Re: undefined reference to `pcre_jit_exec'

From: Jeffrey Walton <noloader@gmail.com>
Date: Oct 12, 2017, 21:00 UTC
Message-ID: <CAH8yC8kSpON5UP=pfsGXQ9JhhZOHVPetFHbr0BqBPnoYzj4Hog@mail.gmail.com>
In-Reply-To: <20171012203832.ui52j7cdrztc6vhs@sigill.intra.peff.net>

On Thu, Oct 12, 2017 at 4:38 PM, Jeff King <peff@peff.net> wrote:

Show 18 quoted lines

> On Thu, Oct 12, 2017 at 04:34:38PM -0400, Jeffrey Walton wrote:
>
>> > It looks like autoconf turns on USE_LIBPCRE1, but isn't smart enough to
>> > test NO_LIBPCRE1_JIT.
>>
>> If Git wants Jit, then I am inclined to configure PCRE to provide it.
>
> It does make things faster. OTOH, we lived for many years without it, so
> certainly it's not the end of the world to build without it.
>
> There are some numbers in the commit message of fbaceaac47 (grep: add
> support for the PCRE v1 JIT API, 2017-05-25).
>
>> A quick question if you happen to know... Does PCRE Jit cause a loss
>> of NX-stacks? If it causes a loss of NX-stacks, then I think I prefer
>> to disable it.
>
> I don't know. Ævar (cc'd) might.

Thanks. Building PCRE with Jit enabled results in:

$ readelf -l /usr/local/libexec/git-core/git-credential-re| grep -i -A1 stack
  GNU_STACK      0x0000000000000000 0x0000000000000000 0x0000000000000000
                 0x0000000000000000 0x0000000000000000  RW     10

So it looks like the NX-stacks were not lost.

Thanks again.

Jeff