LCOV - code coverage report
Current view: top level - include/llvm/Analysis - LoopAccessAnalysis.h (source / functions) Hit Total Coverage
Test: llvm-toolchain.info Lines: 47 47 100.0 %
Date: 2018-06-17 00:07:59 Functions: 14 14 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : //===- llvm/Analysis/LoopAccessAnalysis.h -----------------------*- C++ -*-===//
       2             : //
       3             : //                     The LLVM Compiler Infrastructure
       4             : //
       5             : // This file is distributed under the University of Illinois Open Source
       6             : // License. See LICENSE.TXT for details.
       7             : //
       8             : //===----------------------------------------------------------------------===//
       9             : //
      10             : // This file defines the interface for the loop memory dependence framework that
      11             : // was originally developed for the Loop Vectorizer.
      12             : //
      13             : //===----------------------------------------------------------------------===//
      14             : 
      15             : #ifndef LLVM_ANALYSIS_LOOPACCESSANALYSIS_H
      16             : #define LLVM_ANALYSIS_LOOPACCESSANALYSIS_H
      17             : 
      18             : #include "llvm/ADT/EquivalenceClasses.h"
      19             : #include "llvm/ADT/Optional.h"
      20             : #include "llvm/ADT/SetVector.h"
      21             : #include "llvm/Analysis/AliasAnalysis.h"
      22             : #include "llvm/Analysis/AliasSetTracker.h"
      23             : #include "llvm/Analysis/LoopAnalysisManager.h"
      24             : #include "llvm/Analysis/ScalarEvolutionExpressions.h"
      25             : #include "llvm/IR/DiagnosticInfo.h"
      26             : #include "llvm/IR/ValueHandle.h"
      27             : #include "llvm/Pass.h"
      28             : #include "llvm/Support/raw_ostream.h"
      29             : 
      30             : namespace llvm {
      31             : 
      32             : class Value;
      33             : class DataLayout;
      34             : class ScalarEvolution;
      35             : class Loop;
      36             : class SCEV;
      37             : class SCEVUnionPredicate;
      38             : class LoopAccessInfo;
      39             : class OptimizationRemarkEmitter;
      40             : 
      41             : /// Collection of parameters shared beetween the Loop Vectorizer and the
      42             : /// Loop Access Analysis.
      43             : struct VectorizerParams {
      44             :   /// Maximum SIMD width.
      45             :   static const unsigned MaxVectorWidth;
      46             : 
      47             :   /// VF as overridden by the user.
      48             :   static unsigned VectorizationFactor;
      49             :   /// Interleave factor as overridden by the user.
      50             :   static unsigned VectorizationInterleave;
      51             :   /// True if force-vector-interleave was specified by the user.
      52             :   static bool isInterleaveForced();
      53             : 
      54             :   /// \When performing memory disambiguation checks at runtime do not
      55             :   /// make more than this number of comparisons.
      56             :   static unsigned RuntimeMemoryCheckThreshold;
      57             : };
      58             : 
      59             : /// Checks memory dependences among accesses to the same underlying
      60             : /// object to determine whether there vectorization is legal or not (and at
      61             : /// which vectorization factor).
      62             : ///
      63             : /// Note: This class will compute a conservative dependence for access to
      64             : /// different underlying pointers. Clients, such as the loop vectorizer, will
      65             : /// sometimes deal these potential dependencies by emitting runtime checks.
      66             : ///
      67             : /// We use the ScalarEvolution framework to symbolically evalutate access
      68             : /// functions pairs. Since we currently don't restructure the loop we can rely
      69             : /// on the program order of memory accesses to determine their safety.
      70             : /// At the moment we will only deem accesses as safe for:
      71             : ///  * A negative constant distance assuming program order.
      72             : ///
      73             : ///      Safe: tmp = a[i + 1];     OR     a[i + 1] = x;
      74             : ///            a[i] = tmp;                y = a[i];
      75             : ///
      76             : ///   The latter case is safe because later checks guarantuee that there can't
      77             : ///   be a cycle through a phi node (that is, we check that "x" and "y" is not
      78             : ///   the same variable: a header phi can only be an induction or a reduction, a
      79             : ///   reduction can't have a memory sink, an induction can't have a memory
      80             : ///   source). This is important and must not be violated (or we have to
      81             : ///   resort to checking for cycles through memory).
      82             : ///
      83             : ///  * A positive constant distance assuming program order that is bigger
      84             : ///    than the biggest memory access.
      85             : ///
      86             : ///     tmp = a[i]        OR              b[i] = x
      87             : ///     a[i+2] = tmp                      y = b[i+2];
      88             : ///
      89             : ///     Safe distance: 2 x sizeof(a[0]), and 2 x sizeof(b[0]), respectively.
      90             : ///
      91             : ///  * Zero distances and all accesses have the same size.
