[RFC PATCH 1/2] grep: fallback to interpreter if JIT fails with pcre1

From

Carlo Marcelo Arenas Belón <carenas@gmail.com>

Date

Dec 9, 2018, 23:00 UTC

Message-ID

<20181209230024.43444-2-carenas@gmail.com>

In-Reply-To

<20181209230024.43444-1-carenas@gmail.com>

Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
---
 Makefile | 12 ++++++------
 grep.c   |  6 ++++++
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/Makefile b/Makefile
index 1a44c811aa..62b0cb6ee6 100644
--- a/Makefile
+++ b/Makefile
@@ -32,14 +32,14 @@ all::
 # USE_LIBPCRE is a synonym for USE_LIBPCRE2, define USE_LIBPCRE1
 # instead if you'd like to use the legacy version 1 of the PCRE
 # library. Support for version 1 will likely be removed in some future
-# release of Git, as upstream has all but abandoned it.
+# release of Git, as upstream is focusing all development for new
+# features in the newer version instead.
 #
 # When using USE_LIBPCRE1, define NO_LIBPCRE1_JIT if the PCRE v1
-# library is compiled without --enable-jit. We will auto-detect
-# whether the version of the PCRE v1 library in use has JIT support at
-# all, but we unfortunately can't auto-detect whether JIT support
-# hasn't been compiled in in an otherwise JIT-supporting version. If
-# you have link-time errors about a missing `pcre_jit_exec` define
+# library is newer than 8.32 but compiled without --enable-jit or
+# you want to disable JIT
+#
+# If you have link-time errors about a missing `pcre_jit_exec` define
 # this, or recompile PCRE v1 with --enable-jit.
 #
 # Define LIBPCREDIR=/foo/bar if your PCRE header and library files are
diff --git a/grep.c b/grep.c
index 4db1510d16..5ccc0421a1 100644
--- a/grep.c
+++ b/grep.c
@@ -405,6 +405,12 @@ static void compile_pcre1_regexp(struct grep_pat *p, const struct grep_opt *opt)
 		die("%s", error);
 
 #ifdef GIT_PCRE1_USE_JIT
+	if (p->pcre1_extra_info &&
+		!(p->pcre1_extra_info->flags & PCRE_EXTRA_EXECUTABLE_JIT)) {
+		/* JIT failed so fallback to the interpreter */
+		p->pcre1_jit_on = 0;
+		return;
+	}
 	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);

-- 
2.20.0