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[PATCH v2 5/7] grep: un-break building with PCRE < 8.32

From
Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Date
May 23, 2017, 19:24 UTC
Message-ID
<20170523192453.14172-6-avarab@gmail.com>
In-Reply-To
<20170523192453.14172-1-avarab@gmail.com>

Amend my change earlier in this series ("grep: add support for the PCRE v1 JIT API", 2017-04-11) to un-break the build on PCRE v1 versions earlier than 8.32.

The JIT support was added in version 8.20 released on 2011-10-21, but it wasn't until 8.32 released on 2012-11-30 that the fast code path to use the JIT via pcre_jit_exec() was added[1] (see also [2]).

This means that versions 8.20 through 8.31 could still use the JIT, but supporting it on those versions would add to the already verbose macro soup around JIT support it, and I don't expect that the use-case of compiling a brand new git against a 5 year old PCRE is particularly common, and if someone does that they can just get the existing pre-JIT slow codepath.

So just take the easy way out and disable the JIT on any version older than 8.32.

The reason this change isn't part of the initial change PCRE JIT support is because possibly slightly annoying someone who's bisecting with an ancient PCRE is worth it to have a cleaner history showing which parts of the implementation are only used for ancient PCRE versions. This also makes it easier to revert this change if we ever decide to stop supporting those old versions.

1. http://www.pcre.org/original/changelog.txt ("28. Introducing a
   native interface for JIT. Through this interface, the
   compiled[...]")
2. https://bugs.exim.org/show_bug.cgi?id=2121
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 grep.c | 8 ++++----
 grep.h | 5 +++++
 2 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/grep.c b/grep.c
index 49e9aed457..3c0c30f033 100644
--- a/grep.c
+++ b/grep.c
@@ -351,7 +351,7 @@ static void compile_pcre1_regexp(struct grep_pat *p, const struct grep_opt *opt)
 	const char *error;
 	int erroffset;
 	int options = PCRE_MULTILINE;
-#ifdef PCRE_CONFIG_JIT
+#ifdef GIT_PCRE1_CAN_DO_MODERN_JIT
 	int canjit;
 #endif
 
@@ -372,7 +372,7 @@ static void compile_pcre1_regexp(struct grep_pat *p, const struct grep_opt *opt)
 	if (!p->pcre1_extra_info && error)
 		die("%s", error);
 
-#ifdef PCRE_CONFIG_JIT
+#ifdef GIT_PCRE1_CAN_DO_MODERN_JIT
 	pcre_config(PCRE_CONFIG_JIT, &canjit);
 	if (canjit == 1) {
 		p->pcre1_jit_stack = pcre_jit_stack_alloc(1, 1024 * 1024);
@@ -392,7 +392,7 @@ static int pcre1match(struct grep_pat *p, const char *line, const char *eol,
 	if (eflags & REG_NOTBOL)
 		flags |= PCRE_NOTBOL;
 
-#ifdef PCRE_CONFIG_JIT
+#ifdef GIT_PCRE1_CAN_DO_MODERN_JIT
 	if (p->pcre1_jit_on)
 		ret = pcre_jit_exec(p->pcre1_regexp, p->pcre1_extra_info, line,
 				    eol - line, 0, flags, ovector,
@@ -418,7 +418,7 @@ static void free_pcre1_regexp(struct grep_pat *p)
 {
 	pcre_free(p->pcre1_regexp);
 
-#ifdef PCRE_CONFIG_JIT
+#ifdef GIT_PCRE1_CAN_DO_MODERN_JIT
 	if (p->pcre1_jit_on) {
 		pcre_free_study(p->pcre1_extra_info);
 		pcre_jit_stack_free(p->pcre1_jit_stack);
diff --git a/grep.h b/grep.h
index 14f47189f9..73ef0ef8ec 100644
--- a/grep.h
+++ b/grep.h
@@ -3,6 +3,11 @@
 #include "color.h"
 #ifdef USE_LIBPCRE1
 #include <pcre.h>
+#ifdef PCRE_CONFIG_JIT
+#if PCRE_MAJOR >= 8 && PCRE_MINOR >= 32
+#define GIT_PCRE1_CAN_DO_MODERN_JIT
+#endif
+#endif
 #ifndef PCRE_STUDY_JIT_COMPILE
 #define PCRE_STUDY_JIT_COMPILE 0
 #endif

