#include "llvm/Analysis/AliasSetTracker.h"
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/IR/ValueHandle.h"
+#include "llvm/Pass.h"
#include "llvm/Support/raw_ostream.h"
namespace llvm {
/// Optimization analysis message produced during vectorization. Messages inform
/// the user why vectorization did not occur.
-class VectorizationReport {
+class LoopAccessReport {
std::string Message;
- Instruction *Instr;
+ const Instruction *Instr;
+
+protected:
+ LoopAccessReport(const Twine &Message, const Instruction *I)
+ : Message(Message.str()), Instr(I) {}
public:
- VectorizationReport(Instruction *I = nullptr)
- : Message("loop not vectorized: "), Instr(I) {}
+ LoopAccessReport(const Instruction *I = nullptr) : Instr(I) {}
- template <typename A> VectorizationReport &operator<<(const A &Value) {
+ template <typename A> LoopAccessReport &operator<<(const A &Value) {
raw_string_ostream Out(Message);
Out << Value;
return *this;
}
- Instruction *getInstr() { return Instr; }
+ const Instruction *getInstr() const { return Instr; }
std::string &str() { return Message; }
+ const std::string &str() const { return Message; }
operator Twine() { return Message; }
- /// \brief Emit an analysis note with the debug location from the instruction
- /// in \p Message if available. Otherwise use the location of \p TheLoop.
- static void emitAnalysis(VectorizationReport &Message,
+ /// \brief Emit an analysis note for \p PassName with the debug location from
+ /// the instruction in \p Message if available. Otherwise use the location of
+ /// \p TheLoop.
+ static void emitAnalysis(const LoopAccessReport &Message,
const Function *TheFunction,
- const Loop *TheLoop);
+ const Loop *TheLoop,
+ const char *PassName);
};
/// \brief Collection of parameters shared beetween the Loop Vectorizer and the
/// \\brief When performing memory disambiguation checks at runtime do not
/// make more than this number of comparisons.
- static const unsigned RuntimeMemoryCheckThreshold;
+ static unsigned RuntimeMemoryCheckThreshold;
+};
+
+/// \brief Checks memory dependences among accesses to the same underlying
+/// object to determine whether there vectorization is legal or not (and at
+/// which vectorization factor).
+///
+/// Note: This class will compute a conservative dependence for access to
+/// different underlying pointers. Clients, such as the loop vectorizer, will
+/// sometimes deal these potential dependencies by emitting runtime checks.
+///
+/// We use the ScalarEvolution framework to symbolically evalutate access
+/// functions pairs. Since we currently don't restructure the loop we can rely
+/// on the program order of memory accesses to determine their safety.
+/// At the moment we will only deem accesses as safe for:
+/// * A negative constant distance assuming program order.
+///
+/// Safe: tmp = a[i + 1]; OR a[i + 1] = x;
+/// a[i] = tmp; y = a[i];
+///
+/// The latter case is safe because later checks guarantuee that there can't
+/// be a cycle through a phi node (that is, we check that "x" and "y" is not
+/// the same variable: a header phi can only be an induction or a reduction, a
+/// reduction can't have a memory sink, an induction can't have a memory
+/// source). This is important and must not be violated (or we have to
+/// resort to checking for cycles through memory).
+///
+/// * A positive constant distance assuming program order that is bigger
+/// than the biggest memory access.
+///
+/// tmp = a[i] OR b[i] = x
+/// a[i+2] = tmp y = b[i+2];
+///
+/// Safe distance: 2 x sizeof(a[0]), and 2 x sizeof(b[0]), respectively.
+///
+/// * Zero distances and all accesses have the same size.
+///
+class MemoryDepChecker {
+public:
+ typedef PointerIntPair<Value *, 1, bool> MemAccessInfo;
+ typedef SmallPtrSet<MemAccessInfo, 8> MemAccessInfoSet;
+ /// \brief Set of potential dependent memory accesses.
+ typedef EquivalenceClasses<MemAccessInfo> DepCandidates;
+
+ /// \brief Dependece between memory access instructions.