      92             : ///
      93       10887 : class MemoryDepChecker {
      94             : public:
      95             :   typedef PointerIntPair<Value *, 1, bool> MemAccessInfo;
      96             :   typedef SmallVector<MemAccessInfo, 8> MemAccessInfoList;
      97             :   /// Set of potential dependent memory accesses.
      98             :   typedef EquivalenceClasses<MemAccessInfo> DepCandidates;
      99             : 
     100             :   /// Dependece between memory access instructions.
     101             :   struct Dependence {
     102             :     /// The type of the dependence.
     103             :     enum DepType {
     104             :       // No dependence.
     105             :       NoDep,
     106             :       // We couldn't determine the direction or the distance.
     107             :       Unknown,
     108             :       // Lexically forward.
     109             :       //
     110             :       // FIXME: If we only have loop-independent forward dependences (e.g. a
     111             :       // read and write of A[i]), LAA will locally deem the dependence "safe"
     112             :       // without querying the MemoryDepChecker.  Therefore we can miss
     113             :       // enumerating loop-independent forward dependences in
     114             :       // getDependences.  Note that as soon as there are different
     115             :       // indices used to access the same array, the MemoryDepChecker *is*
     116             :       // queried and the dependence list is complete.
     117             :       Forward,
     118             :       // Forward, but if vectorized, is likely to prevent store-to-load
     119             :       // forwarding.
     120             :       ForwardButPreventsForwarding,
     121             :       // Lexically backward.
     122             :       Backward,
     123             :       // Backward, but the distance allows a vectorization factor of
     124             :       // MaxSafeDepDistBytes.
     125             :       BackwardVectorizable,
     126             :       // Same, but may prevent store-to-load forwarding.
     127             :       BackwardVectorizableButPreventsForwarding
     128             :     };
     129             : 
     130             :     /// String version of the types.
     131             :     static const char *DepName[];
     132             : 
     133             :     /// Index of the source of the dependence in the InstMap vector.
     134             :     unsigned Source;
     135             :     /// Index of the destination of the dependence in the InstMap vector.
     136             :     unsigned Destination;
     137             :     /// The type of the dependence.
     138             :     DepType Type;
     139             : 
     140             :     Dependence(unsigned Source, unsigned Destination, DepType Type)
     141         401 :         : Source(Source), Destination(Destination), Type(Type) {}
     142             : 
     143             :     /// Return the source instruction of the dependence.
     144             :     Instruction *getSource(const LoopAccessInfo &LAI) const;
     145             :     /// Return the destination instruction of the dependence.
     146             :     Instruction *getDestination(const LoopAccessInfo &LAI) const;
     147             : 
     148             :     /// Dependence types that don't prevent vectorization.
     149             :     static bool isSafeForVectorization(DepType Type);
     150             : 
     151             :     /// Lexically forward dependence.
     152             :     bool isForward() const;
     153             :     /// Lexically backward dependence.
     154             :     bool isBackward() const;
     155             : 
     156             :     /// May be a lexically backward dependence type (includes Unknown).
     157             :     bool isPossiblyBackward() const;
     158             : 
     159             :     /// Print the dependence.  \p Instr is used to map the instruction
     160             :     /// indices to instructions.
     161             :     void print(raw_ostream &OS, unsigned Depth,
     162             :                const SmallVectorImpl<Instruction *> &Instrs) const;
     163             :   };
     164             : 
     165             :   MemoryDepChecker(PredicatedScalarEvolution &PSE, const Loop *L)
     166        3629 :       : PSE(PSE), InnermostLoop(L), AccessIdx(0), MaxSafeRegisterWidth(-1U),
     167             :         ShouldRetryWithRuntimeCheck(false), SafeForVectorization(true),
     168        7258 :         RecordDependences(true) {}
     169             : 
     170             :   /// Register the location (instructions are given increasing numbers)
     171             :   /// of a write access.
     172        3854 :   void addAccess(StoreInst *SI) {
     173             :     Value *Ptr = SI->getPointerOperand();
     174        7708 :     Accesses[MemAccessInfo(Ptr, true)].push_back(AccessIdx);
     175        3854 :     InstMap.push_back(SI);
     176        3854 :     ++AccessIdx;
     177        3854 :   }
     178             : 
     179             :   /// Register the location (instructions are given increasing numbers)
     180             :   /// of a write access.
     181        4632 :   void addAccess(LoadInst *LI) {
     182             :     Value *Ptr = LI->getPointerOperand();
     183        9264 :     Accesses[MemAccessInfo(Ptr, false)].push_back(AccessIdx);
     184        4632 :     InstMap.push_back(LI);
     185        4632 :     ++AccessIdx;
     186        4632 :   }
     187             : 
     188             :   /// Check whether the dependencies between the accesses are safe.
     189             :   ///
     190             :   /// Only checks sets with elements in \p CheckDeps.
     191             :   bool areDepsSafe(DepCandidates &AccessSets, MemAccessInfoList &CheckDeps,
     192             :                    const ValueToValueMap &Strides);
     193             : 
     194             :   /// No memory dependence was encountered that would inhibit
     195             :   /// vectorization.
