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Revert r166049

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- In general, it's unsafe for this transformation.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166135 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Michael Liao
2012-10-17 22:41:15 +00:00
parent 95a2bb4cdf
commit 4031e9018b
2 changed files with 0 additions and 64 deletions
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46
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@@ -5308,52 +5308,6 @@ SDValue DAGCombiner::visitTRUNCATE(SDNode *N) {
if (Reduced.getNode())
return Reduced;
}
// fold (trunc (fptoXi x)) -> (smaller fptoXi x)
if ((N0.getOpcode() == ISD::FP_TO_UINT ||
N0.getOpcode() == ISD::FP_TO_SINT) && !LegalTypes)
return DAG.getNode(N0.getOpcode(), N->getDebugLoc(), VT, N0.getOperand(0));
// fold (trunc (concat ... x ...)) -> (concat ..., (trunc x), ...)),
// where ... are all 'undef'.
if (N0.getOpcode() == ISD::CONCAT_VECTORS && !LegalTypes) {
SmallVector<EVT, 8> VTs;
SDValue V;
unsigned Idx = 0;
unsigned NumDefs = 0;
for (unsigned i = 0, e = N0.getNumOperands(); i != e; ++i) {
SDValue X = N0.getOperand(i);
if (X.getOpcode() != ISD::UNDEF) {
V = X;
Idx = i;
NumDefs++;
}
// Stop if more than one members are non-undef.
if (NumDefs > 1)
break;
VTs.push_back(EVT::getVectorVT(*DAG.getContext(),
VT.getVectorElementType(),
X.getValueType().getVectorNumElements()));
}
if (NumDefs == 0)
return DAG.getUNDEF(VT);
if (NumDefs == 1) {
assert(V.getNode() && "The single defined operand is empty!");
SmallVector<SDValue, 8> Opnds;
for (unsigned i = 0, e = VTs.size(); i != e; ++i) {
if (i != Idx) {
Opnds.push_back(DAG.getUNDEF(VTs[i]));
continue;
}
SDValue NV = DAG.getNode(ISD::TRUNCATE, V.getDebugLoc(), VTs[i], V);
AddToWorkList(NV.getNode());
Opnds.push_back(NV);
}
return DAG.getNode(ISD::CONCAT_VECTORS, N->getDebugLoc(), VT,
&Opnds[0], Opnds.size());
}
}
// Simplify the operands using demanded-bits information.
if (!VT.isVector() &&