Easy to review grep & pre-PCRE changes

Easy to review? 29 (I mean 30) patches? Are you kidding me?!

As noted in v1 (<[email protected]>;
https://public-inbox.org/git/[email protected]/)
these are all doc, test, refactoring etc. changes needed by the subsequent "PCRE v2, PCRE v1 JIT, log -P & fixes" series.

Since Junio hasn't been picking it I'm no longer sending updates to that patch series & waiting for this one to cook first.

See <[email protected]>
(https://public-inbox.org/git/[email protected]/)
for v2 & notes about that version. What changed this time around? See below:

Ævar Arnfjörð Bjarmason (30):
Makefile & configure: reword inaccurate comment about PCRE grep & rev-list doc: stop promising libpcre for --perl-regexp
test-lib: rename the LIBPCRE prerequisite to PCRE

No changes.

log: add exhaustive tests for pattern style options & config

Test comment clarifications in t4202-log.sh as pointed out by Junio.

  log: make --regexp-ignore-case work with --perl-regexp

NEW: I noticed that the -i in git log --perl-regexp -i --grep=<rx> never worked as intended. I.e. the flag for ignoring the case of the pattern wasn't picked up.

Fixing this was trivial (one-line change), so I've included it in this series since it's needed by a new t/perf patch (see below).

grep: add a test asserting that --perl-regexp dies when !PCRE
grep: add a test for backreferences in PCRE patterns
grep: change non-ASCII -i test to stop using --debug
grep: add tests for --threads=N and grep.threads
grep: amend submodule recursion test for regex engine testing
grep: add tests for grep pattern types being passed to submodules

No changes.

grep: add a test helper function for less verbose -f \0 tests

Trivial style changes in nul_match() suggested by Junio. No functional changes.

grep: prepare for testing binary regexes containing rx metacharacters

No changes.

grep: add tests to fix blind spots with \0 patterns

Continued trivial style changes in nul_match() (the other half of the code in that function is added in this commit)>

perf: add a GIT_PERF_MAKE_COMMAND for when *_MAKE_OPTS won't do
perf: emit progress output when unpacking & building

No changes.

perf: add a comparison test of grep regex engines
perf: add a comparison test of grep regex engines with -F
perf: add a comparison test of log --grep regex engines

The log --grep test is new, and all these tests learned to take an env variable to pass arbitrary extra grep/log flags, so I can e.g. test with -i, -v, -w etc.

Subsequent commit messages that e.g. mentioned perf tests with the previous hardcoded -i test have been amended to mention the new test results.

grep: catch a missing enum in switch statement

Grammar fix in commit message.

grep: remove redundant regflags assignments

The two commits that made changes to regflags assignments have been squashed.

grep: factor test for \0 in grep patterns into a function

Rewrote commit message to not go off on a tangent about what grep -f [file-with-\0-pattern] should mean, which is not what this change is about.

grep: change the internal PCRE macro names to be PCRE1
grep: change internal *pcre* variable & function names to be *pcre1*
grep: move is_fixed() earlier to avoid forward declaration
test-lib: add a PTHREADS prerequisite

No changes.

pack-objects & index-pack: add test for --threads warning
pack-objects: fix buggy warning about threads

Rewrote the tests in these two so that the first one sets up a failing test which is subsequently fixed in the commit that fixes the bug, as suggested by Junio.

Removed a stray cat err left over from debugging.

grep: given --threads with NO_PTHREADS=YesPlease, warn
grep: assert that threading is enabled when calling grep_{lock,unlock}

No changes.

 Documentation/git-grep.txt         |   7 +-
 Documentation/rev-list-options.txt |   8 +-
 Makefile                           |  14 ++-
 builtin/grep.c                     |  23 +++-
 builtin/pack-objects.c             |   4 +-
 configure.ac                       |  12 ++-
 grep.c                             | 108 ++++++++++---------
 grep.h                             |  10 +-
 revision.c                         |   1 +
 t/README                           |   8 +-
 t/perf/README                      |  19 +++-
 t/perf/p4220-log-grep-engines.sh   |  44 ++++++++
 t/perf/p7820-grep-engines.sh       |  47 ++++++++
 t/perf/p7821-grep-engines-fixed.sh |  32 ++++++
 t/perf/run                         |  13 ++-
 t/t4202-log.sh                     | 160 +++++++++++++++++++++++++--
 t/t5300-pack-object.sh             |  36 +++++++
 t/t7008-grep-binary.sh             | 135 +++++++++++++++++------
 t/t7810-grep.sh                    |  81 +++++++++++---
 t/t7812-grep-icase-non-ascii.sh    |  29 ++---
 t/t7813-grep-icase-iso.sh          |   2 +-
 t/t7814-grep-recurse-submodules.sh | 215 +++++++++++++++++++++++--------------
 t/test-lib.sh                      |   3 +-
 23 files changed, 771 insertions(+), 240 deletions(-)
 create mode 100755 t/perf/p4220-log-grep-engines.sh
 create mode 100755 t/perf/p7820-grep-engines.sh
 create mode 100755 t/perf/p7821-grep-engines-fixed.sh

2.13.0.303.g4ebf302169

Reword an outdated & inaccurate 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 sense 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.

---
 Makefile     |  6 ++++--
 configure.ac | 12 ++++++++----
 2 files changed, 12 insertions(+), 6 deletions(-)

index e35542e631..eedadb8056 100644
@@ -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.

index 128165529f..deeb968daa 100644
@@ -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

2.13.0.303.g4ebf302169

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 these types of patterns using "a compile-time dependency".

Saying "libpcre" means that we're talking about libpcre.so, which is always going to be v1. This change is part of an ongoing saga to add support for libpcre2, which comes with PCRE v2.

In the future we might use some completely unrelated library to provide perl-compatible regular expression support. By wording the documentation differently and not promising any specific version of PCRE or even PCRE at all we have more wiggle room to change the implementation.

---
 Documentation/git-grep.txt         | 7 +++++--
 Documentation/rev-list-options.txt | 8 ++++++--
 2 files changed, 11 insertions(+), 4 deletions(-)

index 71f32f3508..5033483db4 100644
@@ -161,8 +161,11 @@ OPTIONS
 
 -P::
 --perl-regexp::
-	Use Perl-compatible regexp for patterns. Requires libpcre to be
-	compiled in.
+	Use Perl-compatible regular expressions for patterns.
++
+Support for these types of regular expressions is an optional
+compile-time dependency. If Git wasn't compiled with support for them
+providing this option will cause it to die.
 
 -F::
 --fixed-strings::

index a02f7324c0..a46f70c2b1 100644
@@ -92,8 +92,12 @@ endif::git-rev-list[]
 	pattern as a regular expression).
 
 --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.
++
+Support for these types of regular expressions is an optional
+compile-time dependency. If Git wasn't compiled with support for them
+providing this option will cause it to die.
 
 --remove-empty::
 	Stop when a given path disappears from the tree.

2.13.0.303.g4ebf302169

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.

---
 t/README                        |  4 ++--
 t/t7810-grep.sh                 | 28 ++++++++++++++--------------
 t/t7812-grep-icase-non-ascii.sh |  4 ++--
 t/t7813-grep-icase-iso.sh       |  2 +-
 t/test-lib.sh                   |  2 +-
 5 files changed, 20 insertions(+), 20 deletions(-)

index ab386c3681..a90cb62583 100644
@@ -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

index cee42097b0..c84c4d99f9 100755
@@ -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"

@@ -1118,11 +1118,11 @@ 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["
 '
 

@@ -1191,13 +1191,13 @@ 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 \

@@ -1208,7 +1208,7 @@ 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 \

@@ -1343,12 +1343,12 @@ 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
 '

index 169fd8d706..04a61cb8e0 100755
@@ -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 &&

index efef7fb81f..701e08a8e5 100755
@@ -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.ll� Heimur!" &&
 	git grep --perl-regexp -i "TILRAUN: H.LL� HEIMUR!"
 '

index 26b3edfb2e..04d857a42b 100644
@@ -1014,7 +1014,7 @@ 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?

2.13.0.303.g4ebf302169

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.

---
 t/t4202-log.sh | 98 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 97 insertions(+), 1 deletion(-)

index f577990716..a8dce0ca2d 100755
@@ -262,7 +262,30 @@ 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 &&
+	# basic would need \(s\) to do the same
+	git log -1 --pretty="tformat:%s" -F -E --grep="(s).c.nd" >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success PCRE '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
+	) &&
+
+	# In PCRE \d in [\d] is like saying "0-9", and matches the 2
+	# in 2e...
+	echo 2e >expect &&
+	git -C num_commits log -1 --pretty="tformat:%s" -F -E --perl-regexp --grep="[\d]" >actual &&
+	test_cmp expect actual &&
+
+	# ...in POSIX basic and extended it is the same as [d],
+	# i.e. "d", which matches 1d, but does not match 2e.
+	echo 1d >expect &&
+	git -C num_commits log -1 --pretty="tformat:%s" -F -E --grep="[\d]" >actual &&
 	test_cmp expect actual
 '
 

@@ -280,6 +303,79 @@ 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 &&
+
+		# The tagname is overridden here because creating a
+		# tag called "(1|2)" as test_commit would otherwise
+		# implicitly do would fail on e.g. MINGW.
+		test_commit "(1|2)" file B 2 &&
+
+		echo "(1|2)" >expect.fixed &&
+		cp expect.fixed expect.basic &&
+		cp expect.fixed expect.extended &&
+		cp expect.fixed expect.perl &&
+
+		# A strcmp-like match with fixed.
+		git -c grep.patternType=fixed log --pretty=tformat:%s \
+			--grep="(1|2)" >actual.fixed &&
+
+		# POSIX basic matches (, | and ) literally.
+		git -c grep.patternType=basic log --pretty=tformat:%s \
+			--grep="(.|.)" >actual.basic &&
+
+		# POSIX extended needs to have | escaped to match it
+		# literally, whereas under basic this is the same as
+		# (|2), i.e. it would also match "1". This test checks
+		# for extended by asserting that it is not matching
+		# what basic would match.
+		git -c grep.patternType=extended log --pretty=tformat:%s \
+			--grep="\|2" >actual.extended &&
+		if test_have_prereq PCRE
+		then
+			# Only PCRE would match [\d]\| with only
+			# "(1|2)" due to [\d]. POSIX basic would match
+			# both it and "1" since similarly to the
+			# extended match above it is the same as
+			# \([\d]\|\). POSIX extended would
+			# match neither.
+			git -c grep.patternType=perl log --pretty=tformat:%s \
+				--grep="[\d]\|" >actual.perl &&
+			test_cmp expect.perl actual.perl
+		fi &&
+		test_cmp expect.fixed actual.fixed &&
+		test_cmp expect.basic actual.basic &&
+		test_cmp expect.extended actual.extended &&
+
+		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 PCRE
+		then
+			git log --pretty=tformat:%s --perl-regexp \
+				--grep="[\d]\|" >actual.perl.long-arg &&
+			test_cmp expect.perl 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
+	)
+'
+
 cat > expect <<EOF
 * Second
 * sixth

2.13.0.303.g4ebf302169

Make the --regexp-ignore-case option work with --perl-regexp. This never worked, and there was no test for this. Fix the bug and add a test.

When PCRE support was added in commit 63e7e9d8b6 ("git-grep: Learn PCRE", 2011-05-09) compile_pcre_regexp() would only check opt->ignore_case, but when the --perl-regexp option was added in commit 727b6fc3ed ("log --grep: accept --basic-regexp and --perl-regexp", 2012-10-03) the code didn't set the opt->ignore_case.

Change the test suite to test for -i and --invert-regexp with basic/extended/perl patterns in addition to fixed, which was the only patternType that was tested for before in combination with those options.

---
 revision.c     |  1 +
 t/t4202-log.sh | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 56 insertions(+), 5 deletions(-)

index 8a8c1789c7..4883cdd2d0 100644
@@ -1991,6 +1991,7 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
 	} else if (!strcmp(arg, "--extended-regexp") || !strcmp(arg, "-E")) {
 		revs->grep_filter.pattern_type_option = GREP_PATTERN_TYPE_ERE;
 	} else if (!strcmp(arg, "--regexp-ignore-case") || !strcmp(arg, "-i")) {
+		revs->grep_filter.ignore_case = 1;
 		revs->grep_filter.regflags |= REG_ICASE;
 		DIFF_OPT_SET(&revs->diffopt, PICKAXE_IGNORE_CASE);
 	} else if (!strcmp(arg, "--fixed-strings") || !strcmp(arg, "-F")) {

2.13.0.303.g4ebf302169

I started hacking up a patch to fix the root cause of this, i.e. the users of the grep API should only set .ignore_case = 1 and not care about setting regflags, but it was more than a trivial change, so I didn't include it in this series:

index 3ffb5b4e81..be28c37265 100644
@@ -1151,8 +1151,6 @@ int cmd_grep(int argc, const char **argv, const

char *prefix)

        if (!opt.pattern_list)
                die(_("no pattern given."));

- if (!opt.fixed && opt.ignore_case)
- opt.regflags |= REG_ICASE;

        compile_grep_patterns(&opt);

index 47cee45067..7b13ee1043 100644
@@ -435,12 +435,11 @@ static void compile_fixed_regexp(struct grep_pat

*p, struct grep_opt *opt)

static void compile_regexp(struct grep_pat *p, struct grep_opt *opt) {
- int icase, ascii_only;

+       int ascii_only;
        int err;

        p->word_regexp = opt->word_regexp;
        p->ignore_case = opt->ignore_case;
-       icase          = opt->regflags & REG_ICASE || p->ignore_case;
        ascii_only     = !has_non_ascii(p->pattern);

        /*
@@ -456,12 +455,12 @@ static void compile_regexp(struct grep_pat *p,
struct grep_opt *opt)
         * want to use kws.
         */
        if (opt->fixed || is_fixed(p->pattern, p->patternlen))
-               p->fixed = !icase || ascii_only;
+               p->fixed = !p->ignore_case || ascii_only;
        else
                p->fixed = 0;

        if (p->fixed) {
-               p->kws = kwsalloc(icase ? tolower_trans_tbl : NULL);
+               p->kws = kwsalloc(p->ignore_case ? tolower_trans_tbl : NULL);
                kwsincr(p->kws, p->pattern, p->patternlen);
                kwsprep(p->kws);
                return;
@@ -480,6 +479,8 @@ static void compile_regexp(struct grep_pat *p,
struct grep_opt *opt)
                return;
        }

+ if (p->ignore_case)

+               opt->regflags |= REG_ICASE;
        err = regcomp(&p->regexp, p->pattern, opt->regflags);
        if (err) {
                char errbuf[1024];

index 4883cdd2d0..30c23a1098 100644
@@ -1992,7 +1992,6 @@ static int handle_revision_opt(struct rev_info

*revs, int argc, const char **arg

                revs->grep_filter.pattern_type_option = GREP_PATTERN_TYPE_ERE;
        } else if (!strcmp(arg, "--regexp-ignore-case") || !strcmp(arg, "-i")) {
                revs->grep_filter.ignore_case = 1;
-               revs->grep_filter.regflags |= REG_ICASE;
                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;

But an even better solution is to get rid of passing the regflags field in grep_opt entirely, this conflicts with some of my later patches:

index 3ffb5b4e81..be28c37265 100644
@@ -1151,8 +1151,6 @@ int cmd_grep(int argc, const char **argv, const

char *prefix)

        if (!opt.pattern_list)
                die(_("no pattern given."));

- if (!opt.fixed && opt.ignore_case)
- opt.regflags |= REG_ICASE;

        compile_grep_patterns(&opt);

index 47cee45067..1bde7037ba 100644
@@ -34,7 +34,6 @@ void init_grep_defaults(void)
        memset(opt, 0, sizeof(*opt));
        opt->relative = 1;
        opt->pathname = 1;
-       opt->regflags = REG_NEWLINE;
        opt->max_depth = -1;
        opt->pattern_type_option = GREP_PATTERN_TYPE_UNSPECIFIED;
        opt->extended_regexp_option = 0;

@@ -156,7 +155,6 @@ void grep_init(struct grep_opt *opt, const char *prefix)
        opt->linenum = def->linenum;
        opt->max_depth = def->max_depth;
        opt->pathname = def->pathname;
-       opt->regflags = def->regflags;
        opt->relative = def->relative;
        opt->output = def->output;
 

