Merge remote-tracking branch 'upstream/master' into fix_repeatcmdline

1 files changed, 13388 insertions, 122 deletions

diff --git a/src/nvim/regexp.c b/src/nvim/regexp.c
index 122f3e2020..3536196a3b 100644
--- a/src/nvim/regexp.c
+++ b/src/nvim/regexp.c
@@ -1,6 +1,3 @@
-// This is an open source non-commercial project. Dear PVS-Studio, please check
-// it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
-
 // Handling of regular expressions: vim_regcomp(), vim_regexec(), vim_regsub()
 
 // By default: do not create debugging logs or files related to regular
@@ -10,38 +7,170 @@
 // #define REGEXP_DEBUG
 
 #include <assert.h>
+#include <ctype.h>
 #include <inttypes.h>
+#include <limits.h>
 #include <stdbool.h>
+#include <stddef.h>
 #include <string.h>
 #include <sys/types.h>
 
-#include "nvim/ascii.h"
+#include "nvim/ascii_defs.h"
 #include "nvim/buffer_defs.h"
 #include "nvim/charset.h"
 #include "nvim/eval.h"
 #include "nvim/eval/typval.h"
-#include "nvim/eval/typval_defs.h"
 #include "nvim/eval/userfunc.h"
+#include "nvim/func_attr.h"
 #include "nvim/garray.h"
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
 #include "nvim/keycodes.h"
-#include "nvim/macros.h"
+#include "nvim/macros_defs.h"
 #include "nvim/mark.h"
 #include "nvim/mbyte.h"
 #include "nvim/memline.h"
 #include "nvim/memory.h"
 #include "nvim/message.h"
-#include "nvim/option_defs.h"
+#include "nvim/option_vars.h"
 #include "nvim/os/input.h"
 #include "nvim/plines.h"
-#include "nvim/pos.h"
+#include "nvim/pos_defs.h"
+#include "nvim/profile.h"
 #include "nvim/regexp.h"
 #include "nvim/regexp_defs.h"
 #include "nvim/strings.h"
-#include "nvim/types.h"
-#include "nvim/undo_defs.h"
-#include "nvim/vim.h"
+#include "nvim/types_defs.h"
+#include "nvim/vim_defs.h"
+
+// Structure used to save the current input state, when it needs to be
+// restored after trying a match.  Used by reg_save() and reg_restore().
+// Also stores the length of "backpos".
+typedef struct {
+  union {
+    uint8_t *ptr;       // rex.input pointer, for single-line regexp
+    lpos_T pos;        // rex.input pos, for multi-line regexp
+  } rs_u;
+  int rs_len;
+} regsave_T;
+
+// struct to save start/end pointer/position in for \(\)
+typedef struct {
+  union {
+    uint8_t *ptr;
+    lpos_T pos;
+  } se_u;
+} save_se_T;
+
+// Values for rs_state in regitem_T.
+typedef enum regstate_E {
+  RS_NOPEN = 0,         // NOPEN and NCLOSE
+  RS_MOPEN,             // MOPEN + [0-9]
+  RS_MCLOSE,            // MCLOSE + [0-9]
+  RS_ZOPEN,             // ZOPEN + [0-9]
+  RS_ZCLOSE,            // ZCLOSE + [0-9]
+  RS_BRANCH,            // BRANCH
+  RS_BRCPLX_MORE,       // BRACE_COMPLEX and trying one more match
+  RS_BRCPLX_LONG,       // BRACE_COMPLEX and trying longest match
+  RS_BRCPLX_SHORT,      // BRACE_COMPLEX and trying shortest match
+  RS_NOMATCH,           // NOMATCH
+  RS_BEHIND1,           // BEHIND / NOBEHIND matching rest
+  RS_BEHIND2,           // BEHIND / NOBEHIND matching behind part
+  RS_STAR_LONG,         // STAR/PLUS/BRACE_SIMPLE longest match
+  RS_STAR_SHORT,  // STAR/PLUS/BRACE_SIMPLE shortest match
+} regstate_T;
+
+// When there are alternatives a regstate_T is put on the regstack to remember
+// what we are doing.
+// Before it may be another type of item, depending on rs_state, to remember
+// more things.
+typedef struct regitem_S {
+  regstate_T rs_state;         // what we are doing, one of RS_ above
+  int16_t rs_no;            // submatch nr or BEHIND/NOBEHIND
+  uint8_t *rs_scan;         // current node in program
+  union {
+    save_se_T sesave;
+    regsave_T regsave;
+  } rs_un;                      // room for saving rex.input
+} regitem_T;
+
+// used for BEHIND and NOBEHIND matching
+typedef struct regbehind_S {
+  regsave_T save_after;
+  regsave_T save_behind;
+  int save_need_clear_subexpr;
+  save_se_T save_start[NSUBEXP];
+  save_se_T save_end[NSUBEXP];
+} regbehind_T;
+
+// Since the out pointers in the list are always
+// uninitialized, we use the pointers themselves
+// as storage for the Ptrlists.
+typedef union Ptrlist Ptrlist;
+union Ptrlist {
+  Ptrlist *next;
+  nfa_state_T *s;
+};
+
+struct Frag {
+  nfa_state_T *start;
+  Ptrlist *out;
+};
+typedef struct Frag Frag_T;
+
+typedef struct {
+  int in_use;       ///< number of subexpr with useful info
+
+  // When REG_MULTI is true list.multi is used, otherwise list.line.
+  union {
+    struct multipos {
+      linenr_T start_lnum;
+      linenr_T end_lnum;
+      colnr_T start_col;
+      colnr_T end_col;
+    } multi[NSUBEXP];
+    struct linepos {
+      uint8_t *start;
+      uint8_t *end;
+    } line[NSUBEXP];
+  } list;
+  colnr_T orig_start_col;  // list.multi[0].start_col without \zs
+} regsub_T;
+
+typedef struct {
+  regsub_T norm;      // \( .. \) matches
+  regsub_T synt;      // \z( .. \) matches
+} regsubs_T;
+
+// nfa_pim_T stores a Postponed Invisible Match.
+typedef struct nfa_pim_S nfa_pim_T;
+struct nfa_pim_S {
+  int result;                   // NFA_PIM_*, see below
+  nfa_state_T *state;           // the invisible match start state
+  regsubs_T subs;               // submatch info, only party used
+  union {
+    lpos_T pos;
+    uint8_t *ptr;
+  } end;                        // where the match must end
+};
+
+// nfa_thread_T contains execution information of a NFA state
+typedef struct {
+  nfa_state_T *state;
+  int count;
+  nfa_pim_T pim;                // if pim.result != NFA_PIM_UNUSED: postponed
+                                // invisible match
+  regsubs_T subs;               // submatch info, only party used
+} nfa_thread_T;
+
+// nfa_list_T contains the alternative NFA execution states.
+typedef struct {
+  nfa_thread_T *t;           ///< allocated array of states
+  int n;                        ///< nr of states currently in "t"
+  int len;                      ///< max nr of states in "t"
+  int id;                       ///< ID of the list
+  int has_pim;                  ///< true when any state has a PIM
+} nfa_list_T;
 
 #ifdef REGEXP_DEBUG
 // show/save debugging data when BT engine is used
@@ -59,11 +188,7 @@
 #define un_Magic(x)     ((x) + 256)
 #define is_Magic(x)     ((x) < 0)
 
-// We should define ftpr as a pointer to a function returning a pointer to
-// a function returning a pointer to a function ...
-// This is impossible, so we declare a pointer to a function returning a
-// pointer to a function returning void. This should work for all compilers.
-typedef void (*(*fptr_T)(int *, int))(void);
+typedef void (*fptr_T)(int *, int);
 
 static int no_Magic(int x)
 {
@@ -97,31 +222,41 @@ static int toggle_Magic(int x)
 #define EMSG2_RET_NULL(m, c) \
   return (semsg((m), (c) ? "" : "\\"), rc_did_emsg = true, (void *)NULL)
 #define EMSG3_RET_NULL(m, c, a) \
-  return (semsg((const char *)(m), (c) ? "" : "\\", (a)), rc_did_emsg = true, (void *)NULL)
+  return (semsg((m), (c) ? "" : "\\", (a)), rc_did_emsg = true, (void *)NULL)
 #define EMSG2_RET_FAIL(m, c) \
   return (semsg((m), (c) ? "" : "\\"), rc_did_emsg = true, FAIL)
-#define EMSG_ONE_RET_NULL EMSG2_RET_NULL(_("E369: invalid item in %s%%[]"), reg_magic == MAGIC_ALL)
-
-#define MAX_LIMIT       (32767L << 16L)
-
-static char e_missingbracket[] = N_("E769: Missing ] after %s[");
-static char e_reverse_range[] = N_("E944: Reverse range in character class");
-static char e_large_class[] = N_("E945: Range too large in character class");
-static char e_unmatchedpp[] = N_("E53: Unmatched %s%%(");
-static char e_unmatchedp[] = N_("E54: Unmatched %s(");
-static char e_unmatchedpar[] = N_("E55: Unmatched %s)");
-static char e_z_not_allowed[] = N_("E66: \\z( not allowed here");
-static char e_z1_not_allowed[] = N_("E67: \\z1 - \\z9 not allowed here");
-static char e_missing_sb[] = N_("E69: Missing ] after %s%%[");
-static char e_empty_sb[] = N_("E70: Empty %s%%[]");
-static char e_recursive[] = N_("E956: Cannot use pattern recursively");
-static char e_regexp_number_after_dot_pos_search_chr[]
+#define EMSG_ONE_RET_NULL EMSG2_RET_NULL(_(e_invalid_item_in_str_brackets), reg_magic == MAGIC_ALL)
+
+#define MAX_LIMIT       (32767 << 16)
+
+static const char e_invalid_character_after_str_at[]
+  = N_("E59: Invalid character after %s@");
+static const char e_invalid_use_of_underscore[]
+  = N_("E63: Invalid use of \\_");
+static const char e_pattern_uses_more_memory_than_maxmempattern[]
+  = N_("E363: Pattern uses more memory than 'maxmempattern'");
+static const char e_invalid_item_in_str_brackets[]
+  = N_("E369: Invalid item in %s%%[]");
+static const char e_missing_delimiter_after_search_pattern_str[]
+  = N_("E654: Missing delimiter after search pattern: %s");
+static const char e_missingbracket[] = N_("E769: Missing ] after %s[");
+static const char e_reverse_range[] = N_("E944: Reverse range in character class");
+static const char e_large_class[] = N_("E945: Range too large in character class");
+static const char e_unmatchedpp[] = N_("E53: Unmatched %s%%(");
+static const char e_unmatchedp[] = N_("E54: Unmatched %s(");
+static const char e_unmatchedpar[] = N_("E55: Unmatched %s)");
+static const char e_z_not_allowed[] = N_("E66: \\z( not allowed here");
+static const char e_z1_not_allowed[] = N_("E67: \\z1 - \\z9 not allowed here");
+static const char e_missing_sb[] = N_("E69: Missing ] after %s%%[");
+static const char e_empty_sb[] = N_("E70: Empty %s%%[]");
+static const char e_recursive[] = N_("E956: Cannot use pattern recursively");
+static const char e_regexp_number_after_dot_pos_search_chr[]
   = N_("E1204: No Number allowed after .: '\\%%%c'");
-static char e_nfa_regexp_missing_value_in_chr[]
+static const char e_nfa_regexp_missing_value_in_chr[]
   = N_("E1273: (NFA regexp) missing value in '\\%%%c'");
-static char e_atom_engine_must_be_at_start_of_pattern[]
+static const char e_atom_engine_must_be_at_start_of_pattern[]
   = N_("E1281: Atom '\\%%#=%c' must be at the start of the pattern");
-static char e_substitute_nesting_too_deep[] = N_("E1290: substitute nesting too deep");
+static const char e_substitute_nesting_too_deep[] = N_("E1290: substitute nesting too deep");
 
 #define NOT_MULTI       0
 #define MULTI_ONE       1
@@ -491,7 +626,7 @@ char *skip_regexp_err(char *startp, int delim, int magic)
   char *p = skip_regexp(startp, delim, magic);
 
   if (*p != delim) {
-    semsg(_("E654: missing delimiter after search pattern: %s"), startp);
+    semsg(_(e_missing_delimiter_after_search_pattern_str), startp);
     return NULL;
   }
   return p;
@@ -869,7 +1004,7 @@ static int64_t getoctchrs(void)
   int c;
   int i;
 
-  for (i = 0; i < 3 && nr < 040; i++) {  // -V536
+  for (i = 0; i < 3 && nr < 040; i++) {
     c = (uint8_t)regparse[0];
     if (c < '0' || c > '7') {
       break;
@@ -889,11 +1024,11 @@ static int64_t getoctchrs(void)
 // If the first character is '-', then the range is reversed.
 // Should end with 'end'.  If minval is missing, zero is default, if maxval is
 // missing, a very big number is the default.
-static int read_limits(long *minval, long *maxval)
+static int read_limits(int *minval, int *maxval)
 {
   int reverse = false;
   char *first_char;
-  long tmp;
+  int tmp;
 
   if (*regparse == '-') {
     // Starts with '-', so reverse the range later.
@@ -901,10 +1036,10 @@ static int read_limits(long *minval, long *maxval)
     reverse = true;
   }
   first_char = regparse;
-  *minval = getdigits_long(&regparse, false, 0);
+  *minval = getdigits_int(&regparse, false, 0);
   if (*regparse == ',') {           // There is a comma.
     if (ascii_isdigit(*++regparse)) {
-      *maxval = getdigits_long(&regparse, false, MAX_LIMIT);
+      *maxval = getdigits_int(&regparse, false, MAX_LIMIT);
     } else {
       *maxval = MAX_LIMIT;
     }
@@ -989,6 +1124,8 @@ typedef struct {
   // flag in the regexp.  Defaults to false, always.
   bool reg_icombine;
 
+  bool reg_nobreak;
+
   // Copy of "rmm_maxcol": maximum column to search for a match.  Zero when
   // there is no maximum.
   colnr_T reg_maxcol;
@@ -1011,6 +1148,13 @@ typedef struct {
 static regexec_T rex;
 static bool rex_in_use = false;
 
+static void reg_breakcheck(void)
+{
+  if (!rex.reg_nobreak) {
+    fast_breakcheck();
+  }
+}
+
 // Return true if character 'c' is included in 'iskeyword' option for
 // "reg_buf" buffer.
 static bool reg_iswordc(int c)
@@ -1030,7 +1174,7 @@ static char *reg_getline(linenr_T lnum)
     // Must have matched the "\n" in the last line.
     return "";
   }
-  return ml_get_buf(rex.reg_buf, rex.reg_firstlnum + lnum, false);
+  return ml_get_buf(rex.reg_buf, rex.reg_firstlnum + lnum);
 }
 
 static uint8_t *reg_startzp[NSUBEXP];  // Workspace to mark beginning
@@ -1150,9 +1294,7 @@ static bool reg_match_visual(void)
     rex.line = (uint8_t *)reg_getline(rex.lnum);
     rex.input = rex.line + col;
 
-    unsigned int cols_u = win_linetabsize(wp, rex.reg_firstlnum + rex.lnum, (char *)rex.line, col);
-    assert(cols_u <= MAXCOL);
-    colnr_T cols = (colnr_T)cols_u;
+    colnr_T cols = win_linetabsize(wp, rex.reg_firstlnum + rex.lnum, (char *)rex.line, col);
     if (cols < start || cols > end - (*p_sel == 'e')) {
       return false;
     }
@@ -1221,7 +1363,7 @@ static void reg_nextline(void)
 {
   rex.line = (uint8_t *)reg_getline(++rex.lnum);
   rex.input = rex.line;
-  fast_breakcheck();
+  reg_breakcheck();
 }
 
 // Check whether a backreference matches.
@@ -1239,7 +1381,7 @@ static int match_with_backref(linenr_T start_lnum, colnr_T start_col, linenr_T e
   if (bytelen != NULL) {
     *bytelen = 0;
   }
-  for (;;) {
+  while (true) {
     // Since getting one line may invalidate the other, need to make copy.
     // Slow!
     if (rex.line != reg_tofree) {
@@ -1393,7 +1535,7 @@ static int cstrncmp(char *s1, char *s2, int *n)
 
   // if it failed and it's utf8 and we want to combineignore:
   if (result != 0 && rex.reg_icombine) {
-    char *str1, *str2;
+    const char *str1, *str2;
     int c1, c2, c11, c12;
     int junk;
 
@@ -1403,8 +1545,8 @@ static int cstrncmp(char *s1, char *s2, int *n)
     str2 = s2;
     c1 = c2 = 0;
     while ((int)(str1 - s1) < *n) {
-      c1 = mb_ptr2char_adv((const char **)&str1);
-      c2 = mb_ptr2char_adv((const char **)&str2);
+      c1 = mb_ptr2char_adv(&str1);
+      c2 = mb_ptr2char_adv(&str2);
 
       // decompose the character if necessary, into 'base' characters
       // because I don't care about Arabic, I will hard-code the Hebrew
@@ -1475,34 +1617,14 @@ static inline char *cstrchr(const char *const s, const int c)
 //                    regsub stuff                            //
 ////////////////////////////////////////////////////////////////
 
-// This stuff below really confuses cc on an SGI -- webb
-
-static fptr_T do_upper(int *d, int c)
-{
-  *d = mb_toupper(c);
-
-  return (fptr_T)NULL;
-}
-
-static fptr_T do_Upper(int *d, int c)
+static void do_upper(int *d, int c)
 {
   *d = mb_toupper(c);
-
-  return (fptr_T)do_Upper;
-}
-
-static fptr_T do_lower(int *d, int c)
-{
-  *d = mb_tolower(c);
-
-  return (fptr_T)NULL;
 }
 
-static fptr_T do_Lower(int *d, int c)
+static void do_lower(int *d, int c)
 {
   *d = mb_tolower(c);
-
-  return (fptr_T)do_Lower;
 }
 
 /// regtilde(): Replace tildes in the pattern by the old pattern.
@@ -1518,41 +1640,46 @@ static fptr_T do_Lower(int *d, int c)
 char *regtilde(char *source, int magic, bool preview)
 {
   char *newsub = source;
-  char *tmpsub;
-  char *p;
-  int len;
-  int prevlen;
 
-  for (p = newsub; *p; p++) {
+  for (char *p = newsub; *p; p++) {
     if ((*p == '~' && magic) || (*p == '\\' && *(p + 1) == '~' && !magic)) {
       if (reg_prev_sub != NULL) {
         // length = len(newsub) - 1 + len(prev_sub) + 1
-        prevlen = (int)strlen(reg_prev_sub);
-        tmpsub = xmalloc(strlen(newsub) + (size_t)prevlen);
+        // Avoid making the text longer than MAXCOL, it will cause
+        // trouble at some point.
+        size_t prevsublen = strlen(reg_prev_sub);
+        size_t newsublen = strlen(newsub);
+        if (prevsublen > MAXCOL || newsublen > MAXCOL
+            || newsublen + prevsublen > MAXCOL) {
+          emsg(_(e_resulting_text_too_long));
+          break;
+        }
+
+        char *tmpsub = xmalloc(newsublen + prevsublen);
         // copy prefix
-        len = (int)(p - newsub);              // not including ~
-        memmove(tmpsub, newsub, (size_t)len);
+        size_t prefixlen = (size_t)(p - newsub);  // not including ~
+        memmove(tmpsub, newsub, prefixlen);
         // interpret tilde
-        memmove(tmpsub + len, reg_prev_sub, (size_t)prevlen);
+        memmove(tmpsub + prefixlen, reg_prev_sub, prevsublen);
         // copy postfix
         if (!magic) {
-          p++;                                // back off backslash
+          p++;  // back off backslash
         }
-        STRCPY(tmpsub + len + prevlen, p + 1);
+        STRCPY(tmpsub + prefixlen + prevsublen, p + 1);
 
-        if (newsub != source) {               // already allocated newsub
+        if (newsub != source) {  // allocated newsub before
           xfree(newsub);
         }
         newsub = tmpsub;
-        p = newsub + len + prevlen;
+        p = newsub + prefixlen + prevsublen;
       } else if (magic) {
-        STRMOVE(p, p + 1);              // remove '~'
+        STRMOVE(p, p + 1);  // remove '~'
       } else {
-        STRMOVE(p, p + 2);              // remove '\~'
+        STRMOVE(p, p + 2);  // remove '\~'
       }
       p--;
     } else {
-      if (*p == '\\' && p[1]) {         // skip escaped characters
+      if (*p == '\\' && p[1]) {  // skip escaped characters
         p++;
       }
       p += utfc_ptr2len(p) - 1;
@@ -1746,9 +1873,10 @@ static int vim_regsub_both(char *source, typval_T *expr, char *dest, int destlen
     // "flags & REGSUB_COPY" == 0 to the call with
     // "flags & REGSUB_COPY" != 0.
     if (copy) {
-      if (eval_result[nested] != NULL) {
+      size_t reslen = eval_result[nested] != NULL ? strlen(eval_result[nested]) : 0;
+      if (eval_result[nested] != NULL && reslen < (size_t)destlen) {
         STRCPY(dest, eval_result[nested]);
-        dst += strlen(eval_result[nested]);
+        dst += reslen;
         XFREE_CLEAR(eval_result[nested]);
       }
     } else {
@@ -1812,7 +1940,7 @@ static int vim_regsub_both(char *source, typval_T *expr, char *dest, int destlen
         }
         tv_clear(&rettv);
       } else {
-        eval_result[nested] = eval_to_string(source + 2, NULL, true);
+        eval_result[nested] = eval_to_string(source + 2, true);
       }
       nesting--;
 
@@ -1866,16 +1994,16 @@ static int vim_regsub_both(char *source, typval_T *expr, char *dest, int destlen
         } else if (vim_strchr("uUlLeE", (uint8_t)(*src))) {
           switch (*src++) {
           case 'u':
-            func_one = (fptr_T)do_upper;
+            func_one = do_upper;
             continue;
           case 'U':
-            func_all = (fptr_T)do_Upper;
+            func_all = do_upper;
             continue;
           case 'l':
-            func_one = (fptr_T)do_lower;
+            func_one = do_lower;
             continue;
           case 'L':
-            func_all = (fptr_T)do_Lower;
+            func_all = do_lower;
             continue;
           case 'e':
           case 'E':
@@ -1934,11 +2062,13 @@ static int vim_regsub_both(char *source, typval_T *expr, char *dest, int destlen
         } else {
           c = utf_ptr2char(src - 1);
         }
+
         // Write to buffer, if copy is set.
         if (func_one != NULL) {
-          func_one = (fptr_T)(func_one(&cc, c));
+          func_one(&cc, c);
+          func_one = NULL;
         } else if (func_all != NULL) {
-          func_all = (fptr_T)(func_all(&cc, c));
+          func_all(&cc, c);
         } else {
           // just copy
           cc = c;
@@ -1994,7 +2124,7 @@ static int vim_regsub_both(char *source, typval_T *expr, char *dest, int destlen
           }
         }
         if (s != NULL) {
-          for (;;) {
+          while (true) {
             if (len == 0) {
               if (REG_MULTI) {
                 if (rex.reg_mmatch->endpos[no].lnum == clnum) {
@@ -2041,11 +2171,10 @@ static int vim_regsub_both(char *source, typval_T *expr, char *dest, int destlen
                 c = utf_ptr2char(s);
 
                 if (func_one != (fptr_T)NULL) {
-                  // Turbo C complains without the typecast
-                  func_one = (fptr_T)(func_one(&cc, c));
+                  func_one(&cc, c);
+                  func_one = NULL;
                 } else if (func_all != (fptr_T)NULL) {
-                  // Turbo C complains without the typecast
-                  func_all = (fptr_T)(func_all(&cc, c));
+                  func_all(&cc, c);
                 } else {  // just copy
                   cc = c;
                 }
@@ -2175,7 +2304,7 @@ char *reg_submatch(int no)
         }
         len += rsm.sm_mmatch->endpos[no].col;
         if (round == 2) {
-          retval[len] = NUL;  // -V595
+          retval[len] = NUL;
         }
         len++;
       }
@@ -2237,12 +2366,12 @@ list_T *reg_submatch_list(int no)
       tv_list_append_string(list, s, ecol);
     }
   } else {
-    s = (const char *)rsm.sm_match->startp[no];
+    s = rsm.sm_match->startp[no];
     if (s == NULL || rsm.sm_match->endp[no] == NULL) {
       return NULL;
     }
     list = tv_list_alloc(1);
-    tv_list_append_string(list, s, (const char *)rsm.sm_match->endp[no] - s);
+    tv_list_append_string(list, s, rsm.sm_match->endp[no] - s);
   }
 
   tv_list_ref(list);
@@ -2265,14 +2394,13151 @@ static void init_regexec_multi(regmmatch_T *rmp, win_T *win, buf_T *buf, linenr_
   rex.reg_line_lbr = false;
   rex.reg_ic = rmp->rmm_ic;
   rex.reg_icombine = false;
+  rex.reg_nobreak = rmp->regprog->re_flags & RE_NOBREAK;
   rex.reg_maxcol = rmp->rmm_maxcol;
 }
 