+ struct Dependence {
+ /// \brief The type of the dependence.
+ enum DepType {
+ // No dependence.
+ NoDep,
+ // We couldn't determine the direction or the distance.
+ Unknown,
+ // Lexically forward.
+ Forward,
+ // Forward, but if vectorized, is likely to prevent store-to-load
+ // forwarding.
+ ForwardButPreventsForwarding,
+ // Lexically backward.
+ Backward,
+ // Backward, but the distance allows a vectorization factor of
+ // MaxSafeDepDistBytes.
+ BackwardVectorizable,
+ // Same, but may prevent store-to-load forwarding.
+ BackwardVectorizableButPreventsForwarding
+ };
+
+ /// \brief String version of the types.
+ static const char *DepName[];
+
+ /// \brief Index of the source of the dependence in the InstMap vector.
+ unsigned Source;
+ /// \brief Index of the destination of the dependence in the InstMap vector.
+ unsigned Destination;
+ /// \brief The type of the dependence.
+ DepType Type;
+
+ Dependence(unsigned Source, unsigned Destination, DepType Type)
+ : Source(Source), Destination(Destination), Type(Type) {}
+
+ /// \brief Dependence types that don't prevent vectorization.
+ static bool isSafeForVectorization(DepType Type);
+
+ /// \brief Dependence types that can be queried from the analysis.
+ static bool isInterestingDependence(DepType Type);
+
+ /// \brief Lexically backward dependence types.
+ bool isPossiblyBackward() const;
+
+ /// \brief Print the dependence. \p Instr is used to map the instruction
+ /// indices to instructions.
+ void print(raw_ostream &OS, unsigned Depth,
+ const SmallVectorImpl<Instruction *> &Instrs) const;
+ };
+
+ MemoryDepChecker(ScalarEvolution *Se, const Loop *L)
+ : SE(Se), InnermostLoop(L), AccessIdx(0),
+ ShouldRetryWithRuntimeCheck(false), SafeForVectorization(true),
+ RecordInterestingDependences(true) {}
+
+ /// \brief Register the location (instructions are given increasing numbers)
+ /// of a write access.
+ void addAccess(StoreInst *SI) {
+ Value *Ptr = SI->getPointerOperand();
+ Accesses[MemAccessInfo(Ptr, true)].push_back(AccessIdx);
+ InstMap.push_back(SI);
+ ++AccessIdx;
+ }
+
+ /// \brief Register the location (instructions are given increasing numbers)
+ /// of a write access.
+ void addAccess(LoadInst *LI) {
+ Value *Ptr = LI->getPointerOperand();
+ Accesses[MemAccessInfo(Ptr, false)].push_back(AccessIdx);
+ InstMap.push_back(LI);
+ ++AccessIdx;
+ }
+
+ /// \brief Check whether the dependencies between the accesses are safe.
+ ///
+ /// Only checks sets with elements in \p CheckDeps.
+ bool areDepsSafe(DepCandidates &AccessSets, MemAccessInfoSet &CheckDeps,
+ const ValueToValueMap &Strides);
+
+ /// \brief No memory dependence was encountered that would inhibit
+ /// vectorization.
+ bool isSafeForVectorization() const { return SafeForVectorization; }
+
+ /// \brief The maximum number of bytes of a vector register we can vectorize
+ /// the accesses safely with.
+ unsigned getMaxSafeDepDistBytes() { return MaxSafeDepDistBytes; }
+
+ /// \brief In same cases when the dependency check fails we can still
+ /// vectorize the loop with a dynamic array access check.
+ bool shouldRetryWithRuntimeCheck() { return ShouldRetryWithRuntimeCheck; }
+
+ /// \brief Returns the interesting dependences. If null is returned we
+ /// exceeded the MaxInterestingDependence threshold and this information is
+ /// not available.
+ const SmallVectorImpl<Dependence> *getInterestingDependences() const {
+ return RecordInterestingDependences ? &InterestingDependences : nullptr;
+ }
+
+ void clearInterestingDependences() { InterestingDependences.clear(); }
+
+ /// \brief The vector of memory access instructions. The indices are used as
+ /// instruction identifiers in the Dependence class.