@@ -179,25 +177,25 @@ 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->regflags &= ~REG_EXTENDED;
+               opt->extended = 0;
                break;
         case GREP_PATTERN_TYPE_ERE:
                opt->fixed = 0;
                opt->pcre = 0;
-               opt->regflags |= REG_EXTENDED;
+               opt->extended = 1;
                break;

        case GREP_PATTERN_TYPE_FIXED:
                opt->fixed = 1;
                opt->pcre = 0;
-               opt->regflags &= ~REG_EXTENDED;
+               opt->extended = 0;
                break;

        case GREP_PATTERN_TYPE_PCRE:
                opt->fixed = 0;
                opt->pcre = 1;
-               opt->regflags &= ~REG_EXTENDED;
+               opt->extended = 0;
                break;
        }
 }
@@ -415,10 +413,9 @@ static void compile_fixed_regexp(struct grep_pat
*p, struct grep_opt *opt)
 {
        struct strbuf sb = STRBUF_INIT;
        int err;

- int regflags;
+ int regflags = REG_NEWLINE;

        basic_regex_quote_buf(&sb, p->pattern);
-       regflags = opt->regflags & ~REG_EXTENDED;
        if (opt->ignore_case)
                regflags |= REG_ICASE;
        err = regcomp(&p->regexp, sb.buf, regflags);

@@ -435,12 +432,12 @@ static void compile_fixed_regexp(struct grep_pat *p, struct grep_opt *opt)

static void compile_regexp(struct grep_pat *p, struct grep_opt *opt) {
- int icase, ascii_only;

+       int ascii_only;
        int err;

+ int regflags = REG_NEWLINE;

        p->word_regexp = opt->word_regexp;
        p->ignore_case = opt->ignore_case;
-       icase          = opt->regflags & REG_ICASE || p->ignore_case;
        ascii_only     = !has_non_ascii(p->pattern);

        /*
@@ -456,12 +453,12 @@ static void compile_regexp(struct grep_pat *p,
struct grep_opt *opt)
         * want to use kws.
         */
        if (opt->fixed || is_fixed(p->pattern, p->patternlen))
-               p->fixed = !icase || ascii_only;
+               p->fixed = !p->ignore_case || ascii_only;
        else
                p->fixed = 0;

        if (p->fixed) {
-               p->kws = kwsalloc(icase ? tolower_trans_tbl : NULL);
+               p->kws = kwsalloc(p->ignore_case ? tolower_trans_tbl : NULL);
                kwsincr(p->kws, p->pattern, p->patternlen);
                kwsprep(p->kws);
                return;
@@ -480,7 +477,11 @@ static void compile_regexp(struct grep_pat *p,
struct grep_opt *opt)
                return;
        }

- err = regcomp(&p->regexp, p->pattern, opt->regflags);
+ if (p->ignore_case)
+ regflags |= REG_ICASE;
+ if (opt->extended)
+ regflags |= REG_EXTENDED;

+       err = regcomp(&p->regexp, p->pattern, regflags);
        if (err) {
                char errbuf[1024];
                regerror(err, &p->regexp, errbuf, 1024);

index 267534ca24..d9d603deb1 100644
@@ -129,7 +129,6 @@ struct grep_opt {
        char color_match_selected[COLOR_MAXLEN];
        char color_selected[COLOR_MAXLEN];
        char color_sep[COLOR_MAXLEN];
-       int regflags;
        unsigned pre_context;
        unsigned post_context;
        unsigned last_shown;

index 4883cdd2d0..67240d38af 100644
@@ -1362,7 +1362,6 @@ void init_revisions(struct rev_info *revs, const

char *prefix)

        init_grep_defaults();
        grep_init(&revs->grep_filter, prefix);
        revs->grep_filter.status_only = 1;

- revs->grep_filter.regflags = REG_NEWLINE;

        diff_setup(&revs->diffopt);
        if (prefix && !revs->diffopt.prefix) {
@@ -1992,7 +1991,6 @@ static int handle_revision_opt(struct rev_info
*revs, int argc, const char **arg
                revs->grep_filter.pattern_type_option = GREP_PATTERN_TYPE_ERE;
        } else if (!strcmp(arg, "--regexp-ignore-case") || !strcmp(arg, "-i")) {
                revs->grep_filter.ignore_case = 1;
-               revs->grep_filter.regflags |= REG_ICASE;
                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;

But as all this code cleanup isn't needed for fixing this bug, and I'd really like to get this series merged into next/master ASAP so I can start submitting the grep/pcre patches that are actually interesting, let's leave this orthogonal code cleanup for now.

Ah, sorry. Now I re-read my response, "Looks good. I however wonder..." does sound like I am requesting to do something more to solve the same issue. I shouldn't have phrased it that way. It was more like "while I was staring the context lines of your patch, I noticed this tangent", nothing more.

Yes, that may be a good direction to go in longer term, but let's not push it before the other bits already in flight land safely.

Yes. Thanks.

Here's a follow-up to a small tangent of discussion in my ~30 patch grep cleanup series.

There are no functional changes here, just getting rid of dead code, and removing the POSIX regflags variable from the grep API used by grep/log, which was the cause of the long-standing bug of "-i" not working with PCRE when used via git-log.

Ævar Arnfjörð Bjarmason (5):
grep: remove redundant double assignment to 0
grep: remove redundant grep pattern type assignment
grep: remove redundant "fixed" field re-assignment to 0
grep: remove redundant and verbose re-assignments to 0
grep: remove regflags from the public grep_opt API

 builtin/grep.c |  2 --
 grep.c         | 59 +++++++++++++++++++++++++++++++++-------------------------
 grep.h         |  1 -
 revision.c     |  2 --
 4 files changed, 34 insertions(+), 30 deletions(-)

2.13.1.611.g7e3b11ae1

Stop assigning 0 to the extended_regexp_option field right after we've zeroed out the entire struct with memset() just a few lines earlier.

Unlike some of the code being refactored in subsequent commits, this was always completely redundant. See the original code introduced in 84befcd0a4 ("grep: add a grep.patternType configuration setting", 2012-08-03).

---
 grep.c | 1 -
 1 file changed, 1 deletion(-)

index 98733db623..29439886e7 100644
@@ -38,7 +38,6 @@ void init_grep_defaults(void)
 	opt->regflags = REG_NEWLINE;
 	opt->max_depth = -1;
 	opt->pattern_type_option = GREP_PATTERN_TYPE_UNSPECIFIED;
-	opt->extended_regexp_option = 0;
 	color_set(opt->color_context, "");
 	color_set(opt->color_filename, "");
 	color_set(opt->color_function, "");

2.13.1.611.g7e3b11ae1

Remove a redundant assignment to extended_regexp_option to make it zero if grep.extendedRegexp is not set. This is always called right after init_grep_defaults() which memsets the entire structure to 0.

This is a logical follow-up to my commit to remove redundant regflags assignments[1]. This logic was originally introduced in [2], but as explained in the former commit it's working around a pattern in our code that no longer exists, and is now confusing as it leads the reader to think that this needs to be flipped back & forth.

1. e0b9f8ae09 ("grep: remove redundant regflags assignments", 2017-05-25)
2. b22520a37c ("grep: allow -E and -n to be turned on by default via configuration", 2011-03-30)

---
 grep.c | 2 --
 1 file changed, 2 deletions(-)

index 29439886e7..6614042fdc 100644
@@ -80,8 +80,6 @@ int grep_config(const char *var, const char *value, void *cb)
 	if (!strcmp(var, "grep.extendedregexp")) {
 		if (git_config_bool(var, value))
 			opt->extended_regexp_option = 1;
-		else
-			opt->extended_regexp_option = 0;
 		return 0;
 	}
 

2.13.1.611.g7e3b11ae1

On Thu, Jun 29 2017, Stefan Beller jotted:

I didn't think about that. Good point. I'll do that instead in v2.

Remove the redundant re-assignment of the fixed field to zero right after the entire struct has been set to zero via memset(...).

Unlike some nearby commits this pattern doesn't date back to the pattern described in e0b9f8ae09 ("grep: remove redundant regflags assignments", 2017-05-25), instead it was apparently cargo-culted in 9eceddeec6 ("Use kwset in grep", 2011-08-21).

---
 grep.c | 2 --
 1 file changed, 2 deletions(-)

index 6614042fdc..7cd8a6512f 100644
@@ -627,8 +627,6 @@ static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
 	    has_null(p->pattern, p->patternlen) ||
 	    is_fixed(p->pattern, p->patternlen))
 		p->fixed = !icase || ascii_only;
-	else
-		p->fixed = 0;
 
 	if (p->fixed) {
 		p->kws = kwsalloc(icase ? tolower_trans_tbl : NULL);

2.13.1.611.g7e3b11ae1

Remove the redundant re-assignments of the fixed/pcre1/pcre2 fields to zero right after the entire struct has been set to zero via memset(...).

See an earlier related cleanup commit e0b9f8ae09 ("grep: remove redundant regflags assignments", 2017-05-25) for an explanation of why the code was structured like this to begin with.

---
 grep.c | 11 -----------
 1 file changed, 11 deletions(-)

index 7cd8a6512f..736e1e00d6 100644
@@ -175,28 +175,18 @@ static void grep_set_pattern_type_option(enum grep_pattern_type pattern_type, st
 		/* fall through */
 
 	case GREP_PATTERN_TYPE_BRE:
-		opt->fixed = 0;
-		opt->pcre1 = 0;
-		opt->pcre2 = 0;
 		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;
 		break;
 
 	case GREP_PATTERN_TYPE_PCRE:
-		opt->fixed = 0;
 #ifdef USE_LIBPCRE2
-		opt->pcre1 = 0;
 		opt->pcre2 = 1;
 #else
 		/*

@@ -206,7 +196,6 @@ static void grep_set_pattern_type_option(enum grep_pattern_type pattern_type, st
 		 * "cannot use Perl-compatible regexes[...]".
 		 */
 		opt->pcre1 = 1;
-		opt->pcre2 = 0;
 #endif
 		break;
 	}

2.13.1.611.g7e3b11ae1

Refactor calls to the grep machinery to always pass opt.ignore_case & opt.extended_regexp_option instead of setting the equivalent regflags bits.

The bug fixed when making -i work with -P in commit 9e3cbc59d5 ("log:
make --regexp-ignore-case work with --perl-regexp", 2017-05-20) was really just plastering over the code smell which this change fixes.

See my "Re: [PATCH v3 05/30] log: make --regexp-ignore-case work with --perl-regexp"[1] for the discussion leading up to this.

The reason for adding the extensive commentary here is that I discovered some subtle complexity in implementing this that really should be called out explicitly to future readers.

Before this change we'd rely on the difference between extended_regexp_option and regflags to serve as a membrane between our preliminary parsing of grep.extendedRegexp and grep.patternType, and what we decided to do internally.

Now that those two are the same thing, it's necessary to unset extended_regexp_option just before we commit in cases where both of those config variables are set. See 84befcd0a4 ("grep: add a grep.patternType configuration setting", 2012-08-03) for the code and documentation related to that.

The explanation of why the if/else branches in grep_commit_pattern_type() are ordered the way they are exists in that commit message, but I think it's worth calling this subtlety out explicitly with a comment for future readers.

Unrelated to that: I could have factored out the default REG_NEWLINE flag into some custom GIT_GREP_H_DEFAULT_REGFLAGS or something, but since it's just used in two places I didn't think it was worth the effort.

As an aside we're really lacking test coverage regflags being initiated as 0 instead of as REG_NEWLINE. Tests will fail if it's removed from compile_regexp(), but not if it's removed from compile_fixed_regexp(). I have not dug to see if it's actually needed in the latter case or if the test coverage is lacking.

1. <CACBZZX6Hp4Q4TOj_X1fbdCA4twoXF5JemZ5ZbEn7wmkA=1KO2g@mail.gmail.com>
(https://public-inbox.org/git/CACBZZX6Hp4Q4TOj_X1fbdCA4twoXF5JemZ5ZbEn7wmkA=1KO2g@mail.gmail.com/)

---
 builtin/grep.c |  2 --
 grep.c         | 43 ++++++++++++++++++++++++++++++++++---------
 grep.h         |  1 -
 revision.c     |  2 --
 4 files changed, 34 insertions(+), 14 deletions(-)

index f61a9d938b..b682966439 100644
@@ -1169,8 +1169,6 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 
 	if (!opt.pattern_list)
 		die(_("no pattern given."));
-	if (!opt.fixed && opt.ignore_case)
-		opt.regflags |= REG_ICASE;
 
 	/*
 	 * We have to find "--" in a separate pass, because its presence

index b8f93bfc2d..0c091e5104 100644
@@ -162,7 +162,6 @@ struct grep_opt {
 	char color_match_selected[COLOR_MAXLEN];
 	char color_selected[COLOR_MAXLEN];
 	char color_sep[COLOR_MAXLEN];
-	int regflags;
 	unsigned pre_context;
 	unsigned post_context;
 	unsigned last_shown;

index e181ad1b70..207103d211 100644
@@ -1362,7 +1362,6 @@ void init_revisions(struct rev_info *revs, const char *prefix)
 	init_grep_defaults();
 	grep_init(&revs->grep_filter, prefix);
 	revs->grep_filter.status_only = 1;
-	revs->grep_filter.regflags = REG_NEWLINE;
 
 	diff_setup(&revs->diffopt);
 	if (prefix && !revs->diffopt.prefix) {

@@ -2022,7 +2021,6 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
 		revs->grep_filter.pattern_type_option = GREP_PATTERN_TYPE_ERE;
 	} else if (!strcmp(arg, "--regexp-ignore-case") || !strcmp(arg, "-i")) {
 		revs->grep_filter.ignore_case = 1;
-		revs->grep_filter.regflags |= REG_ICASE;
 		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;

2.13.1.611.g7e3b11ae1

Up to here the commit message is inspiring confidence.

This sounds as if extra careful review is needed.

On Thu, Jun 29 2017, Stefan Beller jotted:

Thanks.

Note though (since I didn't say this explicitly) nothing about this commit changes the semanics of what we pass to regcomp, I'm just noting this caveat with REG_NEWLINE as an aside since I'm moving it around.

I mean this "else if" code *must* be in that order, i.e.:

	else if (opt->pattern_type_option != GREP_PATTERN_TYPE_UNSPECIFIED)
		grep_set_pattern_type_option(opt->pattern_type_option, opt);
	else if (opt->extended_regexp_option)
		grep_set_pattern_type_option(GREP_PATTERN_TYPE_ERE, opt);

Not:

	else if (opt->extended_regexp_option)
		grep_set_pattern_type_option(GREP_PATTERN_TYPE_ERE, opt);
	else if (opt->pattern_type_option != GREP_PATTERN_TYPE_UNSPECIFIED)
		grep_set_pattern_type_option(opt->pattern_type_option, opt);

Since we only want to pay attention to grep.extendedRegexp it grep.patternType is not set. If grep.patternType is set then the pattern_type_option will not be GREP_PATTERN_TYPE_UNSPECIFIED (but e.g. GREP_PATTERN_TYPE_BRE).

Ah you mean the whole "When committing to the pattern type by" comment + code. Yeah I think that makes sense. I'll try that for v2 and see if it's better.

*Points up at "moving it around" comment above*

Addresses comments from Stefan Beller (thanks!). I looked into it and the REG_NEWLINE flag was redundant in 1/2 cases, see 6/6 for the removal of that.

I looked into refactoring 5/6 as noted in [email protected], but for the reasons now explained in the last paragraph of 5/6 decided not to and to keep it as it was.

Ævar Arnfjörð Bjarmason (6):
grep: remove redundant double assignment to 0
grep: adjust a redundant grep pattern type assignment
grep: remove redundant "fixed" field re-assignment to 0
grep: remove redundant and verbose re-assignments to 0
grep: remove regflags from the public grep_opt API
grep: remove redundant REG_NEWLINE when compiling fixed regex

 builtin/grep.c |  2 --
 grep.c         | 62 +++++++++++++++++++++++++++++++++-------------------------
 grep.h         |  1 -
 revision.c     |  2 --
 4 files changed, 35 insertions(+), 32 deletions(-)

2.13.1.611.g7e3b11ae1

Stop assigning 0 to the extended_regexp_option field right after we've zeroed out the entire struct with memset() just a few lines earlier.

Unlike some of the code being refactored in subsequent commits, this was always completely redundant. See the original code introduced in 84befcd0a4 ("grep: add a grep.patternType configuration setting", 2012-08-03).

