[llvm] [AMDGPU] Promote uniform ops to I32 in ISel (PR #106383)

[Matt Arsenault via llvm-commits]

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@@ -145,6 +145,31 @@ def expand_promoted_fmed3 : GICombineRule<
 
 } // End Predicates = [NotHasMed3_16]
 
+def promote_i16_uniform_binops_frag : GICombinePatFrag<
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arsenm wrote:

It's not really legalization. It's a register bank aware optimization. I would drop all the globalisel handling from this patch, it's a separate issue 

https://github.com/llvm/llvm-project/pull/106383