-// XXX Do not allow headers generator to catch definitions from regexp_nfa.c
-#ifndef DO_NOT_DEFINE_EMPTY_ATTRIBUTES
-# include "nvim/regexp_bt.c"
-# include "nvim/regexp_nfa.c"
+// regexp_bt.c {{{1
+
+// Backtracking regular expression implementation.
+//
+// NOTICE:
+//
+// This is NOT the original regular expression code as written by Henry
+// Spencer.  This code has been modified specifically for use with the VIM
+// editor, and should not be used separately from Vim.  If you want a good
+// regular expression library, get the original code.  The copyright notice
+// that follows is from the original.
+//
+// END NOTICE
+//
+//      Copyright (c) 1986 by University of Toronto.
+//      Written by Henry Spencer.  Not derived from licensed software.
+//
+//      Permission is granted to anyone to use this software for any
+//      purpose on any computer system, and to redistribute it freely,
+//      subject to the following restrictions:
+//
+//      1. The author is not responsible for the consequences of use of
+//              this software, no matter how awful, even if they arise
+//              from defects in it.
+//
+//      2. The origin of this software must not be misrepresented, either
+//              by explicit claim or by omission.
+//
+//      3. Altered versions must be plainly marked as such, and must not
+//              be misrepresented as being the original software.
+//
+// Beware that some of this code is subtly aware of the way operator
+// precedence is structured in regular expressions.  Serious changes in
+// regular-expression syntax might require a total rethink.
+//
+// Changes have been made by Tony Andrews, Olaf 'Rhialto' Seibert, Robert
+// Webb, Ciaran McCreesh and Bram Moolenaar.
+// Named character class support added by Walter Briscoe (1998 Jul 01)
+
+// The "internal use only" fields in regexp_defs.h are present to pass info from
+// compile to execute that permits the execute phase to run lots faster on
+// simple cases.  They are:
+//
+// regstart     char that must begin a match; NUL if none obvious; Can be a
+//              multi-byte character.
+// reganch      is the match anchored (at beginning-of-line only)?
+// regmust      string (pointer into program) that match must include, or NULL
+// regmlen      length of regmust string
+// regflags     RF_ values or'ed together
+//
+// Regstart and reganch permit very fast decisions on suitable starting points
+// for a match, cutting down the work a lot.  Regmust permits fast rejection
+// of lines that cannot possibly match.  The regmust tests are costly enough
+// that vim_regcomp() supplies a regmust only if the r.e. contains something
+// potentially expensive (at present, the only such thing detected is * or +
+// at the start of the r.e., which can involve a lot of backup).  Regmlen is
+// supplied because the test in vim_regexec() needs it and vim_regcomp() is
+// computing it anyway.
+
+// Structure for regexp "program".  This is essentially a linear encoding
+// of a nondeterministic finite-state machine (aka syntax charts or
+// "railroad normal form" in parsing technology).  Each node is an opcode
+// plus a "next" pointer, possibly plus an operand.  "Next" pointers of
+// all nodes except BRANCH and BRACES_COMPLEX implement concatenation; a "next"
+// pointer with a BRANCH on both ends of it is connecting two alternatives.
+// (Here we have one of the subtle syntax dependencies: an individual BRANCH
+// (as opposed to a collection of them) is never concatenated with anything
+// because of operator precedence).  The "next" pointer of a BRACES_COMPLEX
+// node points to the node after the stuff to be repeated.
+// The operand of some types of node is a literal string; for others, it is a
+// node leading into a sub-FSM.  In particular, the operand of a BRANCH node
+// is the first node of the branch.
+// (NB this is *not* a tree structure: the tail of the branch connects to the
+// thing following the set of BRANCHes.)
+//
+// pattern      is coded like:
+//
+//                        +-----------------+
+//                        |                 V
+// <aa>\|<bb>   BRANCH <aa> BRANCH <bb> --> END
+//                   |      ^    |          ^
+//                   +------+    +----------+
+//
+//
+//                     +------------------+
+//                     V                  |
+// <aa>*        BRANCH BRANCH <aa> --> BACK BRANCH --> NOTHING --> END
+//                   |      |               ^                      ^
+//                   |      +---------------+                      |
+//                   +---------------------------------------------+
+//
+//
+//                     +----------------------+
+//                     V                      |
+// <aa>\+       BRANCH <aa> --> BRANCH --> BACK  BRANCH --> NOTHING --> END
+//                   |               |           ^                      ^
+//                   |               +-----------+                      |
+//                   +--------------------------------------------------+
+//
+//
+//                                      +-------------------------+
+//                                      V                         |
+// <aa>\{}      BRANCH BRACE_LIMITS --> BRACE_COMPLEX <aa> --> BACK  END
+//                   |                              |                ^
+//                   |                              +----------------+
+//                   +-----------------------------------------------+
+//
+//
+// <aa>\@!<bb>  BRANCH NOMATCH <aa> --> END  <bb> --> END
+//                   |       |                ^       ^
+//                   |       +----------------+       |
+//                   +--------------------------------+
+//
+//                                                    +---------+
+//                                                    |         V
+// \z[abc]      BRANCH BRANCH  a  BRANCH  b  BRANCH  c  BRANCH  NOTHING --> END
+//                   |      |          |          |     ^                   ^
+//                   |      |          |          +-----+                   |
+//                   |      |          +----------------+                   |
+//                   |      +---------------------------+                   |
+//                   +------------------------------------------------------+
+//
+// They all start with a BRANCH for "\|" alternatives, even when there is only
+// one alternative.
+
+// The opcodes are:
+
+// definition   number             opnd?    meaning
+#define END             0       //      End of program or NOMATCH operand.
+#define BOL             1       //      Match "" at beginning of line.
+#define EOL             2       //      Match "" at end of line.
+#define BRANCH          3       // node Match this alternative, or the
+                                //      next...
+#define BACK            4       //      Match "", "next" ptr points backward.
+#define EXACTLY         5       // str  Match this string.
+#define NOTHING         6       //      Match empty string.
+#define STAR            7       // node Match this (simple) thing 0 or more
+                                //      times.
+#define PLUS            8       // node Match this (simple) thing 1 or more
+                                //      times.
+#define MATCH           9       // node match the operand zero-width
+#define NOMATCH         10      // node check for no match with operand
+#define BEHIND          11      // node look behind for a match with operand
+#define NOBEHIND        12      // node look behind for no match with operand
+#define SUBPAT          13      // node match the operand here
+#define BRACE_SIMPLE    14      // node Match this (simple) thing between m and
+                                //      n times (\{m,n\}).
+#define BOW             15      //      Match "" after [^a-zA-Z0-9_]
+#define EOW             16      //      Match "" at    [^a-zA-Z0-9_]
+#define BRACE_LIMITS    17      // nr nr  define the min & max for BRACE_SIMPLE
+                                //      and BRACE_COMPLEX.
+#define NEWL            18      //      Match line-break
+#define BHPOS           19      //      End position for BEHIND or NOBEHIND
+
+// character classes: 20-48 normal, 50-78 include a line-break
+#define ADD_NL          30
+#define FIRST_NL        ANY + ADD_NL
+#define ANY             20      //      Match any one character.
+#define ANYOF           21      // str  Match any character in this string.
+#define ANYBUT          22      // str  Match any character not in this
+                                //      string.
+#define IDENT           23      //      Match identifier char
+#define SIDENT          24      //      Match identifier char but no digit
+#define KWORD           25      //      Match keyword char
+#define SKWORD          26      //      Match word char but no digit
+#define FNAME           27      //      Match file name char
+#define SFNAME          28      //      Match file name char but no digit
+#define PRINT           29      //      Match printable char
+#define SPRINT          30      //      Match printable char but no digit
+#define WHITE           31      //      Match whitespace char
+#define NWHITE          32      //      Match non-whitespace char
+#define DIGIT           33      //      Match digit char
+#define NDIGIT          34      //      Match non-digit char
+#define HEX             35      //      Match hex char
+#define NHEX            36      //      Match non-hex char
+#define OCTAL           37      //      Match octal char
+#define NOCTAL          38      //      Match non-octal char
+#define WORD            39      //      Match word char
+#define NWORD           40      //      Match non-word char
+#define HEAD            41      //      Match head char
+#define NHEAD           42      //      Match non-head char
+#define ALPHA           43      //      Match alpha char
+#define NALPHA          44      //      Match non-alpha char
+#define LOWER           45      //      Match lowercase char
+#define NLOWER          46      //      Match non-lowercase char
+#define UPPER           47      //      Match uppercase char
+#define NUPPER          48      //      Match non-uppercase char
+#define LAST_NL         NUPPER + ADD_NL
+#define WITH_NL(op)     ((op) >= FIRST_NL && (op) <= LAST_NL)
+
+#define MOPEN           80   // -89 Mark this point in input as start of
+                             //     \( … \) subexpr.  MOPEN + 0 marks start of
+                             //     match.
+#define MCLOSE          90   // -99 Analogous to MOPEN.  MCLOSE + 0 marks
+                             //     end of match.
+#define BACKREF         100  // -109 node Match same string again \1-\9.
+
+#define ZOPEN          110  // -119 Mark this point in input as start of
+                            //  \z( … \) subexpr.
+#define ZCLOSE         120  // -129 Analogous to ZOPEN.
+#define ZREF           130  // -139 node Match external submatch \z1-\z9
+
+#define BRACE_COMPLEX   140  // -149 node Match nodes between m & n times
+
+#define NOPEN           150     // Mark this point in input as start of
+                                // \%( subexpr.
+#define NCLOSE          151     // Analogous to NOPEN.
+
+#define MULTIBYTECODE   200     // mbc  Match one multi-byte character
+#define RE_BOF          201     //      Match "" at beginning of file.
+#define RE_EOF          202     //      Match "" at end of file.
+#define CURSOR          203     //      Match location of cursor.
+
+#define RE_LNUM         204     // nr cmp  Match line number
+#define RE_COL          205     // nr cmp  Match column number
+#define RE_VCOL         206     // nr cmp  Match virtual column number
+
+#define RE_MARK         207     // mark cmp  Match mark position
+#define RE_VISUAL       208     //      Match Visual area
+#define RE_COMPOSING    209     // any composing characters
+
+// Flags to be passed up and down.
+#define HASWIDTH        0x1     // Known never to match null string.
+#define SIMPLE          0x2     // Simple enough to be STAR/PLUS operand.
+#define SPSTART         0x4     // Starts with * or +.
+#define HASNL           0x8     // Contains some \n.
+#define HASLOOKBH       0x10    // Contains "\@<=" or "\@<!".
+#define WORST           0       // Worst case.
+
+static int prevchr_len;         ///< byte length of previous char
+static int num_complex_braces;  ///< Complex \{...} count
+static uint8_t *regcode;         ///< Code-emit pointer, or JUST_CALC_SIZE
+static int64_t regsize;            ///< Code size.
+static int reg_toolong;         ///< true when offset out of range
+static uint8_t had_endbrace[NSUBEXP];  ///< flags, true if end of () found
+static int64_t brace_min[10];        ///< Minimums for complex brace repeats
+static int64_t brace_max[10];        ///< Maximums for complex brace repeats
+static int brace_count[10];       ///< Current counts for complex brace repeats
+static int one_exactly = false;   ///< only do one char for EXACTLY
+
+// When making changes to classchars also change nfa_classcodes.
+static uint8_t *classchars = (uint8_t *)".iIkKfFpPsSdDxXoOwWhHaAlLuU";
+static int classcodes[] = {
+  ANY, IDENT, SIDENT, KWORD, SKWORD,
+  FNAME, SFNAME, PRINT, SPRINT,
+  WHITE, NWHITE, DIGIT, NDIGIT,
+  HEX, NHEX, OCTAL, NOCTAL,
+  WORD, NWORD, HEAD, NHEAD,
+  ALPHA, NALPHA, LOWER, NLOWER,
+  UPPER, NUPPER
+};
+
+// When regcode is set to this value, code is not emitted and size is computed
+// instead.
+#define JUST_CALC_SIZE  ((uint8_t *)-1)
+
+// used for STAR, PLUS and BRACE_SIMPLE matching
+typedef struct regstar_S {
+  int nextb;            // next byte
+  int nextb_ic;         // next byte reverse case
+  int64_t count;
+  int64_t minval;
+  int64_t maxval;
+} regstar_T;
+
+// used to store input position when a BACK was encountered, so that we now if
+// we made any progress since the last time.
+typedef struct backpos_S {
+  uint8_t *bp_scan;         // "scan" where BACK was encountered
+  regsave_T bp_pos;           // last input position
+} backpos_T;
+
+// "regstack" and "backpos" are used by regmatch().  They are kept over calls
+// to avoid invoking malloc() and free() often.
+// "regstack" is a stack with regitem_T items, sometimes preceded by regstar_T
+// or regbehind_T.
+// "backpos_T" is a table with backpos_T for BACK
+static garray_T regstack = GA_EMPTY_INIT_VALUE;
+static garray_T backpos = GA_EMPTY_INIT_VALUE;
+
+static regsave_T behind_pos;
+
+// Both for regstack and backpos tables we use the following strategy of
+// allocation (to reduce malloc/free calls):
+// - Initial size is fairly small.
+// - When needed, the tables are grown bigger (8 times at first, double after
+//   that).
+// - After executing the match we free the memory only if the array has grown.
+//   Thus the memory is kept allocated when it's at the initial size.
+// This makes it fast while not keeping a lot of memory allocated.
+// A three times speed increase was observed when using many simple patterns.
+#define REGSTACK_INITIAL        2048
+#define BACKPOS_INITIAL         64
+
+// Opcode notes:
+//
+// BRANCH       The set of branches constituting a single choice are hooked
+//              together with their "next" pointers, since precedence prevents
+//              anything being concatenated to any individual branch.  The
+//              "next" pointer of the last BRANCH in a choice points to the
+//              thing following the whole choice.  This is also where the
+//              final "next" pointer of each individual branch points; each
+//              branch starts with the operand node of a BRANCH node.
+//
+// BACK         Normal "next" pointers all implicitly point forward; BACK
+//              exists to make loop structures possible.
+//
+// STAR,PLUS    '=', and complex '*' and '+', are implemented as circular
+//              BRANCH structures using BACK.  Simple cases (one character
+//              per match) are implemented with STAR and PLUS for speed
+//              and to minimize recursive plunges.
+//
+// BRACE_LIMITS This is always followed by a BRACE_SIMPLE or BRACE_COMPLEX
+//              node, and defines the min and max limits to be used for that
+//              node.
+//
+// MOPEN,MCLOSE ...are numbered at compile time.
+// ZOPEN,ZCLOSE ...ditto
+///
+//
+//
+// A node is one char of opcode followed by two chars of "next" pointer.
+// "Next" pointers are stored as two 8-bit bytes, high order first.  The
+// value is a positive offset from the opcode of the node containing it.
+// An operand, if any, simply follows the node.  (Note that much of the
+// code generation knows about this implicit relationship.)
+//
+// Using two bytes for the "next" pointer is vast overkill for most things,
+// but allows patterns to get big without disasters.
+#define OP(p)           ((int)(*(p)))
+#define NEXT(p)         (((*((p) + 1) & 0377) << 8) + (*((p) + 2) & 0377))
+#define OPERAND(p)      ((p) + 3)
+// Obtain an operand that was stored as four bytes, MSB first.
+#define OPERAND_MIN(p)  (((int64_t)(p)[3] << 24) + ((int64_t)(p)[4] << 16) \
+                         + ((int64_t)(p)[5] << 8) + (int64_t)(p)[6])
+// Obtain a second operand stored as four bytes.
+#define OPERAND_MAX(p)  OPERAND_MIN((p) + 4)
+// Obtain a second single-byte operand stored after a four bytes operand.
+#define OPERAND_CMP(p)  (p)[7]
+
+static uint8_t *reg(int paren, int *flagp);
+
+#ifdef BT_REGEXP_DUMP
+static void     regdump(uint8_t *, bt_regprog_T *);
+#endif
+
+#ifdef REGEXP_DEBUG
+static uint8_t *regprop(uint8_t *);
+
+static int regnarrate = 0;
+#endif
+
+// Setup to parse the regexp.  Used once to get the length and once to do it.
+static void regcomp_start(uint8_t *expr, int re_flags)                        // see vim_regcomp()
+{
+  initchr((char *)expr);
+  if (re_flags & RE_MAGIC) {
+    reg_magic = MAGIC_ON;
+  } else {
+    reg_magic = MAGIC_OFF;
+  }
+  reg_string = (re_flags & RE_STRING);
+  reg_strict = (re_flags & RE_STRICT);
+  get_cpo_flags();
+
+  num_complex_braces = 0;
+  regnpar = 1;
+  CLEAR_FIELD(had_endbrace);
+  regnzpar = 1;
+  re_has_z = 0;
+  regsize = 0L;
+  reg_toolong = false;
+  regflags = 0;
+  had_eol = false;
+}
+
+// Return true if MULTIBYTECODE should be used instead of EXACTLY for
+// character "c".
+static bool use_multibytecode(int c)
+{
+  return utf_char2len(c) > 1
+         && (re_multi_type(peekchr()) != NOT_MULTI
+             || utf_iscomposing(c));
+}
+
+// Emit (if appropriate) a byte of code
+static void regc(int b)
+{
+  if (regcode == JUST_CALC_SIZE) {
+    regsize++;
+  } else {
+    *regcode++ = (uint8_t)b;
+  }
+}
+
+// Emit (if appropriate) a multi-byte character of code
+static void regmbc(int c)
+{
+  if (regcode == JUST_CALC_SIZE) {
+    regsize += utf_char2len(c);
+  } else {
+    regcode += utf_char2bytes(c, (char *)regcode);
+  }
+}
+
+// Produce the bytes for equivalence class "c".
+// Currently only handles latin1, latin9 and utf-8.
+// NOTE: When changing this function, also change nfa_emit_equi_class()
+static void reg_equi_class(int c)
+{
+  {
+    switch (c) {
+    // Do not use '\300' style, it results in a negative number.
+    case 'A':
+    case 0xc0:
+    case 0xc1:
+    case 0xc2:
+    case 0xc3:
+    case 0xc4:
+    case 0xc5:
+    case 0x100:
+    case 0x102:
+    case 0x104:
+    case 0x1cd:
+    case 0x1de:
+    case 0x1e0:
+    case 0x1fa:
+    case 0x202:
+    case 0x226:
+    case 0x23a:
+    case 0x1e00:
+    case 0x1ea0:
+    case 0x1ea2:
+    case 0x1ea4:
+    case 0x1ea6:
+    case 0x1ea8:
+    case 0x1eaa:
+    case 0x1eac:
+    case 0x1eae:
+    case 0x1eb0:
+    case 0x1eb2:
+    case 0x1eb4:
+    case 0x1eb6:
+      regmbc('A'); regmbc(0xc0); regmbc(0xc1); regmbc(0xc2);
+      regmbc(0xc3); regmbc(0xc4); regmbc(0xc5);
+      regmbc(0x100); regmbc(0x102); regmbc(0x104);
+      regmbc(0x1cd); regmbc(0x1de); regmbc(0x1e0);
+      regmbc(0x1fa); regmbc(0x202); regmbc(0x226);
+      regmbc(0x23a); regmbc(0x1e00); regmbc(0x1ea0);
+      regmbc(0x1ea2); regmbc(0x1ea4); regmbc(0x1ea6);
+      regmbc(0x1ea8); regmbc(0x1eaa); regmbc(0x1eac);
+      regmbc(0x1eae); regmbc(0x1eb0); regmbc(0x1eb2);
+      regmbc(0x1eb4); regmbc(0x1eb6);
+      return;
+    case 'B':
+    case 0x181:
+    case 0x243:
+    case 0x1e02:
+    case 0x1e04:
+    case 0x1e06:
+      regmbc('B');
+      regmbc(0x181); regmbc(0x243); regmbc(0x1e02);
+      regmbc(0x1e04); regmbc(0x1e06);
+      return;
+    case 'C':
+    case 0xc7:
+    case 0x106:
+    case 0x108:
+    case 0x10a:
+    case 0x10c:
+    case 0x187:
+    case 0x23b:
+    case 0x1e08:
+    case 0xa792:
+      regmbc('C'); regmbc(0xc7);
+      regmbc(0x106); regmbc(0x108); regmbc(0x10a);
+      regmbc(0x10c); regmbc(0x187); regmbc(0x23b);
+      regmbc(0x1e08); regmbc(0xa792);
+      return;
+    case 'D':
+    case 0x10e:
+    case 0x110:
+    case 0x18a:
+    case 0x1e0a:
+    case 0x1e0c:
+    case 0x1e0e:
+    case 0x1e10:
+    case 0x1e12:
+      regmbc('D'); regmbc(0x10e); regmbc(0x110);
+      regmbc(0x18a); regmbc(0x1e0a); regmbc(0x1e0c);
+      regmbc(0x1e0e); regmbc(0x1e10); regmbc(0x1e12);
+      return;
+    case 'E':
+    case 0xc8:
+    case 0xc9:
+    case 0xca:
+    case 0xcb:
+    case 0x112:
+    case 0x114:
+    case 0x116:
+    case 0x118:
+    case 0x11a:
+    case 0x204:
+    case 0x206:
+    case 0x228:
+    case 0x246:
+    case 0x1e14:
+    case 0x1e16:
+    case 0x1e18:
+    case 0x1e1a:
+    case 0x1e1c:
+    case 0x1eb8:
+    case 0x1eba:
+    case 0x1ebc:
+    case 0x1ebe:
+    case 0x1ec0:
+    case 0x1ec2:
+    case 0x1ec4:
+    case 0x1ec6:
+      regmbc('E'); regmbc(0xc8); regmbc(0xc9);
+      regmbc(0xca); regmbc(0xcb); regmbc(0x112);
+      regmbc(0x114); regmbc(0x116); regmbc(0x118);
+      regmbc(0x11a); regmbc(0x204); regmbc(0x206);
+      regmbc(0x228); regmbc(0x246); regmbc(0x1e14);
+      regmbc(0x1e16); regmbc(0x1e18); regmbc(0x1e1a);
+      regmbc(0x1e1c); regmbc(0x1eb8); regmbc(0x1eba);
+      regmbc(0x1ebc); regmbc(0x1ebe); regmbc(0x1ec0);
+      regmbc(0x1ec2); regmbc(0x1ec4); regmbc(0x1ec6);
+      return;
+    case 'F':
+    case 0x191:
+    case 0x1e1e:
+    case 0xa798:
+      regmbc('F'); regmbc(0x191); regmbc(0x1e1e);
+      regmbc(0xa798);
+      return;
+    case 'G':
+    case 0x11c:
+    case 0x11e:
+    case 0x120:
+    case 0x122:
+    case 0x193:
+    case 0x1e4:
+    case 0x1e6:
+    case 0x1f4:
+    case 0x1e20:
+    case 0xa7a0:
+      regmbc('G'); regmbc(0x11c); regmbc(0x11e);
+      regmbc(0x120); regmbc(0x122); regmbc(0x193);
+      regmbc(0x1e4); regmbc(0x1e6); regmbc(0x1f4);
+      regmbc(0x1e20); regmbc(0xa7a0);
+      return;
+    case 'H':
+    case 0x124:
+    case 0x126:
+    case 0x21e:
+    case 0x1e22:
+    case 0x1e24:
+    case 0x1e26:
+    case 0x1e28:
+    case 0x1e2a:
+    case 0x2c67:
+      regmbc('H'); regmbc(0x124); regmbc(0x126);
+      regmbc(0x21e); regmbc(0x1e22); regmbc(0x1e24);
+      regmbc(0x1e26); regmbc(0x1e28); regmbc(0x1e2a);
+      regmbc(0x2c67);
+      return;
+    case 'I':
+    case 0xcc:
+    case 0xcd:
+    case 0xce:
+    case 0xcf:
+    case 0x128:
+    case 0x12a:
+    case 0x12c:
+    case 0x12e:
+    case 0x130:
+    case 0x197:
+    case 0x1cf:
+    case 0x208:
+    case 0x20a:
+    case 0x1e2c:
+    case 0x1e2e:
+    case 0x1ec8:
+    case 0x1eca:
+      regmbc('I'); regmbc(0xcc); regmbc(0xcd);
+      regmbc(0xce); regmbc(0xcf); regmbc(0x128);
+      regmbc(0x12a); regmbc(0x12c); regmbc(0x12e);
+      regmbc(0x130); regmbc(0x197); regmbc(0x1cf);
+      regmbc(0x208); regmbc(0x20a); regmbc(0x1e2c);
+      regmbc(0x1e2e); regmbc(0x1ec8); regmbc(0x1eca);
+      return;
+    case 'J':
+    case 0x134:
+    case 0x248:
+      regmbc('J'); regmbc(0x134); regmbc(0x248);
+      return;
+    case 'K':
+    case 0x136:
+    case 0x198:
+    case 0x1e8:
+    case 0x1e30:
+    case 0x1e32:
+    case 0x1e34:
+    case 0x2c69:
+    case 0xa740:
+      regmbc('K'); regmbc(0x136); regmbc(0x198);
+      regmbc(0x1e8); regmbc(0x1e30); regmbc(0x1e32);
+      regmbc(0x1e34); regmbc(0x2c69); regmbc(0xa740);
+      return;
+    case 'L':
+    case 0x139:
+    case 0x13b:
+    case 0x13d:
+    case 0x13f:
+    case 0x141:
+    case 0x23d:
+    case 0x1e36:
+    case 0x1e38:
+    case 0x1e3a:
+    case 0x1e3c:
+    case 0x2c60:
+      regmbc('L'); regmbc(0x139); regmbc(0x13b);
+      regmbc(0x13d); regmbc(0x13f); regmbc(0x141);
+      regmbc(0x23d); regmbc(0x1e36); regmbc(0x1e38);
+      regmbc(0x1e3a); regmbc(0x1e3c); regmbc(0x2c60);
+      return;
+    case 'M':
+    case 0x1e3e:
+    case 0x1e40:
+    case 0x1e42:
+      regmbc('M'); regmbc(0x1e3e); regmbc(0x1e40);
+      regmbc(0x1e42);
+      return;
+    case 'N':
+    case 0xd1:
+    case 0x143:
+    case 0x145:
+    case 0x147:
+    case 0x1f8:
+    case 0x1e44:
+    case 0x1e46:
+    case 0x1e48:
+    case 0x1e4a:
+    case 0xa7a4:
+      regmbc('N'); regmbc(0xd1);
+      regmbc(0x143); regmbc(0x145); regmbc(0x147);
+      regmbc(0x1f8); regmbc(0x1e44); regmbc(0x1e46);
+      regmbc(0x1e48); regmbc(0x1e4a); regmbc(0xa7a4);
+      return;
+    case 'O':
+    case 0xd2:
+    case 0xd3:
+    case 0xd4:
+    case 0xd5:
+    case 0xd6:
+    case 0xd8:
+    case 0x14c:
+    case 0x14e:
+    case 0x150:
+    case 0x19f:
+    case 0x1a0:
+    case 0x1d1:
+    case 0x1ea:
+    case 0x1ec:
+    case 0x1fe:
+    case 0x20c:
+    case 0x20e:
+    case 0x22a:
+    case 0x22c:
+    case 0x22e:
+    case 0x230:
+    case 0x1e4c:
+    case 0x1e4e:
+    case 0x1e50:
+    case 0x1e52:
+    case 0x1ecc:
+    case 0x1ece:
+    case 0x1ed0:
+    case 0x1ed2:
+    case 0x1ed4:
+    case 0x1ed6:
+    case 0x1ed8:
+    case 0x1eda:
+    case 0x1edc:
+    case 0x1ede:
+    case 0x1ee0:
+    case 0x1ee2:
+      regmbc('O'); regmbc(0xd2); regmbc(0xd3); regmbc(0xd4);
+      regmbc(0xd5); regmbc(0xd6); regmbc(0xd8);
+      regmbc(0x14c); regmbc(0x14e); regmbc(0x150);
+      regmbc(0x19f); regmbc(0x1a0); regmbc(0x1d1);
+      regmbc(0x1ea); regmbc(0x1ec); regmbc(0x1fe);
+      regmbc(0x20c); regmbc(0x20e); regmbc(0x22a);
+      regmbc(0x22c); regmbc(0x22e); regmbc(0x230);
+      regmbc(0x1e4c); regmbc(0x1e4e); regmbc(0x1e50);
+      regmbc(0x1e52); regmbc(0x1ecc); regmbc(0x1ece);
+      regmbc(0x1ed0); regmbc(0x1ed2); regmbc(0x1ed4);
+      regmbc(0x1ed6); regmbc(0x1ed8); regmbc(0x1eda);
+      regmbc(0x1edc); regmbc(0x1ede); regmbc(0x1ee0);
+      regmbc(0x1ee2);
+      return;
+    case 'P':
+    case 0x1a4:
+    case 0x1e54:
+    case 0x1e56:
+    case 0x2c63:
+      regmbc('P'); regmbc(0x1a4); regmbc(0x1e54);
+      regmbc(0x1e56); regmbc(0x2c63);
+      return;
+    case 'Q':
+    case 0x24a:
+      regmbc('Q'); regmbc(0x24a);
+      return;
+    case 'R':
+    case 0x154:
+    case 0x156:
+    case 0x158:
+    case 0x210:
+    case 0x212:
+    case 0x24c:
+    case 0x1e58:
+    case 0x1e5a:
+    case 0x1e5c:
+    case 0x1e5e:
+    case 0x2c64:
+    case 0xa7a6:
+      regmbc('R'); regmbc(0x154); regmbc(0x156);
+      regmbc(0x210); regmbc(0x212); regmbc(0x158);
+      regmbc(0x24c); regmbc(0x1e58); regmbc(0x1e5a);
+      regmbc(0x1e5c); regmbc(0x1e5e); regmbc(0x2c64);
+      regmbc(0xa7a6);
+      return;
+    case 'S':
+    case 0x15a:
+    case 0x15c:
+    case 0x15e:
+    case 0x160:
+    case 0x218:
+    case 0x1e60:
+    case 0x1e62:
+    case 0x1e64:
+    case 0x1e66:
+    case 0x1e68:
+    case 0x2c7e:
+    case 0xa7a8:
+      regmbc('S'); regmbc(0x15a); regmbc(0x15c);
+      regmbc(0x15e); regmbc(0x160); regmbc(0x218);
+      regmbc(0x1e60); regmbc(0x1e62); regmbc(0x1e64);
+      regmbc(0x1e66); regmbc(0x1e68); regmbc(0x2c7e);
+      regmbc(0xa7a8);
+      return;
+    case 'T':
+    case 0x162:
+    case 0x164:
+    case 0x166:
+    case 0x1ac:
+    case 0x1ae:
+    case 0x21a:
+    case 0x23e:
+    case 0x1e6a:
+    case 0x1e6c:
+    case 0x1e6e:
+    case 0x1e70:
+      regmbc('T'); regmbc(0x162); regmbc(0x164);
+      regmbc(0x166); regmbc(0x1ac); regmbc(0x23e);
+      regmbc(0x1ae); regmbc(0x21a); regmbc(0x1e6a);
+      regmbc(0x1e6c); regmbc(0x1e6e); regmbc(0x1e70);
+      return;
+    case 'U':
+    case 0xd9:
+    case 0xda:
+    case 0xdb:
+    case 0xdc:
+    case 0x168:
+    case 0x16a:
+    case 0x16c:
+    case 0x16e:
+    case 0x170:
+    case 0x172:
+    case 0x1af:
+    case 0x1d3:
+    case 0x1d5:
+    case 0x1d7:
+    case 0x1d9:
+    case 0x1db:
+    case 0x214:
+    case 0x216:
+    case 0x244:
+    case 0x1e72:
+    case 0x1e74:
+    case 0x1e76:
+    case 0x1e78:
+    case 0x1e7a:
+    case 0x1ee4:
+    case 0x1ee6:
+    case 0x1ee8:
+    case 0x1eea:
+    case 0x1eec:
+    case 0x1eee:
+    case 0x1ef0:
+      regmbc('U'); regmbc(0xd9); regmbc(0xda);
+      regmbc(0xdb); regmbc(0xdc); regmbc(0x168);
+      regmbc(0x16a); regmbc(0x16c); regmbc(0x16e);
+      regmbc(0x170); regmbc(0x172); regmbc(0x1af);
+      regmbc(0x1d3); regmbc(0x1d5); regmbc(0x1d7);
+      regmbc(0x1d9); regmbc(0x1db); regmbc(0x214);
+      regmbc(0x216); regmbc(0x244); regmbc(0x1e72);
+      regmbc(0x1e74); regmbc(0x1e76); regmbc(0x1e78);
+      regmbc(0x1e7a); regmbc(0x1ee4); regmbc(0x1ee6);
+      regmbc(0x1ee8); regmbc(0x1eea); regmbc(0x1eec);
+      regmbc(0x1eee); regmbc(0x1ef0);
+      return;
+    case 'V':
+    case 0x1b2:
+    case 0x1e7c:
+    case 0x1e7e:
+      regmbc('V'); regmbc(0x1b2); regmbc(0x1e7c);
+      regmbc(0x1e7e);
+      return;
+    case 'W':
+    case 0x174:
+    case 0x1e80:
+    case 0x1e82:
+    case 0x1e84:
+    case 0x1e86:
+    case 0x1e88:
+      regmbc('W'); regmbc(0x174); regmbc(0x1e80);
+      regmbc(0x1e82); regmbc(0x1e84); regmbc(0x1e86);
+      regmbc(0x1e88);
+      return;
+    case 'X':
+    case 0x1e8a:
+    case 0x1e8c:
+      regmbc('X'); regmbc(0x1e8a); regmbc(0x1e8c);
+      return;
+    case 'Y':
+    case 0xdd:
+    case 0x176:
+    case 0x178:
+    case 0x1b3:
+    case 0x232:
+    case 0x24e:
+    case 0x1e8e:
+    case 0x1ef2:
+    case 0x1ef6:
+    case 0x1ef4:
+    case 0x1ef8:
+      regmbc('Y'); regmbc(0xdd); regmbc(0x176);
+      regmbc(0x178); regmbc(0x1b3); regmbc(0x232);
+      regmbc(0x24e); regmbc(0x1e8e); regmbc(0x1ef2);
+      regmbc(0x1ef4); regmbc(0x1ef6); regmbc(0x1ef8);
+      return;
+    case 'Z':
+    case 0x179:
+    case 0x17b:
+    case 0x17d:
+    case 0x1b5:
+    case 0x1e90:
+    case 0x1e92:
+    case 0x1e94:
+    case 0x2c6b:
+      regmbc('Z'); regmbc(0x179); regmbc(0x17b);
+      regmbc(0x17d); regmbc(0x1b5); regmbc(0x1e90);
+      regmbc(0x1e92); regmbc(0x1e94); regmbc(0x2c6b);
+      return;
+    case 'a':
+    case 0xe0:
+    case 0xe1:
+    case 0xe2:
+    case 0xe3:
+    case 0xe4:
+    case 0xe5:
+    case 0x101:
+    case 0x103:
+    case 0x105:
+    case 0x1ce:
+    case 0x1df:
+    case 0x1e1:
+    case 0x1fb:
+    case 0x201:
+    case 0x203:
+    case 0x227:
+    case 0x1d8f:
+    case 0x1e01:
+    case 0x1e9a:
+    case 0x1ea1:
+    case 0x1ea3:
+    case 0x1ea5:
+    case 0x1ea7:
+    case 0x1ea9:
+    case 0x1eab:
+    case 0x1ead:
+    case 0x1eaf:
+    case 0x1eb1:
+    case 0x1eb3:
+    case 0x1eb5:
+    case 0x1eb7:
+    case 0x2c65:
+      regmbc('a'); regmbc(0xe0); regmbc(0xe1);
+      regmbc(0xe2); regmbc(0xe3); regmbc(0xe4);
+      regmbc(0xe5); regmbc(0x101); regmbc(0x103);
+      regmbc(0x105); regmbc(0x1ce); regmbc(0x1df);
+      regmbc(0x1e1); regmbc(0x1fb); regmbc(0x201);
+      regmbc(0x203); regmbc(0x227); regmbc(0x1d8f);
+      regmbc(0x1e01); regmbc(0x1e9a); regmbc(0x1ea1);
+      regmbc(0x1ea3); regmbc(0x1ea5); regmbc(0x1ea7);
+      regmbc(0x1ea9); regmbc(0x1eab); regmbc(0x1ead);
+      regmbc(0x1eaf); regmbc(0x1eb1); regmbc(0x1eb3);
+      regmbc(0x1eb5); regmbc(0x1eb7); regmbc(0x2c65);
+      return;
+    case 'b':
+    case 0x180:
+    case 0x253:
+    case 0x1d6c:
+    case 0x1d80:
+    case 0x1e03:
+    case 0x1e05:
+    case 0x1e07:
+      regmbc('b');
+      regmbc(0x180); regmbc(0x253); regmbc(0x1d6c);
+      regmbc(0x1d80); regmbc(0x1e03); regmbc(0x1e05);
+      regmbc(0x1e07);
+      return;
+    case 'c':
+    case 0xe7:
+    case 0x107:
+    case 0x109:
+    case 0x10b:
+    case 0x10d:
+    case 0x188:
+    case 0x23c:
+    case 0x1e09:
+    case 0xa793:
+    case 0xa794:
+      regmbc('c'); regmbc(0xe7); regmbc(0x107);
+      regmbc(0x109); regmbc(0x10b); regmbc(0x10d);
+      regmbc(0x188); regmbc(0x23c); regmbc(0x1e09);
+      regmbc(0xa793); regmbc(0xa794);
+      return;
+    case 'd':
+    case 0x10f:
+    case 0x111:
+    case 0x257:
+    case 0x1d6d:
+    case 0x1d81:
+    case 0x1d91:
+    case 0x1e0b:
+    case 0x1e0d:
+    case 0x1e0f:
+    case 0x1e11:
+    case 0x1e13:
+      regmbc('d'); regmbc(0x10f); regmbc(0x111);
+      regmbc(0x257); regmbc(0x1d6d); regmbc(0x1d81);
+      regmbc(0x1d91); regmbc(0x1e0b); regmbc(0x1e0d);
+      regmbc(0x1e0f); regmbc(0x1e11); regmbc(0x1e13);
+      return;
+    case 'e':
+    case 0xe8:
+    case 0xe9:
+    case 0xea:
+    case 0xeb:
+    case 0x113:
+    case 0x115:
+    case 0x117:
+    case 0x119:
+    case 0x11b:
+    case 0x205:
+    case 0x207:
+    case 0x229:
+    case 0x247:
+    case 0x1d92:
+    case 0x1e15:
+    case 0x1e17:
+    case 0x1e19:
+    case 0x1e1b:
+    case 0x1eb9:
+    case 0x1ebb:
+    case 0x1e1d:
+    case 0x1ebd:
+    case 0x1ebf:
+    case 0x1ec1:
+    case 0x1ec3:
+    case 0x1ec5:
+    case 0x1ec7:
+      regmbc('e'); regmbc(0xe8); regmbc(0xe9);
+      regmbc(0xea); regmbc(0xeb); regmbc(0x113);
+      regmbc(0x115); regmbc(0x117); regmbc(0x119);
+      regmbc(0x11b); regmbc(0x205); regmbc(0x207);
+      regmbc(0x229); regmbc(0x247); regmbc(0x1d92);
+      regmbc(0x1e15); regmbc(0x1e17); regmbc(0x1e19);
+      regmbc(0x1e1b); regmbc(0x1e1d); regmbc(0x1eb9);
+      regmbc(0x1ebb); regmbc(0x1ebd); regmbc(0x1ebf);
+      regmbc(0x1ec1); regmbc(0x1ec3); regmbc(0x1ec5);
+      regmbc(0x1ec7);
+      return;
+    case 'f':
+    case 0x192:
+    case 0x1d6e:
+    case 0x1d82:
+    case 0x1e1f:
+    case 0xa799:
+      regmbc('f'); regmbc(0x192); regmbc(0x1d6e);
+      regmbc(0x1d82); regmbc(0x1e1f); regmbc(0xa799);
+      return;
+    case 'g':
+    case 0x11d:
+    case 0x11f:
+    case 0x121:
+    case 0x123:
+    case 0x1e5:
+    case 0x1e7:
+    case 0x260:
+    case 0x1f5:
+    case 0x1d83:
+    case 0x1e21:
+    case 0xa7a1:
+      regmbc('g'); regmbc(0x11d); regmbc(0x11f);
+      regmbc(0x121); regmbc(0x123); regmbc(0x1e5);
+      regmbc(0x1e7); regmbc(0x1f5); regmbc(0x260);
+      regmbc(0x1d83); regmbc(0x1e21); regmbc(0xa7a1);
+      return;
+    case 'h':
+    case 0x125:
+    case 0x127:
+    case 0x21f:
+    case 0x1e23:
+    case 0x1e25:
+    case 0x1e27:
+    case 0x1e29:
+    case 0x1e2b:
+    case 0x1e96:
+    case 0x2c68:
+    case 0xa795:
+      regmbc('h'); regmbc(0x125); regmbc(0x127);
+      regmbc(0x21f); regmbc(0x1e23); regmbc(0x1e25);
+      regmbc(0x1e27); regmbc(0x1e29); regmbc(0x1e2b);
+      regmbc(0x1e96); regmbc(0x2c68); regmbc(0xa795);
+      return;
+    case 'i':
+    case 0xec:
+    case 0xed:
+    case 0xee:
+    case 0xef:
+    case 0x129:
+    case 0x12b:
+    case 0x12d:
+    case 0x12f:
+    case 0x1d0:
+    case 0x209:
+    case 0x20b:
+    case 0x268:
+    case 0x1d96:
+    case 0x1e2d:
+    case 0x1e2f:
+    case 0x1ec9:
+    case 0x1ecb:
+      regmbc('i'); regmbc(0xec); regmbc(0xed);
+      regmbc(0xee); regmbc(0xef); regmbc(0x129);
+      regmbc(0x12b); regmbc(0x12d); regmbc(0x12f);
+      regmbc(0x1d0); regmbc(0x209); regmbc(0x20b);
+      regmbc(0x268); regmbc(0x1d96); regmbc(0x1e2d);
+      regmbc(0x1e2f); regmbc(0x1ec9); regmbc(0x1ecb);
+      return;
+    case 'j':
+    case 0x135:
+    case 0x1f0:
+    case 0x249:
+      regmbc('j'); regmbc(0x135); regmbc(0x1f0);
+      regmbc(0x249);
+      return;
+    case 'k':
+    case 0x137:
+    case 0x199:
+    case 0x1e9:
+    case 0x1d84:
+    case 0x1e31:
+    case 0x1e33:
+    case 0x1e35:
+    case 0x2c6a:
+    case 0xa741:
+      regmbc('k'); regmbc(0x137); regmbc(0x199);
+      regmbc(0x1e9); regmbc(0x1d84); regmbc(0x1e31);
+      regmbc(0x1e33); regmbc(0x1e35); regmbc(0x2c6a);
+      regmbc(0xa741);
+      return;
+    case 'l':
+    case 0x13a:
+    case 0x13c:
+    case 0x13e:
+    case 0x140:
+    case 0x142:
+    case 0x19a:
+    case 0x1e37:
+    case 0x1e39:
+    case 0x1e3b:
+    case 0x1e3d:
+    case 0x2c61:
+      regmbc('l'); regmbc(0x13a); regmbc(0x13c);
+      regmbc(0x13e); regmbc(0x140); regmbc(0x142);
+      regmbc(0x19a); regmbc(0x1e37); regmbc(0x1e39);
+      regmbc(0x1e3b); regmbc(0x1e3d); regmbc(0x2c61);
+      return;
+    case 'm':
+    case 0x1d6f:
+    case 0x1e3f:
+    case 0x1e41:
+    case 0x1e43:
+      regmbc('m'); regmbc(0x1d6f); regmbc(0x1e3f);
+      regmbc(0x1e41); regmbc(0x1e43);
+      return;
+    case 'n':
+    case 0xf1:
+    case 0x144:
+    case 0x146:
+    case 0x148:
+    case 0x149:
+    case 0x1f9:
+    case 0x1d70:
+    case 0x1d87:
+    case 0x1e45:
+    case 0x1e47:
+    case 0x1e49:
+    case 0x1e4b:
+    case 0xa7a5:
+      regmbc('n'); regmbc(0xf1); regmbc(0x144);
+      regmbc(0x146); regmbc(0x148); regmbc(0x149);
+      regmbc(0x1f9); regmbc(0x1d70); regmbc(0x1d87);
+      regmbc(0x1e45); regmbc(0x1e47); regmbc(0x1e49);
+      regmbc(0x1e4b); regmbc(0xa7a5);
+      return;
+    case 'o':
+    case 0xf2:
+    case 0xf3:
+    case 0xf4:
+    case 0xf5:
+    case 0xf6:
+    case 0xf8:
+    case 0x14d:
+    case 0x14f:
+    case 0x151:
+    case 0x1a1:
+    case 0x1d2:
+    case 0x1eb:
+    case 0x1ed:
+    case 0x1ff:
+    case 0x20d:
+    case 0x20f:
+    case 0x22b:
+    case 0x22d:
+    case 0x22f:
+    case 0x231:
+    case 0x275:
+    case 0x1e4d:
+    case 0x1e4f:
+    case 0x1e51:
+    case 0x1e53:
+    case 0x1ecd:
+    case 0x1ecf:
+    case 0x1ed1:
+    case 0x1ed3:
+    case 0x1ed5:
+    case 0x1ed7:
+    case 0x1ed9:
+    case 0x1edb:
+    case 0x1edd:
+    case 0x1edf:
+    case 0x1ee1:
+    case 0x1ee3:
+      regmbc('o'); regmbc(0xf2); regmbc(0xf3);
+      regmbc(0xf4); regmbc(0xf5); regmbc(0xf6);
+      regmbc(0xf8); regmbc(0x14d); regmbc(0x14f);
+      regmbc(0x151); regmbc(0x1a1); regmbc(0x1d2);
+      regmbc(0x1eb); regmbc(0x1ed); regmbc(0x1ff);
+      regmbc(0x20d); regmbc(0x20f); regmbc(0x22b);
+      regmbc(0x22d); regmbc(0x22f); regmbc(0x231);
+      regmbc(0x275); regmbc(0x1e4d); regmbc(0x1e4f);
+      regmbc(0x1e51); regmbc(0x1e53); regmbc(0x1ecd);
+      regmbc(0x1ecf); regmbc(0x1ed1); regmbc(0x1ed3);
+      regmbc(0x1ed5); regmbc(0x1ed7); regmbc(0x1ed9);
+      regmbc(0x1edb); regmbc(0x1edd); regmbc(0x1edf);
+      regmbc(0x1ee1); regmbc(0x1ee3);
+      return;
+    case 'p':
+    case 0x1a5:
+    case 0x1d71:
+    case 0x1d88:
+    case 0x1d7d:
+    case 0x1e55:
+    case 0x1e57:
+      regmbc('p'); regmbc(0x1a5); regmbc(0x1d71);
+      regmbc(0x1d7d); regmbc(0x1d88); regmbc(0x1e55);
+      regmbc(0x1e57);
+      return;
+    case 'q':
+    case 0x24b:
+    case 0x2a0:
+      regmbc('q'); regmbc(0x24b); regmbc(0x2a0);
+      return;
+    case 'r':
+    case 0x155:
+    case 0x157:
+    case 0x159:
+    case 0x211:
+    case 0x213:
+    case 0x24d:
+    case 0x27d:
+    case 0x1d72:
+    case 0x1d73:
+    case 0x1d89:
+    case 0x1e59:
+    case 0x1e5b:
+    case 0x1e5d:
+    case 0x1e5f:
+    case 0xa7a7:
+      regmbc('r'); regmbc(0x155); regmbc(0x157);
+      regmbc(0x159); regmbc(0x211); regmbc(0x213);
+      regmbc(0x24d); regmbc(0x1d72); regmbc(0x1d73);
+      regmbc(0x1d89); regmbc(0x1e59); regmbc(0x27d);
+      regmbc(0x1e5b); regmbc(0x1e5d); regmbc(0x1e5f);
+      regmbc(0xa7a7);
+      return;
+    case 's':
+    case 0x15b:
+    case 0x15d:
+    case 0x15f:
+    case 0x161:
+    case 0x1e61:
+    case 0x219:
+    case 0x23f:
+    case 0x1d74:
+    case 0x1d8a:
+    case 0x1e63:
+    case 0x1e65:
+    case 0x1e67:
+    case 0x1e69:
+    case 0xa7a9:
+      regmbc('s'); regmbc(0x15b); regmbc(0x15d);
+      regmbc(0x15f); regmbc(0x161); regmbc(0x23f);
+      regmbc(0x219); regmbc(0x1d74); regmbc(0x1d8a);
+      regmbc(0x1e61); regmbc(0x1e63); regmbc(0x1e65);
+      regmbc(0x1e67); regmbc(0x1e69); regmbc(0xa7a9);
+      return;
+    case 't':
+    case 0x163:
+    case 0x165:
+    case 0x167:
+    case 0x1ab:
+    case 0x1ad:
+    case 0x21b:
+    case 0x288:
+    case 0x1d75:
+    case 0x1e6b:
+    case 0x1e6d:
+    case 0x1e6f:
+    case 0x1e71:
+    case 0x1e97:
+    case 0x2c66:
+      regmbc('t'); regmbc(0x163); regmbc(0x165);
+      regmbc(0x167); regmbc(0x1ab); regmbc(0x21b);
+      regmbc(0x1ad); regmbc(0x288); regmbc(0x1d75);
+      regmbc(0x1e6b); regmbc(0x1e6d); regmbc(0x1e6f);
+      regmbc(0x1e71); regmbc(0x1e97); regmbc(0x2c66);
+      return;
+    case 'u':
+    case 0xf9:
+    case 0xfa:
+    case 0xfb:
+    case 0xfc:
+    case 0x169:
+    case 0x16b:
+    case 0x16d:
+    case 0x16f:
+    case 0x171:
+    case 0x173:
+    case 0x1b0:
+    case 0x1d4:
+    case 0x1d6:
+    case 0x1d8:
+    case 0x1da:
+    case 0x1dc:
+    case 0x215:
+    case 0x217:
+    case 0x289:
+    case 0x1e73:
+    case 0x1d7e:
+    case 0x1d99:
+    case 0x1e75:
+    case 0x1e77:
+    case 0x1e79:
+    case 0x1e7b:
+    case 0x1ee5:
+    case 0x1ee7:
+    case 0x1ee9:
+    case 0x1eeb:
+    case 0x1eed:
+    case 0x1eef:
+    case 0x1ef1:
+      regmbc('u'); regmbc(0xf9); regmbc(0xfa);
+      regmbc(0xfb); regmbc(0xfc); regmbc(0x169);
+      regmbc(0x16b); regmbc(0x16d); regmbc(0x16f);
+      regmbc(0x171); regmbc(0x173); regmbc(0x1d6);
+      regmbc(0x1d8); regmbc(0x1da); regmbc(0x1dc);
+      regmbc(0x215); regmbc(0x217); regmbc(0x1b0);
+      regmbc(0x1d4); regmbc(0x289); regmbc(0x1d7e);
+      regmbc(0x1d99); regmbc(0x1e73); regmbc(0x1e75);
+      regmbc(0x1e77); regmbc(0x1e79); regmbc(0x1e7b);
+      regmbc(0x1ee5); regmbc(0x1ee7); regmbc(0x1ee9);
+      regmbc(0x1eeb); regmbc(0x1eed); regmbc(0x1eef);
+      regmbc(0x1ef1);
+      return;
+    case 'v':
+    case 0x28b:
+    case 0x1d8c:
+    case 0x1e7d:
+    case 0x1e7f:
+      regmbc('v'); regmbc(0x28b); regmbc(0x1d8c);
+      regmbc(0x1e7d); regmbc(0x1e7f);
+      return;
+    case 'w':
+    case 0x175:
+    case 0x1e81:
+    case 0x1e83:
+    case 0x1e85:
+    case 0x1e87:
+    case 0x1e89:
+    case 0x1e98:
+      regmbc('w'); regmbc(0x175); regmbc(0x1e81);
+      regmbc(0x1e83); regmbc(0x1e85); regmbc(0x1e87);
+      regmbc(0x1e89); regmbc(0x1e98);
+      return;
+    case 'x':
+    case 0x1e8b:
+    case 0x1e8d:
+      regmbc('x'); regmbc(0x1e8b); regmbc(0x1e8d);
+      return;
+    case 'y':
+    case 0xfd:
+    case 0xff:
+    case 0x177:
+    case 0x1b4:
+    case 0x233:
+    case 0x24f:
+    case 0x1e8f:
+    case 0x1e99:
+    case 0x1ef3:
+    case 0x1ef5:
+    case 0x1ef7:
+    case 0x1ef9:
+      regmbc('y'); regmbc(0xfd); regmbc(0xff);
+      regmbc(0x177); regmbc(0x1b4); regmbc(0x233);
+      regmbc(0x24f); regmbc(0x1e8f); regmbc(0x1e99);
+      regmbc(0x1ef3); regmbc(0x1ef5); regmbc(0x1ef7);
+      regmbc(0x1ef9);
+      return;
+    case 'z':
+    case 0x17a:
+    case 0x17c:
+    case 0x17e:
+    case 0x1b6:
+    case 0x1d76:
+    case 0x1d8e:
+    case 0x1e91:
+    case 0x1e93:
+    case 0x1e95:
+    case 0x2c6c:
+      regmbc('z'); regmbc(0x17a); regmbc(0x17c);
+      regmbc(0x17e); regmbc(0x1b6); regmbc(0x1d76);
+      regmbc(0x1d8e); regmbc(0x1e91); regmbc(0x1e93);
+      regmbc(0x1e95); regmbc(0x2c6c);
+      return;
+    }
+  }
+  regmbc(c);
+}
+
+// Emit a node.
+// Return pointer to generated code.
+static uint8_t *regnode(int op)
+{
+  uint8_t *ret;
+
+  ret = regcode;
+  if (ret == JUST_CALC_SIZE) {
+    regsize += 3;
+  } else {
+    *regcode++ = (uint8_t)op;
+    *regcode++ = NUL;                   // Null "next" pointer.
+    *regcode++ = NUL;
+  }
+  return ret;
+}
+
+// Write a four bytes number at "p" and return pointer to the next char.
+static uint8_t *re_put_uint32(uint8_t *p, uint32_t val)
+{
+  *p++ = (uint8_t)((val >> 24) & 0377);
+  *p++ = (uint8_t)((val >> 16) & 0377);
+  *p++ = (uint8_t)((val >> 8) & 0377);
+  *p++ = (uint8_t)(val & 0377);
+  return p;
+}
+
+// regnext - dig the "next" pointer out of a node
+// Returns NULL when calculating size, when there is no next item and when
+// there is an error.
+static uint8_t *regnext(uint8_t *p)
+  FUNC_ATTR_NONNULL_ALL
+{
+  int offset;
+
+  if (p == JUST_CALC_SIZE || reg_toolong) {
+    return NULL;
+  }
+
+  offset = NEXT(p);
+  if (offset == 0) {
+    return NULL;
+  }
+
+  if (OP(p) == BACK) {
+    return p - offset;
+  } else {
+    return p + offset;
+  }
+}
+
+// Set the next-pointer at the end of a node chain.
+static void regtail(uint8_t *p, const uint8_t *val)
+{
+  int offset;
+
+  if (p == JUST_CALC_SIZE) {
+    return;
+  }
+
+  // Find last node.
+  uint8_t *scan = p;
+  while (true) {
+    uint8_t *temp = regnext(scan);
+    if (temp == NULL) {
+      break;
+    }
+    scan = temp;
+  }
+
+  if (OP(scan) == BACK) {
+    offset = (int)(scan - val);
+  } else {
+    offset = (int)(val - scan);
+  }
+  // When the offset uses more than 16 bits it can no longer fit in the two
+  // bytes available.  Use a global flag to avoid having to check return
+  // values in too many places.
+  if (offset > 0xffff) {
+    reg_toolong = true;
+  } else {
+    *(scan + 1) = (uint8_t)(((unsigned)offset >> 8) & 0377);
+    *(scan + 2) = (uint8_t)(offset & 0377);
+  }
+}
+
+// Like regtail, on item after a BRANCH; nop if none.
+static void regoptail(uint8_t *p, uint8_t *val)
+{
+  // When op is neither BRANCH nor BRACE_COMPLEX0-9, it is "operandless"
+  if (p == NULL || p == JUST_CALC_SIZE
+      || (OP(p) != BRANCH
+          && (OP(p) < BRACE_COMPLEX || OP(p) > BRACE_COMPLEX + 9))) {
+    return;
+  }
+  regtail(OPERAND(p), val);
+}
+
+// Insert an operator in front of already-emitted operand
+//
+// Means relocating the operand.
+static void reginsert(int op, uint8_t *opnd)
+{
+  uint8_t *src;
+  uint8_t *dst;
+  uint8_t *place;
+
+  if (regcode == JUST_CALC_SIZE) {
+    regsize += 3;
+    return;
+  }
+  src = regcode;
+  regcode += 3;
+  dst = regcode;
+  while (src > opnd) {
+    *--dst = *--src;
+  }
+
+  place = opnd;                 // Op node, where operand used to be.
+  *place++ = (uint8_t)op;
+  *place++ = NUL;
+  *place = NUL;
+}
+
+// Insert an operator in front of already-emitted operand.
+// Add a number to the operator.
+static void reginsert_nr(int op, int64_t val, uint8_t *opnd)
+{
+  uint8_t *src;
+  uint8_t *dst;
+  uint8_t *place;
+
+  if (regcode == JUST_CALC_SIZE) {
+    regsize += 7;
+    return;
+  }
+  src = regcode;
+  regcode += 7;
+  dst = regcode;
+  while (src > opnd) {
+    *--dst = *--src;
+  }
+
+  place = opnd;                 // Op node, where operand used to be.
+  *place++ = (uint8_t)op;
+  *place++ = NUL;
+  *place++ = NUL;
+  assert(val >= 0 && (uintmax_t)val <= UINT32_MAX);
+  re_put_uint32(place, (uint32_t)val);
+}
+
+// Insert an operator in front of already-emitted operand.
+// The operator has the given limit values as operands.  Also set next pointer.
+//
+// Means relocating the operand.
+static void reginsert_limits(int op, int64_t minval, int64_t maxval, uint8_t *opnd)
+{
+  uint8_t *src;
+  uint8_t *dst;
+  uint8_t *place;
+
+  if (regcode == JUST_CALC_SIZE) {
+    regsize += 11;
+    return;
+  }
+  src = regcode;
+  regcode += 11;
+  dst = regcode;
+  while (src > opnd) {
+    *--dst = *--src;
+  }
+
+  place = opnd;                 // Op node, where operand used to be.
+  *place++ = (uint8_t)op;
+  *place++ = NUL;
+  *place++ = NUL;
+  assert(minval >= 0 && (uintmax_t)minval <= UINT32_MAX);
+  place = re_put_uint32(place, (uint32_t)minval);
+  assert(maxval >= 0 && (uintmax_t)maxval <= UINT32_MAX);
+  place = re_put_uint32(place, (uint32_t)maxval);
+  regtail(opnd, place);
+}
+
+/// Return true if the back reference is legal. We must have seen the close
+/// brace.
+/// TODO(vim): Should also check that we don't refer to something repeated
+/// (+*=): what instance of the repetition should we match?
+static int seen_endbrace(int refnum)
+{
+  if (!had_endbrace[refnum]) {
+    uint8_t *p;
+
+    // Trick: check if "@<=" or "@<!" follows, in which case
+    // the \1 can appear before the referenced match.
+    for (p = (uint8_t *)regparse; *p != NUL; p++) {
+      if (p[0] == '@' && p[1] == '<' && (p[2] == '!' || p[2] == '=')) {
+        break;
+      }
+    }
+
+    if (*p == NUL) {
+      emsg(_("E65: Illegal back reference"));
+      rc_did_emsg = true;
+      return false;
+    }
+  }
+  return true;
+}
+
+// Parse the lowest level.
+//
+// Optimization:  gobbles an entire sequence of ordinary characters so that
+// it can turn them into a single node, which is smaller to store and
+// faster to run.  Don't do this when one_exactly is set.
+static uint8_t *regatom(int *flagp)
+{
+  uint8_t *ret;
+  int flags;
+  int c;
+  uint8_t *p;
+  int extra = 0;
+  int save_prev_at_start = prev_at_start;
+
+  *flagp = WORST;               // Tentatively.
+
+  c = getchr();
+  switch (c) {
+  case Magic('^'):
+    ret = regnode(BOL);
+    break;
+
+  case Magic('$'):
+    ret = regnode(EOL);
+    had_eol = true;
+    break;
+
+  case Magic('<'):
+    ret = regnode(BOW);
+    break;
+
+  case Magic('>'):
+    ret = regnode(EOW);
+    break;
+
+  case Magic('_'):
+    c = no_Magic(getchr());
+    if (c == '^') {             // "\_^" is start-of-line
+      ret = regnode(BOL);
+      break;
+    }
+    if (c == '$') {             // "\_$" is end-of-line
+      ret = regnode(EOL);
+      had_eol = true;
+      break;
+    }
+
+    extra = ADD_NL;
+    *flagp |= HASNL;
+
+    // "\_[" is character range plus newline
+    if (c == '[') {
+      goto collection;
+    }
+
+    // "\_x" is character class plus newline
+    FALLTHROUGH;
+
+  // Character classes.
+  case Magic('.'):
+  case Magic('i'):
+  case Magic('I'):
+  case Magic('k'):
+  case Magic('K'):
+  case Magic('f'):
+  case Magic('F'):
+  case Magic('p'):
+  case Magic('P'):
+  case Magic('s'):
+  case Magic('S'):
+  case Magic('d'):
+  case Magic('D'):
+  case Magic('x'):
+  case Magic('X'):
+  case Magic('o'):
+  case Magic('O'):
+  case Magic('w'):
+  case Magic('W'):
+  case Magic('h'):
+  case Magic('H'):
+  case Magic('a'):
+  case Magic('A'):
+  case Magic('l'):
+  case Magic('L'):
+  case Magic('u'):
+  case Magic('U'):
+    p = (uint8_t *)vim_strchr((char *)classchars, no_Magic(c));
+    if (p == NULL) {
+      EMSG_RET_NULL(_(e_invalid_use_of_underscore));
+    }
+    // When '.' is followed by a composing char ignore the dot, so that
+    // the composing char is matched here.
+    if (c == Magic('.') && utf_iscomposing(peekchr())) {
+      c = getchr();
+      goto do_multibyte;
+    }
+    ret = regnode(classcodes[p - classchars] + extra);
+    *flagp |= HASWIDTH | SIMPLE;
+    break;
+
+  case Magic('n'):
+    if (reg_string) {
+      // In a string "\n" matches a newline character.
+      ret = regnode(EXACTLY);
+      regc(NL);
+      regc(NUL);
+      *flagp |= HASWIDTH | SIMPLE;
+    } else {
+      // In buffer text "\n" matches the end of a line.
+      ret = regnode(NEWL);
+      *flagp |= HASWIDTH | HASNL;
+    }
+    break;
+
+  case Magic('('):
+    if (one_exactly) {
+      EMSG_ONE_RET_NULL;
+    }
+    ret = reg(REG_PAREN, &flags);
+    if (ret == NULL) {
+      return NULL;
+    }
+    *flagp |= flags & (HASWIDTH | SPSTART | HASNL | HASLOOKBH);
+    break;
+
+  case NUL:
+  case Magic('|'):
+  case Magic('&'):
+  case Magic(')'):
+    if (one_exactly) {
+      EMSG_ONE_RET_NULL;
+    }
+    IEMSG_RET_NULL(_(e_internal));       // Supposed to be caught earlier.
+  // NOTREACHED
+
+  case Magic('='):
+  case Magic('?'):
+  case Magic('+'):
+  case Magic('@'):
+  case Magic('{'):
+  case Magic('*'):
+    c = no_Magic(c);
+    EMSG3_RET_NULL(_("E64: %s%c follows nothing"),
+                   (c == '*' ? reg_magic >= MAGIC_ON : reg_magic == MAGIC_ALL), c);
+  // NOTREACHED
+
+  case Magic('~'):              // previous substitute pattern
+    if (reg_prev_sub != NULL) {
+      uint8_t *lp;
+
+      ret = regnode(EXACTLY);
+      lp = (uint8_t *)reg_prev_sub;
+      while (*lp != NUL) {
+        regc(*lp++);
+      }
+      regc(NUL);
+      if (*reg_prev_sub != NUL) {
+        *flagp |= HASWIDTH;
+        if ((lp - (uint8_t *)reg_prev_sub) == 1) {
+          *flagp |= SIMPLE;
+        }
+      }
+    } else {
+      EMSG_RET_NULL(_(e_nopresub));
+    }
+    break;
+
+  case Magic('1'):
+  case Magic('2'):
+  case Magic('3'):
+  case Magic('4'):
+  case Magic('5'):
+  case Magic('6'):
+  case Magic('7'):
+  case Magic('8'):
+  case Magic('9'): {
+    int refnum;
+
+    refnum = c - Magic('0');
+    if (!seen_endbrace(refnum)) {
+      return NULL;
+    }
+    ret = regnode(BACKREF + refnum);
+  }
+  break;
+
+  case Magic('z'):
+    c = no_Magic(getchr());
+    switch (c) {
+    case '(':
+      if ((reg_do_extmatch & REX_SET) == 0) {
+        EMSG_RET_NULL(_(e_z_not_allowed));
+      }
+      if (one_exactly) {
+        EMSG_ONE_RET_NULL;
+      }
+      ret = reg(REG_ZPAREN, &flags);
+      if (ret == NULL) {
+        return NULL;
+      }
+      *flagp |= flags & (HASWIDTH|SPSTART|HASNL|HASLOOKBH);
+      re_has_z = REX_SET;
+      break;
+
+    case '1':
+    case '2':
+    case '3':
+    case '4':
+    case '5':
+    case '6':
+    case '7':
+    case '8':
+    case '9':
+      if ((reg_do_extmatch & REX_USE) == 0) {
+        EMSG_RET_NULL(_(e_z1_not_allowed));
+      }
+      ret = regnode(ZREF + c - '0');
+      re_has_z = REX_USE;
+      break;
+
+    case 's':
+      ret = regnode(MOPEN + 0);
+      if (!re_mult_next("\\zs")) {
+        return NULL;
+      }
+      break;
+
+    case 'e':
+      ret = regnode(MCLOSE + 0);
+      if (!re_mult_next("\\ze")) {
+        return NULL;
+      }
+      break;
+
+    default:
+      EMSG_RET_NULL(_("E68: Invalid character after \\z"));
+    }
+    break;
+
+  case Magic('%'):
+    c = no_Magic(getchr());
+    switch (c) {
+    // () without a back reference
+    case '(':
+      if (one_exactly) {
+        EMSG_ONE_RET_NULL;
+      }
+      ret = reg(REG_NPAREN, &flags);
+      if (ret == NULL) {
+        return NULL;
+      }
+      *flagp |= flags & (HASWIDTH | SPSTART | HASNL | HASLOOKBH);
+      break;
+
+    // Catch \%^ and \%$ regardless of where they appear in the
+    // pattern -- regardless of whether or not it makes sense.
+    case '^':
+      ret = regnode(RE_BOF);
+      break;
+
+    case '$':
+      ret = regnode(RE_EOF);
+      break;
+
+    case '#':
+      if (regparse[0] == '=' && regparse[1] >= 48 && regparse[1] <= 50) {
+        // misplaced \%#=1
+        semsg(_(e_atom_engine_must_be_at_start_of_pattern), regparse[1]);
+        return FAIL;
+      }
+      ret = regnode(CURSOR);
+      break;
+
+    case 'V':
+      ret = regnode(RE_VISUAL);
+      break;
+
+    case 'C':
+      ret = regnode(RE_COMPOSING);
+      break;
+
+    // \%[abc]: Emit as a list of branches, all ending at the last
+    // branch which matches nothing.
+    case '[':
+      if (one_exactly) {                        // doesn't nest
+        EMSG_ONE_RET_NULL;
+      }
+      {
+        uint8_t *lastbranch;
+        uint8_t *lastnode = NULL;
+        uint8_t *br;
+
+        ret = NULL;
+        while ((c = getchr()) != ']') {
+          if (c == NUL) {
+            EMSG2_RET_NULL(_(e_missing_sb),
+                           reg_magic == MAGIC_ALL);
+          }
+          br = regnode(BRANCH);
+          if (ret == NULL) {
+            ret = br;
+          } else {
+            regtail(lastnode, br);
+            if (reg_toolong) {
+              return NULL;
+            }
+          }
+
+          ungetchr();
+          one_exactly = true;
+          lastnode = regatom(flagp);
+          one_exactly = false;
+          if (lastnode == NULL) {
+            return NULL;
+          }
+        }
+        if (ret == NULL) {
+          EMSG2_RET_NULL(_(e_empty_sb),
+                         reg_magic == MAGIC_ALL);
+        }
+        lastbranch = regnode(BRANCH);
+        br = regnode(NOTHING);
+        if (ret != JUST_CALC_SIZE) {
+          regtail(lastnode, br);
+          regtail(lastbranch, br);
+          // connect all branches to the NOTHING
+          // branch at the end
+          for (br = ret; br != lastnode;) {
+            if (OP(br) == BRANCH) {
+              regtail(br, lastbranch);
+              if (reg_toolong) {
+                return NULL;
+              }
+              br = OPERAND(br);
+            } else {
+              br = regnext(br);
+            }
+          }
+        }
+        *flagp &= ~(HASWIDTH | SIMPLE);
+        break;
+      }
+
+    case 'd':               // %d123 decimal
+    case 'o':               // %o123 octal
+    case 'x':               // %xab hex 2
+    case 'u':               // %uabcd hex 4
+    case 'U':               // %U1234abcd hex 8
+    {
+      int64_t i;
+
+      switch (c) {
+      case 'd':
+        i = getdecchrs(); break;
+      case 'o':
+        i = getoctchrs(); break;
+      case 'x':
+        i = gethexchrs(2); break;
+      case 'u':
+        i = gethexchrs(4); break;
+      case 'U':
+        i = gethexchrs(8); break;
+      default:
+        i = -1; break;
+      }
+
+      if (i < 0 || i > INT_MAX) {
+        EMSG2_RET_NULL(_("E678: Invalid character after %s%%[dxouU]"),
+                       reg_magic == MAGIC_ALL);
+      }
+      if (use_multibytecode((int)i)) {
+        ret = regnode(MULTIBYTECODE);
+      } else {
+        ret = regnode(EXACTLY);
+      }
+      if (i == 0) {
+        regc(0x0a);
+      } else {
+        regmbc((int)i);
+      }
+      regc(NUL);
+      *flagp |= HASWIDTH;
+      break;
+    }
+
+    default:
+      if (ascii_isdigit(c) || c == '<' || c == '>' || c == '\'' || c == '.') {
+        uint32_t n = 0;
+        int cmp;
+        bool cur = false;
+        bool got_digit = false;
+
+        cmp = c;
+        if (cmp == '<' || cmp == '>') {
+          c = getchr();
+        }
+        if (no_Magic(c) == '.') {
+          cur = true;
+          c = getchr();
+        }
+        while (ascii_isdigit(c)) {
+          got_digit = true;
+          n = n * 10 + (uint32_t)(c - '0');
+          c = getchr();
+        }
+        if (c == '\'' && n == 0) {
+          // "\%'m", "\%<'m" and "\%>'m": Mark
+          c = getchr();
+          ret = regnode(RE_MARK);
+          if (ret == JUST_CALC_SIZE) {
+            regsize += 2;
+          } else {
+            *regcode++ = (uint8_t)c;
+            *regcode++ = (uint8_t)cmp;
+          }
+          break;
+        } else if ((c == 'l' || c == 'c' || c == 'v') && (cur || got_digit)) {
+          if (cur && n) {
+            semsg(_(e_regexp_number_after_dot_pos_search_chr), no_Magic(c));
+            rc_did_emsg = true;
+            return NULL;
+          }
+          if (c == 'l') {
+            if (cur) {
+              n = (uint32_t)curwin->w_cursor.lnum;
+            }
+            ret = regnode(RE_LNUM);
+            if (save_prev_at_start) {
+              at_start = true;
+            }
+          } else if (c == 'c') {
+            if (cur) {
+              n = (uint32_t)curwin->w_cursor.col;
+              n++;
+            }
+            ret = regnode(RE_COL);
+          } else {
+            if (cur) {
+              colnr_T vcol = 0;
+              getvvcol(curwin, &curwin->w_cursor, NULL, NULL, &vcol);
+              n = (uint32_t)(++vcol);
+            }
+            ret = regnode(RE_VCOL);
+          }
+          if (ret == JUST_CALC_SIZE) {
+            regsize += 5;
+          } else {
+            // put the number and the optional
+            // comparator after the opcode
+            regcode = re_put_uint32(regcode, n);
+            *regcode++ = (uint8_t)cmp;
+          }
+          break;
+        }
+      }
+
+      EMSG2_RET_NULL(_("E71: Invalid character after %s%%"),
+                     reg_magic == MAGIC_ALL);
+    }
+    break;
+
+  case Magic('['):
+collection:
+    {
+      uint8_t *lp;
+
+      // If there is no matching ']', we assume the '[' is a normal
+      // character.  This makes 'incsearch' and ":help [" work.
+      lp = (uint8_t *)skip_anyof(regparse);
+      if (*lp == ']') {         // there is a matching ']'
+        int startc = -1;                // > 0 when next '-' is a range
+        int endc;
+
+        // In a character class, different parsing rules apply.
+        // Not even \ is special anymore, nothing is.
+        if (*regparse == '^') {             // Complement of range.
+          ret = regnode(ANYBUT + extra);
+          regparse++;
+        } else {
+          ret = regnode(ANYOF + extra);
+        }
+
+        // At the start ']' and '-' mean the literal character.
+        if (*regparse == ']' || *regparse == '-') {
+          startc = (uint8_t)(*regparse);
+          regc(*regparse++);
+        }
+
+        while (*regparse != NUL && *regparse != ']') {
+          if (*regparse == '-') {
+            regparse++;
+            // The '-' is not used for a range at the end and
+            // after or before a '\n'.
+            if (*regparse == ']' || *regparse == NUL
+                || startc == -1
+                || (regparse[0] == '\\' && regparse[1] == 'n')) {
+              regc('-');
+              startc = '-';                     // [--x] is a range
+            } else {
+              // Also accept "a-[.z.]"
+              endc = 0;
+              if (*regparse == '[') {
+                endc = get_coll_element(&regparse);
+              }
+              if (endc == 0) {
+                endc = mb_ptr2char_adv((const char **)&regparse);
+              }
+
+              // Handle \o40, \x20 and \u20AC style sequences
+              if (endc == '\\' && !reg_cpo_lit) {
+                endc = coll_get_char();
+              }
+
+              if (startc > endc) {
+                EMSG_RET_NULL(_(e_reverse_range));
+              }
+              if (utf_char2len(startc) > 1
+                  || utf_char2len(endc) > 1) {
+                // Limit to a range of 256 chars
+                if (endc > startc + 256) {
+                  EMSG_RET_NULL(_(e_large_class));
+                }
+                while (++startc <= endc) {
