grep: use PCRE v2 under the hood for -G & -E for big performance gain

Change the underlying engine powering POSIX basic & extended patterns to be PCRE v2 under the hood. This relies on an experimental SVN-trunk only PCRE v2 API which Philip Hazel (the PCRE maintainer) wrote up in response to a feature request I filed1[1]. This allows us to use pcre2_pattern_convert() to power all grep regex matches by converting the POSIX patterns into PCRE syntax before compiling them. Due to PCRE generally being faster than POSIX, but most importantly due to its JIT feature (where available) this speeds up grep by a *lot*. The improvements to the "perl" tests are already a part of this series, but all the other benchmarks show improvements made by this change alone: $ GIT_PERF_REPEAT_COUNT=30 GIT_PERF_LARGE_REPO=~/g/linux GIT_PERF_MAKE_COMMAND='grep -q LIBPCRE2 Makefile && make -j8 USE_LIBPCRE2=YesPlease USE_LIBPCRE2_BUNDLED=Y CC=~/perl5/installed/bin/gcc NO_R_TO_GCC_LINKER=YesPlease CFLAGS=-O3 || make -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 v2.13.0 HEAD -- p*grep* [...] Test v2.13.0 HEAD ----------------------------------------------------------------------------------------- 7810.1: grep worktree, cheap regex 0.19(0.35+0.62) 0.18(0.34+0.57) -5.3% 7810.2: grep worktree, expensive regex 4.35(30.52+0.32) 0.92(5.55+0.39) -78.9% 7810.3: grep --cached, cheap regex 2.92(2.83+0.06) 2.83(2.75+0.07) -3.1% 7810.4: grep --cached, expensive regex 21.12(21.02+0.08) 6.28(6.15+0.10) -70.3% 7820.1: basic grep how.to 0.28(1.27+0.41) 0.19(0.33+0.58) -32.1% 7820.2: extended grep how.to 0.28(1.19+0.49) 0.19(0.32+0.55) -32.1% 7820.3: perl grep how.to 0.27(1.10+0.52) 0.19(0.26+0.63) -29.6% 7820.5: basic grep ^how to 0.27(1.22+0.43) 0.18(0.28+0.63) -33.3% 7820.6: extended grep ^how to 0.27(1.20+0.44) 0.18(0.29+0.62) -33.3% 7820.7: perl grep ^how to 0.48(2.81+0.39) 0.18(0.29+0.61) -62.5% 7820.9: basic grep [how] to 0.42(2.19+0.44) 0.21(0.34+0.65) -50.0% 7820.10: extended grep [how] to 0.41(2.18+0.43) 0.21(0.36+0.63) -48.8% 7820.11: perl grep [how] to 0.47(2.63+0.38) 0.20(0.29+0.70) -57.4% 7820.13: basic grep $e.t[^ ]*\|v.ry$ rare 0.55(3.25+0.43) 0.19(0.53+0.52) -65.5% 7820.14: extended grep (e.t[^ ]*|v.ry) rare 0.54(3.30+0.42) 0.19(0.51+0.53) -64.8% 7820.15: perl grep (e.t[^ ]*|v.ry) rare 0.88(5.77+0.41) 0.19(0.52+0.53) -78.4% 7820.17: basic grep m$ú\|u$lt.b$æ\|y$te 0.28(1.28+0.47) 0.18(0.35+0.57) -35.7% 7820.18: extended grep m(ú|u)lt.b(æ|y)te 0.28(1.32+0.43) 0.18(0.28+0.64) -35.7% 7820.19: perl grep m(ú|u)lt.b(æ|y)te 0.32(1.62+0.43) 0.18(0.28+0.64) -43.8% 7821.1: fixed grep int 0.50(1.76+0.58) 0.39(1.16+0.69) -22.0% 7821.2: basic grep int 0.55(1.83+0.72) 0.41(1.10+0.68) -25.5% 7821.3: extended grep int 0.56(1.78+0.73) 0.47(1.17+0.75) -16.1% 7821.4: perl grep int 0.52(1.57+0.80) 0.47(1.29+0.64) -9.6% 7821.6: fixed grep -i int 0.55(2.06+0.64) 0.44(1.32+0.65) -20.0% 7821.7: basic grep -i int 0.59(2.10+0.67) 0.51(1.40+0.76) -13.6% 7821.8: extended grep -i int 0.56(2.08+0.67) 0.53(1.45+0.72) -5.4% 7821.9: perl grep -i int 0.58(2.12+0.59) 0.51(1.36+0.78) -12.1% 7821.11: fixed grep æ 0.30(1.34+0.40) 0.18(0.27+0.64) -40.0% 7821.12: basic grep æ 0.30(1.21+0.53) 0.18(0.31+0.59) -40.0% 7821.13: extended grep æ 0.30(1.30+0.44) 0.18(0.28+0.63) -40.0% 7821.14: perl grep æ 0.29(1.22+0.52) 0.18(0.33+0.57) -37.9% 7821.16: fixed grep -i æ 0.23(0.86+0.51) 0.18(0.27+0.63) -21.7% 7821.17: basic grep -i æ 0.23(0.86+0.50) 0.18(0.28+0.62) -21.7% 7821.18: extended grep -i æ 0.24(0.89+0.49) 0.18(0.28+0.62) -25.0% 7821.19: perl grep -i æ 0.22(0.80+0.48) 0.18(0.30+0.60) -18.2% Caveats & other things to mention: * This will expose PCRE v2 (as opposed to C library reg(comp|exec))to the network via gitweb in its default configuration. See <CACBZZX6V8qbnrZAdhRvPthy5Z91iEG8rrJ=Sf9tdkOt52M9j1Q@mail.gmail.com> for a discussion of security & other caveats related to that. * I'm checking for PCRE2_CONVERT_POSIX_BASIC to enable this, but the experimental API of pcre2_pattern_convert() may change before it makes it into a release. If we think this patch is awesome enough to get into a git release regardless, it should be guarded by some other method so we don't rudely tie upstream PCRE to this API least they break git versions in the wild. * One way to do to that would be to guard this via the USE_LIBPCRE2_BUNDLED flag, but see the above E-Mail thread for concerns about shipping an embedded PCRE, and for ways that could be made OK. * We could ship some copy of just the logic in pcre2_pattern_convert() & use the system PCRE instead. I haven't tried splitting it off from the PCRE codebase, and don't know how hard that would be. * There are outstanding bugs in the pcre2_pattern_convert() function. Grepping with -G and -E for all ASCII characters from 1..127 both "$char" and "\\$char" will produce numerous differences. These are mostly obscure cases, I'm working out fixes to those with Philip. 1. https://bugs.exim.org/show_bug.cgi?id=2106 Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
avar · May 29, 2017 · a3cc090 · a3cc090
1 parent 7dd367e
commit a3cc090
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Showing 5 changed files with 89 additions and 32 deletions.
diff --git a/grep.c b/grep.c
@@ -470,8 +470,47 @@ static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt
 	int options = PCRE2_MULTILINE;
 	const uint8_t *character_tables = NULL;
 	int jitret;
+	int icase = opt->regflags & REG_ICASE || p->ignore_case;
+	PCRE2_SPTR pattern = (PCRE2_SPTR)p->pattern;
+	PCRE2_SIZE length = p->patternlen;
+	int copied_pattern = 0;
+	struct strbuf pattern_sb = STRBUF_INIT;
+#ifdef PCRE2_CONVERT_POSIX_BASIC
+	int convret;
+	PCRE2_UCHAR *convpatbuf = NULL;
+	PCRE2_SIZE convpatlen;
+	int converted_pattern = 0;
+#endif
 
