src/llvm/lib/Transforms/ObjCARC/ObjCARCAliasAnalysis.h

   1 //===- ObjCARCAliasAnalysis.h - ObjC ARC Optimization -*- 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 file declares a simple ARC-aware AliasAnalysis using special knowledge
  11 /// of Objective C to enhance other optimization passes which rely on the Alias
  12 /// Analysis infrastructure.
  13 ///
  14 /// WARNING: This file knows about certain library functions. It recognizes them
  15 /// by name, and hardwires knowledge of their semantics.
  16 ///
  17 /// WARNING: This file knows about how certain Objective-C library functions are
  18 /// used. Naive LLVM IR transformations which would otherwise be
  19 /// behavior-preserving may break these assumptions.
  20 ///
  21 //===----------------------------------------------------------------------===//
  22
  23 #ifndef LLVM_LIB_TRANSFORMS_OBJCARC_OBJCARCALIASANALYSIS_H
  24 #define LLVM_LIB_TRANSFORMS_OBJCARC_OBJCARCALIASANALYSIS_H
  25
  26 #include "llvm/Analysis/AliasAnalysis.h"
  27 #include "llvm/Pass.h"
  28
  29 namespace llvm {
  30 namespace objcarc {
  31
  32   /// \brief This is a simple alias analysis implementation that uses knowledge
  33   /// of ARC constructs to answer queries.
  34   ///
  35   /// TODO: This class could be generalized to know about other ObjC-specific
  36   /// tricks. Such as knowing that ivars in the non-fragile ABI are non-aliasing
  37   /// even though their offsets are dynamic.
  38   class ObjCARCAliasAnalysis : public ImmutablePass,
  39                                public AliasAnalysis {
  40   public:
  41     static char ID; // Class identification, replacement for typeinfo
  42     ObjCARCAliasAnalysis() : ImmutablePass(ID) {
  43       initializeObjCARCAliasAnalysisPass(*PassRegistry::getPassRegistry());
  44     }
  45
  46   private:
  47     void initializePass() override {
  48       InitializeAliasAnalysis(this);
  49     }
  50
  51     /// This method is used when a pass implements an analysis interface through
  52     /// multiple inheritance.  If needed, it should override this to adjust the
  53     /// this pointer as needed for the specified pass info.
  54     void *getAdjustedAnalysisPointer(const void *PI) override {
  55       if (PI == &AliasAnalysis::ID)
  56         return static_cast<AliasAnalysis *>(this);
  57       return this;
  58     }
  59
  60     void getAnalysisUsage(AnalysisUsage &AU) const override;
  61     AliasResult alias(const Location &LocA, const Location &LocB) override;
  62     bool pointsToConstantMemory(const Location &Loc, bool OrLocal) override;
  63     ModRefBehavior getModRefBehavior(ImmutableCallSite CS) override;
  64     ModRefBehavior getModRefBehavior(const Function *F) override;
  65     ModRefResult getModRefInfo(ImmutableCallSite CS,
  66                                const Location &Loc) override;
  67     ModRefResult getModRefInfo(ImmutableCallSite CS1,
  68                                ImmutableCallSite CS2) override;
  69   };
  70
  71 } // namespace objcarc
  72 } // namespace llvm
  73
  74 #endif