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Refactor zero folding slightly. Clean up todo.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125651 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Eric Christopher 2011-02-16 04:50:12 +00:00
parent 908159b46a
commit 7bccf6abdc
1 changed files with 20 additions and 22 deletions
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42
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -1518,6 +1518,22 @@ SDValue DAGCombiner::visitADDE(SDNode *N) {
return SDValue();
}
// Since it may not be valid to emit a fold to zero for vector initializers
// check if we can before folding.
static SDValue tryFoldToZero(DebugLoc DL, const TargetLowering &TLI, EVT VT,
SelectionDAG &DAG, bool LegalOperations) {
if (!VT.isVector()) {
return DAG.getConstant(0, VT);
} else if (!LegalOperations || TLI.isOperationLegal(ISD::BUILD_VECTOR, VT)) {
// Produce a vector of zeros.
SDValue El = DAG.getConstant(0, VT.getVectorElementType());
std::vector<SDValue> Ops(VT.getVectorNumElements(), El);
return DAG.getNode(ISD::BUILD_VECTOR, DL, VT,
&Ops[0], Ops.size());
}
return SDValue();
}
SDValue DAGCombiner::visitSUB(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
@ -1533,17 +1549,8 @@ SDValue DAGCombiner::visitSUB(SDNode *N) {
// fold (sub x, x) -> 0
// FIXME: Refactor this and xor and other similar operations together.
if (N0 == N1) {
if (!VT.isVector()) {
return DAG.getConstant(0, VT);
} else if (!LegalOperations || TLI.isOperationLegal(ISD::BUILD_VECTOR, VT)){
// Produce a vector of zeros.
SDValue El = DAG.getConstant(0, VT.getVectorElementType());
std::vector<SDValue> Ops(VT.getVectorNumElements(), El);
return DAG.getNode(ISD::BUILD_VECTOR, N->getDebugLoc(), VT,
&Ops[0], Ops.size());
}
}
if (N0 == N1)
return tryFoldToZero(N->getDebugLoc(), TLI, VT, DAG, LegalOperations);
// fold (sub c1, c2) -> c1-c2
if (N0C && N1C)
return DAG.FoldConstantArithmetic(ISD::SUB, VT, N0C, N1C);
@ -2843,17 +2850,8 @@ SDValue DAGCombiner::visitXOR(SDNode *N) {
N01C->getAPIntValue(), VT));
}
// fold (xor x, x) -> 0
if (N0 == N1) {
if (!VT.isVector()) {
return DAG.getConstant(0, VT);
} else if (!LegalOperations || TLI.isOperationLegal(ISD::BUILD_VECTOR, VT)){
// Produce a vector of zeros.
SDValue El = DAG.getConstant(0, VT.getVectorElementType());
std::vector<SDValue> Ops(VT.getVectorNumElements(), El);
return DAG.getNode(ISD::BUILD_VECTOR, N->getDebugLoc(), VT,
&Ops[0], Ops.size());
}
}
if (N0 == N1)
return tryFoldToZero(N->getDebugLoc(), TLI, VT, DAG, LegalOperations);
// Simplify: xor (op x...), (op y...) -> (op (xor x, y))
if (N0.getOpcode() == N1.getOpcode()) {