[PATCH v2 00/13] PCRE v1 improvements & PCRE v2 support

[PATCH v2 00/13] PCRE v1 improvements & PCRE v2 support

[Ævar Arnfjörð Bjarmason]

It's been a while since I sent v1 of this. I addressed most of the
comments, except:

 * grep w/submodules doesn't properly pcre2 to submodule greps.

 * The critiqued adding runtime complexity by supporting both pcre1 &
   pcre2 via a switch is still there.

I wanted to get something out the door to review the other bits I've
changed sooner than later, so I'm sending it in the state it's in.
Depending on the consensus for those two issues, fixes for those can
easily be addedd on top.

Comments on specific patches:

Ævar Arnfjörð Bjarmason (13):

Firstly, the "git grep --threads=N" patch is missing, that became the
independent "[PATCH v2 0/8] grep threading cleanup & tests"
series. See <20170416222102.2320-1-avarab@gmail.com>.

  grep: remove redundant regflags assignment under PCRE

No changes.

  Makefile & configure: reword outdated comment about PCRE

Fix comment copy as suggested by JK, and explained the confusing
copy/pasting of Makefile comments to configure.ac in the commit
message.

  grep: add a test for backreferences in PCRE patterns

No changes.

  log: add exhaustive tests for pattern style options & config

Now using [\d] instead of \((?=1) as a pattern to tell -E and -P
patterns apart, as suggested by JK.

  log: add -P as a synonym for --perl-regexp

Uses the [\d] pattern now for a test, no other changes.

  grep & rev-list doc: stop promising libpcre for --perl-regexp

No changes.

  grep: make grep.patternType=[pcre|pcre1] a synonym for "perl"

Minor grammar fix in commit message.

  test-lib: rename the LIBPCRE prerequisite to PCRE

No changes.

  grep: change the internal PCRE macro names to be PCRE1

No changes.

  grep: change the internal PCRE code & header names to be PCRE1

No changes.

  perf: add a performance comparison test of grep -E and -P

NEW: Instead of my huge perl -MBenchmark one-liner I wrote a t/perf/
test for grep engine comparison which I'm citing for subsequent
changes.

  grep: add support for the PCRE v1 JIT API

NEW: Adds JIT support for PCRE v1.

  grep: add support for PCRE v2

Lots of changes:

 - Much smaller and hopefully less confusing commit message &
   discussion of performance differences.

 - Much improved PCRE v2 API use. The Zoltán Herczeg on the pcre-dev
   list helped a lot with that. Now less buggy & more performant.

 - Plugged a trivial memory leak I missed in v1.

Ævar Arnfjörð Bjarmason (13):
  grep: remove redundant regflags assignment under PCRE
  Makefile & configure: reword outdated comment about PCRE
  grep: add a test for backreferences in PCRE patterns
  log: add exhaustive tests for pattern style options & config
  log: add -P as a synonym for --perl-regexp
  grep & rev-list doc: stop promising libpcre for --perl-regexp
  grep: make grep.patternType=[pcre|pcre1] a synonym for "perl"
  test-lib: rename the LIBPCRE prerequisite to PCRE
  grep: change the internal PCRE macro names to be PCRE1
  grep: change the internal PCRE code & header names to be PCRE1
  perf: add a performance comparison test of grep -E and -P
  grep: add support for the PCRE v1 JIT API
  grep: add support for PCRE v2

 Documentation/config.txt           |   7 ++
 Documentation/git-grep.txt         |   4 +-
 Documentation/rev-list-options.txt |   6 +-
 Makefile                           |  28 ++++-
 configure.ac                       |  61 +++++++++-
 grep.c                             | 233 ++++++++++++++++++++++++++++++++-----
 grep.h                             |  36 +++++-
 revision.c                         |   2 +-
 t/README                           |  16 ++-
 t/perf/p7820-grep-engines.sh       |  25 ++++
 t/t4202-log.sh                     |  86 +++++++++++++-
 t/t7810-grep.sh                    |  69 ++++++++---
 t/t7812-grep-icase-non-ascii.sh    |   4 +-
 t/t7813-grep-icase-iso.sh          |  11 +-
 t/test-lib.sh                      |   4 +-
 15 files changed, 516 insertions(+), 76 deletions(-)
 create mode 100755 t/perf/p7820-grep-engines.sh

-- 
2.11.0

[PATCH v2 01/13] grep: remove redundant regflags assignment under PCRE

[Ævar Arnfjörð Bjarmason]

Remove a redundant assignment to the "regflags" variable. This
variable is only used for POSIX regular expression matching, not when
the PCRE library is used.

This redundant assignment was added as a result of copy/paste
programming in commit 84befcd0a4 ("grep: add a grep.patternType
configuration setting", 2012-08-03). That commit modified already
working code in commit cca2c172e0 ("git-grep: do not die upon -F/-P
when grep.extendedRegexp is set.", 2011-05-09) which didn't assign to
regflags when under PCRE.

Revert back to that behavior, more to reduce "wait this is used under
PCRE how?" confusion when reading the code, than to to save ourselves
trivial CPU cycles by removing one assignment.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 grep.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/grep.c b/grep.c
index 47cee45067..59ae7809f2 100644
--- a/grep.c
+++ b/grep.c
@@ -197,7 +197,6 @@ static void grep_set_pattern_type_option(enum grep_pattern_type pattern_type, st
 	case GREP_PATTERN_TYPE_PCRE:
 		opt->fixed = 0;
 		opt->pcre = 1;
-		opt->regflags &= ~REG_EXTENDED;
 		break;
 	}
 }
-- 
2.11.0

[PATCH v2 02/13] Makefile & configure: reword outdated comment about PCRE

[Ævar Arnfjörð Bjarmason]

Reword an outdated comment which suggests that only git-grep can use
PCRE.

This comment was added back when PCRE support was initially added in
commit 63e7e9d8b6 ("git-grep: Learn PCRE", 2011-05-09), and was true
at the time.

It hasn't been telling the full truth since git-log learned to use
PCRE with --grep in commit 727b6fc3ed ("log --grep: accept
--basic-regexp and --perl-regexp", 2012-10-03), and more importantly
is likely to get more inaccurate over time as more use is made of PCRE
in other areas.

Reword it to be more future-proof, and to more clearly explain that
this enables user-initiated runtime behavior.

Copy/pasting this so much in configure.ac is lame, these Makefile-like
flags aren't even used by autoconf, just the corresponding
--with[out]-* options. But copy/pasting the comments that make sense
for the Makefile to configure.ac where they make less sence is the
pattern everything else follows in that file. I'm not going to war
against that as part of this change, just following the existing
pattern.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Makefile     |  6 ++++--
 configure.ac | 12 ++++++++----
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/Makefile b/Makefile
index d595ea3837..516f57aac8 100644
--- a/Makefile
+++ b/Makefile
@@ -24,8 +24,10 @@ all::
 # Define NO_OPENSSL environment variable if you do not have OpenSSL.
 # This also implies BLK_SHA1.
 #
-# Define USE_LIBPCRE if you have and want to use libpcre. git-grep will be
-# able to use Perl-compatible regular expressions.
+# Define USE_LIBPCRE if you have and want to use libpcre. Various
+# commands such as log and grep offer runtime options to use
+# Perl-compatible regular expressions instead of standard or extended
+# POSIX regular expressions.
 #
 # Define LIBPCREDIR=/foo/bar if your libpcre header and library files are in
 # /foo/bar/include and /foo/bar/lib directories.
diff --git a/configure.ac b/configure.ac
index 128165529f..deeb968daa 100644
--- a/configure.ac
+++ b/configure.ac
@@ -250,8 +250,10 @@ AS_HELP_STRING([--with-openssl],[use OpenSSL library (default is YES)])
 AS_HELP_STRING([],              [ARG can be prefix for openssl library and headers]),
 GIT_PARSE_WITH([openssl]))
 
-# Define USE_LIBPCRE if you have and want to use libpcre. git-grep will be
-# able to use Perl-compatible regular expressions.
+# Define USE_LIBPCRE if you have and want to use libpcre. Various
+# commands such as log and grep offer runtime options to use
+# Perl-compatible regular expressions instead of standard or extended
+# POSIX regular expressions.
 #
 # Define LIBPCREDIR=/foo/bar if your libpcre header and library files are in
 # /foo/bar/include and /foo/bar/lib directories.
@@ -499,8 +501,10 @@ GIT_CONF_SUBST([NEEDS_SSL_WITH_CRYPTO])
 GIT_CONF_SUBST([NO_OPENSSL])
 
 #
-# Define USE_LIBPCRE if you have and want to use libpcre. git-grep will be
-# able to use Perl-compatible regular expressions.
+# Define USE_LIBPCRE if you have and want to use libpcre. Various
+# commands such as log and grep offer runtime options to use
+# Perl-compatible regular expressions instead of standard or extended
+# POSIX regular expressions.
 #
 
 if test -n "$USE_LIBPCRE"; then
-- 
2.11.0

[PATCH v2 03/13] grep: add a test for backreferences in PCRE patterns

[Ævar Arnfjörð Bjarmason]

Add a test for backreferences such as (.)\1 in PCRE patterns. This
test ensures that the PCRE_NO_AUTO_CAPTURE option isn't turned
on. Before this change turning it on would break these sort of
patterns, but wouldn't break any tests.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 t/t7810-grep.sh | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/t/t7810-grep.sh b/t/t7810-grep.sh
index cee42097b0..8baed0f37d 100755
--- a/t/t7810-grep.sh
+++ b/t/t7810-grep.sh
@@ -1102,6 +1102,13 @@ test_expect_success LIBPCRE 'grep -P -w pattern' '
 	test_cmp expected actual
 '
 
+test_expect_success PCRE 'grep -P backreferences work (the PCRE NO_AUTO_CAPTURE flag is not set)' '
+	git grep -P -h "(?P<one>.)(?P=one)" hello_world >actual &&
+	test_cmp hello_world actual &&
+	git grep -P -h "(.)\1" hello_world >actual &&
+	test_cmp hello_world actual
+'
+
 test_expect_success 'grep -G invalidpattern properly dies ' '
 	test_must_fail git grep -G "a["
 '
-- 
2.11.0

[PATCH v2 04/13] log: add exhaustive tests for pattern style options & config

[Ævar Arnfjörð Bjarmason]

Add exhaustive tests for how the different grep.patternType options &
the corresponding command-line options affect git-log.

Before this change it was possible to patch revision.c so that the
--basic-regexp option was synonymous with --extended-regexp, and
--perl-regexp wasn't recognized at all, and still have 100% of the
test suite pass.

This was because the first test being modified here, added in commit
34a4ae55b2 ("log --grep: use the same helper to set -E/-F options as
"git grep"", 2012-10-03), didn't actually check whether we'd enabled
extended regular expressions as distinct from re-toggling non-fixed
string support.

Fix that by changing the pattern to a pattern that'll only match if
--extended-regexp option is provided, but won't match under the
default --basic-regexp option.

Other potential regressions were possible since there were no tests
for the rest of the combinations of grep.patternType configuration
toggles & corresponding git-log command-line options. Add exhaustive
tests for those.

