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Differential D62774 Diff 202903 llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

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llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

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Show First 20 Lines • Show All 3,027 Lines • ▼ Show 20 LinesSDValue DAGCombiner::visitSUB(SDNode *N) {
} }
// (x - C) - y -> (x - y) - C // (x - C) - y -> (x - y) - C
// This is necessary because SUB(X,C) -> ADD(X,-C) doesn't work for vectors. // This is necessary because SUB(X,C) -> ADD(X,-C) doesn't work for vectors.
if (N0.hasOneUse() && N0.getOpcode() == ISD::SUB && if (N0.hasOneUse() && N0.getOpcode() == ISD::SUB &&
isConstantOrConstantVector(N0.getOperand(1), /*NoOpaques=*/true)) { isConstantOrConstantVector(N0.getOperand(1), /*NoOpaques=*/true)) {
SDValue Sub = DAG.getNode(ISD::SUB, DL, VT, N0.getOperand(0), N1); SDValue Sub = DAG.getNode(ISD::SUB, DL, VT, N0.getOperand(0), N1);
return DAG.getNode(ISD::SUB, DL, VT, Sub, N0.getOperand(1)); return DAG.getNode(ISD::SUB, DL, VT, Sub, N0.getOperand(1));
} }
// (C - x) - y -> C - (x + y)
if (N0.hasOneUse() && N0.getOpcode() == ISD::SUB &&
isConstantOrConstantVector(N0.getOperand(0), /*NoOpaques=*/true)) {
SDValue Add = DAG.getNode(ISD::ADD, DL, VT, N0.getOperand(1), N1);
return DAG.getNode(ISD::SUB, DL, VT, N0.getOperand(0), Add);
}
// If the target's bool is represented as 0/-1, prefer to make this 'add 0/-1' // If the target's bool is represented as 0/-1, prefer to make this 'add 0/-1'
// rather than 'sub 0/1' (the sext should get folded). // rather than 'sub 0/1' (the sext should get folded).
// sub X, (zext i1 Y) --> add X, (sext i1 Y) // sub X, (zext i1 Y) --> add X, (sext i1 Y)
if (N1.getOpcode() == ISD::ZERO_EXTEND && if (N1.getOpcode() == ISD::ZERO_EXTEND &&
N1.getOperand(0).getScalarValueSizeInBits() == 1 && N1.getOperand(0).getScalarValueSizeInBits() == 1 &&
TLI.getBooleanContents(VT) == TLI.getBooleanContents(VT) ==
TargetLowering::ZeroOrNegativeOneBooleanContent) { TargetLowering::ZeroOrNegativeOneBooleanContent) {
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