---
 grep.c | 1 -
 1 file changed, 1 deletion(-)

index 98733db623..29439886e7 100644
@@ -38,7 +38,6 @@ void init_grep_defaults(void)
 	opt->regflags = REG_NEWLINE;
 	opt->max_depth = -1;
 	opt->pattern_type_option = GREP_PATTERN_TYPE_UNSPECIFIED;
-	opt->extended_regexp_option = 0;
 	color_set(opt->color_context, "");
 	color_set(opt->color_filename, "");
 	color_set(opt->color_function, "");

2.13.1.611.g7e3b11ae1

Adjust a now-redundant assignment to extended_regexp_option to make it zero if grep.extendedRegexp is not set. This is always called right after init_grep_defaults() which memsets the entire structure to 0, so there's no need to set it again to zero.

However the reason for the if/else pattern is a holdover from[1] where this was adjusted from a bitfield assignment to a boolean. Rather than getting rid of the assignment to 0 in all cases, let's just use the value returned by git_config_bool(), which is more idiomatic and in sync with the rest of the boolean handling in this function.

This is a logical follow-up to my commit to remove redundant regflags assignments[2]. This logic was originally introduced in [3], but as explained in the former commit it's working around a pattern in our code that no longer exists, and is now confusing as it leads the reader to think that this needs to be flipped back & forth.

1. 84befcd0a4 ("grep: add a grep.patternType configuration setting", 2012-08-03)
2. e0b9f8ae09 ("grep: remove redundant regflags assignments", 2017-05-25)
3. b22520a37c ("grep: allow -E and -n to be turned on by default via configuration", 2011-03-30)

---
 grep.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

index 29439886e7..817270d081 100644
@@ -78,10 +78,7 @@ int grep_config(const char *var, const char *value, void *cb)
 		return -1;
 
 	if (!strcmp(var, "grep.extendedregexp")) {
-		if (git_config_bool(var, value))
-			opt->extended_regexp_option = 1;
-		else
-			opt->extended_regexp_option = 0;
+		opt->extended_regexp_option = git_config_bool(var, value);
 		return 0;
 	}
 

2.13.1.611.g7e3b11ae1

Remove the redundant re-assignment of the fixed field to zero right after the entire struct has been set to zero via memset(...).

Unlike some nearby commits this pattern doesn't date back to the pattern described in e0b9f8ae09 ("grep: remove redundant regflags assignments", 2017-05-25), instead it was apparently cargo-culted in 9eceddeec6 ("Use kwset in grep", 2011-08-21).

---
 grep.c | 2 --
 1 file changed, 2 deletions(-)

index 817270d081..86dc9b696f 100644
@@ -626,8 +626,6 @@ static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
 	    has_null(p->pattern, p->patternlen) ||
 	    is_fixed(p->pattern, p->patternlen))
 		p->fixed = !icase || ascii_only;
-	else
-		p->fixed = 0;
 
 	if (p->fixed) {
 		p->kws = kwsalloc(icase ? tolower_trans_tbl : NULL);

2.13.1.611.g7e3b11ae1

Remove the redundant re-assignments of the fixed/pcre1/pcre2 fields to zero right after the entire struct has been set to zero via memset(...).

See an earlier related cleanup commit e0b9f8ae09 ("grep: remove redundant regflags assignments", 2017-05-25) for an explanation of why the code was structured like this to begin with.

---
 grep.c | 11 -----------
 1 file changed, 11 deletions(-)

index 86dc9b696f..7fcdaa0753 100644
@@ -174,28 +174,18 @@ static void grep_set_pattern_type_option(enum grep_pattern_type pattern_type, st
 		/* fall through */
 
 	case GREP_PATTERN_TYPE_BRE:
-		opt->fixed = 0;
-		opt->pcre1 = 0;
-		opt->pcre2 = 0;
 		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;
 		break;
 
 	case GREP_PATTERN_TYPE_PCRE:
-		opt->fixed = 0;
 #ifdef USE_LIBPCRE2
-		opt->pcre1 = 0;
 		opt->pcre2 = 1;
 #else
 		/*

@@ -205,7 +195,6 @@ static void grep_set_pattern_type_option(enum grep_pattern_type pattern_type, st
 		 * "cannot use Perl-compatible regexes[...]".
 		 */
 		opt->pcre1 = 1;
-		opt->pcre2 = 0;
 #endif
 		break;
 	}

2.13.1.611.g7e3b11ae1

Refactor calls to the grep machinery to always pass opt.ignore_case & opt.extended_regexp_option instead of setting the equivalent regflags bits.

The bug fixed when making -i work with -P in commit 9e3cbc59d5 ("log:
make --regexp-ignore-case work with --perl-regexp", 2017-05-20) was really just plastering over the code smell which this change fixes.

The reason for adding the extensive commentary here is that I discovered some subtle complexity in implementing this that really should be called out explicitly to future readers.

Before this change we'd rely on the difference between extended_regexp_option and regflags to serve as a membrane between our preliminary parsing of grep.extendedRegexp and grep.patternType, and what we decided to do internally.

Now that those two are the same thing, it's necessary to unset extended_regexp_option just before we commit in cases where both of those config variables are set. See 84befcd0a4 ("grep: add a grep.patternType configuration setting", 2012-08-03) for the code and documentation related to that.

The explanation of why the if/else branches in grep_commit_pattern_type() are ordered the way they are exists in that commit message, but I think it's worth calling this subtlety out explicitly with a comment for future readers.

Even though grep_commit_pattern_type() is the only caller of grep_set_pattern_type_option() it's simpler to reset the extended_regexp_option flag in the latter, since 2/3 branches in the former would otherwise need to reset it, this way we can do it in one place.

---
 builtin/grep.c |  2 --
 grep.c         | 43 ++++++++++++++++++++++++++++++++++---------
 grep.h         |  1 -
 revision.c     |  2 --
 4 files changed, 34 insertions(+), 14 deletions(-)

index f61a9d938b..b682966439 100644
@@ -1169,8 +1169,6 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 
 	if (!opt.pattern_list)
 		die(_("no pattern given."));
-	if (!opt.fixed && opt.ignore_case)
-		opt.regflags |= REG_ICASE;
 
 	/*
 	 * We have to find "--" in a separate pass, because its presence

index b8f93bfc2d..0c091e5104 100644
@@ -162,7 +162,6 @@ struct grep_opt {
 	char color_match_selected[COLOR_MAXLEN];
 	char color_selected[COLOR_MAXLEN];
 	char color_sep[COLOR_MAXLEN];
-	int regflags;
 	unsigned pre_context;
 	unsigned post_context;
 	unsigned last_shown;

index e181ad1b70..207103d211 100644
@@ -1362,7 +1362,6 @@ void init_revisions(struct rev_info *revs, const char *prefix)
 	init_grep_defaults();
 	grep_init(&revs->grep_filter, prefix);
 	revs->grep_filter.status_only = 1;
-	revs->grep_filter.regflags = REG_NEWLINE;
 
 	diff_setup(&revs->diffopt);
 	if (prefix && !revs->diffopt.prefix) {

@@ -2022,7 +2021,6 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
 		revs->grep_filter.pattern_type_option = GREP_PATTERN_TYPE_ERE;
 	} else if (!strcmp(arg, "--regexp-ignore-case") || !strcmp(arg, "-i")) {
 		revs->grep_filter.ignore_case = 1;
-		revs->grep_filter.regflags |= REG_ICASE;
 		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;

2.13.1.611.g7e3b11ae1

Remove the redundant REG_NEWLINE regcomp() flag from the code that compiles a fixed-string regular-expression.

The REG_NEWLINE causes metacharacters such as "." to match a newline, since the basic_regex_quote_buf() function being called here escapes all metacharacters using REG_NEWLINE is confusing and redundant.

The use of this flag was introduced as an unintended emergent property of 793dc676e0 ("grep/icase: avoid kwsset when -F is specified", 2016-06-25).

That change amended the existing regflags, which were initialized to REG_NEWLINE in init_grep_defaults() assuming a subsequent non-fixed regcomp().

Manual testing reveals that this was always redundant, since no flags of any use were inherited from opt->regflags even back then. 793dc676e0 passes all tests with this on top:

    diff --git a/grep.c b/grep.c
    index 627ae3e3e8..89e84ed7fd 100644
    --- a/grep.c
    +++ b/grep.c
    @@ -407,3 +407,3 @@ static void compile_fixed_regexp(struct grep_pat *p, struct grep_opt *opt)
            basic_regex_quote_buf(&sb, p->pattern);
    -       regflags = opt->regflags & ~REG_EXTENDED;
    +       regflags = 0;
            if (opt->ignore_case)

Since this isn't used for anything and never was, remove it to reduce confusion when reading this code.

---
 grep.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 11a86548d6..2efec0e182 100644
@@ -593,7 +593,7 @@ static void compile_fixed_regexp(struct grep_pat *p, struct grep_opt *opt)
 {
 	struct strbuf sb = STRBUF_INIT;
 	int err;
-	int regflags = REG_NEWLINE;
+	int regflags = 0;
 
 	basic_regex_quote_buf(&sb, p->pattern);
 	if (opt->ignore_case)

2.13.1.611.g7e3b11ae1

Add a test asserting that when --perl-regexp (and -P for grep) is given to git-grep & git-log that we die with an error.

In developing the PCRE v2 series I introduced a regression where -P would (through control-flow fall-through) become synonymous with basic POSIX matching. I.e. 'git grep -P '[\d]' would match "d" instead of digits.

The entire test suite would still pass with this serious regression, since everything that tested for --perl-regexp would be guarded by the PCRE prerequisite, fix that blind-spot by adding tests under !PCRE asserting that git must die when given --perl-regexp or -P.

---
 t/t4202-log.sh  |  4 +++-
 t/t7810-grep.sh | 12 ++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

index 547f4c19a7..dbed3efeee 100755
@@ -418,7 +418,9 @@ test_expect_success 'log with various grep.patternType configurations & command-
 			git log --pretty=tformat:%s --perl-regexp \
 				--grep="[\d]\|" >actual.perl.long-arg &&
 			test_cmp expect.perl actual.perl.long-arg
-
+		else
+			test_must_fail git log --perl-regexp \
+				--grep="[\d]\|"
 		fi &&
 		test_cmp expect.fixed actual.fixed.long-arg &&
 		test_cmp expect.basic actual.basic.long-arg &&

index c84c4d99f9..8d69113695 100755
@@ -281,6 +281,10 @@ do
 		test_cmp expected actual
 	'
 
+	test_expect_success !PCRE "grep $L with grep.patterntype=perl errors without PCRE" '
+		test_must_fail git -c grep.patterntype=perl grep "foo.*bar"
+	'
+
 	test_expect_success "grep $L with grep.patternType=default and grep.extendedRegexp=true" '
 		echo "${HC}ab:abc" >expected &&
 		git \

@@ -1058,11 +1062,19 @@ test_expect_success PCRE 'grep --perl-regexp pattern' '
 	test_cmp expected actual
 '
 
+test_expect_success !PCRE 'grep --perl-regexp pattern errors without PCRE' '
+	test_must_fail git grep --perl-regexp "foo.*bar"
+'
+
 test_expect_success PCRE 'grep -P pattern' '
 	git grep -P "\p{Ps}.*?\p{Pe}" hello.c >actual &&
 	test_cmp expected actual
 '
 
+test_expect_success !PCRE 'grep -P pattern errors without PCRE' '
+	test_must_fail git grep -P "foo.*bar"
+'
+
 test_expect_success 'grep pattern with grep.extendedRegexp=true' '
 	>empty &&
 	test_must_fail git -c grep.extendedregexp=true \

2.13.0.303.g4ebf302169

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.

---
 t/t7810-grep.sh | 7 +++++++
 1 file changed, 7 insertions(+)

index 8d69113695..daa906b9b0 100755
@@ -1114,6 +1114,13 @@ test_expect_success PCRE '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["
 '

2.13.0.303.g4ebf302169

Change a non-ASCII case-insensitive test case to stop using --debug, and instead simply test for the expected results.

The test coverage remains the same with this change, but the test won't break due to internal refactoring.

This test was added in commit 793dc676e0 ("grep/icase: avoid kwsset when -F is specified", 2016-06-25). It was asserting that the regex must be compiled with compile_fixed_regexp(), instead test for the expected results, allowing the underlying implementation to change.

---
 t/t7812-grep-icase-non-ascii.sh | 25 +++++--------------------
 1 file changed, 5 insertions(+), 20 deletions(-)

index 04a61cb8e0..0059a1f837 100755
@@ -36,29 +36,14 @@ test_expect_success GETTEXT_LOCALE,PCRE 'grep pcre utf-8 string with "+"' '
 '
 
 test_expect_success REGEX_LOCALE 'grep literal string, with -F' '
-	git grep --debug -i -F "TILRAUN: Halló Heimur!"  2>&1 >/dev/null |
-		 grep fixed >debug1 &&
-	test_write_lines "fixed TILRAUN: Halló Heimur!" >expect1 &&
-	test_cmp expect1 debug1 &&
-
-	git grep --debug -i -F "TILRAUN: HALLÓ HEIMUR!"  2>&1 >/dev/null |
-		 grep fixed >debug2 &&
-	test_write_lines "fixed TILRAUN: HALLÓ HEIMUR!" >expect2 &&
-	test_cmp expect2 debug2
+	git grep -i -F "TILRAUN: Halló Heimur!" &&
+	git grep -i -F "TILRAUN: HALLÓ HEIMUR!"
 '
 
 test_expect_success REGEX_LOCALE 'grep string with regex, with -F' '
-	test_write_lines "^*TILR^AUN:.* \\Halló \$He[]imur!\$" >file &&
-
-	git grep --debug -i -F "^*TILR^AUN:.* \\Halló \$He[]imur!\$" 2>&1 >/dev/null |
-		 grep fixed >debug1 &&
-	test_write_lines "fixed \\^*TILR^AUN:\\.\\* \\\\Halló \$He\\[]imur!\\\$" >expect1 &&
-	test_cmp expect1 debug1 &&
-
-	git grep --debug -i -F "^*TILR^AUN:.* \\HALLÓ \$HE[]IMUR!\$"  2>&1 >/dev/null |
-		 grep fixed >debug2 &&
-	test_write_lines "fixed \\^*TILR^AUN:\\.\\* \\\\HALLÓ \$HE\\[]IMUR!\\\$" >expect2 &&
-	test_cmp expect2 debug2
+	test_write_lines "TILRAUN: Halló Heimur [abc]!" >file3 &&
+	git add file3 &&
+	git grep -i -F "TILRAUN: Halló Heimur [abc]!" file3
 '
 
 test_expect_success REGEX_LOCALE 'pickaxe -i on non-ascii' '

2.13.0.303.g4ebf302169

Add tests for --threads=N being supplied on the command-line, or when grep.threads=N being supplied in the configuration.

When the threading support was made run-time configurable in commit 89f09dd34e ("grep: add --threads=<num> option and grep.threads configuration", 2015-12-15) no tests were added for it.

In developing a change to the grep code I was able to make '--threads=1 <pat>` segfault, while the test suite still passed. This change fixes that blind spot in the tests.

In addition to asserting that asking for N threads shouldn't segfault, test that the grep output given any N is the same.

The choice to test only 1..10 as opposed to 1..8 or 1..16 or whatever is arbitrary. Testing 1..1024 works locally for me (but gets noticeably slower as more threads are spawned). Given the structure of the code there's no reason to test an arbitrary number of threads, only 0, 1 and >=2 are special modes of operation.

A later patch introduces a PTHREADS test prerequisite which is true under NO_PTHREADS=UnfortunatelyYes, but even under NO_PTHREADS it's fine to test --threads=N, we'll just ignore it and not use threading. So these tests also make sense under that mode to assert that --threads=N without pthreads still returns expected results.

---
 t/t7810-grep.sh | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

index daa906b9b0..561709ef6a 100755
@@ -775,6 +775,22 @@ test_expect_success 'grep -W with userdiff' '
 	test_cmp expected actual
 '
 
+for threads in $(test_seq 0 10)
+do
+	test_expect_success "grep --threads=$threads & -c grep.threads=$threads" "
+		git grep --threads=$threads . >actual.$threads &&
+		if test $threads -ge 1
+		then
+			test_cmp actual.\$(($threads - 1)) actual.$threads
+		fi &&
+		git -c grep.threads=$threads grep . >actual.$threads &&
+		if test $threads -ge 1
+		then
+			test_cmp actual.\$(($threads - 1)) actual.$threads
+		fi
+	"
+done
+
 test_expect_success 'grep from a subdirectory to search wider area (1)' '
 	mkdir -p s &&
 	(

2.13.0.303.g4ebf302169

Amend the submodule recursion test to prepare it for subsequent tests of whether it passes along the grep.patternType to the submodule greps.

This is the result of searching & replacing:

    foobar -> (1|2)d(3|4)
    foo    -> (1|2)
    bar    -> (3|4)

Currently there's no tests for whether e.g. -P or -E is correctly passed along, tests for that will be added in a follow-up change, but first add content to the tests which will match differently under different regex engines.

