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      1 //===- DependencyAnalysis.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 ///
     11 /// This file declares special dependency analysis routines used in Objective C
     12 /// ARC Optimizations.
     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_TRANSFORMS_OBJCARC_DEPEDENCYANALYSIS_H
     24 #define LLVM_TRANSFORMS_OBJCARC_DEPEDENCYANALYSIS_H
     25 
     26 #include "llvm/ADT/SmallPtrSet.h"
     27 
     28 namespace llvm {
     29   class BasicBlock;
     30   class Instruction;
     31   class Value;
     32 }
     33 
     34 namespace llvm {
     35 namespace objcarc {
     36 
     37 class ProvenanceAnalysis;
     38 
     39 /// \enum DependenceKind
     40 /// \brief Defines different dependence kinds among various ARC constructs.
     41 ///
     42 /// There are several kinds of dependence-like concepts in use here.
     43 ///
     44 enum DependenceKind {
     45   NeedsPositiveRetainCount,
     46   AutoreleasePoolBoundary,
     47   CanChangeRetainCount,
     48   RetainAutoreleaseDep,       ///< Blocks objc_retainAutorelease.
     49   RetainAutoreleaseRVDep,     ///< Blocks objc_retainAutoreleaseReturnValue.
     50   RetainRVDep                 ///< Blocks objc_retainAutoreleasedReturnValue.
     51 };
     52 
     53 void FindDependencies(DependenceKind Flavor,
     54                       const Value *Arg,
     55                       BasicBlock *StartBB, Instruction *StartInst,
     56                       SmallPtrSet<Instruction *, 4> &DependingInstructions,
     57                       SmallPtrSet<const BasicBlock *, 4> &Visited,
     58                       ProvenanceAnalysis &PA);
     59 
     60 bool
     61 Depends(DependenceKind Flavor, Instruction *Inst, const Value *Arg,
     62         ProvenanceAnalysis &PA);
     63 
     64 /// Test whether the given instruction can "use" the given pointer's object in a
     65 /// way that requires the reference count to be positive.
     66 bool
     67 CanUse(const Instruction *Inst, const Value *Ptr, ProvenanceAnalysis &PA,
     68        InstructionClass Class);
     69 
     70 /// Test whether the given instruction can result in a reference count
     71 /// modification (positive or negative) for the pointer's object.
     72 bool
     73 CanAlterRefCount(const Instruction *Inst, const Value *Ptr,
     74                  ProvenanceAnalysis &PA, InstructionClass Class);
     75 
     76 } // namespace objcarc
     77 } // namespace llvm
     78 
     79 #endif // LLVM_TRANSFORMS_OBJCARC_DEPEDENCYANALYSIS_H
     80