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- #pragma once
- #ifdef __GNUC__
- #pragma GCC diagnostic push
- #pragma GCC diagnostic ignored "-Wunused-parameter"
- #endif
- //===- llvm/Analysis/AliasAnalysis.h - Alias Analysis Interface -*- C++ -*-===//
- //
- // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
- // See https://llvm.org/LICENSE.txt for license information.
- // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
- //
- //===----------------------------------------------------------------------===//
- //
- // This file defines the generic AliasAnalysis interface, which is used as the
- // common interface used by all clients of alias analysis information, and
- // implemented by all alias analysis implementations. Mod/Ref information is
- // also captured by this interface.
- //
- // Implementations of this interface must implement the various virtual methods,
- // which automatically provides functionality for the entire suite of client
- // APIs.
- //
- // This API identifies memory regions with the MemoryLocation class. The pointer
- // component specifies the base memory address of the region. The Size specifies
- // the maximum size (in address units) of the memory region, or
- // MemoryLocation::UnknownSize if the size is not known. The TBAA tag
- // identifies the "type" of the memory reference; see the
- // TypeBasedAliasAnalysis class for details.
- //
- // Some non-obvious details include:
- // - Pointers that point to two completely different objects in memory never
- // alias, regardless of the value of the Size component.
- // - NoAlias doesn't imply inequal pointers. The most obvious example of this
- // is two pointers to constant memory. Even if they are equal, constant
- // memory is never stored to, so there will never be any dependencies.
- // In this and other situations, the pointers may be both NoAlias and
- // MustAlias at the same time. The current API can only return one result,
- // though this is rarely a problem in practice.
- //
- //===----------------------------------------------------------------------===//
- #ifndef LLVM_ANALYSIS_ALIASANALYSIS_H
- #define LLVM_ANALYSIS_ALIASANALYSIS_H
- #include "llvm/ADT/DenseMap.h"
- #include "llvm/ADT/Sequence.h"
- #include "llvm/ADT/SmallVector.h"
- #include "llvm/Analysis/MemoryLocation.h"
- #include "llvm/IR/PassManager.h"
- #include "llvm/Pass.h"
- #include "llvm/Support/ModRef.h"
- #include <cstdint>
- #include <functional>
- #include <memory>
- #include <optional>
- #include <vector>
- namespace llvm {
- class AnalysisUsage;
- class AtomicCmpXchgInst;
- class BasicAAResult;
- class BasicBlock;
- class CatchPadInst;
- class CatchReturnInst;
- class DominatorTree;
- class FenceInst;
- class Function;
- class LoopInfo;
- class PreservedAnalyses;
- class TargetLibraryInfo;
- class Value;
- template <typename> class SmallPtrSetImpl;
- /// The possible results of an alias query.
- ///
- /// These results are always computed between two MemoryLocation objects as
- /// a query to some alias analysis.
- ///
- /// Note that these are unscoped enumerations because we would like to support
- /// implicitly testing a result for the existence of any possible aliasing with
- /// a conversion to bool, but an "enum class" doesn't support this. The
- /// canonical names from the literature are suffixed and unique anyways, and so
- /// they serve as global constants in LLVM for these results.
- ///
- /// See docs/AliasAnalysis.html for more information on the specific meanings
- /// of these values.
- class AliasResult {
- private:
- static const int OffsetBits = 23;
- static const int AliasBits = 8;
- static_assert(AliasBits + 1 + OffsetBits <= 32,
- "AliasResult size is intended to be 4 bytes!");
- unsigned int Alias : AliasBits;
- unsigned int HasOffset : 1;
- signed int Offset : OffsetBits;
- public:
- enum Kind : uint8_t {
- /// The two locations do not alias at all.
- ///
- /// This value is arranged to convert to false, while all other values
- /// convert to true. This allows a boolean context to convert the result to
- /// a binary flag indicating whether there is the possibility of aliasing.
- NoAlias = 0,
- /// The two locations may or may not alias. This is the least precise
- /// result.
- MayAlias,
- /// The two locations alias, but only due to a partial overlap.
- PartialAlias,
- /// The two locations precisely alias each other.
- MustAlias,
- };
- static_assert(MustAlias < (1 << AliasBits),
- "Not enough bit field size for the enum!");
- explicit AliasResult() = delete;
- constexpr AliasResult(const Kind &Alias)
- : Alias(Alias), HasOffset(false), Offset(0) {}
- operator Kind() const { return static_cast<Kind>(Alias); }
- constexpr bool hasOffset() const { return HasOffset; }
- constexpr int32_t getOffset() const {
- assert(HasOffset && "No offset!");
- return Offset;
- }
- void setOffset(int32_t NewOffset) {
- if (isInt<OffsetBits>(NewOffset)) {
- HasOffset = true;
- Offset = NewOffset;
- }
- }
- /// Helper for processing AliasResult for swapped memory location pairs.
- void swap(bool DoSwap = true) {
- if (DoSwap && hasOffset())
- setOffset(-getOffset());
- }
- };
- static_assert(sizeof(AliasResult) == 4,
- "AliasResult size is intended to be 4 bytes!");
- /// << operator for AliasResult.
