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 30namespace llvm { 31 32class Value; 33class DataLayout; 34class ScalarEvolution; 35class Loop; 36class SCEV; 37class SCEVUnionPredicate; 38class LoopAccessInfo; 39class OptimizationRemarkEmitter; 40 41/// \brief Collection of parameters shared beetween the Loop Vectorizer and the 42/// Loop Access Analysis. 43struct 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/// 93class MemoryDepChecker { 94public: 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 : 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 : PSE(PSE), InnermostLoop(L), AccessIdx(0), 167 ShouldRetryWithRuntimeCheck(false), SafeForVectorization(true), 168 RecordDependences(true) {} 169 170 /// \brief Register the location (instructions are given increasing numbers) 171 /// of a write access. 172 void addAccess(StoreInst *SI) { 173 Value *Ptr = SI->getPointerOperand(); 174 Accesses[MemAccessInfo(Ptr, true)].push_back(AccessIdx); 175 InstMap.push_back(SI); 176 ++AccessIdx; 177 } 178 179 /// \brief Register the location (instructions are given increasing numbers) 180 /// of a write access. 181 void addAccess(LoadInst *LI) { 182 Value *Ptr = LI->getPointerOperand(); 183 Accesses[MemAccessInfo(Ptr, false)].push_back(AccessIdx); 184 InstMap.push_back(LI); 185 ++AccessIdx; 186 } 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 return RecordDependences ? &Dependences : nullptr; 211 } 212 213 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 return InstMap; 219 } 220 221 /// \brief Generate a mapping between the memory instructions and their 222 /// indices according to program order. 223 DenseMap<Instruction *, unsigned> generateInstructionOrderMap() const { 224 DenseMap<Instruction *, unsigned> OrderMap; 225 226 for (unsigned I = 0; I < InstMap.size(); ++I) 227 OrderMap[InstMap[I]] = I; 228 229 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 236private: 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. 301class RuntimePointerChecking { 302public: 303 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 : PointerValue(PointerValue), Start(Start), End(End), 326 IsWritePtr(IsWritePtr), DependencySetId(DependencySetId), 327 AliasSetId(AliasSetId), Expr(Expr) {} 328 }; 329 330 RuntimePointerChecking(ScalarEvolution *SE) : Need(false), SE(SE) {} 331 332 /// Reset the state of the pointer runtime information. 333 void reset() { 334 Need = false; 335 Pointers.clear(); 336 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 struct CheckingPtrGroup { 354 /// \brief Create a new pointer checking group containing a single 355 /// pointer, with index \p Index in RtCheck. 356 CheckingPtrGroup(unsigned Index, RuntimePointerChecking &RtCheck) 357 : RtCheck(RtCheck), High(RtCheck.Pointers[Index].End), 358 Low(RtCheck.Pointers[Index].Start) { 359 Members.push_back(Index); 360 } 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 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 return Pointers[PtrIdx]; 440 } 441 442private: 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. 483class LoopAccessInfo { 484public: 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 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 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 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 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 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 const ValueToValueMap &getSymbolicStrides() const { return SymbolicStrides; } 550 551 /// \brief Pointer has a symbolic stride. 552 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 const PredicatedScalarEvolution &getPSE() const { return *PSE; } 570 571private: 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 630Value *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. 642const 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. 656int64_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. 662bool 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. 672class LoopAccessLegacyAnalysis : public FunctionPass { 673public: 674 static char ID; 675 676 LoopAccessLegacyAnalysis() : FunctionPass(ID) { 677 initializeLoopAccessLegacyAnalysisPass(*PassRegistry::getPassRegistry()); 678 } 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 void releaseMemory() override { 690 // Invalidate the cache when the pass is freed. 691 LoopAccessInfoMap.clear(); 692 } 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 697private: 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. 716class LoopAccessAnalysis 717 : public AnalysisInfoMixin<LoopAccessAnalysis> { 718 friend AnalysisInfoMixin<LoopAccessAnalysis>; 719 static AnalysisKey Key; 720 721public: 722 typedef LoopAccessInfo Result; 723 724 Result run(Loop &L, LoopAnalysisManager &AM, LoopStandardAnalysisResults &AR); 725}; 726 727inline Instruction *MemoryDepChecker::Dependence::getSource( 728 const LoopAccessInfo &LAI) const { 729 return LAI.getDepChecker().getMemoryInstructions()[Source]; 730} 731 732inline Instruction *MemoryDepChecker::Dependence::getDestination( 733 const LoopAccessInfo &LAI) const { 734 return LAI.getDepChecker().getMemoryInstructions()[Destination]; 735} 736 737} // End llvm namespace 738 739#endif 740