1 //===- llvm/Analysis/LoopAccessAnalysis.h -----------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the interface for the loop memory dependence framework that
11 // was originally developed for the Loop Vectorizer.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_ANALYSIS_LOOPACCESSANALYSIS_H
16 #define LLVM_ANALYSIS_LOOPACCESSANALYSIS_H
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/ScalarEvolutionExpressions.h"
24 #include "llvm/IR/ValueHandle.h"
25 #include "llvm/Pass.h"
26 #include "llvm/Support/raw_ostream.h"
32 class ScalarEvolution;
35 class SCEVUnionPredicate;
38 /// Optimization analysis message produced during vectorization. Messages inform
39 /// the user why vectorization did not occur.
40 class LoopAccessReport {
42 const Instruction *Instr;
45 LoopAccessReport(const Twine &Message, const Instruction *I)
46 : Message(Message.str()), Instr(I) {}
49 LoopAccessReport(const Instruction *I = nullptr) : Instr(I) {}
51 template <typename A> LoopAccessReport &operator<<(const A &Value) {
52 raw_string_ostream Out(Message);
57 const Instruction *getInstr() const { return Instr; }
59 std::string &str() { return Message; }
60 const std::string &str() const { return Message; }
61 operator Twine() { return Message; }
63 /// \brief Emit an analysis note for \p PassName with the debug location from
64 /// the instruction in \p Message if available. Otherwise use the location of
66 static void emitAnalysis(const LoopAccessReport &Message,
67 const Function *TheFunction,
69 const char *PassName);
72 /// \brief Collection of parameters shared beetween the Loop Vectorizer and the
73 /// Loop Access Analysis.
74 struct VectorizerParams {
75 /// \brief Maximum SIMD width.
76 static const unsigned MaxVectorWidth;
78 /// \brief VF as overridden by the user.
79 static unsigned VectorizationFactor;
80 /// \brief Interleave factor as overridden by the user.
81 static unsigned VectorizationInterleave;
82 /// \brief True if force-vector-interleave was specified by the user.
83 static bool isInterleaveForced();
85 /// \\brief When performing memory disambiguation checks at runtime do not
86 /// make more than this number of comparisons.
87 static unsigned RuntimeMemoryCheckThreshold;
90 /// \brief Checks memory dependences among accesses to the same underlying
91 /// object to determine whether there vectorization is legal or not (and at
92 /// which vectorization factor).
94 /// Note: This class will compute a conservative dependence for access to
95 /// different underlying pointers. Clients, such as the loop vectorizer, will
96 /// sometimes deal these potential dependencies by emitting runtime checks.
98 /// We use the ScalarEvolution framework to symbolically evalutate access
99 /// functions pairs. Since we currently don't restructure the loop we can rely
100 /// on the program order of memory accesses to determine their safety.
101 /// At the moment we will only deem accesses as safe for:
102 /// * A negative constant distance assuming program order.
104 /// Safe: tmp = a[i + 1]; OR a[i + 1] = x;
105 /// a[i] = tmp; y = a[i];
107 /// The latter case is safe because later checks guarantuee that there can't
108 /// be a cycle through a phi node (that is, we check that "x" and "y" is not
109 /// the same variable: a header phi can only be an induction or a reduction, a
110 /// reduction can't have a memory sink, an induction can't have a memory
111 /// source). This is important and must not be violated (or we have to
112 /// resort to checking for cycles through memory).
114 /// * A positive constant distance assuming program order that is bigger
115 /// than the biggest memory access.
117 /// tmp = a[i] OR b[i] = x
118 /// a[i+2] = tmp y = b[i+2];
120 /// Safe distance: 2 x sizeof(a[0]), and 2 x sizeof(b[0]), respectively.
122 /// * Zero distances and all accesses have the same size.
