| //===- LoopVectorize.cpp - A Loop Vectorizer ------------------------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This is the LLVM loop vectorizer. This pass modifies 'vectorizable' loops |
| // and generates target-independent LLVM-IR. |
| // The vectorizer uses the TargetTransformInfo analysis to estimate the costs |
| // of instructions in order to estimate the profitability of vectorization. |
| // |
| // The loop vectorizer combines consecutive loop iterations into a single |
| // 'wide' iteration. After this transformation the index is incremented |
| // by the SIMD vector width, and not by one. |
| // |
| // This pass has three parts: |
| // 1. The main loop pass that drives the different parts. |
| // 2. LoopVectorizationLegality - A unit that checks for the legality |
| // of the vectorization. |
| // 3. InnerLoopVectorizer - A unit that performs the actual |
| // widening of instructions. |
| // 4. LoopVectorizationCostModel - A unit that checks for the profitability |
| // of vectorization. It decides on the optimal vector width, which |
| // can be one, if vectorization is not profitable. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // The reduction-variable vectorization is based on the paper: |
| // D. Nuzman and R. Henderson. Multi-platform Auto-vectorization. |
| // |
| // Variable uniformity checks are inspired by: |
| // Karrenberg, R. and Hack, S. Whole Function Vectorization. |
| // |
| // The interleaved access vectorization is based on the paper: |
| // Dorit Nuzman, Ira Rosen and Ayal Zaks. Auto-Vectorization of Interleaved |
| // Data for SIMD |
| // |
| // Other ideas/concepts are from: |
| // A. Zaks and D. Nuzman. Autovectorization in GCC-two years later. |
| // |
| // S. Maleki, Y. Gao, M. Garzaran, T. Wong and D. Padua. An Evaluation of |
| // Vectorizing Compilers. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/Transforms/Vectorize.h" |
| #include "llvm/ADT/DenseMap.h" |
| #include "llvm/ADT/EquivalenceClasses.h" |
| #include "llvm/ADT/Hashing.h" |
| #include "llvm/ADT/MapVector.h" |
| #include "llvm/ADT/SetVector.h" |
| #include "llvm/ADT/SmallPtrSet.h" |
| #include "llvm/ADT/SmallSet.h" |
| #include "llvm/ADT/SmallVector.h" |
| #include "llvm/ADT/Statistic.h" |
| #include "llvm/ADT/StringExtras.h" |
| #include "llvm/Analysis/AliasAnalysis.h" |
| #include "llvm/Analysis/AliasSetTracker.h" |
| #include "llvm/Analysis/AssumptionCache.h" |
| #include "llvm/Analysis/BlockFrequencyInfo.h" |
| #include "llvm/Analysis/CodeMetrics.h" |
| #include "llvm/Analysis/LoopAccessAnalysis.h" |
| #include "llvm/Analysis/LoopInfo.h" |
| #include "llvm/Analysis/LoopIterator.h" |
| #include "llvm/Analysis/LoopPass.h" |
| #include "llvm/Analysis/ScalarEvolution.h" |
| #include "llvm/Analysis/ScalarEvolutionExpander.h" |
| #include "llvm/Analysis/ScalarEvolutionExpressions.h" |
| #include "llvm/Analysis/TargetTransformInfo.h" |
| #include "llvm/Analysis/ValueTracking.h" |
| #include "llvm/IR/Constants.h" |
| #include "llvm/IR/DataLayout.h" |
| #include "llvm/IR/DebugInfo.h" |
| #include "llvm/IR/DerivedTypes.h" |
| #include "llvm/IR/DiagnosticInfo.h" |
| #include "llvm/IR/Dominators.h" |
| #include "llvm/IR/Function.h" |
| #include "llvm/IR/IRBuilder.h" |
| #include "llvm/IR/Instructions.h" |
| #include "llvm/IR/IntrinsicInst.h" |
| #include "llvm/IR/LLVMContext.h" |
| #include "llvm/IR/Module.h" |
| #include "llvm/IR/PatternMatch.h" |
| #include "llvm/IR/Type.h" |
| #include "llvm/IR/Value.h" |
| #include "llvm/IR/ValueHandle.h" |
| #include "llvm/IR/Verifier.h" |
| #include "llvm/Pass.h" |
| #include "llvm/Support/BranchProbability.h" |
| #include "llvm/Support/CommandLine.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include "llvm/Transforms/Scalar.h" |
| #include "llvm/Transforms/Utils/BasicBlockUtils.h" |
| #include "llvm/Transforms/Utils/Local.h" |
| #include "llvm/Analysis/VectorUtils.h" |
| #include "llvm/Transforms/Utils/LoopUtils.h" |
| #include <algorithm> |
| #include <map> |
| #include <tuple> |
| |
| using namespace llvm; |
| using namespace llvm::PatternMatch; |
| |
| #define LV_NAME "loop-vectorize" |
| #define DEBUG_TYPE LV_NAME |
| |
| STATISTIC(LoopsVectorized, "Number of loops vectorized"); |
| STATISTIC(LoopsAnalyzed, "Number of loops analyzed for vectorization"); |
| |
| static cl::opt<bool> |
| EnableIfConversion("enable-if-conversion", cl::init(true), cl::Hidden, |
| cl::desc("Enable if-conversion during vectorization.")); |
| |
| /// We don't vectorize loops with a known constant trip count below this number. |
| static cl::opt<unsigned> |
| TinyTripCountVectorThreshold("vectorizer-min-trip-count", cl::init(16), |
| cl::Hidden, |
| cl::desc("Don't vectorize loops with a constant " |
| "trip count that is smaller than this " |
| "value.")); |
| |
| /// This enables versioning on the strides of symbolically striding memory |
| /// accesses in code like the following. |
| /// for (i = 0; i < N; ++i) |
| /// A[i * Stride1] += B[i * Stride2] ... |
| /// |
| /// Will be roughly translated to |
| /// if (Stride1 == 1 && Stride2 == 1) { |
| /// for (i = 0; i < N; i+=4) |
| /// A[i:i+3] += ... |
| /// } else |
| /// ... |
| static cl::opt<bool> EnableMemAccessVersioning( |
| "enable-mem-access-versioning", cl::init(true), cl::Hidden, |
| cl::desc("Enable symblic stride memory access versioning")); |
| |
| static cl::opt<bool> EnableInterleavedMemAccesses( |
| "enable-interleaved-mem-accesses", cl::init(false), cl::Hidden, |
| cl::desc("Enable vectorization on interleaved memory accesses in a loop")); |
| |
| /// Maximum factor for an interleaved memory access. |
| static cl::opt<unsigned> MaxInterleaveGroupFactor( |
| "max-interleave-group-factor", cl::Hidden, |
| cl::desc("Maximum factor for an interleaved access group (default = 8)"), |
| cl::init(8)); |
| |
| /// We don't interleave loops with a known constant trip count below this |
| /// number. |
| static const unsigned TinyTripCountInterleaveThreshold = 128; |
| |
| static cl::opt<unsigned> ForceTargetNumScalarRegs( |
| "force-target-num-scalar-regs", cl::init(0), cl::Hidden, |
| cl::desc("A flag that overrides the target's number of scalar registers.")); |
| |
| static cl::opt<unsigned> ForceTargetNumVectorRegs( |
| "force-target-num-vector-regs", cl::init(0), cl::Hidden, |
| cl::desc("A flag that overrides the target's number of vector registers.")); |
| |
| /// Maximum vectorization interleave count. |
| static const unsigned MaxInterleaveFactor = 16; |
| |
| static cl::opt<unsigned> ForceTargetMaxScalarInterleaveFactor( |
| "force-target-max-scalar-interleave", cl::init(0), cl::Hidden, |
| cl::desc("A flag that overrides the target's max interleave factor for " |
| "scalar loops.")); |
| |
| static cl::opt<unsigned> ForceTargetMaxVectorInterleaveFactor( |
| "force-target-max-vector-interleave", cl::init(0), cl::Hidden, |
| cl::desc("A flag that overrides the target's max interleave factor for " |
| "vectorized loops.")); |
| |
| static cl::opt<unsigned> ForceTargetInstructionCost( |
| "force-target-instruction-cost", cl::init(0), cl::Hidden, |
| cl::desc("A flag that overrides the target's expected cost for " |
| "an instruction to a single constant value. Mostly " |
| "useful for getting consistent testing.")); |
| |
| static cl::opt<unsigned> SmallLoopCost( |
| "small-loop-cost", cl::init(20), cl::Hidden, |
| cl::desc( |
| "The cost of a loop that is considered 'small' by the interleaver.")); |
| |
| static cl::opt<bool> LoopVectorizeWithBlockFrequency( |
| "loop-vectorize-with-block-frequency", cl::init(false), cl::Hidden, |
| cl::desc("Enable the use of the block frequency analysis to access PGO " |
| "heuristics minimizing code growth in cold regions and being more " |
| "aggressive in hot regions.")); |
| |
| // Runtime interleave loops for load/store throughput. |
| static cl::opt<bool> EnableLoadStoreRuntimeInterleave( |
| "enable-loadstore-runtime-interleave", cl::init(true), cl::Hidden, |
| cl::desc( |
| "Enable runtime interleaving until load/store ports are saturated")); |
| |
| /// The number of stores in a loop that are allowed to need predication. |
| static cl::opt<unsigned> NumberOfStoresToPredicate( |
| "vectorize-num-stores-pred", cl::init(1), cl::Hidden, |
| cl::desc("Max number of stores to be predicated behind an if.")); |
| |
| static cl::opt<bool> EnableIndVarRegisterHeur( |
| "enable-ind-var-reg-heur", cl::init(true), cl::Hidden, |
| cl::desc("Count the induction variable only once when interleaving")); |
| |
| static cl::opt<bool> EnableCondStoresVectorization( |
| "enable-cond-stores-vec", cl::init(false), cl::Hidden, |
| cl::desc("Enable if predication of stores during vectorization.")); |
| |
| static cl::opt<unsigned> MaxNestedScalarReductionIC( |
| "max-nested-scalar-reduction-interleave", cl::init(2), cl::Hidden, |
| cl::desc("The maximum interleave count to use when interleaving a scalar " |
| "reduction in a nested loop.")); |
| |
| namespace { |
| |
| // Forward declarations. |
| class LoopVectorizationLegality; |
| class LoopVectorizationCostModel; |
| class LoopVectorizeHints; |
| |
| /// \brief This modifies LoopAccessReport to initialize message with |
| /// loop-vectorizer-specific part. |
| class VectorizationReport : public LoopAccessReport { |
| public: |
| VectorizationReport(Instruction *I = nullptr) |
| : LoopAccessReport("loop not vectorized: ", I) {} |
| |
| /// \brief This allows promotion of the loop-access analysis report into the |
| /// loop-vectorizer report. It modifies the message to add the |
| /// loop-vectorizer-specific part of the message. |
| explicit VectorizationReport(const LoopAccessReport &R) |
| : LoopAccessReport(Twine("loop not vectorized: ") + R.str(), |
| R.getInstr()) {} |
| }; |
| |
| /// A helper function for converting Scalar types to vector types. |
| /// If the incoming type is void, we return void. If the VF is 1, we return |
| /// the scalar type. |
| static Type* ToVectorTy(Type *Scalar, unsigned VF) { |
| if (Scalar->isVoidTy() || VF == 1) |
| return Scalar; |
| return VectorType::get(Scalar, VF); |
| } |
| |
| /// InnerLoopVectorizer vectorizes loops which contain only one basic |
| /// block to a specified vectorization factor (VF). |
| /// This class performs the widening of scalars into vectors, or multiple |
| /// scalars. This class also implements the following features: |
| /// * It inserts an epilogue loop for handling loops that don't have iteration |
| /// counts that are known to be a multiple of the vectorization factor. |
| /// * It handles the code generation for reduction variables. |
| /// * Scalarization (implementation using scalars) of un-vectorizable |
| /// instructions. |
| /// InnerLoopVectorizer does not perform any vectorization-legality |
| /// checks, and relies on the caller to check for the different legality |
| /// aspects. The InnerLoopVectorizer relies on the |
| /// LoopVectorizationLegality class to provide information about the induction |
| /// and reduction variables that were found to a given vectorization factor. |
| class InnerLoopVectorizer { |
| public: |
| InnerLoopVectorizer(Loop *OrigLoop, ScalarEvolution *SE, LoopInfo *LI, |
| DominatorTree *DT, const TargetLibraryInfo *TLI, |
| const TargetTransformInfo *TTI, unsigned VecWidth, |
| unsigned UnrollFactor) |
| : OrigLoop(OrigLoop), SE(SE), LI(LI), DT(DT), TLI(TLI), TTI(TTI), |
| VF(VecWidth), UF(UnrollFactor), Builder(SE->getContext()), |
| Induction(nullptr), OldInduction(nullptr), WidenMap(UnrollFactor), |
| Legal(nullptr), AddedSafetyChecks(false) {} |
| |
| // Perform the actual loop widening (vectorization). |
| void vectorize(LoopVectorizationLegality *L) { |
| Legal = L; |
| // Create a new empty loop. Unlink the old loop and connect the new one. |
| createEmptyLoop(); |
| // Widen each instruction in the old loop to a new one in the new loop. |
| // Use the Legality module to find the induction and reduction variables. |
| vectorizeLoop(); |
| // Register the new loop and update the analysis passes. |
| updateAnalysis(); |
| } |
| |
| // Return true if any runtime check is added. |
| bool IsSafetyChecksAdded() { |
| return AddedSafetyChecks; |
| } |
| |
| virtual ~InnerLoopVectorizer() {} |
| |
| protected: |
| /// A small list of PHINodes. |
| typedef SmallVector<PHINode*, 4> PhiVector; |
| /// When we unroll loops we have multiple vector values for each scalar. |
| /// This data structure holds the unrolled and vectorized values that |
| /// originated from one scalar instruction. |
| typedef SmallVector<Value*, 2> VectorParts; |
| |
| // When we if-convert we need to create edge masks. We have to cache values |
| // so that we don't end up with exponential recursion/IR. |
| typedef DenseMap<std::pair<BasicBlock*, BasicBlock*>, |
| VectorParts> EdgeMaskCache; |
| |
| /// \brief Add checks for strides that were assumed to be 1. |
| /// |
| /// Returns the last check instruction and the first check instruction in the |
| /// pair as (first, last). |
| std::pair<Instruction *, Instruction *> addStrideCheck(Instruction *Loc); |
| |
| /// Create an empty loop, based on the loop ranges of the old loop. |
| void createEmptyLoop(); |
| /// Copy and widen the instructions from the old loop. |
| virtual void vectorizeLoop(); |
| |
| /// \brief The Loop exit block may have single value PHI nodes where the |
| /// incoming value is 'Undef'. While vectorizing we only handled real values |
| /// that were defined inside the loop. Here we fix the 'undef case'. |
| /// See PR14725. |
| void fixLCSSAPHIs(); |
| |
| /// A helper function that computes the predicate of the block BB, assuming |
| /// that the header block of the loop is set to True. It returns the *entry* |
| /// mask for the block BB. |
| VectorParts createBlockInMask(BasicBlock *BB); |
| /// A helper function that computes the predicate of the edge between SRC |
| /// and DST. |
| VectorParts createEdgeMask(BasicBlock *Src, BasicBlock *Dst); |
| |
| /// A helper function to vectorize a single BB within the innermost loop. |
| void vectorizeBlockInLoop(BasicBlock *BB, PhiVector *PV); |
| |
| /// Vectorize a single PHINode in a block. This method handles the induction |
| /// variable canonicalization. It supports both VF = 1 for unrolled loops and |
| /// arbitrary length vectors. |
| void widenPHIInstruction(Instruction *PN, VectorParts &Entry, |
| unsigned UF, unsigned VF, PhiVector *PV); |
| |
| /// Insert the new loop to the loop hierarchy and pass manager |
| /// and update the analysis passes. |
| void updateAnalysis(); |
| |
| /// This instruction is un-vectorizable. Implement it as a sequence |
| /// of scalars. If \p IfPredicateStore is true we need to 'hide' each |
| /// scalarized instruction behind an if block predicated on the control |
| /// dependence of the instruction. |
| virtual void scalarizeInstruction(Instruction *Instr, |
| bool IfPredicateStore=false); |
| |
| /// Vectorize Load and Store instructions, |
| virtual void vectorizeMemoryInstruction(Instruction *Instr); |
| |
| /// Create a broadcast instruction. This method generates a broadcast |
| /// instruction (shuffle) for loop invariant values and for the induction |
| /// value. If this is the induction variable then we extend it to N, N+1, ... |
| /// this is needed because each iteration in the loop corresponds to a SIMD |
| /// element. |
| virtual Value *getBroadcastInstrs(Value *V); |
| |
| /// This function adds (StartIdx, StartIdx + Step, StartIdx + 2*Step, ...) |
| /// to each vector element of Val. The sequence starts at StartIndex. |
| virtual Value *getStepVector(Value *Val, int StartIdx, Value *Step); |
| |
| /// When we go over instructions in the basic block we rely on previous |
| /// values within the current basic block or on loop invariant values. |
| /// When we widen (vectorize) values we place them in the map. If the values |
| /// are not within the map, they have to be loop invariant, so we simply |
| /// broadcast them into a vector. |
| VectorParts &getVectorValue(Value *V); |
| |
| /// Try to vectorize the interleaved access group that \p Instr belongs to. |
| void vectorizeInterleaveGroup(Instruction *Instr); |
| |
| /// Generate a shuffle sequence that will reverse the vector Vec. |
| virtual Value *reverseVector(Value *Vec); |
| |
| /// This is a helper class that holds the vectorizer state. It maps scalar |
| /// instructions to vector instructions. When the code is 'unrolled' then |
| /// then a single scalar value is mapped to multiple vector parts. The parts |
| /// are stored in the VectorPart type. |
| struct ValueMap { |
| /// C'tor. UnrollFactor controls the number of vectors ('parts') that |
| /// are mapped. |
| ValueMap(unsigned UnrollFactor) : UF(UnrollFactor) {} |
| |
| /// \return True if 'Key' is saved in the Value Map. |
| bool has(Value *Key) const { return MapStorage.count(Key); } |
| |
| /// Initializes a new entry in the map. Sets all of the vector parts to the |
| /// save value in 'Val'. |
| /// \return A reference to a vector with splat values. |
| VectorParts &splat(Value *Key, Value *Val) { |
| VectorParts &Entry = MapStorage[Key]; |
| Entry.assign(UF, Val); |
| return Entry; |
| } |
| |
| ///\return A reference to the value that is stored at 'Key'. |
| VectorParts &get(Value *Key) { |
| VectorParts &Entry = MapStorage[Key]; |
| if (Entry.empty()) |
| Entry.resize(UF); |
| assert(Entry.size() == UF); |
| return Entry; |
| } |
| |
| private: |
| /// The unroll factor. Each entry in the map stores this number of vector |
| /// elements. |
| unsigned UF; |
| |
| /// Map storage. We use std::map and not DenseMap because insertions to a |
| /// dense map invalidates its iterators. |
| std::map<Value *, VectorParts> MapStorage; |
| }; |
| |
| /// The original loop. |
| Loop *OrigLoop; |
| /// Scev analysis to use. |
| ScalarEvolution *SE; |
| /// Loop Info. |
| LoopInfo *LI; |
| /// Dominator Tree. |
| DominatorTree *DT; |
| /// Alias Analysis. |
| AliasAnalysis *AA; |
| /// Target Library Info. |
| const TargetLibraryInfo *TLI; |
| /// Target Transform Info. |
| const TargetTransformInfo *TTI; |
| |
| /// The vectorization SIMD factor to use. Each vector will have this many |
| /// vector elements. |
| unsigned VF; |
| |
| protected: |
| /// The vectorization unroll factor to use. Each scalar is vectorized to this |
| /// many different vector instructions. |
| unsigned UF; |
| |
| /// The builder that we use |
| IRBuilder<> Builder; |
| |
| // --- Vectorization state --- |
| |
| /// The vector-loop preheader. |
| BasicBlock *LoopVectorPreHeader; |
| /// The scalar-loop preheader. |
| BasicBlock *LoopScalarPreHeader; |
| /// Middle Block between the vector and the scalar. |
| BasicBlock *LoopMiddleBlock; |
| ///The ExitBlock of the scalar loop. |
| BasicBlock *LoopExitBlock; |
| ///The vector loop body. |
| SmallVector<BasicBlock *, 4> LoopVectorBody; |
| ///The scalar loop body. |
| BasicBlock *LoopScalarBody; |
| /// A list of all bypass blocks. The first block is the entry of the loop. |
| SmallVector<BasicBlock *, 4> LoopBypassBlocks; |
| |
| /// The new Induction variable which was added to the new block. |
| PHINode *Induction; |
| /// The induction variable of the old basic block. |
| PHINode *OldInduction; |
| /// Holds the extended (to the widest induction type) start index. |
| Value *ExtendedIdx; |
| /// Maps scalars to widened vectors. |
| ValueMap WidenMap; |
| EdgeMaskCache MaskCache; |
| |
| LoopVectorizationLegality *Legal; |
| |
| // Record whether runtime check is added. |
| bool AddedSafetyChecks; |
| }; |
| |
| class InnerLoopUnroller : public InnerLoopVectorizer { |
| public: |
| InnerLoopUnroller(Loop *OrigLoop, ScalarEvolution *SE, LoopInfo *LI, |
| DominatorTree *DT, const TargetLibraryInfo *TLI, |
| const TargetTransformInfo *TTI, unsigned UnrollFactor) |
| : InnerLoopVectorizer(OrigLoop, SE, LI, DT, TLI, TTI, 1, UnrollFactor) {} |
| |
| private: |
| void scalarizeInstruction(Instruction *Instr, |
| bool IfPredicateStore = false) override; |
| void vectorizeMemoryInstruction(Instruction *Instr) override; |
| Value *getBroadcastInstrs(Value *V) override; |
| Value *getStepVector(Value *Val, int StartIdx, Value *Step) override; |
| Value *reverseVector(Value *Vec) override; |
| }; |
| |
| /// \brief Look for a meaningful debug location on the instruction or it's |
| /// operands. |
| static Instruction *getDebugLocFromInstOrOperands(Instruction *I) { |
| if (!I) |
| return I; |
| |
| DebugLoc Empty; |
| if (I->getDebugLoc() != Empty) |
| return I; |
| |
| for (User::op_iterator OI = I->op_begin(), OE = I->op_end(); OI != OE; ++OI) { |
| if (Instruction *OpInst = dyn_cast<Instruction>(*OI)) |
| if (OpInst->getDebugLoc() != Empty) |
| return OpInst; |
| } |
| |
| return I; |
| } |
| |
| /// \brief Set the debug location in the builder using the debug location in the |
| /// instruction. |
| static void setDebugLocFromInst(IRBuilder<> &B, const Value *Ptr) { |
| if (const Instruction *Inst = dyn_cast_or_null<Instruction>(Ptr)) |
| B.SetCurrentDebugLocation(Inst->getDebugLoc()); |
| else |
| B.SetCurrentDebugLocation(DebugLoc()); |
| } |
| |
| #ifndef NDEBUG |
| /// \return string containing a file name and a line # for the given loop. |
| static std::string getDebugLocString(const Loop *L) { |
| std::string Result; |
| if (L) { |
| raw_string_ostream OS(Result); |
| if (const DebugLoc LoopDbgLoc = L->getStartLoc()) |
| LoopDbgLoc.print(OS); |
| else |
| // Just print the module name. |
| OS << L->getHeader()->getParent()->getParent()->getModuleIdentifier(); |
| OS.flush(); |
| } |
| return Result; |
| } |
| #endif |
| |
| /// \brief Propagate known metadata from one instruction to another. |
| static void propagateMetadata(Instruction *To, const Instruction *From) { |
| SmallVector<std::pair<unsigned, MDNode *>, 4> Metadata; |
| From->getAllMetadataOtherThanDebugLoc(Metadata); |
| |
| for (auto M : Metadata) { |
| unsigned Kind = M.first; |
| |
| // These are safe to transfer (this is safe for TBAA, even when we |
| // if-convert, because should that metadata have had a control dependency |
| // on the condition, and thus actually aliased with some other |
| // non-speculated memory access when the condition was false, this would be |
| // caught by the runtime overlap checks). |
| if (Kind != LLVMContext::MD_tbaa && |
| Kind != LLVMContext::MD_alias_scope && |
| Kind != LLVMContext::MD_noalias && |
| Kind != LLVMContext::MD_fpmath) |
| continue; |
| |
| To->setMetadata(Kind, M.second); |
| } |
| } |
| |
| /// \brief Propagate known metadata from one instruction to a vector of others. |
| static void propagateMetadata(SmallVectorImpl<Value *> &To, const Instruction *From) { |
| for (Value *V : To) |
| if (Instruction *I = dyn_cast<Instruction>(V)) |
| propagateMetadata(I, From); |
| } |
| |
| /// \brief The group of interleaved loads/stores sharing the same stride and |
| /// close to each other. |
| /// |
| /// Each member in this group has an index starting from 0, and the largest |
| /// index should be less than interleaved factor, which is equal to the absolute |
| /// value of the access's stride. |
| /// |
| /// E.g. An interleaved load group of factor 4: |
| /// for (unsigned i = 0; i < 1024; i+=4) { |
| /// a = A[i]; // Member of index 0 |
| /// b = A[i+1]; // Member of index 1 |
| /// d = A[i+3]; // Member of index 3 |
| /// ... |
| /// } |
| /// |
| /// An interleaved store group of factor 4: |
| /// for (unsigned i = 0; i < 1024; i+=4) { |
| /// ... |
| /// A[i] = a; // Member of index 0 |
| /// A[i+1] = b; // Member of index 1 |
| /// A[i+2] = c; // Member of index 2 |
| /// A[i+3] = d; // Member of index 3 |
| /// } |
| /// |
| /// Note: the interleaved load group could have gaps (missing members), but |
| /// the interleaved store group doesn't allow gaps. |
| class InterleaveGroup { |
| public: |
| InterleaveGroup(Instruction *Instr, int Stride, unsigned Align) |
| : Align(Align), SmallestKey(0), LargestKey(0), InsertPos(Instr) { |
| assert(Align && "The alignment should be non-zero"); |
| |
| Factor = std::abs(Stride); |
| assert(Factor > 1 && "Invalid interleave factor"); |
| |
| Reverse = Stride < 0; |
| Members[0] = Instr; |
| } |
| |
| bool isReverse() const { return Reverse; } |
| unsigned getFactor() const { return Factor; } |
| unsigned getAlignment() const { return Align; } |
| unsigned getNumMembers() const { return Members.size(); } |
| |
| /// \brief Try to insert a new member \p Instr with index \p Index and |
| /// alignment \p NewAlign. The index is related to the leader and it could be |
| /// negative if it is the new leader. |
| /// |
| /// \returns false if the instruction doesn't belong to the group. |
| bool insertMember(Instruction *Instr, int Index, unsigned NewAlign) { |
| assert(NewAlign && "The new member's alignment should be non-zero"); |
| |
| int Key = Index + SmallestKey; |
| |
| // Skip if there is already a member with the same index. |
| if (Members.count(Key)) |
| return false; |
| |
| if (Key > LargestKey) { |
| // The largest index is always less than the interleave factor. |
| if (Index >= static_cast<int>(Factor)) |
| return false; |
| |
| LargestKey = Key; |
| } else if (Key < SmallestKey) { |
| // The largest index is always less than the interleave factor. |
| if (LargestKey - Key >= static_cast<int>(Factor)) |
| return false; |
| |
| SmallestKey = Key; |
| } |
| |
| // It's always safe to select the minimum alignment. |
| Align = std::min(Align, NewAlign); |
| Members[Key] = Instr; |
| return true; |
| } |
| |
| /// \brief Get the member with the given index \p Index |
| /// |
| /// \returns nullptr if contains no such member. |
| Instruction *getMember(unsigned Index) const { |
| int Key = SmallestKey + Index; |
| if (!Members.count(Key)) |
| return nullptr; |
| |
