| //===- BBVectorize.cpp - A Basic-Block Vectorizer -------------------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements a basic-block vectorization pass. The algorithm was |
| // inspired by that used by the Vienna MAP Vectorizor by Franchetti and Kral, |
| // et al. It works by looking for chains of pairable operations and then |
| // pairing them. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #define BBV_NAME "bb-vectorize" |
| #define DEBUG_TYPE BBV_NAME |
| #include "llvm/Constants.h" |
| #include "llvm/DerivedTypes.h" |
| #include "llvm/Function.h" |
| #include "llvm/Instructions.h" |
| #include "llvm/IntrinsicInst.h" |
| #include "llvm/Intrinsics.h" |
| #include "llvm/LLVMContext.h" |
| #include "llvm/Pass.h" |
| #include "llvm/Type.h" |
| #include "llvm/ADT/DenseMap.h" |
| #include "llvm/ADT/DenseSet.h" |
| #include "llvm/ADT/SmallVector.h" |
| #include "llvm/ADT/Statistic.h" |
| #include "llvm/ADT/STLExtras.h" |
| #include "llvm/ADT/StringExtras.h" |
| #include "llvm/Analysis/AliasAnalysis.h" |
| #include "llvm/Analysis/AliasSetTracker.h" |
| #include "llvm/Analysis/ScalarEvolution.h" |
| #include "llvm/Analysis/ScalarEvolutionExpressions.h" |
| #include "llvm/Analysis/ValueTracking.h" |
| #include "llvm/Support/CommandLine.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include "llvm/Support/ValueHandle.h" |
| #include "llvm/Target/TargetData.h" |
| #include "llvm/Transforms/Vectorize.h" |
| #include <algorithm> |
| #include <map> |
| using namespace llvm; |
| |
| static cl::opt<unsigned> |
| ReqChainDepth("bb-vectorize-req-chain-depth", cl::init(6), cl::Hidden, |
| cl::desc("The required chain depth for vectorization")); |
| |
| static cl::opt<unsigned> |
| SearchLimit("bb-vectorize-search-limit", cl::init(400), cl::Hidden, |
| cl::desc("The maximum search distance for instruction pairs")); |
| |
| static cl::opt<bool> |
| SplatBreaksChain("bb-vectorize-splat-breaks-chain", cl::init(false), cl::Hidden, |
| cl::desc("Replicating one element to a pair breaks the chain")); |
| |
| static cl::opt<unsigned> |
| VectorBits("bb-vectorize-vector-bits", cl::init(128), cl::Hidden, |
| cl::desc("The size of the native vector registers")); |
| |
| static cl::opt<unsigned> |
| MaxIter("bb-vectorize-max-iter", cl::init(0), cl::Hidden, |
| cl::desc("The maximum number of pairing iterations")); |
| |
| static cl::opt<unsigned> |
| MaxInsts("bb-vectorize-max-instr-per-group", cl::init(500), cl::Hidden, |
| cl::desc("The maximum number of pairable instructions per group")); |
| |
| static cl::opt<unsigned> |
| MaxCandPairsForCycleCheck("bb-vectorize-max-cycle-check-pairs", cl::init(200), |
| cl::Hidden, cl::desc("The maximum number of candidate pairs with which to use" |
| " a full cycle check")); |
| |
| static cl::opt<bool> |
| NoInts("bb-vectorize-no-ints", cl::init(false), cl::Hidden, |
| cl::desc("Don't try to vectorize integer values")); |
| |
| static cl::opt<bool> |
| NoFloats("bb-vectorize-no-floats", cl::init(false), cl::Hidden, |
| cl::desc("Don't try to vectorize floating-point values")); |
| |
| static cl::opt<bool> |
| NoPointers("bb-vectorize-no-pointers", cl::init(false), cl::Hidden, |
| cl::desc("Don't try to vectorize pointer values")); |
| |
| static cl::opt<bool> |
| NoCasts("bb-vectorize-no-casts", cl::init(false), cl::Hidden, |
| cl::desc("Don't try to vectorize casting (conversion) operations")); |
| |
| static cl::opt<bool> |
| NoMath("bb-vectorize-no-math", cl::init(false), cl::Hidden, |
| cl::desc("Don't try to vectorize floating-point math intrinsics")); |
| |
| static cl::opt<bool> |
| NoFMA("bb-vectorize-no-fma", cl::init(false), cl::Hidden, |
| cl::desc("Don't try to vectorize the fused-multiply-add intrinsic")); |
| |
| static cl::opt<bool> |
| NoSelect("bb-vectorize-no-select", cl::init(false), cl::Hidden, |
| cl::desc("Don't try to vectorize select instructions")); |
| |
| static cl::opt<bool> |
| NoGEP("bb-vectorize-no-gep", cl::init(false), cl::Hidden, |
| cl::desc("Don't try to vectorize getelementptr instructions")); |
| |
| static cl::opt<bool> |
| NoMemOps("bb-vectorize-no-mem-ops", cl::init(false), cl::Hidden, |
| cl::desc("Don't try to vectorize loads and stores")); |
| |
| static cl::opt<bool> |
| AlignedOnly("bb-vectorize-aligned-only", cl::init(false), cl::Hidden, |
| cl::desc("Only generate aligned loads and stores")); |
| |
| static cl::opt<bool> |
| NoMemOpBoost("bb-vectorize-no-mem-op-boost", |
| cl::init(false), cl::Hidden, |
| cl::desc("Don't boost the chain-depth contribution of loads and stores")); |
| |
| static cl::opt<bool> |
| FastDep("bb-vectorize-fast-dep", cl::init(false), cl::Hidden, |
| cl::desc("Use a fast instruction dependency analysis")); |
| |
| #ifndef NDEBUG |
| static cl::opt<bool> |
| DebugInstructionExamination("bb-vectorize-debug-instruction-examination", |
| cl::init(false), cl::Hidden, |
| cl::desc("When debugging is enabled, output information on the" |
| " instruction-examination process")); |
| static cl::opt<bool> |
| DebugCandidateSelection("bb-vectorize-debug-candidate-selection", |
| cl::init(false), cl::Hidden, |
| cl::desc("When debugging is enabled, output information on the" |
| " candidate-selection process")); |
| static cl::opt<bool> |
| DebugPairSelection("bb-vectorize-debug-pair-selection", |
| cl::init(false), cl::Hidden, |
| cl::desc("When debugging is enabled, output information on the" |
| " pair-selection process")); |
| static cl::opt<bool> |
| DebugCycleCheck("bb-vectorize-debug-cycle-check", |
| cl::init(false), cl::Hidden, |
| cl::desc("When debugging is enabled, output information on the" |
| " cycle-checking process")); |
| #endif |
| |
| STATISTIC(NumFusedOps, "Number of operations fused by bb-vectorize"); |
| |
| namespace { |
| struct BBVectorize : public BasicBlockPass { |
| static char ID; // Pass identification, replacement for typeid |
| |
| const VectorizeConfig Config; |
| |
| BBVectorize(const VectorizeConfig &C = VectorizeConfig()) |
| : BasicBlockPass(ID), Config(C) { |
| initializeBBVectorizePass(*PassRegistry::getPassRegistry()); |
| } |
| |
| BBVectorize(Pass *P, const VectorizeConfig &C) |
| : BasicBlockPass(ID), Config(C) { |
| AA = &P->getAnalysis<AliasAnalysis>(); |
| SE = &P->getAnalysis<ScalarEvolution>(); |
| TD = P->getAnalysisIfAvailable<TargetData>(); |
| } |
| |
| typedef std::pair<Value *, Value *> ValuePair; |
| typedef std::pair<ValuePair, size_t> ValuePairWithDepth; |
| typedef std::pair<ValuePair, ValuePair> VPPair; // A ValuePair pair |
| typedef std::pair<std::multimap<Value *, Value *>::iterator, |
| std::multimap<Value *, Value *>::iterator> VPIteratorPair; |
| typedef std::pair<std::multimap<ValuePair, ValuePair>::iterator, |
| std::multimap<ValuePair, ValuePair>::iterator> |
| VPPIteratorPair; |
| |
| AliasAnalysis *AA; |
| ScalarEvolution *SE; |
| TargetData *TD; |
| |
| // FIXME: const correct? |
| |
| bool vectorizePairs(BasicBlock &BB); |
| |
| bool getCandidatePairs(BasicBlock &BB, |
| BasicBlock::iterator &Start, |
| std::multimap<Value *, Value *> &CandidatePairs, |
| std::vector<Value *> &PairableInsts); |
| |
| void computeConnectedPairs(std::multimap<Value *, Value *> &CandidatePairs, |
| std::vector<Value *> &PairableInsts, |
| std::multimap<ValuePair, ValuePair> &ConnectedPairs); |
| |
| void buildDepMap(BasicBlock &BB, |
| std::multimap<Value *, Value *> &CandidatePairs, |
| std::vector<Value *> &PairableInsts, |
| DenseSet<ValuePair> &PairableInstUsers); |
| |
| void choosePairs(std::multimap<Value *, Value *> &CandidatePairs, |
| std::vector<Value *> &PairableInsts, |
| std::multimap<ValuePair, ValuePair> &ConnectedPairs, |
| DenseSet<ValuePair> &PairableInstUsers, |
| DenseMap<Value *, Value *>& ChosenPairs); |
| |
| void fuseChosenPairs(BasicBlock &BB, |
| std::vector<Value *> &PairableInsts, |
| DenseMap<Value *, Value *>& ChosenPairs); |
| |
| bool isInstVectorizable(Instruction *I, bool &IsSimpleLoadStore); |
| |
| bool areInstsCompatible(Instruction *I, Instruction *J, |
| bool IsSimpleLoadStore); |
| |
| bool trackUsesOfI(DenseSet<Value *> &Users, |
| AliasSetTracker &WriteSet, Instruction *I, |
| Instruction *J, bool UpdateUsers = true, |
| std::multimap<Value *, Value *> *LoadMoveSet = 0); |
| |
| void computePairsConnectedTo( |
| std::multimap<Value *, Value *> &CandidatePairs, |
| std::vector<Value *> &PairableInsts, |
| std::multimap<ValuePair, ValuePair> &ConnectedPairs, |
| ValuePair P); |
| |
| bool pairsConflict(ValuePair P, ValuePair Q, |
| DenseSet<ValuePair> &PairableInstUsers, |
| std::multimap<ValuePair, ValuePair> *PairableInstUserMap = 0); |
| |
| bool pairWillFormCycle(ValuePair P, |
| std::multimap<ValuePair, ValuePair> &PairableInstUsers, |
| DenseSet<ValuePair> &CurrentPairs); |
| |
| void pruneTreeFor( |
| std::multimap<Value *, Value *> &CandidatePairs, |
| std::vector<Value *> &PairableInsts, |
| std::multimap<ValuePair, ValuePair> &ConnectedPairs, |
| DenseSet<ValuePair> &PairableInstUsers, |
| std::multimap<ValuePair, ValuePair> &PairableInstUserMap, |
| DenseMap<Value *, Value *> &ChosenPairs, |
| DenseMap<ValuePair, size_t> &Tree, |
| DenseSet<ValuePair> &PrunedTree, ValuePair J, |
| bool UseCycleCheck); |
| |
| void buildInitialTreeFor( |
| std::multimap<Value *, Value *> &CandidatePairs, |
| std::vector<Value *> &PairableInsts, |
| std::multimap<ValuePair, ValuePair> &ConnectedPairs, |