124 class MemoryDepChecker {
126 typedef PointerIntPair<Value *, 1, bool> MemAccessInfo;
127 typedef SmallPtrSet<MemAccessInfo, 8> MemAccessInfoSet;
128 /// \brief Set of potential dependent memory accesses.
129 typedef EquivalenceClasses<MemAccessInfo> DepCandidates;
131 /// \brief Dependece between memory access instructions.
133 /// \brief The type of the dependence.
137 // We couldn't determine the direction or the distance.
139 // Lexically forward.
141 // FIXME: If we only have loop-independent forward dependences (e.g. a
142 // read and write of A[i]), LAA will locally deem the dependence "safe"
143 // without querying the MemoryDepChecker. Therefore we can miss
144 // enumerating loop-independent forward dependences in
145 // getDependences. Note that as soon as there are different
146 // indices used to access the same array, the MemoryDepChecker *is*
147 // queried and the dependence list is complete.
149 // Forward, but if vectorized, is likely to prevent store-to-load
151 ForwardButPreventsForwarding,
152 // Lexically backward.
154 // Backward, but the distance allows a vectorization factor of
155 // MaxSafeDepDistBytes.
156 BackwardVectorizable,
157 // Same, but may prevent store-to-load forwarding.
158 BackwardVectorizableButPreventsForwarding
161 /// \brief String version of the types.
162 static const char *DepName[];
164 /// \brief Index of the source of the dependence in the InstMap vector.
166 /// \brief Index of the destination of the dependence in the InstMap vector.
167 unsigned Destination;
168 /// \brief The type of the dependence.
171 Dependence(unsigned Source, unsigned Destination, DepType Type)
172 : Source(Source), Destination(Destination), Type(Type) {}
174 /// \brief Return the source instruction of the dependence.
175 Instruction *getSource(const LoopAccessInfo &LAI) const;
176 /// \brief Return the destination instruction of the dependence.
177 Instruction *getDestination(const LoopAccessInfo &LAI) const;
179 /// \brief Dependence types that don't prevent vectorization.
180 static bool isSafeForVectorization(DepType Type);
182 /// \brief Lexically forward dependence.
183 bool isForward() const;
184 /// \brief Lexically backward dependence.
185 bool isBackward() const;
187 /// \brief May be a lexically backward dependence type (includes Unknown).
188 bool isPossiblyBackward() const;
190 /// \brief Print the dependence. \p Instr is used to map the instruction
191 /// indices to instructions.
192 void print(raw_ostream &OS, unsigned Depth,
193 const SmallVectorImpl<Instruction *> &Instrs) const;
196 MemoryDepChecker(ScalarEvolution *Se, const Loop *L,
197 SCEVUnionPredicate &Preds)
198 : SE(Se), InnermostLoop(L), AccessIdx(0),
199 ShouldRetryWithRuntimeCheck(false), SafeForVectorization(true),
200 RecordDependences(true), Preds(Preds) {}
202 /// \brief Register the location (instructions are given increasing numbers)
203 /// of a write access.
204 void addAccess(StoreInst *SI) {
205 Value *Ptr = SI->getPointerOperand();
206 Accesses[MemAccessInfo(Ptr, true)].push_back(AccessIdx);
207 InstMap.push_back(SI);
211 /// \brief Register the location (instructions are given increasing numbers)
212 /// of a write access.
213 void addAccess(LoadInst *LI) {
214 Value *Ptr = LI->getPointerOperand();
215 Accesses[MemAccessInfo(Ptr, false)].push_back(AccessIdx);
216 InstMap.push_back(LI);
220 /// \brief Check whether the dependencies between the accesses are safe.
222 /// Only checks sets with elements in \p CheckDeps.
223 bool areDepsSafe(DepCandidates &AccessSets, MemAccessInfoSet &CheckDeps,
224 const ValueToValueMap &Strides);
226 /// \brief No memory dependence was encountered that would inhibit
228 bool isSafeForVectorization() const { return SafeForVectorization; }
230 /// \brief The maximum number of bytes of a vector register we can vectorize
231 /// the accesses safely with.
