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+//===- llvm/Analysis/LoopAccessAnalysis.h -----------------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the interface for the loop memory dependence framework that
+// was originally developed for the Loop Vectorizer.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ANALYSIS_LOOPACCESSANALYSIS_H
+#define LLVM_ANALYSIS_LOOPACCESSANALYSIS_H
+
+#include "llvm/ADT/EquivalenceClasses.h"
+#include "llvm/ADT/Optional.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/AliasSetTracker.h"
+#include "llvm/Analysis/LoopAnalysisManager.h"
+#include "llvm/Analysis/ScalarEvolutionExpressions.h"
+#include "llvm/IR/DiagnosticInfo.h"
+#include "llvm/IR/ValueHandle.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/raw_ostream.h"
+
+namespace llvm {
+
+class Value;
+class DataLayout;
+class ScalarEvolution;
+class Loop;
+class SCEV;
+class SCEVUnionPredicate;
+class LoopAccessInfo;
+class OptimizationRemarkEmitter;
+
+/// \brief Collection of parameters shared beetween the Loop Vectorizer and the
+/// Loop Access Analysis.
+struct VectorizerParams {
+ /// \brief Maximum SIMD width.
+ static const unsigned MaxVectorWidth;
+
+ /// \brief VF as overridden by the user.
+ static unsigned VectorizationFactor;
+ /// \brief Interleave factor as overridden by the user.
+ static unsigned VectorizationInterleave;
+ /// \brief True if force-vector-interleave was specified by the user.
+ static bool isInterleaveForced();
+
+ /// \\brief When performing memory disambiguation checks at runtime do not
+ /// make more than this number of comparisons.
+ static unsigned RuntimeMemoryCheckThreshold;
+};
+
+/// \brief Checks memory dependences among accesses to the same underlying
+/// object to determine whether there vectorization is legal or not (and at
+/// which vectorization factor).
+///
+/// Note: This class will compute a conservative dependence for access to
+/// different underlying pointers. Clients, such as the loop vectorizer, will
+/// sometimes deal these potential dependencies by emitting runtime checks.
+///
+/// We use the ScalarEvolution framework to symbolically evalutate access
+/// functions pairs. Since we currently don't restructure the loop we can rely
+/// on the program order of memory accesses to determine their safety.
+/// At the moment we will only deem accesses as safe for:
+/// * A negative constant distance assuming program order.
+///
+/// Safe: tmp = a[i + 1]; OR a[i + 1] = x;
+/// a[i] = tmp; y = a[i];
+///
+/// The latter case is safe because later checks guarantuee that there can't
+/// be a cycle through a phi node (that is, we check that "x" and "y" is not
+/// the same variable: a header phi can only be an induction or a reduction, a
+/// reduction can't have a memory sink, an induction can't have a memory
+/// source). This is important and must not be violated (or we have to
+/// resort to checking for cycles through memory).
+///
+/// * A positive constant distance assuming program order that is bigger
+/// than the biggest memory access.
+///
+/// tmp = a[i] OR b[i] = x
+/// a[i+2] = tmp y = b[i+2];
+///
+/// Safe distance: 2 x sizeof(a[0]), and 2 x sizeof(b[0]), respectively.
+///
+/// * Zero distances and all accesses have the same size.
+///
+class MemoryDepChecker {
+public:
+ typedef PointerIntPair<Value *, 1, bool> MemAccessInfo;
+ typedef SmallVector<MemAccessInfo, 8> MemAccessInfoList;
+ /// \brief Set of potential dependent memory accesses.
+ typedef EquivalenceClasses<MemAccessInfo> DepCandidates;
+
+ /// \brief Dependece between memory access instructions.
+ struct Dependence {
+ /// \brief The type of the dependence.
+ enum DepType {
+ // No dependence.
+ NoDep,
+ // We couldn't determine the direction or the distance.
+ Unknown,
+ // Lexically forward.
