https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117103
Bug ID: 117103
Summary: GCC trunk emits push + pop at -Oz when a mov could
suffice
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: dccitaliano at gmail dot com
Target Milestone: ---
Not a big deal, and maybe there are cases where it's not profitable, but I
found this while testing: https://clang.godbolt.org/z/6K18T1a7a
```
int f(int a, int b, int increment) {
int i = 0;
while (i < a) {
if (i % 2 == 0) {
i += 2;
} else {
i++;
}
}
int j = 0;
while (j < b) {
j += increment;
if (j > b / 2) {
j += 1;
}
}
return 0;
}
```
-Os emits:
mov ecx, 2
-Oz emits:
push 2
[...]
pop rcx
Another interesting (maybe?, not sure) bit is that the loop could be elided
entirely. I can file another bug if there's interest, or just reuse this one.
