Merge #9803 from janlazo/vim-8.0.0504

Benchmarked using RelWithDebInfo build and the `:Time` command from
https://github.com/tpope/vim-scriptease .

    :Time for i in range(0,99999)|call exists(':abbreviate')|endfor

- before (8698830cbd73):   0.431 seconds
- after (63025a1d65bf): 0.345 seconds
- Vim 8.1.1005 : 0.361 seconds

1 files changed, 22 insertions, 5 deletions

diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index fbe41f9914..037b5dec7f 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -2263,8 +2263,11 @@ static char_u * do_one_cmd(char_u **cmdlinep,
   need_rethrow = check_cstack = FALSE;
 
 doend:
-  if (curwin->w_cursor.lnum == 0)       /* can happen with zero line number */
+  // can happen with zero line number
+  if (curwin->w_cursor.lnum == 0) {
     curwin->w_cursor.lnum = 1;
+    curwin->w_cursor.col = 0;
+  }
 
   if (errormsg != NULL && *errormsg != NUL && !did_emsg) {
     if (flags & DOCMD_VERBOSE) {
@@ -2440,10 +2443,24 @@ static char_u *find_command(exarg_T *eap, int *full)
       }
     }
 
-    if (ASCII_ISLOWER(*eap->cmd))
-      eap->cmdidx = cmdidxs[CharOrdLow(*eap->cmd)];
-    else
-      eap->cmdidx = cmdidxs[26];
+    if (ASCII_ISLOWER(eap->cmd[0])) {
+      const int c1 = eap->cmd[0];
+      const int c2 = eap->cmd[1];
+
+      if (command_count != (int)CMD_SIZE) {
+        iemsg((char *)_("E943: Command table needs to be updated, run 'make'"));
+        getout(1);
+      }
+
+      // Use a precomputed index for fast look-up in cmdnames[]
+      // taking into account the first 2 letters of eap->cmd.
+      eap->cmdidx = cmdidxs1[CharOrdLow(c1)];
+      if (ASCII_ISLOWER(c2)) {
+        eap->cmdidx += cmdidxs2[CharOrdLow(c1)][CharOrdLow(c2)];
+      }
+    } else {
+      eap->cmdidx = CMD_bang;
+    }
 
     for (; (int)eap->cmdidx < (int)CMD_SIZE;
          eap->cmdidx = (cmdidx_T)((int)eap->cmdidx + 1))