1 //===- DependencyAnalysis.h - ObjC ARC Optimization ---*- C++ -*-----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
11 /// This file declares special dependency analysis routines used in Objective C
12 /// ARC Optimizations.
14 /// WARNING: This file knows about certain library functions. It recognizes them
15 /// by name, and hardwires knowledge of their semantics.
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.
21 //===----------------------------------------------------------------------===//
23 #ifndef LLVM_LIB_TRANSFORMS_OBJCARC_DEPENDENCYANALYSIS_H
24 #define LLVM_LIB_TRANSFORMS_OBJCARC_DEPENDENCYANALYSIS_H
26 #include "llvm/ADT/SmallPtrSet.h"
27 #include "llvm/Analysis/ObjCARCInstKind.h"
38 class ProvenanceAnalysis;
40 /// \enum DependenceKind
41 /// Defines different dependence kinds among various ARC constructs.
43 /// There are several kinds of dependence-like concepts in use here.
46 NeedsPositiveRetainCount,
47 AutoreleasePoolBoundary,
49 RetainAutoreleaseDep, ///< Blocks objc_retainAutorelease.
50 RetainAutoreleaseRVDep, ///< Blocks objc_retainAutoreleaseReturnValue.
51 RetainRVDep ///< Blocks objc_retainAutoreleasedReturnValue.
54 void FindDependencies(DependenceKind Flavor,
56 BasicBlock *StartBB, Instruction *StartInst,
57 SmallPtrSetImpl<Instruction *> &DependingInstructions,
58 SmallPtrSetImpl<const BasicBlock *> &Visited,
59 ProvenanceAnalysis &PA);
62 Depends(DependenceKind Flavor, Instruction *Inst, const Value *Arg,
63 ProvenanceAnalysis &PA);
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,
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);
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);
80 static inline bool CanDecrementRefCount(const Instruction *Inst,
82 ProvenanceAnalysis &PA) {
83 return CanDecrementRefCount(Inst, Ptr, PA, GetARCInstKind(Inst));
86 } // namespace objcarc