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      1 //===- llvm/Analysis/AliasAnalysis.h - Alias Analysis Interface -*- 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 generic AliasAnalysis interface, which is used as the
     11 // common interface used by all clients of alias analysis information, and
     12 // implemented by all alias analysis implementations.  Mod/Ref information is
     13 // also captured by this interface.
     14 //
     15 // Implementations of this interface must implement the various virtual methods,
     16 // which automatically provides functionality for the entire suite of client
     17 // APIs.
     18 //
     19 // This API identifies memory regions with the Location class. The pointer
     20 // component specifies the base memory address of the region. The Size specifies
     21 // the maximum size (in address units) of the memory region, or UnknownSize if
     22 // the size is not known. The TBAA tag identifies the "type" of the memory
     23 // reference; see the TypeBasedAliasAnalysis class for details.
     24 //
     25 // Some non-obvious details include:
     26 //  - Pointers that point to two completely different objects in memory never
     27 //    alias, regardless of the value of the Size component.
     28 //  - NoAlias doesn't imply inequal pointers. The most obvious example of this
     29 //    is two pointers to constant memory. Even if they are equal, constant
     30 //    memory is never stored to, so there will never be any dependencies.
     31 //    In this and other situations, the pointers may be both NoAlias and
     32 //    MustAlias at the same time. The current API can only return one result,
     33 //    though this is rarely a problem in practice.
     34 //
     35 //===----------------------------------------------------------------------===//
     36 
     37 #ifndef LLVM_ANALYSIS_ALIAS_ANALYSIS_H
     38 #define LLVM_ANALYSIS_ALIAS_ANALYSIS_H
     39 
     40 #include "llvm/Support/CallSite.h"
     41 #include "llvm/ADT/DenseMap.h"
     42 
     43 namespace llvm {
     44 
     45 class LoadInst;
     46 class StoreInst;
     47 class VAArgInst;
     48 class TargetData;
     49 class Pass;
     50 class AnalysisUsage;
     51 class MemTransferInst;
     52 class MemIntrinsic;
     53 
     54 class AliasAnalysis {
     55 protected:
     56   const TargetData *TD;
     57 
     58 private:
     59   AliasAnalysis *AA;       // Previous Alias Analysis to chain to.
     60 
     61 protected:
     62   /// InitializeAliasAnalysis - Subclasses must call this method to initialize
     63   /// the AliasAnalysis interface before any other methods are called.  This is
     64   /// typically called by the run* methods of these subclasses.  This may be
     65   /// called multiple times.
     66   ///
     67   void InitializeAliasAnalysis(Pass *P);
     68 
     69   /// getAnalysisUsage - All alias analysis implementations should invoke this
     70   /// directly (using AliasAnalysis::getAnalysisUsage(AU)).
     71   virtual void getAnalysisUsage(AnalysisUsage &AU) const;
     72 
     73 public:
     74   static char ID; // Class identification, replacement for typeinfo
     75   AliasAnalysis() : TD(0), AA(0) {}
     76   virtual ~AliasAnalysis();  // We want to be subclassed
     77 
     78   /// UnknownSize - This is a special value which can be used with the
     79   /// size arguments in alias queries to indicate that the caller does not
     80   /// know the sizes of the potential memory references.
     81   static uint64_t const UnknownSize = ~UINT64_C(0);
     82 
     83   /// getTargetData - Return a pointer to the current TargetData object, or
     84   /// null if no TargetData object is available.
     85   ///
     86   const TargetData *getTargetData() const { return TD; }
     87 
     88   /// getTypeStoreSize - Return the TargetData store size for the given type,
     89   /// if known, or a conservative value otherwise.
     90   ///
     91   uint64_t getTypeStoreSize(Type *Ty);
     92 
     93   //===--------------------------------------------------------------------===//
     94   /// Alias Queries...
     95   ///
     96 
     97   /// Location - A description of a memory location.
