Fix Regression/Transforms/LoopStrengthReduce/phi_node_update_multiple_preds.ll
by being more careful about updating PHI nodes
llvm-svn: 22739
diff --git a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index 4975614..547fd25 100644
--- a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -423,21 +423,28 @@
}
// PHI nodes are more complex. We have to insert one copy of the NewBase+Imm
- // expression into each operand block that uses it.
+ // expression into each operand block that uses it. Note that PHI nodes can
+ // have multiple entries for the same predecessor. We use a map to make sure
+ // that a PHI node only has a single Value* for each predecessor (which also
+ // prevents us from inserting duplicate code in some blocks).
+ std::map<BasicBlock*, Value*> InsertedCode;
PHINode *PN = cast<PHINode>(Inst);
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
if (PN->getIncomingValue(i) == OperandValToReplace) {
// FIXME: this should split any critical edges.
- // Insert the code into the end of the predecessor block.
- BasicBlock::iterator InsertPt = PN->getIncomingBlock(i)->getTerminator();
+ Value *&Code = InsertedCode[PN->getIncomingBlock(i)];
+ if (!Code) {
+ // Insert the code into the end of the predecessor block.
+ BasicBlock::iterator InsertPt =PN->getIncomingBlock(i)->getTerminator();
- SCEVHandle NewValSCEV = SCEVAddExpr::get(NewBase, Imm);
- Value *NewVal = Rewriter.expandCodeFor(NewValSCEV, InsertPt,
- OperandValToReplace->getType());
+ SCEVHandle NewValSCEV = SCEVAddExpr::get(NewBase, Imm);
+ Code = Rewriter.expandCodeFor(NewValSCEV, InsertPt,
+ OperandValToReplace->getType());
+ }
// Replace the use of the operand Value with the new Phi we just created.
- PN->setIncomingValue(i, NewVal);
+ PN->setIncomingValue(i, Code);
Rewriter.clear();
}
}