     196             :   bool isSafeForVectorization() const { return SafeForVectorization; }
     197             : 
     198             :   /// The maximum number of bytes of a vector register we can vectorize
     199             :   /// the accesses safely with.
     200             :   uint64_t getMaxSafeDepDistBytes() { return MaxSafeDepDistBytes; }
     201             : 
     202             :   /// Return the number of elements that are safe to operate on
     203             :   /// simultaneously, multiplied by the size of the element in bits.
     204             :   uint64_t getMaxSafeRegisterWidth() const { return MaxSafeRegisterWidth; }
     205             : 
     206             :   /// In same cases when the dependency check fails we can still
     207             :   /// vectorize the loop with a dynamic array access check.
     208             :   bool shouldRetryWithRuntimeCheck() { return ShouldRetryWithRuntimeCheck; }
     209             : 
     210             :   /// Returns the memory dependences.  If null is returned we exceeded
     211             :   /// the MaxDependences threshold and this information is not
     212             :   /// available.
     213             :   const SmallVectorImpl<Dependence> *getDependences() const {
     214        2898 :     return RecordDependences ? &Dependences : nullptr;
     215             :   }
     216             : 
     217             :   void clearDependences() { Dependences.clear(); }
     218             : 
     219             :   /// The vector of memory access instructions.  The indices are used as
     220             :   /// instruction identifiers in the Dependence class.
     221             :   const SmallVectorImpl<Instruction *> &getMemoryInstructions() const {
     222          93 :     return InstMap;
     223             :   }
     224             : 
     225             :   /// Generate a mapping between the memory instructions and their
     226             :   /// indices according to program order.
     227          25 :   DenseMap<Instruction *, unsigned> generateInstructionOrderMap() const {
     228             :     DenseMap<Instruction *, unsigned> OrderMap;
     229             : 
     230         293 :     for (unsigned I = 0; I < InstMap.size(); ++I)
     231          81 :       OrderMap[InstMap[I]] = I;
     232             : 
     233          25 :     return OrderMap;
     234             :   }
     235             : 
     236             :   /// Find the set of instructions that read or write via \p Ptr.
     237             :   SmallVector<Instruction *, 4> getInstructionsForAccess(Value *Ptr,
     238             :                                                          bool isWrite) const;
     239             : 
     240             : private:
     241             :   /// A wrapper around ScalarEvolution, used to add runtime SCEV checks, and
     242             :   /// applies dynamic knowledge to simplify SCEV expressions and convert them
     243             :   /// to a more usable form. We need this in case assumptions about SCEV
     244             :   /// expressions need to be made in order to avoid unknown dependences. For
     245             :   /// example we might assume a unit stride for a pointer in order to prove
     246             :   /// that a memory access is strided and doesn't wrap.
     247             :   PredicatedScalarEvolution &PSE;
     248             :   const Loop *InnermostLoop;
     249             : 
     250             :   /// Maps access locations (ptr, read/write) to program order.
     251             :   DenseMap<MemAccessInfo, std::vector<unsigned> > Accesses;
     252             : 
     253             :   /// Memory access instructions in program order.
     254             :   SmallVector<Instruction *, 16> InstMap;
     255             : 
     256             :   /// The program order index to be used for the next instruction.
     257             :   unsigned AccessIdx;
     258             : 
     259             :   // We can access this many bytes in parallel safely.
     260             :   uint64_t MaxSafeDepDistBytes;
     261             : 
     262             :   /// Number of elements (from consecutive iterations) that are safe to
     263             :   /// operate on simultaneously, multiplied by the size of the element in bits.
     264             :   /// The size of the element is taken from the memory access that is most
     265             :   /// restrictive.
     266             :   uint64_t MaxSafeRegisterWidth;
     267             : 
     268             :   /// If we see a non-constant dependence distance we can still try to
     269             :   /// vectorize this loop with runtime checks.
     270             :   bool ShouldRetryWithRuntimeCheck;
     271             : 
     272             :   /// No memory dependence was encountered that would inhibit
     273             :   /// vectorization.
     274             :   bool SafeForVectorization;
     275             : 
     276             :   //// True if Dependences reflects the dependences in the
     277             :   //// loop.  If false we exceeded MaxDependences and
     278             :   //// Dependences is invalid.
     279             :   bool RecordDependences;
     280             : 
     281             :   /// Memory dependences collected during the analysis.  Only valid if
     282             :   /// RecordDependences is true.
     283             :   SmallVector<Dependence, 8> Dependences;
     284             : 
     285             :   /// Check whether there is a plausible dependence between the two
     286             :   /// accesses.
     287             :   ///
     288             :   /// Access \p A must happen before \p B in program order. The two indices
     289             :   /// identify the index into the program order map.