-	assert(opt->pcre2);
+	if (opt->fixed || has_null(p->pattern, p->patternlen) || is_fixed(p->pattern, p->patternlen)) {
+		if (icase)
+			strbuf_add(&pattern_sb, "(?i)", 4);
+		if (opt->fixed)
+			strbuf_add(&pattern_sb, "\\Q", 2);
+		strbuf_add(&pattern_sb, p->pattern, p->patternlen);
+		if (opt->fixed)
+			strbuf_add(&pattern_sb, "\\E", 2);
+
+		pattern = (PCRE2_SPTR)pattern_sb.buf;
+		length = pattern_sb.len;
+		copied_pattern = 1;
+	} else if (opt->pcre2_posix_emulation) {
+#ifdef PCRE2_CONVERT_POSIX_BASIC
+		convret = pcre2_pattern_convert(pattern, length,
+					       (opt->regflags & REG_EXTENDED
+						? PCRE2_CONVERT_POSIX_EXTENDED
+						: PCRE2_CONVERT_POSIX_BASIC),
+					       &convpatbuf, &convpatlen, NULL);
+		if (convret != 0) {
+			pcre2_get_error_message(convret, errbuf, sizeof(errbuf));
+			compile_regexp_failed(p, (const char *)&errbuf);
+		}
+		pattern = convpatbuf;
+		length = convpatlen;
+		converted_pattern = 1;
+#endif
+	} else
+		assert(opt->pcre2);
 
