LCOV - code coverage report
Current view: top level - include/llvm/Analysis - LoopAccessAnalysis.h (source / functions) Hit Total Coverage
Test: llvm-toolchain.info Lines: 58 58 100.0 %
Date: 2017-09-14 15:23:50 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             : /// \brief Collection of parameters shared beetween the Loop Vectorizer and the
      42             : /// Loop Access Analysis.
      43             : struct VectorizerParams {
      44             :   /// \brief Maximum SIMD width.
      45             :   static const unsigned MaxVectorWidth;
      46             : 
      47             :   /// \brief VF as overridden by the user.
      48             :   static unsigned VectorizationFactor;
      49             :   /// \brief Interleave factor as overridden by the user.
      50             :   static unsigned VectorizationInterleave;
      51             :   /// \brief True if force-vector-interleave was specified by the user.
      52             :   static bool isInterleaveForced();
      53             : 
      54             :   /// \\brief When performing memory disambiguation checks at runtime do not
      55             :   /// make more than this number of comparisons.
      56             :   static unsigned RuntimeMemoryCheckThreshold;
      57             : };
      58             : 
      59             : /// \brief 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       12816 : class MemoryDepChecker {
      94             : public:
      95             :   typedef PointerIntPair<Value *, 1, bool> MemAccessInfo;
      96             :   typedef SmallVector<MemAccessInfo, 8> MemAccessInfoList;
      97             :   /// \brief Set of potential dependent memory accesses.
      98             :   typedef EquivalenceClasses<MemAccessInfo> DepCandidates;
      99             : 
     100             :   /// \brief Dependece between memory access instructions.
     101             :   struct Dependence {
     102             :     /// \brief 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             :     /// \brief String version of the types.
     131             :     static const char *DepName[];
     132             : 
     133             :     /// \brief Index of the source of the dependence in the InstMap vector.
     134             :     unsigned Source;
     135             :     /// \brief Index of the destination of the dependence in the InstMap vector.
     136             :     unsigned Destination;
     137             :     /// \brief The type of the dependence.
     138             :     DepType Type;
     139             : 
     140             :     Dependence(unsigned Source, unsigned Destination, DepType Type)
     141         463 :         : Source(Source), Destination(Destination), Type(Type) {}
     142             : 
     143             :     /// \brief Return the source instruction of the dependence.
     144             :     Instruction *getSource(const LoopAccessInfo &LAI) const;
     145             :     /// \brief Return the destination instruction of the dependence.
     146             :     Instruction *getDestination(const LoopAccessInfo &LAI) const;
     147             : 
     148             :     /// \brief Dependence types that don't prevent vectorization.
     149             :     static bool isSafeForVectorization(DepType Type);
     150             : 
     151             :     /// \brief Lexically forward dependence.
     152             :     bool isForward() const;
     153             :     /// \brief Lexically backward dependence.
     154             :     bool isBackward() const;
     155             : 
     156             :     /// \brief May be a lexically backward dependence type (includes Unknown).
     157             :     bool isPossiblyBackward() const;
     158             : 
     159             :     /// \brief 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        3204 :       : PSE(PSE), InnermostLoop(L), AccessIdx(0),
     167             :         ShouldRetryWithRuntimeCheck(false), SafeForVectorization(true),
     168       12816 :         RecordDependences(true) {}
     169             : 
     170             :   /// \brief Register the location (instructions are given increasing numbers)
     171             :   /// of a write access.
     172        3158 :   void addAccess(StoreInst *SI) {
     173        3158 :     Value *Ptr = SI->getPointerOperand();
     174        6316 :     Accesses[MemAccessInfo(Ptr, true)].push_back(AccessIdx);
     175        3158 :     InstMap.push_back(SI);
     176        3158 :     ++AccessIdx;
     177        3158 :   }
     178             : 
     179             :   /// \brief Register the location (instructions are given increasing numbers)
     180             :   /// of a write access.
