https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121704
Bug ID: 121704
Summary: wrong code at -O3 with "-fno-gcse -fno-ipa-cp" 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: ---
Compiler Explorer: https://godbolt.org/z/T9f835368
Note:
- works: 13.* and earlier
- fails: 14.1 and later
- -fno-tree-slsr and -fno-ivopts do not make it disappear
[514] % 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 20250828 (experimental) (GCC)
[515] %
[515] % gcctk -O3 small.c; ./a.out
[516] % gcctk -O3 -fno-gcse -fno-ipa-cp small.c
[517] % ./a.out
Segmentation fault
[518] %
[518] % cat small.c
int a[] = {
0, 4, 8, 4, 124634137, 5,
5, 5, 4, 2044508324, 0, 4,
5, 1, 7, 2428444049, 498536548, 6,
4089016648, 4, 50548861, 1843258603, 107580753, 2211677639,
5883990, 2, 2, 6, 335633487, 5,
5, 7, 7073096, 1281953886, 2, 2724688242,
1006888145, 1258607687, 3524101629, 3, 901097722, 1119000684,
6, 8065728, 1, 1172266101, 705015759, 5,
651767980, 1373503546, 4, 104598, 3, 1,
5, 3099436303, 4, 4, 3322730930, 2970347812,
795835527, 1483230225, 5, 3060149565, 2, 31158534,
2563907772, 4023717930, 907459465, 5, 3, 904427059,
2013776290, 251722036, 4, 0, 3, 3,
439277719, 7, 802195444, 6, 8001368, 4066508878,
70925, 3092731, 2181625025, 4111451223, 706088902, 314042704,
2344532202, 2, 1658658271, 7, 2362670323, 5,
303535960, 6, 7007092, 3569037538, 70817, 1037604311,
3, 3554079995, 6, 79679996, 909243462, 3663771856,
1141124467, 7, 1, 3708648649, 8, 6,
3188396048, 4, 909, 5, 3110523913, 3462522015,
4, 702138776, 2966460450, 3352799412, 1504918807, 783551873,
3082640443, 3233442989, 4, 6, 7068, 10842,
5, 1, 70997, 3, 0, 2489596804,
225274430, 2053790376, 5, 3, 3, 2097651377,
4027552580, 90386, 2, 1762050814, 5, 5,
5, 507879, 4275313526, 0, 282753626, 2,
708143, 2394877945, 397917763, 7, 604390888, 2714866558,
2, 6, 5, 60999, 1068828381, 9,
3624741850, 8, 906185462, 1090812512, 3, 9,
5, 1181335161, 4, 60834842, 8085408, 1382605366,
109, 3138078467, 3, 400815, 3317316542, 608,
733239954, 6, 1, 5, 3, 1,
607071920, 3965973030, 2, 40735498, 2617837225, 1,
1913087877, 83908371, 2512341634, 803740692, 2075208622, 2,
3, 3855990285, 2094854071, 198958881, 2262029012, 0,
1759359992, 534414190, 1, 4139329115, 1, 414664567,
4, 4279200368, 1684554, 6, 2405801727, 5,
5, 1, 5067896, 3608007406, 308918612, 8,
808555105, 3, 1, 5, 59818, 3654703836,
1088359270, 0, 9, 3736837829, 202900863, 817233897,
108, 0, 1404277552, 0, 207493, 3,
9, 1, 3009837614, 3294710456, 6, 4,
3020668471, 5, 510334235, 755167117};
int b, c, d, e, f;
int g(int h, char k) { return (h >> 8 & 16777215) ^ a[(h ^ k) & 255]; }
int l(int h, int k[]) {
int j = 4294967295, i = 0;
for (; i < h; ++i) {
b = (j >> 8 & 16777215) ^ a[(j ^ k[i]) & 255];
c = b;
c = g(c, k[i] >> 8);
c = g(c, k[i] >> 6);
c = g(c, k[i] >> 4);
j = c;
}
j = j ^ 4294967295;
return j;
}
int m(volatile int h[], int k, volatile int n[][1], int o, int p, int q,
int r[][3], int s[][1], volatile int t) {
d = p + 5;
e = 5 / t - 1;
s[2][0] = -2;
if (e)
h[1] = -(1 % n[2][0]) + 1;
p = 1 - o;
n[2][0] = 1 - s[0][0] - r[1][2];
return l(25, (int[]){h[0], h[1], k, n[0][0], n[1][0],
n[2][0], o, p, q, r[0][0],
r[0][1], r[0][2], r[1][0], r[1][1], r[1][2],
r[2][0], r[2][1], r[2][2], s[0][0], s[1][0],
s[2][0], 0, d, e, t});
}
void u(volatile int h[][1]) {
f = -1;
do {
m((int[]){1, 1}, 1, (int(*)[])(int[]){1, 1, 2}, 1, 2, 1,
(int(*)[])(int[9]){1}, (int(*)[])(int[]){2, 1, 1}, -2) -
h[m((int[]){-1, 1}, -1, (int(*)[])(int[]){-1, -1, 2}, -1, -2, -1,
(int(*)[])(int[]){-1, -1, -1, -1, -1, -1, -1, -1, -1},
(int(*)[])(int[]){-2, -1, 1}, -2) -
1316653008][0];
} while (m((int[]){1, 1}, 1, (int(*)[])(int[]){1, 1, 2}, 1, 2, 1,
(int(*)[])(int[9]){1}, (int(*)[])(int[]){2, 1, 1}, 2) /
f < 0);
}
int main() { u((int(*)[])(int[]){0}); }