+ const SmallVectorImpl<Instruction *> &getMemoryInstructions() const {
+ return InstMap;
+ }
+
+ /// \brief Find the set of instructions that read or write via \p Ptr.
+ SmallVector<Instruction *, 4> getInstructionsForAccess(Value *Ptr,
+ bool isWrite) const;
+
+private:
+ ScalarEvolution *SE;
+ const Loop *InnermostLoop;
+
+ /// \brief Maps access locations (ptr, read/write) to program order.
+ DenseMap<MemAccessInfo, std::vector<unsigned> > Accesses;
+
+ /// \brief Memory access instructions in program order.
+ SmallVector<Instruction *, 16> InstMap;
+
+ /// \brief The program order index to be used for the next instruction.
+ unsigned AccessIdx;
+
+ // We can access this many bytes in parallel safely.
+ unsigned MaxSafeDepDistBytes;
+
+ /// \brief If we see a non-constant dependence distance we can still try to
+ /// vectorize this loop with runtime checks.
+ bool ShouldRetryWithRuntimeCheck;
+
+ /// \brief No memory dependence was encountered that would inhibit
+ /// vectorization.
+ bool SafeForVectorization;
+
+ //// \brief True if InterestingDependences reflects the dependences in the
+ //// loop. If false we exceeded MaxInterestingDependence and
+ //// InterestingDependences is invalid.
+ bool RecordInterestingDependences;
+
+ /// \brief Interesting memory dependences collected during the analysis as
+ /// defined by isInterestingDependence. Only valid if
+ /// RecordInterestingDependences is true.
+ SmallVector<Dependence, 8> InterestingDependences;
+
+ /// \brief Check whether there is a plausible dependence between the two
+ /// accesses.
+ ///
+ /// Access \p A must happen before \p B in program order. The two indices
+ /// identify the index into the program order map.
+ ///
+ /// This function checks whether there is a plausible dependence (or the
+ /// absence of such can't be proved) between the two accesses. If there is a
+ /// plausible dependence but the dependence distance is bigger than one
+ /// element access it records this distance in \p MaxSafeDepDistBytes (if this
+ /// distance is smaller than any other distance encountered so far).
+ /// Otherwise, this function returns true signaling a possible dependence.
+ Dependence::DepType isDependent(const MemAccessInfo &A, unsigned AIdx,
+ const MemAccessInfo &B, unsigned BIdx,
+ const ValueToValueMap &Strides);
+
+ /// \brief Check whether the data dependence could prevent store-load
+ /// forwarding.
+ bool couldPreventStoreLoadForward(unsigned Distance, unsigned TypeByteSize);
+};
+
+/// \brief Holds information about the memory runtime legality checks to verify
+/// that a group of pointers do not overlap.
+class RuntimePointerChecking {
+public:
+ struct PointerInfo {
+ /// Holds the pointer value that we need to check.
+ TrackingVH<Value> PointerValue;
+ /// Holds the pointer value at the beginning of the loop.
+ const SCEV *Start;
+ /// Holds the pointer value at the end of the loop.
+ const SCEV *End;
+ /// Holds the information if this pointer is used for writing to memory.
+ bool IsWritePtr;
+ /// Holds the id of the set of pointers that could be dependent because of a
+ /// shared underlying object.
+ unsigned DependencySetId;
+ /// Holds the id of the disjoint alias set to which this pointer belongs.
+ unsigned AliasSetId;
+ /// SCEV for the access.
+ const SCEV *Expr;
+
+ PointerInfo(Value *PointerValue, const SCEV *Start, const SCEV *End,
+ bool IsWritePtr, unsigned DependencySetId, unsigned AliasSetId,
+ const SCEV *Expr)
+ : PointerValue(PointerValue), Start(Start), End(End),
+ IsWritePtr(IsWritePtr), DependencySetId(DependencySetId),
+ AliasSetId(AliasSetId), Expr(Expr) {}
+ };
+
+ RuntimePointerChecking(ScalarEvolution *SE) : Need(false), SE(SE) {}
+
+ /// Reset the state of the pointer runtime information.