- raw_ostream &operator<<(raw_ostream &OS, AliasResult AR);
- /// Virtual base class for providers of capture information.
- struct CaptureInfo {
- virtual ~CaptureInfo() = 0;
- virtual bool isNotCapturedBeforeOrAt(const Value *Object,
- const Instruction *I) = 0;
- };
- /// Context-free CaptureInfo provider, which computes and caches whether an
- /// object is captured in the function at all, but does not distinguish whether
- /// it was captured before or after the context instruction.
- class SimpleCaptureInfo final : public CaptureInfo {
- SmallDenseMap<const Value *, bool, 8> IsCapturedCache;
- public:
- bool isNotCapturedBeforeOrAt(const Value *Object,
- const Instruction *I) override;
- };
- /// Context-sensitive CaptureInfo provider, which computes and caches the
- /// earliest common dominator closure of all captures. It provides a good
- /// approximation to a precise "captures before" analysis.
- class EarliestEscapeInfo final : public CaptureInfo {
- DominatorTree &DT;
- const LoopInfo &LI;
- /// Map from identified local object to an instruction before which it does
- /// not escape, or nullptr if it never escapes. The "earliest" instruction
- /// may be a conservative approximation, e.g. the first instruction in the
- /// function is always a legal choice.
- DenseMap<const Value *, Instruction *> EarliestEscapes;
- /// Reverse map from instruction to the objects it is the earliest escape for.
- /// This is used for cache invalidation purposes.
- DenseMap<Instruction *, TinyPtrVector<const Value *>> Inst2Obj;
- const SmallPtrSetImpl<const Value *> &EphValues;
- public:
- EarliestEscapeInfo(DominatorTree &DT, const LoopInfo &LI,
- const SmallPtrSetImpl<const Value *> &EphValues)
- : DT(DT), LI(LI), EphValues(EphValues) {}
- bool isNotCapturedBeforeOrAt(const Value *Object,
- const Instruction *I) override;
- void removeInstruction(Instruction *I);
- };
- /// Cache key for BasicAA results. It only includes the pointer and size from
- /// MemoryLocation, as BasicAA is AATags independent. Additionally, it includes
- /// the value of MayBeCrossIteration, which may affect BasicAA results.
- struct AACacheLoc {
- using PtrTy = PointerIntPair<const Value *, 1, bool>;
- PtrTy Ptr;
- LocationSize Size;
- AACacheLoc(PtrTy Ptr, LocationSize Size) : Ptr(Ptr), Size(Size) {}
- AACacheLoc(const Value *Ptr, LocationSize Size, bool MayBeCrossIteration)
- : Ptr(Ptr, MayBeCrossIteration), Size(Size) {}
- };
- template <> struct DenseMapInfo<AACacheLoc> {
- static inline AACacheLoc getEmptyKey() {
- return {DenseMapInfo<AACacheLoc::PtrTy>::getEmptyKey(),
- DenseMapInfo<LocationSize>::getEmptyKey()};
- }
- static inline AACacheLoc getTombstoneKey() {
- return {DenseMapInfo<AACacheLoc::PtrTy>::getTombstoneKey(),
- DenseMapInfo<LocationSize>::getTombstoneKey()};
- }
- static unsigned getHashValue(const AACacheLoc &Val) {
- return DenseMapInfo<AACacheLoc::PtrTy>::getHashValue(Val.Ptr) ^
- DenseMapInfo<LocationSize>::getHashValue(Val.Size);
- }
- static bool isEqual(const AACacheLoc &LHS, const AACacheLoc &RHS) {
- return LHS.Ptr == RHS.Ptr && LHS.Size == RHS.Size;
- }
- };
- class AAResults;
- /// This class stores info we want to provide to or retain within an alias
- /// query. By default, the root query is stateless and starts with a freshly
- /// constructed info object. Specific alias analyses can use this query info to
- /// store per-query state that is important for recursive or nested queries to
- /// avoid recomputing. To enable preserving this state across multiple queries
- /// where safe (due to the IR not changing), use a `BatchAAResults` wrapper.
- /// The information stored in an `AAQueryInfo` is currently limitted to the
- /// caches used by BasicAA, but can further be extended to fit other AA needs.
- class AAQueryInfo {
- public:
- using LocPair = std::pair<AACacheLoc, AACacheLoc>;
- struct CacheEntry {
- AliasResult Result;
- /// Number of times a NoAlias assumption has been used.
- /// 0 for assumptions that have not been used, -1 for definitive results.
- int NumAssumptionUses;
- /// Whether this is a definitive (non-assumption) result.
- bool isDefinitive() const { return NumAssumptionUses < 0; }
- };
- // Alias analysis result aggregration using which this query is performed.
- // Can be used to perform recursive queries.
- AAResults &AAR;
- using AliasCacheT = SmallDenseMap<LocPair, CacheEntry, 8>;
- AliasCacheT AliasCache;
- CaptureInfo *CI;
- /// Query depth used to distinguish recursive queries.
- unsigned Depth = 0;
- /// How many active NoAlias assumption uses there are.