     181        3538 :   void addAccess(LoadInst *LI) {
     182        3538 :     Value *Ptr = LI->getPointerOperand();
     183        7076 :     Accesses[MemAccessInfo(Ptr, false)].push_back(AccessIdx);
     184        3538 :     InstMap.push_back(LI);
     185        3538 :     ++AccessIdx;
     186        3538 :   }
     187             : 
     188             :   /// \brief 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             :   /// \brief No memory dependence was encountered that would inhibit
     195             :   /// vectorization.
     196             :   bool isSafeForVectorization() const { return SafeForVectorization; }
     197             : 
     198             :   /// \brief 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             :   /// \brief In same cases when the dependency check fails we can still
     203             :   /// vectorize the loop with a dynamic array access check.
     204             :   bool shouldRetryWithRuntimeCheck() { return ShouldRetryWithRuntimeCheck; }
     205             : 
     206             :   /// \brief Returns the memory dependences.  If null is returned we exceeded
     207             :   /// the MaxDependences threshold and this information is not
     208             :   /// available.
     209             :   const SmallVectorImpl<Dependence> *getDependences() const {
     210        2866 :     return RecordDependences ? &Dependences : nullptr;
     211             :   }
     212             : 
     213          30 :   void clearDependences() { Dependences.clear(); }
     214             : 
     215             :   /// \brief The vector of memory access instructions.  The indices are used as
     216             :   /// instruction identifiers in the Dependence class.
     217             :   const SmallVectorImpl<Instruction *> &getMemoryInstructions() const {
     218          93 :     return InstMap;
     219             :   }
     220             : 
     221             :   /// \brief Generate a mapping between the memory instructions and their
     222             :   /// indices according to program order.
     223          28 :   DenseMap<Instruction *, unsigned> generateInstructionOrderMap() const {
     224          28 :     DenseMap<Instruction *, unsigned> OrderMap;
     225             : 
     226         236 :     for (unsigned I = 0; I < InstMap.size(); ++I)
     227         270 :       OrderMap[InstMap[I]] = I;
     228             : 
     229          28 :     return OrderMap;
     230             :   }
     231             : 
     232             :   /// \brief Find the set of instructions that read or write via \p Ptr.
     233             :   SmallVector<Instruction *, 4> getInstructionsForAccess(Value *Ptr,
     234             :                                                          bool isWrite) const;
     235             : 
     236             : private:
     237             :   /// A wrapper around ScalarEvolution, used to add runtime SCEV checks, and
     238             :   /// applies dynamic knowledge to simplify SCEV expressions and convert them
     239             :   /// to a more usable form. We need this in case assumptions about SCEV
     240             :   /// expressions need to be made in order to avoid unknown dependences. For
     241             :   /// example we might assume a unit stride for a pointer in order to prove
     242             :   /// that a memory access is strided and doesn't wrap.
     243             :   PredicatedScalarEvolution &PSE;
     244             :   const Loop *InnermostLoop;
     245             : 
     246             :   /// \brief Maps access locations (ptr, read/write) to program order.
     247             :   DenseMap<MemAccessInfo, std::vector<unsigned> > Accesses;
     248             : 
     249             :   /// \brief Memory access instructions in program order.
     250             :   SmallVector<Instruction *, 16> InstMap;
     251             : 
     252             :   /// \brief The program order index to be used for the next instruction.
     253             :   unsigned AccessIdx;
     254             : 
     255             :   // We can access this many bytes in parallel safely.
     256             :   uint64_t MaxSafeDepDistBytes;
     257             : 
     258             :   /// \brief If we see a non-constant dependence distance we can still try to
     259             :   /// vectorize this loop with runtime checks.
     260             :   bool ShouldRetryWithRuntimeCheck;
     261             : 
     262             :   /// \brief No memory dependence was encountered that would inhibit
     263             :   /// vectorization.
     264             :   bool SafeForVectorization;
     265             : 
     266             :   //// \brief True if Dependences reflects the dependences in the
     267             :   //// loop.  If false we exceeded MaxDependences and
     268             :   //// Dependences is invalid.
     269             :   bool RecordDependences;
     270             : 
     271             :   /// \brief Memory dependences collected during the analysis.  Only valid if
     272             :   /// RecordDependences is true.
