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clean up some corner cases

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23692 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-10-10 23:00:08 +00:00
parent 87514ca04c
commit 04ecf6d65f
1 changed files with 6 additions and 2 deletions
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8
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -1583,14 +1583,18 @@ SDOperand DAGCombiner::visitSTORE(SDNode *N) {
SDOperand SrcValue = N->getOperand(3); SDOperand SrcValue = N->getOperand(3);
// If this is a store that kills a previous store, remove the previous store. // If this is a store that kills a previous store, remove the previous store.
if (Chain.getOpcode() == ISD::STORE && Chain.getOperand(2) == Ptr) { if (Chain.getOpcode() == ISD::STORE && Chain.getOperand(2) == Ptr &&
Chain.Val->hasOneUse() /* Avoid introducing DAG cycles */) {
// Create a new store of Value that replaces both stores. // Create a new store of Value that replaces both stores.
SDNode *PrevStore = Chain.Val; SDNode *PrevStore = Chain.Val;
if (PrevStore->getOperand(1) == Value) // Same value multiply stored.
return Chain;
SDOperand NewStore = DAG.getNode(ISD::STORE, MVT::Other, SDOperand NewStore = DAG.getNode(ISD::STORE, MVT::Other,
PrevStore->getOperand(0), Value, Ptr, PrevStore->getOperand(0), Value, Ptr,
SrcValue); SrcValue);
CombineTo(N, NewStore); // Nuke this store.
CombineTo(PrevStore, NewStore); // Nuke the previous store. CombineTo(PrevStore, NewStore); // Nuke the previous store.
return NewStore; // Replace this store with NewStore. return SDOperand(N, 0);
} }
return SDOperand(); return SDOperand();