- int NumAssumptionUses = 0;
- /// Location pairs for which an assumption based result is currently stored.
- /// Used to remove all potentially incorrect results from the cache if an
- /// assumption is disproven.
- SmallVector<AAQueryInfo::LocPair, 4> AssumptionBasedResults;
- /// Tracks whether the accesses may be on different cycle iterations.
- ///
- /// When interpret "Value" pointer equality as value equality we need to make
- /// sure that the "Value" is not part of a cycle. Otherwise, two uses could
- /// come from different "iterations" of a cycle and see different values for
- /// the same "Value" pointer.
- ///
- /// The following example shows the problem:
- /// %p = phi(%alloca1, %addr2)
- /// %l = load %ptr
- /// %addr1 = gep, %alloca2, 0, %l
- /// %addr2 = gep %alloca2, 0, (%l + 1)
- /// alias(%p, %addr1) -> MayAlias !
- /// store %l, ...
- bool MayBeCrossIteration = false;
- AAQueryInfo(AAResults &AAR, CaptureInfo *CI) : AAR(AAR), CI(CI) {}
- };
- /// AAQueryInfo that uses SimpleCaptureInfo.
- class SimpleAAQueryInfo : public AAQueryInfo {
- SimpleCaptureInfo CI;
- public:
- SimpleAAQueryInfo(AAResults &AAR) : AAQueryInfo(AAR, &CI) {}
- };
- class BatchAAResults;
- class AAResults {
- public:
- // Make these results default constructable and movable. We have to spell
- // these out because MSVC won't synthesize them.
- AAResults(const TargetLibraryInfo &TLI) : TLI(TLI) {}
- AAResults(AAResults &&Arg);
- ~AAResults();
- /// Register a specific AA result.
- template <typename AAResultT> void addAAResult(AAResultT &AAResult) {
- // FIXME: We should use a much lighter weight system than the usual
- // polymorphic pattern because we don't own AAResult. It should
- // ideally involve two pointers and no separate allocation.
- AAs.emplace_back(new Model<AAResultT>(AAResult, *this));
- }
- /// Register a function analysis ID that the results aggregation depends on.
- ///
- /// This is used in the new pass manager to implement the invalidation logic
- /// where we must invalidate the results aggregation if any of our component
- /// analyses become invalid.
- void addAADependencyID(AnalysisKey *ID) { AADeps.push_back(ID); }
- /// Handle invalidation events in the new pass manager.
- ///
- /// The aggregation is invalidated if any of the underlying analyses is
- /// invalidated.
- bool invalidate(Function &F, const PreservedAnalyses &PA,
- FunctionAnalysisManager::Invalidator &Inv);
- //===--------------------------------------------------------------------===//
- /// \name Alias Queries
- /// @{
- /// The main low level interface to the alias analysis implementation.
- /// Returns an AliasResult indicating whether the two pointers are aliased to
- /// each other. This is the interface that must be implemented by specific
- /// alias analysis implementations.
- AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB);
- /// A convenience wrapper around the primary \c alias interface.
- AliasResult alias(const Value *V1, LocationSize V1Size, const Value *V2,
- LocationSize V2Size) {
- return alias(MemoryLocation(V1, V1Size), MemoryLocation(V2, V2Size));
- }
- /// A convenience wrapper around the primary \c alias interface.
- AliasResult alias(const Value *V1, const Value *V2) {
- return alias(MemoryLocation::getBeforeOrAfter(V1),
- MemoryLocation::getBeforeOrAfter(V2));
- }
- /// A trivial helper function to check to see if the specified pointers are
- /// no-alias.
- bool isNoAlias(const MemoryLocation &LocA, const MemoryLocation &LocB) {
- return alias(LocA, LocB) == AliasResult::NoAlias;
- }
- /// A convenience wrapper around the \c isNoAlias helper interface.
- bool isNoAlias(const Value *V1, LocationSize V1Size, const Value *V2,
- LocationSize V2Size) {
- return isNoAlias(MemoryLocation(V1, V1Size), MemoryLocation(V2, V2Size));
- }
- /// A convenience wrapper around the \c isNoAlias helper interface.
- bool isNoAlias(const Value *V1, const Value *V2) {
- return isNoAlias(MemoryLocation::getBeforeOrAfter(V1),
- MemoryLocation::getBeforeOrAfter(V2));
- }
- /// A trivial helper function to check to see if the specified pointers are
- /// must-alias.
- bool isMustAlias(const MemoryLocation &LocA, const MemoryLocation &LocB) {
- return alias(LocA, LocB) == AliasResult::MustAlias;
- }
- /// A convenience wrapper around the \c isMustAlias helper interface.
- bool isMustAlias(const Value *V1, const Value *V2) {
- return alias(V1, LocationSize::precise(1), V2, LocationSize::precise(1)) ==
- AliasResult::MustAlias;
- }
- /// Checks whether the given location points to constant memory, or if
- /// \p OrLocal is true whether it points to a local alloca.