| DenseSet<ValuePair> &PairableInstUsers, |
| DenseMap<Value *, Value *> &ChosenPairs, |
| DenseMap<ValuePair, size_t> &Tree, ValuePair J); |
| |
| void findBestTreeFor( |
| std::multimap<Value *, Value *> &CandidatePairs, |
| std::vector<Value *> &PairableInsts, |
| std::multimap<ValuePair, ValuePair> &ConnectedPairs, |
| DenseSet<ValuePair> &PairableInstUsers, |
| std::multimap<ValuePair, ValuePair> &PairableInstUserMap, |
| DenseMap<Value *, Value *> &ChosenPairs, |
| DenseSet<ValuePair> &BestTree, size_t &BestMaxDepth, |
| size_t &BestEffSize, VPIteratorPair ChoiceRange, |
| bool UseCycleCheck); |
| |
| Value *getReplacementPointerInput(LLVMContext& Context, Instruction *I, |
| Instruction *J, unsigned o, bool &FlipMemInputs); |
| |
| void fillNewShuffleMask(LLVMContext& Context, Instruction *J, |
| unsigned NumElem, unsigned MaskOffset, unsigned NumInElem, |
| unsigned IdxOffset, std::vector<Constant*> &Mask); |
| |
| Value *getReplacementShuffleMask(LLVMContext& Context, Instruction *I, |
| Instruction *J); |
| |
| Value *getReplacementInput(LLVMContext& Context, Instruction *I, |
| Instruction *J, unsigned o, bool FlipMemInputs); |
| |
| void getReplacementInputsForPair(LLVMContext& Context, Instruction *I, |
| Instruction *J, SmallVector<Value *, 3> &ReplacedOperands, |
| bool &FlipMemInputs); |
| |
| void replaceOutputsOfPair(LLVMContext& Context, Instruction *I, |
| Instruction *J, Instruction *K, |
| Instruction *&InsertionPt, Instruction *&K1, |
| Instruction *&K2, bool &FlipMemInputs); |
| |
| void collectPairLoadMoveSet(BasicBlock &BB, |
| DenseMap<Value *, Value *> &ChosenPairs, |
| std::multimap<Value *, Value *> &LoadMoveSet, |
| Instruction *I); |
| |
| void collectLoadMoveSet(BasicBlock &BB, |
| std::vector<Value *> &PairableInsts, |
| DenseMap<Value *, Value *> &ChosenPairs, |
| std::multimap<Value *, Value *> &LoadMoveSet); |
| |
| bool canMoveUsesOfIAfterJ(BasicBlock &BB, |
| std::multimap<Value *, Value *> &LoadMoveSet, |
| Instruction *I, Instruction *J); |
| |
| void moveUsesOfIAfterJ(BasicBlock &BB, |
| std::multimap<Value *, Value *> &LoadMoveSet, |
| Instruction *&InsertionPt, |
| Instruction *I, Instruction *J); |
| |
| bool vectorizeBB(BasicBlock &BB) { |
| bool changed = false; |
| // Iterate a sufficient number of times to merge types of size 1 bit, |
| // then 2 bits, then 4, etc. up to half of the target vector width of the |
| // target vector register. |
| for (unsigned v = 2, n = 1; |
| v <= Config.VectorBits && (!Config.MaxIter || n <= Config.MaxIter); |
| v *= 2, ++n) { |
| DEBUG(dbgs() << "BBV: fusing loop #" << n << |
| " for " << BB.getName() << " in " << |
| BB.getParent()->getName() << "...\n"); |
| if (vectorizePairs(BB)) |
| changed = true; |
| else |
| break; |
| } |
| |
| DEBUG(dbgs() << "BBV: done!\n"); |
| return changed; |
| } |
| |
| virtual bool runOnBasicBlock(BasicBlock &BB) { |
| AA = &getAnalysis<AliasAnalysis>(); |
| SE = &getAnalysis<ScalarEvolution>(); |
| TD = getAnalysisIfAvailable<TargetData>(); |
| |
| return vectorizeBB(BB); |
| } |
| |
| virtual void getAnalysisUsage(AnalysisUsage &AU) const { |
| BasicBlockPass::getAnalysisUsage(AU); |
| AU.addRequired<AliasAnalysis>(); |
| AU.addRequired<ScalarEvolution>(); |
| AU.addPreserved<AliasAnalysis>(); |
| AU.addPreserved<ScalarEvolution>(); |
| AU.setPreservesCFG(); |
| } |
| |
| // This returns the vector type that holds a pair of the provided type. |
| // If the provided type is already a vector, then its length is doubled. |
| static inline VectorType *getVecTypeForPair(Type *ElemTy) { |
| if (VectorType *VTy = dyn_cast<VectorType>(ElemTy)) { |
| unsigned numElem = VTy->getNumElements(); |
| return VectorType::get(ElemTy->getScalarType(), numElem*2); |
| } |
| |
| return VectorType::get(ElemTy, 2); |
| } |
| |
| // Returns the weight associated with the provided value. A chain of |
| // candidate pairs has a length given by the sum of the weights of its |
| // members (one weight per pair; the weight of each member of the pair |
| // is assumed to be the same). This length is then compared to the |
| // chain-length threshold to determine if a given chain is significant |
| // enough to be vectorized. The length is also used in comparing |
| // candidate chains where longer chains are considered to be better. |
| // Note: when this function returns 0, the resulting instructions are |
| // not actually fused. |
| inline size_t getDepthFactor(Value *V) { |
| // InsertElement and ExtractElement have a depth factor of zero. This is |
| // for two reasons: First, they cannot be usefully fused. Second, because |
| // the pass generates a lot of these, they can confuse the simple metric |
| // used to compare the trees in the next iteration. Thus, giving them a |
| // weight of zero allows the pass to essentially ignore them in |
| // subsequent iterations when looking for vectorization opportunities |
| // while still tracking dependency chains that flow through those |
| // instructions. |
| if (isa<InsertElementInst>(V) || isa<ExtractElementInst>(V)) |
| return 0; |
| |
| // Give a load or store half of the required depth so that load/store |
| // pairs will vectorize. |
| if (!Config.NoMemOpBoost && (isa<LoadInst>(V) || isa<StoreInst>(V))) |
| return Config.ReqChainDepth/2; |
| |
| return 1; |
| } |
| |
| // This determines the relative offset of two loads or stores, returning |
| // true if the offset could be determined to be some constant value. |
| // For example, if OffsetInElmts == 1, then J accesses the memory directly |
| // after I; if OffsetInElmts == -1 then I accesses the memory |
| // directly after J. This function assumes that both instructions |
| // have the same type. |
| bool getPairPtrInfo(Instruction *I, Instruction *J, |
| Value *&IPtr, Value *&JPtr, unsigned &IAlignment, unsigned &JAlignment, |
| int64_t &OffsetInElmts) { |
| OffsetInElmts = 0; |
| if (isa<LoadInst>(I)) { |
| IPtr = cast<LoadInst>(I)->getPointerOperand(); |
| JPtr = cast<LoadInst>(J)->getPointerOperand(); |
| IAlignment = cast<LoadInst>(I)->getAlignment(); |
| JAlignment = cast<LoadInst>(J)->getAlignment(); |
| } else { |
| IPtr = cast<StoreInst>(I)->getPointerOperand(); |
| JPtr = cast<StoreInst>(J)->getPointerOperand(); |
| IAlignment = cast<StoreInst>(I)->getAlignment(); |
| JAlignment = cast<StoreInst>(J)->getAlignment(); |
| } |
| |
| const SCEV *IPtrSCEV = SE->getSCEV(IPtr); |
| const SCEV *JPtrSCEV = SE->getSCEV(JPtr); |
| |
| // If this is a trivial offset, then we'll get something like |
| // 1*sizeof(type). With target data, which we need anyway, this will get |
| // constant folded into a number. |
| const SCEV *OffsetSCEV = SE->getMinusSCEV(JPtrSCEV, IPtrSCEV); |
| if (const SCEVConstant *ConstOffSCEV = |
| dyn_cast<SCEVConstant>(OffsetSCEV)) { |
| ConstantInt *IntOff = ConstOffSCEV->getValue(); |
| int64_t Offset = IntOff->getSExtValue(); |
| |
| Type *VTy = cast<PointerType>(IPtr->getType())->getElementType(); |
| int64_t VTyTSS = (int64_t) TD->getTypeStoreSize(VTy); |
| |
| assert(VTy == cast<PointerType>(JPtr->getType())->getElementType()); |
| |
| OffsetInElmts = Offset/VTyTSS; |
| return (abs64(Offset) % VTyTSS) == 0; |
| } |
| |
| return false; |
| } |
| |
| // Returns true if the provided CallInst represents an intrinsic that can |
| // be vectorized. |
| bool isVectorizableIntrinsic(CallInst* I) { |
| Function *F = I->getCalledFunction(); |
| if (!F) return false; |
| |
| unsigned IID = F->getIntrinsicID(); |
| if (!IID) return false; |
| |
| switch(IID) { |
| default: |
| return false; |
| case Intrinsic::sqrt: |
| case Intrinsic::powi: |
| case Intrinsic::sin: |
| case Intrinsic::cos: |
| case Intrinsic::log: |
| case Intrinsic::log2: |
| case Intrinsic::log10: |
| case Intrinsic::exp: |
| case Intrinsic::exp2: |
| case Intrinsic::pow: |
| return Config.VectorizeMath; |
| case Intrinsic::fma: |
| return Config.VectorizeFMA; |
| } |
| } |
| |
| // Returns true if J is the second element in some pair referenced by |
| // some multimap pair iterator pair. |
| template <typename V> |
| bool isSecondInIteratorPair(V J, std::pair< |
| typename std::multimap<V, V>::iterator, |
| typename std::multimap<V, V>::iterator> PairRange) { |
| for (typename std::multimap<V, V>::iterator K = PairRange.first; |
| K != PairRange.second; ++K) |
| if (K->second == J) return true; |
| |
| return false; |
| } |
| }; |
| |
| // This function implements one vectorization iteration on the provided |
| // basic block. It returns true if the block is changed. |
| bool BBVectorize::vectorizePairs(BasicBlock &BB) { |
| bool ShouldContinue; |
| BasicBlock::iterator Start = BB.getFirstInsertionPt(); |
| |
| std::vector<Value *> AllPairableInsts; |
| DenseMap<Value *, Value *> AllChosenPairs; |
| |
| do { |
| std::vector<Value *> PairableInsts; |
| std::multimap<Value *, Value *> CandidatePairs; |
| ShouldContinue = getCandidatePairs(BB, Start, CandidatePairs, |
| PairableInsts); |
| if (PairableInsts.empty()) continue; |
| |
| // Now we have a map of all of the pairable instructions and we need to |
| // select the best possible pairing. A good pairing is one such that the |
| // users of the pair are also paired. This defines a (directed) forest |
| // over the pairs such that two pairs are connected iff the second pair |
| // uses the first. |
| |