| return Members.find(Key)->second; |
| } |
| |
| /// \brief Get the index for the given member. Unlike the key in the member |
| /// map, the index starts from 0. |
| unsigned getIndex(Instruction *Instr) const { |
| for (auto I : Members) |
| if (I.second == Instr) |
| return I.first - SmallestKey; |
| |
| llvm_unreachable("InterleaveGroup contains no such member"); |
| } |
| |
| Instruction *getInsertPos() const { return InsertPos; } |
| void setInsertPos(Instruction *Inst) { InsertPos = Inst; } |
| |
| private: |
| unsigned Factor; // Interleave Factor. |
| bool Reverse; |
| unsigned Align; |
| DenseMap<int, Instruction *> Members; |
| int SmallestKey; |
| int LargestKey; |
| |
| // To avoid breaking dependences, vectorized instructions of an interleave |
| // group should be inserted at either the first load or the last store in |
| // program order. |
| // |
| // E.g. %even = load i32 // Insert Position |
| // %add = add i32 %even // Use of %even |
| // %odd = load i32 |
| // |
| // store i32 %even |
| // %odd = add i32 // Def of %odd |
| // store i32 %odd // Insert Position |
| Instruction *InsertPos; |
| }; |
| |
| /// \brief Drive the analysis of interleaved memory accesses in the loop. |
| /// |
| /// Use this class to analyze interleaved accesses only when we can vectorize |
| /// a loop. Otherwise it's meaningless to do analysis as the vectorization |
| /// on interleaved accesses is unsafe. |
| /// |
| /// The analysis collects interleave groups and records the relationships |
| /// between the member and the group in a map. |
| class InterleavedAccessInfo { |
| public: |
| InterleavedAccessInfo(ScalarEvolution *SE, Loop *L, DominatorTree *DT) |
| : SE(SE), TheLoop(L), DT(DT) {} |
| |
| ~InterleavedAccessInfo() { |
| SmallSet<InterleaveGroup *, 4> DelSet; |
| // Avoid releasing a pointer twice. |
| for (auto &I : InterleaveGroupMap) |
| DelSet.insert(I.second); |
| for (auto *Ptr : DelSet) |
| delete Ptr; |
| } |
| |
| /// \brief Analyze the interleaved accesses and collect them in interleave |
| /// groups. Substitute symbolic strides using \p Strides. |
| void analyzeInterleaving(const ValueToValueMap &Strides); |
| |
| /// \brief Check if \p Instr belongs to any interleave group. |
| bool isInterleaved(Instruction *Instr) const { |
| return InterleaveGroupMap.count(Instr); |
| } |
| |
| /// \brief Get the interleave group that \p Instr belongs to. |
| /// |
| /// \returns nullptr if doesn't have such group. |
| InterleaveGroup *getInterleaveGroup(Instruction *Instr) const { |
| if (InterleaveGroupMap.count(Instr)) |
| return InterleaveGroupMap.find(Instr)->second; |
| return nullptr; |
| } |
| |
| private: |
| ScalarEvolution *SE; |
| Loop *TheLoop; |
| DominatorTree *DT; |
| |
| /// Holds the relationships between the members and the interleave group. |
| DenseMap<Instruction *, InterleaveGroup *> InterleaveGroupMap; |
| |
| /// \brief The descriptor for a strided memory access. |
| struct StrideDescriptor { |
| StrideDescriptor(int Stride, const SCEV *Scev, unsigned Size, |
| unsigned Align) |
| : Stride(Stride), Scev(Scev), Size(Size), Align(Align) {} |
| |
| StrideDescriptor() : Stride(0), Scev(nullptr), Size(0), Align(0) {} |
| |
| int Stride; // The access's stride. It is negative for a reverse access. |
| const SCEV *Scev; // The scalar expression of this access |
| unsigned Size; // The size of the memory object. |
| unsigned Align; // The alignment of this access. |
| }; |
| |
| /// \brief Create a new interleave group with the given instruction \p Instr, |
| /// stride \p Stride and alignment \p Align. |
| /// |
| /// \returns the newly created interleave group. |
| InterleaveGroup *createInterleaveGroup(Instruction *Instr, int Stride, |
| unsigned Align) { |
| assert(!InterleaveGroupMap.count(Instr) && |
| "Already in an interleaved access group"); |
| InterleaveGroupMap[Instr] = new InterleaveGroup(Instr, Stride, Align); |
| return InterleaveGroupMap[Instr]; |
| } |
| |
| /// \brief Release the group and remove all the relationships. |
| void releaseGroup(InterleaveGroup *Group) { |
| for (unsigned i = 0; i < Group->getFactor(); i++) |
| if (Instruction *Member = Group->getMember(i)) |
| InterleaveGroupMap.erase(Member); |
| |
| delete Group; |
| } |
| |
| /// \brief Collect all the accesses with a constant stride in program order. |
| void collectConstStridedAccesses( |
| MapVector<Instruction *, StrideDescriptor> &StrideAccesses, |
| const ValueToValueMap &Strides); |
| }; |
| |
| /// LoopVectorizationLegality checks if it is legal to vectorize a loop, and |
| /// to what vectorization factor. |
| /// This class does not look at the profitability of vectorization, only the |
| /// legality. This class has two main kinds of checks: |
| /// * Memory checks - The code in canVectorizeMemory checks if vectorization |
| /// will change the order of memory accesses in a way that will change the |
| /// correctness of the program. |
| /// * Scalars checks - The code in canVectorizeInstrs and canVectorizeMemory |
| /// checks for a number of different conditions, such as the availability of a |
| /// single induction variable, that all types are supported and vectorize-able, |
| /// etc. This code reflects the capabilities of InnerLoopVectorizer. |
| /// This class is also used by InnerLoopVectorizer for identifying |
| /// induction variable and the different reduction variables. |
| class LoopVectorizationLegality { |
| public: |
| LoopVectorizationLegality(Loop *L, ScalarEvolution *SE, DominatorTree *DT, |
| TargetLibraryInfo *TLI, AliasAnalysis *AA, |
| Function *F, const TargetTransformInfo *TTI, |
| LoopAccessAnalysis *LAA) |
| : NumPredStores(0), TheLoop(L), SE(SE), TLI(TLI), TheFunction(F), |
| TTI(TTI), DT(DT), LAA(LAA), LAI(nullptr), InterleaveInfo(SE, L, DT), |
| Induction(nullptr), WidestIndTy(nullptr), HasFunNoNaNAttr(false) {} |
| |
| /// This enum represents the kinds of inductions that we support. |
| enum InductionKind { |
| IK_NoInduction, ///< Not an induction variable. |
| IK_IntInduction, ///< Integer induction variable. Step = C. |
| IK_PtrInduction ///< Pointer induction var. Step = C / sizeof(elem). |
| }; |
| |
| /// A struct for saving information about induction variables. |
| struct InductionInfo { |
| InductionInfo(Value *Start, InductionKind K, ConstantInt *Step) |
| : StartValue(Start), IK(K), StepValue(Step) { |
| assert(IK != IK_NoInduction && "Not an induction"); |
| assert(StartValue && "StartValue is null"); |
| assert(StepValue && !StepValue->isZero() && "StepValue is zero"); |
| assert((IK != IK_PtrInduction || StartValue->getType()->isPointerTy()) && |
| "StartValue is not a pointer for pointer induction"); |
| assert((IK != IK_IntInduction || StartValue->getType()->isIntegerTy()) && |
| "StartValue is not an integer for integer induction"); |
| assert(StepValue->getType()->isIntegerTy() && |
| "StepValue is not an integer"); |
| } |
| InductionInfo() |
| : StartValue(nullptr), IK(IK_NoInduction), StepValue(nullptr) {} |
| |
| /// Get the consecutive direction. Returns: |
| /// 0 - unknown or non-consecutive. |
| /// 1 - consecutive and increasing. |
| /// -1 - consecutive and decreasing. |
| int getConsecutiveDirection() const { |
| if (StepValue && (StepValue->isOne() || StepValue->isMinusOne())) |
| return StepValue->getSExtValue(); |
| return 0; |
| } |
| |
| /// Compute the transformed value of Index at offset StartValue using step |
| /// StepValue. |
| /// For integer induction, returns StartValue + Index * StepValue. |
| /// For pointer induction, returns StartValue[Index * StepValue]. |
| /// FIXME: The newly created binary instructions should contain nsw/nuw |
| /// flags, which can be found from the original scalar operations. |
| Value *transform(IRBuilder<> &B, Value *Index) const { |
| switch (IK) { |
| case IK_IntInduction: |
| assert(Index->getType() == StartValue->getType() && |
| "Index type does not match StartValue type"); |
| if (StepValue->isMinusOne()) |
| return B.CreateSub(StartValue, Index); |
| if (!StepValue->isOne()) |
| Index = B.CreateMul(Index, StepValue); |
| return B.CreateAdd(StartValue, Index); |
| |
| case IK_PtrInduction: |
| assert(Index->getType() == StepValue->getType() && |
| "Index type does not match StepValue type"); |
| if (StepValue->isMinusOne()) |
| Index = B.CreateNeg(Index); |
| else if (!StepValue->isOne()) |
| Index = B.CreateMul(Index, StepValue); |
| return B.CreateGEP(nullptr, StartValue, Index); |
| |
| case IK_NoInduction: |
| return nullptr; |
| } |
| llvm_unreachable("invalid enum"); |
| } |
| |
| /// Start value. |
| TrackingVH<Value> StartValue; |
| /// Induction kind. |
| InductionKind IK; |
| /// Step value. |
| ConstantInt *StepValue; |
| }; |
| |
| /// ReductionList contains the reduction descriptors for all |
| /// of the reductions that were found in the loop. |
| typedef DenseMap<PHINode *, RecurrenceDescriptor> ReductionList; |
| |
| /// InductionList saves induction variables and maps them to the |
| /// induction descriptor. |
| typedef MapVector<PHINode*, InductionInfo> InductionList; |
| |
| /// Returns true if it is legal to vectorize this loop. |
| /// This does not mean that it is profitable to vectorize this |
| /// loop, only that it is legal to do so. |
| bool canVectorize(); |
| |
| /// Returns the Induction variable. |
| PHINode *getInduction() { return Induction; } |
| |
| /// Returns the reduction variables found in the loop. |
| ReductionList *getReductionVars() { return &Reductions; } |
| |
| /// Returns the induction variables found in the loop. |
| InductionList *getInductionVars() { return &Inductions; } |
| |
| /// Returns the widest induction type. |
| Type *getWidestInductionType() { return WidestIndTy; } |
| |
| /// Returns True if V is an induction variable in this loop. |
| bool isInductionVariable(const Value *V); |
| |
| /// Return true if the block BB needs to be predicated in order for the loop |
| /// to be vectorized. |
| bool blockNeedsPredication(BasicBlock *BB); |
| |
| /// Check if this pointer is consecutive when vectorizing. This happens |
| /// when the last index of the GEP is the induction variable, or that the |
| /// pointer itself is an induction variable. |
| /// This check allows us to vectorize A[idx] into a wide load/store. |
| /// Returns: |
| /// 0 - Stride is unknown or non-consecutive. |
| /// 1 - Address is consecutive. |
| /// -1 - Address is consecutive, and decreasing. |
| int isConsecutivePtr(Value *Ptr); |
| |
| /// Returns true if the value V is uniform within the loop. |
| bool isUniform(Value *V); |
| |
| /// Returns true if this instruction will remain scalar after vectorization. |
| bool isUniformAfterVectorization(Instruction* I) { return Uniforms.count(I); } |
| |
| /// Returns the information that we collected about runtime memory check. |
| const RuntimePointerChecking *getRuntimePointerChecking() const { |
| return LAI->getRuntimePointerChecking(); |
| } |
| |
| const LoopAccessInfo *getLAI() const { |
| return LAI; |
| } |
| |
| /// \brief Check if \p Instr belongs to any interleaved access group. |
| bool isAccessInterleaved(Instruction *Instr) { |
| return InterleaveInfo.isInterleaved(Instr); |
| } |
| |
| /// \brief Get the interleaved access group that \p Instr belongs to. |
| const InterleaveGroup *getInterleavedAccessGroup(Instruction *Instr) { |
| return InterleaveInfo.getInterleaveGroup(Instr); |
| } |
| |
| unsigned getMaxSafeDepDistBytes() { return LAI->getMaxSafeDepDistBytes(); } |
| |
| bool hasStride(Value *V) { return StrideSet.count(V); } |
| bool mustCheckStrides() { return !StrideSet.empty(); } |
| SmallPtrSet<Value *, 8>::iterator strides_begin() { |
| return StrideSet.begin(); |
| } |
| SmallPtrSet<Value *, 8>::iterator strides_end() { return StrideSet.end(); } |
| |
| /// Returns true if the target machine supports masked store operation |
| /// for the given \p DataType and kind of access to \p Ptr. |
| bool isLegalMaskedStore(Type *DataType, Value *Ptr) { |
| return TTI->isLegalMaskedStore(DataType, isConsecutivePtr(Ptr)); |
| } |
| /// Returns true if the target machine supports masked load operation |
| /// for the given \p DataType and kind of access to \p Ptr. |
| bool isLegalMaskedLoad(Type *DataType, Value *Ptr) { |
| return TTI->isLegalMaskedLoad(DataType, isConsecutivePtr(Ptr)); |
| } |
| /// Returns true if vector representation of the instruction \p I |
| /// requires mask. |
| bool isMaskRequired(const Instruction* I) { |
| return (MaskedOp.count(I) != 0); |
| } |
| unsigned getNumStores() const { |
| return LAI->getNumStores(); |
| } |
| unsigned getNumLoads() const { |
| return LAI->getNumLoads(); |
| } |
| unsigned getNumPredStores() const { |
| return NumPredStores; |
| } |
| private: |
| /// Check if a single basic block loop is vectorizable. |
| /// At this point we know that this is a loop with a constant trip count |
| /// and we only need to check individual instructions. |
| bool canVectorizeInstrs(); |
| |
| /// When we vectorize loops we may change the order in which |
| /// we read and write from memory. This method checks if it is |
| /// legal to vectorize the code, considering only memory constrains. |
| /// Returns true if the loop is vectorizable |
| bool canVectorizeMemory(); |
| |
| /// Return true if we can vectorize this loop using the IF-conversion |
| /// transformation. |
| bool canVectorizeWithIfConvert(); |
| |
| /// Collect the variables that need to stay uniform after vectorization. |
| void collectLoopUniforms(); |
| |
| /// Return true if all of the instructions in the block can be speculatively |
| /// executed. \p SafePtrs is a list of addresses that are known to be legal |
| /// and we know that we can read from them without segfault. |
| bool blockCanBePredicated(BasicBlock *BB, SmallPtrSetImpl<Value *> &SafePtrs); |
| |
| /// Returns the induction kind of Phi and record the step. This function may |
| /// return NoInduction if the PHI is not an induction variable. |
| InductionKind isInductionVariable(PHINode *Phi, ConstantInt *&StepValue); |
| |
| /// \brief Collect memory access with loop invariant strides. |
| /// |
| /// Looks for accesses like "a[i * StrideA]" where "StrideA" is loop |
| /// invariant. |
| void collectStridedAccess(Value *LoadOrStoreInst); |
| |
| /// Report an analysis message to assist the user in diagnosing loops that are |
| /// not vectorized. These are handled as LoopAccessReport rather than |
| /// VectorizationReport because the << operator of VectorizationReport returns |
| /// LoopAccessReport. |
| void emitAnalysis(const LoopAccessReport &Message) { |
| LoopAccessReport::emitAnalysis(Message, TheFunction, TheLoop, LV_NAME); |
| } |
| |
| unsigned NumPredStores; |
| |
| /// The loop that we evaluate. |
| Loop *TheLoop; |
| /// Scev analysis. |
| ScalarEvolution *SE; |
| /// Target Library Info. |
| TargetLibraryInfo *TLI; |
| /// Parent function |
| Function *TheFunction; |
| /// Target Transform Info |
| const TargetTransformInfo *TTI; |
| /// Dominator Tree. |
| DominatorTree *DT; |
| // LoopAccess analysis. |
| LoopAccessAnalysis *LAA; |
| // And the loop-accesses info corresponding to this loop. This pointer is |
| // null until canVectorizeMemory sets it up. |
| const LoopAccessInfo *LAI; |
| |
| /// The interleave access information contains groups of interleaved accesses |
| /// with the same stride and close to each other. |
| InterleavedAccessInfo InterleaveInfo; |
| |
| // --- vectorization state --- // |
| |
| /// Holds the integer induction variable. This is the counter of the |
| /// loop. |
| PHINode *Induction; |
| /// Holds the reduction variables. |
| ReductionList Reductions; |
| /// Holds all of the induction variables that we found in the loop. |
| /// Notice that inductions don't need to start at zero and that induction |
| /// variables can be pointers. |
| InductionList Inductions; |
| /// Holds the widest induction type encountered. |
| Type *WidestIndTy; |
| |
| /// Allowed outside users. This holds the reduction |
| /// vars which can be accessed from outside the loop. |
| SmallPtrSet<Value*, 4> AllowedExit; |
| /// This set holds the variables which are known to be uniform after |
| /// vectorization. |
| SmallPtrSet<Instruction*, 4> Uniforms; |
| |
| /// Can we assume the absence of NaNs. |
| bool HasFunNoNaNAttr; |
| |
| ValueToValueMap Strides; |
| SmallPtrSet<Value *, 8> StrideSet; |
| |
| /// While vectorizing these instructions we have to generate a |
| /// call to the appropriate masked intrinsic |
| SmallPtrSet<const Instruction*, 8> MaskedOp; |
| }; |
| |
| /// LoopVectorizationCostModel - estimates the expected speedups due to |
| /// vectorization. |
| /// In many cases vectorization is not profitable. This can happen because of |
| /// a number of reasons. In this class we mainly attempt to predict the |
| /// expected speedup/slowdowns due to the supported instruction set. We use the |
| /// TargetTransformInfo to query the different backends for the cost of |
| /// different operations. |
| class LoopVectorizationCostModel { |
| public: |
| LoopVectorizationCostModel(Loop *L, ScalarEvolution *SE, LoopInfo *LI, |
| LoopVectorizationLegality *Legal, |
| const TargetTransformInfo &TTI, |
| const TargetLibraryInfo *TLI, AssumptionCache *AC, |
| const Function *F, const LoopVectorizeHints *Hints) |
| : TheLoop(L), SE(SE), LI(LI), Legal(Legal), TTI(TTI), TLI(TLI), |
| TheFunction(F), Hints(Hints) { |
| CodeMetrics::collectEphemeralValues(L, AC, EphValues); |
| } |
| |
| /// Information about vectorization costs |
| struct VectorizationFactor { |
| unsigned Width; // Vector width with best cost |
| unsigned Cost; // Cost of the loop with that width |
| }; |
| /// \return The most profitable vectorization factor and the cost of that VF. |
| /// This method checks every power of two up to VF. If UserVF is not ZERO |
| /// then this vectorization factor will be selected if vectorization is |
| /// possible. |
| VectorizationFactor selectVectorizationFactor(bool OptForSize); |
| |
| /// \return The size (in bits) of the widest type in the code that |
| /// needs to be vectorized. We ignore values that remain scalar such as |
| /// 64 bit loop indices. |
| unsigned getWidestType(); |
| |
| /// \return The desired interleave count. |
| /// If interleave count has been specified by metadata it will be returned. |
| /// Otherwise, the interleave count is computed and returned. VF and LoopCost |
| /// are the selected vectorization factor and the cost of the selected VF. |
| unsigned selectInterleaveCount(bool OptForSize, unsigned VF, |
| unsigned LoopCost); |
| |
| /// \return The most profitable unroll factor. |
| /// This method finds the best unroll-factor based on register pressure and |
| /// other parameters. VF and LoopCost are the selected vectorization factor |
| /// and the cost of the selected VF. |
| unsigned computeInterleaveCount(bool OptForSize, unsigned VF, |
| unsigned LoopCost); |
| |
| /// \brief A struct that represents some properties of the register usage |
| /// of a loop. |
| struct RegisterUsage { |
| /// Holds the number of loop invariant values that are used in the loop. |
| unsigned LoopInvariantRegs; |
| /// Holds the maximum number of concurrent live intervals in the loop. |
| unsigned MaxLocalUsers; |
| /// Holds the number of instructions in the loop. |
| unsigned NumInstructions; |
| }; |
| |
| /// \return information about the register usage of the loop. |
| RegisterUsage calculateRegisterUsage(); |
| |
| private: |
| /// Returns the expected execution cost. The unit of the cost does |
| /// not matter because we use the 'cost' units to compare different |
| /// vector widths. The cost that is returned is *not* normalized by |
| /// the factor width. |
| unsigned expectedCost(unsigned VF); |
| |
| /// Returns the execution time cost of an instruction for a given vector |
| /// width. Vector width of one means scalar. |
| unsigned getInstructionCost(Instruction *I, unsigned VF); |
| |
| /// Returns whether the instruction is a load or store and will be a emitted |
| /// as a vector operation. |
| bool isConsecutiveLoadOrStore(Instruction *I); |
| |
| /// Report an analysis message to assist the user in diagnosing loops that are |
| /// not vectorized. These are handled as LoopAccessReport rather than |
| /// VectorizationReport because the << operator of VectorizationReport returns |
| /// LoopAccessReport. |
| void emitAnalysis(const LoopAccessReport &Message) { |
| LoopAccessReport::emitAnalysis(Message, TheFunction, TheLoop, LV_NAME); |
| } |
| |
| /// Values used only by @llvm.assume calls. |
| SmallPtrSet<const Value *, 32> EphValues; |
| |
| /// The loop that we evaluate. |
| Loop *TheLoop; |
| /// Scev analysis. |
| ScalarEvolution *SE; |
| /// Loop Info analysis. |
| LoopInfo *LI; |
| /// Vectorization legality. |
| LoopVectorizationLegality *Legal; |
| /// Vector target information. |
| const TargetTransformInfo &TTI; |
| /// Target Library Info. |
| const TargetLibraryInfo *TLI; |
| const Function *TheFunction; |
| // Loop Vectorize Hint. |
| const LoopVectorizeHints *Hints; |
| }; |
| |
| /// Utility class for getting and setting loop vectorizer hints in the form |
| /// of loop metadata. |
| /// This class keeps a number of loop annotations locally (as member variables) |
| /// and can, upon request, write them back as metadata on the loop. It will |
| /// initially scan the loop for existing metadata, and will update the local |
| /// values based on information in the loop. |
| /// We cannot write all values to metadata, as the mere presence of some info, |
| /// for example 'force', means a decision has been made. So, we need to be |
| /// careful NOT to add them if the user hasn't specifically asked so. |
| class LoopVectorizeHints { |
| enum HintKind { |
| HK_WIDTH, |
| HK_UNROLL, |
| HK_FORCE |
| }; |
| |
| /// Hint - associates name and validation with the hint value. |
| struct Hint { |
| const char * Name; |
| unsigned Value; // This may have to change for non-numeric values. |
| HintKind Kind; |
| |
| Hint(const char * Name, unsigned Value, HintKind Kind) |
| : Name(Name), Value(Value), Kind(Kind) { } |
| |
| bool validate(unsigned Val) { |
| switch (Kind) { |
| case HK_WIDTH: |
| return isPowerOf2_32(Val) && Val <= VectorizerParams::MaxVectorWidth; |
| case HK_UNROLL: |
| return isPowerOf2_32(Val) && Val <= MaxInterleaveFactor; |
| case HK_FORCE: |
| return (Val <= 1); |
| } |
| return false; |
| } |
| }; |
| |
| /// Vectorization width. |
| Hint Width; |
| /// Vectorization interleave factor. |
| Hint Interleave; |
| /// Vectorization forced |
| Hint Force; |
| |
| /// Return the loop metadata prefix. |
| static StringRef Prefix() { return "llvm.loop."; } |
| |
| public: |
| enum ForceKind { |
| FK_Undefined = -1, ///< Not selected. |
| FK_Disabled = 0, ///< Forcing disabled. |
| FK_Enabled = 1, ///< Forcing enabled. |
| }; |
| |
| LoopVectorizeHints(const Loop *L, bool DisableInterleaving) |
| : Width("vectorize.width", VectorizerParams::VectorizationFactor, |
| HK_WIDTH), |
| Interleave("interleave.count", DisableInterleaving, HK_UNROLL), |
| Force("vectorize.enable", FK_Undefined, HK_FORCE), |
| TheLoop(L) { |
| // Populate values with existing loop metadata. |
| getHintsFromMetadata(); |
| |
| // force-vector-interleave overrides DisableInterleaving. |
| if (VectorizerParams::isInterleaveForced()) |
| Interleave.Value = VectorizerParams::VectorizationInterleave; |
| |
| DEBUG(if (DisableInterleaving && Interleave.Value == 1) dbgs() |
| << "LV: Interleaving disabled by the pass manager\n"); |
| } |
| |
| /// Mark the loop L as already vectorized by setting the width to 1. |
| void setAlreadyVectorized() { |
| Width.Value = Interleave.Value = 1; |
| Hint Hints[] = {Width, Interleave}; |
| writeHintsToMetadata(Hints); |
| } |
| |
| /// Dumps all the hint information. |
| std::string emitRemark() const { |
| VectorizationReport R; |
| if (Force.Value == LoopVectorizeHints::FK_Disabled) |
| R << "vectorization is explicitly disabled"; |
| else { |
| R << "use -Rpass-analysis=loop-vectorize for more info"; |
| if (Force.Value == LoopVectorizeHints::FK_Enabled) { |
| R << " (Force=true"; |
| if (Width.Value != 0) |
| R << ", Vector Width=" << Width.Value; |
| if (Interleave.Value != 0) |
| R << ", Interleave Count=" << Interleave.Value; |
| R << ")"; |
| } |
| } |
| |
| return R.str(); |
| } |
| |
| unsigned getWidth() const { return Width.Value; } |
| unsigned getInterleave() const { return Interleave.Value; } |
| enum ForceKind getForce() const { return (ForceKind)Force.Value; } |
| |
| private: |
| /// Find hints specified in the loop metadata and update local values. |
| void getHintsFromMetadata() { |
| MDNode *LoopID = TheLoop->getLoopID(); |
| if (!LoopID) |
| return; |
| |
| // First operand should refer to the loop id itself. |
| assert(LoopID->getNumOperands() > 0 && "requires at least one operand"); |
| assert(LoopID->getOperand(0) == LoopID && "invalid loop id"); |
| |
| for (unsigned i = 1, ie = LoopID->getNumOperands(); i < ie; ++i) { |
| const MDString *S = nullptr; |
| SmallVector<Metadata *, 4> Args; |
| |
| // The expected hint is either a MDString or a MDNode with the first |
| // operand a MDString. |
| if (const MDNode *MD = dyn_cast<MDNode>(LoopID->getOperand(i))) { |
| if (!MD || MD->getNumOperands() == 0) |
| continue; |
| S = dyn_cast<MDString>(MD->getOperand(0)); |
| for (unsigned i = 1, ie = MD->getNumOperands(); i < ie; ++i) |
| Args.push_back(MD->getOperand(i)); |
| } else { |
| S = dyn_cast<MDString>(LoopID->getOperand(i)); |
| assert(Args.size() == 0 && "too many arguments for MDString"); |
| } |
| |
| if (!S) |
| continue; |
| |
| // Check if the hint starts with the loop metadata prefix. |
| StringRef Name = S->getString(); |