- bool pointsToConstantMemory(const MemoryLocation &Loc, bool OrLocal = false) {
- return isNoModRef(getModRefInfoMask(Loc, OrLocal));
- }
- /// A convenience wrapper around the primary \c pointsToConstantMemory
- /// interface.
- bool pointsToConstantMemory(const Value *P, bool OrLocal = false) {
- return pointsToConstantMemory(MemoryLocation::getBeforeOrAfter(P), OrLocal);
- }
- /// @}
- //===--------------------------------------------------------------------===//
- /// \name Simple mod/ref information
- /// @{
- /// Returns a bitmask that should be unconditionally applied to the ModRef
- /// info of a memory location. This allows us to eliminate Mod and/or Ref
- /// from the ModRef info based on the knowledge that the memory location
- /// points to constant and/or locally-invariant memory.
- ///
- /// If IgnoreLocals is true, then this method returns NoModRef for memory
- /// that points to a local alloca.
- ModRefInfo getModRefInfoMask(const MemoryLocation &Loc,
- bool IgnoreLocals = false);
- /// A convenience wrapper around the primary \c getModRefInfoMask
- /// interface.
- ModRefInfo getModRefInfoMask(const Value *P, bool IgnoreLocals = false) {
- return getModRefInfoMask(MemoryLocation::getBeforeOrAfter(P), IgnoreLocals);
- }
- /// Get the ModRef info associated with a pointer argument of a call. The
- /// result's bits are set to indicate the allowed aliasing ModRef kinds. Note
- /// that these bits do not necessarily account for the overall behavior of
- /// the function, but rather only provide additional per-argument
- /// information.
- ModRefInfo getArgModRefInfo(const CallBase *Call, unsigned ArgIdx);
- /// Return the behavior of the given call site.
- MemoryEffects getMemoryEffects(const CallBase *Call);
- /// Return the behavior when calling the given function.
- MemoryEffects getMemoryEffects(const Function *F);
- /// Checks if the specified call is known to never read or write memory.
- ///
- /// Note that if the call only reads from known-constant memory, it is also
- /// legal to return true. Also, calls that unwind the stack are legal for
- /// this predicate.
- ///
- /// Many optimizations (such as CSE and LICM) can be performed on such calls
- /// without worrying about aliasing properties, and many calls have this
- /// property (e.g. calls to 'sin' and 'cos').
- ///
- /// This property corresponds to the GCC 'const' attribute.
- bool doesNotAccessMemory(const CallBase *Call) {
- return getMemoryEffects(Call).doesNotAccessMemory();
- }
- /// Checks if the specified function is known to never read or write memory.
- ///
- /// Note that if the function only reads from known-constant memory, it is
- /// also legal to return true. Also, function that unwind the stack are legal
- /// for this predicate.
- ///
- /// Many optimizations (such as CSE and LICM) can be performed on such calls
- /// to such functions without worrying about aliasing properties, and many
- /// functions have this property (e.g. 'sin' and 'cos').
- ///
- /// This property corresponds to the GCC 'const' attribute.
- bool doesNotAccessMemory(const Function *F) {
- return getMemoryEffects(F).doesNotAccessMemory();
- }
- /// Checks if the specified call is known to only read from non-volatile
- /// memory (or not access memory at all).
- ///
- /// Calls that unwind the stack are legal for this predicate.
- ///
- /// This property allows many common optimizations to be performed in the
- /// absence of interfering store instructions, such as CSE of strlen calls.
- ///
- /// This property corresponds to the GCC 'pure' attribute.
- bool onlyReadsMemory(const CallBase *Call) {
- return getMemoryEffects(Call).onlyReadsMemory();
- }
- /// Checks if the specified function is known to only read from non-volatile
- /// memory (or not access memory at all).
- ///
- /// Functions that unwind the stack are legal for this predicate.
- ///
- /// This property allows many common optimizations to be performed in the
- /// absence of interfering store instructions, such as CSE of strlen calls.
- ///
- /// This property corresponds to the GCC 'pure' attribute.
- bool onlyReadsMemory(const Function *F) {
- return getMemoryEffects(F).onlyReadsMemory();
- }
- /// Check whether or not an instruction may read or write the optionally
- /// specified memory location.
- ///
- ///
- /// An instruction that doesn't read or write memory may be trivially LICM'd
- /// for example.
- ///
- /// For function calls, this delegates to the alias-analysis specific
- /// call-site mod-ref behavior queries. Otherwise it delegates to the specific
- /// helpers above.
- ModRefInfo getModRefInfo(const Instruction *I,
- const std::optional<MemoryLocation> &OptLoc) {
- SimpleAAQueryInfo AAQIP(*this);
- return getModRefInfo(I, OptLoc, AAQIP);
- }
- /// A convenience wrapper for constructing the memory location.
- ModRefInfo getModRefInfo(const Instruction *I, const Value *P,
- LocationSize Size) {
- return getModRefInfo(I, MemoryLocation(P, Size));
- }
- /// Return information about whether a call and an instruction may refer to
- /// the same memory locations.
- ModRefInfo getModRefInfo(const Instruction *I, const CallBase *Call);
- /// Return information about whether a particular call site modifies
- /// or reads the specified memory location \p MemLoc before instruction \p I
- /// in a BasicBlock.