+ //
+ // FIXME: If we only have loop-independent forward dependences (e.g. a
+ // read and write of A[i]), LAA will locally deem the dependence "safe"
+ // without querying the MemoryDepChecker. Therefore we can miss
+ // enumerating loop-independent forward dependences in
+ // getDependences. Note that as soon as there are different
+ // indices used to access the same array, the MemoryDepChecker *is*
+ // queried and the dependence list is complete.
+ Forward,
+ // Forward, but if vectorized, is likely to prevent store-to-load
+ // forwarding.
+ ForwardButPreventsForwarding,
+ // Lexically backward.
+ Backward,
+ // Backward, but the distance allows a vectorization factor of
+ // MaxSafeDepDistBytes.
+ BackwardVectorizable,
+ // Same, but may prevent store-to-load forwarding.
+ BackwardVectorizableButPreventsForwarding
+ };
+
+ /// \brief String version of the types.
+ static const char *DepName[];
+
+ /// \brief Index of the source of the dependence in the InstMap vector.
+ unsigned Source;
+ /// \brief Index of the destination of the dependence in the InstMap vector.
+ unsigned Destination;
+ /// \brief The type of the dependence.
+ DepType Type;
+
+ Dependence(unsigned Source, unsigned Destination, DepType Type)
+ : Source(Source), Destination(Destination), Type(Type) {}
+
+ /// \brief Return the source instruction of the dependence.
+ Instruction *getSource(const LoopAccessInfo &LAI) const;
+ /// \brief Return the destination instruction of the dependence.
+ Instruction *getDestination(const LoopAccessInfo &LAI) const;
+
+ /// \brief Dependence types that don't prevent vectorization.
+ static bool isSafeForVectorization(DepType Type);
+
+ /// \brief Lexically forward dependence.
+ bool isForward() const;
+ /// \brief Lexically backward dependence.
+ bool isBackward() const;
+
+ /// \brief May be a lexically backward dependence type (includes Unknown).
+ bool isPossiblyBackward() const;
+
+ /// \brief Print the dependence. \p Instr is used to map the instruction
+ /// indices to instructions.
+ void print(raw_ostream &OS, unsigned Depth,
+ const SmallVectorImpl<Instruction *> &Instrs) const;
+ };
+
+ MemoryDepChecker(PredicatedScalarEvolution &PSE, const Loop *L)
+ : PSE(PSE), InnermostLoop(L), AccessIdx(0), MaxSafeRegisterWidth(-1U),
+ ShouldRetryWithRuntimeCheck(false), SafeForVectorization(true),
+ RecordDependences(true) {}
+
+ /// \brief Register the location (instructions are given increasing numbers)
+ /// of a write access.
+ void addAccess(StoreInst *SI) {
+ Value *Ptr = SI->getPointerOperand();
+ Accesses[MemAccessInfo(Ptr, true)].push_back(AccessIdx);
+ InstMap.push_back(SI);
+ ++AccessIdx;
+ }
+
+ /// \brief Register the location (instructions are given increasing numbers)
+ /// of a write access.
+ void addAccess(LoadInst *LI) {
+ Value *Ptr = LI->getPointerOperand();
+ Accesses[MemAccessInfo(Ptr, false)].push_back(AccessIdx);
+ InstMap.push_back(LI);
+ ++AccessIdx;
+ }
+
+ /// \brief Check whether the dependencies between the accesses are safe.
+ ///
+ /// Only checks sets with elements in \p CheckDeps.
+ bool areDepsSafe(DepCandidates &AccessSets, MemAccessInfoList &CheckDeps,
+ const ValueToValueMap &Strides);
+
+ /// \brief No memory dependence was encountered that would inhibit
+ /// vectorization.
+ bool isSafeForVectorization() const { return SafeForVectorization; }
+
+ /// \brief The maximum number of bytes of a vector register we can vectorize
+ /// the accesses safely with.
+ uint64_t getMaxSafeDepDistBytes() { return MaxSafeDepDistBytes; }
+
+ /// \brief Return the number of elements that are safe to operate on
+ /// simultaneously, multiplied by the size of the element in bits.