     98   struct Location {
     99     /// Ptr - The address of the start of the location.
    100     const Value *Ptr;
    101     /// Size - The maximum size of the location, in address-units, or
    102     /// UnknownSize if the size is not known.  Note that an unknown size does
    103     /// not mean the pointer aliases the entire virtual address space, because
    104     /// there are restrictions on stepping out of one object and into another.
    105     /// See http://llvm.org/docs/LangRef.html#pointeraliasing
    106     uint64_t Size;
    107     /// TBAATag - The metadata node which describes the TBAA type of
    108     /// the location, or null if there is no known unique tag.
    109     const MDNode *TBAATag;
    110 
    111     explicit Location(const Value *P = 0, uint64_t S = UnknownSize,
    112                       const MDNode *N = 0)
    113       : Ptr(P), Size(S), TBAATag(N) {}
    114 
    115     Location getWithNewPtr(const Value *NewPtr) const {
    116       Location Copy(*this);
    117       Copy.Ptr = NewPtr;
    118       return Copy;
    119     }
    120 
    121     Location getWithNewSize(uint64_t NewSize) const {
    122       Location Copy(*this);
    123       Copy.Size = NewSize;
    124       return Copy;
    125     }
    126 
    127     Location getWithoutTBAATag() const {
    128       Location Copy(*this);
    129       Copy.TBAATag = 0;
    130       return Copy;
    131     }
    132   };
    133 
    134   /// getLocation - Fill in Loc with information about the memory reference by
    135   /// the given instruction.
    136   Location getLocation(const LoadInst *LI);
    137   Location getLocation(const StoreInst *SI);
    138   Location getLocation(const VAArgInst *VI);
    139   Location getLocation(const AtomicCmpXchgInst *CXI);
    140   Location getLocation(const AtomicRMWInst *RMWI);
    141   static Location getLocationForSource(const MemTransferInst *MTI);
    142   static Location getLocationForDest(const MemIntrinsic *MI);
    143 
    144   /// Alias analysis result - Either we know for sure that it does not alias, we
    145   /// know for sure it must alias, or we don't know anything: The two pointers
    146   /// _might_ alias.  This enum is designed so you can do things like:
    147   ///     if (AA.alias(P1, P2)) { ... }
    148   /// to check to see if two pointers might alias.
    149   ///
    150   /// See docs/AliasAnalysis.html for more information on the specific meanings
    151   /// of these values.
    152   ///
    153   enum AliasResult {
    154     NoAlias = 0,        ///< No dependencies.
    155     MayAlias,           ///< Anything goes.
    156     PartialAlias,       ///< Pointers differ, but pointees overlap.
    157     MustAlias           ///< Pointers are equal.
    158   };
    159 
    160   /// alias - The main low level interface to the alias analysis implementation.
    161   /// Returns an AliasResult indicating whether the two pointers are aliased to
    162   /// each other.  This is the interface that must be implemented by specific
    163   /// alias analysis implementations.
    164   virtual AliasResult alias(const Location &LocA, const Location &LocB);
    165 
    166   /// alias - A convenience wrapper.
    167   AliasResult alias(const Value *V1, uint64_t V1Size,
    168                     const Value *V2, uint64_t V2Size) {
    169     return alias(Location(V1, V1Size), Location(V2, V2Size));
    170   }
    171 
    172   /// alias - A convenience wrapper.
    173   AliasResult alias(const Value *V1, const Value *V2) {
    174     return alias(V1, UnknownSize, V2, UnknownSize);
    175   }
    176 
    177   /// isNoAlias - A trivial helper function to check to see if the specified
    178   /// pointers are no-alias.
    179   bool isNoAlias(const Location &LocA, const Location &LocB) {
    180     return alias(LocA, LocB) == NoAlias;
    181   }
    182 
    183   /// isNoAlias - A convenience wrapper.
