grep: un-break building with PCRE >= 8.32 without --enable-jit

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 later than 8.31 compiled without --enable-jit.

As explained in that change and a later compatibility change in this
series ("grep: un-break building with PCRE < 8.32", 2017-05-10) the
pcre_jit_exec() function is a faster path to execute the JIT.

Unfortunately there's no compatibility stub for that function compiled
into the library if pcre_config(PCRE_CONFIG_JIT, &ret) would return 0,
and no macro that can be used to check for it, so the only portable
option to support builds without --enable-jit is via a new
NO_LIBPCRE1_JIT=UnfortunatelyYes Makefile option[1].

Another option would be to make the JIT opt-in via
USE_LIBPCRE1_JIT=YesPlease, after all it's not a default option of
PCRE v1.

I think it makes more sense to make it opt-out since even though it's
not a default option, most packagers of PCRE seem to turn it on by
default, with the notable exception of the MinGW package.

Make the MinGW platform work by default by changing the build defaults
to turn on NO_LIBPCRE1_JIT=UnfortunatelyYes. It is the only platform
that turns on USE_LIBPCRE=YesPlease by default, see commit
df5218b4c3 ("config.mak.uname: support MSys2", 2016-01-13) for that
change.

1. "How do I support pcre1 JIT on all
versions?"  (https://lists.exim.org/lurker/thread/20170601.103148.10253788.en.html)

2. https://github.com/Alexpux/MINGW-packages/blob/master/mingw-w64-pcre/PKGBUILD
(referenced from "Re: PCRE v2 compile error, was Re: What's cooking
in git.git (May 2017, #01; Mon, 1)";
<alpine.DEB.2.20.1705021756530.3480@virtualbox>)

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Makefile b/Makefile
index a79274e5e69c9a189f6d5a4ee857fedd93a5150d..502c07246f0d2b996d07e9007356541728bd7ccc 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -29,6 +29,14 @@ all::
 # Perl-compatible regular expressions instead of standard or extended
 # POSIX regular expressions.
 #
+# 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
+# this, or recompile PCRE v1 with --enable-jit.
+#
 # Define LIBPCREDIR=/foo/bar if your libpcre header and library files are in
 # /foo/bar/include and /foo/bar/lib directories.
 #
@@ -1094,6 +1102,10 @@ ifdef USE_LIBPCRE
                EXTLIBS += -L$(LIBPCREDIR)/$(lib) $(CC_LD_DYNPATH)$(LIBPCREDIR)/$(lib)
        endif
        EXTLIBS += -lpcre
+
+ifdef NO_LIBPCRE1_JIT
+       BASIC_CFLAGS += -DNO_LIBPCRE1_JIT
+endif
 endif
 
 ifdef HAVE_ALLOCA_H
@@ -2241,6 +2253,7 @@ GIT-BUILD-OPTIONS: FORCE
        @echo NO_CURL=\''$(subst ','\'',$(subst ','\'',$(NO_CURL)))'\' >>$@+
        @echo NO_EXPAT=\''$(subst ','\'',$(subst ','\'',$(NO_EXPAT)))'\' >>$@+
        @echo USE_LIBPCRE1=\''$(subst ','\'',$(subst ','\'',$(USE_LIBPCRE)))'\' >>$@+
+       @echo NO_LIBPCRE1_JIT=\''$(subst ','\'',$(subst ','\'',$(NO_LIBPCRE1_JIT)))'\' >>$@+
        @echo NO_PERL=\''$(subst ','\'',$(subst ','\'',$(NO_PERL)))'\' >>$@+
        @echo NO_PTHREADS=\''$(subst ','\'',$(subst ','\'',$(NO_PTHREADS)))'\' >>$@+
        @echo NO_PYTHON=\''$(subst ','\'',$(subst ','\'',$(NO_PYTHON)))'\' >>$@+

diff --git a/config.mak.uname b/config.mak.uname
index 399fe192719072691ebdbd7954fd8bd6cc12b96e..2a577794ba55f2c2a585f82ae241db9b97ff668c 100644 (file)
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -550,6 +550,7 @@ else
                NO_GETTEXT =
                USE_GETTEXT_SCHEME = fallthrough
                USE_LIBPCRE= YesPlease
+               NO_LIBPCRE1_JIT = UnfortunatelyYes
                NO_CURL =
                USE_NED_ALLOCATOR = YesPlease
        else

diff --git a/grep.h b/grep.h
index ce909697361125c28aa9ecbb401735d9ad47397d..3bff0870b25cedce6d01d2924eb2af61bd6b58aa 100644 (file)
--- a/grep.h
+++ b/grep.h
@@ -5,9 +5,11 @@
 #include <pcre.h>
 #ifdef PCRE_CONFIG_JIT
 #if PCRE_MAJOR >= 8 && PCRE_MINOR >= 32
+#ifndef NO_LIBPCRE1_JIT
 #define GIT_PCRE1_USE_JIT
 #endif
 #endif
+#endif
 #ifndef PCRE_STUDY_JIT_COMPILE
 #define PCRE_STUDY_JIT_COMPILE 0
 #endif