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Canonicalize VECTOR_SHUFFLE(X, X, Y) -> VECTOR_SHUFFLE(X,undef,Y') 

llvm-svn: 27235
This commit is contained in:
Chris Lattner 2006-03-28 22:11:53 +00:00
parent 112cee1182
commit a46dfe80c8
1 changed files with 30 additions and 0 deletions
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30
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -212,6 +212,7 @@ namespace {
SDOperand visitINSERT_VECTOR_ELT(SDNode *N);
SDOperand visitVINSERT_VECTOR_ELT(SDNode *N);
SDOperand visitVBUILD_VECTOR(SDNode *N);
SDOperand visitVECTOR_SHUFFLE(SDNode *N);
SDOperand ReassociateOps(unsigned Opc, SDOperand LHS, SDOperand RHS);
@ -646,6 +647,7 @@ SDOperand DAGCombiner::visit(SDNode *N) {
case ISD::INSERT_VECTOR_ELT: return visitINSERT_VECTOR_ELT(N);
case ISD::VINSERT_VECTOR_ELT: return visitVINSERT_VECTOR_ELT(N);
case ISD::VBUILD_VECTOR: return visitVBUILD_VECTOR(N);
case ISD::VECTOR_SHUFFLE: return visitVECTOR_SHUFFLE(N);
}
return SDOperand();
}
@ -2427,6 +2429,34 @@ SDOperand DAGCombiner::visitVBUILD_VECTOR(SDNode *N) {
return SDOperand();
}
SDOperand DAGCombiner::visitVECTOR_SHUFFLE(SDNode *N) {
// If the LHS and the RHS are the same node, turn the RHS into an undef.
if (N->getOperand(0) == N->getOperand(1)) {
// Check the SHUFFLE mask, mapping any inputs from the 2nd operand into the
// first operand.
std::vector<SDOperand> MappedOps;
SDOperand ShufMask = N->getOperand(2);
unsigned NumElts = ShufMask.getNumOperands();
for (unsigned i = 0, e = ShufMask.getNumOperands(); i != e; ++i) {
if (cast<ConstantSDNode>(ShufMask.getOperand(i))->getValue() >= NumElts) {
unsigned NewIdx =
cast<ConstantSDNode>(ShufMask.getOperand(i))->getValue() - NumElts;
MappedOps.push_back(DAG.getConstant(NewIdx, MVT::i32));
} else {
MappedOps.push_back(ShufMask.getOperand(i));
}
}
ShufMask = DAG.getNode(ISD::BUILD_VECTOR, ShufMask.getValueType(),
MappedOps);
return DAG.getNode(ISD::VECTOR_SHUFFLE, N->getValueType(0),
N->getOperand(0),
DAG.getNode(ISD::UNDEF, N->getValueType(0)),
ShufMask);
}
return SDOperand();
}
SDOperand DAGCombiner::SimplifySelect(SDOperand N0, SDOperand N1, SDOperand N2){
assert(N0.getOpcode() ==ISD::SETCC && "First argument must be a SetCC node!");