 	p->pcre2_compile_context = NULL;
 
@@ -486,11 +525,16 @@ static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt
 	if (is_utf8_locale() && has_non_ascii(p->pattern))
 		options |= PCRE2_UTF;
 
-	p->pcre2_pattern = pcre2_compile((PCRE2_SPTR)p->pattern,
-					 p->patternlen, options, &error, &erroffset,
-					 p->pcre2_compile_context);
+	p->pcre2_pattern = pcre2_compile(pattern, length, options, &error,
+					 &erroffset, p->pcre2_compile_context);
 
 	if (p->pcre2_pattern) {
+		if (copied_pattern)
+			strbuf_release(&pattern_sb);
+#ifdef PCRE2_CONVERT_POSIX_BASIC
+		if (converted_pattern)
+			pcre2_converted_pattern_free(convpatbuf);
+#endif
 		p->pcre2_match_data = pcre2_match_data_create_from_pattern(p->pcre2_pattern, NULL);
 		if (!p->pcre2_match_data)
 			die("Couldn't allocate PCRE2 match data");
@@ -582,7 +626,6 @@ static int pcre2match(struct grep_pat *p, const char *line, const char *eol,
 static void free_pcre2_pattern(struct grep_pat *p)
 {
 }
-#endif /* !USE_LIBPCRE2 */
 
 static void compile_fixed_regexp(struct grep_pat *p, struct grep_opt *opt)
 {
@@ -604,41 +647,21 @@ static void compile_fixed_regexp(struct grep_pat *p, struct grep_opt *opt)
 		compile_regexp_failed(p, errbuf);
 	}
 }
+#endif /* !USE_LIBPCRE2 */
 
 static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
 {
+#ifndef USE_LIBPCRE2
 	int icase, ascii_only;
+#endif
 	int err;
 
 	p->word_regexp = opt->word_regexp;
 	p->ignore_case = opt->ignore_case;
+#ifndef USE_LIBPCRE2
 	icase	       = opt->regflags & REG_ICASE || p->ignore_case;
 	ascii_only     = !has_non_ascii(p->pattern);
 
-#ifdef USE_LIBPCRE2
-	if (has_null(p->pattern, p->patternlen)) {
-		struct strbuf sb = STRBUF_INIT;
-		if (icase)
-			strbuf_add(&sb, "(?i)", 4);
-		if (opt->fixed)
-			strbuf_add(&sb, "\\Q", 2);		
-		strbuf_add(&sb, p->pattern, p->patternlen);
-		if (opt->fixed)
-			strbuf_add(&sb, "\\E", 2);
-
-		p->pattern = sb.buf;
-		p->patternlen = sb.len;
-
-		/* FIXME: Check in compile_pcre2_pattern() that we're
-		 * using basic rx using !opt->pcre2 && <something>
-		 */
-		opt->pcre2 = 1;
-
-		compile_pcre2_pattern(p, opt);
-		return;
-	}
-#endif
-
 	/*
 	 * Even when -F (fixed) asks us to do a non-regexp search, we
 	 * may not be able to correctly case-fold when -i
@@ -672,12 +695,26 @@ static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
 		compile_fixed_regexp(p, opt);
 		return;
 	}
+#endif
 
