https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115494
Bug ID: 115494
Summary: wrong code at -O{2,3} with "-fno-ssa-phiopt" on
x86_64-linux-gnu (the generated code hangs)
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 doesn't reproduce with 13.* and
earlier.
Compiler Explorer: https://godbolt.org/z/889EdEeE9
[627] % 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 20240614 (experimental) (GCC)
[628] %
[628] % gcctk -O2 small.c; ./a.out; echo $?
0
[629] % gcctk -O2 -fno-ssa-phiopt small.c; ./a.out; echo $?
1
[630] % cat small.c
unsigned char a;
int b = 1, c, d;
int main() {
char e;
c = b - c;
a = ~(c || a);
e = -(b ^ a);
d = e && b;
a = ~(b & a);
if (a < 2)
return 1;
return 0;
}