- ModRefInfo callCapturesBefore(const Instruction *I,
- const MemoryLocation &MemLoc,
- DominatorTree *DT) {
- SimpleAAQueryInfo AAQIP(*this);
- return callCapturesBefore(I, MemLoc, DT, AAQIP);
- }
- /// A convenience wrapper to synthesize a memory location.
- ModRefInfo callCapturesBefore(const Instruction *I, const Value *P,
- LocationSize Size, DominatorTree *DT) {
- return callCapturesBefore(I, MemoryLocation(P, Size), DT);
- }
- /// @}
- //===--------------------------------------------------------------------===//
- /// \name Higher level methods for querying mod/ref information.
- /// @{
- /// Check if it is possible for execution of the specified basic block to
- /// modify the location Loc.
- bool canBasicBlockModify(const BasicBlock &BB, const MemoryLocation &Loc);
- /// A convenience wrapper synthesizing a memory location.
- bool canBasicBlockModify(const BasicBlock &BB, const Value *P,
- LocationSize Size) {
- return canBasicBlockModify(BB, MemoryLocation(P, Size));
- }
- /// Check if it is possible for the execution of the specified instructions
- /// to mod\ref (according to the mode) the location Loc.
- ///
- /// The instructions to consider are all of the instructions in the range of
- /// [I1,I2] INCLUSIVE. I1 and I2 must be in the same basic block.
- bool canInstructionRangeModRef(const Instruction &I1, const Instruction &I2,
- const MemoryLocation &Loc,
- const ModRefInfo Mode);
- /// A convenience wrapper synthesizing a memory location.
- bool canInstructionRangeModRef(const Instruction &I1, const Instruction &I2,
- const Value *Ptr, LocationSize Size,
- const ModRefInfo Mode) {
- return canInstructionRangeModRef(I1, I2, MemoryLocation(Ptr, Size), Mode);
- }
- // CtxI can be nullptr, in which case the query is whether or not the aliasing
- // relationship holds through the entire function.
- AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB,
- AAQueryInfo &AAQI, const Instruction *CtxI = nullptr);
- bool pointsToConstantMemory(const MemoryLocation &Loc, AAQueryInfo &AAQI,
- bool OrLocal = false);
- ModRefInfo getModRefInfoMask(const MemoryLocation &Loc, AAQueryInfo &AAQI,
- bool IgnoreLocals = false);
- ModRefInfo getModRefInfo(const Instruction *I, const CallBase *Call2,
- AAQueryInfo &AAQIP);
- ModRefInfo getModRefInfo(const CallBase *Call, const MemoryLocation &Loc,
- AAQueryInfo &AAQI);
- ModRefInfo getModRefInfo(const CallBase *Call1, const CallBase *Call2,
- AAQueryInfo &AAQI);
- ModRefInfo getModRefInfo(const VAArgInst *V, const MemoryLocation &Loc,
- AAQueryInfo &AAQI);
- ModRefInfo getModRefInfo(const LoadInst *L, const MemoryLocation &Loc,
- AAQueryInfo &AAQI);
- ModRefInfo getModRefInfo(const StoreInst *S, const MemoryLocation &Loc,
- AAQueryInfo &AAQI);
- ModRefInfo getModRefInfo(const FenceInst *S, const MemoryLocation &Loc,
- AAQueryInfo &AAQI);
- ModRefInfo getModRefInfo(const AtomicCmpXchgInst *CX,
- const MemoryLocation &Loc, AAQueryInfo &AAQI);
- ModRefInfo getModRefInfo(const AtomicRMWInst *RMW, const MemoryLocation &Loc,
- AAQueryInfo &AAQI);
- ModRefInfo getModRefInfo(const CatchPadInst *I, const MemoryLocation &Loc,
- AAQueryInfo &AAQI);
- ModRefInfo getModRefInfo(const CatchReturnInst *I, const MemoryLocation &Loc,
- AAQueryInfo &AAQI);
- ModRefInfo getModRefInfo(const Instruction *I,
- const std::optional<MemoryLocation> &OptLoc,
- AAQueryInfo &AAQIP);
- ModRefInfo callCapturesBefore(const Instruction *I,
- const MemoryLocation &MemLoc, DominatorTree *DT,
- AAQueryInfo &AAQIP);
- MemoryEffects getMemoryEffects(const CallBase *Call, AAQueryInfo &AAQI);
- private:
- class Concept;
- template <typename T> class Model;
- friend class AAResultBase;
- const TargetLibraryInfo &TLI;
- std::vector<std::unique_ptr<Concept>> AAs;
- std::vector<AnalysisKey *> AADeps;
- friend class BatchAAResults;
- };
- /// This class is a wrapper over an AAResults, and it is intended to be used
- /// only when there are no IR changes inbetween queries. BatchAAResults is
- /// reusing the same `AAQueryInfo` to preserve the state across queries,
- /// esentially making AA work in "batch mode". The internal state cannot be
- /// cleared, so to go "out-of-batch-mode", the user must either use AAResults,
- /// or create a new BatchAAResults.
