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17acad625c
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@ -532,6 +532,10 @@ SDOperand DAGCombiner::visitSUB(SDNode *N) {
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ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0.Val);
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ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1.Val);
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// fold (sub x, x) -> 0
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if (N0 == N1)
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return DAG.getConstant(0, N->getValueType(0));
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// fold (sub c1, c2) -> c1-c2
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if (N0C && N1C)
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return DAG.getConstant(N0C->getValue() - N1C->getValue(),
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