https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119594
Bug ID: 119594
Summary: wrong code at -Os with "-fno-dce -fno-tree-dce
-fno-tree-dse" 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 and doesn't reproduce with 14.2 and
earlier.
Compiler Explorer: https://godbolt.org/z/7ae57xhzP
[508] % 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 20250402 (experimental) (GCC)
[509] %
[509] % gcctk -Os small.c; ./a.out
[510] % gcctk -Os -fno-dce -fno-tree-dce -fno-tree-dse small.c
[511] % ./a.out
Aborted
[512] % cat small.c
int a, b;
static unsigned c = -1;
void d(int e) { a = a ^ e; }
void f(long e) { d(e >> 1); }
int main() {
int g[2], h = 0;
for (; h < 2; h++)
g[h] = -1;
for (; b; b++)
;
g[1] = 0;
f(c);
if (!a)
__builtin_abort();
return 0;
}