232 unsigned getMaxSafeDepDistBytes() { return MaxSafeDepDistBytes; }
234 /// \brief In same cases when the dependency check fails we can still
235 /// vectorize the loop with a dynamic array access check.
236 bool shouldRetryWithRuntimeCheck() { return ShouldRetryWithRuntimeCheck; }
238 /// \brief Returns the memory dependences. If null is returned we exceeded
239 /// the MaxDependences threshold and this information is not
241 const SmallVectorImpl<Dependence> *getDependences() const {
242 return RecordDependences ? &Dependences : nullptr;
245 void clearDependences() { Dependences.clear(); }
247 /// \brief The vector of memory access instructions. The indices are used as
248 /// instruction identifiers in the Dependence class.
249 const SmallVectorImpl<Instruction *> &getMemoryInstructions() const {
253 /// \brief Generate a mapping between the memory instructions and their
254 /// indices according to program order.
255 DenseMap<Instruction *, unsigned> generateInstructionOrderMap() const {
256 DenseMap<Instruction *, unsigned> OrderMap;
258 for (unsigned I = 0; I < InstMap.size(); ++I)
259 OrderMap[InstMap[I]] = I;
264 /// \brief Find the set of instructions that read or write via \p Ptr.
265 SmallVector<Instruction *, 4> getInstructionsForAccess(Value *Ptr,
270 const Loop *InnermostLoop;
272 /// \brief Maps access locations (ptr, read/write) to program order.
273 DenseMap<MemAccessInfo, std::vector<unsigned> > Accesses;
275 /// \brief Memory access instructions in program order.
276 SmallVector<Instruction *, 16> InstMap;
278 /// \brief The program order index to be used for the next instruction.
281 // We can access this many bytes in parallel safely.
282 unsigned MaxSafeDepDistBytes;
284 /// \brief If we see a non-constant dependence distance we can still try to
285 /// vectorize this loop with runtime checks.
286 bool ShouldRetryWithRuntimeCheck;
288 /// \brief No memory dependence was encountered that would inhibit
290 bool SafeForVectorization;
292 //// \brief True if Dependences reflects the dependences in the
293 //// loop. If false we exceeded MaxDependences and
294 //// Dependences is invalid.
295 bool RecordDependences;
297 /// \brief Memory dependences collected during the analysis. Only valid if
298 /// RecordDependences is true.
299 SmallVector<Dependence, 8> Dependences;
301 /// \brief Check whether there is a plausible dependence between the two
304 /// Access \p A must happen before \p B in program order. The two indices
305 /// identify the index into the program order map.
307 /// This function checks whether there is a plausible dependence (or the
308 /// absence of such can't be proved) between the two accesses. If there is a
309 /// plausible dependence but the dependence distance is bigger than one
310 /// element access it records this distance in \p MaxSafeDepDistBytes (if this
311 /// distance is smaller than any other distance encountered so far).
312 /// Otherwise, this function returns true signaling a possible dependence.
313 Dependence::DepType isDependent(const MemAccessInfo &A, unsigned AIdx,
314 const MemAccessInfo &B, unsigned BIdx,
315 const ValueToValueMap &Strides);
317 /// \brief Check whether the data dependence could prevent store-load
319 bool couldPreventStoreLoadForward(unsigned Distance, unsigned TypeByteSize);
321 /// The SCEV predicate containing all the SCEV-related assumptions.
322 /// The dependence checker needs this in order to convert SCEVs of pointers
323 /// to more accurate expressions in the context of existing assumptions.
324 /// We also need this in case assumptions about SCEV expressions need to
325 /// be made in order to avoid unknown dependences. For example we might
326 /// assume a unit stride for a pointer in order to prove that a memory access
327 /// is strided and doesn't wrap.