- class BatchAAResults {
- AAResults &AA;
- AAQueryInfo AAQI;
- SimpleCaptureInfo SimpleCI;
- public:
- BatchAAResults(AAResults &AAR) : AA(AAR), AAQI(AAR, &SimpleCI) {}
- BatchAAResults(AAResults &AAR, CaptureInfo *CI) : AA(AAR), AAQI(AAR, CI) {}
- AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB) {
- return AA.alias(LocA, LocB, AAQI);
- }
- bool pointsToConstantMemory(const MemoryLocation &Loc, bool OrLocal = false) {
- return AA.pointsToConstantMemory(Loc, AAQI, OrLocal);
- }
- ModRefInfo getModRefInfoMask(const MemoryLocation &Loc,
- bool IgnoreLocals = false) {
- return AA.getModRefInfoMask(Loc, AAQI, IgnoreLocals);
- }
- ModRefInfo getModRefInfo(const Instruction *I,
- const std::optional<MemoryLocation> &OptLoc) {
- return AA.getModRefInfo(I, OptLoc, AAQI);
- }
- ModRefInfo getModRefInfo(const Instruction *I, const CallBase *Call2) {
- return AA.getModRefInfo(I, Call2, AAQI);
- }
- ModRefInfo getArgModRefInfo(const CallBase *Call, unsigned ArgIdx) {
- return AA.getArgModRefInfo(Call, ArgIdx);
- }
- MemoryEffects getMemoryEffects(const CallBase *Call) {
- return AA.getMemoryEffects(Call, AAQI);
- }
- bool isMustAlias(const MemoryLocation &LocA, const MemoryLocation &LocB) {
- return alias(LocA, LocB) == AliasResult::MustAlias;
- }
- bool isMustAlias(const Value *V1, const Value *V2) {
- return alias(MemoryLocation(V1, LocationSize::precise(1)),
- MemoryLocation(V2, LocationSize::precise(1))) ==
- AliasResult::MustAlias;
- }
- ModRefInfo callCapturesBefore(const Instruction *I,
- const MemoryLocation &MemLoc,
- DominatorTree *DT) {
- return AA.callCapturesBefore(I, MemLoc, DT, AAQI);
- }
- /// Assume that values may come from different cycle iterations.
- void enableCrossIterationMode() {
- AAQI.MayBeCrossIteration = true;
- }
- };
- /// Temporary typedef for legacy code that uses a generic \c AliasAnalysis
- /// pointer or reference.
- using AliasAnalysis = AAResults;
- /// A private abstract base class describing the concept of an individual alias
- /// analysis implementation.
- ///
- /// This interface is implemented by any \c Model instantiation. It is also the
- /// interface which a type used to instantiate the model must provide.
- ///
- /// All of these methods model methods by the same name in the \c
- /// AAResults class. Only differences and specifics to how the
- /// implementations are called are documented here.
- class AAResults::Concept {
- public:
- virtual ~Concept() = 0;
- //===--------------------------------------------------------------------===//
- /// \name Alias Queries
- /// @{
- /// The main low level interface to the alias analysis implementation.
- /// Returns an AliasResult indicating whether the two pointers are aliased to
- /// each other. This is the interface that must be implemented by specific
- /// alias analysis implementations.
- virtual AliasResult alias(const MemoryLocation &LocA,
- const MemoryLocation &LocB, AAQueryInfo &AAQI,
- const Instruction *CtxI) = 0;
- /// @}
- //===--------------------------------------------------------------------===//
- /// \name Simple mod/ref information
- /// @{
- /// Returns a bitmask that should be unconditionally applied to the ModRef
- /// info of a memory location. This allows us to eliminate Mod and/or Ref from
- /// the ModRef info based on the knowledge that the memory location points to
- /// constant and/or locally-invariant memory.
- virtual ModRefInfo getModRefInfoMask(const MemoryLocation &Loc,
- AAQueryInfo &AAQI,
- bool IgnoreLocals) = 0;
- /// Get the ModRef info associated with a pointer argument of a callsite. The
- /// result's bits are set to indicate the allowed aliasing ModRef kinds. Note
- /// that these bits do not necessarily account for the overall behavior of
- /// the function, but rather only provide additional per-argument
- /// information.
- virtual ModRefInfo getArgModRefInfo(const CallBase *Call,
- unsigned ArgIdx) = 0;
- /// Return the behavior of the given call site.
- virtual MemoryEffects getMemoryEffects(const CallBase *Call,
- AAQueryInfo &AAQI) = 0;
- /// Return the behavior when calling the given function.
- virtual MemoryEffects getMemoryEffects(const Function *F) = 0;
- /// getModRefInfo (for call sites) - Return information about whether
- /// a particular call site modifies or reads the specified memory location.
- virtual ModRefInfo getModRefInfo(const CallBase *Call,
- const MemoryLocation &Loc,
- AAQueryInfo &AAQI) = 0;
- /// Return information about whether two call sites may refer to the same set
- /// of memory locations. See the AA documentation for details:
- /// http://llvm.org/docs/AliasAnalysis.html#ModRefInfo
- virtual ModRefInfo getModRefInfo(const CallBase *Call1, const CallBase *Call2,
- AAQueryInfo &AAQI) = 0;
- /// @}
- };
- /// A private class template which derives from \c Concept and wraps some other
- /// type.
