[PATCH] D152798: [AMDGPU][ValueTracking] Handle amdgcn intrinsics that cannot create poison

[Jay Foad via Phabricator via llvm-commits]

foad added a comment.

>> I was wondering about that case myself. I don't see the benefit of saying that a load-like intrinsic can return poison, unless the compiler recognizes it as a load well enough to do things like forwarding a previously stored value through it.
>
> Not sure I follow. Do you want to define your load intrinsics are performing an implicit freeze? You could do that, but I'm not sure it is desirable.

I don't understand the big picture here: what possible benefit is there to telling the compiler that the value that is loaded can (or can't) be poison, when the compiler knows nothing else about the provenance of that value?

(By contrast, for a //normal// IR load, I can see that tracking the poison-ness of the loaded value might be useful, so that IR passes can add or remove store->load pairs without affecting poison-ness.)


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  https://reviews.llvm.org/D152798/new/

https://reviews.llvm.org/D152798