//===- llvm/Analysis/LoopAccessAnalysis.h -----------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the interface for the loop memory dependence framework that
// was originally developed for the Loop Vectorizer.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_LOOPACCESSANALYSIS_H
#define LLVM_ANALYSIS_LOOPACCESSANALYSIS_H
#include "llvm/ADT/EquivalenceClasses.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/AliasSetTracker.h"
#include "llvm/Analysis/LoopAnalysisManager.h"
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/ValueHandle.h"
#include "llvm/Pass.h"
#include "llvm/Support/raw_ostream.h"
namespace llvm {
class Value;
class DataLayout;
class ScalarEvolution;
class Loop;
class SCEV;
class SCEVUnionPredicate;
class LoopAccessInfo;
class OptimizationRemarkEmitter;
/// \brief Collection of parameters shared beetween the Loop Vectorizer and the
/// Loop Access Analysis.
struct VectorizerParams {
/// \brief Maximum SIMD width.
static const unsigned MaxVectorWidth;
/// \brief VF as overridden by the user.
static unsigned VectorizationFactor;
/// \brief Interleave factor as overridden by the user.
static unsigned VectorizationInterleave;
/// \brief True if force-vector-interleave was specified by the user.
static bool isInterleaveForced();
/// \\brief When performing memory disambiguation checks at runtime do not
/// make more than this number of comparisons.
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 SmallVector<MemAccessInfo, 8> MemAccessInfoList;
/// \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.
//
// FIXME: If we only have loop-independent forward dependences (e.g. a
// read and write of A[i]), LAA will locally deem the dependence "safe"
// without querying the MemoryDepChecker. Therefore we can miss
// enumerating loop-independent forward dependences in
// getDependences. Note that as soon as there are different
// indices used to access the same array, the MemoryDepChecker *is*
// queried and the dependence list is complete.
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 Return the source instruction of the dependence.
Instruction *getSource(const LoopAccessInfo &LAI) const;
/// \brief Return the destination instruction of the dependence.
Instruction *getDestination(const LoopAccessInfo &LAI) const;
/// \brief Dependence types that don't prevent vectorization.
static bool isSafeForVectorization(DepType Type);
/// \brief Lexically forward dependence.
bool isForward() const;
/// \brief Lexically backward dependence.
bool isBackward() const;
/// \brief May be a lexically backward dependence type (includes Unknown).
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(PredicatedScalarEvolution &PSE, const Loop *L)
: PSE(PSE), InnermostLoop(L), AccessIdx(0), MaxSafeRegisterWidth(-1U),
ShouldRetryWithRuntimeCheck(false), SafeForVectorization(true),
RecordDependences(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, MemAccessInfoList &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.
uint64_t getMaxSafeDepDistBytes() { return MaxSafeDepDistBytes; }
/// \brief Return the number of elements that are safe to operate on
/// simultaneously, multiplied by the size of the element in bits.
uint64_t getMaxSafeRegisterWidth() const { return MaxSafeRegisterWidth; }
/// \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 memory dependences. If null is returned we exceeded
/// the MaxDependences threshold and this information is not
/// available.
const SmallVectorImpl<Dependence> *getDependences() const {
return RecordDependences ? &Dependences : nullptr;
}
void clearDependences() { Dependences.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 Generate a mapping between the memory instructions and their
/// indices according to program order.
DenseMap<Instruction *, unsigned> generateInstructionOrderMap() const {
DenseMap<Instruction *, unsigned> OrderMap;
for (unsigned I = 0; I < InstMap.size(); ++I)
OrderMap[InstMap[I]] = I;
return OrderMap;
}
/// \brief Find the set of instructions that read or write via \p Ptr.
SmallVector<Instruction *, 4> getInstructionsForAccess(Value *Ptr,
bool isWrite) const;
private:
/// A wrapper around ScalarEvolution, used to add runtime SCEV checks, and
/// applies dynamic knowledge to simplify SCEV expressions and convert them
/// to a more usable form. We need this in case assumptions about SCEV
/// expressions need to be made in order to avoid unknown dependences. For
/// example we might assume a unit stride for a pointer in order to prove
/// that a memory access is strided and doesn't wrap.
PredicatedScalarEvolution &PSE;
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.
uint64_t MaxSafeDepDistBytes;
/// \brief Number of elements (from consecutive iterations) that are safe to
/// operate on simultaneously, multiplied by the size of the element in bits.
/// The size of the element is taken from the memory access that is most
/// restrictive.
uint64_t MaxSafeRegisterWidth;
/// \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 Dependences reflects the dependences in the
//// loop. If false we exceeded MaxDependences and
//// Dependences is invalid.
bool RecordDependences;
/// \brief Memory dependences collected during the analysis. Only valid if
/// RecordDependences is true.