Reuse the pattern established in an earlier commit of mine in this series ("log: add exhaustive tests for pattern style options & config", 2017-04-07). The pattern "(.|.)[\d]" will match this content differently under fixed/basic/extended & perl.

This test code was originally added in commit 0281e487fd ("grep:
optionally recurse into submodules", 2016-12-16).

---
 t/t7814-grep-recurse-submodules.sh | 166 ++++++++++++++++++-------------------
 1 file changed, 83 insertions(+), 83 deletions(-)

index 5b6eb3a65e..1472855e1d 100755
@@ -9,13 +9,13 @@ submodules.
 . ./test-lib.sh
 
 test_expect_success 'setup directory structure and submodule' '
-	echo "foobar" >a &&
+	echo "(1|2)d(3|4)" >a &&
 	mkdir b &&
-	echo "bar" >b/b &&
+	echo "(3|4)" >b/b &&
 	git add a b &&
 	git commit -m "add a and b" &&
 	git init submodule &&
-	echo "foobar" >submodule/a &&
+	echo "(1|2)d(3|4)" >submodule/a &&
 	git -C submodule add a &&
 	git -C submodule commit -m "add a" &&
 	git submodule add ./submodule &&

@@ -24,18 +24,18 @@ test_expect_success 'setup directory structure and submodule' '
 
 test_expect_success 'grep correctly finds patterns in a submodule' '
 	cat >expect <<-\EOF &&
-	a:foobar
-	b/b:bar
-	submodule/a:foobar
+	a:(1|2)d(3|4)
+	b/b:(3|4)
+	submodule/a:(1|2)d(3|4)
 	EOF
 
-	git grep -e "bar" --recurse-submodules >actual &&
+	git grep -e "(3|4)" --recurse-submodules >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep and basic pathspecs' '
 	cat >expect <<-\EOF &&
-	submodule/a:foobar
+	submodule/a:(1|2)d(3|4)
 	EOF
 
 	git grep -e. --recurse-submodules -- submodule >actual &&

@@ -44,7 +44,7 @@ test_expect_success 'grep and basic pathspecs' '
 
 test_expect_success 'grep and nested submodules' '
 	git init submodule/sub &&
-	echo "foobar" >submodule/sub/a &&
+	echo "(1|2)d(3|4)" >submodule/sub/a &&
 	git -C submodule/sub add a &&
 	git -C submodule/sub commit -m "add a" &&
 	git -C submodule submodule add ./sub &&

@@ -54,117 +54,117 @@ test_expect_success 'grep and nested submodules' '
 	git commit -m "updated submodule" &&
 
 	cat >expect <<-\EOF &&
-	a:foobar
-	b/b:bar
-	submodule/a:foobar
-	submodule/sub/a:foobar
+	a:(1|2)d(3|4)
+	b/b:(3|4)
+	submodule/a:(1|2)d(3|4)
+	submodule/sub/a:(1|2)d(3|4)
 	EOF
 
-	git grep -e "bar" --recurse-submodules >actual &&
+	git grep -e "(3|4)" --recurse-submodules >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep and multiple patterns' '
 	cat >expect <<-\EOF &&
-	a:foobar
-	submodule/a:foobar
-	submodule/sub/a:foobar
+	a:(1|2)d(3|4)
+	submodule/a:(1|2)d(3|4)
+	submodule/sub/a:(1|2)d(3|4)
 	EOF
 
-	git grep -e "bar" --and -e "foo" --recurse-submodules >actual &&
+	git grep -e "(3|4)" --and -e "(1|2)" --recurse-submodules >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep and multiple patterns' '
 	cat >expect <<-\EOF &&
-	b/b:bar
+	b/b:(3|4)
 	EOF
 
-	git grep -e "bar" --and --not -e "foo" --recurse-submodules >actual &&
+	git grep -e "(3|4)" --and --not -e "(1|2)" --recurse-submodules >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'basic grep tree' '
 	cat >expect <<-\EOF &&
-	HEAD:a:foobar
-	HEAD:b/b:bar
-	HEAD:submodule/a:foobar
-	HEAD:submodule/sub/a:foobar
+	HEAD:a:(1|2)d(3|4)
+	HEAD:b/b:(3|4)
+	HEAD:submodule/a:(1|2)d(3|4)
+	HEAD:submodule/sub/a:(1|2)d(3|4)
 	EOF
 
-	git grep -e "bar" --recurse-submodules HEAD >actual &&
+	git grep -e "(3|4)" --recurse-submodules HEAD >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep tree HEAD^' '
 	cat >expect <<-\EOF &&
-	HEAD^:a:foobar
-	HEAD^:b/b:bar
-	HEAD^:submodule/a:foobar
+	HEAD^:a:(1|2)d(3|4)
+	HEAD^:b/b:(3|4)
+	HEAD^:submodule/a:(1|2)d(3|4)
 	EOF
 
-	git grep -e "bar" --recurse-submodules HEAD^ >actual &&
+	git grep -e "(3|4)" --recurse-submodules HEAD^ >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep tree HEAD^^' '
 	cat >expect <<-\EOF &&
-	HEAD^^:a:foobar
-	HEAD^^:b/b:bar
+	HEAD^^:a:(1|2)d(3|4)
+	HEAD^^:b/b:(3|4)
 	EOF
 
-	git grep -e "bar" --recurse-submodules HEAD^^ >actual &&
+	git grep -e "(3|4)" --recurse-submodules HEAD^^ >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep tree and pathspecs' '
 	cat >expect <<-\EOF &&
-	HEAD:submodule/a:foobar
-	HEAD:submodule/sub/a:foobar
+	HEAD:submodule/a:(1|2)d(3|4)
+	HEAD:submodule/sub/a:(1|2)d(3|4)
 	EOF
 
-	git grep -e "bar" --recurse-submodules HEAD -- submodule >actual &&
+	git grep -e "(3|4)" --recurse-submodules HEAD -- submodule >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep tree and pathspecs' '
 	cat >expect <<-\EOF &&
-	HEAD:submodule/a:foobar
-	HEAD:submodule/sub/a:foobar
+	HEAD:submodule/a:(1|2)d(3|4)
+	HEAD:submodule/sub/a:(1|2)d(3|4)
 	EOF
 
-	git grep -e "bar" --recurse-submodules HEAD -- "submodule*a" >actual &&
+	git grep -e "(3|4)" --recurse-submodules HEAD -- "submodule*a" >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep tree and more pathspecs' '
 	cat >expect <<-\EOF &&
-	HEAD:submodule/a:foobar
+	HEAD:submodule/a:(1|2)d(3|4)
 	EOF
 
-	git grep -e "bar" --recurse-submodules HEAD -- "submodul?/a" >actual &&
+	git grep -e "(3|4)" --recurse-submodules HEAD -- "submodul?/a" >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep tree and more pathspecs' '
 	cat >expect <<-\EOF &&
-	HEAD:submodule/sub/a:foobar
+	HEAD:submodule/sub/a:(1|2)d(3|4)
 	EOF
 
-	git grep -e "bar" --recurse-submodules HEAD -- "submodul*/sub/a" >actual &&
+	git grep -e "(3|4)" --recurse-submodules HEAD -- "submodul*/sub/a" >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success !MINGW 'grep recurse submodule colon in name' '
 	git init parent &&
 	test_when_finished "rm -rf parent" &&
-	echo "foobar" >"parent/fi:le" &&
+	echo "(1|2)d(3|4)" >"parent/fi:le" &&
 	git -C parent add "fi:le" &&
 	git -C parent commit -m "add fi:le" &&
 
 	git init "su:b" &&
 	test_when_finished "rm -rf su:b" &&
-	echo "foobar" >"su:b/fi:le" &&
+	echo "(1|2)d(3|4)" >"su:b/fi:le" &&
 	git -C "su:b" add "fi:le" &&
 	git -C "su:b" commit -m "add fi:le" &&
 

@@ -172,30 +172,30 @@ test_expect_success !MINGW 'grep recurse submodule colon in name' '
 	git -C parent commit -m "add submodule" &&
 
 	cat >expect <<-\EOF &&
-	fi:le:foobar
-	su:b/fi:le:foobar
+	fi:le:(1|2)d(3|4)
+	su:b/fi:le:(1|2)d(3|4)
 	EOF
-	git -C parent grep -e "foobar" --recurse-submodules >actual &&
+	git -C parent grep -e "(1|2)d(3|4)" --recurse-submodules >actual &&
 	test_cmp expect actual &&
 
 	cat >expect <<-\EOF &&
-	HEAD:fi:le:foobar
-	HEAD:su:b/fi:le:foobar
+	HEAD:fi:le:(1|2)d(3|4)
+	HEAD:su:b/fi:le:(1|2)d(3|4)
 	EOF
-	git -C parent grep -e "foobar" --recurse-submodules HEAD >actual &&
+	git -C parent grep -e "(1|2)d(3|4)" --recurse-submodules HEAD >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep history with moved submoules' '
 	git init parent &&
 	test_when_finished "rm -rf parent" &&
-	echo "foobar" >parent/file &&
+	echo "(1|2)d(3|4)" >parent/file &&
 	git -C parent add file &&
 	git -C parent commit -m "add file" &&
 
 	git init sub &&
 	test_when_finished "rm -rf sub" &&
-	echo "foobar" >sub/file &&
+	echo "(1|2)d(3|4)" >sub/file &&
 	git -C sub add file &&
 	git -C sub commit -m "add file" &&
 

@@ -203,82 +203,82 @@ test_expect_success 'grep history with moved submoules' '
 	git -C parent commit -m "add submodule" &&
 
 	cat >expect <<-\EOF &&
-	dir/sub/file:foobar
-	file:foobar
+	dir/sub/file:(1|2)d(3|4)
+	file:(1|2)d(3|4)
 	EOF
-	git -C parent grep -e "foobar" --recurse-submodules >actual &&
+	git -C parent grep -e "(1|2)d(3|4)" --recurse-submodules >actual &&
 	test_cmp expect actual &&
 
 	git -C parent mv dir/sub sub-moved &&
 	git -C parent commit -m "moved submodule" &&
 
 	cat >expect <<-\EOF &&
-	file:foobar
-	sub-moved/file:foobar
+	file:(1|2)d(3|4)
+	sub-moved/file:(1|2)d(3|4)
 	EOF
-	git -C parent grep -e "foobar" --recurse-submodules >actual &&
+	git -C parent grep -e "(1|2)d(3|4)" --recurse-submodules >actual &&
 	test_cmp expect actual &&
 
 	cat >expect <<-\EOF &&
-	HEAD^:dir/sub/file:foobar
-	HEAD^:file:foobar
+	HEAD^:dir/sub/file:(1|2)d(3|4)
+	HEAD^:file:(1|2)d(3|4)
 	EOF
-	git -C parent grep -e "foobar" --recurse-submodules HEAD^ >actual &&
+	git -C parent grep -e "(1|2)d(3|4)" --recurse-submodules HEAD^ >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep using relative path' '
 	test_when_finished "rm -rf parent sub" &&
 	git init sub &&
-	echo "foobar" >sub/file &&
+	echo "(1|2)d(3|4)" >sub/file &&
 	git -C sub add file &&
 	git -C sub commit -m "add file" &&
 
 	git init parent &&
-	echo "foobar" >parent/file &&
+	echo "(1|2)d(3|4)" >parent/file &&
 	git -C parent add file &&
 	mkdir parent/src &&
-	echo "foobar" >parent/src/file2 &&
+	echo "(1|2)d(3|4)" >parent/src/file2 &&
 	git -C parent add src/file2 &&
 	git -C parent submodule add ../sub &&
 	git -C parent commit -m "add files and submodule" &&
 
 	# From top works
 	cat >expect <<-\EOF &&
-	file:foobar
-	src/file2:foobar
-	sub/file:foobar
+	file:(1|2)d(3|4)
+	src/file2:(1|2)d(3|4)
+	sub/file:(1|2)d(3|4)
 	EOF
-	git -C parent grep --recurse-submodules -e "foobar" >actual &&
+	git -C parent grep --recurse-submodules -e "(1|2)d(3|4)" >actual &&
 	test_cmp expect actual &&
 
 	# Relative path to top
 	cat >expect <<-\EOF &&
-	../file:foobar
-	file2:foobar
-	../sub/file:foobar
+	../file:(1|2)d(3|4)
+	file2:(1|2)d(3|4)
+	../sub/file:(1|2)d(3|4)
 	EOF
-	git -C parent/src grep --recurse-submodules -e "foobar" -- .. >actual &&
+	git -C parent/src grep --recurse-submodules -e "(1|2)d(3|4)" -- .. >actual &&
 	test_cmp expect actual &&
 
 	# Relative path to submodule
 	cat >expect <<-\EOF &&
-	../sub/file:foobar
+	../sub/file:(1|2)d(3|4)
 	EOF
-	git -C parent/src grep --recurse-submodules -e "foobar" -- ../sub >actual &&
+	git -C parent/src grep --recurse-submodules -e "(1|2)d(3|4)" -- ../sub >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep from a subdir' '
 	test_when_finished "rm -rf parent sub" &&
 	git init sub &&
-	echo "foobar" >sub/file &&
+	echo "(1|2)d(3|4)" >sub/file &&
 	git -C sub add file &&
 	git -C sub commit -m "add file" &&
 
 	git init parent &&
 	mkdir parent/src &&
-	echo "foobar" >parent/src/file &&
+	echo "(1|2)d(3|4)" >parent/src/file &&
 	git -C parent add src/file &&
 	git -C parent submodule add ../sub src/sub &&
 	git -C parent submodule add ../sub sub &&

@@ -286,19 +286,19 @@ test_expect_success 'grep from a subdir' '
 
 	# Verify grep from root works
 	cat >expect <<-\EOF &&
-	src/file:foobar
-	src/sub/file:foobar
-	sub/file:foobar
+	src/file:(1|2)d(3|4)
+	src/sub/file:(1|2)d(3|4)
+	sub/file:(1|2)d(3|4)
 	EOF
-	git -C parent grep --recurse-submodules -e "foobar" >actual &&
+	git -C parent grep --recurse-submodules -e "(1|2)d(3|4)" >actual &&
 	test_cmp expect actual &&
 
 	# Verify grep from a subdir works
 	cat >expect <<-\EOF &&
-	file:foobar
-	sub/file:foobar
+	file:(1|2)d(3|4)
+	sub/file:(1|2)d(3|4)
 	EOF
-	git -C parent/src grep --recurse-submodules -e "foobar" >actual &&
+	git -C parent/src grep --recurse-submodules -e "(1|2)d(3|4)" >actual &&
 	test_cmp expect actual
 '
 

2.13.0.303.g4ebf302169

Add testing for grep pattern types being correctly passed to submodules. The pattern "(.|.)[\d]" matches differently under fixed (not at all), and then matches different lines under basic/extended & perl regular expressions, so this change asserts that the pattern type is passed along correctly.

---
 t/t7814-grep-recurse-submodules.sh | 49 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

index 1472855e1d..3a58197f47 100755
@@ -313,4 +313,53 @@ test_incompatible_with_recurse_submodules ()
 test_incompatible_with_recurse_submodules --untracked
 test_incompatible_with_recurse_submodules --no-index
 
+test_expect_success 'grep --recurse-submodules should pass the pattern type along' '
+	# Fixed
+	test_must_fail git grep -F --recurse-submodules -e "(.|.)[\d]" &&
+	test_must_fail git -c grep.patternType=fixed grep --recurse-submodules -e "(.|.)[\d]" &&
+
+	# Basic
+	git grep -G --recurse-submodules -e "(.|.)[\d]" >actual &&
+	cat >expect <<-\EOF &&
+	a:(1|2)d(3|4)
+	submodule/a:(1|2)d(3|4)
+	submodule/sub/a:(1|2)d(3|4)
+	EOF
+	test_cmp expect actual &&
+	git -c grep.patternType=basic grep --recurse-submodules -e "(.|.)[\d]" >actual &&
+	test_cmp expect actual &&
+
+	# Extended
+	git grep -E --recurse-submodules -e "(.|.)[\d]" >actual &&
+	cat >expect <<-\EOF &&
+	.gitmodules:[submodule "submodule"]
+	.gitmodules:	path = submodule
+	.gitmodules:	url = ./submodule
+	a:(1|2)d(3|4)
+	submodule/.gitmodules:[submodule "sub"]
+	submodule/a:(1|2)d(3|4)
+	submodule/sub/a:(1|2)d(3|4)
+	EOF
+	test_cmp expect actual &&
+	git -c grep.patternType=extended grep --recurse-submodules -e "(.|.)[\d]" >actual &&
+	test_cmp expect actual &&
+	git -c grep.extendedRegexp=true grep --recurse-submodules -e "(.|.)[\d]" >actual &&
+	test_cmp expect actual &&
+
+	# Perl
+	if test_have_prereq PCRE
+	then
+		git grep -P --recurse-submodules -e "(.|.)[\d]" >actual &&
+		cat >expect <<-\EOF &&
+		a:(1|2)d(3|4)
+		b/b:(3|4)
+		submodule/a:(1|2)d(3|4)
+		submodule/sub/a:(1|2)d(3|4)
+		EOF
+		test_cmp expect actual &&
+		git -c grep.patternType=perl grep --recurse-submodules -e "(.|.)[\d]" >actual &&
+		test_cmp expect actual
+	fi
+'
+
 test_done

2.13.0.303.g4ebf302169

Add a helper function to make the tests which check for patterns with \0 in them more succinct. Right now this isn't a big win, but subsequent commits will add a lot more of these tests.

