https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118739
Bug ID: 118739
Summary: wrong code at -O{s,3} with "-fno-tree-forwprop
-fno-tree-vrp" 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 14.2 and
earlier.
Compiler Explorer: https://godbolt.org/z/b745bvYEx
[615] % 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/15.0.1/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 15.0.1 20250203 (experimental) (GCC)
[616] %
[616] % gcctk -O3 small.c; ./a.out
0
[617] % gcctk -O3 -fno-tree-forwprop -fno-tree-vrp small.c
[618] % ./a.out
0
Aborted
[619] % cat small.c
int printf(const char *, ...);
volatile int a;
int b, c, d = 1, e, f, g;
int h() {
int i = 1;
j:
for (b = 1; b; b--) {
printf("0\n");
g = 0;
for (; g <= 1; g++) {
int k = f = 0;
for (; f <= 1; f++)
k = (1 == i) >= k || ((d = 0) >= a) + k;
}
}
for (; i < 3; i++) {
if (!c)
return g;
if (e)
goto j;
printf("0\n");
}
return 0;
}
int main() {
h();
if (d != 1)
__builtin_abort();
return 0;
}