+ void reset() {
+ Need = false;
+ Pointers.clear();
+ Checks.clear();
+ }
+
+ /// Insert a pointer and calculate the start and end SCEVs.
+ void insert(Loop *Lp, Value *Ptr, bool WritePtr, unsigned DepSetId,
+ unsigned ASId, const ValueToValueMap &Strides);
+
+ /// \brief No run-time memory checking is necessary.
+ bool empty() const { return Pointers.empty(); }
+
+ /// A grouping of pointers. A single memcheck is required between
+ /// two groups.
+ struct CheckingPtrGroup {
+ /// \brief Create a new pointer checking group containing a single
+ /// pointer, with index \p Index in RtCheck.
+ CheckingPtrGroup(unsigned Index, RuntimePointerChecking &RtCheck)
+ : RtCheck(RtCheck), High(RtCheck.Pointers[Index].End),
+ Low(RtCheck.Pointers[Index].Start) {
+ Members.push_back(Index);
+ }
+
+ /// \brief Tries to add the pointer recorded in RtCheck at index
+ /// \p Index to this pointer checking group. We can only add a pointer
+ /// to a checking group if we will still be able to get
+ /// the upper and lower bounds of the check. Returns true in case
+ /// of success, false otherwise.
+ bool addPointer(unsigned Index);
+
+ /// Constitutes the context of this pointer checking group. For each
+ /// pointer that is a member of this group we will retain the index
+ /// at which it appears in RtCheck.
+ RuntimePointerChecking &RtCheck;
+ /// The SCEV expression which represents the upper bound of all the
+ /// pointers in this group.
+ const SCEV *High;
+ /// The SCEV expression which represents the lower bound of all the
+ /// pointers in this group.
+ const SCEV *Low;
+ /// Indices of all the pointers that constitute this grouping.
+ SmallVector<unsigned, 2> Members;
+ };
+
+ /// \brief A memcheck which made up of a pair of grouped pointers.
+ ///
+ /// These *have* to be const for now, since checks are generated from
+ /// CheckingPtrGroups in LAI::addRuntimeCheck which is a const member
+ /// function. FIXME: once check-generation is moved inside this class (after
+ /// the PtrPartition hack is removed), we could drop const.
+ typedef std::pair<const CheckingPtrGroup *, const CheckingPtrGroup *>
+ PointerCheck;
+
+ /// \brief Generate the checks and store it. This also performs the grouping
+ /// of pointers to reduce the number of memchecks necessary.
+ void generateChecks(MemoryDepChecker::DepCandidates &DepCands,
+ bool UseDependencies);
+
+ /// \brief Returns the checks that generateChecks created.
+ const SmallVectorImpl<PointerCheck> &getChecks() const { return Checks; }
+
+ /// \brief Decide if we need to add a check between two groups of pointers,
+ /// according to needsChecking.
+ bool needsChecking(const CheckingPtrGroup &M, const CheckingPtrGroup &N,
+ const SmallVectorImpl<int> *PtrPartition) const;
+
+ /// \brief Returns the number of run-time checks required according to
+ /// needsChecking.
+ unsigned getNumberOfChecks() const { return Checks.size(); }
+
+ /// \brief Print the list run-time memory checks necessary.
+ void print(raw_ostream &OS, unsigned Depth = 0) const;
+
+ /// Print \p Checks.
+ void printChecks(raw_ostream &OS, const SmallVectorImpl<PointerCheck> &Checks,
+ unsigned Depth = 0) const;
+
+ /// This flag indicates if we need to add the runtime check.
+ bool Need;
+
+ /// Information about the pointers that may require checking.
+ SmallVector<PointerInfo, 2> Pointers;
+
+ /// Holds a partitioning of pointers into "check groups".
