| Issue |
180991
|
| Summary |
dead stack stores after expand-memcmp
|
| Labels |
llvm:codegen,
missed-optimization
|
| Assignees |
|
| Reporter |
nickdesaulniers
|
https://codingmarginalia.blogspot.com/2026/02/both-gcc-and-clang-generate.html mentions that
```c++
#include <array>
static constexpr int arraySize = 1;
bool isAllZeros (const std::array<int, arraySize> &array) {
std::array<int, arraySize> allZeros {};
return array == allZeros;
}
```
produces a dead store to the stack for optimized builds:
```asm
isAllZeros: # @isAllZeros
movq $0, -8(%rsp)
cmpq $0, (%rdi)
sete %al
retq
```
I wonder if `expand-memcmp` should be doing a round of load-store forwarding?
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