https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115092
Bug ID: 115092
Summary: wrong code at -O1 with "-fgcse -ftree-pre
-fno-tree-dominator-opts -fno-tree-fre
-fno-guess-branch-probability" on x86_64-linux-gnu
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: zhendong.su at inf dot ethz.ch
Target Milestone: ---
It appears to be a recent regression as it only reproduces with 14.1 and trunk,
but not 13.* and earlier. It needs several flags, but hope it's still of
interest.
Compiler Explorer: https://godbolt.org/z/qTc3e6s7f
[521] % gcctk -v
Using built-in specs.
COLLECT_GCC=gcctk
COLLECT_LTO_WRAPPER=/local/suz-local/software/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/15.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-trunk/configure --disable-bootstrap
--enable-checking=yes --prefix=/local/suz-local/software/local/gcc-trunk
--enable-sanitizers --enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 15.0.0 20240514 (experimental) (GCC)
[522] %
[522] % gcctk -O1 small.c; ./a.out
[523] %
[523] % gcctk -O1 -fgcse -ftree-pre -fno-tree-dominator-opts -fno-tree-fre
-fno-guess-branch-probability small.c
[524] % ./a.out
Floating point exception
[525] %
[525] % cat small.c
int a, b, c = 1, d, e;
int main() {
int f, g = a;
b = -2;
f = -(1 >> ((c && b) & ~a));
if (f <= b)
d = g / e;
return 0;
}