     273             :   SmallVector<Dependence, 8> Dependences;
     274             : 
     275             :   /// \brief Check whether there is a plausible dependence between the two
     276             :   /// accesses.
     277             :   ///
     278             :   /// Access \p A must happen before \p B in program order. The two indices
     279             :   /// identify the index into the program order map.
     280             :   ///
     281             :   /// This function checks  whether there is a plausible dependence (or the
     282             :   /// absence of such can't be proved) between the two accesses. If there is a
     283             :   /// plausible dependence but the dependence distance is bigger than one
     284             :   /// element access it records this distance in \p MaxSafeDepDistBytes (if this
     285             :   /// distance is smaller than any other distance encountered so far).
     286             :   /// Otherwise, this function returns true signaling a possible dependence.
     287             :   Dependence::DepType isDependent(const MemAccessInfo &A, unsigned AIdx,
     288             :                                   const MemAccessInfo &B, unsigned BIdx,
     289             :                                   const ValueToValueMap &Strides);
     290             : 
     291             :   /// \brief Check whether the data dependence could prevent store-load
     292             :   /// forwarding.
     293             :   ///
     294             :   /// \return false if we shouldn't vectorize at all or avoid larger
     295             :   /// vectorization factors by limiting MaxSafeDepDistBytes.
     296             :   bool couldPreventStoreLoadForward(uint64_t Distance, uint64_t TypeByteSize);
     297             : };
     298             : 
     299             : /// \brief Holds information about the memory runtime legality checks to verify
     300             : /// that a group of pointers do not overlap.
     301       12816 : class RuntimePointerChecking {
     302             : public:
     303        9114 :   struct PointerInfo {
     304             :     /// Holds the pointer value that we need to check.
     305             :     TrackingVH<Value> PointerValue;
     306             :     /// Holds the smallest byte address accessed by the pointer throughout all
     307             :     /// iterations of the loop.
     308             :     const SCEV *Start;
     309             :     /// Holds the largest byte address accessed by the pointer throughout all
     310             :     /// iterations of the loop, plus 1.
     311             :     const SCEV *End;
     312             :     /// Holds the information if this pointer is used for writing to memory.
     313             :     bool IsWritePtr;
     314             :     /// Holds the id of the set of pointers that could be dependent because of a
     315             :     /// shared underlying object.
     316             :     unsigned DependencySetId;
     317             :     /// Holds the id of the disjoint alias set to which this pointer belongs.
     318             :     unsigned AliasSetId;
     319             :     /// SCEV for the access.
     320             :     const SCEV *Expr;
     321             : 
     322             :     PointerInfo(Value *PointerValue, const SCEV *Start, const SCEV *End,
     323             :                 bool IsWritePtr, unsigned DependencySetId, unsigned AliasSetId,
     324             :                 const SCEV *Expr)
     325        2465 :         : PointerValue(PointerValue), Start(Start), End(End),
     326             :           IsWritePtr(IsWritePtr), DependencySetId(DependencySetId),
     327        4930 :           AliasSetId(AliasSetId), Expr(Expr) {}
     328             :   };
     329             : 
     330       12816 :   RuntimePointerChecking(ScalarEvolution *SE) : Need(false), SE(SE) {}
     331             : 
     332             :   /// Reset the state of the pointer runtime information.
     333             :   void reset() {
     334         241 :     Need = false;
     335         482 :     Pointers.clear();
     336         482 :     Checks.clear();
     337             :   }
     338             : 
     339             :   /// Insert a pointer and calculate the start and end SCEVs.
     340             :   /// We need \p PSE in order to compute the SCEV expression of the pointer
     341             :   /// according to the assumptions that we've made during the analysis.
     342             :   /// The method might also version the pointer stride according to \p Strides,
     343             :   /// and add new predicates to \p PSE.
     344             :   void insert(Loop *Lp, Value *Ptr, bool WritePtr, unsigned DepSetId,
     345             :               unsigned ASId, const ValueToValueMap &Strides,
     346             :               PredicatedScalarEvolution &PSE);
     347             : 
     348             :   /// \brief No run-time memory checking is necessary.
