[llvm] [DAG] SelectionDAG::canCreateUndefOrPoison - Mark AVGFLOORS and AVGCEILS as safe (PR #148191)

[Jay Foad via llvm-commits]

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@@ -5542,6 +5542,10 @@ bool SelectionDAG::canCreateUndefOrPoison(SDValue Op, const APInt &DemandedElts,
   case ISD::UADDSAT:
   case ISD::SSUBSAT:
   case ISD::USUBSAT:
+  case ISD::AVGFLOORS:
+  case ISD::AVGFLOORU:
+  case ISD::AVGCEILS:
+  case ISD::AVGCEILU:
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jayfoad wrote:

These proofs are weird: the whole point of the and/xor/ashr/add implementation is that you _don't_ need to extend to a wider type, you can do all operations in i8.

https://github.com/llvm/llvm-project/pull/148191