diff options
| -rw-r--r-- | llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp | 21 |
1 files changed, 14 insertions, 7 deletions
diff --git a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp index 4975614e50b..547fd25d58a 100644 --- a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp +++ b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp @@ -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(); } } |
