On Linux/x86_64,

6bbe931ea0e8f412c81fed8a3df4a07df97821f4 is the first bad commit
commit 6bbe931ea0e8f412c81fed8a3df4a07df97821f4
Author: Kyrylo Tkachov <[email protected]>
Date:   Fri Jun 12 00:00:00 2026 +0000

    match.pd: fold (0/1) * -(0/1) into -((0/1) & (0/1))

caused

FAIL: g++.dg/tree-ssa/mult-negate-zeroone-1.C  -std=gnu++20  scan-tree-dump-not 
optimized " * "
FAIL: g++.dg/tree-ssa/mult-negate-zeroone-1.C  -std=gnu++26  scan-tree-dump-not 
optimized " * "
FAIL: g++.dg/tree-ssa/mult-negate-zeroone-1.C  -std=gnu++98  scan-tree-dump-not 
optimized " * "

with GCC configured with

../../gcc/configure 
--prefix=/export/users3/haochenj/src/gcc-bisect/master/master/r17-1528/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="dg.exp=g++.dg/tree-ssa/mult-negate-zeroone-1.C 
--target_board='unix{-m32}'"
$ cd {build_dir}/gcc && make check 
RUNTESTFLAGS="dg.exp=g++.dg/tree-ssa/mult-negate-zeroone-1.C 
--target_board='unix{-m32\ -march=cascadelake}'"
$ cd {build_dir}/gcc && make check 
RUNTESTFLAGS="dg.exp=g++.dg/tree-ssa/mult-negate-zeroone-1.C 
--target_board='unix{-m64}'"
$ cd {build_dir}/gcc && make check 
RUNTESTFLAGS="dg.exp=g++.dg/tree-ssa/mult-negate-zeroone-1.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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