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
28namespace llvm {
29  class BasicBlock;
30  class Instruction;
31  class Value;
32}
33
34namespace llvm {
35namespace objcarc {
36
37class 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///
44enum DependenceKind {
45  NeedsPositiveRetainCount,
46  AutoreleasePoolBoundary,
47  CanChangeRetainCount,
48  RetainAutoreleaseDep,       ///< Blocks objc_retainAutorelease.
49  RetainAutoreleaseRVDep,     ///< Blocks objc_retainAutoreleaseReturnValue.
50  RetainRVDep                 ///< Blocks objc_retainAutoreleasedReturnValue.
51};
52
53void 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
60bool
61Depends(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.
66bool
67CanUse(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.
72bool
73CanAlterRefCount(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