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

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.

 Documentation/rev-list-options.txt |   1 +
 Makefile                           |  49 ++++++++--
 builtin/grep.c                     |  16 +++-
 config.mak.uname                   |   1 +
 configure.ac                       |  77 ++++++++++++---
 grep.c                             | 185 ++++++++++++++++++++++++++++++++++++-
 grep.h                             |  33 +++++++
 revision.c                         |   2 +-
 t/t4202-log.sh                     |  12 +++
 t/test-lib.sh                      |   2 +-
 10 files changed, 349 insertions(+), 29 deletions(-)