+ SmallVector<CheckingPtrGroup, 2> CheckingGroups;
+
+ /// \brief Check if pointers are in the same partition
+ ///
+ /// \p PtrToPartition contains the partition number for pointers (-1 if the
+ /// pointer belongs to multiple partitions).
+ static bool
+ arePointersInSamePartition(const SmallVectorImpl<int> &PtrToPartition,
+ unsigned PtrIdx1, unsigned PtrIdx2);
+
+ /// \brief Decide whether we need to issue a run-time check for pointer at
+ /// index \p I and \p J to prove their independence.
+ ///
+ /// If \p PtrPartition is set, it contains the partition number for
+ /// pointers (-1 if the pointer belongs to multiple partitions). In this
+ /// case omit checks between pointers belonging to the same partition.
+ bool needsChecking(unsigned I, unsigned J,
+ const SmallVectorImpl<int> *PtrPartition = nullptr) const;
+
+private:
+ /// \brief Groups pointers such that a single memcheck is required
+ /// between two different groups. This will clear the CheckingGroups vector
+ /// and re-compute it. We will only group dependecies if \p UseDependencies
+ /// is true, otherwise we will create a separate group for each pointer.
+ void groupChecks(MemoryDepChecker::DepCandidates &DepCands,
+ bool UseDependencies);
+
+ /// Generate the checks and return them.
+ ///
+ /// \p PtrToPartition contains the partition number for pointers. If passed,
+ /// omit checks between pointers belonging to the same partition. Partition
+ /// number -1 means that the pointer is used in multiple partitions. In this
+ /// case we can't safely omit the check.
+ SmallVector<PointerCheck, 4>
+ generateChecks(const SmallVectorImpl<int> *PtrPartition = nullptr) const;
+
+ /// Holds a pointer to the ScalarEvolution analysis.
+ ScalarEvolution *SE;
+
+ /// \brief Set of run-time checks required to establish independence of
+ /// otherwise may-aliasing pointers in the loop.
+ SmallVector<PointerCheck, 4> Checks;
};
/// \brief Drive the analysis of memory accesses in the loop
/// RuntimePointerCheck class.
class LoopAccessInfo {
public:
- /// This struct holds information about the memory runtime legality check that
- /// a group of pointers do not overlap.
- struct RuntimePointerCheck {
- RuntimePointerCheck() : Need(false) {}
-
- /// Reset the state of the pointer runtime information.
- void reset() {
- Need = false;
- Pointers.clear();
- Starts.clear();
- Ends.clear();
- IsWritePtr.clear();
- DependencySetId.clear();
- AliasSetId.clear();
- }
-
- /// Insert a pointer and calculate the start and end SCEVs.
- void insert(ScalarEvolution *SE, Loop *Lp, Value *Ptr, bool WritePtr,
- unsigned DepSetId, unsigned ASId, ValueToValueMap &Strides);
-
- /// \brief Decide whether we need to issue a run-time check for pointer at
- /// index \p I and \p J to prove their independence.
- bool needsChecking(unsigned I, unsigned J) const;
-
- /// This flag indicates if we need to add the runtime check.
- bool Need;
- /// Holds the pointers that we need to check.
- SmallVector<TrackingVH<Value>, 2> Pointers;
- /// Holds the pointer value at the beginning of the loop.
- SmallVector<const SCEV*, 2> Starts;
- /// Holds the pointer value at the end of the loop.
- SmallVector<const SCEV*, 2> Ends;
- /// Holds the information if this pointer is used for writing to memory.
- SmallVector<bool, 2> IsWritePtr;
- /// Holds the id of the set of pointers that could be dependent because of a
- /// shared underlying object.
- SmallVector<unsigned, 2> DependencySetId;
- /// Holds the id of the disjoint alias set to which this pointer belongs.
