From: Junio C Hamano <gitster@pobox.com>
To: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Cc: git@vger.kernel.org, "Jeff King" <peff@peff.net>,
"Jeffrey Walton" <noloader@gmail.com>,
"Michał Kiedrowicz" <michal.kiedrowicz@gmail.com>,
"J Smith" <dark.panda@gmail.com>,
"Victor Leschuk" <vleschuk@gmail.com>,
"Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>,
"Fredrik Kuivinen" <frekui@gmail.com>,
"Brandon Williams" <bmwill@google.com>,
"Stefan Beller" <sbeller@google.com>,
"Johannes Schindelin" <johannes.schindelin@gmx.de>,
"Simon Ruderich" <simon@ruderich.org>
Subject: Re: [PATCH v2 4/7] grep: add support for the PCRE v1 JIT API
Date: Wed, 24 May 2017 14:17:11 +0900 [thread overview]
Message-ID: <xmqqlgpmhm08.fsf@gitster.mtv.corp.google.com> (raw)
In-Reply-To: <20170523192453.14172-5-avarab@gmail.com> ("Ævar Arnfjörð Bjarmason"'s message of "Tue, 23 May 2017 19:24:50 +0000")
Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:
> diff --git a/grep.c b/grep.c
> index 1157529115..49e9aed457 100644
> --- a/grep.c
> +++ b/grep.c
> @@ -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
Is "canjit" a property purely of the library (e.g. version and
compilation option), or of combination of that and nature of the
pattern, or something else like the memory pressure?
I am wondering if it is worth doing something like this:
static int canjit = -1;
if (canjit < 0) {
pcre_config(PCRE_CONFIG_JIT, &canjit);
}
if it depends purely on the library linked to the process.
> @@ -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");
I agree that dying is OK, but as far as I can tell, this is not a
BUG (there is no error a programmer can correct by a follow-up
patch); please do not mark it as such (it is likely that we'll later
do a tree-wide s/die("BUG:/BUG("/ and this will interfere).
> + pcre_assign_jit_stack(p->pcre1_extra_info, NULL, p->pcre1_jit_stack);
> + p->pcre1_jit_on = 1;
Contrary to what I wondered about "canjit" above, I think it makes
tons of sense to contain the "is JIT in use?" information in "struct
grep_pat" and not rely on any global state. Not that we are likely
to want to be able to JIT some patterns while not doing others. So
I agree with the design choice of adding pcre1_jit_on field to the
structure.
But then, wouldn't it make more sense to do all of the above without
the canjit variable at all? i.e. something like...
#ifdef PCRE_CONFIG_JIT
pcre_config(PCRE_CONFIG_JIT, &p->pcre1_jit_on);
if (p->pcre1_jit_on)
... stack thing ...
#else
p->pcre1_jit_on = 0;
#endif
> +#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);
It is very thoughtful to add a blank line here (and you did the same
in another similar hunk), but I have a feeling that it is still a
bit too subtle a hint to signal to the readers that these two
pcre_free()s fire differently, i.e. the former does not fire if jit
is on but the latter always fires.
Would this be a bit safer while being not too ugly to live, I wonder?
#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);
Thanks.
next prev parent reply other threads:[~2017-05-24 5:17 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-20 21:42 [PATCH v3 00/30] Easy to review grep & pre-PCRE changes Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 01/30] Makefile & configure: reword inaccurate comment about PCRE Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 02/30] grep & rev-list doc: stop promising libpcre for --perl-regexp Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 03/30] test-lib: rename the LIBPCRE prerequisite to PCRE Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 04/30] log: add exhaustive tests for pattern style options & config Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 05/30] log: make --regexp-ignore-case work with --perl-regexp Ævar Arnfjörð Bjarmason
2017-05-20 23:50 ` Junio C Hamano
2017-05-21 6:58 ` Ævar Arnfjörð Bjarmason
2017-05-22 0:17 ` Junio C Hamano
2017-06-28 21:58 ` [PATCH 0/5] grep: remove redundant code & reflags from API Ævar Arnfjörð Bjarmason
2017-06-29 22:22 ` [PATCH v2 0/6] " Ævar Arnfjörð Bjarmason
2017-06-29 22:22 ` [PATCH v2 1/6] grep: remove redundant double assignment to 0 Ævar Arnfjörð Bjarmason
2017-06-29 22:22 ` [PATCH v2 2/6] grep: adjust a redundant grep pattern type assignment Ævar Arnfjörð Bjarmason
2017-06-29 22:22 ` [PATCH v2 3/6] grep: remove redundant "fixed" field re-assignment to 0 Ævar Arnfjörð Bjarmason
2017-06-29 22:22 ` [PATCH v2 4/6] grep: remove redundant and verbose re-assignments " Ævar Arnfjörð Bjarmason
2017-06-29 22:22 ` [PATCH v2 5/6] grep: remove regflags from the public grep_opt API Ævar Arnfjörð Bjarmason
2017-06-30 17:20 ` Junio C Hamano
2017-06-29 22:22 ` [PATCH v2 6/6] grep: remove redundant REG_NEWLINE when compiling fixed regex Ævar Arnfjörð Bjarmason
2017-06-28 21:58 ` [PATCH 1/5] grep: remove redundant double assignment to 0 Ævar Arnfjörð Bjarmason
2017-06-28 21:58 ` [PATCH 2/5] grep: remove redundant grep pattern type assignment Ævar Arnfjörð Bjarmason
2017-06-29 17:03 ` Stefan Beller
2017-06-29 17:50 ` Ævar Arnfjörð Bjarmason
2017-06-28 21:58 ` [PATCH 3/5] grep: remove redundant "fixed" field re-assignment to 0 Ævar Arnfjörð Bjarmason