     290             :   ///
     291             :   /// This function checks  whether there is a plausible dependence (or the
     292             :   /// absence of such can't be proved) between the two accesses. If there is a
     293             :   /// plausible dependence but the dependence distance is bigger than one
     294             :   /// element access it records this distance in \p MaxSafeDepDistBytes (if this
     295             :   /// distance is smaller than any other distance encountered so far).
     296             :   /// Otherwise, this function returns true signaling a possible dependence.
     297             :   Dependence::DepType isDependent(const MemAccessInfo &A, unsigned AIdx,
     298             :                                   const MemAccessInfo &B, unsigned BIdx,
     299             :                                   const ValueToValueMap &Strides);
     300             : 
     301             :   /// Check whether the data dependence could prevent store-load
     302             :   /// forwarding.
     303             :   ///
     304             :   /// \return false if we shouldn't vectorize at all or avoid larger
     305             :   /// vectorization factors by limiting MaxSafeDepDistBytes.
     306             :   bool couldPreventStoreLoadForward(uint64_t Distance, uint64_t TypeByteSize);
     307             : };
     308             : 
     309             : /// Holds information about the memory runtime legality checks to verify
     310             : /// that a group of pointers do not overlap.
     311        7258 : class RuntimePointerChecking {
     312             : public:
     313        8594 :   struct PointerInfo {
     314             :     /// Holds the pointer value that we need to check.
     315             :     TrackingVH<Value> PointerValue;
     316             :     /// Holds the smallest byte address accessed by the pointer throughout all
     317             :     /// iterations of the loop.
     318             :     const SCEV *Start;
     319             :     /// Holds the largest byte address accessed by the pointer throughout all
     320             :     /// iterations of the loop, plus 1.
     321             :     const SCEV *End;
     322             :     /// Holds the information if this pointer is used for writing to memory.
     323             :     bool IsWritePtr;
     324             :     /// Holds the id of the set of pointers that could be dependent because of a
     325             :     /// shared underlying object.
     326             :     unsigned DependencySetId;
     327             :     /// Holds the id of the disjoint alias set to which this pointer belongs.
     328             :     unsigned AliasSetId;
     329             :     /// SCEV for the access.
     330             :     const SCEV *Expr;
     331             : 
     332             :     PointerInfo(Value *PointerValue, const SCEV *Start, const SCEV *End,
     333             :                 bool IsWritePtr, unsigned DependencySetId, unsigned AliasSetId,
     334             :                 const SCEV *Expr)
     335        3416 :         : PointerValue(PointerValue), Start(Start), End(End),
     336             :           IsWritePtr(IsWritePtr), DependencySetId(DependencySetId),
     337        3416 :           AliasSetId(AliasSetId), Expr(Expr) {}
     338             :   };
     339             : 
     340        7258 :   RuntimePointerChecking(ScalarEvolution *SE) : Need(false), SE(SE) {}
     341             : 
     342             :   /// Reset the state of the pointer runtime information.
     343             :   void reset() {
     344         287 :     Need = false;
     345             :     Pointers.clear();
     346             :     Checks.clear();
     347             :   }
     348             : 
     349             :   /// Insert a pointer and calculate the start and end SCEVs.
     350             :   /// We need \p PSE in order to compute the SCEV expression of the pointer
     351             :   /// according to the assumptions that we've made during the analysis.
     352             :   /// The method might also version the pointer stride according to \p Strides,
     353             :   /// and add new predicates to \p PSE.
     354             :   void insert(Loop *Lp, Value *Ptr, bool WritePtr, unsigned DepSetId,
     355             :               unsigned ASId, const ValueToValueMap &Strides,
     356             :               PredicatedScalarEvolution &PSE);
     357             : 
     358             :   /// No run-time memory checking is necessary.
     359             :   bool empty() const { return Pointers.empty(); }
     360             : 
     361             :   /// A grouping of pointers. A single memcheck is required between
     362             :   /// two groups.
     363        6633 :   struct CheckingPtrGroup {
     364             :     /// Create a new pointer checking group containing a single
     365             :     /// pointer, with index \p Index in RtCheck.
     366         969 :     CheckingPtrGroup(unsigned Index, RuntimePointerChecking &RtCheck)
     367        2907 :         : RtCheck(RtCheck), High(RtCheck.Pointers[Index].End),
     368        2907 :           Low(RtCheck.Pointers[Index].Start) {
     369         969 :       Members.push_back(Index);
     370         969 :     }
     371             : 
     372             :     /// Tries to add the pointer recorded in RtCheck at index
     373             :     /// \p Index to this pointer checking group. We can only add a pointer
     374             :     /// to a checking group if we will still be able to get
     375             :     /// the upper and lower bounds of the check. Returns true in case
     376             :     /// of success, false otherwise.
     377             :     bool addPointer(unsigned Index);
     378             : 
     379             :     /// Constitutes the context of this pointer checking group. For each
     380             :     /// pointer that is a member of this group we will retain the index
     381             :     /// at which it appears in RtCheck.