+ uint64_t getMaxSafeRegisterWidth() const { return MaxSafeRegisterWidth; }
+
+ /// \brief In same cases when the dependency check fails we can still
+ /// vectorize the loop with a dynamic array access check.
+ bool shouldRetryWithRuntimeCheck() { return ShouldRetryWithRuntimeCheck; }
+
+ /// \brief Returns the memory dependences. If null is returned we exceeded
+ /// the MaxDependences threshold and this information is not
+ /// available.
+ const SmallVectorImpl<Dependence> *getDependences() const {
+ return RecordDependences ? &Dependences : nullptr;
+ }
+
+ void clearDependences() { Dependences.clear(); }
+
+ /// \brief The vector of memory access instructions. The indices are used as
+ /// instruction identifiers in the Dependence class.
+ const SmallVectorImpl<Instruction *> &getMemoryInstructions() const {
+ return InstMap;
+ }
+
+ /// \brief Generate a mapping between the memory instructions and their
+ /// indices according to program order.
+ DenseMap<Instruction *, unsigned> generateInstructionOrderMap() const {
+ DenseMap<Instruction *, unsigned> OrderMap;
+
+ for (unsigned I = 0; I < InstMap.size(); ++I)
+ OrderMap[InstMap[I]] = I;
+
+ return OrderMap;
+ }
+
+ /// \brief Find the set of instructions that read or write via \p Ptr.
+ SmallVector<Instruction *, 4> getInstructionsForAccess(Value *Ptr,
+ bool isWrite) const;
+
+private:
+ /// A wrapper around ScalarEvolution, used to add runtime SCEV checks, and
+ /// applies dynamic knowledge to simplify SCEV expressions and convert them
+ /// to a more usable form. We need this in case assumptions about SCEV
+ /// expressions need to be made in order to avoid unknown dependences. For
+ /// example we might assume a unit stride for a pointer in order to prove
+ /// that a memory access is strided and doesn't wrap.
+ PredicatedScalarEvolution &PSE;
+ const Loop *InnermostLoop;
+
+ /// \brief Maps access locations (ptr, read/write) to program order.
+ DenseMap<MemAccessInfo, std::vector<unsigned> > Accesses;
+
+ /// \brief Memory access instructions in program order.
+ SmallVector<Instruction *, 16> InstMap;
+
+ /// \brief The program order index to be used for the next instruction.
+ unsigned AccessIdx;
+
+ // We can access this many bytes in parallel safely.
+ uint64_t MaxSafeDepDistBytes;
+
+ /// \brief Number of elements (from consecutive iterations) that are safe to
+ /// operate on simultaneously, multiplied by the size of the element in bits.
+ /// The size of the element is taken from the memory access that is most
+ /// restrictive.
+ uint64_t MaxSafeRegisterWidth;
+
+ /// \brief If we see a non-constant dependence distance we can still try to
+ /// vectorize this loop with runtime checks.
+ bool ShouldRetryWithRuntimeCheck;
+
+ /// \brief No memory dependence was encountered that would inhibit
+ /// vectorization.
+ bool SafeForVectorization;
+
+ //// \brief True if Dependences reflects the dependences in the
+ //// loop. If false we exceeded MaxDependences and
+ //// Dependences is invalid.
+ bool RecordDependences;
+
+ /// \brief Memory dependences collected during the analysis. Only valid if
+ /// RecordDependences is true.
+ SmallVector<Dependence, 8> Dependences;
+
+ /// \brief Check whether there is a plausible dependence between the two
+ /// accesses.
+ ///
+ /// Access \p A must happen before \p B in program order. The two indices
+ /// identify the index into the program order map.
+ ///
+ /// This function checks whether there is a plausible dependence (or the
+ /// absence of such can't be proved) between the two accesses. If there is a
+ /// plausible dependence but the dependence distance is bigger than one
+ /// element access it records this distance in \p MaxSafeDepDistBytes (if this
+ /// distance is smaller than any other distance encountered so far).