| if (Args.size() == 1) |
| setHint(Name, Args[0]); |
| } |
| } |
| |
| /// Checks string hint with one operand and set value if valid. |
| void setHint(StringRef Name, Metadata *Arg) { |
| if (!Name.startswith(Prefix())) |
| return; |
| Name = Name.substr(Prefix().size(), StringRef::npos); |
| |
| const ConstantInt *C = mdconst::dyn_extract<ConstantInt>(Arg); |
| if (!C) return; |
| unsigned Val = C->getZExtValue(); |
| |
| Hint *Hints[] = {&Width, &Interleave, &Force}; |
| for (auto H : Hints) { |
| if (Name == H->Name) { |
| if (H->validate(Val)) |
| H->Value = Val; |
| else |
| DEBUG(dbgs() << "LV: ignoring invalid hint '" << Name << "'\n"); |
| break; |
| } |
| } |
| } |
| |
| /// Create a new hint from name / value pair. |
| MDNode *createHintMetadata(StringRef Name, unsigned V) const { |
| LLVMContext &Context = TheLoop->getHeader()->getContext(); |
| Metadata *MDs[] = {MDString::get(Context, Name), |
| ConstantAsMetadata::get( |
| ConstantInt::get(Type::getInt32Ty(Context), V))}; |
| return MDNode::get(Context, MDs); |
| } |
| |
| /// Matches metadata with hint name. |
| bool matchesHintMetadataName(MDNode *Node, ArrayRef<Hint> HintTypes) { |
| MDString* Name = dyn_cast<MDString>(Node->getOperand(0)); |
| if (!Name) |
| return false; |
| |
| for (auto H : HintTypes) |
| if (Name->getString().endswith(H.Name)) |
| return true; |
| return false; |
| } |
| |
| /// Sets current hints into loop metadata, keeping other values intact. |
| void writeHintsToMetadata(ArrayRef<Hint> HintTypes) { |
| if (HintTypes.size() == 0) |
| return; |
| |
| // Reserve the first element to LoopID (see below). |
| SmallVector<Metadata *, 4> MDs(1); |
| // If the loop already has metadata, then ignore the existing operands. |
| MDNode *LoopID = TheLoop->getLoopID(); |
| if (LoopID) { |
| for (unsigned i = 1, ie = LoopID->getNumOperands(); i < ie; ++i) { |
| MDNode *Node = cast<MDNode>(LoopID->getOperand(i)); |
| // If node in update list, ignore old value. |
| if (!matchesHintMetadataName(Node, HintTypes)) |
| MDs.push_back(Node); |
| } |
| } |
| |
| // Now, add the missing hints. |
| for (auto H : HintTypes) |
| MDs.push_back(createHintMetadata(Twine(Prefix(), H.Name).str(), H.Value)); |
| |
| // Replace current metadata node with new one. |
| LLVMContext &Context = TheLoop->getHeader()->getContext(); |
| MDNode *NewLoopID = MDNode::get(Context, MDs); |
| // Set operand 0 to refer to the loop id itself. |
| NewLoopID->replaceOperandWith(0, NewLoopID); |
| |
| TheLoop->setLoopID(NewLoopID); |
| } |
| |
| /// The loop these hints belong to. |
| const Loop *TheLoop; |
| }; |
| |
| static void emitMissedWarning(Function *F, Loop *L, |
| const LoopVectorizeHints &LH) { |
| emitOptimizationRemarkMissed(F->getContext(), DEBUG_TYPE, *F, |
| L->getStartLoc(), LH.emitRemark()); |
| |
| if (LH.getForce() == LoopVectorizeHints::FK_Enabled) { |
| if (LH.getWidth() != 1) |
| emitLoopVectorizeWarning( |
| F->getContext(), *F, L->getStartLoc(), |
| "failed explicitly specified loop vectorization"); |
| else if (LH.getInterleave() != 1) |
| emitLoopInterleaveWarning( |
| F->getContext(), *F, L->getStartLoc(), |
| "failed explicitly specified loop interleaving"); |
| } |
| } |
| |
| static void addInnerLoop(Loop &L, SmallVectorImpl<Loop *> &V) { |
| if (L.empty()) |
| return V.push_back(&L); |
| |
| for (Loop *InnerL : L) |
| addInnerLoop(*InnerL, V); |
| } |
| |
| /// The LoopVectorize Pass. |
| struct LoopVectorize : public FunctionPass { |
| /// Pass identification, replacement for typeid |
| static char ID; |
| |
| explicit LoopVectorize(bool NoUnrolling = false, bool AlwaysVectorize = true) |
| : FunctionPass(ID), |
| DisableUnrolling(NoUnrolling), |
| AlwaysVectorize(AlwaysVectorize) { |
| initializeLoopVectorizePass(*PassRegistry::getPassRegistry()); |
| } |
| |
| ScalarEvolution *SE; |
| LoopInfo *LI; |
| TargetTransformInfo *TTI; |
| DominatorTree *DT; |
| BlockFrequencyInfo *BFI; |
| TargetLibraryInfo *TLI; |
| AliasAnalysis *AA; |
| AssumptionCache *AC; |
| LoopAccessAnalysis *LAA; |
| bool DisableUnrolling; |
| bool AlwaysVectorize; |
| |
| BlockFrequency ColdEntryFreq; |
| |
| bool runOnFunction(Function &F) override { |
| SE = &getAnalysis<ScalarEvolution>(); |
| LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo(); |
| TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F); |
| DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree(); |
| BFI = &getAnalysis<BlockFrequencyInfo>(); |
| auto *TLIP = getAnalysisIfAvailable<TargetLibraryInfoWrapperPass>(); |
| TLI = TLIP ? &TLIP->getTLI() : nullptr; |
| AA = &getAnalysis<AliasAnalysis>(); |
| AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F); |
| LAA = &getAnalysis<LoopAccessAnalysis>(); |
| |
| // Compute some weights outside of the loop over the loops. Compute this |
| // using a BranchProbability to re-use its scaling math. |
| const BranchProbability ColdProb(1, 5); // 20% |
| ColdEntryFreq = BlockFrequency(BFI->getEntryFreq()) * ColdProb; |
| |
| // Don't attempt if |
| // 1. the target claims to have no vector registers, and |
| // 2. interleaving won't help ILP. |
| // |
| // The second condition is necessary because, even if the target has no |
| // vector registers, loop vectorization may still enable scalar |
| // interleaving. |
| if (!TTI->getNumberOfRegisters(true) && TTI->getMaxInterleaveFactor(1) < 2) |
| return false; |
| |
| // Build up a worklist of inner-loops to vectorize. This is necessary as |
| // the act of vectorizing or partially unrolling a loop creates new loops |
| // and can invalidate iterators across the loops. |
| SmallVector<Loop *, 8> Worklist; |
| |
| for (Loop *L : *LI) |
| addInnerLoop(*L, Worklist); |
| |
| LoopsAnalyzed += Worklist.size(); |
| |
| // Now walk the identified inner loops. |
| bool Changed = false; |
| while (!Worklist.empty()) |
| Changed |= processLoop(Worklist.pop_back_val()); |
| |
| // Process each loop nest in the function. |
| return Changed; |
| } |
| |
| static void AddRuntimeUnrollDisableMetaData(Loop *L) { |
| SmallVector<Metadata *, 4> MDs; |
| // Reserve first location for self reference to the LoopID metadata node. |
| MDs.push_back(nullptr); |
| bool IsUnrollMetadata = false; |
| MDNode *LoopID = L->getLoopID(); |
| if (LoopID) { |
| // First find existing loop unrolling disable metadata. |
| for (unsigned i = 1, ie = LoopID->getNumOperands(); i < ie; ++i) { |
| MDNode *MD = dyn_cast<MDNode>(LoopID->getOperand(i)); |
| if (MD) { |
| const MDString *S = dyn_cast<MDString>(MD->getOperand(0)); |
| IsUnrollMetadata = |
| S && S->getString().startswith("llvm.loop.unroll.disable"); |
| } |
| MDs.push_back(LoopID->getOperand(i)); |
| } |
| } |
| |
| if (!IsUnrollMetadata) { |
| // Add runtime unroll disable metadata. |
| LLVMContext &Context = L->getHeader()->getContext(); |
| SmallVector<Metadata *, 1> DisableOperands; |
| DisableOperands.push_back( |
| MDString::get(Context, "llvm.loop.unroll.runtime.disable")); |
| MDNode *DisableNode = MDNode::get(Context, DisableOperands); |
| MDs.push_back(DisableNode); |
| MDNode *NewLoopID = MDNode::get(Context, MDs); |
| // Set operand 0 to refer to the loop id itself. |
| NewLoopID->replaceOperandWith(0, NewLoopID); |
| L->setLoopID(NewLoopID); |
| } |
| } |
| |
| bool processLoop(Loop *L) { |
| assert(L->empty() && "Only process inner loops."); |
| |
| #ifndef NDEBUG |
| const std::string DebugLocStr = getDebugLocString(L); |
| #endif /* NDEBUG */ |
| |
| DEBUG(dbgs() << "\nLV: Checking a loop in \"" |
| << L->getHeader()->getParent()->getName() << "\" from " |
| << DebugLocStr << "\n"); |
| |
| LoopVectorizeHints Hints(L, DisableUnrolling); |
| |
| DEBUG(dbgs() << "LV: Loop hints:" |
| << " force=" |
| << (Hints.getForce() == LoopVectorizeHints::FK_Disabled |
| ? "disabled" |
| : (Hints.getForce() == LoopVectorizeHints::FK_Enabled |
| ? "enabled" |
| : "?")) << " width=" << Hints.getWidth() |
| << " unroll=" << Hints.getInterleave() << "\n"); |
| |
| // Function containing loop |
| Function *F = L->getHeader()->getParent(); |
| |
| // Looking at the diagnostic output is the only way to determine if a loop |
| // was vectorized (other than looking at the IR or machine code), so it |
| // is important to generate an optimization remark for each loop. Most of |
| // these messages are generated by emitOptimizationRemarkAnalysis. Remarks |
| // generated by emitOptimizationRemark and emitOptimizationRemarkMissed are |
| // less verbose reporting vectorized loops and unvectorized loops that may |
| // benefit from vectorization, respectively. |
| |
| if (Hints.getForce() == LoopVectorizeHints::FK_Disabled) { |
| DEBUG(dbgs() << "LV: Not vectorizing: #pragma vectorize disable.\n"); |
| emitOptimizationRemarkAnalysis(F->getContext(), DEBUG_TYPE, *F, |
| L->getStartLoc(), Hints.emitRemark()); |
| return false; |
| } |
| |
| if (!AlwaysVectorize && Hints.getForce() != LoopVectorizeHints::FK_Enabled) { |
| DEBUG(dbgs() << "LV: Not vectorizing: No #pragma vectorize enable.\n"); |
| emitOptimizationRemarkAnalysis(F->getContext(), DEBUG_TYPE, *F, |
| L->getStartLoc(), Hints.emitRemark()); |
| return false; |
| } |
| |
| if (Hints.getWidth() == 1 && Hints.getInterleave() == 1) { |
| DEBUG(dbgs() << "LV: Not vectorizing: Disabled/already vectorized.\n"); |
| emitOptimizationRemarkAnalysis( |
| F->getContext(), DEBUG_TYPE, *F, L->getStartLoc(), |
| "loop not vectorized: vector width and interleave count are " |
| "explicitly set to 1"); |
| return false; |
| } |
| |
| // Check the loop for a trip count threshold: |
| // do not vectorize loops with a tiny trip count. |
| const unsigned TC = SE->getSmallConstantTripCount(L); |
| if (TC > 0u && TC < TinyTripCountVectorThreshold) { |
| DEBUG(dbgs() << "LV: Found a loop with a very small trip count. " |
| << "This loop is not worth vectorizing."); |
| if (Hints.getForce() == LoopVectorizeHints::FK_Enabled) |
| DEBUG(dbgs() << " But vectorizing was explicitly forced.\n"); |
| else { |
| DEBUG(dbgs() << "\n"); |
| emitOptimizationRemarkAnalysis( |
| F->getContext(), DEBUG_TYPE, *F, L->getStartLoc(), |
| "vectorization is not beneficial and is not explicitly forced"); |
| return false; |
| } |
| } |
| |
| // Check if it is legal to vectorize the loop. |
| LoopVectorizationLegality LVL(L, SE, DT, TLI, AA, F, TTI, LAA); |
| if (!LVL.canVectorize()) { |
| DEBUG(dbgs() << "LV: Not vectorizing: Cannot prove legality.\n"); |
| emitMissedWarning(F, L, Hints); |
| return false; |
| } |
| |
| // Use the cost model. |
| LoopVectorizationCostModel CM(L, SE, LI, &LVL, *TTI, TLI, AC, F, &Hints); |
| |
| // Check the function attributes to find out if this function should be |
| // optimized for size. |
| bool OptForSize = Hints.getForce() != LoopVectorizeHints::FK_Enabled && |
| F->hasFnAttribute(Attribute::OptimizeForSize); |
| |
| // Compute the weighted frequency of this loop being executed and see if it |
| // is less than 20% of the function entry baseline frequency. Note that we |
| // always have a canonical loop here because we think we *can* vectoriez. |
| // FIXME: This is hidden behind a flag due to pervasive problems with |
| // exactly what block frequency models. |
| if (LoopVectorizeWithBlockFrequency) { |
| BlockFrequency LoopEntryFreq = BFI->getBlockFreq(L->getLoopPreheader()); |
| if (Hints.getForce() != LoopVectorizeHints::FK_Enabled && |
| LoopEntryFreq < ColdEntryFreq) |
| OptForSize = true; |
| } |
| |
| // Check the function attributes to see if implicit floats are allowed.a |
| // FIXME: This check doesn't seem possibly correct -- what if the loop is |
| // an integer loop and the vector instructions selected are purely integer |
| // vector instructions? |
| if (F->hasFnAttribute(Attribute::NoImplicitFloat)) { |
| DEBUG(dbgs() << "LV: Can't vectorize when the NoImplicitFloat" |
| "attribute is used.\n"); |
| emitOptimizationRemarkAnalysis( |
| F->getContext(), DEBUG_TYPE, *F, L->getStartLoc(), |
| "loop not vectorized due to NoImplicitFloat attribute"); |
| emitMissedWarning(F, L, Hints); |
| return false; |
| } |
| |
| // Select the optimal vectorization factor. |
| const LoopVectorizationCostModel::VectorizationFactor VF = |
| CM.selectVectorizationFactor(OptForSize); |
| |
| // Select the interleave count. |
| unsigned IC = CM.selectInterleaveCount(OptForSize, VF.Width, VF.Cost); |
| |
| DEBUG(dbgs() << "LV: Found a vectorizable loop (" << VF.Width << ") in " |
| << DebugLocStr << '\n'); |
| DEBUG(dbgs() << "LV: Interleave Count is " << IC << '\n'); |
| |
| if (VF.Width == 1) { |
| DEBUG(dbgs() << "LV: Vectorization is possible but not beneficial\n"); |
| |
| if (IC == 1) { |
| emitOptimizationRemarkAnalysis( |
| F->getContext(), DEBUG_TYPE, *F, L->getStartLoc(), |
| "not beneficial to vectorize and user disabled interleaving"); |
| return false; |
| } |
| DEBUG(dbgs() << "LV: Trying to at least unroll the loops.\n"); |
| |
| // Report the unrolling decision. |
| emitOptimizationRemark(F->getContext(), DEBUG_TYPE, *F, L->getStartLoc(), |
| Twine("interleaved by " + Twine(IC) + |
| " (vectorization not beneficial)")); |
| |
| InnerLoopUnroller Unroller(L, SE, LI, DT, TLI, TTI, IC); |
| Unroller.vectorize(&LVL); |
| } else { |
| // If we decided that it is *legal* to vectorize the loop then do it. |
| InnerLoopVectorizer LB(L, SE, LI, DT, TLI, TTI, VF.Width, IC); |
| LB.vectorize(&LVL); |
| ++LoopsVectorized; |
| |
| // Add metadata to disable runtime unrolling scalar loop when there's no |
| // runtime check about strides and memory. Because at this situation, |
| // scalar loop is rarely used not worthy to be unrolled. |
| if (!LB.IsSafetyChecksAdded()) |
| AddRuntimeUnrollDisableMetaData(L); |
| |
| // Report the vectorization decision. |
| emitOptimizationRemark(F->getContext(), DEBUG_TYPE, *F, L->getStartLoc(), |
| Twine("vectorized loop (vectorization width: ") + |
| Twine(VF.Width) + ", interleaved count: " + |
| Twine(IC) + ")"); |
| } |
| |
| // Mark the loop as already vectorized to avoid vectorizing again. |
| Hints.setAlreadyVectorized(); |
| |
| DEBUG(verifyFunction(*L->getHeader()->getParent())); |
| return true; |
| } |
| |
| void getAnalysisUsage(AnalysisUsage &AU) const override { |
| AU.addRequired<AssumptionCacheTracker>(); |
| AU.addRequiredID(LoopSimplifyID); |
| AU.addRequiredID(LCSSAID); |
| AU.addRequired<BlockFrequencyInfo>(); |
| AU.addRequired<DominatorTreeWrapperPass>(); |
| AU.addRequired<LoopInfoWrapperPass>(); |
| AU.addRequired<ScalarEvolution>(); |
| AU.addRequired<TargetTransformInfoWrapperPass>(); |
| AU.addRequired<AliasAnalysis>(); |
| AU.addRequired<LoopAccessAnalysis>(); |
| AU.addPreserved<LoopInfoWrapperPass>(); |
| AU.addPreserved<DominatorTreeWrapperPass>(); |
| AU.addPreserved<AliasAnalysis>(); |
| } |
| |
| }; |
| |
| } // end anonymous namespace |
| |
| //===----------------------------------------------------------------------===// |
| // Implementation of LoopVectorizationLegality, InnerLoopVectorizer and |
| // LoopVectorizationCostModel. |
| //===----------------------------------------------------------------------===// |
| |
| Value *InnerLoopVectorizer::getBroadcastInstrs(Value *V) { |
| // We need to place the broadcast of invariant variables outside the loop. |
| Instruction *Instr = dyn_cast<Instruction>(V); |
| bool NewInstr = |
| (Instr && std::find(LoopVectorBody.begin(), LoopVectorBody.end(), |
| Instr->getParent()) != LoopVectorBody.end()); |
| bool Invariant = OrigLoop->isLoopInvariant(V) && !NewInstr; |
| |
| // Place the code for broadcasting invariant variables in the new preheader. |
| IRBuilder<>::InsertPointGuard Guard(Builder); |
| if (Invariant) |
| Builder.SetInsertPoint(LoopVectorPreHeader->getTerminator()); |
| |
| // Broadcast the scalar into all locations in the vector. |
| Value *Shuf = Builder.CreateVectorSplat(VF, V, "broadcast"); |
| |
| return Shuf; |
| } |
| |
| Value *InnerLoopVectorizer::getStepVector(Value *Val, int StartIdx, |
| Value *Step) { |
| assert(Val->getType()->isVectorTy() && "Must be a vector"); |
| assert(Val->getType()->getScalarType()->isIntegerTy() && |
| "Elem must be an integer"); |
| assert(Step->getType() == Val->getType()->getScalarType() && |
| "Step has wrong type"); |
| // Create the types. |
| Type *ITy = Val->getType()->getScalarType(); |
| VectorType *Ty = cast<VectorType>(Val->getType()); |
| int VLen = Ty->getNumElements(); |
| SmallVector<Constant*, 8> Indices; |
| |
| // Create a vector of consecutive numbers from zero to VF. |
| for (int i = 0; i < VLen; ++i) |
| Indices.push_back(ConstantInt::get(ITy, StartIdx + i)); |
| |
| // Add the consecutive indices to the vector value. |
| Constant *Cv = ConstantVector::get(Indices); |
| assert(Cv->getType() == Val->getType() && "Invalid consecutive vec"); |
| Step = Builder.CreateVectorSplat(VLen, Step); |
| assert(Step->getType() == Val->getType() && "Invalid step vec"); |
| // FIXME: The newly created binary instructions should contain nsw/nuw flags, |
| // which can be found from the original scalar operations. |
| Step = Builder.CreateMul(Cv, Step); |
| return Builder.CreateAdd(Val, Step, "induction"); |
| } |
| |
| int LoopVectorizationLegality::isConsecutivePtr(Value *Ptr) { |
| assert(Ptr->getType()->isPointerTy() && "Unexpected non-ptr"); |
| // Make sure that the pointer does not point to structs. |
| if (Ptr->getType()->getPointerElementType()->isAggregateType()) |
| return 0; |
| |
| // If this value is a pointer induction variable we know it is consecutive. |
| PHINode *Phi = dyn_cast_or_null<PHINode>(Ptr); |
| if (Phi && Inductions.count(Phi)) { |
| InductionInfo II = Inductions[Phi]; |
| return II.getConsecutiveDirection(); |
| } |
| |
| GetElementPtrInst *Gep = dyn_cast_or_null<GetElementPtrInst>(Ptr); |
| if (!Gep) |
| return 0; |
| |
| unsigned NumOperands = Gep->getNumOperands(); |
| Value *GpPtr = Gep->getPointerOperand(); |
| // If this GEP value is a consecutive pointer induction variable and all of |
| // the indices are constant then we know it is consecutive. We can |
| Phi = dyn_cast<PHINode>(GpPtr); |
| if (Phi && Inductions.count(Phi)) { |
| |
| // Make sure that the pointer does not point to structs. |
| PointerType *GepPtrType = cast<PointerType>(GpPtr->getType()); |
| if (GepPtrType->getElementType()->isAggregateType()) |
| return 0; |
| |
| // Make sure that all of the index operands are loop invariant. |
| for (unsigned i = 1; i < NumOperands; ++i) |
| if (!SE->isLoopInvariant(SE->getSCEV(Gep->getOperand(i)), TheLoop)) |
| return 0; |
| |
| InductionInfo II = Inductions[Phi]; |
| return II.getConsecutiveDirection(); |
| } |
| |
| unsigned InductionOperand = getGEPInductionOperand(Gep); |
| |
| // Check that all of the gep indices are uniform except for our induction |
| // operand. |
| for (unsigned i = 0; i != NumOperands; ++i) |
| if (i != InductionOperand && |
| !SE->isLoopInvariant(SE->getSCEV(Gep->getOperand(i)), TheLoop)) |
| return 0; |
| |
| // We can emit wide load/stores only if the last non-zero index is the |
| // induction variable. |
| const SCEV *Last = nullptr; |
| if (!Strides.count(Gep)) |
| Last = SE->getSCEV(Gep->getOperand(InductionOperand)); |
| else { |
| // Because of the multiplication by a stride we can have a s/zext cast. |
| // We are going to replace this stride by 1 so the cast is safe to ignore. |
| // |
| // %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ] |
| // %0 = trunc i64 %indvars.iv to i32 |
| // %mul = mul i32 %0, %Stride1 |
| // %idxprom = zext i32 %mul to i64 << Safe cast. |
| // %arrayidx = getelementptr inbounds i32* %B, i64 %idxprom |
| // |
| Last = replaceSymbolicStrideSCEV(SE, Strides, |
| Gep->getOperand(InductionOperand), Gep); |
| if (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(Last)) |
| Last = |
| (C->getSCEVType() == scSignExtend || C->getSCEVType() == scZeroExtend) |
| ? C->getOperand() |
| : Last; |
| } |
| if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Last)) { |
| const SCEV *Step = AR->getStepRecurrence(*SE); |
| |
| // The memory is consecutive because the last index is consecutive |
| // and all other indices are loop invariant. |
| if (Step->isOne()) |
| return 1; |
| if (Step->isAllOnesValue()) |
| return -1; |
| } |
| |
| return 0; |
| } |
| |
| bool LoopVectorizationLegality::isUniform(Value *V) { |
| return LAI->isUniform(V); |
| } |
| |
| InnerLoopVectorizer::VectorParts& |
| InnerLoopVectorizer::getVectorValue(Value *V) { |
| assert(V != Induction && "The new induction variable should not be used."); |
| assert(!V->getType()->isVectorTy() && "Can't widen a vector"); |
| |
| // If we have a stride that is replaced by one, do it here. |
| if (Legal->hasStride(V)) |
| V = ConstantInt::get(V->getType(), 1); |
| |
| // If we have this scalar in the map, return it. |
| if (WidenMap.has(V)) |
| return WidenMap.get(V); |
| |
| // If this scalar is unknown, assume that it is a constant or that it is |
| // loop invariant. Broadcast V and save the value for future uses. |
| Value *B = getBroadcastInstrs(V); |
| return WidenMap.splat(V, B); |
| } |
| |
| Value *InnerLoopVectorizer::reverseVector(Value *Vec) { |
| assert(Vec->getType()->isVectorTy() && "Invalid type"); |
| SmallVector<Constant*, 8> ShuffleMask; |
| for (unsigned i = 0; i < VF; ++i) |
| ShuffleMask.push_back(Builder.getInt32(VF - i - 1)); |
| |
| return Builder.CreateShuffleVector(Vec, UndefValue::get(Vec->getType()), |
| ConstantVector::get(ShuffleMask), |
| "reverse"); |
| } |
| |
| // Get a mask to interleave \p NumVec vectors into a wide vector. |
| // I.e. <0, VF, VF*2, ..., VF*(NumVec-1), 1, VF+1, VF*2+1, ...> |
| // E.g. For 2 interleaved vectors, if VF is 4, the mask is: |
| // <0, 4, 1, 5, 2, 6, 3, 7> |
| static Constant *getInterleavedMask(IRBuilder<> &Builder, unsigned VF, |
| unsigned NumVec) { |
| SmallVector<Constant *, 16> Mask; |
| for (unsigned i = 0; i < VF; i++) |
| for (unsigned j = 0; j < NumVec; j++) |
| Mask.push_back(Builder.getInt32(j * VF + i)); |
| |
| return ConstantVector::get(Mask); |
| } |
| |
| // Get the strided mask starting from index \p Start. |
| // I.e. <Start, Start + Stride, ..., Start + Stride*(VF-1)> |
| static Constant *getStridedMask(IRBuilder<> &Builder, unsigned Start, |
| unsigned Stride, unsigned VF) { |
| SmallVector<Constant *, 16> Mask; |
| for (unsigned i = 0; i < VF; i++) |
| Mask.push_back(Builder.getInt32(Start + i * Stride)); |
| |
| return ConstantVector::get(Mask); |
| } |
| |
| // Get a mask of two parts: The first part consists of sequential integers |
| // starting from 0, The second part consists of UNDEFs. |
| // I.e. <0, 1, 2, ..., NumInt - 1, undef, ..., undef> |
| static Constant *getSequentialMask(IRBuilder<> &Builder, unsigned NumInt, |
| unsigned NumUndef) { |
| SmallVector<Constant *, 16> Mask; |
| for (unsigned i = 0; i < NumInt; i++) |
| Mask.push_back(Builder.getInt32(i)); |
| |
| Constant *Undef = UndefValue::get(Builder.getInt32Ty()); |
| for (unsigned i = 0; i < NumUndef; i++) |
| Mask.push_back(Undef); |
| |
| return ConstantVector::get(Mask); |
| } |
| |
| // Concatenate two vectors with the same element type. The 2nd vector should |
| // not have more elements than the 1st vector. If the 2nd vector has less |
| // elements, extend it with UNDEFs. |
| static Value *ConcatenateTwoVectors(IRBuilder<> &Builder, Value *V1, |
| Value *V2) { |
| VectorType *VecTy1 = dyn_cast<VectorType>(V1->getType()); |
| VectorType *VecTy2 = dyn_cast<VectorType>(V2->getType()); |
| assert(VecTy1 && VecTy2 && |
| VecTy1->getScalarType() == VecTy2->getScalarType() && |
| "Expect two vectors with the same element type"); |
| |
| unsigned NumElts1 = VecTy1->getNumElements(); |
| unsigned NumElts2 = VecTy2->getNumElements(); |
| assert(NumElts1 >= NumElts2 && "Unexpect the first vector has less elements"); |
| |
| if (NumElts1 > NumElts2) { |
| // Extend with UNDEFs. |
| Constant *ExtMask = |
| getSequentialMask(Builder, NumElts2, NumElts1 - NumElts2); |
| V2 = Builder.CreateShuffleVector(V2, UndefValue::get(VecTy2), ExtMask); |
| } |
| |
| Constant *Mask = getSequentialMask(Builder, NumElts1 + NumElts2, 0); |
| return Builder.CreateShuffleVector(V1, V2, Mask); |
| } |
| |
| // Concatenate vectors in the given list. All vectors have the same type. |
| static Value *ConcatenateVectors(IRBuilder<> &Builder, |
| ArrayRef<Value *> InputList) { |
| unsigned NumVec = InputList.size(); |
| assert(NumVec > 1 && "Should be at least two vectors"); |
| |
| SmallVector<Value *, 8> ResList; |
| ResList.append(InputList.begin(), InputList.end()); |
| do { |
| SmallVector<Value *, 8> TmpList; |
| for (unsigned i = 0; i < NumVec - 1; i += 2) { |
| Value *V0 = ResList[i], *V1 = ResList[i + 1]; |
| assert((V0->getType() == V1->getType() || i == NumVec - 2) && |
| "Only the last vector may have a different type"); |
| |
| TmpList.push_back(ConcatenateTwoVectors(Builder, V0, V1)); |
| } |
| |
| // Push the last vector if the total number of vectors is odd. |
| if (NumVec % 2 != 0) |
| TmpList.push_back(ResList[NumVec - 1]); |
| |
| ResList = TmpList; |
| NumVec = ResList.size(); |
| } while (NumVec > 1); |
| |
| return ResList[0]; |
| } |
| |
| // Try to vectorize the interleave group that \p Instr belongs to. |
| // |
| // E.g. Translate following interleaved load group (factor = 3): |
| // for (i = 0; i < N; i+=3) { |
| // R = Pic[i]; // Member of index 0 |
| // G = Pic[i+1]; // Member of index 1 |
| // B = Pic[i+2]; // Member of index 2 |
| // ... // do something to R, G, B |
| // } |
| // To: |
| // %wide.vec = load <12 x i32> ; Read 4 tuples of R,G,B |
| // %R.vec = shuffle %wide.vec, undef, <0, 3, 6, 9> ; R elements |
| // %G.vec = shuffle %wide.vec, undef, <1, 4, 7, 10> ; G elements |
| // %B.vec = shuffle %wide.vec, undef, <2, 5, 8, 11> ; B elements |
| // |
| // Or translate following interleaved store group (factor = 3): |
| // for (i = 0; i < N; i+=3) { |