     382             :     RuntimePointerChecking &RtCheck;
     383             :     /// The SCEV expression which represents the upper bound of all the
     384             :     /// pointers in this group.
     385             :     const SCEV *High;
     386             :     /// The SCEV expression which represents the lower bound of all the
     387             :     /// pointers in this group.
     388             :     const SCEV *Low;
     389             :     /// Indices of all the pointers that constitute this grouping.
     390             :     SmallVector<unsigned, 2> Members;
     391             :   };
     392             : 
     393             :   /// A memcheck which made up of a pair of grouped pointers.
     394             :   ///
     395             :   /// These *have* to be const for now, since checks are generated from
     396             :   /// CheckingPtrGroups in LAI::addRuntimeChecks which is a const member
     397             :   /// function.  FIXME: once check-generation is moved inside this class (after
     398             :   /// the PtrPartition hack is removed), we could drop const.
     399             :   typedef std::pair<const CheckingPtrGroup *, const CheckingPtrGroup *>
     400             :       PointerCheck;
     401             : 
     402             :   /// Generate the checks and store it.  This also performs the grouping
     403             :   /// of pointers to reduce the number of memchecks necessary.
     404             :   void generateChecks(MemoryDepChecker::DepCandidates &DepCands,
     405             :                       bool UseDependencies);
     406             : 
     407             :   /// Returns the checks that generateChecks created.
     408             :   const SmallVector<PointerCheck, 4> &getChecks() const { return Checks; }
     409             : 
     410             :   /// Decide if we need to add a check between two groups of pointers,
     411             :   /// according to needsChecking.
     412             :   bool needsChecking(const CheckingPtrGroup &M,
     413             :                      const CheckingPtrGroup &N) const;
     414             : 
     415             :   /// Returns the number of run-time checks required according to
     416             :   /// needsChecking.
     417         876 :   unsigned getNumberOfChecks() const { return Checks.size(); }
     418             : 
     419             :   /// Print the list run-time memory checks necessary.
     420             :   void print(raw_ostream &OS, unsigned Depth = 0) const;
     421             : 
     422             :   /// Print \p Checks.
     423             :   void printChecks(raw_ostream &OS, const SmallVectorImpl<PointerCheck> &Checks,
     424             :                    unsigned Depth = 0) const;
     425             : 
     426             :   /// This flag indicates if we need to add the runtime check.
     427             :   bool Need;
     428             : 
     429             :   /// Information about the pointers that may require checking.
     430             :   SmallVector<PointerInfo, 2> Pointers;
     431             : 
     432             :   /// Holds a partitioning of pointers into "check groups".
     433             :   SmallVector<CheckingPtrGroup, 2> CheckingGroups;
     434             : 
     435             :   /// Check if pointers are in the same partition
     436             :   ///
     437             :   /// \p PtrToPartition contains the partition number for pointers (-1 if the
     438             :   /// pointer belongs to multiple partitions).
     439             :   static bool
     440             :   arePointersInSamePartition(const SmallVectorImpl<int> &PtrToPartition,
     441             :                              unsigned PtrIdx1, unsigned PtrIdx2);
     442             : 
     443             :   /// Decide whether we need to issue a run-time check for pointer at
     444             :   /// index \p I and \p J to prove their independence.
     445             :   bool needsChecking(unsigned I, unsigned J) const;
     446             : 
     447             :   /// Return PointerInfo for pointer at index \p PtrIdx.
     448             :   const PointerInfo &getPointerInfo(unsigned PtrIdx) const {
     449         528 :     return Pointers[PtrIdx];
     450             :   }
     451             : 
     452             : private:
     453             :   /// Groups pointers such that a single memcheck is required
     454             :   /// between two different groups. This will clear the CheckingGroups vector
     455             :   /// and re-compute it. We will only group dependecies if \p UseDependencies
     456             :   /// is true, otherwise we will create a separate group for each pointer.
     457             :   void groupChecks(MemoryDepChecker::DepCandidates &DepCands,
     458             :                    bool UseDependencies);
     459             : 
     460             :   /// Generate the checks and return them.
     461             :   SmallVector<PointerCheck, 4>
     462             :   generateChecks() const;
     463             : 
     464             :   /// Holds a pointer to the ScalarEvolution analysis.
     465             :   ScalarEvolution *SE;
     466             : 
     467             :   /// Set of run-time checks required to establish independence of
     468             :   /// otherwise may-aliasing pointers in the loop.
     469             :   SmallVector<PointerCheck, 4> Checks;
     470             : };
     471             : 
     472             : /// Drive the analysis of memory accesses in the loop
     473             : ///
     474             : /// This class is responsible for analyzing the memory accesses of a loop.  It
     475             : /// collects the accesses and then its main helper the AccessAnalysis class
     476             : /// finds and categorizes the dependences in buildDependenceSets.
     477             : ///
     478             : /// For memory dependences that can be analyzed at compile time, it determines
     479             : /// whether the dependence is part of cycle inhibiting vectorization.  This work
     480             : /// is delegated to the MemoryDepChecker class.