The helper is based on the match() function in t3070-wildmatch.sh.

---
 t/t7008-grep-binary.sh | 58 +++++++++++++++++++++++++-------------------------
 1 file changed, 29 insertions(+), 29 deletions(-)

index 9c9c378119..df93d8e44c 100755
@@ -4,6 +4,29 @@ test_description='git grep in binary files'
 
 . ./test-lib.sh
 
+nul_match () {
+	matches=$1
+	flags=$2
+	pattern=$3
+	pattern_human=$(echo "$pattern" | sed 's/Q/<NUL>/g')
+
+	if test "$matches" = 1
+	then
+		test_expect_success "git grep -f f $flags '$pattern_human' a" "
+			printf '$pattern' | q_to_nul >f &&
+			git grep -f f $flags a
+		"
+	elif test "$matches" = 0
+	then
+		test_expect_success "git grep -f f $flags '$pattern_human' a" "
+			printf '$pattern' | q_to_nul >f &&
+			test_must_fail git grep -f f $flags a
+		"
+	else
+		test_expect_success "PANIC: Test framework error. Unknown matches value $matches" 'false'
+	fi
+}
+
 test_expect_success 'setup' "
 	echo 'binaryQfile' | q_to_nul >a &&
 	git add a &&

@@ -69,35 +92,12 @@ test_expect_failure 'git grep .fi a' '
 	git grep .fi a
 '
 
-test_expect_success 'git grep -F y<NUL>f a' "
-	printf 'yQf' | q_to_nul >f &&
-	git grep -f f -F a
-"
-
-test_expect_success 'git grep -F y<NUL>x a' "
-	printf 'yQx' | q_to_nul >f &&
-	test_must_fail git grep -f f -F a
-"
-
-test_expect_success 'git grep -Fi Y<NUL>f a' "
-	printf 'YQf' | q_to_nul >f &&
-	git grep -f f -Fi a
-"
-
-test_expect_success 'git grep -Fi Y<NUL>x a' "
-	printf 'YQx' | q_to_nul >f &&
-	test_must_fail git grep -f f -Fi a
-"
-
-test_expect_success 'git grep y<NUL>f a' "
-	printf 'yQf' | q_to_nul >f &&
-	git grep -f f a
-"
-
-test_expect_success 'git grep y<NUL>x a' "
-	printf 'yQx' | q_to_nul >f &&
-	test_must_fail git grep -f f a
-"
+nul_match 1 '-F' 'yQf'
+nul_match 0 '-F' 'yQx'
+nul_match 1 '-Fi' 'YQf'
+nul_match 0 '-Fi' 'YQx'
+nul_match 1 '' 'yQf'
+nul_match 0 '' 'yQx'
 
 test_expect_success 'grep respects binary diff attribute' '
 	echo text >t &&

2.13.0.303.g4ebf302169

Add setup code needed for testing regexes that contain both binary data and regex metacharacters.

The POSIX regcomp() function inherently can't support that, because it takes a \0-delimited char *, but other regex engines APIs like PCRE v2 take a pattern/length pair, and are thus able to handle \0s in patterns as well as any other character.

When kwset was imported in commit 9eceddeec6 ("Use kwset in grep", 2011-08-21) this limitation was fixed, but at the expense of introducing the undocumented limitation that any pattern containing \0 implicitly becomes a fixed match (equivalent to -F having been provided).

That's not something we'd like to keep in the future. The inability to match patterns containing \0 is a leaky implementation detail.

So add tests as a first step towards changing that. In order to test that \0-patterns can properly match as regexes the test string needs to have some regex metacharacters in it.

There were other blind spots in the tests. The code around kwset specially handles case-insensitive & non-ASCII data, but there were no tests for this.

Fix all of that by amending the text being matched to contain both regex metacharacters & non-ASCII data.

---
 t/t7008-grep-binary.sh | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

index df93d8e44c..20370d6e0c 100755
@@ -28,7 +28,7 @@ nul_match () {
 }
 
 test_expect_success 'setup' "
-	echo 'binaryQfile' | q_to_nul >a &&
+	echo 'binaryQfileQm[*]cQ*æQð' | q_to_nul >a &&
 	git add a &&
 	git commit -m.
 "

@@ -162,7 +162,7 @@ test_expect_success 'grep does not honor textconv' '
 '
 
 test_expect_success 'grep --textconv honors textconv' '
-	echo "a:binaryQfile" >expect &&
+	echo "a:binaryQfileQm[*]cQ*æQð" >expect &&
 	git grep --textconv Qfile >actual &&
 	test_cmp expect actual
 '

@@ -172,7 +172,7 @@ test_expect_success 'grep --no-textconv does not honor textconv' '
 '
 
 test_expect_success 'grep --textconv blob honors textconv' '
-	echo "HEAD:a:binaryQfile" >expect &&
+	echo "HEAD:a:binaryQfileQm[*]cQ*æQð" >expect &&
 	git grep --textconv Qfile HEAD:a >actual &&
 	test_cmp expect actual
 '

2.13.0.303.g4ebf302169

Address a big blind spot in the tests for patterns containing \0. The is_fixed() function considers any string that contains \0 fixed, even if it contains regular expression metacharacters, those patterns are currently matched with kwset.

Before this change removing that memchr(s, 0, len) check from is_fixed() wouldn't change the result of any of the tests, since regcomp() will happily match the part before the \0.

The kwset path is dependent on whether the the -i flag is on, and whether the pattern has any non-ASCII characters, but none of this was tested for.

---
 t/t7008-grep-binary.sh | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)

index 20370d6e0c..615e7e0162 100755
@@ -22,6 +22,18 @@ nul_match () {
 			printf '$pattern' | q_to_nul >f &&
 			test_must_fail git grep -f f $flags a
 		"
+	elif test "$matches" = T1
+	then
+		test_expect_failure "git grep -f f $flags '$pattern_human' a" "
+			printf '$pattern' | q_to_nul >f &&
+			git grep -f f $flags a
+		"
+	elif test "$matches" = T0
+	then
+		test_expect_failure "git grep -f f $flags '$pattern_human' a" "
+			printf '$pattern' | q_to_nul >f &&
+			test_must_fail git grep -f f $flags a
+		"
 	else
 		test_expect_success "PANIC: Test framework error. Unknown matches value $matches" 'false'
 	fi

@@ -98,6 +110,65 @@ nul_match 1 '-Fi' 'YQf'
 nul_match 0 '-Fi' 'YQx'
 nul_match 1 '' 'yQf'
 nul_match 0 '' 'yQx'
+nul_match 1 '' 'æQð'
+nul_match 1 '-F' 'eQm[*]c'
+nul_match 1 '-Fi' 'EQM[*]C'
+
+# Regex patterns that would match but shouldn't with -F
+nul_match 0 '-F' 'yQ[f]'
+nul_match 0 '-F' '[y]Qf'
+nul_match 0 '-Fi' 'YQ[F]'
+nul_match 0 '-Fi' '[Y]QF'
+nul_match 0 '-F' 'æQ[ð]'
+nul_match 0 '-F' '[æ]Qð'
+nul_match 0 '-Fi' 'ÆQ[Ð]'
+nul_match 0 '-Fi' '[Æ]QÐ'
+
+# kwset is disabled on -i & non-ASCII. No way to match non-ASCII \0
+# patterns case-insensitively.
+nul_match T1 '-i' 'ÆQÐ'
+
+# \0 implicitly disables regexes. This is an undocumented internal
+# limitation.
+nul_match T1 '' 'yQ[f]'
+nul_match T1 '' '[y]Qf'
+nul_match T1 '-i' 'YQ[F]'
+nul_match T1 '-i' '[Y]Qf'
+nul_match T1 '' 'æQ[ð]'
+nul_match T1 '' '[æ]Qð'
+nul_match T1 '-i' 'ÆQ[Ð]'
+
+# ... because of \0 implicitly disabling regexes regexes that
+# should/shouldn't match don't do the right thing.
+nul_match T1 '' 'eQm.*cQ'
+nul_match T1 '-i' 'EQM.*cQ'
+nul_match T0 '' 'eQm[*]c'
+nul_match T0 '-i' 'EQM[*]C'
+
+# Due to the REG_STARTEND extension when kwset() is disabled on -i &
+# non-ASCII the string will be matched in its entirety, but the
+# pattern will be cut off at the first \0.
+nul_match 0 '-i' 'NOMATCHQð'
+nul_match T0 '-i' '[Æ]QNOMATCH'
+nul_match T0 '-i' '[æ]QNOMATCH'
+# Matches, but for the wrong reasons, just stops at [æ]
+nul_match 1 '-i' '[Æ]Qð'
+nul_match 1 '-i' '[æ]Qð'
+
+# Ensure that the matcher doesn't regress to something that stops at
+# \0
+nul_match 0 '-F' 'yQ[f]'
+nul_match 0 '-Fi' 'YQ[F]'
+nul_match 0 '' 'yQNOMATCH'
+nul_match 0 '' 'QNOMATCH'
+nul_match 0 '-i' 'YQNOMATCH'
+nul_match 0 '-i' 'QNOMATCH'
+nul_match 0 '-F' 'æQ[ð]'
+nul_match 0 '-Fi' 'ÆQ[Ð]'
+nul_match 0 '' 'yQNÓMATCH'
+nul_match 0 '' 'QNÓMATCH'
+nul_match 0 '-i' 'YQNÓMATCH'
+nul_match 0 '-i' 'QNÓMATCH'
 
 test_expect_success 'grep respects binary diff attribute' '
 	echo text >t &&

2.13.0.303.g4ebf302169

Add a git GIT_PERF_MAKE_COMMAND variable to compliment the existing GIT_PERF_MAKE_OPTS facility. This allows specifying an arbitrary shell command to execute instead of 'make'.

This is useful e.g. in cases where the name, semantics or defaults of a Makefile flag have changed over time. It can even be used to change the contents of the tree, useful for monkeypatching ancient versions of git to get them to build.

This opens Pandora's box in some ways, it's now possible to "jailbreak" the perf environment and e.g. modify the source tree via this arbitrary instead of just issuing a custom "make" command, such a command has to be re-entrant in the sense that subsequent perf runs will re-use the possibly modified tree.

It would be pointless to try to mitigate or work around that caveat in a tool purely aimed at Git developers, so this change makes no attempt to do so.

---
 Makefile      |  3 +++
 t/perf/README | 19 +++++++++++++++++--
 t/perf/run    | 11 +++++++++--
 3 files changed, 29 insertions(+), 4 deletions(-)

index eedadb8056..d1587452f1 100644
@@ -2272,6 +2272,9 @@ endif
 ifdef GIT_PERF_MAKE_OPTS
 	@echo GIT_PERF_MAKE_OPTS=\''$(subst ','\'',$(subst ','\'',$(GIT_PERF_MAKE_OPTS)))'\' >>$@+
 endif
+ifdef GIT_PERF_MAKE_COMMAND
+	@echo GIT_PERF_MAKE_COMMAND=\''$(subst ','\'',$(subst ','\'',$(GIT_PERF_MAKE_COMMAND)))'\' >>$@+
+endif
 ifdef GIT_INTEROP_MAKE_OPTS
 	@echo GIT_INTEROP_MAKE_OPTS=\''$(subst ','\'',$(subst ','\'',$(GIT_INTEROP_MAKE_OPTS)))'\' >>$@+
 endif

index 49ea4349be..b3d95042a8 100644
@@ -60,8 +60,23 @@ You can set the following variables (also in your config.mak):
 
     GIT_PERF_MAKE_OPTS
 	Options to use when automatically building a git tree for
-	performance testing.  E.g., -j6 would be useful.
-
+	performance testing. E.g., -j6 would be useful. Passed
+	directly to make as "make $GIT_PERF_MAKE_OPTS".
+
+    GIT_PERF_MAKE_COMMAND
+	An arbitrary command that'll be run in place of the make
+	command, if set the GIT_PERF_MAKE_OPTS variable is
+	ignored. Useful in cases where source tree changes might
+	require issuing a different make command to different
+	revisions.
+
+	This can be (ab)used to monkeypatch or otherwise change the
+	tree about to be built. Note that the build directory can be
+	re-used for subsequent runs so the make command might get
+	executed multiple times on the same tree, but don't count on
+	any of that, that's an implementation detail that might change
+	in the future.
+ 
     GIT_PERF_REPO
     GIT_PERF_LARGE_REPO
 	Repositories to copy for the performance tests.  The normal

index c788d713ae..b61024a830 100755
@@ -37,8 +37,15 @@ build_git_rev () {
 			cp "../../$config" "build/$rev/"
 		fi
 	done
-	(cd build/$rev && make $GIT_PERF_MAKE_OPTS) ||
-	die "failed to build revision '$mydir'"
+	(
+		cd build/$rev &&
+		if test -n "$GIT_PERF_MAKE_COMMAND"
+		then
+			sh -c "$GIT_PERF_MAKE_COMMAND"
+		else
+			make $GIT_PERF_MAKE_OPTS
+		fi
+	) || die "failed to build revision '$mydir'"
 }
 
 run_dirs_helper () {

2.13.0.303.g4ebf302169

Thanks, forgot about diff --check on the whole series with all the other checks I was doing.

Amend the t/perf/run output so that in addition to the "Running N tests" heading currently being emitted, it also emits "Unpacking $rev" and "Building $rev" when setting up the build/$rev directory & when building it, respectively.

This makes it easier to see what's going on and what revision is being tested as the output scrolls by.

---
 t/perf/run | 2 ++
 1 file changed, 2 insertions(+)

index b61024a830..beb4acc0e4 100755
@@ -24,6 +24,7 @@ run_one_dir () {
 
 unpack_git_rev () {
 	rev=$1
+	echo "=== Unpacking $rev in build/$rev ==="
 	mkdir -p build/$rev
 	(cd "$(git rev-parse --show-cdup)" && git archive --format=tar $rev) |
 	(cd build/$rev && tar x)

@@ -37,6 +38,7 @@ build_git_rev () {
 			cp "../../$config" "build/$rev/"
 		fi
 	done
+	echo "=== Building $rev ==="
 	(
 		cd build/$rev &&
 		if test -n "$GIT_PERF_MAKE_COMMAND"

2.13.0.303.g4ebf302169

Add a very basic performance comparison test comparing the POSIX basic, extended and perl engines.

In theory the "basic" and "extended" engines should be implemented using the same underlying code with a slightly different pattern parser, but some implementations may not do this. Jump through some slight hoops to test both, which is worthwhile since "basic" is the default.