+ /// Otherwise, this function returns true signaling a possible dependence.
+ Dependence::DepType isDependent(const MemAccessInfo &A, unsigned AIdx,
+ const MemAccessInfo &B, unsigned BIdx,
+ const ValueToValueMap &Strides);
+
+ /// \brief Check whether the data dependence could prevent store-load
+ /// forwarding.
+ ///
+ /// \return false if we shouldn't vectorize at all or avoid larger
+ /// vectorization factors by limiting MaxSafeDepDistBytes.
+ bool couldPreventStoreLoadForward(uint64_t Distance, uint64_t TypeByteSize);
+};
+
+/// \brief Holds information about the memory runtime legality checks to verify
+/// that a group of pointers do not overlap.
+class RuntimePointerChecking {
+public:
+ struct PointerInfo {
+ /// Holds the pointer value that we need to check.
+ TrackingVH<Value> PointerValue;
+ /// Holds the smallest byte address accessed by the pointer throughout all
+ /// iterations of the loop.
+ const SCEV *Start;
+ /// Holds the largest byte address accessed by the pointer throughout all
+ /// iterations of the loop, plus 1.
+ const SCEV *End;
+ /// Holds the information if this pointer is used for writing to memory.
+ bool IsWritePtr;
+ /// Holds the id of the set of pointers that could be dependent because of a
+ /// shared underlying object.
+ unsigned DependencySetId;
+ /// Holds the id of the disjoint alias set to which this pointer belongs.
+ unsigned AliasSetId;
+ /// SCEV for the access.
+ const SCEV *Expr;
+
+ PointerInfo(Value *PointerValue, const SCEV *Start, const SCEV *End,
+ bool IsWritePtr, unsigned DependencySetId, unsigned AliasSetId,
+ const SCEV *Expr)
+ : PointerValue(PointerValue), Start(Start), End(End),
+ IsWritePtr(IsWritePtr), DependencySetId(DependencySetId),
+ AliasSetId(AliasSetId), Expr(Expr) {}
+ };
+
+ RuntimePointerChecking(ScalarEvolution *SE) : Need(false), SE(SE) {}
+
+ /// Reset the state of the pointer runtime information.
+ void reset() {
+ Need = false;
+ Pointers.clear();
+ Checks.clear();
+ }
+
+ /// Insert a pointer and calculate the start and end SCEVs.
+ /// We need \p PSE in order to compute the SCEV expression of the pointer
+ /// according to the assumptions that we've made during the analysis.
+ /// The method might also version the pointer stride according to \p Strides,
+ /// and add new predicates to \p PSE.
+ void insert(Loop *Lp, Value *Ptr, bool WritePtr, unsigned DepSetId,
+ unsigned ASId, const ValueToValueMap &Strides,
+ PredicatedScalarEvolution &PSE);
+
+ /// \brief No run-time memory checking is necessary.
+ bool empty() const { return Pointers.empty(); }
+
+ /// A grouping of pointers. A single memcheck is required between
+ /// two groups.
+ struct CheckingPtrGroup {
+ /// \brief Create a new pointer checking group containing a single
+ /// pointer, with index \p Index in RtCheck.
+ CheckingPtrGroup(unsigned Index, RuntimePointerChecking &RtCheck)
+ : RtCheck(RtCheck), High(RtCheck.Pointers[Index].End),
+ Low(RtCheck.Pointers[Index].Start) {
+ Members.push_back(Index);
+ }
+
+ /// \brief Tries to add the pointer recorded in RtCheck at index
+ /// \p Index to this pointer checking group. We can only add a pointer
+ /// to a checking group if we will still be able to get
+ /// the upper and lower bounds of the check. Returns true in case
+ /// of success, false otherwise.
+ bool addPointer(unsigned Index);
+
+ /// Constitutes the context of this pointer checking group. For each
+ /// pointer that is a member of this group we will retain the index
+ /// at which it appears in RtCheck.
+ RuntimePointerChecking &RtCheck;
+ /// The SCEV expression which represents the upper bound of all the
+ /// pointers in this group.
