[llvm] [SelectionDAG] Move VSelect sign pattern check from AArch64 to general SelectionDAG (PR #151840)

[Matt Arsenault via llvm-commits]

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@@ -13957,8 +13957,13 @@ static SDValue combineVSelectWithAllOnesOrZeros(SDValue Cond, SDValue TVal,
       ISD::isConstantSplatVector(TVal.getNode(), TValAPInt) &&
       TValAPInt.isOne() &&
       ISD::isConstantSplatVectorAllOnes(Cond.getOperand(1).getNode()) &&
-      ISD::isConstantSplatVectorAllOnes(FVal.getNode())) {
-    return SDValue();
+      ISD::isConstantSplatVectorAllOnes(FVal.getNode()) &&
+      !TLI.shouldAvoidTransformToShift(VT, VT.getScalarSizeInBits() - 1)) {
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arsenm wrote:

This is one of those terrible TLI hooks that don't really make any sense, but I see it's preexisting 

https://github.com/llvm/llvm-project/pull/151840