     349             :   bool empty() const { return Pointers.empty(); }
     350             : 
     351             :   /// A grouping of pointers. A single memcheck is required between
     352             :   /// two groups.
     353        8594 :   struct CheckingPtrGroup {
     354             :     /// \brief Create a new pointer checking group containing a single
     355             :     /// pointer, with index \p Index in RtCheck.
     356         767 :     CheckingPtrGroup(unsigned Index, RuntimePointerChecking &RtCheck)
     357        2301 :         : RtCheck(RtCheck), High(RtCheck.Pointers[Index].End),
     358        3068 :           Low(RtCheck.Pointers[Index].Start) {
     359         767 :       Members.push_back(Index);
     360         767 :     }
     361             : 
     362             :     /// \brief Tries to add the pointer recorded in RtCheck at index
     363             :     /// \p Index to this pointer checking group. We can only add a pointer
     364             :     /// to a checking group if we will still be able to get
     365             :     /// the upper and lower bounds of the check. Returns true in case
     366             :     /// of success, false otherwise.
     367             :     bool addPointer(unsigned Index);
     368             : 
     369             :     /// Constitutes the context of this pointer checking group. For each
     370             :     /// pointer that is a member of this group we will retain the index
     371             :     /// at which it appears in RtCheck.
     372             :     RuntimePointerChecking &RtCheck;
     373             :     /// The SCEV expression which represents the upper bound of all the
     374             :     /// pointers in this group.
     375             :     const SCEV *High;
     376             :     /// The SCEV expression which represents the lower bound of all the
     377             :     /// pointers in this group.
     378             :     const SCEV *Low;
     379             :     /// Indices of all the pointers that constitute this grouping.
     380             :     SmallVector<unsigned, 2> Members;
     381             :   };
     382             : 
     383             :   /// \brief A memcheck which made up of a pair of grouped pointers.
     384             :   ///
     385             :   /// These *have* to be const for now, since checks are generated from
     386             :   /// CheckingPtrGroups in LAI::addRuntimeChecks which is a const member
     387             :   /// function.  FIXME: once check-generation is moved inside this class (after
     388             :   /// the PtrPartition hack is removed), we could drop const.
     389             :   typedef std::pair<const CheckingPtrGroup *, const CheckingPtrGroup *>
     390             :       PointerCheck;
     391             : 
     392             :   /// \brief Generate the checks and store it.  This also performs the grouping
     393             :   /// of pointers to reduce the number of memchecks necessary.
     394             :   void generateChecks(MemoryDepChecker::DepCandidates &DepCands,
     395             :                       bool UseDependencies);
     396             : 
     397             :   /// \brief Returns the checks that generateChecks created.
     398             :   const SmallVector<PointerCheck, 4> &getChecks() const { return Checks; }
     399             : 
     400             :   /// \brief Decide if we need to add a check between two groups of pointers,
     401             :   /// according to needsChecking.
     402             :   bool needsChecking(const CheckingPtrGroup &M,
     403             :                      const CheckingPtrGroup &N) const;
     404             : 
     405             :   /// \brief Returns the number of run-time checks required according to
     406             :   /// needsChecking.
     407        1530 :   unsigned getNumberOfChecks() const { return Checks.size(); }
     408             : 
     409             :   /// \brief Print the list run-time memory checks necessary.
     410             :   void print(raw_ostream &OS, unsigned Depth = 0) const;
     411             : 
     412             :   /// Print \p Checks.
     413             :   void printChecks(raw_ostream &OS, const SmallVectorImpl<PointerCheck> &Checks,
     414             :                    unsigned Depth = 0) const;
     415             : 
     416             :   /// This flag indicates if we need to add the runtime check.
     417             :   bool Need;
     418             : 
     419             :   /// Information about the pointers that may require checking.
     420             :   SmallVector<PointerInfo, 2> Pointers;
     421             : 
     422             :   /// Holds a partitioning of pointers into "check groups".
     423             :   SmallVector<CheckingPtrGroup, 2> CheckingGroups;
     424             : 
     425             :   /// \brief Check if pointers are in the same partition
     426             :   ///
     427             :   /// \p PtrToPartition contains the partition number for pointers (-1 if the
     428             :   /// pointer belongs to multiple partitions).