    184   bool isNoAlias(const Value *V1, uint64_t V1Size,
    185                  const Value *V2, uint64_t V2Size) {
    186     return isNoAlias(Location(V1, V1Size), Location(V2, V2Size));
    187   }
    188 
    189   /// isMustAlias - A convenience wrapper.
    190   bool isMustAlias(const Location &LocA, const Location &LocB) {
    191     return alias(LocA, LocB) == MustAlias;
    192   }
    193 
    194   /// isMustAlias - A convenience wrapper.
    195   bool isMustAlias(const Value *V1, const Value *V2) {
    196     return alias(V1, 1, V2, 1) == MustAlias;
    197   }
    198 
    199   /// pointsToConstantMemory - If the specified memory location is
    200   /// known to be constant, return true. If OrLocal is true and the
    201   /// specified memory location is known to be "local" (derived from
    202   /// an alloca), return true. Otherwise return false.
    203   virtual bool pointsToConstantMemory(const Location &Loc,
    204                                       bool OrLocal = false);
    205 
    206   /// pointsToConstantMemory - A convenient wrapper.
    207   bool pointsToConstantMemory(const Value *P, bool OrLocal = false) {
    208     return pointsToConstantMemory(Location(P), OrLocal);
    209   }
    210 
    211   //===--------------------------------------------------------------------===//
    212   /// Simple mod/ref information...
    213   ///
    214 
    215   /// ModRefResult - Represent the result of a mod/ref query.  Mod and Ref are
    216   /// bits which may be or'd together.
    217   ///
    218   enum ModRefResult { NoModRef = 0, Ref = 1, Mod = 2, ModRef = 3 };
    219 
    220   /// These values define additional bits used to define the
    221   /// ModRefBehavior values.
    222   enum { Nowhere = 0, ArgumentPointees = 4, Anywhere = 8 | ArgumentPointees };
    223 
    224   /// ModRefBehavior - Summary of how a function affects memory in the program.
    225   /// Loads from constant globals are not considered memory accesses for this
    226   /// interface.  Also, functions may freely modify stack space local to their
    227   /// invocation without having to report it through these interfaces.
    228   enum ModRefBehavior {
    229     /// DoesNotAccessMemory - This function does not perform any non-local loads
    230     /// or stores to memory.
    231     ///
    232     /// This property corresponds to the GCC 'const' attribute.
    233     /// This property corresponds to the LLVM IR 'readnone' attribute.
    234     /// This property corresponds to the IntrNoMem LLVM intrinsic flag.
    235     DoesNotAccessMemory = Nowhere | NoModRef,
    236 
    237     /// OnlyReadsArgumentPointees - The only memory references in this function
    238     /// (if it has any) are non-volatile loads from objects pointed to by its
    239     /// pointer-typed arguments, with arbitrary offsets.
    240     ///
    241     /// This property corresponds to the IntrReadArgMem LLVM intrinsic flag.
    242     OnlyReadsArgumentPointees = ArgumentPointees | Ref,
    243 
    244     /// OnlyAccessesArgumentPointees - The only memory references in this
    245     /// function (if it has any) are non-volatile loads and stores from objects
    246     /// pointed to by its pointer-typed arguments, with arbitrary offsets.
    247     ///
    248     /// This property corresponds to the IntrReadWriteArgMem LLVM intrinsic flag.
    249     OnlyAccessesArgumentPointees = ArgumentPointees | ModRef,
    250 
    251     /// OnlyReadsMemory - This function does not perform any non-local stores or
    252     /// volatile loads, but may read from any memory location.
    253     ///
    254     /// This property corresponds to the GCC 'pure' attribute.
    255     /// This property corresponds to the LLVM IR 'readonly' attribute.
    256     /// This property corresponds to the IntrReadMem LLVM intrinsic flag.
    257     OnlyReadsMemory = Anywhere | Ref,
    258 
    259     /// UnknownModRefBehavior - This indicates that the function could not be
    260     /// classified into one of the behaviors above.
