GNU bug report logs - #23712
[PATCH 1/6] maint: mark a couple of static variables const

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Zev Weiss <zev <at> bewilderbeest.net>
To: bug-grep <at> gnu.org
Cc: Zev Weiss <zev <at> bewilderbeest.net>
Subject: [PATCH 1/6] maint: mark a couple of static variables const
Date: Tue,  7 Jun 2016 01:37:38 -0500

* src/dfa.c (parse_bracket_exp): mark zeroclass const.
* src/dfasearch.c: mark patterns0 const.
---
 src/dfa.c       | 2 +-
 src/dfasearch.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/dfa.c b/src/dfa.c
index 4e47b39..19363ce 100644
--- a/src/dfa.c
+++ b/src/dfa.c
@@ -1183,7 +1183,7 @@ parse_bracket_exp (void)
 
   if (dfa->multibyte)
     {
-      static charclass zeroclass;
+      static charclass const zeroclass;
       work_mbc->invert = invert;
       work_mbc->cset = equal (ccl, zeroclass) ? -1 : charclass_index (ccl);
       return MBCSET;
diff --git a/src/dfasearch.c b/src/dfasearch.c
index d3db824..8052ef0 100644
--- a/src/dfasearch.c
+++ b/src/dfasearch.c
@@ -38,7 +38,7 @@ static kwset_t kwset;
 static struct dfa *dfa;
 
 /* The Regex compiled patterns.  */
-static struct patterns
+static const struct patterns
 {
   /* Regex compiled regexp. */
   struct re_pattern_buffer regexbuf;
-- 
2.8.0.rc3

Message #10 received at 23712-done <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: 23712-done <at> debbugs.gnu.org
Cc: Zev Weiss <zev <at> bewilderbeest.net>
Subject: Re: [PATCH 1/6] maint: mark a couple of static variables const
Date: Wed, 17 Aug 2016 18:54:05 -0700

[Message part 1 (text/plain, inline)]

Thanks, this patch was installed into grep in June so I'm marking the bug report 
as done.

Also, I installed the attached two patches as followup. The first is because 
I've run into too many compilers that complain about 'static const int x;' on 
the grounds that x should have an initializer. Rewriting the code to avoid these 
zero constants makes the code a tiny bit smaller on x86-64, so it's likely a 
tiny win anyway.

The 2nd patch changes this code to use 64-bit words on x86-64 GNU/Linux, much as 
other parts of grep already do. This makes the code a tiny bit smaller too.

The runtime performance change is likely so small I haven't bothered to try to 
measure it. Perhaps some day compilers will be smart enough to put those 256-bit 
arrays into registers and regex nerds can tune it some more....

[0001-dfa-avoid-uninitialized-constants.patch (text/x-diff, attachment)]

[0002-dfa-use-64-bit-when-ulong-is-at-least-that-wide.patch (text/x-diff, attachment)]

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