| // ... do something to R, G, B |
| // Pic[i] = R; // Member of index 0 |
| // Pic[i+1] = G; // Member of index 1 |
| // Pic[i+2] = B; // Member of index 2 |
| // } |
| // To: |
| // %R_G.vec = shuffle %R.vec, %G.vec, <0, 1, 2, ..., 7> |
| // %B_U.vec = shuffle %B.vec, undef, <0, 1, 2, 3, u, u, u, u> |
| // %interleaved.vec = shuffle %R_G.vec, %B_U.vec, |
| // <0, 4, 8, 1, 5, 9, 2, 6, 10, 3, 7, 11> ; Interleave R,G,B elements |
| // store <12 x i32> %interleaved.vec ; Write 4 tuples of R,G,B |
| void InnerLoopVectorizer::vectorizeInterleaveGroup(Instruction *Instr) { |
| const InterleaveGroup *Group = Legal->getInterleavedAccessGroup(Instr); |
| assert(Group && "Fail to get an interleaved access group."); |
| |
| // Skip if current instruction is not the insert position. |
| if (Instr != Group->getInsertPos()) |
| return; |
| |
| LoadInst *LI = dyn_cast<LoadInst>(Instr); |
| StoreInst *SI = dyn_cast<StoreInst>(Instr); |
| Value *Ptr = LI ? LI->getPointerOperand() : SI->getPointerOperand(); |
| |
| // Prepare for the vector type of the interleaved load/store. |
| Type *ScalarTy = LI ? LI->getType() : SI->getValueOperand()->getType(); |
| unsigned InterleaveFactor = Group->getFactor(); |
| Type *VecTy = VectorType::get(ScalarTy, InterleaveFactor * VF); |
| Type *PtrTy = VecTy->getPointerTo(Ptr->getType()->getPointerAddressSpace()); |
| |
| // Prepare for the new pointers. |
| setDebugLocFromInst(Builder, Ptr); |
| VectorParts &PtrParts = getVectorValue(Ptr); |
| SmallVector<Value *, 2> NewPtrs; |
| unsigned Index = Group->getIndex(Instr); |
| for (unsigned Part = 0; Part < UF; Part++) { |
| // Extract the pointer for current instruction from the pointer vector. A |
| // reverse access uses the pointer in the last lane. |
| Value *NewPtr = Builder.CreateExtractElement( |
| PtrParts[Part], |
| Group->isReverse() ? Builder.getInt32(VF - 1) : Builder.getInt32(0)); |
| |
| // Notice current instruction could be any index. Need to adjust the address |
| // to the member of index 0. |
| // |
| // E.g. a = A[i+1]; // Member of index 1 (Current instruction) |
| // b = A[i]; // Member of index 0 |
| // Current pointer is pointed to A[i+1], adjust it to A[i]. |
| // |
| // E.g. A[i+1] = a; // Member of index 1 |
| // A[i] = b; // Member of index 0 |
| // A[i+2] = c; // Member of index 2 (Current instruction) |
| // Current pointer is pointed to A[i+2], adjust it to A[i]. |
| NewPtr = Builder.CreateGEP(NewPtr, Builder.getInt32(-Index)); |
| |
| // Cast to the vector pointer type. |
| NewPtrs.push_back(Builder.CreateBitCast(NewPtr, PtrTy)); |
| } |
| |
| setDebugLocFromInst(Builder, Instr); |
| Value *UndefVec = UndefValue::get(VecTy); |
| |
| // Vectorize the interleaved load group. |
| if (LI) { |
| for (unsigned Part = 0; Part < UF; Part++) { |
| Instruction *NewLoadInstr = Builder.CreateAlignedLoad( |
| NewPtrs[Part], Group->getAlignment(), "wide.vec"); |
| |
| for (unsigned i = 0; i < InterleaveFactor; i++) { |
| Instruction *Member = Group->getMember(i); |
| |
| // Skip the gaps in the group. |
| if (!Member) |
| continue; |
| |
| Constant *StrideMask = getStridedMask(Builder, i, InterleaveFactor, VF); |
| Value *StridedVec = Builder.CreateShuffleVector( |
| NewLoadInstr, UndefVec, StrideMask, "strided.vec"); |
| |
| // If this member has different type, cast the result type. |
| if (Member->getType() != ScalarTy) { |
| VectorType *OtherVTy = VectorType::get(Member->getType(), VF); |
| StridedVec = Builder.CreateBitOrPointerCast(StridedVec, OtherVTy); |
| } |
| |
| VectorParts &Entry = WidenMap.get(Member); |
| Entry[Part] = |
| Group->isReverse() ? reverseVector(StridedVec) : StridedVec; |
| } |
| |
| propagateMetadata(NewLoadInstr, Instr); |
| } |
| return; |
| } |
| |
| // The sub vector type for current instruction. |
| VectorType *SubVT = VectorType::get(ScalarTy, VF); |
| |
| // Vectorize the interleaved store group. |
| for (unsigned Part = 0; Part < UF; Part++) { |
| // Collect the stored vector from each member. |
| SmallVector<Value *, 4> StoredVecs; |
| for (unsigned i = 0; i < InterleaveFactor; i++) { |
| // Interleaved store group doesn't allow a gap, so each index has a member |
| Instruction *Member = Group->getMember(i); |
| assert(Member && "Fail to get a member from an interleaved store group"); |
| |
| Value *StoredVec = |
| getVectorValue(dyn_cast<StoreInst>(Member)->getValueOperand())[Part]; |
| if (Group->isReverse()) |
| StoredVec = reverseVector(StoredVec); |
| |
| // If this member has different type, cast it to an unified type. |
| if (StoredVec->getType() != SubVT) |
| StoredVec = Builder.CreateBitOrPointerCast(StoredVec, SubVT); |
| |
| StoredVecs.push_back(StoredVec); |
| } |
| |
| // Concatenate all vectors into a wide vector. |
| Value *WideVec = ConcatenateVectors(Builder, StoredVecs); |
| |
| // Interleave the elements in the wide vector. |
| Constant *IMask = getInterleavedMask(Builder, VF, InterleaveFactor); |
| Value *IVec = Builder.CreateShuffleVector(WideVec, UndefVec, IMask, |
| "interleaved.vec"); |
| |
| Instruction *NewStoreInstr = |
| Builder.CreateAlignedStore(IVec, NewPtrs[Part], Group->getAlignment()); |
| propagateMetadata(NewStoreInstr, Instr); |
| } |
| } |
| |
| void InnerLoopVectorizer::vectorizeMemoryInstruction(Instruction *Instr) { |
| // Attempt to issue a wide load. |
| LoadInst *LI = dyn_cast<LoadInst>(Instr); |
| StoreInst *SI = dyn_cast<StoreInst>(Instr); |
| |
| assert((LI || SI) && "Invalid Load/Store instruction"); |
| |
| // Try to vectorize the interleave group if this access is interleaved. |
| if (Legal->isAccessInterleaved(Instr)) |
| return vectorizeInterleaveGroup(Instr); |
| |
| Type *ScalarDataTy = LI ? LI->getType() : SI->getValueOperand()->getType(); |
| Type *DataTy = VectorType::get(ScalarDataTy, VF); |
| Value *Ptr = LI ? LI->getPointerOperand() : SI->getPointerOperand(); |
| unsigned Alignment = LI ? LI->getAlignment() : SI->getAlignment(); |
| // An alignment of 0 means target abi alignment. We need to use the scalar's |
| // target abi alignment in such a case. |
| const DataLayout &DL = Instr->getModule()->getDataLayout(); |
| if (!Alignment) |
| Alignment = DL.getABITypeAlignment(ScalarDataTy); |
| unsigned AddressSpace = Ptr->getType()->getPointerAddressSpace(); |
| unsigned ScalarAllocatedSize = DL.getTypeAllocSize(ScalarDataTy); |
| unsigned VectorElementSize = DL.getTypeStoreSize(DataTy) / VF; |
| |
| if (SI && Legal->blockNeedsPredication(SI->getParent()) && |
| !Legal->isMaskRequired(SI)) |
| return scalarizeInstruction(Instr, true); |
| |
| if (ScalarAllocatedSize != VectorElementSize) |
| return scalarizeInstruction(Instr); |
| |
| // If the pointer is loop invariant or if it is non-consecutive, |
| // scalarize the load. |
| int ConsecutiveStride = Legal->isConsecutivePtr(Ptr); |
| bool Reverse = ConsecutiveStride < 0; |
| bool UniformLoad = LI && Legal->isUniform(Ptr); |
| if (!ConsecutiveStride || UniformLoad) |
| return scalarizeInstruction(Instr); |
| |
| Constant *Zero = Builder.getInt32(0); |
| VectorParts &Entry = WidenMap.get(Instr); |
| |
| // Handle consecutive loads/stores. |
| GetElementPtrInst *Gep = dyn_cast<GetElementPtrInst>(Ptr); |
| if (Gep && Legal->isInductionVariable(Gep->getPointerOperand())) { |
| setDebugLocFromInst(Builder, Gep); |
| Value *PtrOperand = Gep->getPointerOperand(); |
| Value *FirstBasePtr = getVectorValue(PtrOperand)[0]; |
| FirstBasePtr = Builder.CreateExtractElement(FirstBasePtr, Zero); |
| |
| // Create the new GEP with the new induction variable. |
| GetElementPtrInst *Gep2 = cast<GetElementPtrInst>(Gep->clone()); |
| Gep2->setOperand(0, FirstBasePtr); |
| Gep2->setName("gep.indvar.base"); |
| Ptr = Builder.Insert(Gep2); |
| } else if (Gep) { |
| setDebugLocFromInst(Builder, Gep); |
| assert(SE->isLoopInvariant(SE->getSCEV(Gep->getPointerOperand()), |
| OrigLoop) && "Base ptr must be invariant"); |
| |
| // The last index does not have to be the induction. It can be |
| // consecutive and be a function of the index. For example A[I+1]; |
| unsigned NumOperands = Gep->getNumOperands(); |
| unsigned InductionOperand = getGEPInductionOperand(Gep); |
| // Create the new GEP with the new induction variable. |
| GetElementPtrInst *Gep2 = cast<GetElementPtrInst>(Gep->clone()); |
| |
| for (unsigned i = 0; i < NumOperands; ++i) { |
| Value *GepOperand = Gep->getOperand(i); |
| Instruction *GepOperandInst = dyn_cast<Instruction>(GepOperand); |
| |
| // Update last index or loop invariant instruction anchored in loop. |
| if (i == InductionOperand || |
| (GepOperandInst && OrigLoop->contains(GepOperandInst))) { |
| assert((i == InductionOperand || |
| SE->isLoopInvariant(SE->getSCEV(GepOperandInst), OrigLoop)) && |
| "Must be last index or loop invariant"); |
| |
| VectorParts &GEPParts = getVectorValue(GepOperand); |
| Value *Index = GEPParts[0]; |
| Index = Builder.CreateExtractElement(Index, Zero); |
| Gep2->setOperand(i, Index); |
| Gep2->setName("gep.indvar.idx"); |
| } |
| } |
| Ptr = Builder.Insert(Gep2); |
| } else { |
| // Use the induction element ptr. |
| assert(isa<PHINode>(Ptr) && "Invalid induction ptr"); |
| setDebugLocFromInst(Builder, Ptr); |
| VectorParts &PtrVal = getVectorValue(Ptr); |
| Ptr = Builder.CreateExtractElement(PtrVal[0], Zero); |
| } |
| |
| VectorParts Mask = createBlockInMask(Instr->getParent()); |
| // Handle Stores: |
| if (SI) { |
| assert(!Legal->isUniform(SI->getPointerOperand()) && |
| "We do not allow storing to uniform addresses"); |
| setDebugLocFromInst(Builder, SI); |
| // We don't want to update the value in the map as it might be used in |
| // another expression. So don't use a reference type for "StoredVal". |
| VectorParts StoredVal = getVectorValue(SI->getValueOperand()); |
| |
| for (unsigned Part = 0; Part < UF; ++Part) { |
| // Calculate the pointer for the specific unroll-part. |
| Value *PartPtr = |
| Builder.CreateGEP(nullptr, Ptr, Builder.getInt32(Part * VF)); |
| |
| if (Reverse) { |
| // If we store to reverse consecutive memory locations then we need |
| // to reverse the order of elements in the stored value. |
| StoredVal[Part] = reverseVector(StoredVal[Part]); |
| // If the address is consecutive but reversed, then the |
| // wide store needs to start at the last vector element. |
| PartPtr = Builder.CreateGEP(nullptr, Ptr, Builder.getInt32(-Part * VF)); |
| PartPtr = Builder.CreateGEP(nullptr, PartPtr, Builder.getInt32(1 - VF)); |
| Mask[Part] = reverseVector(Mask[Part]); |
| } |
| |
| Value *VecPtr = Builder.CreateBitCast(PartPtr, |
| DataTy->getPointerTo(AddressSpace)); |
| |
| Instruction *NewSI; |
| if (Legal->isMaskRequired(SI)) |
| NewSI = Builder.CreateMaskedStore(StoredVal[Part], VecPtr, Alignment, |
| Mask[Part]); |
| else |
| NewSI = Builder.CreateAlignedStore(StoredVal[Part], VecPtr, Alignment); |
| propagateMetadata(NewSI, SI); |
| } |
| return; |
| } |
| |
| // Handle loads. |
| assert(LI && "Must have a load instruction"); |
| setDebugLocFromInst(Builder, LI); |
| for (unsigned Part = 0; Part < UF; ++Part) { |
| // Calculate the pointer for the specific unroll-part. |
| Value *PartPtr = |
| Builder.CreateGEP(nullptr, Ptr, Builder.getInt32(Part * VF)); |
| |
| if (Reverse) { |
| // If the address is consecutive but reversed, then the |
| // wide load needs to start at the last vector element. |
| PartPtr = Builder.CreateGEP(nullptr, Ptr, Builder.getInt32(-Part * VF)); |
| PartPtr = Builder.CreateGEP(nullptr, PartPtr, Builder.getInt32(1 - VF)); |
| Mask[Part] = reverseVector(Mask[Part]); |
| } |
| |
| Instruction* NewLI; |
| Value *VecPtr = Builder.CreateBitCast(PartPtr, |
| DataTy->getPointerTo(AddressSpace)); |
| if (Legal->isMaskRequired(LI)) |
| NewLI = Builder.CreateMaskedLoad(VecPtr, Alignment, Mask[Part], |
| UndefValue::get(DataTy), |
| "wide.masked.load"); |
| else |
| NewLI = Builder.CreateAlignedLoad(VecPtr, Alignment, "wide.load"); |
| propagateMetadata(NewLI, LI); |
| Entry[Part] = Reverse ? reverseVector(NewLI) : NewLI; |
| } |
| } |
| |
| void InnerLoopVectorizer::scalarizeInstruction(Instruction *Instr, bool IfPredicateStore) { |
| assert(!Instr->getType()->isAggregateType() && "Can't handle vectors"); |
| // Holds vector parameters or scalars, in case of uniform vals. |
| SmallVector<VectorParts, 4> Params; |
| |
| setDebugLocFromInst(Builder, Instr); |
| |
| // Find all of the vectorized parameters. |
| for (unsigned op = 0, e = Instr->getNumOperands(); op != e; ++op) { |
| Value *SrcOp = Instr->getOperand(op); |
| |
| // If we are accessing the old induction variable, use the new one. |
| if (SrcOp == OldInduction) { |
| Params.push_back(getVectorValue(SrcOp)); |
| continue; |
| } |
| |
| // Try using previously calculated values. |
| Instruction *SrcInst = dyn_cast<Instruction>(SrcOp); |
| |
| // If the src is an instruction that appeared earlier in the basic block |
| // then it should already be vectorized. |
| if (SrcInst && OrigLoop->contains(SrcInst)) { |
| assert(WidenMap.has(SrcInst) && "Source operand is unavailable"); |
| // The parameter is a vector value from earlier. |
| Params.push_back(WidenMap.get(SrcInst)); |
| } else { |
| // The parameter is a scalar from outside the loop. Maybe even a constant. |
| VectorParts Scalars; |
| Scalars.append(UF, SrcOp); |
| Params.push_back(Scalars); |
| } |
| } |
| |
| assert(Params.size() == Instr->getNumOperands() && |
| "Invalid number of operands"); |
| |
| // Does this instruction return a value ? |
| bool IsVoidRetTy = Instr->getType()->isVoidTy(); |
| |
| Value *UndefVec = IsVoidRetTy ? nullptr : |
| UndefValue::get(VectorType::get(Instr->getType(), VF)); |
| // Create a new entry in the WidenMap and initialize it to Undef or Null. |
| VectorParts &VecResults = WidenMap.splat(Instr, UndefVec); |
| |
| Instruction *InsertPt = Builder.GetInsertPoint(); |
| BasicBlock *IfBlock = Builder.GetInsertBlock(); |
| BasicBlock *CondBlock = nullptr; |
| |
| VectorParts Cond; |
| Loop *VectorLp = nullptr; |
| if (IfPredicateStore) { |
| assert(Instr->getParent()->getSinglePredecessor() && |
| "Only support single predecessor blocks"); |
| Cond = createEdgeMask(Instr->getParent()->getSinglePredecessor(), |
| Instr->getParent()); |
| VectorLp = LI->getLoopFor(IfBlock); |
| assert(VectorLp && "Must have a loop for this block"); |
| } |
| |
| // For each vector unroll 'part': |
| for (unsigned Part = 0; Part < UF; ++Part) { |
| // For each scalar that we create: |
| for (unsigned Width = 0; Width < VF; ++Width) { |
| |
| // Start if-block. |
| Value *Cmp = nullptr; |
| if (IfPredicateStore) { |
| Cmp = Builder.CreateExtractElement(Cond[Part], Builder.getInt32(Width)); |
| Cmp = Builder.CreateICmp(ICmpInst::ICMP_EQ, Cmp, ConstantInt::get(Cmp->getType(), 1)); |
| CondBlock = IfBlock->splitBasicBlock(InsertPt, "cond.store"); |
| LoopVectorBody.push_back(CondBlock); |
| VectorLp->addBasicBlockToLoop(CondBlock, *LI); |
| // Update Builder with newly created basic block. |
| Builder.SetInsertPoint(InsertPt); |
| } |
| |
| Instruction *Cloned = Instr->clone(); |
| if (!IsVoidRetTy) |
| Cloned->setName(Instr->getName() + ".cloned"); |
| // Replace the operands of the cloned instructions with extracted scalars. |
| for (unsigned op = 0, e = Instr->getNumOperands(); op != e; ++op) { |
| Value *Op = Params[op][Part]; |
| // Param is a vector. Need to extract the right lane. |
| if (Op->getType()->isVectorTy()) |
| Op = Builder.CreateExtractElement(Op, Builder.getInt32(Width)); |
| Cloned->setOperand(op, Op); |
| } |
| |
| // Place the cloned scalar in the new loop. |
| Builder.Insert(Cloned); |
| |
| // If the original scalar returns a value we need to place it in a vector |
| // so that future users will be able to use it. |
| if (!IsVoidRetTy) |
| VecResults[Part] = Builder.CreateInsertElement(VecResults[Part], Cloned, |
| Builder.getInt32(Width)); |
| // End if-block. |
| if (IfPredicateStore) { |
| BasicBlock *NewIfBlock = CondBlock->splitBasicBlock(InsertPt, "else"); |
| LoopVectorBody.push_back(NewIfBlock); |
| VectorLp->addBasicBlockToLoop(NewIfBlock, *LI); |
| Builder.SetInsertPoint(InsertPt); |
| ReplaceInstWithInst(IfBlock->getTerminator(), |
| BranchInst::Create(CondBlock, NewIfBlock, Cmp)); |
| IfBlock = NewIfBlock; |
| } |
| } |
| } |
| } |
| |
| static Instruction *getFirstInst(Instruction *FirstInst, Value *V, |
| Instruction *Loc) { |
| if (FirstInst) |
| return FirstInst; |
| if (Instruction *I = dyn_cast<Instruction>(V)) |
| return I->getParent() == Loc->getParent() ? I : nullptr; |
| return nullptr; |
| } |
| |
| std::pair<Instruction *, Instruction *> |
| InnerLoopVectorizer::addStrideCheck(Instruction *Loc) { |
| Instruction *tnullptr = nullptr; |
| if (!Legal->mustCheckStrides()) |
| return std::pair<Instruction *, Instruction *>(tnullptr, tnullptr); |
| |
| IRBuilder<> ChkBuilder(Loc); |
| |
| // Emit checks. |
| Value *Check = nullptr; |
| Instruction *FirstInst = nullptr; |
| for (SmallPtrSet<Value *, 8>::iterator SI = Legal->strides_begin(), |
| SE = Legal->strides_end(); |
| SI != SE; ++SI) { |
| Value *Ptr = stripIntegerCast(*SI); |
| Value *C = ChkBuilder.CreateICmpNE(Ptr, ConstantInt::get(Ptr->getType(), 1), |
| "stride.chk"); |
| // Store the first instruction we create. |
| FirstInst = getFirstInst(FirstInst, C, Loc); |
| if (Check) |
| Check = ChkBuilder.CreateOr(Check, C); |
| else |
| Check = C; |
| } |
| |
| // We have to do this trickery because the IRBuilder might fold the check to a |
| // constant expression in which case there is no Instruction anchored in a |
| // the block. |
| LLVMContext &Ctx = Loc->getContext(); |
| Instruction *TheCheck = |
| BinaryOperator::CreateAnd(Check, ConstantInt::getTrue(Ctx)); |
| ChkBuilder.Insert(TheCheck, "stride.not.one"); |
| FirstInst = getFirstInst(FirstInst, TheCheck, Loc); |
| |
| return std::make_pair(FirstInst, TheCheck); |
| } |
| |
| void InnerLoopVectorizer::createEmptyLoop() { |
| /* |
| In this function we generate a new loop. The new loop will contain |
| the vectorized instructions while the old loop will continue to run the |
| scalar remainder. |
| |
| [ ] <-- Back-edge taken count overflow check. |
| / | |
| / v |
| | [ ] <-- vector loop bypass (may consist of multiple blocks). |
| | / | |
| | / v |
| || [ ] <-- vector pre header. |
| || | |
| || v |
| || [ ] \ |
| || [ ]_| <-- vector loop. |
| || | |
| | \ v |
| | >[ ] <--- middle-block. |
| | / | |
| | / v |
| -|- >[ ] <--- new preheader. |
| | | |
| | v |
| | [ ] \ |
| | [ ]_| <-- old scalar loop to handle remainder. |
| \ | |
| \ v |
| >[ ] <-- exit block. |
| ... |
| */ |
| |
| BasicBlock *OldBasicBlock = OrigLoop->getHeader(); |
| BasicBlock *VectorPH = OrigLoop->getLoopPreheader(); |
| BasicBlock *ExitBlock = OrigLoop->getExitBlock(); |
| assert(VectorPH && "Invalid loop structure"); |
| assert(ExitBlock && "Must have an exit block"); |
| |
| // Some loops have a single integer induction variable, while other loops |
| // don't. One example is c++ iterators that often have multiple pointer |
| // induction variables. In the code below we also support a case where we |
| // don't have a single induction variable. |
| OldInduction = Legal->getInduction(); |
| Type *IdxTy = Legal->getWidestInductionType(); |
| |
| // Find the loop boundaries. |
| const SCEV *ExitCount = SE->getBackedgeTakenCount(OrigLoop); |
| assert(ExitCount != SE->getCouldNotCompute() && "Invalid loop count"); |
| |
| // The exit count might have the type of i64 while the phi is i32. This can |
| // happen if we have an induction variable that is sign extended before the |
| // compare. The only way that we get a backedge taken count is that the |
| // induction variable was signed and as such will not overflow. In such a case |
| // truncation is legal. |
| if (ExitCount->getType()->getPrimitiveSizeInBits() > |
| IdxTy->getPrimitiveSizeInBits()) |
| ExitCount = SE->getTruncateOrNoop(ExitCount, IdxTy); |
| |
| const SCEV *BackedgeTakeCount = SE->getNoopOrZeroExtend(ExitCount, IdxTy); |
| // Get the total trip count from the count by adding 1. |
| ExitCount = SE->getAddExpr(BackedgeTakeCount, |
| SE->getConstant(BackedgeTakeCount->getType(), 1)); |
| |
| const DataLayout &DL = OldBasicBlock->getModule()->getDataLayout(); |
| |
| // Expand the trip count and place the new instructions in the preheader. |
| // Notice that the pre-header does not change, only the loop body. |
| SCEVExpander Exp(*SE, DL, "induction"); |
| |
| // We need to test whether the backedge-taken count is uint##_max. Adding one |
| // to it will cause overflow and an incorrect loop trip count in the vector |
| // body. In case of overflow we want to directly jump to the scalar remainder |
| // loop. |
| Value *BackedgeCount = |
| Exp.expandCodeFor(BackedgeTakeCount, BackedgeTakeCount->getType(), |
| VectorPH->getTerminator()); |
| if (BackedgeCount->getType()->isPointerTy()) |
| BackedgeCount = CastInst::CreatePointerCast(BackedgeCount, IdxTy, |
| "backedge.ptrcnt.to.int", |
| VectorPH->getTerminator()); |
| Instruction *CheckBCOverflow = |
| CmpInst::Create(Instruction::ICmp, CmpInst::ICMP_EQ, BackedgeCount, |
| Constant::getAllOnesValue(BackedgeCount->getType()), |
| "backedge.overflow", VectorPH->getTerminator()); |
| |
| // The loop index does not have to start at Zero. Find the original start |
| // value from the induction PHI node. If we don't have an induction variable |
| // then we know that it starts at zero. |
| Builder.SetInsertPoint(VectorPH->getTerminator()); |
| Value *StartIdx = ExtendedIdx = |
| OldInduction |
| ? Builder.CreateZExt(OldInduction->getIncomingValueForBlock(VectorPH), |
| IdxTy) |
| : ConstantInt::get(IdxTy, 0); |
| |
| // Count holds the overall loop count (N). |
| Value *Count = Exp.expandCodeFor(ExitCount, ExitCount->getType(), |
| VectorPH->getTerminator()); |
| |
| LoopBypassBlocks.push_back(VectorPH); |
| |
| // Split the single block loop into the two loop structure described above. |
| BasicBlock *VecBody = |
| VectorPH->splitBasicBlock(VectorPH->getTerminator(), "vector.body"); |
| BasicBlock *MiddleBlock = |
| VecBody->splitBasicBlock(VecBody->getTerminator(), "middle.block"); |
| BasicBlock *ScalarPH = |
| MiddleBlock->splitBasicBlock(MiddleBlock->getTerminator(), "scalar.ph"); |
| |
| // Create and register the new vector loop. |
| Loop* Lp = new Loop(); |
| Loop *ParentLoop = OrigLoop->getParentLoop(); |
| |
| // Insert the new loop into the loop nest and register the new basic blocks |
| // before calling any utilities such as SCEV that require valid LoopInfo. |
| if (ParentLoop) { |
| ParentLoop->addChildLoop(Lp); |
| ParentLoop->addBasicBlockToLoop(ScalarPH, *LI); |
| ParentLoop->addBasicBlockToLoop(MiddleBlock, *LI); |
| } else { |
| LI->addTopLevelLoop(Lp); |
| } |
| Lp->addBasicBlockToLoop(VecBody, *LI); |
| |
| // Use this IR builder to create the loop instructions (Phi, Br, Cmp) |
| // inside the loop. |
| Builder.SetInsertPoint(VecBody->getFirstNonPHI()); |
| |
| // Generate the induction variable. |
| setDebugLocFromInst(Builder, getDebugLocFromInstOrOperands(OldInduction)); |
| Induction = Builder.CreatePHI(IdxTy, 2, "index"); |
| // The loop step is equal to the vectorization factor (num of SIMD elements) |
| // times the unroll factor (num of SIMD instructions). |
| Constant *Step = ConstantInt::get(IdxTy, VF * UF); |
| |
| // Generate code to check that the loop's trip count that we computed by |
| // adding one to the backedge-taken count will not overflow. |
| BasicBlock *NewVectorPH = |
| VectorPH->splitBasicBlock(VectorPH->getTerminator(), "overflow.checked"); |
| if (ParentLoop) |
| ParentLoop->addBasicBlockToLoop(NewVectorPH, *LI); |
| ReplaceInstWithInst( |
| VectorPH->getTerminator(), |
| BranchInst::Create(ScalarPH, NewVectorPH, CheckBCOverflow)); |
| VectorPH = NewVectorPH; |
| |
| // This is the IR builder that we use to add all of the logic for bypassing |
| // the new vector loop. |
| IRBuilder<> BypassBuilder(VectorPH->getTerminator()); |
| setDebugLocFromInst(BypassBuilder, |
| getDebugLocFromInstOrOperands(OldInduction)); |
| |
| // We may need to extend the index in case there is a type mismatch. |
| // We know that the count starts at zero and does not overflow. |
| if (Count->getType() != IdxTy) { |
| // The exit count can be of pointer type. Convert it to the correct |
| // integer type. |
| if (ExitCount->getType()->isPointerTy()) |
| Count = BypassBuilder.CreatePointerCast(Count, IdxTy, "ptrcnt.to.int"); |
| else |
| Count = BypassBuilder.CreateZExtOrTrunc(Count, IdxTy, "cnt.cast"); |
| } |
| |
| // Add the start index to the loop count to get the new end index. |
| Value *IdxEnd = BypassBuilder.CreateAdd(Count, StartIdx, "end.idx"); |
| |
| // Now we need to generate the expression for N - (N % VF), which is |
| // the part that the vectorized body will execute. |
| Value *R = BypassBuilder.CreateURem(Count, Step, "n.mod.vf"); |
| Value *CountRoundDown = BypassBuilder.CreateSub(Count, R, "n.vec"); |
| Value *IdxEndRoundDown = BypassBuilder.CreateAdd(CountRoundDown, StartIdx, |
| "end.idx.rnd.down"); |
| |
| // Now, compare the new count to zero. If it is zero skip the vector loop and |
| // jump to the scalar loop. |
| Value *Cmp = |
| BypassBuilder.CreateICmpEQ(IdxEndRoundDown, StartIdx, "cmp.zero"); |
| NewVectorPH = |
| VectorPH->splitBasicBlock(VectorPH->getTerminator(), "vector.ph"); |
| if (ParentLoop) |
| ParentLoop->addBasicBlockToLoop(NewVectorPH, *LI); |
| LoopBypassBlocks.push_back(VectorPH); |
| ReplaceInstWithInst(VectorPH->getTerminator(), |
| BranchInst::Create(MiddleBlock, NewVectorPH, Cmp)); |
| VectorPH = NewVectorPH; |
| |
| // Generate the code to check that the strides we assumed to be one are really |
| // one. We want the new basic block to start at the first instruction in a |
| // sequence of instructions that form a check. |
| Instruction *StrideCheck; |
| Instruction *FirstCheckInst; |