     429             :   static bool
     430             :   arePointersInSamePartition(const SmallVectorImpl<int> &PtrToPartition,
     431             :                              unsigned PtrIdx1, unsigned PtrIdx2);
     432             : 
     433             :   /// \brief Decide whether we need to issue a run-time check for pointer at
     434             :   /// index \p I and \p J to prove their independence.
     435             :   bool needsChecking(unsigned I, unsigned J) const;
     436             : 
     437             :   /// \brief Return PointerInfo for pointer at index \p PtrIdx.
     438             :   const PointerInfo &getPointerInfo(unsigned PtrIdx) const {
     439         846 :     return Pointers[PtrIdx];
     440             :   }
     441             : 
     442             : private:
     443             :   /// \brief Groups pointers such that a single memcheck is required
     444             :   /// between two different groups. This will clear the CheckingGroups vector
     445             :   /// and re-compute it. We will only group dependecies if \p UseDependencies
     446             :   /// is true, otherwise we will create a separate group for each pointer.
     447             :   void groupChecks(MemoryDepChecker::DepCandidates &DepCands,
     448             :                    bool UseDependencies);
     449             : 
     450             :   /// Generate the checks and return them.
     451             :   SmallVector<PointerCheck, 4>
     452             :   generateChecks() const;
     453             : 
     454             :   /// Holds a pointer to the ScalarEvolution analysis.
     455             :   ScalarEvolution *SE;
     456             : 
     457             :   /// \brief Set of run-time checks required to establish independence of
     458             :   /// otherwise may-aliasing pointers in the loop.
     459             :   SmallVector<PointerCheck, 4> Checks;
     460             : };
     461             : 
     462             : /// \brief Drive the analysis of memory accesses in the loop
     463             : ///
     464             : /// This class is responsible for analyzing the memory accesses of a loop.  It
     465             : /// collects the accesses and then its main helper the AccessAnalysis class
     466             : /// finds and categorizes the dependences in buildDependenceSets.
     467             : ///
     468             : /// For memory dependences that can be analyzed at compile time, it determines
     469             : /// whether the dependence is part of cycle inhibiting vectorization.  This work
     470             : /// is delegated to the MemoryDepChecker class.
     471             : ///
     472             : /// For memory dependences that cannot be determined at compile time, it
     473             : /// generates run-time checks to prove independence.  This is done by
     474             : /// AccessAnalysis::canCheckPtrAtRT and the checks are maintained by the
     475             : /// RuntimePointerCheck class.
     476             : ///
     477             : /// If pointers can wrap or can't be expressed as affine AddRec expressions by
     478             : /// ScalarEvolution, we will generate run-time checks by emitting a
     479             : /// SCEVUnionPredicate.
     480             : ///
     481             : /// Checks for both memory dependences and the SCEV predicates contained in the
     482             : /// PSE must be emitted in order for the results of this analysis to be valid.
     483       15038 : class LoopAccessInfo {
     484             : public:
     485             :   LoopAccessInfo(Loop *L, ScalarEvolution *SE, const TargetLibraryInfo *TLI,
     486             :                  AliasAnalysis *AA, DominatorTree *DT, LoopInfo *LI);
     487             : 
     488             :   /// Return true we can analyze the memory accesses in the loop and there are
     489             :   /// no memory dependence cycles.
     490             :   bool canVectorizeMemory() const { return CanVecMem; }
     491             : 
     492             :   const RuntimePointerChecking *getRuntimePointerChecking() const {
     493        2356 :     return PtrRtChecking.get();
     494             :   }
     495             : 
     496             :   /// \brief Number of memchecks required to prove independence of otherwise
     497             :   /// may-alias pointers.
     498             :   unsigned getNumRuntimePointerChecks() const {
     499        2295 :     return PtrRtChecking->getNumberOfChecks();
     500             :   }
     501             : 
     502             :   /// Return true if the block BB needs to be predicated in order for the loop
     503             :   /// to be vectorized.
