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

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

(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