From d0f56132cfa6e25fb9692e84ea12444c86b92ae4 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Fri, 14 Jan 2011 19:50:47 +0000 Subject: [PATCH] switch SRoA to use LoadAndStorePromoter instead of its own copy of the code. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123457 91177308-0d34-0410-b5e6-96231b3b80d8 --- .../Scalar/ScalarReplAggregates.cpp | 166 +++--------------- 1 file changed, 28 insertions(+), 138 deletions(-) diff --git a/lib/Transforms/Scalar/ScalarReplAggregates.cpp b/lib/Transforms/Scalar/ScalarReplAggregates.cpp index f66a7193312..07d9787e663 100644 --- a/lib/Transforms/Scalar/ScalarReplAggregates.cpp +++ b/lib/Transforms/Scalar/ScalarReplAggregates.cpp @@ -840,144 +840,35 @@ bool SROA::runOnFunction(Function &F) { return Changed; } -/// PromoteAlloca - Promote an alloca to registers, using SSAUpdater. -static void PromoteAlloca(AllocaInst *AI, SSAUpdater &SSA) { - SSA.Initialize(AI->getType()->getElementType(), AI->getName()); +namespace { +class AllocaPromoter : public LoadAndStorePromoter { + AllocaInst *AI; +public: + AllocaPromoter() : AI(0) {} + + void run(AllocaInst *AI, SSAUpdater &SSA) { + // Remember which alloca we're promoting (for isInstInList). + this->AI = AI; - // First step: bucket up uses of the alloca by the block they occur in. - // This is important because we have to handle multiple defs/uses in a block - // ourselves: SSAUpdater is purely for cross-block references. - // FIXME: Want a TinyVector since there is often 0/1 element. - DenseMap > UsesByBlock; - - for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end(); - UI != E; ++UI) { - Instruction *User = cast(*UI); - UsesByBlock[User->getParent()].push_back(User); + // Build the list of instructions to promote. + SmallVector Insts; + for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end(); + UI != E; ++UI) + Insts.push_back(cast(*UI)); + + LoadAndStorePromoter::run(AI->getName(), Insts, &SSA); + + AI->eraseFromParent(); } - // Okay, now we can iterate over all the blocks in the function with uses, - // processing them. Keep track of which loads are loading a live-in value. - // Walk the uses in the use-list order to be determinstic. - SmallVector LiveInLoads; - DenseMap ReplacedLoads; - - for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end(); - UI != E; ++UI) { - Instruction *User = cast(*UI); - BasicBlock *BB = User->getParent(); - std::vector &BlockUses = UsesByBlock[BB]; - - // If this block has already been processed, ignore this repeat use. - if (BlockUses.empty()) continue; - - // Okay, this is the first use in the block. If this block just has a - // single user in it, we can rewrite it trivially. - if (BlockUses.size() == 1) { - // If it is a store, it is a trivial def of the value in the block. - if (StoreInst *SI = dyn_cast(User)) - SSA.AddAvailableValue(BB, SI->getOperand(0)); - else - // Otherwise it is a load, queue it to rewrite as a live-in load. - LiveInLoads.push_back(cast(User)); - BlockUses.clear(); - continue; - } - - // Otherwise, check to see if this block is all loads. - bool HasStore = false; - for (unsigned i = 0, e = BlockUses.size(); i != e; ++i) { - if (isa(BlockUses[i])) { - HasStore = true; - break; - } - } - - // If so, we can queue them all as live in loads. We don't have an - // efficient way to tell which on is first in the block and don't want to - // scan large blocks, so just add all loads as live ins. - if (!HasStore) { - for (unsigned i = 0, e = BlockUses.size(); i != e; ++i) - LiveInLoads.push_back(cast(BlockUses[i])); - BlockUses.clear(); - continue; - } - - // Otherwise, we have mixed loads and stores (or just a bunch of stores). - // Since SSAUpdater is purely for cross-block values, we need to determine - // the order of these instructions in the block. If the first use in the - // block is a load, then it uses the live in value. The last store defines - // the live out value. We handle this by doing a linear scan of the block. - Value *StoredValue = 0; - for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) { - if (LoadInst *L = dyn_cast(II)) { - // If this is a load from an unrelated pointer, ignore it. - if (L->getOperand(0) != AI) continue; - - // If we haven't seen a store yet, this is a live in use, otherwise - // use the stored value. - if (StoredValue) { - L->replaceAllUsesWith(StoredValue); - ReplacedLoads[L] = StoredValue; - } else { - LiveInLoads.push_back(L); - } - continue; - } - - if (StoreInst *S = dyn_cast(II)) { - // If this is a store to an unrelated pointer, ignore it. - if (S->getPointerOperand() != AI) continue; - - // Remember that this is the active value in the block. - StoredValue = S->getOperand(0); - } - } - - // The last stored value that happened is the live-out for the block. - assert(StoredValue && "Already checked that there is a store in block"); - SSA.AddAvailableValue(BB, StoredValue); - BlockUses.clear(); + virtual bool isInstInList(Instruction *I, + const SmallVectorImpl &Insts) const { + if (LoadInst *LI = dyn_cast(I)) + return LI->getOperand(0) == AI; + return cast(I)->getPointerOperand() == AI; } - - // Okay, now we rewrite all loads that use live-in values in the loop, - // inserting PHI nodes as necessary. - for (unsigned i = 0, e = LiveInLoads.size(); i != e; ++i) { - LoadInst *ALoad = LiveInLoads[i]; - Value *NewVal = SSA.GetValueInMiddleOfBlock(ALoad->getParent()); - ALoad->replaceAllUsesWith(NewVal); - ReplacedLoads[ALoad] = NewVal; - } - - // Now that everything is rewritten, delete the old instructions from the - // function. They should all be dead now. - for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end(); UI != E; ) { - Instruction *User = cast(*UI++); - - // If this is a load that still has uses, then the load must have been added - // as a live value in the SSAUpdate data structure for a block (e.g. because - // the loaded value was stored later). In this case, we need to recursively - // propagate the updates until we get to the real value. - if (!User->use_empty()) { - Value *NewVal = ReplacedLoads[User]; - assert(NewVal && "not a replaced load?"); - - // Propagate down to the ultimate replacee. The intermediately loads - // could theoretically already have been deleted, so we don't want to - // dereference the Value*'s. - DenseMap::iterator RLI = ReplacedLoads.find(NewVal); - while (RLI != ReplacedLoads.end()) { - NewVal = RLI->second; - RLI = ReplacedLoads.find(NewVal); - } - - User->replaceAllUsesWith(NewVal); - } - - User->eraseFromParent(); - } -} - +}; +} // end anon namespace bool SROA::performPromotion(Function &F) { std::vector Allocas; @@ -1008,10 +899,9 @@ bool SROA::performPromotion(Function &F) { PromoteMemToReg(Allocas, *DT, *DF); else { SSAUpdater SSA; - for (unsigned i = 0, e = Allocas.size(); i != e; ++i) { - PromoteAlloca(Allocas[i], SSA); - Allocas[i]->eraseFromParent(); - } + AllocaPromoter Promoter; + for (unsigned i = 0, e = Allocas.size(); i != e; ++i) + Promoter.run(Allocas[i], SSA); } NumPromoted += Allocas.size(); Changed = true;