https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122037
Bug ID: 122037
Summary: unused __builtin_stack_save (due to noreturn) is not
removed
Product: gcc
Version: 16.0
Status: UNCONFIRMED
Keywords: missed-optimization, TREE
Severity: enhancement
Priority: P3
Component: tree-optimization
Assignee: pinskia at gcc dot gnu.org
Reporter: pinskia at gcc dot gnu.org
Target Milestone: ---
Take:
```
void bar1 (char *, int) __attribute__((noreturn));
void foo1 (int size)
{
char temp[size];
temp[size-1] = '\0';
bar1 (temp, size);
}
```
Currently at .optimize we have:
```
__builtin_stack_save ();
_1 = (sizetype) size_6(D);
temp.1_8 = __builtin_alloca_with_align (_1, 8);
_2 = size_6(D) + -1;
(*temp.1_8)[_2] = 0;
bar1 (temp.1_8, size_6(D));
```
That __builtin_stack_save there can be removed.
This can be done in gimple-fold. Basically if the LHS does not exist on the
STACK_SAVE builtin, it can be turned into a NOP.