| // Note that it only matters that both members of the second pair use some |
| // element of the first pair (to allow for splatting). |
| |
| std::multimap<ValuePair, ValuePair> ConnectedPairs; |
| computeConnectedPairs(CandidatePairs, PairableInsts, ConnectedPairs); |
| if (ConnectedPairs.empty()) continue; |
| |
| // Build the pairable-instruction dependency map |
| DenseSet<ValuePair> PairableInstUsers; |
| buildDepMap(BB, CandidatePairs, PairableInsts, PairableInstUsers); |
| |
| // There is now a graph of the connected pairs. For each variable, pick |
| // the pairing with the largest tree meeting the depth requirement on at |
| // least one branch. Then select all pairings that are part of that tree |
| // and remove them from the list of available pairings and pairable |
| // variables. |
| |
| DenseMap<Value *, Value *> ChosenPairs; |
| choosePairs(CandidatePairs, PairableInsts, ConnectedPairs, |
| PairableInstUsers, ChosenPairs); |
| |
| if (ChosenPairs.empty()) continue; |
| AllPairableInsts.insert(AllPairableInsts.end(), PairableInsts.begin(), |
| PairableInsts.end()); |
| AllChosenPairs.insert(ChosenPairs.begin(), ChosenPairs.end()); |
| } while (ShouldContinue); |
| |
| if (AllChosenPairs.empty()) return false; |
| NumFusedOps += AllChosenPairs.size(); |
| |
| // A set of pairs has now been selected. It is now necessary to replace the |
| // paired instructions with vector instructions. For this procedure each |
| // operand must be replaced with a vector operand. This vector is formed |
| // by using build_vector on the old operands. The replaced values are then |
| // replaced with a vector_extract on the result. Subsequent optimization |
| // passes should coalesce the build/extract combinations. |
| |
| fuseChosenPairs(BB, AllPairableInsts, AllChosenPairs); |
| return true; |
| } |
| |
| // This function returns true if the provided instruction is capable of being |
| // fused into a vector instruction. This determination is based only on the |
| // type and other attributes of the instruction. |
| bool BBVectorize::isInstVectorizable(Instruction *I, |
| bool &IsSimpleLoadStore) { |
| IsSimpleLoadStore = false; |
| |
| if (CallInst *C = dyn_cast<CallInst>(I)) { |
| if (!isVectorizableIntrinsic(C)) |
| return false; |
| } else if (LoadInst *L = dyn_cast<LoadInst>(I)) { |
| // Vectorize simple loads if possbile: |
| IsSimpleLoadStore = L->isSimple(); |
| if (!IsSimpleLoadStore || !Config.VectorizeMemOps) |
| return false; |
| } else if (StoreInst *S = dyn_cast<StoreInst>(I)) { |
| // Vectorize simple stores if possbile: |
| IsSimpleLoadStore = S->isSimple(); |
| if (!IsSimpleLoadStore || !Config.VectorizeMemOps) |
| return false; |
| } else if (CastInst *C = dyn_cast<CastInst>(I)) { |
| // We can vectorize casts, but not casts of pointer types, etc. |
| if (!Config.VectorizeCasts) |
| return false; |
| |
| Type *SrcTy = C->getSrcTy(); |
| if (!SrcTy->isSingleValueType()) |
| return false; |
| |
| Type *DestTy = C->getDestTy(); |
| if (!DestTy->isSingleValueType()) |
| return false; |
| } else if (isa<SelectInst>(I)) { |
| if (!Config.VectorizeSelect) |
| return false; |
| } else if (GetElementPtrInst *G = dyn_cast<GetElementPtrInst>(I)) { |
| if (!Config.VectorizeGEP) |
| return false; |
| |
| // Currently, vector GEPs exist only with one index. |
| if (G->getNumIndices() != 1) |
| return false; |
| } else if (!(I->isBinaryOp() || isa<ShuffleVectorInst>(I) || |
| isa<ExtractElementInst>(I) || isa<InsertElementInst>(I))) { |
| return false; |
| } |
| |
| // We can't vectorize memory operations without target data |
| if (TD == 0 && IsSimpleLoadStore) |
| return false; |
| |
| Type *T1, *T2; |
| if (isa<StoreInst>(I)) { |
| // For stores, it is the value type, not the pointer type that matters |
| // because the value is what will come from a vector register. |
| |
| Value *IVal = cast<StoreInst>(I)->getValueOperand(); |
| T1 = IVal->getType(); |
| } else { |
| T1 = I->getType(); |
| } |
| |
| if (I->isCast()) |
| T2 = cast<CastInst>(I)->getSrcTy(); |
| else |
| T2 = T1; |
| |
| // Not every type can be vectorized... |
| if (!(VectorType::isValidElementType(T1) || T1->isVectorTy()) || |
| !(VectorType::isValidElementType(T2) || T2->isVectorTy())) |
| return false; |
| |
| if (!Config.VectorizeInts |
| && (T1->isIntOrIntVectorTy() || T2->isIntOrIntVectorTy())) |
| return false; |
| |
| if (!Config.VectorizeFloats |
| && (T1->isFPOrFPVectorTy() || T2->isFPOrFPVectorTy())) |
| return false; |
| |
| if ((!Config.VectorizePointers || TD == 0) && |
| (T1->getScalarType()->isPointerTy() || |
| T2->getScalarType()->isPointerTy())) |
| return false; |
| |
| if (T1->getPrimitiveSizeInBits() > Config.VectorBits/2 || |
| T2->getPrimitiveSizeInBits() > Config.VectorBits/2) |
| return false; |
| |
| return true; |
| } |
| |
| // This function returns true if the two provided instructions are compatible |
| // (meaning that they can be fused into a vector instruction). This assumes |
| // that I has already been determined to be vectorizable and that J is not |
| // in the use tree of I. |
| bool BBVectorize::areInstsCompatible(Instruction *I, Instruction *J, |
| bool IsSimpleLoadStore) { |
| DEBUG(if (DebugInstructionExamination) dbgs() << "BBV: looking at " << *I << |
| " <-> " << *J << "\n"); |
| |
| // Loads and stores can be merged if they have different alignments, |
| // but are otherwise the same. |
| LoadInst *LI, *LJ; |
| StoreInst *SI, *SJ; |
| if ((LI = dyn_cast<LoadInst>(I)) && (LJ = dyn_cast<LoadInst>(J))) { |
| if (I->getType() != J->getType()) |
| return false; |
| |
| if (LI->getPointerOperand()->getType() != |
| LJ->getPointerOperand()->getType() || |
| LI->isVolatile() != LJ->isVolatile() || |
| LI->getOrdering() != LJ->getOrdering() || |
| LI->getSynchScope() != LJ->getSynchScope()) |
| return false; |
| } else if ((SI = dyn_cast<StoreInst>(I)) && (SJ = dyn_cast<StoreInst>(J))) { |
| if (SI->getValueOperand()->getType() != |
| SJ->getValueOperand()->getType() || |
| SI->getPointerOperand()->getType() != |
| SJ->getPointerOperand()->getType() || |
| SI->isVolatile() != SJ->isVolatile() || |
| SI->getOrdering() != SJ->getOrdering() || |
| SI->getSynchScope() != SJ->getSynchScope()) |
| return false; |
| } else if (!J->isSameOperationAs(I)) { |
| return false; |
| } |
| // FIXME: handle addsub-type operations! |
| |
| if (IsSimpleLoadStore) { |
| Value *IPtr, *JPtr; |
| unsigned IAlignment, JAlignment; |
| int64_t OffsetInElmts = 0; |
| if (getPairPtrInfo(I, J, IPtr, JPtr, IAlignment, JAlignment, |
| OffsetInElmts) && abs64(OffsetInElmts) == 1) { |
| if (Config.AlignedOnly) { |
| Type *aType = isa<StoreInst>(I) ? |
| cast<StoreInst>(I)->getValueOperand()->getType() : I->getType(); |
| // An aligned load or store is possible only if the instruction |
| // with the lower offset has an alignment suitable for the |
| // vector type. |
| |
| unsigned BottomAlignment = IAlignment; |
| if (OffsetInElmts < 0) BottomAlignment = JAlignment; |
| |
| Type *VType = getVecTypeForPair(aType); |
| unsigned VecAlignment = TD->getPrefTypeAlignment(VType); |
| if (BottomAlignment < VecAlignment) |
| return false; |
| } |
| } else { |
| return false; |
| } |
| } else if (isa<ShuffleVectorInst>(I)) { |
| // Only merge two shuffles if they're both constant |
| return isa<Constant>(I->getOperand(2)) && |
| isa<Constant>(J->getOperand(2)); |
| // FIXME: We may want to vectorize non-constant shuffles also. |
| } |
| |
| // The powi intrinsic is special because only the first argument is |
| // vectorized, the second arguments must be equal. |
| CallInst *CI = dyn_cast<CallInst>(I); |
| Function *FI; |
| if (CI && (FI = CI->getCalledFunction()) && |
| FI->getIntrinsicID() == Intrinsic::powi) { |
| |
| Value *A1I = CI->getArgOperand(1), |
| *A1J = cast<CallInst>(J)->getArgOperand(1); |
| const SCEV *A1ISCEV = SE->getSCEV(A1I), |
| *A1JSCEV = SE->getSCEV(A1J); |
| return (A1ISCEV == A1JSCEV); |
| } |
| |
| return true; |
| } |
| |
| // Figure out whether or not J uses I and update the users and write-set |
| // structures associated with I. Specifically, Users represents the set of |
| // instructions that depend on I. WriteSet represents the set |
| // of memory locations that are dependent on I. If UpdateUsers is true, |
| // and J uses I, then Users is updated to contain J and WriteSet is updated |
| // to contain any memory locations to which J writes. The function returns |
| // true if J uses I. By default, alias analysis is used to determine |
| // whether J reads from memory that overlaps with a location in WriteSet. |
| // If LoadMoveSet is not null, then it is a previously-computed multimap |
| // where the key is the memory-based user instruction and the value is |
| // the instruction to be compared with I. So, if LoadMoveSet is provided, |
| // then the alias analysis is not used. This is necessary because this |
| // function is called during the process of moving instructions during |
| // vectorization and the results of the alias analysis are not stable during |
| // that process. |
| bool BBVectorize::trackUsesOfI(DenseSet<Value *> &Users, |
| AliasSetTracker &WriteSet, Instruction *I, |
| Instruction *J, bool UpdateUsers, |
| std::multimap<Value *, Value *> *LoadMoveSet) { |
| bool UsesI = false; |
| |
| // This instruction may already be marked as a user due, for example, to |
