[llvm] [AMDGPU][GlobalISel] Add register bank legalize rules for amdgcn_icmp, amdgcn_fcmp (PR #172017)

[Matt Arsenault via llvm-commits]

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@@ -1449,6 +1449,17 @@ bool RegBankLegalizeHelper::lower(MachineInstr &MI,
     return lowerAbsToNegMax(MI);
   case AbsToS32:
     return lowerAbsToS32(MI);
+  case IcmpI1ToBallot: {
+    // amdgcn.icmp(i1 src, i1 0, NE) -> ballot(src)
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arsenm wrote:

This doesn't belong in the regbanklegalizer. Ideally we would just bitcode autoupgrade, but this can be normal legalization I suppose 

https://github.com/llvm/llvm-project/pull/172017