[llvm] [InstCombine] Fold Xor with or disjoint (PR #105992)

[via llvm-commits]

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@@ -4693,7 +4693,21 @@ Instruction *InstCombinerImpl::visitXor(BinaryOperator &I) {
   // calls in there are unnecessary as SimplifyDemandedInstructionBits should
   // have already taken care of those cases.
   Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-  Value *M;
+  Value *X, *Y, *M;
+
+  // (A | B) ^ C -> (A ^ C) ^ B
+  // C ^ (A | B) -> B ^ (A ^ C)
+  if (match(&I, m_c_Xor(m_OneUse(m_c_DisjointOr(m_Value(X), m_Value(Y))),
+                        m_Value(M)))) {
+    if (Value *XorAC = simplifyBinOp(Instruction::Xor, X, M, SQ)) {
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XChy wrote:

Don’t use braces on single-statement body of if. See https://llvm.org/docs/CodingStandards.html#don-t-use-braces-on-simple-single-statement-bodies-of-if-else-loop-statements

https://github.com/llvm/llvm-project/pull/105992