| // being a member of a selected pair. |
| if (Users.count(J)) |
| UsesI = true; |
| |
| if (!UsesI) |
| for (User::op_iterator JU = J->op_begin(), JE = J->op_end(); |
| JU != JE; ++JU) { |
| Value *V = *JU; |
| if (I == V || Users.count(V)) { |
| UsesI = true; |
| break; |
| } |
| } |
| if (!UsesI && J->mayReadFromMemory()) { |
| if (LoadMoveSet) { |
| VPIteratorPair JPairRange = LoadMoveSet->equal_range(J); |
| UsesI = isSecondInIteratorPair<Value*>(I, JPairRange); |
| } else { |
| for (AliasSetTracker::iterator W = WriteSet.begin(), |
| WE = WriteSet.end(); W != WE; ++W) { |
| if (W->aliasesUnknownInst(J, *AA)) { |
| UsesI = true; |
| break; |
| } |
| } |
| } |
| } |
| |
| if (UsesI && UpdateUsers) { |
| if (J->mayWriteToMemory()) WriteSet.add(J); |
| Users.insert(J); |
| } |
| |
| return UsesI; |
| } |
| |
| // This function iterates over all instruction pairs in the provided |
| // basic block and collects all candidate pairs for vectorization. |
| bool BBVectorize::getCandidatePairs(BasicBlock &BB, |
| BasicBlock::iterator &Start, |
| std::multimap<Value *, Value *> &CandidatePairs, |
| std::vector<Value *> &PairableInsts) { |
| BasicBlock::iterator E = BB.end(); |
| if (Start == E) return false; |
| |
| bool ShouldContinue = false, IAfterStart = false; |
| for (BasicBlock::iterator I = Start++; I != E; ++I) { |
| if (I == Start) IAfterStart = true; |
| |
| bool IsSimpleLoadStore; |
| if (!isInstVectorizable(I, IsSimpleLoadStore)) continue; |
| |
| // Look for an instruction with which to pair instruction *I... |
| DenseSet<Value *> Users; |
| AliasSetTracker WriteSet(*AA); |
| bool JAfterStart = IAfterStart; |
| BasicBlock::iterator J = llvm::next(I); |
| for (unsigned ss = 0; J != E && ss <= Config.SearchLimit; ++J, ++ss) { |
| if (J == Start) JAfterStart = true; |
| |
| // Determine if J uses I, if so, exit the loop. |
| bool UsesI = trackUsesOfI(Users, WriteSet, I, J, !Config.FastDep); |
| if (Config.FastDep) { |
| // Note: For this heuristic to be effective, independent operations |
| // must tend to be intermixed. This is likely to be true from some |
| // kinds of grouped loop unrolling (but not the generic LLVM pass), |
| // but otherwise may require some kind of reordering pass. |
| |
| // When using fast dependency analysis, |
| // stop searching after first use: |
| if (UsesI) break; |
| } else { |
| if (UsesI) continue; |
| } |
| |
| // J does not use I, and comes before the first use of I, so it can be |
| // merged with I if the instructions are compatible. |
| if (!areInstsCompatible(I, J, IsSimpleLoadStore)) continue; |
| |
| // J is a candidate for merging with I. |
| if (!PairableInsts.size() || |
| PairableInsts[PairableInsts.size()-1] != I) { |
| PairableInsts.push_back(I); |
| } |
| |
| CandidatePairs.insert(ValuePair(I, J)); |
| |
| // The next call to this function must start after the last instruction |
| // selected during this invocation. |
| if (JAfterStart) { |
| Start = llvm::next(J); |
| IAfterStart = JAfterStart = false; |
| } |
| |
| DEBUG(if (DebugCandidateSelection) dbgs() << "BBV: candidate pair " |
| << *I << " <-> " << *J << "\n"); |
| |
| // If we have already found too many pairs, break here and this function |
| // will be called again starting after the last instruction selected |
| // during this invocation. |
| if (PairableInsts.size() >= Config.MaxInsts) { |
| ShouldContinue = true; |
| break; |
| } |
| } |
| |
| if (ShouldContinue) |
| break; |
| } |
| |
| DEBUG(dbgs() << "BBV: found " << PairableInsts.size() |
| << " instructions with candidate pairs\n"); |
| |
| return ShouldContinue; |
| } |
| |
| // Finds candidate pairs connected to the pair P = <PI, PJ>. This means that |
| // it looks for pairs such that both members have an input which is an |
| // output of PI or PJ. |
| void BBVectorize::computePairsConnectedTo( |
| std::multimap<Value *, Value *> &CandidatePairs, |
| std::vector<Value *> &PairableInsts, |
| std::multimap<ValuePair, ValuePair> &ConnectedPairs, |
| ValuePair P) { |
| StoreInst *SI, *SJ; |
| |
| // For each possible pairing for this variable, look at the uses of |
| // the first value... |
| for (Value::use_iterator I = P.first->use_begin(), |
| E = P.first->use_end(); I != E; ++I) { |
| if (isa<LoadInst>(*I)) { |
| // A pair cannot be connected to a load because the load only takes one |
| // operand (the address) and it is a scalar even after vectorization. |
| continue; |
| } else if ((SI = dyn_cast<StoreInst>(*I)) && |
| P.first == SI->getPointerOperand()) { |
| // Similarly, a pair cannot be connected to a store through its |
| // pointer operand. |
| continue; |
| } |
| |
| VPIteratorPair IPairRange = CandidatePairs.equal_range(*I); |
| |
| // For each use of the first variable, look for uses of the second |
| // variable... |
| for (Value::use_iterator J = P.second->use_begin(), |
| E2 = P.second->use_end(); J != E2; ++J) { |
| if ((SJ = dyn_cast<StoreInst>(*J)) && |
| P.second == SJ->getPointerOperand()) |
| continue; |
| |
| VPIteratorPair JPairRange = CandidatePairs.equal_range(*J); |
| |
| // Look for <I, J>: |
| if (isSecondInIteratorPair<Value*>(*J, IPairRange)) |
| ConnectedPairs.insert(VPPair(P, ValuePair(*I, *J))); |
| |
| // Look for <J, I>: |
| if (isSecondInIteratorPair<Value*>(*I, JPairRange)) |
| ConnectedPairs.insert(VPPair(P, ValuePair(*J, *I))); |
| } |
| |
| if (Config.SplatBreaksChain) continue; |
| // Look for cases where just the first value in the pair is used by |
| // both members of another pair (splatting). |
| for (Value::use_iterator J = P.first->use_begin(); J != E; ++J) { |
| if ((SJ = dyn_cast<StoreInst>(*J)) && |
| P.first == SJ->getPointerOperand()) |
| continue; |
| |
| if (isSecondInIteratorPair<Value*>(*J, IPairRange)) |
| ConnectedPairs.insert(VPPair(P, ValuePair(*I, *J))); |
| } |
| } |
| |
| if (Config.SplatBreaksChain) return; |
| // Look for cases where just the second value in the pair is used by |
| // both members of another pair (splatting). |
| for (Value::use_iterator I = P.second->use_begin(), |
| E = P.second->use_end(); I != E; ++I) { |
| if (isa<LoadInst>(*I)) |
| continue; |
| else if ((SI = dyn_cast<StoreInst>(*I)) && |
| P.second == SI->getPointerOperand()) |
| continue; |
| |
| VPIteratorPair IPairRange = CandidatePairs.equal_range(*I); |
| |
| for (Value::use_iterator J = P.second->use_begin(); J != E; ++J) { |
| if ((SJ = dyn_cast<StoreInst>(*J)) && |
| P.second == SJ->getPointerOperand()) |
| continue; |
| |
| if (isSecondInIteratorPair<Value*>(*J, IPairRange)) |
| ConnectedPairs.insert(VPPair(P, ValuePair(*I, *J))); |
| } |
| } |
| } |
| |
| // This function figures out which pairs are connected. Two pairs are |
| // connected if some output of the first pair forms an input to both members |
| // of the second pair. |
| void BBVectorize::computeConnectedPairs( |
| std::multimap<Value *, Value *> &CandidatePairs, |
| std::vector<Value *> &PairableInsts, |
| std::multimap<ValuePair, ValuePair> &ConnectedPairs) { |
| |
| for (std::vector<Value *>::iterator PI = PairableInsts.begin(), |
| PE = PairableInsts.end(); PI != PE; ++PI) { |
| VPIteratorPair choiceRange = CandidatePairs.equal_range(*PI); |
| |
| for (std::multimap<Value *, Value *>::iterator P = choiceRange.first; |
| P != choiceRange.second; ++P) |
| computePairsConnectedTo(CandidatePairs, PairableInsts, |
| ConnectedPairs, *P); |
| } |
| |
| DEBUG(dbgs() << "BBV: found " << ConnectedPairs.size() |
| << " pair connections.\n"); |
| } |
| |
| // This function builds a set of use tuples such that <A, B> is in the set |
| // if B is in the use tree of A. If B is in the use tree of A, then B |
| // depends on the output of A. |
| void BBVectorize::buildDepMap( |
| BasicBlock &BB, |
| std::multimap<Value *, Value *> &CandidatePairs, |
| std::vector<Value *> &PairableInsts, |
| DenseSet<ValuePair> &PairableInstUsers) { |
| DenseSet<Value *> IsInPair; |
| for (std::multimap<Value *, Value *>::iterator C = CandidatePairs.begin(), |
| E = CandidatePairs.end(); C != E; ++C) { |
| IsInPair.insert(C->first); |
| IsInPair.insert(C->second); |
| } |
| |
| // Iterate through the basic block, recording all Users of each |
| // pairable instruction. |
| |
| BasicBlock::iterator E = BB.end(); |
| for (BasicBlock::iterator I = BB.getFirstInsertionPt(); I != E; ++I) { |
| if (IsInPair.find(I) == IsInPair.end()) continue; |
| |
| DenseSet<Value *> Users; |
| AliasSetTracker WriteSet(*AA); |
| for (BasicBlock::iterator J = llvm::next(I); J != E; ++J) |
| (void) trackUsesOfI(Users, WriteSet, I, J); |
| |
| for (DenseSet<Value *>::iterator U = Users.begin(), E = Users.end(); |
| U != E; ++U) |
| PairableInstUsers.insert(ValuePair(I, *U)); |
| } |
| } |
| |
| // Returns true if an input to pair P is an output of pair Q and also an |
| // input of pair Q is an output of pair P. If this is the case, then these |
| // two pairs cannot be simultaneously fused. |
| bool BBVectorize::pairsConflict(ValuePair P, ValuePair Q, |
| DenseSet<ValuePair> &PairableInstUsers, |
| std::multimap<ValuePair, ValuePair> *PairableInstUserMap) { |
| // Two pairs are in conflict if they are mutual Users of eachother. |
| bool QUsesP = PairableInstUsers.count(ValuePair(P.first, Q.first)) || |
| PairableInstUsers.count(ValuePair(P.first, Q.second)) || |
| PairableInstUsers.count(ValuePair(P.second, Q.first)) || |