     481             : ///
     482             : /// For memory dependences that cannot be determined at compile time, it
     483             : /// generates run-time checks to prove independence.  This is done by
     484             : /// AccessAnalysis::canCheckPtrAtRT and the checks are maintained by the
     485             : /// RuntimePointerCheck class.
     486             : ///
     487             : /// If pointers can wrap or can't be expressed as affine AddRec expressions by
     488             : /// ScalarEvolution, we will generate run-time checks by emitting a
     489             : /// SCEVUnionPredicate.
     490             : ///
     491             : /// Checks for both memory dependences and the SCEV predicates contained in the
     492             : /// PSE must be emitted in order for the results of this analysis to be valid.
     493        8308 : class LoopAccessInfo {
     494             : public:
     495             :   LoopAccessInfo(Loop *L, ScalarEvolution *SE, const TargetLibraryInfo *TLI,
     496             :                  AliasAnalysis *AA, DominatorTree *DT, LoopInfo *LI);
     497             : 
     498             :   /// Return true we can analyze the memory accesses in the loop and there are
     499             :   /// no memory dependence cycles.
     500             :   bool canVectorizeMemory() const { return CanVecMem; }
     501             : 
     502             :   const RuntimePointerChecking *getRuntimePointerChecking() const {
     503             :     return PtrRtChecking.get();
     504             :   }
     505             : 
     506             :   /// Number of memchecks required to prove independence of otherwise
     507             :   /// may-alias pointers.
     508             :   unsigned getNumRuntimePointerChecks() const {
     509             :     return PtrRtChecking->getNumberOfChecks();
     510             :   }
     511             : 
     512             :   /// Return true if the block BB needs to be predicated in order for the loop
     513             :   /// to be vectorized.
     514             :   static bool blockNeedsPredication(BasicBlock *BB, Loop *TheLoop,
     515             :                                     DominatorTree *DT);
     516             : 
     517             :   /// Returns true if the value V is uniform within the loop.
     518             :   bool isUniform(Value *V) const;
     519             : 
     520             :   uint64_t getMaxSafeDepDistBytes() const { return MaxSafeDepDistBytes; }
     521             :   unsigned getNumStores() const { return NumStores; }
     522             :   unsigned getNumLoads() const { return NumLoads;}
     523             : 
     524             :   /// Add code that checks at runtime if the accessed arrays overlap.
     525             :   ///
     526             :   /// Returns a pair of instructions where the first element is the first
     527             :   /// instruction generated in possibly a sequence of instructions and the
     528             :   /// second value is the final comparator value or NULL if no check is needed.
     529             :   std::pair<Instruction *, Instruction *>
     530             :   addRuntimeChecks(Instruction *Loc) const;
     531             : 
     532             :   /// Generete the instructions for the checks in \p PointerChecks.
     533             :   ///
     534             :   /// Returns a pair of instructions where the first element is the first
     535             :   /// instruction generated in possibly a sequence of instructions and the
     536             :   /// second value is the final comparator value or NULL if no check is needed.
     537             :   std::pair<Instruction *, Instruction *>
     538             :   addRuntimeChecks(Instruction *Loc,
     539             :                    const SmallVectorImpl<RuntimePointerChecking::PointerCheck>
     540             :                        &PointerChecks) const;
     541             : 
     542             :   /// The diagnostics report generated for the analysis.  E.g. why we
     543             :   /// couldn't analyze the loop.
     544             :   const OptimizationRemarkAnalysis *getReport() const { return Report.get(); }
     545             : 
     546             :   /// the Memory Dependence Checker which can determine the
     547             :   /// loop-independent and loop-carried dependences between memory accesses.
     548             :   const MemoryDepChecker &getDepChecker() const { return *DepChecker; }
     549             : 
     550             :   /// Return the list of instructions that use \p Ptr to read or write
     551             :   /// memory.
     552             :   SmallVector<Instruction *, 4> getInstructionsForAccess(Value *Ptr,
     553             :                                                          bool isWrite) const {
     554         112 :     return DepChecker->getInstructionsForAccess(Ptr, isWrite);
     555             :   }
     556             : 
     557             :   /// If an access has a symbolic strides, this maps the pointer value to
     558             :   /// the stride symbol.
     559        7621 :   const ValueToValueMap &getSymbolicStrides() const { return SymbolicStrides; }
     560             : 
     561             :   /// Pointer has a symbolic stride.
     562        7390 :   bool hasStride(Value *V) const { return StrideSet.count(V); }
     563             : 
     564             :   /// Print the information about the memory accesses in the loop.
     565             :   void print(raw_ostream &OS, unsigned Depth = 0) const;
     566             : 
     567             :   /// Checks existence of store to invariant address inside loop.
     568             :   /// If the loop has any store to invariant address, then it returns true,
     569             :   /// else returns false.
