https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116753
Bug ID: 116753
Summary: [regression from GCC 12.4] GCC trunk (-O3) can't fold
a loop into a constant
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: dccitaliano at gmail dot com
Target Milestone: ---
https://godbolt.org/z/xGh9vY57b
```
long patatino() {
long x = 0;
for (int i = 0; i < 5; ++i) {
while (x < 10) {
if (x % 2 == 0) {
x += 2;
} else {
x += 1;
}
// Dead while loop
while ((x > 20) && (i % 3 == 0) && (x % 5 == 0)) {
x -= 5;
}
// Dead while loop
while ((x < -5) && (i % 2 == 0) && (x % 3 == 0)) {
x += 3;
}
}
}
return x;
}
```
GCC trunk emits:
patatino():
mov eax, 2
.L2:
add rax, 2
cmp rax, 9
jle .L2
ret
GCC 12.4 emits:
patatino():
mov eax, 10
ret