- ///
- /// This models the concept by directly forwarding each interface point to the
- /// wrapped type which must implement a compatible interface. This provides
- /// a type erased binding.
- template <typename AAResultT> class AAResults::Model final : public Concept {
- AAResultT &Result;
- public:
- explicit Model(AAResultT &Result, AAResults &AAR) : Result(Result) {}
- ~Model() override = default;
- AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB,
- AAQueryInfo &AAQI, const Instruction *CtxI) override {
- return Result.alias(LocA, LocB, AAQI, CtxI);
- }
- ModRefInfo getModRefInfoMask(const MemoryLocation &Loc, AAQueryInfo &AAQI,
- bool IgnoreLocals) override {
- return Result.getModRefInfoMask(Loc, AAQI, IgnoreLocals);
- }
- ModRefInfo getArgModRefInfo(const CallBase *Call, unsigned ArgIdx) override {
- return Result.getArgModRefInfo(Call, ArgIdx);
- }
- MemoryEffects getMemoryEffects(const CallBase *Call,
- AAQueryInfo &AAQI) override {
- return Result.getMemoryEffects(Call, AAQI);
- }
- MemoryEffects getMemoryEffects(const Function *F) override {
- return Result.getMemoryEffects(F);
- }
- ModRefInfo getModRefInfo(const CallBase *Call, const MemoryLocation &Loc,
- AAQueryInfo &AAQI) override {
- return Result.getModRefInfo(Call, Loc, AAQI);
- }
- ModRefInfo getModRefInfo(const CallBase *Call1, const CallBase *Call2,
- AAQueryInfo &AAQI) override {
- return Result.getModRefInfo(Call1, Call2, AAQI);
- }
- };
- /// A base class to help implement the function alias analysis results concept.
- ///
- /// Because of the nature of many alias analysis implementations, they often
- /// only implement a subset of the interface. This base class will attempt to
- /// implement the remaining portions of the interface in terms of simpler forms
- /// of the interface where possible, and otherwise provide conservatively
- /// correct fallback implementations.
- ///
- /// Implementors of an alias analysis should derive from this class, and then
- /// override specific methods that they wish to customize. There is no need to
- /// use virtual anywhere.
- class AAResultBase {
- protected:
- explicit AAResultBase() = default;
- // Provide all the copy and move constructors so that derived types aren't
- // constrained.
- AAResultBase(const AAResultBase &Arg) {}
- AAResultBase(AAResultBase &&Arg) {}
- public:
- AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB,
- AAQueryInfo &AAQI, const Instruction *I) {
- return AliasResult::MayAlias;
- }
- ModRefInfo getModRefInfoMask(const MemoryLocation &Loc, AAQueryInfo &AAQI,
- bool IgnoreLocals) {
- return ModRefInfo::ModRef;
- }
- ModRefInfo getArgModRefInfo(const CallBase *Call, unsigned ArgIdx) {
- return ModRefInfo::ModRef;
- }
- MemoryEffects getMemoryEffects(const CallBase *Call, AAQueryInfo &AAQI) {
- return MemoryEffects::unknown();
- }
- MemoryEffects getMemoryEffects(const Function *F) {
- return MemoryEffects::unknown();
- }
- ModRefInfo getModRefInfo(const CallBase *Call, const MemoryLocation &Loc,
- AAQueryInfo &AAQI) {
- return ModRefInfo::ModRef;
- }
- ModRefInfo getModRefInfo(const CallBase *Call1, const CallBase *Call2,
- AAQueryInfo &AAQI) {
- return ModRefInfo::ModRef;
- }
- };
- /// Return true if this pointer is returned by a noalias function.
- bool isNoAliasCall(const Value *V);
- /// Return true if this pointer refers to a distinct and identifiable object.
- /// This returns true for:
- /// Global Variables and Functions (but not Global Aliases)
- /// Allocas
- /// ByVal and NoAlias Arguments
- /// NoAlias returns (e.g. calls to malloc)
- ///
- bool isIdentifiedObject(const Value *V);
- /// Return true if V is umabigously identified at the function-level.
- /// Different IdentifiedFunctionLocals can't alias.
- /// Further, an IdentifiedFunctionLocal can not alias with any function
- /// arguments other than itself, which is not necessarily true for
- /// IdentifiedObjects.
- bool isIdentifiedFunctionLocal(const Value *V);
- /// Returns true if the pointer is one which would have been considered an
- /// escape by isNonEscapingLocalObject.
- bool isEscapeSource(const Value *V);
- /// Return true if Object memory is not visible after an unwind, in the sense
- /// that program semantics cannot depend on Object containing any particular
- /// value on unwind. If the RequiresNoCaptureBeforeUnwind out parameter is set
- /// to true, then the memory is only not visible if the object has not been
- /// captured prior to the unwind. Otherwise it is not visible even if captured.
