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_LIB_TRANSFORMS_OBJCARC_DEPENDENCYANALYSIS_H 24 #define LLVM_LIB_TRANSFORMS_OBJCARC_DEPENDENCYANALYSIS_H 25 26 #include "llvm/ADT/SmallPtrSet.h" 27 #include "llvm/Analysis/ObjCARCInstKind.h" 28 29 namespace llvm { 30 class BasicBlock; 31 class Instruction; 32 class Value; 33 } 34 35 namespace llvm { 36 namespace objcarc { 37 38 class ProvenanceAnalysis; 39 40 /// \enum DependenceKind 41 /// \brief Defines different dependence kinds among various ARC constructs. 42 /// 43 /// There are several kinds of dependence-like concepts in use here. 44 /// 45 enum DependenceKind { 46 NeedsPositiveRetainCount, 47 AutoreleasePoolBoundary, 48 CanChangeRetainCount, 49 RetainAutoreleaseDep, ///< Blocks objc_retainAutorelease. 50 RetainAutoreleaseRVDep, ///< Blocks objc_retainAutoreleaseReturnValue. 51 RetainRVDep ///< Blocks objc_retainAutoreleasedReturnValue. 52 }; 53 54 void FindDependencies(DependenceKind Flavor, 55 const Value *Arg, 56 BasicBlock *StartBB, Instruction *StartInst, 57 SmallPtrSetImpl<Instruction *> &DependingInstructions, 58 SmallPtrSetImpl<const BasicBlock *> &Visited, 59 ProvenanceAnalysis &PA); 60 61 bool 62 Depends(DependenceKind Flavor, Instruction *Inst, const Value *Arg, 63 ProvenanceAnalysis &PA); 64 65 /// Test whether the given instruction can "use" the given pointer's object in a 66 /// way that requires the reference count to be positive. 67 bool CanUse(const Instruction *Inst, const Value *Ptr, ProvenanceAnalysis &PA, 68 ARCInstKind 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 CanAlterRefCount(const Instruction *Inst, const Value *Ptr, 73 ProvenanceAnalysis &PA, ARCInstKind Class); 74 75 /// Returns true if we can not conservatively prove that Inst can not decrement 76 /// the reference count of Ptr. Returns false if we can. 77 bool CanDecrementRefCount(const Instruction *Inst, const Value *Ptr, 78 ProvenanceAnalysis &PA, ARCInstKind Class); 79 80 static inline bool CanDecrementRefCount(const Instruction *Inst, 81 const Value *Ptr, 82 ProvenanceAnalysis &PA) { 83 return CanDecrementRefCount(Inst, Ptr, PA, GetARCInstKind(Inst)); 84 } 85 86 } // namespace objcarc 87 } // namespace llvm 88 89 #endif 90