+ const SCEV *High;
+ /// The SCEV expression which represents the lower bound of all the
+ /// pointers in this group.
+ const SCEV *Low;
+ /// Indices of all the pointers that constitute this grouping.
+ SmallVector<unsigned, 2> Members;
+ };
+
+ /// \brief A memcheck which made up of a pair of grouped pointers.
+ ///
+ /// These *have* to be const for now, since checks are generated from
+ /// CheckingPtrGroups in LAI::addRuntimeChecks which is a const member
+ /// function. FIXME: once check-generation is moved inside this class (after
+ /// the PtrPartition hack is removed), we could drop const.
+ typedef std::pair<const CheckingPtrGroup *, const CheckingPtrGroup *>
+ PointerCheck;
+
+ /// \brief Generate the checks and store it. This also performs the grouping
+ /// of pointers to reduce the number of memchecks necessary.
+ void generateChecks(MemoryDepChecker::DepCandidates &DepCands,
+ bool UseDependencies);
+
+ /// \brief Returns the checks that generateChecks created.
+ const SmallVector<PointerCheck, 4> &getChecks() const { return Checks; }
+
+ /// \brief Decide if we need to add a check between two groups of pointers,
+ /// according to needsChecking.
+ bool needsChecking(const CheckingPtrGroup &M,
+ const CheckingPtrGroup &N) const;
+
+ /// \brief Returns the number of run-time checks required according to
+ /// needsChecking.
+ unsigned getNumberOfChecks() const { return Checks.size(); }
+
+ /// \brief Print the list run-time memory checks necessary.
+ void print(raw_ostream &OS, unsigned Depth = 0) const;
+
+ /// Print \p Checks.
+ void printChecks(raw_ostream &OS, const SmallVectorImpl<PointerCheck> &Checks,
+ unsigned Depth = 0) const;
+
+ /// This flag indicates if we need to add the runtime check.
+ bool Need;
+
+ /// Information about the pointers that may require checking.
+ SmallVector<PointerInfo, 2> Pointers;
+
+ /// Holds a partitioning of pointers into "check groups".
+ SmallVector<CheckingPtrGroup, 2> CheckingGroups;
+
+ /// \brief Check if pointers are in the same partition
+ ///
+ /// \p PtrToPartition contains the partition number for pointers (-1 if the
+ /// pointer belongs to multiple partitions).
+ static bool
+ arePointersInSamePartition(const SmallVectorImpl<int> &PtrToPartition,
+ unsigned PtrIdx1, unsigned PtrIdx2);
+
+ /// \brief Decide whether we need to issue a run-time check for pointer at
+ /// index \p I and \p J to prove their independence.
+ bool needsChecking(unsigned I, unsigned J) const;
+
+ /// \brief Return PointerInfo for pointer at index \p PtrIdx.
+ const PointerInfo &getPointerInfo(unsigned PtrIdx) const {
+ return Pointers[PtrIdx];
+ }
+
+private:
+ /// \brief Groups pointers such that a single memcheck is required
+ /// between two different groups. This will clear the CheckingGroups vector
+ /// and re-compute it. We will only group dependecies if \p UseDependencies
+ /// is true, otherwise we will create a separate group for each pointer.
+ void groupChecks(MemoryDepChecker::DepCandidates &DepCands,
+ bool UseDependencies);
+
+ /// Generate the checks and return them.
+ SmallVector<PointerCheck, 4>
+ generateChecks() const;
+
+ /// Holds a pointer to the ScalarEvolution analysis.
+ ScalarEvolution *SE;
+
+ /// \brief Set of run-time checks required to establish independence of
+ /// otherwise may-aliasing pointers in the loop.
+ SmallVector<PointerCheck, 4> Checks;
+};
+
+/// \brief Drive the analysis of memory accesses in the loop
+///
+/// This class is responsible for analyzing the memory accesses of a loop. It
+/// collects the accesses and then its main helper the AccessAnalysis class
+/// finds and categorizes the dependences in buildDependenceSets.