    261     UnknownModRefBehavior = Anywhere | ModRef
    262   };
    263 
    264   /// getModRefBehavior - Return the behavior when calling the given call site.
    265   virtual ModRefBehavior getModRefBehavior(ImmutableCallSite CS);
    266 
    267   /// getModRefBehavior - Return the behavior when calling the given function.
    268   /// For use when the call site is not known.
    269   virtual ModRefBehavior getModRefBehavior(const Function *F);
    270 
    271   /// doesNotAccessMemory - If the specified call is known to never read or
    272   /// write memory, return true.  If the call only reads from known-constant
    273   /// memory, it is also legal to return true.  Calls that unwind the stack
    274   /// are legal for this predicate.
    275   ///
    276   /// Many optimizations (such as CSE and LICM) can be performed on such calls
    277   /// without worrying about aliasing properties, and many calls have this
    278   /// property (e.g. calls to 'sin' and 'cos').
    279   ///
    280   /// This property corresponds to the GCC 'const' attribute.
    281   ///
    282   bool doesNotAccessMemory(ImmutableCallSite CS) {
    283     return getModRefBehavior(CS) == DoesNotAccessMemory;
    284   }
    285 
    286   /// doesNotAccessMemory - If the specified function is known to never read or
    287   /// write memory, return true.  For use when the call site is not known.
    288   ///
    289   bool doesNotAccessMemory(const Function *F) {
    290     return getModRefBehavior(F) == DoesNotAccessMemory;
    291   }
    292 
    293   /// onlyReadsMemory - If the specified call is known to only read from
    294   /// non-volatile memory (or not access memory at all), return true.  Calls
    295   /// that unwind the stack are legal for this predicate.
    296   ///
    297   /// This property allows many common optimizations to be performed in the
    298   /// absence of interfering store instructions, such as CSE of strlen calls.
    299   ///
    300   /// This property corresponds to the GCC 'pure' attribute.
    301   ///
    302   bool onlyReadsMemory(ImmutableCallSite CS) {
    303     return onlyReadsMemory(getModRefBehavior(CS));
    304   }
    305 
    306   /// onlyReadsMemory - If the specified function is known to only read from
    307   /// non-volatile memory (or not access memory at all), return true.  For use
    308   /// when the call site is not known.
    309   ///
    310   bool onlyReadsMemory(const Function *F) {
    311     return onlyReadsMemory(getModRefBehavior(F));
    312   }
    313 
    314   /// onlyReadsMemory - Return true if functions with the specified behavior are
    315   /// known to only read from non-volatile memory (or not access memory at all).
    316   ///
    317   static bool onlyReadsMemory(ModRefBehavior MRB) {
    318     return !(MRB & Mod);
    319   }
    320 
    321   /// onlyAccessesArgPointees - Return true if functions with the specified
    322   /// behavior are known to read and write at most from objects pointed to by
    323   /// their pointer-typed arguments (with arbitrary offsets).
    324   ///
    325   static bool onlyAccessesArgPointees(ModRefBehavior MRB) {
    326     return !(MRB & Anywhere & ~ArgumentPointees);
    327   }
    328 
    329   /// doesAccessArgPointees - Return true if functions with the specified
    330   /// behavior are known to potentially read or write from objects pointed
    331   /// to be their pointer-typed arguments (with arbitrary offsets).
    332   ///
    333   static bool doesAccessArgPointees(ModRefBehavior MRB) {
    334     return (MRB & ModRef) && (MRB & ArgumentPointees);
    335   }
    336 
    337   /// getModRefInfo - Return information about whether or not an instruction may
    338   /// read or write the specified memory location.  An instruction
    339   /// that doesn't read or write memory may be trivially LICM'd for example.
