https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115568
Bug ID: 115568
Summary: wrong code at -O2 with "-fno-tree-sink -fno-tree-ter
-fschedule-insns" 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 regression from 11.*, and affects 12.* and later.
Compiler Explorer: https://godbolt.org/z/dT39sfGd6
[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 20240620 (experimental) (GCC)
[525] %
[525] % gcctk -O2 small.c; ./a.out
[526] %
[526] % gcctk -O2 -fno-tree-sink -fno-tree-ter -fschedule-insns small.c
[527] % ./a.out
Floating point exception
[528] %
[528] % cat small.c
int a, c, d = 1, e, f = 1, h, i, j;
unsigned b = 1, g;
int main() {
for (; h < 2; h++) {
int k = ~(b || 0), l = ((~e - j) ^ a % b) % k, m = (b ^ -1) + e;
unsigned o = ~a % ~1;
if (f) {
l = d;
m = 10;
i = e;
d = -(~e + b);
g = o % m;
e = -1;
n:
a = a % ~i;
b = ~k;
if (!g) {
b = e + o % -1;
continue;
}
if (!l)
break;
}
int q = (~d + g) << ~e, p = (~d - q) & a >> b;
unsigned s = ~((g & e) + (p | (b ^ (d + k))));
int r = (e & s) + p, u = d | ~a,
t = ((~(q + (~a + (s + e)))) & u) | (-g & (c << d ^ p));
if (t)
if (!r)
goto n;
g = m;
e = i;
}
return 0;
}