The patterns being passed to fixed/basic/extended/PCRE are carefully
crafted to return the wrong thing if the grep engine were to pick any
other matching method than the one it's told to use.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 t/t4202-log.sh | 77 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 76 insertions(+), 1 deletion(-)

diff --git a/t/t4202-log.sh b/t/t4202-log.sh
index f577990716..fc186f10ea 100755
--- a/t/t4202-log.sh
+++ b/t/t4202-log.sh
@@ -262,7 +262,23 @@ test_expect_success 'log --grep -i' '
 
 test_expect_success 'log -F -E --grep=<ere> uses ere' '
 	echo second >expect &&
-	git log -1 --pretty="tformat:%s" -F -E --grep=s.c.nd >actual &&
+	git log -1 --pretty="tformat:%s" -F -E --grep="(s).c.nd" >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success LIBPCRE 'log -F -E --perl-regexp --grep=<pcre> uses PCRE' '
+	test_when_finished "rm -rf num_commits" &&
+	git init num_commits &&
+	(
+		cd num_commits &&
+		test_commit 1d &&
+		test_commit 2e
+	) &&
+	echo 2e >expect &&
+	git -C num_commits log -1 --pretty="tformat:%s" -F -E --perl-regexp --grep="[\d]" >actual &&
+	test_cmp expect actual &&
+	echo 1d >expect &&
+	git -C num_commits log -1 --pretty="tformat:%s" -F -E --grep="[\d]" >actual &&
 	test_cmp expect actual
 '
 
@@ -280,6 +296,65 @@ test_expect_success 'log with grep.patternType configuration and command line' '
 	test_cmp expect actual
 '
 
+test_expect_success 'log with various grep.patternType configurations & command-lines' '
+	git init pattern-type &&
+	(
+		cd pattern-type &&
+		test_commit 1 file A &&
+		test_commit "(1|2)" file B &&
+
+		echo "(1|2)" >expect.fixed &&
+		cp expect.fixed expect.basic &&
+		cp expect.fixed expect.extended &&
+		cp expect.fixed expect.perl &&
+
+		git -c grep.patternType=fixed log --pretty=tformat:%s \
+			--grep="(1|2)" >actual.fixed &&
+		git -c grep.patternType=basic log --pretty=tformat:%s \
+			--grep="(.|.)" >actual.basic &&
+		git -c grep.patternType=extended log --pretty=tformat:%s \
+			--grep="\|2" >actual.extended &&
+		if test_have_prereq LIBPCRE
+		then
+			git -c grep.patternType=perl log --pretty=tformat:%s \
+				--grep="[\d]\|" >actual.perl
+		fi &&
+		test_cmp expect.fixed actual.fixed &&
+		test_cmp expect.basic actual.basic &&
+		test_cmp expect.extended actual.extended &&
+		if test_have_prereq LIBPCRE
+		then
+			test_cmp expect.perl actual.perl
+		fi &&
+
+		git log --pretty=tformat:%s -F \
+			--grep="(1|2)" >actual.fixed.short-arg &&
+		git log --pretty=tformat:%s -E \
+			--grep="\|2" >actual.extended.short-arg &&
+		test_cmp expect.fixed actual.fixed.short-arg &&
+		test_cmp expect.extended actual.extended.short-arg &&
+
+		git log --pretty=tformat:%s --fixed-strings \
+			--grep="(1|2)" >actual.fixed.long-arg &&
+		git log --pretty=tformat:%s --basic-regexp \
+			--grep="(.|.)" >actual.basic.long-arg &&
+		git log --pretty=tformat:%s --extended-regexp \
+			--grep="\|2" >actual.extended.long-arg &&
+		if test_have_prereq LIBPCRE
+		then
+			git log --pretty=tformat:%s --perl-regexp \
+				--grep="[\d]\|" >actual.perl.long-arg
+		fi &&
+		test_cmp expect.fixed actual.fixed.long-arg &&
+		test_cmp expect.basic actual.basic.long-arg &&
+		test_cmp expect.extended actual.extended.long-arg &&
+		if test_have_prereq LIBPCRE
+		then
+			test_cmp expect.perl actual.perl.long-arg
+		fi
+	)
+'
+
 cat > expect <<EOF
 * Second
 * sixth
-- 
2.11.0

[PATCH v2 05/13] log: add -P as a synonym for --perl-regexp

[Ævar Arnfjörð Bjarmason]

Add a short -P option as a synonym for the longer --perl-regexp, for
consistency with the options the corresponding grep invocations
accept.

This was intentionally omitted in commit 727b6fc3ed ("log --grep:
accept --basic-regexp and --perl-regexp", 2012-10-03) for unspecified
future use.

Since nothing has come along in over 4 1/2 years that's wanted to use
it, it's more valuable to make it consistent with "grep" than to keep
it open for future use, and to avoid the confusion of -P meaning
different things for grep & log, as is the case with the -G option.

As noted in the aforementioned commit the --basic-regexp option can't
have a corresponding -G argument, as the log command already uses that
for -G<regex>.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Documentation/rev-list-options.txt | 1 +
 revision.c                         | 2 +-
 t/t4202-log.sh                     | 9 +++++++++
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/Documentation/rev-list-options.txt b/Documentation/rev-list-options.txt
index a02f7324c0..5b7fa49a7f 100644
--- a/Documentation/rev-list-options.txt
+++ b/Documentation/rev-list-options.txt
@@ -91,6 +91,7 @@ endif::git-rev-list[]
 	Consider the limiting patterns to be fixed strings (don't interpret
 	pattern as a regular expression).
 
+-P::
 --perl-regexp::
 	Consider the limiting patterns to be Perl-compatible regular expressions.
 	Requires libpcre to be compiled in.
diff --git a/revision.c b/revision.c
index 7ff61ff5f7..03a3a012de 100644
--- a/revision.c
+++ b/revision.c
@@ -1995,7 +1995,7 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
 		DIFF_OPT_SET(&revs->diffopt, PICKAXE_IGNORE_CASE);
 	} else if (!strcmp(arg, "--fixed-strings") || !strcmp(arg, "-F")) {
 		revs->grep_filter.pattern_type_option = GREP_PATTERN_TYPE_FIXED;
-	} else if (!strcmp(arg, "--perl-regexp")) {
+	} else if (!strcmp(arg, "--perl-regexp") || !strcmp(arg, "-P")) {
 		revs->grep_filter.pattern_type_option = GREP_PATTERN_TYPE_PCRE;
 	} else if (!strcmp(arg, "--all-match")) {
 		revs->grep_filter.all_match = 1;
diff --git a/t/t4202-log.sh b/t/t4202-log.sh
index fc186f10ea..06acc848b8 100755
--- a/t/t4202-log.sh
+++ b/t/t4202-log.sh
@@ -331,8 +331,17 @@ test_expect_success 'log with various grep.patternType configurations & command-
 			--grep="(1|2)" >actual.fixed.short-arg &&
 		git log --pretty=tformat:%s -E \
 			--grep="\|2" >actual.extended.short-arg &&
+		if test_have_prereq PCRE
+		then
+			git log --pretty=tformat:%s -P \
+				--grep="[\d]\|" >actual.perl.short-arg
+		fi &&
 		test_cmp expect.fixed actual.fixed.short-arg &&
 		test_cmp expect.extended actual.extended.short-arg &&
+		if test_have_prereq PCRE
+		then
+			test_cmp expect.perl actual.perl.short-arg
+		fi &&
 
 		git log --pretty=tformat:%s --fixed-strings \
 			--grep="(1|2)" >actual.fixed.long-arg &&
-- 
2.11.0

[PATCH v2 06/13] grep & rev-list doc: stop promising libpcre for --perl-regexp

[Ævar Arnfjörð Bjarmason]

Stop promising in our grep & rev-list options documentation that we're
always going to be using libpcre when given the --perl-regexp option.

Instead talk about using "Perl-compatible regular expressions" and
using "the PCRE library". Saying "libpcre" strongly suggests that we
might be talking about libpcre.so, which is always going to be v1.

Not only do does the documentation now align more clearly with future
plans, but it should be more easily readable to the layman.

This is for preparation for libpcre2 support, which in the future may
be powering the --perl-regexp option by default, depending on how Git
is compiled.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Documentation/git-grep.txt         | 4 ++--
 Documentation/rev-list-options.txt | 5 +++--
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/Documentation/git-grep.txt b/Documentation/git-grep.txt
index 71f32f3508..e42ba83c42 100644
--- a/Documentation/git-grep.txt
+++ b/Documentation/git-grep.txt
@@ -161,8 +161,8 @@ OPTIONS
 
 -P::
 --perl-regexp::
-	Use Perl-compatible regexp for patterns. Requires libpcre to be
-	compiled in.
+	Use Perl-compatible regular expressions for patterns. Uses the
+	PCRE library, which Git needs to be compiled against.
 
 -F::
 --fixed-strings::
diff --git a/Documentation/rev-list-options.txt b/Documentation/rev-list-options.txt
index 5b7fa49a7f..565cde636e 100644
--- a/Documentation/rev-list-options.txt
+++ b/Documentation/rev-list-options.txt
@@ -93,8 +93,9 @@ endif::git-rev-list[]
 
 -P::
 --perl-regexp::
-	Consider the limiting patterns to be Perl-compatible regular expressions.
-	Requires libpcre to be compiled in.
+	Consider the limiting patterns to be Perl-compatible regular
+	expressions. Uses the PCRE library, which Git needs to be
+	compiled against.
 
 --remove-empty::
 	Stop when a given path disappears from the tree.
-- 
2.11.0

[PATCH v2 07/13] grep: make grep.patternType=[pcre|pcre1] a synonym for "perl"

[Ævar Arnfjörð Bjarmason]

Make the pattern types "pcre" & "pcre1" synonyms for the long-standing
"perl" grep.patternType.

This change is part of a longer patch series to add pcre2 support to
Git. It's nice to be able to performance test PCRE v1 v.s. v2 without
having to recompile git, and doing that via grep.patternType makes
sense.

However, just adding "pcre2" when we only have "perl" would be
confusing, so start by adding a "pcre" & "pcre1" synonym.

In the future "perl" and "pcre" might be changed to default to "pcre2"
instead of "pcre1", and depending on how Git is compiled the more
specific "pcre1" or "pcre2" pattern types might produce an error.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Documentation/config.txt |  9 +++++++++
 grep.c                   |  4 +++-
 t/t7810-grep.sh          | 10 ++++++++++
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 475e874d51..5ef12d0694 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -1624,6 +1624,15 @@ grep.patternType::
 	'fixed', or 'perl' will enable the `--basic-regexp`, `--extended-regexp`,
 	`--fixed-strings`, or `--perl-regexp` option accordingly, while the
 	value 'default' will return to the default matching behavior.
++
+The 'pcre' and 'pcre1' values are synonyms for 'perl'. The other
+values starting with 'pcre' are reserved for future use, e.g. if we'd
+like to use 'pcre2' for the PCRE v2 library.
++
+In the future 'perl' and 'pcre' might become synonyms for some other
+implementation or PCRE version, such as 'pcre2', while the more
+specific 'pcre1' & 'pcre2' might throw errors depending on whether git
+is compiled to include those libraries.
 
 grep.extendedRegexp::
 	If set to true, enable `--extended-regexp` option by default. This
diff --git a/grep.c b/grep.c
index 59ae7809f2..506545c0ee 100644
--- a/grep.c
+++ b/grep.c
@@ -60,7 +60,9 @@ static int parse_pattern_type_arg(const char *opt, const char *arg)
 		return GREP_PATTERN_TYPE_ERE;
 	else if (!strcmp(arg, "fixed"))
 		return GREP_PATTERN_TYPE_FIXED;
-	else if (!strcmp(arg, "perl"))
+	else if (!strcmp(arg, "perl") ||
+		 !strcmp(arg, "pcre") ||
+		 !strcmp(arg, "pcre1"))
 		return GREP_PATTERN_TYPE_PCRE;
 	die("bad %s argument: %s", opt, arg);
 }
diff --git a/t/t7810-grep.sh b/t/t7810-grep.sh
index 8baed0f37d..0fb95c7438 100755
--- a/t/t7810-grep.sh
+++ b/t/t7810-grep.sh
@@ -1512,4 +1512,14 @@ test_expect_success 'grep does not report i-t-a and assume unchanged with -L' '
 	test_cmp expected actual
 '
 
+test_expect_success LIBPCRE "grep with grep.patternType synonyms perl/pcre/pcre1" '
+	echo "#include <stdio.h>" >expected &&
+	git -c grep.patternType=perl  grep -h --no-line-number "st(?=dio)" >actual &&
+	test_cmp expected actual &&
+	git -c grep.patternType=pcre  grep -h --no-line-number "st(?=dio)" >actual &&
+	test_cmp expected actual &&
+	git -c grep.patternType=pcre1 grep -h --no-line-number "st(?=dio)" >actual &&
+	test_cmp expected actual
+'
+
 test_done
-- 
2.11.0

[PATCH v2 08/13] test-lib: rename the LIBPCRE prerequisite to PCRE

[Ævar Arnfjörð Bjarmason]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
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Rename the LIBPCRE prerequisite to PCRE. This is for preparation for
libpcre2 support, where having just "LIBPCRE" would be confusing as it
implies v1 of the library.

