https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116420
Bug ID: 116420
Summary: wrong code at -O{2,3} with "-fno-forward-propagate
-fno-tree-ch" 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 doesn't reproduce with 14.* and
earlier.
Compiler Explorer: https://godbolt.org/z/zfssY8K95
[524] % 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 20240819 (experimental) (GCC)
[525] %
[525] % gcctk -O2 small.c; ./a.out
[526] %
[526] % gcctk -O2 -fno-forward-propagate -fno-tree-ch small.c
[527] % ./a.out
Aborted
[528] % cat small.c
int a, d, e;
char b = -1, c, f;
int main() {
int g;
for (; d < 1; d++) {
g = b;
for (; c; c = g)
;
}
f = g;
for (; e < 1; e++)
if (g >= a)
__builtin_abort();
return 0;
}
