[PATCH] D63420: AMDGPU: Fix s.buffer.load being marked as readnone

Mon Jun 17 05:55:59 PDT 2019

arsenm added a comment.

In D63420#1545917 <https://reviews.llvm.org/D63420#1545917>, @nhaehnle wrote:

> What does this actually fix?
>
> This is likely to pessimize codegen for graphics quite badly. Graphics APIs make fairly strong aliasing guarantees which we don't properly express in LLVM at the moment, and we kind of get by without it by having s.buffer.load be readnone.

When trying to do some global isel work, I ran into inconsistencies in the attributes (e.g. D63422 <https://reviews.llvm.org/D63422>), and I don't want to spread awareness of this hack to more places. We can't really fix this until we have fat pointers. I would rather have the declaration be accurate. If graphics users want to assume readnone as a performance hack until that is fixed, they can annotate every call site with readnone.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D63420/new/

https://reviews.llvm.org/D63420