89 lines
3.3 KiB
C++
89 lines
3.3 KiB
C++
//===- DependencyAnalysis.h - ObjC ARC Optimization ---*- C++ -*-----------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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/// \file
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///
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/// This file declares special dependency analysis routines used in Objective C
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/// ARC Optimizations.
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///
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/// WARNING: This file knows about certain library functions. It recognizes them
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/// by name, and hardwires knowledge of their semantics.
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///
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/// WARNING: This file knows about how certain Objective-C library functions are
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/// used. Naive LLVM IR transformations which would otherwise be
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/// behavior-preserving may break these assumptions.
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///
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIB_TRANSFORMS_OBJCARC_DEPENDENCYANALYSIS_H
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#define LLVM_LIB_TRANSFORMS_OBJCARC_DEPENDENCYANALYSIS_H
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/Analysis/ObjCARCInstKind.h"
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namespace llvm {
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class BasicBlock;
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class Instruction;
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class Value;
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}
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namespace llvm {
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namespace objcarc {
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class ProvenanceAnalysis;
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/// \enum DependenceKind
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/// Defines different dependence kinds among various ARC constructs.
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///
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/// There are several kinds of dependence-like concepts in use here.
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///
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enum DependenceKind {
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NeedsPositiveRetainCount,
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AutoreleasePoolBoundary,
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CanChangeRetainCount,
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RetainAutoreleaseDep, ///< Blocks objc_retainAutorelease.
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RetainAutoreleaseRVDep, ///< Blocks objc_retainAutoreleaseReturnValue.
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RetainRVDep ///< Blocks objc_retainAutoreleasedReturnValue.
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};
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/// Find dependent instructions. If there is exactly one dependent instruction,
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/// return it. Otherwise, return null.
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llvm::Instruction *findSingleDependency(DependenceKind Flavor, const Value *Arg,
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BasicBlock *StartBB,
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Instruction *StartInst,
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ProvenanceAnalysis &PA);
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bool
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Depends(DependenceKind Flavor, Instruction *Inst, const Value *Arg,
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ProvenanceAnalysis &PA);
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/// Test whether the given instruction can "use" the given pointer's object in a
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/// way that requires the reference count to be positive.
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bool CanUse(const Instruction *Inst, const Value *Ptr, ProvenanceAnalysis &PA,
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ARCInstKind Class);
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/// Test whether the given instruction can result in a reference count
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/// modification (positive or negative) for the pointer's object.
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bool CanAlterRefCount(const Instruction *Inst, const Value *Ptr,
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ProvenanceAnalysis &PA, ARCInstKind Class);
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/// Returns true if we can not conservatively prove that Inst can not decrement
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/// the reference count of Ptr. Returns false if we can.
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bool CanDecrementRefCount(const Instruction *Inst, const Value *Ptr,
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ProvenanceAnalysis &PA, ARCInstKind Class);
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static inline bool CanDecrementRefCount(const Instruction *Inst,
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const Value *Ptr,
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ProvenanceAnalysis &PA) {
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return CanDecrementRefCount(Inst, Ptr, PA, GetARCInstKind(Inst));
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}
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} // namespace objcarc
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} // namespace llvm
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#endif
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