Running this on an i7 3.4GHz Linux 4.9.0-2 Debian testing against a checkout of linux.git & latest upstream PCRE, both PCRE and git compiled with -O3 using gcc 7.1.1:

    $ GIT_PERF_REPEAT_COUNT=10 GIT_PERF_LARGE_REPO=~/g/linux ./run p7820-grep-engines.sh
    [...]
    Test                                            this tree
    ---------------------------------------------------------------
    7820.1: basic grep 'how.to'                     0.34(1.24+0.53)
    7820.2: extended grep 'how.to'                  0.33(1.23+0.45)
    7820.3: perl grep 'how.to'                      0.31(1.05+0.56)
    7820.5: basic grep '^how to'                    0.32(1.24+0.42)
    7820.6: extended grep '^how to'                 0.33(1.20+0.44)
    7820.7: perl grep '^how to'                     0.57(2.67+0.42)
    7820.9: basic grep '[how] to'                   0.51(2.16+0.45)
    7820.10: extended grep '[how] to'               0.49(2.20+0.43)
    7820.11: perl grep '[how] to'                   0.56(2.60+0.43)
    7820.13: basic grep '\(e.t[^ ]*\|v.ry\) rare'   0.66(3.25+0.40)
    7820.14: extended grep '(e.t[^ ]*|v.ry) rare'   0.65(3.19+0.46)
    7820.15: perl grep '(e.t[^ ]*|v.ry) rare'       1.05(5.74+0.34)
    7820.17: basic grep 'm\(ú\|u\)lt.b\(æ\|y\)te'   0.34(1.28+0.47)
    7820.18: extended grep 'm(ú|u)lt.b(æ|y)te'      0.34(1.38+0.38)
    7820.19: perl grep 'm(ú|u)lt.b(æ|y)te'          0.39(1.56+0.44)

Options can also be passed to git-grep via the GIT_PERF_7820_GREP_OPTS environment variable. There are various modes such as "-v" that have very different performance profiles, but handling the combinatorial explosion of testing all those options would make this script much more complex and harder to maintain. Instead just add the ability to do one-shot runs with arbitrary options, e.g.:

    $ GIT_PERF_REPEAT_COUNT=10 GIT_PERF_LARGE_REPO=~/g/linux GIT_PERF_7820_GREP_OPTS=" -i" ./run p7820-grep-engines.sh
    [...]
    Test                                               this tree
    ------------------------------------------------------------------
    7820.1: basic grep -i 'how.to'                     0.49(1.72+0.38)
    7820.2: extended grep -i 'how.to'                  0.46(1.64+0.42)
    7820.3: perl grep -i 'how.to'                      0.44(1.45+0.45)
    7820.5: basic grep -i '^how to'                    0.47(1.76+0.38)
    7820.6: extended grep -i '^how to'                 0.47(1.70+0.42)
    7820.7: perl grep -i '^how to'                     0.65(2.72+0.37)
    7820.9: basic grep -i '[how] to'                   0.86(3.64+0.42)
    7820.10: extended grep -i '[how] to'               0.84(3.62+0.46)
    7820.11: perl grep -i '[how] to'                   0.73(3.06+0.39)
    7820.13: basic grep -i '\(e.t[^ ]*\|v.ry\) rare'   1.63(8.13+0.36)
    7820.14: extended grep -i '(e.t[^ ]*|v.ry) rare'   1.64(8.01+0.44)
    7820.15: perl grep -i '(e.t[^ ]*|v.ry) rare'       1.44(6.88+0.44)
    7820.17: basic grep -i 'm\(ú\|u\)lt.b\(æ\|y\)te'   0.66(2.67+0.44)
    7820.18: extended grep -i 'm(ú|u)lt.b(æ|y)te'      0.66(2.67+0.43)
    7820.19: perl grep -i 'm(ú|u)lt.b(æ|y)te'          0.59(2.31+0.37)

---
 t/perf/p7820-grep-engines.sh | 47 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100755 t/perf/p7820-grep-engines.sh

new file mode 100755
index 0000000000..a3a1b9fa28
@@ -0,0 +1,47 @@
+#!/bin/sh
+
+test_description="Comparison of git-grep's regex engines
+
+Set GIT_PERF_7820_GREP_OPTS in the environment to pass options to
+git-grep. Make sure to include a leading space,
+e.g. GIT_PERF_7820_GREP_OPTS=' -i'. Some options to try:
+
+	-i
+	-w
+	-v
+	-vi
+	-vw
+	-viw
+"
+
+. ./perf-lib.sh
+
+test_perf_large_repo
+test_checkout_worktree
+
+for pattern in \
+	'how.to' \
+	'^how to' \
+	'[how] to' \
+	'\(e.t[^ ]*\|v.ry\) rare' \
+	'm\(ú\|u\)lt.b\(æ\|y\)te'
+do
+	for engine in basic extended perl
+	do
+		if test $engine != "basic"
+		then
+			# Poor man's basic -> extended converter.
+			pattern=$(echo "$pattern" | sed 's/\\//g')
+		fi
+		test_perf "$engine grep$GIT_PERF_7820_GREP_OPTS '$pattern'" "
+			git -c grep.patternType=$engine grep$GIT_PERF_7820_GREP_OPTS -- '$pattern' >'out.$engine' || :
+		"
+	done
+
+	test_expect_success "assert that all engines found the same for$GIT_PERF_7820_GREP_OPTS '$pattern'" "
+		test_cmp 'out.basic' 'out.extended' &&
+		test_cmp 'out.basic' 'out.perl'
+	"
+done
+
+test_done

2.13.0.303.g4ebf302169

Add a performance comparison test which compares both case-sensitive & case-insensitive fixed-string grep, as well as non-ASCII case-sensitive & case-insensitive grep.

    $ GIT_PERF_REPEAT_COUNT=10 GIT_PERF_LARGE_REPO=~/g/linux ./run p7821-grep-engines-fixed.sh
    [...]
    Test                             this tree
    ------------------------------------------------
    7821.1: fixed grep int           0.61(1.72+0.65)
    7821.2: basic grep int           0.69(1.72+0.53)
    7821.3: extended grep int        0.60(1.72+0.54)
    7821.4: perl grep int            0.65(1.65+0.64)
    7821.6: fixed grep uncommon      0.25(0.53+0.48)
    7821.7: basic grep uncommon      0.26(0.57+0.46)
    7821.8: extended grep uncommon   0.25(0.52+0.51)
    7821.9: perl grep uncommon       0.26(0.56+0.48)
    7821.11: fixed grep æ            0.40(1.26+0.44)
    7821.12: basic grep æ            0.40(1.28+0.43)
    7821.13: extended grep æ         0.39(1.28+0.44)
    7821.14: perl grep æ             0.39(1.29+0.44)

This test needs to be run with GIT_PERF_7821_GREP_OPTS=' -i' to avoid going through the same kwset.[ch] codepath, see the "Even when -F..." comment in grep.c:

    $ GIT_PERF_REPEAT_COUNT=10 GIT_PERF_LARGE_REPO=~/g/linux GIT_PERF_7821_GREP_OPTS=' -i' ./run p7821-grep-engines-fixed.sh
    [...]
    Test                                this tree
    ---------------------------------------------------
    7821.1: fixed grep -i int           1.55(1.86+0.66)
    7821.2: basic grep -i int           0.66(1.97+0.54)
    7821.3: extended grep -i int        0.72(1.88+0.62)
    7821.4: perl grep -i int            0.75(1.93+0.57)
    7821.6: fixed grep -i uncommon      0.27(0.52+0.54)
    7821.7: basic grep -i uncommon      0.25(0.58+0.44)
    7821.8: extended grep -i uncommon   0.26(0.62+0.43)
    7821.9: perl grep -i uncommon       0.26(0.55+0.53)
    7821.11: fixed grep -i æ            0.32(0.87+0.46)
    7821.12: basic grep -i æ            0.30(0.90+0.41)
    7821.13: extended grep -i æ         0.32(0.92+0.41)
    7821.14: perl grep -i æ             0.29(0.71+0.53)

I'm planning to make that not be the case, this performance test gives a baseline for comparing performance before & after any such change.

See commit ("perf: add a comparison test of grep regex engines", 2017-04-19) for details on the machine the above test run was executed on.

---
 t/perf/p7821-grep-engines-fixed.sh | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100755 t/perf/p7821-grep-engines-fixed.sh

new file mode 100755
index 0000000000..d935194ecf
@@ -0,0 +1,32 @@
+#!/bin/sh
+
+test_description="Comparison of git-grep's regex engines with -F
+
+Set GIT_PERF_7821_GREP_OPTS in the environment to pass options to
+git-grep. Make sure to include a leading space,
+e.g. GIT_PERF_7821_GREP_OPTS=' -w'. See p7820-grep-engines.sh for more
+options to try.
+"
+
+. ./perf-lib.sh
+
+test_perf_large_repo
+test_checkout_worktree
+
+for args in 'int' 'uncommon' 'æ'
+do
+	for engine in fixed basic extended perl
+	do
+		test_perf "$engine grep$GIT_PERF_7821_GREP_OPTS $args" "
+			git -c grep.patternType=$engine grep$GIT_PERF_7821_GREP_OPTS $args >'out.$engine.$args' || :
+		"
+	done
+
+	test_expect_success "assert that all engines found the same for$GIT_PERF_7821_GREP_OPTS $args" "
+		test_cmp 'out.fixed.$args' 'out.basic.$args' &&
+		test_cmp 'out.fixed.$args' 'out.extended.$args' &&
+		test_cmp 'out.fixed.$args' 'out.perl.$args'
+	"
+done
+
+test_done

2.13.0.303.g4ebf302169

Add a very basic performance comparison test comparing the POSIX basic, extended and perl engines with patterns matching log messages via --grep=<pattern>.

    $ GIT_PERF_REPEAT_COUNT=10 GIT_PERF_LARGE_REPO=~/g/linux ./run p4220-log-grep-engines.sh
    [...]
    Test                                                  this tree
    ---------------------------------------------------------------------
    4220.1: basic log --grep='how.to'                     6.22(6.00+0.21)
    4220.2: extended log --grep='how.to'                  6.23(5.98+0.23)
    4220.3: perl log --grep='how.to'                      6.07(5.79+0.25)
    4220.5: basic log --grep='^how to'                    6.19(5.93+0.22)
    4220.6: extended log --grep='^how to'                 6.19(5.93+0.23)
    4220.7: perl log --grep='^how to'                     6.14(5.88+0.24)
    4220.9: basic log --grep='[how] to'                   6.96(6.65+0.28)
    4220.10: extended log --grep='[how] to'               6.96(6.69+0.24)
    4220.11: perl log --grep='[how] to'                   6.95(6.58+0.33)
    4220.13: basic log --grep='\(e.t[^ ]*\|v.ry\) rare'   7.10(6.80+0.27)
    4220.14: extended log --grep='(e.t[^ ]*|v.ry) rare'   7.07(6.80+0.26)
    4220.15: perl log --grep='(e.t[^ ]*|v.ry) rare'       7.70(7.46+0.22)
    4220.17: basic log --grep='m\(ú\|u\)lt.b\(æ\|y\)te'   6.12(5.87+0.24)
    4220.18: extended log --grep='m(ú|u)lt.b(æ|y)te'      6.14(5.84+0.26)
    4220.19: perl log --grep='m(ú|u)lt.b(æ|y)te'          6.16(5.93+0.20)

With -i:

    $ GIT_PERF_REPEAT_COUNT=10 GIT_PERF_LARGE_REPO=~/g/linux GIT_PERF_4220_LOG_OPTS=' -i' ./run p4220-log-grep-engines.sh
    [...]
    Test                                                     this tree
    ------------------------------------------------------------------------
    4220.1: basic log -i --grep='how.to'                     6.74(6.41+0.32)
    4220.2: extended log -i --grep='how.to'                  6.78(6.55+0.22)
    4220.3: perl log -i --grep='how.to'                      6.06(5.77+0.28)
    4220.5: basic log -i --grep='^how to'                    6.80(6.57+0.22)
    4220.6: extended log -i --grep='^how to'                 6.83(6.52+0.29)
    4220.7: perl log -i --grep='^how to'                     6.16(5.94+0.20)
    4220.9: basic log -i --grep='[how] to'                   7.87(7.61+0.24)
    4220.10: extended log -i --grep='[how] to'               7.85(7.57+0.27)
    4220.11: perl log -i --grep='[how] to'                   7.03(6.75+0.25)
    4220.13: basic log -i --grep='\(e.t[^ ]*\|v.ry\) rare'   8.68(8.41+0.25)
    4220.14: extended log -i --grep='(e.t[^ ]*|v.ry) rare'   8.80(8.44+0.28)
    4220.15: perl log -i --grep='(e.t[^ ]*|v.ry) rare'       7.85(7.56+0.26)
    4220.17: basic log -i --grep='m\(ú\|u\)lt.b\(æ\|y\)te'   6.94(6.68+0.24)
    4220.18: extended log -i --grep='m(ú|u)lt.b(æ|y)te'      7.04(6.76+0.24)
    4220.19: perl log -i --grep='m(ú|u)lt.b(æ|y)te'          6.26(5.92+0.29)

See commit ("perf: add a comparison test of grep regex engines", 2017-04-19) for details on the machine the above test run was executed on.

Before commit ("log: make --regexp-ignore-case work with --perl-regexp", 2017-05-20) this test will almost definitely fail (depending on the repo) if passed the -i option, since it wasn't properly supported under PCRE.

---
 t/perf/p4220-log-grep-engines.sh | 44 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100755 t/perf/p4220-log-grep-engines.sh

new file mode 100755
index 0000000000..02793ac77b
@@ -0,0 +1,44 @@
+#!/bin/sh
+
+test_description="Comparison of git-log's --grep regex engines
+
+Set GIT_PERF_4220_LOG_OPTS in the environment to pass options to
+git-grep. Make sure to include a leading space,
+e.g. GIT_PERF_4220_LOG_OPTS=' -i'. Some options to try:
+
+	-i
+	--invert-grep
+	-i --invert-grep
+"
+
+. ./perf-lib.sh
+
+test_perf_large_repo
+test_checkout_worktree
+
+for pattern in \
+	'how.to' \
+	'^how to' \
+	'[how] to' \
+	'\(e.t[^ ]*\|v.ry\) rare' \
+	'm\(ú\|u\)lt.b\(æ\|y\)te'
+do
+	for engine in basic extended perl
+	do
+		if test $engine != "basic"
+		then
+			# Poor man's basic -> extended converter.
+			pattern=$(echo $pattern | sed 's/\\//g')
+		fi
+		test_perf "$engine log$GIT_PERF_4220_LOG_OPTS --grep='$pattern'" "
+			git -c grep.patternType=$engine log --pretty=format:%h$GIT_PERF_4220_LOG_OPTS --grep='$pattern' >'out.$engine' || :
+		"
+	done
+
+	test_expect_success "assert that all engines found the same for$GIT_PERF_4220_LOG_OPTS '$pattern'" "
+		test_cmp 'out.basic' 'out.extended' &&
+		test_cmp 'out.basic' 'out.perl'
+	"
+done
+
+test_done

2.13.0.303.g4ebf302169

Add a die(...) to a default case for the switch statement selecting between grep pattern types under --recurse-submodules.

Normally this would be caught by -Wswitch, but the grep_pattern_type type is converted to int by going through parse_options(). Changing the argument type passed to compile_submodule_options() won't work, the value will just get coerced. The -Wswitch-default warning will warn about it, but that produces a lot of noise across the codebase, this potential issue would be drowned in that noise.

Thus catching this at runtime is the least bad option. This won't ever trigger in practice, but if a new pattern type were to be added this catches an otherwise silent bug during development.

See commit 0281e487fd ("grep: optionally recurse into submodules", 2016-12-16) for the initial addition of this code.

---
 builtin/grep.c | 2 ++
 1 file changed, 2 insertions(+)

index 3ffb5b4e81..a191e2976b 100644
@@ -495,6 +495,8 @@ static void compile_submodule_options(const struct grep_opt *opt,
 		break;
 	case GREP_PATTERN_TYPE_UNSPECIFIED:
 		break;
+	default:
+		die("BUG: Added a new grep pattern type without updating switch statement");
 	}
 
 	for (pattern = opt->pattern_list; pattern != NULL;

2.13.0.303.g4ebf302169

Remove redundant assignments to the "regflags" variable. This variable is only used set under GREP_PATTERN_TYPE_ERE, so there's no need to un-set it under GREP_PATTERN_TYPE_{FIXED,BRE,PCRE}.

Back in 5010cb5fcc[1], we did do "opt.regflags &= ~REG_EXTENDED" upon seeing "-G" on the command line and flipped the bit on upon seeing "-E", but I think that was perfectly sensible and it would have been a bug if we didn't. They were part of the command line parsing that could have seen "-E" on the command line earlier.

When cca2c172 ("git-grep: do not die upon -F/-P when grep.extendedRegexp is set.", 2011-05-09) switched the command line parsing to "read into a 'tentatively this is what we saw the last' variable and then finally commit just once", we didn't touch opt.regflags for PCRE and FIXED, but we still had to flip regflags between BRE and ERE, because parsing of grep.extendedregexp configuration variable directly touched opt.regflags back then, which was done by b22520a3 ("grep: allow -E and -n to be turned on by default via configuration", 2011-03-30).

When 84befcd0 ("grep: add a grep.patternType configuration setting", 2012-08-03) introduced extended_regexp_option field, we stopped flipping regflags while reading the configuration, and that was when we should have noticed and stopped dropping REG_EXTENDED bit in the "now we can commit what type to use" helper function.

