https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127596
Bug ID: 127596
Summary: wrong code at -O3 with "-fno-thread-jumps -ftracer
-fno-tree-forwprop" on x86_64-linux-gnu
Product: gcc
Version: 16.0
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: ---
Compiler Explorer: https://godbolt.org/z/c6rhnjMrz
Note:
- fails: 16.1 to trunk
- works: 15.3 and earlier
[580] % gcctk -v
Using built-in specs.
COLLECT_GCC=gcctk
COLLECT_LTO_WRAPPER=/local/home/suz/suz-local/software/local/gcc-trunk/bin/../libexec/gcc/x86_64-pc-linux-gnu/17.0.0/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++,lto --disable-werror
--disable-multilib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 17.0.0 20260924 (experimental) [master r17-1628-gd1c12591336] (GCC)
[581] %
[581] % gcctk -O3 small.c; ./a.out
[582] %
[582] % gcctk -O3 -fno-thread-jumps -ftracer -fno-tree-forwprop small.c
[583] % ./a.out
Aborted
[584] % cat small.c
short d = -7, k = -2586, l, n = -8, p = -1, q = -17829;
int m = -15, o, r;
int a(int s, int u) {
int e[256];
for (int f = 0; f < 256; ++f) {
unsigned c = f;
for (int g = 0; g < 8; ++g)
c = c & 1 ? c >> 1 ^ 3988292384 : c >> 1;
e[f] = c;
}
unsigned h = s;
int i = u;
for (int b = 0; b < 4; ++b) {
char ab = i;
i >>= 8;
h = h >> 8 ^ e[(h ^ ab) & 255];
}
return h;
}
void j(int s, int u) {
if (s != u)
__builtin_abort();
}
int t(char s, long u) {
int v = -244, w, *x, **ak;
x = &w;
ak = &x;
o = -524300;
do {
*x = 2146435073 - u;
if (~w != -3) {
do {
ak = &x + 2;
if (w)
goto ag;
*x = 0;
} while (0 < u - s);
}
if (!l) {
ag:
*ak = &v;
w = -2147483628;
}
} while (o < w);
r = a(0, m);
r = a(r, 12);
r = a(r, (long)((unsigned long)k << 48) >> 48);
r = a(r, (long)((unsigned long)d << 48) >> 48);
r = a(r, 0);
r = a(r, (long)((unsigned long)32768 << 48) >> 48);
r = a(r, v);
r = a(r, 1576633);
r = a(r, 39);
r = a(r, (long)((unsigned long)o << 40) >> 40);
r = a(r, 27);
r = a(r, 11085);
r = a(r, 19737);
r = a(r, (long)((unsigned long)q << 48) >> 48);
r = a(r, p);
r = a(r, (long)((unsigned long)n << 48) >> 48);
r = a(r, 18546);
r = a(r, 235);
r = a(r, w);
r = a(r, 0);
r = a(r, u);
r = a(r, 0);
r = a(r, 0);
r = a(r, 0);
r = a(r, *x);
r = a(r, 19737);
return r;
}
int main() {
int aj = t(0, 2146435071);
j(-965382002, aj);
return 0;
}
