1 //===- ObjCARCAliasAnalysis.h - ObjC ARC Optimization -*- C++ -*-----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 /// This file declares a simple ARC-aware AliasAnalysis using special knowledge
11 /// of Objective C to enhance other optimization passes which rely on the Alias
12 /// Analysis infrastructure.
14 /// WARNING: This file knows about certain library functions. It recognizes them
15 /// by name, and hardwires knowledge of their semantics.
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.
21 //===----------------------------------------------------------------------===//
23 #ifndef LLVM_LIB_TRANSFORMS_OBJCARC_OBJCARCALIASANALYSIS_H
24 #define LLVM_LIB_TRANSFORMS_OBJCARC_OBJCARCALIASANALYSIS_H
26 #include "llvm/Analysis/AliasAnalysis.h"
27 #include "llvm/Pass.h"
32 /// \brief This is a simple alias analysis implementation that uses knowledge
33 /// of ARC constructs to answer queries.
35 /// TODO: This class could be generalized to know about other ObjC-specific
36 /// tricks. Such as knowing that ivars in the non-fragile ABI are non-aliasing
37 /// even though their offsets are dynamic.
38 class ObjCARCAliasAnalysis : public ImmutablePass,
39 public AliasAnalysis {
41 static char ID; // Class identification, replacement for typeinfo
42 ObjCARCAliasAnalysis() : ImmutablePass(ID) {
43 initializeObjCARCAliasAnalysisPass(*PassRegistry::getPassRegistry());
47 void initializePass() override {
48 InitializeAliasAnalysis(this);
51 /// This method is used when a pass implements an analysis interface through
52 /// multiple inheritance. If needed, it should override this to adjust the
53 /// this pointer as needed for the specified pass info.
54 void *getAdjustedAnalysisPointer(const void *PI) override {
55 if (PI == &AliasAnalysis::ID)
56 return static_cast<AliasAnalysis *>(this);
60 void getAnalysisUsage(AnalysisUsage &AU) const override;
61 AliasResult alias(const Location &LocA, const Location &LocB) override;
62 bool pointsToConstantMemory(const Location &Loc, bool OrLocal) override;
63 ModRefBehavior getModRefBehavior(ImmutableCallSite CS) override;
64 ModRefBehavior getModRefBehavior(const Function *F) override;
65 ModRefResult getModRefInfo(ImmutableCallSite CS,
66 const Location &Loc) override;
67 ModRefResult getModRefInfo(ImmutableCallSite CS1,
68 ImmutableCallSite CS2) override;
71 } // namespace objcarc