Re: [PATCH v4 0/8] PCRE v2, PCRE v1 JIT, log -P & fixes

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

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Hi,

On Fri, 2 Jun 2017, Junio C Hamano wrote:

> Ævar Arnfjörð Bjarmason  <avarab@gmail.com> writes:
> 
> > See <20170525200528.22037-1-avarab@gmail.com> for v3
> > (https://public-inbox.org/git/20170525200528.22037-1-avarab@gmail.com/).
> >
> > This is on top of "[PATCH v4 00/31] Easy to review grep & pre-PCRE
> > changes".
> >
> > Changes:
> >
> > Ævar Arnfjörð Bjarmason (8):
> >   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
> >
> > No changes.
> >
> >   grep: un-break building with PCRE >= 8.32 without --enable-jit
> >
> > NEW: It turns out that a PCRE version that supports JIT, but is built
> > without JIT support will fail at link time since there's no
> > pcre_jit_exec symbol.
> >
> > It also turns out (contrary to what I claimed on list before, my
> > mistake) that there's no way to detect this through some macro. All
> > the pcre include files are the same with/without --enable-jit, only
> > the object file differs.
> >
> > So there's now a NO_LIBPCRE1_JIT flag to the Makefile, which is off by
> > default, but turned on on MinGW. I have not tested that
> > config.mak.uname change, but everything else I could test on Linux.
> >
> > The reason for why it's NO_LIBPCRE1_JIT not USE_LIBPCRE1_JIT is that
> > in practice pretty much everyone who builds pcre builds it with JIT
> > (I've looked through various Linux/BSD distro build files), it's MinGW
> > that's the exception here. Given the performance gain it makes sense
> > to make it the default.
> >
> >   grep: add support for PCRE v2
> >
> > Almost no changes, just:
> >
> >  * A trivial change to stop redundantly assigning to pcre2_jit_on,
> >    mistakenly left over from an earlier version.
> >
> >  * Updated commit message / perf numbers for the extra patches in the
> >    series both here and in v3.
> 
> Nicely summarised and matches what I received; thanks, will replace.

For the record: I spent the entire development time I had today on trying
to get PCRE2 to build and to figure out which PCRE2 tests fail and why.

I hoped to get to the bottom why the JIT is disabled in PCRE1, but ran out
of time.

I seem to have gotten PCRE2 to build and figured out why the tests failed
(spoiler: all of the failures were bogus and no indication of an
incorrectly-built PCRE2).

I barely had time to build `pu` (forcing PCRE2) and to run the test
scripts whose file names contain the substring "grep". Seems to work so
far, but this is by no means comprehensive testing; it is more like hushed
and rushed testing on a Friday night when I should have stopped working 10
minutes ago.

Will continue with testing Git for Windows using PCRE2 next week and keep
you posted,
Dscho