- SmallVector<unsigned, 2> AliasSetId;
- };
-
- LoopAccessInfo(Loop *L, ScalarEvolution *SE, const DataLayout *DL,
+ LoopAccessInfo(Loop *L, ScalarEvolution *SE, const DataLayout &DL,
const TargetLibraryInfo *TLI, AliasAnalysis *AA,
- DominatorTree *DT) :
- TheLoop(L), SE(SE), DL(DL), TLI(TLI), AA(AA), DT(DT), NumLoads(0),
- NumStores(0), MaxSafeDepDistBytes(-1U), CanVecMem(false) {}
-
- /// \brief Analyze the loop. Replaces symbolic strides using Strides.
- void analyzeLoop(ValueToValueMap &Strides);
+ DominatorTree *DT, LoopInfo *LI,
+ const ValueToValueMap &Strides);
/// Return true we can analyze the memory accesses in the loop and there are
/// no memory dependence cycles.
- bool canVectorizeMemory() { return CanVecMem; }
+ bool canVectorizeMemory() const { return CanVecMem; }
+
+ const RuntimePointerChecking *getRuntimePointerChecking() const {
+ return &PtrRtChecking;
+ }
- RuntimePointerCheck *getRuntimePointerCheck() { return &PtrRtCheck; }
+ /// \brief Number of memchecks required to prove independence of otherwise
+ /// may-alias pointers.
+ unsigned getNumRuntimePointerChecks() const {
+ return PtrRtChecking.getNumberOfChecks();
+ }
/// Return true if the block BB needs to be predicated in order for the loop
/// to be vectorized.
DominatorTree *DT);
/// Returns true if the value V is uniform within the loop.
- bool isUniform(Value *V);
+ bool isUniform(Value *V) const;
unsigned getMaxSafeDepDistBytes() const { return MaxSafeDepDistBytes; }
unsigned getNumStores() const { return NumStores; }
/// Returns a pair of instructions where the first element is the first
/// instruction generated in possibly a sequence of instructions and the
/// second value is the final comparator value or NULL if no check is needed.
- std::pair<Instruction *, Instruction *> addRuntimeCheck(Instruction *Loc);
+ std::pair<Instruction *, Instruction *>
+ addRuntimeCheck(Instruction *Loc) const;
+
+ /// \brief Generete the instructions for the checks in \p PointerChecks.
+ ///
+ /// Returns a pair of instructions where the first element is the first
+ /// instruction generated in possibly a sequence of instructions and the
+ /// second value is the final comparator value or NULL if no check is needed.
+ std::pair<Instruction *, Instruction *>
+ addRuntimeCheck(Instruction *Loc,
+ const SmallVectorImpl<RuntimePointerChecking::PointerCheck>
+ &PointerChecks) const;
/// \brief The diagnostics report generated for the analysis. E.g. why we
/// couldn't analyze the loop.
- Optional<VectorizationReport> &getReport() { return Report; }
+ const Optional<LoopAccessReport> &getReport() const { return Report; }
+
+ /// \brief the Memory Dependence Checker which can determine the
+ /// loop-independent and loop-carried dependences between memory accesses.
+ const MemoryDepChecker &getDepChecker() const { return DepChecker; }
+
+ /// \brief Return the list of instructions that use \p Ptr to read or write
+ /// memory.
+ SmallVector<Instruction *, 4> getInstructionsForAccess(Value *Ptr,
+ bool isWrite) const {
+ return DepChecker.getInstructionsForAccess(Ptr, isWrite);
+ }
+
+ /// \brief Print the information about the memory accesses in the loop.
+ void print(raw_ostream &OS, unsigned Depth = 0) const;
+
+ /// \brief Used to ensure that if the analysis was run with speculating the
+ /// value of symbolic strides, the client queries it with the same assumption.
+ /// Only used in DEBUG build but we don't want NDEBUG-dependent ABI.
+ unsigned NumSymbolicStrides;
+
+ /// \brief Checks existence of store to invariant address inside loop.
+ /// If the loop has any store to invariant address, then it returns true,
+ /// else returns false.
+ bool hasStoreToLoopInvariantAddress() const {
+ return StoreToLoopInvariantAddress;
+ }
private:
- void emitAnalysis(VectorizationReport &Message);
+ /// \brief Analyze the loop. Substitute symbolic strides using Strides.