SmallVector<Dependence, 8> Dependences;
/// \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.
///
/// \return false if we shouldn't vectorize at all or avoid larger
/// vectorization factors by limiting MaxSafeDepDistBytes.
bool couldPreventStoreLoadForward(uint64_t Distance, uint64_t 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 smallest byte address accessed by the pointer throughout all
/// iterations of the loop.
const SCEV *Start;
/// Holds the largest byte address accessed by the pointer throughout all
/// iterations of the loop, plus 1.
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.
/// We need \p PSE in order to compute the SCEV expression of the pointer
/// according to the assumptions that we've made during the analysis.
/// The method might also version the pointer stride according to \p Strides,
/// and add new predicates to \p PSE.
void insert(Loop *Lp, Value *Ptr, bool WritePtr, unsigned DepSetId,
unsigned ASId, const ValueToValueMap &Strides,
PredicatedScalarEvolution &PSE);
/// \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::addRuntimeChecks 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 SmallVector<PointerCheck, 4> &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;
/// \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.
bool needsChecking(unsigned I, unsigned J) const;
/// \brief Return PointerInfo for pointer at index \p PtrIdx.
const PointerInfo &getPointerInfo(unsigned PtrIdx) const {
return Pointers[PtrIdx];
}
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.
SmallVector<PointerCheck, 4>
generateChecks() 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
///
/// This class is responsible for analyzing the memory accesses of a loop. It
/// collects the accesses and then its main helper the AccessAnalysis class
/// finds and categorizes the dependences in buildDependenceSets.
///
/// For memory dependences that can be analyzed at compile time, it determines
/// whether the dependence is part of cycle inhibiting vectorization. This work
/// is delegated to the MemoryDepChecker class.
///
/// For memory dependences that cannot be determined at compile time, it
/// generates run-time checks to prove independence. This is done by
/// AccessAnalysis::canCheckPtrAtRT and the checks are maintained by the
/// RuntimePointerCheck class.
///
/// If pointers can wrap or can't be expressed as affine AddRec expressions by
/// ScalarEvolution, we will generate run-time checks by emitting a
/// SCEVUnionPredicate.
///
/// Checks for both memory dependences and the SCEV predicates contained in the
/// PSE must be emitted in order for the results of this analysis to be valid.
class LoopAccessInfo {
public:
LoopAccessInfo(Loop *L, ScalarEvolution *SE, const TargetLibraryInfo *TLI,
AliasAnalysis *AA, DominatorTree *DT, LoopInfo *LI);
/// Return true we can analyze the memory accesses in the loop and there are
/// no memory dependence cycles.
bool canVectorizeMemory() const { return CanVecMem; }
const RuntimePointerChecking *getRuntimePointerChecking() const {
return PtrRtChecking.get();
}
/// \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.
static bool blockNeedsPredication(BasicBlock *BB, Loop *TheLoop,
DominatorTree *DT);
/// Returns true if the value V is uniform within the loop.
bool isUniform(Value *V) const;
uint64_t getMaxSafeDepDistBytes() const { return MaxSafeDepDistBytes; }
unsigned getNumStores() const { return NumStores; }
unsigned getNumLoads() const { return NumLoads;}
/// \brief Add code that checks at runtime if the accessed arrays overlap.
///
/// 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 *>
addRuntimeChecks(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 *>
addRuntimeChecks(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.
const OptimizationRemarkAnalysis *getReport() const { return Report.get(); }
/// \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 If an access has a symbolic strides, this maps the pointer value to
/// the stride symbol.
const ValueToValueMap &getSymbolicStrides() const { return SymbolicStrides; }
/// \brief Pointer has a symbolic stride.
bool hasStride(Value *V) const { return StrideSet.count(V); }
/// \brief Print the information about the memory accesses in the loop.
void print(raw_ostream &OS, unsigned Depth = 0) const;
/// \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;
}
/// Used to add runtime SCEV checks. Simplifies SCEV expressions and converts
/// them to a more usable form. All SCEV expressions during the analysis
/// should be re-written (and therefore simplified) according to PSE.
/// A user of LoopAccessAnalysis will need to emit the runtime checks
/// associated with this predicate.
const PredicatedScalarEvolution &getPSE() const { return *PSE; }
private:
/// \brief Analyze the loop.
void analyzeLoop(AliasAnalysis *AA, LoopInfo *LI,
const TargetLibraryInfo *TLI, DominatorTree *DT);
/// \brief Check if the structure of the loop allows it to be analyzed by this
/// pass.
bool canAnalyzeLoop();
/// \brief Save the analysis remark.