None of these tests are incompatible between versions 1 & 2 of
libpcre, it's less confusing to give them a more general name to make
it clear that they work on both library versions.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 t/README                        |  4 ++--
 t/t4202-log.sh                  | 10 +++++-----
 t/t7810-grep.sh                 | 30 +++++++++++++++---------------
 t/t7812-grep-icase-non-ascii.sh |  4 ++--
 t/t7813-grep-icase-iso.sh       |  2 +-
 t/test-lib.sh                   |  2 +-
 6 files changed, 26 insertions(+), 26 deletions(-)

diff --git a/t/README b/t/README
index ab386c3681..a90cb62583 100644
--- a/t/README
+++ b/t/README
@@ -803,9 +803,9 @@ use these, and "test_set_prereq" for how to define your own.
    Test is not run by root user, and an attempt to write to an
    unwritable file is expected to fail correctly.
 
- - LIBPCRE
+ - PCRE
 
-   Git was compiled with USE_LIBPCRE=YesPlease. Wrap any tests
+   Git was compiled with support for PCRE. Wrap any tests
    that use git-grep --perl-regexp or git-grep -P in these.
 
  - CASE_INSENSITIVE_FS
diff --git a/t/t4202-log.sh b/t/t4202-log.sh
index 06acc848b8..0b5f808ca3 100755
--- a/t/t4202-log.sh
+++ b/t/t4202-log.sh
@@ -266,7 +266,7 @@ test_expect_success 'log -F -E --grep=<ere> uses ere' '
 	test_cmp expect actual
 '
 
-test_expect_success LIBPCRE 'log -F -E --perl-regexp --grep=<pcre> uses PCRE' '
+test_expect_success PCRE 'log -F -E --perl-regexp --grep=<pcre> uses PCRE' '
 	test_when_finished "rm -rf num_commits" &&
 	git init num_commits &&
 	(
@@ -314,7 +314,7 @@ test_expect_success 'log with various grep.patternType configurations & command-
 			--grep="(.|.)" >actual.basic &&
 		git -c grep.patternType=extended log --pretty=tformat:%s \
 			--grep="\|2" >actual.extended &&
-		if test_have_prereq LIBPCRE
+		if test_have_prereq PCRE
 		then
 			git -c grep.patternType=perl log --pretty=tformat:%s \
 				--grep="[\d]\|" >actual.perl
@@ -322,7 +322,7 @@ test_expect_success 'log with various grep.patternType configurations & command-
 		test_cmp expect.fixed actual.fixed &&
 		test_cmp expect.basic actual.basic &&
 		test_cmp expect.extended actual.extended &&
-		if test_have_prereq LIBPCRE
+		if test_have_prereq PCRE
 		then
 			test_cmp expect.perl actual.perl
 		fi &&
@@ -349,7 +349,7 @@ test_expect_success 'log with various grep.patternType configurations & command-
 			--grep="(.|.)" >actual.basic.long-arg &&
 		git log --pretty=tformat:%s --extended-regexp \
 			--grep="\|2" >actual.extended.long-arg &&
-		if test_have_prereq LIBPCRE
+		if test_have_prereq PCRE
 		then
 			git log --pretty=tformat:%s --perl-regexp \
 				--grep="[\d]\|" >actual.perl.long-arg
@@ -357,7 +357,7 @@ test_expect_success 'log with various grep.patternType configurations & command-
 		test_cmp expect.fixed actual.fixed.long-arg &&
 		test_cmp expect.basic actual.basic.long-arg &&
 		test_cmp expect.extended actual.extended.long-arg &&
-		if test_have_prereq LIBPCRE
+		if test_have_prereq PCRE
 		then
 			test_cmp expect.perl actual.perl.long-arg
 		fi
diff --git a/t/t7810-grep.sh b/t/t7810-grep.sh
index 0fb95c7438..f929b447e9 100755
--- a/t/t7810-grep.sh
+++ b/t/t7810-grep.sh
@@ -275,7 +275,7 @@ do
 		test_cmp expected actual
 	'
 
-	test_expect_success LIBPCRE "grep $L with grep.patterntype=perl" '
+	test_expect_success PCRE "grep $L with grep.patterntype=perl" '
 		echo "${HC}ab:a+b*c" >expected &&
 		git -c grep.patterntype=perl grep "a\x{2b}b\x{2a}c" $H ab >actual &&
 		test_cmp expected actual
@@ -1053,12 +1053,12 @@ hello.c:int main(int argc, const char **argv)
 hello.c:	printf("Hello world.\n");
 EOF
 
-test_expect_success LIBPCRE 'grep --perl-regexp pattern' '
+test_expect_success PCRE 'grep --perl-regexp pattern' '
 	git grep --perl-regexp "\p{Ps}.*?\p{Pe}" hello.c >actual &&
 	test_cmp expected actual
 '
 
-test_expect_success LIBPCRE 'grep -P pattern' '
+test_expect_success PCRE 'grep -P pattern' '
 	git grep -P "\p{Ps}.*?\p{Pe}" hello.c >actual &&
 	test_cmp expected actual
 '
@@ -1070,13 +1070,13 @@ test_expect_success 'grep pattern with grep.extendedRegexp=true' '
 	test_cmp empty actual
 '
 
-test_expect_success LIBPCRE 'grep -P pattern with grep.extendedRegexp=true' '
+test_expect_success PCRE 'grep -P pattern with grep.extendedRegexp=true' '
 	git -c grep.extendedregexp=true \
 		grep -P "\p{Ps}.*?\p{Pe}" hello.c >actual &&
 	test_cmp expected actual
 '
 
-test_expect_success LIBPCRE 'grep -P -v pattern' '
+test_expect_success PCRE 'grep -P -v pattern' '
 	{
 		echo "ab:a+b*c"
 		echo "ab:a+bc"
@@ -1085,7 +1085,7 @@ test_expect_success LIBPCRE 'grep -P -v pattern' '
 	test_cmp expected actual
 '
 
-test_expect_success LIBPCRE 'grep -P -i pattern' '
+test_expect_success PCRE 'grep -P -i pattern' '
 	cat >expected <<-EOF &&
 	hello.c:	printf("Hello world.\n");
 	EOF
@@ -1093,7 +1093,7 @@ test_expect_success LIBPCRE 'grep -P -i pattern' '
 	test_cmp expected actual
 '
 
-test_expect_success LIBPCRE 'grep -P -w pattern' '
+test_expect_success PCRE 'grep -P -w pattern' '
 	{
 		echo "hello_world:Hello world"
 		echo "hello_world:HeLLo world"
@@ -1125,11 +1125,11 @@ test_expect_success 'grep invalidpattern properly dies with grep.patternType=ext
 	test_must_fail git -c grep.patterntype=extended grep "a["
 '
 
-test_expect_success LIBPCRE 'grep -P invalidpattern properly dies ' '
+test_expect_success PCRE 'grep -P invalidpattern properly dies ' '
 	test_must_fail git grep -P "a["
 '
 
-test_expect_success LIBPCRE 'grep invalidpattern properly dies with grep.patternType=perl' '
+test_expect_success PCRE 'grep invalidpattern properly dies with grep.patternType=perl' '
 	test_must_fail git -c grep.patterntype=perl grep "a["
 '
 
@@ -1198,13 +1198,13 @@ test_expect_success 'grep pattern with grep.patternType=fixed, =basic, =perl, =e
 	test_cmp expected actual
 '
 
-test_expect_success LIBPCRE 'grep -G -F -E -P pattern' '
+test_expect_success PCRE 'grep -G -F -E -P pattern' '
 	echo "d0:0" >expected &&
 	git grep -G -F -E -P "[\d]" d0 >actual &&
 	test_cmp expected actual
 '
 
-test_expect_success LIBPCRE 'grep pattern with grep.patternType=fixed, =basic, =extended, =perl' '
+test_expect_success PCRE 'grep pattern with grep.patternType=fixed, =basic, =extended, =perl' '
 	echo "d0:0" >expected &&
 	git \
 		-c grep.patterntype=fixed \
@@ -1215,7 +1215,7 @@ test_expect_success LIBPCRE 'grep pattern with grep.patternType=fixed, =basic, =
 	test_cmp expected actual
 '
 
-test_expect_success LIBPCRE 'grep -P pattern with grep.patternType=fixed' '
+test_expect_success PCRE 'grep -P pattern with grep.patternType=fixed' '
 	echo "ab:a+b*c" >expected &&
 	git \
 		-c grep.patterntype=fixed \
@@ -1350,12 +1350,12 @@ space: line with leading space2
 space: line with leading space3
 EOF
 
-test_expect_success LIBPCRE 'grep -E "^ "' '
+test_expect_success PCRE 'grep -E "^ "' '
 	git grep -E "^ " space >actual &&
 	test_cmp expected actual
 '
 
-test_expect_success LIBPCRE 'grep -P "^ "' '
+test_expect_success PCRE 'grep -P "^ "' '
 	git grep -P "^ " space >actual &&
 	test_cmp expected actual
 '
@@ -1512,7 +1512,7 @@ test_expect_success 'grep does not report i-t-a and assume unchanged with -L' '
 	test_cmp expected actual
 '
 
-test_expect_success LIBPCRE "grep with grep.patternType synonyms perl/pcre/pcre1" '
+test_expect_success PCRE "grep with grep.patternType synonyms perl/pcre/pcre1" '
 	echo "#include <stdio.h>" >expected &&
 	git -c grep.patternType=perl  grep -h --no-line-number "st(?=dio)" >actual &&
 	test_cmp expected actual &&
diff --git a/t/t7812-grep-icase-non-ascii.sh b/t/t7812-grep-icase-non-ascii.sh
index 169fd8d706..04a61cb8e0 100755
--- a/t/t7812-grep-icase-non-ascii.sh
+++ b/t/t7812-grep-icase-non-ascii.sh
@@ -20,13 +20,13 @@ test_expect_success REGEX_LOCALE 'grep literal string, no -F' '
 	git grep -i "TILRAUN: HALLÓ HEIMUR!"
 '
 