+ void analyzeLoop(const ValueToValueMap &Strides);
+
+ /// \brief Check if the structure of the loop allows it to be analyzed by this
+ /// pass.
+ bool canAnalyzeLoop();
+
+ void emitAnalysis(LoopAccessReport &Message);
/// We need to check that all of the pointers in this list are disjoint
/// at runtime.
- RuntimePointerCheck PtrRtCheck;
+ RuntimePointerChecking PtrRtChecking;
+
+ /// \brief the Memory Dependence Checker which can determine the
+ /// loop-independent and loop-carried dependences between memory accesses.
+ MemoryDepChecker DepChecker;
+
Loop *TheLoop;
ScalarEvolution *SE;
- const DataLayout *DL;
+ const DataLayout &DL;
const TargetLibraryInfo *TLI;
AliasAnalysis *AA;
DominatorTree *DT;
+ LoopInfo *LI;
unsigned NumLoads;
unsigned NumStores;
/// \brief Cache the result of analyzeLoop.
bool CanVecMem;
+ /// \brief Indicator for storing to uniform addresses.
+ /// If a loop has write to a loop invariant address then it should be true.
+ bool StoreToLoopInvariantAddress;
+
/// \brief The diagnostics report generated for the analysis. E.g. why we
/// couldn't analyze the loop.
- Optional<VectorizationReport> Report;
+ Optional<LoopAccessReport> Report;
};
Value *stripIntegerCast(Value *V);
/// Ptr. \p PtrToStride provides the mapping between the pointer value and its
/// stride as collected by LoopVectorizationLegality::collectStridedAccess.
const SCEV *replaceSymbolicStrideSCEV(ScalarEvolution *SE,
- ValueToValueMap &PtrToStride,
+ const ValueToValueMap &PtrToStride,
Value *Ptr, Value *OrigPtr = nullptr);
+/// \brief Check the stride of the pointer and ensure that it does not wrap in
+/// the address space.
+int isStridedPtr(ScalarEvolution *SE, Value *Ptr, const Loop *Lp,
+ const ValueToValueMap &StridesMap);
+
+/// \brief This analysis provides dependence information for the memory accesses
+/// of a loop.
+///
+/// It runs the analysis for a loop on demand. This can be initiated by
+/// querying the loop access info via LAA::getInfo. getInfo return a
+/// LoopAccessInfo object. See this class for the specifics of what information
+/// is provided.
+class LoopAccessAnalysis : public FunctionPass {
+public:
+ static char ID;
+
+ LoopAccessAnalysis() : FunctionPass(ID) {
+ initializeLoopAccessAnalysisPass(*PassRegistry::getPassRegistry());
+ }
+
+ bool runOnFunction(Function &F) override;
+
+ void getAnalysisUsage(AnalysisUsage &AU) const override;
+
+ /// \brief Query the result of the loop access information for the loop \p L.
+ ///
+ /// If the client speculates (and then issues run-time checks) for the values
+ /// of symbolic strides, \p Strides provides the mapping (see
+ /// replaceSymbolicStrideSCEV). If there is no cached result available run
+ /// the analysis.
+ const LoopAccessInfo &getInfo(Loop *L, const ValueToValueMap &Strides);
+
+ void releaseMemory() override {
+ // Invalidate the cache when the pass is freed.
+ LoopAccessInfoMap.clear();
+ }
+
+ /// \brief Print the result of the analysis when invoked with -analyze.
+ void print(raw_ostream &OS, const Module *M = nullptr) const override;
+
+private:
+ /// \brief The cache.
+ DenseMap<Loop *, std::unique_ptr<LoopAccessInfo>> LoopAccessInfoMap;
+
+ // The used analysis passes.
+ ScalarEvolution *SE;
+ const TargetLibraryInfo *TLI;
+ AliasAnalysis *AA;
+ DominatorTree *DT;
+ LoopInfo *LI;
+};
} // End llvm namespace
#endif
projects / oota-llvm.git / blobdiff