+                  regmbc(startc);
+                }
+              } else {
+                while (++startc <= endc) {
+                  regc(startc);
+                }
+              }
+              startc = -1;
+            }
+          }
+          // Only "\]", "\^", "\]" and "\\" are special in Vi.  Vim
+          // accepts "\t", "\e", etc., but only when the 'l' flag in
+          // 'cpoptions' is not included.
+          else if (*regparse == '\\'
+                   && (vim_strchr(REGEXP_INRANGE, (uint8_t)regparse[1]) != NULL
+                       || (!reg_cpo_lit
+                           && vim_strchr(REGEXP_ABBR,
+                                         (uint8_t)regparse[1]) != NULL))) {
+            regparse++;
+            if (*regparse == 'n') {
+              // '\n' in range: also match NL
+              if (ret != JUST_CALC_SIZE) {
+                // Using \n inside [^] does not change what
+                // matches. "[^\n]" is the same as ".".
+                if (*ret == ANYOF) {
+                  *ret = ANYOF + ADD_NL;
+                  *flagp |= HASNL;
+                }
+                // else: must have had a \n already
+              }
+              regparse++;
+              startc = -1;
+            } else if (*regparse == 'd'
+                       || *regparse == 'o'
+                       || *regparse == 'x'
+                       || *regparse == 'u'
+                       || *regparse == 'U') {
+              startc = coll_get_char();
+              if (startc == 0) {
+                regc(0x0a);
+              } else {
+                regmbc(startc);
+              }
+            } else {
+              startc = backslash_trans(*regparse++);
+              regc(startc);
+            }
+          } else if (*regparse == '[') {
+            int c_class;
+            int cu;
+
+            c_class = get_char_class(&regparse);
+            startc = -1;
+            // Characters assumed to be 8 bits!
+            switch (c_class) {
+            case CLASS_NONE:
+              c_class = get_equi_class(&regparse);
+              if (c_class != 0) {
+                // produce equivalence class
+                reg_equi_class(c_class);
+              } else if ((c_class = get_coll_element(&regparse)) != 0) {
+                // produce a collating element
+                regmbc(c_class);
+              } else {
+                // literal '[', allow [[-x] as a range
+                startc = (uint8_t)(*regparse++);
+                regc(startc);
+              }
+              break;
+            case CLASS_ALNUM:
+              for (cu = 1; cu < 128; cu++) {
+                if (isalnum(cu)) {
+                  regmbc(cu);
+                }
+              }
+              break;
+            case CLASS_ALPHA:
+              for (cu = 1; cu < 128; cu++) {
+                if (isalpha(cu)) {
+                  regmbc(cu);
+                }
+              }
+              break;
+            case CLASS_BLANK:
+              regc(' ');
+              regc('\t');
+              break;
+            case CLASS_CNTRL:
+              for (cu = 1; cu <= 127; cu++) {
+                if (iscntrl(cu)) {
+                  regmbc(cu);
+                }
+              }
+              break;
+            case CLASS_DIGIT:
+              for (cu = 1; cu <= 127; cu++) {
+                if (ascii_isdigit(cu)) {
+                  regmbc(cu);
+                }
+              }
+              break;
+            case CLASS_GRAPH:
+              for (cu = 1; cu <= 127; cu++) {
+                if (isgraph(cu)) {
+                  regmbc(cu);
+                }
+              }
+              break;
+            case CLASS_LOWER:
+              for (cu = 1; cu <= 255; cu++) {
+                if (mb_islower(cu) && cu != 170 && cu != 186) {
+                  regmbc(cu);
+                }
+              }
+              break;
+            case CLASS_PRINT:
+              for (cu = 1; cu <= 255; cu++) {
+                if (vim_isprintc(cu)) {
+                  regmbc(cu);
+                }
+              }
+              break;
+            case CLASS_PUNCT:
+              for (cu = 1; cu < 128; cu++) {
+                if (ispunct(cu)) {
+                  regmbc(cu);
+                }
+              }
+              break;
+            case CLASS_SPACE:
+              for (cu = 9; cu <= 13; cu++) {
+                regc(cu);
+              }
+              regc(' ');
+              break;
+            case CLASS_UPPER:
+              for (cu = 1; cu <= 255; cu++) {
+                if (mb_isupper(cu)) {
+                  regmbc(cu);
+                }
+              }
+              break;
+            case CLASS_XDIGIT:
+              for (cu = 1; cu <= 255; cu++) {
+                if (ascii_isxdigit(cu)) {
+                  regmbc(cu);
+                }
+              }
+              break;
+            case CLASS_TAB:
+              regc('\t');
+              break;
+            case CLASS_RETURN:
+              regc('\r');
+              break;
+            case CLASS_BACKSPACE:
+              regc('\b');
+              break;
+            case CLASS_ESCAPE:
+              regc(ESC);
+              break;
+            case CLASS_IDENT:
+              for (cu = 1; cu <= 255; cu++) {
+                if (vim_isIDc(cu)) {
+                  regmbc(cu);
+                }
+              }
+              break;
+            case CLASS_KEYWORD:
+              for (cu = 1; cu <= 255; cu++) {
+                if (reg_iswordc(cu)) {
+                  regmbc(cu);
+                }
+              }
+              break;
+            case CLASS_FNAME:
+              for (cu = 1; cu <= 255; cu++) {
+                if (vim_isfilec(cu)) {
+                  regmbc(cu);
+                }
+              }
+              break;
+            }
+          } else {
+            // produce a multibyte character, including any
+            // following composing characters.
+            startc = utf_ptr2char(regparse);
+            int len = utfc_ptr2len(regparse);
+            if (utf_char2len(startc) != len) {
+              // composing chars
+              startc = -1;
+            }
+            while (--len >= 0) {
+              regc(*regparse++);
+            }
+          }
+        }
+        regc(NUL);
+        prevchr_len = 1;                // last char was the ']'
+        if (*regparse != ']') {
+          EMSG_RET_NULL(_(e_toomsbra));                 // Cannot happen?
+        }
+        skipchr();                  // let's be friends with the lexer again
+        *flagp |= HASWIDTH | SIMPLE;
+        break;
+      } else if (reg_strict) {
+        EMSG2_RET_NULL(_(e_missingbracket), reg_magic > MAGIC_OFF);
+      }
+    }
+    FALLTHROUGH;
+
+  default: {
+    int len;
+
+    // A multi-byte character is handled as a separate atom if it's
+    // before a multi and when it's a composing char.
+    if (use_multibytecode(c)) {
+do_multibyte:
+      ret = regnode(MULTIBYTECODE);
+      regmbc(c);
+      *flagp |= HASWIDTH | SIMPLE;
+      break;
+    }
+
+    ret = regnode(EXACTLY);
+
+    // Append characters as long as:
+    // - there is no following multi, we then need the character in
+    //   front of it as a single character operand
+    // - not running into a Magic character
+    // - "one_exactly" is not set
+    // But always emit at least one character.  Might be a Multi,
+    // e.g., a "[" without matching "]".
+    for (len = 0; c != NUL && (len == 0
+                               || (re_multi_type(peekchr()) == NOT_MULTI
+                                   && !one_exactly
+                                   && !is_Magic(c))); len++) {
+      c = no_Magic(c);
+      {
+        regmbc(c);
+        {
+          int l;
+
+          // Need to get composing character too.
+          while (true) {
+            l = utf_ptr2len(regparse);
+            if (!utf_composinglike(regparse, regparse + l)) {
+              break;
+            }
+            regmbc(utf_ptr2char(regparse));
+            skipchr();
+          }
+        }
+      }
+      c = getchr();
+    }
+    ungetchr();
+
+    regc(NUL);
+    *flagp |= HASWIDTH;
+    if (len == 1) {
+      *flagp |= SIMPLE;
+    }
+  }
+  break;
+  }
+
+  return ret;
+}
+
+// Parse something followed by possible [*+=].
+//
+// Note that the branching code sequences used for = and the general cases
+// of * and + are somewhat optimized:  they use the same NOTHING node as
+// both the endmarker for their branch list and the body of the last branch.
+// It might seem that this node could be dispensed with entirely, but the
+// endmarker role is not redundant.
+static uint8_t *regpiece(int *flagp)
+{
+  uint8_t *ret;
+  int op;
+  uint8_t *next;
+  int flags;
+  int minval;
+  int maxval;
+
+  ret = regatom(&flags);
+  if (ret == NULL) {
+    return NULL;
+  }
+
+  op = peekchr();
+  if (re_multi_type(op) == NOT_MULTI) {
+    *flagp = flags;
+    return ret;
+  }
+  // default flags
+  *flagp = (WORST | SPSTART | (flags & (HASNL | HASLOOKBH)));
+
+  skipchr();
+  switch (op) {
+  case Magic('*'):
+    if (flags & SIMPLE) {
+      reginsert(STAR, ret);
+    } else {
+      // Emit x* as (x&|), where & means "self".
+      reginsert(BRANCH, ret);           // Either x
+      regoptail(ret, regnode(BACK));            // and loop
+      regoptail(ret, ret);              // back
+      regtail(ret, regnode(BRANCH));            // or
+      regtail(ret, regnode(NOTHING));           // null.
+    }
+    break;
+
+  case Magic('+'):
+    if (flags & SIMPLE) {
+      reginsert(PLUS, ret);
+    } else {
+      // Emit x+ as x(&|), where & means "self".
+      next = regnode(BRANCH);           // Either
+      regtail(ret, next);
+      regtail(regnode(BACK), ret);              // loop back
+      regtail(next, regnode(BRANCH));           // or
+      regtail(ret, regnode(NOTHING));           // null.
+    }
+    *flagp = (WORST | HASWIDTH | (flags & (HASNL | HASLOOKBH)));
+    break;
+
+  case Magic('@'): {
+    int lop = END;
+    int64_t nr = getdecchrs();
+
+    switch (no_Magic(getchr())) {
+    case '=':
+      lop = MATCH; break;                                 // \@=
+    case '!':
+      lop = NOMATCH; break;                               // \@!
+    case '>':
+      lop = SUBPAT; break;                                // \@>
+    case '<':
+      switch (no_Magic(getchr())) {
+      case '=':
+        lop = BEHIND; break;                               // \@<=
+      case '!':
+        lop = NOBEHIND; break;                             // \@<!
+      }
+    }
+    if (lop == END) {
+      EMSG2_RET_NULL(_(e_invalid_character_after_str_at),
+                     reg_magic == MAGIC_ALL);
+    }
+    // Look behind must match with behind_pos.
+    if (lop == BEHIND || lop == NOBEHIND) {
+      regtail(ret, regnode(BHPOS));
+      *flagp |= HASLOOKBH;
+    }
+    regtail(ret, regnode(END));             // operand ends
+    if (lop == BEHIND || lop == NOBEHIND) {
+      if (nr < 0) {
+        nr = 0;                 // no limit is same as zero limit
+      }
+      reginsert_nr(lop, (uint32_t)nr, ret);
+    } else {
+      reginsert(lop, ret);
+    }
+    break;
+  }
+
+  case Magic('?'):
+  case Magic('='):
+    // Emit x= as (x|)
+    reginsert(BRANCH, ret);                     // Either x
+    regtail(ret, regnode(BRANCH));              // or
+    next = regnode(NOTHING);                    // null.
+    regtail(ret, next);
+    regoptail(ret, next);
+    break;
+
+  case Magic('{'):
+    if (!read_limits(&minval, &maxval)) {
+      return NULL;
+    }
+    if (flags & SIMPLE) {
+      reginsert(BRACE_SIMPLE, ret);
+      reginsert_limits(BRACE_LIMITS, minval, maxval, ret);
+    } else {
+      if (num_complex_braces >= 10) {
+        EMSG2_RET_NULL(_("E60: Too many complex %s{...}s"),
+                       reg_magic == MAGIC_ALL);
+      }
+      reginsert(BRACE_COMPLEX + num_complex_braces, ret);
+      regoptail(ret, regnode(BACK));
+      regoptail(ret, ret);
+      reginsert_limits(BRACE_LIMITS, minval, maxval, ret);
+      num_complex_braces++;
+    }
+    if (minval > 0 && maxval > 0) {
+      *flagp = (HASWIDTH | (flags & (HASNL | HASLOOKBH)));
+    }
+    break;
+  }
+  if (re_multi_type(peekchr()) != NOT_MULTI) {
+    // Can't have a multi follow a multi.
+    if (peekchr() == Magic('*')) {
+      EMSG2_RET_NULL(_("E61: Nested %s*"), reg_magic >= MAGIC_ON);
+    }
+    EMSG3_RET_NULL(_("E62: Nested %s%c"), reg_magic == MAGIC_ALL, no_Magic(peekchr()));
+  }
+
+  return ret;
+}
+
+// Parse one alternative of an | or & operator.
+// Implements the concatenation operator.
+static uint8_t *regconcat(int *flagp)
+{
+  uint8_t *first = NULL;
+  uint8_t *chain = NULL;
+  uint8_t *latest;
+  int flags;
+  int cont = true;
+
+  *flagp = WORST;               // Tentatively.
+
+  while (cont) {
+    switch (peekchr()) {
+    case NUL:
+    case Magic('|'):
+    case Magic('&'):
+    case Magic(')'):
+      cont = false;
+      break;
+    case Magic('Z'):
+      regflags |= RF_ICOMBINE;
+      skipchr_keepstart();
+      break;
+    case Magic('c'):
+      regflags |= RF_ICASE;
+      skipchr_keepstart();
+      break;
+    case Magic('C'):
+      regflags |= RF_NOICASE;
+      skipchr_keepstart();
+      break;
+    case Magic('v'):
+      reg_magic = MAGIC_ALL;
+      skipchr_keepstart();
+      curchr = -1;
+      break;
+    case Magic('m'):
+      reg_magic = MAGIC_ON;
+      skipchr_keepstart();
+      curchr = -1;
+      break;
+    case Magic('M'):
+      reg_magic = MAGIC_OFF;
+      skipchr_keepstart();
+      curchr = -1;
+      break;
+    case Magic('V'):
+      reg_magic = MAGIC_NONE;
+      skipchr_keepstart();
+      curchr = -1;
+      break;
+    default:
+      latest = regpiece(&flags);
+      if (latest == NULL || reg_toolong) {
+        return NULL;
+      }
+      *flagp |= flags & (HASWIDTH | HASNL | HASLOOKBH);
+      if (chain == NULL) {                      // First piece.
+        *flagp |= flags & SPSTART;
+      } else {
+        regtail(chain, latest);
+      }
+      chain = latest;
+      if (first == NULL) {
+        first = latest;
+      }
+      break;
+    }
+  }
+  if (first == NULL) {          // Loop ran zero times.
+    first = regnode(NOTHING);
+  }
+  return first;
+}
+
+// Parse one alternative of an | operator.
+// Implements the & operator.
+static uint8_t *regbranch(int *flagp)
+{
+  uint8_t *ret;
+  uint8_t *chain = NULL;
+  uint8_t *latest;
+  int flags;
+
+  *flagp = WORST | HASNL;               // Tentatively.
+
+  ret = regnode(BRANCH);
+  while (true) {
+    latest = regconcat(&flags);
+    if (latest == NULL) {
+      return NULL;
+    }
+    // If one of the branches has width, the whole thing has.  If one of
+    // the branches anchors at start-of-line, the whole thing does.
+    // If one of the branches uses look-behind, the whole thing does.
+    *flagp |= flags & (HASWIDTH | SPSTART | HASLOOKBH);
+    // If one of the branches doesn't match a line-break, the whole thing
+    // doesn't.
+    *flagp &= ~HASNL | (flags & HASNL);
+    if (chain != NULL) {
+      regtail(chain, latest);
+    }
+    if (peekchr() != Magic('&')) {
+      break;
+    }
+    skipchr();
+    regtail(latest, regnode(END));     // operand ends
+    if (reg_toolong) {
+      break;
+    }
+    reginsert(MATCH, latest);
+    chain = latest;
+  }
+
+  return ret;
+}
+
+/// Parse regular expression, i.e. main body or parenthesized thing.
+///
+/// Caller must absorb opening parenthesis.
+///
+/// Combining parenthesis handling with the base level of regular expression
+/// is a trifle forced, but the need to tie the tails of the branches to what
+/// follows makes it hard to avoid.
+///
+/// @param paren  REG_NOPAREN, REG_PAREN, REG_NPAREN or REG_ZPAREN
+static uint8_t *reg(int paren, int *flagp)
+{
+  uint8_t *ret;
+  uint8_t *br;
+  uint8_t *ender;
+  int parno = 0;
+  int flags;
+
+  *flagp = HASWIDTH;            // Tentatively.
+
+  if (paren == REG_ZPAREN) {
+    // Make a ZOPEN node.
+    if (regnzpar >= NSUBEXP) {
+      EMSG_RET_NULL(_("E50: Too many \\z("));
+    }
+    parno = regnzpar;
+    regnzpar++;
+    ret = regnode(ZOPEN + parno);
+  } else if (paren == REG_PAREN) {
+    // Make a MOPEN node.
+    if (regnpar >= NSUBEXP) {
+      EMSG2_RET_NULL(_("E51: Too many %s("), reg_magic == MAGIC_ALL);
+    }
+    parno = regnpar;
+    regnpar++;
+    ret = regnode(MOPEN + parno);
+  } else if (paren == REG_NPAREN) {
+    // Make a NOPEN node.
+    ret = regnode(NOPEN);
+  } else {
+    ret = NULL;
+  }
+
+  // Pick up the branches, linking them together.
+  br = regbranch(&flags);
+  if (br == NULL) {
+    return NULL;
+  }
+  if (ret != NULL) {
+    regtail(ret, br);           // [MZ]OPEN -> first.
+  } else {
+    ret = br;
+  }
+  // If one of the branches can be zero-width, the whole thing can.
+  // If one of the branches has * at start or matches a line-break, the
+  // whole thing can.
+  if (!(flags & HASWIDTH)) {
+    *flagp &= ~HASWIDTH;
+  }
+  *flagp |= flags & (SPSTART | HASNL | HASLOOKBH);
+  while (peekchr() == Magic('|')) {
+    skipchr();
+    br = regbranch(&flags);
+    if (br == NULL || reg_toolong) {
+      return NULL;
+    }
+    regtail(ret, br);           // BRANCH -> BRANCH.
+    if (!(flags & HASWIDTH)) {
+      *flagp &= ~HASWIDTH;
+    }
+    *flagp |= flags & (SPSTART | HASNL | HASLOOKBH);
+  }
+
+  // Make a closing node, and hook it on the end.
+  ender = regnode(paren == REG_ZPAREN ? ZCLOSE + parno
+                                      : paren == REG_PAREN ? MCLOSE + parno
+                                                           : paren == REG_NPAREN ? NCLOSE : END);
+  regtail(ret, ender);
+
+  // Hook the tails of the branches to the closing node.
+  for (br = ret; br != NULL; br = regnext(br)) {
+    regoptail(br, ender);
+  }
+
+  // Check for proper termination.
+  if (paren != REG_NOPAREN && getchr() != Magic(')')) {
+    if (paren == REG_ZPAREN) {
+      EMSG_RET_NULL(_("E52: Unmatched \\z("));
+    } else if (paren == REG_NPAREN) {
+      EMSG2_RET_NULL(_(e_unmatchedpp), reg_magic == MAGIC_ALL);
+    } else {
+      EMSG2_RET_NULL(_(e_unmatchedp), reg_magic == MAGIC_ALL);
+    }
+  } else if (paren == REG_NOPAREN && peekchr() != NUL) {
+    if (curchr == Magic(')')) {
+      EMSG2_RET_NULL(_(e_unmatchedpar), reg_magic == MAGIC_ALL);
+    } else {
+      EMSG_RET_NULL(_(e_trailing));             // "Can't happen".
+    }
+    // NOTREACHED
+  }
+  // Here we set the flag allowing back references to this set of
+  // parentheses.
+  if (paren == REG_PAREN) {
+    had_endbrace[parno] = true;  // have seen the close paren
+  }
+  return ret;
+}
+
+// bt_regcomp() - compile a regular expression into internal code for the
+// traditional back track matcher.
+// Returns the program in allocated space.  Returns NULL for an error.
+//
+// We can't allocate space until we know how big the compiled form will be,
+// but we can't compile it (and thus know how big it is) until we've got a
+// place to put the code.  So we cheat:  we compile it twice, once with code
+// generation turned off and size counting turned on, and once "for real".
+// This also means that we don't allocate space until we are sure that the
+// thing really will compile successfully, and we never have to move the
+// code and thus invalidate pointers into it.  (Note that it has to be in
+// one piece because free() must be able to free it all.)
+//
+// Whether upper/lower case is to be ignored is decided when executing the
+// program, it does not matter here.
+//
+// Beware that the optimization-preparation code in here knows about some
+// of the structure of the compiled regexp.
+// "re_flags": RE_MAGIC and/or RE_STRING.
+static regprog_T *bt_regcomp(uint8_t *expr, int re_flags)
+{
+  uint8_t *scan;
+  uint8_t *longest;
+  int len;
+  int flags;
+
+  if (expr == NULL) {
+    IEMSG_RET_NULL(_(e_null));
+  }
+
+  init_class_tab();
+
+  // First pass: determine size, legality.
+  regcomp_start(expr, re_flags);
+  regcode = JUST_CALC_SIZE;
+  regc(REGMAGIC);
+  if (reg(REG_NOPAREN, &flags) == NULL) {
+    return NULL;
+  }
+
+  // Allocate space.
+  bt_regprog_T *r = xmalloc(offsetof(bt_regprog_T, program) + (size_t)regsize);
+  r->re_in_use = false;
+
+  // Second pass: emit code.
+  regcomp_start(expr, re_flags);
+  regcode = r->program;
+  regc(REGMAGIC);
+  if (reg(REG_NOPAREN, &flags) == NULL || reg_toolong) {
+    xfree(r);
+    if (reg_toolong) {
+      EMSG_RET_NULL(_("E339: Pattern too long"));
+    }
+    return NULL;
+  }
+
+  // Dig out information for optimizations.
+  r->regstart = NUL;            // Worst-case defaults.
+  r->reganch = 0;
+  r->regmust = NULL;
+  r->regmlen = 0;
+  r->regflags = regflags;
+  if (flags & HASNL) {
+    r->regflags |= RF_HASNL;
+  }
+  if (flags & HASLOOKBH) {
+    r->regflags |= RF_LOOKBH;
+  }
+  // Remember whether this pattern has any \z specials in it.
+  r->reghasz = (uint8_t)re_has_z;
+  scan = r->program + 1;        // First BRANCH.
+  if (OP(regnext(scan)) == END) {   // Only one top-level choice.
+    scan = OPERAND(scan);
+
+    // Starting-point info.
+    if (OP(scan) == BOL || OP(scan) == RE_BOF) {
+      r->reganch++;
+      scan = regnext(scan);
+    }
+
+    if (OP(scan) == EXACTLY) {
+      r->regstart = utf_ptr2char((char *)OPERAND(scan));
+    } else if (OP(scan) == BOW
+               || OP(scan) == EOW
+               || OP(scan) == NOTHING
+               || OP(scan) == MOPEN + 0 || OP(scan) == NOPEN
+               || OP(scan) == MCLOSE + 0 || OP(scan) == NCLOSE) {
+      uint8_t *regnext_scan = regnext(scan);
+      if (OP(regnext_scan) == EXACTLY) {
+        r->regstart = utf_ptr2char((char *)OPERAND(regnext_scan));
+      }
+    }
+
+    // If there's something expensive in the r.e., find the longest
+    // literal string that must appear and make it the regmust.  Resolve
+    // ties in favor of later strings, since the regstart check works
+    // with the beginning of the r.e. and avoiding duplication
+    // strengthens checking.  Not a strong reason, but sufficient in the
+    // absence of others.
+
+    // When the r.e. starts with BOW, it is faster to look for a regmust
+    // first. Used a lot for "#" and "*" commands. (Added by mool).
+    if ((flags & SPSTART || OP(scan) == BOW || OP(scan) == EOW)
+        && !(flags & HASNL)) {
+      longest = NULL;
+      len = 0;
+      for (; scan != NULL; scan = regnext(scan)) {
+        if (OP(scan) == EXACTLY && strlen((char *)OPERAND(scan)) >= (size_t)len) {
+          longest = OPERAND(scan);
+          len = (int)strlen((char *)OPERAND(scan));
+        }
+      }
+      r->regmust = longest;
+      r->regmlen = len;
+    }
+  }
+#ifdef BT_REGEXP_DUMP
+  regdump(expr, r);
+#endif
+  r->engine = &bt_regengine;
+  return (regprog_T *)r;
+}
+
+// Check if during the previous call to vim_regcomp the EOL item "$" has been
+// found.  This is messy, but it works fine.
+int vim_regcomp_had_eol(void)
+{
+  return had_eol;
+}
+
+// Get a number after a backslash that is inside [].
+// When nothing is recognized return a backslash.
+static int coll_get_char(void)
+{
+  int64_t nr = -1;
+
+  switch (*regparse++) {
+  case 'd':
+    nr = getdecchrs(); break;
+  case 'o':
+    nr = getoctchrs(); break;
+  case 'x':
+    nr = gethexchrs(2); break;
+  case 'u':
+    nr = gethexchrs(4); break;
+  case 'U':
+    nr = gethexchrs(8); break;
+  }
+  if (nr < 0 || nr > INT_MAX) {
+    // If getting the number fails be backwards compatible: the character
+    // is a backslash.
+    regparse--;
+    nr = '\\';
+  }
+  return (int)nr;
+}
+
+// Free a compiled regexp program, returned by bt_regcomp().
+static void bt_regfree(regprog_T *prog)
+{
+  xfree(prog);
+}
+
+#define ADVANCE_REGINPUT() MB_PTR_ADV(rex.input)
+
+// The arguments from BRACE_LIMITS are stored here.  They are actually local
+// to regmatch(), but they are here to reduce the amount of stack space used
+// (it can be called recursively many times).
+static int64_t bl_minval;
+static int64_t bl_maxval;
+
+// Save the input line and position in a regsave_T.
+static void reg_save(regsave_T *save, garray_T *gap)
+  FUNC_ATTR_NONNULL_ALL
+{
+  if (REG_MULTI) {
+    save->rs_u.pos.col = (colnr_T)(rex.input - rex.line);
+    save->rs_u.pos.lnum = rex.lnum;
+  } else {
+    save->rs_u.ptr = rex.input;
+  }
+  save->rs_len = gap->ga_len;
+}
+
+// Restore the input line and position from a regsave_T.
+static void reg_restore(regsave_T *save, garray_T *gap)
+  FUNC_ATTR_NONNULL_ALL
+{
+  if (REG_MULTI) {
+    if (rex.lnum != save->rs_u.pos.lnum) {
+      // only call reg_getline() when the line number changed to save
+      // a bit of time
+      rex.lnum = save->rs_u.pos.lnum;
+      rex.line = (uint8_t *)reg_getline(rex.lnum);
+    }
+    rex.input = rex.line + save->rs_u.pos.col;
+  } else {
+    rex.input = save->rs_u.ptr;
+  }
+  gap->ga_len = save->rs_len;
+}
+
+// Return true if current position is equal to saved position.
+static bool reg_save_equal(const regsave_T *save)
+  FUNC_ATTR_NONNULL_ALL
+{
+  if (REG_MULTI) {
+    return rex.lnum == save->rs_u.pos.lnum
+           && rex.input == rex.line + save->rs_u.pos.col;
+  }
+  return rex.input == save->rs_u.ptr;
+}
+
+// Save the sub-expressions before attempting a match.
+#define save_se(savep, posp, pp) \
+  REG_MULTI ? save_se_multi((savep), (posp)) : save_se_one((savep), (pp))
+
+// After a failed match restore the sub-expressions.
+#define restore_se(savep, posp, pp) { \
+  if (REG_MULTI)  /* NOLINT(readability/braces) */ \
+  *(posp) = (savep)->se_u.pos; \
+  else  /* NOLINT */ \
+  *(pp) = (savep)->se_u.ptr; }
+
+// Tentatively set the sub-expression start to the current position (after
+// calling regmatch() they will have changed).  Need to save the existing
+// values for when there is no match.
+// Use se_save() to use pointer (save_se_multi()) or position (save_se_one()),
+// depending on REG_MULTI.
+static void save_se_multi(save_se_T *savep, lpos_T *posp)
+{
+  savep->se_u.pos = *posp;
+  posp->lnum = rex.lnum;
+  posp->col = (colnr_T)(rex.input - rex.line);
+}
+
+static void save_se_one(save_se_T *savep, uint8_t **pp)
+{
+  savep->se_u.ptr = *pp;
+  *pp = rex.input;
+}
+
+/// regrepeat - repeatedly match something simple, return how many.
+/// Advances rex.input (and rex.lnum) to just after the matched chars.
+///
+/// @param maxcount  maximum number of matches allowed
+static int regrepeat(uint8_t *p, int64_t maxcount)
+{
+  int64_t count = 0;
+  uint8_t *opnd;
+  int mask;
+  int testval = 0;
+
+  uint8_t *scan = rex.input;  // Make local copy of rex.input for speed.
+  opnd = OPERAND(p);
+  switch (OP(p)) {
+  case ANY:
+  case ANY + ADD_NL:
+    while (count < maxcount) {
+      // Matching anything means we continue until end-of-line (or
+      // end-of-file for ANY + ADD_NL), only limited by maxcount.
+      while (*scan != NUL && count < maxcount) {
+        count++;
+        MB_PTR_ADV(scan);
+      }
+      if (!REG_MULTI || !WITH_NL(OP(p)) || rex.lnum > rex.reg_maxline
+          || rex.reg_line_lbr || count == maxcount) {
+        break;
+      }
+      count++;  // count the line-break
+      reg_nextline();
+      scan = rex.input;
+      if (got_int) {
+        break;
+      }
+    }
+    break;
+
+  case IDENT:
+  case IDENT + ADD_NL:
+    testval = 1;
+    FALLTHROUGH;
+  case SIDENT:
+  case SIDENT + ADD_NL:
+    while (count < maxcount) {
+      if (vim_isIDc(utf_ptr2char((char *)scan)) && (testval || !ascii_isdigit(*scan))) {
+        MB_PTR_ADV(scan);
+      } else if (*scan == NUL) {
+        if (!REG_MULTI || !WITH_NL(OP(p)) || rex.lnum > rex.reg_maxline
+            || rex.reg_line_lbr) {
+          break;
+        }
+        reg_nextline();
+        scan = rex.input;
+        if (got_int) {
+          break;
+        }
+      } else if (rex.reg_line_lbr && *scan == '\n' && WITH_NL(OP(p))) {
+        scan++;
+      } else {
+        break;
+      }
+      count++;
+    }
+    break;
+
+  case KWORD:
+  case KWORD + ADD_NL:
+    testval = 1;
+    FALLTHROUGH;
+  case SKWORD:
+  case SKWORD + ADD_NL:
+    while (count < maxcount) {
+      if (vim_iswordp_buf((char *)scan, rex.reg_buf)
+          && (testval || !ascii_isdigit(*scan))) {
+        MB_PTR_ADV(scan);
+      } else if (*scan == NUL) {
+        if (!REG_MULTI || !WITH_NL(OP(p)) || rex.lnum > rex.reg_maxline
+            || rex.reg_line_lbr) {
+          break;
+        }
+        reg_nextline();
+        scan = rex.input;
+        if (got_int) {
+          break;
+        }
+      } else if (rex.reg_line_lbr && *scan == '\n' && WITH_NL(OP(p))) {
+        scan++;
+      } else {
+        break;
+      }
+      count++;
+    }
+    break;
+
+  case FNAME:
+  case FNAME + ADD_NL:
+    testval = 1;
+    FALLTHROUGH;
+  case SFNAME:
+  case SFNAME + ADD_NL:
+    while (count < maxcount) {
+      if (vim_isfilec(utf_ptr2char((char *)scan)) && (testval || !ascii_isdigit(*scan))) {
+        MB_PTR_ADV(scan);
+      } else if (*scan == NUL) {
+        if (!REG_MULTI || !WITH_NL(OP(p)) || rex.lnum > rex.reg_maxline
+            || rex.reg_line_lbr) {
+          break;
+        }
+        reg_nextline();
+        scan = rex.input;
+        if (got_int) {
+          break;
+        }
+      } else if (rex.reg_line_lbr && *scan == '\n' && WITH_NL(OP(p))) {
+        scan++;
+      } else {
+        break;
+      }
+      count++;
+    }
+    break;
+
+  case PRINT:
+  case PRINT + ADD_NL:
+    testval = 1;
+    FALLTHROUGH;
+  case SPRINT:
+  case SPRINT + ADD_NL:
+    while (count < maxcount) {
+      if (*scan == NUL) {
+        if (!REG_MULTI || !WITH_NL(OP(p)) || rex.lnum > rex.reg_maxline
+            || rex.reg_line_lbr) {
+          break;
+        }
+        reg_nextline();
+        scan = rex.input;
+        if (got_int) {
+          break;
+        }
+      } else if (vim_isprintc(utf_ptr2char((char *)scan)) == 1
+                 && (testval || !ascii_isdigit(*scan))) {
+        MB_PTR_ADV(scan);
+      } else if (rex.reg_line_lbr && *scan == '\n' && WITH_NL(OP(p))) {
+        scan++;
+      } else {
+        break;
+      }
+      count++;
+    }
+    break;
+
+  case WHITE:
+  case WHITE + ADD_NL:
+    testval = mask = RI_WHITE;
+do_class:
+    while (count < maxcount) {
+      int l;
+      if (*scan == NUL) {
+        if (!REG_MULTI || !WITH_NL(OP(p)) || rex.lnum > rex.reg_maxline
+            || rex.reg_line_lbr) {
+          break;
+        }
+        reg_nextline();
+        scan = rex.input;
+        if (got_int) {
+          break;
+        }
+      } else if ((l = utfc_ptr2len((char *)scan)) > 1) {
+        if (testval != 0) {
+          break;
+        }
+        scan += l;
+      } else if ((class_tab[*scan] & mask) == testval) {
+        scan++;
+      } else if (rex.reg_line_lbr && *scan == '\n' && WITH_NL(OP(p))) {
+        scan++;
+      } else {
+        break;
+      }
+      count++;
+    }
+    break;
+
+  case NWHITE:
+  case NWHITE + ADD_NL:
+    mask = RI_WHITE;
+    goto do_class;
+  case DIGIT:
+  case DIGIT + ADD_NL:
+    testval = mask = RI_DIGIT;
+    goto do_class;
+  case NDIGIT:
+  case NDIGIT + ADD_NL:
+    mask = RI_DIGIT;
+    goto do_class;
+  case HEX:
+  case HEX + ADD_NL:
+    testval = mask = RI_HEX;
+    goto do_class;
+  case NHEX:
+  case NHEX + ADD_NL:
+    mask = RI_HEX;
+    goto do_class;
+  case OCTAL:
+  case OCTAL + ADD_NL:
+    testval = mask = RI_OCTAL;
+    goto do_class;
+  case NOCTAL:
+  case NOCTAL + ADD_NL:
+    mask = RI_OCTAL;
+    goto do_class;
+  case WORD:
+  case WORD + ADD_NL:
+    testval = mask = RI_WORD;
+    goto do_class;
+  case NWORD:
+  case NWORD + ADD_NL:
+    mask = RI_WORD;
+    goto do_class;
+  case HEAD:
+  case HEAD + ADD_NL:
+    testval = mask = RI_HEAD;
+    goto do_class;
+  case NHEAD:
+  case NHEAD + ADD_NL:
+    mask = RI_HEAD;
+    goto do_class;
+  case ALPHA:
+  case ALPHA + ADD_NL:
+    testval = mask = RI_ALPHA;
+    goto do_class;
+  case NALPHA:
+  case NALPHA + ADD_NL:
+    mask = RI_ALPHA;
+    goto do_class;
+  case LOWER:
+  case LOWER + ADD_NL:
+    testval = mask = RI_LOWER;
+    goto do_class;
+  case NLOWER:
+  case NLOWER + ADD_NL:
+    mask = RI_LOWER;
+    goto do_class;
+  case UPPER:
+  case UPPER + ADD_NL:
+    testval = mask = RI_UPPER;
+    goto do_class;
+  case NUPPER:
+  case NUPPER + ADD_NL:
+    mask = RI_UPPER;
+    goto do_class;
+
+  case EXACTLY: {
+    int cu, cl;
+
+    // This doesn't do a multi-byte character, because a MULTIBYTECODE
+    // would have been used for it.  It does handle single-byte
+    // characters, such as latin1.
+    if (rex.reg_ic) {
+      cu = mb_toupper(*opnd);
+      cl = mb_tolower(*opnd);
+      while (count < maxcount && (*scan == cu || *scan == cl)) {
+        count++;
+        scan++;
+      }
+    } else {
+      cu = *opnd;
+      while (count < maxcount && *scan == cu) {
+        count++;
+        scan++;
+      }
+    }
+    break;
+  }
+
+  case MULTIBYTECODE: {
+    int i, len, cf = 0;
+
+    // Safety check (just in case 'encoding' was changed since
+    // compiling the program).
+    if ((len = utfc_ptr2len((char *)opnd)) > 1) {
+      if (rex.reg_ic) {
+        cf = utf_fold(utf_ptr2char((char *)opnd));
+      }
+      while (count < maxcount && utfc_ptr2len((char *)scan) >= len) {
+        for (i = 0; i < len; i++) {
+          if (opnd[i] != scan[i]) {
+            break;
+          }
+        }
+        if (i < len && (!rex.reg_ic
+                        || utf_fold(utf_ptr2char((char *)scan)) != cf)) {
+          break;
+        }
+        scan += len;
+        count++;
+      }
+    }
+  }
+  break;
+
+  case ANYOF:
+  case ANYOF + ADD_NL:
+    testval = 1;
+    FALLTHROUGH;
+
+  case ANYBUT:
+  case ANYBUT + ADD_NL:
+    while (count < maxcount) {
+      int len;
+      if (*scan == NUL) {
+        if (!REG_MULTI || !WITH_NL(OP(p)) || rex.lnum > rex.reg_maxline
+            || rex.reg_line_lbr) {
+          break;
+        }
+        reg_nextline();
+        scan = rex.input;
+        if (got_int) {
+          break;
+        }
+      } else if (rex.reg_line_lbr && *scan == '\n' && WITH_NL(OP(p))) {
+        scan++;
+      } else if ((len = utfc_ptr2len((char *)scan)) > 1) {
+        if ((cstrchr((char *)opnd, utf_ptr2char((char *)scan)) == NULL) == testval) {
+          break;
+        }
+        scan += len;
+      } else {
+        if ((cstrchr((char *)opnd, *scan) == NULL) == testval) {
+          break;
+        }
+        scan++;
+      }
+      count++;
+    }
+    break;
+
+  case NEWL:
+    while (count < maxcount
+           && ((*scan == NUL && rex.lnum <= rex.reg_maxline && !rex.reg_line_lbr
+                && REG_MULTI) || (*scan == '\n' && rex.reg_line_lbr))) {
+      count++;
+      if (rex.reg_line_lbr) {
+        ADVANCE_REGINPUT();
+      } else {
+        reg_nextline();
+      }
+      scan = rex.input;
+      if (got_int) {
+        break;
+      }
+    }
+    break;
+
+  default:  // Oh dear.  Called inappropriately.
+    iemsg(_(e_re_corr));
+#ifdef REGEXP_DEBUG
+    printf("Called regrepeat with op code %d\n", OP(p));
+#endif
+    break;
+  }
+
+  rex.input = scan;
+
+  return (int)count;
+}
+
+// Push an item onto the regstack.
+// Returns pointer to new item.  Returns NULL when out of memory.
+static regitem_T *regstack_push(regstate_T state, uint8_t *scan)
+{
+  regitem_T *rp;
+
+  if ((int64_t)((unsigned)regstack.ga_len >> 10) >= p_mmp) {
+    emsg(_(e_pattern_uses_more_memory_than_maxmempattern));
+    return NULL;
+  }
+  ga_grow(&regstack, sizeof(regitem_T));
+
+  rp = (regitem_T *)((char *)regstack.ga_data + regstack.ga_len);
+  rp->rs_state = state;
+  rp->rs_scan = scan;
+
+  regstack.ga_len += (int)sizeof(regitem_T);
+  return rp;
+}
+
+// Pop an item from the regstack.
+static void regstack_pop(uint8_t **scan)
+{
+  regitem_T *rp;
+
+  rp = (regitem_T *)((char *)regstack.ga_data + regstack.ga_len) - 1;
+  *scan = rp->rs_scan;
+
+  regstack.ga_len -= (int)sizeof(regitem_T);
+}
+
+// Save the current subexpr to "bp", so that they can be restored
+// later by restore_subexpr().
+static void save_subexpr(regbehind_T *bp)
+  FUNC_ATTR_NONNULL_ALL
+{
+  // When "rex.need_clear_subexpr" is set we don't need to save the values, only
+  // remember that this flag needs to be set again when restoring.
+  bp->save_need_clear_subexpr = rex.need_clear_subexpr;
+  if (rex.need_clear_subexpr) {
+    return;
+  }
+
+  for (int i = 0; i < NSUBEXP; i++) {
+    if (REG_MULTI) {
+      bp->save_start[i].se_u.pos = rex.reg_startpos[i];
+      bp->save_end[i].se_u.pos = rex.reg_endpos[i];
+    } else {
+      bp->save_start[i].se_u.ptr = rex.reg_startp[i];
+      bp->save_end[i].se_u.ptr = rex.reg_endp[i];
+    }
+  }
+}
+
+// Restore the subexpr from "bp".
+static void restore_subexpr(regbehind_T *bp)
+  FUNC_ATTR_NONNULL_ALL
+{
+  // Only need to restore saved values when they are not to be cleared.
+  rex.need_clear_subexpr = bp->save_need_clear_subexpr;
+  if (rex.need_clear_subexpr) {
+    return;
+  }
+
+  for (int i = 0; i < NSUBEXP; i++) {
+    if (REG_MULTI) {
+      rex.reg_startpos[i] = bp->save_start[i].se_u.pos;
+      rex.reg_endpos[i] = bp->save_end[i].se_u.pos;
+    } else {
+      rex.reg_startp[i] = bp->save_start[i].se_u.ptr;
+      rex.reg_endp[i] = bp->save_end[i].se_u.ptr;
+    }
+  }
+}
+/// Main matching routine
+///
+/// Conceptually the strategy is simple: Check to see whether the current node
+/// matches, push an item onto the regstack and loop to see whether the rest
+/// matches, and then act accordingly.  In practice we make some effort to
+/// avoid using the regstack, in particular by going through "ordinary" nodes
+/// (that don't need to know whether the rest of the match failed) by a nested
+/// loop.
+///
+/// @param scan       Current node.
+/// @param tm         timeout limit or NULL
+/// @param timed_out  flag set on timeout or NULL
+///
+/// @return - true when there is a match.  Leaves rex.input and rex.lnum
+///         just after the last matched character.
+///         - false when there is no match.  Leaves rex.input and rex.lnum in an
+///         undefined state!
+static bool regmatch(uint8_t *scan, const proftime_T *tm, int *timed_out)
+{
+  uint8_t *next;          // Next node.
+  int op;
+  int c;
+  regitem_T *rp;
+  int no;
+  int status;                   // one of the RA_ values:
+  int tm_count = 0;
+
+  // Make "regstack" and "backpos" empty.  They are allocated and freed in
+  // bt_regexec_both() to reduce malloc()/free() calls.
+  regstack.ga_len = 0;
+  backpos.ga_len = 0;
+
+  // Repeat until "regstack" is empty.
+  while (true) {
+    // Some patterns may take a long time to match, e.g., "\([a-z]\+\)\+Q".
+    // Allow interrupting them with CTRL-C.
+    reg_breakcheck();
+
+#ifdef REGEXP_DEBUG
+    if (scan != NULL && regnarrate) {
+      os_errmsg((char *)regprop(scan));
+      os_errmsg("(\n");
+    }
+#endif
+
+    // Repeat for items that can be matched sequentially, without using the
+    // regstack.
+    while (true) {
+      if (got_int || scan == NULL) {
+        status = RA_FAIL;
+        break;
+      }
+      // Check for timeout once in a 100 times to avoid overhead.
+      if (tm != NULL && ++tm_count == 100) {
+        tm_count = 0;
+        if (profile_passed_limit(*tm)) {
+          if (timed_out != NULL) {
+            *timed_out = true;
+          }
+          status = RA_FAIL;
+          break;
+        }
+      }
+      status = RA_CONT;
+
+#ifdef REGEXP_DEBUG
+      if (regnarrate) {
+        os_errmsg((char *)regprop(scan));
+        os_errmsg("...\n");
+        if (re_extmatch_in != NULL) {
+          int i;
+
+          os_errmsg(_("External submatches:\n"));
+          for (i = 0; i < NSUBEXP; i++) {
+            os_errmsg("    \"");
+            if (re_extmatch_in->matches[i] != NULL) {
+              os_errmsg((char *)re_extmatch_in->matches[i]);
+            }
+            os_errmsg("\"\n");
+          }
+        }
+      }
+#endif
+      next = regnext(scan);
+
+      op = OP(scan);
+      // Check for character class with NL added.
+      if (!rex.reg_line_lbr && WITH_NL(op) && REG_MULTI
+          && *rex.input == NUL && rex.lnum <= rex.reg_maxline) {
+        reg_nextline();
+      } else if (rex.reg_line_lbr && WITH_NL(op) && *rex.input == '\n') {
+        ADVANCE_REGINPUT();
+      } else {
+        if (WITH_NL(op)) {
+          op -= ADD_NL;
+        }
+        c = utf_ptr2char((char *)rex.input);
+        switch (op) {
+        case BOL:
+          if (rex.input != rex.line) {
+            status = RA_NOMATCH;
+          }
+          break;
+
+        case EOL:
+          if (c != NUL) {
+            status = RA_NOMATCH;
+          }
+          break;
+
+        case RE_BOF:
+          // We're not at the beginning of the file when below the first
+          // line where we started, not at the start of the line or we
+          // didn't start at the first line of the buffer.
+          if (rex.lnum != 0 || rex.input != rex.line
+              || (REG_MULTI && rex.reg_firstlnum > 1)) {
+            status = RA_NOMATCH;
+          }
+          break;
+
+        case RE_EOF:
+          if (rex.lnum != rex.reg_maxline || c != NUL) {
+            status = RA_NOMATCH;
+          }
+          break;
+
+        case CURSOR:
+          // Check if the buffer is in a window and compare the
+          // rex.reg_win->w_cursor position to the match position.
+          if (rex.reg_win == NULL
+              || (rex.lnum + rex.reg_firstlnum != rex.reg_win->w_cursor.lnum)
+              || ((colnr_T)(rex.input - rex.line) !=
+                  rex.reg_win->w_cursor.col)) {
+            status = RA_NOMATCH;
+          }
+          break;
+
+        case RE_MARK:
+          // Compare the mark position to the match position.
+        {
+          int mark = OPERAND(scan)[0];
+          int cmp = OPERAND(scan)[1];
+          pos_T *pos;
+          size_t col = REG_MULTI ? (size_t)(rex.input - rex.line) : 0;
+          fmark_T *fm = mark_get(rex.reg_buf, curwin, NULL, kMarkBufLocal, mark);
+
+          // Line may have been freed, get it again.
+          if (REG_MULTI) {
+            rex.line = (uint8_t *)reg_getline(rex.lnum);
+            rex.input = rex.line + col;
+          }
+
+          if (fm == NULL                    // mark doesn't exist
+              || fm->mark.lnum <= 0) {           // mark isn't set in reg_buf
+            status = RA_NOMATCH;
+          } else {
+            pos = &fm->mark;
+            const colnr_T pos_col = pos->lnum == rex.lnum + rex.reg_firstlnum
+                                    && pos->col == MAXCOL
+                                    ? (colnr_T)strlen(reg_getline(pos->lnum - rex.reg_firstlnum))
+                                    : pos->col;
+
+            if (pos->lnum == rex.lnum + rex.reg_firstlnum
+                ? (pos_col == (colnr_T)(rex.input - rex.line)
+                   ? (cmp == '<' || cmp == '>')
+                   : (pos_col < (colnr_T)(rex.input - rex.line)
+                      ? cmp != '>'
+                      : cmp != '<'))
+                : (pos->lnum < rex.lnum + rex.reg_firstlnum
+                   ? cmp != '>'
+                   : cmp != '<')) {
+              status = RA_NOMATCH;
+            }
+          }
+        }
+        break;
+
+        case RE_VISUAL:
+          if (!reg_match_visual()) {
+            status = RA_NOMATCH;
+          }
+          break;
+
+        case RE_LNUM:
+          assert(rex.lnum + rex.reg_firstlnum >= 0
+                 && (uintmax_t)(rex.lnum + rex.reg_firstlnum) <= UINT32_MAX);
+          if (!REG_MULTI
+              || !re_num_cmp((uint32_t)(rex.lnum + rex.reg_firstlnum), scan)) {
+            status = RA_NOMATCH;
+          }
+          break;
+
+        case RE_COL:
+          assert(rex.input - rex.line + 1 >= 0
+                 && (uintmax_t)(rex.input - rex.line + 1) <= UINT32_MAX);
+          if (!re_num_cmp((uint32_t)(rex.input - rex.line + 1), scan)) {
+            status = RA_NOMATCH;
+          }
+          break;
+
+        case RE_VCOL:
+          if (!re_num_cmp((unsigned)win_linetabsize(rex.reg_win == NULL ? curwin : rex.reg_win,
+                                                    rex.reg_firstlnum + rex.lnum,
+                                                    (char *)rex.line,
+                                                    (colnr_T)(rex.input - rex.line)) + 1,
+                          scan)) {
+            status = RA_NOMATCH;
+          }
+          break;
+
+        case BOW:  // \<word; rex.input points to w
+          if (c == NUL) {  // Can't match at end of line
+            status = RA_NOMATCH;
+          } else {
+            // Get class of current and previous char (if it exists).
+            const int this_class =
+              mb_get_class_tab((char *)rex.input, rex.reg_buf->b_chartab);
+            if (this_class <= 1) {
+              status = RA_NOMATCH;  // Not on a word at all.
+            } else if (reg_prev_class() == this_class) {
+              status = RA_NOMATCH;  // Previous char is in same word.
+            }
+          }
+          break;
+
+        case EOW:  // word\>; rex.input points after d
+          if (rex.input == rex.line) {  // Can't match at start of line
+            status = RA_NOMATCH;
+          } else {
+            int this_class, prev_class;
+
+            // Get class of current and previous char (if it exists).
+            this_class = mb_get_class_tab((char *)rex.input, rex.reg_buf->b_chartab);
+            prev_class = reg_prev_class();
+            if (this_class == prev_class
+                || prev_class == 0 || prev_class == 1) {
+              status = RA_NOMATCH;
+            }
+          }
+          break;  // Matched with EOW
+
+        case ANY:
+          // ANY does not match new lines.
+          if (c == NUL) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case IDENT:
+          if (!vim_isIDc(c)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case SIDENT:
+          if (ascii_isdigit(*rex.input) || !vim_isIDc(c)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case KWORD:
+          if (!vim_iswordp_buf((char *)rex.input, rex.reg_buf)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case SKWORD:
+          if (ascii_isdigit(*rex.input)
+              || !vim_iswordp_buf((char *)rex.input, rex.reg_buf)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case FNAME:
+          if (!vim_isfilec(c)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case SFNAME:
+          if (ascii_isdigit(*rex.input) || !vim_isfilec(c)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case PRINT:
+          if (!vim_isprintc(utf_ptr2char((char *)rex.input))) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case SPRINT:
+          if (ascii_isdigit(*rex.input) || !vim_isprintc(utf_ptr2char((char *)rex.input))) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case WHITE:
+          if (!ascii_iswhite(c)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case NWHITE:
+          if (c == NUL || ascii_iswhite(c)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case DIGIT:
+          if (!ri_digit(c)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case NDIGIT:
+          if (c == NUL || ri_digit(c)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case HEX:
+          if (!ri_hex(c)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case NHEX:
+          if (c == NUL || ri_hex(c)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case OCTAL:
+          if (!ri_octal(c)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case NOCTAL:
+          if (c == NUL || ri_octal(c)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case WORD:
+          if (!ri_word(c)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case NWORD:
+          if (c == NUL || ri_word(c)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case HEAD:
+          if (!ri_head(c)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case NHEAD:
+          if (c == NUL || ri_head(c)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case ALPHA:
+          if (!ri_alpha(c)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case NALPHA:
+          if (c == NUL || ri_alpha(c)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case LOWER:
+          if (!ri_lower(c)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case NLOWER:
+          if (c == NUL || ri_lower(c)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case UPPER:
+          if (!ri_upper(c)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case NUPPER:
+          if (c == NUL || ri_upper(c)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case EXACTLY: {
+          int len;
+          uint8_t *opnd;
+
+          opnd = OPERAND(scan);
+          // Inline the first byte, for speed.
+          if (*opnd != *rex.input
+              && (!rex.reg_ic)) {
+            status = RA_NOMATCH;
+          } else if (*opnd == NUL) {
+            // match empty string always works; happens when "~" is
+            // empty.
+          } else {
+            if (opnd[1] == NUL && !rex.reg_ic) {
+              len = 1;  // matched a single byte above
+            } else {
+              // Need to match first byte again for multi-byte.
+              len = (int)strlen((char *)opnd);
+              if (cstrncmp((char *)opnd, (char *)rex.input, &len) != 0) {
+                status = RA_NOMATCH;
+              }
+            }
+            // Check for following composing character, unless %C
+            // follows (skips over all composing chars).
+            if (status != RA_NOMATCH
+                && utf_composinglike((char *)rex.input, (char *)rex.input + len)
+                && !rex.reg_icombine
+                && OP(next) != RE_COMPOSING) {
+              // raaron: This code makes a composing character get
+              // ignored, which is the correct behavior (sometimes)
+              // for voweled Hebrew texts.
+              status = RA_NOMATCH;
+            }
+            if (status != RA_NOMATCH) {
+              rex.input += len;
+            }
+          }
+        }
+        break;
+
+        case ANYOF:
+        case ANYBUT:
+          if (c == NUL) {
+            status = RA_NOMATCH;
+          } else if ((cstrchr((char *)OPERAND(scan), c) == NULL) == (op == ANYOF)) {
+            status = RA_NOMATCH;
+          } else {
+            ADVANCE_REGINPUT();
+          }
+          break;
+
+        case MULTIBYTECODE: {
+          int i, len;
+
+          const uint8_t *opnd = OPERAND(scan);
+          // Safety check (just in case 'encoding' was changed since
+          // compiling the program).
+          if ((len = utfc_ptr2len((char *)opnd)) < 2) {
+            status = RA_NOMATCH;
+            break;
+          }
+          const int opndc = utf_ptr2char((char *)opnd);
+          if (utf_iscomposing(opndc)) {
+            // When only a composing char is given match at any
+            // position where that composing char appears.
+            status = RA_NOMATCH;
+            for (i = 0; rex.input[i] != NUL;
+                 i += utf_ptr2len((char *)rex.input + i)) {
+              const int inpc = utf_ptr2char((char *)rex.input + i);
+              if (!utf_iscomposing(inpc)) {
+                if (i > 0) {
+                  break;
+                }
+              } else if (opndc == inpc) {
+                // Include all following composing chars.
+                len = i + utfc_ptr2len((char *)rex.input + i);
+                status = RA_MATCH;
+                break;
+              }
+            }
+          } else {
+            for (i = 0; i < len; i++) {
+              if (opnd[i] != rex.input[i]) {
+                status = RA_NOMATCH;
+                break;
+              }
+            }
+          }
+          rex.input += len;
+        }
+        break;
+
+        case RE_COMPOSING:
+          // Skip composing characters.
+          while (utf_iscomposing(utf_ptr2char((char *)rex.input))) {
+            MB_CPTR_ADV(rex.input);
+          }
+          break;
+
+        case NOTHING:
+          break;
+
+        case BACK: {
+          int i;
+
+          // When we run into BACK we need to check if we don't keep
+          // looping without matching any input.  The second and later
+          // times a BACK is encountered it fails if the input is still
+          // at the same position as the previous time.
+          // The positions are stored in "backpos" and found by the
+          // current value of "scan", the position in the RE program.
+          backpos_T *bp = (backpos_T *)backpos.ga_data;
+          for (i = 0; i < backpos.ga_len; i++) {
+            if (bp[i].bp_scan == scan) {
+              break;
+            }
+          }
+          if (i == backpos.ga_len) {
+            backpos_T *p = GA_APPEND_VIA_PTR(backpos_T, &backpos);
+            p->bp_scan = scan;
+          } else if (reg_save_equal(&bp[i].bp_pos)) {
+            // Still at same position as last time, fail.
+            status = RA_NOMATCH;
+          }
+
+          assert(status != RA_FAIL);
+          if (status != RA_NOMATCH) {
+            reg_save(&bp[i].bp_pos, &backpos);
+          }
+        }
+        break;
+
+        case MOPEN + 0:     // Match start: \zs
+        case MOPEN + 1:     // \(
+        case MOPEN + 2:
+        case MOPEN + 3:
+        case MOPEN + 4:
+        case MOPEN + 5:
+        case MOPEN + 6:
+        case MOPEN + 7:
+        case MOPEN + 8:
+        case MOPEN + 9:
+          no = op - MOPEN;
+          cleanup_subexpr();
+          rp = regstack_push(RS_MOPEN, scan);
+          if (rp == NULL) {
+            status = RA_FAIL;
+          } else {
+            rp->rs_no = (int16_t)no;
+            save_se(&rp->rs_un.sesave, &rex.reg_startpos[no],
+                    &rex.reg_startp[no]);
+            // We simply continue and handle the result when done.
+          }
+          break;
+
+        case NOPEN:         // \%(
+        case NCLOSE:        // \) after \%(
+          if (regstack_push(RS_NOPEN, scan) == NULL) {
+            status = RA_FAIL;
+          }
+          // We simply continue and handle the result when done.
+          break;
+
+        case ZOPEN + 1:
+        case ZOPEN + 2:
+        case ZOPEN + 3:
+        case ZOPEN + 4:
+        case ZOPEN + 5:
+        case ZOPEN + 6:
+        case ZOPEN + 7:
+        case ZOPEN + 8:
+        case ZOPEN + 9:
+          no = op - ZOPEN;
+          cleanup_zsubexpr();
+          rp = regstack_push(RS_ZOPEN, scan);
+          if (rp == NULL) {
+            status = RA_FAIL;
+          } else {
+            rp->rs_no = (int16_t)no;
+            save_se(&rp->rs_un.sesave, &reg_startzpos[no],
+                    &reg_startzp[no]);
+            // We simply continue and handle the result when done.
+          }
+          break;
+
+        case MCLOSE + 0:    // Match end: \ze
+        case MCLOSE + 1:    // \)
+        case MCLOSE + 2:
+        case MCLOSE + 3:
+        case MCLOSE + 4:
+        case MCLOSE + 5:
+        case MCLOSE + 6:
+        case MCLOSE + 7:
+        case MCLOSE + 8:
+        case MCLOSE + 9:
+          no = op - MCLOSE;
+          cleanup_subexpr();
+          rp = regstack_push(RS_MCLOSE, scan);
+          if (rp == NULL) {
+            status = RA_FAIL;
+          } else {
+            rp->rs_no = (int16_t)no;
+            save_se(&rp->rs_un.sesave, &rex.reg_endpos[no], &rex.reg_endp[no]);
+            // We simply continue and handle the result when done.
+          }
+          break;
+
+        case ZCLOSE + 1:    // \) after \z(
+        case ZCLOSE + 2:
+        case ZCLOSE + 3:
+        case ZCLOSE + 4:
+        case ZCLOSE + 5:
+        case ZCLOSE + 6:
+        case ZCLOSE + 7:
+        case ZCLOSE + 8:
+        case ZCLOSE + 9:
+          no = op - ZCLOSE;
+          cleanup_zsubexpr();
+          rp = regstack_push(RS_ZCLOSE, scan);
+          if (rp == NULL) {
+            status = RA_FAIL;
+          } else {
+            rp->rs_no = (int16_t)no;
+            save_se(&rp->rs_un.sesave, &reg_endzpos[no],
+                    &reg_endzp[no]);
+            // We simply continue and handle the result when done.
+          }
+          break;
+
+        case BACKREF + 1:
+        case BACKREF + 2:
+        case BACKREF + 3:
+        case BACKREF + 4:
+        case BACKREF + 5:
+        case BACKREF + 6:
+        case BACKREF + 7:
+        case BACKREF + 8:
+        case BACKREF + 9: {
+          int len;
+
+          no = op - BACKREF;
+          cleanup_subexpr();
+          if (!REG_MULTI) {  // Single-line regexp
+            if (rex.reg_startp[no] == NULL || rex.reg_endp[no] == NULL) {
+              // Backref was not set: Match an empty string.
+              len = 0;
+            } else {
+              // Compare current input with back-ref in the same line.
+              len = (int)(rex.reg_endp[no] - rex.reg_startp[no]);
+              if (cstrncmp((char *)rex.reg_startp[no], (char *)rex.input, &len) != 0) {
+                status = RA_NOMATCH;
+              }
+            }
+          } else {  // Multi-line regexp
+            if (rex.reg_startpos[no].lnum < 0 || rex.reg_endpos[no].lnum < 0) {
+              // Backref was not set: Match an empty string.
+              len = 0;
+            } else {
+              if (rex.reg_startpos[no].lnum == rex.lnum
+                  && rex.reg_endpos[no].lnum == rex.lnum) {
+                // Compare back-ref within the current line.
+                len = rex.reg_endpos[no].col - rex.reg_startpos[no].col;
+                if (cstrncmp((char *)rex.line + rex.reg_startpos[no].col,
+                             (char *)rex.input, &len) != 0) {
+                  status = RA_NOMATCH;
+                }
+              } else {
+                // Messy situation: Need to compare between two lines.
+                int r = match_with_backref(rex.reg_startpos[no].lnum,
+                                           rex.reg_startpos[no].col,
+                                           rex.reg_endpos[no].lnum,
+                                           rex.reg_endpos[no].col,
+                                           &len);
+                if (r != RA_MATCH) {
+                  status = r;
+                }
+              }
+            }
+          }
+
+          // Matched the backref, skip over it.
+          rex.input += len;
+        }
+        break;
+
+        case ZREF + 1:
+        case ZREF + 2:
+        case ZREF + 3:
+        case ZREF + 4:
+        case ZREF + 5:
+        case ZREF + 6:
+        case ZREF + 7:
+        case ZREF + 8:
+        case ZREF + 9:
+          cleanup_zsubexpr();
+          no = op - ZREF;
+          if (re_extmatch_in != NULL
+              && re_extmatch_in->matches[no] != NULL) {
+            int len = (int)strlen((char *)re_extmatch_in->matches[no]);
+            if (cstrncmp((char *)re_extmatch_in->matches[no], (char *)rex.input, &len) != 0) {
+              status = RA_NOMATCH;
+            } else {
+              rex.input += len;
+            }
+          } else {
+            // Backref was not set: Match an empty string.
+          }
+          break;
+
+        case BRANCH:
+          if (OP(next) != BRANCH) {     // No choice.
+            next = OPERAND(scan);               // Avoid recursion.
+          } else {
+            rp = regstack_push(RS_BRANCH, scan);
+            if (rp == NULL) {
+              status = RA_FAIL;
+            } else {
+              status = RA_BREAK;                // rest is below
+            }
+          }
+          break;
+
+        case BRACE_LIMITS:
+          if (OP(next) == BRACE_SIMPLE) {
+            bl_minval = OPERAND_MIN(scan);
+            bl_maxval = OPERAND_MAX(scan);
+          } else if (OP(next) >= BRACE_COMPLEX
+                     && OP(next) < BRACE_COMPLEX + 10) {
+            no = OP(next) - BRACE_COMPLEX;
+            brace_min[no] = OPERAND_MIN(scan);
+            brace_max[no] = OPERAND_MAX(scan);
+            brace_count[no] = 0;
+          } else {
+            internal_error("BRACE_LIMITS");
+            status = RA_FAIL;
+          }
+          break;
+
+        case BRACE_COMPLEX + 0:
+        case BRACE_COMPLEX + 1:
+        case BRACE_COMPLEX + 2:
+        case BRACE_COMPLEX + 3:
+        case BRACE_COMPLEX + 4:
+        case BRACE_COMPLEX + 5:
+        case BRACE_COMPLEX + 6:
+        case BRACE_COMPLEX + 7:
+        case BRACE_COMPLEX + 8:
+        case BRACE_COMPLEX + 9:
+          no = op - BRACE_COMPLEX;
+          brace_count[no]++;
+
+          // If not matched enough times yet, try one more
+          if (brace_count[no] <= (brace_min[no] <= brace_max[no]
+                                  ? brace_min[no] : brace_max[no])) {
+            rp = regstack_push(RS_BRCPLX_MORE, scan);
+            if (rp == NULL) {
+              status = RA_FAIL;
+            } else {
+              rp->rs_no = (int16_t)no;
+              reg_save(&rp->rs_un.regsave, &backpos);
+              next = OPERAND(scan);
+              // We continue and handle the result when done.
+            }
+            break;
+          }
+
+          // If matched enough times, may try matching some more
+          if (brace_min[no] <= brace_max[no]) {
+            // Range is the normal way around, use longest match
+            if (brace_count[no] <= brace_max[no]) {
+              rp = regstack_push(RS_BRCPLX_LONG, scan);
+              if (rp == NULL) {
+                status = RA_FAIL;
+              } else {
+                rp->rs_no = (int16_t)no;
+                reg_save(&rp->rs_un.regsave, &backpos);
+                next = OPERAND(scan);
+                // We continue and handle the result when done.
+              }
+            }
+          } else {
+            // Range is backwards, use shortest match first
+            if (brace_count[no] <= brace_min[no]) {
+              rp = regstack_push(RS_BRCPLX_SHORT, scan);