| std::tie(FirstCheckInst, StrideCheck) = |
| addStrideCheck(VectorPH->getTerminator()); |
| if (StrideCheck) { |
| AddedSafetyChecks = true; |
| // Create a new block containing the stride check. |
| VectorPH->setName("vector.stridecheck"); |
| NewVectorPH = |
| VectorPH->splitBasicBlock(VectorPH->getTerminator(), "vector.ph"); |
| if (ParentLoop) |
| ParentLoop->addBasicBlockToLoop(NewVectorPH, *LI); |
| LoopBypassBlocks.push_back(VectorPH); |
| |
| // Replace the branch into the memory check block with a conditional branch |
| // for the "few elements case". |
| ReplaceInstWithInst( |
| VectorPH->getTerminator(), |
| BranchInst::Create(MiddleBlock, NewVectorPH, StrideCheck)); |
| |
| VectorPH = NewVectorPH; |
| } |
| |
| // Generate the code that checks in runtime if arrays overlap. We put the |
| // checks into a separate block to make the more common case of few elements |
| // faster. |
| Instruction *MemRuntimeCheck; |
| std::tie(FirstCheckInst, MemRuntimeCheck) = |
| Legal->getLAI()->addRuntimeCheck(VectorPH->getTerminator()); |
| if (MemRuntimeCheck) { |
| AddedSafetyChecks = true; |
| // Create a new block containing the memory check. |
| VectorPH->setName("vector.memcheck"); |
| NewVectorPH = |
| VectorPH->splitBasicBlock(VectorPH->getTerminator(), "vector.ph"); |
| if (ParentLoop) |
| ParentLoop->addBasicBlockToLoop(NewVectorPH, *LI); |
| LoopBypassBlocks.push_back(VectorPH); |
| |
| // Replace the branch into the memory check block with a conditional branch |
| // for the "few elements case". |
| ReplaceInstWithInst( |
| VectorPH->getTerminator(), |
| BranchInst::Create(MiddleBlock, NewVectorPH, MemRuntimeCheck)); |
| |
| VectorPH = NewVectorPH; |
| } |
| |
| // We are going to resume the execution of the scalar loop. |
| // Go over all of the induction variables that we found and fix the |
| // PHIs that are left in the scalar version of the loop. |
| // The starting values of PHI nodes depend on the counter of the last |
| // iteration in the vectorized loop. |
| // If we come from a bypass edge then we need to start from the original |
| // start value. |
| |
| // This variable saves the new starting index for the scalar loop. |
| PHINode *ResumeIndex = nullptr; |
| LoopVectorizationLegality::InductionList::iterator I, E; |
| LoopVectorizationLegality::InductionList *List = Legal->getInductionVars(); |
| // Set builder to point to last bypass block. |
| BypassBuilder.SetInsertPoint(LoopBypassBlocks.back()->getTerminator()); |
| for (I = List->begin(), E = List->end(); I != E; ++I) { |
| PHINode *OrigPhi = I->first; |
| LoopVectorizationLegality::InductionInfo II = I->second; |
| |
| Type *ResumeValTy = (OrigPhi == OldInduction) ? IdxTy : OrigPhi->getType(); |
| PHINode *ResumeVal = PHINode::Create(ResumeValTy, 2, "resume.val", |
| MiddleBlock->getTerminator()); |
| // We might have extended the type of the induction variable but we need a |
| // truncated version for the scalar loop. |
| PHINode *TruncResumeVal = (OrigPhi == OldInduction) ? |
| PHINode::Create(OrigPhi->getType(), 2, "trunc.resume.val", |
| MiddleBlock->getTerminator()) : nullptr; |
| |
| // Create phi nodes to merge from the backedge-taken check block. |
| PHINode *BCResumeVal = PHINode::Create(ResumeValTy, 3, "bc.resume.val", |
| ScalarPH->getTerminator()); |
| BCResumeVal->addIncoming(ResumeVal, MiddleBlock); |
| |
| PHINode *BCTruncResumeVal = nullptr; |
| if (OrigPhi == OldInduction) { |
| BCTruncResumeVal = |
| PHINode::Create(OrigPhi->getType(), 2, "bc.trunc.resume.val", |
| ScalarPH->getTerminator()); |
| BCTruncResumeVal->addIncoming(TruncResumeVal, MiddleBlock); |
| } |
| |
| Value *EndValue = nullptr; |
| switch (II.IK) { |
| case LoopVectorizationLegality::IK_NoInduction: |
| llvm_unreachable("Unknown induction"); |
| case LoopVectorizationLegality::IK_IntInduction: { |
| // Handle the integer induction counter. |
| assert(OrigPhi->getType()->isIntegerTy() && "Invalid type"); |
| |
| // We have the canonical induction variable. |
| if (OrigPhi == OldInduction) { |
| // Create a truncated version of the resume value for the scalar loop, |
| // we might have promoted the type to a larger width. |
| EndValue = |
| BypassBuilder.CreateTrunc(IdxEndRoundDown, OrigPhi->getType()); |
| // The new PHI merges the original incoming value, in case of a bypass, |
| // or the value at the end of the vectorized loop. |
| for (unsigned I = 1, E = LoopBypassBlocks.size(); I != E; ++I) |
| TruncResumeVal->addIncoming(II.StartValue, LoopBypassBlocks[I]); |
| TruncResumeVal->addIncoming(EndValue, VecBody); |
| |
| BCTruncResumeVal->addIncoming(II.StartValue, LoopBypassBlocks[0]); |
| |
| // We know what the end value is. |
| EndValue = IdxEndRoundDown; |
| // We also know which PHI node holds it. |
| ResumeIndex = ResumeVal; |
| break; |
| } |
| |
| // Not the canonical induction variable - add the vector loop count to the |
| // start value. |
| Value *CRD = BypassBuilder.CreateSExtOrTrunc(CountRoundDown, |
| II.StartValue->getType(), |
| "cast.crd"); |
| EndValue = II.transform(BypassBuilder, CRD); |
| EndValue->setName("ind.end"); |
| break; |
| } |
| case LoopVectorizationLegality::IK_PtrInduction: { |
| Value *CRD = BypassBuilder.CreateSExtOrTrunc(CountRoundDown, |
| II.StepValue->getType(), |
| "cast.crd"); |
| EndValue = II.transform(BypassBuilder, CRD); |
| EndValue->setName("ptr.ind.end"); |
| break; |
| } |
| }// end of case |
| |
| // The new PHI merges the original incoming value, in case of a bypass, |
| // or the value at the end of the vectorized loop. |
| for (unsigned I = 1, E = LoopBypassBlocks.size(); I != E; ++I) { |
| if (OrigPhi == OldInduction) |
| ResumeVal->addIncoming(StartIdx, LoopBypassBlocks[I]); |
| else |
| ResumeVal->addIncoming(II.StartValue, LoopBypassBlocks[I]); |
| } |
| ResumeVal->addIncoming(EndValue, VecBody); |
| |
| // Fix the scalar body counter (PHI node). |
| unsigned BlockIdx = OrigPhi->getBasicBlockIndex(ScalarPH); |
| |
| // The old induction's phi node in the scalar body needs the truncated |
| // value. |
| if (OrigPhi == OldInduction) { |
| BCResumeVal->addIncoming(StartIdx, LoopBypassBlocks[0]); |
| OrigPhi->setIncomingValue(BlockIdx, BCTruncResumeVal); |
| } else { |
| BCResumeVal->addIncoming(II.StartValue, LoopBypassBlocks[0]); |
| OrigPhi->setIncomingValue(BlockIdx, BCResumeVal); |
| } |
| } |
| |
| // If we are generating a new induction variable then we also need to |
| // generate the code that calculates the exit value. This value is not |
| // simply the end of the counter because we may skip the vectorized body |
| // in case of a runtime check. |
| if (!OldInduction){ |
| assert(!ResumeIndex && "Unexpected resume value found"); |
| ResumeIndex = PHINode::Create(IdxTy, 2, "new.indc.resume.val", |
| MiddleBlock->getTerminator()); |
| for (unsigned I = 1, E = LoopBypassBlocks.size(); I != E; ++I) |
| ResumeIndex->addIncoming(StartIdx, LoopBypassBlocks[I]); |
| ResumeIndex->addIncoming(IdxEndRoundDown, VecBody); |
| } |
| |
| // Make sure that we found the index where scalar loop needs to continue. |
| assert(ResumeIndex && ResumeIndex->getType()->isIntegerTy() && |
| "Invalid resume Index"); |
| |
| // Add a check in the middle block to see if we have completed |
| // all of the iterations in the first vector loop. |
| // If (N - N%VF) == N, then we *don't* need to run the remainder. |
| Value *CmpN = CmpInst::Create(Instruction::ICmp, CmpInst::ICMP_EQ, IdxEnd, |
| ResumeIndex, "cmp.n", |
| MiddleBlock->getTerminator()); |
| ReplaceInstWithInst(MiddleBlock->getTerminator(), |
| BranchInst::Create(ExitBlock, ScalarPH, CmpN)); |
| |
| // Create i+1 and fill the PHINode. |
| Value *NextIdx = Builder.CreateAdd(Induction, Step, "index.next"); |
| Induction->addIncoming(StartIdx, VectorPH); |
| Induction->addIncoming(NextIdx, VecBody); |
| // Create the compare. |
| Value *ICmp = Builder.CreateICmpEQ(NextIdx, IdxEndRoundDown); |
| Builder.CreateCondBr(ICmp, MiddleBlock, VecBody); |
| |
| // Now we have two terminators. Remove the old one from the block. |
| VecBody->getTerminator()->eraseFromParent(); |
| |
| // Get ready to start creating new instructions into the vectorized body. |
| Builder.SetInsertPoint(VecBody->getFirstInsertionPt()); |
| |
| // Save the state. |
| LoopVectorPreHeader = VectorPH; |
| LoopScalarPreHeader = ScalarPH; |
| LoopMiddleBlock = MiddleBlock; |
| LoopExitBlock = ExitBlock; |
| LoopVectorBody.push_back(VecBody); |
| LoopScalarBody = OldBasicBlock; |
| |
| LoopVectorizeHints Hints(Lp, true); |
| Hints.setAlreadyVectorized(); |
| } |
| |
| namespace { |
| struct CSEDenseMapInfo { |
| static bool canHandle(Instruction *I) { |
| return isa<InsertElementInst>(I) || isa<ExtractElementInst>(I) || |
| isa<ShuffleVectorInst>(I) || isa<GetElementPtrInst>(I); |
| } |
| static inline Instruction *getEmptyKey() { |
| return DenseMapInfo<Instruction *>::getEmptyKey(); |
| } |
| static inline Instruction *getTombstoneKey() { |
| return DenseMapInfo<Instruction *>::getTombstoneKey(); |
| } |
| static unsigned getHashValue(Instruction *I) { |
| assert(canHandle(I) && "Unknown instruction!"); |
| return hash_combine(I->getOpcode(), hash_combine_range(I->value_op_begin(), |
| I->value_op_end())); |
| } |
| static bool isEqual(Instruction *LHS, Instruction *RHS) { |
| if (LHS == getEmptyKey() || RHS == getEmptyKey() || |
| LHS == getTombstoneKey() || RHS == getTombstoneKey()) |
| return LHS == RHS; |
| return LHS->isIdenticalTo(RHS); |
| } |
| }; |
| } |
| |
| /// \brief Check whether this block is a predicated block. |
| /// Due to if predication of stores we might create a sequence of "if(pred) a[i] |
| /// = ...; " blocks. We start with one vectorized basic block. For every |
| /// conditional block we split this vectorized block. Therefore, every second |
| /// block will be a predicated one. |
| static bool isPredicatedBlock(unsigned BlockNum) { |
| return BlockNum % 2; |
| } |
| |
| ///\brief Perform cse of induction variable instructions. |
| static void cse(SmallVector<BasicBlock *, 4> &BBs) { |
| // Perform simple cse. |
| SmallDenseMap<Instruction *, Instruction *, 4, CSEDenseMapInfo> CSEMap; |
| for (unsigned i = 0, e = BBs.size(); i != e; ++i) { |
| BasicBlock *BB = BBs[i]; |
| for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;) { |
| Instruction *In = I++; |
| |
| if (!CSEDenseMapInfo::canHandle(In)) |
| continue; |
| |
| // Check if we can replace this instruction with any of the |
| // visited instructions. |
| if (Instruction *V = CSEMap.lookup(In)) { |
| In->replaceAllUsesWith(V); |
| In->eraseFromParent(); |
| continue; |
| } |
| // Ignore instructions in conditional blocks. We create "if (pred) a[i] = |
| // ...;" blocks for predicated stores. Every second block is a predicated |
| // block. |
| if (isPredicatedBlock(i)) |
| continue; |
| |
| CSEMap[In] = In; |
| } |
| } |
| } |
| |
| /// \brief Adds a 'fast' flag to floating point operations. |
| static Value *addFastMathFlag(Value *V) { |
| if (isa<FPMathOperator>(V)){ |
| FastMathFlags Flags; |
| Flags.setUnsafeAlgebra(); |
| cast<Instruction>(V)->setFastMathFlags(Flags); |
| } |
| return V; |
| } |
| |
| /// Estimate the overhead of scalarizing a value. Insert and Extract are set if |
| /// the result needs to be inserted and/or extracted from vectors. |
| static unsigned getScalarizationOverhead(Type *Ty, bool Insert, bool Extract, |
| const TargetTransformInfo &TTI) { |
| if (Ty->isVoidTy()) |
| return 0; |
| |
| assert(Ty->isVectorTy() && "Can only scalarize vectors"); |
| unsigned Cost = 0; |
| |
| for (int i = 0, e = Ty->getVectorNumElements(); i < e; ++i) { |
| if (Insert) |
| Cost += TTI.getVectorInstrCost(Instruction::InsertElement, Ty, i); |
| if (Extract) |
| Cost += TTI.getVectorInstrCost(Instruction::ExtractElement, Ty, i); |
| } |
| |
| return Cost; |
| } |
| |
| // Estimate cost of a call instruction CI if it were vectorized with factor VF. |
| // Return the cost of the instruction, including scalarization overhead if it's |
| // needed. The flag NeedToScalarize shows if the call needs to be scalarized - |
| // i.e. either vector version isn't available, or is too expensive. |
| static unsigned getVectorCallCost(CallInst *CI, unsigned VF, |
| const TargetTransformInfo &TTI, |
| const TargetLibraryInfo *TLI, |
| bool &NeedToScalarize) { |
| Function *F = CI->getCalledFunction(); |
| StringRef FnName = CI->getCalledFunction()->getName(); |
| Type *ScalarRetTy = CI->getType(); |
| SmallVector<Type *, 4> Tys, ScalarTys; |
| for (auto &ArgOp : CI->arg_operands()) |
| ScalarTys.push_back(ArgOp->getType()); |
| |
| // Estimate cost of scalarized vector call. The source operands are assumed |
| // to be vectors, so we need to extract individual elements from there, |
| // execute VF scalar calls, and then gather the result into the vector return |
| // value. |
| unsigned ScalarCallCost = TTI.getCallInstrCost(F, ScalarRetTy, ScalarTys); |
| if (VF == 1) |
| return ScalarCallCost; |
| |
| // Compute corresponding vector type for return value and arguments. |
| Type *RetTy = ToVectorTy(ScalarRetTy, VF); |
| for (unsigned i = 0, ie = ScalarTys.size(); i != ie; ++i) |
| Tys.push_back(ToVectorTy(ScalarTys[i], VF)); |
| |
| // Compute costs of unpacking argument values for the scalar calls and |
| // packing the return values to a vector. |
| unsigned ScalarizationCost = |
| getScalarizationOverhead(RetTy, true, false, TTI); |
| for (unsigned i = 0, ie = Tys.size(); i != ie; ++i) |
| ScalarizationCost += getScalarizationOverhead(Tys[i], false, true, TTI); |
| |
| unsigned Cost = ScalarCallCost * VF + ScalarizationCost; |
| |
| // If we can't emit a vector call for this function, then the currently found |
| // cost is the cost we need to return. |
| NeedToScalarize = true; |
| if (!TLI || !TLI->isFunctionVectorizable(FnName, VF) || CI->isNoBuiltin()) |
| return Cost; |
| |
| // If the corresponding vector cost is cheaper, return its cost. |
| unsigned VectorCallCost = TTI.getCallInstrCost(nullptr, RetTy, Tys); |
| if (VectorCallCost < Cost) { |
| NeedToScalarize = false; |
| return VectorCallCost; |
| } |
| return Cost; |
| } |
| |
| // Estimate cost of an intrinsic call instruction CI if it were vectorized with |
| // factor VF. Return the cost of the instruction, including scalarization |
| // overhead if it's needed. |
| static unsigned getVectorIntrinsicCost(CallInst *CI, unsigned VF, |
| const TargetTransformInfo &TTI, |
| const TargetLibraryInfo *TLI) { |
| Intrinsic::ID ID = getIntrinsicIDForCall(CI, TLI); |
| assert(ID && "Expected intrinsic call!"); |
| |
| Type *RetTy = ToVectorTy(CI->getType(), VF); |
| SmallVector<Type *, 4> Tys; |
| for (unsigned i = 0, ie = CI->getNumArgOperands(); i != ie; ++i) |
| Tys.push_back(ToVectorTy(CI->getArgOperand(i)->getType(), VF)); |
| |
| return TTI.getIntrinsicInstrCost(ID, RetTy, Tys); |
| } |
| |
| void InnerLoopVectorizer::vectorizeLoop() { |
| //===------------------------------------------------===// |
| // |
| // Notice: any optimization or new instruction that go |
| // into the code below should be also be implemented in |
| // the cost-model. |
| // |
| //===------------------------------------------------===// |
| Constant *Zero = Builder.getInt32(0); |
| |
| // In order to support reduction variables we need to be able to vectorize |
| // Phi nodes. Phi nodes have cycles, so we need to vectorize them in two |
| // stages. First, we create a new vector PHI node with no incoming edges. |
| // We use this value when we vectorize all of the instructions that use the |
| // PHI. Next, after all of the instructions in the block are complete we |
| // add the new incoming edges to the PHI. At this point all of the |
| // instructions in the basic block are vectorized, so we can use them to |
| // construct the PHI. |
| PhiVector RdxPHIsToFix; |
| |
| // Scan the loop in a topological order to ensure that defs are vectorized |
| // before users. |
| LoopBlocksDFS DFS(OrigLoop); |
| DFS.perform(LI); |
| |
| // Vectorize all of the blocks in the original loop. |
| for (LoopBlocksDFS::RPOIterator bb = DFS.beginRPO(), |
| be = DFS.endRPO(); bb != be; ++bb) |
| vectorizeBlockInLoop(*bb, &RdxPHIsToFix); |
| |
| // At this point every instruction in the original loop is widened to |
| // a vector form. We are almost done. Now, we need to fix the PHI nodes |
| // that we vectorized. The PHI nodes are currently empty because we did |
| // not want to introduce cycles. Notice that the remaining PHI nodes |
| // that we need to fix are reduction variables. |
| |
| // Create the 'reduced' values for each of the induction vars. |
| // The reduced values are the vector values that we scalarize and combine |
| // after the loop is finished. |
| for (PhiVector::iterator it = RdxPHIsToFix.begin(), e = RdxPHIsToFix.end(); |
| it != e; ++it) { |
| PHINode *RdxPhi = *it; |
| assert(RdxPhi && "Unable to recover vectorized PHI"); |
| |
| // Find the reduction variable descriptor. |
| assert(Legal->getReductionVars()->count(RdxPhi) && |
| "Unable to find the reduction variable"); |
| RecurrenceDescriptor RdxDesc = (*Legal->getReductionVars())[RdxPhi]; |
| |
| RecurrenceDescriptor::RecurrenceKind RK = RdxDesc.getRecurrenceKind(); |
| TrackingVH<Value> ReductionStartValue = RdxDesc.getRecurrenceStartValue(); |
| Instruction *LoopExitInst = RdxDesc.getLoopExitInstr(); |
| RecurrenceDescriptor::MinMaxRecurrenceKind MinMaxKind = |
| RdxDesc.getMinMaxRecurrenceKind(); |
| setDebugLocFromInst(Builder, ReductionStartValue); |
| |
| // We need to generate a reduction vector from the incoming scalar. |
| // To do so, we need to generate the 'identity' vector and override |
| // one of the elements with the incoming scalar reduction. We need |
| // to do it in the vector-loop preheader. |
| Builder.SetInsertPoint(LoopBypassBlocks[1]->getTerminator()); |
| |
| // This is the vector-clone of the value that leaves the loop. |
| VectorParts &VectorExit = getVectorValue(LoopExitInst); |
| Type *VecTy = VectorExit[0]->getType(); |
| |
| // Find the reduction identity variable. Zero for addition, or, xor, |
| // one for multiplication, -1 for And. |
| Value *Identity; |
| Value *VectorStart; |
| if (RK == RecurrenceDescriptor::RK_IntegerMinMax || |
| RK == RecurrenceDescriptor::RK_FloatMinMax) { |
| // MinMax reduction have the start value as their identify. |
| if (VF == 1) { |
| VectorStart = Identity = ReductionStartValue; |
| } else { |
| VectorStart = Identity = |
| Builder.CreateVectorSplat(VF, ReductionStartValue, "minmax.ident"); |
| } |
| } else { |
| // Handle other reduction kinds: |
| Constant *Iden = RecurrenceDescriptor::getRecurrenceIdentity( |
| RK, VecTy->getScalarType()); |
| if (VF == 1) { |
| Identity = Iden; |
| // This vector is the Identity vector where the first element is the |
| // incoming scalar reduction. |
| VectorStart = ReductionStartValue; |
| } else { |
| Identity = ConstantVector::getSplat(VF, Iden); |
| |
| // This vector is the Identity vector where the first element is the |
| // incoming scalar reduction. |
| VectorStart = |
| Builder.CreateInsertElement(Identity, ReductionStartValue, Zero); |
| } |
| } |
| |
| // Fix the vector-loop phi. |
| |
| // Reductions do not have to start at zero. They can start with |
| // any loop invariant values. |
| VectorParts &VecRdxPhi = WidenMap.get(RdxPhi); |
| BasicBlock *Latch = OrigLoop->getLoopLatch(); |
| Value *LoopVal = RdxPhi->getIncomingValueForBlock(Latch); |
| VectorParts &Val = getVectorValue(LoopVal); |
| for (unsigned part = 0; part < UF; ++part) { |
| // Make sure to add the reduction stat value only to the |
| // first unroll part. |
| Value *StartVal = (part == 0) ? VectorStart : Identity; |
| cast<PHINode>(VecRdxPhi[part])->addIncoming(StartVal, |
| LoopVectorPreHeader); |
| cast<PHINode>(VecRdxPhi[part])->addIncoming(Val[part], |
| LoopVectorBody.back()); |
| } |
| |
| // Before each round, move the insertion point right between |
| // the PHIs and the values we are going to write. |
| // This allows us to write both PHINodes and the extractelement |
| // instructions. |
| Builder.SetInsertPoint(LoopMiddleBlock->getFirstInsertionPt()); |
| |
| VectorParts RdxParts; |
| setDebugLocFromInst(Builder, LoopExitInst); |
| for (unsigned part = 0; part < UF; ++part) { |
| // This PHINode contains the vectorized reduction variable, or |
| // the initial value vector, if we bypass the vector loop. |
| VectorParts &RdxExitVal = getVectorValue(LoopExitInst); |
| PHINode *NewPhi = Builder.CreatePHI(VecTy, 2, "rdx.vec.exit.phi"); |
| Value *StartVal = (part == 0) ? VectorStart : Identity; |
| for (unsigned I = 1, E = LoopBypassBlocks.size(); I != E; ++I) |
| NewPhi->addIncoming(StartVal, LoopBypassBlocks[I]); |
| NewPhi->addIncoming(RdxExitVal[part], |
| LoopVectorBody.back()); |
| RdxParts.push_back(NewPhi); |
| } |
| |
| // Reduce all of the unrolled parts into a single vector. |
| Value *ReducedPartRdx = RdxParts[0]; |
| unsigned Op = RecurrenceDescriptor::getRecurrenceBinOp(RK); |
| setDebugLocFromInst(Builder, ReducedPartRdx); |
| for (unsigned part = 1; part < UF; ++part) { |
| if (Op != Instruction::ICmp && Op != Instruction::FCmp) |
| // Floating point operations had to be 'fast' to enable the reduction. |
| ReducedPartRdx = addFastMathFlag( |
| Builder.CreateBinOp((Instruction::BinaryOps)Op, RdxParts[part], |
| ReducedPartRdx, "bin.rdx")); |
| else |
| ReducedPartRdx = RecurrenceDescriptor::createMinMaxOp( |
| Builder, MinMaxKind, ReducedPartRdx, RdxParts[part]); |
| } |
| |
| if (VF > 1) { |
| // VF is a power of 2 so we can emit the reduction using log2(VF) shuffles |
| // and vector ops, reducing the set of values being computed by half each |
| // round. |
| assert(isPowerOf2_32(VF) && |
| "Reduction emission only supported for pow2 vectors!"); |
| Value *TmpVec = ReducedPartRdx; |
| SmallVector<Constant*, 32> ShuffleMask(VF, nullptr); |
| for (unsigned i = VF; i != 1; i >>= 1) { |
| // Move the upper half of the vector to the lower half. |
| for (unsigned j = 0; j != i/2; ++j) |
| ShuffleMask[j] = Builder.getInt32(i/2 + j); |
| |
| // Fill the rest of the mask with undef. |
| std::fill(&ShuffleMask[i/2], ShuffleMask.end(), |
| UndefValue::get(Builder.getInt32Ty())); |
| |
| Value *Shuf = |
| Builder.CreateShuffleVector(TmpVec, |
| UndefValue::get(TmpVec->getType()), |
| ConstantVector::get(ShuffleMask), |
| "rdx.shuf"); |
| |
| if (Op != Instruction::ICmp && Op != Instruction::FCmp) |
| // Floating point operations had to be 'fast' to enable the reduction. |
| TmpVec = addFastMathFlag(Builder.CreateBinOp( |
| (Instruction::BinaryOps)Op, TmpVec, Shuf, "bin.rdx")); |
| else |
| TmpVec = RecurrenceDescriptor::createMinMaxOp(Builder, MinMaxKind, |
| TmpVec, Shuf); |
| } |
| |
| // The result is in the first element of the vector. |
| ReducedPartRdx = Builder.CreateExtractElement(TmpVec, |
| Builder.getInt32(0)); |
| } |
| |
| // Create a phi node that merges control-flow from the backedge-taken check |
| // block and the middle block. |
| PHINode *BCBlockPhi = PHINode::Create(RdxPhi->getType(), 2, "bc.merge.rdx", |
| LoopScalarPreHeader->getTerminator()); |
| BCBlockPhi->addIncoming(ReductionStartValue, LoopBypassBlocks[0]); |
| BCBlockPhi->addIncoming(ReducedPartRdx, LoopMiddleBlock); |
| |
| // Now, we need to fix the users of the reduction variable |
| // inside and outside of the scalar remainder loop. |
| // We know that the loop is in LCSSA form. We need to update the |
| // PHI nodes in the exit blocks. |
| for (BasicBlock::iterator LEI = LoopExitBlock->begin(), |
| LEE = LoopExitBlock->end(); LEI != LEE; ++LEI) { |
| PHINode *LCSSAPhi = dyn_cast<PHINode>(LEI); |
| if (!LCSSAPhi) break; |
| |
| // All PHINodes need to have a single entry edge, or two if |
| // we already fixed them. |
| assert(LCSSAPhi->getNumIncomingValues() < 3 && "Invalid LCSSA PHI"); |
| |
| // We found our reduction value exit-PHI. Update it with the |
| // incoming bypass edge. |
| if (LCSSAPhi->getIncomingValue(0) == LoopExitInst) { |
| // Add an edge coming from the bypass. |
| LCSSAPhi->addIncoming(ReducedPartRdx, LoopMiddleBlock); |
| break; |
| } |
| }// end of the LCSSA phi scan. |
| |
| // Fix the scalar loop reduction variable with the incoming reduction sum |
| // from the vector body and from the backedge value. |
| int IncomingEdgeBlockIdx = |
| (RdxPhi)->getBasicBlockIndex(OrigLoop->getLoopLatch()); |
| assert(IncomingEdgeBlockIdx >= 0 && "Invalid block index"); |
| // Pick the other block. |
| int SelfEdgeBlockIdx = (IncomingEdgeBlockIdx ? 0 : 1); |
| (RdxPhi)->setIncomingValue(SelfEdgeBlockIdx, BCBlockPhi); |
| (RdxPhi)->setIncomingValue(IncomingEdgeBlockIdx, LoopExitInst); |
| }// end of for each redux variable. |
| |
| fixLCSSAPHIs(); |
| |
| // Remove redundant induction instructions. |
| cse(LoopVectorBody); |
| } |
| |
| void InnerLoopVectorizer::fixLCSSAPHIs() { |
| for (BasicBlock::iterator LEI = LoopExitBlock->begin(), |
| LEE = LoopExitBlock->end(); LEI != LEE; ++LEI) { |
| PHINode *LCSSAPhi = dyn_cast<PHINode>(LEI); |
| if (!LCSSAPhi) break; |
| if (LCSSAPhi->getNumIncomingValues() == 1) |
| LCSSAPhi->addIncoming(UndefValue::get(LCSSAPhi->getType()), |
| LoopMiddleBlock); |
| } |
| } |
| |
| InnerLoopVectorizer::VectorParts |
| InnerLoopVectorizer::createEdgeMask(BasicBlock *Src, BasicBlock *Dst) { |
| assert(std::find(pred_begin(Dst), pred_end(Dst), Src) != pred_end(Dst) && |
| "Invalid edge"); |
| |
| // Look for cached value. |
| std::pair<BasicBlock*, BasicBlock*> Edge(Src, Dst); |
| EdgeMaskCache::iterator ECEntryIt = MaskCache.find(Edge); |
| if (ECEntryIt != MaskCache.end()) |
| return ECEntryIt->second; |
| |
| VectorParts SrcMask = createBlockInMask(Src); |
| |
| // The terminator has to be a branch inst! |
| BranchInst *BI = dyn_cast<BranchInst>(Src->getTerminator()); |
| assert(BI && "Unexpected terminator found"); |