-test_expect_success GETTEXT_LOCALE,LIBPCRE 'grep pcre utf-8 icase' '
+test_expect_success GETTEXT_LOCALE,PCRE 'grep pcre utf-8 icase' '
 	git grep --perl-regexp    "TILRAUN: H.lló Heimur!" &&
 	git grep --perl-regexp -i "TILRAUN: H.lló Heimur!" &&
 	git grep --perl-regexp -i "TILRAUN: H.LLÓ HEIMUR!"
 '
 
-test_expect_success GETTEXT_LOCALE,LIBPCRE 'grep pcre utf-8 string with "+"' '
+test_expect_success GETTEXT_LOCALE,PCRE 'grep pcre utf-8 string with "+"' '
 	test_write_lines "TILRAUN: Hallóó Heimur!" >file2 &&
 	git add file2 &&
 	git grep -l --perl-regexp "TILRAUN: H.lló+ Heimur!" >actual &&
diff --git a/t/t7813-grep-icase-iso.sh b/t/t7813-grep-icase-iso.sh
index efef7fb81f..701e08a8e5 100755
--- a/t/t7813-grep-icase-iso.sh
+++ b/t/t7813-grep-icase-iso.sh
@@ -11,7 +11,7 @@ test_expect_success GETTEXT_ISO_LOCALE 'setup' '
 	export LC_ALL
 '
 
-test_expect_success GETTEXT_ISO_LOCALE,LIBPCRE 'grep pcre string' '
+test_expect_success GETTEXT_ISO_LOCALE,PCRE 'grep pcre string' '
 	git grep --perl-regexp -i "TILRAUN: H.lló Heimur!" &&
 	git grep --perl-regexp -i "TILRAUN: H.LLÓ HEIMUR!"
 '
diff --git a/t/test-lib.sh b/t/test-lib.sh
index 13b5696822..6abf1d1918 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -1010,7 +1010,7 @@ esac
 ( COLUMNS=1 && test $COLUMNS = 1 ) && test_set_prereq COLUMNS_CAN_BE_1
 test -z "$NO_PERL" && test_set_prereq PERL
 test -z "$NO_PYTHON" && test_set_prereq PYTHON
-test -n "$USE_LIBPCRE" && test_set_prereq LIBPCRE
+test -n "$USE_LIBPCRE" && test_set_prereq PCRE
 test -z "$NO_GETTEXT" && test_set_prereq GETTEXT
 
 # Can we rely on git's output in the C locale?
-- 
2.11.0

[PATCH v2 09/13] grep: change the internal PCRE macro names to be PCRE1

[Ævar Arnfjörð Bjarmason]

Change the internal USE_LIBPCRE define, & build options flag to use a
naming convention ending in PCRE1, without changing the long-standing
USE_LIBPCRE Makefile flag which enables this code.

This is for preparation for libpcre2 support where having things like
USE_LIBPCRE and USE_LIBPCRE2 in any more places than we absolutely
need to for backwards compatibility with old Makefile arguments would
be confusing.

In some ways it would be better to change everything that now uses
USE_LIBPCRE to use USE_LIBPCRE1, and to make specifying
USE_LIBPCRE (or --with-pcre) an error. This would impose a one-time
burden on packagers of git to s/USE_LIBPCRE/USE_LIBPCRE1/ in their
build scripts.

However I'd like to leave the door open to making
USE_LIBPCRE=YesPlease eventually mean USE_LIBPCRE2=YesPlease,
i.e. once PCRE v2 is ubiquitous enough that it makes sense to make it
the default.

This code and the USE_LIBPCRE Makefile argument was added in commit
63e7e9d8b6 ("git-grep: Learn PCRE", 2011-05-09). At the time there was
no indication that the PCRE project would release an entirely new &
incompatible API around 3 years later.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Makefile      | 4 ++--
 grep.c        | 6 +++---
 grep.h        | 2 +-
 t/test-lib.sh | 2 +-
 4 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/Makefile b/Makefile
index 516f57aac8..cd19980906 100644
--- a/Makefile
+++ b/Makefile
@@ -1084,7 +1084,7 @@ ifdef NO_LIBGEN_H
 endif
 
 ifdef USE_LIBPCRE
-	BASIC_CFLAGS += -DUSE_LIBPCRE
+	BASIC_CFLAGS += -DUSE_LIBPCRE1
 	ifdef LIBPCREDIR
 		BASIC_CFLAGS += -I$(LIBPCREDIR)/include
 		EXTLIBS += -L$(LIBPCREDIR)/$(lib) $(CC_LD_DYNPATH)$(LIBPCREDIR)/$(lib)
@@ -2236,7 +2236,7 @@ GIT-BUILD-OPTIONS: FORCE
 	@echo TAR=\''$(subst ','\'',$(subst ','\'',$(TAR)))'\' >>$@+
 	@echo NO_CURL=\''$(subst ','\'',$(subst ','\'',$(NO_CURL)))'\' >>$@+
 	@echo NO_EXPAT=\''$(subst ','\'',$(subst ','\'',$(NO_EXPAT)))'\' >>$@+
-	@echo USE_LIBPCRE=\''$(subst ','\'',$(subst ','\'',$(USE_LIBPCRE)))'\' >>$@+
+	@echo USE_LIBPCRE1=\''$(subst ','\'',$(subst ','\'',$(USE_LIBPCRE)))'\' >>$@+
 	@echo NO_PERL=\''$(subst ','\'',$(subst ','\'',$(NO_PERL)))'\' >>$@+
 	@echo NO_PYTHON=\''$(subst ','\'',$(subst ','\'',$(NO_PYTHON)))'\' >>$@+
 	@echo NO_UNIX_SOCKETS=\''$(subst ','\'',$(subst ','\'',$(NO_UNIX_SOCKETS)))'\' >>$@+
diff --git a/grep.c b/grep.c
index 506545c0ee..2535abd214 100644
--- a/grep.c
+++ b/grep.c
@@ -325,7 +325,7 @@ static NORETURN void compile_regexp_failed(const struct grep_pat *p,
 	die("%s'%s': %s", where, p->pattern, error);
 }
 
-#ifdef USE_LIBPCRE
+#ifdef USE_LIBPCRE1
 static void compile_pcre_regexp(struct grep_pat *p, const struct grep_opt *opt)
 {
 	const char *error;
@@ -377,7 +377,7 @@ static void free_pcre_regexp(struct grep_pat *p)
 	pcre_free(p->pcre_extra_info);
 	pcre_free((void *)p->pcre_tables);
 }
-#else /* !USE_LIBPCRE */
+#else /* !USE_LIBPCRE1 */
 static void compile_pcre_regexp(struct grep_pat *p, const struct grep_opt *opt)
 {
 	die("cannot use Perl-compatible regexes when not compiled with USE_LIBPCRE");
@@ -392,7 +392,7 @@ static int pcrematch(struct grep_pat *p, const char *line, const char *eol,
 static void free_pcre_regexp(struct grep_pat *p)
 {
 }
-#endif /* !USE_LIBPCRE */
+#endif /* !USE_LIBPCRE1 */
 
 static int is_fixed(const char *s, size_t len)
 {
diff --git a/grep.h b/grep.h
index 267534ca24..073b0e4c92 100644
--- a/grep.h
+++ b/grep.h
@@ -1,7 +1,7 @@
 #ifndef GREP_H
 #define GREP_H
 #include "color.h"
-#ifdef USE_LIBPCRE
+#ifdef USE_LIBPCRE1
 #include <pcre.h>
 #else
 typedef int pcre;
diff --git a/t/test-lib.sh b/t/test-lib.sh
index 6abf1d1918..e5cfbcc36b 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -1010,7 +1010,7 @@ esac
 ( COLUMNS=1 && test $COLUMNS = 1 ) && test_set_prereq COLUMNS_CAN_BE_1
 test -z "$NO_PERL" && test_set_prereq PERL
 test -z "$NO_PYTHON" && test_set_prereq PYTHON
-test -n "$USE_LIBPCRE" && test_set_prereq PCRE
+test -n "$USE_LIBPCRE1" && test_set_prereq PCRE
 test -z "$NO_GETTEXT" && test_set_prereq GETTEXT
 
 # Can we rely on git's output in the C locale?
-- 
2.11.0

[PATCH v2 10/13] grep: change the internal PCRE code & header names to be PCRE1

[Ævar Arnfjörð Bjarmason]

Change the internal PCRE variable & function names to have a "1"
suffix. This is for preparation for libpcre2 support, where having
non-versioned names would be confusing.

The earlier "grep: change the internal PCRE macro names to be PCRE1"
change elaborates on the motivations behind this commit.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 builtin/grep.c |  4 ++--
 grep.c         | 56 ++++++++++++++++++++++++++++----------------------------
 grep.h         | 10 +++++-----
 revision.c     |  2 +-
 4 files changed, 36 insertions(+), 36 deletions(-)

diff --git a/builtin/grep.c b/builtin/grep.c
index 65070c52fc..945e9e7f2e 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -490,7 +490,7 @@ static void compile_submodule_options(const struct grep_opt *opt,
 	case GREP_PATTERN_TYPE_FIXED:
 		argv_array_push(&submodule_options, "-F");
 		break;
-	case GREP_PATTERN_TYPE_PCRE:
+	case GREP_PATTERN_TYPE_PCRE1:
 		argv_array_push(&submodule_options, "-P");
 		break;
 	case GREP_PATTERN_TYPE_UNSPECIFIED:
@@ -1018,7 +1018,7 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 			    GREP_PATTERN_TYPE_FIXED),
 		OPT_SET_INT('P', "perl-regexp", &pattern_type_arg,
 			    N_("use Perl-compatible regular expressions"),
-			    GREP_PATTERN_TYPE_PCRE),
+			    GREP_PATTERN_TYPE_PCRE1),
 		OPT_GROUP(""),
 		OPT_BOOL('n', "line-number", &opt.linenum, N_("show line numbers")),
 		OPT_NEGBIT('h', NULL, &opt.pathname, N_("don't show filenames"), 1),
diff --git a/grep.c b/grep.c
index 2535abd214..d2c87ee2c3 100644
--- a/grep.c
+++ b/grep.c
@@ -63,7 +63,7 @@ static int parse_pattern_type_arg(const char *opt, const char *arg)
 	else if (!strcmp(arg, "perl") ||
 		 !strcmp(arg, "pcre") ||
 		 !strcmp(arg, "pcre1"))
-		return GREP_PATTERN_TYPE_PCRE;
+		return GREP_PATTERN_TYPE_PCRE1;
 	die("bad %s argument: %s", opt, arg);
 }
 
@@ -180,25 +180,25 @@ static void grep_set_pattern_type_option(enum grep_pattern_type pattern_type, st
 
 	case GREP_PATTERN_TYPE_BRE:
 		opt->fixed = 0;
-		opt->pcre = 0;
+		opt->pcre1 = 0;
 		opt->regflags &= ~REG_EXTENDED;
 		break;
 
 	case GREP_PATTERN_TYPE_ERE:
 		opt->fixed = 0;
-		opt->pcre = 0;
+		opt->pcre1 = 0;
 		opt->regflags |= REG_EXTENDED;
 		break;
 
 	case GREP_PATTERN_TYPE_FIXED:
 		opt->fixed = 1;
-		opt->pcre = 0;
+		opt->pcre1 = 0;
 		opt->regflags &= ~REG_EXTENDED;
 		break;
 
-	case GREP_PATTERN_TYPE_PCRE:
+	case GREP_PATTERN_TYPE_PCRE1:
 		opt->fixed = 0;
-		opt->pcre = 1;
+		opt->pcre1 = 1;
 		break;
 	}
 }
@@ -326,7 +326,7 @@ static NORETURN void compile_regexp_failed(const struct grep_pat *p,
 }
 