+              if (rp == NULL) {
+                status = RA_FAIL;
+              } else {
+                reg_save(&rp->rs_un.regsave, &backpos);
+                // We continue and handle the result when done.
+              }
+            }
+          }
+          break;
+
+        case BRACE_SIMPLE:
+        case STAR:
+        case PLUS: {
+          regstar_T rst;
+
+          // Lookahead to avoid useless match attempts when we know
+          // what character comes next.
+          if (OP(next) == EXACTLY) {
+            rst.nextb = *OPERAND(next);
+            if (rex.reg_ic) {
+              if (mb_isupper(rst.nextb)) {
+                rst.nextb_ic = mb_tolower(rst.nextb);
+              } else {
+                rst.nextb_ic = mb_toupper(rst.nextb);
+              }
+            } else {
+              rst.nextb_ic = rst.nextb;
+            }
+          } else {
+            rst.nextb = NUL;
+            rst.nextb_ic = NUL;
+          }
+          if (op != BRACE_SIMPLE) {
+            rst.minval = (op == STAR) ? 0 : 1;
+            rst.maxval = MAX_LIMIT;
+          } else {
+            rst.minval = bl_minval;
+            rst.maxval = bl_maxval;
+          }
+
+          // When maxval > minval, try matching as much as possible, up
+          // to maxval.  When maxval < minval, try matching at least the
+          // minimal number (since the range is backwards, that's also
+          // maxval!).
+          rst.count = regrepeat(OPERAND(scan), rst.maxval);
+          if (got_int) {
+            status = RA_FAIL;
+            break;
+          }
+          if (rst.minval <= rst.maxval
+              ? rst.count >= rst.minval : rst.count >= rst.maxval) {
+            // It could match.  Prepare for trying to match what
+            // follows.  The code is below.  Parameters are stored in
+            // a regstar_T on the regstack.
+            if ((int64_t)((unsigned)regstack.ga_len >> 10) >= p_mmp) {
+              emsg(_(e_pattern_uses_more_memory_than_maxmempattern));
+              status = RA_FAIL;
+            } else {
+              ga_grow(&regstack, sizeof(regstar_T));
+              regstack.ga_len += (int)sizeof(regstar_T);
+              rp = regstack_push(rst.minval <= rst.maxval ? RS_STAR_LONG : RS_STAR_SHORT, scan);
+              if (rp == NULL) {
+                status = RA_FAIL;
+              } else {
+                *(((regstar_T *)rp) - 1) = rst;
+                status = RA_BREAK;                  // skip the restore bits
+              }
+            }
+          } else {
+            status = RA_NOMATCH;
+          }
+        }
+        break;
+
+        case NOMATCH:
+        case MATCH:
+        case SUBPAT:
+          rp = regstack_push(RS_NOMATCH, scan);
+          if (rp == NULL) {
+            status = RA_FAIL;
+          } else {
+            rp->rs_no = (int16_t)op;
+            reg_save(&rp->rs_un.regsave, &backpos);
+            next = OPERAND(scan);
+            // We continue and handle the result when done.
+          }
+          break;
+
+        case BEHIND:
+        case NOBEHIND:
+          // Need a bit of room to store extra positions.
+          if ((int64_t)((unsigned)regstack.ga_len >> 10) >= p_mmp) {
+            emsg(_(e_pattern_uses_more_memory_than_maxmempattern));
+            status = RA_FAIL;
+          } else {
+            ga_grow(&regstack, sizeof(regbehind_T));
+            regstack.ga_len += (int)sizeof(regbehind_T);
+            rp = regstack_push(RS_BEHIND1, scan);
+            if (rp == NULL) {
+              status = RA_FAIL;
+            } else {
+              // Need to save the subexpr to be able to restore them
+              // when there is a match but we don't use it.
+              save_subexpr(((regbehind_T *)rp) - 1);
+
+              rp->rs_no = (int16_t)op;
+              reg_save(&rp->rs_un.regsave, &backpos);
+              // First try if what follows matches.  If it does then we
+              // check the behind match by looping.
+            }
+          }
+          break;
+
+        case BHPOS:
+          if (REG_MULTI) {
+            if (behind_pos.rs_u.pos.col != (colnr_T)(rex.input - rex.line)
+                || behind_pos.rs_u.pos.lnum != rex.lnum) {
+              status = RA_NOMATCH;
+            }
+          } else if (behind_pos.rs_u.ptr != rex.input) {
+            status = RA_NOMATCH;
+          }
+          break;
+
+        case NEWL:
+          if ((c != NUL || !REG_MULTI || rex.lnum > rex.reg_maxline
+               || rex.reg_line_lbr) && (c != '\n' || !rex.reg_line_lbr)) {
+            status = RA_NOMATCH;
+          } else if (rex.reg_line_lbr) {
+            ADVANCE_REGINPUT();
+          } else {
+            reg_nextline();
+          }
+          break;
+
+        case END:
+          status = RA_MATCH;    // Success!
+          break;
+
+        default:
+          iemsg(_(e_re_corr));
+#ifdef REGEXP_DEBUG
+          printf("Illegal op code %d\n", op);
+#endif
+          status = RA_FAIL;
+          break;
+        }
+      }
+
+      // If we can't continue sequentially, break the inner loop.
+      if (status != RA_CONT) {
+        break;
+      }
+
+      // Continue in inner loop, advance to next item.
+      scan = next;
+    }  // end of inner loop
+
+    // If there is something on the regstack execute the code for the state.
+    // If the state is popped then loop and use the older state.
+    while (!GA_EMPTY(&regstack) && status != RA_FAIL) {
+      rp = (regitem_T *)((char *)regstack.ga_data + regstack.ga_len) - 1;
+      switch (rp->rs_state) {
+      case RS_NOPEN:
+        // Result is passed on as-is, simply pop the state.
+        regstack_pop(&scan);
+        break;
+
+      case RS_MOPEN:
+        // Pop the state.  Restore pointers when there is no match.
+        if (status == RA_NOMATCH) {
+          restore_se(&rp->rs_un.sesave, &rex.reg_startpos[rp->rs_no],
+                     &rex.reg_startp[rp->rs_no]);
+        }
+        regstack_pop(&scan);
+        break;
+
+      case RS_ZOPEN:
+        // Pop the state.  Restore pointers when there is no match.
+        if (status == RA_NOMATCH) {
+          restore_se(&rp->rs_un.sesave, &reg_startzpos[rp->rs_no],
+                     &reg_startzp[rp->rs_no]);
+        }
+        regstack_pop(&scan);
+        break;
+
+      case RS_MCLOSE:
+        // Pop the state.  Restore pointers when there is no match.
+        if (status == RA_NOMATCH) {
+          restore_se(&rp->rs_un.sesave, &rex.reg_endpos[rp->rs_no],
+                     &rex.reg_endp[rp->rs_no]);
+        }
+        regstack_pop(&scan);
+        break;
+
+      case RS_ZCLOSE:
+        // Pop the state.  Restore pointers when there is no match.
+        if (status == RA_NOMATCH) {
+          restore_se(&rp->rs_un.sesave, &reg_endzpos[rp->rs_no],
+                     &reg_endzp[rp->rs_no]);
+        }
+        regstack_pop(&scan);
+        break;
+
+      case RS_BRANCH:
+        if (status == RA_MATCH) {
+          // this branch matched, use it
+          regstack_pop(&scan);
+        } else {
+          if (status != RA_BREAK) {
+            // After a non-matching branch: try next one.
+            reg_restore(&rp->rs_un.regsave, &backpos);
+            scan = rp->rs_scan;
+          }
+          if (scan == NULL || OP(scan) != BRANCH) {
+            // no more branches, didn't find a match
+            status = RA_NOMATCH;
+            regstack_pop(&scan);
+          } else {
+            // Prepare to try a branch.
+            rp->rs_scan = regnext(scan);
+            reg_save(&rp->rs_un.regsave, &backpos);
+            scan = OPERAND(scan);
+          }
+        }
+        break;
+
+      case RS_BRCPLX_MORE:
+        // Pop the state.  Restore pointers when there is no match.
+        if (status == RA_NOMATCH) {
+          reg_restore(&rp->rs_un.regsave, &backpos);
+          brace_count[rp->rs_no]--;             // decrement match count
+        }
+        regstack_pop(&scan);
+        break;
+
+      case RS_BRCPLX_LONG:
+        // Pop the state.  Restore pointers when there is no match.
+        if (status == RA_NOMATCH) {
+          // There was no match, but we did find enough matches.
+          reg_restore(&rp->rs_un.regsave, &backpos);
+          brace_count[rp->rs_no]--;
+          // continue with the items after "\{}"
+          status = RA_CONT;
+        }
+        regstack_pop(&scan);
+        if (status == RA_CONT) {
+          scan = regnext(scan);
+        }
+        break;
+
+      case RS_BRCPLX_SHORT:
+        // Pop the state.  Restore pointers when there is no match.
+        if (status == RA_NOMATCH) {
+          // There was no match, try to match one more item.
+          reg_restore(&rp->rs_un.regsave, &backpos);
+        }
+        regstack_pop(&scan);
+        if (status == RA_NOMATCH) {
+          scan = OPERAND(scan);
+          status = RA_CONT;
+        }
+        break;
+
+      case RS_NOMATCH:
+        // Pop the state.  If the operand matches for NOMATCH or
+        // doesn't match for MATCH/SUBPAT, we fail.  Otherwise backup,
+        // except for SUBPAT, and continue with the next item.
+        if (status == (rp->rs_no == NOMATCH ? RA_MATCH : RA_NOMATCH)) {
+          status = RA_NOMATCH;
+        } else {
+          status = RA_CONT;
+          if (rp->rs_no != SUBPAT) {            // zero-width
+            reg_restore(&rp->rs_un.regsave, &backpos);
+          }
+        }
+        regstack_pop(&scan);
+        if (status == RA_CONT) {
+          scan = regnext(scan);
+        }
+        break;
+
+      case RS_BEHIND1:
+        if (status == RA_NOMATCH) {
+          regstack_pop(&scan);
+          regstack.ga_len -= (int)sizeof(regbehind_T);
+        } else {
+          // The stuff after BEHIND/NOBEHIND matches.  Now try if
+          // the behind part does (not) match before the current
+          // position in the input.  This must be done at every
+          // position in the input and checking if the match ends at
+          // the current position.
+
+          // save the position after the found match for next
+          reg_save(&(((regbehind_T *)rp) - 1)->save_after, &backpos);
+
+          // Start looking for a match with operand at the current
+          // position.  Go back one character until we find the
+          // result, hitting the start of the line or the previous
+          // line (for multi-line matching).
+          // Set behind_pos to where the match should end, BHPOS
+          // will match it.  Save the current value.
+          (((regbehind_T *)rp) - 1)->save_behind = behind_pos;
+          behind_pos = rp->rs_un.regsave;
+
+          rp->rs_state = RS_BEHIND2;
+
+          reg_restore(&rp->rs_un.regsave, &backpos);
+          scan = OPERAND(rp->rs_scan) + 4;
+        }
+        break;
+
+      case RS_BEHIND2:
+        // Looping for BEHIND / NOBEHIND match.
+        if (status == RA_MATCH && reg_save_equal(&behind_pos)) {
+          // found a match that ends where "next" started
+          behind_pos = (((regbehind_T *)rp) - 1)->save_behind;
+          if (rp->rs_no == BEHIND) {
+            reg_restore(&(((regbehind_T *)rp) - 1)->save_after,
+                        &backpos);
+          } else {
+            // But we didn't want a match.  Need to restore the
+            // subexpr, because what follows matched, so they have
+            // been set.
+            status = RA_NOMATCH;
+            restore_subexpr(((regbehind_T *)rp) - 1);
+          }
+          regstack_pop(&scan);
+          regstack.ga_len -= (int)sizeof(regbehind_T);
+        } else {
+          int64_t limit;
+
+          // No match or a match that doesn't end where we want it: Go
+          // back one character.  May go to previous line once.
+          no = OK;
+          limit = OPERAND_MIN(rp->rs_scan);
+          if (REG_MULTI) {
+            if (limit > 0
+                && ((rp->rs_un.regsave.rs_u.pos.lnum
+                     < behind_pos.rs_u.pos.lnum
+                     ? (colnr_T)strlen((char *)rex.line)
+                     : behind_pos.rs_u.pos.col)
+                    - rp->rs_un.regsave.rs_u.pos.col >= limit)) {
+              no = FAIL;
+            } else if (rp->rs_un.regsave.rs_u.pos.col == 0) {
+              if (rp->rs_un.regsave.rs_u.pos.lnum
+                  < behind_pos.rs_u.pos.lnum
+                  || reg_getline(--rp->rs_un.regsave.rs_u.pos.lnum)
+                  == NULL) {
+                no = FAIL;
+              } else {
+                reg_restore(&rp->rs_un.regsave, &backpos);
+                rp->rs_un.regsave.rs_u.pos.col =
+                  (colnr_T)strlen((char *)rex.line);
+              }
+            } else {
+              const uint8_t *const line =
+                (uint8_t *)reg_getline(rp->rs_un.regsave.rs_u.pos.lnum);
+
+              rp->rs_un.regsave.rs_u.pos.col -=
+                utf_head_off((char *)line,
+                             (char *)line + rp->rs_un.regsave.rs_u.pos.col - 1)
+                + 1;
+            }
+          } else {
+            if (rp->rs_un.regsave.rs_u.ptr == rex.line) {
+              no = FAIL;
+            } else {
+              MB_PTR_BACK(rex.line, rp->rs_un.regsave.rs_u.ptr);
+              if (limit > 0
+                  && (behind_pos.rs_u.ptr - rp->rs_un.regsave.rs_u.ptr) > (ptrdiff_t)limit) {
+                no = FAIL;
+              }
+            }
+          }
+          if (no == OK) {
+            // Advanced, prepare for finding match again.
+            reg_restore(&rp->rs_un.regsave, &backpos);
+            scan = OPERAND(rp->rs_scan) + 4;
+            if (status == RA_MATCH) {
+              // We did match, so subexpr may have been changed,
+              // need to restore them for the next try.
+              status = RA_NOMATCH;
+              restore_subexpr(((regbehind_T *)rp) - 1);
+            }
+          } else {
+            // Can't advance.  For NOBEHIND that's a match.
+            behind_pos = (((regbehind_T *)rp) - 1)->save_behind;
+            if (rp->rs_no == NOBEHIND) {
+              reg_restore(&(((regbehind_T *)rp) - 1)->save_after,
+                          &backpos);
+              status = RA_MATCH;
+            } else {
+              // We do want a proper match.  Need to restore the
+              // subexpr if we had a match, because they may have
+              // been set.
+              if (status == RA_MATCH) {
+                status = RA_NOMATCH;
+                restore_subexpr(((regbehind_T *)rp) - 1);
+              }
+            }
+            regstack_pop(&scan);
+            regstack.ga_len -= (int)sizeof(regbehind_T);
+          }
+        }
+        break;
+
+      case RS_STAR_LONG:
+      case RS_STAR_SHORT: {
+        regstar_T *rst = ((regstar_T *)rp) - 1;
+
+        if (status == RA_MATCH) {
+          regstack_pop(&scan);
+          regstack.ga_len -= (int)sizeof(regstar_T);
+          break;
+        }
+
+        // Tried once already, restore input pointers.
+        if (status != RA_BREAK) {
+          reg_restore(&rp->rs_un.regsave, &backpos);
+        }
+
+        // Repeat until we found a position where it could match.
+        while (true) {
+          if (status != RA_BREAK) {
+            // Tried first position already, advance.
+            if (rp->rs_state == RS_STAR_LONG) {
+              // Trying for longest match, but couldn't or
+              // didn't match -- back up one char.
+              if (--rst->count < rst->minval) {
+                break;
+              }
+              if (rex.input == rex.line) {
+                // backup to last char of previous line
+                if (rex.lnum == 0) {
+                  status = RA_NOMATCH;
+                  break;
+                }
+                rex.lnum--;
+                rex.line = (uint8_t *)reg_getline(rex.lnum);
+                // Just in case regrepeat() didn't count right.
+                if (rex.line == NULL) {
+                  break;
+                }
+                rex.input = rex.line + strlen((char *)rex.line);
+                reg_breakcheck();
+              } else {
+                MB_PTR_BACK(rex.line, rex.input);
+              }
+            } else {
+              // Range is backwards, use shortest match first.
+              // Careful: maxval and minval are exchanged!
+              // Couldn't or didn't match: try advancing one
+              // char.
+              if (rst->count == rst->minval
+                  || regrepeat(OPERAND(rp->rs_scan), 1L) == 0) {
+                break;
+              }
+              rst->count++;
+            }
+            if (got_int) {
+              break;
+            }
+          } else {
+            status = RA_NOMATCH;
+          }
+
+          // If it could match, try it.
+          if (rst->nextb == NUL || *rex.input == rst->nextb
+              || *rex.input == rst->nextb_ic) {
+            reg_save(&rp->rs_un.regsave, &backpos);
+            scan = regnext(rp->rs_scan);
+            status = RA_CONT;
+            break;
+          }
+        }
+        if (status != RA_CONT) {
+          // Failed.
+          regstack_pop(&scan);
+          regstack.ga_len -= (int)sizeof(regstar_T);
+          status = RA_NOMATCH;
+        }
+      }
+      break;
+      }
+
+      // If we want to continue the inner loop or didn't pop a state
+      // continue matching loop
+      if (status == RA_CONT || rp == (regitem_T *)
+          ((char *)regstack.ga_data + regstack.ga_len) - 1) {
+        break;
+      }
+    }
+
+    // May need to continue with the inner loop, starting at "scan".
+    if (status == RA_CONT) {
+      continue;
+    }
+
+    // If the regstack is empty or something failed we are done.
+    if (GA_EMPTY(&regstack) || status == RA_FAIL) {
+      if (scan == NULL) {
+        // We get here only if there's trouble -- normally "case END" is
+        // the terminating point.
+        iemsg(_(e_re_corr));
+#ifdef REGEXP_DEBUG
+        printf("Premature EOL\n");
+#endif
+      }
+      return status == RA_MATCH;
+    }
+  }  // End of loop until the regstack is empty.
+
+  // NOTREACHED
+}
+
+/// Try match of "prog" with at rex.line["col"].
+///
+/// @param tm         timeout limit or NULL
+/// @param timed_out  flag set on timeout or NULL
+///
+/// @return  0 for failure, or number of lines contained in the match.
+static int regtry(bt_regprog_T *prog, colnr_T col, proftime_T *tm, int *timed_out)
+{
+  rex.input = rex.line + col;
+  rex.need_clear_subexpr = true;
+  // Clear the external match subpointers if necessaey.
+  rex.need_clear_zsubexpr = (prog->reghasz == REX_SET);
+
+  if (regmatch(prog->program + 1, tm, timed_out) == 0) {
+    return 0;
+  }
+
+  cleanup_subexpr();
+  if (REG_MULTI) {
+    if (rex.reg_startpos[0].lnum < 0) {
+      rex.reg_startpos[0].lnum = 0;
+      rex.reg_startpos[0].col = col;
+    }
+    if (rex.reg_endpos[0].lnum < 0) {
+      rex.reg_endpos[0].lnum = rex.lnum;
+      rex.reg_endpos[0].col = (int)(rex.input - rex.line);
+    } else {
+      // Use line number of "\ze".
+      rex.lnum = rex.reg_endpos[0].lnum;
+    }
+  } else {
+    if (rex.reg_startp[0] == NULL) {
+      rex.reg_startp[0] = rex.line + col;
+    }
+    if (rex.reg_endp[0] == NULL) {
+      rex.reg_endp[0] = rex.input;
+    }
+  }
+  // Package any found \z(...\) matches for export. Default is none.
+  unref_extmatch(re_extmatch_out);
+  re_extmatch_out = NULL;
+
+  if (prog->reghasz == REX_SET) {
+    int i;
+
+    cleanup_zsubexpr();
+    re_extmatch_out = make_extmatch();
+    for (i = 0; i < NSUBEXP; i++) {
+      if (REG_MULTI) {
+        // Only accept single line matches.
+        if (reg_startzpos[i].lnum >= 0
+            && reg_endzpos[i].lnum == reg_startzpos[i].lnum
+            && reg_endzpos[i].col >= reg_startzpos[i].col) {
+          re_extmatch_out->matches[i] =
+            (uint8_t *)xstrnsave(reg_getline(reg_startzpos[i].lnum) + reg_startzpos[i].col,
+                                 (size_t)(reg_endzpos[i].col - reg_startzpos[i].col));
+        }
+      } else {
+        if (reg_startzp[i] != NULL && reg_endzp[i] != NULL) {
+          re_extmatch_out->matches[i] =
+            (uint8_t *)xstrnsave((char *)reg_startzp[i], (size_t)(reg_endzp[i] - reg_startzp[i]));
+        }
+      }
+    }
+  }
+  return 1 + rex.lnum;
+}
+
+/// Match a regexp against a string ("line" points to the string) or multiple
+/// lines (if "line" is NULL, use reg_getline()).
+///
+/// @param startcol   column to start looking for match
+/// @param tm         timeout limit or NULL
+/// @param timed_out  flag set on timeout or NULL
+///
+/// @return  0 for failure, or number of lines contained in the match.
+static int bt_regexec_both(uint8_t *line, colnr_T startcol, proftime_T *tm, int *timed_out)
+{
+  bt_regprog_T *prog;
+  uint8_t *s;
+  colnr_T col = startcol;
+  int retval = 0;
+
+  // Create "regstack" and "backpos" if they are not allocated yet.
+  // We allocate *_INITIAL amount of bytes first and then set the grow size
+  // to much bigger value to avoid many malloc calls in case of deep regular
+  // expressions.
+  if (regstack.ga_data == NULL) {
+    // Use an item size of 1 byte, since we push different things
+    // onto the regstack.
+    ga_init(&regstack, 1, REGSTACK_INITIAL);
+    ga_grow(&regstack, REGSTACK_INITIAL);
+    ga_set_growsize(&regstack, REGSTACK_INITIAL * 8);
+  }
+
+  if (backpos.ga_data == NULL) {
+    ga_init(&backpos, sizeof(backpos_T), BACKPOS_INITIAL);
+    ga_grow(&backpos, BACKPOS_INITIAL);
+    ga_set_growsize(&backpos, BACKPOS_INITIAL * 8);
+  }
+
+  if (REG_MULTI) {
+    prog = (bt_regprog_T *)rex.reg_mmatch->regprog;
+    line = (uint8_t *)reg_getline(0);
+    rex.reg_startpos = rex.reg_mmatch->startpos;
+    rex.reg_endpos = rex.reg_mmatch->endpos;
+  } else {
+    prog = (bt_regprog_T *)rex.reg_match->regprog;
+    rex.reg_startp = (uint8_t **)rex.reg_match->startp;
+    rex.reg_endp = (uint8_t **)rex.reg_match->endp;
+  }
+
+  // Be paranoid...
+  if (prog == NULL || line == NULL) {
+    iemsg(_(e_null));
+    goto theend;
+  }
+
+  // Check validity of program.
+  if (prog_magic_wrong()) {
+    goto theend;
+  }
+
+  // If the start column is past the maximum column: no need to try.
+  if (rex.reg_maxcol > 0 && col >= rex.reg_maxcol) {
+    goto theend;
+  }
+
+  // If pattern contains "\c" or "\C": overrule value of rex.reg_ic
+  if (prog->regflags & RF_ICASE) {
+    rex.reg_ic = true;
+  } else if (prog->regflags & RF_NOICASE) {
+    rex.reg_ic = false;
+  }
+
+  // If pattern contains "\Z" overrule value of rex.reg_icombine
+  if (prog->regflags & RF_ICOMBINE) {
+    rex.reg_icombine = true;
+  }
+
+  // If there is a "must appear" string, look for it.
+  if (prog->regmust != NULL) {
+    int c = utf_ptr2char((char *)prog->regmust);
+    s = line + col;
+
+    // This is used very often, esp. for ":global".  Use two versions of
+    // the loop to avoid overhead of conditions.
+    if (!rex.reg_ic) {
+      while ((s = (uint8_t *)vim_strchr((char *)s, c)) != NULL) {
+        if (cstrncmp((char *)s, (char *)prog->regmust, &prog->regmlen) == 0) {
+          break;  // Found it.
+        }
+        MB_PTR_ADV(s);
+      }
+    } else {
+      while ((s = (uint8_t *)cstrchr((char *)s, c)) != NULL) {
+        if (cstrncmp((char *)s, (char *)prog->regmust, &prog->regmlen) == 0) {
+          break;  // Found it.
+        }
+        MB_PTR_ADV(s);
+      }
+    }
+    if (s == NULL) {  // Not present.
+      goto theend;
+    }
+  }
+
+  rex.line = line;
+  rex.lnum = 0;
+  reg_toolong = false;
+
+  // Simplest case: Anchored match need be tried only once.
+  if (prog->reganch) {
+    int c = utf_ptr2char((char *)rex.line + col);
+    if (prog->regstart == NUL
+        || prog->regstart == c
+        || (rex.reg_ic
+            && (utf_fold(prog->regstart) == utf_fold(c)
+                || (c < 255 && prog->regstart < 255
+                    && mb_tolower(prog->regstart) == mb_tolower(c))))) {
+      retval = regtry(prog, col, tm, timed_out);
+    } else {
+      retval = 0;
+    }
+  } else {
+    int tm_count = 0;
+    // Messy cases:  unanchored match.
+    while (!got_int) {
+      if (prog->regstart != NUL) {
+        // Skip until the char we know it must start with.
+        s = (uint8_t *)cstrchr((char *)rex.line + col, prog->regstart);
+        if (s == NULL) {
+          retval = 0;
+          break;
+        }
+        col = (int)(s - rex.line);
+      }
+
+      // Check for maximum column to try.
+      if (rex.reg_maxcol > 0 && col >= rex.reg_maxcol) {
+        retval = 0;
+        break;
+      }
+
+      retval = regtry(prog, col, tm, timed_out);
+      if (retval > 0) {
+        break;
+      }
+
+      // if not currently on the first line, get it again
+      if (rex.lnum != 0) {
+        rex.lnum = 0;
+        rex.line = (uint8_t *)reg_getline(0);
+      }
+      if (rex.line[col] == NUL) {
+        break;
+      }
+      col += utfc_ptr2len((char *)rex.line + col);
+      // Check for timeout once in a twenty times to avoid overhead.
+      if (tm != NULL && ++tm_count == 20) {
+        tm_count = 0;
+        if (profile_passed_limit(*tm)) {
+          if (timed_out != NULL) {
+            *timed_out = true;
+          }
+          break;
+        }
+      }
+    }
+  }
+
+theend:
+  // Free "reg_tofree" when it's a bit big.
+  // Free regstack and backpos if they are bigger than their initial size.
+  if (reg_tofreelen > 400) {
+    XFREE_CLEAR(reg_tofree);
+  }
+  if (regstack.ga_maxlen > REGSTACK_INITIAL) {
+    ga_clear(&regstack);
+  }
+  if (backpos.ga_maxlen > BACKPOS_INITIAL) {
+    ga_clear(&backpos);
+  }
+
+  if (retval > 0) {
+    // Make sure the end is never before the start.  Can happen when \zs
+    // and \ze are used.
+    if (REG_MULTI) {
+      const lpos_T *const start = &rex.reg_mmatch->startpos[0];
+      const lpos_T *const end = &rex.reg_mmatch->endpos[0];
+
+      if (end->lnum < start->lnum
+          || (end->lnum == start->lnum && end->col < start->col)) {
+        rex.reg_mmatch->endpos[0] = rex.reg_mmatch->startpos[0];
+      }
+
+      // startpos[0] may be set by "\zs", also return the column where
+      // the whole pattern matched.
+      rex.reg_mmatch->rmm_matchcol = col;
+    } else {
+      if (rex.reg_match->endp[0] < rex.reg_match->startp[0]) {
+        rex.reg_match->endp[0] = rex.reg_match->startp[0];
+      }
+
+      // startpos[0] may be set by "\zs", also return the column where
+      // the whole pattern matched.
+      rex.reg_match->rm_matchcol = col;
+    }
+  }
+
+  return retval;
+}
+
+/// Match a regexp against a string.
+/// "rmp->regprog" is a compiled regexp as returned by vim_regcomp().
+/// Uses curbuf for line count and 'iskeyword'.
+/// If "line_lbr" is true, consider a "\n" in "line" to be a line break.
+///
+/// @param line  string to match against
+/// @param col   column to start looking for match
+///
+/// @return  0 for failure, number of lines contained in the match otherwise.
+static int bt_regexec_nl(regmatch_T *rmp, uint8_t *line, colnr_T col, bool line_lbr)
+{
+  rex.reg_match = rmp;
+  rex.reg_mmatch = NULL;
+  rex.reg_maxline = 0;
+  rex.reg_line_lbr = line_lbr;
+  rex.reg_buf = curbuf;
+  rex.reg_win = NULL;
+  rex.reg_ic = rmp->rm_ic;
+  rex.reg_icombine = false;
+  rex.reg_nobreak = rmp->regprog->re_flags & RE_NOBREAK;
+  rex.reg_maxcol = 0;
+
+  int64_t r = bt_regexec_both(line, col, NULL, NULL);
+  assert(r <= INT_MAX);
+  return (int)r;
+}
+
+/// Matches a regexp against multiple lines.
+/// "rmp->regprog" is a compiled regexp as returned by vim_regcomp().
+/// Uses curbuf for line count and 'iskeyword'.
+///
+/// @param win Window in which to search or NULL
+/// @param buf Buffer in which to search
+/// @param lnum Number of line to start looking for match
+/// @param col Column to start looking for match
+/// @param tm Timeout limit or NULL
+///
+/// @return zero if there is no match and number of lines contained in the match
+///         otherwise.
+static int bt_regexec_multi(regmmatch_T *rmp, win_T *win, buf_T *buf, linenr_T lnum, colnr_T col,
+                            proftime_T *tm, int *timed_out)
+{
+  init_regexec_multi(rmp, win, buf, lnum);
+  return bt_regexec_both(NULL, col, tm, timed_out);
+}
+
+// Compare a number with the operand of RE_LNUM, RE_COL or RE_VCOL.
+static int re_num_cmp(uint32_t val, const uint8_t *scan)
+{
+  uint32_t n = (uint32_t)OPERAND_MIN(scan);
+
+  if (OPERAND_CMP(scan) == '>') {
+    return val > n;
+  }
+  if (OPERAND_CMP(scan) == '<') {
+    return val < n;
+  }
+  return val == n;
+}
+
+#ifdef BT_REGEXP_DUMP
+
+// regdump - dump a regexp onto stdout in vaguely comprehensible form
+static void regdump(uint8_t *pattern, bt_regprog_T *r)
+{
+  uint8_t *s;
+  int op = EXACTLY;             // Arbitrary non-END op.
+  uint8_t *next;
+  uint8_t *end = NULL;
+  FILE *f;
+
+# ifdef BT_REGEXP_LOG
+  f = fopen("bt_regexp_log.log", "a");
+# else
+  f = stdout;
+# endif
+  if (f == NULL) {
+    return;
+  }
+  fprintf(f, "-------------------------------------\n\r\nregcomp(%s):\r\n",
+          pattern);
+
+  s = r->program + 1;
+  // Loop until we find the END that isn't before a referred next (an END
+  // can also appear in a NOMATCH operand).
+  while (op != END || s <= end) {
+    op = OP(s);
+    fprintf(f, "%2d%s", (int)(s - r->program), regprop(s));     // Where, what.
+    next = regnext(s);
+    if (next == NULL) {         // Next ptr.
+      fprintf(f, "(0)");
+    } else {
+      fprintf(f, "(%d)", (int)((s - r->program) + (next - s)));
+    }
+    if (end < next) {
+      end = next;
+    }
+    if (op == BRACE_LIMITS) {
+      // Two ints
+      fprintf(f, " minval %" PRId64 ", maxval %" PRId64,
+              (int64_t)OPERAND_MIN(s), (int64_t)OPERAND_MAX(s));
+      s += 8;
+    } else if (op == BEHIND || op == NOBEHIND) {
+      // one int
+      fprintf(f, " count %" PRId64, (int64_t)OPERAND_MIN(s));
+      s += 4;
+    } else if (op == RE_LNUM || op == RE_COL || op == RE_VCOL) {
+      // one int plus comparator
+      fprintf(f, " count %" PRId64, (int64_t)OPERAND_MIN(s));
+      s += 5;
+    }
+    s += 3;
+    if (op == ANYOF || op == ANYOF + ADD_NL
+        || op == ANYBUT || op == ANYBUT + ADD_NL
+        || op == EXACTLY) {
+      // Literal string, where present.
+      fprintf(f, "\nxxxxxxxxx\n");
+      while (*s != NUL) {
+        fprintf(f, "%c", *s++);
+      }
+      fprintf(f, "\nxxxxxxxxx\n");
+      s++;
+    }
+    fprintf(f, "\r\n");
+  }
+
+  // Header fields of interest.
+  if (r->regstart != NUL) {
+    fprintf(f, "start `%s' 0x%x; ", r->regstart < 256
+            ? (char *)transchar(r->regstart)
+            : "multibyte", r->regstart);
+  }
+  if (r->reganch) {
+    fprintf(f, "anchored; ");
+  }
+  if (r->regmust != NULL) {
+    fprintf(f, "must have \"%s\"", r->regmust);
+  }
+  fprintf(f, "\r\n");
+
+# ifdef BT_REGEXP_LOG
+  fclose(f);
+# endif
+}
+#endif      // BT_REGEXP_DUMP
+
+#ifdef REGEXP_DEBUG
+
+// regprop - printable representation of opcode
+static uint8_t *regprop(uint8_t *op)
+{
+  char *p;
+  static char buf[50];
+
+  STRCPY(buf, ":");
+
+  switch ((int)OP(op)) {
+  case BOL:
+    p = "BOL";
+    break;
+  case EOL:
+    p = "EOL";
+    break;
+  case RE_BOF:
+    p = "BOF";
+    break;
+  case RE_EOF:
+    p = "EOF";
+    break;
+  case CURSOR:
+    p = "CURSOR";
+    break;
+  case RE_VISUAL:
+    p = "RE_VISUAL";
+    break;
+  case RE_LNUM:
+    p = "RE_LNUM";
+    break;
+  case RE_MARK:
+    p = "RE_MARK";
+    break;
+  case RE_COL:
+    p = "RE_COL";
+    break;
+  case RE_VCOL:
+    p = "RE_VCOL";
+    break;
+  case BOW:
+    p = "BOW";
+    break;
+  case EOW:
+    p = "EOW";
+    break;
+  case ANY:
+    p = "ANY";
+    break;
+  case ANY + ADD_NL:
+    p = "ANY+NL";
+    break;
+  case ANYOF:
+    p = "ANYOF";
+    break;
+  case ANYOF + ADD_NL:
+    p = "ANYOF+NL";
+    break;
+  case ANYBUT:
+    p = "ANYBUT";
+    break;
+  case ANYBUT + ADD_NL:
+    p = "ANYBUT+NL";
+    break;
+  case IDENT:
+    p = "IDENT";
+    break;
+  case IDENT + ADD_NL:
+    p = "IDENT+NL";
+    break;
+  case SIDENT:
+    p = "SIDENT";
+    break;
+  case SIDENT + ADD_NL:
+    p = "SIDENT+NL";
+    break;
+  case KWORD:
+    p = "KWORD";
+    break;
+  case KWORD + ADD_NL:
+    p = "KWORD+NL";
+    break;
+  case SKWORD:
+    p = "SKWORD";
+    break;
+  case SKWORD + ADD_NL:
+    p = "SKWORD+NL";
+    break;
+  case FNAME:
+    p = "FNAME";
+    break;
+  case FNAME + ADD_NL:
+    p = "FNAME+NL";
+    break;
+  case SFNAME:
+    p = "SFNAME";
+    break;
+  case SFNAME + ADD_NL:
+    p = "SFNAME+NL";
+    break;
+  case PRINT:
+    p = "PRINT";
+    break;
+  case PRINT + ADD_NL:
+    p = "PRINT+NL";
+    break;
+  case SPRINT:
+    p = "SPRINT";
+    break;
+  case SPRINT + ADD_NL:
+    p = "SPRINT+NL";
+    break;
+  case WHITE:
+    p = "WHITE";
+    break;
+  case WHITE + ADD_NL:
+    p = "WHITE+NL";
+    break;
+  case NWHITE:
+    p = "NWHITE";
+    break;
+  case NWHITE + ADD_NL:
+    p = "NWHITE+NL";
+    break;
+  case DIGIT:
+    p = "DIGIT";
+    break;
+  case DIGIT + ADD_NL:
+    p = "DIGIT+NL";
+    break;
+  case NDIGIT:
+    p = "NDIGIT";
+    break;
+  case NDIGIT + ADD_NL:
+    p = "NDIGIT+NL";
+    break;
+  case HEX:
+    p = "HEX";
+    break;
+  case HEX + ADD_NL:
+    p = "HEX+NL";
+    break;
+  case NHEX:
+    p = "NHEX";
+    break;
+  case NHEX + ADD_NL:
+    p = "NHEX+NL";
+    break;
+  case OCTAL:
+    p = "OCTAL";
+    break;
+  case OCTAL + ADD_NL:
+    p = "OCTAL+NL";
+    break;
+  case NOCTAL:
+    p = "NOCTAL";
+    break;
+  case NOCTAL + ADD_NL:
+    p = "NOCTAL+NL";
+    break;
+  case WORD:
+    p = "WORD";
+    break;
+  case WORD + ADD_NL:
+    p = "WORD+NL";
+    break;
+  case NWORD:
+    p = "NWORD";
+    break;
+  case NWORD + ADD_NL:
+    p = "NWORD+NL";
+    break;
+  case HEAD:
+    p = "HEAD";
+    break;
+  case HEAD + ADD_NL:
+    p = "HEAD+NL";
+    break;
+  case NHEAD:
+    p = "NHEAD";
+    break;
+  case NHEAD + ADD_NL:
+    p = "NHEAD+NL";
+    break;
+  case ALPHA:
+    p = "ALPHA";
+    break;
+  case ALPHA + ADD_NL:
+    p = "ALPHA+NL";
+    break;
+  case NALPHA:
+    p = "NALPHA";
+    break;
+  case NALPHA + ADD_NL:
+    p = "NALPHA+NL";
+    break;
+  case LOWER:
+    p = "LOWER";
+    break;
+  case LOWER + ADD_NL:
+    p = "LOWER+NL";
+    break;
+  case NLOWER:
+    p = "NLOWER";
+    break;
+  case NLOWER + ADD_NL:
+    p = "NLOWER+NL";
+    break;
+  case UPPER:
+    p = "UPPER";
+    break;
+  case UPPER + ADD_NL:
+    p = "UPPER+NL";
+    break;
+  case NUPPER:
+    p = "NUPPER";
+    break;
+  case NUPPER + ADD_NL:
+    p = "NUPPER+NL";
+    break;
+  case BRANCH:
+    p = "BRANCH";
+    break;
+  case EXACTLY:
+    p = "EXACTLY";
+    break;
+  case NOTHING:
+    p = "NOTHING";
+    break;
+  case BACK:
+    p = "BACK";
+    break;
+  case END:
+    p = "END";
+    break;
+  case MOPEN + 0:
+    p = "MATCH START";
+    break;
+  case MOPEN + 1:
+  case MOPEN + 2:
+  case MOPEN + 3:
+  case MOPEN + 4:
+  case MOPEN + 5:
+  case MOPEN + 6:
+  case MOPEN + 7:
+  case MOPEN + 8:
+  case MOPEN + 9:
+    snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "MOPEN%d", OP(op) - MOPEN);
+    p = NULL;
+    break;
+  case MCLOSE + 0:
+    p = "MATCH END";
+    break;
+  case MCLOSE + 1:
+  case MCLOSE + 2:
+  case MCLOSE + 3:
+  case MCLOSE + 4:
+  case MCLOSE + 5:
+  case MCLOSE + 6:
+  case MCLOSE + 7:
+  case MCLOSE + 8:
+  case MCLOSE + 9:
+    snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "MCLOSE%d", OP(op) - MCLOSE);
+    p = NULL;
+    break;
+  case BACKREF + 1:
+  case BACKREF + 2:
+  case BACKREF + 3:
+  case BACKREF + 4:
+  case BACKREF + 5:
+  case BACKREF + 6:
+  case BACKREF + 7:
+  case BACKREF + 8:
+  case BACKREF + 9:
+    snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "BACKREF%d", OP(op) - BACKREF);
+    p = NULL;
+    break;
+  case NOPEN:
+    p = "NOPEN";
+    break;
+  case NCLOSE:
+    p = "NCLOSE";
+    break;
+  case ZOPEN + 1:
+  case ZOPEN + 2:
+  case ZOPEN + 3:
+  case ZOPEN + 4:
+  case ZOPEN + 5:
+  case ZOPEN + 6:
+  case ZOPEN + 7:
+  case ZOPEN + 8:
+  case ZOPEN + 9:
+    snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "ZOPEN%d", OP(op) - ZOPEN);
+    p = NULL;
+    break;
+  case ZCLOSE + 1:
+  case ZCLOSE + 2:
+  case ZCLOSE + 3:
+  case ZCLOSE + 4:
+  case ZCLOSE + 5:
+  case ZCLOSE + 6:
+  case ZCLOSE + 7:
+  case ZCLOSE + 8:
+  case ZCLOSE + 9:
+    snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "ZCLOSE%d", OP(op) - ZCLOSE);
+    p = NULL;
+    break;
+  case ZREF + 1:
+  case ZREF + 2:
+  case ZREF + 3:
+  case ZREF + 4:
+  case ZREF + 5:
+  case ZREF + 6:
+  case ZREF + 7:
+  case ZREF + 8:
+  case ZREF + 9:
+    snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "ZREF%d", OP(op) - ZREF);
+    p = NULL;
+    break;
+  case STAR:
+    p = "STAR";
+    break;
+  case PLUS:
+    p = "PLUS";
+    break;
+  case NOMATCH:
+    p = "NOMATCH";
+    break;
+  case MATCH:
+    p = "MATCH";
+    break;
+  case BEHIND:
+    p = "BEHIND";
+    break;
+  case NOBEHIND:
+    p = "NOBEHIND";
+    break;
+  case SUBPAT:
+    p = "SUBPAT";
+    break;
+  case BRACE_LIMITS:
+    p = "BRACE_LIMITS";
+    break;
+  case BRACE_SIMPLE:
+    p = "BRACE_SIMPLE";
+    break;
+  case BRACE_COMPLEX + 0:
+  case BRACE_COMPLEX + 1:
+  case BRACE_COMPLEX + 2:
+  case BRACE_COMPLEX + 3:
+  case BRACE_COMPLEX + 4:
+  case BRACE_COMPLEX + 5:
+  case BRACE_COMPLEX + 6:
+  case BRACE_COMPLEX + 7:
+  case BRACE_COMPLEX + 8:
+  case BRACE_COMPLEX + 9:
+    snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "BRACE_COMPLEX%d",
+             OP(op) - BRACE_COMPLEX);
+    p = NULL;
+    break;
+  case MULTIBYTECODE:
+    p = "MULTIBYTECODE";
+    break;
+  case NEWL:
+    p = "NEWL";
+    break;
+  default:
+    snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "corrupt %d", OP(op));
+    p = NULL;
+    break;
+  }
+  if (p != NULL) {
+    STRCAT(buf, p);
+  }
+  return (uint8_t *)buf;
+}
+#endif      // REGEXP_DEBUG
+
+// }}}1
+
+// regexp_nfa.c {{{1
+// NFA regular expression implementation.
+
+// Logging of NFA engine.
+//
+// The NFA engine can write four log files:
+// - Error log: Contains NFA engine's fatal errors.
+// - Dump log: Contains compiled NFA state machine's information.
+// - Run log: Contains information of matching procedure.
+// - Debug log: Contains detailed information of matching procedure. Can be
+//   disabled by undefining NFA_REGEXP_DEBUG_LOG.
+// The first one can also be used without debug mode.
+// The last three are enabled when compiled as debug mode and individually
+// disabled by commenting them out.
+// The log files can get quite big!
+// To disable all of this when compiling Vim for debugging, undefine REGEXP_DEBUG in
+// regexp.c
+#ifdef REGEXP_DEBUG
+# define NFA_REGEXP_ERROR_LOG   "nfa_regexp_error.log"
+# define NFA_REGEXP_DUMP_LOG    "nfa_regexp_dump.log"
+# define NFA_REGEXP_RUN_LOG     "nfa_regexp_run.log"
+# define NFA_REGEXP_DEBUG_LOG   "nfa_regexp_debug.log"
+#endif
+
+// Added to NFA_ANY - NFA_NUPPER_IC to include a NL.
+#define NFA_ADD_NL              31
+
+enum {
+  NFA_SPLIT = -1024,
+  NFA_MATCH,
+  NFA_EMPTY,                        // matches 0-length
+
+  NFA_START_COLL,                   // [abc] start
+  NFA_END_COLL,                     // [abc] end
+  NFA_START_NEG_COLL,               // [^abc] start
+  NFA_END_NEG_COLL,                 // [^abc] end (postfix only)
+  NFA_RANGE,                        // range of the two previous items
+                                    // (postfix only)
+  NFA_RANGE_MIN,                    // low end of a range
+  NFA_RANGE_MAX,                    // high end of a range
+
+  NFA_CONCAT,                       // concatenate two previous items (postfix
+                                    // only)
+  NFA_OR,                           // \| (postfix only)
+  NFA_STAR,                         // greedy * (postfix only)
+  NFA_STAR_NONGREEDY,               // non-greedy * (postfix only)
+  NFA_QUEST,                        // greedy \? (postfix only)
+  NFA_QUEST_NONGREEDY,              // non-greedy \? (postfix only)
+
+  NFA_BOL,                          // ^    Begin line
+  NFA_EOL,                          // $    End line
+  NFA_BOW,                          // \<   Begin word
+  NFA_EOW,                          // \>   End word
+  NFA_BOF,                          // \%^  Begin file
+  NFA_EOF,                          // \%$  End file
+  NFA_NEWL,
+  NFA_ZSTART,                       // Used for \zs
+  NFA_ZEND,                         // Used for \ze
+  NFA_NOPEN,                        // Start of subexpression marked with \%(
+  NFA_NCLOSE,                       // End of subexpr. marked with \%( ... \)
+  NFA_START_INVISIBLE,
+  NFA_START_INVISIBLE_FIRST,
+  NFA_START_INVISIBLE_NEG,
+  NFA_START_INVISIBLE_NEG_FIRST,
+  NFA_START_INVISIBLE_BEFORE,
+  NFA_START_INVISIBLE_BEFORE_FIRST,
+  NFA_START_INVISIBLE_BEFORE_NEG,
+  NFA_START_INVISIBLE_BEFORE_NEG_FIRST,
+  NFA_START_PATTERN,
+  NFA_END_INVISIBLE,
+  NFA_END_INVISIBLE_NEG,
+  NFA_END_PATTERN,
+  NFA_COMPOSING,                    // Next nodes in NFA are part of the
+                                    // composing multibyte char
+  NFA_END_COMPOSING,                // End of a composing char in the NFA
+  NFA_ANY_COMPOSING,                // \%C: Any composing characters.
+  NFA_OPT_CHARS,                    // \%[abc]
+
+  // The following are used only in the postfix form, not in the NFA
+  NFA_PREV_ATOM_NO_WIDTH,           // Used for \@=
+  NFA_PREV_ATOM_NO_WIDTH_NEG,       // Used for \@!
+  NFA_PREV_ATOM_JUST_BEFORE,        // Used for \@<=
+  NFA_PREV_ATOM_JUST_BEFORE_NEG,    // Used for \@<!
+  NFA_PREV_ATOM_LIKE_PATTERN,       // Used for \@>
+
+  NFA_BACKREF1,                     // \1
+  NFA_BACKREF2,                     // \2
+  NFA_BACKREF3,                     // \3
+  NFA_BACKREF4,                     // \4
+  NFA_BACKREF5,                     // \5
+  NFA_BACKREF6,                     // \6
+  NFA_BACKREF7,                     // \7
+  NFA_BACKREF8,                     // \8
+  NFA_BACKREF9,                     // \9
+  NFA_ZREF1,                        // \z1
+  NFA_ZREF2,                        // \z2
+  NFA_ZREF3,                        // \z3
+  NFA_ZREF4,                        // \z4
+  NFA_ZREF5,                        // \z5
+  NFA_ZREF6,                        // \z6
+  NFA_ZREF7,                        // \z7
+  NFA_ZREF8,                        // \z8
+  NFA_ZREF9,                        // \z9
+  NFA_SKIP,                         // Skip characters
+
+  NFA_MOPEN,
+  NFA_MOPEN1,
+  NFA_MOPEN2,
+  NFA_MOPEN3,
+  NFA_MOPEN4,
+  NFA_MOPEN5,
+  NFA_MOPEN6,
+  NFA_MOPEN7,
+  NFA_MOPEN8,
+  NFA_MOPEN9,
+
+  NFA_MCLOSE,
+  NFA_MCLOSE1,
+  NFA_MCLOSE2,
+  NFA_MCLOSE3,
+  NFA_MCLOSE4,
+  NFA_MCLOSE5,
+  NFA_MCLOSE6,
+  NFA_MCLOSE7,
+  NFA_MCLOSE8,
+  NFA_MCLOSE9,
+
+  NFA_ZOPEN,
+  NFA_ZOPEN1,
+  NFA_ZOPEN2,
+  NFA_ZOPEN3,
+  NFA_ZOPEN4,
+  NFA_ZOPEN5,
+  NFA_ZOPEN6,
+  NFA_ZOPEN7,
+  NFA_ZOPEN8,
+  NFA_ZOPEN9,
+
+  NFA_ZCLOSE,
+  NFA_ZCLOSE1,
+  NFA_ZCLOSE2,
+  NFA_ZCLOSE3,
+  NFA_ZCLOSE4,
+  NFA_ZCLOSE5,
+  NFA_ZCLOSE6,
+  NFA_ZCLOSE7,
+  NFA_ZCLOSE8,
+  NFA_ZCLOSE9,
+
+  // NFA_FIRST_NL
+  NFA_ANY,              //      Match any one character.
+  NFA_IDENT,            //      Match identifier char
+  NFA_SIDENT,           //      Match identifier char but no digit
+  NFA_KWORD,            //      Match keyword char
+  NFA_SKWORD,           //      Match word char but no digit
+  NFA_FNAME,            //      Match file name char
+  NFA_SFNAME,           //      Match file name char but no digit
+  NFA_PRINT,            //      Match printable char
+  NFA_SPRINT,           //      Match printable char but no digit
+  NFA_WHITE,            //      Match whitespace char
+  NFA_NWHITE,           //      Match non-whitespace char
+  NFA_DIGIT,            //      Match digit char
+  NFA_NDIGIT,           //      Match non-digit char
+  NFA_HEX,              //      Match hex char
+  NFA_NHEX,             //      Match non-hex char
+  NFA_OCTAL,            //      Match octal char
+  NFA_NOCTAL,           //      Match non-octal char
+  NFA_WORD,             //      Match word char
+  NFA_NWORD,            //      Match non-word char
+  NFA_HEAD,             //      Match head char
+  NFA_NHEAD,            //      Match non-head char
+  NFA_ALPHA,            //      Match alpha char
+  NFA_NALPHA,           //      Match non-alpha char
+  NFA_LOWER,            //      Match lowercase char
+  NFA_NLOWER,           //      Match non-lowercase char
+  NFA_UPPER,            //      Match uppercase char
+  NFA_NUPPER,           //      Match non-uppercase char
+  NFA_LOWER_IC,         //      Match [a-z]
+  NFA_NLOWER_IC,        //      Match [^a-z]
+  NFA_UPPER_IC,         //      Match [A-Z]
+  NFA_NUPPER_IC,        //      Match [^A-Z]
+
+  NFA_FIRST_NL = NFA_ANY + NFA_ADD_NL,
+  NFA_LAST_NL = NFA_NUPPER_IC + NFA_ADD_NL,
+
+  NFA_CURSOR,           //      Match cursor pos
+  NFA_LNUM,             //      Match line number
+  NFA_LNUM_GT,          //      Match > line number
+  NFA_LNUM_LT,          //      Match < line number
+  NFA_COL,              //      Match cursor column
+  NFA_COL_GT,           //      Match > cursor column
+  NFA_COL_LT,           //      Match < cursor column
+  NFA_VCOL,             //      Match cursor virtual column
+  NFA_VCOL_GT,          //      Match > cursor virtual column
+  NFA_VCOL_LT,          //      Match < cursor virtual column
+  NFA_MARK,             //      Match mark
+  NFA_MARK_GT,          //      Match > mark
+  NFA_MARK_LT,          //      Match < mark
+  NFA_VISUAL,           //      Match Visual area
+
+  // Character classes [:alnum:] etc
+  NFA_CLASS_ALNUM,
+  NFA_CLASS_ALPHA,
+  NFA_CLASS_BLANK,
+  NFA_CLASS_CNTRL,
+  NFA_CLASS_DIGIT,
+  NFA_CLASS_GRAPH,
+  NFA_CLASS_LOWER,
+  NFA_CLASS_PRINT,
+  NFA_CLASS_PUNCT,
+  NFA_CLASS_SPACE,
+  NFA_CLASS_UPPER,
+  NFA_CLASS_XDIGIT,
+  NFA_CLASS_TAB,
+  NFA_CLASS_RETURN,
+  NFA_CLASS_BACKSPACE,
+  NFA_CLASS_ESCAPE,
+  NFA_CLASS_IDENT,
+  NFA_CLASS_KEYWORD,
+  NFA_CLASS_FNAME,
+};
+
+// Keep in sync with classchars.
+static int nfa_classcodes[] = {
+  NFA_ANY, NFA_IDENT, NFA_SIDENT, NFA_KWORD, NFA_SKWORD,
+  NFA_FNAME, NFA_SFNAME, NFA_PRINT, NFA_SPRINT,
+  NFA_WHITE, NFA_NWHITE, NFA_DIGIT, NFA_NDIGIT,
+  NFA_HEX, NFA_NHEX, NFA_OCTAL, NFA_NOCTAL,
+  NFA_WORD, NFA_NWORD, NFA_HEAD, NFA_NHEAD,
+  NFA_ALPHA, NFA_NALPHA, NFA_LOWER, NFA_NLOWER,
+  NFA_UPPER, NFA_NUPPER
+};
+
+static const char e_nul_found[] = N_("E865: (NFA) Regexp end encountered prematurely");
+static const char e_misplaced[] = N_("E866: (NFA regexp) Misplaced %c");
+static const char e_ill_char_class[] = N_("E877: (NFA regexp) Invalid character class: %" PRId64);
+static const char e_value_too_large[] = N_("E951: \\% value too large");
+
+// Variables only used in nfa_regcomp() and descendants.
+static int nfa_re_flags;  ///< re_flags passed to nfa_regcomp().
+static int *post_start;   ///< holds the postfix form of r.e.
+static int *post_end;
+static int *post_ptr;
+
+// Set when the pattern should use the NFA engine.
+// E.g. [[:upper:]] only allows 8bit characters for BT engine,
+// while NFA engine handles multibyte characters correctly.
+static bool wants_nfa;
+
+static int nstate;  ///< Number of states in the NFA. Also used when executing.
+static int istate;  ///< Index in the state vector, used in alloc_state()
+
+// If not NULL match must end at this position
+static save_se_T *nfa_endp = NULL;
+
+// 0 for first call to nfa_regmatch(), 1 for recursive call.
+static int nfa_ll_index = 0;
+
+// Helper functions used when doing re2post() ... regatom() parsing
+#define EMIT(c) \
+  do { \
+    if (post_ptr >= post_end) { \
+      realloc_post_list(); \
+    } \
+    *post_ptr++ = c; \
+  } while (0)
+
+/// Initialize internal variables before NFA compilation.
+///
+/// @param re_flags  @see vim_regcomp()
+static void nfa_regcomp_start(uint8_t *expr, int re_flags)
+{
+  size_t postfix_size;
+  size_t nstate_max;
+
+  nstate = 0;
+  istate = 0;
+  // A reasonable estimation for maximum size
+  nstate_max = (strlen((char *)expr) + 1) * 25;
+
+  // Some items blow up in size, such as [A-z].  Add more space for that.
+  // When it is still not enough realloc_post_list() will be used.
+  nstate_max += 1000;
+
+  // Size for postfix representation of expr.
+  postfix_size = sizeof(int) * nstate_max;
+
+  post_start = (int *)xmalloc(postfix_size);
+  post_ptr = post_start;
+  post_end = post_start + nstate_max;
+  wants_nfa = false;
+  rex.nfa_has_zend = false;
+  rex.nfa_has_backref = false;
+
+  // shared with BT engine
+  regcomp_start(expr, re_flags);
+}
+
+// Figure out if the NFA state list starts with an anchor, must match at start
+// of the line.
+static int nfa_get_reganch(nfa_state_T *start, int depth)
+{
+  nfa_state_T *p = start;
+
+  if (depth > 4) {
+    return 0;
+  }
+
+  while (p != NULL) {
+    switch (p->c) {
+    case NFA_BOL:
+    case NFA_BOF:
+      return 1;           // yes!
+
+    case NFA_ZSTART:
+    case NFA_ZEND:
+    case NFA_CURSOR:
+    case NFA_VISUAL:
+
+    case NFA_MOPEN:
+    case NFA_MOPEN1:
+    case NFA_MOPEN2:
+    case NFA_MOPEN3:
+    case NFA_MOPEN4:
+    case NFA_MOPEN5:
+    case NFA_MOPEN6:
+    case NFA_MOPEN7:
+    case NFA_MOPEN8:
+    case NFA_MOPEN9:
+    case NFA_NOPEN:
+    case NFA_ZOPEN:
+    case NFA_ZOPEN1:
+    case NFA_ZOPEN2:
+    case NFA_ZOPEN3:
+    case NFA_ZOPEN4:
+    case NFA_ZOPEN5:
+    case NFA_ZOPEN6:
+    case NFA_ZOPEN7:
+    case NFA_ZOPEN8:
+    case NFA_ZOPEN9:
+      p = p->out;
+      break;
+
+    case NFA_SPLIT:
+      return nfa_get_reganch(p->out, depth + 1)
+             && nfa_get_reganch(p->out1, depth + 1);
+
+    default:
+      return 0;           // noooo
+    }
+  }
+  return 0;
+}
+
+// Figure out if the NFA state list starts with a character which must match
+// at start of the match.
+static int nfa_get_regstart(nfa_state_T *start, int depth)
+{
+  nfa_state_T *p = start;
+
+  if (depth > 4) {
+    return 0;
+  }
+
+  while (p != NULL) {
+    switch (p->c) {
+    // all kinds of zero-width matches
+    case NFA_BOL:
+    case NFA_BOF:
+    case NFA_BOW:
+    case NFA_EOW:
+    case NFA_ZSTART:
+    case NFA_ZEND:
+    case NFA_CURSOR:
+    case NFA_VISUAL:
+    case NFA_LNUM:
+    case NFA_LNUM_GT:
+    case NFA_LNUM_LT:
+    case NFA_COL:
+    case NFA_COL_GT:
+    case NFA_COL_LT:
+    case NFA_VCOL:
+    case NFA_VCOL_GT:
+    case NFA_VCOL_LT:
+    case NFA_MARK:
+    case NFA_MARK_GT:
+    case NFA_MARK_LT:
+
+    case NFA_MOPEN:
+    case NFA_MOPEN1:
+    case NFA_MOPEN2:
+    case NFA_MOPEN3:
+    case NFA_MOPEN4:
+    case NFA_MOPEN5:
+    case NFA_MOPEN6:
+    case NFA_MOPEN7:
+    case NFA_MOPEN8:
+    case NFA_MOPEN9:
+    case NFA_NOPEN:
+    case NFA_ZOPEN:
+    case NFA_ZOPEN1:
+    case NFA_ZOPEN2:
+    case NFA_ZOPEN3:
+    case NFA_ZOPEN4:
+    case NFA_ZOPEN5:
+    case NFA_ZOPEN6:
+    case NFA_ZOPEN7:
+    case NFA_ZOPEN8:
+    case NFA_ZOPEN9:
+      p = p->out;
+      break;
+
+    case NFA_SPLIT: {
+      int c1 = nfa_get_regstart(p->out, depth + 1);
+      int c2 = nfa_get_regstart(p->out1, depth + 1);
+
+      if (c1 == c2) {
+        return c1;             // yes!
+      }
+      return 0;
+    }
+
+    default:
+      if (p->c > 0) {
+        return p->c;             // yes!
+      }
+      return 0;
+    }
+  }
+  return 0;
+}
+
+// Figure out if the NFA state list contains just literal text and nothing
+// else.  If so return a string in allocated memory with what must match after
+// regstart.  Otherwise return NULL.
+static uint8_t *nfa_get_match_text(nfa_state_T *start)
+{
+  nfa_state_T *p = start;
+  int len = 0;
+  uint8_t *ret;
+  uint8_t *s;
+
+  if (p->c != NFA_MOPEN) {
+    return NULL;     // just in case
+  }
+  p = p->out;
+  while (p->c > 0) {
+    len += utf_char2len(p->c);
+    p = p->out;
+  }
+  if (p->c != NFA_MCLOSE || p->out->c != NFA_MATCH) {
+    return NULL;
+  }
+
+  ret = xmalloc((size_t)len);
+  p = start->out->out;     // skip first char, it goes into regstart
+  s = ret;
+  while (p->c > 0) {
+    s += utf_char2bytes(p->c, (char *)s);
+    p = p->out;
+  }
+  *s = NUL;
+
+  return ret;
+}
+
+// Allocate more space for post_start.  Called when
+// running above the estimated number of states.
+static void realloc_post_list(void)
+{
+  // For weird patterns the number of states can be very high. Increasing by
+  // 50% seems a reasonable compromise between memory use and speed.
+  const size_t new_max = (size_t)(post_end - post_start) * 3 / 2;
+  int *new_start = xrealloc(post_start, new_max * sizeof(int));
+  post_ptr = new_start + (post_ptr - post_start);
+  post_end = new_start + new_max;
+  post_start = new_start;
+}
+
+// Search between "start" and "end" and try to recognize a
+// character class in expanded form. For example [0-9].
+// On success, return the id the character class to be emitted.
+// On failure, return 0 (=FAIL)
+// Start points to the first char of the range, while end should point
+// to the closing brace.
+// Keep in mind that 'ignorecase' applies at execution time, thus [a-z] may
+// need to be interpreted as [a-zA-Z].
+static int nfa_recognize_char_class(uint8_t *start, const uint8_t *end, int extra_newl)
+{
+#define CLASS_not            0x80
+#define CLASS_af             0x40
+#define CLASS_AF             0x20
+#define CLASS_az             0x10
+#define CLASS_AZ             0x08
+#define CLASS_o7             0x04
+#define CLASS_o9             0x02
+#define CLASS_underscore     0x01
+
+  uint8_t *p;
+  int config = 0;
+
+  bool newl = extra_newl == true;
+
+  if (*end != ']') {
+    return FAIL;
+  }
+  p = start;
+  if (*p == '^') {
+    config |= CLASS_not;
+    p++;
+  }
+
+  while (p < end) {
+    if (p + 2 < end && *(p + 1) == '-') {
+      switch (*p) {
+      case '0':
+        if (*(p + 2) == '9') {
+          config |= CLASS_o9;
+          break;
+        } else if (*(p + 2) == '7') {
+          config |= CLASS_o7;
+          break;
+        }
+        return FAIL;
+      case 'a':
+        if (*(p + 2) == 'z') {
+          config |= CLASS_az;
+          break;
+        } else if (*(p + 2) == 'f') {
+          config |= CLASS_af;
+          break;
+        }
+        return FAIL;
+      case 'A':
+        if (*(p + 2) == 'Z') {
+          config |= CLASS_AZ;
+          break;
+        } else if (*(p + 2) == 'F') {
+          config |= CLASS_AF;
+          break;
+        }
+        return FAIL;
+      default:
+        return FAIL;
+      }
+      p += 3;
+    } else if (p + 1 < end && *p == '\\' && *(p + 1) == 'n') {
+      newl = true;
+      p += 2;
+    } else if (*p == '_') {
+      config |= CLASS_underscore;
+      p++;
+    } else if (*p == '\n') {
+      newl = true;
+      p++;
+    } else {
+      return FAIL;
+    }
+  }   // while (p < end)
+
+  if (p != end) {
+    return FAIL;
+  }
+
+  if (newl == true) {
+    extra_newl = NFA_ADD_NL;
+  }
+
+  switch (config) {
+  case CLASS_o9:
+    return extra_newl + NFA_DIGIT;
+  case CLASS_not |  CLASS_o9:
+    return extra_newl + NFA_NDIGIT;
+  case CLASS_af | CLASS_AF | CLASS_o9:
+    return extra_newl + NFA_HEX;
+  case CLASS_not | CLASS_af | CLASS_AF | CLASS_o9:
+    return extra_newl + NFA_NHEX;
+  case CLASS_o7:
+    return extra_newl + NFA_OCTAL;
+  case CLASS_not | CLASS_o7:
+    return extra_newl + NFA_NOCTAL;
+  case CLASS_az | CLASS_AZ | CLASS_o9 | CLASS_underscore:
+    return extra_newl + NFA_WORD;
+  case CLASS_not | CLASS_az | CLASS_AZ | CLASS_o9 | CLASS_underscore:
+    return extra_newl + NFA_NWORD;
+  case CLASS_az | CLASS_AZ | CLASS_underscore:
+    return extra_newl + NFA_HEAD;
+  case CLASS_not | CLASS_az | CLASS_AZ | CLASS_underscore:
+    return extra_newl + NFA_NHEAD;
+  case CLASS_az | CLASS_AZ:
+    return extra_newl + NFA_ALPHA;
+  case CLASS_not | CLASS_az | CLASS_AZ:
+    return extra_newl + NFA_NALPHA;
+  case CLASS_az:
+    return extra_newl + NFA_LOWER_IC;
+  case CLASS_not | CLASS_az:
+    return extra_newl + NFA_NLOWER_IC;
+  case CLASS_AZ:
+    return extra_newl + NFA_UPPER_IC;
+  case CLASS_not | CLASS_AZ:
+    return extra_newl + NFA_NUPPER_IC;
+  }
+  return FAIL;
+}
+
+// Produce the bytes for equivalence class "c".
+// Currently only handles latin1, latin9 and utf-8.
+// Emits bytes in postfix notation: 'a,b,NFA_OR,c,NFA_OR' is
+// equivalent to 'a OR b OR c'
+//
+// NOTE! When changing this function, also update reg_equi_class()
+static void nfa_emit_equi_class(int c)
+{
+#define EMIT2(c)   EMIT(c); EMIT(NFA_CONCAT);
+
+  {
+#define A_grave 0xc0
+#define A_acute 0xc1
+#define A_circumflex 0xc2
+#define A_virguilla 0xc3
+#define A_diaeresis 0xc4
+#define A_ring 0xc5
+#define C_cedilla 0xc7
+#define E_grave 0xc8
+#define E_acute 0xc9
+#define E_circumflex 0xca
+#define E_diaeresis 0xcb
+#define I_grave 0xcc
+#define I_acute 0xcd
+#define I_circumflex 0xce
+#define I_diaeresis 0xcf
+#define N_virguilla 0xd1
+#define O_grave 0xd2
+#define O_acute 0xd3
+#define O_circumflex 0xd4
+#define O_virguilla 0xd5
+#define O_diaeresis 0xd6
+#define O_slash 0xd8
+#define U_grave 0xd9
+#define U_acute 0xda
+#define U_circumflex 0xdb
+#define U_diaeresis 0xdc
+#define Y_acute 0xdd
+#define a_grave 0xe0
+#define a_acute 0xe1
+#define a_circumflex 0xe2
+#define a_virguilla 0xe3
+#define a_diaeresis 0xe4
+#define a_ring 0xe5
+#define c_cedilla 0xe7
+#define e_grave 0xe8
+#define e_acute 0xe9
+#define e_circumflex 0xea
+#define e_diaeresis 0xeb
+#define i_grave 0xec
+#define i_acute 0xed
+#define i_circumflex 0xee
+#define i_diaeresis 0xef
+#define n_virguilla 0xf1
+#define o_grave 0xf2
+#define o_acute 0xf3
+#define o_circumflex 0xf4
+#define o_virguilla 0xf5
+#define o_diaeresis 0xf6
+#define o_slash 0xf8
+#define u_grave 0xf9
+#define u_acute 0xfa
+#define u_circumflex 0xfb
+#define u_diaeresis 0xfc
+#define y_acute 0xfd
+#define y_diaeresis 0xff
+    switch (c) {
+    case 'A':
+    case A_grave:
+    case A_acute:
+    case A_circumflex:
+    case A_virguilla:
+    case A_diaeresis:
+    case A_ring:
+    case 0x100:
+    case 0x102:
+    case 0x104:
+    case 0x1cd:
+    case 0x1de:
+    case 0x1e0:
+    case 0x1fa:
+    case 0x200:
+    case 0x202:
+    case 0x226:
+    case 0x23a:
+    case 0x1e00:
+    case 0x1ea0:
+    case 0x1ea2:
+    case 0x1ea4:
+    case 0x1ea6:
+    case 0x1ea8:
+    case 0x1eaa:
+    case 0x1eac:
+    case 0x1eae:
+    case 0x1eb0:
+    case 0x1eb2:
+    case 0x1eb4:
+    case 0x1eb6:
+      EMIT2('A') EMIT2(A_grave) EMIT2(A_acute)  // NOLINT(whitespace/cast)
+      EMIT2(A_circumflex) EMIT2(A_virguilla)    // NOLINT(whitespace/cast)
+      EMIT2(A_diaeresis) EMIT2(A_ring)          // NOLINT(whitespace/cast)
+      EMIT2(0x100) EMIT2(0x102) EMIT2(0x104)
+      EMIT2(0x1cd) EMIT2(0x1de) EMIT2(0x1e0)
+      EMIT2(0x1fa) EMIT2(0x200) EMIT2(0x202)
+      EMIT2(0x226) EMIT2(0x23a) EMIT2(0x1e00)
+      EMIT2(0x1ea0) EMIT2(0x1ea2) EMIT2(0x1ea4)
+      EMIT2(0x1ea6) EMIT2(0x1ea8) EMIT2(0x1eaa)
+      EMIT2(0x1eac) EMIT2(0x1eae) EMIT2(0x1eb0)
+      EMIT2(0x1eb2) EMIT2(0x1eb6) EMIT2(0x1eb4)
+      return;
+
+    case 'B':
+    case 0x181:
+    case 0x243:
+    case 0x1e02:
+    case 0x1e04:
+    case 0x1e06:
+      EMIT2('B')
+      EMIT2(0x181) EMIT2(0x243) EMIT2(0x1e02)
+      EMIT2(0x1e04) EMIT2(0x1e06)
+      return;
+
+    case 'C':
+    case C_cedilla:
+    case 0x106:
+    case 0x108:
+    case 0x10a:
+    case 0x10c:
+    case 0x187:
+    case 0x23b:
+    case 0x1e08:
+    case 0xa792:
+      EMIT2('C') EMIT2(C_cedilla)
+      EMIT2(0x106) EMIT2(0x108) EMIT2(0x10a)
+      EMIT2(0x10c) EMIT2(0x187) EMIT2(0x23b)
+      EMIT2(0x1e08) EMIT2(0xa792)
+      return;
+
+    case 'D':
+    case 0x10e:
+    case 0x110:
+    case 0x18a:
+    case 0x1e0a:
+    case 0x1e0c:
+    case 0x1e0e:
+    case 0x1e10:
+    case 0x1e12:
+      EMIT2('D') EMIT2(0x10e) EMIT2(0x110) EMIT2(0x18a)
+      EMIT2(0x1e0a) EMIT2(0x1e0c) EMIT2(0x1e0e)
+      EMIT2(0x1e10) EMIT2(0x1e12)
+      return;
+
+    case 'E':
+    case E_grave:
+    case E_acute:
+    case E_circumflex:
+    case E_diaeresis:
+    case 0x112:
+    case 0x114:
+    case 0x116:
+    case 0x118:
+    case 0x11a:
+    case 0x204:
+    case 0x206:
+    case 0x228:
+    case 0x246:
+    case 0x1e14:
+    case 0x1e16:
+    case 0x1e18:
+    case 0x1e1a:
+    case 0x1e1c:
+    case 0x1eb8:
+    case 0x1eba:
+    case 0x1ebc:
+    case 0x1ebe:
+    case 0x1ec0:
+    case 0x1ec2:
+    case 0x1ec4:
+    case 0x1ec6:
+      EMIT2('E') EMIT2(E_grave) EMIT2(E_acute)  // NOLINT(whitespace/cast)
+      EMIT2(E_circumflex) EMIT2(E_diaeresis)    // NOLINT(whitespace/cast)
+      EMIT2(0x112) EMIT2(0x114) EMIT2(0x116)
+      EMIT2(0x118) EMIT2(0x11a) EMIT2(0x204)
+      EMIT2(0x206) EMIT2(0x228) EMIT2(0x246)
+      EMIT2(0x1e14) EMIT2(0x1e16) EMIT2(0x1e18)
+      EMIT2(0x1e1a) EMIT2(0x1e1c) EMIT2(0x1eb8)
+      EMIT2(0x1eba) EMIT2(0x1ebc) EMIT2(0x1ebe)
+      EMIT2(0x1ec0) EMIT2(0x1ec2) EMIT2(0x1ec4)
+      EMIT2(0x1ec6)
+      return;
+
+    case 'F':
+    case 0x191:
+    case 0x1e1e:
+    case 0xa798:
+      EMIT2('F') EMIT2(0x191) EMIT2(0x1e1e) EMIT2(0xa798)
+      return;
+
+    case 'G':
+    case 0x11c:
+    case 0x11e:
+    case 0x120:
+    case 0x122:
+    case 0x193:
+    case 0x1e4:
+    case 0x1e6:
+    case 0x1f4:
+    case 0x1e20:
+    case 0xa7a0:
+      EMIT2('G') EMIT2(0x11c) EMIT2(0x11e) EMIT2(0x120)
+      EMIT2(0x122) EMIT2(0x193) EMIT2(0x1e4)
+      EMIT2(0x1e6) EMIT2(0x1f4) EMIT2(0x1e20)
+      EMIT2(0xa7a0)
+      return;
+
+    case 'H':
+    case 0x124:
+    case 0x126:
+    case 0x21e:
+    case 0x1e22:
+    case 0x1e24:
+    case 0x1e26:
+    case 0x1e28:
+    case 0x1e2a:
+    case 0x2c67:
+      EMIT2('H') EMIT2(0x124) EMIT2(0x126) EMIT2(0x21e)
+      EMIT2(0x1e22) EMIT2(0x1e24) EMIT2(0x1e26)
+      EMIT2(0x1e28) EMIT2(0x1e2a) EMIT2(0x2c67)
+      return;
+
+    case 'I':
+    case I_grave:
+    case I_acute:
+    case I_circumflex:
+    case I_diaeresis:
+    case 0x128:
+    case 0x12a:
+    case 0x12c:
+    case 0x12e:
+    case 0x130:
+    case 0x197:
+    case 0x1cf:
+    case 0x208:
+    case 0x20a:
+    case 0x1e2c:
+    case 0x1e2e:
+    case 0x1ec8:
+    case 0x1eca:
+      EMIT2('I') EMIT2(I_grave) EMIT2(I_acute)  // NOLINT(whitespace/cast)
+      EMIT2(I_circumflex) EMIT2(I_diaeresis)    // NOLINT(whitespace/cast)
+      EMIT2(0x128) EMIT2(0x12a) EMIT2(0x12c)
+      EMIT2(0x12e) EMIT2(0x130) EMIT2(0x197)
+      EMIT2(0x1cf) EMIT2(0x208) EMIT2(0x20a)
+      EMIT2(0x1e2c) EMIT2(0x1e2e) EMIT2(0x1ec8)
+      EMIT2(0x1eca)
+      return;
+
+    case 'J':
+    case 0x134:
+    case 0x248:
+      EMIT2('J') EMIT2(0x134) EMIT2(0x248)
+      return;
+
+    case 'K':
+    case 0x136:
+    case 0x198:
+    case 0x1e8:
+    case 0x1e30:
+    case 0x1e32:
+    case 0x1e34:
+    case 0x2c69:
+    case 0xa740:
+      EMIT2('K') EMIT2(0x136) EMIT2(0x198) EMIT2(0x1e8)
+      EMIT2(0x1e30) EMIT2(0x1e32) EMIT2(0x1e34)
+      EMIT2(0x2c69) EMIT2(0xa740)
+      return;
+
+    case 'L':
+    case 0x139:
+    case 0x13b:
+    case 0x13d:
+    case 0x13f:
+    case 0x141:
+    case 0x23d:
+    case 0x1e36:
+    case 0x1e38:
+    case 0x1e3a:
+    case 0x1e3c:
+    case 0x2c60:
+      EMIT2('L') EMIT2(0x139) EMIT2(0x13b)
+      EMIT2(0x13d) EMIT2(0x13f) EMIT2(0x141)
+      EMIT2(0x23d) EMIT2(0x1e36) EMIT2(0x1e38)
+      EMIT2(0x1e3a) EMIT2(0x1e3c) EMIT2(0x2c60)
+      return;
+
+    case 'M':
+    case 0x1e3e:
+    case 0x1e40:
+    case 0x1e42:
+      EMIT2('M') EMIT2(0x1e3e) EMIT2(0x1e40)
+      EMIT2(0x1e42)
+      return;
+
+    case 'N':
+    case N_virguilla:
+    case 0x143:
+    case 0x145:
+    case 0x147:
+    case 0x1f8:
+    case 0x1e44:
+    case 0x1e46:
+    case 0x1e48:
+    case 0x1e4a:
+    case 0xa7a4:
+      EMIT2('N') EMIT2(N_virguilla)
+      EMIT2(0x143) EMIT2(0x145) EMIT2(0x147)
+      EMIT2(0x1f8) EMIT2(0x1e44) EMIT2(0x1e46)
+      EMIT2(0x1e48) EMIT2(0x1e4a) EMIT2(0xa7a4)
+      return;
+
+    case 'O':
+    case O_grave:
+    case O_acute:
+    case O_circumflex:
+    case O_virguilla:
+    case O_diaeresis:
+    case O_slash:
+    case 0x14c:
+    case 0x14e:
+    case 0x150:
+    case 0x19f:
+    case 0x1a0:
+    case 0x1d1:
+    case 0x1ea:
+    case 0x1ec:
+    case 0x1fe:
+    case 0x20c:
+    case 0x20e:
+    case 0x22a:
+    case 0x22c:
+    case 0x22e:
+    case 0x230:
+    case 0x1e4c:
+    case 0x1e4e:
+    case 0x1e50:
+    case 0x1e52:
+    case 0x1ecc:
+    case 0x1ece:
+    case 0x1ed0:
+    case 0x1ed2:
+    case 0x1ed4:
+    case 0x1ed6:
+    case 0x1ed8:
+    case 0x1eda:
+    case 0x1edc:
+    case 0x1ede:
+    case 0x1ee0:
+    case 0x1ee2:
+      EMIT2('O') EMIT2(O_grave) EMIT2(O_acute)  // NOLINT(whitespace/cast)
+      EMIT2(O_circumflex) EMIT2(O_virguilla)    // NOLINT(whitespace/cast)
+      EMIT2(O_diaeresis) EMIT2(O_slash)         // NOLINT(whitespace/cast)
+      EMIT2(0x14c) EMIT2(0x14e) EMIT2(0x150)
+      EMIT2(0x19f) EMIT2(0x1a0) EMIT2(0x1d1)
+      EMIT2(0x1ea) EMIT2(0x1ec) EMIT2(0x1fe)
+      EMIT2(0x20c) EMIT2(0x20e) EMIT2(0x22a)
+      EMIT2(0x22c) EMIT2(0x22e) EMIT2(0x230)
+      EMIT2(0x1e4c) EMIT2(0x1e4e) EMIT2(0x1e50)
+      EMIT2(0x1e52) EMIT2(0x1ecc) EMIT2(0x1ece)
+      EMIT2(0x1ed0) EMIT2(0x1ed2) EMIT2(0x1ed4)
+      EMIT2(0x1ed6) EMIT2(0x1ed8) EMIT2(0x1eda)
+      EMIT2(0x1edc) EMIT2(0x1ede) EMIT2(0x1ee0)
+      EMIT2(0x1ee2)
+      return;
+
+    case 'P':
+    case 0x1a4:
+    case 0x1e54:
+    case 0x1e56:
+    case 0x2c63:
+      EMIT2('P') EMIT2(0x1a4) EMIT2(0x1e54) EMIT2(0x1e56)
+      EMIT2(0x2c63)
+      return;
+
+    case 'Q':
+    case 0x24a:
+      EMIT2('Q') EMIT2(0x24a)
+      return;
+
+    case 'R':
+    case 0x154:
+    case 0x156:
+    case 0x158:
+    case 0x210:
+    case 0x212:
+    case 0x24c:
+    case 0x1e58:
+    case 0x1e5a:
+    case 0x1e5c:
+    case 0x1e5e:
+    case 0x2c64:
+    case 0xa7a6:
+      EMIT2('R') EMIT2(0x154) EMIT2(0x156) EMIT2(0x158)
+      EMIT2(0x210) EMIT2(0x212) EMIT2(0x24c) EMIT2(0x1e58)
+      EMIT2(0x1e5a) EMIT2(0x1e5c) EMIT2(0x1e5e) EMIT2(0x2c64)
+      EMIT2(0xa7a6)
+      return;
+
+    case 'S':
+    case 0x15a:
+    case 0x15c:
+    case 0x15e:
+    case 0x160:
+    case 0x218:
+    case 0x1e60:
+    case 0x1e62:
+    case 0x1e64:
+    case 0x1e66:
+    case 0x1e68:
+    case 0x2c7e:
+    case 0xa7a8:
+      EMIT2('S') EMIT2(0x15a) EMIT2(0x15c) EMIT2(0x15e)
+      EMIT2(0x160) EMIT2(0x218) EMIT2(0x1e60) EMIT2(0x1e62)
+      EMIT2(0x1e64) EMIT2(0x1e66) EMIT2(0x1e68) EMIT2(0x2c7e)
+      EMIT2(0xa7a8)
+      return;
+
+    case 'T':
+    case 0x162:
+    case 0x164:
+    case 0x166:
+    case 0x1ac:
+    case 0x1ae:
+    case 0x21a:
+    case 0x23e:
+    case 0x1e6a:
+    case 0x1e6c:
+    case 0x1e6e:
+    case 0x1e70:
+      EMIT2('T') EMIT2(0x162) EMIT2(0x164) EMIT2(0x166)
+      EMIT2(0x1ac) EMIT2(0x1ae) EMIT2(0x23e) EMIT2(0x21a)
+      EMIT2(0x1e6a) EMIT2(0x1e6c) EMIT2(0x1e6e) EMIT2(0x1e70)
+      return;
+
+    case 'U':
+    case U_grave:
+    case U_acute:
+    case U_diaeresis:
+    case U_circumflex:
+    case 0x168:
+    case 0x16a:
+    case 0x16c:
+    case 0x16e:
+    case 0x170:
+    case 0x172:
+    case 0x1af:
+    case 0x1d3:
+    case 0x1d5:
+    case 0x1d7:
+    case 0x1d9:
+    case 0x1db:
+    case 0x214:
+    case 0x216:
+    case 0x244:
+    case 0x1e72:
+    case 0x1e74:
+    case 0x1e76:
+    case 0x1e78:
+    case 0x1e7a:
+    case 0x1ee4:
+    case 0x1ee6:
+    case 0x1ee8:
+    case 0x1eea:
+    case 0x1eec:
+    case 0x1eee:
+    case 0x1ef0:
+      EMIT2('U') EMIT2(U_grave) EMIT2(U_acute)  // NOLINT(whitespace/cast)
+      EMIT2(U_diaeresis) EMIT2(U_circumflex)    // NOLINT(whitespace/cast)
+      EMIT2(0x168) EMIT2(0x16a)
+      EMIT2(0x16c) EMIT2(0x16e) EMIT2(0x170)
+      EMIT2(0x172) EMIT2(0x1af) EMIT2(0x1d3)
+      EMIT2(0x1d5) EMIT2(0x1d7) EMIT2(0x1d9)
+      EMIT2(0x1db) EMIT2(0x214) EMIT2(0x216)
+      EMIT2(0x244) EMIT2(0x1e72) EMIT2(0x1e74)
+      EMIT2(0x1e76) EMIT2(0x1e78) EMIT2(0x1e7a)
+      EMIT2(0x1ee4) EMIT2(0x1ee6) EMIT2(0x1ee8)
+      EMIT2(0x1eea) EMIT2(0x1eec) EMIT2(0x1eee)
+      EMIT2(0x1ef0)
+      return;
+
+    case 'V':
+    case 0x1b2:
+    case 0x1e7c:
+    case 0x1e7e:
+      EMIT2('V') EMIT2(0x1b2) EMIT2(0x1e7c) EMIT2(0x1e7e)
+      return;
+
+    case 'W':
+    case 0x174:
+    case 0x1e80:
+    case 0x1e82:
+    case 0x1e84:
+    case 0x1e86:
+    case 0x1e88:
+      EMIT2('W') EMIT2(0x174) EMIT2(0x1e80) EMIT2(0x1e82)
+      EMIT2(0x1e84) EMIT2(0x1e86) EMIT2(0x1e88)
+      return;
+
+    case 'X':
+    case 0x1e8a:
+    case 0x1e8c:
+      EMIT2('X') EMIT2(0x1e8a) EMIT2(0x1e8c)
+      return;
+
+    case 'Y':
+    case Y_acute:
+    case 0x176:
+    case 0x178:
+    case 0x1b3:
+    case 0x232:
+    case 0x24e:
+    case 0x1e8e:
+    case 0x1ef2:
+    case 0x1ef4:
+    case 0x1ef6:
+    case 0x1ef8:
+      EMIT2('Y') EMIT2(Y_acute)
+      EMIT2(0x176) EMIT2(0x178) EMIT2(0x1b3)
+      EMIT2(0x232) EMIT2(0x24e) EMIT2(0x1e8e)
+      EMIT2(0x1ef2) EMIT2(0x1ef4) EMIT2(0x1ef6)
+      EMIT2(0x1ef8)
+      return;
+
+    case 'Z':
+    case 0x179:
+    case 0x17b:
+    case 0x17d:
+    case 0x1b5:
+    case 0x1e90:
+    case 0x1e92:
+    case 0x1e94:
+    case 0x2c6b:
+      EMIT2('Z') EMIT2(0x179) EMIT2(0x17b) EMIT2(0x17d)
+      EMIT2(0x1b5) EMIT2(0x1e90) EMIT2(0x1e92)
+      EMIT2(0x1e94) EMIT2(0x2c6b)
+      return;
+
+    case 'a':
+    case a_grave:
+    case a_acute:
+    case a_circumflex:
+    case a_virguilla:
+    case a_diaeresis:
+    case a_ring:
+    case 0x101:
+    case 0x103:
+    case 0x105:
+    case 0x1ce:
+    case 0x1df:
+    case 0x1e1:
+    case 0x1fb:
+    case 0x201:
+    case 0x203:
+    case 0x227:
+    case 0x1d8f:
+    case 0x1e01:
+    case 0x1e9a:
+    case 0x1ea1:
+    case 0x1ea3:
+    case 0x1ea5:
+    case 0x1ea7:
+    case 0x1ea9:
+    case 0x1eab:
+    case 0x1ead:
+    case 0x1eaf:
+    case 0x1eb1:
+    case 0x1eb3:
+    case 0x1eb5:
+    case 0x1eb7:
+    case 0x2c65:
+      EMIT2('a') EMIT2(a_grave) EMIT2(a_acute)  // NOLINT(whitespace/cast)
+      EMIT2(a_circumflex) EMIT2(a_virguilla)    // NOLINT(whitespace/cast)
+      EMIT2(a_diaeresis) EMIT2(a_ring)          // NOLINT(whitespace/cast)
+      EMIT2(0x101) EMIT2(0x103) EMIT2(0x105)
+      EMIT2(0x1ce) EMIT2(0x1df) EMIT2(0x1e1)
+      EMIT2(0x1fb) EMIT2(0x201) EMIT2(0x203)
+      EMIT2(0x227) EMIT2(0x1d8f) EMIT2(0x1e01)
+      EMIT2(0x1e9a) EMIT2(0x1ea1) EMIT2(0x1ea3)
+      EMIT2(0x1ea5) EMIT2(0x1ea7) EMIT2(0x1ea9)
+      EMIT2(0x1eab) EMIT2(0x1ead) EMIT2(0x1eaf)
+      EMIT2(0x1eb1) EMIT2(0x1eb3) EMIT2(0x1eb5)
+      EMIT2(0x1eb7) EMIT2(0x2c65)
+      return;
+
+    case 'b':
+    case 0x180:
+    case 0x253:
+    case 0x1d6c:
+    case 0x1d80:
+    case 0x1e03:
+    case 0x1e05:
+    case 0x1e07:
+      EMIT2('b') EMIT2(0x180) EMIT2(0x253) EMIT2(0x1d6c)
+      EMIT2(0x1d80) EMIT2(0x1e03) EMIT2(0x1e05) EMIT2(0x1e07)
+      return;
+
+    case 'c':
+    case c_cedilla:
+    case 0x107:
+    case 0x109:
+    case 0x10b:
+    case 0x10d:
+    case 0x188:
+    case 0x23c:
+    case 0x1e09:
+    case 0xa793:
+    case 0xa794:
+      EMIT2('c') EMIT2(c_cedilla)
+      EMIT2(0x107) EMIT2(0x109) EMIT2(0x10b)
+      EMIT2(0x10d) EMIT2(0x188) EMIT2(0x23c)
+      EMIT2(0x1e09) EMIT2(0xa793) EMIT2(0xa794)
+      return;
+
+    case 'd':
+    case 0x10f:
+    case 0x111:
+    case 0x257:
+    case 0x1d6d:
+    case 0x1d81:
+    case 0x1d91:
+    case 0x1e0b:
+    case 0x1e0d:
+    case 0x1e0f:
+    case 0x1e11:
+    case 0x1e13:
+      EMIT2('d') EMIT2(0x10f) EMIT2(0x111)
+      EMIT2(0x257) EMIT2(0x1d6d) EMIT2(0x1d81)
+      EMIT2(0x1d91) EMIT2(0x1e0b) EMIT2(0x1e0d)
+      EMIT2(0x1e0f) EMIT2(0x1e11) EMIT2(0x1e13)
+      return;
+
+    case 'e':
+    case e_grave:
+    case e_acute:
+    case e_circumflex:
+    case e_diaeresis:
+    case 0x113:
+    case 0x115:
+    case 0x117:
+    case 0x119:
+    case 0x11b:
+    case 0x205:
+    case 0x207:
+    case 0x229:
+    case 0x247:
+    case 0x1d92:
+    case 0x1e15:
+    case 0x1e17:
+    case 0x1e19:
+    case 0x1e1b:
+    case 0x1e1d:
+    case 0x1eb9:
+    case 0x1ebb:
+    case 0x1ebd:
+    case 0x1ebf:
+    case 0x1ec1:
+    case 0x1ec3:
+    case 0x1ec5:
+    case 0x1ec7:
+      EMIT2('e') EMIT2(e_grave) EMIT2(e_acute)  // NOLINT(whitespace/cast)
+      EMIT2(e_circumflex) EMIT2(e_diaeresis)    // NOLINT(whitespace/cast)
+      EMIT2(0x113) EMIT2(0x115)
+      EMIT2(0x117) EMIT2(0x119) EMIT2(0x11b)
+      EMIT2(0x205) EMIT2(0x207) EMIT2(0x229)
+      EMIT2(0x247) EMIT2(0x1d92) EMIT2(0x1e15)
+      EMIT2(0x1e17) EMIT2(0x1e19) EMIT2(0x1e1b)
+      EMIT2(0x1e1d) EMIT2(0x1eb9) EMIT2(0x1ebb)
+      EMIT2(0x1ebd) EMIT2(0x1ebf) EMIT2(0x1ec1)
+      EMIT2(0x1ec3) EMIT2(0x1ec5) EMIT2(0x1ec7)
+      return;
+
+    case 'f':
+    case 0x192:
+    case 0x1d6e:
+    case 0x1d82:
+    case 0x1e1f:
+    case 0xa799:
+      EMIT2('f') EMIT2(0x192) EMIT2(0x1d6e) EMIT2(0x1d82)
+      EMIT2(0x1e1f) EMIT2(0xa799)
+      return;
+
+    case 'g':
+    case 0x11d:
+    case 0x11f:
+    case 0x121:
+    case 0x123:
+    case 0x1e5:
+    case 0x1e7:
+    case 0x1f5:
+    case 0x260:
+    case 0x1d83:
+    case 0x1e21:
+    case 0xa7a1:
+      EMIT2('g') EMIT2(0x11d) EMIT2(0x11f) EMIT2(0x121)
+      EMIT2(0x123) EMIT2(0x1e5) EMIT2(0x1e7)
+      EMIT2(0x1f5) EMIT2(0x260) EMIT2(0x1d83)
+      EMIT2(0x1e21) EMIT2(0xa7a1)
+      return;
+
+    case 'h':
+    case 0x125:
+    case 0x127:
+    case 0x21f:
+    case 0x1e23:
+    case 0x1e25:
+    case 0x1e27:
+    case 0x1e29:
+    case 0x1e2b:
+    case 0x1e96:
+    case 0x2c68:
+    case 0xa795:
+      EMIT2('h') EMIT2(0x125) EMIT2(0x127) EMIT2(0x21f)
+      EMIT2(0x1e23) EMIT2(0x1e25) EMIT2(0x1e27)
+      EMIT2(0x1e29) EMIT2(0x1e2b) EMIT2(0x1e96)
+      EMIT2(0x2c68) EMIT2(0xa795)
+      return;
+
+    case 'i':
+    case i_grave:
+    case i_acute:
+    case i_circumflex:
+    case i_diaeresis:
+    case 0x129:
+    case 0x12b:
+    case 0x12d:
+    case 0x12f:
+    case 0x1d0:
+    case 0x209:
+    case 0x20b:
+    case 0x268:
+    case 0x1d96:
+    case 0x1e2d:
+    case 0x1e2f:
+    case 0x1ec9:
+    case 0x1ecb:
+      EMIT2('i') EMIT2(i_grave) EMIT2(i_acute)  // NOLINT(whitespace/cast)
+      EMIT2(i_circumflex) EMIT2(i_diaeresis)    // NOLINT(whitespace/cast)
+      EMIT2(0x129) EMIT2(0x12b) EMIT2(0x12d)
+      EMIT2(0x12f) EMIT2(0x1d0) EMIT2(0x209)
+      EMIT2(0x20b) EMIT2(0x268) EMIT2(0x1d96)
+      EMIT2(0x1e2d) EMIT2(0x1e2f) EMIT2(0x1ec9)
+      EMIT2(0x1ecb) EMIT2(0x1ecb)
+      return;
+
+    case 'j':
+    case 0x135:
+    case 0x1f0:
+    case 0x249:
+      EMIT2('j') EMIT2(0x135) EMIT2(0x1f0) EMIT2(0x249)
+      return;
+
+    case 'k':
+    case 0x137:
+    case 0x199:
+    case 0x1e9:
+    case 0x1d84:
+    case 0x1e31:
+    case 0x1e33:
+    case 0x1e35:
+    case 0x2c6a:
+    case 0xa741:
+      EMIT2('k') EMIT2(0x137) EMIT2(0x199) EMIT2(0x1e9)
+      EMIT2(0x1d84) EMIT2(0x1e31) EMIT2(0x1e33)
+      EMIT2(0x1e35) EMIT2(0x2c6a) EMIT2(0xa741)
+      return;
+
+    case 'l':
+    case 0x13a:
+    case 0x13c:
+    case 0x13e:
+    case 0x140:
+    case 0x142:
+    case 0x19a:
+    case 0x1e37:
+    case 0x1e39:
+    case 0x1e3b:
+    case 0x1e3d:
+    case 0x2c61:
+      EMIT2('l') EMIT2(0x13a) EMIT2(0x13c)
+      EMIT2(0x13e) EMIT2(0x140) EMIT2(0x142)
+      EMIT2(0x19a) EMIT2(0x1e37) EMIT2(0x1e39)
+      EMIT2(0x1e3b) EMIT2(0x1e3d) EMIT2(0x2c61)
+      return;
+
+    case 'm':
+    case 0x1d6f:
+    case 0x1e3f:
+    case 0x1e41:
+    case 0x1e43:
+      EMIT2('m') EMIT2(0x1d6f) EMIT2(0x1e3f)
+      EMIT2(0x1e41) EMIT2(0x1e43)
+      return;
+
+    case 'n':
+    case n_virguilla:
+    case 0x144:
+    case 0x146:
+    case 0x148:
+    case 0x149:
+    case 0x1f9:
+    case 0x1d70:
+    case 0x1d87:
+    case 0x1e45:
+    case 0x1e47:
+    case 0x1e49:
+    case 0x1e4b:
+    case 0xa7a5:
+      EMIT2('n') EMIT2(n_virguilla)
+      EMIT2(0x144) EMIT2(0x146) EMIT2(0x148)
+      EMIT2(0x149) EMIT2(0x1f9) EMIT2(0x1d70)
+      EMIT2(0x1d87) EMIT2(0x1e45) EMIT2(0x1e47)
+      EMIT2(0x1e49) EMIT2(0x1e4b) EMIT2(0xa7a5)
+      return;
+
+    case 'o':
+    case o_grave:
+    case o_acute:
+    case o_circumflex:
+    case o_virguilla:
+    case o_diaeresis:
+    case o_slash:
+    case 0x14d:
+    case 0x14f:
+    case 0x151:
+    case 0x1a1:
+    case 0x1d2:
+    case 0x1eb:
+    case 0x1ed:
+    case 0x1ff:
+    case 0x20d:
+    case 0x20f:
+    case 0x22b:
+    case 0x22d:
+    case 0x22f:
+    case 0x231:
+    case 0x275:
+    case 0x1e4d:
+    case 0x1e4f:
+    case 0x1e51:
+    case 0x1e53:
+    case 0x1ecd:
+    case 0x1ecf:
+    case 0x1ed1:
+    case 0x1ed3:
+    case 0x1ed5:
+    case 0x1ed7:
+    case 0x1ed9:
+    case 0x1edb:
+    case 0x1edd:
+    case 0x1edf:
+    case 0x1ee1:
+    case 0x1ee3:
+      EMIT2('o') EMIT2(o_grave) EMIT2(o_acute)  // NOLINT(whitespace/cast)
+      EMIT2(o_circumflex) EMIT2(o_virguilla)    // NOLINT(whitespace/cast)
+      EMIT2(o_diaeresis) EMIT2(o_slash)         // NOLINT(whitespace/cast)
+      EMIT2(0x14d) EMIT2(0x14f) EMIT2(0x151)
+      EMIT2(0x1a1) EMIT2(0x1d2) EMIT2(0x1eb)
+      EMIT2(0x1ed) EMIT2(0x1ff) EMIT2(0x20d)
+      EMIT2(0x20f) EMIT2(0x22b) EMIT2(0x22d)
+      EMIT2(0x22f) EMIT2(0x231) EMIT2(0x275)
+      EMIT2(0x1e4d) EMIT2(0x1e4f) EMIT2(0x1e51)
+      EMIT2(0x1e53) EMIT2(0x1ecd) EMIT2(0x1ecf)
+      EMIT2(0x1ed1) EMIT2(0x1ed3) EMIT2(0x1ed5)
+      EMIT2(0x1ed7) EMIT2(0x1ed9) EMIT2(0x1edb)
+      EMIT2(0x1edd) EMIT2(0x1edf) EMIT2(0x1ee1)
+      EMIT2(0x1ee3)
+      return;
+
+    case 'p':
+    case 0x1a5:
+    case 0x1d71:
+    case 0x1d7d:
+    case 0x1d88:
+    case 0x1e55:
+    case 0x1e57:
+      EMIT2('p') EMIT2(0x1a5) EMIT2(0x1d71) EMIT2(0x1d7d)
+      EMIT2(0x1d88) EMIT2(0x1e55) EMIT2(0x1e57)
+      return;
+
+    case 'q':
+    case 0x24b:
+    case 0x2a0:
+      EMIT2('q') EMIT2(0x24b) EMIT2(0x2a0)
+      return;
+
+    case 'r':
+    case 0x155:
+    case 0x157:
+    case 0x159:
+    case 0x211:
+    case 0x213:
+    case 0x24d:
+    case 0x27d:
+    case 0x1d72:
+    case 0x1d73:
+    case 0x1d89:
+    case 0x1e59:
+    case 0x1e5b:
+    case 0x1e5d:
+    case 0x1e5f:
+    case 0xa7a7:
+      EMIT2('r') EMIT2(0x155) EMIT2(0x157) EMIT2(0x159)
+      EMIT2(0x211) EMIT2(0x213) EMIT2(0x24d) EMIT2(0x27d)
+      EMIT2(0x1d72) EMIT2(0x1d73) EMIT2(0x1d89) EMIT2(0x1e59)
+      EMIT2(0x1e5b) EMIT2(0x1e5d) EMIT2(0x1e5f) EMIT2(0xa7a7)
+      return;
+
+    case 's':
+    case 0x15b:
+    case 0x15d:
+    case 0x15f:
+    case 0x161:
+    case 0x219:
+    case 0x23f:
+    case 0x1d74:
+    case 0x1d8a:
+    case 0x1e61:
+    case 0x1e63:
+    case 0x1e65:
+    case 0x1e67:
+    case 0x1e69:
+    case 0xa7a9:
+      EMIT2('s') EMIT2(0x15b) EMIT2(0x15d) EMIT2(0x15f)
+      EMIT2(0x161) EMIT2(0x219) EMIT2(0x23f) EMIT2(0x1d74)
+      EMIT2(0x1d8a) EMIT2(0x1e61) EMIT2(0x1e63) EMIT2(0x1e65)
+      EMIT2(0x1e67) EMIT2(0x1e69) EMIT2(0xa7a9)
+      return;
+
+    case 't':
+    case 0x163:
+    case 0x165:
+    case 0x167:
+    case 0x1ab:
+    case 0x1ad:
+    case 0x21b:
+    case 0x288:
+    case 0x1d75:
+    case 0x1e6b:
+    case 0x1e6d:
+    case 0x1e6f:
+    case 0x1e71:
+    case 0x1e97:
+    case 0x2c66:
+      EMIT2('t') EMIT2(0x163) EMIT2(0x165) EMIT2(0x167)
+      EMIT2(0x1ab) EMIT2(0x1ad) EMIT2(0x21b) EMIT2(0x288)
+      EMIT2(0x1d75) EMIT2(0x1e6b) EMIT2(0x1e6d) EMIT2(0x1e6f)
+      EMIT2(0x1e71) EMIT2(0x1e97) EMIT2(0x2c66)
+      return;
+
+    case 'u':
+    case u_grave:
+    case u_acute:
+    case u_circumflex:
+    case u_diaeresis:
+    case 0x169:
+    case 0x16b:
+    case 0x16d:
+    case 0x16f:
+    case 0x171:
+    case 0x173:
+    case 0x1b0:
+    case 0x1d4:
+    case 0x1d6:
+    case 0x1d8:
+    case 0x1da:
+    case 0x1dc:
+    case 0x215:
+    case 0x217:
+    case 0x289:
+    case 0x1d7e:
+    case 0x1d99:
+    case 0x1e73:
+    case 0x1e75:
+    case 0x1e77:
+    case 0x1e79:
+    case 0x1e7b:
+    case 0x1ee5:
+    case 0x1ee7:
+    case 0x1ee9:
+    case 0x1eeb:
+    case 0x1eed:
+    case 0x1eef:
+    case 0x1ef1:
+      EMIT2('u') EMIT2(u_grave) EMIT2(u_acute)  // NOLINT(whitespace/cast)
+      EMIT2(u_circumflex) EMIT2(u_diaeresis)    // NOLINT(whitespace/cast)
+      EMIT2(0x169) EMIT2(0x16b)
+      EMIT2(0x16d) EMIT2(0x16f) EMIT2(0x171)
+      EMIT2(0x173) EMIT2(0x1d6) EMIT2(0x1d8)
+      EMIT2(0x215) EMIT2(0x217) EMIT2(0x1b0)
+      EMIT2(0x1d4) EMIT2(0x1da) EMIT2(0x1dc)
+      EMIT2(0x289) EMIT2(0x1e73) EMIT2(0x1d7e)
+      EMIT2(0x1d99) EMIT2(0x1e75) EMIT2(0x1e77)
+      EMIT2(0x1e79) EMIT2(0x1e7b) EMIT2(0x1ee5)
+      EMIT2(0x1ee7) EMIT2(0x1ee9) EMIT2(0x1eeb)
+      EMIT2(0x1eed) EMIT2(0x1eef) EMIT2(0x1ef1)
+      return;
+
+    case 'v':
+    case 0x28b:
+    case 0x1d8c:
+    case 0x1e7d:
+    case 0x1e7f:
+      EMIT2('v') EMIT2(0x28b) EMIT2(0x1d8c) EMIT2(0x1e7d)
+      EMIT2(0x1e7f)
+      return;
+
+    case 'w':
+    case 0x175:
+    case 0x1e81:
+    case 0x1e83:
+    case 0x1e85:
+    case 0x1e87:
+    case 0x1e89:
+    case 0x1e98:
+      EMIT2('w') EMIT2(0x175) EMIT2(0x1e81) EMIT2(0x1e83)
+      EMIT2(0x1e85) EMIT2(0x1e87) EMIT2(0x1e89) EMIT2(0x1e98)
+      return;
+
+    case 'x':
+    case 0x1e8b:
+    case 0x1e8d:
+      EMIT2('x') EMIT2(0x1e8b) EMIT2(0x1e8d)
+      return;
+
+    case 'y':
+    case y_acute:
+    case y_diaeresis:
+    case 0x177:
+    case 0x1b4:
+    case 0x233:
+    case 0x24f:
+    case 0x1e8f:
+    case 0x1e99:
+    case 0x1ef3:
+    case 0x1ef5:
+    case 0x1ef7:
+    case 0x1ef9:
+      EMIT2('y') EMIT2(y_acute) EMIT2(y_diaeresis)  // NOLINT(whitespace/cast)
+      EMIT2(0x177) EMIT2(0x1b4) EMIT2(0x233) EMIT2(0x24f)
+      EMIT2(0x1e8f) EMIT2(0x1e99) EMIT2(0x1ef3)
+      EMIT2(0x1ef5) EMIT2(0x1ef7) EMIT2(0x1ef9)
+      return;
+
+    case 'z':
+    case 0x17a:
+    case 0x17c:
+    case 0x17e:
+    case 0x1b6:
+    case 0x1d76:
+    case 0x1d8e:
+    case 0x1e91:
+    case 0x1e93:
+    case 0x1e95:
+    case 0x2c6c:
+      EMIT2('z') EMIT2(0x17a) EMIT2(0x17c) EMIT2(0x17e)
+      EMIT2(0x1b6) EMIT2(0x1d76) EMIT2(0x1d8e) EMIT2(0x1e91)
+      EMIT2(0x1e93) EMIT2(0x1e95) EMIT2(0x2c6c)
+      return;
+
+      // default: character itself
+    }
+  }
+
+  EMIT2(c);
+#undef EMIT2
+}
+
+// Code to parse regular expression.
+//
+// We try to reuse parsing functions in regexp.c to
+// minimize surprise and keep the syntax consistent.
+
+// Parse the lowest level.
+//
+// An atom can be one of a long list of items.  Many atoms match one character
+// in the text.  It is often an ordinary character or a character class.
+// Braces can be used to make a pattern into an atom.  The "\z(\)" construct
+// is only for syntax highlighting.
+//
+// atom    ::=     ordinary-atom
+//     or  \( pattern \)
+//     or  \%( pattern \)
+//     or  \z( pattern \)
+static int nfa_regatom(void)
+{
+  int c;
+  int charclass;
+  int equiclass;
+  int collclass;
+  int got_coll_char;
+  uint8_t *p;
+  uint8_t *endp;
+  uint8_t *old_regparse = (uint8_t *)regparse;
+  int extra = 0;
+  int emit_range;
+  int negated;
+  int startc = -1;
+  int save_prev_at_start = prev_at_start;
+
+  c = getchr();
+  switch (c) {
+  case NUL:
+    EMSG_RET_FAIL(_(e_nul_found));
+
+  case Magic('^'):
+    EMIT(NFA_BOL);
+    break;
+
+  case Magic('$'):
+    EMIT(NFA_EOL);
+    had_eol = true;
+    break;
+
+  case Magic('<'):
+    EMIT(NFA_BOW);
+    break;
+
+  case Magic('>'):
+    EMIT(NFA_EOW);
+    break;
+
+  case Magic('_'):
+    c = no_Magic(getchr());
+    if (c == NUL) {
+      EMSG_RET_FAIL(_(e_nul_found));
+    }
+
+    if (c == '^') {             // "\_^" is start-of-line
+      EMIT(NFA_BOL);
+      break;
+    }
+    if (c == '$') {             // "\_$" is end-of-line
+      EMIT(NFA_EOL);
+      had_eol = true;
+      break;
+    }
+
+    extra = NFA_ADD_NL;
+
+    // "\_[" is collection plus newline
+    if (c == '[') {
+      goto collection;
+    }
+
+    // "\_x" is character class plus newline
+    FALLTHROUGH;
+
+  // Character classes.
+  case Magic('.'):
+  case Magic('i'):
+  case Magic('I'):
+  case Magic('k'):
+  case Magic('K'):
+  case Magic('f'):
+  case Magic('F'):
+  case Magic('p'):
+  case Magic('P'):
+  case Magic('s'):
+  case Magic('S'):
+  case Magic('d'):
+  case Magic('D'):
+  case Magic('x'):
+  case Magic('X'):
+  case Magic('o'):
+  case Magic('O'):
+  case Magic('w'):
+  case Magic('W'):
+  case Magic('h'):
+  case Magic('H'):
+  case Magic('a'):
+  case Magic('A'):
+  case Magic('l'):
+  case Magic('L'):
+  case Magic('u'):
+  case Magic('U'):
+    p = (uint8_t *)vim_strchr((char *)classchars, no_Magic(c));
+    if (p == NULL) {
+      if (extra == NFA_ADD_NL) {
+        semsg(_(e_ill_char_class), (int64_t)c);
+        rc_did_emsg = true;
+        return FAIL;
+      }
+      siemsg("INTERNAL: Unknown character class char: %" PRId64, (int64_t)c);
+      return FAIL;
+    }
+    // When '.' is followed by a composing char ignore the dot, so that
+    // the composing char is matched here.
+    if (c == Magic('.') && utf_iscomposing(peekchr())) {
+      old_regparse = (uint8_t *)regparse;
+      c = getchr();
+      goto nfa_do_multibyte;
+    }
+    EMIT(nfa_classcodes[p - classchars]);
+    if (extra == NFA_ADD_NL) {
+      EMIT(NFA_NEWL);
+      EMIT(NFA_OR);
+      regflags |= RF_HASNL;
+    }
+    break;
+
+  case Magic('n'):
+    if (reg_string) {
+      // In a string "\n" matches a newline character.
+      EMIT(NL);
+    } else {
+      // In buffer text "\n" matches the end of a line.
+      EMIT(NFA_NEWL);
+      regflags |= RF_HASNL;
+    }
+    break;
+
+  case Magic('('):
+    if (nfa_reg(REG_PAREN) == FAIL) {
+      return FAIL;                  // cascaded error
+    }
+    break;
+
+  case Magic('|'):
+  case Magic('&'):
+  case Magic(')'):
+    semsg(_(e_misplaced), (char)no_Magic(c));
+    return FAIL;
+
+  case Magic('='):
+  case Magic('?'):
+  case Magic('+'):
+  case Magic('@'):
+  case Magic('*'):
+  case Magic('{'):
+    // these should follow an atom, not form an atom
+    semsg(_(e_misplaced), (char)no_Magic(c));
+    return FAIL;
+
+  case Magic('~'): {
+    uint8_t *lp;
+
+    // Previous substitute pattern.
+    // Generated as "\%(pattern\)".
+    if (reg_prev_sub == NULL) {
+      emsg(_(e_nopresub));
+      return FAIL;
+    }
+    for (lp = (uint8_t *)reg_prev_sub; *lp != NUL; MB_CPTR_ADV(lp)) {
+      EMIT(utf_ptr2char((char *)lp));
+      if (lp != (uint8_t *)reg_prev_sub) {
+        EMIT(NFA_CONCAT);
+      }
+    }
+    EMIT(NFA_NOPEN);
+    break;
+  }
+
+  case Magic('1'):
+  case Magic('2'):
+  case Magic('3'):
+  case Magic('4'):
+  case Magic('5'):
+  case Magic('6'):
+  case Magic('7'):
+  case Magic('8'):
+  case Magic('9'): {
+    int refnum = no_Magic(c) - '1';
+
+    if (!seen_endbrace(refnum + 1)) {
+      return FAIL;
+    }
+    EMIT(NFA_BACKREF1 + refnum);
+    rex.nfa_has_backref = true;
+  }
+  break;
+
+  case Magic('z'):
+    c = no_Magic(getchr());
+    switch (c) {
+    case 's':
+      EMIT(NFA_ZSTART);
+      if (!re_mult_next("\\zs")) {
+        return false;
+      }
+      break;
+    case 'e':
+      EMIT(NFA_ZEND);
+      rex.nfa_has_zend = true;
+      if (!re_mult_next("\\zs")) {
+        return false;
+      }
+      break;
+    case '1':
+    case '2':
+    case '3':
+    case '4':
+    case '5':
+    case '6':
+    case '7':
+    case '8':
+    case '9':
+      // \z1...\z9
+      if ((reg_do_extmatch & REX_USE) == 0) {
+        EMSG_RET_FAIL(_(e_z1_not_allowed));
+      }
+      EMIT(NFA_ZREF1 + (no_Magic(c) - '1'));
+      // No need to set rex.nfa_has_backref, the sub-matches don't
+      // change when \z1 .. \z9 matches or not.
+      re_has_z = REX_USE;
+      break;
+    case '(':
+      // \z(
+      if (reg_do_extmatch != REX_SET) {
+        EMSG_RET_FAIL(_(e_z_not_allowed));
+      }
+      if (nfa_reg(REG_ZPAREN) == FAIL) {
+        return FAIL;                        // cascaded error
+      }
+      re_has_z = REX_SET;
+      break;
+    default:
+      semsg(_("E867: (NFA) Unknown operator '\\z%c'"),
+            no_Magic(c));
+      return FAIL;
+    }
+    break;
+
+  case Magic('%'):
+    c = no_Magic(getchr());
+    switch (c) {
+    // () without a back reference
+    case '(':
+      if (nfa_reg(REG_NPAREN) == FAIL) {
+        return FAIL;
+      }
+      EMIT(NFA_NOPEN);
+      break;
+
+    case 'd':               // %d123 decimal
+    case 'o':               // %o123 octal
+    case 'x':               // %xab hex 2
+    case 'u':               // %uabcd hex 4
+    case 'U':               // %U1234abcd hex 8
+    {
+      int64_t nr;
+
+      switch (c) {
+      case 'd':
+        nr = getdecchrs(); break;
+      case 'o':
+        nr = getoctchrs(); break;
+      case 'x':
+        nr = gethexchrs(2); break;
+      case 'u':
+        nr = gethexchrs(4); break;
+      case 'U':
+        nr = gethexchrs(8); break;
+      default:
+        nr = -1; break;
+      }
+
+      if (nr < 0 || nr > INT_MAX) {
+        EMSG2_RET_FAIL(_("E678: Invalid character after %s%%[dxouU]"),
+                       reg_magic == MAGIC_ALL);
+      }
+      // A NUL is stored in the text as NL
+      // TODO(vim): what if a composing character follows?
+      EMIT(nr == 0 ? 0x0a : (int)nr);
+    }
+    break;
+
+    // Catch \%^ and \%$ regardless of where they appear in the
+    // pattern -- regardless of whether or not it makes sense.
+    case '^':
+      EMIT(NFA_BOF);
+      break;
+
+    case '$':
+      EMIT(NFA_EOF);
+      break;
+
+    case '#':
+      if (regparse[0] == '=' && regparse[1] >= 48
+          && regparse[1] <= 50) {
+        // misplaced \%#=1
+        semsg(_(e_atom_engine_must_be_at_start_of_pattern), regparse[1]);
+        return FAIL;
+      }
+      EMIT(NFA_CURSOR);
+      break;
+
+    case 'V':
+      EMIT(NFA_VISUAL);
+      break;
+
+    case 'C':
+      EMIT(NFA_ANY_COMPOSING);
+      break;
+
+    case '[': {
+      int n;
+
+      // \%[abc]
+      for (n = 0; (c = peekchr()) != ']'; n++) {
+        if (c == NUL) {
+          EMSG2_RET_FAIL(_(e_missing_sb),
+                         reg_magic == MAGIC_ALL);
+        }
+        // recursive call!
+        if (nfa_regatom() == FAIL) {
+          return FAIL;
+        }
+      }
+      (void)getchr();  // get the ]
+      if (n == 0) {
+        EMSG2_RET_FAIL(_(e_empty_sb), reg_magic == MAGIC_ALL);
+      }
+      EMIT(NFA_OPT_CHARS);
+      EMIT(n);
+
+      // Emit as "\%(\%[abc]\)" to be able to handle
+      // "\%[abc]*" which would cause the empty string to be
+      // matched an unlimited number of times. NFA_NOPEN is
+      // added only once at a position, while NFA_SPLIT is
+      // added multiple times.  This is more efficient than
+      // not allowing NFA_SPLIT multiple times, it is used
+      // a lot.
+      EMIT(NFA_NOPEN);
+      break;
+    }
+
+    default: {
+      int64_t n = 0;
+      const int cmp = c;
+      bool cur = false;
+      bool got_digit = false;
+
+      if (c == '<' || c == '>') {
+        c = getchr();
+      }
+      if (no_Magic(c) == '.') {
+        cur = true;
+        c = getchr();
+      }
+      while (ascii_isdigit(c)) {
+        if (cur) {
+          semsg(_(e_regexp_number_after_dot_pos_search_chr), no_Magic(c));
+          return FAIL;
+        }
+        if (n > (INT32_MAX - (c - '0')) / 10) {
+          // overflow.
+          emsg(_(e_value_too_large));
+          return FAIL;
+        }
+        n = n * 10 + (c - '0');
+        c = getchr();
+        got_digit = true;
+      }
+      if (c == 'l' || c == 'c' || c == 'v') {
+        int32_t limit = INT32_MAX;
+
+        if (!cur && !got_digit) {
+          semsg(_(e_nfa_regexp_missing_value_in_chr), no_Magic(c));
+          return FAIL;
+        }
+        if (c == 'l') {
+          if (cur) {
+            n = curwin->w_cursor.lnum;
+          }
+          // \%{n}l  \%{n}<l  \%{n}>l
+          EMIT(cmp == '<' ? NFA_LNUM_LT
+                          : cmp == '>' ? NFA_LNUM_GT : NFA_LNUM);
+          if (save_prev_at_start) {
+            at_start = true;
+          }
+        } else if (c == 'c') {
+          if (cur) {
+            n = curwin->w_cursor.col;
+            n++;
+          }
+          // \%{n}c  \%{n}<c  \%{n}>c
+          EMIT(cmp == '<' ? NFA_COL_LT
+                          : cmp == '>' ? NFA_COL_GT : NFA_COL);
+        } else {
+          if (cur) {
+            colnr_T vcol = 0;
+            getvvcol(curwin, &curwin->w_cursor, NULL, NULL, &vcol);
+            n = ++vcol;
+          }
+          // \%{n}v  \%{n}<v  \%{n}>v
+          EMIT(cmp == '<' ? NFA_VCOL_LT
+                          : cmp == '>' ? NFA_VCOL_GT : NFA_VCOL);
+          limit = INT32_MAX / MB_MAXBYTES;
+        }
+        if (n >= limit) {
+          emsg(_(e_value_too_large));
+          return FAIL;
+        }
+        EMIT((int)n);
+        break;
+      } else if (c == '\'' && n == 0) {
+        // \%'m  \%<'m  \%>'m
+        EMIT(cmp == '<' ? NFA_MARK_LT
+                        : cmp == '>' ? NFA_MARK_GT : NFA_MARK);
+        EMIT(getchr());
+        break;
+      }
+    }
+      semsg(_("E867: (NFA) Unknown operator '\\%%%c'"),
+            no_Magic(c));
+      return FAIL;
+    }
+    break;
+
+  case Magic('['):
+collection:
+    // [abc]  uses NFA_START_COLL - NFA_END_COLL
+    // [^abc] uses NFA_START_NEG_COLL - NFA_END_NEG_COLL
+    // Each character is produced as a regular state, using
+    // NFA_CONCAT to bind them together.
+    // Besides normal characters there can be:
+    // - character classes  NFA_CLASS_*
+    // - ranges, two characters followed by NFA_RANGE.
+
+    p = (uint8_t *)regparse;
+    endp = (uint8_t *)skip_anyof((char *)p);
+    if (*endp == ']') {
+      // Try to reverse engineer character classes. For example,
+      // recognize that [0-9] stands for \d and [A-Za-z_] for \h,
+      // and perform the necessary substitutions in the NFA.
+      int result = nfa_recognize_char_class((uint8_t *)regparse, endp, extra == NFA_ADD_NL);
+      if (result != FAIL) {
+        if (result >= NFA_FIRST_NL && result <= NFA_LAST_NL) {
+          EMIT(result - NFA_ADD_NL);
+          EMIT(NFA_NEWL);
+          EMIT(NFA_OR);
+        } else {
+          EMIT(result);
+        }
+        regparse = (char *)endp;
+        MB_PTR_ADV(regparse);
+        return OK;
+      }
+      // Failed to recognize a character class. Use the simple
+      // version that turns [abc] into 'a' OR 'b' OR 'c'
+      negated = false;
+      if (*regparse == '^') {                           // negated range
+        negated = true;
+        MB_PTR_ADV(regparse);
+        EMIT(NFA_START_NEG_COLL);
+      } else {
+        EMIT(NFA_START_COLL);
+      }
+      if (*regparse == '-') {
+        startc = '-';
+        EMIT(startc);
+        EMIT(NFA_CONCAT);
+        MB_PTR_ADV(regparse);
+      }
+      // Emit the OR branches for each character in the []
+      emit_range = false;
+      while ((uint8_t *)regparse < endp) {
+        int oldstartc = startc;
+        startc = -1;
+        got_coll_char = false;
+        if (*regparse == '[') {
+          // Check for [: :], [= =], [. .]
+          equiclass = collclass = 0;
+          charclass = get_char_class(&regparse);
+          if (charclass == CLASS_NONE) {
+            equiclass = get_equi_class(&regparse);
+            if (equiclass == 0) {
+              collclass = get_coll_element(&regparse);
+            }
+          }
+
+          // Character class like [:alpha:]
+          if (charclass != CLASS_NONE) {
+            switch (charclass) {
+            case CLASS_ALNUM:
+              EMIT(NFA_CLASS_ALNUM);
+              break;
+            case CLASS_ALPHA:
+              EMIT(NFA_CLASS_ALPHA);
+              break;
+            case CLASS_BLANK:
+              EMIT(NFA_CLASS_BLANK);
+              break;
+            case CLASS_CNTRL:
+              EMIT(NFA_CLASS_CNTRL);
+              break;
+            case CLASS_DIGIT:
+              EMIT(NFA_CLASS_DIGIT);
+              break;
+            case CLASS_GRAPH:
+              EMIT(NFA_CLASS_GRAPH);
+              break;
+            case CLASS_LOWER:
+              wants_nfa = true;
+              EMIT(NFA_CLASS_LOWER);
+              break;
+            case CLASS_PRINT:
+              EMIT(NFA_CLASS_PRINT);
+              break;
+            case CLASS_PUNCT:
+              EMIT(NFA_CLASS_PUNCT);
+              break;
+            case CLASS_SPACE:
+              EMIT(NFA_CLASS_SPACE);
+              break;
+            case CLASS_UPPER:
+              wants_nfa = true;
+              EMIT(NFA_CLASS_UPPER);
+              break;
+            case CLASS_XDIGIT:
+              EMIT(NFA_CLASS_XDIGIT);
+              break;
+            case CLASS_TAB:
+              EMIT(NFA_CLASS_TAB);
+              break;
+            case CLASS_RETURN:
+              EMIT(NFA_CLASS_RETURN);
+              break;
+            case CLASS_BACKSPACE:
+              EMIT(NFA_CLASS_BACKSPACE);
+              break;
+            case CLASS_ESCAPE:
+              EMIT(NFA_CLASS_ESCAPE);
+              break;
+            case CLASS_IDENT:
+              EMIT(NFA_CLASS_IDENT);
+              break;
+            case CLASS_KEYWORD:
+              EMIT(NFA_CLASS_KEYWORD);
+              break;
+            case CLASS_FNAME:
+              EMIT(NFA_CLASS_FNAME);
+              break;
+            }
+            EMIT(NFA_CONCAT);
+            continue;
+          }
+          // Try equivalence class [=a=] and the like
+          if (equiclass != 0) {
+            nfa_emit_equi_class(equiclass);
+            continue;
+          }
+          // Try collating class like [. .]
+          if (collclass != 0) {
+            startc = collclass;                  // allow [.a.]-x as a range
+            // Will emit the proper atom at the end of the
+            // while loop.
+          }
+        }
+        // Try a range like 'a-x' or '\t-z'. Also allows '-' as a
+        // start character.
+        if (*regparse == '-' && oldstartc != -1) {
+          emit_range = true;
+          startc = oldstartc;
+          MB_PTR_ADV(regparse);
+          continue;                         // reading the end of the range
+        }
+
+        // Now handle simple and escaped characters.
+        // Only "\]", "\^", "\]" and "\\" are special in Vi.  Vim
+        // accepts "\t", "\e", etc., but only when the 'l' flag in
+        // 'cpoptions' is not included.
+        if (*regparse == '\\'
+            && (uint8_t *)regparse + 1 <= endp
+            && (vim_strchr(REGEXP_INRANGE, (uint8_t)regparse[1]) != NULL
+                || (!reg_cpo_lit
+                    && vim_strchr(REGEXP_ABBR, (uint8_t)regparse[1])
+                    != NULL))) {
+          MB_PTR_ADV(regparse);
+
+          if (*regparse == 'n') {
+            startc = (reg_string || emit_range || regparse[1] == '-')
+                     ? NL : NFA_NEWL;
+          } else if (*regparse == 'd'
+                     || *regparse == 'o'
+                     || *regparse == 'x'
+                     || *regparse == 'u'
+                     || *regparse == 'U') {
+            // TODO(RE): This needs more testing
+            startc = coll_get_char();
+            got_coll_char = true;
+            MB_PTR_BACK(old_regparse, regparse);
+          } else {
+            // \r,\t,\e,\b
+            startc = backslash_trans(*regparse);
+          }
+        }
+
+        // Normal printable char
+        if (startc == -1) {
+          startc = utf_ptr2char(regparse);
+        }
+
+        // Previous char was '-', so this char is end of range.
+        if (emit_range) {
+          int endc = startc;
+          startc = oldstartc;
+          if (startc > endc) {
+            EMSG_RET_FAIL(_(e_reverse_range));
+          }
+
+          if (endc > startc + 2) {
+            // Emit a range instead of the sequence of
+            // individual characters.
+            if (startc == 0) {
+              // \x00 is translated to \x0a, start at \x01.
+              EMIT(1);
+            } else {
+              post_ptr--;                   // remove NFA_CONCAT
+            }
+            EMIT(endc);
+            EMIT(NFA_RANGE);
+            EMIT(NFA_CONCAT);
+          } else if (utf_char2len(startc) > 1
+                     || utf_char2len(endc) > 1) {
+            // Emit the characters in the range.
+            // "startc" was already emitted, so skip it.
+            for (c = startc + 1; c <= endc; c++) {
+              EMIT(c);
+              EMIT(NFA_CONCAT);
+            }
+          } else {
+            // Emit the range. "startc" was already emitted, so
+            // skip it.
+            for (c = startc + 1; c <= endc; c++) {
+              EMIT(c);
+              EMIT(NFA_CONCAT);
+            }
+          }
+          emit_range = false;
+          startc = -1;
+        } else {
+          // This char (startc) is not part of a range. Just
+          // emit it.
+          // Normally, simply emit startc. But if we get char
+          // code=0 from a collating char, then replace it with
+          // 0x0a.
+          // This is needed to completely mimic the behaviour of
+          // the backtracking engine.
+          if (startc == NFA_NEWL) {
+            // Line break can't be matched as part of the
+            // collection, add an OR below. But not for negated
+            // range.
+            if (!negated) {
+              extra = NFA_ADD_NL;
+            }
+          } else {
+            if (got_coll_char == true && startc == 0) {
+              EMIT(0x0a);
+            } else {
+              EMIT(startc);
+            }
+            EMIT(NFA_CONCAT);
+          }
+        }
+
+        MB_PTR_ADV(regparse);
+      }           // while (p < endp)
+
+      MB_PTR_BACK(old_regparse, regparse);
+      if (*regparse == '-') {               // if last, '-' is just a char
+        EMIT('-');
+        EMIT(NFA_CONCAT);
+      }
+
+      // skip the trailing ]
+      regparse = (char *)endp;
+      MB_PTR_ADV(regparse);
+
+      // Mark end of the collection.
+      if (negated == true) {
+        EMIT(NFA_END_NEG_COLL);
+      } else {
+        EMIT(NFA_END_COLL);
+      }
+
+      // \_[] also matches \n but it's not negated
+      if (extra == NFA_ADD_NL) {
+        EMIT(reg_string ? NL : NFA_NEWL);
+        EMIT(NFA_OR);
+      }
+
+      return OK;
+    }         // if exists closing ]
+
+    if (reg_strict) {
+      EMSG_RET_FAIL(_(e_missingbracket));
+    }
+    FALLTHROUGH;
+
+  default: {
+    int plen;
+
+nfa_do_multibyte:
+    // plen is length of current char with composing chars
+    if (utf_char2len(c) != (plen = utfc_ptr2len((char *)old_regparse))
+        || utf_iscomposing(c)) {
+      int i = 0;
+
+      // A base character plus composing characters, or just one
+      // or more composing characters.
+      // This requires creating a separate atom as if enclosing
+      // the characters in (), where NFA_COMPOSING is the ( and
+      // NFA_END_COMPOSING is the ). Note that right now we are
+      // building the postfix form, not the NFA itself;
+      // a composing char could be: a, b, c, NFA_COMPOSING
+      // where 'b' and 'c' are chars with codes > 256. */
+      while (true) {
+        EMIT(c);
+        if (i > 0) {
+          EMIT(NFA_CONCAT);
+        }
+        if ((i += utf_char2len(c)) >= plen) {
+          break;
+        }
+        c = utf_ptr2char((char *)old_regparse + i);
+      }
+      EMIT(NFA_COMPOSING);
+      regparse = (char *)old_regparse + plen;
+    } else {
+      c = no_Magic(c);
+      EMIT(c);
+    }
+    return OK;
+  }
+  }
+
+  return OK;
+}
+
+// Parse something followed by possible [*+=].
+//
+// A piece is an atom, possibly followed by a multi, an indication of how many
+// times the atom can be matched.  Example: "a*" matches any sequence of "a"
+// characters: "", "a", "aa", etc.
+//
+// piece   ::=      atom
+//      or  atom  multi
+static int nfa_regpiece(void)
+{
+  int i;
+  int op;
+  int ret;
+  int minval, maxval;
+  bool greedy = true;  // Braces are prefixed with '-' ?
+  parse_state_T old_state;
+  parse_state_T new_state;
+  int64_t c2;
+  int old_post_pos;
+  int my_post_start;
+  int quest;
+
+  // Save the current parse state, so that we can use it if <atom>{m,n} is
+  // next.
+  save_parse_state(&old_state);
+
+  // store current pos in the postfix form, for \{m,n} involving 0s
+  my_post_start = (int)(post_ptr - post_start);
+
+  ret = nfa_regatom();
+  if (ret == FAIL) {
+    return FAIL;            // cascaded error
+  }
+  op = peekchr();
+  if (re_multi_type(op) == NOT_MULTI) {
+    return OK;
+  }
+
+  skipchr();
+  switch (op) {
+  case Magic('*'):
+    EMIT(NFA_STAR);
+    break;
+
+  case Magic('+'):
+    // Trick: Normally, (a*)\+ would match the whole input "aaa".  The
+    // first and only submatch would be "aaa". But the backtracking
+    // engine interprets the plus as "try matching one more time", and
+    // a* matches a second time at the end of the input, the empty
+    // string.
+    // The submatch will be the empty string.
+    //
+    // In order to be consistent with the old engine, we replace
+    // <atom>+ with <atom><atom>*
+    restore_parse_state(&old_state);
+    curchr = -1;
+    if (nfa_regatom() == FAIL) {
+      return FAIL;
+    }
+    EMIT(NFA_STAR);
+    EMIT(NFA_CONCAT);
+    skipchr();                  // skip the \+
+    break;
+
+  case Magic('@'):
+    c2 = getdecchrs();
+    op = no_Magic(getchr());
+    i = 0;
+    switch (op) {
+    case '=':
+      // \@=
+      i = NFA_PREV_ATOM_NO_WIDTH;
+      break;
+    case '!':
+      // \@!
+      i = NFA_PREV_ATOM_NO_WIDTH_NEG;
+      break;
+    case '<':
+      op = no_Magic(getchr());
+      if (op == '=') {
+        // \@<=
+        i = NFA_PREV_ATOM_JUST_BEFORE;
+      } else if (op == '!') {
+        // \@<!
+        i = NFA_PREV_ATOM_JUST_BEFORE_NEG;
+      }
+      break;
+    case '>':
+      // \@>
+      i = NFA_PREV_ATOM_LIKE_PATTERN;
+      break;
+    }
+    if (i == 0) {
+      semsg(_("E869: (NFA) Unknown operator '\\@%c'"), op);
+      return FAIL;
+    }
+    EMIT(i);
+    if (i == NFA_PREV_ATOM_JUST_BEFORE
+        || i == NFA_PREV_ATOM_JUST_BEFORE_NEG) {
+      EMIT((int)c2);
+    }
+    break;
+
+  case Magic('?'):
+  case Magic('='):
+    EMIT(NFA_QUEST);
+    break;
+
+  case Magic('{'):
+    // a{2,5} will expand to 'aaa?a?a?'
+    // a{-1,3} will expand to 'aa??a??', where ?? is the nongreedy
+    // version of '?'
+    // \v(ab){2,3} will expand to '(ab)(ab)(ab)?', where all the
+    // parenthesis have the same id
+
+    greedy = true;
+    c2 = peekchr();
+    if (c2 == '-' || c2 == Magic('-')) {
+      skipchr();
+      greedy = false;
+    }
+    if (!read_limits(&minval, &maxval)) {
+      EMSG_RET_FAIL(_("E870: (NFA regexp) Error reading repetition limits"));
+    }
+
+    //  <atom>{0,inf}, <atom>{0,} and <atom>{}  are equivalent to
+    //  <atom>*
+    if (minval == 0 && maxval == MAX_LIMIT) {
+      if (greedy) {
+        // \{}, \{0,}
+        EMIT(NFA_STAR);
+      } else {
+        // \{-}, \{-0,}
+        EMIT(NFA_STAR_NONGREEDY);
+      }
+      break;
+    }
+
+    // Special case: x{0} or x{-0}
+    if (maxval == 0) {
+      // Ignore result of previous call to nfa_regatom()
+      post_ptr = post_start + my_post_start;
+      // NFA_EMPTY is 0-length and works everywhere
+      EMIT(NFA_EMPTY);
+      return OK;
+    }
+
+    // The engine is very inefficient (uses too many states) when the
+    // maximum is much larger than the minimum and when the maximum is
+    // large.  However, when maxval is MAX_LIMIT, it is okay, as this
+    // will emit NFA_STAR.
+    // Bail out if we can use the other engine, but only, when the
+    // pattern does not need the NFA engine like (e.g. [[:upper:]]\{2,\}
+    // does not work with characters > 8 bit with the BT engine)
+    if ((nfa_re_flags & RE_AUTO)
+        && (maxval > 500 || maxval > minval + 200)
+        && (maxval != MAX_LIMIT && minval < 200)
+        && !wants_nfa) {
+      return FAIL;
+    }
+
+    // Ignore previous call to nfa_regatom()
+    post_ptr = post_start + my_post_start;
+    // Save parse state after the repeated atom and the \{}
+    save_parse_state(&new_state);
+
+    quest = (greedy == true ? NFA_QUEST : NFA_QUEST_NONGREEDY);
+    for (i = 0; i < maxval; i++) {
+      // Goto beginning of the repeated atom
+      restore_parse_state(&old_state);
+      old_post_pos = (int)(post_ptr - post_start);
+      if (nfa_regatom() == FAIL) {
+        return FAIL;
+      }
+      // after "minval" times, atoms are optional
+      if (i + 1 > minval) {
+        if (maxval == MAX_LIMIT) {
+          if (greedy) {
+            EMIT(NFA_STAR);
+          } else {
+            EMIT(NFA_STAR_NONGREEDY);
+          }
+        } else {
+          EMIT(quest);
+        }
+      }
+      if (old_post_pos != my_post_start) {
+        EMIT(NFA_CONCAT);
+      }
+      if (i + 1 > minval && maxval == MAX_LIMIT) {
+        break;
+      }
+    }
+
+    // Go to just after the repeated atom and the \{}
+    restore_parse_state(&new_state);
+    curchr = -1;
+
+    break;
+
+  default:
+    break;
+  }     // end switch
+
+  if (re_multi_type(peekchr()) != NOT_MULTI) {
+    // Can't have a multi follow a multi.
+    EMSG_RET_FAIL(_("E871: (NFA regexp) Can't have a multi follow a multi"));
+  }
+
+  return OK;
+}
+
+// Parse one or more pieces, concatenated.  It matches a match for the
+// first piece, followed by a match for the second piece, etc.  Example:
+// "f[0-9]b", first matches "f", then a digit and then "b".
+//
+// concat  ::=      piece
+//      or  piece piece
+//      or  piece piece piece
+//      etc.
+static int nfa_regconcat(void)
+{
+  bool cont = true;
+  bool first = true;
+
+  while (cont) {
+    switch (peekchr()) {
+    case NUL:
+    case Magic('|'):
+    case Magic('&'):
+    case Magic(')'):
+      cont = false;
+      break;
+
+    case Magic('Z'):
+      regflags |= RF_ICOMBINE;
+      skipchr_keepstart();
+      break;
+    case Magic('c'):
+      regflags |= RF_ICASE;
+      skipchr_keepstart();
+      break;
+    case Magic('C'):
+      regflags |= RF_NOICASE;
+      skipchr_keepstart();
+      break;
+    case Magic('v'):
+      reg_magic = MAGIC_ALL;
+      skipchr_keepstart();
+      curchr = -1;
+      break;
+    case Magic('m'):
+      reg_magic = MAGIC_ON;
+      skipchr_keepstart();
+      curchr = -1;
+      break;
+    case Magic('M'):
+      reg_magic = MAGIC_OFF;
+      skipchr_keepstart();
+      curchr = -1;
+      break;
+    case Magic('V'):
+      reg_magic = MAGIC_NONE;
+      skipchr_keepstart();
+      curchr = -1;
+      break;
+
+    default:
+      if (nfa_regpiece() == FAIL) {
+        return FAIL;
+      }
+      if (first == false) {
+        EMIT(NFA_CONCAT);
+      } else {
+        first = false;
+      }
+      break;
+    }
+  }
+
+  return OK;
+}
+
+// Parse a branch, one or more concats, separated by "\&".  It matches the
+// last concat, but only if all the preceding concats also match at the same
+// position.  Examples:
+//      "foobeep\&..." matches "foo" in "foobeep".
+//      ".*Peter\&.*Bob" matches in a line containing both "Peter" and "Bob"
+//
+// branch ::=       concat
+//              or  concat \& concat
+//              or  concat \& concat \& concat
+//              etc.
+static int nfa_regbranch(void)
+{
+  int old_post_pos;
+
+  old_post_pos = (int)(post_ptr - post_start);
+
+  // First branch, possibly the only one
+  if (nfa_regconcat() == FAIL) {
+    return FAIL;
+  }
+
+  // Try next concats
+  while (peekchr() == Magic('&')) {
+    skipchr();
+    // if concat is empty do emit a node
+    if (old_post_pos == (int)(post_ptr - post_start)) {
+      EMIT(NFA_EMPTY);
+    }
+    EMIT(NFA_NOPEN);
+    EMIT(NFA_PREV_ATOM_NO_WIDTH);
+    old_post_pos = (int)(post_ptr - post_start);
+    if (nfa_regconcat() == FAIL) {
+      return FAIL;
+    }
+    // if concat is empty do emit a node
+    if (old_post_pos == (int)(post_ptr - post_start)) {
+      EMIT(NFA_EMPTY);
+    }
+    EMIT(NFA_CONCAT);
+  }
+
+  // if a branch is empty, emit one node for it
+  if (old_post_pos == (int)(post_ptr - post_start)) {
+    EMIT(NFA_EMPTY);
+  }
+
+  return OK;
+}
+
+///  Parse a pattern, one or more branches, separated by "\|".  It matches
+///  anything that matches one of the branches.  Example: "foo\|beep" matches
+///  "foo" and matches "beep".  If more than one branch matches, the first one
+///  is used.
+///
+///  pattern ::=     branch
+///      or  branch \| branch
+///      or  branch \| branch \| branch
+///      etc.
+///
+/// @param paren  REG_NOPAREN, REG_PAREN, REG_NPAREN or REG_ZPAREN
+static int nfa_reg(int paren)
+{
+  int parno = 0;
+
+  if (paren == REG_PAREN) {
+    if (regnpar >= NSUBEXP) {   // Too many `('
+      EMSG_RET_FAIL(_("E872: (NFA regexp) Too many '('"));
+    }
+    parno = regnpar++;
+  } else if (paren == REG_ZPAREN) {
+    // Make a ZOPEN node.
+    if (regnzpar >= NSUBEXP) {
+      EMSG_RET_FAIL(_("E879: (NFA regexp) Too many \\z("));
+    }
+    parno = regnzpar++;
+  }
+
+  if (nfa_regbranch() == FAIL) {
+    return FAIL;            // cascaded error
+  }
+  while (peekchr() == Magic('|')) {
+    skipchr();
+    if (nfa_regbranch() == FAIL) {
+      return FAIL;          // cascaded error
+    }
+    EMIT(NFA_OR);
+  }
+
+  // Check for proper termination.
+  if (paren != REG_NOPAREN && getchr() != Magic(')')) {
+    if (paren == REG_NPAREN) {
+      EMSG2_RET_FAIL(_(e_unmatchedpp), reg_magic == MAGIC_ALL);
+    } else {
+      EMSG2_RET_FAIL(_(e_unmatchedp), reg_magic == MAGIC_ALL);
+    }
+  } else if (paren == REG_NOPAREN && peekchr() != NUL) {
+    if (peekchr() == Magic(')')) {
+      EMSG2_RET_FAIL(_(e_unmatchedpar), reg_magic == MAGIC_ALL);
+    } else {
+      EMSG_RET_FAIL(_("E873: (NFA regexp) proper termination error"));
+    }
+  }
+  // Here we set the flag allowing back references to this set of
+  // parentheses.
+  if (paren == REG_PAREN) {
+    had_endbrace[parno] = true;  // have seen the close paren
+    EMIT(NFA_MOPEN + parno);
+  } else if (paren == REG_ZPAREN) {
+    EMIT(NFA_ZOPEN + parno);
+  }
+
+  return OK;
+}
+
+#ifdef REGEXP_DEBUG
+static uint8_t code[50];
+
+static void nfa_set_code(int c)
+{
+  int addnl = false;
+
+  if (c >= NFA_FIRST_NL && c <= NFA_LAST_NL) {
+    addnl = true;
+    c -= NFA_ADD_NL;
+  }
+
+  STRCPY(code, "");
+  switch (c) {
+  case NFA_MATCH:
+    STRCPY(code, "NFA_MATCH "); break;
+  case NFA_SPLIT:
+    STRCPY(code, "NFA_SPLIT "); break;
+  case NFA_CONCAT:
+    STRCPY(code, "NFA_CONCAT "); break;
+  case NFA_NEWL:
+    STRCPY(code, "NFA_NEWL "); break;
+  case NFA_ZSTART:
+    STRCPY(code, "NFA_ZSTART"); break;
+  case NFA_ZEND:
+    STRCPY(code, "NFA_ZEND"); break;
+
+  case NFA_BACKREF1:
+    STRCPY(code, "NFA_BACKREF1"); break;
+  case NFA_BACKREF2:
+    STRCPY(code, "NFA_BACKREF2"); break;
+  case NFA_BACKREF3:
+    STRCPY(code, "NFA_BACKREF3"); break;
+  case NFA_BACKREF4:
+    STRCPY(code, "NFA_BACKREF4"); break;
+  case NFA_BACKREF5:
+    STRCPY(code, "NFA_BACKREF5"); break;
+  case NFA_BACKREF6:
+    STRCPY(code, "NFA_BACKREF6"); break;
+  case NFA_BACKREF7:
+    STRCPY(code, "NFA_BACKREF7"); break;
+  case NFA_BACKREF8:
+    STRCPY(code, "NFA_BACKREF8"); break;
+  case NFA_BACKREF9:
+    STRCPY(code, "NFA_BACKREF9"); break;
+  case NFA_ZREF1:
+    STRCPY(code, "NFA_ZREF1"); break;
+  case NFA_ZREF2:
+    STRCPY(code, "NFA_ZREF2"); break;
+  case NFA_ZREF3:
+    STRCPY(code, "NFA_ZREF3"); break;
+  case NFA_ZREF4:
+    STRCPY(code, "NFA_ZREF4"); break;
+  case NFA_ZREF5:
+    STRCPY(code, "NFA_ZREF5"); break;
+  case NFA_ZREF6:
+    STRCPY(code, "NFA_ZREF6"); break;
+  case NFA_ZREF7:
+    STRCPY(code, "NFA_ZREF7"); break;
+  case NFA_ZREF8:
+    STRCPY(code, "NFA_ZREF8"); break;
+  case NFA_ZREF9:
+    STRCPY(code, "NFA_ZREF9"); break;
+  case NFA_SKIP:
+    STRCPY(code, "NFA_SKIP"); break;
+
+  case NFA_PREV_ATOM_NO_WIDTH:
+    STRCPY(code, "NFA_PREV_ATOM_NO_WIDTH"); break;
+  case NFA_PREV_ATOM_NO_WIDTH_NEG:
+    STRCPY(code, "NFA_PREV_ATOM_NO_WIDTH_NEG"); break;
+  case NFA_PREV_ATOM_JUST_BEFORE:
+    STRCPY(code, "NFA_PREV_ATOM_JUST_BEFORE"); break;
+  case NFA_PREV_ATOM_JUST_BEFORE_NEG:
+    STRCPY(code, "NFA_PREV_ATOM_JUST_BEFORE_NEG"); break;
+  case NFA_PREV_ATOM_LIKE_PATTERN:
+    STRCPY(code, "NFA_PREV_ATOM_LIKE_PATTERN"); break;
+
+  case NFA_NOPEN:
+    STRCPY(code, "NFA_NOPEN"); break;
+  case NFA_NCLOSE:
+    STRCPY(code, "NFA_NCLOSE"); break;
+  case NFA_START_INVISIBLE:
+    STRCPY(code, "NFA_START_INVISIBLE"); break;
+  case NFA_START_INVISIBLE_FIRST:
+    STRCPY(code, "NFA_START_INVISIBLE_FIRST"); break;
+  case NFA_START_INVISIBLE_NEG:
+    STRCPY(code, "NFA_START_INVISIBLE_NEG"); break;
+  case NFA_START_INVISIBLE_NEG_FIRST:
+    STRCPY(code, "NFA_START_INVISIBLE_NEG_FIRST"); break;
+  case NFA_START_INVISIBLE_BEFORE:
+    STRCPY(code, "NFA_START_INVISIBLE_BEFORE"); break;
+  case NFA_START_INVISIBLE_BEFORE_FIRST:
+    STRCPY(code, "NFA_START_INVISIBLE_BEFORE_FIRST"); break;
+  case NFA_START_INVISIBLE_BEFORE_NEG:
+    STRCPY(code, "NFA_START_INVISIBLE_BEFORE_NEG"); break;
+  case NFA_START_INVISIBLE_BEFORE_NEG_FIRST:
+    STRCPY(code, "NFA_START_INVISIBLE_BEFORE_NEG_FIRST"); break;
+  case NFA_START_PATTERN:
+    STRCPY(code, "NFA_START_PATTERN"); break;
+  case NFA_END_INVISIBLE:
+    STRCPY(code, "NFA_END_INVISIBLE"); break;
+  case NFA_END_INVISIBLE_NEG:
+    STRCPY(code, "NFA_END_INVISIBLE_NEG"); break;
+  case NFA_END_PATTERN:
+    STRCPY(code, "NFA_END_PATTERN"); break;
+
+  case NFA_COMPOSING:
+    STRCPY(code, "NFA_COMPOSING"); break;
+  case NFA_END_COMPOSING:
+    STRCPY(code, "NFA_END_COMPOSING"); break;
+  case NFA_OPT_CHARS:
+    STRCPY(code, "NFA_OPT_CHARS"); break;
+
+  case NFA_MOPEN:
+  case NFA_MOPEN1:
+  case NFA_MOPEN2:
+  case NFA_MOPEN3:
+  case NFA_MOPEN4:
+  case NFA_MOPEN5:
+  case NFA_MOPEN6:
+  case NFA_MOPEN7:
+  case NFA_MOPEN8:
+  case NFA_MOPEN9:
+    STRCPY(code, "NFA_MOPEN(x)");
+    code[10] = c - NFA_MOPEN + '0';
+    break;
+  case NFA_MCLOSE:
+  case NFA_MCLOSE1:
+  case NFA_MCLOSE2:
+  case NFA_MCLOSE3:
+  case NFA_MCLOSE4:
+  case NFA_MCLOSE5:
+  case NFA_MCLOSE6:
+  case NFA_MCLOSE7:
+  case NFA_MCLOSE8:
+  case NFA_MCLOSE9:
+    STRCPY(code, "NFA_MCLOSE(x)");
+    code[11] = c - NFA_MCLOSE + '0';
+    break;
+  case NFA_ZOPEN:
+  case NFA_ZOPEN1:
+  case NFA_ZOPEN2:
+  case NFA_ZOPEN3:
+  case NFA_ZOPEN4:
+  case NFA_ZOPEN5:
+  case NFA_ZOPEN6:
+  case NFA_ZOPEN7:
+  case NFA_ZOPEN8:
+  case NFA_ZOPEN9:
+    STRCPY(code, "NFA_ZOPEN(x)");
+    code[10] = c - NFA_ZOPEN + '0';
+    break;
+  case NFA_ZCLOSE:
+  case NFA_ZCLOSE1:
+  case NFA_ZCLOSE2:
+  case NFA_ZCLOSE3:
+  case NFA_ZCLOSE4:
+  case NFA_ZCLOSE5:
+  case NFA_ZCLOSE6:
+  case NFA_ZCLOSE7:
+  case NFA_ZCLOSE8:
+  case NFA_ZCLOSE9:
+    STRCPY(code, "NFA_ZCLOSE(x)");
+    code[11] = c - NFA_ZCLOSE + '0';
+    break;
+  case NFA_EOL:
+    STRCPY(code, "NFA_EOL "); break;
+  case NFA_BOL:
+    STRCPY(code, "NFA_BOL "); break;
+  case NFA_EOW:
+    STRCPY(code, "NFA_EOW "); break;
+  case NFA_BOW:
+    STRCPY(code, "NFA_BOW "); break;
+  case NFA_EOF:
+    STRCPY(code, "NFA_EOF "); break;
+  case NFA_BOF:
+    STRCPY(code, "NFA_BOF "); break;
+  case NFA_LNUM:
+    STRCPY(code, "NFA_LNUM "); break;
+  case NFA_LNUM_GT:
+    STRCPY(code, "NFA_LNUM_GT "); break;
+  case NFA_LNUM_LT:
+    STRCPY(code, "NFA_LNUM_LT "); break;
+  case NFA_COL:
+    STRCPY(code, "NFA_COL "); break;
+  case NFA_COL_GT:
+    STRCPY(code, "NFA_COL_GT "); break;
+  case NFA_COL_LT:
+    STRCPY(code, "NFA_COL_LT "); break;
+  case NFA_VCOL:
+    STRCPY(code, "NFA_VCOL "); break;
+  case NFA_VCOL_GT:
+    STRCPY(code, "NFA_VCOL_GT "); break;
+  case NFA_VCOL_LT:
+    STRCPY(code, "NFA_VCOL_LT "); break;
+  case NFA_MARK:
+    STRCPY(code, "NFA_MARK "); break;
+  case NFA_MARK_GT:
+    STRCPY(code, "NFA_MARK_GT "); break;
+  case NFA_MARK_LT:
+    STRCPY(code, "NFA_MARK_LT "); break;
+  case NFA_CURSOR:
+    STRCPY(code, "NFA_CURSOR "); break;
+  case NFA_VISUAL:
+    STRCPY(code, "NFA_VISUAL "); break;
+  case NFA_ANY_COMPOSING:
+    STRCPY(code, "NFA_ANY_COMPOSING "); break;
+
+  case NFA_STAR:
+    STRCPY(code, "NFA_STAR "); break;
+  case NFA_STAR_NONGREEDY:
+    STRCPY(code, "NFA_STAR_NONGREEDY "); break;
+  case NFA_QUEST:
+    STRCPY(code, "NFA_QUEST"); break;
+  case NFA_QUEST_NONGREEDY:
+    STRCPY(code, "NFA_QUEST_NON_GREEDY"); break;
+  case NFA_EMPTY:
+    STRCPY(code, "NFA_EMPTY"); break;
+  case NFA_OR:
+    STRCPY(code, "NFA_OR"); break;
+
+  case NFA_START_COLL:
+    STRCPY(code, "NFA_START_COLL"); break;
+  case NFA_END_COLL:
+    STRCPY(code, "NFA_END_COLL"); break;
+  case NFA_START_NEG_COLL:
+    STRCPY(code, "NFA_START_NEG_COLL"); break;
+  case NFA_END_NEG_COLL:
+    STRCPY(code, "NFA_END_NEG_COLL"); break;
+  case NFA_RANGE:
+    STRCPY(code, "NFA_RANGE"); break;
+  case NFA_RANGE_MIN:
+    STRCPY(code, "NFA_RANGE_MIN"); break;
+  case NFA_RANGE_MAX:
+    STRCPY(code, "NFA_RANGE_MAX"); break;
+
+  case NFA_CLASS_ALNUM:
+    STRCPY(code, "NFA_CLASS_ALNUM"); break;
+  case NFA_CLASS_ALPHA:
+    STRCPY(code, "NFA_CLASS_ALPHA"); break;
+  case NFA_CLASS_BLANK:
+    STRCPY(code, "NFA_CLASS_BLANK"); break;
+  case NFA_CLASS_CNTRL:
+    STRCPY(code, "NFA_CLASS_CNTRL"); break;
+  case NFA_CLASS_DIGIT:
+    STRCPY(code, "NFA_CLASS_DIGIT"); break;
+  case NFA_CLASS_GRAPH:
+    STRCPY(code, "NFA_CLASS_GRAPH"); break;
+  case NFA_CLASS_LOWER:
+    STRCPY(code, "NFA_CLASS_LOWER"); break;
+  case NFA_CLASS_PRINT:
+    STRCPY(code, "NFA_CLASS_PRINT"); break;
+  case NFA_CLASS_PUNCT:
+    STRCPY(code, "NFA_CLASS_PUNCT"); break;
+  case NFA_CLASS_SPACE:
+    STRCPY(code, "NFA_CLASS_SPACE"); break;
+  case NFA_CLASS_UPPER:
+    STRCPY(code, "NFA_CLASS_UPPER"); break;
+  case NFA_CLASS_XDIGIT:
+    STRCPY(code, "NFA_CLASS_XDIGIT"); break;
+  case NFA_CLASS_TAB:
+    STRCPY(code, "NFA_CLASS_TAB"); break;
+  case NFA_CLASS_RETURN:
+    STRCPY(code, "NFA_CLASS_RETURN"); break;
+  case NFA_CLASS_BACKSPACE:
+    STRCPY(code, "NFA_CLASS_BACKSPACE"); break;
+  case NFA_CLASS_ESCAPE:
+    STRCPY(code, "NFA_CLASS_ESCAPE"); break;
+  case NFA_CLASS_IDENT:
+    STRCPY(code, "NFA_CLASS_IDENT"); break;
+  case NFA_CLASS_KEYWORD:
+    STRCPY(code, "NFA_CLASS_KEYWORD"); break;
+  case NFA_CLASS_FNAME:
+    STRCPY(code, "NFA_CLASS_FNAME"); break;
+
+  case NFA_ANY:
+    STRCPY(code, "NFA_ANY"); break;
+  case NFA_IDENT:
+    STRCPY(code, "NFA_IDENT"); break;
+  case NFA_SIDENT:
+    STRCPY(code, "NFA_SIDENT"); break;
+  case NFA_KWORD:
+    STRCPY(code, "NFA_KWORD"); break;
+  case NFA_SKWORD:
+    STRCPY(code, "NFA_SKWORD"); break;
+  case NFA_FNAME:
+    STRCPY(code, "NFA_FNAME"); break;
+  case NFA_SFNAME:
+    STRCPY(code, "NFA_SFNAME"); break;
+  case NFA_PRINT:
+    STRCPY(code, "NFA_PRINT"); break;
+  case NFA_SPRINT:
+    STRCPY(code, "NFA_SPRINT"); break;
+  case NFA_WHITE:
+    STRCPY(code, "NFA_WHITE"); break;
+  case NFA_NWHITE:
+    STRCPY(code, "NFA_NWHITE"); break;
+  case NFA_DIGIT:
+    STRCPY(code, "NFA_DIGIT"); break;
+  case NFA_NDIGIT:
+    STRCPY(code, "NFA_NDIGIT"); break;
+  case NFA_HEX:
+    STRCPY(code, "NFA_HEX"); break;
+  case NFA_NHEX:
+    STRCPY(code, "NFA_NHEX"); break;
+  case NFA_OCTAL:
+    STRCPY(code, "NFA_OCTAL"); break;
+  case NFA_NOCTAL:
+    STRCPY(code, "NFA_NOCTAL"); break;
+  case NFA_WORD:
+    STRCPY(code, "NFA_WORD"); break;
+  case NFA_NWORD:
+    STRCPY(code, "NFA_NWORD"); break;
+  case NFA_HEAD:
+    STRCPY(code, "NFA_HEAD"); break;
+  case NFA_NHEAD:
+    STRCPY(code, "NFA_NHEAD"); break;
+  case NFA_ALPHA:
+    STRCPY(code, "NFA_ALPHA"); break;
+  case NFA_NALPHA:
+    STRCPY(code, "NFA_NALPHA"); break;
+  case NFA_LOWER:
+    STRCPY(code, "NFA_LOWER"); break;
+  case NFA_NLOWER:
+    STRCPY(code, "NFA_NLOWER"); break;
+  case NFA_UPPER:
+    STRCPY(code, "NFA_UPPER"); break;
+  case NFA_NUPPER:
+    STRCPY(code, "NFA_NUPPER"); break;
+  case NFA_LOWER_IC:
+    STRCPY(code, "NFA_LOWER_IC"); break;
+  case NFA_NLOWER_IC:
+    STRCPY(code, "NFA_NLOWER_IC"); break;
