[llvm] [AMDGPU] Allow shinking instruction with dead sdst (PR #68028)

[Jay Foad via llvm-commits]

jayfoad wrote:

If it does not affect GFX10+ then I have almost no interest in this patch :)

I have tried compiling our 10,000 graphics shaders for gfx900 and your patch makes absolutely no difference at all to the generated code, which seems odd.

https://github.com/llvm/llvm-project/pull/68028