 #ifdef USE_LIBPCRE1
-static void compile_pcre_regexp(struct grep_pat *p, const struct grep_opt *opt)
+static void compile_pcre1_regexp(struct grep_pat *p, const struct grep_opt *opt)
 {
 	const char *error;
 	int erroffset;
@@ -334,23 +334,23 @@ static void compile_pcre_regexp(struct grep_pat *p, const struct grep_opt *opt)
 
 	if (opt->ignore_case) {
 		if (has_non_ascii(p->pattern))
-			p->pcre_tables = pcre_maketables();
+			p->pcre1_tables = pcre_maketables();
 		options |= PCRE_CASELESS;
 	}
 	if (is_utf8_locale() && has_non_ascii(p->pattern))
 		options |= PCRE_UTF8;
 
-	p->pcre_regexp = pcre_compile(p->pattern, options, &error, &erroffset,
-				      p->pcre_tables);
-	if (!p->pcre_regexp)
+	p->pcre1_regexp = pcre_compile(p->pattern, options, &error, &erroffset,
+				      p->pcre1_tables);
+	if (!p->pcre1_regexp)
 		compile_regexp_failed(p, error);
 
-	p->pcre_extra_info = pcre_study(p->pcre_regexp, 0, &error);
-	if (!p->pcre_extra_info && error)
+	p->pcre1_extra_info = pcre_study(p->pcre1_regexp, 0, &error);
+	if (!p->pcre1_extra_info && error)
 		die("%s", error);
 }
 
-static int pcrematch(struct grep_pat *p, const char *line, const char *eol,
+static int pcre1match(struct grep_pat *p, const char *line, const char *eol,
 		regmatch_t *match, int eflags)
 {
 	int ovector[30], ret, flags = 0;
@@ -358,7 +358,7 @@ static int pcrematch(struct grep_pat *p, const char *line, const char *eol,
 	if (eflags & REG_NOTBOL)
 		flags |= PCRE_NOTBOL;
 
-	ret = pcre_exec(p->pcre_regexp, p->pcre_extra_info, line, eol - line,
+	ret = pcre_exec(p->pcre1_regexp, p->pcre1_extra_info, line, eol - line,
 			0, flags, ovector, ARRAY_SIZE(ovector));
 	if (ret < 0 && ret != PCRE_ERROR_NOMATCH)
 		die("pcre_exec failed with error code %d", ret);
@@ -371,25 +371,25 @@ static int pcrematch(struct grep_pat *p, const char *line, const char *eol,
 	return ret;
 }
 
-static void free_pcre_regexp(struct grep_pat *p)
+static void free_pcre1_regexp(struct grep_pat *p)
 {
-	pcre_free(p->pcre_regexp);
-	pcre_free(p->pcre_extra_info);
-	pcre_free((void *)p->pcre_tables);
+	pcre_free(p->pcre1_regexp);
+	pcre_free(p->pcre1_extra_info);
+	pcre_free((void *)p->pcre1_tables);
 }
 #else /* !USE_LIBPCRE1 */
-static void compile_pcre_regexp(struct grep_pat *p, const struct grep_opt *opt)
+static void compile_pcre1_regexp(struct grep_pat *p, const struct grep_opt *opt)
 {
 	die("cannot use Perl-compatible regexes when not compiled with USE_LIBPCRE");
 }
 
-static int pcrematch(struct grep_pat *p, const char *line, const char *eol,
+static int pcre1match(struct grep_pat *p, const char *line, const char *eol,
 		regmatch_t *match, int eflags)
 {
 	return 1;
 }
 
-static void free_pcre_regexp(struct grep_pat *p)
+static void free_pcre1_regexp(struct grep_pat *p)
 {
 }
 #endif /* !USE_LIBPCRE1 */
@@ -476,8 +476,8 @@ static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
 		return;
 	}
 
-	if (opt->pcre) {
-		compile_pcre_regexp(p, opt);
+	if (opt->pcre1) {
+		compile_pcre1_regexp(p, opt);
 		return;
 	}
 
@@ -833,8 +833,8 @@ void free_grep_patterns(struct grep_opt *opt)
 		case GREP_PATTERN_BODY:
 			if (p->kws)
 				kwsfree(p->kws);
-			else if (p->pcre_regexp)
-				free_pcre_regexp(p);
+			else if (p->pcre1_regexp)
+				free_pcre1_regexp(p);
 			else
 				regfree(&p->regexp);
 			free(p->pattern);
@@ -913,8 +913,8 @@ static int patmatch(struct grep_pat *p, char *line, char *eol,
 
 	if (p->fixed)
 		hit = !fixmatch(p, line, eol, match);
-	else if (p->pcre_regexp)
-		hit = !pcrematch(p, line, eol, match, eflags);
+	else if (p->pcre1_regexp)
+		hit = !pcre1match(p, line, eol, match, eflags);
 	else
 		hit = !regexec_buf(&p->regexp, line, eol - line, 1, match,
 				   eflags);
diff --git a/grep.h b/grep.h
index 073b0e4c92..fa2ab9485f 100644
--- a/grep.h
+++ b/grep.h
@@ -46,9 +46,9 @@ struct grep_pat {
 	size_t patternlen;
 	enum grep_header_field field;
 	regex_t regexp;
-	pcre *pcre_regexp;
-	pcre_extra *pcre_extra_info;
-	const unsigned char *pcre_tables;
+	pcre *pcre1_regexp;
+	pcre_extra *pcre1_extra_info;
+	const unsigned char *pcre1_tables;
 	kwset_t kws;
 	unsigned fixed:1;
 	unsigned ignore_case:1;
@@ -68,7 +68,7 @@ enum grep_pattern_type {
 	GREP_PATTERN_TYPE_BRE,
 	GREP_PATTERN_TYPE_ERE,
 	GREP_PATTERN_TYPE_FIXED,
-	GREP_PATTERN_TYPE_PCRE
+	GREP_PATTERN_TYPE_PCRE1
 };
 
 struct grep_expr {
@@ -111,7 +111,7 @@ struct grep_opt {
 	int allow_textconv;
 	int extended;
 	int use_reflog_filter;
-	int pcre;
+	int pcre1;
 	int relative;
 	int pathname;
 	int null_following_name;
diff --git a/revision.c b/revision.c
index 03a3a012de..7a10a8570a 100644
--- a/revision.c
+++ b/revision.c
@@ -1996,7 +1996,7 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
 	} else if (!strcmp(arg, "--fixed-strings") || !strcmp(arg, "-F")) {
 		revs->grep_filter.pattern_type_option = GREP_PATTERN_TYPE_FIXED;
 	} else if (!strcmp(arg, "--perl-regexp") || !strcmp(arg, "-P")) {
-		revs->grep_filter.pattern_type_option = GREP_PATTERN_TYPE_PCRE;
+		revs->grep_filter.pattern_type_option = GREP_PATTERN_TYPE_PCRE1;
 	} else if (!strcmp(arg, "--all-match")) {
 		revs->grep_filter.all_match = 1;
 	} else if (!strcmp(arg, "--invert-grep")) {
-- 
2.11.0

[PATCH v2 11/13] perf: add a performance comparison test of grep -E and -P

[Ævar Arnfjörð Bjarmason]

Add a very basic performance comparison test comparing the POSIX
extended & pcre1 engines.

I'm skipping the "basic" POSIX engine because supporting its alternate
regex syntax is hard, although it would be interesting to test it, at
least under glibc it seems to be an entirely different engine, since
it can have very different performance even for patterns that mean the
same thing under extended and non-extended POSIX regular expression
syntax.

Running this on an i7 3.4GHz Linux 3.16.0-4 Debian testing against a
checkout of linux.git & latest upstream PCRE, both PCRE and git
compiled with -O3:

    $ GIT_PERF_LARGE_REPO=~/g/linux ./run p7820-grep-engines.sh
    [...]
    Test                                                       this tree
    -----------------------------------------------------------------------------
    7820.1: extended with how.to                               0.28(1.23+0.44)
    7820.2: extended with ^how to                              0.26(1.15+0.38)
    7820.3: extended with \w+our\w*                            6.06(38.44+0.35)
    7820.4: extended with -?-?-?-?-?-?-?-?-?-?-?-----------$   0.37(1.57+0.38)
    7820.5: pcre1 with how.to                                  0.26(1.15+0.37)
    7820.6: pcre1 with ^how to                                 0.46(2.66+0.31)
    7820.7: pcre1 with \w+our\w*                               16.42(99.42+0.48)
    7820.8: pcre1 with -?-?-?-?-?-?-?-?-?-?-?-----------$      81.52(275.37+0.41)

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 t/perf/p7820-grep-engines.sh | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)
 create mode 100755 t/perf/p7820-grep-engines.sh

diff --git a/t/perf/p7820-grep-engines.sh b/t/perf/p7820-grep-engines.sh
new file mode 100755
index 0000000000..5ae42ceccc
--- /dev/null
+++ b/t/perf/p7820-grep-engines.sh
@@ -0,0 +1,25 @@
+#!/bin/sh
+
+test_description="Comparison of git-grep's regex engines"
+
+. ./perf-lib.sh
+
+test_perf_large_repo
+test_checkout_worktree
+
+for engine in extended pcre1
+do
+	# Patterns stolen from http://sljit.sourceforge.net/pcre.html
+	for pattern in \
+		'how.to' \
+		'^how to' \
+		'\w+our\w*' \
+		'-?-?-?-?-?-?-?-?-?-?-?-----------$'
+	do
+		test_perf "$engine with $pattern" "
+			git -c grep.patternType=$engine grep -- '$pattern' || :
+		"
+	done
+done
+
+test_done
-- 
2.11.0

[PATCH v2 12/13] grep: add support for the PCRE v1 JIT API

[Ævar Arnfjörð Bjarmason]

Change the grep PCRE v1 code to use JIT when available. When PCRE
support was initially added in commit 63e7e9d8b6 ("git-grep: Learn
PCRE", 2011-05-09) PCRE had no JIT support, it was integrated into
8.20 released on 2011-10-21.

When JIT support is enabled the PCRE performance usually improves by
more than 50%. The pattern compilation times are relatively slower,
but those relative numbers are tiny, and are easily made back in all
but the most trivial cases of grep. Detailed benchhmarks are available
at: http://sljit.sourceforge.net/pcre.html

With this change the difference in a t/perf/p7820-grep-engines.sh run
is, shown with git --word-diff:

    7820.1: extended with how.to                               [-0.28(1.23+0.44)-]{+0.28(1.18+0.39)+}
    7820.2: extended with ^how to                              [-0.26(1.15+0.38)-]{+0.27(1.13+0.40)+}
    7820.3: extended with \w+our\w*                            [-6.06(38.44+0.35)-]{+6.11(38.66+0.32)+}
    7820.4: extended with -?-?-?-?-?-?-?-?-?-?-?-----------$   [-0.37(1.57+0.38)-]{+0.37(1.56+0.42)+}
    7820.5: pcre1 with how.to                                  [-0.26(1.15+0.37)-]{+0.19(0.39+0.55)+}
    7820.6: pcre1 with ^how to                                 [-0.46(2.66+0.31)-]{+0.22(0.67+0.44)+}
    7820.7: pcre1 with \w+our\w*                               [-16.42(99.42+0.48)-]{+0.51(3.05+0.24)+}
    7820.8: pcre1 with -?-?-?-?-?-?-?-?-?-?-?-----------$      [-81.52(275.37+0.41)-]{+5.16(19.31+0.33)+}

The conditional support for JIT is implemented as suggested in the
pcrejit(3) man page. E.g. defining PCRE_STUDY_JIT_COMPILE to 0 if it's
not present.