    340   ModRefResult getModRefInfo(const Instruction *I,
    341                              const Location &Loc) {
    342     switch (I->getOpcode()) {
    343     case Instruction::VAArg:  return getModRefInfo((const VAArgInst*)I, Loc);
    344     case Instruction::Load:   return getModRefInfo((const LoadInst*)I,  Loc);
    345     case Instruction::Store:  return getModRefInfo((const StoreInst*)I, Loc);
    346     case Instruction::Fence:  return getModRefInfo((const FenceInst*)I, Loc);
    347     case Instruction::AtomicCmpXchg:
    348       return getModRefInfo((const AtomicCmpXchgInst*)I, Loc);
    349     case Instruction::AtomicRMW:
    350       return getModRefInfo((const AtomicRMWInst*)I, Loc);
    351     case Instruction::Call:   return getModRefInfo((const CallInst*)I,  Loc);
    352     case Instruction::Invoke: return getModRefInfo((const InvokeInst*)I,Loc);
    353     default:                  return NoModRef;
    354     }
    355   }
    356 
    357   /// getModRefInfo - A convenience wrapper.
    358   ModRefResult getModRefInfo(const Instruction *I,
    359                              const Value *P, uint64_t Size) {
    360     return getModRefInfo(I, Location(P, Size));
    361   }
    362 
    363   /// getModRefInfo (for call sites) - Return whether information about whether
    364   /// a particular call site modifies or reads the specified memory location.
    365   virtual ModRefResult getModRefInfo(ImmutableCallSite CS,
    366                                      const Location &Loc);
    367 
    368   /// getModRefInfo (for call sites) - A convenience wrapper.
    369   ModRefResult getModRefInfo(ImmutableCallSite CS,
    370                              const Value *P, uint64_t Size) {
    371     return getModRefInfo(CS, Location(P, Size));
    372   }
    373 
    374   /// getModRefInfo (for calls) - Return whether information about whether
    375   /// a particular call modifies or reads the specified memory location.
    376   ModRefResult getModRefInfo(const CallInst *C, const Location &Loc) {
    377     return getModRefInfo(ImmutableCallSite(C), Loc);
    378   }
    379 
    380   /// getModRefInfo (for calls) - A convenience wrapper.
    381   ModRefResult getModRefInfo(const CallInst *C, const Value *P, uint64_t Size) {
    382     return getModRefInfo(C, Location(P, Size));
    383   }
    384 
    385   /// getModRefInfo (for invokes) - Return whether information about whether
    386   /// a particular invoke modifies or reads the specified memory location.
    387   ModRefResult getModRefInfo(const InvokeInst *I,
    388                              const Location &Loc) {
    389     return getModRefInfo(ImmutableCallSite(I), Loc);
    390   }
    391 
    392   /// getModRefInfo (for invokes) - A convenience wrapper.
    393   ModRefResult getModRefInfo(const InvokeInst *I,
    394                              const Value *P, uint64_t Size) {
    395     return getModRefInfo(I, Location(P, Size));
    396   }
    397 
    398   /// getModRefInfo (for loads) - Return whether information about whether
    399   /// a particular load modifies or reads the specified memory location.
    400   ModRefResult getModRefInfo(const LoadInst *L, const Location &Loc);
    401 
    402   /// getModRefInfo (for loads) - A convenience wrapper.
    403   ModRefResult getModRefInfo(const LoadInst *L, const Value *P, uint64_t Size) {
    404     return getModRefInfo(L, Location(P, Size));
    405   }
    406 
    407   /// getModRefInfo (for stores) - Return whether information about whether
    408   /// a particular store modifies or reads the specified memory location.
    409   ModRefResult getModRefInfo(const StoreInst *S, const Location &Loc);
    410 
    411   /// getModRefInfo (for stores) - A convenience wrapper.
    412   ModRefResult getModRefInfo(const StoreInst *S, const Value *P, uint64_t Size){
    413     return getModRefInfo(S, Location(P, Size));
    414   }
    415 
    416   /// getModRefInfo (for fences) - Return whether information about whether
    417   /// a particular store modifies or reads the specified memory location.
