diff options
| -rw-r--r-- | lib/Transforms/Scalar/LICM.cpp | 78 |
1 files changed, 57 insertions, 21 deletions
diff --git a/lib/Transforms/Scalar/LICM.cpp b/lib/Transforms/Scalar/LICM.cpp index 9a104db00a..554b5ec517 100644 --- a/lib/Transforms/Scalar/LICM.cpp +++ b/lib/Transforms/Scalar/LICM.cpp @@ -184,13 +184,13 @@ namespace { /// void PromoteValuesInLoop(); - /// findPromotableValuesInLoop - Check the current loop for stores to + /// FindPromotableValuesInLoop - Check the current loop for stores to /// definite pointers, which are not loaded and stored through may aliases. /// If these are found, create an alloca for the value, add it to the /// PromotedValues list, and keep track of the mapping from value to /// alloca... /// - void findPromotableValuesInLoop( + void FindPromotableValuesInLoop( std::vector<std::pair<AllocaInst*, Value*> > &PromotedValues, std::map<Value*, AllocaInst*> &Val2AlMap); }; @@ -546,7 +546,7 @@ void LICM::sink(Instruction &I) { if (AI) { std::vector<AllocaInst*> Allocas; Allocas.push_back(AI); - PromoteMemToReg(Allocas, *DT, *DF, AA->getTargetData()); + PromoteMemToReg(Allocas, *DT, *DF, AA->getTargetData(), CurAST); } } } @@ -617,20 +617,47 @@ void LICM::PromoteValuesInLoop() { std::vector<std::pair<AllocaInst*, Value*> > PromotedValues; std::map<Value*, AllocaInst*> ValueToAllocaMap; // Map of ptr to alloca - findPromotableValuesInLoop(PromotedValues, ValueToAllocaMap); - if (ValueToAllocaMap.empty()) return; // If there are values to promote... + FindPromotableValuesInLoop(PromotedValues, ValueToAllocaMap); + if (ValueToAllocaMap.empty()) return; // If there are values to promote. Changed = true; NumPromoted += PromotedValues.size(); + std::vector<Value*> PointerValueNumbers; + // Emit a copy from the value into the alloca'd value in the loop preheader TerminatorInst *LoopPredInst = Preheader->getTerminator(); for (unsigned i = 0, e = PromotedValues.size(); i != e; ++i) { - // Load from the memory we are promoting... - LoadInst *LI = new LoadInst(PromotedValues[i].second, - PromotedValues[i].second->getName()+".promoted", - LoopPredInst); - // Store into the temporary alloca... + Value *Ptr = PromotedValues[i].second; + + // If we are promoting a pointer value, update alias information for the + // inserted load. + Value *LoadValue = 0; + if (isa<PointerType>(cast<PointerType>(Ptr->getType())->getElementType())) { + // Locate a load or store through the pointer, and assign the same value + // to LI as we are loading or storing. Since we know that the value is + // stored in this loop, this will always succeed. + for (Value::use_iterator UI = Ptr->use_begin(), E = Ptr->use_end(); + UI != E; ++UI) + if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) { + LoadValue = LI; + break; + } else if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) { + if (SI->getOperand(1) == LI) { + LoadValue = SI->getOperand(0); + break; + } + } + assert(LoadValue && "No store through the pointer found!"); + PointerValueNumbers.push_back(LoadValue); // Remember this for later. + } + + // Load from the memory we are promoting. + LoadInst *LI = new LoadInst(Ptr, Ptr->getName()+".promoted", LoopPredInst); + + if (LoadValue) CurAST->copyValue(LoadValue, LI); + + // Store into the temporary alloca. new StoreInst(LI, PromotedValues[i].first, LoopPredInst); } @@ -669,45 +696,51 @@ void LICM::PromoteValuesInLoop() { CurLoop->getExitBlocks(ExitBlocks); for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) if (ProcessedBlocks.insert(ExitBlocks[i]).second) { - // Copy all of the allocas into their memory locations... + // Copy all of the allocas into their memory locations. BasicBlock::iterator BI = ExitBlocks[i]->begin(); while (isa<PHINode>(*BI)) - ++BI; // Skip over all of the phi nodes in the block... + ++BI; // Skip over all of the phi nodes in the block. Instruction *InsertPos = BI; + unsigned PVN = 0; for (unsigned i = 0, e = PromotedValues.size(); i != e; ++i) { - // Load from the alloca... + // Load from the alloca. LoadInst *LI = new LoadInst(PromotedValues[i].first, "", InsertPos); - // Store into the memory we promoted... + + // If this is a pointer type, update alias info appropriately. + if (isa<PointerType>(LI->getType())) + CurAST->copyValue(PointerValueNumbers[PVN++], LI); + + // 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... + // all of the new allocas we just created into real SSA registers. // std::vector<AllocaInst*> PromotedAllocas; PromotedAllocas.reserve(PromotedValues.size()); for (unsigned i = 0, e = PromotedValues.size(); i != e; ++i) PromotedAllocas.push_back(PromotedValues[i].first); - PromoteMemToReg(PromotedAllocas, *DT, *DF, AA->getTargetData()); + PromoteMemToReg(PromotedAllocas, *DT, *DF, AA->getTargetData(), CurAST); } -/// findPromotableValuesInLoop - Check the current loop for stores to definite +/// FindPromotableValuesInLoop - Check the current loop for stores to definite /// pointers, which are not loaded and stored through may aliases. If these are /// found, create an alloca for the value, add it to the PromotedValues list, -/// and keep track of the mapping from value to alloca... +/// and keep track of the mapping from value to alloca. /// -void LICM::findPromotableValuesInLoop( +void LICM::FindPromotableValuesInLoop( std::vector<std::pair<AllocaInst*, Value*> > &PromotedValues, std::map<Value*, AllocaInst*> &ValueToAllocaMap) { Instruction *FnStart = CurLoop->getHeader()->getParent()->begin()->begin(); - // Loop over all of the alias sets in the tracker object... + // Loop over all of the alias sets in the tracker object. for (AliasSetTracker::iterator I = CurAST->begin(), E = CurAST->end(); I != E; ++I) { AliasSet &AS = *I; // We can promote this alias set if it has a store, if it is a "Must" alias - // set, if the pointer is loop invariant, if if we are not eliminating any + // set, if the pointer is loop invariant, and if we are not eliminating any // volatile loads or stores. if (!AS.isForwardingAliasSet() && AS.isMod() && AS.isMustAlias() && !AS.isVolatile() && CurLoop->isLoopInvariant(AS.begin()->first)) { @@ -729,6 +762,9 @@ void LICM::findPromotableValuesInLoop( const Type *Ty = cast<PointerType>(V->getType())->getElementType(); AllocaInst *AI = new AllocaInst(Ty, 0, V->getName()+".tmp", FnStart); PromotedValues.push_back(std::make_pair(AI, V)); + + // Update the AST and alias analysis. + CurAST->copyValue(V, AI); for (AliasSet::iterator I = AS.begin(), E = AS.end(); I != E; ++I) ValueToAllocaMap.insert(std::make_pair(I->first, AI)); |