https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123048
Bug ID: 123048
Summary: wrong code at -O3 with -fschedule-insns on
x86_64-linux-gnu
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: zhendong.su at inf dot ethz.ch
Target Milestone: ---
Compiler Explorer: https://godbolt.org/z/jefb6TP74
Note:
- fails: trunk
- works: 15.2 and earlier
[515] % 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/16.0.0/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 16.0.0 20251208 (experimental) (GCC)
[516] %
[516] % gcctk -O3 small.c; ./a.out
[517] % gcctk -O3 -fschedule-insns small.c
[518] % ./a.out
Aborted
[519] % cat small.c
int a[] = {
4, 7, 5, 5, 54, 2044508324,
0, 4, 7, 4049, 8, 6,
4089016648, 4, 50548861, 3, 107580753, 9,
2, 6, 7, 5, 5, 7,
7073096, 6, 2, 2, 1006888145, 607687,
101629, 3, 901097722, 9000684, 6, 8065728,
1, 1, 705015759, 5, 0, 6,
4, 104598, 3, 1, 5, 3099436303,
4, 4, 30930, 70347812, 7, 5,
-1810856918, 907459465, 5, 3, 904427059, 2013776290,
6, 4, 0, 3, 3, 9,
7, 802195444, 6, 8001368, 4066508878, 70925,
3092731, 5, 706088902, 4, 2, 2,
1, 7, 3, 5, 303535960, 6,
7007092, 9037538, 70817, 1, 3, 4079995,
6, 6, 909243462, 6, 7, 7,
1, 708648649, 8, 6, 6048, 4,
909, 5, 10523913, 5, 4, 702138776,
0, 2, 504918807, 3, 3082640443, 9,
4, 6, 7068, 10842, 1, 70997,
3, 0, 4, 0, 2053790376, 90386,
2, 2050814, 5, 5, 0, 6,
2, 708143, 5, 3, 7, 604390888,
8, 2, 6, 5, 60999, 1068828381,
9, 0, 8, 906185462, 1090812512, 3,
9, 5, 1, 4, 60834842, 8085408,
6, 109, 8078467, 3, 400815, 2,
608, 4, 6, 5, 3, 1,
607071920, 0, 2, 40735498, 5, 1,
3087877, 908371, 4, 803740692, 2075208622, 2,
3, 90285, 2094854071, 1, 2029012, 0,
2, 0, 1, 5, 1, 7,
4, 200368, 4, 405801727, 5, 5,
1, 5067896, 608007406, 308918612, 8, 808555105};
int c, d, e, k, j[3] = {1,2}, *l;
unsigned h;
int n(int o, unsigned p) { return o >> 8 ^ a[(o ^ p) & 255]; }
int fn2(int o, int p) {
d = (o >> 8 & 16777215) ^ a[(o ^ p) & 255];
o = d;
o = n(o, p >> 8 & 255);
o = n(o, p >> 6);
c = o >> 8 ^ a[(o ^ 24) & 255];
return c;
}
int q(int o, int p, int r[], int s) {
unsigned b = -1;
int m, f;
m = -1 - o;
if (m + e)
goto ag;
do {
while (k)
;
for (int i = 0; i < 6; ++i)
h = fn2(h, l[i]);
} while (o);
ag:
f = -(1 % r[1]);
m = 1 / s;
int a[] = {o, p, r[0], r[1], r[2], f, m, s};
for (int i = 0; i < 8; i++)
b = fn2(b, a[i]);
return b;
}
int main() {
int g = q(-5, 1, j, 2);
if (g != 4639)
__builtin_abort();
return 0;
}
