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Implement Transforms/InstCombine/xor.ll:test19
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11490 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -1002,15 +1002,26 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) {
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return Changed ? &I : 0;
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}
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// XorSelf - Implements: X ^ X --> 0
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struct XorSelf {
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Value *RHS;
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XorSelf(Value *rhs) : RHS(rhs) {}
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bool shouldApply(Value *LHS) const { return LHS == RHS; }
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Instruction *apply(BinaryOperator &Xor) const {
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return &Xor;
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}
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};
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Instruction *InstCombiner::visitXor(BinaryOperator &I) {
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bool Changed = SimplifyCommutative(I);
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Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
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// xor X, X = 0
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if (Op0 == Op1)
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// xor X, X = 0, even if X is nested in a sequence of Xor's.
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if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
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assert(Result == &I && "AssociativeOpt didn't work?");
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return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
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}
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if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
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// xor X, 0 == X
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