328 SCEVUnionPredicate &Preds;
331 /// \brief Holds information about the memory runtime legality checks to verify
332 /// that a group of pointers do not overlap.
333 class RuntimePointerChecking {
336 /// Holds the pointer value that we need to check.
337 TrackingVH<Value> PointerValue;
338 /// Holds the pointer value at the beginning of the loop.
340 /// Holds the pointer value at the end of the loop.
342 /// Holds the information if this pointer is used for writing to memory.
344 /// Holds the id of the set of pointers that could be dependent because of a
345 /// shared underlying object.
346 unsigned DependencySetId;
347 /// Holds the id of the disjoint alias set to which this pointer belongs.
349 /// SCEV for the access.
352 PointerInfo(Value *PointerValue, const SCEV *Start, const SCEV *End,
353 bool IsWritePtr, unsigned DependencySetId, unsigned AliasSetId,
355 : PointerValue(PointerValue), Start(Start), End(End),
356 IsWritePtr(IsWritePtr), DependencySetId(DependencySetId),
357 AliasSetId(AliasSetId), Expr(Expr) {}
360 RuntimePointerChecking(ScalarEvolution *SE) : Need(false), SE(SE) {}
362 /// Reset the state of the pointer runtime information.
369 /// Insert a pointer and calculate the start and end SCEVs.
370 /// \p We need Preds in order to compute the SCEV expression of the pointer
371 /// according to the assumptions that we've made during the analysis.
372 /// The method might also version the pointer stride according to \p Strides,
373 /// and change \p Preds.
374 void insert(Loop *Lp, Value *Ptr, bool WritePtr, unsigned DepSetId,
375 unsigned ASId, const ValueToValueMap &Strides,
376 SCEVUnionPredicate &Preds);
378 /// \brief No run-time memory checking is necessary.
379 bool empty() const { return Pointers.empty(); }
381 /// A grouping of pointers. A single memcheck is required between
383 struct CheckingPtrGroup {
384 /// \brief Create a new pointer checking group containing a single
385 /// pointer, with index \p Index in RtCheck.
386 CheckingPtrGroup(unsigned Index, RuntimePointerChecking &RtCheck)
387 : RtCheck(RtCheck), High(RtCheck.Pointers[Index].End),
388 Low(RtCheck.Pointers[Index].Start) {
389 Members.push_back(Index);
392 /// \brief Tries to add the pointer recorded in RtCheck at index
393 /// \p Index to this pointer checking group. We can only add a pointer
394 /// to a checking group if we will still be able to get
395 /// the upper and lower bounds of the check. Returns true in case
396 /// of success, false otherwise.
397 bool addPointer(unsigned Index);
399 /// Constitutes the context of this pointer checking group. For each
400 /// pointer that is a member of this group we will retain the index
401 /// at which it appears in RtCheck.
402 RuntimePointerChecking &RtCheck;
403 /// The SCEV expression which represents the upper bound of all the
404 /// pointers in this group.
406 /// The SCEV expression which represents the lower bound of all the
407 /// pointers in this group.
409 /// Indices of all the pointers that constitute this grouping.
410 SmallVector<unsigned, 2> Members;
413 /// \brief A memcheck which made up of a pair of grouped pointers.
415 /// These *have* to be const for now, since checks are generated from
416 /// CheckingPtrGroups in LAI::addRuntimeChecks which is a const member
417 /// function. FIXME: once check-generation is moved inside this class (after
418 /// the PtrPartition hack is removed), we could drop const.
419 typedef std::pair<const CheckingPtrGroup *, const CheckingPtrGroup *>
422 /// \brief Generate the checks and store it. This also performs the grouping
423 /// of pointers to reduce the number of memchecks necessary.
424 void generateChecks(MemoryDepChecker::DepCandidates &DepCands,
425 bool UseDependencies);
427 /// \brief Returns the checks that generateChecks created.