+  case NFA_UPPER_IC:
+    STRCPY(code, "NFA_UPPER_IC"); break;
+  case NFA_NUPPER_IC:
+    STRCPY(code, "NFA_NUPPER_IC"); break;
+
+  default:
+    STRCPY(code, "CHAR(x)");
+    code[5] = c;
+  }
+
+  if (addnl == true) {
+    STRCAT(code, " + NEWLINE ");
+  }
+}
+
+static FILE *log_fd;
+static const uint8_t e_log_open_failed[] =
+  N_("Could not open temporary log file for writing, displaying on stderr... ");
+
+// Print the postfix notation of the current regexp.
+static void nfa_postfix_dump(uint8_t *expr, int retval)
+{
+  int *p;
+  FILE *f;
+
+  f = fopen(NFA_REGEXP_DUMP_LOG, "a");
+  if (f == NULL) {
+    return;
+  }
+
+  fprintf(f, "\n-------------------------\n");
+  if (retval == FAIL) {
+    fprintf(f, ">>> NFA engine failed... \n");
+  } else if (retval == OK) {
+    fprintf(f, ">>> NFA engine succeeded !\n");
+  }
+  fprintf(f, "Regexp: \"%s\"\nPostfix notation (char): \"", expr);
+  for (p = post_start; *p && p < post_ptr; p++) {
+    nfa_set_code(*p);
+    fprintf(f, "%s, ", code);
+  }
+  fprintf(f, "\"\nPostfix notation (int): ");
+  for (p = post_start; *p && p < post_ptr; p++) {
+    fprintf(f, "%d ", *p);
+  }
+  fprintf(f, "\n\n");
+  fclose(f);
+}
+
+// Print the NFA starting with a root node "state".
+static void nfa_print_state(FILE *debugf, nfa_state_T *state)
+{
+  garray_T indent;
+
+  ga_init(&indent, 1, 64);
+  ga_append(&indent, '\0');
+  nfa_print_state2(debugf, state, &indent);
+  ga_clear(&indent);
+}
+
+static void nfa_print_state2(FILE *debugf, nfa_state_T *state, garray_T *indent)
+{
+  uint8_t *p;
+
+  if (state == NULL) {
+    return;
+  }
+
+  fprintf(debugf, "(%2d)", abs(state->id));
+
+  // Output indent
+  p = (uint8_t *)indent->ga_data;
+  if (indent->ga_len >= 3) {
+    int last = indent->ga_len - 3;
+    uint8_t save[2];
+
+    strncpy(save, &p[last], 2);  // NOLINT(runtime/printf)
+    memcpy(&p[last], "+-", 2);
+    fprintf(debugf, " %s", p);
+    strncpy(&p[last], save, 2);  // NOLINT(runtime/printf)
+  } else {
+    fprintf(debugf, " %s", p);
+  }
+
+  nfa_set_code(state->c);
+  fprintf(debugf, "%s (%d) (id=%d) val=%d\n",
+          code,
+          state->c,
+          abs(state->id),
+          state->val);
+  if (state->id < 0) {
+    return;
+  }
+
+  state->id = abs(state->id) * -1;
+
+  // grow indent for state->out
+  indent->ga_len -= 1;
+  if (state->out1) {
+    ga_concat(indent, (uint8_t *)"| ");
+  } else {
+    ga_concat(indent, (uint8_t *)"  ");
+  }
+  ga_append(indent, NUL);
+
+  nfa_print_state2(debugf, state->out, indent);
+
+  // replace last part of indent for state->out1
+  indent->ga_len -= 3;
+  ga_concat(indent, (uint8_t *)"  ");
+  ga_append(indent, NUL);
+
+  nfa_print_state2(debugf, state->out1, indent);
+
+  // shrink indent
+  indent->ga_len -= 3;
+  ga_append(indent, NUL);
+}
+
+// Print the NFA state machine.
+static void nfa_dump(nfa_regprog_T *prog)
+{
+  FILE *debugf = fopen(NFA_REGEXP_DUMP_LOG, "a");
+
+  if (debugf == NULL) {
+    return;
+  }
+
+  nfa_print_state(debugf, prog->start);
+
+  if (prog->reganch) {
+    fprintf(debugf, "reganch: %d\n", prog->reganch);
+  }
+  if (prog->regstart != NUL) {
+    fprintf(debugf, "regstart: %c (decimal: %d)\n",
+            prog->regstart, prog->regstart);
+  }
+  if (prog->match_text != NULL) {
+    fprintf(debugf, "match_text: \"%s\"\n", prog->match_text);
+  }
+
+  fclose(debugf);
+}
+#endif  // REGEXP_DEBUG
+
+// Parse r.e. @expr and convert it into postfix form.
+// Return the postfix string on success, NULL otherwise.
+static int *re2post(void)
+{
+  if (nfa_reg(REG_NOPAREN) == FAIL) {
+    return NULL;
+  }
+  EMIT(NFA_MOPEN);
+  return post_start;
+}
+
+// NB. Some of the code below is inspired by Russ's.
+
+// Represents an NFA state plus zero or one or two arrows exiting.
+// if c == MATCH, no arrows out; matching state.
+// If c == SPLIT, unlabeled arrows to out and out1 (if != NULL).
+// If c < 256, labeled arrow with character c to out.
+
+static nfa_state_T *state_ptr;  // points to nfa_prog->state
+
+// Allocate and initialize nfa_state_T.
+static nfa_state_T *alloc_state(int c, nfa_state_T *out, nfa_state_T *out1)
+{
+  nfa_state_T *s;
+
+  if (istate >= nstate) {
+    return NULL;
+  }
+
+  s = &state_ptr[istate++];
+
+  s->c = c;
+  s->out = out;
+  s->out1 = out1;
+  s->val = 0;
+
+  s->id = istate;
+  s->lastlist[0] = 0;
+  s->lastlist[1] = 0;
+
+  return s;
+}
+
+// A partially built NFA without the matching state filled in.
+// Frag_T.start points at the start state.
+// Frag_T.out is a list of places that need to be set to the
+// next state for this fragment.
+
+// Initialize a Frag_T struct and return it.
+static Frag_T frag(nfa_state_T *start, Ptrlist *out)
+{
+  Frag_T n;
+
+  n.start = start;
+  n.out = out;
+  return n;
+}
+
+// Create singleton list containing just outp.
+static Ptrlist *list1(nfa_state_T **outp)
+{
+  Ptrlist *l;
+
+  l = (Ptrlist *)outp;
+  l->next = NULL;
+  return l;
+}
+
+// Patch the list of states at out to point to start.
+static void patch(Ptrlist *l, nfa_state_T *s)
+{
+  Ptrlist *next;
+
+  for (; l; l = next) {
+    next = l->next;
+    l->s = s;
+  }
+}
+
+// Join the two lists l1 and l2, returning the combination.
+static Ptrlist *append(Ptrlist *l1, Ptrlist *l2)
+{
+  Ptrlist *oldl1;
+
+  oldl1 = l1;
+  while (l1->next) {
+    l1 = l1->next;
+  }
+  l1->next = l2;
+  return oldl1;
+}
+
+// Stack used for transforming postfix form into NFA.
+static Frag_T empty;
+
+static void st_error(int *postfix, int *end, int *p)
+{
+#ifdef NFA_REGEXP_ERROR_LOG
+  FILE *df;
+  int *p2;
+
+  df = fopen(NFA_REGEXP_ERROR_LOG, "a");
+  if (df) {
+    fprintf(df, "Error popping the stack!\n");
+# ifdef REGEXP_DEBUG
+    fprintf(df, "Current regexp is \"%s\"\n", nfa_regengine.expr);
+# endif
+    fprintf(df, "Postfix form is: ");
+# ifdef REGEXP_DEBUG
+    for (p2 = postfix; p2 < end; p2++) {
+      nfa_set_code(*p2);
+      fprintf(df, "%s, ", code);
+    }
+    nfa_set_code(*p);
+    fprintf(df, "\nCurrent position is: ");
+    for (p2 = postfix; p2 <= p; p2++) {
+      nfa_set_code(*p2);
+      fprintf(df, "%s, ", code);
+    }
+# else
+    for (p2 = postfix; p2 < end; p2++) {
+      fprintf(df, "%d, ", *p2);
+    }
+    fprintf(df, "\nCurrent position is: ");
+    for (p2 = postfix; p2 <= p; p2++) {
+      fprintf(df, "%d, ", *p2);
+    }
+# endif
+    fprintf(df, "\n--------------------------\n");
+    fclose(df);
+  }
+#endif
+  emsg(_("E874: (NFA) Could not pop the stack!"));
+}
+
+// Push an item onto the stack.
+static void st_push(Frag_T s, Frag_T **p, Frag_T *stack_end)
+{
+  Frag_T *stackp = *p;
+
+  if (stackp >= stack_end) {
+    return;
+  }
+  *stackp = s;
+  *p = *p + 1;
+}
+
+// Pop an item from the stack.
+static Frag_T st_pop(Frag_T **p, Frag_T *stack)
+{
+  Frag_T *stackp;
+
+  *p = *p - 1;
+  stackp = *p;
+  if (stackp < stack) {
+    return empty;
+  }
+  return **p;
+}
+
+// Estimate the maximum byte length of anything matching "state".
+// When unknown or unlimited return -1.
+static int nfa_max_width(nfa_state_T *startstate, int depth)
+{
+  int l, r;
+  nfa_state_T *state = startstate;
+  int len = 0;
+
+  // detect looping in a NFA_SPLIT
+  if (depth > 4) {
+    return -1;
+  }
+
+  while (state != NULL) {
+    switch (state->c) {
+    case NFA_END_INVISIBLE:
+    case NFA_END_INVISIBLE_NEG:
+      // the end, return what we have
+      return len;
+
+    case NFA_SPLIT:
+      // two alternatives, use the maximum
+      l = nfa_max_width(state->out, depth + 1);
+      r = nfa_max_width(state->out1, depth + 1);
+      if (l < 0 || r < 0) {
+        return -1;
+      }
+      return len + (l > r ? l : r);
+
+    case NFA_ANY:
+    case NFA_START_COLL:
+    case NFA_START_NEG_COLL:
+      // Matches some character, including composing chars.
+      len += MB_MAXBYTES;
+      if (state->c != NFA_ANY) {
+        // Skip over the characters.
+        state = state->out1->out;
+        continue;
+      }
+      break;
+
+    case NFA_DIGIT:
+    case NFA_WHITE:
+    case NFA_HEX:
+    case NFA_OCTAL:
+      // ascii
+      len++;
+      break;
+
+    case NFA_IDENT:
+    case NFA_SIDENT:
+    case NFA_KWORD:
+    case NFA_SKWORD:
+    case NFA_FNAME:
+    case NFA_SFNAME:
+    case NFA_PRINT:
+    case NFA_SPRINT:
+    case NFA_NWHITE:
+    case NFA_NDIGIT:
+    case NFA_NHEX:
+    case NFA_NOCTAL:
+    case NFA_WORD:
+    case NFA_NWORD:
+    case NFA_HEAD:
+    case NFA_NHEAD:
+    case NFA_ALPHA:
+    case NFA_NALPHA:
+    case NFA_LOWER:
+    case NFA_NLOWER:
+    case NFA_UPPER:
+    case NFA_NUPPER:
+    case NFA_LOWER_IC:
+    case NFA_NLOWER_IC:
+    case NFA_UPPER_IC:
+    case NFA_NUPPER_IC:
+    case NFA_ANY_COMPOSING:
+      // possibly non-ascii
+      len += 3;
+      break;
+
+    case NFA_START_INVISIBLE:
+    case NFA_START_INVISIBLE_NEG:
+    case NFA_START_INVISIBLE_BEFORE:
+    case NFA_START_INVISIBLE_BEFORE_NEG:
+      // zero-width, out1 points to the END state
+      state = state->out1->out;
+      continue;
+
+    case NFA_BACKREF1:
+    case NFA_BACKREF2:
+    case NFA_BACKREF3:
+    case NFA_BACKREF4:
+    case NFA_BACKREF5:
+    case NFA_BACKREF6:
+    case NFA_BACKREF7:
+    case NFA_BACKREF8:
+    case NFA_BACKREF9:
+    case NFA_ZREF1:
+    case NFA_ZREF2:
+    case NFA_ZREF3:
+    case NFA_ZREF4:
+    case NFA_ZREF5:
+    case NFA_ZREF6:
+    case NFA_ZREF7:
+    case NFA_ZREF8:
+    case NFA_ZREF9:
+    case NFA_NEWL:
+    case NFA_SKIP:
+      // unknown width
+      return -1;
+
+    case NFA_BOL:
+    case NFA_EOL:
+    case NFA_BOF:
+    case NFA_EOF:
+    case NFA_BOW:
+    case NFA_EOW:
+    case NFA_MOPEN:
+    case NFA_MOPEN1:
+    case NFA_MOPEN2:
+    case NFA_MOPEN3:
+    case NFA_MOPEN4:
+    case NFA_MOPEN5:
+    case NFA_MOPEN6:
+    case NFA_MOPEN7:
+    case NFA_MOPEN8:
+    case NFA_MOPEN9:
+    case NFA_ZOPEN:
+    case NFA_ZOPEN1:
+    case NFA_ZOPEN2:
+    case NFA_ZOPEN3:
+    case NFA_ZOPEN4:
+    case NFA_ZOPEN5:
+    case NFA_ZOPEN6:
+    case NFA_ZOPEN7:
+    case NFA_ZOPEN8:
+    case NFA_ZOPEN9:
+    case NFA_ZCLOSE:
+    case NFA_ZCLOSE1:
+    case NFA_ZCLOSE2:
+    case NFA_ZCLOSE3:
+    case NFA_ZCLOSE4:
+    case NFA_ZCLOSE5:
+    case NFA_ZCLOSE6:
+    case NFA_ZCLOSE7:
+    case NFA_ZCLOSE8:
+    case NFA_ZCLOSE9:
+    case NFA_MCLOSE:
+    case NFA_MCLOSE1:
+    case NFA_MCLOSE2:
+    case NFA_MCLOSE3:
+    case NFA_MCLOSE4:
+    case NFA_MCLOSE5:
+    case NFA_MCLOSE6:
+    case NFA_MCLOSE7:
+    case NFA_MCLOSE8:
+    case NFA_MCLOSE9:
+    case NFA_NOPEN:
+    case NFA_NCLOSE:
+
+    case NFA_LNUM_GT:
+    case NFA_LNUM_LT:
+    case NFA_COL_GT:
+    case NFA_COL_LT:
+    case NFA_VCOL_GT:
+    case NFA_VCOL_LT:
+    case NFA_MARK_GT:
+    case NFA_MARK_LT:
+    case NFA_VISUAL:
+    case NFA_LNUM:
+    case NFA_CURSOR:
+    case NFA_COL:
+    case NFA_VCOL:
+    case NFA_MARK:
+
+    case NFA_ZSTART:
+    case NFA_ZEND:
+    case NFA_OPT_CHARS:
+    case NFA_EMPTY:
+    case NFA_START_PATTERN:
+    case NFA_END_PATTERN:
+    case NFA_COMPOSING:
+    case NFA_END_COMPOSING:
+      // zero-width
+      break;
+
+    default:
+      if (state->c < 0) {
+        // don't know what this is
+        return -1;
+      }
+      // normal character
+      len += utf_char2len(state->c);
+      break;
+    }
+
+    // normal way to continue
+    state = state->out;
+  }
+
+  // unrecognized, "cannot happen"
+  return -1;
+}
+
+// Convert a postfix form into its equivalent NFA.
+// Return the NFA start state on success, NULL otherwise.
+static nfa_state_T *post2nfa(int *postfix, int *end, int nfa_calc_size)
+{
+  int *p;
+  int mopen;
+  int mclose;
+  Frag_T *stack = NULL;
+  Frag_T *stackp = NULL;
+  Frag_T *stack_end = NULL;
+  Frag_T e1;
+  Frag_T e2;
+  Frag_T e;
+  nfa_state_T *s;
+  nfa_state_T *s1;
+  nfa_state_T *matchstate;
+  nfa_state_T *ret = NULL;
+
+  if (postfix == NULL) {
+    return NULL;
+  }
+
+#define PUSH(s)     st_push((s), &stackp, stack_end)
+#define POP()       st_pop(&stackp, stack); \
+  if (stackp < stack) { \
+    st_error(postfix, end, p); \
+    xfree(stack); \
+    return NULL; \
+  }
+
+  if (nfa_calc_size == false) {
+    // Allocate space for the stack. Max states on the stack: "nstate".
+    stack = xmalloc((size_t)(nstate + 1) * sizeof(Frag_T));
+    stackp = stack;
+    stack_end = stack + (nstate + 1);
+  }
+
+  for (p = postfix; p < end; p++) {
+    switch (*p) {
+    case NFA_CONCAT:
+      // Concatenation.
+      // Pay attention: this operator does not exist in the r.e. itself
+      // (it is implicit, really).  It is added when r.e. is translated
+      // to postfix form in re2post().
+      if (nfa_calc_size == true) {
+        // nstate += 0;
+        break;
+      }
+      e2 = POP();
+      e1 = POP();
+      patch(e1.out, e2.start);
+      PUSH(frag(e1.start, e2.out));
+      break;
+
+    case NFA_OR:
+      // Alternation
+      if (nfa_calc_size == true) {
+        nstate++;
+        break;
+      }
+      e2 = POP();
+      e1 = POP();
+      s = alloc_state(NFA_SPLIT, e1.start, e2.start);
+      if (s == NULL) {
+        goto theend;
+      }
+      PUSH(frag(s, append(e1.out, e2.out)));
+      break;
+
+    case NFA_STAR:
+      // Zero or more, prefer more
+      if (nfa_calc_size == true) {
+        nstate++;
+        break;
+      }
+      e = POP();
+      s = alloc_state(NFA_SPLIT, e.start, NULL);
+      if (s == NULL) {
+        goto theend;
+      }
+      patch(e.out, s);
+      PUSH(frag(s, list1(&s->out1)));
+      break;
+
+    case NFA_STAR_NONGREEDY:
+      // Zero or more, prefer zero
+      if (nfa_calc_size == true) {
+        nstate++;
+        break;
+      }
+      e = POP();
+      s = alloc_state(NFA_SPLIT, NULL, e.start);
+      if (s == NULL) {
+        goto theend;
+      }
+      patch(e.out, s);
+      PUSH(frag(s, list1(&s->out)));
+      break;
+
+    case NFA_QUEST:
+      // one or zero atoms=> greedy match
+      if (nfa_calc_size == true) {
+        nstate++;
+        break;
+      }
+      e = POP();
+      s = alloc_state(NFA_SPLIT, e.start, NULL);
+      if (s == NULL) {
+        goto theend;
+      }
+      PUSH(frag(s, append(e.out, list1(&s->out1))));
+      break;
+
+    case NFA_QUEST_NONGREEDY:
+      // zero or one atoms => non-greedy match
+      if (nfa_calc_size == true) {
+        nstate++;
+        break;
+      }
+      e = POP();
+      s = alloc_state(NFA_SPLIT, NULL, e.start);
+      if (s == NULL) {
+        goto theend;
+      }
+      PUSH(frag(s, append(e.out, list1(&s->out))));
+      break;
+
+    case NFA_END_COLL:
+    case NFA_END_NEG_COLL:
+      // On the stack is the sequence starting with NFA_START_COLL or
+      // NFA_START_NEG_COLL and all possible characters. Patch it to
+      // add the output to the start.
+      if (nfa_calc_size == true) {
+        nstate++;
+        break;
+      }
+      e = POP();
+      s = alloc_state(NFA_END_COLL, NULL, NULL);
+      if (s == NULL) {
+        goto theend;
+      }
+      patch(e.out, s);
+      e.start->out1 = s;
+      PUSH(frag(e.start, list1(&s->out)));
+      break;
+
+    case NFA_RANGE:
+      // Before this are two characters, the low and high end of a
+      // range.  Turn them into two states with MIN and MAX.
+      if (nfa_calc_size == true) {
+        // nstate += 0;
+        break;
+      }
+      e2 = POP();
+      e1 = POP();
+      e2.start->val = e2.start->c;
+      e2.start->c = NFA_RANGE_MAX;
+      e1.start->val = e1.start->c;
+      e1.start->c = NFA_RANGE_MIN;
+      patch(e1.out, e2.start);
+      PUSH(frag(e1.start, e2.out));
+      break;
+
+    case NFA_EMPTY:
+      // 0-length, used in a repetition with max/min count of 0
+      if (nfa_calc_size == true) {
+        nstate++;
+        break;
+      }
+      s = alloc_state(NFA_EMPTY, NULL, NULL);
+      if (s == NULL) {
+        goto theend;
+      }
+      PUSH(frag(s, list1(&s->out)));
+      break;
+
+    case NFA_OPT_CHARS: {
+      int n;
+
+      // \%[abc] implemented as:
+      //    NFA_SPLIT
+      //    +-CHAR(a)
+      //    | +-NFA_SPLIT
+      //    |   +-CHAR(b)
+      //    |   | +-NFA_SPLIT
+      //    |   |   +-CHAR(c)
+      //    |   |   | +-next
+      //    |   |   +- next
+      //    |   +- next
+      //    +- next
+      n = *++p;  // get number of characters
+      if (nfa_calc_size == true) {
+        nstate += n;
+        break;
+      }
+      s = NULL;       // avoid compiler warning
+      e1.out = NULL;       // stores list with out1's
+      s1 = NULL;       // previous NFA_SPLIT to connect to
+      while (n-- > 0) {
+        e = POP();         // get character
+        s = alloc_state(NFA_SPLIT, e.start, NULL);
+        if (s == NULL) {
+          goto theend;
+        }
+        if (e1.out == NULL) {
+          e1 = e;
+        }
+        patch(e.out, s1);
+        append(e1.out, list1(&s->out1));
+        s1 = s;
+      }
+      PUSH(frag(s, e1.out));
+      break;
+    }
+
+    case NFA_PREV_ATOM_NO_WIDTH:
+    case NFA_PREV_ATOM_NO_WIDTH_NEG:
+    case NFA_PREV_ATOM_JUST_BEFORE:
+    case NFA_PREV_ATOM_JUST_BEFORE_NEG:
+    case NFA_PREV_ATOM_LIKE_PATTERN: {
+      int before = (*p == NFA_PREV_ATOM_JUST_BEFORE
+                    || *p == NFA_PREV_ATOM_JUST_BEFORE_NEG);
+      int pattern = (*p == NFA_PREV_ATOM_LIKE_PATTERN);
+      int start_state;
+      int end_state;
+      int n = 0;
+      nfa_state_T *zend;
+      nfa_state_T *skip;
+
+      switch (*p) {
+      case NFA_PREV_ATOM_NO_WIDTH:
+        start_state = NFA_START_INVISIBLE;
+        end_state = NFA_END_INVISIBLE;
+        break;
+      case NFA_PREV_ATOM_NO_WIDTH_NEG:
+        start_state = NFA_START_INVISIBLE_NEG;
+        end_state = NFA_END_INVISIBLE_NEG;
+        break;
+      case NFA_PREV_ATOM_JUST_BEFORE:
+        start_state = NFA_START_INVISIBLE_BEFORE;
+        end_state = NFA_END_INVISIBLE;
+        break;
+      case NFA_PREV_ATOM_JUST_BEFORE_NEG:
+        start_state = NFA_START_INVISIBLE_BEFORE_NEG;
+        end_state = NFA_END_INVISIBLE_NEG;
+        break;
+      default:           // NFA_PREV_ATOM_LIKE_PATTERN:
+        start_state = NFA_START_PATTERN;
+        end_state = NFA_END_PATTERN;
+        break;
+      }
+
+      if (before) {
+        n = *++p;         // get the count
+      }
+      // The \@= operator: match the preceding atom with zero width.
+      // The \@! operator: no match for the preceding atom.
+      // The \@<= operator: match for the preceding atom.
+      // The \@<! operator: no match for the preceding atom.
+      // Surrounds the preceding atom with START_INVISIBLE and
+      // END_INVISIBLE, similarly to MOPEN.
+
+      if (nfa_calc_size == true) {
+        nstate += pattern ? 4 : 2;
+        break;
+      }
+      e = POP();
+      s1 = alloc_state(end_state, NULL, NULL);
+      if (s1 == NULL) {
+        goto theend;
+      }
+
+      s = alloc_state(start_state, e.start, s1);
+      if (s == NULL) {
+        goto theend;
+      }
+      if (pattern) {
+        // NFA_ZEND -> NFA_END_PATTERN -> NFA_SKIP -> what follows.
+        skip = alloc_state(NFA_SKIP, NULL, NULL);
+        if (skip == NULL) {
+          goto theend;
+        }
+        zend = alloc_state(NFA_ZEND, s1, NULL);
+        if (zend == NULL) {
+          goto theend;
+        }
+        s1->out = skip;
+        patch(e.out, zend);
+        PUSH(frag(s, list1(&skip->out)));
+      } else {
+        patch(e.out, s1);
+        PUSH(frag(s, list1(&s1->out)));
+        if (before) {
+          if (n <= 0) {
+            // See if we can guess the maximum width, it avoids a
+            // lot of pointless tries.
+            n = nfa_max_width(e.start, 0);
+          }
+          s->val = n;           // store the count
+        }
+      }
+      break;
+    }
+
+    case NFA_COMPOSING:         // char with composing char
+      FALLTHROUGH;
+
+    case NFA_MOPEN:     // \( \) Submatch
+    case NFA_MOPEN1:
+    case NFA_MOPEN2:
+    case NFA_MOPEN3:
+    case NFA_MOPEN4:
+    case NFA_MOPEN5:
+    case NFA_MOPEN6:
+    case NFA_MOPEN7:
+    case NFA_MOPEN8:
+    case NFA_MOPEN9:
+    case NFA_ZOPEN:     // \z( \) Submatch
+    case NFA_ZOPEN1:
+    case NFA_ZOPEN2:
+    case NFA_ZOPEN3:
+    case NFA_ZOPEN4:
+    case NFA_ZOPEN5:
+    case NFA_ZOPEN6:
+    case NFA_ZOPEN7:
+    case NFA_ZOPEN8:
+    case NFA_ZOPEN9:
+    case NFA_NOPEN:     // \%( \) "Invisible Submatch"
+      if (nfa_calc_size == true) {
+        nstate += 2;
+        break;
+      }
+
+      mopen = *p;
+      switch (*p) {
+      case NFA_NOPEN:
+        mclose = NFA_NCLOSE; break;
+      case NFA_ZOPEN:
+        mclose = NFA_ZCLOSE; break;
+      case NFA_ZOPEN1:
+        mclose = NFA_ZCLOSE1; break;
+      case NFA_ZOPEN2:
+        mclose = NFA_ZCLOSE2; break;
+      case NFA_ZOPEN3:
+        mclose = NFA_ZCLOSE3; break;
+      case NFA_ZOPEN4:
+        mclose = NFA_ZCLOSE4; break;
+      case NFA_ZOPEN5:
+        mclose = NFA_ZCLOSE5; break;
+      case NFA_ZOPEN6:
+        mclose = NFA_ZCLOSE6; break;
+      case NFA_ZOPEN7:
+        mclose = NFA_ZCLOSE7; break;
+      case NFA_ZOPEN8:
+        mclose = NFA_ZCLOSE8; break;
+      case NFA_ZOPEN9:
+        mclose = NFA_ZCLOSE9; break;
+      case NFA_COMPOSING:
+        mclose = NFA_END_COMPOSING; break;
+      default:
+        // NFA_MOPEN, NFA_MOPEN1 .. NFA_MOPEN9
+        mclose = *p + NSUBEXP;
+        break;
+      }
+
+      // Allow "NFA_MOPEN" as a valid postfix representation for
+      // the empty regexp "". In this case, the NFA will be
+      // NFA_MOPEN -> NFA_MCLOSE. Note that this also allows
+      // empty groups of parenthesis, and empty mbyte chars
+      if (stackp == stack) {
+        s = alloc_state(mopen, NULL, NULL);
+        if (s == NULL) {
+          goto theend;
+        }
+        s1 = alloc_state(mclose, NULL, NULL);
+        if (s1 == NULL) {
+          goto theend;
+        }
+        patch(list1(&s->out), s1);
+        PUSH(frag(s, list1(&s1->out)));
+        break;
+      }
+
+      // At least one node was emitted before NFA_MOPEN, so
+      // at least one node will be between NFA_MOPEN and NFA_MCLOSE
+      e = POP();
+      s = alloc_state(mopen, e.start, NULL);         // `('
+      if (s == NULL) {
+        goto theend;
+      }
+
+      s1 = alloc_state(mclose, NULL, NULL);         // `)'
+      if (s1 == NULL) {
+        goto theend;
+      }
+      patch(e.out, s1);
+
+      if (mopen == NFA_COMPOSING) {
+        // COMPOSING->out1 = END_COMPOSING
+        patch(list1(&s->out1), s1);
+      }
+
+      PUSH(frag(s, list1(&s1->out)));
+      break;
+
+    case NFA_BACKREF1:
+    case NFA_BACKREF2:
+    case NFA_BACKREF3:
+    case NFA_BACKREF4:
+    case NFA_BACKREF5:
+    case NFA_BACKREF6:
+    case NFA_BACKREF7:
+    case NFA_BACKREF8:
+    case NFA_BACKREF9:
+    case NFA_ZREF1:
+    case NFA_ZREF2:
+    case NFA_ZREF3:
+    case NFA_ZREF4:
+    case NFA_ZREF5:
+    case NFA_ZREF6:
+    case NFA_ZREF7:
+    case NFA_ZREF8:
+    case NFA_ZREF9:
+      if (nfa_calc_size == true) {
+        nstate += 2;
+        break;
+      }
+      s = alloc_state(*p, NULL, NULL);
+      if (s == NULL) {
+        goto theend;
+      }
+      s1 = alloc_state(NFA_SKIP, NULL, NULL);
+      if (s1 == NULL) {
+        goto theend;
+      }
+      patch(list1(&s->out), s1);
+      PUSH(frag(s, list1(&s1->out)));
+      break;
+
+    case NFA_LNUM:
+    case NFA_LNUM_GT:
+    case NFA_LNUM_LT:
+    case NFA_VCOL:
+    case NFA_VCOL_GT:
+    case NFA_VCOL_LT:
+    case NFA_COL:
+    case NFA_COL_GT:
+    case NFA_COL_LT:
+    case NFA_MARK:
+    case NFA_MARK_GT:
+    case NFA_MARK_LT: {
+      int n = *++p;       // lnum, col or mark name
+
+      if (nfa_calc_size == true) {
+        nstate += 1;
+        break;
+      }
+      s = alloc_state(p[-1], NULL, NULL);
+      if (s == NULL) {
+        goto theend;
+      }
+      s->val = n;
+      PUSH(frag(s, list1(&s->out)));
+      break;
+    }
+
+    case NFA_ZSTART:
+    case NFA_ZEND:
+    default:
+      // Operands
+      if (nfa_calc_size == true) {
+        nstate++;
+        break;
+      }
+      s = alloc_state(*p, NULL, NULL);
+      if (s == NULL) {
+        goto theend;
+      }
+      PUSH(frag(s, list1(&s->out)));
+      break;
+    }     // switch(*p)
+  }   // for(p = postfix; *p; ++p)
+
+  if (nfa_calc_size == true) {
+    nstate++;
+    goto theend;        // Return value when counting size is ignored anyway
+  }
+
+  e = POP();
+  if (stackp != stack) {
+    xfree(stack);
+    EMSG_RET_NULL(_("E875: (NFA regexp) (While converting from postfix to NFA),"
+                    "too many states left on stack"));
+  }
+
+  if (istate >= nstate) {
+    xfree(stack);
+    EMSG_RET_NULL(_("E876: (NFA regexp) "
+                    "Not enough space to store the whole NFA "));
+  }
+
+  matchstate = &state_ptr[istate++];   // the match state
+  matchstate->c = NFA_MATCH;
+  matchstate->out = matchstate->out1 = NULL;
+  matchstate->id = 0;
+
+  patch(e.out, matchstate);
+  ret = e.start;
+
+theend:
+  xfree(stack);
+  return ret;
+
+#undef POP1
+#undef PUSH1
+#undef POP2
+#undef PUSH2
+#undef POP
+#undef PUSH
+}
+
+// After building the NFA program, inspect it to add optimization hints.
+static void nfa_postprocess(nfa_regprog_T *prog)
+{
+  int i;
+  int c;
+
+  for (i = 0; i < prog->nstate; i++) {
+    c = prog->state[i].c;
+    if (c == NFA_START_INVISIBLE
+        || c == NFA_START_INVISIBLE_NEG
+        || c == NFA_START_INVISIBLE_BEFORE
+        || c == NFA_START_INVISIBLE_BEFORE_NEG) {
+      int directly;
+
+      // Do it directly when what follows is possibly the end of the
+      // match.
+      if (match_follows(prog->state[i].out1->out, 0)) {
+        directly = true;
+      } else {
+        int ch_invisible = failure_chance(prog->state[i].out, 0);
+        int ch_follows = failure_chance(prog->state[i].out1->out, 0);
+
+        // Postpone when the invisible match is expensive or has a
+        // lower chance of failing.
+        if (c == NFA_START_INVISIBLE_BEFORE
+            || c == NFA_START_INVISIBLE_BEFORE_NEG) {
+          // "before" matches are very expensive when
+          // unbounded, always prefer what follows then,
+          // unless what follows will always match.
+          // Otherwise strongly prefer what follows.
+          if (prog->state[i].val <= 0 && ch_follows > 0) {
+            directly = false;
+          } else {
+            directly = ch_follows * 10 < ch_invisible;
+          }
+        } else {
+          // normal invisible, first do the one with the
+          // highest failure chance
+          directly = ch_follows < ch_invisible;
+        }
+      }
+      if (directly) {
+        // switch to the _FIRST state
+        prog->state[i].c++;
+      }
+    }
+  }
+}
+
+/////////////////////////////////////////////////////////////////
+// NFA execution code.
+/////////////////////////////////////////////////////////////////
+
+// Values for done in nfa_pim_T.
+#define NFA_PIM_UNUSED   0      // pim not used
+#define NFA_PIM_TODO     1      // pim not done yet
+#define NFA_PIM_MATCH    2      // pim executed, matches
+#define NFA_PIM_NOMATCH  3      // pim executed, no match
+
+#ifdef REGEXP_DEBUG
+static void log_subsexpr(regsubs_T *subs)
+{
+  log_subexpr(&subs->norm);
+  if (rex.nfa_has_zsubexpr) {
+    log_subexpr(&subs->synt);
+  }
+}
+
+static void log_subexpr(regsub_T *sub)
+{
+  int j;
+
+  for (j = 0; j < sub->in_use; j++) {
+    if (REG_MULTI) {
+      fprintf(log_fd, "*** group %d, start: c=%d, l=%d, end: c=%d, l=%d\n",
+              j,
+              sub->list.multi[j].start_col,
+              (int)sub->list.multi[j].start_lnum,
+              sub->list.multi[j].end_col,
+              (int)sub->list.multi[j].end_lnum);
+    } else {
+      char *s = (char *)sub->list.line[j].start;
+      char *e = (char *)sub->list.line[j].end;
+
+      fprintf(log_fd, "*** group %d, start: \"%s\", end: \"%s\"\n",
+              j,
+              s == NULL ? "NULL" : s,
+              e == NULL ? "NULL" : e);
+    }
+  }
+}
+
+static char *pim_info(const nfa_pim_T *pim)
+{
+  static char buf[30];
+
+  if (pim == NULL || pim->result == NFA_PIM_UNUSED) {
+    buf[0] = NUL;
+  } else {
+    snprintf(buf, sizeof(buf), " PIM col %d",
+             REG_MULTI
+             ? (int)pim->end.pos.col
+             : (int)(pim->end.ptr - rex.input));
+  }
+  return buf;
+}
+
+#endif
+
+// Used during execution: whether a match has been found.
+static int nfa_match;
+static proftime_T *nfa_time_limit;
+static int *nfa_timed_out;
+static int nfa_time_count;
+
+// Copy postponed invisible match info from "from" to "to".
+static void copy_pim(nfa_pim_T *to, nfa_pim_T *from)
+{
+  to->result = from->result;
+  to->state = from->state;
+  copy_sub(&to->subs.norm, &from->subs.norm);
+  if (rex.nfa_has_zsubexpr) {
+    copy_sub(&to->subs.synt, &from->subs.synt);
+  }
+  to->end = from->end;
+}
+
+static void clear_sub(regsub_T *sub)
+{
+  if (REG_MULTI) {
+    // Use 0xff to set lnum to -1
+    memset(sub->list.multi, 0xff, sizeof(struct multipos) * (size_t)rex.nfa_nsubexpr);
+  } else {
+    memset(sub->list.line, 0, sizeof(struct linepos) * (size_t)rex.nfa_nsubexpr);
+  }
+  sub->in_use = 0;
+}
+
+// Copy the submatches from "from" to "to".
+static void copy_sub(regsub_T *to, regsub_T *from)
+{
+  to->in_use = from->in_use;
+  if (from->in_use <= 0) {
+    return;
+  }
+
+  // Copy the match start and end positions.
+  if (REG_MULTI) {
+    memmove(&to->list.multi[0], &from->list.multi[0],
+            sizeof(struct multipos) * (size_t)from->in_use);
+    to->orig_start_col = from->orig_start_col;
+  } else {
+    memmove(&to->list.line[0], &from->list.line[0],
+            sizeof(struct linepos) * (size_t)from->in_use);
+  }
+}
+
+// Like copy_sub() but exclude the main match.
+static void copy_sub_off(regsub_T *to, regsub_T *from)
+{
+  if (to->in_use < from->in_use) {
+    to->in_use = from->in_use;
+  }
+  if (from->in_use <= 1) {
+    return;
+  }
+
+  // Copy the match start and end positions.
+  if (REG_MULTI) {
+    memmove(&to->list.multi[1], &from->list.multi[1],
+            sizeof(struct multipos) * (size_t)(from->in_use - 1));
+  } else {
+    memmove(&to->list.line[1], &from->list.line[1],
+            sizeof(struct linepos) * (size_t)(from->in_use - 1));
+  }
+}
+
+// Like copy_sub() but only do the end of the main match if \ze is present.
+static void copy_ze_off(regsub_T *to, regsub_T *from)
+{
+  if (!rex.nfa_has_zend) {
+    return;
+  }
+
+  if (REG_MULTI) {
+    if (from->list.multi[0].end_lnum >= 0) {
+      to->list.multi[0].end_lnum = from->list.multi[0].end_lnum;
+      to->list.multi[0].end_col = from->list.multi[0].end_col;
+    }
+  } else {
+    if (from->list.line[0].end != NULL) {
+      to->list.line[0].end = from->list.line[0].end;
+    }
+  }
+}
+
+// Return true if "sub1" and "sub2" have the same start positions.
+// When using back-references also check the end position.
+static bool sub_equal(regsub_T *sub1, regsub_T *sub2)
+{
+  int i;
+  int todo;
+  linenr_T s1;
+  linenr_T s2;
+  uint8_t *sp1;
+  uint8_t *sp2;
+
+  todo = sub1->in_use > sub2->in_use ? sub1->in_use : sub2->in_use;
+  if (REG_MULTI) {
+    for (i = 0; i < todo; i++) {
+      if (i < sub1->in_use) {
+        s1 = sub1->list.multi[i].start_lnum;
+      } else {
+        s1 = -1;
+      }
+      if (i < sub2->in_use) {
+        s2 = sub2->list.multi[i].start_lnum;
+      } else {
+        s2 = -1;
+      }
+      if (s1 != s2) {
+        return false;
+      }
+      if (s1 != -1 && sub1->list.multi[i].start_col
+          != sub2->list.multi[i].start_col) {
+        return false;
+      }
+      if (rex.nfa_has_backref) {
+        if (i < sub1->in_use) {
+          s1 = sub1->list.multi[i].end_lnum;
+        } else {
+          s1 = -1;
+        }
+        if (i < sub2->in_use) {
+          s2 = sub2->list.multi[i].end_lnum;
+        } else {
+          s2 = -1;
+        }
+        if (s1 != s2) {
+          return false;
+        }
+        if (s1 != -1
+            && sub1->list.multi[i].end_col != sub2->list.multi[i].end_col) {
+          return false;
+        }
+      }
+    }
+  } else {
+    for (i = 0; i < todo; i++) {
+      if (i < sub1->in_use) {
+        sp1 = sub1->list.line[i].start;
+      } else {
+        sp1 = NULL;
+      }
+      if (i < sub2->in_use) {
+        sp2 = sub2->list.line[i].start;
+      } else {
+        sp2 = NULL;
+      }
+      if (sp1 != sp2) {
+        return false;
+      }
+      if (rex.nfa_has_backref) {
+        if (i < sub1->in_use) {
+          sp1 = sub1->list.line[i].end;
+        } else {
+          sp1 = NULL;
+        }
+        if (i < sub2->in_use) {
+          sp2 = sub2->list.line[i].end;
+        } else {
+          sp2 = NULL;
+        }
+        if (sp1 != sp2) {
+          return false;
+        }
+      }
+    }
+  }
+
+  return true;
+}
+
+#ifdef REGEXP_DEBUG
+static void open_debug_log(TriState result)
+{
+  log_fd = fopen(NFA_REGEXP_RUN_LOG, "a");
+  if (log_fd == NULL) {
+    emsg(_(e_log_open_failed));
+    log_fd = stderr;
+  }
+
+  fprintf(log_fd, "****************************\n");
+  fprintf(log_fd, "FINISHED RUNNING nfa_regmatch() recursively\n");
+  fprintf(log_fd, "MATCH = %s\n", result == kTrue ? "OK" : result == kNone ? "MAYBE" : "FALSE");
+  fprintf(log_fd, "****************************\n");
+}
+
+static void report_state(char *action, regsub_T *sub, nfa_state_T *state, int lid, nfa_pim_T *pim)
+{
+  int col;
+
+  if (sub->in_use <= 0) {
+    col = -1;
+  } else if (REG_MULTI) {
+    col = sub->list.multi[0].start_col;
+  } else {
+    col = (int)(sub->list.line[0].start - rex.line);
+  }
+  nfa_set_code(state->c);
+  if (log_fd == NULL) {
+    open_debug_log(kNone);
+  }
+  fprintf(log_fd, "> %s state %d to list %d. char %d: %s (start col %d)%s\n",
+          action, abs(state->id), lid, state->c, code, col,
+          pim_info(pim));
+}
+
+#endif
+
+/// @param l      runtime state list
+/// @param state  state to update
+/// @param subs   pointers to subexpressions
+/// @param pim    postponed match or NULL
+///
+/// @return  true if the same state is already in list "l" with the same
+///          positions as "subs".
+static bool has_state_with_pos(nfa_list_T *l, nfa_state_T *state, regsubs_T *subs, nfa_pim_T *pim)
+  FUNC_ATTR_NONNULL_ARG(1, 2, 3)
+{
+  for (int i = 0; i < l->n; i++) {
+    nfa_thread_T *thread = &l->t[i];
+    if (thread->state->id == state->id
+        && sub_equal(&thread->subs.norm, &subs->norm)
+        && (!rex.nfa_has_zsubexpr
+            || sub_equal(&thread->subs.synt, &subs->synt))
+        && pim_equal(&thread->pim, pim)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+// Return true if "one" and "two" are equal.  That includes when both are not
+// set.
+static bool pim_equal(const nfa_pim_T *one, const nfa_pim_T *two)
+{
+  const bool one_unused = (one == NULL || one->result == NFA_PIM_UNUSED);
+  const bool two_unused = (two == NULL || two->result == NFA_PIM_UNUSED);
+
+  if (one_unused) {
+    // one is unused: equal when two is also unused
+    return two_unused;
+  }
+  if (two_unused) {
+    // one is used and two is not: not equal
+    return false;
+  }
+  // compare the state id
+  if (one->state->id != two->state->id) {
+    return false;
+  }
+  // compare the position
+  if (REG_MULTI) {
+    return one->end.pos.lnum == two->end.pos.lnum
+           && one->end.pos.col == two->end.pos.col;
+  }
+  return one->end.ptr == two->end.ptr;
+}
+
+// Return true if "state" leads to a NFA_MATCH without advancing the input.
+static bool match_follows(const nfa_state_T *startstate, int depth)
+  FUNC_ATTR_NONNULL_ALL
+{
+  const nfa_state_T *state = startstate;
+
+  // avoid too much recursion
+  if (depth > 10) {
+    return false;
+  }
+  while (state != NULL) {
+    switch (state->c) {
+    case NFA_MATCH:
+    case NFA_MCLOSE:
+    case NFA_END_INVISIBLE:
+    case NFA_END_INVISIBLE_NEG:
+    case NFA_END_PATTERN:
+      return true;
+
+    case NFA_SPLIT:
+      return match_follows(state->out, depth + 1)
+             || match_follows(state->out1, depth + 1);
+
+    case NFA_START_INVISIBLE:
+    case NFA_START_INVISIBLE_FIRST:
+    case NFA_START_INVISIBLE_BEFORE:
+    case NFA_START_INVISIBLE_BEFORE_FIRST:
+    case NFA_START_INVISIBLE_NEG:
+    case NFA_START_INVISIBLE_NEG_FIRST:
+    case NFA_START_INVISIBLE_BEFORE_NEG:
+    case NFA_START_INVISIBLE_BEFORE_NEG_FIRST:
+    case NFA_COMPOSING:
+      // skip ahead to next state
+      state = state->out1->out;
+      continue;
+
+    case NFA_ANY:
+    case NFA_ANY_COMPOSING:
+    case NFA_IDENT:
+    case NFA_SIDENT:
+    case NFA_KWORD:
+    case NFA_SKWORD:
+    case NFA_FNAME:
+    case NFA_SFNAME:
+    case NFA_PRINT:
+    case NFA_SPRINT:
+    case NFA_WHITE:
+    case NFA_NWHITE:
+    case NFA_DIGIT:
+    case NFA_NDIGIT:
+    case NFA_HEX:
+    case NFA_NHEX:
+    case NFA_OCTAL:
+    case NFA_NOCTAL:
+    case NFA_WORD:
+    case NFA_NWORD:
+    case NFA_HEAD:
+    case NFA_NHEAD:
+    case NFA_ALPHA:
+    case NFA_NALPHA:
+    case NFA_LOWER:
+    case NFA_NLOWER:
+    case NFA_UPPER:
+    case NFA_NUPPER:
+    case NFA_LOWER_IC:
+    case NFA_NLOWER_IC:
+    case NFA_UPPER_IC:
+    case NFA_NUPPER_IC:
+    case NFA_START_COLL:
+    case NFA_START_NEG_COLL:
+    case NFA_NEWL:
+      // state will advance input
+      return false;
+
+    default:
+      if (state->c > 0) {
+        // state will advance input
+        return false;
+      }
+      // Others: zero-width or possibly zero-width, might still find
+      // a match at the same position, keep looking.
+      break;
+    }
+    state = state->out;
+  }
+  return false;
+}
+
+/// @param l      runtime state list
+/// @param state  state to update
+/// @param subs   pointers to subexpressions
+///
+/// @return  true if "state" is already in list "l".
+static bool state_in_list(nfa_list_T *l, nfa_state_T *state, regsubs_T *subs)
+  FUNC_ATTR_NONNULL_ALL
+{
+  if (state->lastlist[nfa_ll_index] == l->id) {
+    if (!rex.nfa_has_backref || has_state_with_pos(l, state, subs, NULL)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+// Offset used for "off" by addstate_here().
+#define ADDSTATE_HERE_OFFSET 10
+
+/// Add "state" and possibly what follows to state list ".".
+///
+/// @param l         runtime state list
+/// @param state     state to update
+/// @param subs_arg  pointers to subexpressions
+/// @param pim       postponed look-behind match
+/// @param off_arg   byte offset, when -1 go to next line
+///
+/// @return  "subs_arg", possibly copied into temp_subs.
+///          NULL when recursiveness is too deep.
+static regsubs_T *addstate(nfa_list_T *l, nfa_state_T *state, regsubs_T *subs_arg, nfa_pim_T *pim,
+                           int off_arg)
+  FUNC_ATTR_NONNULL_ARG(1, 2) FUNC_ATTR_WARN_UNUSED_RESULT
+{
+  int subidx;
+  int off = off_arg;
+  int add_here = false;
+  int listindex = 0;
+  int k;
+  int found = false;
+  nfa_thread_T *thread;
+  struct multipos save_multipos;
+  int save_in_use;
+  uint8_t *save_ptr;
+  int i;
+  regsub_T *sub;
+  regsubs_T *subs = subs_arg;
+  static regsubs_T temp_subs;
+#ifdef REGEXP_DEBUG
+  int did_print = false;
+#endif
+  static int depth = 0;
+
+  // This function is called recursively.  When the depth is too much we run
+  // out of stack and crash, limit recursiveness here.
+  if (++depth >= 5000 || subs == NULL) {
+    depth--;
+    return NULL;
+  }
+
+  if (off_arg <= -ADDSTATE_HERE_OFFSET) {
+    add_here = true;
+    off = 0;
+    listindex = -(off_arg + ADDSTATE_HERE_OFFSET);
+  }
+
+  switch (state->c) {
+  case NFA_NCLOSE:
+  case NFA_MCLOSE:
+  case NFA_MCLOSE1:
+  case NFA_MCLOSE2:
+  case NFA_MCLOSE3:
+  case NFA_MCLOSE4:
+  case NFA_MCLOSE5:
+  case NFA_MCLOSE6:
+  case NFA_MCLOSE7:
+  case NFA_MCLOSE8:
+  case NFA_MCLOSE9:
+  case NFA_ZCLOSE:
+  case NFA_ZCLOSE1:
+  case NFA_ZCLOSE2:
+  case NFA_ZCLOSE3:
+  case NFA_ZCLOSE4:
+  case NFA_ZCLOSE5:
+  case NFA_ZCLOSE6:
+  case NFA_ZCLOSE7:
+  case NFA_ZCLOSE8:
+  case NFA_ZCLOSE9:
+  case NFA_MOPEN:
+  case NFA_ZEND:
+  case NFA_SPLIT:
+  case NFA_EMPTY:
+    // These nodes are not added themselves but their "out" and/or
+    // "out1" may be added below.
+    break;
+
+  case NFA_BOL:
+  case NFA_BOF:
+    // "^" won't match past end-of-line, don't bother trying.
+    // Except when at the end of the line, or when we are going to the
+    // next line for a look-behind match.
+    if (rex.input > rex.line
+        && *rex.input != NUL
+        && (nfa_endp == NULL
+            || !REG_MULTI
+            || rex.lnum == nfa_endp->se_u.pos.lnum)) {
+      goto skip_add;
+    }
+    FALLTHROUGH;
+
+  case NFA_MOPEN1:
+  case NFA_MOPEN2:
+  case NFA_MOPEN3:
+  case NFA_MOPEN4:
+  case NFA_MOPEN5:
+  case NFA_MOPEN6:
+  case NFA_MOPEN7:
+  case NFA_MOPEN8:
+  case NFA_MOPEN9:
+  case NFA_ZOPEN:
+  case NFA_ZOPEN1:
+  case NFA_ZOPEN2:
+  case NFA_ZOPEN3:
+  case NFA_ZOPEN4:
+  case NFA_ZOPEN5:
+  case NFA_ZOPEN6:
+  case NFA_ZOPEN7:
+  case NFA_ZOPEN8:
+  case NFA_ZOPEN9:
+  case NFA_NOPEN:
+  case NFA_ZSTART:
+  // These nodes need to be added so that we can bail out when it
+  // was added to this list before at the same position to avoid an
+  // endless loop for "\(\)*"
+
+  default:
+    if (state->lastlist[nfa_ll_index] == l->id && state->c != NFA_SKIP) {
+      // This state is already in the list, don't add it again,
+      // unless it is an MOPEN that is used for a backreference or
+      // when there is a PIM. For NFA_MATCH check the position,
+      // lower position is preferred.
+      if (!rex.nfa_has_backref && pim == NULL && !l->has_pim
+          && state->c != NFA_MATCH) {
+        // When called from addstate_here() do insert before
+        // existing states.
+        if (add_here) {
+          for (k = 0; k < l->n && k < listindex; k++) {
+            if (l->t[k].state->id == state->id) {
+              found = true;
+              break;
+            }
+          }
+        }
+
+        if (!add_here || found) {
+skip_add:
+#ifdef REGEXP_DEBUG
+          nfa_set_code(state->c);
+          fprintf(log_fd,
+                  "> Not adding state %d to list %d. char %d: %s pim: %s has_pim: %d found: %d\n",
+                  abs(state->id), l->id, state->c, code,
+                  pim == NULL ? "NULL" : "yes", l->has_pim, found);
+#endif
+          depth--;
+          return subs;
+        }
+      }
+
+      // Do not add the state again when it exists with the same
+      // positions.
+      if (has_state_with_pos(l, state, subs, pim)) {
+        goto skip_add;
+      }
+    }
+
+    // When there are backreferences or PIMs the number of states may
+    // be (a lot) bigger than anticipated.
+    if (l->n == l->len) {
+      const int newlen = l->len * 3 / 2 + 50;
+      const size_t newsize = (size_t)newlen * sizeof(nfa_thread_T);
+
+      if ((int64_t)(newsize >> 10) >= p_mmp) {
+        emsg(_(e_pattern_uses_more_memory_than_maxmempattern));
+        depth--;
+        return NULL;
+      }
+      if (subs != &temp_subs) {
+        // "subs" may point into the current array, need to make a
+        // copy before it becomes invalid.
+        copy_sub(&temp_subs.norm, &subs->norm);
+        if (rex.nfa_has_zsubexpr) {
+          copy_sub(&temp_subs.synt, &subs->synt);
+        }
+        subs = &temp_subs;
+      }
+
+      nfa_thread_T *const newt = xrealloc(l->t, newsize);
+      l->t = newt;
+      l->len = newlen;
+    }
+
+    // add the state to the list
+    state->lastlist[nfa_ll_index] = l->id;
+    thread = &l->t[l->n++];
+    thread->state = state;
+    if (pim == NULL) {
+      thread->pim.result = NFA_PIM_UNUSED;
+    } else {
+      copy_pim(&thread->pim, pim);
+      l->has_pim = true;
+    }
+    copy_sub(&thread->subs.norm, &subs->norm);
+    if (rex.nfa_has_zsubexpr) {
+      copy_sub(&thread->subs.synt, &subs->synt);
+    }
+#ifdef REGEXP_DEBUG
+    report_state("Adding", &thread->subs.norm, state, l->id, pim);
+    did_print = true;
 #endif
+  }
+
+#ifdef REGEXP_DEBUG
+  if (!did_print) {
+    report_state("Processing", &subs->norm, state, l->id, pim);
+  }
+#endif
+  switch (state->c) {
+  case NFA_MATCH:
+    break;
+
+  case NFA_SPLIT:
+    // order matters here
+    subs = addstate(l, state->out, subs, pim, off_arg);
+    subs = addstate(l, state->out1, subs, pim, off_arg);
+    break;
+
+  case NFA_EMPTY:
+  case NFA_NOPEN:
+  case NFA_NCLOSE:
+    subs = addstate(l, state->out, subs, pim, off_arg);
+    break;
+
+  case NFA_MOPEN:
+  case NFA_MOPEN1:
+  case NFA_MOPEN2:
+  case NFA_MOPEN3:
+  case NFA_MOPEN4:
+  case NFA_MOPEN5:
+  case NFA_MOPEN6:
+  case NFA_MOPEN7:
+  case NFA_MOPEN8:
+  case NFA_MOPEN9:
+  case NFA_ZOPEN:
+  case NFA_ZOPEN1:
+  case NFA_ZOPEN2:
+  case NFA_ZOPEN3:
+  case NFA_ZOPEN4:
+  case NFA_ZOPEN5:
+  case NFA_ZOPEN6:
+  case NFA_ZOPEN7:
+  case NFA_ZOPEN8:
+  case NFA_ZOPEN9:
+  case NFA_ZSTART:
+    if (state->c == NFA_ZSTART) {
+      subidx = 0;
+      sub = &subs->norm;
+    } else if (state->c >= NFA_ZOPEN && state->c <= NFA_ZOPEN9) {
+      subidx = state->c - NFA_ZOPEN;
+      sub = &subs->synt;
+    } else {
+      subidx = state->c - NFA_MOPEN;
+      sub = &subs->norm;
+    }
+
+    // avoid compiler warnings
+    save_ptr = NULL;
+    CLEAR_FIELD(save_multipos);
+
+    // Set the position (with "off" added) in the subexpression.  Save
+    // and restore it when it was in use.  Otherwise fill any gap.
+    if (REG_MULTI) {
+      if (subidx < sub->in_use) {
+        save_multipos = sub->list.multi[subidx];
+        save_in_use = -1;
+      } else {
+        save_in_use = sub->in_use;
+        for (i = sub->in_use; i < subidx; i++) {
+          sub->list.multi[i].start_lnum = -1;
+          sub->list.multi[i].end_lnum = -1;
+        }
+        sub->in_use = subidx + 1;
+      }
+      if (off == -1) {
+        sub->list.multi[subidx].start_lnum = rex.lnum + 1;
+        sub->list.multi[subidx].start_col = 0;
+      } else {
+        sub->list.multi[subidx].start_lnum = rex.lnum;
+        sub->list.multi[subidx].start_col =
+          (colnr_T)(rex.input - rex.line + off);
+      }
+      sub->list.multi[subidx].end_lnum = -1;
+    } else {
+      if (subidx < sub->in_use) {
+        save_ptr = sub->list.line[subidx].start;
+        save_in_use = -1;
+      } else {
+        save_in_use = sub->in_use;
+        for (i = sub->in_use; i < subidx; i++) {
+          sub->list.line[i].start = NULL;
+          sub->list.line[i].end = NULL;
+        }
+        sub->in_use = subidx + 1;
+      }
+      sub->list.line[subidx].start = rex.input + off;
+    }
+
+    subs = addstate(l, state->out, subs, pim, off_arg);
+    if (subs == NULL) {
+      break;
+    }
+    // "subs" may have changed, need to set "sub" again.
+    if (state->c >= NFA_ZOPEN && state->c <= NFA_ZOPEN9) {
+      sub = &subs->synt;
+    } else {
+      sub = &subs->norm;
+    }
+
+    if (save_in_use == -1) {
+      if (REG_MULTI) {
+        sub->list.multi[subidx] = save_multipos;
+      } else {
+        sub->list.line[subidx].start = save_ptr;
+      }
+    } else {
+      sub->in_use = save_in_use;
+    }
+    break;
+
+  case NFA_MCLOSE:
+    if (rex.nfa_has_zend
+        && (REG_MULTI
+            ? subs->norm.list.multi[0].end_lnum >= 0
+            : subs->norm.list.line[0].end != NULL)) {
+      // Do not overwrite the position set by \ze.
+      subs = addstate(l, state->out, subs, pim, off_arg);
+      break;
+    }
+    FALLTHROUGH;
+  case NFA_MCLOSE1:
+  case NFA_MCLOSE2:
+  case NFA_MCLOSE3:
+  case NFA_MCLOSE4:
+  case NFA_MCLOSE5:
+  case NFA_MCLOSE6:
+  case NFA_MCLOSE7:
+  case NFA_MCLOSE8:
+  case NFA_MCLOSE9:
+  case NFA_ZCLOSE:
+  case NFA_ZCLOSE1:
+  case NFA_ZCLOSE2:
+  case NFA_ZCLOSE3:
+  case NFA_ZCLOSE4:
+  case NFA_ZCLOSE5:
+  case NFA_ZCLOSE6:
+  case NFA_ZCLOSE7:
+  case NFA_ZCLOSE8:
+  case NFA_ZCLOSE9:
+  case NFA_ZEND:
+    if (state->c == NFA_ZEND) {
+      subidx = 0;
+      sub = &subs->norm;
+    } else if (state->c >= NFA_ZCLOSE && state->c <= NFA_ZCLOSE9) {
+      subidx = state->c - NFA_ZCLOSE;
+      sub = &subs->synt;
+    } else {
+      subidx = state->c - NFA_MCLOSE;
+      sub = &subs->norm;
+    }
+
+    // We don't fill in gaps here, there must have been an MOPEN that
+    // has done that.
+    save_in_use = sub->in_use;
+    if (sub->in_use <= subidx) {
+      sub->in_use = subidx + 1;
+    }
+    if (REG_MULTI) {
+      save_multipos = sub->list.multi[subidx];
+      if (off == -1) {
+        sub->list.multi[subidx].end_lnum = rex.lnum + 1;
+        sub->list.multi[subidx].end_col = 0;
+      } else {
+        sub->list.multi[subidx].end_lnum = rex.lnum;
+        sub->list.multi[subidx].end_col =
+          (colnr_T)(rex.input - rex.line + off);
+      }
+      // avoid compiler warnings
+      save_ptr = NULL;
+    } else {
+      save_ptr = sub->list.line[subidx].end;
+      sub->list.line[subidx].end = rex.input + off;
+      // avoid compiler warnings
+      CLEAR_FIELD(save_multipos);
+    }
+
+    subs = addstate(l, state->out, subs, pim, off_arg);
+    if (subs == NULL) {
+      break;
+    }
+    // "subs" may have changed, need to set "sub" again.
+    if (state->c >= NFA_ZCLOSE && state->c <= NFA_ZCLOSE9) {
+      sub = &subs->synt;
+    } else {
+      sub = &subs->norm;
+    }
+
+    if (REG_MULTI) {
+      sub->list.multi[subidx] = save_multipos;
+    } else {
+      sub->list.line[subidx].end = save_ptr;
+    }
+    sub->in_use = save_in_use;
+    break;
+  }
+  depth--;
+  return subs;
+}
+
+/// Like addstate(), but the new state(s) are put at position "*ip".
+/// Used for zero-width matches, next state to use is the added one.
+/// This makes sure the order of states to be tried does not change, which
+/// matters for alternatives.
+///
+/// @param l      runtime state list
+/// @param state  state to update
+/// @param subs   pointers to subexpressions
+/// @param pim    postponed look-behind match
+static regsubs_T *addstate_here(nfa_list_T *l, nfa_state_T *state, regsubs_T *subs, nfa_pim_T *pim,
+                                int *ip)
+  FUNC_ATTR_NONNULL_ARG(1, 2, 5) FUNC_ATTR_WARN_UNUSED_RESULT
+{
+  int tlen = l->n;
+  int count;
+  int listidx = *ip;
+
+  // First add the state(s) at the end, so that we know how many there are.
+  // Pass the listidx as offset (avoids adding another argument to
+  // addstate()).
+  regsubs_T *r = addstate(l, state, subs, pim, -listidx - ADDSTATE_HERE_OFFSET);
+  if (r == NULL) {
+    return NULL;
+  }
+
+  // when "*ip" was at the end of the list, nothing to do
+  if (listidx + 1 == tlen) {
+    return r;
+  }
+
+  // re-order to put the new state at the current position
+  count = l->n - tlen;
+  if (count == 0) {
+    return r;  // no state got added
+  }
+  if (count == 1) {
+    // overwrite the current state
+    l->t[listidx] = l->t[l->n - 1];
+  } else if (count > 1) {
+    if (l->n + count - 1 >= l->len) {
+      // not enough space to move the new states, reallocate the list
+      // and move the states to the right position
+      const int newlen = l->len * 3 / 2 + 50;
+      const size_t newsize = (size_t)newlen * sizeof(nfa_thread_T);
+
+      if ((int64_t)(newsize >> 10) >= p_mmp) {
+        emsg(_(e_pattern_uses_more_memory_than_maxmempattern));
+        return NULL;
+      }
+      nfa_thread_T *const newl = xmalloc(newsize);
+      l->len = newlen;
+      memmove(&(newl[0]),
+              &(l->t[0]),
+              sizeof(nfa_thread_T) * (size_t)listidx);
+      memmove(&(newl[listidx]),
+              &(l->t[l->n - count]),
+              sizeof(nfa_thread_T) * (size_t)count);
+      memmove(&(newl[listidx + count]),
+              &(l->t[listidx + 1]),
+              sizeof(nfa_thread_T) * (size_t)(l->n - count - listidx - 1));
+      xfree(l->t);
+      l->t = newl;
+    } else {
+      // make space for new states, then move them from the
+      // end to the current position
+      memmove(&(l->t[listidx + count]),
+              &(l->t[listidx + 1]),
+              sizeof(nfa_thread_T) * (size_t)(l->n - listidx - 1));
+      memmove(&(l->t[listidx]),
+              &(l->t[l->n - 1]),
+              sizeof(nfa_thread_T) * (size_t)count);
+    }
+  }
+  l->n--;
+  *ip = listidx - 1;
+
+  return r;
+}
+
+// Check character class "class" against current character c.
+static int check_char_class(int cls, int c)
+{
+  switch (cls) {
+  case NFA_CLASS_ALNUM:
+    if (c >= 1 && c < 128 && isalnum(c)) {
+      return OK;
+    }
+    break;
+  case NFA_CLASS_ALPHA:
+    if (c >= 1 && c < 128 && isalpha(c)) {
+      return OK;
+    }
+    break;
+  case NFA_CLASS_BLANK:
+    if (c == ' ' || c == '\t') {
+      return OK;
+    }
+    break;
+  case NFA_CLASS_CNTRL:
+    if (c >= 1 && c <= 127 && iscntrl(c)) {
+      return OK;
+    }
+    break;
+  case NFA_CLASS_DIGIT:
+    if (ascii_isdigit(c)) {
+      return OK;
+    }
+    break;
+  case NFA_CLASS_GRAPH:
+    if (c >= 1 && c <= 127 && isgraph(c)) {
+      return OK;
+    }
+    break;
+  case NFA_CLASS_LOWER:
+    if (mb_islower(c) && c != 170 && c != 186) {
+      return OK;
+    }
+    break;
+  case NFA_CLASS_PRINT:
+    if (vim_isprintc(c)) {
+      return OK;
+    }
+    break;
+  case NFA_CLASS_PUNCT:
+    if (c >= 1 && c < 128 && ispunct(c)) {
+      return OK;
+    }
+    break;
+  case NFA_CLASS_SPACE:
+    if ((c >= 9 && c <= 13) || (c == ' ')) {
+      return OK;
+    }
+    break;
+  case NFA_CLASS_UPPER:
+    if (mb_isupper(c)) {
+      return OK;
+    }
+    break;
+  case NFA_CLASS_XDIGIT:
+    if (ascii_isxdigit(c)) {
+      return OK;
+    }
+    break;
+  case NFA_CLASS_TAB:
+    if (c == '\t') {
+      return OK;
+    }
+    break;
+  case NFA_CLASS_RETURN:
+    if (c == '\r') {
+      return OK;
+    }
+    break;
+  case NFA_CLASS_BACKSPACE:
+    if (c == '\b') {
+      return OK;
+    }
+    break;
+  case NFA_CLASS_ESCAPE:
+    if (c == ESC) {
+      return OK;
+    }
+    break;
+  case NFA_CLASS_IDENT:
+    if (vim_isIDc(c)) {
+      return OK;
+    }
+    break;
+  case NFA_CLASS_KEYWORD:
+    if (reg_iswordc(c)) {
+      return OK;
+    }
+    break;
+  case NFA_CLASS_FNAME:
+    if (vim_isfilec(c)) {
+      return OK;
+    }
+    break;
+
+  default:
+    // should not be here :P
+    siemsg(_(e_ill_char_class), (int64_t)cls);
+    return FAIL;
+  }
+  return FAIL;
+}
+
+/// Check for a match with subexpression "subidx".
+///
+/// @param sub      pointers to subexpressions
+/// @param bytelen  out: length of match in bytes
+///
+/// @return  true if it matches.
+static int match_backref(regsub_T *sub, int subidx, int *bytelen)
+{
+  int len;
+
+  if (sub->in_use <= subidx) {
+retempty:
+    // backref was not set, match an empty string
+    *bytelen = 0;
+    return true;
+  }
+
+  if (REG_MULTI) {
+    if (sub->list.multi[subidx].start_lnum < 0
+        || sub->list.multi[subidx].end_lnum < 0) {
+      goto retempty;
+    }
+    if (sub->list.multi[subidx].start_lnum == rex.lnum
+        && sub->list.multi[subidx].end_lnum == rex.lnum) {
+      len = sub->list.multi[subidx].end_col
+            - sub->list.multi[subidx].start_col;
+      if (cstrncmp((char *)rex.line + sub->list.multi[subidx].start_col,
+                   (char *)rex.input, &len) == 0) {
+        *bytelen = len;
+        return true;
+      }
+    } else {
+      if (match_with_backref(sub->list.multi[subidx].start_lnum,
+                             sub->list.multi[subidx].start_col,
+                             sub->list.multi[subidx].end_lnum,
+                             sub->list.multi[subidx].end_col,
+                             bytelen) == RA_MATCH) {
+        return true;
+      }
+    }
+  } else {
+    if (sub->list.line[subidx].start == NULL
+        || sub->list.line[subidx].end == NULL) {
+      goto retempty;
+    }
+    len = (int)(sub->list.line[subidx].end - sub->list.line[subidx].start);
+    if (cstrncmp((char *)sub->list.line[subidx].start, (char *)rex.input, &len) == 0) {
+      *bytelen = len;
+      return true;
+    }
+  }
+  return false;
+}
+
+/// Check for a match with \z subexpression "subidx".
+///
+/// @param bytelen  out: length of match in bytes
+///
+/// @return  true if it matches.
+static int match_zref(int subidx, int *bytelen)
+{
+  int len;
+
+  cleanup_zsubexpr();
+  if (re_extmatch_in == NULL || re_extmatch_in->matches[subidx] == NULL) {
+    // backref was not set, match an empty string
+    *bytelen = 0;
+    return true;
+  }
+
+  len = (int)strlen((char *)re_extmatch_in->matches[subidx]);
+  if (cstrncmp((char *)re_extmatch_in->matches[subidx], (char *)rex.input, &len) == 0) {
+    *bytelen = len;
+    return true;
+  }
+  return false;
+}
+
+// Save list IDs for all NFA states of "prog" into "list".
+// Also reset the IDs to zero.
+// Only used for the recursive value lastlist[1].
+static void nfa_save_listids(nfa_regprog_T *prog, int *list)
+{
+  int i;
+  nfa_state_T *p;
+
+  // Order in the list is reverse, it's a bit faster that way.
+  p = &prog->state[0];
+  for (i = prog->nstate; --i >= 0;) {
+    list[i] = p->lastlist[1];
+    p->lastlist[1] = 0;
+    p++;
+  }
+}
+
+// Restore list IDs from "list" to all NFA states.
+static void nfa_restore_listids(nfa_regprog_T *prog, const int *list)
+{
+  int i;
+  nfa_state_T *p;
+
+  p = &prog->state[0];
+  for (i = prog->nstate; --i >= 0;) {
+    p->lastlist[1] = list[i];
+    p++;
+  }
+}
+
+static bool nfa_re_num_cmp(uintmax_t val, int op, uintmax_t pos)
+{
+  if (op == 1) {
+    return pos > val;
+  }
+  if (op == 2) {
+    return pos < val;
+  }
+  return val == pos;
+}
+
+// Recursively call nfa_regmatch()
+// "pim" is NULL or contains info about a Postponed Invisible Match (start
+// position).
+static int recursive_regmatch(nfa_state_T *state, nfa_pim_T *pim, nfa_regprog_T *prog,
+                              regsubs_T *submatch, regsubs_T *m, int **listids, int *listids_len)
+  FUNC_ATTR_NONNULL_ARG(1, 3, 5, 6, 7)
+{
+  const int save_reginput_col = (int)(rex.input - rex.line);
+  const int save_reglnum = rex.lnum;
+  const int save_nfa_match = nfa_match;
+  const int save_nfa_listid = rex.nfa_listid;
+  save_se_T *const save_nfa_endp = nfa_endp;
+  save_se_T endpos;
+  save_se_T *endposp = NULL;
+  int need_restore = false;
+
+  if (pim != NULL) {
+    // start at the position where the postponed match was
+    if (REG_MULTI) {
+      rex.input = rex.line + pim->end.pos.col;
+    } else {
+      rex.input = pim->end.ptr;
+    }
+  }
+
+  if (state->c == NFA_START_INVISIBLE_BEFORE
+      || state->c == NFA_START_INVISIBLE_BEFORE_FIRST
+      || state->c == NFA_START_INVISIBLE_BEFORE_NEG
+      || state->c == NFA_START_INVISIBLE_BEFORE_NEG_FIRST) {
+    // The recursive match must end at the current position. When "pim" is
+    // not NULL it specifies the current position.
+    endposp = &endpos;
+    if (REG_MULTI) {
+      if (pim == NULL) {
+        endpos.se_u.pos.col = (int)(rex.input - rex.line);
+        endpos.se_u.pos.lnum = rex.lnum;
+      } else {
+        endpos.se_u.pos = pim->end.pos;
+      }
+    } else {
+      if (pim == NULL) {
+        endpos.se_u.ptr = rex.input;
+      } else {
+        endpos.se_u.ptr = pim->end.ptr;
+      }
+    }
+
+    // Go back the specified number of bytes, or as far as the
+    // start of the previous line, to try matching "\@<=" or
+    // not matching "\@<!". This is very inefficient, limit the number of
+    // bytes if possible.
+    if (state->val <= 0) {
+      if (REG_MULTI) {
+        rex.line = (uint8_t *)reg_getline(--rex.lnum);
+        if (rex.line == NULL) {
+          // can't go before the first line
+          rex.line = (uint8_t *)reg_getline(++rex.lnum);
+        }
+      }
+      rex.input = rex.line;
+    } else {
+      if (REG_MULTI && (int)(rex.input - rex.line) < state->val) {
+        // Not enough bytes in this line, go to end of
+        // previous line.
+        rex.line = (uint8_t *)reg_getline(--rex.lnum);
+        if (rex.line == NULL) {
+          // can't go before the first line
+          rex.line = (uint8_t *)reg_getline(++rex.lnum);
+          rex.input = rex.line;
+        } else {
+          rex.input = rex.line + strlen((char *)rex.line);
+        }
+      }
+      if ((int)(rex.input - rex.line) >= state->val) {
+        rex.input -= state->val;
+        rex.input -= utf_head_off((char *)rex.line, (char *)rex.input);
+      } else {
+        rex.input = rex.line;
+      }
+    }
+  }
+
+#ifdef REGEXP_DEBUG
+  if (log_fd != stderr) {
+    fclose(log_fd);
+  }
+  log_fd = NULL;
+#endif
+  // Have to clear the lastlist field of the NFA nodes, so that
+  // nfa_regmatch() and addstate() can run properly after recursion.
+  if (nfa_ll_index == 1) {
+    // Already calling nfa_regmatch() recursively.  Save the lastlist[1]
+    // values and clear them.
+    if (*listids == NULL || *listids_len < prog->nstate) {
+      xfree(*listids);
+      *listids = xmalloc(sizeof(**listids) * (size_t)prog->nstate);
+      *listids_len = prog->nstate;
+    }
+    nfa_save_listids(prog, *listids);
+    need_restore = true;
+    // any value of rex.nfa_listid will do
+  } else {
+    // First recursive nfa_regmatch() call, switch to the second lastlist
+    // entry.  Make sure rex.nfa_listid is different from a previous
+    // recursive call, because some states may still have this ID.
+    nfa_ll_index++;
+    if (rex.nfa_listid <= rex.nfa_alt_listid) {
+      rex.nfa_listid = rex.nfa_alt_listid;
+    }
+  }
+
+  // Call nfa_regmatch() to check if the current concat matches at this
+  // position. The concat ends with the node NFA_END_INVISIBLE
+  nfa_endp = endposp;
+  const int result = nfa_regmatch(prog, state->out, submatch, m);
+
+  if (need_restore) {
+    nfa_restore_listids(prog, *listids);
+  } else {
+    nfa_ll_index--;
+    rex.nfa_alt_listid = rex.nfa_listid;
+  }
+
+  // restore position in input text
+  rex.lnum = save_reglnum;
+  if (REG_MULTI) {
+    rex.line = (uint8_t *)reg_getline(rex.lnum);
+  }
+  rex.input = rex.line + save_reginput_col;
+  if (result != NFA_TOO_EXPENSIVE) {
+    nfa_match = save_nfa_match;
