[llvm] [InstCombine] Fold xor(zext(or disjoint X, C1), C2) (PR #214970)

[Andreas Jonson via llvm-commits]

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In-Reply-To: <llvm.org/llvm/llvm-project/pull/214970 at github.com>


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@@ -1775,6 +1775,27 @@ static Instruction *foldLogicCastConstant(BinaryOperator &Logic, CastInst *Cast,
   Type *DestTy = Logic.getType();
   Type *SrcTy = Cast->getSrcTy();
 
+  // xor (zext (or disjoint X, NarrowC)), WideC
+  //   -> xor (zext X), WideC ^ zext(NarrowC)
+  if (LogicOpc == Instruction::Xor && SrcTy->isIntegerTy() &&
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andjo403 wrote:

as this will only be valid for xor feels like this belong in visitXor instead of foldLogicCastConstant

https://github.com/llvm/llvm-project/pull/214970