+///
+/// For memory dependences that can be analyzed at compile time, it determines
+/// whether the dependence is part of cycle inhibiting vectorization. This work
+/// is delegated to the MemoryDepChecker class.
+///
+/// For memory dependences that cannot be determined at compile time, it
+/// generates run-time checks to prove independence. This is done by
+/// AccessAnalysis::canCheckPtrAtRT and the checks are maintained by the
+/// RuntimePointerCheck class.
+///
+/// If pointers can wrap or can't be expressed as affine AddRec expressions by
+/// ScalarEvolution, we will generate run-time checks by emitting a
+/// SCEVUnionPredicate.
+///
+/// Checks for both memory dependences and the SCEV predicates contained in the
+/// PSE must be emitted in order for the results of this analysis to be valid.
+class LoopAccessInfo {
+public:
+ LoopAccessInfo(Loop *L, ScalarEvolution *SE, const TargetLibraryInfo *TLI,
+ AliasAnalysis *AA, DominatorTree *DT, LoopInfo *LI);
+
+ /// Return true we can analyze the memory accesses in the loop and there are
+ /// no memory dependence cycles.
+ bool canVectorizeMemory() const { return CanVecMem; }
+
+ const RuntimePointerChecking *getRuntimePointerChecking() const {
+ return PtrRtChecking.get();
+ }
+
+ /// \brief Number of memchecks required to prove independence of otherwise
+ /// may-alias pointers.
+ unsigned getNumRuntimePointerChecks() const {
+ return PtrRtChecking->getNumberOfChecks();
+ }
+
+ /// Return true if the block BB needs to be predicated in order for the loop
+ /// to be vectorized.
+ static bool blockNeedsPredication(BasicBlock *BB, Loop *TheLoop,
+ DominatorTree *DT);
+
+ /// Returns true if the value V is uniform within the loop.
+ bool isUniform(Value *V) const;
+
+ uint64_t getMaxSafeDepDistBytes() const { return MaxSafeDepDistBytes; }
+ unsigned getNumStores() const { return NumStores; }
+ unsigned getNumLoads() const { return NumLoads;}
+
+ /// \brief Add code that checks at runtime if the accessed arrays overlap.
+ ///
+ /// Returns a pair of instructions where the first element is the first
+ /// instruction generated in possibly a sequence of instructions and the
+ /// second value is the final comparator value or NULL if no check is needed.
+ std::pair<Instruction *, Instruction *>
+ addRuntimeChecks(Instruction *Loc) const;
+
+ /// \brief Generete the instructions for the checks in \p PointerChecks.
+ ///
+ /// Returns a pair of instructions where the first element is the first
+ /// instruction generated in possibly a sequence of instructions and the
+ /// second value is the final comparator value or NULL if no check is needed.
+ std::pair<Instruction *, Instruction *>
+ addRuntimeChecks(Instruction *Loc,
+ const SmallVectorImpl<RuntimePointerChecking::PointerCheck>
+ &PointerChecks) const;
+
+ /// \brief The diagnostics report generated for the analysis. E.g. why we
+ /// couldn't analyze the loop.
+ const OptimizationRemarkAnalysis *getReport() const { return Report.get(); }
+
+ /// \brief the Memory Dependence Checker which can determine the
+ /// loop-independent and loop-carried dependences between memory accesses.
+ const MemoryDepChecker &getDepChecker() const { return *DepChecker; }
+
+ /// \brief Return the list of instructions that use \p Ptr to read or write
+ /// memory.
+ SmallVector<Instruction *, 4> getInstructionsForAccess(Value *Ptr,
+ bool isWrite) const {
+ return DepChecker->getInstructionsForAccess(Ptr, isWrite);
+ }
+
+ /// \brief If an access has a symbolic strides, this maps the pointer value to
+ /// the stride symbol.
+ const ValueToValueMap &getSymbolicStrides() const { return SymbolicStrides; }
+
+ /// \brief Pointer has a symbolic stride.
