This goes on top of the 29 patch series of "Easy to review grep &
pre-PCRE changes" ([ref];
https://public-inbox.org/git/20170511091829.5634-1-avarab@gmail.com/).

This could be split into 3 unrelated things, but I have think it's
probably easier for everyone to bundle these up, since they all go on
top of the other series. Comments below:

Ævar Arnfjörð Bjarmason (7):
  grep: don't redundantly compile throwaway patterns under threading
  grep: skip pthreads overhead when using one thread

Internal changes to grep to not redundantly spawn threads. No
functional changes, just internal cleanup.

  log: add -P as a synonym for --perl-regexp

Trivial change to add -P.

  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

I tested ancient versions of PCRE, which turned up build issues that
are fixed this time around.

  grep: add support for PCRE v2

The main point of this whole thing.

 Documentation/rev-list-options.txt |   1 +
 Makefile                           |  30 +++++--
 builtin/grep.c                     |  16 +++-
 configure.ac                       |  77 +++++++++++++---
 grep.c                             | 180 ++++++++++++++++++++++++++++++++++++-
 grep.h                             |  31 +++++++
 revision.c                         |   2 +-
 t/t4202-log.sh                     |  12 +++
 t/test-lib.sh                      |   2 +-
 9 files changed, 327 insertions(+), 24 deletions(-)

-- 
2.11.0