[llvm] [AMDGPU] Account for aliasing reads in RewriteOutArguments (PR #209908)

[via llvm-commits]

================

----------------
robertvirany wrote:

The check expects the desired no-op behavior, but fails before the source change. Without the fix, the pass rewrites the callee to return a struct and moves the `%val` store after the load, which is the miscompile in #207969.

https://github.com/llvm/llvm-project/pull/209908