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Fix a bug in the folding of binary operators to undef.

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Thanks to Lauro for spotting this!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@38491 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman
2007-07-10 15:19:29 +00:00
parent eff155349a
commit 70fb1aefd5
1 changed files with 10 additions and 4 deletions
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14
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -855,7 +855,9 @@ SDOperand DAGCombiner::visitADD(SDNode *N) {
if (FoldedVOp.Val) return FoldedVOp; if (FoldedVOp.Val) return FoldedVOp;
// fold (add x, undef) -> undef // fold (add x, undef) -> undef
if (N0.getOpcode() == ISD::UNDEF || N1.getOpcode() == ISD::UNDEF) if (N0.getOpcode() == ISD::UNDEF)
return N0;
if (N1.getOpcode() == ISD::UNDEF)
return N1; return N1;
// fold (add c1, c2) -> c1+c2 // fold (add c1, c2) -> c1+c2
if (N0C && N1C) if (N0C && N1C)
@ -1029,8 +1031,10 @@ SDOperand DAGCombiner::visitSUB(SDNode *N) {
if (Result.Val) return Result; if (Result.Val) return Result;
} }
// If either operand of a sub is undef, the result is undef // If either operand of a sub is undef, the result is undef
if (N0.getOpcode() == ISD::UNDEF || N1.getOpcode() == ISD::UNDEF) if (N0.getOpcode() == ISD::UNDEF)
return DAG.getNode(ISD::UNDEF, VT); return N0;
if (N1.getOpcode() == ISD::UNDEF)
return N1;
return SDOperand(); return SDOperand();
} }
@ -1890,7 +1894,9 @@ SDOperand DAGCombiner::visitXOR(SDNode *N) {
if (FoldedVOp.Val) return FoldedVOp; if (FoldedVOp.Val) return FoldedVOp;
// fold (xor x, undef) -> undef // fold (xor x, undef) -> undef
if (N0.getOpcode() == ISD::UNDEF || N1.getOpcode() == ISD::UNDEF) if (N0.getOpcode() == ISD::UNDEF)
return N0;
if (N1.getOpcode() == ISD::UNDEF)
return N1; return N1;
// fold (xor c1, c2) -> c1^c2 // fold (xor c1, c2) -> c1^c2
if (N0C && N1C) if (N0C && N1C)