428 const SmallVector<PointerCheck, 4> &getChecks() const { return Checks; }
430 /// \brief Decide if we need to add a check between two groups of pointers,
431 /// according to needsChecking.
432 bool needsChecking(const CheckingPtrGroup &M,
433 const CheckingPtrGroup &N) const;
435 /// \brief Returns the number of run-time checks required according to
437 unsigned getNumberOfChecks() const { return Checks.size(); }
439 /// \brief Print the list run-time memory checks necessary.
440 void print(raw_ostream &OS, unsigned Depth = 0) const;
443 void printChecks(raw_ostream &OS, const SmallVectorImpl<PointerCheck> &Checks,
444 unsigned Depth = 0) const;
446 /// This flag indicates if we need to add the runtime check.
449 /// Information about the pointers that may require checking.
450 SmallVector<PointerInfo, 2> Pointers;
452 /// Holds a partitioning of pointers into "check groups".
453 SmallVector<CheckingPtrGroup, 2> CheckingGroups;
455 /// \brief Check if pointers are in the same partition
457 /// \p PtrToPartition contains the partition number for pointers (-1 if the
458 /// pointer belongs to multiple partitions).
460 arePointersInSamePartition(const SmallVectorImpl<int> &PtrToPartition,
461 unsigned PtrIdx1, unsigned PtrIdx2);
463 /// \brief Decide whether we need to issue a run-time check for pointer at
464 /// index \p I and \p J to prove their independence.
465 bool needsChecking(unsigned I, unsigned J) const;
467 /// \brief Return PointerInfo for pointer at index \p PtrIdx.
468 const PointerInfo &getPointerInfo(unsigned PtrIdx) const {
469 return Pointers[PtrIdx];
473 /// \brief Groups pointers such that a single memcheck is required
474 /// between two different groups. This will clear the CheckingGroups vector
475 /// and re-compute it. We will only group dependecies if \p UseDependencies
476 /// is true, otherwise we will create a separate group for each pointer.
477 void groupChecks(MemoryDepChecker::DepCandidates &DepCands,
478 bool UseDependencies);
480 /// Generate the checks and return them.
481 SmallVector<PointerCheck, 4>
482 generateChecks() const;
484 /// Holds a pointer to the ScalarEvolution analysis.
487 /// \brief Set of run-time checks required to establish independence of
488 /// otherwise may-aliasing pointers in the loop.
489 SmallVector<PointerCheck, 4> Checks;
492 /// \brief Drive the analysis of memory accesses in the loop
494 /// This class is responsible for analyzing the memory accesses of a loop. It
495 /// collects the accesses and then its main helper the AccessAnalysis class
496 /// finds and categorizes the dependences in buildDependenceSets.
498 /// For memory dependences that can be analyzed at compile time, it determines
499 /// whether the dependence is part of cycle inhibiting vectorization. This work
500 /// is delegated to the MemoryDepChecker class.
502 /// For memory dependences that cannot be determined at compile time, it
503 /// generates run-time checks to prove independence. This is done by
504 /// AccessAnalysis::canCheckPtrAtRT and the checks are maintained by the
505 /// RuntimePointerCheck class.
507 /// If pointers can wrap or can't be expressed as affine AddRec expressions by
508 /// ScalarEvolution, we will generate run-time checks by emitting a
509 /// SCEVUnionPredicate.
511 /// Checks for both memory dependences and SCEV predicates must be emitted in
512 /// order for the results of this analysis to be valid.
513 class LoopAccessInfo {
515 LoopAccessInfo(Loop *L, ScalarEvolution *SE, const DataLayout &DL,
516 const TargetLibraryInfo *TLI, AliasAnalysis *AA,
517 DominatorTree *DT, LoopInfo *LI,
518 const ValueToValueMap &Strides);
520 /// Return true we can analyze the memory accesses in the loop and there are
521 /// no memory dependence cycles.
