| Issue |
91292
|
| Summary |
Can `prefetchw`+`mov` to that location be folded to a `movnti`?
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
Validark
|
See title. Please pardon my ignorance on this topic but I am not really sure how to look up the answer to this kind of question.
I have this Zig code:
```zig
export fn movnti(dest: *u32, src: u32) void {
@prefetch(dest, .{ .rw = .write, .locality = 0 });
dest.* = src;
}
```
Here is the LLVM IR:
```llvm
define dso_local void @movnti(ptr nocapture nonnull align 4 %0, i32 %1) local_unnamed_addr {
Entry:
tail call void @llvm.prefetch.p0(ptr nonnull %0, i32 1, i32 0, i32 1)
store i32 %1, ptr %0, align 4
ret void
}
declare void @llvm.dbg.value(metadata, metadata, metadata) #1
declare void @llvm.prefetch.p0(ptr nocapture readonly, i32 immarg, i32 immarg, i32 immarg) #2
```
Currently turns into this on x86 Zen 3:
```asm
movnti:
prefetchw byte ptr [rdi]
mov dword ptr [rdi], esi
ret
```
My question is, could this be turned into a `movnti` instruction?
Thank you.
https://zig.godbolt.org/z/hffbv46vs
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