There's no graceful fallback if pcre_jit_stack_alloc() fails under
PCRE_CONFIG_JIT, instead the program will abort. I don't think this is
worth handling, it'll only fail in cases where malloc() doesn't work,
in which case we're screwed anyway.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 grep.c | 27 ++++++++++++++++++++++++++-
 grep.h |  5 +++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/grep.c b/grep.c
index d2c87ee2c3..eb68bdaa2a 100644
--- a/grep.c
+++ b/grep.c
@@ -331,6 +331,9 @@ 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
+	int canjit;
+#endif
 
 	if (opt->ignore_case) {
 		if (has_non_ascii(p->pattern))
@@ -345,9 +348,19 @@ static void compile_pcre1_regexp(struct grep_pat *p, const struct grep_opt *opt)
 	if (!p->pcre1_regexp)
 		compile_regexp_failed(p, error);
 
-	p->pcre1_extra_info = pcre_study(p->pcre1_regexp, 0, &error);
+	p->pcre1_extra_info = pcre_study(p->pcre1_regexp, PCRE_STUDY_JIT_COMPILE, &error);
 	if (!p->pcre1_extra_info && error)
 		die("%s", error);
+
+#ifdef PCRE_CONFIG_JIT
+	pcre_config(PCRE_CONFIG_JIT, &canjit);
+	if (canjit == 1) {
+		p->pcre1_jit_stack = pcre_jit_stack_alloc(1, 1024 * 1024);
+		if (!p->pcre1_jit_stack)
+			die("BUG: Couldn't allocate PCRE JIT stack");
+		pcre_assign_jit_stack(p->pcre1_extra_info, NULL, p->pcre1_jit_stack);
+	}
+#endif
 }
 
 static int pcre1match(struct grep_pat *p, const char *line, const char *eol,
@@ -358,8 +371,15 @@ static int pcre1match(struct grep_pat *p, const char *line, const char *eol,
 	if (eflags & REG_NOTBOL)
 		flags |= PCRE_NOTBOL;
 
+#ifdef PCRE_CONFIG_JIT
+	ret = pcre_jit_exec(p->pcre1_regexp, p->pcre1_extra_info, line, eol - line,
+			    0, flags, ovector, ARRAY_SIZE(ovector),
+			    p->pcre1_jit_stack);
+#else
 	ret = pcre_exec(p->pcre1_regexp, p->pcre1_extra_info, line, eol - line,
 			0, flags, ovector, ARRAY_SIZE(ovector));
+#endif
+
 	if (ret < 0 && ret != PCRE_ERROR_NOMATCH)
 		die("pcre_exec failed with error code %d", ret);
 	if (ret > 0) {
@@ -374,7 +394,12 @@ 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
+	pcre_free_study(p->pcre1_extra_info);
+	pcre_jit_stack_free(p->pcre1_jit_stack);
+#else
 	pcre_free(p->pcre1_extra_info);
+#endif
 	pcre_free((void *)p->pcre1_tables);
 }
 #else /* !USE_LIBPCRE1 */
diff --git a/grep.h b/grep.h
index fa2ab9485f..29e20bf837 100644
--- a/grep.h
+++ b/grep.h
@@ -3,9 +3,13 @@
 #include "color.h"
 #ifdef USE_LIBPCRE1
 #include <pcre.h>
+#ifndef PCRE_STUDY_JIT_COMPILE
+#define PCRE_STUDY_JIT_COMPILE 0
+#endif
 #else
 typedef int pcre;
 typedef int pcre_extra;
+typedef int pcre_jit_stack;
 #endif
 #include "kwset.h"
 #include "thread-utils.h"
@@ -48,6 +52,7 @@ struct grep_pat {
 	regex_t regexp;
 	pcre *pcre1_regexp;
 	pcre_extra *pcre1_extra_info;
+	pcre_jit_stack *pcre1_jit_stack;
 	const unsigned char *pcre1_tables;
 	kwset_t kws;
 	unsigned fixed:1;
-- 
2.11.0

[PATCH v2 13/13] grep: add support for PCRE v2

[Ævar Arnfjörð Bjarmason]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset=UTF-8, Size: 23500 bytes --]

Add support for v2 of the PCRE API. This is a new major version of
PCRE that came out in early 2015[1].

The regular expression syntax is the same, but while the API is
similar-ish, pretty much every function is either renamed or takes
different arguments. Thus using it via entirely new functions makes
sense, as opposed to trying to e.g. have one compile_pcre_pattern()
that would call either PCRE v1 or v2 functions.

Git can now be compiled with any combination of
USE_LIBPCRE=[YesPlease|] & USE_LIBPCRE2=[YesPlease|]. If both are
provided the version of the PCRE library can be selected at runtime
with grep.PatternType, but the default (for now) is v1.

This table shows what the various combinations do, depending on what
libraries Git is compiled against:

    |------------------+-----+-----+----------|
    | grep.PatternType | v1  | v2  | v1 && v2 |
    |------------------+-----+-----+----------|
    | perl             | v1  | v2  | v1       |
    | pcre             | v1  | v2  | v1       |
    | pcre1            | v1  | ERR | v1       |
    | pcre2            | ERR | v2  | v2       |
    |------------------+-----+-----+----------|

When Git is only compiled with v2 grep.PatternType=perl, --perl-regexp
& -P will use v2. All tests pass with this new PCRE version. When Git
is compiled with both v1 & v2 most of the tests will only test v1, but
there are some v2-specific tests that will be run.

With earlier patches to enable JIT for PCRE v1 the performance of the
release versions of both libraries have almost exactly the same
performance, with PCRE v2 being around 1% slower.

However after I reported this to the pcre-dev mailing list[2] I got a
lot of help with the API use from Zoltán Herczeg, he
subsequently optimized some of the JIT functionality in v2 of the
library.

Running the p7820-grep-engines.sh performance test against the latest
Subversion trunk of both, with both them and git compiled as -O3, and
the test run against linux.git, gives the following results:

    7820.1: extended with how.to                               0.27(1.22+0.34)
    7820.2: extended with ^how to                              0.27(1.18+0.36)
    7820.3: extended with \w+our\w*                            6.09(38.64+0.32)
    7820.4: extended with -?-?-?-?-?-?-?-?-?-?-?-----------$   0.38(1.69+0.28)
    7820.5: pcre1 with how.to                                  0.19(0.42+0.53)
    7820.6: pcre1 with ^how to                                 0.23(0.58+0.50)
    7820.7: pcre1 with \w+our\w*                               0.50(2.93+0.34)
    7820.8: pcre1 with -?-?-?-?-?-?-?-?-?-?-?-----------$      5.12(19.32+0.38)
    7820.9: pcre2 with how.to                                  0.19(0.34+0.57)
    7820.10: pcre2 with ^how to                                0.19(0.29+0.60)
    7820.11: pcre2 with \w+our\w*                              0.51(2.85+0.41)
    7820.12: pcre2 with -?-?-?-?-?-?-?-?-?-?-?-----------$     5.04(19.27+0.31)

I.e. the two are neck-to-neck, but PCRE v2 usually pulls ahead, when
it does it's up to 20% faster.

A brief note on thread safety: As noted in pcre2api(3) & pcre2jit(3)
the compiled pattern can be shared between threads, but not some of
the JIT context, however the grep threading support does all pattern &
JIT compilation in separate threads, so this code doesn't need to
concern itself with thread safety.

See commit 63e7e9d8b6 ("git-grep: Learn PCRE", 2011-05-09) for the
initial addition of PCRE v1. This change follows some of the same
patterns it did (and which were discussed on list at the time),
e.g. mocking up types with typedef instead of ifdef-ing them out when
USE_LIBPCRE2 isn't defined. This adds some trivial memory use to the
program, but makes the code look nicer.

1. https://lists.exim.org/lurker/message/20150105.162835.0666407a.en.html
2. https://lists.exim.org/lurker/thread/20170419.172322.833ee099.en.html

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Documentation/config.txt     |  14 ++--
 Makefile                     |  18 ++++++
 builtin/grep.c               |   4 +-
 configure.ac                 |  49 +++++++++++++-
 grep.c                       | 149 ++++++++++++++++++++++++++++++++++++++++++-
 grep.h                       |  21 +++++-
 revision.c                   |   2 +-
 t/README                     |  12 ++++
 t/perf/p7820-grep-engines.sh |   2 +-
 t/t7810-grep.sh              |  30 ++++++++-
 t/t7813-grep-icase-iso.sh    |  11 ++--
 t/test-lib.sh                |   4 +-
 12 files changed, 291 insertions(+), 25 deletions(-)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 5ef12d0694..a5fc482495 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -1625,14 +1625,12 @@ grep.patternType::
 	`--fixed-strings`, or `--perl-regexp` option accordingly, while the
 	value 'default' will return to the default matching behavior.
 +
-The 'pcre' and 'pcre1' values are synonyms for 'perl'. The other
-values starting with 'pcre' are reserved for future use, e.g. if we'd
-like to use 'pcre2' for the PCRE v2 library.
-+
-In the future 'perl' and 'pcre' might become synonyms for some other
-implementation or PCRE version, such as 'pcre2', while the more
-specific 'pcre1' & 'pcre2' might throw errors depending on whether git
-is compiled to include those libraries.
+The 'perl' and 'pcre' values are synonyms. Depending on which PCRE
+library Git was compiled with either or both of 'pcre1' and 'pcre2'
+might also be available.
++
+If both are available Git currently defaults to 'pcre1', but this
+might change in future versions.
 
 grep.extendedRegexp::
 	If set to true, enable `--extended-regexp` option by default. This
diff --git a/Makefile b/Makefile
index cd19980906..6eba4e40e3 100644
--- a/Makefile
+++ b/Makefile
@@ -32,6 +32,14 @@ all::
 # Define LIBPCREDIR=/foo/bar if your libpcre header and library files are in
 # /foo/bar/include and /foo/bar/lib directories.
 #
+# Define USE_LIBPCRE2 if you have and want to use libpcre2. Various
+# commands such as log and grep offer runtime options to use
+# Perl-compatible regular expressions instead of standard or extended
+# POSIX regular expressions.
+#
+# Define LIBPCRE2DIR=/foo/bar if your libpcre2 header and library
+# files are in /foo/bar/include and /foo/bar/lib directories.
+#
 # Define HAVE_ALLOCA_H if you have working alloca(3) defined in that header.
 #
 # Define NO_CURL if you do not have libcurl installed.  git-http-fetch and
@@ -1092,6 +1100,15 @@ ifdef USE_LIBPCRE
 	EXTLIBS += -lpcre
 endif
 
