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      1 //===- TypeBasedAliasAnalysis.h - Type-Based Alias Analysis -----*- 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 /// \file
     10 /// This is the interface for a metadata-based TBAA. See the source file for
     11 /// details on the algorithm.
     12 ///
     13 //===----------------------------------------------------------------------===//
     14 
     15 #ifndef LLVM_ANALYSIS_TYPEBASEDALIASANALYSIS_H
     16 #define LLVM_ANALYSIS_TYPEBASEDALIASANALYSIS_H
     17 
     18 #include "llvm/Analysis/AliasAnalysis.h"
     19 #include "llvm/IR/Function.h"
     20 #include "llvm/IR/Metadata.h"
     21 #include "llvm/Pass.h"
     22 
     23 namespace llvm {
     24 
     25 /// A simple AA result that uses TBAA metadata to answer queries.
     26 class TypeBasedAAResult : public AAResultBase<TypeBasedAAResult> {
     27   friend AAResultBase<TypeBasedAAResult>;
     28 
     29 public:
     30   explicit TypeBasedAAResult(const TargetLibraryInfo &TLI)
     31       : AAResultBase(TLI) {}
     32   TypeBasedAAResult(TypeBasedAAResult &&Arg) : AAResultBase(std::move(Arg)) {}
     33 
     34   /// Handle invalidation events from the new pass manager.
     35   ///
     36   /// By definition, this result is stateless and so remains valid.
     37   bool invalidate(Function &, const PreservedAnalyses &) { return false; }
     38 
     39   AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB);
     40   bool pointsToConstantMemory(const MemoryLocation &Loc, bool OrLocal);
     41   FunctionModRefBehavior getModRefBehavior(ImmutableCallSite CS);
     42   FunctionModRefBehavior getModRefBehavior(const Function *F);
     43   ModRefInfo getModRefInfo(ImmutableCallSite CS, const MemoryLocation &Loc);
     44   ModRefInfo getModRefInfo(ImmutableCallSite CS1, ImmutableCallSite CS2);
     45 
     46 private:
     47   bool Aliases(const MDNode *A, const MDNode *B) const;
     48   bool PathAliases(const MDNode *A, const MDNode *B) const;
     49 };
     50 
     51 /// Analysis pass providing a never-invalidated alias analysis result.
     52 class TypeBasedAA {
     53 public:
     54   typedef TypeBasedAAResult Result;
     55 
     56   /// \brief Opaque, unique identifier for this analysis pass.
     57   static void *ID() { return (void *)&PassID; }
     58 
     59   TypeBasedAAResult run(Function &F, AnalysisManager<Function> *AM);
     60 
     61   /// \brief Provide access to a name for this pass for debugging purposes.
     62   static StringRef name() { return "TypeBasedAA"; }
     63 
     64 private:
     65   static char PassID;
     66 };
     67 
     68 /// Legacy wrapper pass to provide the TypeBasedAAResult object.
     69 class TypeBasedAAWrapperPass : public ImmutablePass {
     70   std::unique_ptr<TypeBasedAAResult> Result;
     71 
     72 public:
     73   static char ID;
     74 
     75   TypeBasedAAWrapperPass();
     76 
     77   TypeBasedAAResult &getResult() { return *Result; }
     78   const TypeBasedAAResult &getResult() const { return *Result; }
     79 
     80   bool doInitialization(Module &M) override;
     81   bool doFinalization(Module &M) override;
     82   void getAnalysisUsage(AnalysisUsage &AU) const override;
     83 };
     84 
     85 //===--------------------------------------------------------------------===//
     86 //
     87 // createTypeBasedAAWrapperPass - This pass implements metadata-based
     88 // type-based alias analysis.
     89 //
     90 ImmutablePass *createTypeBasedAAWrapperPass();
     91 }
     92 
     93 #endif
     94