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
CanDecrementRefCount(const Instruction * Inst,const Value * Ptr,ProvenanceAnalysis & PA)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