grep: un-break building with PCRE < 8.32

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 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>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/grep.c b/grep.c
index ffe95995eee4351cabe8bfd956617e7dfa97d0eb..19fa67c34c2dda42ba9c0d3d6cb88f99aad22af8 100644 (file)
--- a/grep.c
+++ b/grep.c
@@ -369,7 +369,7 @@ 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_USE_JIT
        pcre_config(PCRE_CONFIG_JIT, &p->pcre1_jit_on);
        if (p->pcre1_jit_on == 1) {
                p->pcre1_jit_stack = pcre_jit_stack_alloc(1, 1024 * 1024);
@@ -391,7 +391,7 @@ 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_USE_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 int pcre1match(struct grep_pat *p, const char *line, const char *eol,
 static void free_pcre1_regexp(struct grep_pat *p)
 {
        pcre_free(p->pcre1_regexp);
-#ifdef PCRE_CONFIG_JIT
+#ifdef GIT_PCRE1_USE_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 14f47189f9f0c94f2863836446dd16ca00ca390e..3b948d91553142b8e3e9c52c2e4a5cd1a66a497a 100644 (file)
--- 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_USE_JIT
+#endif
+#endif
 #ifndef PCRE_STUDY_JIT_COMPILE
 #define PCRE_STUDY_JIT_COMPILE 0
 #endif