bug#46256: [feature/native-comp] AOT eln files ignored if run from build tree

[Eli Zaretskii <eliz@gnu.org>]

> From: Andrea Corallo <akrl@sdf.org>
> Cc: Eli Zaretskii <eliz@gnu.org>, 46256@debbugs.gnu.org,
>         andrewjmoreton@gmail.com
> Date: Sat, 06 Mar 2021 19:48:53 +0000
> 
> > It's crashing for me with a Feb 15 build of libgccjit from gcc trunk,
> > but not with a newer build from gcc trunk, so it looks like a gcc bug
> > that has since been fixed.
> 
> I think what you see should be PR99126 [1] that was fixed recently on
> trunk.
> 
> IIRC (might be wrong) Eli is on a GCC 9, where at the time I could not
> reproduce this bug.

Yes, I'm using GCC 9.2.0.

> If we discover PR99126 shows-up in versions other than 10 we might
> want to relax the version check around the workaround we have in
> place.

It looks like that: I patched comp.c to take the workaround regardless
of the libgccjit version, and the result of running under GDB is:

  libgccjit.so: note: disable pass tree-isolate-paths for functions in the range of [0, 4294967295]
  [Inferior 1 (process 5640) exited normally]

It also completed much faster than the buggy version, which probably
means the buggy code has some kind of infinite recursion or other
issue that causes the run to be much more expensive.