On Tue, 2025-10-21 at 02:22 +0000, Jiang, Haochen wrote:
> On Linux/x86_64,
> 
> 6883d51304f1aa852da3f2b4eb26bdf2e12bbcb9 is the first bad commit
> commit 6883d51304f1aa852da3f2b4eb26bdf2e12bbcb9
> Author: Avinash Jayakar <[email protected]>
> Date:   Fri Oct 17 12:38:59 2025 +0530
> 
>     vect: Add pattern recognition for vectorizing
> {FLOOR,CEIL,ROUND}_{MOD, DIV}_EXPR
> 
> caused
> 
> FAIL: gcc.dg/vect/pr104116-ceil-umod-2.c -flto -ffat-lto-objects 
> scan-tree-dump-times vect "optimized: loop vectorized" 1
> FAIL: gcc.dg/vect/pr104116-ceil-umod-2.c scan-tree-dump-times vect
> "optimized: loop vectorized" 1
> FAIL: gcc.dg/vect/pr104116-ceil-umod-pow2.c -flto -ffat-lto-objects 
> scan-tree-dump-times vect "optimized: loop vectorized" 1
> FAIL: gcc.dg/vect/pr104116-ceil-umod-pow2.c scan-tree-dump-times vect
> "optimized: loop vectorized" 1
> FAIL: gcc.dg/vect/pr104116-round-umod-2.c -flto -ffat-lto-objects 
> scan-tree-dump-times vect "optimized: loop vectorized" 1
> FAIL: gcc.dg/vect/pr104116-round-umod-2.c scan-tree-dump-times vect
> "optimized: loop vectorized" 1
> 
> with GCC configured with
> 
> ../../gcc/configure --prefix=/export/users3/haochenj/src/gcc-
> bisect/master/master/r16-4464/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/pr104116-ceil-umod-2.c --
> target_board='unix{-m32\ -march=cascadelake}'"
> $ cd {build_dir}/gcc && make check
> RUNTESTFLAGS="vect.exp=gcc.dg/vect/pr104116-ceil-umod-2.c --
> target_board='unix{-m64\ -march=cascadelake}'"
> $ cd {build_dir}/gcc && make check
> RUNTESTFLAGS="vect.exp=gcc.dg/vect/pr104116-ceil-umod-pow2.c --
> target_board='unix{-m32\ -march=cascadelake}'"
> $ cd {build_dir}/gcc && make check
> RUNTESTFLAGS="vect.exp=gcc.dg/vect/pr104116-ceil-umod-pow2.c --
> target_board='unix{-m64\ -march=cascadelake}'"
> $ cd {build_dir}/gcc && make check
> RUNTESTFLAGS="vect.exp=gcc.dg/vect/pr104116-round-umod-2.c --
> target_board='unix{-m32\ -march=cascadelake}'"
> $ cd {build_dir}/gcc && make check
> RUNTESTFLAGS="vect.exp=gcc.dg/vect/pr104116-round-umod-2.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.)


Looks like an extra loop is also vectorized, I will disable
optimization for all those loops and send a patch. 
aarch64 also has similar failure:
https://linaro.atlassian.net/browse/GNU-1707

Thanks,
Avinash

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