https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122933
Bug ID: 122933
Summary: invalid epilogue for x86_64-w64-mingw32
Product: gcc
Version: 16.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: lh_mouse at 126 dot com
Target Milestone: ---
```
// x86_64-w64-mingw32-g++ test.cpp -O2 -S -masm=intel
void
something_that_may_throw(void*);
int
test()
{
char large[500];
something_that_may_throw(large);
return 42;
}
```
```
.seh_proc "_Z4testv"
"_Z4testv":
.LFB0:
lea rsp, -552[rsp]
.seh_stackalloc 552
.seh_endprologue
lea rcx, 32[rsp]
call "_Z24something_that_may_throwPv"
mov eax, 42
lea rsp, 552[rsp] # <==== not allowed in epilogue
ret
.seh_endproc
```
Using LEA with RSP as the base pointer is prohibited; it must be `add rsp,
552`. Only LEA with RBP is allowed.
(https://learn.microsoft.com/en-us/cpp/build/prolog-and-epilog?view=msvc-170#epilog-code)
> When a frame pointer is not used, the epilog must use `add RSP,constant`
> to deallocate the fixed part of the stack. It may not use
> `lea RSP,constant[RSP]` instead. This restriction exists so the unwind
> code has fewer patterns to recognize when searching for epilogs.