+ifdef USE_LIBPCRE2
+	BASIC_CFLAGS += -DUSE_LIBPCRE2
+	ifdef LIBPCRE2DIR
+		BASIC_CFLAGS += -I$(LIBPCRE2DIR)/include
+		EXTLIBS += -L$(LIBPCRE2DIR)/$(lib) $(CC_LD_DYNPATH)$(LIBPCR2EDIR)/$(lib)
+	endif
+	EXTLIBS += -lpcre2-8
+endif
+
 ifdef HAVE_ALLOCA_H
 	BASIC_CFLAGS += -DHAVE_ALLOCA_H
 endif
@@ -2237,6 +2254,7 @@ GIT-BUILD-OPTIONS: FORCE
 	@echo NO_CURL=\''$(subst ','\'',$(subst ','\'',$(NO_CURL)))'\' >>$@+
 	@echo NO_EXPAT=\''$(subst ','\'',$(subst ','\'',$(NO_EXPAT)))'\' >>$@+
 	@echo USE_LIBPCRE1=\''$(subst ','\'',$(subst ','\'',$(USE_LIBPCRE)))'\' >>$@+
+	@echo USE_LIBPCRE2=\''$(subst ','\'',$(subst ','\'',$(USE_LIBPCRE2)))'\' >>$@+
 	@echo NO_PERL=\''$(subst ','\'',$(subst ','\'',$(NO_PERL)))'\' >>$@+
 	@echo NO_PYTHON=\''$(subst ','\'',$(subst ','\'',$(NO_PYTHON)))'\' >>$@+
 	@echo NO_UNIX_SOCKETS=\''$(subst ','\'',$(subst ','\'',$(NO_UNIX_SOCKETS)))'\' >>$@+
diff --git a/builtin/grep.c b/builtin/grep.c
index 945e9e7f2e..65070c52fc 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -490,7 +490,7 @@ static void compile_submodule_options(const struct grep_opt *opt,
 	case GREP_PATTERN_TYPE_FIXED:
 		argv_array_push(&submodule_options, "-F");
 		break;
-	case GREP_PATTERN_TYPE_PCRE1:
+	case GREP_PATTERN_TYPE_PCRE:
 		argv_array_push(&submodule_options, "-P");
 		break;
 	case GREP_PATTERN_TYPE_UNSPECIFIED:
@@ -1018,7 +1018,7 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 			    GREP_PATTERN_TYPE_FIXED),
 		OPT_SET_INT('P', "perl-regexp", &pattern_type_arg,
 			    N_("use Perl-compatible regular expressions"),
-			    GREP_PATTERN_TYPE_PCRE1),
+			    GREP_PATTERN_TYPE_PCRE),
 		OPT_GROUP(""),
 		OPT_BOOL('n', "line-number", &opt.linenum, N_("show line numbers")),
 		OPT_NEGBIT('h', NULL, &opt.pathname, N_("don't show filenames"), 1),
diff --git a/configure.ac b/configure.ac
index deeb968daa..725c2d6949 100644
--- a/configure.ac
+++ b/configure.ac
@@ -259,8 +259,8 @@ GIT_PARSE_WITH([openssl]))
 # /foo/bar/include and /foo/bar/lib directories.
 #
 AC_ARG_WITH(libpcre,
-AS_HELP_STRING([--with-libpcre],[support Perl-compatible regexes (default is NO)])
-AS_HELP_STRING([],           [ARG can be also prefix for libpcre library and headers]),
+AS_HELP_STRING([--with-libpcre],[support Perl-compatible regexes via libpcre1 (default is NO)])
+AS_HELP_STRING([],           [ARG can be also prefix for libpcre1 library and headers]),
     if test "$withval" = "no"; then
 	USE_LIBPCRE=
     elif test "$withval" = "yes"; then
@@ -273,6 +273,30 @@ AS_HELP_STRING([],           [ARG can be also prefix for libpcre library and hea
         dnl it yet.
 	GIT_CONF_SUBST([LIBPCREDIR])
     fi)
+
+# Define USE_LIBPCRE2 if you have and want to use libpcre2. Various
+# commands such as log and grep offer runtime options to use
+# Perl-compatible regular expressions instead of standard or extended
+# POSIX regular expressions.
+#
+# Define LIBPCR2EDIR=/foo/bar if your libpcre2 header and library
+# files are in /foo/bar/include and /foo/bar/lib directories.
+#
+AC_ARG_WITH(libpcre2,
+AS_HELP_STRING([--with-libpcre2],[support Perl-compatible regexes via libpcre2 (default is NO)])
+AS_HELP_STRING([],           [ARG can be also prefix for libpcre library and headers]),
+    if test "$withval" = "no"; then
+	USE_LIBPCRE2=
+    elif test "$withval" = "yes"; then
+	USE_LIBPCRE2=YesPlease
+    else
+	USE_LIBPCRE2=YesPlease
+	LIBPCRE2DIR=$withval
+	AC_MSG_NOTICE([Setting LIBPCRE2DIR to $LIBPCREDIR])
+        dnl USE_LIBPCRE2 can still be modified below, so don't substitute
+        dnl it yet.
+	GIT_CONF_SUBST([LIBPCRE2DIR])
+    fi)
 #
 # Define HAVE_ALLOCA_H if you have working alloca(3) defined in that header.
 AC_FUNC_ALLOCA
@@ -522,6 +546,27 @@ GIT_CONF_SUBST([USE_LIBPCRE])
 fi
 
 #
+# Define USE_LIBPCRE2 if you have and want to use libpcre2. Various
+# commands such as log and grep offer runtime options to use
+# Perl-compatible regular expressions instead of standard or extended
+# POSIX regular expressions.
+#
+
+if test -n "$USE_LIBPCRE2"; then
+
+GIT_STASH_FLAGS($LIBPCRE2DIR)
+
+AC_CHECK_LIB([pcre2-8], [pcre2_config_8],
+[USE_LIBPCRE2=YesPlease],
+[USE_LIBPCRE2=])
+
+GIT_UNSTASH_FLAGS($LIBPCRE2DIR)
+
+GIT_CONF_SUBST([USE_LIBPCRE2])
+
+fi
+
+#
 # Define NO_CURL if you do not have libcurl installed.  git-http-pull and
 # git-http-push are not built, and you cannot use http:// and https://
 # transports.
diff --git a/grep.c b/grep.c
index eb68bdaa2a..39955f5745 100644
--- a/grep.c
+++ b/grep.c
@@ -61,9 +61,12 @@ static int parse_pattern_type_arg(const char *opt, const char *arg)
 	else if (!strcmp(arg, "fixed"))
 		return GREP_PATTERN_TYPE_FIXED;
 	else if (!strcmp(arg, "perl") ||
-		 !strcmp(arg, "pcre") ||
-		 !strcmp(arg, "pcre1"))
+		 !strcmp(arg, "pcre"))
+		return GREP_PATTERN_TYPE_PCRE;
+	else if (!strcmp(arg, "pcre1"))
 		return GREP_PATTERN_TYPE_PCRE1;
+	else if (!strcmp(arg, "pcre2"))
+		return GREP_PATTERN_TYPE_PCRE2;
 	die("bad %s argument: %s", opt, arg);
 }
 
@@ -181,24 +184,48 @@ static void grep_set_pattern_type_option(enum grep_pattern_type pattern_type, st
 	case GREP_PATTERN_TYPE_BRE:
 		opt->fixed = 0;
 		opt->pcre1 = 0;
+		opt->pcre2 = 0;
 		opt->regflags &= ~REG_EXTENDED;
 		break;
 
 	case GREP_PATTERN_TYPE_ERE:
 		opt->fixed = 0;
 		opt->pcre1 = 0;
+		opt->pcre2 = 0;
 		opt->regflags |= REG_EXTENDED;
 		break;
 
 	case GREP_PATTERN_TYPE_FIXED:
 		opt->fixed = 1;
 		opt->pcre1 = 0;
+		opt->pcre2 = 0;
 		opt->regflags &= ~REG_EXTENDED;
 		break;
 
+	case GREP_PATTERN_TYPE_PCRE:
+		opt->fixed = 0;
+		/* We default to pcre1 if we have both versions. This
+		 * may change in future versions.
+		 */
+#ifdef USE_LIBPCRE1
+		opt->pcre1 = 1;
+		opt->pcre2 = 0;
+#elif USE_LIBPCRE2
+		opt->pcre1 = 0;
+		opt->pcre2 = 1;
+#endif
+		break;
+
 	case GREP_PATTERN_TYPE_PCRE1:
 		opt->fixed = 0;
 		opt->pcre1 = 1;
+		opt->pcre2 = 0;
+		break;
+
+	case GREP_PATTERN_TYPE_PCRE2:
+		opt->fixed = 0;
+		opt->pcre1 = 0;
+		opt->pcre2 = 1;
 		break;
 	}
 }
@@ -419,6 +446,115 @@ static void free_pcre1_regexp(struct grep_pat *p)
 }
 #endif /* !USE_LIBPCRE1 */
 
+#ifdef USE_LIBPCRE2
+static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt)
+{
+	int error;
+	PCRE2_UCHAR errbuf[256];
+	PCRE2_SIZE erroffset;
+	int options = PCRE2_MULTILINE;
+	const uint8_t *character_tables = NULL;
+	uint32_t canjit;
+	int jitret;
+
+	p->pcre2_ccontext = NULL;
+
+	if (opt->ignore_case) {
+		if (has_non_ascii(p->pattern)) {
+			character_tables = pcre2_maketables(NULL);
+			p->pcre2_ccontext = pcre2_compile_context_create(NULL);
+			pcre2_set_character_tables(p->pcre2_ccontext, character_tables);
+		}
+		options |= PCRE2_CASELESS;
+	}
+	if (is_utf8_locale() && has_non_ascii(p->pattern))
+		options |= PCRE2_UTF;
+
+	p->pcre2_pattern = pcre2_compile((PCRE2_SPTR)p->pattern,
+					 p->patternlen, options, &error, &erroffset,
+					 p->pcre2_ccontext);
+
+	if (p->pcre2_pattern) {
+		p->pcre2_match_data = pcre2_match_data_create_from_pattern(p->pcre2_pattern, NULL);
+		if (!p->pcre2_match_data)
+			die("BUG: Couldn't allocate PCRE2 match data");
+	} else {
+		pcre2_get_error_message(error, errbuf, sizeof(errbuf));
+		compile_regexp_failed(p, (const char *)&errbuf);
+	}
+
+	pcre2_config(PCRE2_CONFIG_JIT, &canjit);
+	if (canjit == 1) {
+		jitret = pcre2_jit_compile(p->pcre2_pattern, PCRE2_JIT_COMPLETE);
+		if (!jitret)
+			p->pcre2_jit_on = 1;
+		else
+			die("BUG: Couldn't JIT the PCRE2 pattern '%s', got '%d'\n", p->pattern, jitret);
+		p->pcre2_jit_stack = pcre2_jit_stack_create(1, 1024 * 1024, NULL);
+		if (!p->pcre2_jit_stack)
+			die("BUG: Couldn't allocate PCRE2 JIT stack");
+		p->pcre2_match_context = pcre2_match_context_create(NULL);
+		if (!p->pcre2_jit_stack)
+			die("BUG: Couldn't allocate PCRE2 match context");
+		pcre2_jit_stack_assign(p->pcre2_match_context, NULL, p->pcre2_jit_stack);
+	}
+}
+
+static int pcre2match(struct grep_pat *p, const char *line, const char *eol,
+		regmatch_t *match, int eflags)
+{
+	int ret, flags = 0;
+	PCRE2_SIZE *ovector;
+
+	if (eflags & REG_NOTBOL)
+		flags |= PCRE2_NOTBOL;
+
+	if (p->pcre2_jit_on)
+		ret = pcre2_jit_match(p->pcre2_pattern, (unsigned char *)line,
+				      eol - line, 0, flags, p->pcre2_match_data,
+				      NULL);
+	else
+		ret = pcre2_match(p->pcre2_pattern, (unsigned char *)line,
+				  eol - line, 0, flags, p->pcre2_match_data,
+				  NULL);
+
+	if (ret < 0 && ret != PCRE2_ERROR_NOMATCH)
+		die("pcre_exec failed with error code %d", ret);
+	if (ret > 0) {
+		ovector = pcre2_get_ovector_pointer(p->pcre2_match_data);
+		ret = 0;
+		match->rm_so = (int)ovector[0];
+		match->rm_eo = (int)ovector[1];
+	}
+
+	return ret;
+}
+
+static void free_pcre2_pattern(struct grep_pat *p)
+{
+	pcre2_compile_context_free(p->pcre2_ccontext);
+	pcre2_code_free(p->pcre2_pattern);
+	pcre2_match_data_free(p->pcre2_match_data);
+	pcre2_jit_stack_free(p->pcre2_jit_stack);
+	pcre2_match_context_free(p->pcre2_match_context);
+}
+#else /* !USE_LIBPCRE2 */
+static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt)
+{
+	die("cannot use Perl-compatible regexes when not compiled with USE_LIBPCRE2");
+}
+
+static int pcre2match(struct grep_pat *p, const char *line, const char *eol,
+		regmatch_t *match, int eflags)
+{
+	return 1;
+}
+
+static void free_pcre2_pattern(struct grep_pat *p)
+{
+}
+#endif /* !USE_LIBPCRE2 */
+
 static int is_fixed(const char *s, size_t len)
 {
 	size_t i;
@@ -506,6 +642,11 @@ static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
 		return;
 	}
 