2017-06-29 17:10 ` Stefan Beller
2017-06-28 21:58 ` [PATCH 4/5] grep: remove redundant and verbose re-assignments " Ævar Arnfjörð Bjarmason
2017-06-28 21:58 ` [PATCH 5/5] grep: remove regflags from the public grep_opt API Ævar Arnfjörð Bjarmason
2017-06-29 17:43 ` Stefan Beller
2017-06-29 18:16 ` Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 06/30] grep: add a test asserting that --perl-regexp dies when !PCRE Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 07/30] grep: add a test for backreferences in PCRE patterns Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 08/30] grep: change non-ASCII -i test to stop using --debug Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 09/30] grep: add tests for --threads=N and grep.threads Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 10/30] grep: amend submodule recursion test for regex engine testing Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 11/30] grep: add tests for grep pattern types being passed to submodules Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 12/30] grep: add a test helper function for less verbose -f \0 tests Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 13/30] grep: prepare for testing binary regexes containing rx metacharacters Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 14/30] grep: add tests to fix blind spots with \0 patterns Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 15/30] perf: add a GIT_PERF_MAKE_COMMAND for when *_MAKE_OPTS won't do Ævar Arnfjörð Bjarmason
2017-05-20 23:50 ` Junio C Hamano
2017-05-21 6:23 ` Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 16/30] perf: emit progress output when unpacking & building Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 17/30] perf: add a comparison test of grep regex engines Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 18/30] perf: add a comparison test of grep regex engines with -F Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 19/30] perf: add a comparison test of log --grep regex engines Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 20/30] grep: catch a missing enum in switch statement Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 21/30] grep: remove redundant regflags assignments Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 22/30] grep: factor test for \0 in grep patterns into a function Ævar Arnfjörð Bjarmason
2017-05-23 21:17 ` Brandon Williams
2017-05-20 21:42 ` [PATCH v3 23/30] grep: change the internal PCRE macro names to be PCRE1 Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 24/30] grep: change internal *pcre* variable & function names to be *pcre1* Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 25/30] grep: move is_fixed() earlier to avoid forward declaration Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 26/30] test-lib: add a PTHREADS prerequisite Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 27/30] pack-objects & index-pack: add test for --threads warning Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 28/30] pack-objects: fix buggy warning about threads Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 29/30] grep: given --threads with NO_PTHREADS=YesPlease, warn Ævar Arnfjörð Bjarmason
2017-05-20 21:42 ` [PATCH v3 30/30] grep: assert that threading is enabled when calling grep_{lock,unlock} Ævar Arnfjörð Bjarmason
2017-05-20 23:50 ` [PATCH v3 00/30] Easy to review grep & pre-PCRE changes Junio C Hamano
2017-05-23 19:24 ` [PATCH v2 0/7] PCRE v2, PCRE v1 JIT, log -P & fixes Ævar Arnfjörð Bjarmason
2017-05-23 19:24 ` [PATCH v2 1/7] grep: don't redundantly compile throwaway patterns under threading Ævar Arnfjörð Bjarmason
2017-05-24 4:42 ` Junio C Hamano
2017-05-25 10:33 ` Ævar Arnfjörð Bjarmason
2017-05-26 0:58 ` Junio C Hamano
2017-05-26 8:06 ` Ævar Arnfjörð Bjarmason
2017-05-26 9:49 ` Junio C Hamano
2017-05-23 19:24 ` [PATCH v2 2/7] grep: skip pthreads overhead when using one thread Ævar Arnfjörð Bjarmason
2017-05-24 4:45 ` Junio C Hamano
2017-05-23 19:24 ` [PATCH v2 3/7] log: add -P as a synonym for --perl-regexp Ævar Arnfjörð Bjarmason
2017-05-23 19:24 ` [PATCH v2 4/7] grep: add support for the PCRE v1 JIT API Ævar Arnfjörð Bjarmason
2017-05-24 5:17 ` Junio C Hamano [this message]
2017-05-24 7:37 ` Ævar Arnfjörð Bjarmason
2017-05-23 19:24 ` [PATCH v2 5/7] grep: un-break building with PCRE < 8.32 Ævar Arnfjörð Bjarmason
2017-05-24 6:00 ` Junio C Hamano
2017-05-24 6:38 ` Junio C Hamano
2017-05-23 19:24 ` [PATCH v2 6/7] grep: un-break building with PCRE < 8.20 Ævar Arnfjörð Bjarmason
2017-05-23 19:24 ` [PATCH v2 7/7] grep: add support for PCRE v2 Ævar Arnfjörð Bjarmason
2017-05-24 6:23 ` Junio C Hamano
2017-05-25 9:49 ` Ævar Arnfjörð Bjarmason
-- strict thread matches above, loose matches on Subject: below --
2017-05-13 23:45 [PATCH v2 0/7] PCRE v2, PCRE v1 JIT, log -P & fixes Ævar Arnfjörð Bjarmason
2017-05-13 23:45 ` [PATCH v2 4/7] grep: add support for the PCRE v1 JIT API Ævar Arnfjörð Bjarmason
2017-05-14 14:43 ` Simon Ruderich
2017-05-14 15:10 ` Ævar Arnfjörð Bjarmason
2017-05-14 15:23 ` Ævar Arnfjörð Bjarmason
2017-05-15 2:43 ` Junio C Hamano
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