| //===- llvm/Analysis/AliasAnalysis.h - Alias Analysis Interface -*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file was developed by the LLVM research group and is distributed under |
| // the University of Illinois Open Source License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // 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 represents memory as a (Pointer, Size) pair. The Pointer component |
| // specifies the base memory address of the region, the Size specifies how large |
| // of an area is being queried. If Size is 0, two pointers only alias if they |
| // are exactly equal. If size is greater than zero, but small, the two pointers |
| // alias if the areas pointed to overlap. If the size is very large (ie, ~0U), |
| // then the two pointers alias if they may be pointing to components of the same |
| // memory object. Pointers that point to two completely different objects in |
| // memory never alias, regardless of the value of the Size component. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_ANALYSIS_ALIAS_ANALYSIS_H |
| #define LLVM_ANALYSIS_ALIAS_ANALYSIS_H |
| |
| #include "llvm/Support/CallSite.h" |
| class LoadInst; |
| class StoreInst; |
| class TargetData; |
| class AnalysisUsage; |
| class Pass; |
| |
| class AliasAnalysis { |
| const TargetData *TD; |
| protected: |
| /// InitializeAliasAnalysis - Subclasses must call this method to initialize |
| /// the AliasAnalysis interface before any other methods are called. This is |
| /// typically called by the run* methods of these subclasses. This may be |
| /// called multiple times. |
| /// |
| void InitializeAliasAnalysis(Pass *P); |
| |
| // getAnalysisUsage - All alias analysis implementations should invoke this |
| // directly (using AliasAnalysis::getAnalysisUsage(AU)) to make sure that |
| // TargetData is required by the pass. |
| virtual void getAnalysisUsage(AnalysisUsage &AU) const; |
| |
| public: |
| AliasAnalysis() : TD(0) {} |
| virtual ~AliasAnalysis(); // We want to be subclassed |
| |
| /// getTargetData - Every alias analysis implementation depends on the size of |
| /// data items in the current Target. This provides a uniform way to handle |
| /// it. |
| const TargetData &getTargetData() const { return *TD; } |
| |
| //===--------------------------------------------------------------------===// |
| /// Alias Queries... |
| /// |
| |
| /// Alias analysis result - Either we know for sure that it does not alias, we |
| /// know for sure it must alias, or we don't know anything: The two pointers |
| /// _might_ alias. This enum is designed so you can do things like: |
| /// if (AA.alias(P1, P2)) { ... } |
| /// to check to see if two pointers might alias. |
| /// |
| enum AliasResult { NoAlias = 0, MayAlias = 1, MustAlias = 2 }; |
| |
| /// alias - The main low level interface to the alias analysis implementation. |
| /// Returns a Result 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 Value *V1, unsigned V1Size, |
| const Value *V2, unsigned V2Size) { |
| return MayAlias; |
| } |
| |
| /// getMustAliases - If there are any pointers known that must alias this |
| /// pointer, return them now. This allows alias-set based alias analyses to |
| /// perform a form a value numbering (which is exposed by load-vn). If an |
| /// alias analysis supports this, it should ADD any must aliased pointers to |
| /// the specified vector. |
| /// |
| virtual void getMustAliases(Value *P, std::vector<Value*> &RetVals) {} |
| |
| |
| //===--------------------------------------------------------------------===// |
| /// Simple mod/ref information... |
| /// |
| |
| /// ModRefResult - Represent the result of a mod/ref query. Mod and Ref are |
| /// bits which may be or'd together. |
| /// |
| enum ModRefResult { NoModRef = 0, Ref = 1, Mod = 2, ModRef = 3 }; |
| |
| /// getModRefInfo - Return information about whether or not an instruction may |
| /// read or write memory specified by the pointer operand. An instruction |
| /// that doesn't read or write memory may be trivially LICM'd for example. |
| |
| /// getModRefInfo (for call sites) - Return whether information about whether |
| /// a particular call site modifies or reads the memory specified by the |
| /// pointer. |
| /// |
| virtual ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size) { |
| return ModRef; |
| } |
| |
| /// getModRefInfo - Return information about whether two call sites may refer |
| /// to the same set of memory locations. This function returns NoModRef if |
| /// the two calls refer to disjoint memory locations, Ref if they both read |
| /// some of the same memory, Mod if they both write to some of the same |
| /// memory, and ModRef if they read and write to the same memory. |
| /// |
| virtual ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) { |
| return ModRef; |
| } |
| |
| /// Convenience functions... |
| ModRefResult getModRefInfo(LoadInst *L, Value *P, unsigned Size); |
| ModRefResult getModRefInfo(StoreInst*S, Value *P, unsigned Size); |
| ModRefResult getModRefInfo(CallInst *C, Value *P, unsigned Size) { |
| return getModRefInfo(CallSite(C), P, Size); |
| } |
| ModRefResult getModRefInfo(InvokeInst*I, Value *P, unsigned Size) { |
| return getModRefInfo(CallSite(I), P, Size); |
| } |
| ModRefResult getModRefInfo(Instruction *I, Value *P, unsigned Size) { |
| switch (I->getOpcode()) { |
| case Instruction::Load: return getModRefInfo((LoadInst*)I, P, Size); |
| case Instruction::Store: return getModRefInfo((StoreInst*)I, P, Size); |
| case Instruction::Call: return getModRefInfo((CallInst*)I, P, Size); |
| case Instruction::Invoke: return getModRefInfo((InvokeInst*)I, P, Size); |
| default: return NoModRef; |
| } |
| } |
| |
| /// canBasicBlockModify - Return true if it is possible for execution of the |
| /// specified basic block to modify the value pointed to by Ptr. |
| /// |
| bool canBasicBlockModify(const BasicBlock &BB, const Value *P, unsigned Size); |
| |
| /// canInstructionRangeModify - Return true if it is possible for the |
| /// execution of the specified instructions to modify the value pointed to by |
| /// Ptr. 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 canInstructionRangeModify(const Instruction &I1, const Instruction &I2, |
| const Value *Ptr, unsigned Size); |
| }; |
| |
| #endif |