| |
| if (BI->isConditional()) { |
| VectorParts EdgeMask = getVectorValue(BI->getCondition()); |
| |
| if (BI->getSuccessor(0) != Dst) |
| for (unsigned part = 0; part < UF; ++part) |
| EdgeMask[part] = Builder.CreateNot(EdgeMask[part]); |
| |
| for (unsigned part = 0; part < UF; ++part) |
| EdgeMask[part] = Builder.CreateAnd(EdgeMask[part], SrcMask[part]); |
| |
| MaskCache[Edge] = EdgeMask; |
| return EdgeMask; |
| } |
| |
| MaskCache[Edge] = SrcMask; |
| return SrcMask; |
| } |
| |
| InnerLoopVectorizer::VectorParts |
| InnerLoopVectorizer::createBlockInMask(BasicBlock *BB) { |
| assert(OrigLoop->contains(BB) && "Block is not a part of a loop"); |
| |
| // Loop incoming mask is all-one. |
| if (OrigLoop->getHeader() == BB) { |
| Value *C = ConstantInt::get(IntegerType::getInt1Ty(BB->getContext()), 1); |
| return getVectorValue(C); |
| } |
| |
| // This is the block mask. We OR all incoming edges, and with zero. |
| Value *Zero = ConstantInt::get(IntegerType::getInt1Ty(BB->getContext()), 0); |
| VectorParts BlockMask = getVectorValue(Zero); |
| |
| // For each pred: |
| for (pred_iterator it = pred_begin(BB), e = pred_end(BB); it != e; ++it) { |
| VectorParts EM = createEdgeMask(*it, BB); |
| for (unsigned part = 0; part < UF; ++part) |
| BlockMask[part] = Builder.CreateOr(BlockMask[part], EM[part]); |
| } |
| |
| return BlockMask; |
| } |
| |
| void InnerLoopVectorizer::widenPHIInstruction(Instruction *PN, |
| InnerLoopVectorizer::VectorParts &Entry, |
| unsigned UF, unsigned VF, PhiVector *PV) { |
| PHINode* P = cast<PHINode>(PN); |
| // Handle reduction variables: |
| if (Legal->getReductionVars()->count(P)) { |
| for (unsigned part = 0; part < UF; ++part) { |
| // This is phase one of vectorizing PHIs. |
| Type *VecTy = (VF == 1) ? PN->getType() : |
| VectorType::get(PN->getType(), VF); |
| Entry[part] = PHINode::Create(VecTy, 2, "vec.phi", |
| LoopVectorBody.back()-> getFirstInsertionPt()); |
| } |
| PV->push_back(P); |
| return; |
| } |
| |
| setDebugLocFromInst(Builder, P); |
| // Check for PHI nodes that are lowered to vector selects. |
| if (P->getParent() != OrigLoop->getHeader()) { |
| // We know that all PHIs in non-header blocks are converted into |
| // selects, so we don't have to worry about the insertion order and we |
| // can just use the builder. |
| // At this point we generate the predication tree. There may be |
| // duplications since this is a simple recursive scan, but future |
| // optimizations will clean it up. |
| |
| unsigned NumIncoming = P->getNumIncomingValues(); |
| |
| // Generate a sequence of selects of the form: |
| // SELECT(Mask3, In3, |
| // SELECT(Mask2, In2, |
| // ( ...))) |
| for (unsigned In = 0; In < NumIncoming; In++) { |
| VectorParts Cond = createEdgeMask(P->getIncomingBlock(In), |
| P->getParent()); |
| VectorParts &In0 = getVectorValue(P->getIncomingValue(In)); |
| |
| for (unsigned part = 0; part < UF; ++part) { |
| // We might have single edge PHIs (blocks) - use an identity |
| // 'select' for the first PHI operand. |
| if (In == 0) |
| Entry[part] = Builder.CreateSelect(Cond[part], In0[part], |
| In0[part]); |
| else |
| // Select between the current value and the previous incoming edge |
| // based on the incoming mask. |
| Entry[part] = Builder.CreateSelect(Cond[part], In0[part], |
| Entry[part], "predphi"); |
| } |
| } |
| return; |
| } |
| |
| // This PHINode must be an induction variable. |
| // Make sure that we know about it. |
| assert(Legal->getInductionVars()->count(P) && |
| "Not an induction variable"); |
| |
| LoopVectorizationLegality::InductionInfo II = |
| Legal->getInductionVars()->lookup(P); |
| |
| // FIXME: The newly created binary instructions should contain nsw/nuw flags, |
| // which can be found from the original scalar operations. |
| switch (II.IK) { |
| case LoopVectorizationLegality::IK_NoInduction: |
| llvm_unreachable("Unknown induction"); |
| case LoopVectorizationLegality::IK_IntInduction: { |
| assert(P->getType() == II.StartValue->getType() && "Types must match"); |
| Type *PhiTy = P->getType(); |
| Value *Broadcasted; |
| if (P == OldInduction) { |
| // Handle the canonical induction variable. We might have had to |
| // extend the type. |
| Broadcasted = Builder.CreateTrunc(Induction, PhiTy); |
| } else { |
| // Handle other induction variables that are now based on the |
| // canonical one. |
| Value *NormalizedIdx = Builder.CreateSub(Induction, ExtendedIdx, |
| "normalized.idx"); |
| NormalizedIdx = Builder.CreateSExtOrTrunc(NormalizedIdx, PhiTy); |
| Broadcasted = II.transform(Builder, NormalizedIdx); |
| Broadcasted->setName("offset.idx"); |
| } |
| Broadcasted = getBroadcastInstrs(Broadcasted); |
| // After broadcasting the induction variable we need to make the vector |
| // consecutive by adding 0, 1, 2, etc. |
| for (unsigned part = 0; part < UF; ++part) |
| Entry[part] = getStepVector(Broadcasted, VF * part, II.StepValue); |
| return; |
| } |
| case LoopVectorizationLegality::IK_PtrInduction: |
| // Handle the pointer induction variable case. |
| assert(P->getType()->isPointerTy() && "Unexpected type."); |
| // This is the normalized GEP that starts counting at zero. |
| Value *NormalizedIdx = |
| Builder.CreateSub(Induction, ExtendedIdx, "normalized.idx"); |
| NormalizedIdx = |
| Builder.CreateSExtOrTrunc(NormalizedIdx, II.StepValue->getType()); |
| // This is the vector of results. Notice that we don't generate |
| // vector geps because scalar geps result in better code. |
| for (unsigned part = 0; part < UF; ++part) { |
| if (VF == 1) { |
| int EltIndex = part; |
| Constant *Idx = ConstantInt::get(NormalizedIdx->getType(), EltIndex); |
| Value *GlobalIdx = Builder.CreateAdd(NormalizedIdx, Idx); |
| Value *SclrGep = II.transform(Builder, GlobalIdx); |
| SclrGep->setName("next.gep"); |
| Entry[part] = SclrGep; |
| continue; |
| } |
| |
| Value *VecVal = UndefValue::get(VectorType::get(P->getType(), VF)); |
| for (unsigned int i = 0; i < VF; ++i) { |
| int EltIndex = i + part * VF; |
| Constant *Idx = ConstantInt::get(NormalizedIdx->getType(), EltIndex); |
| Value *GlobalIdx = Builder.CreateAdd(NormalizedIdx, Idx); |
| Value *SclrGep = II.transform(Builder, GlobalIdx); |
| SclrGep->setName("next.gep"); |
| VecVal = Builder.CreateInsertElement(VecVal, SclrGep, |
| Builder.getInt32(i), |
| "insert.gep"); |
| } |
| Entry[part] = VecVal; |
| } |
| return; |
| } |
| } |
| |
| void InnerLoopVectorizer::vectorizeBlockInLoop(BasicBlock *BB, PhiVector *PV) { |
| // For each instruction in the old loop. |
| for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e; ++it) { |
| VectorParts &Entry = WidenMap.get(it); |
| switch (it->getOpcode()) { |
| case Instruction::Br: |
| // Nothing to do for PHIs and BR, since we already took care of the |
| // loop control flow instructions. |
| continue; |
| case Instruction::PHI: { |
| // Vectorize PHINodes. |
| widenPHIInstruction(it, Entry, UF, VF, PV); |
| continue; |
| }// End of PHI. |
| |
| case Instruction::Add: |
| case Instruction::FAdd: |
| case Instruction::Sub: |
| case Instruction::FSub: |
| case Instruction::Mul: |
| case Instruction::FMul: |
| case Instruction::UDiv: |
| case Instruction::SDiv: |
| case Instruction::FDiv: |
| case Instruction::URem: |
| case Instruction::SRem: |
| case Instruction::FRem: |
| case Instruction::Shl: |
| case Instruction::LShr: |
| case Instruction::AShr: |
| case Instruction::And: |
| case Instruction::Or: |
| case Instruction::Xor: { |
| // Just widen binops. |
| BinaryOperator *BinOp = dyn_cast<BinaryOperator>(it); |
| setDebugLocFromInst(Builder, BinOp); |
| VectorParts &A = getVectorValue(it->getOperand(0)); |
| VectorParts &B = getVectorValue(it->getOperand(1)); |
| |
| // Use this vector value for all users of the original instruction. |
| for (unsigned Part = 0; Part < UF; ++Part) { |
| Value *V = Builder.CreateBinOp(BinOp->getOpcode(), A[Part], B[Part]); |
| |
| if (BinaryOperator *VecOp = dyn_cast<BinaryOperator>(V)) |
| VecOp->copyIRFlags(BinOp); |
| |
| Entry[Part] = V; |
| } |
| |
| propagateMetadata(Entry, it); |
| break; |
| } |
| case Instruction::Select: { |
| // Widen selects. |
| // If the selector is loop invariant we can create a select |
| // instruction with a scalar condition. Otherwise, use vector-select. |
| bool InvariantCond = SE->isLoopInvariant(SE->getSCEV(it->getOperand(0)), |
| OrigLoop); |
| setDebugLocFromInst(Builder, it); |
| |
| // The condition can be loop invariant but still defined inside the |
| // loop. This means that we can't just use the original 'cond' value. |
| // We have to take the 'vectorized' value and pick the first lane. |
| // Instcombine will make this a no-op. |
| VectorParts &Cond = getVectorValue(it->getOperand(0)); |
| VectorParts &Op0 = getVectorValue(it->getOperand(1)); |
| VectorParts &Op1 = getVectorValue(it->getOperand(2)); |
| |
| Value *ScalarCond = (VF == 1) ? Cond[0] : |
| Builder.CreateExtractElement(Cond[0], Builder.getInt32(0)); |
| |
| for (unsigned Part = 0; Part < UF; ++Part) { |
| Entry[Part] = Builder.CreateSelect( |
| InvariantCond ? ScalarCond : Cond[Part], |
| Op0[Part], |
| Op1[Part]); |
| } |
| |
| propagateMetadata(Entry, it); |
| break; |
| } |
| |
| case Instruction::ICmp: |
| case Instruction::FCmp: { |
| // Widen compares. Generate vector compares. |
| bool FCmp = (it->getOpcode() == Instruction::FCmp); |
| CmpInst *Cmp = dyn_cast<CmpInst>(it); |
| setDebugLocFromInst(Builder, it); |
| VectorParts &A = getVectorValue(it->getOperand(0)); |
| VectorParts &B = getVectorValue(it->getOperand(1)); |
| for (unsigned Part = 0; Part < UF; ++Part) { |
| Value *C = nullptr; |
| if (FCmp) |
| C = Builder.CreateFCmp(Cmp->getPredicate(), A[Part], B[Part]); |
| else |
| C = Builder.CreateICmp(Cmp->getPredicate(), A[Part], B[Part]); |
| Entry[Part] = C; |
| } |
| |
| propagateMetadata(Entry, it); |
| break; |
| } |
| |
| case Instruction::Store: |
| case Instruction::Load: |
| vectorizeMemoryInstruction(it); |
| break; |
| case Instruction::ZExt: |
| case Instruction::SExt: |
| case Instruction::FPToUI: |
| case Instruction::FPToSI: |
| case Instruction::FPExt: |
| case Instruction::PtrToInt: |
| case Instruction::IntToPtr: |
| case Instruction::SIToFP: |
| case Instruction::UIToFP: |
| case Instruction::Trunc: |
| case Instruction::FPTrunc: |
| case Instruction::BitCast: { |
| CastInst *CI = dyn_cast<CastInst>(it); |
| setDebugLocFromInst(Builder, it); |
| /// Optimize the special case where the source is the induction |
| /// variable. Notice that we can only optimize the 'trunc' case |
| /// because: a. FP conversions lose precision, b. sext/zext may wrap, |
| /// c. other casts depend on pointer size. |
| if (CI->getOperand(0) == OldInduction && |
| it->getOpcode() == Instruction::Trunc) { |
| Value *ScalarCast = Builder.CreateCast(CI->getOpcode(), Induction, |
| CI->getType()); |
| Value *Broadcasted = getBroadcastInstrs(ScalarCast); |
| LoopVectorizationLegality::InductionInfo II = |
| Legal->getInductionVars()->lookup(OldInduction); |
| Constant *Step = |
| ConstantInt::getSigned(CI->getType(), II.StepValue->getSExtValue()); |
| for (unsigned Part = 0; Part < UF; ++Part) |
| Entry[Part] = getStepVector(Broadcasted, VF * Part, Step); |
| propagateMetadata(Entry, it); |
| break; |
| } |
| /// Vectorize casts. |
| Type *DestTy = (VF == 1) ? CI->getType() : |
| VectorType::get(CI->getType(), VF); |
| |
| VectorParts &A = getVectorValue(it->getOperand(0)); |
| for (unsigned Part = 0; Part < UF; ++Part) |
| Entry[Part] = Builder.CreateCast(CI->getOpcode(), A[Part], DestTy); |
| propagateMetadata(Entry, it); |
| break; |
| } |
| |
| case Instruction::Call: { |
| // Ignore dbg intrinsics. |
| if (isa<DbgInfoIntrinsic>(it)) |
| break; |
| setDebugLocFromInst(Builder, it); |
| |
| Module *M = BB->getParent()->getParent(); |
| CallInst *CI = cast<CallInst>(it); |
| |
| StringRef FnName = CI->getCalledFunction()->getName(); |
| Function *F = CI->getCalledFunction(); |
| Type *RetTy = ToVectorTy(CI->getType(), VF); |
| SmallVector<Type *, 4> Tys; |
| for (unsigned i = 0, ie = CI->getNumArgOperands(); i != ie; ++i) |
| Tys.push_back(ToVectorTy(CI->getArgOperand(i)->getType(), VF)); |
| |
| Intrinsic::ID ID = getIntrinsicIDForCall(CI, TLI); |
| if (ID && |
| (ID == Intrinsic::assume || ID == Intrinsic::lifetime_end || |
| ID == Intrinsic::lifetime_start)) { |
| scalarizeInstruction(it); |
| break; |
| } |
| // The flag shows whether we use Intrinsic or a usual Call for vectorized |
| // version of the instruction. |
| // Is it beneficial to perform intrinsic call compared to lib call? |
| bool NeedToScalarize; |
| unsigned CallCost = getVectorCallCost(CI, VF, *TTI, TLI, NeedToScalarize); |
| bool UseVectorIntrinsic = |
| ID && getVectorIntrinsicCost(CI, VF, *TTI, TLI) <= CallCost; |
| if (!UseVectorIntrinsic && NeedToScalarize) { |
| scalarizeInstruction(it); |
| break; |
| } |
| |
| for (unsigned Part = 0; Part < UF; ++Part) { |
| SmallVector<Value *, 4> Args; |
| for (unsigned i = 0, ie = CI->getNumArgOperands(); i != ie; ++i) { |
| Value *Arg = CI->getArgOperand(i); |
| // Some intrinsics have a scalar argument - don't replace it with a |
| // vector. |
| if (!UseVectorIntrinsic || !hasVectorInstrinsicScalarOpd(ID, i)) { |
| VectorParts &VectorArg = getVectorValue(CI->getArgOperand(i)); |
| Arg = VectorArg[Part]; |
| } |
| Args.push_back(Arg); |
| } |
| |
| Function *VectorF; |
| if (UseVectorIntrinsic) { |
| // Use vector version of the intrinsic. |
| Type *TysForDecl[] = {CI->getType()}; |
| if (VF > 1) |
| TysForDecl[0] = VectorType::get(CI->getType()->getScalarType(), VF); |
| VectorF = Intrinsic::getDeclaration(M, ID, TysForDecl); |
| } else { |
| // Use vector version of the library call. |
| StringRef VFnName = TLI->getVectorizedFunction(FnName, VF); |
| assert(!VFnName.empty() && "Vector function name is empty."); |
| VectorF = M->getFunction(VFnName); |
| if (!VectorF) { |
| // Generate a declaration |
| FunctionType *FTy = FunctionType::get(RetTy, Tys, false); |
| VectorF = |
| Function::Create(FTy, Function::ExternalLinkage, VFnName, M); |
| VectorF->copyAttributesFrom(F); |
| } |
| } |
| assert(VectorF && "Can't create vector function."); |
| Entry[Part] = Builder.CreateCall(VectorF, Args); |
| } |
| |
| propagateMetadata(Entry, it); |
| break; |
| } |
| |
| default: |
| // All other instructions are unsupported. Scalarize them. |
| scalarizeInstruction(it); |
| break; |
| }// end of switch. |
| }// end of for_each instr. |
| } |
| |
| void InnerLoopVectorizer::updateAnalysis() { |
| // Forget the original basic block. |
| SE->forgetLoop(OrigLoop); |
| |
| // Update the dominator tree information. |
| assert(DT->properlyDominates(LoopBypassBlocks.front(), LoopExitBlock) && |
| "Entry does not dominate exit."); |
| |
| for (unsigned I = 1, E = LoopBypassBlocks.size(); I != E; ++I) |
| DT->addNewBlock(LoopBypassBlocks[I], LoopBypassBlocks[I-1]); |
| DT->addNewBlock(LoopVectorPreHeader, LoopBypassBlocks.back()); |
| |
| // Due to if predication of stores we might create a sequence of "if(pred) |
| // a[i] = ...; " blocks. |
| for (unsigned i = 0, e = LoopVectorBody.size(); i != e; ++i) { |
| if (i == 0) |
| DT->addNewBlock(LoopVectorBody[0], LoopVectorPreHeader); |
| else if (isPredicatedBlock(i)) { |
| DT->addNewBlock(LoopVectorBody[i], LoopVectorBody[i-1]); |
| } else { |
| DT->addNewBlock(LoopVectorBody[i], LoopVectorBody[i-2]); |
| } |
| } |
| |
| DT->addNewBlock(LoopMiddleBlock, LoopBypassBlocks[1]); |
| DT->addNewBlock(LoopScalarPreHeader, LoopBypassBlocks[0]); |
| DT->changeImmediateDominator(LoopScalarBody, LoopScalarPreHeader); |
| DT->changeImmediateDominator(LoopExitBlock, LoopBypassBlocks[0]); |
| |
| DEBUG(DT->verifyDomTree()); |
| } |
| |
| /// \brief Check whether it is safe to if-convert this phi node. |
| /// |
| /// Phi nodes with constant expressions that can trap are not safe to if |
| /// convert. |
| static bool canIfConvertPHINodes(BasicBlock *BB) { |
| for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) { |
| PHINode *Phi = dyn_cast<PHINode>(I); |
| if (!Phi) |
| return true; |
| for (unsigned p = 0, e = Phi->getNumIncomingValues(); p != e; ++p) |
| if (Constant *C = dyn_cast<Constant>(Phi->getIncomingValue(p))) |
| if (C->canTrap()) |
| return false; |
| } |
| return true; |
| } |
| |
| bool LoopVectorizationLegality::canVectorizeWithIfConvert() { |
| if (!EnableIfConversion) { |
| emitAnalysis(VectorizationReport() << "if-conversion is disabled"); |
| return false; |
| } |
| |
| assert(TheLoop->getNumBlocks() > 1 && "Single block loops are vectorizable"); |
| |
| // A list of pointers that we can safely read and write to. |
| SmallPtrSet<Value *, 8> SafePointes; |
| |
| // Collect safe addresses. |
| for (Loop::block_iterator BI = TheLoop->block_begin(), |
| BE = TheLoop->block_end(); BI != BE; ++BI) { |
| BasicBlock *BB = *BI; |
| |
| if (blockNeedsPredication(BB)) |
| continue; |
| |
| for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) { |
| if (LoadInst *LI = dyn_cast<LoadInst>(I)) |
| SafePointes.insert(LI->getPointerOperand()); |
| else if (StoreInst *SI = dyn_cast<StoreInst>(I)) |
| SafePointes.insert(SI->getPointerOperand()); |
| } |
| } |
| |
| // Collect the blocks that need predication. |
| BasicBlock *Header = TheLoop->getHeader(); |
| for (Loop::block_iterator BI = TheLoop->block_begin(), |
| BE = TheLoop->block_end(); BI != BE; ++BI) { |
| BasicBlock *BB = *BI; |
| |
| // We don't support switch statements inside loops. |
| if (!isa<BranchInst>(BB->getTerminator())) { |
| emitAnalysis(VectorizationReport(BB->getTerminator()) |
| << "loop contains a switch statement"); |
| return false; |
| } |
| |
| // We must be able to predicate all blocks that need to be predicated. |
| if (blockNeedsPredication(BB)) { |
| if (!blockCanBePredicated(BB, SafePointes)) { |
| emitAnalysis(VectorizationReport(BB->getTerminator()) |
| << "control flow cannot be substituted for a select"); |
| return false; |
| } |
| } else if (BB != Header && !canIfConvertPHINodes(BB)) { |
| emitAnalysis(VectorizationReport(BB->getTerminator()) |
| << "control flow cannot be substituted for a select"); |
| return false; |
| } |
| } |
| |
| // We can if-convert this loop. |
| return true; |
| } |
| |
| bool LoopVectorizationLegality::canVectorize() { |
| // We must have a loop in canonical form. Loops with indirectbr in them cannot |
| // be canonicalized. |
| if (!TheLoop->getLoopPreheader()) { |
| emitAnalysis( |
| VectorizationReport() << |
| "loop control flow is not understood by vectorizer"); |
| return false; |
| } |
| |
| // We can only vectorize innermost loops. |
| if (!TheLoop->empty()) { |
| emitAnalysis(VectorizationReport() << "loop is not the innermost loop"); |
| return false; |
| } |
| |
| // We must have a single backedge. |
| if (TheLoop->getNumBackEdges() != 1) { |
| emitAnalysis( |
| VectorizationReport() << |
| "loop control flow is not understood by vectorizer"); |
| return false; |
| } |
| |
| // We must have a single exiting block. |
| if (!TheLoop->getExitingBlock()) { |
| emitAnalysis( |
| VectorizationReport() << |
| "loop control flow is not understood by vectorizer"); |
| return false; |
| } |
| |
| // We only handle bottom-tested loops, i.e. loop in which the condition is |
| // checked at the end of each iteration. With that we can assume that all |
| // instructions in the loop are executed the same number of times. |
| if (TheLoop->getExitingBlock() != TheLoop->getLoopLatch()) { |
| emitAnalysis( |
| VectorizationReport() << |
| "loop control flow is not understood by vectorizer"); |
| return false; |
| } |
| |
| // We need to have a loop header. |
| DEBUG(dbgs() << "LV: Found a loop: " << |
| TheLoop->getHeader()->getName() << '\n'); |
| |
| // Check if we can if-convert non-single-bb loops. |
| unsigned NumBlocks = TheLoop->getNumBlocks(); |
| if (NumBlocks != 1 && !canVectorizeWithIfConvert()) { |
| DEBUG(dbgs() << "LV: Can't if-convert the loop.\n"); |
| return false; |
| } |
| |
| // ScalarEvolution needs to be able to find the exit count. |
| const SCEV *ExitCount = SE->getBackedgeTakenCount(TheLoop); |
| if (ExitCount == SE->getCouldNotCompute()) { |
| emitAnalysis(VectorizationReport() << |
| "could not determine number of loop iterations"); |
| DEBUG(dbgs() << "LV: SCEV could not compute the loop exit count.\n"); |
| return false; |
| } |
| |
| // Check if we can vectorize the instructions and CFG in this loop. |
| if (!canVectorizeInstrs()) { |
| DEBUG(dbgs() << "LV: Can't vectorize the instructions or CFG\n"); |
| return false; |
| } |
| |
| // Go over each instruction and look at memory deps. |
| if (!canVectorizeMemory()) { |
| DEBUG(dbgs() << "LV: Can't vectorize due to memory conflicts\n"); |
| return false; |
| } |
| |
| // Collect all of the variables that remain uniform after vectorization. |
| collectLoopUniforms(); |
| |
| DEBUG(dbgs() << "LV: We can vectorize this loop" |
| << (LAI->getRuntimePointerChecking()->Need |
| ? " (with a runtime bound check)" |
| : "") |
| << "!\n"); |
| |
| // Analyze interleaved memory accesses. |
| if (EnableInterleavedMemAccesses) |
| InterleaveInfo.analyzeInterleaving(Strides); |
| |
| // Okay! We can vectorize. At this point we don't have any other mem analysis |
| // which may limit our maximum vectorization factor, so just return true with |
| // no restrictions. |
| return true; |
| } |
| |
| static Type *convertPointerToIntegerType(const DataLayout &DL, Type *Ty) { |
| if (Ty->isPointerTy()) |
| return DL.getIntPtrType(Ty); |
| |
| // It is possible that char's or short's overflow when we ask for the loop's |
| // trip count, work around this by changing the type size. |
| if (Ty->getScalarSizeInBits() < 32) |
| return Type::getInt32Ty(Ty->getContext()); |
| |
| return Ty; |
| } |
| |
| static Type* getWiderType(const DataLayout &DL, Type *Ty0, Type *Ty1) { |
| Ty0 = convertPointerToIntegerType(DL, Ty0); |
| Ty1 = convertPointerToIntegerType(DL, Ty1); |
| if (Ty0->getScalarSizeInBits() > Ty1->getScalarSizeInBits()) |
| return Ty0; |
| return Ty1; |
| } |
| |
| /// \brief Check that the instruction has outside loop users and is not an |
| /// identified reduction variable. |
| static bool hasOutsideLoopUser(const Loop *TheLoop, Instruction *Inst, |
| SmallPtrSetImpl<Value *> &Reductions) { |
| // Reduction instructions are allowed to have exit users. All other |
| // instructions must not have external users. |
| if (!Reductions.count(Inst)) |
| //Check that all of the users of the loop are inside the BB. |
| for (User *U : Inst->users()) { |
| Instruction *UI = cast<Instruction>(U); |
| // This user may be a reduction exit value. |
| if (!TheLoop->contains(UI)) { |
| DEBUG(dbgs() << "LV: Found an outside user for : " << *UI << '\n'); |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| bool LoopVectorizationLegality::canVectorizeInstrs() { |
| BasicBlock *PreHeader = TheLoop->getLoopPreheader(); |
| BasicBlock *Header = TheLoop->getHeader(); |
| |
| // Look for the attribute signaling the absence of NaNs. |
| Function &F = *Header->getParent(); |
| const DataLayout &DL = F.getParent()->getDataLayout(); |
| if (F.hasFnAttribute("no-nans-fp-math")) |
| HasFunNoNaNAttr = |
| F.getFnAttribute("no-nans-fp-math").getValueAsString() == "true"; |
| |
| // For each block in the loop. |
| for (Loop::block_iterator bb = TheLoop->block_begin(), |
| be = TheLoop->block_end(); bb != be; ++bb) { |
| |
| // Scan the instructions in the block and look for hazards. |
| for (BasicBlock::iterator it = (*bb)->begin(), e = (*bb)->end(); it != e; |
| ++it) { |
| |
| if (PHINode *Phi = dyn_cast<PHINode>(it)) { |
| Type *PhiTy = Phi->getType(); |
| // Check that this PHI type is allowed. |
| if (!PhiTy->isIntegerTy() && |
| !PhiTy->isFloatingPointTy() && |
| !PhiTy->isPointerTy()) { |
| emitAnalysis(VectorizationReport(it) |
| << "loop control flow is not understood by vectorizer"); |
| DEBUG(dbgs() << "LV: Found an non-int non-pointer PHI.\n"); |
| return false; |
| } |
| |
| // If this PHINode is not in the header block, then we know that we |
| // can convert it to select during if-conversion. No need to check if |
| // the PHIs in this block are induction or reduction variables. |
| if (*bb != Header) { |
| // Check that this instruction has no outside users or is an |
| // identified reduction value with an outside user. |
| if (!hasOutsideLoopUser(TheLoop, it, AllowedExit)) |
| continue; |
| emitAnalysis(VectorizationReport(it) << |
| "value could not be identified as " |
| "an induction or reduction variable"); |
| return false; |
| } |
| |
| // We only allow if-converted PHIs with exactly two incoming values. |
| if (Phi->getNumIncomingValues() != 2) { |
| emitAnalysis(VectorizationReport(it) |
| << "control flow not understood by vectorizer"); |
| DEBUG(dbgs() << "LV: Found an invalid PHI.\n"); |
| return false; |
| } |
| |
| // This is the value coming from the preheader. |
| Value *StartValue = Phi->getIncomingValueForBlock(PreHeader); |
| ConstantInt *StepValue = nullptr; |
| // Check if this is an induction variable. |
| InductionKind IK = isInductionVariable(Phi, StepValue); |
| |
| if (IK_NoInduction != IK) { |
| // Get the widest type. |
| if (!WidestIndTy) |
| WidestIndTy = convertPointerToIntegerType(DL, PhiTy); |
| else |
| WidestIndTy = getWiderType(DL, PhiTy, WidestIndTy); |
| |
| // Int inductions are special because we only allow one IV. |
| if (IK == IK_IntInduction && StepValue->isOne()) { |
| // Use the phi node with the widest type as induction. Use the last |
| // one if there are multiple (no good reason for doing this other |
| // than it is expedient). |
| if (!Induction || PhiTy == WidestIndTy) |
| Induction = Phi; |
| } |
| |
| DEBUG(dbgs() << "LV: Found an induction variable.\n"); |
| Inductions[Phi] = InductionInfo(StartValue, IK, StepValue); |