     570             :   bool hasStoreToLoopInvariantAddress() const {
     571             :     return StoreToLoopInvariantAddress;
     572             :   }
     573             : 
     574             :   /// Used to add runtime SCEV checks. Simplifies SCEV expressions and converts
     575             :   /// them to a more usable form.  All SCEV expressions during the analysis
     576             :   /// should be re-written (and therefore simplified) according to PSE.
     577             :   /// A user of LoopAccessAnalysis will need to emit the runtime checks
     578             :   /// associated with this predicate.
     579             :   const PredicatedScalarEvolution &getPSE() const { return *PSE; }
     580             : 
     581             : private:
     582             :   /// Analyze the loop.
     583             :   void analyzeLoop(AliasAnalysis *AA, LoopInfo *LI,
     584             :                    const TargetLibraryInfo *TLI, DominatorTree *DT);
     585             : 
     586             :   /// Check if the structure of the loop allows it to be analyzed by this
     587             :   /// pass.
     588             :   bool canAnalyzeLoop();
     589             : 
     590             :   /// Save the analysis remark.
     591             :   ///
     592             :   /// LAA does not directly emits the remarks.  Instead it stores it which the
     593             :   /// client can retrieve and presents as its own analysis
     594             :   /// (e.g. -Rpass-analysis=loop-vectorize).
     595             :   OptimizationRemarkAnalysis &recordAnalysis(StringRef RemarkName,
     596             :                                              Instruction *Instr = nullptr);
     597             : 
     598             :   /// Collect memory access with loop invariant strides.
     599             :   ///
     600             :   /// Looks for accesses like "a[i * StrideA]" where "StrideA" is loop
     601             :   /// invariant.
     602             :   void collectStridedAccess(Value *LoadOrStoreInst);
     603             : 
     604             :   std::unique_ptr<PredicatedScalarEvolution> PSE;
     605             : 
     606             :   /// We need to check that all of the pointers in this list are disjoint
     607             :   /// at runtime. Using std::unique_ptr to make using move ctor simpler.
     608             :   std::unique_ptr<RuntimePointerChecking> PtrRtChecking;
     609             : 
     610             :   /// the Memory Dependence Checker which can determine the
     611             :   /// loop-independent and loop-carried dependences between memory accesses.
     612             :   std::unique_ptr<MemoryDepChecker> DepChecker;
     613             : 
     614             :   Loop *TheLoop;
     615             : 
     616             :   unsigned NumLoads;
     617             :   unsigned NumStores;
     618             : 
     619             :   uint64_t MaxSafeDepDistBytes;
     620             : 
     621             :   /// Cache the result of analyzeLoop.
     622             :   bool CanVecMem;
     623             : 
     624             :   /// Indicator for storing to uniform addresses.
     625             :   /// If a loop has write to a loop invariant address then it should be true.
     626             :   bool StoreToLoopInvariantAddress;
     627             : 
     628             :   /// The diagnostics report generated for the analysis.  E.g. why we
     629             :   /// couldn't analyze the loop.
     630             :   std::unique_ptr<OptimizationRemarkAnalysis> Report;
     631             : 
     632             :   /// If an access has a symbolic strides, this maps the pointer value to
     633             :   /// the stride symbol.
     634             :   ValueToValueMap SymbolicStrides;
     635             : 
     636             :   /// Set of symbolic strides values.
     637             :   SmallPtrSet<Value *, 8> StrideSet;
     638             : };
     639             : 
     640             : Value *stripIntegerCast(Value *V);
     641             : 
     642             : /// Return the SCEV corresponding to a pointer with the symbolic stride
     643             : /// replaced with constant one, assuming the SCEV predicate associated with
     644             : /// \p PSE is true.
     645             : ///
     646             : /// If necessary this method will version the stride of the pointer according
     647             : /// to \p PtrToStride and therefore add further predicates to \p PSE.
     648             : ///
     649             : /// If \p OrigPtr is not null, use it to look up the stride value instead of \p
     650             : /// Ptr.  \p PtrToStride provides the mapping between the pointer value and its
     651             : /// stride as collected by LoopVectorizationLegality::collectStridedAccess.
     652             : const SCEV *replaceSymbolicStrideSCEV(PredicatedScalarEvolution &PSE,
     653             :                                       const ValueToValueMap &PtrToStride,
     654             :                                       Value *Ptr, Value *OrigPtr = nullptr);
     655             : 
     656             : /// If the pointer has a constant stride return it in units of its
     657             : /// element size.  Otherwise return zero.
     658             : ///
     659             : /// Ensure that it does not wrap in the address space, assuming the predicate
     660             : /// associated with \p PSE is true.
     661             : ///
     662             : /// If necessary this method will version the stride of the pointer according
     663             : /// to \p PtrToStride and therefore add further predicates to \p PSE.
     664             : /// The \p Assume parameter indicates if we are allowed to make additional
     665             : /// run-time assumptions.
