vim-patch:8.0.0643: when a pattern search is slow Vim becomes unusable

Problem:    When 'hlsearch' is set and matching with the last search pattern
            is very slow, Vim becomes unusable.  Cannot quit search by
            pressing CTRL-C.
Solution:   When the search times out set a flag and don't try again.  Check
            for timeout and CTRL-C in NFA loop that adds states.
https://github.com/vim/vim/commit/fbd0b0af6800f6ff89857863d6a07ea03f09ff6c

1 files changed, 22 insertions, 14 deletions

diff --git a/src/nvim/regexp.c b/src/nvim/regexp.c
index c043d4a173..25fa67c112 100644
--- a/src/nvim/regexp.c
+++ b/src/nvim/regexp.c
@@ -3297,7 +3297,7 @@ bt_regexec_nl (
   rex.reg_icombine = false;
   rex.reg_maxcol = 0;
 
-  long r = bt_regexec_both(line, col, NULL);
+  long r = bt_regexec_both(line, col, NULL, NULL);
   assert(r <= INT_MAX);
   return (int)r;
 }
@@ -3357,7 +3357,8 @@ static inline char_u *cstrchr(const char_u *const s, const int c)
 /// @return zero if there is no match and number of lines contained in the match
 ///         otherwise.
 static long bt_regexec_multi(regmmatch_T *rmp, win_T *win, buf_T *buf,
-                             linenr_T lnum, colnr_T col, proftime_T *tm)
+                             linenr_T lnum, colnr_T col,
+                             proftime_T *tm, int *timed_out)
 {
   rex.reg_match = NULL;
   rex.reg_mmatch = rmp;
@@ -3370,7 +3371,7 @@ static long bt_regexec_multi(regmmatch_T *rmp, win_T *win, buf_T *buf,
   rex.reg_icombine = false;
   rex.reg_maxcol = rmp->rmm_maxcol;
 
-  return bt_regexec_both(NULL, col, tm);
+  return bt_regexec_both(NULL, col, tm, timed_out);
 }
 
 /*
@@ -3379,8 +3380,10 @@ static long bt_regexec_multi(regmmatch_T *rmp, win_T *win, buf_T *buf,
  * Returns 0 for failure, number of lines contained in the match otherwise.
  */
 static long bt_regexec_both(char_u *line,
-                            colnr_T col, /* column to start looking for match */
-                            proftime_T *tm /* timeout limit or NULL */
+                            // column to start looking for match
+                            colnr_T col,
+                            proftime_T *tm,   // timeout limit or NULL
+                            int *timed_out    // flag set on timeout or NULL
                             )
 {
   bt_regprog_T        *prog;
@@ -3525,8 +3528,12 @@ static long bt_regexec_both(char_u *line,
       /* 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 (profile_passed_limit(*tm)) {
+          if (timed_out != NULL) {
+            *timed_out = true;
+          }
           break;
+        }
       }
     }
   }
@@ -7275,12 +7282,13 @@ int vim_regexec_nl(regmatch_T *rmp, char_u *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,               /* window in which to search or NULL */
-  buf_T       *buf,               /* buffer in which to search */
-  linenr_T lnum,                  /* nr of line to start looking for match */
-  colnr_T col,                    /* column to start looking for match */
-  proftime_T  *tm                 /* timeout limit or NULL */
+    regmmatch_T *rmp,
+    win_T       *win,               // window in which to search or NULL
+    buf_T       *buf,               // buffer in which to search
+    linenr_T lnum,                  // nr of line to start looking for match
+    colnr_T col,                    // column to start looking for match
+    proftime_T  *tm,                // timeout limit or NULL
+    int         *timed_out          // flag is set when timeout limit reached
 )
 {
   regexec_T rex_save;
@@ -7293,7 +7301,7 @@ long vim_regexec_multi(
   rex_in_use = true;
 
   int result = rmp->regprog->engine->regexec_multi(rmp, win, buf, lnum, col,
-                                                   tm);
+                                                   tm, timed_out);
 
   // NFA engine aborted because it's very slow, use backtracking engine instead.
   if (rmp->regprog->re_engine == AUTOMATIC_ENGINE
@@ -7313,7 +7321,7 @@ long vim_regexec_multi(
 
     if (rmp->regprog != NULL) {
       result = rmp->regprog->engine->regexec_multi(rmp, win, buf, lnum, col,
-                                                   tm);
+                                                   tm, timed_out);
     }
 
     xfree(pat);