522 bool canVectorizeMemory() const { return CanVecMem; }
524 const RuntimePointerChecking *getRuntimePointerChecking() const {
525 return &PtrRtChecking;
528 /// \brief Number of memchecks required to prove independence of otherwise
529 /// may-alias pointers.
530 unsigned getNumRuntimePointerChecks() const {
531 return PtrRtChecking.getNumberOfChecks();
534 /// Return true if the block BB needs to be predicated in order for the loop
535 /// to be vectorized.
536 static bool blockNeedsPredication(BasicBlock *BB, Loop *TheLoop,
539 /// Returns true if the value V is uniform within the loop.
540 bool isUniform(Value *V) const;
542 unsigned getMaxSafeDepDistBytes() const { return MaxSafeDepDistBytes; }
543 unsigned getNumStores() const { return NumStores; }
544 unsigned getNumLoads() const { return NumLoads;}
546 /// \brief Add code that checks at runtime if the accessed arrays overlap.
548 /// Returns a pair of instructions where the first element is the first
549 /// instruction generated in possibly a sequence of instructions and the
550 /// second value is the final comparator value or NULL if no check is needed.
551 std::pair<Instruction *, Instruction *>
552 addRuntimeChecks(Instruction *Loc) const;
554 /// \brief Generete the instructions for the checks in \p PointerChecks.
556 /// Returns a pair of instructions where the first element is the first
557 /// instruction generated in possibly a sequence of instructions and the
558 /// second value is the final comparator value or NULL if no check is needed.
559 std::pair<Instruction *, Instruction *>
560 addRuntimeChecks(Instruction *Loc,
561 const SmallVectorImpl<RuntimePointerChecking::PointerCheck>
562 &PointerChecks) const;
564 /// \brief The diagnostics report generated for the analysis. E.g. why we
565 /// couldn't analyze the loop.
566 const Optional<LoopAccessReport> &getReport() const { return Report; }
568 /// \brief the Memory Dependence Checker which can determine the
569 /// loop-independent and loop-carried dependences between memory accesses.
570 const MemoryDepChecker &getDepChecker() const { return DepChecker; }
572 /// \brief Return the list of instructions that use \p Ptr to read or write
574 SmallVector<Instruction *, 4> getInstructionsForAccess(Value *Ptr,
575 bool isWrite) const {
576 return DepChecker.getInstructionsForAccess(Ptr, isWrite);
579 /// \brief Print the information about the memory accesses in the loop.
580 void print(raw_ostream &OS, unsigned Depth = 0) const;
582 /// \brief Used to ensure that if the analysis was run with speculating the
583 /// value of symbolic strides, the client queries it with the same assumption.
584 /// Only used in DEBUG build but we don't want NDEBUG-dependent ABI.
585 unsigned NumSymbolicStrides;
587 /// \brief Checks existence of store to invariant address inside loop.
588 /// If the loop has any store to invariant address, then it returns true,
589 /// else returns false.
590 bool hasStoreToLoopInvariantAddress() const {
591 return StoreToLoopInvariantAddress;
594 /// The SCEV predicate contains all the SCEV-related assumptions.
595 /// The is used to keep track of the minimal set of assumptions on SCEV
596 /// expressions that the analysis needs to make in order to return a
597 /// meaningful result. All SCEV expressions during the analysis should be
598 /// re-written (and therefore simplified) according to Preds.
599 /// A user of LoopAccessAnalysis will need to emit the runtime checks
600 /// associated with this predicate.
601 SCEVUnionPredicate Preds;
604 /// \brief Analyze the loop. Substitute symbolic strides using Strides.
605 void analyzeLoop(const ValueToValueMap &Strides);
607 /// \brief Check if the structure of the loop allows it to be analyzed by this
609 bool canAnalyzeLoop();
611 void emitAnalysis(LoopAccessReport &Message);
613 /// We need to check that all of the pointers in this list are disjoint
615 RuntimePointerChecking PtrRtChecking;
617 /// \brief the Memory Dependence Checker which can determine the
618 /// loop-independent and loop-carried dependences between memory accesses.
