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
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 SmallPtrSetImpl<Instruction *> &DependingInstructions,
57 SmallPtrSetImpl<const BasicBlock *> &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 CanUse(const Instruction *Inst, const Value *Ptr, ProvenanceAnalysis &PA,
67 ARCInstKind Class);
68
69 /// Test whether the given instruction can result in a reference count
70 /// modification (positive or negative) for the pointer's object.
71 bool CanAlterRefCount(const Instruction *Inst, const Value *Ptr,
72 ProvenanceAnalysis &PA, ARCInstKind Class);
73
74 /// Returns true if we can not conservatively prove that Inst can not decrement
75 /// the reference count of Ptr. Returns false if we can.
76 bool CanDecrementRefCount(const Instruction *Inst, const Value *Ptr,
77 ProvenanceAnalysis &PA, ARCInstKind Class);
78
CanDecrementRefCount(const Instruction * Inst,const Value * Ptr,ProvenanceAnalysis & PA)79 static inline bool CanDecrementRefCount(const Instruction *Inst,
80 const Value *Ptr,
81 ProvenanceAnalysis &PA) {
82 return CanDecrementRefCount(Inst, Ptr, PA, GetARCInstKind(Inst));
83 }
84
85 } // namespace objcarc
86 } // namespace llvm
87
88 #endif
89