There is no reason to do this anymore, so stop doing it, more to reduce "wait this is used under fixed/BRE/PCRE how?" confusion when reading the code, than to to save ourselves trivial CPU cycles by removing one assignment.

1. "built-in "git grep"", 2006-04-30.

---
 grep.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

index 47cee45067..bf6c2494fd 100644
@@ -179,7 +179,6 @@ 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->regflags &= ~REG_EXTENDED;
 		break;
 
 	case GREP_PATTERN_TYPE_ERE:

@@ -191,13 +190,11 @@ static void grep_set_pattern_type_option(enum grep_pattern_type pattern_type, st
 	case GREP_PATTERN_TYPE_FIXED:
 		opt->fixed = 1;
 		opt->pcre = 0;
-		opt->regflags &= ~REG_EXTENDED;
 		break;
 
 	case GREP_PATTERN_TYPE_PCRE:
 		opt->fixed = 0;
 		opt->pcre = 1;
-		opt->regflags &= ~REG_EXTENDED;
 		break;
 	}
 }

@@ -415,10 +412,9 @@ static void compile_fixed_regexp(struct grep_pat *p, struct grep_opt *opt)
 {
 	struct strbuf sb = STRBUF_INIT;
 	int err;
-	int regflags;
+	int regflags = opt->regflags;
 
 	basic_regex_quote_buf(&sb, p->pattern);
-	regflags = opt->regflags & ~REG_EXTENDED;
 	if (opt->ignore_case)
 		regflags |= REG_ICASE;
 	err = regcomp(&p->regexp, sb.buf, regflags);

2.13.0.303.g4ebf302169

Factor the test for \0 in grep patterns into a function. Since commit 9eceddeec6 ("Use kwset in grep", 2011-08-21) any pattern containing a \0 is considered fixed as regcomp() can't handle it.

This change makes later changes that make use of either has_null() or is_fixed() (but not both) smaller.

While I'm at it make the comment conform to the style guide, i.e. add an opening "/*\n".

---
 grep.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

index bf6c2494fd..79eb681c6e 100644
@@ -321,6 +321,18 @@ static NORETURN void compile_regexp_failed(const struct grep_pat *p,
 	die("%s'%s': %s", where, p->pattern, error);
 }
 
+static int has_null(const char *s, size_t len)
+{
+	/*
+	 * regcomp cannot accept patterns with NULs so when using it
+	 * we consider any pattern containing a NUL fixed.
+	 */
+	if (memchr(s, 0, len))
+		return 1;
+
+	return 0;
+}
+
 #ifdef USE_LIBPCRE
 static void compile_pcre_regexp(struct grep_pat *p, const struct grep_opt *opt)
 {

@@ -394,12 +406,6 @@ static int is_fixed(const char *s, size_t len)
 {
 	size_t i;
 
-	/* regcomp cannot accept patterns with NULs so we
-	 * consider any pattern containing a NUL fixed.
-	 */
-	if (memchr(s, 0, len))
-		return 1;
-
 	for (i = 0; i < len; i++) {
 		if (is_regex_special(s[i]))
 			return 0;

@@ -451,7 +457,7 @@ static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
 	 * simple string match using kws.  p->fixed tells us if we
 	 * want to use kws.
 	 */
-	if (opt->fixed || is_fixed(p->pattern, p->patternlen))
+	if (opt->fixed || has_null(p->pattern, p->patternlen) || is_fixed(p->pattern, p->patternlen))
 		p->fixed = !icase || ascii_only;
 	else
 		p->fixed = 0;

2.13.0.303.g4ebf302169

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.

---
 Makefile      | 4 ++--
 grep.c        | 6 +++---
 grep.h        | 2 +-
 t/test-lib.sh | 2 +-
 4 files changed, 7 insertions(+), 7 deletions(-)

index d1587452f1..374fbc7e58 100644
@@ -1088,7 +1088,7 @@ 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)

@@ -2240,7 +2240,7 @@ 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 ','\'',$(NO_UNIX_SOCKETS)))'\' >>$@+

index 79eb681c6e..854f2404be 100644
@@ -333,7 +333,7 @@ static int has_null(const char *s, size_t len)
 	return 0;
 }
 
-#ifdef USE_LIBPCRE
+#ifdef USE_LIBPCRE1
 static void compile_pcre_regexp(struct grep_pat *p, const struct grep_opt *opt)
 {
 	const char *error;

@@ -385,7 +385,7 @@ 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");

@@ -400,7 +400,7 @@ 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)
 {

index 267534ca24..073b0e4c92 100644
@@ -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;

index 04d857a42b..1d0f636cbd 100644
@@ -1014,7 +1014,7 @@ 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?

2.13.0.303.g4ebf302169

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.

An earlier change in this series ("grep: change the internal PCRE macro names to be PCRE1", 2017-04-07) elaborates on the motivations behind this change.

---
 grep.c | 52 ++++++++++++++++++++++++++--------------------------
 grep.h |  8 ++++----
 2 files changed, 30 insertions(+), 30 deletions(-)

index 854f2404be..07512346b1 100644
@@ -178,23 +178,23 @@ 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;
 		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;
 		break;
 
 	case GREP_PATTERN_TYPE_PCRE:
 		opt->fixed = 0;
-		opt->pcre = 1;
+		opt->pcre1 = 1;
 		break;
 	}
 }

@@ -334,7 +334,7 @@ static int has_null(const char *s, size_t len)
 }
 
 #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;

@@ -342,23 +342,23 @@ 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;

@@ -366,7 +366,7 @@ 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);

@@ -379,25 +379,25 @@ 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 */

@@ -477,8 +477,8 @@ 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;
 	}
 

@@ -834,8 +834,8 @@ 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);

@@ -914,8 +914,8 @@ 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);

index 073b0e4c92..38ac82b638 100644
@@ -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;

@@ -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;

2.13.0.303.g4ebf302169

Move the is_fixed() function which are currently only used in compile_regexp() earlier so it can be used in the PCRE family of functions in a later change.

---
 grep.c | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

index 07512346b1..1157529115 100644
@@ -321,6 +321,18 @@ static NORETURN void compile_regexp_failed(const struct grep_pat *p,
 	die("%s'%s': %s", where, p->pattern, error);
 }
 
+static int is_fixed(const char *s, size_t len)
+{
+	size_t i;
+
+	for (i = 0; i < len; i++) {
+		if (is_regex_special(s[i]))
+			return 0;
+	}
+
+	return 1;
+}
+
 static int has_null(const char *s, size_t len)
 {
 	/*

@@ -402,18 +414,6 @@ static void free_pcre1_regexp(struct grep_pat *p)
 }
 #endif /* !USE_LIBPCRE1 */
 
-static int is_fixed(const char *s, size_t len)
-{
-	size_t i;
-
-	for (i = 0; i < len; i++) {
-		if (is_regex_special(s[i]))
-			return 0;
-	}
-
-	return 1;
-}
-
 static void compile_fixed_regexp(struct grep_pat *p, struct grep_opt *opt)
 {
 	struct strbuf sb = STRBUF_INIT;

2.13.0.303.g4ebf302169

Add a PTHREADS prerequisite which is false when git is compiled with NO_PTHREADS=YesPlease.

There's lots of custom code that runs when threading isn't available, but before this prerequisite there was no way to test it.

---
 Makefile      | 1 +
 t/README      | 4 ++++
 t/test-lib.sh | 1 +
 3 files changed, 6 insertions(+)

index 374fbc7e58..a79274e5e6 100644
@@ -2242,6 +2242,7 @@ GIT-BUILD-OPTIONS: FORCE
 	@echo NO_EXPAT=\''$(subst ','\'',$(subst ','\'',$(NO_EXPAT)))'\' >>$@+
 	@echo USE_LIBPCRE1=\''$(subst ','\'',$(subst ','\'',$(USE_LIBPCRE)))'\' >>$@+
 	@echo NO_PERL=\''$(subst ','\'',$(subst ','\'',$(NO_PERL)))'\' >>$@+
+	@echo NO_PTHREADS=\''$(subst ','\'',$(subst ','\'',$(NO_PTHREADS)))'\' >>$@+
 	@echo NO_PYTHON=\''$(subst ','\'',$(subst ','\'',$(NO_PYTHON)))'\' >>$@+
 	@echo NO_UNIX_SOCKETS=\''$(subst ','\'',$(subst ','\'',$(NO_UNIX_SOCKETS)))'\' >>$@+
 	@echo PAGER_ENV=\''$(subst ','\'',$(subst ','\'',$(PAGER_ENV)))'\' >>$@+

index a90cb62583..2f95860369 100644
@@ -817,6 +817,10 @@ use these, and "test_set_prereq" for how to define your own.
    Test is run on a filesystem which converts decomposed utf-8 (nfd)
    to precomposed utf-8 (nfc).
 
+ - PTHREADS
+
+   Git wasn't compiled with NO_PTHREADS=YesPlease.
+
 Tips for Writing Tests
 ----------------------
 

index 1d0f636cbd..43529451f9 100644
@@ -1013,6 +1013,7 @@ esac
 
 ( COLUMNS=1 && test $COLUMNS = 1 ) && test_set_prereq COLUMNS_CAN_BE_1
 test -z "$NO_PERL" && test_set_prereq PERL
+test -z "$NO_PTHREADS" && test_set_prereq PTHREADS
 test -z "$NO_PYTHON" && test_set_prereq PYTHON
 test -n "$USE_LIBPCRE1" && test_set_prereq PCRE
 test -z "$NO_GETTEXT" && test_set_prereq GETTEXT

2.13.0.303.g4ebf302169

Add a test for the warning that's emitted when --threads or pack.threads is provided under NO_PTHREADS=YesPlease. This uses the new PTHREADS prerequisite.

The assertion for C_LOCALE_OUTPUT in the latter test is currently redundant, since unlike index-pack the pack-objects warnings aren't i18n'd. However they might be changed to be i18n'd in the future, and there's no harm in future-proofing the test.

There's an existing bug in the implementation of pack-objects which this test currently tests for as-is. Details about the bug & the fix are included in a follow-up change.

---
 t/t5300-pack-object.sh | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

index 43a672c345..6ed23ee1d2 100755
@@ -421,6 +421,42 @@ test_expect_success 'index-pack <pack> works in non-repo' '
 	test_path_is_file foo.idx
 '
 
+test_expect_success !PTHREADS,C_LOCALE_OUTPUT 'index-pack --threads=N or pack.threads=N warns when no pthreads' '
+	test_must_fail git index-pack --threads=2 2>err &&
+	grep ^warning: err >warnings &&
+	test_line_count = 1 warnings &&
+	grep -F "no threads support, ignoring --threads=2" err &&
+
+	test_must_fail git -c pack.threads=2 index-pack 2>err &&
+	grep ^warning: err >warnings &&
+	test_line_count = 1 warnings &&
+	grep -F "no threads support, ignoring pack.threads" err &&
+
+	test_must_fail git -c pack.threads=2 index-pack --threads=4 2>err &&
+	grep ^warning: err >warnings &&
+	test_line_count = 2 warnings &&
+	grep -F "no threads support, ignoring --threads=4" err &&
+	grep -F "no threads support, ignoring pack.threads" err
+'
+
+test_expect_success !PTHREADS,C_LOCALE_OUTPUT 'pack-objects --threads=N or pack.threads=N warns when no pthreads' '
+	git pack-objects --threads=2 --stdout --all </dev/null >/dev/null 2>err &&
+	grep ^warning: err >warnings &&
+	test_line_count = 1 warnings &&
+	grep -F "no threads support, ignoring --threads" err &&
+
+	git -c pack.threads=2 pack-objects --stdout --all </dev/null >/dev/null 2>err &&
+	grep ^warning: err >warnings &&
+	test_must_fail test_line_count = 1 warnings &&
+	grep -F "no threads support, ignoring pack.threads" err &&
+
+	git -c pack.threads=2 pack-objects --threads=4 --stdout --all </dev/null >/dev/null 2>err &&
+	grep ^warning: err >warnings &&
+	test_line_count = 2 warnings &&
+	grep -F "no threads support, ignoring --threads" err &&
+	grep -F "no threads support, ignoring pack.threads" err
+'
+
 #
 # WARNING!
 #

2.13.0.303.g4ebf302169

Fix a buggy warning about threads under NO_PTHREADS=YesPlease. Due to re-using the delta_search_threads variable for both the state of the "pack.threads" config & the --threads option, setting "pack.threads" but not supplying --threads would trigger the warning for both "pack.threads" & --threads.

Solve this bug by resetting the delta_search_threads variable in git_pack_config(), it might then be set by --threads again and be subsequently warned about, as the test I'm changing here asserts.

---
 builtin/pack-objects.c | 4 +++-
 t/t5300-pack-object.sh | 2 +-
 2 files changed, 4 insertions(+), 2 deletions(-)

index 9b4ba8a80d..efa21a15dd 100644
@@ -2472,8 +2472,10 @@ static int git_pack_config(const char *k, const char *v, void *cb)
 			die("invalid number of threads specified (%d)",
 			    delta_search_threads);
 #ifdef NO_PTHREADS
-		if (delta_search_threads != 1)
+		if (delta_search_threads != 1) {
 			warning("no threads support, ignoring %s", k);
+			delta_search_threads = 0;
+		}
 #endif
 		return 0;
 	}

index 6ed23ee1d2..9c68b99251 100755
@@ -447,7 +447,7 @@ test_expect_success !PTHREADS,C_LOCALE_OUTPUT 'pack-objects --threads=N or pack.
 
 	git -c pack.threads=2 pack-objects --stdout --all </dev/null >/dev/null 2>err &&
 	grep ^warning: err >warnings &&
-	test_must_fail test_line_count = 1 warnings &&
+	test_line_count = 1 warnings &&
 	grep -F "no threads support, ignoring pack.threads" err &&
 
 	git -c pack.threads=2 pack-objects --threads=4 --stdout --all </dev/null >/dev/null 2>err &&

2.13.0.303.g4ebf302169

Add a warning about missing thread support when grep.threads or --threads is set to a non 0 (default) or 1 (no parallelism) value under NO_PTHREADS=YesPlease.

This is for consistency with the index-pack & pack-objects commands, which also take a --threads option & are configurable via pack.threads, and have long warned about the same under NO_PTHREADS=YesPlease.

---
 builtin/grep.c  | 13 +++++++++++++
 t/t7810-grep.sh | 18 ++++++++++++++++++
 2 files changed, 31 insertions(+)

index a191e2976b..3c721b75a5 100644
@@ -289,6 +289,17 @@ static int grep_cmd_config(const char *var, const char *value, void *cb)
 		if (num_threads < 0)
 			die(_("invalid number of threads specified (%d) for %s"),
 			    num_threads, var);
+#ifdef NO_PTHREADS
+		else if (num_threads && num_threads != 1) {
+			/*
+			 * TRANSLATORS: %s is the configuration
+			 * variable for tweaking threads, currently
+			 * grep.threads
+			 */
+			warning(_("no threads support, ignoring %s"), var);
+			num_threads = 0;
+		}
+#endif
 	}
 
 	return st;

@@ -1229,6 +1240,8 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 	else if (num_threads < 0)
 		die(_("invalid number of threads specified (%d)"), num_threads);
 #else
+	if (num_threads)
+		warning(_("no threads support, ignoring --threads"));
 	num_threads = 0;
 #endif
 

index 561709ef6a..f106387820 100755
@@ -791,6 +791,24 @@ do
 	"
 done
 
+test_expect_success !PTHREADS,C_LOCALE_OUTPUT 'grep --threads=N or pack.threads=N warns when no pthreads' '
+	git grep --threads=2 Hello hello_world 2>err &&
+	grep ^warning: err >warnings &&
+	test_line_count = 1 warnings &&
+	grep -F "no threads support, ignoring --threads" err &&
+	git -c grep.threads=2 grep Hello hello_world 2>err &&
+	grep ^warning: err >warnings &&
+	test_line_count = 1 warnings &&
+	grep -F "no threads support, ignoring grep.threads" err &&
+	git -c grep.threads=2 grep --threads=4 Hello hello_world 2>err &&
+	grep ^warning: err >warnings &&
+	test_line_count = 2 warnings &&
+	grep -F "no threads support, ignoring --threads" err &&
+	grep -F "no threads support, ignoring grep.threads" err &&
+	git -c grep.threads=0 grep --threads=0 Hello hello_world 2>err &&
+	test_line_count = 0 err
+'
+
 test_expect_success 'grep from a subdirectory to search wider area (1)' '
 	mkdir -p s &&
 	(

2.13.0.303.g4ebf302169

Change the grep_{lock,unlock} functions to assert that num_threads is true, instead of only locking & unlocking the pthread mutex lock when it is.

