https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110141
Bug ID: 110141
Summary: Wrong code at -O2 on x86_64-linux-gnu
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: shaohua.li at inf dot ethz.ch
Target Milestone: ---
For the following code, gcc since 12 emits the wrong code at -O2.
Compiler explorer: https://godbolt.org/z/reGo6jqGK
$ cat a.c
int printf(const char *, ...);
int h, i = 1, m;
int *j = &i, *k = &i, *l;
short n(short b, short c, int d) {
short e[] = {71, c, c, 40, 28, 57, 3, 8, 79, 19, c};
int f = d, a = b;
short *g = e;
while (f > 1) {
a += *g++;
f -= 2;
}
a += *g -= 255;
return a;
}
int fn2() {
h = 0;
for (;; h = 5) {
int o[4];
m = 0;
for (; m < 4; m++)
o[n(6, 7, 19) - 70 + m] = 6;
if (h) {
for (;;) {
int p = 0;
if (*k)
break;
l = &p;
}
*j = o[0];
return 0;
}
}
}
int main() {
fn2();
printf("%d\n", i);
}
$
$ gcc-tk -O0 a.c && ./a.out
6
$ gcc-tk -O2 a.c && ./a.out
0
$