+    rex.nfa_listid = save_nfa_listid;
+  }
+  nfa_endp = save_nfa_endp;
+
+#ifdef REGEXP_DEBUG
+  open_debug_log(result);
+#endif
+
+  return result;
+}
+
+// Estimate the chance of a match with "state" failing.
+// empty match: 0
+// NFA_ANY: 1
+// specific character: 99
+static int failure_chance(nfa_state_T *state, int depth)
+{
+  int c = state->c;
+  int l, r;
+
+  // detect looping
+  if (depth > 4) {
+    return 1;
+  }
+
+  switch (c) {
+  case NFA_SPLIT:
+    if (state->out->c == NFA_SPLIT || state->out1->c == NFA_SPLIT) {
+      // avoid recursive stuff
+      return 1;
+    }
+    // two alternatives, use the lowest failure chance
+    l = failure_chance(state->out, depth + 1);
+    r = failure_chance(state->out1, depth + 1);
+    return l < r ? l : r;
+
+  case NFA_ANY:
+    // matches anything, unlikely to fail
+    return 1;
+
+  case NFA_MATCH:
+  case NFA_MCLOSE:
+  case NFA_ANY_COMPOSING:
+    // empty match works always
+    return 0;
+
+  case NFA_START_INVISIBLE:
+  case NFA_START_INVISIBLE_FIRST:
+  case NFA_START_INVISIBLE_NEG:
+  case NFA_START_INVISIBLE_NEG_FIRST:
+  case NFA_START_INVISIBLE_BEFORE:
+  case NFA_START_INVISIBLE_BEFORE_FIRST:
+  case NFA_START_INVISIBLE_BEFORE_NEG:
+  case NFA_START_INVISIBLE_BEFORE_NEG_FIRST:
+  case NFA_START_PATTERN:
+    // recursive regmatch is expensive, use low failure chance
+    return 5;
+
+  case NFA_BOL:
+  case NFA_EOL:
+  case NFA_BOF:
+  case NFA_EOF:
+  case NFA_NEWL:
+    return 99;
+
+  case NFA_BOW:
+  case NFA_EOW:
+    return 90;
+
+  case NFA_MOPEN:
+  case NFA_MOPEN1:
+  case NFA_MOPEN2:
+  case NFA_MOPEN3:
+  case NFA_MOPEN4:
+  case NFA_MOPEN5:
+  case NFA_MOPEN6:
+  case NFA_MOPEN7:
+  case NFA_MOPEN8:
+  case NFA_MOPEN9:
+  case NFA_ZOPEN:
+  case NFA_ZOPEN1:
+  case NFA_ZOPEN2:
+  case NFA_ZOPEN3:
+  case NFA_ZOPEN4:
+  case NFA_ZOPEN5:
+  case NFA_ZOPEN6:
+  case NFA_ZOPEN7:
+  case NFA_ZOPEN8:
+  case NFA_ZOPEN9:
+  case NFA_ZCLOSE:
+  case NFA_ZCLOSE1:
+  case NFA_ZCLOSE2:
+  case NFA_ZCLOSE3:
+  case NFA_ZCLOSE4:
+  case NFA_ZCLOSE5:
+  case NFA_ZCLOSE6:
+  case NFA_ZCLOSE7:
+  case NFA_ZCLOSE8:
+  case NFA_ZCLOSE9:
+  case NFA_NOPEN:
+  case NFA_MCLOSE1:
+  case NFA_MCLOSE2:
+  case NFA_MCLOSE3:
+  case NFA_MCLOSE4:
+  case NFA_MCLOSE5:
+  case NFA_MCLOSE6:
+  case NFA_MCLOSE7:
+  case NFA_MCLOSE8:
+  case NFA_MCLOSE9:
+  case NFA_NCLOSE:
+    return failure_chance(state->out, depth + 1);
+
+  case NFA_BACKREF1:
+  case NFA_BACKREF2:
+  case NFA_BACKREF3:
+  case NFA_BACKREF4:
+  case NFA_BACKREF5:
+  case NFA_BACKREF6:
+  case NFA_BACKREF7:
+  case NFA_BACKREF8:
+  case NFA_BACKREF9:
+  case NFA_ZREF1:
+  case NFA_ZREF2:
+  case NFA_ZREF3:
+  case NFA_ZREF4:
+  case NFA_ZREF5:
+  case NFA_ZREF6:
+  case NFA_ZREF7:
+  case NFA_ZREF8:
+  case NFA_ZREF9:
+    // backreferences don't match in many places
+    return 94;
+
+  case NFA_LNUM_GT:
+  case NFA_LNUM_LT:
+  case NFA_COL_GT:
+  case NFA_COL_LT:
+  case NFA_VCOL_GT:
+  case NFA_VCOL_LT:
+  case NFA_MARK_GT:
+  case NFA_MARK_LT:
+  case NFA_VISUAL:
+    // before/after positions don't match very often
+    return 85;
+
+  case NFA_LNUM:
+    return 90;
+
+  case NFA_CURSOR:
+  case NFA_COL:
+  case NFA_VCOL:
+  case NFA_MARK:
+    // specific positions rarely match
+    return 98;
+
+  case NFA_COMPOSING:
+    return 95;
+
+  default:
+    if (c > 0) {
+      // character match fails often
+      return 95;
+    }
+  }
+
+  // something else, includes character classes
+  return 50;
+}
+
+// Skip until the char "c" we know a match must start with.
+static int skip_to_start(int c, colnr_T *colp)
+{
+  const uint8_t *const s = (uint8_t *)cstrchr((char *)rex.line + *colp, c);
+  if (s == NULL) {
+    return FAIL;
+  }
+  *colp = (int)(s - rex.line);
+  return OK;
+}
+
+// Check for a match with match_text.
+// Called after skip_to_start() has found regstart.
+// Returns zero for no match, 1 for a match.
+static int find_match_text(colnr_T *startcol, int regstart, uint8_t *match_text)
+{
+#define PTR2LEN(x) utf_ptr2len(x)
+
+  colnr_T col = *startcol;
+  int regstart_len = PTR2LEN((char *)rex.line + col);
+
+  while (true) {
+    bool match = true;
+    uint8_t *s1 = match_text;
+    uint8_t *s2 = rex.line + col + regstart_len;  // skip regstart
+    while (*s1) {
+      int c1_len = PTR2LEN((char *)s1);
+      int c1 = utf_ptr2char((char *)s1);
+      int c2_len = PTR2LEN((char *)s2);
+      int c2 = utf_ptr2char((char *)s2);
+
+      if ((c1 != c2 && (!rex.reg_ic || utf_fold(c1) != utf_fold(c2)))
+          || c1_len != c2_len) {
+        match = false;
+        break;
+      }
+      s1 += c1_len;
+      s2 += c2_len;
+    }
+    if (match
+        // check that no composing char follows
+        && !utf_iscomposing(utf_ptr2char((char *)s2))) {
+      cleanup_subexpr();
+      if (REG_MULTI) {
+        rex.reg_startpos[0].lnum = rex.lnum;
+        rex.reg_startpos[0].col = col;
+        rex.reg_endpos[0].lnum = rex.lnum;
+        rex.reg_endpos[0].col = (colnr_T)(s2 - rex.line);
+      } else {
+        rex.reg_startp[0] = rex.line + col;
+        rex.reg_endp[0] = s2;
+      }
+      *startcol = col;
+      return 1L;
+    }
+
+    // Try finding regstart after the current match.
+    col += regstart_len;  // skip regstart
+    if (skip_to_start(regstart, &col) == FAIL) {
+      break;
+    }
+  }
+
+  *startcol = col;
+  return 0L;
+
+#undef PTR2LEN
+}
+
+static int nfa_did_time_out(void)
+{
+  if (nfa_time_limit != NULL && profile_passed_limit(*nfa_time_limit)) {
+    if (nfa_timed_out != NULL) {
+      *nfa_timed_out = true;
+    }
+    return true;
+  }
+  return false;
+}
+
+/// Main matching routine.
+///
+/// Run NFA to determine whether it matches rex.input.
+///
+/// When "nfa_endp" is not NULL it is a required end-of-match position.
+///
+/// Return true if there is a match, false if there is no match,
+/// NFA_TOO_EXPENSIVE if we end up with too many states.
+/// When there is a match "submatch" contains the positions.
+///
+/// Note: Caller must ensure that: start != NULL.
+static int nfa_regmatch(nfa_regprog_T *prog, nfa_state_T *start, regsubs_T *submatch, regsubs_T *m)
+  FUNC_ATTR_NONNULL_ARG(1, 2, 4)
+{
+  int result = false;
+  int flag = 0;
+  bool go_to_nextline = false;
+  nfa_thread_T *t;
+  nfa_list_T list[2];
+  int listidx;
+  nfa_list_T *thislist;
+  nfa_list_T *nextlist;
+  int *listids = NULL;
+  int listids_len = 0;
+  nfa_state_T *add_state;
+  bool add_here;
+  int add_count;
+  int add_off = 0;
+  int toplevel = start->c == NFA_MOPEN;
+  regsubs_T *r;
+  // Some patterns may take a long time to match, especially when using
+  // recursive_regmatch(). Allow interrupting them with CTRL-C.
+  reg_breakcheck();
+  if (got_int) {
+    return false;
+  }
+  if (nfa_did_time_out()) {
+    return false;
+  }
+
+#ifdef NFA_REGEXP_DEBUG_LOG
+  FILE *debug = fopen(NFA_REGEXP_DEBUG_LOG, "a");
+
+  if (debug == NULL) {
+    semsg("(NFA) COULD NOT OPEN %s!", NFA_REGEXP_DEBUG_LOG);
+    return false;
+  }
+#endif
+  nfa_match = false;
+
+  // Allocate memory for the lists of nodes.
+  size_t size = (size_t)(prog->nstate + 1) * sizeof(nfa_thread_T);
+  list[0].t = xmalloc(size);
+  list[0].len = prog->nstate + 1;
+  list[1].t = xmalloc(size);
+  list[1].len = prog->nstate + 1;
+
+#ifdef REGEXP_DEBUG
+  log_fd = fopen(NFA_REGEXP_RUN_LOG, "a");
+  if (log_fd == NULL) {
+    emsg(_(e_log_open_failed));
+    log_fd = stderr;
+  }
+  fprintf(log_fd, "**********************************\n");
+  nfa_set_code(start->c);
+  fprintf(log_fd, " RUNNING nfa_regmatch() starting with state %d, code %s\n",
+          abs(start->id), code);
+  fprintf(log_fd, "**********************************\n");
+#endif
+
+  thislist = &list[0];
+  thislist->n = 0;
+  thislist->has_pim = false;
+  nextlist = &list[1];
+  nextlist->n = 0;
+  nextlist->has_pim = false;
+#ifdef REGEXP_DEBUG
+  fprintf(log_fd, "(---) STARTSTATE first\n");
+#endif
+  thislist->id = rex.nfa_listid + 1;
+
+  // Inline optimized code for addstate(thislist, start, m, 0) if we know
+  // it's the first MOPEN.
+  if (toplevel) {
+    if (REG_MULTI) {
+      m->norm.list.multi[0].start_lnum = rex.lnum;
+      m->norm.list.multi[0].start_col = (colnr_T)(rex.input - rex.line);
+      m->norm.orig_start_col = m->norm.list.multi[0].start_col;
+    } else {
+      m->norm.list.line[0].start = rex.input;
+    }
+    m->norm.in_use = 1;
+    r = addstate(thislist, start->out, m, NULL, 0);
+  } else {
+    r = addstate(thislist, start, m, NULL, 0);
+  }
+  if (r == NULL) {
+    nfa_match = NFA_TOO_EXPENSIVE;
+    goto theend;
+  }
+
+#define ADD_STATE_IF_MATCH(state) \
+  if (result) { \
+    add_state = (state)->out; \
+    add_off = clen; \
+  }
+
+  // Run for each character.
+  while (true) {
+    int curc = utf_ptr2char((char *)rex.input);
+    int clen = utfc_ptr2len((char *)rex.input);
+    if (curc == NUL) {
+      clen = 0;
+      go_to_nextline = false;
+    }
+
+    // swap lists
+    thislist = &list[flag];
+    nextlist = &list[flag ^= 1];
+    nextlist->n = 0;                // clear nextlist
+    nextlist->has_pim = false;
+    rex.nfa_listid++;
+    if (prog->re_engine == AUTOMATIC_ENGINE
+        && (rex.nfa_listid >= NFA_MAX_STATES)) {
+      // Too many states, retry with old engine.
+      nfa_match = NFA_TOO_EXPENSIVE;
+      goto theend;
+    }
+
+    thislist->id = rex.nfa_listid;
+    nextlist->id = rex.nfa_listid + 1;
+
+#ifdef REGEXP_DEBUG
+    fprintf(log_fd, "------------------------------------------\n");
+    fprintf(log_fd, ">>> Reginput is \"%s\"\n", rex.input);
+    fprintf(log_fd,
+            ">>> Advanced one character... Current char is %c (code %d) \n",
+            curc,
+            (int)curc);
+    fprintf(log_fd, ">>> Thislist has %d states available: ", thislist->n);
+    {
+      int i;
+
+      for (i = 0; i < thislist->n; i++) {
+        fprintf(log_fd, "%d  ", abs(thislist->t[i].state->id));
+      }
+    }
+    fprintf(log_fd, "\n");
+#endif
+
+#ifdef NFA_REGEXP_DEBUG_LOG
+    fprintf(debug, "\n-------------------\n");
+#endif
+    // If the state lists are empty we can stop.
+    if (thislist->n == 0) {
+      break;
+    }
+
+    // compute nextlist
+    for (listidx = 0; listidx < thislist->n; listidx++) {
+      // If the list gets very long there probably is something wrong.
+      // At least allow interrupting with CTRL-C.
+      reg_breakcheck();
+      if (got_int) {
+        break;
+      }
+      if (nfa_time_limit != NULL && ++nfa_time_count == 20) {
+        nfa_time_count = 0;
+        if (nfa_did_time_out()) {
+          break;
+        }
+      }
+      t = &thislist->t[listidx];
+
+#ifdef NFA_REGEXP_DEBUG_LOG
+      nfa_set_code(t->state->c);
+      fprintf(debug, "%s, ", code);
+#endif
+#ifdef REGEXP_DEBUG
+      {
+        int col;
+
+        if (t->subs.norm.in_use <= 0) {
+          col = -1;
+        } else if (REG_MULTI) {
+          col = t->subs.norm.list.multi[0].start_col;
+        } else {
+          col = (int)(t->subs.norm.list.line[0].start - rex.line);
+        }
+        nfa_set_code(t->state->c);
+        fprintf(log_fd, "(%d) char %d %s (start col %d)%s... \n",
+                abs(t->state->id), (int)t->state->c, code, col,
+                pim_info(&t->pim));
+      }
+#endif
+
+      // Handle the possible codes of the current state.
+      // The most important is NFA_MATCH.
+      add_state = NULL;
+      add_here = false;
+      add_count = 0;
+      switch (t->state->c) {
+      case NFA_MATCH:
+        // If the match is not at the start of the line, ends before a
+        // composing characters and rex.reg_icombine is not set, that
+        // is not really a match.
+        if (!rex.reg_icombine
+            && rex.input != rex.line
+            && utf_iscomposing(curc)) {
+          break;
+        }
+        nfa_match = true;
+        copy_sub(&submatch->norm, &t->subs.norm);
+        if (rex.nfa_has_zsubexpr) {
+          copy_sub(&submatch->synt, &t->subs.synt);
+        }
+#ifdef REGEXP_DEBUG
+        log_subsexpr(&t->subs);
+#endif
+        // Found the left-most longest match, do not look at any other
+        // states at this position.  When the list of states is going
+        // to be empty quit without advancing, so that "rex.input" is
+        // correct.
+        if (nextlist->n == 0) {
+          clen = 0;
+        }
+        goto nextchar;
+
+      case NFA_END_INVISIBLE:
+      case NFA_END_INVISIBLE_NEG:
+      case NFA_END_PATTERN:
+        // This is only encountered after a NFA_START_INVISIBLE or
+        // NFA_START_INVISIBLE_BEFORE node.
+        // They surround a zero-width group, used with "\@=", "\&",
+        // "\@!", "\@<=" and "\@<!".
+        // If we got here, it means that the current "invisible" group
+        // finished successfully, so return control to the parent
+        // nfa_regmatch().  For a look-behind match only when it ends
+        // in the position in "nfa_endp".
+        // Submatches are stored in *m, and used in the parent call.
+#ifdef REGEXP_DEBUG
+        if (nfa_endp != NULL) {
+          if (REG_MULTI) {
+            fprintf(log_fd,
+                    "Current lnum: %d, endp lnum: %d;"
+                    " current col: %d, endp col: %d\n",
+                    (int)rex.lnum,
+                    (int)nfa_endp->se_u.pos.lnum,
+                    (int)(rex.input - rex.line),
+                    nfa_endp->se_u.pos.col);
+          } else {
+            fprintf(log_fd, "Current col: %d, endp col: %d\n",
+                    (int)(rex.input - rex.line),
+                    (int)(nfa_endp->se_u.ptr - rex.input));
+          }
+        }
+#endif
+        // If "nfa_endp" is set it's only a match if it ends at
+        // "nfa_endp"
+        if (nfa_endp != NULL
+            && (REG_MULTI
+                ? (rex.lnum != nfa_endp->se_u.pos.lnum
+                   || (int)(rex.input - rex.line) != nfa_endp->se_u.pos.col)
+                : rex.input != nfa_endp->se_u.ptr)) {
+          break;
+        }
+        // do not set submatches for \@!
+        if (t->state->c != NFA_END_INVISIBLE_NEG) {
+          copy_sub(&m->norm, &t->subs.norm);
+          if (rex.nfa_has_zsubexpr) {
+            copy_sub(&m->synt, &t->subs.synt);
+          }
+        }
+#ifdef REGEXP_DEBUG
+        fprintf(log_fd, "Match found:\n");
+        log_subsexpr(m);
+#endif
+        nfa_match = true;
+        // See comment above at "goto nextchar".
+        if (nextlist->n == 0) {
+          clen = 0;
+        }
+        goto nextchar;
+
+      case NFA_START_INVISIBLE:
+      case NFA_START_INVISIBLE_FIRST:
+      case NFA_START_INVISIBLE_NEG:
+      case NFA_START_INVISIBLE_NEG_FIRST:
+      case NFA_START_INVISIBLE_BEFORE:
+      case NFA_START_INVISIBLE_BEFORE_FIRST:
+      case NFA_START_INVISIBLE_BEFORE_NEG:
+      case NFA_START_INVISIBLE_BEFORE_NEG_FIRST:
+#ifdef REGEXP_DEBUG
+        fprintf(log_fd, "Failure chance invisible: %d, what follows: %d\n",
+                failure_chance(t->state->out, 0),
+                failure_chance(t->state->out1->out, 0));
+#endif
+        // Do it directly if there already is a PIM or when
+        // nfa_postprocess() detected it will work better.
+        if (t->pim.result != NFA_PIM_UNUSED
+            || t->state->c == NFA_START_INVISIBLE_FIRST
+            || t->state->c == NFA_START_INVISIBLE_NEG_FIRST
+            || t->state->c == NFA_START_INVISIBLE_BEFORE_FIRST
+            || t->state->c == NFA_START_INVISIBLE_BEFORE_NEG_FIRST) {
+          int in_use = m->norm.in_use;
+
+          // Copy submatch info for the recursive call, opposite
+          // of what happens on success below.
+          copy_sub_off(&m->norm, &t->subs.norm);
+          if (rex.nfa_has_zsubexpr) {
+            copy_sub_off(&m->synt, &t->subs.synt);
+          }
+          // First try matching the invisible match, then what
+          // follows.
+          result = recursive_regmatch(t->state, NULL, prog, submatch, m,
+                                      &listids, &listids_len);
+          if (result == NFA_TOO_EXPENSIVE) {
+            nfa_match = result;
+            goto theend;
+          }
+
+          // for \@! and \@<! it is a match when the result is
+          // false
+          if (result != (t->state->c == NFA_START_INVISIBLE_NEG
+                         || t->state->c == NFA_START_INVISIBLE_NEG_FIRST
+                         || t->state->c
+                         == NFA_START_INVISIBLE_BEFORE_NEG
+                         || t->state->c
+                         == NFA_START_INVISIBLE_BEFORE_NEG_FIRST)) {
+            // Copy submatch info from the recursive call
+            copy_sub_off(&t->subs.norm, &m->norm);
+            if (rex.nfa_has_zsubexpr) {
+              copy_sub_off(&t->subs.synt, &m->synt);
+            }
+            // If the pattern has \ze and it matched in the
+            // sub pattern, use it.
+            copy_ze_off(&t->subs.norm, &m->norm);
+
+            // t->state->out1 is the corresponding
+            // END_INVISIBLE node; Add its out to the current
+            // list (zero-width match).
+            add_here = true;
+            add_state = t->state->out1->out;
+          }
+          m->norm.in_use = in_use;
+        } else {
+          nfa_pim_T pim;
+
+          // First try matching what follows.  Only if a match
+          // is found verify the invisible match matches.  Add a
+          // nfa_pim_T to the following states, it contains info
+          // about the invisible match.
+          pim.state = t->state;
+          pim.result = NFA_PIM_TODO;
+          pim.subs.norm.in_use = 0;
+          pim.subs.synt.in_use = 0;
+          if (REG_MULTI) {
+            pim.end.pos.col = (int)(rex.input - rex.line);
+            pim.end.pos.lnum = rex.lnum;
+          } else {
+            pim.end.ptr = rex.input;
+          }
+          // t->state->out1 is the corresponding END_INVISIBLE
+          // node; Add its out to the current list (zero-width
+          // match).
+          if (addstate_here(thislist, t->state->out1->out, &t->subs,
+                            &pim, &listidx) == NULL) {
+            nfa_match = NFA_TOO_EXPENSIVE;
+            goto theend;
+          }
+        }
+        break;
+
+      case NFA_START_PATTERN: {
+        nfa_state_T *skip = NULL;
+#ifdef REGEXP_DEBUG
+        int skip_lid = 0;
+#endif
+
+        // There is no point in trying to match the pattern if the
+        // output state is not going to be added to the list.
+        if (state_in_list(nextlist, t->state->out1->out, &t->subs)) {
+          skip = t->state->out1->out;
+#ifdef REGEXP_DEBUG
+          skip_lid = nextlist->id;
+#endif
+        } else if (state_in_list(nextlist,
+                                 t->state->out1->out->out, &t->subs)) {
+          skip = t->state->out1->out->out;
+#ifdef REGEXP_DEBUG
+          skip_lid = nextlist->id;
+#endif
+        } else if (state_in_list(thislist,
+                                 t->state->out1->out->out, &t->subs)) {
+          skip = t->state->out1->out->out;
+#ifdef REGEXP_DEBUG
+          skip_lid = thislist->id;
+#endif
+        }
+        if (skip != NULL) {
+#ifdef REGEXP_DEBUG
+          nfa_set_code(skip->c);
+          fprintf(log_fd,
+                  "> Not trying to match pattern, output state %d is already in list %d. char %d: %s\n",
+                  abs(skip->id), skip_lid, skip->c, code);
+#endif
+          break;
+        }
+        // Copy submatch info to the recursive call, opposite of what
+        // happens afterwards.
+        copy_sub_off(&m->norm, &t->subs.norm);
+        if (rex.nfa_has_zsubexpr) {
+          copy_sub_off(&m->synt, &t->subs.synt);
+        }
+
+        // First try matching the pattern.
+        result = recursive_regmatch(t->state, NULL, prog, submatch, m,
+                                    &listids, &listids_len);
+        if (result == NFA_TOO_EXPENSIVE) {
+          nfa_match = result;
+          goto theend;
+        }
+        if (result) {
+          int bytelen;
+
+#ifdef REGEXP_DEBUG
+          fprintf(log_fd, "NFA_START_PATTERN matches:\n");
+          log_subsexpr(m);
+#endif
+          // Copy submatch info from the recursive call
+          copy_sub_off(&t->subs.norm, &m->norm);
+          if (rex.nfa_has_zsubexpr) {
+            copy_sub_off(&t->subs.synt, &m->synt);
+          }
+          // Now we need to skip over the matched text and then
+          // continue with what follows.
+          if (REG_MULTI) {
+            // TODO(RE): multi-line match
+            bytelen = m->norm.list.multi[0].end_col
+                      - (int)(rex.input - rex.line);
+          } else {
+            bytelen = (int)(m->norm.list.line[0].end - rex.input);
+          }
+
+#ifdef REGEXP_DEBUG
+          fprintf(log_fd, "NFA_START_PATTERN length: %d\n", bytelen);
+#endif
+          if (bytelen == 0) {
+            // empty match, output of corresponding
+            // NFA_END_PATTERN/NFA_SKIP to be used at current
+            // position
+            add_here = true;
+            add_state = t->state->out1->out->out;
+          } else if (bytelen <= clen) {
+            // match current character, output of corresponding
+            // NFA_END_PATTERN to be used at next position.
+            add_state = t->state->out1->out->out;
+            add_off = clen;
+          } else {
+            // skip over the matched characters, set character
+            // count in NFA_SKIP
+            add_state = t->state->out1->out;
+            add_off = bytelen;
+            add_count = bytelen - clen;
+          }
+        }
+        break;
+      }
+
+      case NFA_BOL:
+        if (rex.input == rex.line) {
+          add_here = true;
+          add_state = t->state->out;
+        }
+        break;
+
+      case NFA_EOL:
+        if (curc == NUL) {
+          add_here = true;
+          add_state = t->state->out;
+        }
+        break;
+
+      case NFA_BOW:
+        result = true;
+
+        if (curc == NUL) {
+          result = false;
+        } else {
+          int this_class;
+
+          // Get class of current and previous char (if it exists).
+          this_class = mb_get_class_tab((char *)rex.input, rex.reg_buf->b_chartab);
+          if (this_class <= 1) {
+            result = false;
+          } else if (reg_prev_class() == this_class) {
+            result = false;
+          }
+        }
+        if (result) {
+          add_here = true;
+          add_state = t->state->out;
+        }
+        break;
+
+      case NFA_EOW:
+        result = true;
+        if (rex.input == rex.line) {
+          result = false;
+        } else {
+          int this_class, prev_class;
+
+          // Get class of current and previous char (if it exists).
+          this_class = mb_get_class_tab((char *)rex.input, rex.reg_buf->b_chartab);
+          prev_class = reg_prev_class();
+          if (this_class == prev_class
+              || prev_class == 0 || prev_class == 1) {
+            result = false;
+          }
+        }
+        if (result) {
+          add_here = true;
+          add_state = t->state->out;
+        }
+        break;
+
+      case NFA_BOF:
+        if (rex.lnum == 0 && rex.input == rex.line
+            && (!REG_MULTI || rex.reg_firstlnum == 1)) {
+          add_here = true;
+          add_state = t->state->out;
+        }
+        break;
+
+      case NFA_EOF:
+        if (rex.lnum == rex.reg_maxline && curc == NUL) {
+          add_here = true;
+          add_state = t->state->out;
+        }
+        break;
+
+      case NFA_COMPOSING: {
+        int mc = curc;
+        int len = 0;
+        nfa_state_T *end;
+        nfa_state_T *sta;
+        int cchars[MAX_MCO];
+        int ccount = 0;
+        int j;
+
+        sta = t->state->out;
+        len = 0;
+        if (utf_iscomposing(sta->c)) {
+          // Only match composing character(s), ignore base
+          // character.  Used for ".{composing}" and "{composing}"
+          // (no preceding character).
+          len += utf_char2len(mc);
+        }
+        if (rex.reg_icombine && len == 0) {
+          // If \Z was present, then ignore composing characters.
+          // When ignoring the base character this always matches.
+          if (sta->c != curc) {
+            result = FAIL;
+          } else {
+            result = OK;
+          }
+          while (sta->c != NFA_END_COMPOSING) {
+            sta = sta->out;
+          }
+        } else if (len > 0 || mc == sta->c) {
+          // Check base character matches first, unless ignored.
+          if (len == 0) {
+            len += utf_char2len(mc);
+            sta = sta->out;
+          }
+
+          // We don't care about the order of composing characters.
+          // Get them into cchars[] first.
+          while (len < clen) {
+            mc = utf_ptr2char((char *)rex.input + len);
+            cchars[ccount++] = mc;
+            len += utf_char2len(mc);
+            if (ccount == MAX_MCO) {
+              break;
+            }
+          }
+
+          // Check that each composing char in the pattern matches a
+          // composing char in the text.  We do not check if all
+          // composing chars are matched.
+          result = OK;
+          while (sta->c != NFA_END_COMPOSING) {
+            for (j = 0; j < ccount; j++) {
+              if (cchars[j] == sta->c) {
+                break;
+              }
+            }
+            if (j == ccount) {
+              result = FAIL;
+              break;
+            }
+            sta = sta->out;
+          }
+        } else {
+          result = FAIL;
+        }
+
+        end = t->state->out1;               // NFA_END_COMPOSING
+        ADD_STATE_IF_MATCH(end);
+        break;
+      }
+
+      case NFA_NEWL:
+        if (curc == NUL && !rex.reg_line_lbr && REG_MULTI
+            && rex.lnum <= rex.reg_maxline) {
+          go_to_nextline = true;
+          // Pass -1 for the offset, which means taking the position
+          // at the start of the next line.
+          add_state = t->state->out;
+          add_off = -1;
+        } else if (curc == '\n' && rex.reg_line_lbr) {
+          // match \n as if it is an ordinary character
+          add_state = t->state->out;
+          add_off = 1;
+        }
+        break;
+
+      case NFA_START_COLL:
+      case NFA_START_NEG_COLL: {
+        // What follows is a list of characters, until NFA_END_COLL.
+        // One of them must match or none of them must match.
+        nfa_state_T *state;
+        int result_if_matched;
+        int c1, c2;
+
+        // Never match EOL. If it's part of the collection it is added
+        // as a separate state with an OR.
+        if (curc == NUL) {
+          break;
+        }
+
+        state = t->state->out;
+        result_if_matched = (t->state->c == NFA_START_COLL);
+        while (true) {
+          if (state->c == NFA_END_COLL) {
+            result = !result_if_matched;
+            break;
+          }
+          if (state->c == NFA_RANGE_MIN) {
+            c1 = state->val;
+            state = state->out;             // advance to NFA_RANGE_MAX
+            c2 = state->val;
+#ifdef REGEXP_DEBUG
+            fprintf(log_fd, "NFA_RANGE_MIN curc=%d c1=%d c2=%d\n",
+                    curc, c1, c2);
+#endif
+            if (curc >= c1 && curc <= c2) {
+              result = result_if_matched;
+              break;
+            }
+            if (rex.reg_ic) {
+              int curc_low = utf_fold(curc);
+              int done = false;
+
+              for (; c1 <= c2; c1++) {
+                if (utf_fold(c1) == curc_low) {
+                  result = result_if_matched;
+                  done = true;
+                  break;
+                }
+              }
+              if (done) {
+                break;
+              }
+            }
+          } else if (state->c < 0 ? check_char_class(state->c, curc)
+                                  : (curc == state->c
+                                     || (rex.reg_ic
+                                         && utf_fold(curc) == utf_fold(state->c)))) {
+            result = result_if_matched;
+            break;
+          }
+          state = state->out;
+        }
+        if (result) {
+          // next state is in out of the NFA_END_COLL, out1 of
+          // START points to the END state
+          add_state = t->state->out1->out;
+          add_off = clen;
+        }
+        break;
+      }
+
+      case NFA_ANY:
+        // Any char except '\0', (end of input) does not match.
+        if (curc > 0) {
+          add_state = t->state->out;
+          add_off = clen;
+        }
+        break;
+
+      case NFA_ANY_COMPOSING:
+        // On a composing character skip over it.  Otherwise do
+        // nothing.  Always matches.
+        if (utf_iscomposing(curc)) {
+          add_off = clen;
+        } else {
+          add_here = true;
+          add_off = 0;
+        }
+        add_state = t->state->out;
+        break;
+
+      // Character classes like \a for alpha, \d for digit etc.
+      case NFA_IDENT:           //  \i
+        result = vim_isIDc(curc);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_SIDENT:          //  \I
+        result = !ascii_isdigit(curc) && vim_isIDc(curc);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_KWORD:           //  \k
+        result = vim_iswordp_buf((char *)rex.input, rex.reg_buf);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_SKWORD:          //  \K
+        result = !ascii_isdigit(curc)
+                 && vim_iswordp_buf((char *)rex.input, rex.reg_buf);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_FNAME:           //  \f
+        result = vim_isfilec(curc);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_SFNAME:          //  \F
+        result = !ascii_isdigit(curc) && vim_isfilec(curc);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_PRINT:           //  \p
+        result = vim_isprintc(utf_ptr2char((char *)rex.input));
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_SPRINT:          //  \P
+        result = !ascii_isdigit(curc) && vim_isprintc(utf_ptr2char((char *)rex.input));
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_WHITE:           //  \s
+        result = ascii_iswhite(curc);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_NWHITE:          //  \S
+        result = curc != NUL && !ascii_iswhite(curc);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_DIGIT:           //  \d
+        result = ri_digit(curc);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_NDIGIT:          //  \D
+        result = curc != NUL && !ri_digit(curc);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_HEX:             //  \x
+        result = ri_hex(curc);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_NHEX:            //  \X
+        result = curc != NUL && !ri_hex(curc);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_OCTAL:           //  \o
+        result = ri_octal(curc);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_NOCTAL:          //  \O
+        result = curc != NUL && !ri_octal(curc);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_WORD:            //  \w
+        result = ri_word(curc);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_NWORD:           //  \W
+        result = curc != NUL && !ri_word(curc);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_HEAD:            //  \h
+        result = ri_head(curc);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_NHEAD:           //  \H
+        result = curc != NUL && !ri_head(curc);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_ALPHA:           //  \a
+        result = ri_alpha(curc);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_NALPHA:          //  \A
+        result = curc != NUL && !ri_alpha(curc);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_LOWER:           //  \l
+        result = ri_lower(curc);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_NLOWER:          //  \L
+        result = curc != NUL && !ri_lower(curc);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_UPPER:           //  \u
+        result = ri_upper(curc);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_NUPPER:          // \U
+        result = curc != NUL && !ri_upper(curc);
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_LOWER_IC:        // [a-z]
+        result = ri_lower(curc) || (rex.reg_ic && ri_upper(curc));
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_NLOWER_IC:       // [^a-z]
+        result = curc != NUL
+                 && !(ri_lower(curc) || (rex.reg_ic && ri_upper(curc)));
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_UPPER_IC:        // [A-Z]
+        result = ri_upper(curc) || (rex.reg_ic && ri_lower(curc));
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_NUPPER_IC:       // [^A-Z]
+        result = curc != NUL
+                 && !(ri_upper(curc) || (rex.reg_ic && ri_lower(curc)));
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+
+      case NFA_BACKREF1:
+      case NFA_BACKREF2:
+      case NFA_BACKREF3:
+      case NFA_BACKREF4:
+      case NFA_BACKREF5:
+      case NFA_BACKREF6:
+      case NFA_BACKREF7:
+      case NFA_BACKREF8:
+      case NFA_BACKREF9:
+      case NFA_ZREF1:
+      case NFA_ZREF2:
+      case NFA_ZREF3:
+      case NFA_ZREF4:
+      case NFA_ZREF5:
+      case NFA_ZREF6:
+      case NFA_ZREF7:
+      case NFA_ZREF8:
+      case NFA_ZREF9:
+        // \1 .. \9  \z1 .. \z9
+      {
+        int subidx;
+        int bytelen;
+
+        if (t->state->c <= NFA_BACKREF9) {
+          subidx = t->state->c - NFA_BACKREF1 + 1;
+          result = match_backref(&t->subs.norm, subidx, &bytelen);
+        } else {
+          subidx = t->state->c - NFA_ZREF1 + 1;
+          result = match_zref(subidx, &bytelen);
+        }
+
+        if (result) {
+          if (bytelen == 0) {
+            // empty match always works, output of NFA_SKIP to be
+            // used next
+            add_here = true;
+            add_state = t->state->out->out;
+          } else if (bytelen <= clen) {
+            // match current character, jump ahead to out of
+            // NFA_SKIP
+            add_state = t->state->out->out;
+            add_off = clen;
+          } else {
+            // skip over the matched characters, set character
+            // count in NFA_SKIP
+            add_state = t->state->out;
+            add_off = bytelen;
+            add_count = bytelen - clen;
+          }
+        }
+        break;
+      }
+      case NFA_SKIP:
+        // character of previous matching \1 .. \9  or \@>
+        if (t->count - clen <= 0) {
+          // end of match, go to what follows
+          add_state = t->state->out;
+          add_off = clen;
+        } else {
+          // add state again with decremented count
+          add_state = t->state;
+          add_off = 0;
+          add_count = t->count - clen;
+        }
+        break;
+
+      case NFA_LNUM:
+      case NFA_LNUM_GT:
+      case NFA_LNUM_LT:
+        assert(t->state->val >= 0
+               && !((rex.reg_firstlnum > 0
+                     && rex.lnum > LONG_MAX - rex.reg_firstlnum)
+                    || (rex.reg_firstlnum < 0
+                        && rex.lnum < LONG_MIN + rex.reg_firstlnum))
+               && rex.lnum + rex.reg_firstlnum >= 0);
+        result = (REG_MULTI
+                  && nfa_re_num_cmp((uintmax_t)t->state->val,
+                                    t->state->c - NFA_LNUM,
+                                    (uintmax_t)rex.lnum + (uintmax_t)rex.reg_firstlnum));
+        if (result) {
+          add_here = true;
+          add_state = t->state->out;
+        }
+        break;
+
+      case NFA_COL:
+      case NFA_COL_GT:
+      case NFA_COL_LT:
+        assert(t->state->val >= 0
+               && rex.input >= rex.line
+               && (uintmax_t)(rex.input - rex.line) <= UINTMAX_MAX - 1);
+        result = nfa_re_num_cmp((uintmax_t)t->state->val,
+                                t->state->c - NFA_COL,
+                                (uintmax_t)(rex.input - rex.line + 1));
+        if (result) {
+          add_here = true;
+          add_state = t->state->out;
+        }
+        break;
+
+      case NFA_VCOL:
+      case NFA_VCOL_GT:
+      case NFA_VCOL_LT: {
+        int op = t->state->c - NFA_VCOL;
+        colnr_T col = (colnr_T)(rex.input - rex.line);
+
+        // Bail out quickly when there can't be a match, avoid the overhead of
+        // win_linetabsize() on long lines.
+        if (op != 1 && col > t->state->val * MB_MAXBYTES) {
+          break;
+        }
+
+        result = false;
+        win_T *wp = rex.reg_win == NULL ? curwin : rex.reg_win;
+        if (op == 1 && col - 1 > t->state->val && col > 100) {
+          int64_t ts = (int64_t)wp->w_buffer->b_p_ts;
+
+          // Guess that a character won't use more columns than 'tabstop',
+          // with a minimum of 4.
+          if (ts < 4) {
+            ts = 4;
+          }
+          result = col > t->state->val * ts;
+        }
+        if (!result) {
+          int lts = win_linetabsize(wp, rex.reg_firstlnum + rex.lnum, (char *)rex.line, col);
+          assert(t->state->val >= 0);
+          result = nfa_re_num_cmp((uintmax_t)t->state->val, op, (uintmax_t)lts + 1);
+        }
+        if (result) {
+          add_here = true;
+          add_state = t->state->out;
+        }
+      }
+      break;
+
+      case NFA_MARK:
+      case NFA_MARK_GT:
+      case NFA_MARK_LT: {
+        size_t col = REG_MULTI ? (size_t)(rex.input - rex.line) : 0;
+        fmark_T *fm = mark_get(rex.reg_buf, curwin, NULL, kMarkBufLocal, t->state->val);
+
+        // Line may have been freed, get it again.
+        if (REG_MULTI) {
+          rex.line = (uint8_t *)reg_getline(rex.lnum);
+          rex.input = rex.line + col;
+        }
+
+        // Compare the mark position to the match position, if the mark
+        // exists and mark is set in reg_buf.
+        if (fm != NULL && fm->mark.lnum > 0) {
+          pos_T *pos = &fm->mark;
+          const colnr_T pos_col = pos->lnum == rex.lnum + rex.reg_firstlnum
+                                  && pos->col == MAXCOL
+                                  ? (colnr_T)strlen(reg_getline(pos->lnum - rex.reg_firstlnum))
+                                  : pos->col;
+
+          result = pos->lnum == rex.lnum + rex.reg_firstlnum
+                   ? (pos_col == (colnr_T)(rex.input - rex.line)
+                      ? t->state->c == NFA_MARK
+                      : (pos_col < (colnr_T)(rex.input - rex.line)
+                         ? t->state->c == NFA_MARK_GT
+                         : t->state->c == NFA_MARK_LT))
+                   : (pos->lnum < rex.lnum + rex.reg_firstlnum
+                      ? t->state->c == NFA_MARK_GT
+                      : t->state->c == NFA_MARK_LT);
+          if (result) {
+            add_here = true;
+            add_state = t->state->out;
+          }
+        }
+        break;
+      }
+
+      case NFA_CURSOR:
+        result = rex.reg_win != NULL
+                 && (rex.lnum + rex.reg_firstlnum == rex.reg_win->w_cursor.lnum)
+                 && ((colnr_T)(rex.input - rex.line) == rex.reg_win->w_cursor.col);
+        if (result) {
+          add_here = true;
+          add_state = t->state->out;
+        }
+        break;
+
+      case NFA_VISUAL:
+        result = reg_match_visual();
+        if (result) {
+          add_here = true;
+          add_state = t->state->out;
+        }
+        break;
+
+      case NFA_MOPEN1:
+      case NFA_MOPEN2:
+      case NFA_MOPEN3:
+      case NFA_MOPEN4:
+      case NFA_MOPEN5:
+      case NFA_MOPEN6:
+      case NFA_MOPEN7:
+      case NFA_MOPEN8:
+      case NFA_MOPEN9:
+      case NFA_ZOPEN:
+      case NFA_ZOPEN1:
+      case NFA_ZOPEN2:
+      case NFA_ZOPEN3:
+      case NFA_ZOPEN4:
+      case NFA_ZOPEN5:
+      case NFA_ZOPEN6:
+      case NFA_ZOPEN7:
+      case NFA_ZOPEN8:
+      case NFA_ZOPEN9:
+      case NFA_NOPEN:
+      case NFA_ZSTART:
+        // These states are only added to be able to bail out when
+        // they are added again, nothing is to be done.
+        break;
+
+      default:          // regular character
+      {
+        int c = t->state->c;
+
+#ifdef REGEXP_DEBUG
+        if (c < 0) {
+          siemsg("INTERNAL: Negative state char: %" PRId64, (int64_t)c);
+        }
+#endif
+        result = (c == curc);
+
+        if (!result && rex.reg_ic) {
+          result = utf_fold(c) == utf_fold(curc);
+        }
+
+        // If rex.reg_icombine is not set only skip over the character
+        // itself.  When it is set skip over composing characters.
+        if (result && !rex.reg_icombine) {
+          clen = utf_ptr2len((char *)rex.input);
+        }
+
+        ADD_STATE_IF_MATCH(t->state);
+        break;
+      }
+      }       // switch (t->state->c)
+
+      if (add_state != NULL) {
+        nfa_pim_T *pim;
+        nfa_pim_T pim_copy;
+
+        if (t->pim.result == NFA_PIM_UNUSED) {
+          pim = NULL;
+        } else {
+          pim = &t->pim;
+        }
+
+        // Handle the postponed invisible match if the match might end
+        // without advancing and before the end of the line.
+        if (pim != NULL && (clen == 0 || match_follows(add_state, 0))) {
+          if (pim->result == NFA_PIM_TODO) {
+#ifdef REGEXP_DEBUG
+            fprintf(log_fd, "\n");
+            fprintf(log_fd, "==================================\n");
+            fprintf(log_fd, "Postponed recursive nfa_regmatch()\n");
+            fprintf(log_fd, "\n");
+#endif
+            result = recursive_regmatch(pim->state, pim, prog, submatch, m,
+                                        &listids, &listids_len);
+            pim->result = result ? NFA_PIM_MATCH : NFA_PIM_NOMATCH;
+            // for \@! and \@<! it is a match when the result is
+            // false
+            if (result != (pim->state->c == NFA_START_INVISIBLE_NEG
+                           || pim->state->c == NFA_START_INVISIBLE_NEG_FIRST
+                           || pim->state->c
+                           == NFA_START_INVISIBLE_BEFORE_NEG
+                           || pim->state->c
+                           == NFA_START_INVISIBLE_BEFORE_NEG_FIRST)) {
+              // Copy submatch info from the recursive call
+              copy_sub_off(&pim->subs.norm, &m->norm);
+              if (rex.nfa_has_zsubexpr) {
+                copy_sub_off(&pim->subs.synt, &m->synt);
+              }
+            }
+          } else {
+            result = (pim->result == NFA_PIM_MATCH);
+#ifdef REGEXP_DEBUG
+            fprintf(log_fd, "\n");
+            fprintf(log_fd,
+                    "Using previous recursive nfa_regmatch() result, result == %d\n",
+                    pim->result);
+            fprintf(log_fd, "MATCH = %s\n", result ? "OK" : "false");
+            fprintf(log_fd, "\n");
+#endif
+          }
+
+          // for \@! and \@<! it is a match when result is false
+          if (result != (pim->state->c == NFA_START_INVISIBLE_NEG
+                         || pim->state->c == NFA_START_INVISIBLE_NEG_FIRST
+                         || pim->state->c
+                         == NFA_START_INVISIBLE_BEFORE_NEG
+                         || pim->state->c
+                         == NFA_START_INVISIBLE_BEFORE_NEG_FIRST)) {
+            // Copy submatch info from the recursive call
+            copy_sub_off(&t->subs.norm, &pim->subs.norm);
+            if (rex.nfa_has_zsubexpr) {
+              copy_sub_off(&t->subs.synt, &pim->subs.synt);
+            }
+          } else {
+            // look-behind match failed, don't add the state
+            continue;
+          }
+
+          // Postponed invisible match was handled, don't add it to
+          // following states.
+          pim = NULL;
+        }
+
+        // If "pim" points into l->t it will become invalid when
+        // adding the state causes the list to be reallocated.  Make a
+        // local copy to avoid that.
+        if (pim == &t->pim) {
+          copy_pim(&pim_copy, pim);
+          pim = &pim_copy;
+        }
+
+        if (add_here) {
+          r = addstate_here(thislist, add_state, &t->subs, pim, &listidx);
+        } else {
+          r = addstate(nextlist, add_state, &t->subs, pim, add_off);
+          if (add_count > 0) {
+            nextlist->t[nextlist->n - 1].count = add_count;
+          }
+        }
+        if (r == NULL) {
+          nfa_match = NFA_TOO_EXPENSIVE;
+          goto theend;
+        }
+      }
+    }     // for (thislist = thislist; thislist->state; thislist++)
+
+    // Look for the start of a match in the current position by adding the
+    // start state to the list of states.
+    // The first found match is the leftmost one, thus the order of states
+    // matters!
+    // Do not add the start state in recursive calls of nfa_regmatch(),
+    // because recursive calls should only start in the first position.
+    // Unless "nfa_endp" is not NULL, then we match the end position.
+    // Also don't start a match past the first line.
+    if (!nfa_match
+        && ((toplevel
+             && rex.lnum == 0
+             && clen != 0
+             && (rex.reg_maxcol == 0
+                 || (colnr_T)(rex.input - rex.line) < rex.reg_maxcol))
+            || (nfa_endp != NULL
+                && (REG_MULTI
+                    ? (rex.lnum < nfa_endp->se_u.pos.lnum
+                       || (rex.lnum == nfa_endp->se_u.pos.lnum
+                           && (int)(rex.input - rex.line)
+                           < nfa_endp->se_u.pos.col))
+                    : rex.input < nfa_endp->se_u.ptr)))) {
+#ifdef REGEXP_DEBUG
+      fprintf(log_fd, "(---) STARTSTATE\n");
+#endif
+      // Inline optimized code for addstate() if we know the state is
+      // the first MOPEN.
+      if (toplevel) {
+        int add = true;
+
+        if (prog->regstart != NUL && clen != 0) {
+          if (nextlist->n == 0) {
+            colnr_T col = (colnr_T)(rex.input - rex.line) + clen;
+
+            // Nextlist is empty, we can skip ahead to the
+            // character that must appear at the start.
+            if (skip_to_start(prog->regstart, &col) == FAIL) {
+              break;
+            }
+#ifdef REGEXP_DEBUG
+            fprintf(log_fd, "  Skipping ahead %d bytes to regstart\n",
+                    col - ((colnr_T)(rex.input - rex.line) + clen));
+#endif
+            rex.input = rex.line + col - clen;
+          } else {
+            // Checking if the required start character matches is
+            // cheaper than adding a state that won't match.
+            const int c = utf_ptr2char((char *)rex.input + clen);
+            if (c != prog->regstart
+                && (!rex.reg_ic
+                    || utf_fold(c) != utf_fold(prog->regstart))) {
+#ifdef REGEXP_DEBUG
+              fprintf(log_fd,
+                      "  Skipping start state, regstart does not match\n");
+#endif
+              add = false;
+            }
+          }
+        }
+
+        if (add) {
+          if (REG_MULTI) {
+            m->norm.list.multi[0].start_col =
+              (colnr_T)(rex.input - rex.line) + clen;
+            m->norm.orig_start_col =
+              m->norm.list.multi[0].start_col;
+          } else {
+            m->norm.list.line[0].start = rex.input + clen;
+          }
+          if (addstate(nextlist, start->out, m, NULL, clen) == NULL) {
+            nfa_match = NFA_TOO_EXPENSIVE;
+            goto theend;
+          }
+        }
+      } else {
+        if (addstate(nextlist, start, m, NULL, clen) == NULL) {
+          nfa_match = NFA_TOO_EXPENSIVE;
+          goto theend;
+        }
+      }
+    }
+
+#ifdef REGEXP_DEBUG
+    fprintf(log_fd, ">>> Thislist had %d states available: ", thislist->n);
+    {
+      int i;
+
+      for (i = 0; i < thislist->n; i++) {
+        fprintf(log_fd, "%d  ", abs(thislist->t[i].state->id));
+      }
+    }
+    fprintf(log_fd, "\n");
+#endif
+
+nextchar:
+    // Advance to the next character, or advance to the next line, or
+    // finish.
+    if (clen != 0) {
+      rex.input += clen;
+    } else if (go_to_nextline || (nfa_endp != NULL && REG_MULTI
+                                  && rex.lnum < nfa_endp->se_u.pos.lnum)) {
+      reg_nextline();
+    } else {
+      break;
+    }
+
+    // Allow interrupting with CTRL-C.
+    reg_breakcheck();
+    if (got_int) {
+      break;
+    }
+    // Check for timeout once every twenty times to avoid overhead.
+    if (nfa_time_limit != NULL && ++nfa_time_count == 20) {
+      nfa_time_count = 0;
+      if (nfa_did_time_out()) {
+        break;
+      }
+    }
+  }
+
+#ifdef REGEXP_DEBUG
+  if (log_fd != stderr) {
+    fclose(log_fd);
+  }
+  log_fd = NULL;
+#endif
+
+theend:
+  // Free memory
+  xfree(list[0].t);
+  xfree(list[1].t);
+  xfree(listids);
+#undef ADD_STATE_IF_MATCH
+#ifdef NFA_REGEXP_DEBUG_LOG
+  fclose(debug);
+#endif
+
+  return nfa_match;
+}
+
+/// Try match of "prog" with at rex.line["col"].
+///
+/// @param tm         timeout limit or NULL
+/// @param timed_out  flag set on timeout or NULL
+///
+/// @return  <= 0 for failure, number of lines contained in the match otherwise.
+static int nfa_regtry(nfa_regprog_T *prog, colnr_T col, proftime_T *tm, int *timed_out)
+{
+  int i;
+  regsubs_T subs, m;
+  nfa_state_T *start = prog->start;
+#ifdef REGEXP_DEBUG
+  FILE *f;
+#endif
+
+  rex.input = rex.line + col;
+  nfa_time_limit = tm;
+  nfa_timed_out = timed_out;
+  nfa_time_count = 0;
+
+#ifdef REGEXP_DEBUG
+  f = fopen(NFA_REGEXP_RUN_LOG, "a");
+  if (f != NULL) {
+    fprintf(f,
+            "\n\n\t=======================================================\n");
+# ifdef REGEXP_DEBUG
+    fprintf(f, "\tRegexp is \"%s\"\n", nfa_regengine.expr);
+# endif
+    fprintf(f, "\tInput text is \"%s\" \n", rex.input);
+    fprintf(f, "\t=======================================================\n\n");
+    nfa_print_state(f, start);
+    fprintf(f, "\n\n");
+    fclose(f);
+  } else {
+    emsg("Could not open temporary log file for writing");
+  }
+#endif
+
+  clear_sub(&subs.norm);
+  clear_sub(&m.norm);
+  clear_sub(&subs.synt);
+  clear_sub(&m.synt);
+
+  int result = nfa_regmatch(prog, start, &subs, &m);
+  if (!result) {
+    return 0;
+  } else if (result == NFA_TOO_EXPENSIVE) {
+    return result;
+  }
+
+  cleanup_subexpr();
+  if (REG_MULTI) {
+    for (i = 0; i < subs.norm.in_use; i++) {
+      rex.reg_startpos[i].lnum = subs.norm.list.multi[i].start_lnum;
+      rex.reg_startpos[i].col = subs.norm.list.multi[i].start_col;
+
+      rex.reg_endpos[i].lnum = subs.norm.list.multi[i].end_lnum;
+      rex.reg_endpos[i].col = subs.norm.list.multi[i].end_col;
+    }
+    if (rex.reg_mmatch != NULL) {
+      rex.reg_mmatch->rmm_matchcol = subs.norm.orig_start_col;
+    }
+
+    if (rex.reg_startpos[0].lnum < 0) {
+      rex.reg_startpos[0].lnum = 0;
+      rex.reg_startpos[0].col = col;
+    }
+    if (rex.reg_endpos[0].lnum < 0) {
+      // pattern has a \ze but it didn't match, use current end
+      rex.reg_endpos[0].lnum = rex.lnum;
+      rex.reg_endpos[0].col = (int)(rex.input - rex.line);
+    } else {
+      // Use line number of "\ze".
+      rex.lnum = rex.reg_endpos[0].lnum;
+    }
+  } else {
+    for (i = 0; i < subs.norm.in_use; i++) {
+      rex.reg_startp[i] = subs.norm.list.line[i].start;
+      rex.reg_endp[i] = subs.norm.list.line[i].end;
+    }
+
+    if (rex.reg_startp[0] == NULL) {
+      rex.reg_startp[0] = rex.line + col;
+    }
+    if (rex.reg_endp[0] == NULL) {
+      rex.reg_endp[0] = rex.input;
+    }
+  }
+
+  // Package any found \z(...\) matches for export. Default is none.
+  unref_extmatch(re_extmatch_out);
+  re_extmatch_out = NULL;
+
+  if (prog->reghasz == REX_SET) {
+    cleanup_zsubexpr();
+    re_extmatch_out = make_extmatch();
+    // Loop over \z1, \z2, etc.  There is no \z0.
+    for (i = 1; i < subs.synt.in_use; i++) {
+      if (REG_MULTI) {
+        struct multipos *mpos = &subs.synt.list.multi[i];
+
+        // Only accept single line matches that are valid.
+        if (mpos->start_lnum >= 0
+            && mpos->start_lnum == mpos->end_lnum
+            && mpos->end_col >= mpos->start_col) {
+          re_extmatch_out->matches[i] =
+            (uint8_t *)xstrnsave(reg_getline(mpos->start_lnum) + mpos->start_col,
+                                 (size_t)(mpos->end_col - mpos->start_col));
+        }
+      } else {
+        struct linepos *lpos = &subs.synt.list.line[i];
+
+        if (lpos->start != NULL && lpos->end != NULL) {
+          re_extmatch_out->matches[i] =
+            (uint8_t *)xstrnsave((char *)lpos->start, (size_t)(lpos->end - lpos->start));
+        }
+      }
+    }
+  }
+
+  return 1 + rex.lnum;
+}
+
+/// Match a regexp against a string ("line" points to the string) or multiple
+/// lines (if "line" is NULL, use reg_getline()).
+///
+/// @param line String in which to search or NULL
+/// @param startcol Column to start looking for match
+/// @param tm Timeout limit or NULL
+/// @param timed_out Flag set on timeout or NULL
+///
+/// @return <= 0 if there is no match and number of lines contained in the
+/// match otherwise.
+static int nfa_regexec_both(uint8_t *line, colnr_T startcol, proftime_T *tm, int *timed_out)
+{
+  nfa_regprog_T *prog;
+  int retval = 0;
+  colnr_T col = startcol;
+
+  if (REG_MULTI) {
+    prog = (nfa_regprog_T *)rex.reg_mmatch->regprog;
+    line = (uint8_t *)reg_getline(0);  // relative to the cursor
+    rex.reg_startpos = rex.reg_mmatch->startpos;
+    rex.reg_endpos = rex.reg_mmatch->endpos;
+  } else {
+    prog = (nfa_regprog_T *)rex.reg_match->regprog;
+    rex.reg_startp = (uint8_t **)rex.reg_match->startp;
+    rex.reg_endp = (uint8_t **)rex.reg_match->endp;
+  }
+
+  // Be paranoid...
+  if (prog == NULL || line == NULL) {
+    iemsg(_(e_null));
+    goto theend;
+  }
+
+  // If pattern contains "\c" or "\C": overrule value of rex.reg_ic
+  if (prog->regflags & RF_ICASE) {
+    rex.reg_ic = true;
+  } else if (prog->regflags & RF_NOICASE) {
+    rex.reg_ic = false;
+  }
+
+  // If pattern contains "\Z" overrule value of rex.reg_icombine
+  if (prog->regflags & RF_ICOMBINE) {
+    rex.reg_icombine = true;
+  }
+
+  rex.line = line;
+  rex.lnum = 0;  // relative to line
+
+  rex.nfa_has_zend = prog->has_zend;
+  rex.nfa_has_backref = prog->has_backref;
+  rex.nfa_nsubexpr = prog->nsubexp;
+  rex.nfa_listid = 1;
+  rex.nfa_alt_listid = 2;
+#ifdef REGEXP_DEBUG
+  nfa_regengine.expr = prog->pattern;
+#endif
+
+  if (prog->reganch && col > 0) {
+    return 0L;
+  }
+
+  rex.need_clear_subexpr = true;
+  // Clear the external match subpointers if necessary.
+  if (prog->reghasz == REX_SET) {
+    rex.nfa_has_zsubexpr = true;
+    rex.need_clear_zsubexpr = true;
+  } else {
+    rex.nfa_has_zsubexpr = false;
+    rex.need_clear_zsubexpr = false;
+  }
+
+  if (prog->regstart != NUL) {
+    // Skip ahead until a character we know the match must start with.
+    // When there is none there is no match.
+    if (skip_to_start(prog->regstart, &col) == FAIL) {
+      return 0L;
+    }
+
+    // If match_text is set it contains the full text that must match.
+    // Nothing else to try. Doesn't handle combining chars well.
+    if (prog->match_text != NULL && !rex.reg_icombine) {
+      retval = find_match_text(&col, prog->regstart, prog->match_text);
+      if (REG_MULTI) {
+        rex.reg_mmatch->rmm_matchcol = col;
+      } else {
+        rex.reg_match->rm_matchcol = col;
+      }
+      return retval;
+    }
+  }
+
+  // If the start column is past the maximum column: no need to try.
+  if (rex.reg_maxcol > 0 && col >= rex.reg_maxcol) {
+    goto theend;
+  }
+
+  // Set the "nstate" used by nfa_regcomp() to zero to trigger an error when
+  // it's accidentally used during execution.
+  nstate = 0;
+  for (int i = 0; i < prog->nstate; i++) {
+    prog->state[i].id = i;
+    prog->state[i].lastlist[0] = 0;
+    prog->state[i].lastlist[1] = 0;
+  }
+
+  retval = nfa_regtry(prog, col, tm, timed_out);
+
+#ifdef REGEXP_DEBUG
+  nfa_regengine.expr = NULL;
+#endif
+
+theend:
+  if (retval > 0) {
+    // Make sure the end is never before the start.  Can happen when \zs and
+    // \ze are used.
+    if (REG_MULTI) {
+      const lpos_T *const start = &rex.reg_mmatch->startpos[0];
+      const lpos_T *const end = &rex.reg_mmatch->endpos[0];
+
+      if (end->lnum < start->lnum
+          || (end->lnum == start->lnum && end->col < start->col)) {
+        rex.reg_mmatch->endpos[0] = rex.reg_mmatch->startpos[0];
+      }
+    } else {
+      if (rex.reg_match->endp[0] < rex.reg_match->startp[0]) {
+        rex.reg_match->endp[0] = rex.reg_match->startp[0];
+      }
+
+      // startpos[0] may be set by "\zs", also return the column where
+      // the whole pattern matched.
+      rex.reg_match->rm_matchcol = col;
+    }
+  }
+
+  return retval;
+}
+
+// Compile a regular expression into internal code for the NFA matcher.
+// Returns the program in allocated space.  Returns NULL for an error.
+static regprog_T *nfa_regcomp(uint8_t *expr, int re_flags)
+{
+  nfa_regprog_T *prog = NULL;
+  int *postfix;
+
+  if (expr == NULL) {
+    return NULL;
+  }
+
+#ifdef REGEXP_DEBUG
+  nfa_regengine.expr = expr;
+#endif
+  nfa_re_flags = re_flags;
+
+  init_class_tab();
+
+  nfa_regcomp_start(expr, re_flags);
+
+  // Build postfix form of the regexp. Needed to build the NFA
+  // (and count its size).
+  postfix = re2post();
+  if (postfix == NULL) {
+    goto fail;              // Cascaded (syntax?) error
+  }
+
+  // In order to build the NFA, we parse the input regexp twice:
+  // 1. first pass to count size (so we can allocate space)
+  // 2. second to emit code
+#ifdef REGEXP_DEBUG
+  {
+    FILE *f = fopen(NFA_REGEXP_RUN_LOG, "a");
+
+    if (f != NULL) {
+      fprintf(f,
+              "\n*****************************\n\n\n\n\t"
+              "Compiling regexp \"%s\"... hold on !\n",
+              expr);
+      fclose(f);
+    }
+  }
+#endif
+
+  // PASS 1
+  // Count number of NFA states in "nstate". Do not build the NFA.
+  post2nfa(postfix, post_ptr, true);
+
+  // allocate the regprog with space for the compiled regexp
+  size_t prog_size = offsetof(nfa_regprog_T, state) + sizeof(nfa_state_T) * (size_t)nstate;
+  prog = xmalloc(prog_size);
+  state_ptr = prog->state;
+  prog->re_in_use = false;
+
+  // PASS 2
+  // Build the NFA
+  prog->start = post2nfa(postfix, post_ptr, false);
+  if (prog->start == NULL) {
+    goto fail;
+  }
+  prog->regflags = regflags;
+  prog->engine = &nfa_regengine;
+  prog->nstate = nstate;
+  prog->has_zend = rex.nfa_has_zend;
+  prog->has_backref = rex.nfa_has_backref;
+  prog->nsubexp = regnpar;
+
+  nfa_postprocess(prog);
+
+  prog->reganch = nfa_get_reganch(prog->start, 0);
+  prog->regstart = nfa_get_regstart(prog->start, 0);
+  prog->match_text = nfa_get_match_text(prog->start);
+
+#ifdef REGEXP_DEBUG
+  nfa_postfix_dump(expr, OK);
+  nfa_dump(prog);
+#endif
+  // Remember whether this pattern has any \z specials in it.
+  prog->reghasz = re_has_z;
+  prog->pattern = xstrdup((char *)expr);
+#ifdef REGEXP_DEBUG
+  nfa_regengine.expr = NULL;
+#endif
+
+out:
+  xfree(post_start);
+  post_start = post_ptr = post_end = NULL;
+  state_ptr = NULL;
+  return (regprog_T *)prog;
+
+fail:
+  XFREE_CLEAR(prog);
+#ifdef REGEXP_DEBUG
+  nfa_postfix_dump(expr, FAIL);
+  nfa_regengine.expr = NULL;
+#endif
+  goto out;
+}
+
+// Free a compiled regexp program, returned by nfa_regcomp().
+static void nfa_regfree(regprog_T *prog)
+{
+  if (prog == NULL) {
+    return;
+  }
+
+  xfree(((nfa_regprog_T *)prog)->match_text);
+  xfree(((nfa_regprog_T *)prog)->pattern);
+  xfree(prog);
+}
+
+/// Match a regexp against a string.
+/// "rmp->regprog" is a compiled regexp as returned by nfa_regcomp().
+/// Uses curbuf for line count and 'iskeyword'.
+/// If "line_lbr" is true, consider a "\n" in "line" to be a line break.
+///
+/// @param line  string to match against
+/// @param col   column to start looking for match
+///
+/// @return  <= 0 for failure, number of lines contained in the match otherwise.
+static int nfa_regexec_nl(regmatch_T *rmp, uint8_t *line, colnr_T col, bool line_lbr)
+{
+  rex.reg_match = rmp;
+  rex.reg_mmatch = NULL;
+  rex.reg_maxline = 0;
+  rex.reg_line_lbr = line_lbr;
+  rex.reg_buf = curbuf;
+  rex.reg_win = NULL;
+  rex.reg_ic = rmp->rm_ic;
+  rex.reg_icombine = false;
+  rex.reg_nobreak = rmp->regprog->re_flags & RE_NOBREAK;
+  rex.reg_maxcol = 0;
+  return nfa_regexec_both(line, col, NULL, NULL);
+}
+
+/// Matches a regexp against multiple lines.
+/// "rmp->regprog" is a compiled regexp as returned by vim_regcomp().
+/// Uses curbuf for line count and 'iskeyword'.
+///
+/// @param win Window in which to search or NULL
+/// @param buf Buffer in which to search
+/// @param lnum Number of line to start looking for match
+/// @param col Column to start looking for match
+/// @param tm Timeout limit or NULL
+/// @param timed_out Flag set on timeout or NULL
+///
+/// @return <= 0 if there is no match and number of lines contained in the match
+/// otherwise.
+///
+/// @note The body is the same as bt_regexec() except for nfa_regexec_both()
+///
+/// @warning
+/// Match may actually be in another line. e.g.:
+/// when r.e. is \nc, cursor is at 'a' and the text buffer looks like
+///
+/// @par
+///
+///     +-------------------------+
+///     |a                        |
+///     |b                        |
+///     |c                        |
+///     |                         |
+///     +-------------------------+
+///
+/// @par
+/// then nfa_regexec_multi() returns 3. while the original vim_regexec_multi()
+/// returns 0 and a second call at line 2 will return 2.
+///
+/// @par
+/// FIXME if this behavior is not compatible.
+static int nfa_regexec_multi(regmmatch_T *rmp, win_T *win, buf_T *buf, linenr_T lnum, colnr_T col,
+                             proftime_T *tm, int *timed_out)
+{
+  init_regexec_multi(rmp, win, buf, lnum);
+  return nfa_regexec_both(NULL, col, tm, timed_out);
+}
+// }}}1
 
