bug#58558: 29.0.50; re-search-forward is slow in some buffers

[Ihor Radchenko]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

> BTW, when debugging such performance problem, I often resort to
> a few `DEFVAR_INT` defining ad-hoc counter variables, then sprinkle
> corresponding increments of those variables from various places
> (typically function entry point, loops, ...).

Well. I just tried, but my Emacs-C foo is not good enough.
The attached patch fails to compile.

>From ac15ad3262ddf0a0bf459dc603cb79f7f9c737f7 Mon Sep 17 00:00:00 2001
Message-Id: 
<ac15ad3262ddf0a0bf459dc603cb79f7f9c737f7.1681212491.git.yantar92@posteo.net>
From: Ihor Radchenko <yantar92@posteo.net>
Date: Tue, 11 Apr 2023 13:27:56 +0200
Subject: [PATCH] add debug vars

---
 src/regex-emacs.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/src/regex-emacs.c b/src/regex-emacs.c
index 2571812cb39..6bcc64d5c0a 100644
--- a/src/regex-emacs.c
+++ b/src/regex-emacs.c
@@ -3889,6 +3889,25 @@ unwind_re_match (void *ptr)
   b->text->inhibit_shrinking = 0;
 }
 
+DEFVAR_INT("re-match-2-internal-bytepos-calls-1", 
re_match_2_internal_bytepos_calls_1,
+          doc: /* Call count 1.  Internal use only. */);
+DEFVAR_INT("re-match-2-internal-bytepos-calls-2", 
re_match_2_internal_bytepos_calls_2,
+          doc: /* Call count 1.  Internal use only. */);
+DEFVAR_INT("re-match-2-internal-bytepos-calls-3", 
re_match_2_internal_bytepos_calls_3,
+          doc: /* Call count 1.  Internal use only. */);
+DEFVAR_INT("re-match-2-internal-bytepos-calls-4", 
re_match_2_internal_bytepos_calls_4,
+          doc: /* Call count 1.  Internal use only. */);
+DEFVAR_INT("re-match-2-internal-bytepos-calls-5", 
re_match_2_internal_bytepos_calls_5,
+          doc: /* Call count 1.  Internal use only. */);
+DEFVAR_INT("re-match-2-internal-bytepos-calls-6", 
re_match_2_internal_bytepos_calls_6,
+          doc: /* Call count 1.  Internal use only. */);
+re_match_2_internal_bytepos_calls_1 = 0;
+re_match_2_internal_bytepos_calls_2 = 0;
+re_match_2_internal_bytepos_calls_3 = 0;
+re_match_2_internal_bytepos_calls_4 = 0;
+re_match_2_internal_bytepos_calls_5 = 0;
+re_match_2_internal_bytepos_calls_6 = 0;
+
 /* This is a separate function so that we can force an alloca cleanup
    afterwards.  */
 static ptrdiff_t
@@ -4808,6 +4827,7 @@ re_match_2_internal (struct re_pattern_buffer *bufp,
                int dummy;
                 ptrdiff_t offset = PTR_TO_OFFSET (d);
                 ptrdiff_t charpos = SYNTAX_TABLE_BYTE_TO_CHAR (offset) - 1;
+               re_match_2_internal_bytepos_calls_1++;
                UPDATE_SYNTAX_TABLE (charpos);
                GET_CHAR_BEFORE_2 (c1, d, string1, end1, string2, end2);
                nchars++;
@@ -4848,6 +4868,7 @@ re_match_2_internal (struct re_pattern_buffer *bufp,
              int dummy;
              ptrdiff_t offset = PTR_TO_OFFSET (d);
              ptrdiff_t charpos = SYNTAX_TABLE_BYTE_TO_CHAR (offset);
+             re_match_2_internal_bytepos_calls_2++;
              UPDATE_SYNTAX_TABLE (charpos);
              PREFETCH ();
              GET_CHAR_AFTER (c2, d, dummy);
@@ -4891,6 +4912,7 @@ re_match_2_internal (struct re_pattern_buffer *bufp,
              int dummy;
               ptrdiff_t offset = PTR_TO_OFFSET (d);
               ptrdiff_t charpos = SYNTAX_TABLE_BYTE_TO_CHAR (offset) - 1;
+             re_match_2_internal_bytepos_calls_3++;
              UPDATE_SYNTAX_TABLE (charpos);
              GET_CHAR_BEFORE_2 (c1, d, string1, end1, string2, end2);
              nchars++;
@@ -4933,6 +4955,7 @@ re_match_2_internal (struct re_pattern_buffer *bufp,
              int s1, s2;
              ptrdiff_t offset = PTR_TO_OFFSET (d);
              ptrdiff_t charpos = SYNTAX_TABLE_BYTE_TO_CHAR (offset);
+             re_match_2_internal_bytepos_calls_4++;
              UPDATE_SYNTAX_TABLE (charpos);
              PREFETCH ();
              c2 = RE_STRING_CHAR (d, target_multibyte);
@@ -4974,6 +4997,7 @@ re_match_2_internal (struct re_pattern_buffer *bufp,
              int s1, s2;
               ptrdiff_t offset = PTR_TO_OFFSET (d);
               ptrdiff_t charpos = SYNTAX_TABLE_BYTE_TO_CHAR (offset) - 1;
+             re_match_2_internal_bytepos_calls_5++;
              UPDATE_SYNTAX_TABLE (charpos);
              GET_CHAR_BEFORE_2 (c1, d, string1, end1, string2, end2);
              nchars++;
@@ -5010,6 +5034,7 @@ re_match_2_internal (struct re_pattern_buffer *bufp,
            {
              ptrdiff_t offset = PTR_TO_OFFSET (d);
              ptrdiff_t pos1 = SYNTAX_TABLE_BYTE_TO_CHAR (offset);
+             re_match_2_internal_bytepos_calls_6++;
              UPDATE_SYNTAX_TABLE (pos1);
            }
            {
-- 
2.40.0

-- 
Ihor Radchenko // yantar92,
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