1 //===- GlobalsModRef.h - Simple Mod/Ref AA for Globals ----------*- 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 /// This is the interface for a simple mod/ref and alias analysis over globals. 11 /// 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_ANALYSIS_GLOBALSMODREF_H 15 #define LLVM_ANALYSIS_GLOBALSMODREF_H 16 17 #include "llvm/Analysis/AliasAnalysis.h" 18 #include "llvm/Analysis/CallGraph.h" 19 #include "llvm/IR/Constants.h" 20 #include "llvm/IR/Function.h" 21 #include "llvm/IR/Module.h" 22 #include "llvm/IR/ValueHandle.h" 23 #include "llvm/Pass.h" 24 #include <list> 25 26 namespace llvm { 27 28 /// An alias analysis result set for globals. 29 /// 30 /// This focuses on handling aliasing properties of globals and interprocedural 31 /// function call mod/ref information. 32 class GlobalsAAResult : public AAResultBase<GlobalsAAResult> { 33 friend AAResultBase<GlobalsAAResult>; 34 35 class FunctionInfo; 36 37 const DataLayout &DL; 38 const TargetLibraryInfo &TLI; 39 40 /// The globals that do not have their addresses taken. 41 SmallPtrSet<const GlobalValue *, 8> NonAddressTakenGlobals; 42 43 /// IndirectGlobals - The memory pointed to by this global is known to be 44 /// 'owned' by the global. 45 SmallPtrSet<const GlobalValue *, 8> IndirectGlobals; 46 47 /// AllocsForIndirectGlobals - If an instruction allocates memory for an 48 /// indirect global, this map indicates which one. 49 DenseMap<const Value *, const GlobalValue *> AllocsForIndirectGlobals; 50 51 /// For each function, keep track of what globals are modified or read. 52 DenseMap<const Function *, FunctionInfo> FunctionInfos; 53 54 /// A map of functions to SCC. The SCCs are described by a simple integer 55 /// ID that is only useful for comparing for equality (are two functions 56 /// in the same SCC or not?) 57 DenseMap<const Function *, unsigned> FunctionToSCCMap; 58 59 /// Handle to clear this analysis on deletion of values. 60 struct DeletionCallbackHandle final : CallbackVH { 61 GlobalsAAResult *GAR; 62 std::list<DeletionCallbackHandle>::iterator I; 63 64 DeletionCallbackHandle(GlobalsAAResult &GAR, Value *V) 65 : CallbackVH(V), GAR(&GAR) {} 66 67 void deleted() override; 68 }; 69 70 /// List of callbacks for globals being tracked by this analysis. Note that 71 /// these objects are quite large, but we only anticipate having one per 72 /// global tracked by this analysis. There are numerous optimizations we 73 /// could perform to the memory utilization here if this becomes a problem. 74 std::list<DeletionCallbackHandle> Handles; 75 76 explicit GlobalsAAResult(const DataLayout &DL, const TargetLibraryInfo &TLI); 77 78 public: 79 GlobalsAAResult(GlobalsAAResult &&Arg); 80 ~GlobalsAAResult(); 81 82 static GlobalsAAResult analyzeModule(Module &M, const TargetLibraryInfo &TLI, 83 CallGraph &CG); 84 85 //------------------------------------------------ 86 // Implement the AliasAnalysis API 87 // 88 AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB); 89 90 using AAResultBase::getModRefInfo; 91 ModRefInfo getModRefInfo(ImmutableCallSite CS, const MemoryLocation &Loc); 92 93 /// getModRefBehavior - Return the behavior of the specified function if 94 /// called from the specified call site. The call site may be null in which 95 /// case the most generic behavior of this function should be returned. 96 FunctionModRefBehavior getModRefBehavior(const Function *F); 97 98 /// getModRefBehavior - Return the behavior of the specified function if 99 /// called from the specified call site. The call site may be null in which 100 /// case the most generic behavior of this function should be returned. 101 FunctionModRefBehavior getModRefBehavior(ImmutableCallSite CS); 102 103 private: 104 FunctionInfo *getFunctionInfo(const Function *F); 105 106 void AnalyzeGlobals(Module &M); 107 void AnalyzeCallGraph(CallGraph &CG, Module &M); 108 bool AnalyzeUsesOfPointer(Value *V, 109 SmallPtrSetImpl<Function *> *Readers = nullptr, 110 SmallPtrSetImpl<Function *> *Writers = nullptr, 111 GlobalValue *OkayStoreDest = nullptr); 112 bool AnalyzeIndirectGlobalMemory(GlobalVariable *GV); 113 void CollectSCCMembership(CallGraph &CG); 114 115 bool isNonEscapingGlobalNoAlias(const GlobalValue *GV, const Value *V); 116 ModRefInfo getModRefInfoForArgument(ImmutableCallSite CS, 117 const GlobalValue *GV); 118 }; 119 120 /// Analysis pass providing a never-invalidated alias analysis result. 121 class GlobalsAA : public AnalysisInfoMixin<GlobalsAA> { 122 friend AnalysisInfoMixin<GlobalsAA>; 123 static AnalysisKey Key; 124 125 public: 126 typedef GlobalsAAResult Result; 127 128 GlobalsAAResult run(Module &M, ModuleAnalysisManager &AM); 129 }; 130 131 /// Legacy wrapper pass to provide the GlobalsAAResult object. 132 class GlobalsAAWrapperPass : public ModulePass { 133 std::unique_ptr<GlobalsAAResult> Result; 134 135 public: 136 static char ID; 137 138 GlobalsAAWrapperPass(); 139 140 GlobalsAAResult &getResult() { return *Result; } 141 const GlobalsAAResult &getResult() const { return *Result; } 142 143 bool runOnModule(Module &M) override; 144 bool doFinalization(Module &M) override; 145 void getAnalysisUsage(AnalysisUsage &AU) const override; 146 }; 147 148 //===--------------------------------------------------------------------===// 149 // 150 // createGlobalsAAWrapperPass - This pass provides alias and mod/ref info for 151 // global values that do not have their addresses taken. 152 // 153 ModulePass *createGlobalsAAWrapperPass(); 154 } 155 156 #endif 157