     504             :   static bool blockNeedsPredication(BasicBlock *BB, Loop *TheLoop,
     505             :                                     DominatorTree *DT);
     506             : 
     507             :   /// Returns true if the value V is uniform within the loop.
     508             :   bool isUniform(Value *V) const;
     509             : 
     510             :   uint64_t getMaxSafeDepDistBytes() const { return MaxSafeDepDistBytes; }
     511             :   unsigned getNumStores() const { return NumStores; }
     512             :   unsigned getNumLoads() const { return NumLoads;}
     513             : 
     514             :   /// \brief Add code that checks at runtime if the accessed arrays overlap.
     515             :   ///
     516             :   /// Returns a pair of instructions where the first element is the first
     517             :   /// instruction generated in possibly a sequence of instructions and the
     518             :   /// second value is the final comparator value or NULL if no check is needed.
     519             :   std::pair<Instruction *, Instruction *>
     520             :   addRuntimeChecks(Instruction *Loc) const;
     521             : 
     522             :   /// \brief Generete the instructions for the checks in \p PointerChecks.
     523             :   ///
     524             :   /// Returns a pair of instructions where the first element is the first
     525             :   /// instruction generated in possibly a sequence of instructions and the
     526             :   /// second value is the final comparator value or NULL if no check is needed.
     527             :   std::pair<Instruction *, Instruction *>
     528             :   addRuntimeChecks(Instruction *Loc,
     529             :                    const SmallVectorImpl<RuntimePointerChecking::PointerCheck>
     530             :                        &PointerChecks) const;
     531             : 
     532             :   /// \brief The diagnostics report generated for the analysis.  E.g. why we
     533             :   /// couldn't analyze the loop.
     534        1950 :   const OptimizationRemarkAnalysis *getReport() const { return Report.get(); }
     535             : 
     536             :   /// \brief the Memory Dependence Checker which can determine the
     537             :   /// loop-independent and loop-carried dependences between memory accesses.
     538        6320 :   const MemoryDepChecker &getDepChecker() const { return *DepChecker; }
     539             : 
     540             :   /// \brief Return the list of instructions that use \p Ptr to read or write
     541             :   /// memory.
     542             :   SmallVector<Instruction *, 4> getInstructionsForAccess(Value *Ptr,
     543             :                                                          bool isWrite) const {
     544         224 :     return DepChecker->getInstructionsForAccess(Ptr, isWrite);
     545             :   }
     546             : 
     547             :   /// \brief If an access has a symbolic strides, this maps the pointer value to
     548             :   /// the stride symbol.
     549        5113 :   const ValueToValueMap &getSymbolicStrides() const { return SymbolicStrides; }
     550             : 
     551             :   /// \brief Pointer has a symbolic stride.
     552        6738 :   bool hasStride(Value *V) const { return StrideSet.count(V); }
     553             : 
     554             :   /// \brief Print the information about the memory accesses in the loop.
     555             :   void print(raw_ostream &OS, unsigned Depth = 0) const;
     556             : 
     557             :   /// \brief Checks existence of store to invariant address inside loop.
     558             :   /// If the loop has any store to invariant address, then it returns true,
     559             :   /// else returns false.
     560             :   bool hasStoreToLoopInvariantAddress() const {
     561             :     return StoreToLoopInvariantAddress;
     562             :   }
     563             : 
     564             :   /// Used to add runtime SCEV checks. Simplifies SCEV expressions and converts
     565             :   /// them to a more usable form.  All SCEV expressions during the analysis
     566             :   /// should be re-written (and therefore simplified) according to PSE.
     567             :   /// A user of LoopAccessAnalysis will need to emit the runtime checks
     568             :   /// associated with this predicate.
     569        6056 :   const PredicatedScalarEvolution &getPSE() const { return *PSE; }
     570             : 
     571             : private:
     572             :   /// \brief Analyze the loop.
     573             :   void analyzeLoop(AliasAnalysis *AA, LoopInfo *LI,
     574             :                    const TargetLibraryInfo *TLI, DominatorTree *DT);
     575             : 
     576             :   /// \brief Check if the structure of the loop allows it to be analyzed by this
     577             :   /// pass.