| PairableInstUsers.count(ValuePair(P.second, Q.second)); |
| bool PUsesQ = PairableInstUsers.count(ValuePair(Q.first, P.first)) || |
| PairableInstUsers.count(ValuePair(Q.first, P.second)) || |
| PairableInstUsers.count(ValuePair(Q.second, P.first)) || |
| PairableInstUsers.count(ValuePair(Q.second, P.second)); |
| if (PairableInstUserMap) { |
| // FIXME: The expensive part of the cycle check is not so much the cycle |
| // check itself but this edge insertion procedure. This needs some |
| // profiling and probably a different data structure (same is true of |
| // most uses of std::multimap). |
| if (PUsesQ) { |
| VPPIteratorPair QPairRange = PairableInstUserMap->equal_range(Q); |
| if (!isSecondInIteratorPair(P, QPairRange)) |
| PairableInstUserMap->insert(VPPair(Q, P)); |
| } |
| if (QUsesP) { |
| VPPIteratorPair PPairRange = PairableInstUserMap->equal_range(P); |
| if (!isSecondInIteratorPair(Q, PPairRange)) |
| PairableInstUserMap->insert(VPPair(P, Q)); |
| } |
| } |
| |
| return (QUsesP && PUsesQ); |
| } |
| |
| // This function walks the use graph of current pairs to see if, starting |
| // from P, the walk returns to P. |
| bool BBVectorize::pairWillFormCycle(ValuePair P, |
| std::multimap<ValuePair, ValuePair> &PairableInstUserMap, |
| DenseSet<ValuePair> &CurrentPairs) { |
| DEBUG(if (DebugCycleCheck) |
| dbgs() << "BBV: starting cycle check for : " << *P.first << " <-> " |
| << *P.second << "\n"); |
| // A lookup table of visisted pairs is kept because the PairableInstUserMap |
| // contains non-direct associations. |
| DenseSet<ValuePair> Visited; |
| SmallVector<ValuePair, 32> Q; |
| // General depth-first post-order traversal: |
| Q.push_back(P); |
| do { |
| ValuePair QTop = Q.pop_back_val(); |
| Visited.insert(QTop); |
| |
| DEBUG(if (DebugCycleCheck) |
| dbgs() << "BBV: cycle check visiting: " << *QTop.first << " <-> " |
| << *QTop.second << "\n"); |
| VPPIteratorPair QPairRange = PairableInstUserMap.equal_range(QTop); |
| for (std::multimap<ValuePair, ValuePair>::iterator C = QPairRange.first; |
| C != QPairRange.second; ++C) { |
| if (C->second == P) { |
| DEBUG(dbgs() |
| << "BBV: rejected to prevent non-trivial cycle formation: " |
| << *C->first.first << " <-> " << *C->first.second << "\n"); |
| return true; |
| } |
| |
| if (CurrentPairs.count(C->second) && !Visited.count(C->second)) |
| Q.push_back(C->second); |
| } |
| } while (!Q.empty()); |
| |
| return false; |
| } |
| |
| // This function builds the initial tree of connected pairs with the |
| // pair J at the root. |
| void BBVectorize::buildInitialTreeFor( |
| std::multimap<Value *, Value *> &CandidatePairs, |
| std::vector<Value *> &PairableInsts, |
| std::multimap<ValuePair, ValuePair> &ConnectedPairs, |
| DenseSet<ValuePair> &PairableInstUsers, |
| DenseMap<Value *, Value *> &ChosenPairs, |
| DenseMap<ValuePair, size_t> &Tree, ValuePair J) { |
| // Each of these pairs is viewed as the root node of a Tree. The Tree |
| // is then walked (depth-first). As this happens, we keep track of |
| // the pairs that compose the Tree and the maximum depth of the Tree. |
| SmallVector<ValuePairWithDepth, 32> Q; |
| // General depth-first post-order traversal: |
| Q.push_back(ValuePairWithDepth(J, getDepthFactor(J.first))); |
| do { |
| ValuePairWithDepth QTop = Q.back(); |
| |
| // Push each child onto the queue: |
| bool MoreChildren = false; |
| size_t MaxChildDepth = QTop.second; |
| VPPIteratorPair qtRange = ConnectedPairs.equal_range(QTop.first); |
| for (std::multimap<ValuePair, ValuePair>::iterator k = qtRange.first; |
| k != qtRange.second; ++k) { |
| // Make sure that this child pair is still a candidate: |
| bool IsStillCand = false; |
| VPIteratorPair checkRange = |
| CandidatePairs.equal_range(k->second.first); |
| for (std::multimap<Value *, Value *>::iterator m = checkRange.first; |
| m != checkRange.second; ++m) { |
| if (m->second == k->second.second) { |
| IsStillCand = true; |
| break; |
| } |
| } |
| |
| if (IsStillCand) { |
| DenseMap<ValuePair, size_t>::iterator C = Tree.find(k->second); |
| if (C == Tree.end()) { |
| size_t d = getDepthFactor(k->second.first); |
| Q.push_back(ValuePairWithDepth(k->second, QTop.second+d)); |
| MoreChildren = true; |
| } else { |
| MaxChildDepth = std::max(MaxChildDepth, C->second); |
| } |
| } |
| } |
| |
| if (!MoreChildren) { |
| // Record the current pair as part of the Tree: |
| Tree.insert(ValuePairWithDepth(QTop.first, MaxChildDepth)); |
| Q.pop_back(); |
| } |
| } while (!Q.empty()); |
| } |
| |
| // Given some initial tree, prune it by removing conflicting pairs (pairs |
| // that cannot be simultaneously chosen for vectorization). |
| void BBVectorize::pruneTreeFor( |
| std::multimap<Value *, Value *> &CandidatePairs, |
| std::vector<Value *> &PairableInsts, |
| std::multimap<ValuePair, ValuePair> &ConnectedPairs, |
| DenseSet<ValuePair> &PairableInstUsers, |
| std::multimap<ValuePair, ValuePair> &PairableInstUserMap, |
| DenseMap<Value *, Value *> &ChosenPairs, |
| DenseMap<ValuePair, size_t> &Tree, |
| DenseSet<ValuePair> &PrunedTree, ValuePair J, |
| bool UseCycleCheck) { |
| SmallVector<ValuePairWithDepth, 32> Q; |
| // General depth-first post-order traversal: |
| Q.push_back(ValuePairWithDepth(J, getDepthFactor(J.first))); |
| do { |
| ValuePairWithDepth QTop = Q.pop_back_val(); |
| PrunedTree.insert(QTop.first); |
| |
| // Visit each child, pruning as necessary... |
| DenseMap<ValuePair, size_t> BestChildren; |
| VPPIteratorPair QTopRange = ConnectedPairs.equal_range(QTop.first); |
| for (std::multimap<ValuePair, ValuePair>::iterator K = QTopRange.first; |
| K != QTopRange.second; ++K) { |
| DenseMap<ValuePair, size_t>::iterator C = Tree.find(K->second); |
| if (C == Tree.end()) continue; |
| |
| // This child is in the Tree, now we need to make sure it is the |
| // best of any conflicting children. There could be multiple |
| // conflicting children, so first, determine if we're keeping |
| // this child, then delete conflicting children as necessary. |
| |
| // It is also necessary to guard against pairing-induced |
| // dependencies. Consider instructions a .. x .. y .. b |
| // such that (a,b) are to be fused and (x,y) are to be fused |
| // but a is an input to x and b is an output from y. This |
| // means that y cannot be moved after b but x must be moved |
| // after b for (a,b) to be fused. In other words, after |
| // fusing (a,b) we have y .. a/b .. x where y is an input |
| // to a/b and x is an output to a/b: x and y can no longer |
| // be legally fused. To prevent this condition, we must |
| // make sure that a child pair added to the Tree is not |
| // both an input and output of an already-selected pair. |
| |
| // Pairing-induced dependencies can also form from more complicated |
| // cycles. The pair vs. pair conflicts are easy to check, and so |
| // that is done explicitly for "fast rejection", and because for |
| // child vs. child conflicts, we may prefer to keep the current |
| // pair in preference to the already-selected child. |
| DenseSet<ValuePair> CurrentPairs; |
| |
| bool CanAdd = true; |
| for (DenseMap<ValuePair, size_t>::iterator C2 |
| = BestChildren.begin(), E2 = BestChildren.end(); |
| C2 != E2; ++C2) { |
| if (C2->first.first == C->first.first || |
| C2->first.first == C->first.second || |
| C2->first.second == C->first.first || |
| C2->first.second == C->first.second || |
| pairsConflict(C2->first, C->first, PairableInstUsers, |
| UseCycleCheck ? &PairableInstUserMap : 0)) { |
| if (C2->second >= C->second) { |
| CanAdd = false; |
| break; |
| } |
| |
| CurrentPairs.insert(C2->first); |
| } |
| } |
| if (!CanAdd) continue; |
| |
| // Even worse, this child could conflict with another node already |
| // selected for the Tree. If that is the case, ignore this child. |
| for (DenseSet<ValuePair>::iterator T = PrunedTree.begin(), |
| E2 = PrunedTree.end(); T != E2; ++T) { |
| if (T->first == C->first.first || |
| T->first == C->first.second || |
| T->second == C->first.first || |
| T->second == C->first.second || |
| pairsConflict(*T, C->first, PairableInstUsers, |
| UseCycleCheck ? &PairableInstUserMap : 0)) { |
| CanAdd = false; |
| break; |
| } |
| |
| CurrentPairs.insert(*T); |
| } |
| if (!CanAdd) continue; |
| |
| // And check the queue too... |
| for (SmallVector<ValuePairWithDepth, 32>::iterator C2 = Q.begin(), |
| E2 = Q.end(); C2 != E2; ++C2) { |
| if (C2->first.first == C->first.first || |
| C2->first.first == C->first.second || |
| C2->first.second == C->first.first || |
| C2->first.second == C->first.second || |
| pairsConflict(C2->first, C->first, PairableInstUsers, |
| UseCycleCheck ? &PairableInstUserMap : 0)) { |
| CanAdd = false; |
| break; |
| } |
| |
| CurrentPairs.insert(C2->first); |
| } |
| if (!CanAdd) continue; |
| |
| // Last but not least, check for a conflict with any of the |
| // already-chosen pairs. |
| for (DenseMap<Value *, Value *>::iterator C2 = |
| ChosenPairs.begin(), E2 = ChosenPairs.end(); |
| C2 != E2; ++C2) { |
| if (pairsConflict(*C2, C->first, PairableInstUsers, |
| UseCycleCheck ? &PairableInstUserMap : 0)) { |
| CanAdd = false; |
| break; |
| } |
| |
| CurrentPairs.insert(*C2); |
| } |
| if (!CanAdd) continue; |
| |
| // To check for non-trivial cycles formed by the addition of the |
| // current pair we've formed a list of all relevant pairs, now use a |