619 MemoryDepChecker DepChecker;
623 const DataLayout &DL;
624 const TargetLibraryInfo *TLI;
632 unsigned MaxSafeDepDistBytes;
634 /// \brief Cache the result of analyzeLoop.
637 /// \brief Indicator for storing to uniform addresses.
638 /// If a loop has write to a loop invariant address then it should be true.
639 bool StoreToLoopInvariantAddress;
641 /// \brief The diagnostics report generated for the analysis. E.g. why we
642 /// couldn't analyze the loop.
643 Optional<LoopAccessReport> Report;
646 Value *stripIntegerCast(Value *V);
648 ///\brief Return the SCEV corresponding to a pointer with the symbolic stride
649 /// replaced with constant one, assuming \p Preds is true.
651 /// If necessary this method will version the stride of the pointer according
652 /// to \p PtrToStride and therefore add a new predicate to \p Preds.
654 /// If \p OrigPtr is not null, use it to look up the stride value instead of \p
655 /// Ptr. \p PtrToStride provides the mapping between the pointer value and its
656 /// stride as collected by LoopVectorizationLegality::collectStridedAccess.
657 const SCEV *replaceSymbolicStrideSCEV(ScalarEvolution *SE,
658 const ValueToValueMap &PtrToStride,
659 SCEVUnionPredicate &Preds, Value *Ptr,
660 Value *OrigPtr = nullptr);
662 /// \brief Check the stride of the pointer and ensure that it does not wrap in
663 /// the address space, assuming \p Preds is true.
665 /// If necessary this method will version the stride of the pointer according
666 /// to \p PtrToStride and therefore add a new predicate to \p Preds.
667 int isStridedPtr(ScalarEvolution *SE, Value *Ptr, const Loop *Lp,
668 const ValueToValueMap &StridesMap, SCEVUnionPredicate &Preds);
670 /// \brief This analysis provides dependence information for the memory accesses
673 /// It runs the analysis for a loop on demand. This can be initiated by
674 /// querying the loop access info via LAA::getInfo. getInfo return a
675 /// LoopAccessInfo object. See this class for the specifics of what information
677 class LoopAccessAnalysis : public FunctionPass {
681 LoopAccessAnalysis() : FunctionPass(ID) {
682 initializeLoopAccessAnalysisPass(*PassRegistry::getPassRegistry());
685 bool runOnFunction(Function &F) override;
687 void getAnalysisUsage(AnalysisUsage &AU) const override;
689 /// \brief Query the result of the loop access information for the loop \p L.
691 /// If the client speculates (and then issues run-time checks) for the values
692 /// of symbolic strides, \p Strides provides the mapping (see
693 /// replaceSymbolicStrideSCEV). If there is no cached result available run
695 const LoopAccessInfo &getInfo(Loop *L, const ValueToValueMap &Strides);
697 void releaseMemory() override {
698 // Invalidate the cache when the pass is freed.
699 LoopAccessInfoMap.clear();
702 /// \brief Print the result of the analysis when invoked with -analyze.
703 void print(raw_ostream &OS, const Module *M = nullptr) const override;
706 /// \brief The cache.
707 DenseMap<Loop *, std::unique_ptr<LoopAccessInfo>> LoopAccessInfoMap;
709 // The used analysis passes.
711 const TargetLibraryInfo *TLI;
717 inline Instruction *MemoryDepChecker::Dependence::getSource(
718 const LoopAccessInfo &LAI) const {
719 return LAI.getDepChecker().getMemoryInstructions()[Source];
722 inline Instruction *MemoryDepChecker::Dependence::getDestination(
723 const LoopAccessInfo &LAI) const {
724 return LAI.getDepChecker().getMemoryInstructions()[Destination];
727 } // End llvm namespace