///
/// LAA does not directly emits the remarks. Instead it stores it which the
/// client can retrieve and presents as its own analysis
/// (e.g. -Rpass-analysis=loop-vectorize).
OptimizationRemarkAnalysis &recordAnalysis(StringRef RemarkName,
Instruction *Instr = nullptr);
/// \brief Collect memory access with loop invariant strides.
///
/// Looks for accesses like "a[i * StrideA]" where "StrideA" is loop
/// invariant.
void collectStridedAccess(Value *LoadOrStoreInst);
std::unique_ptr<PredicatedScalarEvolution> PSE;
/// We need to check that all of the pointers in this list are disjoint
/// at runtime. Using std::unique_ptr to make using move ctor simpler.
std::unique_ptr<RuntimePointerChecking> PtrRtChecking;
/// \brief the Memory Dependence Checker which can determine the
/// loop-independent and loop-carried dependences between memory accesses.
std::unique_ptr<MemoryDepChecker> DepChecker;
Loop *TheLoop;
unsigned NumLoads;
unsigned NumStores;
uint64_t MaxSafeDepDistBytes;
/// \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.
std::unique_ptr<OptimizationRemarkAnalysis> Report;
/// \brief If an access has a symbolic strides, this maps the pointer value to
/// the stride symbol.
ValueToValueMap SymbolicStrides;
/// \brief Set of symbolic strides values.
SmallPtrSet<Value *, 8> StrideSet;
};
Value *stripIntegerCast(Value *V);
/// \brief Return the SCEV corresponding to a pointer with the symbolic stride
/// replaced with constant one, assuming the SCEV predicate associated with
/// \p PSE is true.
///
/// If necessary this method will version the stride of the pointer according
/// to \p PtrToStride and therefore add further predicates to \p PSE.
///
/// If \p OrigPtr is not null, use it to look up the stride value instead of \p
/// Ptr. \p PtrToStride provides the mapping between the pointer value and its
/// stride as collected by LoopVectorizationLegality::collectStridedAccess.
const SCEV *replaceSymbolicStrideSCEV(PredicatedScalarEvolution &PSE,
const ValueToValueMap &PtrToStride,
Value *Ptr, Value *OrigPtr = nullptr);
/// \brief If the pointer has a constant stride return it in units of its
/// element size. Otherwise return zero.
///
/// Ensure that it does not wrap in the address space, assuming the predicate
/// associated with \p PSE is true.
///
/// If necessary this method will version the stride of the pointer according
/// to \p PtrToStride and therefore add further predicates to \p PSE.
/// The \p Assume parameter indicates if we are allowed to make additional
/// run-time assumptions.
int64_t getPtrStride(PredicatedScalarEvolution &PSE, Value *Ptr, const Loop *Lp,
const ValueToValueMap &StridesMap = ValueToValueMap(),
bool Assume = false, bool ShouldCheckWrap = true);
/// \brief Returns true if the memory operations \p A and \p B are consecutive.
/// This is a simple API that does not depend on the analysis pass.
bool isConsecutiveAccess(Value *A, Value *B, const DataLayout &DL,
ScalarEvolution &SE, bool CheckType = true);
/// \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 LoopAccessLegacyAnalysis : public FunctionPass {
public:
static char ID;
LoopAccessLegacyAnalysis() : FunctionPass(ID) {
initializeLoopAccessLegacyAnalysisPass(*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 there is no cached result available run the analysis.
const LoopAccessInfo &getInfo(Loop *L);
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;
};
/// \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 AM.getResult<LoopAccessAnalysis>.
/// getResult return a LoopAccessInfo object. See this class for the
/// specifics of what information is provided.
class LoopAccessAnalysis
: public AnalysisInfoMixin<LoopAccessAnalysis> {
friend AnalysisInfoMixin<LoopAccessAnalysis>;
static AnalysisKey Key;
public:
typedef LoopAccessInfo Result;
Result run(Loop &L, LoopAnalysisManager &AM, LoopStandardAnalysisResults &AR);
};
inline Instruction *MemoryDepChecker::Dependence::getSource(
const LoopAccessInfo &LAI) const {
return LAI.getDepChecker().getMemoryInstructions()[Source];
}
inline Instruction *MemoryDepChecker::Dependence::getDestination(
const LoopAccessInfo &LAI) const {
return LAI.getDepChecker().getMemoryInstructions()[Destination];
}
} // End llvm namespace
#endif