     578             :   bool canAnalyzeLoop();
     579             : 
     580             :   /// \brief Save the analysis remark.
     581             :   ///
     582             :   /// LAA does not directly emits the remarks.  Instead it stores it which the
     583             :   /// client can retrieve and presents as its own analysis
     584             :   /// (e.g. -Rpass-analysis=loop-vectorize).
     585             :   OptimizationRemarkAnalysis &recordAnalysis(StringRef RemarkName,
     586             :                                              Instruction *Instr = nullptr);
     587             : 
     588             :   /// \brief Collect memory access with loop invariant strides.
     589             :   ///
     590             :   /// Looks for accesses like "a[i * StrideA]" where "StrideA" is loop
     591             :   /// invariant.
     592             :   void collectStridedAccess(Value *LoadOrStoreInst);
     593             : 
     594             :   std::unique_ptr<PredicatedScalarEvolution> PSE;
     595             : 
     596             :   /// We need to check that all of the pointers in this list are disjoint
     597             :   /// at runtime. Using std::unique_ptr to make using move ctor simpler.
     598             :   std::unique_ptr<RuntimePointerChecking> PtrRtChecking;
     599             : 
     600             :   /// \brief the Memory Dependence Checker which can determine the
     601             :   /// loop-independent and loop-carried dependences between memory accesses.
     602             :   std::unique_ptr<MemoryDepChecker> DepChecker;
     603             : 
     604             :   Loop *TheLoop;
     605             : 
     606             :   unsigned NumLoads;
     607             :   unsigned NumStores;
     608             : 
     609             :   uint64_t MaxSafeDepDistBytes;
     610             : 
     611             :   /// \brief Cache the result of analyzeLoop.
     612             :   bool CanVecMem;
     613             : 
     614             :   /// \brief Indicator for storing to uniform addresses.
     615             :   /// If a loop has write to a loop invariant address then it should be true.
     616             :   bool StoreToLoopInvariantAddress;
     617             : 
     618             :   /// \brief The diagnostics report generated for the analysis.  E.g. why we
     619             :   /// couldn't analyze the loop.
     620             :   std::unique_ptr<OptimizationRemarkAnalysis> Report;
     621             : 
     622             :   /// \brief If an access has a symbolic strides, this maps the pointer value to
     623             :   /// the stride symbol.
     624             :   ValueToValueMap SymbolicStrides;
     625             : 
     626             :   /// \brief Set of symbolic strides values.
     627             :   SmallPtrSet<Value *, 8> StrideSet;
     628             : };
     629             : 
     630             : Value *stripIntegerCast(Value *V);
     631             : 
     632             : /// \brief Return the SCEV corresponding to a pointer with the symbolic stride
     633             : /// replaced with constant one, assuming the SCEV predicate associated with
     634             : /// \p PSE is true.
     635             : ///
     636             : /// If necessary this method will version the stride of the pointer according
     637             : /// to \p PtrToStride and therefore add further predicates to \p PSE.
     638             : ///
     639             : /// If \p OrigPtr is not null, use it to look up the stride value instead of \p
     640             : /// Ptr.  \p PtrToStride provides the mapping between the pointer value and its
     641             : /// stride as collected by LoopVectorizationLegality::collectStridedAccess.
     642             : const SCEV *replaceSymbolicStrideSCEV(PredicatedScalarEvolution &PSE,
     643             :                                       const ValueToValueMap &PtrToStride,
     644             :                                       Value *Ptr, Value *OrigPtr = nullptr);
     645             : 
     646             : /// \brief If the pointer has a constant stride return it in units of its
     647             : /// element size.  Otherwise return zero.
     648             : ///
     649             : /// Ensure that it does not wrap in the address space, assuming the predicate
     650             : /// associated with \p PSE is true.
     651             : ///
     652             : /// If necessary this method will version the stride of the pointer according
     653             : /// to \p PtrToStride and therefore add further predicates to \p PSE.
     654             : /// The \p Assume parameter indicates if we are allowed to make additional
     655             : /// run-time assumptions.
