Re: [PATCH] tree-vect.h: Compile check_vect with -O0

On Fri, Aug 7, 2026 at 6:12 AM H.J. Lu <[email protected]> wrote:
>
> commit 44cc8e5718efd0cc1ef57c68052dbe33b047f158
> Author: Ewan <[email protected]>
> Date:   Tue Mar 17 16:12:15 2026 +0800
>
>     i386: Fix __get_cpuid() and __get_cpuid_count() for
> Centaur/Zhaoxin CPUID range
>
> caused many regressions, like
>
> FAIL: gcc.dg/vect/vect-100.c scan-tree-dump-not optimized "Invalid sum"
>
> on Linux/x86-64 with -m32.  The commit above changed __get_cpuid_count
> which is used by check_vect in tree-vect.h.  When GCC tried to vectorize
> check_vect, it outputted
>
> __attribute__((noinline))
> void check_vect ()
> {
> ...
> ;;   Invalid sum of incoming counts 966367640 (estimated locally, freq
> 0.9000), should be 719407024 (estimated locally, freq 0.6700)
>
> which failed
>
> /* { dg-final { scan-tree-dump-not "Invalid sum" "optimized" } } */
>
> Compile check_vect with -O0 to avoid it.
>
> * gcc.dg/vect/tree-vect.h (check_vect): Compile with -O0.
>
>
> --
> H.J.

This fixes:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126697

-- 
H.J.