[llvm] [DAG] SelectionDAG::canCreateUndefOrPoison - add ISD::SCMP/UCMP handling + tests (PR #154127)

[Simon Pilgrim via llvm-commits]

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@@ -5748,6 +5748,8 @@ bool SelectionDAG::canCreateUndefOrPoison(SDValue Op, const APInt &DemandedElts,
   case ISD::FMA:
   case ISD::FMAD:
   case ISD::FP_EXTEND:
+  case ISD::SCMP:
+  case ISD::UCMP:
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RKSimon wrote:

scmp/ucmp don't have any flags - probably better to put them undef the same section umin/umax?

https://github.com/llvm/llvm-project/pull/154127