- bool isNotVisibleOnUnwind(const Value *Object,
- bool &RequiresNoCaptureBeforeUnwind);
- /// A manager for alias analyses.
- ///
- /// This class can have analyses registered with it and when run, it will run
- /// all of them and aggregate their results into single AA results interface
- /// that dispatches across all of the alias analysis results available.
- ///
- /// Note that the order in which analyses are registered is very significant.
- /// That is the order in which the results will be aggregated and queried.
- ///
- /// This manager effectively wraps the AnalysisManager for registering alias
- /// analyses. When you register your alias analysis with this manager, it will
- /// ensure the analysis itself is registered with its AnalysisManager.
- ///
- /// The result of this analysis is only invalidated if one of the particular
- /// aggregated AA results end up being invalidated. This removes the need to
- /// explicitly preserve the results of `AAManager`. Note that analyses should no
- /// longer be registered once the `AAManager` is run.
- class AAManager : public AnalysisInfoMixin<AAManager> {
- public:
- using Result = AAResults;
- /// Register a specific AA result.
- template <typename AnalysisT> void registerFunctionAnalysis() {
- ResultGetters.push_back(&getFunctionAAResultImpl<AnalysisT>);
- }
- /// Register a specific AA result.
- template <typename AnalysisT> void registerModuleAnalysis() {
- ResultGetters.push_back(&getModuleAAResultImpl<AnalysisT>);
- }
- Result run(Function &F, FunctionAnalysisManager &AM);
- private:
- friend AnalysisInfoMixin<AAManager>;
- static AnalysisKey Key;
- SmallVector<void (*)(Function &F, FunctionAnalysisManager &AM,
- AAResults &AAResults),
- 4> ResultGetters;
- template <typename AnalysisT>
- static void getFunctionAAResultImpl(Function &F,
- FunctionAnalysisManager &AM,
- AAResults &AAResults) {
- AAResults.addAAResult(AM.template getResult<AnalysisT>(F));
- AAResults.addAADependencyID(AnalysisT::ID());
- }
- template <typename AnalysisT>
- static void getModuleAAResultImpl(Function &F, FunctionAnalysisManager &AM,
- AAResults &AAResults) {
- auto &MAMProxy = AM.getResult<ModuleAnalysisManagerFunctionProxy>(F);
- if (auto *R =
- MAMProxy.template getCachedResult<AnalysisT>(*F.getParent())) {
- AAResults.addAAResult(*R);
- MAMProxy
- .template registerOuterAnalysisInvalidation<AnalysisT, AAManager>();
- }
- }
- };
- /// A wrapper pass to provide the legacy pass manager access to a suitably
- /// prepared AAResults object.
- class AAResultsWrapperPass : public FunctionPass {
- std::unique_ptr<AAResults> AAR;
- public:
- static char ID;
- AAResultsWrapperPass();
- AAResults &getAAResults() { return *AAR; }
- const AAResults &getAAResults() const { return *AAR; }
- bool runOnFunction(Function &F) override;
- void getAnalysisUsage(AnalysisUsage &AU) const override;
- };
- /// A wrapper pass for external alias analyses. This just squirrels away the
- /// callback used to run any analyses and register their results.
- struct ExternalAAWrapperPass : ImmutablePass {
- using CallbackT = std::function<void(Pass &, Function &, AAResults &)>;
- CallbackT CB;
- static char ID;
- ExternalAAWrapperPass();
- explicit ExternalAAWrapperPass(CallbackT CB);
- void getAnalysisUsage(AnalysisUsage &AU) const override {
- AU.setPreservesAll();
- }
- };
- FunctionPass *createAAResultsWrapperPass();
- /// A wrapper pass around a callback which can be used to populate the
- /// AAResults in the AAResultsWrapperPass from an external AA.
- ///
- /// The callback provided here will be used each time we prepare an AAResults
- /// object, and will receive a reference to the function wrapper pass, the
- /// function, and the AAResults object to populate. This should be used when
- /// setting up a custom pass pipeline to inject a hook into the AA results.
- ImmutablePass *createExternalAAWrapperPass(
- std::function<void(Pass &, Function &, AAResults &)> Callback);
- /// A helper for the legacy pass manager to create a \c AAResults
- /// object populated to the best of our ability for a particular function when
- /// inside of a \c ModulePass or a \c CallGraphSCCPass.
- ///
- /// If a \c ModulePass or a \c CallGraphSCCPass calls \p
- /// createLegacyPMAAResults, it also needs to call \p addUsedAAAnalyses in \p
- /// getAnalysisUsage.
- AAResults createLegacyPMAAResults(Pass &P, Function &F, BasicAAResult &BAR);
- /// A helper for the legacy pass manager to populate \p AU to add uses to make
- /// sure the analyses required by \p createLegacyPMAAResults are available.
- void getAAResultsAnalysisUsage(AnalysisUsage &AU);
- } // end namespace llvm
- #endif // LLVM_ANALYSIS_ALIASANALYSIS_H
- #ifdef __GNUC__
- #pragma GCC diagnostic pop
- #endif
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