Re: [r16-5526 Regression] FAIL: gcc.dg/vect/bb-slp-41.c scan-tree-dump-not slp1 "vectorizing stmts using SLP" on Linux/x86_64

Richard Biener via Gcc-regression <[email protected]>
Newsgroups gmane.comp.gcc.regression,gmane.comp.gcc.patches
Message-ID <CAFiYyc0Y6GZ+FoX9gX8W_VfucSxW0OsVdrpGoZyUjAmmdQP+mw@mail.gmail.com>
On Sun, Nov 23, 2025 at 9:21 AM Haochen Jiang <[email protected]> wrote:
>
> On Linux/x86_64,
>
> ed1911b9f1f1ab0c1b631f0b6427b798c7056200 is the first bad commit
> commit ed1911b9f1f1ab0c1b631f0b6427b798c7056200
> Author: Kugan Vivekanandarajah <[email protected]>
> Date:   Sun Nov 23 15:27:10 2025 +1100
>
>     [tree-optimization] Allow LICM to hoist loads in "self write" patterns
>
> caused
>
> FAIL: gcc.dg/vect/bb-slp-41.c -flto -ffat-lto-objects  scan-tree-dump-not slp1 "vectorizing stmts using SLP"
> FAIL: gcc.dg/vect/bb-slp-41.c scan-tree-dump-not slp1 "vectorizing stmts using SLP"

The vectorization done is sensible.  The testcase doesn't check was it
was intended to ...
we now SLP vectorize the scalar epilog we now unroll.  I can't guess
what we didn't want to
vectorize (some CTOR, obviously).  The testcase was added in
r10-4336-g818b3293f4545d.

I'll fix the testcase in the most reasonable way

Richard.



> with GCC configured with
>
> ../../gcc/configure --prefix=/export/users3/haochenj/src/gcc-bisect/master/master/r16-5526/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/bb-slp-41.c --target_board='unix{-m32}'"
> $ cd {build_dir}/gcc && make check RUNTESTFLAGS="vect.exp=gcc.dg/vect/bb-slp-41.c --target_board='unix{-m32\ -march=cascadelake}'"
> $ cd {build_dir}/gcc && make check RUNTESTFLAGS="vect.exp=gcc.dg/vect/bb-slp-41.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.)
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