-- 
2.13.0.303.g4ebf302169
Previous: Ævar Arnfjörð BjarmasonNext: Junio C Hamano
Message 41 of 58 in “Easy to review grep & pre-PCRE changes”
  1. 00/30 Easy to review grep & pre-PCRE changesÆvar Arnfjörð Bjarmason, May 20, 2017
  2. 01/30 Makefile & configure: reword inaccurate comment about PCREÆvar Arnfjörð Bjarmason, May 20, 2017
  3. 02/30 grep & rev-list doc: stop promising libpcre for --perl-regexpÆvar Arnfjörð Bjarmason, May 20, 2017
  4. 03/30 test-lib: rename the LIBPCRE prerequisite to PCREÆvar Arnfjörð Bjarmason, May 20, 2017
  5. 04/30 log: add exhaustive tests for pattern style options & configÆvar Arnfjörð Bjarmason, May 20, 2017
  6. 07/30 grep: add a test for backreferences in PCRE patternsÆvar Arnfjörð Bjarmason, May 20, 2017
  7. 05/30 log: make --regexp-ignore-case work with --perl-regexpÆvar Arnfjörð Bjarmason, May 20, 2017
  8. Junio C HamanoMay 20, 2017
  9. Ævar Arnfjörð BjarmasonMay 21, 2017
  10. Junio C HamanoMay 22, 2017
  11. 06/30 grep: add a test asserting that --perl-regexp dies when !PCREÆvar Arnfjörð Bjarmason, May 20, 2017
  12. 08/30 grep: change non-ASCII -i test to stop using --debugÆvar Arnfjörð Bjarmason, May 20, 2017
  13. 12/30 grep: add a test helper function for less verbose -f \0 testsÆvar Arnfjörð Bjarmason, May 20, 2017
  14. 10/30 grep: amend submodule recursion test for regex engine testingÆvar Arnfjörð Bjarmason, May 20, 2017
  15. 09/30 grep: add tests for --threads=N and grep.threadsÆvar Arnfjörð Bjarmason, May 20, 2017
  16. 13/30 grep: prepare for testing binary regexes containing rx metacharactersÆvar Arnfjörð Bjarmason, May 20, 2017
  17. 11/30 grep: add tests for grep pattern types being passed to submodulesÆvar Arnfjörð Bjarmason, May 20, 2017
  18. 14/30 grep: add tests to fix blind spots with \0 patternsÆvar Arnfjörð Bjarmason, May 20, 2017
  19. 15/30 perf: add a GIT_PERF_MAKE_COMMAND for when *_MAKE_OPTS won't doÆvar Arnfjörð Bjarmason, May 20, 2017
  20. Junio C HamanoMay 20, 2017
  21. Ævar Arnfjörð BjarmasonMay 21, 2017
  22. 18/30 perf: add a comparison test of grep regex engines with -FÆvar Arnfjörð Bjarmason, May 20, 2017
  23. 20/30 grep: catch a missing enum in switch statementÆvar Arnfjörð Bjarmason, May 20, 2017
  24. 17/30 perf: add a comparison test of grep regex enginesÆvar Arnfjörð Bjarmason, May 20, 2017
  25. 19/30 perf: add a comparison test of log --grep regex enginesÆvar Arnfjörð Bjarmason, May 20, 2017
  26. 16/30 perf: emit progress output when unpacking & buildingÆvar Arnfjörð Bjarmason, May 20, 2017
  27. 21/30 grep: remove redundant regflags assignmentsÆvar Arnfjörð Bjarmason, May 20, 2017
  28. 22/30 grep: factor test for \0 in grep patterns into a functionÆvar Arnfjörð Bjarmason, May 20, 2017
  29. Brandon WilliamsMay 23, 2017
  30. 25/30 grep: move is_fixed() earlier to avoid forward declarationÆvar Arnfjörð Bjarmason, May 20, 2017
  31. 23/30 grep: change the internal PCRE macro names to be PCRE1Ævar Arnfjörð Bjarmason, May 20, 2017
  32. 24/30 grep: change internal *pcre* variable & function names to be *pcre1*Ævar Arnfjörð Bjarmason, May 20, 2017
  33. 26/30 test-lib: add a PTHREADS prerequisiteÆvar Arnfjörð Bjarmason, May 20, 2017
  34. 28/30 pack-objects: fix buggy warning about threadsÆvar Arnfjörð Bjarmason, May 20, 2017
  35. 30/30 grep: assert that threading is enabled when calling grep_{lock,unlock}Ævar Arnfjörð Bjarmason, May 20, 2017
  36. 29/30 grep: given --threads with NO_PTHREADS=YesPlease, warnÆvar Arnfjörð Bjarmason, May 20, 2017
  37. 27/30 pack-objects & index-pack: add test for --threads warningÆvar Arnfjörð Bjarmason, May 20, 2017
  38. Junio C HamanoMay 20, 2017
  39. 0/7 PCRE v2, PCRE v1 JIT, log -P & fixesÆvar Arnfjörð Bjarmason, May 23, 2017
  40. 3/7 log: add -P as a synonym for --perl-regexpÆvar Arnfjörð Bjarmason, May 23, 2017
  41. 5/7 grep: un-break building with PCRE < 8.32Ævar Arnfjörð Bjarmason, May 23, 2017
  42. Junio C HamanoMay 24, 2017
  43. Junio C HamanoMay 24, 2017
  44. 6/7 grep: un-break building with PCRE < 8.20Ævar Arnfjörð Bjarmason, May 23, 2017
  45. 2/7 grep: skip pthreads overhead when using one threadÆvar Arnfjörð Bjarmason, May 23, 2017
  46. Junio C HamanoMay 24, 2017
  47. 4/7 grep: add support for the PCRE v1 JIT APIÆvar Arnfjörð Bjarmason, May 23, 2017
  48. Junio C HamanoMay 24, 2017
  49. Ævar Arnfjörð BjarmasonMay 24, 2017
  50. 7/7 grep: add support for PCRE v2Ævar Arnfjörð Bjarmason, May 23, 2017
  51. Junio C HamanoMay 24, 2017
  52. Ævar Arnfjörð BjarmasonMay 25, 2017
  53. 1/7 grep: don't redundantly compile throwaway patterns under threadingÆvar Arnfjörð Bjarmason, May 23, 2017
  54. Junio C HamanoMay 24, 2017
  55. Ævar Arnfjörð BjarmasonMay 25, 2017
  56. Junio C HamanoMay 26, 2017
  57. Ævar Arnfjörð BjarmasonMay 26, 2017
  58. Junio C HamanoMay 26, 2017

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