 	if (opt->pcre2) {
 		compile_pcre2_pattern(p, opt);
 		return;
 	}
 
+#ifdef USE_LIBPCRE2
+	if (opt->fixed || has_null(p->pattern, p->patternlen) || is_fixed(p->pattern, p->patternlen)) {
+		compile_pcre2_pattern(p, opt);
+		return;
+	}
+
+#ifdef PCRE2_CONVERT_POSIX_BASIC
+	opt->pcre2_posix_emulation = 1;
+	compile_pcre2_pattern(p, opt);
+	return;
+#endif
+#endif
+
 	if (opt->pcre1) {
 		compile_pcre1_regexp(p, opt);
 		return;
@@ -690,6 +727,7 @@ static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
 		regfree(&p->regexp);
 		compile_regexp_failed(p, errbuf);
 	}
+	return;
 }
 
 static struct grep_expr *compile_pattern_or(struct grep_pat **);

diff --git a/grep.h b/grep.h
@@ -29,6 +29,9 @@ typedef int pcre2_compile_context;
 typedef int pcre2_match_context;
 typedef int pcre2_jit_stack;
 #endif
+#ifndef PCRE2_CONVERT_POSIX_EXTENDED
+typedef int pcre2_convert_context;
+#endif
 #include "kwset.h"
 #include "thread-utils.h"
 #include "userdiff.h"
@@ -73,6 +76,7 @@ struct grep_pat {
 	pcre_jit_stack *pcre1_jit_stack;
 	const unsigned char *pcre1_tables;
 	int pcre1_jit_on;
+	pcre2_convert_context *pcre2_convert_context;
 	pcre2_code *pcre2_pattern;
 	pcre2_match_data *pcre2_match_data;
 	pcre2_compile_context *pcre2_compile_context;
@@ -143,6 +147,7 @@ struct grep_opt {
 	int use_reflog_filter;
 	int pcre1;
 	int pcre2;
+	int pcre2_posix_emulation;
 	int relative;
 	int pathname;
 	int null_following_name;

diff --git a/t/README b/t/README
@@ -820,6 +820,12 @@ use these, and "test_set_prereq" for how to define your own.
    USE_LIBPCRE2=YesPlease. Wrap any PCRE using tests that for some
    reason need v2 of the PCRE library instead of v1 in these.
 
+ - LIBPCRE2_BUNDLED
+
+   Git was compiled with the bundled PCRE v2 support via
+   USE_LIBPCRE2=YesPlease &
+   USE_LIBPCRE2_BUNDLED=IWantPatternConvertAwesomeSauce.
+
  - CASE_INSENSITIVE_FS
 
    Test is run on a case insensitive file system.

diff --git a/t/t7008-grep-binary.sh b/t/t7008-grep-binary.sh
@@ -100,9 +100,16 @@ test_expect_success 'git grep ile a' '
 	git grep ile a
 '
 
-test_expect_failure 'git grep .fi a' '
-	git grep .fi a
-'
+if test_have_prereq LIBPCRE2_BUNDLED
+then
+	test_expect_success 'git grep .fi a' '
+		git grep .fi a
+	'
+else
+	test_expect_failure 'git grep .fi a' '
+		git grep .fi a
+	'
+fi
 
 nul_match 1 '-F' 'yQf'
 nul_match 0 '-F' 'yQx'

diff --git a/t/test-lib.sh b/t/test-lib.sh
@@ -1018,6 +1018,7 @@ test -z "$NO_PYTHON" && test_set_prereq PYTHON
 test -n "$USE_LIBPCRE1$USE_LIBPCRE2" && test_set_prereq PCRE
 test -n "$USE_LIBPCRE1" && test_set_prereq LIBPCRE1
 test -n "$USE_LIBPCRE2" && test_set_prereq LIBPCRE2
+test -n "$USE_LIBPCRE2_BUNDLED" && test_set_prereq LIBPCRE2_BUNDLED
 test -z "$NO_GETTEXT" && test_set_prereq GETTEXT
 
 # Can we rely on git's output in the C locale?