+	if (opt->pcre2) {
+		compile_pcre2_pattern(p, opt);
+		return;
+	}
+
 	err = regcomp(&p->regexp, p->pattern, opt->regflags);
 	if (err) {
 		char errbuf[1024];
@@ -860,6 +1001,8 @@ void free_grep_patterns(struct grep_opt *opt)
 				kwsfree(p->kws);
 			else if (p->pcre1_regexp)
 				free_pcre1_regexp(p);
+			else if (p->pcre2_pattern)
+				free_pcre2_pattern(p);
 			else
 				regfree(&p->regexp);
 			free(p->pattern);
@@ -940,6 +1083,8 @@ static int patmatch(struct grep_pat *p, char *line, char *eol,
 		hit = !fixmatch(p, line, eol, match);
 	else if (p->pcre1_regexp)
 		hit = !pcre1match(p, line, eol, match, eflags);
+	else if (p->pcre2_pattern)
+		hit = !pcre2match(p, line, eol, match, eflags);
 	else
 		hit = !regexec_buf(&p->regexp, line, eol - line, 1, match,
 				   eflags);
diff --git a/grep.h b/grep.h
index 29e20bf837..dd16b5fd53 100644
--- a/grep.h
+++ b/grep.h
@@ -11,6 +11,16 @@ typedef int pcre;
 typedef int pcre_extra;
 typedef int pcre_jit_stack;
 #endif
+#ifdef USE_LIBPCRE2
+#define PCRE2_CODE_UNIT_WIDTH 8
+#include <pcre2.h>
+#else
+typedef int pcre2_code;
+typedef int pcre2_match_data;
+typedef int pcre2_compile_context;
+typedef int pcre2_match_context;
+typedef int pcre2_jit_stack;
+#endif
 #include "kwset.h"
 #include "thread-utils.h"
 #include "userdiff.h"
@@ -54,6 +64,12 @@ struct grep_pat {
 	pcre_extra *pcre1_extra_info;
 	pcre_jit_stack *pcre1_jit_stack;
 	const unsigned char *pcre1_tables;
+	pcre2_code *pcre2_pattern;
+	pcre2_match_data *pcre2_match_data;
+	pcre2_compile_context *pcre2_ccontext;
+	pcre2_match_context *pcre2_match_context;
+	pcre2_jit_stack *pcre2_jit_stack;
+	int pcre2_jit_on;
 	kwset_t kws;
 	unsigned fixed:1;
 	unsigned ignore_case:1;
@@ -73,7 +89,9 @@ enum grep_pattern_type {
 	GREP_PATTERN_TYPE_BRE,
 	GREP_PATTERN_TYPE_ERE,
 	GREP_PATTERN_TYPE_FIXED,
-	GREP_PATTERN_TYPE_PCRE1
+	GREP_PATTERN_TYPE_PCRE,
+	GREP_PATTERN_TYPE_PCRE1,
+	GREP_PATTERN_TYPE_PCRE2
 };
 
 struct grep_expr {
@@ -117,6 +135,7 @@ struct grep_opt {
 	int extended;
 	int use_reflog_filter;
 	int pcre1;
+	int pcre2;
 	int relative;
 	int pathname;
 	int null_following_name;
diff --git a/revision.c b/revision.c
index 7a10a8570a..03a3a012de 100644
--- a/revision.c
+++ b/revision.c
@@ -1996,7 +1996,7 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
 	} else if (!strcmp(arg, "--fixed-strings") || !strcmp(arg, "-F")) {
 		revs->grep_filter.pattern_type_option = GREP_PATTERN_TYPE_FIXED;
 	} else if (!strcmp(arg, "--perl-regexp") || !strcmp(arg, "-P")) {
-		revs->grep_filter.pattern_type_option = GREP_PATTERN_TYPE_PCRE1;
+		revs->grep_filter.pattern_type_option = GREP_PATTERN_TYPE_PCRE;
 	} else if (!strcmp(arg, "--all-match")) {
 		revs->grep_filter.all_match = 1;
 	} else if (!strcmp(arg, "--invert-grep")) {
diff --git a/t/README b/t/README
index a90cb62583..547b06e700 100644
--- a/t/README
+++ b/t/README
@@ -808,6 +808,18 @@ use these, and "test_set_prereq" for how to define your own.
    Git was compiled with support for PCRE. Wrap any tests
    that use git-grep --perl-regexp or git-grep -P in these.
 
+ - LIBPCRE1
+
+   Git was compiled with PCRE v1 support via
+   USE_LIBPCRE=YesPlease. Wrap any PCRE using tests that for some
+   reason need v1 of the PCRE library instead of v2 in these.
+
+ - LIBPCRE2
+
+   Git was compiled with PCRE v2 support via
+   USE_LIBPCRE2=YesPlease. Wrap any PCRE using tests that for some
+   reason need v2 of the PCRE library instead of v1 in these.
+
  - CASE_INSENSITIVE_FS
 
    Test is run on a case insensitive file system.
diff --git a/t/perf/p7820-grep-engines.sh b/t/perf/p7820-grep-engines.sh
index 5ae42ceccc..70c5a5ca32 100755
--- a/t/perf/p7820-grep-engines.sh
+++ b/t/perf/p7820-grep-engines.sh
@@ -7,7 +7,7 @@ test_description="Comparison of git-grep's regex engines"
 test_perf_large_repo
 test_checkout_worktree
 
-for engine in extended pcre1
+for engine in extended pcre1 pcre2
 do
 	# Patterns stolen from http://sljit.sourceforge.net/pcre.html
 	for pattern in \
diff --git a/t/t7810-grep.sh b/t/t7810-grep.sh
index f929b447e9..bae7e524b9 100755
--- a/t/t7810-grep.sh
+++ b/t/t7810-grep.sh
@@ -1063,6 +1063,16 @@ test_expect_success PCRE 'grep -P pattern' '
 	test_cmp expected actual
 '
 
+test_expect_success LIBPCRE1 'grep libpcre1 pattern' '
+	git -c grep.patternType=pcre1 grep "\p{Ps}.*?\p{Pe}" hello.c >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success LIBPCRE2 'grep libpcre2 pattern' '
+	git -c grep.patternType=pcre2 grep "\p{Ps}.*?\p{Pe}" hello.c >actual &&
+	test_cmp expected actual
+'
+
 test_expect_success 'grep pattern with grep.extendedRegexp=true' '
 	>empty &&
 	test_must_fail git -c grep.extendedregexp=true \
@@ -1512,14 +1522,28 @@ test_expect_success 'grep does not report i-t-a and assume unchanged with -L' '
 	test_cmp expected actual
 '
 
-test_expect_success PCRE "grep with grep.patternType synonyms perl/pcre/pcre1" '
+test_expect_success PCRE "grep with grep.patternType synonyms perl/pcre" '
 	echo "#include <stdio.h>" >expected &&
 	git -c grep.patternType=perl  grep -h --no-line-number "st(?=dio)" >actual &&
 	test_cmp expected actual &&
 	git -c grep.patternType=pcre  grep -h --no-line-number "st(?=dio)" >actual &&
-	test_cmp expected actual &&
-	git -c grep.patternType=pcre1 grep -h --no-line-number "st(?=dio)" >actual &&
 	test_cmp expected actual
 '
 
+test_expect_success LIBPCRE1 "grep with grep.patternType=pcre1" '
+	echo "#include <stdio.h>" >expected &&
+	git -c grep.patternType=pcre1 grep -h --no-line-number "st(?=dio)" >actual &&
+	test_cmp expected actual &&
+	test_must_fail git -c grep.patternType=pcre1 grep "foo(?+bar)" 2>error &&
+	test_i18ngrep -q "digit expected after" error
+'
+
+test_expect_success LIBPCRE2 "grep with grep.patternType=pcre2" '
+	echo "#include <stdio.h>" >expected &&
+	git -c grep.patternType=pcre2 grep -h --no-line-number "st(?=dio)" >actual &&
+	test_cmp expected actual &&
+	test_must_fail git -c grep.patternType=pcre2 grep "foo(?+bar)" 2>error &&
+	test_i18ngrep -q "digit expected after" error
+'
+
 test_done
diff --git a/t/t7813-grep-icase-iso.sh b/t/t7813-grep-icase-iso.sh
index 701e08a8e5..e16570690c 100755
--- a/t/t7813-grep-icase-iso.sh
+++ b/t/t7813-grep-icase-iso.sh
@@ -11,9 +11,12 @@ test_expect_success GETTEXT_ISO_LOCALE 'setup' '
 	export LC_ALL
 '
 
-test_expect_success GETTEXT_ISO_LOCALE,PCRE 'grep pcre string' '
-	git grep --perl-regexp -i "TILRAUN: H.lló Heimur!" &&
-	git grep --perl-regexp -i "TILRAUN: H.LLÓ HEIMUR!"
-'
+for pcrev in 1 2
+do
+	test_expect_success GETTEXT_ISO_LOCALE,LIBPCRE$pcrev "grep -i with i18n string using libpcre$pcrev" "
+		git -c grep.patternType=pcre$pcrev grep -i \"TILRAUN: H.lló Heimur!\" &&
+		git -c grep.patternType=pcre$pcrev grep -i \"TILRAUN: H.LLÓ HEIMUR!\"
+	"
+done
 
 test_done
diff --git a/t/test-lib.sh b/t/test-lib.sh
index e5cfbcc36b..6f873de3e7 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -1010,7 +1010,9 @@ esac
 ( COLUMNS=1 && test $COLUMNS = 1 ) && test_set_prereq COLUMNS_CAN_BE_1
 test -z "$NO_PERL" && test_set_prereq PERL
 test -z "$NO_PYTHON" && test_set_prereq PYTHON
-test -n "$USE_LIBPCRE1" && test_set_prereq PCRE
+test -n "$USE_LIBPCRE1$USE_LIBPCRE2" && test_set_prereq PCRE
+test -n "$USE_LIBPCRE1" && test_set_prereq LIBPCRE1
+test -n "$USE_LIBPCRE2" && test_set_prereq LIBPCRE2
 test -z "$NO_GETTEXT" && test_set_prereq GETTEXT
 
 # Can we rely on git's output in the C locale?
-- 
2.11.0