Re: [r17-2737 Regression] FAIL: gcc.dg/vect/vect-pr126404.c (test for excess errors) on Linux/x86_64

On Tue, 28 Jul 2026, Haochen Jiang wrote:

> On Linux/x86_64,
> 
> 3cd23c9fd60854cd9d160ce3b341a819025bfeb8 is the first bad commit
> commit 3cd23c9fd60854cd9d160ce3b341a819025bfeb8
> Author: Richard Biener <[email protected]>
> Date:   Mon Jul 27 19:24:32 2026 +0200
> 
>     tree-optimization/126404 - fixup conversion detection in reductions
> 
> caused
> 
> FAIL: gcc.dg/vect/vect-pr126404.c -flto -ffat-lto-objects (internal compiler error: in vect_build_slp_tree_2, at tree-vect-slp.cc:2928)
> FAIL: gcc.dg/vect/vect-pr126404.c -flto -ffat-lto-objects (test for excess errors)
> FAIL: gcc.dg/vect/vect-pr126404.c (internal compiler error: in vect_build_slp_tree_2, at tree-vect-slp.cc:2928)
> FAIL: gcc.dg/vect/vect-pr126404.c (test for excess errors)

It uncovered a latent issue.  I'm testing a fix.

Richard.

> with GCC configured with
> 
> ../../gcc/configure --prefix=/export/users3/haochenj/src/gcc-bisect/master/master/r17-2737/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="vect.exp=gcc.dg/vect/vect-pr126404.c --target_board='unix{-m32\ -march=cascadelake}'"
> $ cd {build_dir}/gcc && make check RUNTESTFLAGS="vect.exp=gcc.dg/vect/vect-pr126404.c --target_board='unix{-m64\ -march=cascadelake}'"
> 
> (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.)
> 

-- 
Richard Biener <[email protected]>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Jochen Jaser, Andrew McDonald, Abhinav Puri; (HRB 36809, AG Nuernberg)