| // graph walk to check for a cycle. We start from the current pair and |
| // walk the use tree to see if we again reach the current pair. If we |
| // do, then the current pair is rejected. |
| |
| // FIXME: It may be more efficient to use a topological-ordering |
| // algorithm to improve the cycle check. This should be investigated. |
| if (UseCycleCheck && |
| pairWillFormCycle(C->first, PairableInstUserMap, CurrentPairs)) |
| continue; |
| |
| // This child can be added, but we may have chosen it in preference |
| // to an already-selected child. Check for this here, and if a |
| // conflict is found, then remove the previously-selected child |
| // before adding this one in its place. |
| for (DenseMap<ValuePair, size_t>::iterator C2 |
| = BestChildren.begin(); C2 != BestChildren.end();) { |
| if (C2->first.first == C->first.first || |
| C2->first.first == C->first.second || |
| C2->first.second == C->first.first || |
| C2->first.second == C->first.second || |
| pairsConflict(C2->first, C->first, PairableInstUsers)) |
| BestChildren.erase(C2++); |
| else |
| ++C2; |
| } |
| |
| BestChildren.insert(ValuePairWithDepth(C->first, C->second)); |
| } |
| |
| for (DenseMap<ValuePair, size_t>::iterator C |
| = BestChildren.begin(), E2 = BestChildren.end(); |
| C != E2; ++C) { |
| size_t DepthF = getDepthFactor(C->first.first); |
| Q.push_back(ValuePairWithDepth(C->first, QTop.second+DepthF)); |
| } |
| } while (!Q.empty()); |
| } |
| |
| // This function finds the best tree of mututally-compatible connected |
| // pairs, given the choice of root pairs as an iterator range. |
| void BBVectorize::findBestTreeFor( |
| std::multimap<Value *, Value *> &CandidatePairs, |
| std::vector<Value *> &PairableInsts, |
| std::multimap<ValuePair, ValuePair> &ConnectedPairs, |
| DenseSet<ValuePair> &PairableInstUsers, |
| std::multimap<ValuePair, ValuePair> &PairableInstUserMap, |
| DenseMap<Value *, Value *> &ChosenPairs, |
| DenseSet<ValuePair> &BestTree, size_t &BestMaxDepth, |
| size_t &BestEffSize, VPIteratorPair ChoiceRange, |
| bool UseCycleCheck) { |
| for (std::multimap<Value *, Value *>::iterator J = ChoiceRange.first; |
| J != ChoiceRange.second; ++J) { |
| |
| // Before going any further, make sure that this pair does not |
| // conflict with any already-selected pairs (see comment below |
| // near the Tree pruning for more details). |
| DenseSet<ValuePair> ChosenPairSet; |
| bool DoesConflict = false; |
| for (DenseMap<Value *, Value *>::iterator C = ChosenPairs.begin(), |
| E = ChosenPairs.end(); C != E; ++C) { |
| if (pairsConflict(*C, *J, PairableInstUsers, |
| UseCycleCheck ? &PairableInstUserMap : 0)) { |
| DoesConflict = true; |
| break; |
| } |
| |
| ChosenPairSet.insert(*C); |
| } |
| if (DoesConflict) continue; |
| |
| if (UseCycleCheck && |
| pairWillFormCycle(*J, PairableInstUserMap, ChosenPairSet)) |
| continue; |
| |
| DenseMap<ValuePair, size_t> Tree; |
| buildInitialTreeFor(CandidatePairs, PairableInsts, ConnectedPairs, |
| PairableInstUsers, ChosenPairs, Tree, *J); |
| |
| // Because we'll keep the child with the largest depth, the largest |
| // depth is still the same in the unpruned Tree. |
| size_t MaxDepth = Tree.lookup(*J); |
| |
| DEBUG(if (DebugPairSelection) dbgs() << "BBV: found Tree for pair {" |
| << *J->first << " <-> " << *J->second << "} of depth " << |
| MaxDepth << " and size " << Tree.size() << "\n"); |
| |
| // At this point the Tree has been constructed, but, may contain |
| // contradictory children (meaning that different children of |
| // some tree node may be attempting to fuse the same instruction). |
| // So now we walk the tree again, in the case of a conflict, |
| // keep only the child with the largest depth. To break a tie, |
| // favor the first child. |
| |
| DenseSet<ValuePair> PrunedTree; |
| pruneTreeFor(CandidatePairs, PairableInsts, ConnectedPairs, |
| PairableInstUsers, PairableInstUserMap, ChosenPairs, Tree, |
| PrunedTree, *J, UseCycleCheck); |
| |
| size_t EffSize = 0; |
| for (DenseSet<ValuePair>::iterator S = PrunedTree.begin(), |
| E = PrunedTree.end(); S != E; ++S) |
| EffSize += getDepthFactor(S->first); |
| |
| DEBUG(if (DebugPairSelection) |
| dbgs() << "BBV: found pruned Tree for pair {" |
| << *J->first << " <-> " << *J->second << "} of depth " << |
| MaxDepth << " and size " << PrunedTree.size() << |
| " (effective size: " << EffSize << ")\n"); |
| if (MaxDepth >= Config.ReqChainDepth && EffSize > BestEffSize) { |
| BestMaxDepth = MaxDepth; |
| BestEffSize = EffSize; |
| BestTree = PrunedTree; |
| } |
| } |
| } |
| |
| // Given the list of candidate pairs, this function selects those |
| // that will be fused into vector instructions. |
| void BBVectorize::choosePairs( |
| std::multimap<Value *, Value *> &CandidatePairs, |
| std::vector<Value *> &PairableInsts, |
| std::multimap<ValuePair, ValuePair> &ConnectedPairs, |
| DenseSet<ValuePair> &PairableInstUsers, |
| DenseMap<Value *, Value *>& ChosenPairs) { |
| bool UseCycleCheck = |
| CandidatePairs.size() <= Config.MaxCandPairsForCycleCheck; |
| std::multimap<ValuePair, ValuePair> PairableInstUserMap; |
| for (std::vector<Value *>::iterator I = PairableInsts.begin(), |
| E = PairableInsts.end(); I != E; ++I) { |
| // The number of possible pairings for this variable: |
| size_t NumChoices = CandidatePairs.count(*I); |
| if (!NumChoices) continue; |
| |
| VPIteratorPair ChoiceRange = CandidatePairs.equal_range(*I); |
| |
| // The best pair to choose and its tree: |
| size_t BestMaxDepth = 0, BestEffSize = 0; |
| DenseSet<ValuePair> BestTree; |
| findBestTreeFor(CandidatePairs, PairableInsts, ConnectedPairs, |
| PairableInstUsers, PairableInstUserMap, ChosenPairs, |
| BestTree, BestMaxDepth, BestEffSize, ChoiceRange, |
| UseCycleCheck); |
| |
| // A tree has been chosen (or not) at this point. If no tree was |
| // chosen, then this instruction, I, cannot be paired (and is no longer |
| // considered). |
| |
| DEBUG(if (BestTree.size() > 0) |
| dbgs() << "BBV: selected pairs in the best tree for: " |
| << *cast<Instruction>(*I) << "\n"); |
| |
| for (DenseSet<ValuePair>::iterator S = BestTree.begin(), |
| SE2 = BestTree.end(); S != SE2; ++S) { |
| // Insert the members of this tree into the list of chosen pairs. |
| ChosenPairs.insert(ValuePair(S->first, S->second)); |
| DEBUG(dbgs() << "BBV: selected pair: " << *S->first << " <-> " << |
| *S->second << "\n"); |
| |
| // Remove all candidate pairs that have values in the chosen tree. |
| for (std::multimap<Value *, Value *>::iterator K = |
| CandidatePairs.begin(); K != CandidatePairs.end();) { |
| if (K->first == S->first || K->second == S->first || |
| K->second == S->second || K->first == S->second) { |
| // Don't remove the actual pair chosen so that it can be used |
| // in subsequent tree selections. |
| if (!(K->first == S->first && K->second == S->second)) |
| CandidatePairs.erase(K++); |
| else |
| ++K; |
| } else { |
| ++K; |
| } |
| } |
| } |
| } |
| |
| DEBUG(dbgs() << "BBV: selected " << ChosenPairs.size() << " pairs.\n"); |
| } |
| |
| std::string getReplacementName(Instruction *I, bool IsInput, unsigned o, |
| unsigned n = 0) { |
| if (!I->hasName()) |
| return ""; |
| |
| return (I->getName() + (IsInput ? ".v.i" : ".v.r") + utostr(o) + |
| (n > 0 ? "." + utostr(n) : "")).str(); |
| } |
| |
| // Returns the value that is to be used as the pointer input to the vector |
| // instruction that fuses I with J. |
| Value *BBVectorize::getReplacementPointerInput(LLVMContext& Context, |
| Instruction *I, Instruction *J, unsigned o, |
| bool &FlipMemInputs) { |
| Value *IPtr, *JPtr; |
| unsigned IAlignment, JAlignment; |
| int64_t OffsetInElmts; |
| (void) getPairPtrInfo(I, J, IPtr, JPtr, IAlignment, JAlignment, |
| OffsetInElmts); |
| |
| // The pointer value is taken to be the one with the lowest offset. |
| Value *VPtr; |
| if (OffsetInElmts > 0) { |
| VPtr = IPtr; |
| } else { |
| FlipMemInputs = true; |
| VPtr = JPtr; |
| } |
| |
| Type *ArgType = cast<PointerType>(IPtr->getType())->getElementType(); |
| Type *VArgType = getVecTypeForPair(ArgType); |
| Type *VArgPtrType = PointerType::get(VArgType, |
| cast<PointerType>(IPtr->getType())->getAddressSpace()); |
| return new BitCastInst(VPtr, VArgPtrType, getReplacementName(I, true, o), |
| /* insert before */ FlipMemInputs ? J : I); |
| } |
| |
| void BBVectorize::fillNewShuffleMask(LLVMContext& Context, Instruction *J, |
| unsigned NumElem, unsigned MaskOffset, unsigned NumInElem, |
| unsigned IdxOffset, std::vector<Constant*> &Mask) { |
| for (unsigned v = 0; v < NumElem/2; ++v) { |
| int m = cast<ShuffleVectorInst>(J)->getMaskValue(v); |
| if (m < 0) { |
| Mask[v+MaskOffset] = UndefValue::get(Type::getInt32Ty(Context)); |
| } else { |
| unsigned mm = m + (int) IdxOffset; |
| if (m >= (int) NumInElem) |
| mm += (int) NumInElem; |
| |
| Mask[v+MaskOffset] = |
| ConstantInt::get(Type::getInt32Ty(Context), mm); |
| } |
| } |
| } |
| |
| // Returns the value that is to be used as the vector-shuffle mask to the |
| // vector instruction that fuses I with J. |
| Value *BBVectorize::getReplacementShuffleMask(LLVMContext& Context, |
| Instruction *I, Instruction *J) { |
| // This is the shuffle mask. We need to append the second |
| // mask to the first, and the numbers need to be adjusted. |
| |
| Type *ArgType = I->getType(); |
| Type *VArgType = getVecTypeForPair(ArgType); |