     656             : int64_t getPtrStride(PredicatedScalarEvolution &PSE, Value *Ptr, const Loop *Lp,
     657             :                      const ValueToValueMap &StridesMap = ValueToValueMap(),
     658             :                      bool Assume = false, bool ShouldCheckWrap = true);
     659             : 
     660             : /// \brief Returns true if the memory operations \p A and \p B are consecutive.
     661             : /// This is a simple API that does not depend on the analysis pass. 
     662             : bool isConsecutiveAccess(Value *A, Value *B, const DataLayout &DL,
     663             :                          ScalarEvolution &SE, bool CheckType = true);
     664             : 
     665             : /// \brief This analysis provides dependence information for the memory accesses
     666             : /// of a loop.
     667             : ///
     668             : /// It runs the analysis for a loop on demand.  This can be initiated by
     669             : /// querying the loop access info via LAA::getInfo.  getInfo return a
     670             : /// LoopAccessInfo object.  See this class for the specifics of what information
     671             : /// is provided.
     672       12648 : class LoopAccessLegacyAnalysis : public FunctionPass {
     673             : public:
     674             :   static char ID;
     675             : 
     676        9486 :   LoopAccessLegacyAnalysis() : FunctionPass(ID) {
     677        3162 :     initializeLoopAccessLegacyAnalysisPass(*PassRegistry::getPassRegistry());
     678        3162 :   }
     679             : 
     680             :   bool runOnFunction(Function &F) override;
     681             : 
     682             :   void getAnalysisUsage(AnalysisUsage &AU) const override;
     683             : 
     684             :   /// \brief Query the result of the loop access information for the loop \p L.
     685             :   ///
     686             :   /// If there is no cached result available run the analysis.
     687             :   const LoopAccessInfo &getInfo(Loop *L);
     688             : 
     689       35116 :   void releaseMemory() override {
     690             :     // Invalidate the cache when the pass is freed.
     691       35116 :     LoopAccessInfoMap.clear();
     692       35116 :   }
     693             : 
     694             :   /// \brief Print the result of the analysis when invoked with -analyze.
     695             :   void print(raw_ostream &OS, const Module *M = nullptr) const override;
     696             : 
     697             : private:
     698             :   /// \brief The cache.
     699             :   DenseMap<Loop *, std::unique_ptr<LoopAccessInfo>> LoopAccessInfoMap;
     700             : 
     701             :   // The used analysis passes.
     702             :   ScalarEvolution *SE;
     703             :   const TargetLibraryInfo *TLI;
     704             :   AliasAnalysis *AA;
     705             :   DominatorTree *DT;
     706             :   LoopInfo *LI;
     707             : };
     708             : 
     709             : /// \brief This analysis provides dependence information for the memory
     710             : /// accesses of a loop.
     711             : ///
     712             : /// It runs the analysis for a loop on demand.  This can be initiated by
     713             : /// querying the loop access info via AM.getResult<LoopAccessAnalysis>. 
     714             : /// getResult return a LoopAccessInfo object.  See this class for the
     715             : /// specifics of what information is provided.
     716             : class LoopAccessAnalysis
     717             :     : public AnalysisInfoMixin<LoopAccessAnalysis> {
     718             :   friend AnalysisInfoMixin<LoopAccessAnalysis>;
     719             :   static AnalysisKey Key;
     720             : 
     721             : public:
     722             :   typedef LoopAccessInfo Result;
     723             : 
     724             :   Result run(Loop &L, LoopAnalysisManager &AM, LoopStandardAnalysisResults &AR);
     725             : };
     726             : 
     727             : inline Instruction *MemoryDepChecker::Dependence::getSource(
     728             :     const LoopAccessInfo &LAI) const {
     729         465 :   return LAI.getDepChecker().getMemoryInstructions()[Source];
     730             : }
     731             : 
     732             : inline Instruction *MemoryDepChecker::Dependence::getDestination(
     733             :     const LoopAccessInfo &LAI) const {
     734         465 :   return LAI.getDepChecker().getMemoryInstructions()[Destination];
     735             : }
     736             : 
     737             : } // End llvm namespace
     738             : 
     739             : #endif

Generated by: LCOV version 1.13