    418   ModRefResult getModRefInfo(const FenceInst *S, const Location &Loc) {
    419     // Conservatively correct.  (We could possibly be a bit smarter if
    420     // Loc is a alloca that doesn't escape.)
    421     return ModRef;
    422   }
    423 
    424   /// getModRefInfo (for fences) - A convenience wrapper.
    425   ModRefResult getModRefInfo(const FenceInst *S, const Value *P, uint64_t Size){
    426     return getModRefInfo(S, Location(P, Size));
    427   }
    428 
    429   /// getModRefInfo (for cmpxchges) - Return whether information about whether
    430   /// a particular cmpxchg modifies or reads the specified memory location.
    431   ModRefResult getModRefInfo(const AtomicCmpXchgInst *CX, const Location &Loc);
    432 
    433   /// getModRefInfo (for cmpxchges) - A convenience wrapper.
    434   ModRefResult getModRefInfo(const AtomicCmpXchgInst *CX,
    435                              const Value *P, unsigned Size) {
    436     return getModRefInfo(CX, Location(P, Size));
    437   }
    438 
    439   /// getModRefInfo (for atomicrmws) - Return whether information about whether
    440   /// a particular atomicrmw modifies or reads the specified memory location.
    441   ModRefResult getModRefInfo(const AtomicRMWInst *RMW, const Location &Loc);
    442 
    443   /// getModRefInfo (for atomicrmws) - A convenience wrapper.
    444   ModRefResult getModRefInfo(const AtomicRMWInst *RMW,
    445                              const Value *P, unsigned Size) {
    446     return getModRefInfo(RMW, Location(P, Size));
    447   }
    448 
    449   /// getModRefInfo (for va_args) - Return whether information about whether
    450   /// a particular va_arg modifies or reads the specified memory location.
    451   ModRefResult getModRefInfo(const VAArgInst* I, const Location &Loc);
    452 
    453   /// getModRefInfo (for va_args) - A convenience wrapper.
    454   ModRefResult getModRefInfo(const VAArgInst* I, const Value* P, uint64_t Size){
    455     return getModRefInfo(I, Location(P, Size));
    456   }
    457 
    458   /// getModRefInfo - Return information about whether two call sites may refer
    459   /// to the same set of memory locations.  See
    460   ///   http://llvm.org/docs/AliasAnalysis.html#ModRefInfo
    461   /// for details.
    462   virtual ModRefResult getModRefInfo(ImmutableCallSite CS1,
    463                                      ImmutableCallSite CS2);
    464 
    465   //===--------------------------------------------------------------------===//
    466   /// Higher level methods for querying mod/ref information.
    467   ///
    468 
    469   /// canBasicBlockModify - Return true if it is possible for execution of the
    470   /// specified basic block to modify the value pointed to by Ptr.
    471   bool canBasicBlockModify(const BasicBlock &BB, const Location &Loc);
    472 
    473   /// canBasicBlockModify - A convenience wrapper.
    474   bool canBasicBlockModify(const BasicBlock &BB, const Value *P, uint64_t Size){
    475     return canBasicBlockModify(BB, Location(P, Size));
    476   }
    477 
    478   /// canInstructionRangeModify - Return true if it is possible for the
    479   /// execution of the specified instructions to modify the value pointed to by
    480   /// Ptr.  The instructions to consider are all of the instructions in the
    481   /// range of [I1,I2] INCLUSIVE.  I1 and I2 must be in the same basic block.
    482   bool canInstructionRangeModify(const Instruction &I1, const Instruction &I2,
    483                                  const Location &Loc);
    484 
    485   /// canInstructionRangeModify - A convenience wrapper.