+ bool hasStride(Value *V) const { return StrideSet.count(V); }
+
+ /// \brief Print the information about the memory accesses in the loop.
+ void print(raw_ostream &OS, unsigned Depth = 0) const;
+
+ /// \brief Checks existence of store to invariant address inside loop.
+ /// If the loop has any store to invariant address, then it returns true,
+ /// else returns false.
+ bool hasStoreToLoopInvariantAddress() const {
+ return StoreToLoopInvariantAddress;
+ }
+
+ /// Used to add runtime SCEV checks. Simplifies SCEV expressions and converts
+ /// them to a more usable form. All SCEV expressions during the analysis
+ /// should be re-written (and therefore simplified) according to PSE.
+ /// A user of LoopAccessAnalysis will need to emit the runtime checks
+ /// associated with this predicate.
+ const PredicatedScalarEvolution &getPSE() const { return *PSE; }
+
+private:
+ /// \brief Analyze the loop.
+ void analyzeLoop(AliasAnalysis *AA, LoopInfo *LI,
+ const TargetLibraryInfo *TLI, DominatorTree *DT);
+
+ /// \brief Check if the structure of the loop allows it to be analyzed by this
+ /// pass.
+ bool canAnalyzeLoop();
+
+ /// \brief Save the analysis remark.
+ ///
+ /// LAA does not directly emits the remarks. Instead it stores it which the
+ /// client can retrieve and presents as its own analysis
+ /// (e.g. -Rpass-analysis=loop-vectorize).
+ OptimizationRemarkAnalysis &recordAnalysis(StringRef RemarkName,
+ Instruction *Instr = nullptr);
+
+ /// \brief Collect memory access with loop invariant strides.
+ ///
+ /// Looks for accesses like "a[i * StrideA]" where "StrideA" is loop
+ /// invariant.
+ void collectStridedAccess(Value *LoadOrStoreInst);
+
+ std::unique_ptr<PredicatedScalarEvolution> PSE;
+
+ /// We need to check that all of the pointers in this list are disjoint
+ /// at runtime. Using std::unique_ptr to make using move ctor simpler.
+ std::unique_ptr<RuntimePointerChecking> PtrRtChecking;
+
+ /// \brief the Memory Dependence Checker which can determine the
+ /// loop-independent and loop-carried dependences between memory accesses.
+ std::unique_ptr<MemoryDepChecker> DepChecker;
+
+ Loop *TheLoop;
+
+ unsigned NumLoads;
+ unsigned NumStores;
+
+ uint64_t MaxSafeDepDistBytes;
+
+ /// \brief Cache the result of analyzeLoop.
+ bool CanVecMem;
+
+ /// \brief Indicator for storing to uniform addresses.
+ /// If a loop has write to a loop invariant address then it should be true.
+ bool StoreToLoopInvariantAddress;
+
+ /// \brief The diagnostics report generated for the analysis. E.g. why we
+ /// couldn't analyze the loop.
+ std::unique_ptr<OptimizationRemarkAnalysis> Report;
+
+ /// \brief If an access has a symbolic strides, this maps the pointer value to
+ /// the stride symbol.
+ ValueToValueMap SymbolicStrides;
+
+ /// \brief Set of symbolic strides values.
+ SmallPtrSet<Value *, 8> StrideSet;
+};
+
+Value *stripIntegerCast(Value *V);
+
+/// \brief Return the SCEV corresponding to a pointer with the symbolic stride
+/// replaced with constant one, assuming the SCEV predicate associated with
+/// \p PSE is true.
+///
+/// If necessary this method will version the stride of the pointer according
+/// to \p PtrToStride and therefore add further predicates to \p PSE.
+///
+/// If \p OrigPtr is not null, use it to look up the stride value instead of \p
+/// Ptr. \p PtrToStride provides the mapping between the pointer value and its
+/// stride as collected by LoopVectorizationLegality::collectStridedAccess.
