[llvm] [X86] Prefer sub-of-not for vector inc-of-add (PR #207695)

[Simon Pilgrim via llvm-commits]

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@@ -3819,6 +3819,13 @@ unsigned X86TargetLowering::preferedOpcodeForCmpEqPiecesOfOperand(
   return ISD::SRL;
 }
 
+bool X86TargetLowering::preferIncOfAddToSubOfNot(EVT VT) const {
+  // Prefer inc-of-add for scalars and single-element vectors, and sub-of-not
+  // for multi-element vectors.
+  return VT.isScalarInteger() ||
+         (VT.isVector() && VT.getVectorElementCount().isScalar());
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RKSimon wrote:

would a `!isTypeLegal(VT.getScalarType())` work better?

https://github.com/llvm/llvm-project/pull/207695