 static regengine_T bt_regengine = {
   bt_regcomp,
@@ -2304,10 +15570,10 @@ static uint8_t regname[][30] = {
 // Returns the program in allocated memory.
 // Use vim_regfree() to free the memory.
 // Returns NULL for an error.
-regprog_T *vim_regcomp(char *expr_arg, int re_flags)
+regprog_T *vim_regcomp(const char *expr_arg, int re_flags)
 {
   regprog_T *prog = NULL;
-  char *expr = expr_arg;
+  const char *expr = expr_arg;
 
   regexp_engine = (int)p_re;
 
@@ -2321,7 +15587,7 @@ regprog_T *vim_regcomp(char *expr_arg, int re_flags)
       regexp_engine = expr[4] - '0';
       expr += 5;
 #ifdef REGEXP_DEBUG
-      smsg("New regexp mode selected (%d): %s",
+      smsg(0, "New regexp mode selected (%d): %s",
            regexp_engine,
            regname[newengine]);
 #endif
@@ -2403,7 +15669,7 @@ void free_regexp_stuff(void)
 
 #endif
 
-static void report_re_switch(char *pat)
+static void report_re_switch(const char *pat)
 {
   if (p_verbose > 0) {
     verbose_enter();
@@ -2425,7 +15691,7 @@ static void report_re_switch(char *pat)
 /// @param nl
 ///
 /// @return true if there is a match, false if not.
-static bool vim_regexec_string(regmatch_T *rmp, char *line, colnr_T col, bool nl)
+static bool vim_regexec_string(regmatch_T *rmp, const char *line, colnr_T col, bool nl)
 {
   regexec_T rex_save;
   bool rex_in_use_save = rex_in_use;
@@ -2482,7 +15748,7 @@ static bool vim_regexec_string(regmatch_T *rmp, char *line, colnr_T col, bool nl
 
 // Note: "*prog" may be freed and changed.
 // Return true if there is a match, false if not.
-bool vim_regexec_prog(regprog_T **prog, bool ignore_case, char *line, colnr_T col)
+bool vim_regexec_prog(regprog_T **prog, bool ignore_case, const char *line, colnr_T col)
 {
   regmatch_T regmatch = { .regprog = *prog, .rm_ic = ignore_case };
   bool r = vim_regexec_string(&regmatch, line, col, false);
@@ -2492,7 +15758,7 @@ bool vim_regexec_prog(regprog_T **prog, bool ignore_case, char *line, colnr_T co
 
 // Note: "rmp->regprog" may be freed and changed.
 // Return true if there is a match, false if not.
-bool vim_regexec(regmatch_T *rmp, char *line, colnr_T col)
+bool vim_regexec(regmatch_T *rmp, const char *line, colnr_T col)
 {
   return vim_regexec_string(rmp, line, col, false);
 }
@@ -2500,7 +15766,7 @@ bool vim_regexec(regmatch_T *rmp, char *line, colnr_T col)
 // Like vim_regexec(), but consider a "\n" in "line" to be a line break.
 // Note: "rmp->regprog" may be freed and changed.
 // Return true if there is a match, false if not.
-bool vim_regexec_nl(regmatch_T *rmp, char *line, colnr_T col)
+bool vim_regexec_nl(regmatch_T *rmp, const char *line, colnr_T col)
 {
   return vim_regexec_string(rmp, line, col, true);
 }
@@ -2519,8 +15785,8 @@ bool vim_regexec_nl(regmatch_T *rmp, char *line, colnr_T col)
 ///
 /// @return  zero if there is no match.  Return number of lines contained in the
 ///          match otherwise.
-long vim_regexec_multi(regmmatch_T *rmp, win_T *win, buf_T *buf, linenr_T lnum, colnr_T col,
-                       proftime_T *tm, int *timed_out)
+int vim_regexec_multi(regmmatch_T *rmp, win_T *win, buf_T *buf, linenr_T lnum, colnr_T col,
+                      proftime_T *tm, int *timed_out)
   FUNC_ATTR_NONNULL_ARG(1)
 {
   regexec_T rex_save;
@@ -2539,7 +15805,7 @@ long vim_regexec_multi(regmmatch_T *rmp, win_T *win, buf_T *buf, linenr_T lnum,
   }
   rex_in_use = true;
 
-  long result = rmp->regprog->engine->regexec_multi(rmp, win, buf, lnum, col, tm, timed_out);
+  int result = rmp->regprog->engine->regexec_multi(rmp, win, buf, lnum, col, tm, timed_out);
   rmp->regprog->re_in_use = false;
 
   // NFA engine aborted because it's very slow, use backtracking engine instead.