[llvm] [AMDGPU] GISelShouldIgnore .td uses (PR #90005)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> will need to examine them more closely; you mentioned some time back that it should be only for patterns applied to scalars, correct? This commit is surely more than that, so will make the next one more precise and include only those.

Nothing about scalars, it's about usage intent. I think there were some pseudos we bypass which we don't need the pattern. I haven't looked at the -warn-on-skipped patterns output in a while so I don't remember what the obvious cases are 

https://github.com/llvm/llvm-project/pull/90005