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Fix Regression/Transforms/LoopStrengthReduce/phi_node_update_multiple_preds.ll

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by being more careful about updating PHI nodes


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22739 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-08-10 00:35:32 +00:00
parent 3b7fd6647d
commit c41e34520a
1 changed files with 14 additions and 7 deletions
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21
lib/Transforms/Scalar/LoopStrengthReduce.cpp
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@ -423,21 +423,28 @@ void BasedUser::RewriteInstructionToUseNewBase(const SCEVHandle &NewBase,
}
// 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();
}
}