lib/Transforms/ObjCARC/DependencyAnalysis.h

   1 //===- DependencyAnalysis.h - ObjC ARC Optimization ---*- C++ -*-----------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 /// \file
   9 ///
  10 /// This file declares special dependency analysis routines used in Objective C
  11 /// ARC Optimizations.
  12 ///
  13 /// WARNING: This file knows about certain library functions. It recognizes them
  14 /// by name, and hardwires knowledge of their semantics.
  15 ///
  16 /// WARNING: This file knows about how certain Objective-C library functions are
  17 /// used. Naive LLVM IR transformations which would otherwise be
  18 /// behavior-preserving may break these assumptions.
  19 ///
  20 //===----------------------------------------------------------------------===//
  21
  22 #ifndef LLVM_LIB_TRANSFORMS_OBJCARC_DEPENDENCYANALYSIS_H
  23 #define LLVM_LIB_TRANSFORMS_OBJCARC_DEPENDENCYANALYSIS_H
  24
  25 #include "llvm/ADT/SmallPtrSet.h"
  26 #include "llvm/Analysis/ObjCARCInstKind.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 /// 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
  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