    486   bool canInstructionRangeModify(const Instruction &I1, const Instruction &I2,
    487                                  const Value *Ptr, uint64_t Size) {
    488     return canInstructionRangeModify(I1, I2, Location(Ptr, Size));
    489   }
    490 
    491   //===--------------------------------------------------------------------===//
    492   /// Methods that clients should call when they transform the program to allow
    493   /// alias analyses to update their internal data structures.  Note that these
    494   /// methods may be called on any instruction, regardless of whether or not
    495   /// they have pointer-analysis implications.
    496   ///
    497 
    498   /// deleteValue - This method should be called whenever an LLVM Value is
    499   /// deleted from the program, for example when an instruction is found to be
    500   /// redundant and is eliminated.
    501   ///
    502   virtual void deleteValue(Value *V);
    503 
    504   /// copyValue - This method should be used whenever a preexisting value in the
    505   /// program is copied or cloned, introducing a new value.  Note that analysis
    506   /// implementations should tolerate clients that use this method to introduce
    507   /// the same value multiple times: if the analysis already knows about a
    508   /// value, it should ignore the request.
    509   ///
    510   virtual void copyValue(Value *From, Value *To);
    511 
    512   /// addEscapingUse - This method should be used whenever an escaping use is
    513   /// added to a pointer value.  Analysis implementations may either return
    514   /// conservative responses for that value in the future, or may recompute
    515   /// some or all internal state to continue providing precise responses.
    516   ///
    517   /// Escaping uses are considered by anything _except_ the following:
    518   ///  - GEPs or bitcasts of the pointer
    519   ///  - Loads through the pointer
    520   ///  - Stores through (but not of) the pointer
    521   virtual void addEscapingUse(Use &U);
    522 
    523   /// replaceWithNewValue - This method is the obvious combination of the two
    524   /// above, and it provided as a helper to simplify client code.
    525   ///
    526   void replaceWithNewValue(Value *Old, Value *New) {
    527     copyValue(Old, New);
    528     deleteValue(Old);
    529   }
    530 };
    531 
    532 // Specialize DenseMapInfo for Location.
    533 template<>
    534 struct DenseMapInfo<AliasAnalysis::Location> {
    535   static inline AliasAnalysis::Location getEmptyKey() {
    536     return
    537       AliasAnalysis::Location(DenseMapInfo<const Value *>::getEmptyKey(),
    538                               0, 0);
    539   }
    540   static inline AliasAnalysis::Location getTombstoneKey() {
    541     return
    542       AliasAnalysis::Location(DenseMapInfo<const Value *>::getTombstoneKey(),
    543                               0, 0);
    544   }
    545   static unsigned getHashValue(const AliasAnalysis::Location &Val) {
    546     return DenseMapInfo<const Value *>::getHashValue(Val.Ptr) ^
    547            DenseMapInfo<uint64_t>::getHashValue(Val.Size) ^
    548            DenseMapInfo<const MDNode *>::getHashValue(Val.TBAATag);
    549   }
    550   static bool isEqual(const AliasAnalysis::Location &LHS,
    551                       const AliasAnalysis::Location &RHS) {
    552     return LHS.Ptr == RHS.Ptr &&
    553            LHS.Size == RHS.Size &&
    554            LHS.TBAATag == RHS.TBAATag;
    555   }
    556 };
    557 
    558 /// isNoAliasCall - Return true if this pointer is returned by a noalias
    559 /// function.
    560 bool isNoAliasCall(const Value *V);
    561 
    562 /// isIdentifiedObject - Return true if this pointer refers to a distinct and
    563 /// identifiable object.  This returns true for:
    564 ///    Global Variables and Functions (but not Global Aliases)
    565 ///    Allocas and Mallocs
    566 ///    ByVal and NoAlias Arguments
    567 ///    NoAlias returns
    568 ///
    569 bool isIdentifiedObject(const Value *V);
    570 
    571 } // End llvm namespace
    572 
    573 #endif
    574