[llvm] [AMDGPU] Set glc/slc on volatile/nontemporal SMEM loads (PR #77443)

[Jay Foad via llvm-commits]

jayfoad wrote:

I think this makes sense by analogy with VMEM loads, but I'd appreciate a sanity check. @nhaehnle @perlfu @t-tye 

https://github.com/llvm/llvm-project/pull/77443