https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116414
Bug ID: 116414
Summary: Missed optimization: Branch elimination and memory
writes
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: madhur4127 at gmail dot com
Target Milestone: ---
Godbolt: https://godbolt.org/z/oKrGfh34z
Code:
```
#include <optional>
#include <cstdint>
std::optional<uint16_t> x(uint16_t x)
{ return x <= 1 ? std::nullopt : std::optional{x}; }
```
GCC trunk generates a branch and uses memory writes whereas it could just use
`eax` like clang
```
x(unsigned short):
cmp di, 1
jbe .L5
mov WORD PTR [rsp-4], di
mov BYTE PTR [rsp-2], 1
mov eax, DWORD PTR [rsp-4]
ret
.L5:
mov BYTE PTR [rsp-2], 0
mov eax, DWORD PTR [rsp-4]
ret
```
clang:
```
x(unsigned short):
xor eax, eax
cmp di, 2
setae al
shl eax, 16
or eax, edi
ret
```