These functions are never called when num_threads isn't true, this logic has gone through multiple iterations since the initial introduction of grep threading in commit 5b594f457a ("Threaded grep", 2010-01-25), but ever since then they'd only be called if num_threads was true, so this check made the code confusing to read.

Replace the check with an assertion, so that it's clear to the reader that this code path is never taken unless we're spawning threads.

---
 builtin/grep.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

index 3c721b75a5..b1095362fb 100644
@@ -73,14 +73,14 @@ static pthread_mutex_t grep_mutex;
 
 static inline void grep_lock(void)
 {
-	if (num_threads)
-		pthread_mutex_lock(&grep_mutex);
+	assert(num_threads);
+	pthread_mutex_lock(&grep_mutex);
 }
 
 static inline void grep_unlock(void)
 {
-	if (num_threads)
-		pthread_mutex_unlock(&grep_mutex);
+	assert(num_threads);
+	pthread_mutex_unlock(&grep_mutex);
 }
 
 /* Signalled when a new work_item is added to todo. */

2.13.0.303.g4ebf302169

I actually do not mind a reroll that goes together with this. The only reason why I skipped the earlier one was because I looked at the original one, and the discussion on the reroll of this 'easy to review' part indicated that it will be rerolled, before I got to look at these upper layer patches.

Overall nicely done. I only had just a few observations.

Thanks.

Great, now that the base of this is migrating to next, here's the second part of this.

For v1 see <[email protected]>
(https://public-inbox.org/git/[email protected]/).

The only changes to the content are better if/else branching around conditional macros (but no functional changes) in the PCRE v1 JIT API patch in response to a comment by Simon Ruderich.

The only other changes are trivial updates to the commit messages to account for t/perf changes made in the series this builds on.

Ævar Arnfjörð Bjarmason (7):
grep: don't redundantly compile throwaway patterns under threading
grep: skip pthreads overhead when using one thread
log: add -P as a synonym for --perl-regexp
grep: add support for the PCRE v1 JIT API
grep: un-break building with PCRE < 8.32
grep: un-break building with PCRE < 8.20
grep: add support for PCRE v2

 Documentation/rev-list-options.txt |   1 +
 Makefile                           |  30 +++++--
 builtin/grep.c                     |  16 +++-
 configure.ac                       |  77 +++++++++++++---
 grep.c                             | 177 ++++++++++++++++++++++++++++++++++++-
 grep.h                             |  31 +++++++
 revision.c                         |   2 +-
 t/t4202-log.sh                     |  12 +++
 t/test-lib.sh                      |   2 +-
 9 files changed, 324 insertions(+), 24 deletions(-)

2.13.0.303.g4ebf302169

Change the pattern compilation logic under threading so that grep doesn't compile a pattern it never ends up using on the non-threaded code path, only to compile it again N times for N threads which will each use their own copy, ignoring the initially compiled pattern.

This redundant compilation dates back to the initial introduction of the threaded grep in commit 5b594f457a ("Threaded grep", 2010-01-25).

There was never any reason for doing this redundant work other than an oversight in the initial commit. Jeff King suggested on-list in <[email protected]> that this might be needed to check the pattern for sanity before threaded execution commences.

That's not the case. The pattern is compiled under threading in start_threads() before any concurrent execution has started by calling pthread_create(), so if the pattern contains an error we still do the right thing. I.e. die with one error before any threaded execution has commenced, instead of e.g. spewing out an error for each N threads, which could be a regression a change like this might inadvertently introduce.

This change is not meant as an optimization, any performance gains from this are in the hundreds to thousands of nanoseconds at most. If we wanted more performance here we could just re-use the compiled patterns in multiple threads (regcomp(3) is thread-safe), or partially re-use them and the associated structures in the case of later PCRE JIT changes.

Rather, it's just to make the code easier to reason about. It's confusing to debug this under threading & non-threading when the threading codepaths redundantly compile a pattern which is never used.

The reason the patterns are recompiled is as a side-effect of duplicating the whole grep_opt structure, which is not thread safe, writable, and munged during execution. The grep_opt structure then points to the grep_pat structure where pattern or patterns are stored.

I looked into e.g. splitting the API into some "do & alloc threadsafe stuff", "spawn thread", "do and alloc non-threadsafe stuff", but the execution time of grep_opt_dup() & pattern compilation is trivial compared to actually executing the grep, so there was no point. Even with the more expensive JIT changes to follow the most expensive PCRE patterns take something like 0.0X milliseconds to compile at most[1].

The undocumented --debug mode added in commit 17bf35a3c7 ("grep: teach --debug option to dump the parse tree", 2012-09-13) still works properly with this change. It only emits debugging info during pattern compilation, which is now dumped by the pattern compiled just before the first thread is started.

1. http://sljit.sourceforge.net/pcre.html

---
 builtin/grep.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

index b1095362fb..12e62fcbf3 100644
@@ -224,7 +224,8 @@ static void start_threads(struct grep_opt *opt)
 		int err;
 		struct grep_opt *o = grep_opt_dup(opt);
 		o->output = strbuf_out;
-		o->debug = 0;
+		if (i)
+			o->debug = 0;
 		compile_grep_patterns(o);
 		err = pthread_create(&threads[i], NULL, run, o);
 

@@ -1167,8 +1168,6 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 	if (!opt.fixed && opt.ignore_case)
 		opt.regflags |= REG_ICASE;
 
-	compile_grep_patterns(&opt);
-
 	/*
 	 * We have to find "--" in a separate pass, because its presence
 	 * influences how we will parse arguments that come before it.

@@ -1245,6 +1244,15 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 	num_threads = 0;
 #endif
 
+	if (!num_threads)
+		/*
+		 * The compiled patterns on the main path are only
+		 * used when not using threading. Otherwise
+		 * start_threads() below calls compile_grep_patterns()
+		 * for each thread.
+		 */
+		compile_grep_patterns(&opt);
+
 #ifndef NO_PTHREADS
 	if (num_threads) {
 		if (!(opt.name_only || opt.unmatch_name_only || opt.count)

2.13.0.303.g4ebf302169

OK.

When opt is passed to run(), opt->debug is still true for the first worker thread. As long as opt->debug never makes difference after compile_grep_patterns(opt) returns, I think the change in this patch safe. I do not know if we want to rely on it, but we can explain it away by saying "we'll only debug the runtime behaviour for the first worker only", or something, so it is not a big deal either way.

Thanks.

Right, the --debug feature only impacts pattern compilation.

I think it's a pointless distraction to start speculating in this commit message what we're going to do with --debug it if it ever starts emitting some debugging information at pattern execution time.

As an aside, I'd very much like to remove both --debug and the --and/--or/--all-match, gives some very rough edges in the UI and how easy it is to make that feature error or segfault, I suspect you might be the only one using it.

There are pattern matching optimizations I'd like to do that are much more of a pain with that feature around. It's easy to AND multiple regexes together into one match via -e, but when you have to deal with negation and arbitrarily complex chained & parenthesized AND/OR you end up having to run your custom state machine on every line with multiple regex matches per line.

The system grep doesn't have this feature, and people seem to do without it. The motivation for it isn't explained in commit 79d3696cfb ("git-grep: boolean expression on pattern matching.", 2006-06-30), but I suspect it's a hack around not being able to do "git grep ... | git grep -v ...", which is how you'd do "I'd like to match this, but not that" with the system grep.

Just supporting that would be much easier than supporting the and/or matching machinery.

OK.

I agree that rewriting "grep -e A -e B" to "grep -e A|B" as an optimization is an interesting possibility to look into, and I can understand that having to support "--and" and "--not" would make such an optimization harder to implement. "-e A --and -e B" must become "-e A.*B|B.*A" and as you get more terms your unified pattern will grow combinatorial, at which point you would be better off matching N patterns and combining the result.

Ever saw a user run "ps | grep rogue | grep -v grep" to find a rogue process to kill? That would not work if the rogue process's command line has a word "grep". Because "git grep" is often run on files in order to find the location the patterns appear in, "git grep -e pattern | grep -v unwanted" shares the same issue--the unwanted pattern may appear in the filename, and the downstream "grep -v" may filter out a valid hit. This is why "--not" exists [*1*]. I agree that emulating it within the same "concatenate patterns into one" optimization you are envisioning may be hard.

Attempting to optimize "--all-match" would share similar difficulty with "--and", but your matching now must be done with the entire buffer and not go line-by-line. It was meant to make it possible to say "find commits that avarab@ talks about both regex and log", i.e.

	$ git log --author=avarab@ --all-match --grep=log --grep=regex

This is not something you can emulate by piping an output of grep to another grep.

But none of the above means you have to give up optimizing.

You can choose not to combine them into a single pattern if certain constructions are hard, and do only the easy ones. If you think that harder combinations are not used very often, the result would be faster for many cases while not losing useful features, which is what we want.

[Footnote]

*1* For human consumption, lack of "--not" may not hurt in the sense
that there are workarounds (i.e. you can do without "| grep -v unwanted" and filter irrelevant ones by eyeballing). But it is essential while scripting and trying to be precise.

To be clear the point of my mail was not to say "I can't think of a way to support both of these things, help!", obviously we can continue to maintain two codepaths. The point was to raise the idea that we could simply remove the more complex & doomed to forever be slow codepath.

Obviously there are caveats with the likes of "grep foo | grep bar" that don't exist with "grep -e foo --and -e bar". I'm less interested in whether we can come up with cases that wouldn't be possible if this were removed, than if anyone's using them in practice.

I suspect that to the extent anyone uses this for common things it could be emulated by --single-line --perl-regexp and e.g. 'foo.*bar' instead of 'foo' --and 'bar'. I.e. we could offer to AND together your regexes and match them over the entire content.

If someone needed something more complex we could just show an example of piping e.g. \0-delimited commit messages into an arbitrary perl script you provide.

Anyway, I've only looked this over a tiny bit, and I don't know whether it's worth it to remove this, right now I was just interested in some reports of what it was used for. I.e. whether anyone uses it for N-level deep mixed AND/OR branches, or whether it's really just a lazy way to concat regexes and get around the current limitation of not being able to match across lines.

To be clear, the point of my response was that these features must remain. As long as they are more convenient than sifting through output produced by pattern matching engine that is less powerful (which forces the user to give wider pattern than desired, to avoid false negatives) with eyeball, having to match each pattern one by one, instead of being able to use a combined and more efficient single pattern, is still more efficient for the end user, which is the point of using a computer.

Skip the administrative overhead of using pthreads when only using one thread. Instead take the non-threaded path which would be taken under NO_PTHREADS.

The threading support was initially added in commit 5b594f457a ("Threaded grep", 2010-01-25) with a hardcoded compile-time number of 8 threads. Later the number of threads was made configurable in commit 89f09dd34e ("grep: add --threads=<num> option and grep.threads configuration", 2015-12-15).

That change did not add any special handling for --threads=1. Now we take a slightly faster path by skipping thread handling entirely when 1 thread is requested.

---
 builtin/grep.c | 2 ++
 1 file changed, 2 insertions(+)

index 12e62fcbf3..bd008cb100 100644
@@ -1238,6 +1238,8 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 		num_threads = GREP_NUM_THREADS_DEFAULT;
 	else if (num_threads < 0)
 		die(_("invalid number of threads specified (%d)"), num_threads);
+	if (num_threads == 1)
+		num_threads = 0;
 #else
 	if (num_threads)
 		warning(_("no threads support, ignoring --threads"));

2.13.0.303.g4ebf302169

OK, this is what Peff and you were discussing in the earlier round, having the controller do the work himself, instead of sitting and waiting for a sole worker to finish the work. Looks good.

Thanks.

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.

Make it consistent with "grep" rather 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>.

---
 Documentation/rev-list-options.txt |  1 +
 revision.c                         |  2 +-
 t/t4202-log.sh                     | 12 ++++++++++++
 3 files changed, 14 insertions(+), 1 deletion(-)

index a46f70c2b1..9c44eae55d 100644
@@ -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.

index 4883cdd2d0..60329da1bd 100644
@@ -1996,7 +1996,7 @@ 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;

index dbed3efeee..2b07d1c0c2 100755
@@ -404,8 +404,20 @@ 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
+		else
+			test_must_fail git log -P \
+				--grep="[\d]\|"
+		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 &&

2.13.0.303.g4ebf302169

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.

Enabling JIT support usually improves performance by more than 40%. 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 benchmarks & overview of compilation times is at: http://sljit.sourceforge.net/pcre.html

With this change the difference in a t/perf/p7820-grep-engines.sh run is, with just the /perl/ tests shown:

    $ GIT_PERF_REPEAT_COUNT=30 GIT_PERF_LARGE_REPO=~/g/linux GIT_PERF_MAKE_OPTS='-j8 USE_LIBPCRE=YesPlease CC=~/perl5/installed/bin/gcc NO_R_TO_GCC_LINKER=YesPlease CFLAGS=-O3 LIBPCREDIR=/home/avar/g/pcre/inst LDFLAGS=-Wl,-rpath,/home/avar/g/pcre/inst/lib' ./run HEAD~ HEAD p7820-grep-engines.sh
    Test                                           HEAD~             HEAD
    ---------------------------------------------------------------------------------------
    7820.3: perl grep 'how.to'                      0.35(1.11+0.43)   0.23(0.42+0.46) -34.3%
    7820.7: perl grep '^how to'                     0.64(2.71+0.36)   0.27(0.66+0.44) -57.8%
    7820.11: perl grep '[how] to'                   0.63(2.51+0.42)   0.33(0.98+0.39) -47.6%
    7820.15: perl grep '(e.t[^ ]*|v.ry) rare'       1.17(5.61+0.35)   0.34(1.08+0.46) -70.9%
    7820.19: perl grep 'm(ú|u)lt.b(æ|y)te'          0.43(1.52+0.44)   0.30(0.88+0.42) -30.2%

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.

The implementation is relatively verbose because even if PCRE_CONFIG_JIT is defined only a call to pcre_config() can determine if the JIT is available, and if so the faster pcre_jit_exec() function should be called instead of pcre_exec(), and a different (but not complimentary!) function needs to be called to free pcre1_extra_info.

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

---
 grep.c | 34 +++++++++++++++++++++++++++++++++-
 grep.h |  6 ++++++
 2 files changed, 39 insertions(+), 1 deletion(-)

index 1157529115..49e9aed457 100644
@@ -351,6 +351,9 @@ 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))

@@ -365,9 +368,20 @@ 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);
+		p->pcre1_jit_on = 1;
+	}
+#endif
 }
 
 static int pcre1match(struct grep_pat *p, const char *line, const char *eol,

@@ -378,8 +392,17 @@ static int pcre1match(struct grep_pat *p, const char *line, const char *eol,
 	if (eflags & REG_NOTBOL)
 		flags |= PCRE_NOTBOL;
 
+#ifdef PCRE_CONFIG_JIT
+	if (p->pcre1_jit_on)
+		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
+#endif
+	/* PCRE_CONFIG_JIT !p->pcre1_jit_on else branch */
 	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);
 	if (ret > 0) {

@@ -394,7 +417,16 @@ 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
+	if (p->pcre1_jit_on) {
+		pcre_free_study(p->pcre1_extra_info);
+		pcre_jit_stack_free(p->pcre1_jit_stack);
+	} else
+#endif
+	/* PCRE_CONFIG_JIT !p->pcre1_jit_on else branch */
 	pcre_free(p->pcre1_extra_info);
+
 	pcre_free((void *)p->pcre1_tables);
 }
 #else /* !USE_LIBPCRE1 */

index 38ac82b638..14f47189f9 100644
@@ -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"

@@ -48,7 +52,9 @@ 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;
+	int pcre1_jit_on;
 	kwset_t kws;
 	unsigned fixed:1;
 	unsigned ignore_case:1;

2.13.0.303.g4ebf302169

It purely depends on how the the library, was compiled. I just wrote it like that because compiling the pattern is not a hot codepath (i.e. we call this max 8 or so times or so, whereas exec will be called thousands/millions/billions of times), so trying to avoid calling this trivial function seemed pointless.

But looking at this again it would be simpler to combine what you're suggesting with just passing a pointer to *.pcre[12]_jit_on directly, skipping the canjit variables.

Makes sense. Looks like the convention for this sort of thing is to just do s/BUG: //, e.g. the code in wrapper.c does that.

*Nod*

Makes sense. I'll change it.

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

---
 grep.c | 8 ++++----
 grep.h | 5 +++++
 2 files changed, 9 insertions(+), 4 deletions(-)

index 49e9aed457..3c0c30f033 100644
@@ -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,