| |
| // Until we explicitly handle the case of an induction variable with |
| // an outside loop user we have to give up vectorizing this loop. |
| if (hasOutsideLoopUser(TheLoop, it, AllowedExit)) { |
| emitAnalysis(VectorizationReport(it) << |
| "use of induction value outside of the " |
| "loop is not handled by vectorizer"); |
| return false; |
| } |
| |
| continue; |
| } |
| |
| if (RecurrenceDescriptor::isReductionPHI(Phi, TheLoop, |
| Reductions[Phi])) { |
| AllowedExit.insert(Reductions[Phi].getLoopExitInstr()); |
| continue; |
| } |
| |
| emitAnalysis(VectorizationReport(it) << |
| "value that could not be identified as " |
| "reduction is used outside the loop"); |
| DEBUG(dbgs() << "LV: Found an unidentified PHI."<< *Phi <<"\n"); |
| return false; |
| }// end of PHI handling |
| |
| // We handle calls that: |
| // * Are debug info intrinsics. |
| // * Have a mapping to an IR intrinsic. |
| // * Have a vector version available. |
| CallInst *CI = dyn_cast<CallInst>(it); |
| if (CI && !getIntrinsicIDForCall(CI, TLI) && !isa<DbgInfoIntrinsic>(CI) && |
| !(CI->getCalledFunction() && TLI && |
| TLI->isFunctionVectorizable(CI->getCalledFunction()->getName()))) { |
| emitAnalysis(VectorizationReport(it) << |
| "call instruction cannot be vectorized"); |
| DEBUG(dbgs() << "LV: Found a non-intrinsic, non-libfunc callsite.\n"); |
| return false; |
| } |
| |
| // Intrinsics such as powi,cttz and ctlz are legal to vectorize if the |
| // second argument is the same (i.e. loop invariant) |
| if (CI && |
| hasVectorInstrinsicScalarOpd(getIntrinsicIDForCall(CI, TLI), 1)) { |
| if (!SE->isLoopInvariant(SE->getSCEV(CI->getOperand(1)), TheLoop)) { |
| emitAnalysis(VectorizationReport(it) |
| << "intrinsic instruction cannot be vectorized"); |
| DEBUG(dbgs() << "LV: Found unvectorizable intrinsic " << *CI << "\n"); |
| return false; |
| } |
| } |
| |
| // Check that the instruction return type is vectorizable. |
| // Also, we can't vectorize extractelement instructions. |
| if ((!VectorType::isValidElementType(it->getType()) && |
| !it->getType()->isVoidTy()) || isa<ExtractElementInst>(it)) { |
| emitAnalysis(VectorizationReport(it) |
| << "instruction return type cannot be vectorized"); |
| DEBUG(dbgs() << "LV: Found unvectorizable type.\n"); |
| return false; |
| } |
| |
| // Check that the stored type is vectorizable. |
| if (StoreInst *ST = dyn_cast<StoreInst>(it)) { |
| Type *T = ST->getValueOperand()->getType(); |
| if (!VectorType::isValidElementType(T)) { |
| emitAnalysis(VectorizationReport(ST) << |
| "store instruction cannot be vectorized"); |
| return false; |
| } |
| if (EnableMemAccessVersioning) |
| collectStridedAccess(ST); |
| } |
| |
| if (EnableMemAccessVersioning) |
| if (LoadInst *LI = dyn_cast<LoadInst>(it)) |
| collectStridedAccess(LI); |
| |
| // Reduction instructions are allowed to have exit users. |
| // All other instructions must not have external users. |
| if (hasOutsideLoopUser(TheLoop, it, AllowedExit)) { |
| emitAnalysis(VectorizationReport(it) << |
| "value cannot be used outside the loop"); |
| return false; |
| } |
| |
| } // next instr. |
| |
| } |
| |
| if (!Induction) { |
| DEBUG(dbgs() << "LV: Did not find one integer induction var.\n"); |
| if (Inductions.empty()) { |
| emitAnalysis(VectorizationReport() |
| << "loop induction variable could not be identified"); |
| return false; |
| } |
| } |
| |
| return true; |
| } |
| |
| void LoopVectorizationLegality::collectStridedAccess(Value *MemAccess) { |
| Value *Ptr = nullptr; |
| if (LoadInst *LI = dyn_cast<LoadInst>(MemAccess)) |
| Ptr = LI->getPointerOperand(); |
| else if (StoreInst *SI = dyn_cast<StoreInst>(MemAccess)) |
| Ptr = SI->getPointerOperand(); |
| else |
| return; |
| |
| Value *Stride = getStrideFromPointer(Ptr, SE, TheLoop); |
| if (!Stride) |
| return; |
| |
| DEBUG(dbgs() << "LV: Found a strided access that we can version"); |
| DEBUG(dbgs() << " Ptr: " << *Ptr << " Stride: " << *Stride << "\n"); |
| Strides[Ptr] = Stride; |
| StrideSet.insert(Stride); |
| } |
| |
| void LoopVectorizationLegality::collectLoopUniforms() { |
| // We now know that the loop is vectorizable! |
| // Collect variables that will remain uniform after vectorization. |
| std::vector<Value*> Worklist; |
| BasicBlock *Latch = TheLoop->getLoopLatch(); |
| |
| // Start with the conditional branch and walk up the block. |
| Worklist.push_back(Latch->getTerminator()->getOperand(0)); |
| |
| // Also add all consecutive pointer values; these values will be uniform |
| // after vectorization (and subsequent cleanup) and, until revectorization is |
| // supported, all dependencies must also be uniform. |
| for (Loop::block_iterator B = TheLoop->block_begin(), |
| BE = TheLoop->block_end(); B != BE; ++B) |
| for (BasicBlock::iterator I = (*B)->begin(), IE = (*B)->end(); |
| I != IE; ++I) |
| if (I->getType()->isPointerTy() && isConsecutivePtr(I)) |
| Worklist.insert(Worklist.end(), I->op_begin(), I->op_end()); |
| |
| while (!Worklist.empty()) { |
| Instruction *I = dyn_cast<Instruction>(Worklist.back()); |
| Worklist.pop_back(); |
| |
| // Look at instructions inside this loop. |
| // Stop when reaching PHI nodes. |
| // TODO: we need to follow values all over the loop, not only in this block. |
| if (!I || !TheLoop->contains(I) || isa<PHINode>(I)) |
| continue; |
| |
| // This is a known uniform. |
| Uniforms.insert(I); |
| |
| // Insert all operands. |
| Worklist.insert(Worklist.end(), I->op_begin(), I->op_end()); |
| } |
| } |
| |
| bool LoopVectorizationLegality::canVectorizeMemory() { |
| LAI = &LAA->getInfo(TheLoop, Strides); |
| auto &OptionalReport = LAI->getReport(); |
| if (OptionalReport) |
| emitAnalysis(VectorizationReport(*OptionalReport)); |
| if (!LAI->canVectorizeMemory()) |
| return false; |
| |
| if (LAI->hasStoreToLoopInvariantAddress()) { |
| emitAnalysis( |
| VectorizationReport() |
| << "write to a loop invariant address could not be vectorized"); |
| DEBUG(dbgs() << "LV: We don't allow storing to uniform addresses\n"); |
| return false; |
| } |
| |
| if (LAI->getNumRuntimePointerChecks() > |
| VectorizerParams::RuntimeMemoryCheckThreshold) { |
| emitAnalysis(VectorizationReport() |
| << LAI->getNumRuntimePointerChecks() << " exceeds limit of " |
| << VectorizerParams::RuntimeMemoryCheckThreshold |
| << " dependent memory operations checked at runtime"); |
| DEBUG(dbgs() << "LV: Too many memory checks needed.\n"); |
| return false; |
| } |
| return true; |
| } |
| |
| LoopVectorizationLegality::InductionKind |
| LoopVectorizationLegality::isInductionVariable(PHINode *Phi, |
| ConstantInt *&StepValue) { |
| if (!isInductionPHI(Phi, SE, StepValue)) |
| return IK_NoInduction; |
| |
| Type *PhiTy = Phi->getType(); |
| // Found an Integer induction variable. |
| if (PhiTy->isIntegerTy()) |
| return IK_IntInduction; |
| // Found an Pointer induction variable. |
| return IK_PtrInduction; |
| } |
| |
| bool LoopVectorizationLegality::isInductionVariable(const Value *V) { |
| Value *In0 = const_cast<Value*>(V); |
| PHINode *PN = dyn_cast_or_null<PHINode>(In0); |
| if (!PN) |
| return false; |
| |
| return Inductions.count(PN); |
| } |
| |
| bool LoopVectorizationLegality::blockNeedsPredication(BasicBlock *BB) { |
| return LoopAccessInfo::blockNeedsPredication(BB, TheLoop, DT); |
| } |
| |
| bool LoopVectorizationLegality::blockCanBePredicated(BasicBlock *BB, |
| SmallPtrSetImpl<Value *> &SafePtrs) { |
| |
| for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e; ++it) { |
| // Check that we don't have a constant expression that can trap as operand. |
| for (Instruction::op_iterator OI = it->op_begin(), OE = it->op_end(); |
| OI != OE; ++OI) { |
| if (Constant *C = dyn_cast<Constant>(*OI)) |
| if (C->canTrap()) |
| return false; |
| } |
| // We might be able to hoist the load. |
| if (it->mayReadFromMemory()) { |
| LoadInst *LI = dyn_cast<LoadInst>(it); |
| if (!LI) |
| return false; |
| if (!SafePtrs.count(LI->getPointerOperand())) { |
| if (isLegalMaskedLoad(LI->getType(), LI->getPointerOperand())) { |
| MaskedOp.insert(LI); |
| continue; |
| } |
| return false; |
| } |
| } |
| |
| // We don't predicate stores at the moment. |
| if (it->mayWriteToMemory()) { |
| StoreInst *SI = dyn_cast<StoreInst>(it); |
| // We only support predication of stores in basic blocks with one |
| // predecessor. |
| if (!SI) |
| return false; |
| |
| bool isSafePtr = (SafePtrs.count(SI->getPointerOperand()) != 0); |
| bool isSinglePredecessor = SI->getParent()->getSinglePredecessor(); |
| |
| if (++NumPredStores > NumberOfStoresToPredicate || !isSafePtr || |
| !isSinglePredecessor) { |
| // Build a masked store if it is legal for the target, otherwise scalarize |
| // the block. |
| bool isLegalMaskedOp = |
| isLegalMaskedStore(SI->getValueOperand()->getType(), |
| SI->getPointerOperand()); |
| if (isLegalMaskedOp) { |
| --NumPredStores; |
| MaskedOp.insert(SI); |
| continue; |
| } |
| return false; |
| } |
| } |
| if (it->mayThrow()) |
| return false; |
| |
| // The instructions below can trap. |
| switch (it->getOpcode()) { |
| default: continue; |
| case Instruction::UDiv: |
| case Instruction::SDiv: |
| case Instruction::URem: |
| case Instruction::SRem: |
| return false; |
| } |
| } |
| |
| return true; |
| } |
| |
| void InterleavedAccessInfo::collectConstStridedAccesses( |
| MapVector<Instruction *, StrideDescriptor> &StrideAccesses, |
| const ValueToValueMap &Strides) { |
| // Holds load/store instructions in program order. |
| SmallVector<Instruction *, 16> AccessList; |
| |
| for (auto *BB : TheLoop->getBlocks()) { |
| bool IsPred = LoopAccessInfo::blockNeedsPredication(BB, TheLoop, DT); |
| |
| for (auto &I : *BB) { |
| if (!isa<LoadInst>(&I) && !isa<StoreInst>(&I)) |
| continue; |
| // FIXME: Currently we can't handle mixed accesses and predicated accesses |
| if (IsPred) |
| return; |
| |
| AccessList.push_back(&I); |
| } |
| } |
| |
| if (AccessList.empty()) |
| return; |
| |
| auto &DL = TheLoop->getHeader()->getModule()->getDataLayout(); |
| for (auto I : AccessList) { |
| LoadInst *LI = dyn_cast<LoadInst>(I); |
| StoreInst *SI = dyn_cast<StoreInst>(I); |
| |
| Value *Ptr = LI ? LI->getPointerOperand() : SI->getPointerOperand(); |
| int Stride = isStridedPtr(SE, Ptr, TheLoop, Strides); |
| |
| // The factor of the corresponding interleave group. |
| unsigned Factor = std::abs(Stride); |
| |
| // Ignore the access if the factor is too small or too large. |
| if (Factor < 2 || Factor > MaxInterleaveGroupFactor) |
| continue; |
| |
| const SCEV *Scev = replaceSymbolicStrideSCEV(SE, Strides, Ptr); |
| PointerType *PtrTy = dyn_cast<PointerType>(Ptr->getType()); |
| unsigned Size = DL.getTypeAllocSize(PtrTy->getElementType()); |
| |
| // An alignment of 0 means target ABI alignment. |
| unsigned Align = LI ? LI->getAlignment() : SI->getAlignment(); |
| if (!Align) |
| Align = DL.getABITypeAlignment(PtrTy->getElementType()); |
| |
| StrideAccesses[I] = StrideDescriptor(Stride, Scev, Size, Align); |
| } |
| } |
| |
| // Analyze interleaved accesses and collect them into interleave groups. |
| // |
| // Notice that the vectorization on interleaved groups will change instruction |
| // orders and may break dependences. But the memory dependence check guarantees |
| // that there is no overlap between two pointers of different strides, element |
| // sizes or underlying bases. |
| // |
| // For pointers sharing the same stride, element size and underlying base, no |
| // need to worry about Read-After-Write dependences and Write-After-Read |
| // dependences. |
| // |
| // E.g. The RAW dependence: A[i] = a; |
| // b = A[i]; |
| // This won't exist as it is a store-load forwarding conflict, which has |
| // already been checked and forbidden in the dependence check. |
| // |
| // E.g. The WAR dependence: a = A[i]; // (1) |
| // A[i] = b; // (2) |
| // The store group of (2) is always inserted at or below (2), and the load group |
| // of (1) is always inserted at or above (1). The dependence is safe. |
| void InterleavedAccessInfo::analyzeInterleaving( |
| const ValueToValueMap &Strides) { |
| DEBUG(dbgs() << "LV: Analyzing interleaved accesses...\n"); |
| |
| // Holds all the stride accesses. |
| MapVector<Instruction *, StrideDescriptor> StrideAccesses; |
| collectConstStridedAccesses(StrideAccesses, Strides); |
| |
| if (StrideAccesses.empty()) |
| return; |
| |
| // Holds all interleaved store groups temporarily. |
| SmallSetVector<InterleaveGroup *, 4> StoreGroups; |
| |
| // Search the load-load/write-write pair B-A in bottom-up order and try to |
| // insert B into the interleave group of A according to 3 rules: |
| // 1. A and B have the same stride. |
| // 2. A and B have the same memory object size. |
| // 3. B belongs to the group according to the distance. |
| // |
| // The bottom-up order can avoid breaking the Write-After-Write dependences |
| // between two pointers of the same base. |
| // E.g. A[i] = a; (1) |
| // A[i] = b; (2) |
| // A[i+1] = c (3) |
| // We form the group (2)+(3) in front, so (1) has to form groups with accesses |
| // above (1), which guarantees that (1) is always above (2). |
| for (auto I = StrideAccesses.rbegin(), E = StrideAccesses.rend(); I != E; |
| ++I) { |
| Instruction *A = I->first; |
| StrideDescriptor DesA = I->second; |
| |
| InterleaveGroup *Group = getInterleaveGroup(A); |
| if (!Group) { |
| DEBUG(dbgs() << "LV: Creating an interleave group with:" << *A << '\n'); |
| Group = createInterleaveGroup(A, DesA.Stride, DesA.Align); |
| } |
| |
| if (A->mayWriteToMemory()) |
| StoreGroups.insert(Group); |
| |
| for (auto II = std::next(I); II != E; ++II) { |
| Instruction *B = II->first; |
| StrideDescriptor DesB = II->second; |
| |
| // Ignore if B is already in a group or B is a different memory operation. |
| if (isInterleaved(B) || A->mayReadFromMemory() != B->mayReadFromMemory()) |
| continue; |
| |
| // Check the rule 1 and 2. |
| if (DesB.Stride != DesA.Stride || DesB.Size != DesA.Size) |
| continue; |
| |
| // Calculate the distance and prepare for the rule 3. |
| const SCEVConstant *DistToA = |
| dyn_cast<SCEVConstant>(SE->getMinusSCEV(DesB.Scev, DesA.Scev)); |
| if (!DistToA) |
| continue; |
| |
| int DistanceToA = DistToA->getValue()->getValue().getSExtValue(); |
| |
| // Skip if the distance is not multiple of size as they are not in the |
| // same group. |
| if (DistanceToA % static_cast<int>(DesA.Size)) |
| continue; |
| |
| // The index of B is the index of A plus the related index to A. |
| int IndexB = |
| Group->getIndex(A) + DistanceToA / static_cast<int>(DesA.Size); |
| |
| // Try to insert B into the group. |
| if (Group->insertMember(B, IndexB, DesB.Align)) { |
| DEBUG(dbgs() << "LV: Inserted:" << *B << '\n' |
| << " into the interleave group with" << *A << '\n'); |
| InterleaveGroupMap[B] = Group; |
| |
| // Set the first load in program order as the insert position. |
| if (B->mayReadFromMemory()) |
| Group->setInsertPos(B); |
| } |
| } // Iteration on instruction B |
| } // Iteration on instruction A |
| |
| // Remove interleaved store groups with gaps. |
| for (InterleaveGroup *Group : StoreGroups) |
| if (Group->getNumMembers() != Group->getFactor()) |
| releaseGroup(Group); |
| } |
| |
| LoopVectorizationCostModel::VectorizationFactor |
| LoopVectorizationCostModel::selectVectorizationFactor(bool OptForSize) { |
| // Width 1 means no vectorize |
| VectorizationFactor Factor = { 1U, 0U }; |
| if (OptForSize && Legal->getRuntimePointerChecking()->Need) { |
| emitAnalysis(VectorizationReport() << |
| "runtime pointer checks needed. Enable vectorization of this " |
| "loop with '#pragma clang loop vectorize(enable)' when " |
| "compiling with -Os"); |
| DEBUG(dbgs() << "LV: Aborting. Runtime ptr check is required in Os.\n"); |
| return Factor; |
| } |
| |
| if (!EnableCondStoresVectorization && Legal->getNumPredStores()) { |
| emitAnalysis(VectorizationReport() << |
| "store that is conditionally executed prevents vectorization"); |
| DEBUG(dbgs() << "LV: No vectorization. There are conditional stores.\n"); |
| return Factor; |
| } |
| |
| // Find the trip count. |
| unsigned TC = SE->getSmallConstantTripCount(TheLoop); |
| DEBUG(dbgs() << "LV: Found trip count: " << TC << '\n'); |
| |
| unsigned WidestType = getWidestType(); |
| unsigned WidestRegister = TTI.getRegisterBitWidth(true); |
| unsigned MaxSafeDepDist = -1U; |
| if (Legal->getMaxSafeDepDistBytes() != -1U) |
| MaxSafeDepDist = Legal->getMaxSafeDepDistBytes() * 8; |
| WidestRegister = ((WidestRegister < MaxSafeDepDist) ? |
| WidestRegister : MaxSafeDepDist); |
| unsigned MaxVectorSize = WidestRegister / WidestType; |
| DEBUG(dbgs() << "LV: The Widest type: " << WidestType << " bits.\n"); |
| DEBUG(dbgs() << "LV: The Widest register is: " |
| << WidestRegister << " bits.\n"); |
| |
| if (MaxVectorSize == 0) { |
| DEBUG(dbgs() << "LV: The target has no vector registers.\n"); |
| MaxVectorSize = 1; |
| } |
| |
| assert(MaxVectorSize <= 64 && "Did not expect to pack so many elements" |
| " into one vector!"); |
| |
| unsigned VF = MaxVectorSize; |
| |
| // If we optimize the program for size, avoid creating the tail loop. |
| if (OptForSize) { |
| // If we are unable to calculate the trip count then don't try to vectorize. |
| if (TC < 2) { |
| emitAnalysis |
| (VectorizationReport() << |
| "unable to calculate the loop count due to complex control flow"); |
| DEBUG(dbgs() << "LV: Aborting. A tail loop is required in Os.\n"); |
| return Factor; |
| } |
| |
| // Find the maximum SIMD width that can fit within the trip count. |
| VF = TC % MaxVectorSize; |
| |
| if (VF == 0) |
| VF = MaxVectorSize; |
| else { |
| // If the trip count that we found modulo the vectorization factor is not |
| // zero then we require a tail. |
| emitAnalysis(VectorizationReport() << |
| "cannot optimize for size and vectorize at the " |
| "same time. Enable vectorization of this loop " |
| "with '#pragma clang loop vectorize(enable)' " |
| "when compiling with -Os"); |
| DEBUG(dbgs() << "LV: Aborting. A tail loop is required in Os.\n"); |
| return Factor; |
| } |
| } |
| |
| int UserVF = Hints->getWidth(); |
| if (UserVF != 0) { |
| assert(isPowerOf2_32(UserVF) && "VF needs to be a power of two"); |
| DEBUG(dbgs() << "LV: Using user VF " << UserVF << ".\n"); |
| |
| Factor.Width = UserVF; |
| return Factor; |
| } |
| |
| float Cost = expectedCost(1); |
| #ifndef NDEBUG |
| const float ScalarCost = Cost; |
| #endif /* NDEBUG */ |
| unsigned Width = 1; |
| DEBUG(dbgs() << "LV: Scalar loop costs: " << (int)ScalarCost << ".\n"); |
| |
| bool ForceVectorization = Hints->getForce() == LoopVectorizeHints::FK_Enabled; |
| // Ignore scalar width, because the user explicitly wants vectorization. |
| if (ForceVectorization && VF > 1) { |
| Width = 2; |
| Cost = expectedCost(Width) / (float)Width; |
| } |
| |
| for (unsigned i=2; i <= VF; i*=2) { |
| // Notice that the vector loop needs to be executed less times, so |
| // we need to divide the cost of the vector loops by the width of |
| // the vector elements. |
| float VectorCost = expectedCost(i) / (float)i; |
| DEBUG(dbgs() << "LV: Vector loop of width " << i << " costs: " << |
| (int)VectorCost << ".\n"); |
| if (VectorCost < Cost) { |
| Cost = VectorCost; |
| Width = i; |
| } |
| } |
| |
| DEBUG(if (ForceVectorization && Width > 1 && Cost >= ScalarCost) dbgs() |
| << "LV: Vectorization seems to be not beneficial, " |
| << "but was forced by a user.\n"); |
| DEBUG(dbgs() << "LV: Selecting VF: "<< Width << ".\n"); |
| Factor.Width = Width; |
| Factor.Cost = Width * Cost; |
| return Factor; |
| } |
| |
| unsigned LoopVectorizationCostModel::getWidestType() { |
| unsigned MaxWidth = 8; |
| const DataLayout &DL = TheFunction->getParent()->getDataLayout(); |
| |
| // For each block. |
| for (Loop::block_iterator bb = TheLoop->block_begin(), |
| be = TheLoop->block_end(); bb != be; ++bb) { |
| BasicBlock *BB = *bb; |
| |
| // For each instruction in the loop. |
| for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e; ++it) { |
| Type *T = it->getType(); |
| |
| // Ignore ephemeral values. |
| if (EphValues.count(it)) |
| continue; |
| |
| // Only examine Loads, Stores and PHINodes. |
| if (!isa<LoadInst>(it) && !isa<StoreInst>(it) && !isa<PHINode>(it)) |
| continue; |
| |
| // Examine PHI nodes that are reduction variables. |
| if (PHINode *PN = dyn_cast<PHINode>(it)) |
| if (!Legal->getReductionVars()->count(PN)) |
| continue; |
| |
| // Examine the stored values. |
| if (StoreInst *ST = dyn_cast<StoreInst>(it)) |
| T = ST->getValueOperand()->getType(); |
| |
| // Ignore loaded pointer types and stored pointer types that are not |
| // consecutive. However, we do want to take consecutive stores/loads of |
| // pointer vectors into account. |
| if (T->isPointerTy() && !isConsecutiveLoadOrStore(it)) |
| continue; |
| |
| MaxWidth = std::max(MaxWidth, |
| (unsigned)DL.getTypeSizeInBits(T->getScalarType())); |
| } |
| } |
| |
| return MaxWidth; |
| } |
| |
| unsigned LoopVectorizationCostModel::selectInterleaveCount(bool OptForSize, |
| unsigned VF, |
| unsigned LoopCost) { |
| |
| // -- The interleave heuristics -- |
| // We interleave the loop in order to expose ILP and reduce the loop overhead. |
| // There are many micro-architectural considerations that we can't predict |
| // at this level. For example, frontend pressure (on decode or fetch) due to |
| // code size, or the number and capabilities of the execution ports. |
| // |
| // We use the following heuristics to select the interleave count: |
| // 1. If the code has reductions, then we interleave to break the cross |
| // iteration dependency. |
| // 2. If the loop is really small, then we interleave to reduce the loop |
| // overhead. |
| // 3. We don't interleave if we think that we will spill registers to memory |
| // due to the increased register pressure. |
| |
| // Use the user preference, unless 'auto' is selected. |
| int UserUF = Hints->getInterleave(); |
| if (UserUF != 0) |
| return UserUF; |
| |
| // When we optimize for size, we don't interleave. |
| if (OptForSize) |
| return 1; |
| |
| // We used the distance for the interleave count. |
| if (Legal->getMaxSafeDepDistBytes() != -1U) |
| return 1; |
| |
| // Do not interleave loops with a relatively small trip count. |
| unsigned TC = SE->getSmallConstantTripCount(TheLoop); |
| if (TC > 1 && TC < TinyTripCountInterleaveThreshold) |
| return 1; |
| |
| unsigned TargetNumRegisters = TTI.getNumberOfRegisters(VF > 1); |
| DEBUG(dbgs() << "LV: The target has " << TargetNumRegisters << |
| " registers\n"); |
| |
| if (VF == 1) { |
| if (ForceTargetNumScalarRegs.getNumOccurrences() > 0) |
| TargetNumRegisters = ForceTargetNumScalarRegs; |
| } else { |
| if (ForceTargetNumVectorRegs.getNumOccurrences() > 0) |
| TargetNumRegisters = ForceTargetNumVectorRegs; |
| } |
| |
| LoopVectorizationCostModel::RegisterUsage R = calculateRegisterUsage(); |
| // We divide by these constants so assume that we have at least one |
| // instruction that uses at least one register. |
| R.MaxLocalUsers = std::max(R.MaxLocalUsers, 1U); |
| R.NumInstructions = std::max(R.NumInstructions, 1U); |
| |
| // We calculate the interleave count using the following formula. |
| // Subtract the number of loop invariants from the number of available |
| // registers. These registers are used by all of the interleaved instances. |
| // Next, divide the remaining registers by the number of registers that is |
| // required by the loop, in order to estimate how many parallel instances |
| // fit without causing spills. All of this is rounded down if necessary to be |
| // a power of two. We want power of two interleave count to simplify any |
| // addressing operations or alignment considerations. |
| unsigned IC = PowerOf2Floor((TargetNumRegisters - R.LoopInvariantRegs) / |
| R.MaxLocalUsers); |
| |
| // Don't count the induction variable as interleaved. |
| if (EnableIndVarRegisterHeur) |
| IC = PowerOf2Floor((TargetNumRegisters - R.LoopInvariantRegs - 1) / |
| std::max(1U, (R.MaxLocalUsers - 1))); |
| |
| // Clamp the interleave ranges to reasonable counts. |
| unsigned MaxInterleaveCount = TTI.getMaxInterleaveFactor(VF); |
| |
| // Check if the user has overridden the max. |
| if (VF == 1) { |
| if (ForceTargetMaxScalarInterleaveFactor.getNumOccurrences() > 0) |
| MaxInterleaveCount = ForceTargetMaxScalarInterleaveFactor; |
| } else { |
| if (ForceTargetMaxVectorInterleaveFactor.getNumOccurrences() > 0) |
| MaxInterleaveCount = ForceTargetMaxVectorInterleaveFactor; |
| } |
| |
| // If we did not calculate the cost for VF (because the user selected the VF) |
| // then we calculate the cost of VF here. |
| if (LoopCost == 0) |
| LoopCost = expectedCost(VF); |
| |
| // Clamp the calculated IC to be between the 1 and the max interleave count |
| // that the target allows. |
| if (IC > MaxInterleaveCount) |
| IC = MaxInterleaveCount; |
| else if (IC < 1) |
| IC = 1; |
| |
| // Interleave if we vectorized this loop and there is a reduction that could |
| // benefit from interleaving. |
| if (VF > 1 && Legal->getReductionVars()->size()) { |
| DEBUG(dbgs() << "LV: Interleaving because of reductions.\n"); |
| return IC; |
| } |
| |
| // Note that if we've already vectorized the loop we will have done the |
| // runtime check and so interleaving won't require further checks. |
| bool InterleavingRequiresRuntimePointerCheck = |
| (VF == 1 && Legal->getRuntimePointerChecking()->Need); |
| |
| // We want to interleave small loops in order to reduce the loop overhead and |
| // potentially expose ILP opportunities. |
| DEBUG(dbgs() << "LV: Loop cost is " << LoopCost << '\n'); |
| if (!InterleavingRequiresRuntimePointerCheck && LoopCost < SmallLoopCost) { |
| // We assume that the cost overhead is 1 and we use the cost model |