| |
| // Get the total number of elements in the fused vector type. |
| // By definition, this must equal the number of elements in |
| // the final mask. |
| unsigned NumElem = cast<VectorType>(VArgType)->getNumElements(); |
| std::vector<Constant*> Mask(NumElem); |
| |
| Type *OpType = I->getOperand(0)->getType(); |
| unsigned NumInElem = cast<VectorType>(OpType)->getNumElements(); |
| |
| // For the mask from the first pair... |
| fillNewShuffleMask(Context, I, NumElem, 0, NumInElem, 0, Mask); |
| |
| // For the mask from the second pair... |
| fillNewShuffleMask(Context, J, NumElem, NumElem/2, NumInElem, NumInElem, |
| Mask); |
| |
| return ConstantVector::get(Mask); |
| } |
| |
| // Returns the value to be used as the specified operand of the vector |
| // instruction that fuses I with J. |
| Value *BBVectorize::getReplacementInput(LLVMContext& Context, Instruction *I, |
| Instruction *J, unsigned o, bool FlipMemInputs) { |
| Value *CV0 = ConstantInt::get(Type::getInt32Ty(Context), 0); |
| Value *CV1 = ConstantInt::get(Type::getInt32Ty(Context), 1); |
| |
| // Compute the fused vector type for this operand |
| Type *ArgType = I->getOperand(o)->getType(); |
| VectorType *VArgType = getVecTypeForPair(ArgType); |
| |
| Instruction *L = I, *H = J; |
| if (FlipMemInputs) { |
| L = J; |
| H = I; |
| } |
| |
| if (ArgType->isVectorTy()) { |
| unsigned numElem = cast<VectorType>(VArgType)->getNumElements(); |
| std::vector<Constant*> Mask(numElem); |
| for (unsigned v = 0; v < numElem; ++v) |
| Mask[v] = ConstantInt::get(Type::getInt32Ty(Context), v); |
| |
| Instruction *BV = new ShuffleVectorInst(L->getOperand(o), |
| H->getOperand(o), |
| ConstantVector::get(Mask), |
| getReplacementName(I, true, o)); |
| BV->insertBefore(J); |
| return BV; |
| } |
| |
| // If these two inputs are the output of another vector instruction, |
| // then we should use that output directly. It might be necessary to |
| // permute it first. [When pairings are fused recursively, you can |
| // end up with cases where a large vector is decomposed into scalars |
| // using extractelement instructions, then built into size-2 |
| // vectors using insertelement and the into larger vectors using |
| // shuffles. InstCombine does not simplify all of these cases well, |
| // and so we make sure that shuffles are generated here when possible. |
| ExtractElementInst *LEE |
| = dyn_cast<ExtractElementInst>(L->getOperand(o)); |
| ExtractElementInst *HEE |
| = dyn_cast<ExtractElementInst>(H->getOperand(o)); |
| |
| if (LEE && HEE && |
| LEE->getOperand(0)->getType() == HEE->getOperand(0)->getType()) { |
| VectorType *EEType = cast<VectorType>(LEE->getOperand(0)->getType()); |
| unsigned LowIndx = cast<ConstantInt>(LEE->getOperand(1))->getZExtValue(); |
| unsigned HighIndx = cast<ConstantInt>(HEE->getOperand(1))->getZExtValue(); |
| if (LEE->getOperand(0) == HEE->getOperand(0)) { |
| if (LowIndx == 0 && HighIndx == 1) |
| return LEE->getOperand(0); |
| |
| std::vector<Constant*> Mask(2); |
| Mask[0] = ConstantInt::get(Type::getInt32Ty(Context), LowIndx); |
| Mask[1] = ConstantInt::get(Type::getInt32Ty(Context), HighIndx); |
| |
| Instruction *BV = new ShuffleVectorInst(LEE->getOperand(0), |
| UndefValue::get(EEType), |
| ConstantVector::get(Mask), |
| getReplacementName(I, true, o)); |
| BV->insertBefore(J); |
| return BV; |
| } |
| |
| std::vector<Constant*> Mask(2); |
| HighIndx += EEType->getNumElements(); |
| Mask[0] = ConstantInt::get(Type::getInt32Ty(Context), LowIndx); |
| Mask[1] = ConstantInt::get(Type::getInt32Ty(Context), HighIndx); |
| |
| Instruction *BV = new ShuffleVectorInst(LEE->getOperand(0), |
| HEE->getOperand(0), |
| ConstantVector::get(Mask), |
| getReplacementName(I, true, o)); |
| BV->insertBefore(J); |
| return BV; |
| } |
| |
| Instruction *BV1 = InsertElementInst::Create( |
| UndefValue::get(VArgType), |
| L->getOperand(o), CV0, |
| getReplacementName(I, true, o, 1)); |
| BV1->insertBefore(I); |
| Instruction *BV2 = InsertElementInst::Create(BV1, H->getOperand(o), |
| CV1, |
| getReplacementName(I, true, o, 2)); |
| BV2->insertBefore(J); |
| return BV2; |
| } |
| |
| // This function creates an array of values that will be used as the inputs |
| // to the vector instruction that fuses I with J. |
| void BBVectorize::getReplacementInputsForPair(LLVMContext& Context, |
| Instruction *I, Instruction *J, |
| SmallVector<Value *, 3> &ReplacedOperands, |
| bool &FlipMemInputs) { |
| FlipMemInputs = false; |
| unsigned NumOperands = I->getNumOperands(); |
| |
| for (unsigned p = 0, o = NumOperands-1; p < NumOperands; ++p, --o) { |
| // Iterate backward so that we look at the store pointer |
| // first and know whether or not we need to flip the inputs. |
| |
| if (isa<LoadInst>(I) || (o == 1 && isa<StoreInst>(I))) { |
| // This is the pointer for a load/store instruction. |
| ReplacedOperands[o] = getReplacementPointerInput(Context, I, J, o, |
| FlipMemInputs); |
| continue; |
| } else if (isa<CallInst>(I)) { |
| Function *F = cast<CallInst>(I)->getCalledFunction(); |
| unsigned IID = F->getIntrinsicID(); |
| if (o == NumOperands-1) { |
| BasicBlock &BB = *I->getParent(); |
| |
| Module *M = BB.getParent()->getParent(); |
| Type *ArgType = I->getType(); |
| Type *VArgType = getVecTypeForPair(ArgType); |
| |
| // FIXME: is it safe to do this here? |
| ReplacedOperands[o] = Intrinsic::getDeclaration(M, |
| (Intrinsic::ID) IID, VArgType); |
| continue; |
| } else if (IID == Intrinsic::powi && o == 1) { |
| // The second argument of powi is a single integer and we've already |
| // checked that both arguments are equal. As a result, we just keep |
| // I's second argument. |
| ReplacedOperands[o] = I->getOperand(o); |
| continue; |
| } |
| } else if (isa<ShuffleVectorInst>(I) && o == NumOperands-1) { |
| ReplacedOperands[o] = getReplacementShuffleMask(Context, I, J); |
| continue; |
| } |
| |
| ReplacedOperands[o] = |
| getReplacementInput(Context, I, J, o, FlipMemInputs); |
| } |
| } |
| |
| // This function creates two values that represent the outputs of the |
| // original I and J instructions. These are generally vector shuffles |
| // or extracts. In many cases, these will end up being unused and, thus, |
| // eliminated by later passes. |
| void BBVectorize::replaceOutputsOfPair(LLVMContext& Context, Instruction *I, |
| Instruction *J, Instruction *K, |
| Instruction *&InsertionPt, |
| Instruction *&K1, Instruction *&K2, |
| bool &FlipMemInputs) { |
| Value *CV0 = ConstantInt::get(Type::getInt32Ty(Context), 0); |
| Value *CV1 = ConstantInt::get(Type::getInt32Ty(Context), 1); |
| |
| if (isa<StoreInst>(I)) { |
| AA->replaceWithNewValue(I, K); |
| AA->replaceWithNewValue(J, K); |
| } else { |
| Type *IType = I->getType(); |
| Type *VType = getVecTypeForPair(IType); |
| |
| if (IType->isVectorTy()) { |
| unsigned numElem = cast<VectorType>(IType)->getNumElements(); |
| std::vector<Constant*> Mask1(numElem), Mask2(numElem); |
| for (unsigned v = 0; v < numElem; ++v) { |
| Mask1[v] = ConstantInt::get(Type::getInt32Ty(Context), v); |
| Mask2[v] = ConstantInt::get(Type::getInt32Ty(Context), numElem+v); |
| } |
| |
| K1 = new ShuffleVectorInst(K, UndefValue::get(VType), |
| ConstantVector::get( |
| FlipMemInputs ? Mask2 : Mask1), |
| getReplacementName(K, false, 1)); |
| K2 = new ShuffleVectorInst(K, UndefValue::get(VType), |
| ConstantVector::get( |
| FlipMemInputs ? Mask1 : Mask2), |
| getReplacementName(K, false, 2)); |
| } else { |
| K1 = ExtractElementInst::Create(K, FlipMemInputs ? CV1 : CV0, |
| getReplacementName(K, false, 1)); |
| K2 = ExtractElementInst::Create(K, FlipMemInputs ? CV0 : CV1, |
| getReplacementName(K, false, 2)); |
| } |
| |
| K1->insertAfter(K); |
| K2->insertAfter(K1); |
| InsertionPt = K2; |
| } |
| } |
| |
| // Move all uses of the function I (including pairing-induced uses) after J. |
| bool BBVectorize::canMoveUsesOfIAfterJ(BasicBlock &BB, |
| std::multimap<Value *, Value *> &LoadMoveSet, |
| Instruction *I, Instruction *J) { |
| // Skip to the first instruction past I. |
| BasicBlock::iterator L = llvm::next(BasicBlock::iterator(I)); |
| |
| DenseSet<Value *> Users; |
| AliasSetTracker WriteSet(*AA); |
| for (; cast<Instruction>(L) != J; ++L) |
| (void) trackUsesOfI(Users, WriteSet, I, L, true, &LoadMoveSet); |
| |
| assert(cast<Instruction>(L) == J && |
| "Tracking has not proceeded far enough to check for dependencies"); |
| // If J is now in the use set of I, then trackUsesOfI will return true |
| // and we have a dependency cycle (and the fusing operation must abort). |
| return !trackUsesOfI(Users, WriteSet, I, J, true, &LoadMoveSet); |
| } |
| |
| // Move all uses of the function I (including pairing-induced uses) after J. |
| void BBVectorize::moveUsesOfIAfterJ(BasicBlock &BB, |
| std::multimap<Value *, Value *> &LoadMoveSet, |
| Instruction *&InsertionPt, |
| Instruction *I, Instruction *J) { |
| // Skip to the first instruction past I. |
| BasicBlock::iterator L = llvm::next(BasicBlock::iterator(I)); |
| |
| DenseSet<Value *> Users; |
| AliasSetTracker WriteSet(*AA); |
| for (; cast<Instruction>(L) != J;) { |
| if (trackUsesOfI(Users, WriteSet, I, L, true, &LoadMoveSet)) { |
| // Move this instruction |
| Instruction *InstToMove = L; ++L; |
| |
| DEBUG(dbgs() << "BBV: moving: " << *InstToMove << |
| " to after " << *InsertionPt << "\n"); |
