https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111319
Bug ID: 111319
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: ---
The executable produced by gcc -O2 would crash. Not sure if there is UB in the
code or not as `h` has not been dereferenced after `h--`.
Compiler explorer: https://godbolt.org/z/avssssPze
$ cat a.c
int printf(const char *, ...);
int a, b = 5, c, d;
int e[2] = {0, 0};
int i() {
int f = 0;
int g[2] = {1, f};
int *h = g;
h--;
if (!b)
while (h >= &c == 1)
h--;
h++;
d = *h;
return d;
}
int main() {
if (e[i()])
e[0] = 0;
printf("%d\n", a);
}
$
$ gcc -O2 a.c && ./a.out
Segmentation fault
$