     666             : int64_t getPtrStride(PredicatedScalarEvolution &PSE, Value *Ptr, const Loop *Lp,
     667             :                      const ValueToValueMap &StridesMap = ValueToValueMap(),
     668             :                      bool Assume = false, bool ShouldCheckWrap = true);
     669             : 
     670             : /// Attempt to sort the pointers in \p VL and return the sorted indices
     671             : /// in \p SortedIndices, if reordering is required.
     672             : ///
     673             : /// Returns 'true' if sorting is legal, otherwise returns 'false'.
     674             : ///
     675             : /// For example, for a given \p VL of memory accesses in program order, a[i+4],
     676             : /// a[i+0], a[i+1] and a[i+7], this function will sort the \p VL and save the
     677             : /// sorted indices in \p SortedIndices as a[i+0], a[i+1], a[i+4], a[i+7] and
     678             : /// saves the mask for actual memory accesses in program order in
     679             : /// \p SortedIndices as <1,2,0,3>
     680             : bool sortPtrAccesses(ArrayRef<Value *> VL, const DataLayout &DL,
     681             :                      ScalarEvolution &SE,
     682             :                      SmallVectorImpl<unsigned> &SortedIndices);
     683             : 
     684             : /// Returns true if the memory operations \p A and \p B are consecutive.
     685             : /// This is a simple API that does not depend on the analysis pass. 
     686             : bool isConsecutiveAccess(Value *A, Value *B, const DataLayout &DL,
     687             :                          ScalarEvolution &SE, bool CheckType = true);
     688             : 
     689             : /// This analysis provides dependence information for the memory accesses
     690             : /// of a loop.
     691             : ///
     692             : /// It runs the analysis for a loop on demand.  This can be initiated by
     693             : /// querying the loop access info via LAA::getInfo.  getInfo return a
     694             : /// LoopAccessInfo object.  See this class for the specifics of what information
     695             : /// is provided.
     696       11409 : class LoopAccessLegacyAnalysis : public FunctionPass {
     697             : public:
     698             :   static char ID;
     699             : 
     700        7606 :   LoopAccessLegacyAnalysis() : FunctionPass(ID) {
     701        3803 :     initializeLoopAccessLegacyAnalysisPass(*PassRegistry::getPassRegistry());
     702        3803 :   }
     703             : 
     704             :   bool runOnFunction(Function &F) override;
     705             : 
     706             :   void getAnalysisUsage(AnalysisUsage &AU) const override;
     707             : 
     708             :   /// Query the result of the loop access information for the loop \p L.
     709             :   ///
     710             :   /// If there is no cached result available run the analysis.
     711             :   const LoopAccessInfo &getInfo(Loop *L);
     712             : 
     713       32903 :   void releaseMemory() override {
     714             :     // Invalidate the cache when the pass is freed.
     715       32903 :     LoopAccessInfoMap.clear();
     716       32903 :   }
     717             : 
     718             :   /// Print the result of the analysis when invoked with -analyze.
     719             :   void print(raw_ostream &OS, const Module *M = nullptr) const override;
     720             : 
     721             : private:
     722             :   /// The cache.
     723             :   DenseMap<Loop *, std::unique_ptr<LoopAccessInfo>> LoopAccessInfoMap;
     724             : 
     725             :   // The used analysis passes.
     726             :   ScalarEvolution *SE;
     727             :   const TargetLibraryInfo *TLI;
     728             :   AliasAnalysis *AA;
     729             :   DominatorTree *DT;
     730             :   LoopInfo *LI;
     731             : };
     732             : 
     733             : /// This analysis provides dependence information for the memory
     734             : /// accesses of a loop.
     735             : ///
     736             : /// It runs the analysis for a loop on demand.  This can be initiated by
     737             : /// querying the loop access info via AM.getResult<LoopAccessAnalysis>. 
     738             : /// getResult return a LoopAccessInfo object.  See this class for the
     739             : /// specifics of what information is provided.
     740             : class LoopAccessAnalysis
     741             :     : public AnalysisInfoMixin<LoopAccessAnalysis> {
     742             :   friend AnalysisInfoMixin<LoopAccessAnalysis>;
     743             :   static AnalysisKey Key;
     744             : 
     745             : public:
     746             :   typedef LoopAccessInfo Result;
     747             : 
     748             :   Result run(Loop &L, LoopAnalysisManager &AM, LoopStandardAnalysisResults &AR);
     749             : };
     750             : 
     751             : inline Instruction *MemoryDepChecker::Dependence::getSource(
     752             :     const LoopAccessInfo &LAI) const {
     753         278 :   return LAI.getDepChecker().getMemoryInstructions()[Source];
     754             : }
     755             : 
     756             : inline Instruction *MemoryDepChecker::Dependence::getDestination(
     757             :     const LoopAccessInfo &LAI) const {
     758         278 :   return LAI.getDepChecker().getMemoryInstructions()[Destination];
     759             : }
     760             : 
     761             : } // End llvm namespace
     762             : 
     763             : #endif

Generated by: LCOV version 1.13