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//===- ObjCARCAliasAnalysis.h - ObjC ARC Alias Analysis ---------*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
/// \file
/// This file declares a simple ARC-aware AliasAnalysis using special knowledge
/// of Objective C to enhance other optimization passes which rely on the Alias
/// Analysis infrastructure.
/// WARNING: This file knows about certain library functions. It recognizes them
/// by name, and hardwires knowledge of their semantics.
/// WARNING: This file knows about how certain Objective-C library functions are
/// used. Naive LLVM IR transformations which would otherwise be
/// behavior-preserving may break these assumptions.
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Pass.h"
namespace llvm {
namespace objcarc {
/// This is a simple alias analysis implementation that uses knowledge
/// of ARC constructs to answer queries.
/// TODO: This class could be generalized to know about other ObjC-specific
/// tricks. Such as knowing that ivars in the non-fragile ABI are non-aliasing
/// even though their offsets are dynamic.
class ObjCARCAAResult : public AAResultBase<ObjCARCAAResult> {
friend AAResultBase<ObjCARCAAResult>;
const DataLayout &DL;
explicit ObjCARCAAResult(const DataLayout &DL) : AAResultBase(), DL(DL) {}
ObjCARCAAResult(ObjCARCAAResult &&Arg)
: AAResultBase(std::move(Arg)), DL(Arg.DL) {}
/// Handle invalidation events from the new pass manager.
/// By definition, this result is stateless and so remains valid.
bool invalidate(Function &, const PreservedAnalyses &,
FunctionAnalysisManager::Invalidator &) {
return false;
AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB);
bool pointsToConstantMemory(const MemoryLocation &Loc, bool OrLocal);
using AAResultBase::getModRefBehavior;
FunctionModRefBehavior getModRefBehavior(const Function *F);
using AAResultBase::getModRefInfo;
ModRefInfo getModRefInfo(const CallBase *Call, const MemoryLocation &Loc);
/// Analysis pass providing a never-invalidated alias analysis result.
class ObjCARCAA : public AnalysisInfoMixin<ObjCARCAA> {
friend AnalysisInfoMixin<ObjCARCAA>;
static AnalysisKey Key;
typedef ObjCARCAAResult Result;
ObjCARCAAResult run(Function &F, FunctionAnalysisManager &AM);
/// Legacy wrapper pass to provide the ObjCARCAAResult object.
class ObjCARCAAWrapperPass : public ImmutablePass {
std::unique_ptr<ObjCARCAAResult> Result;
static char ID;
ObjCARCAAResult &getResult() { return *Result; }
const ObjCARCAAResult &getResult() const { return *Result; }
bool doInitialization(Module &M) override;
bool doFinalization(Module &M) override;
void getAnalysisUsage(AnalysisUsage &AU) const override;
} // namespace objcarc
} // namespace llvm