Re: [r16-5975 Regression] FAIL: gcc.target/i386/pr90178.c scan-assembler-times xorl[\\t ]*\\%eax,[\\t ]*%eax 1 on Linux/x86_64

On Mon, Dec 8, 2025 at 9:00 PM Haochen Jiang <[email protected]> wrote:
>
> On Linux/x86_64,
>
> fae0c626250563c1619cc10c6af18a0c4cae5a97 is the first bad commit
> commit fae0c626250563c1619cc10c6af18a0c4cae5a97
> Author: Andrew Pinski <[email protected]>
> Date:   Sat Dec 6 01:11:29 2025 -0800
>
>     final_cleanup: Call make_forwarders_with_degenerate_phis [PR46555]
>
> caused
>
> FAIL: gcc.target/i386/pr90178.c scan-assembler-times xorl[\\t ]*\\%eax,[\\t ]*%eax 1
>
> with GCC configured with
>
> ../../gcc/configure --prefix=/export/users3/haochenj/src/gcc-bisect/master/master/r16-5975/usr --enable-clocale=gnu --with-system-zlib --with-demangler-in-ld --with-fpmath=sse --enable-languages=c,c++,fortran --enable-cet --without-isl --enable-libmpx x86_64-linux --disable-bootstrap
>
> To reproduce:
>
> $ cd {build_dir}/gcc && make check RUNTESTFLAGS="i386.exp=gcc.target/i386/pr90178.c --target_board='unix{-m32}'"
> $ cd {build_dir}/gcc && make check RUNTESTFLAGS="i386.exp=gcc.target/i386/pr90178.c --target_board='unix{-m32\ -march=cascadelake}'"

I filed https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123070 for the
failure but it looks like a RA issue of not allocating r101 to the
return register (EAX). I can't figure out why though.

Thanks,
Andrew

>
> (Please directly reply to this email for question about this report.)
> (If you met problems with cascadelake related, disabling AVX512F in command line might save that.)
> (However, please make sure that there is no potential problems with AVX512.)