Re: toolchain/58505: GCC 12.4.0 on alpha w/ isl broken at -O2

[Rin Okuyama <rokuyama.rk%gmail.com@localhost>]

The following reply was made to PR toolchain/58505; it has been noted by GNATS.

From: Rin Okuyama <rokuyama.rk%gmail.com@localhost>
To: gnats-bugs%netbsd.org@localhost, mrg%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
 netbsd-bugs%netbsd.org@localhost, tnn%nygren.pp.se@localhost
Cc: 
Subject: Re: toolchain/58505: GCC 12.4.0 on alpha w/ isl broken at -O2
Date: Sat, 3 Aug 2024 18:19:36 +0900

 (1) I've confirmed there's no regression for full ATF run on
 a system built by GCC 12.4 with isl disabled.
 
 On 2024/08/02 17:26, matthew green wrote:
  > can you try disabling the things that isl enables?  each alone
  > or in groups might be necessary to track better..  eg, these if
  > they're enabled:
  >
  > 	-ftree-loop-linear
  > 	-floop-strip-mine
  > 	-floop-block
  > 	-fgraphite-identity
  > 	-floop-nest-optimize
  > 	-floop-parallelize-all
  >
  > at worst, we can just disable isl for alpha.
 
 Unfortunately, I couldn't narrow down the problem :(
 
 (2) `cc -c test.c` succeeds even if all of these options specified, and
 (3) `cc -c -O2 test.c` fails even if all of these options disabled.
 
 On 2024/08/02 20:35, Tobias Nygren wrote:
 > > Rin Okuyama writes:
 > > > I've found this is due to isl
 > 
 > I guess isl-enabled GCC miscompiles parts of GCC. It does not
 > necessarily have to be just the isl code that gets miscompiled.
 
 I may misread your intention, but:
 
 (4) If isl is disabled **only for tools**, generated GCC 12.4 crashes
      when compiling test.c with -O2.
 
 Thanks,
 rin