| // to estimate the cost of the loop and interleave until the cost of the |
| // loop overhead is about 5% of the cost of the loop. |
| unsigned SmallIC = |
| std::min(IC, (unsigned)PowerOf2Floor(SmallLoopCost / LoopCost)); |
| |
| // Interleave until store/load ports (estimated by max interleave count) are |
| // saturated. |
| unsigned NumStores = Legal->getNumStores(); |
| unsigned NumLoads = Legal->getNumLoads(); |
| unsigned StoresIC = IC / (NumStores ? NumStores : 1); |
| unsigned LoadsIC = IC / (NumLoads ? NumLoads : 1); |
| |
| // If we have a scalar reduction (vector reductions are already dealt with |
| // by this point), we can increase the critical path length if the loop |
| // we're interleaving is inside another loop. Limit, by default to 2, so the |
| // critical path only gets increased by one reduction operation. |
| if (Legal->getReductionVars()->size() && |
| TheLoop->getLoopDepth() > 1) { |
| unsigned F = static_cast<unsigned>(MaxNestedScalarReductionIC); |
| SmallIC = std::min(SmallIC, F); |
| StoresIC = std::min(StoresIC, F); |
| LoadsIC = std::min(LoadsIC, F); |
| } |
| |
| if (EnableLoadStoreRuntimeInterleave && |
| std::max(StoresIC, LoadsIC) > SmallIC) { |
| DEBUG(dbgs() << "LV: Interleaving to saturate store or load ports.\n"); |
| return std::max(StoresIC, LoadsIC); |
| } |
| |
| DEBUG(dbgs() << "LV: Interleaving to reduce branch cost.\n"); |
| return SmallIC; |
| } |
| |
| // Interleave if this is a large loop (small loops are already dealt with by |
| // this |
| // point) that could benefit from interleaving. |
| bool HasReductions = (Legal->getReductionVars()->size() > 0); |
| if (TTI.enableAggressiveInterleaving(HasReductions)) { |
| DEBUG(dbgs() << "LV: Interleaving to expose ILP.\n"); |
| return IC; |
| } |
| |
| DEBUG(dbgs() << "LV: Not Interleaving.\n"); |
| return 1; |
| } |
| |
| LoopVectorizationCostModel::RegisterUsage |
| LoopVectorizationCostModel::calculateRegisterUsage() { |
| // This function calculates the register usage by measuring the highest number |
| // of values that are alive at a single location. Obviously, this is a very |
| // rough estimation. We scan the loop in a topological order in order and |
| // assign a number to each instruction. We use RPO to ensure that defs are |
| // met before their users. We assume that each instruction that has in-loop |
| // users starts an interval. We record every time that an in-loop value is |
| // used, so we have a list of the first and last occurrences of each |
| // instruction. Next, we transpose this data structure into a multi map that |
| // holds the list of intervals that *end* at a specific location. This multi |
| // map allows us to perform a linear search. We scan the instructions linearly |
| // and record each time that a new interval starts, by placing it in a set. |
| // If we find this value in the multi-map then we remove it from the set. |
| // The max register usage is the maximum size of the set. |
| // We also search for instructions that are defined outside the loop, but are |
| // used inside the loop. We need this number separately from the max-interval |
| // usage number because when we unroll, loop-invariant values do not take |
| // more register. |
| LoopBlocksDFS DFS(TheLoop); |
| DFS.perform(LI); |
| |
| RegisterUsage R; |
| R.NumInstructions = 0; |
| |
| // Each 'key' in the map opens a new interval. The values |
| // of the map are the index of the 'last seen' usage of the |
| // instruction that is the key. |
| typedef DenseMap<Instruction*, unsigned> IntervalMap; |
| // Maps instruction to its index. |
| DenseMap<unsigned, Instruction*> IdxToInstr; |
| // Marks the end of each interval. |
| IntervalMap EndPoint; |
| // Saves the list of instruction indices that are used in the loop. |
| SmallSet<Instruction*, 8> Ends; |
| // Saves the list of values that are used in the loop but are |
| // defined outside the loop, such as arguments and constants. |
| SmallPtrSet<Value*, 8> LoopInvariants; |
| |
| unsigned Index = 0; |
| for (LoopBlocksDFS::RPOIterator bb = DFS.beginRPO(), |
| be = DFS.endRPO(); bb != be; ++bb) { |
| R.NumInstructions += (*bb)->size(); |
| for (BasicBlock::iterator it = (*bb)->begin(), e = (*bb)->end(); it != e; |
| ++it) { |
| Instruction *I = it; |
| IdxToInstr[Index++] = I; |
| |
| // Save the end location of each USE. |
| for (unsigned i = 0; i < I->getNumOperands(); ++i) { |
| Value *U = I->getOperand(i); |
| Instruction *Instr = dyn_cast<Instruction>(U); |
| |
| // Ignore non-instruction values such as arguments, constants, etc. |
| if (!Instr) continue; |
| |
| // If this instruction is outside the loop then record it and continue. |
| if (!TheLoop->contains(Instr)) { |
| LoopInvariants.insert(Instr); |
| continue; |
| } |
| |
| // Overwrite previous end points. |
| EndPoint[Instr] = Index; |
| Ends.insert(Instr); |
| } |
| } |
| } |
| |
| // Saves the list of intervals that end with the index in 'key'. |
| typedef SmallVector<Instruction*, 2> InstrList; |
| DenseMap<unsigned, InstrList> TransposeEnds; |
| |
| // Transpose the EndPoints to a list of values that end at each index. |
| for (IntervalMap::iterator it = EndPoint.begin(), e = EndPoint.end(); |
| it != e; ++it) |
| TransposeEnds[it->second].push_back(it->first); |
| |
| SmallSet<Instruction*, 8> OpenIntervals; |
| unsigned MaxUsage = 0; |
| |
| |
| DEBUG(dbgs() << "LV(REG): Calculating max register usage:\n"); |
| for (unsigned int i = 0; i < Index; ++i) { |
| Instruction *I = IdxToInstr[i]; |
| // Ignore instructions that are never used within the loop. |
| if (!Ends.count(I)) continue; |
| |
| // Ignore ephemeral values. |
| if (EphValues.count(I)) |
| continue; |
| |
| // Remove all of the instructions that end at this location. |
| InstrList &List = TransposeEnds[i]; |
| for (unsigned int j=0, e = List.size(); j < e; ++j) |
| OpenIntervals.erase(List[j]); |
| |
| // Count the number of live interals. |
| MaxUsage = std::max(MaxUsage, OpenIntervals.size()); |
| |
| DEBUG(dbgs() << "LV(REG): At #" << i << " Interval # " << |
| OpenIntervals.size() << '\n'); |
| |
| // Add the current instruction to the list of open intervals. |
| OpenIntervals.insert(I); |
| } |
| |
| unsigned Invariant = LoopInvariants.size(); |
| DEBUG(dbgs() << "LV(REG): Found max usage: " << MaxUsage << '\n'); |
| DEBUG(dbgs() << "LV(REG): Found invariant usage: " << Invariant << '\n'); |
| DEBUG(dbgs() << "LV(REG): LoopSize: " << R.NumInstructions << '\n'); |
| |
| R.LoopInvariantRegs = Invariant; |
| R.MaxLocalUsers = MaxUsage; |
| return R; |
| } |
| |
| unsigned LoopVectorizationCostModel::expectedCost(unsigned VF) { |
| unsigned Cost = 0; |
| |
| // For each block. |
| for (Loop::block_iterator bb = TheLoop->block_begin(), |
| be = TheLoop->block_end(); bb != be; ++bb) { |
| unsigned BlockCost = 0; |
| BasicBlock *BB = *bb; |
| |
| // For each instruction in the old loop. |
| for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e; ++it) { |
| // Skip dbg intrinsics. |
| if (isa<DbgInfoIntrinsic>(it)) |
| continue; |
| |
| // Ignore ephemeral values. |
| if (EphValues.count(it)) |
| continue; |
| |
| unsigned C = getInstructionCost(it, VF); |
| |
| // Check if we should override the cost. |
| if (ForceTargetInstructionCost.getNumOccurrences() > 0) |
| C = ForceTargetInstructionCost; |
| |
| BlockCost += C; |
| DEBUG(dbgs() << "LV: Found an estimated cost of " << C << " for VF " << |
| VF << " For instruction: " << *it << '\n'); |
| } |
| |
| // We assume that if-converted blocks have a 50% chance of being executed. |
| // When the code is scalar then some of the blocks are avoided due to CF. |
| // When the code is vectorized we execute all code paths. |
| if (VF == 1 && Legal->blockNeedsPredication(*bb)) |
| BlockCost /= 2; |
| |
| Cost += BlockCost; |
| } |
| |
| return Cost; |
| } |
| |
| /// \brief Check whether the address computation for a non-consecutive memory |
| /// access looks like an unlikely candidate for being merged into the indexing |
| /// mode. |
| /// |
| /// We look for a GEP which has one index that is an induction variable and all |
| /// other indices are loop invariant. If the stride of this access is also |
| /// within a small bound we decide that this address computation can likely be |
| /// merged into the addressing mode. |
| /// In all other cases, we identify the address computation as complex. |
| static bool isLikelyComplexAddressComputation(Value *Ptr, |
| LoopVectorizationLegality *Legal, |
| ScalarEvolution *SE, |
| const Loop *TheLoop) { |
| GetElementPtrInst *Gep = dyn_cast<GetElementPtrInst>(Ptr); |
| if (!Gep) |
| return true; |
| |
| // We are looking for a gep with all loop invariant indices except for one |
| // which should be an induction variable. |
| unsigned NumOperands = Gep->getNumOperands(); |
| for (unsigned i = 1; i < NumOperands; ++i) { |
| Value *Opd = Gep->getOperand(i); |
| if (!SE->isLoopInvariant(SE->getSCEV(Opd), TheLoop) && |
| !Legal->isInductionVariable(Opd)) |
| return true; |
| } |
| |
| // Now we know we have a GEP ptr, %inv, %ind, %inv. Make sure that the step |
| // can likely be merged into the address computation. |
| unsigned MaxMergeDistance = 64; |
| |
| const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(SE->getSCEV(Ptr)); |
| if (!AddRec) |
| return true; |
| |
| // Check the step is constant. |
| const SCEV *Step = AddRec->getStepRecurrence(*SE); |
| // Calculate the pointer stride and check if it is consecutive. |
| const SCEVConstant *C = dyn_cast<SCEVConstant>(Step); |
| if (!C) |
| return true; |
| |
| const APInt &APStepVal = C->getValue()->getValue(); |
| |
| // Huge step value - give up. |
| if (APStepVal.getBitWidth() > 64) |
| return true; |
| |
| int64_t StepVal = APStepVal.getSExtValue(); |
| |
| return StepVal > MaxMergeDistance; |
| } |
| |
| static bool isStrideMul(Instruction *I, LoopVectorizationLegality *Legal) { |
| if (Legal->hasStride(I->getOperand(0)) || Legal->hasStride(I->getOperand(1))) |
| return true; |
| return false; |
| } |
| |
| unsigned |
| LoopVectorizationCostModel::getInstructionCost(Instruction *I, unsigned VF) { |
| // If we know that this instruction will remain uniform, check the cost of |
| // the scalar version. |
| if (Legal->isUniformAfterVectorization(I)) |
| VF = 1; |
| |
| Type *RetTy = I->getType(); |
| Type *VectorTy = ToVectorTy(RetTy, VF); |
| |
| // TODO: We need to estimate the cost of intrinsic calls. |
| switch (I->getOpcode()) { |
| case Instruction::GetElementPtr: |
| // We mark this instruction as zero-cost because the cost of GEPs in |
| // vectorized code depends on whether the corresponding memory instruction |
| // is scalarized or not. Therefore, we handle GEPs with the memory |
| // instruction cost. |
| return 0; |
| case Instruction::Br: { |
| return TTI.getCFInstrCost(I->getOpcode()); |
| } |
| case Instruction::PHI: |
| //TODO: IF-converted IFs become selects. |
| return 0; |
| case Instruction::Add: |
| case Instruction::FAdd: |
| case Instruction::Sub: |
| case Instruction::FSub: |
| case Instruction::Mul: |
| case Instruction::FMul: |
| case Instruction::UDiv: |
| case Instruction::SDiv: |
| case Instruction::FDiv: |
| case Instruction::URem: |
| case Instruction::SRem: |
| case Instruction::FRem: |
| case Instruction::Shl: |
| case Instruction::LShr: |
| case Instruction::AShr: |
| case Instruction::And: |
| case Instruction::Or: |
| case Instruction::Xor: { |
| // Since we will replace the stride by 1 the multiplication should go away. |
| if (I->getOpcode() == Instruction::Mul && isStrideMul(I, Legal)) |
| return 0; |
| // Certain instructions can be cheaper to vectorize if they have a constant |
| // second vector operand. One example of this are shifts on x86. |
| TargetTransformInfo::OperandValueKind Op1VK = |
| TargetTransformInfo::OK_AnyValue; |
| TargetTransformInfo::OperandValueKind Op2VK = |
| TargetTransformInfo::OK_AnyValue; |
| TargetTransformInfo::OperandValueProperties Op1VP = |
| TargetTransformInfo::OP_None; |
| TargetTransformInfo::OperandValueProperties Op2VP = |
| TargetTransformInfo::OP_None; |
| Value *Op2 = I->getOperand(1); |
| |
| // Check for a splat of a constant or for a non uniform vector of constants. |
| if (isa<ConstantInt>(Op2)) { |
| ConstantInt *CInt = cast<ConstantInt>(Op2); |
| if (CInt && CInt->getValue().isPowerOf2()) |
| Op2VP = TargetTransformInfo::OP_PowerOf2; |
| Op2VK = TargetTransformInfo::OK_UniformConstantValue; |
| } else if (isa<ConstantVector>(Op2) || isa<ConstantDataVector>(Op2)) { |
| Op2VK = TargetTransformInfo::OK_NonUniformConstantValue; |
| Constant *SplatValue = cast<Constant>(Op2)->getSplatValue(); |
| if (SplatValue) { |
| ConstantInt *CInt = dyn_cast<ConstantInt>(SplatValue); |
| if (CInt && CInt->getValue().isPowerOf2()) |
| Op2VP = TargetTransformInfo::OP_PowerOf2; |
| Op2VK = TargetTransformInfo::OK_UniformConstantValue; |
| } |
| } |
| |
| return TTI.getArithmeticInstrCost(I->getOpcode(), VectorTy, Op1VK, Op2VK, |
| Op1VP, Op2VP); |
| } |
| case Instruction::Select: { |
| SelectInst *SI = cast<SelectInst>(I); |
| const SCEV *CondSCEV = SE->getSCEV(SI->getCondition()); |
| bool ScalarCond = (SE->isLoopInvariant(CondSCEV, TheLoop)); |
| Type *CondTy = SI->getCondition()->getType(); |
| if (!ScalarCond) |
| CondTy = VectorType::get(CondTy, VF); |
| |
| return TTI.getCmpSelInstrCost(I->getOpcode(), VectorTy, CondTy); |
| } |
| case Instruction::ICmp: |
| case Instruction::FCmp: { |
| Type *ValTy = I->getOperand(0)->getType(); |
| VectorTy = ToVectorTy(ValTy, VF); |
| return TTI.getCmpSelInstrCost(I->getOpcode(), VectorTy); |
| } |
| case Instruction::Store: |
| case Instruction::Load: { |
| StoreInst *SI = dyn_cast<StoreInst>(I); |
| LoadInst *LI = dyn_cast<LoadInst>(I); |
| Type *ValTy = (SI ? SI->getValueOperand()->getType() : |
| LI->getType()); |
| VectorTy = ToVectorTy(ValTy, VF); |
| |
| unsigned Alignment = SI ? SI->getAlignment() : LI->getAlignment(); |
| unsigned AS = SI ? SI->getPointerAddressSpace() : |
| LI->getPointerAddressSpace(); |
| Value *Ptr = SI ? SI->getPointerOperand() : LI->getPointerOperand(); |
| // We add the cost of address computation here instead of with the gep |
| // instruction because only here we know whether the operation is |
| // scalarized. |
| if (VF == 1) |
| return TTI.getAddressComputationCost(VectorTy) + |
| TTI.getMemoryOpCost(I->getOpcode(), VectorTy, Alignment, AS); |
| |
| // For an interleaved access, calculate the total cost of the whole |
| // interleave group. |
| if (Legal->isAccessInterleaved(I)) { |
| auto Group = Legal->getInterleavedAccessGroup(I); |
| assert(Group && "Fail to get an interleaved access group."); |
| |
| // Only calculate the cost once at the insert position. |
| if (Group->getInsertPos() != I) |
| return 0; |
| |
| unsigned InterleaveFactor = Group->getFactor(); |
| Type *WideVecTy = |
| VectorType::get(VectorTy->getVectorElementType(), |
| VectorTy->getVectorNumElements() * InterleaveFactor); |
| |
| // Holds the indices of existing members in an interleaved load group. |
| // An interleaved store group doesn't need this as it dones't allow gaps. |
| SmallVector<unsigned, 4> Indices; |
| if (LI) { |
| for (unsigned i = 0; i < InterleaveFactor; i++) |
| if (Group->getMember(i)) |
| Indices.push_back(i); |
| } |
| |
| // Calculate the cost of the whole interleaved group. |
| unsigned Cost = TTI.getInterleavedMemoryOpCost( |
| I->getOpcode(), WideVecTy, Group->getFactor(), Indices, |
| Group->getAlignment(), AS); |
| |
| if (Group->isReverse()) |
| Cost += |
| Group->getNumMembers() * |
| TTI.getShuffleCost(TargetTransformInfo::SK_Reverse, VectorTy, 0); |
| |
| // FIXME: The interleaved load group with a huge gap could be even more |
| // expensive than scalar operations. Then we could ignore such group and |
| // use scalar operations instead. |
| return Cost; |
| } |
| |
| // Scalarized loads/stores. |
| int ConsecutiveStride = Legal->isConsecutivePtr(Ptr); |
| bool Reverse = ConsecutiveStride < 0; |
| const DataLayout &DL = I->getModule()->getDataLayout(); |
| unsigned ScalarAllocatedSize = DL.getTypeAllocSize(ValTy); |
| unsigned VectorElementSize = DL.getTypeStoreSize(VectorTy) / VF; |
| if (!ConsecutiveStride || ScalarAllocatedSize != VectorElementSize) { |
| bool IsComplexComputation = |
| isLikelyComplexAddressComputation(Ptr, Legal, SE, TheLoop); |
| unsigned Cost = 0; |
| // The cost of extracting from the value vector and pointer vector. |
| Type *PtrTy = ToVectorTy(Ptr->getType(), VF); |
| for (unsigned i = 0; i < VF; ++i) { |
| // The cost of extracting the pointer operand. |
| Cost += TTI.getVectorInstrCost(Instruction::ExtractElement, PtrTy, i); |
| // In case of STORE, the cost of ExtractElement from the vector. |
| // In case of LOAD, the cost of InsertElement into the returned |
| // vector. |
| Cost += TTI.getVectorInstrCost(SI ? Instruction::ExtractElement : |
| Instruction::InsertElement, |
| VectorTy, i); |
| } |
| |
| // The cost of the scalar loads/stores. |
| Cost += VF * TTI.getAddressComputationCost(PtrTy, IsComplexComputation); |
| Cost += VF * TTI.getMemoryOpCost(I->getOpcode(), ValTy->getScalarType(), |
| Alignment, AS); |
| return Cost; |
| } |
| |
| // Wide load/stores. |
| unsigned Cost = TTI.getAddressComputationCost(VectorTy); |
| if (Legal->isMaskRequired(I)) |
| Cost += TTI.getMaskedMemoryOpCost(I->getOpcode(), VectorTy, Alignment, |
| AS); |
| else |
| Cost += TTI.getMemoryOpCost(I->getOpcode(), VectorTy, Alignment, AS); |
| |
| if (Reverse) |
| Cost += TTI.getShuffleCost(TargetTransformInfo::SK_Reverse, |
| VectorTy, 0); |
| return Cost; |
| } |
| case Instruction::ZExt: |
| case Instruction::SExt: |
| case Instruction::FPToUI: |
| case Instruction::FPToSI: |
| case Instruction::FPExt: |
| case Instruction::PtrToInt: |
| case Instruction::IntToPtr: |
| case Instruction::SIToFP: |
| case Instruction::UIToFP: |
| case Instruction::Trunc: |
| case Instruction::FPTrunc: |
| case Instruction::BitCast: { |
| // We optimize the truncation of induction variable. |
| // The cost of these is the same as the scalar operation. |
| if (I->getOpcode() == Instruction::Trunc && |
| Legal->isInductionVariable(I->getOperand(0))) |
| return TTI.getCastInstrCost(I->getOpcode(), I->getType(), |
| I->getOperand(0)->getType()); |
| |
| Type *SrcVecTy = ToVectorTy(I->getOperand(0)->getType(), VF); |
| return TTI.getCastInstrCost(I->getOpcode(), VectorTy, SrcVecTy); |
| } |
| case Instruction::Call: { |
| bool NeedToScalarize; |
| CallInst *CI = cast<CallInst>(I); |
| unsigned CallCost = getVectorCallCost(CI, VF, TTI, TLI, NeedToScalarize); |
| if (getIntrinsicIDForCall(CI, TLI)) |
| return std::min(CallCost, getVectorIntrinsicCost(CI, VF, TTI, TLI)); |
| return CallCost; |
| } |
| default: { |
| // We are scalarizing the instruction. Return the cost of the scalar |
| // instruction, plus the cost of insert and extract into vector |
| // elements, times the vector width. |
| unsigned Cost = 0; |
| |
| if (!RetTy->isVoidTy() && VF != 1) { |
| unsigned InsCost = TTI.getVectorInstrCost(Instruction::InsertElement, |
| VectorTy); |
| unsigned ExtCost = TTI.getVectorInstrCost(Instruction::ExtractElement, |
| VectorTy); |
| |
| // The cost of inserting the results plus extracting each one of the |
| // operands. |
| Cost += VF * (InsCost + ExtCost * I->getNumOperands()); |
| } |
| |
| // The cost of executing VF copies of the scalar instruction. This opcode |
| // is unknown. Assume that it is the same as 'mul'. |
| Cost += VF * TTI.getArithmeticInstrCost(Instruction::Mul, VectorTy); |
| return Cost; |
| } |
| }// end of switch. |
| } |
| |
| char LoopVectorize::ID = 0; |
| static const char lv_name[] = "Loop Vectorization"; |
| INITIALIZE_PASS_BEGIN(LoopVectorize, LV_NAME, lv_name, false, false) |
| INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass) |
| INITIALIZE_AG_DEPENDENCY(AliasAnalysis) |
| INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker) |
| INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfo) |
| INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass) |
| INITIALIZE_PASS_DEPENDENCY(ScalarEvolution) |
| INITIALIZE_PASS_DEPENDENCY(LCSSA) |
| INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass) |
| INITIALIZE_PASS_DEPENDENCY(LoopSimplify) |
| INITIALIZE_PASS_DEPENDENCY(LoopAccessAnalysis) |
| INITIALIZE_PASS_END(LoopVectorize, LV_NAME, lv_name, false, false) |
| |
| namespace llvm { |
| Pass *createLoopVectorizePass(bool NoUnrolling, bool AlwaysVectorize) { |
| return new LoopVectorize(NoUnrolling, AlwaysVectorize); |
| } |
| } |
| |
| bool LoopVectorizationCostModel::isConsecutiveLoadOrStore(Instruction *Inst) { |
| // Check for a store. |
| if (StoreInst *ST = dyn_cast<StoreInst>(Inst)) |
| return Legal->isConsecutivePtr(ST->getPointerOperand()) != 0; |
| |
| // Check for a load. |
| if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) |
| return Legal->isConsecutivePtr(LI->getPointerOperand()) != 0; |
| |
| return false; |
| } |
| |
| |
| void InnerLoopUnroller::scalarizeInstruction(Instruction *Instr, |
| bool IfPredicateStore) { |
| assert(!Instr->getType()->isAggregateType() && "Can't handle vectors"); |
| // Holds vector parameters or scalars, in case of uniform vals. |
| SmallVector<VectorParts, 4> Params; |
| |
| setDebugLocFromInst(Builder, Instr); |
| |
| // Find all of the vectorized parameters. |
| for (unsigned op = 0, e = Instr->getNumOperands(); op != e; ++op) { |
| Value *SrcOp = Instr->getOperand(op); |
| |
| // If we are accessing the old induction variable, use the new one. |
| if (SrcOp == OldInduction) { |
| Params.push_back(getVectorValue(SrcOp)); |
| continue; |
| } |
| |
| // Try using previously calculated values. |
| Instruction *SrcInst = dyn_cast<Instruction>(SrcOp); |
| |
| // If the src is an instruction that appeared earlier in the basic block |
| // then it should already be vectorized. |
| if (SrcInst && OrigLoop->contains(SrcInst)) { |
| assert(WidenMap.has(SrcInst) && "Source operand is unavailable"); |
| // The parameter is a vector value from earlier. |
| Params.push_back(WidenMap.get(SrcInst)); |
| } else { |
| // The parameter is a scalar from outside the loop. Maybe even a constant. |
| VectorParts Scalars; |
| Scalars.append(UF, SrcOp); |
| Params.push_back(Scalars); |
| } |
| } |
| |
| assert(Params.size() == Instr->getNumOperands() && |
| "Invalid number of operands"); |
| |
| // Does this instruction return a value ? |
| bool IsVoidRetTy = Instr->getType()->isVoidTy(); |
| |
| Value *UndefVec = IsVoidRetTy ? nullptr : |
| UndefValue::get(Instr->getType()); |
| // Create a new entry in the WidenMap and initialize it to Undef or Null. |
| VectorParts &VecResults = WidenMap.splat(Instr, UndefVec); |
| |
| Instruction *InsertPt = Builder.GetInsertPoint(); |
| BasicBlock *IfBlock = Builder.GetInsertBlock(); |
| BasicBlock *CondBlock = nullptr; |
| |
| VectorParts Cond; |
| Loop *VectorLp = nullptr; |
| if (IfPredicateStore) { |
| assert(Instr->getParent()->getSinglePredecessor() && |
| "Only support single predecessor blocks"); |
| Cond = createEdgeMask(Instr->getParent()->getSinglePredecessor(), |
| Instr->getParent()); |
| VectorLp = LI->getLoopFor(IfBlock); |
| assert(VectorLp && "Must have a loop for this block"); |
| } |
| |
| // For each vector unroll 'part': |
| for (unsigned Part = 0; Part < UF; ++Part) { |
| // For each scalar that we create: |
| |
| // Start an "if (pred) a[i] = ..." block. |
| Value *Cmp = nullptr; |
| if (IfPredicateStore) { |
| if (Cond[Part]->getType()->isVectorTy()) |
| Cond[Part] = |
| Builder.CreateExtractElement(Cond[Part], Builder.getInt32(0)); |
| Cmp = Builder.CreateICmp(ICmpInst::ICMP_EQ, Cond[Part], |
| ConstantInt::get(Cond[Part]->getType(), 1)); |
| CondBlock = IfBlock->splitBasicBlock(InsertPt, "cond.store"); |
| LoopVectorBody.push_back(CondBlock); |
| VectorLp->addBasicBlockToLoop(CondBlock, *LI); |
| // Update Builder with newly created basic block. |
| Builder.SetInsertPoint(InsertPt); |
| } |
| |
| Instruction *Cloned = Instr->clone(); |
| if (!IsVoidRetTy) |
| Cloned->setName(Instr->getName() + ".cloned"); |
| // Replace the operands of the cloned instructions with extracted scalars. |
| for (unsigned op = 0, e = Instr->getNumOperands(); op != e; ++op) { |
| Value *Op = Params[op][Part]; |
| Cloned->setOperand(op, Op); |
| } |
| |
| // Place the cloned scalar in the new loop. |
| Builder.Insert(Cloned); |
| |
| // If the original scalar returns a value we need to place it in a vector |
| // so that future users will be able to use it. |
| if (!IsVoidRetTy) |
| VecResults[Part] = Cloned; |
| |
| // End if-block. |
| if (IfPredicateStore) { |
| BasicBlock *NewIfBlock = CondBlock->splitBasicBlock(InsertPt, "else"); |
| LoopVectorBody.push_back(NewIfBlock); |
| VectorLp->addBasicBlockToLoop(NewIfBlock, *LI); |
| Builder.SetInsertPoint(InsertPt); |
| ReplaceInstWithInst(IfBlock->getTerminator(), |
| BranchInst::Create(CondBlock, NewIfBlock, Cmp)); |
| IfBlock = NewIfBlock; |
| } |
| } |
| } |
| |
| void InnerLoopUnroller::vectorizeMemoryInstruction(Instruction *Instr) { |
| StoreInst *SI = dyn_cast<StoreInst>(Instr); |
| bool IfPredicateStore = (SI && Legal->blockNeedsPredication(SI->getParent())); |
| |
| return scalarizeInstruction(Instr, IfPredicateStore); |
| } |
| |
| Value *InnerLoopUnroller::reverseVector(Value *Vec) { |
| return Vec; |
| } |
| |
| Value *InnerLoopUnroller::getBroadcastInstrs(Value *V) { |
| return V; |
| } |
| |
| Value *InnerLoopUnroller::getStepVector(Value *Val, int StartIdx, Value *Step) { |
| // When unrolling and the VF is 1, we only need to add a simple scalar. |
| Type *ITy = Val->getType(); |
| assert(!ITy->isVectorTy() && "Val must be a scalar"); |
| Constant *C = ConstantInt::get(ITy, StartIdx); |
| return Builder.CreateAdd(Val, Builder.CreateMul(C, Step), "induction"); |
| } |