+const SCEV *replaceSymbolicStrideSCEV(PredicatedScalarEvolution &PSE,
+ const ValueToValueMap &PtrToStride,
+ Value *Ptr, Value *OrigPtr = nullptr);
+
+/// \brief If the pointer has a constant stride return it in units of its
+/// element size. Otherwise return zero.
+///
+/// Ensure that it does not wrap in the address space, assuming the predicate
+/// associated with \p PSE is true.
+///
+/// If necessary this method will version the stride of the pointer according
+/// to \p PtrToStride and therefore add further predicates to \p PSE.
+/// The \p Assume parameter indicates if we are allowed to make additional
+/// run-time assumptions.
+int64_t getPtrStride(PredicatedScalarEvolution &PSE, Value *Ptr, const Loop *Lp,
+ const ValueToValueMap &StridesMap = ValueToValueMap(),
+ bool Assume = false, bool ShouldCheckWrap = true);
+
+/// \brief Returns true if the memory operations \p A and \p B are consecutive.
+/// This is a simple API that does not depend on the analysis pass.
+bool isConsecutiveAccess(Value *A, Value *B, const DataLayout &DL,
+ ScalarEvolution &SE, bool CheckType = true);
+
+/// \brief This analysis provides dependence information for the memory accesses
+/// of a loop.
+///
+/// It runs the analysis for a loop on demand. This can be initiated by
+/// querying the loop access info via LAA::getInfo. getInfo return a
+/// LoopAccessInfo object. See this class for the specifics of what information
+/// is provided.
+class LoopAccessLegacyAnalysis : public FunctionPass {
+public:
+ static char ID;
+
+ LoopAccessLegacyAnalysis() : FunctionPass(ID) {
+ initializeLoopAccessLegacyAnalysisPass(*PassRegistry::getPassRegistry());
+ }
+
+ bool runOnFunction(Function &F) override;
+
+ void getAnalysisUsage(AnalysisUsage &AU) const override;
+
+ /// \brief Query the result of the loop access information for the loop \p L.
+ ///
+ /// If there is no cached result available run the analysis.
+ const LoopAccessInfo &getInfo(Loop *L);
+
+ void releaseMemory() override {
+ // Invalidate the cache when the pass is freed.
+ LoopAccessInfoMap.clear();
+ }
+
+ /// \brief Print the result of the analysis when invoked with -analyze.
+ void print(raw_ostream &OS, const Module *M = nullptr) const override;
+
+private:
+ /// \brief The cache.
+ DenseMap<Loop *, std::unique_ptr<LoopAccessInfo>> LoopAccessInfoMap;
+
+ // The used analysis passes.
+ ScalarEvolution *SE;
+ const TargetLibraryInfo *TLI;
+ AliasAnalysis *AA;
+ DominatorTree *DT;
+ LoopInfo *LI;
+};
+
+/// \brief This analysis provides dependence information for the memory
+/// accesses of a loop.
+///
+/// It runs the analysis for a loop on demand. This can be initiated by
+/// querying the loop access info via AM.getResult<LoopAccessAnalysis>.
+/// getResult return a LoopAccessInfo object. See this class for the
+/// specifics of what information is provided.
+class LoopAccessAnalysis
+ : public AnalysisInfoMixin<LoopAccessAnalysis> {
+ friend AnalysisInfoMixin<LoopAccessAnalysis>;
+ static AnalysisKey Key;
+
+public:
+ typedef LoopAccessInfo Result;
+
+ Result run(Loop &L, LoopAnalysisManager &AM, LoopStandardAnalysisResults &AR);
+};
+
+inline Instruction *MemoryDepChecker::Dependence::getSource(
+ const LoopAccessInfo &LAI) const {
+ return LAI.getDepChecker().getMemoryInstructions()[Source];
+}
+
+inline Instruction *MemoryDepChecker::Dependence::getDestination(
+ const LoopAccessInfo &LAI) const {
+ return LAI.getDepChecker().getMemoryInstructions()[Destination];
+}
+
+} // End llvm namespace
+
+#endif