| InstToMove->removeFromParent(); |
| InstToMove->insertAfter(InsertionPt); |
| InsertionPt = InstToMove; |
| } else { |
| ++L; |
| } |
| } |
| } |
| |
| // Collect all load instruction that are in the move set of a given first |
| // pair member. These loads depend on the first instruction, I, and so need |
| // to be moved after J (the second instruction) when the pair is fused. |
| void BBVectorize::collectPairLoadMoveSet(BasicBlock &BB, |
| DenseMap<Value *, Value *> &ChosenPairs, |
| std::multimap<Value *, Value *> &LoadMoveSet, |
| Instruction *I) { |
| // Skip to the first instruction past I. |
| BasicBlock::iterator L = llvm::next(BasicBlock::iterator(I)); |
| |
| DenseSet<Value *> Users; |
| AliasSetTracker WriteSet(*AA); |
| |
| // Note: We cannot end the loop when we reach J because J could be moved |
| // farther down the use chain by another instruction pairing. Also, J |
| // could be before I if this is an inverted input. |
| for (BasicBlock::iterator E = BB.end(); cast<Instruction>(L) != E; ++L) { |
| if (trackUsesOfI(Users, WriteSet, I, L)) { |
| if (L->mayReadFromMemory()) |
| LoadMoveSet.insert(ValuePair(L, I)); |
| } |
| } |
| } |
| |
| // In cases where both load/stores and the computation of their pointers |
| // are chosen for vectorization, we can end up in a situation where the |
| // aliasing analysis starts returning different query results as the |
| // process of fusing instruction pairs continues. Because the algorithm |
| // relies on finding the same use trees here as were found earlier, we'll |
| // need to precompute the necessary aliasing information here and then |
| // manually update it during the fusion process. |
| void BBVectorize::collectLoadMoveSet(BasicBlock &BB, |
| std::vector<Value *> &PairableInsts, |
| DenseMap<Value *, Value *> &ChosenPairs, |
| std::multimap<Value *, Value *> &LoadMoveSet) { |
| for (std::vector<Value *>::iterator PI = PairableInsts.begin(), |
| PIE = PairableInsts.end(); PI != PIE; ++PI) { |
| DenseMap<Value *, Value *>::iterator P = ChosenPairs.find(*PI); |
| if (P == ChosenPairs.end()) continue; |
| |
| Instruction *I = cast<Instruction>(P->first); |
| collectPairLoadMoveSet(BB, ChosenPairs, LoadMoveSet, I); |
| } |
| } |
| |
| // This function fuses the chosen instruction pairs into vector instructions, |
| // taking care preserve any needed scalar outputs and, then, it reorders the |
| // remaining instructions as needed (users of the first member of the pair |
| // need to be moved to after the location of the second member of the pair |
| // because the vector instruction is inserted in the location of the pair's |
| // second member). |
| void BBVectorize::fuseChosenPairs(BasicBlock &BB, |
| std::vector<Value *> &PairableInsts, |
| DenseMap<Value *, Value *> &ChosenPairs) { |
| LLVMContext& Context = BB.getContext(); |
| |
| // During the vectorization process, the order of the pairs to be fused |
| // could be flipped. So we'll add each pair, flipped, into the ChosenPairs |
| // list. After a pair is fused, the flipped pair is removed from the list. |
| std::vector<ValuePair> FlippedPairs; |
| FlippedPairs.reserve(ChosenPairs.size()); |
| for (DenseMap<Value *, Value *>::iterator P = ChosenPairs.begin(), |
| E = ChosenPairs.end(); P != E; ++P) |
| FlippedPairs.push_back(ValuePair(P->second, P->first)); |
| for (std::vector<ValuePair>::iterator P = FlippedPairs.begin(), |
| E = FlippedPairs.end(); P != E; ++P) |
| ChosenPairs.insert(*P); |
| |
| std::multimap<Value *, Value *> LoadMoveSet; |
| collectLoadMoveSet(BB, PairableInsts, ChosenPairs, LoadMoveSet); |
| |
| DEBUG(dbgs() << "BBV: initial: \n" << BB << "\n"); |
| |
| for (BasicBlock::iterator PI = BB.getFirstInsertionPt(); PI != BB.end();) { |
| DenseMap<Value *, Value *>::iterator P = ChosenPairs.find(PI); |
| if (P == ChosenPairs.end()) { |
| ++PI; |
| continue; |
| } |
| |
| if (getDepthFactor(P->first) == 0) { |
| // These instructions are not really fused, but are tracked as though |
| // they are. Any case in which it would be interesting to fuse them |
| // will be taken care of by InstCombine. |
| --NumFusedOps; |
| ++PI; |
| continue; |
| } |
| |
| Instruction *I = cast<Instruction>(P->first), |
| *J = cast<Instruction>(P->second); |
| |
| DEBUG(dbgs() << "BBV: fusing: " << *I << |
| " <-> " << *J << "\n"); |
| |
| // Remove the pair and flipped pair from the list. |
| DenseMap<Value *, Value *>::iterator FP = ChosenPairs.find(P->second); |
| assert(FP != ChosenPairs.end() && "Flipped pair not found in list"); |
| ChosenPairs.erase(FP); |
| ChosenPairs.erase(P); |
| |
| if (!canMoveUsesOfIAfterJ(BB, LoadMoveSet, I, J)) { |
| DEBUG(dbgs() << "BBV: fusion of: " << *I << |
| " <-> " << *J << |
| " aborted because of non-trivial dependency cycle\n"); |
| --NumFusedOps; |
| ++PI; |
| continue; |
| } |
| |
| bool FlipMemInputs; |
| unsigned NumOperands = I->getNumOperands(); |
| SmallVector<Value *, 3> ReplacedOperands(NumOperands); |
| getReplacementInputsForPair(Context, I, J, ReplacedOperands, |
| FlipMemInputs); |
| |
| // Make a copy of the original operation, change its type to the vector |
| // type and replace its operands with the vector operands. |
| Instruction *K = I->clone(); |
| if (I->hasName()) K->takeName(I); |
| |
| if (!isa<StoreInst>(K)) |
| K->mutateType(getVecTypeForPair(I->getType())); |
| |
| for (unsigned o = 0; o < NumOperands; ++o) |
| K->setOperand(o, ReplacedOperands[o]); |
| |
| // If we've flipped the memory inputs, make sure that we take the correct |
| // alignment. |
| if (FlipMemInputs) { |
| if (isa<StoreInst>(K)) |
| cast<StoreInst>(K)->setAlignment(cast<StoreInst>(J)->getAlignment()); |
| else |
| cast<LoadInst>(K)->setAlignment(cast<LoadInst>(J)->getAlignment()); |
| } |
| |
| K->insertAfter(J); |
| |
| // Instruction insertion point: |
| Instruction *InsertionPt = K; |
| Instruction *K1 = 0, *K2 = 0; |
| replaceOutputsOfPair(Context, I, J, K, InsertionPt, K1, K2, |
| FlipMemInputs); |
| |
| // The use tree of the first original instruction must be moved to after |
| // the location of the second instruction. The entire use tree of the |
| // first instruction is disjoint from the input tree of the second |
| // (by definition), and so commutes with it. |
| |
| moveUsesOfIAfterJ(BB, LoadMoveSet, InsertionPt, I, J); |
| |
| if (!isa<StoreInst>(I)) { |
| I->replaceAllUsesWith(K1); |
| J->replaceAllUsesWith(K2); |
| AA->replaceWithNewValue(I, K1); |
| AA->replaceWithNewValue(J, K2); |
| } |
| |
| // Instructions that may read from memory may be in the load move set. |
| // Once an instruction is fused, we no longer need its move set, and so |
| // the values of the map never need to be updated. However, when a load |
| // is fused, we need to merge the entries from both instructions in the |
| // pair in case those instructions were in the move set of some other |
| // yet-to-be-fused pair. The loads in question are the keys of the map. |
| if (I->mayReadFromMemory()) { |
| std::vector<ValuePair> NewSetMembers; |
| VPIteratorPair IPairRange = LoadMoveSet.equal_range(I); |
| VPIteratorPair JPairRange = LoadMoveSet.equal_range(J); |
| for (std::multimap<Value *, Value *>::iterator N = IPairRange.first; |
| N != IPairRange.second; ++N) |
| NewSetMembers.push_back(ValuePair(K, N->second)); |
| for (std::multimap<Value *, Value *>::iterator N = JPairRange.first; |
| N != JPairRange.second; ++N) |
| NewSetMembers.push_back(ValuePair(K, N->second)); |
| for (std::vector<ValuePair>::iterator A = NewSetMembers.begin(), |
| AE = NewSetMembers.end(); A != AE; ++A) |
| LoadMoveSet.insert(*A); |
| } |
| |
| // Before removing I, set the iterator to the next instruction. |
| PI = llvm::next(BasicBlock::iterator(I)); |
| if (cast<Instruction>(PI) == J) |
| ++PI; |
| |
| SE->forgetValue(I); |
| SE->forgetValue(J); |
| I->eraseFromParent(); |
| J->eraseFromParent(); |
| } |
| |
| DEBUG(dbgs() << "BBV: final: \n" << BB << "\n"); |
| } |
| } |
| |
| char BBVectorize::ID = 0; |
| static const char bb_vectorize_name[] = "Basic-Block Vectorization"; |
| INITIALIZE_PASS_BEGIN(BBVectorize, BBV_NAME, bb_vectorize_name, false, false) |
| INITIALIZE_AG_DEPENDENCY(AliasAnalysis) |
| INITIALIZE_PASS_DEPENDENCY(ScalarEvolution) |
| INITIALIZE_PASS_END(BBVectorize, BBV_NAME, bb_vectorize_name, false, false) |
| |
| BasicBlockPass *llvm::createBBVectorizePass(const VectorizeConfig &C) { |
| return new BBVectorize(C); |
| } |
| |
| bool |
| llvm::vectorizeBasicBlock(Pass *P, BasicBlock &BB, const VectorizeConfig &C) { |
| BBVectorize BBVectorizer(P, C); |
| return BBVectorizer.vectorizeBB(BB); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| VectorizeConfig::VectorizeConfig() { |
| VectorBits = ::VectorBits; |
| VectorizeInts = !::NoInts; |
| VectorizeFloats = !::NoFloats; |
| VectorizePointers = !::NoPointers; |
| VectorizeCasts = !::NoCasts; |
| VectorizeMath = !::NoMath; |
| VectorizeFMA = !::NoFMA; |
| VectorizeSelect = !::NoSelect; |
| VectorizeGEP = !::NoGEP; |
| VectorizeMemOps = !::NoMemOps; |
| AlignedOnly = ::AlignedOnly; |
| ReqChainDepth= ::ReqChainDepth; |
| SearchLimit = ::SearchLimit; |
| MaxCandPairsForCycleCheck = ::MaxCandPairsForCycleCheck; |
| SplatBreaksChain = ::SplatBreaksChain; |
| MaxInsts = ::MaxInsts; |
| MaxIter = ::MaxIter; |
| NoMemOpBoost = ::NoMemOpBoost; |
| FastDep = ::FastDep; |
| } |