diff --git a/lib/Transforms/Scalar/LICM.cpp b/lib/Transforms/Scalar/LICM.cpp index 4100aed4c2b..2293c17c001 100644 --- a/lib/Transforms/Scalar/LICM.cpp +++ b/lib/Transforms/Scalar/LICM.cpp @@ -571,9 +571,7 @@ void LICM::PromoteValuesInLoop() { } // Scan the basic blocks in the loop, replacing uses of our pointers with - // uses of the allocas in question. If we find a branch that exits the - // loop, make sure to put reload code into all of the successors of the - // loop. + // uses of the allocas in question. // const std::vector &LoopBBs = CurLoop->getBlocks(); for (std::vector::const_iterator I = LoopBBs.begin(), @@ -593,27 +591,34 @@ void LICM::PromoteValuesInLoop() { S->setOperand(1, I->second); // Rewrite store instruction... } } - - // Check to see if any successors of this block are outside of the loop. - // If so, we need to copy the value from the alloca back into the memory - // location... - // - for (succ_iterator SI = succ_begin(*I), SE = succ_end(*I); SI != SE; ++SI) - if (!CurLoop->contains(*SI)) { - // Copy all of the allocas into their memory locations... - BasicBlock::iterator BI = (*SI)->begin(); - while (isa(*BI)) - ++BI; // Skip over all of the phi nodes in the block... - Instruction *InsertPos = BI; - for (unsigned i = 0, e = PromotedValues.size(); i != e; ++i) { - // Load from the alloca... - LoadInst *LI = new LoadInst(PromotedValues[i].first, "", InsertPos); - // Store into the memory we promoted... - new StoreInst(LI, PromotedValues[i].second, InsertPos); - } - } } + // Now that the body of the loop uses the allocas instead of the original + // memory locations, insert code to copy the alloca value back into the + // original memory location on all exits from the loop. Note that we only + // want to insert one copy of the code in each exit block, though the loop may + // exit to the same block more than once. + // + std::set ProcessedBlocks; + + const std::vector &ExitBlocks = CurLoop->getExitBlocks(); + for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) + if (!ProcessedBlocks.count(ExitBlocks[i])) { + ProcessedBlocks.insert(ExitBlocks[i]); + + // Copy all of the allocas into their memory locations... + BasicBlock::iterator BI = ExitBlocks[i]->begin(); + while (isa(*BI)) + ++BI; // Skip over all of the phi nodes in the block... + Instruction *InsertPos = BI; + for (unsigned i = 0, e = PromotedValues.size(); i != e; ++i) { + // Load from the alloca... + LoadInst *LI = new LoadInst(PromotedValues[i].first, "", InsertPos); + // Store into the memory we promoted... + new StoreInst(LI, PromotedValues[i].second, InsertPos); + } + } + // Now that we have done the deed, use the mem2reg functionality to promote // all of the new allocas we just created into real SSA registers... //