1 //===- GlobalsModRef.h - Simple Mod/Ref AA for Globals ----------*- 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 /// This is the interface for a simple mod/ref and alias analysis over globals. 10 /// 11 //===----------------------------------------------------------------------===// 12 13 #ifndef LLVM_ANALYSIS_GLOBALSMODREF_H 14 #define LLVM_ANALYSIS_GLOBALSMODREF_H 15 16 #include "llvm/Analysis/AliasAnalysis.h" 17 #include "llvm/Analysis/CallGraph.h" 18 #include "llvm/IR/Constants.h" 19 #include "llvm/IR/Function.h" 20 #include "llvm/IR/Module.h" 21 #include "llvm/IR/ValueHandle.h" 22 #include "llvm/Pass.h" 23 #include <list> 24 25 namespace llvm { 26 27 /// An alias analysis result set for globals. 28 /// 29 /// This focuses on handling aliasing properties of globals and interprocedural 30 /// function call mod/ref information. 31 class GlobalsAAResult : public AAResultBase<GlobalsAAResult> { 32 friend AAResultBase<GlobalsAAResult>; 33 34 class FunctionInfo; 35 36 const DataLayout &DL; 37 std::function<const TargetLibraryInfo &(Function &F)> GetTLI; 38 39 /// The globals that do not have their addresses taken. 40 SmallPtrSet<const GlobalValue *, 8> NonAddressTakenGlobals; 41 42 /// Are there functions with local linkage that may modify globals. 43 bool UnknownFunctionsWithLocalLinkage = false; 44 45 /// IndirectGlobals - The memory pointed to by this global is known to be 46 /// 'owned' by the global. 47 SmallPtrSet<const GlobalValue *, 8> IndirectGlobals; 48 49 /// AllocsForIndirectGlobals - If an instruction allocates memory for an 50 /// indirect global, this map indicates which one. 51 DenseMap<const Value *, const GlobalValue *> AllocsForIndirectGlobals; 52 53 /// For each function, keep track of what globals are modified or read. 54 DenseMap<const Function *, FunctionInfo> FunctionInfos; 55 56 /// A map of functions to SCC. The SCCs are described by a simple integer 57 /// ID that is only useful for comparing for equality (are two functions 58 /// in the same SCC or not?) 59 DenseMap<const Function *, unsigned> FunctionToSCCMap; 60 61 /// Handle to clear this analysis on deletion of values. 62 struct DeletionCallbackHandle final : CallbackVH { 63 GlobalsAAResult *GAR; 64 std::list<DeletionCallbackHandle>::iterator I; 65 66 DeletionCallbackHandle(GlobalsAAResult &GAR, Value *V) 67 : CallbackVH(V), GAR(&GAR) {} 68 69 void deleted() override; 70 }; 71 72 /// List of callbacks for globals being tracked by this analysis. Note that 73 /// these objects are quite large, but we only anticipate having one per 74 /// global tracked by this analysis. There are numerous optimizations we 75 /// could perform to the memory utilization here if this becomes a problem. 76 std::list<DeletionCallbackHandle> Handles; 77 78 explicit GlobalsAAResult( 79 const DataLayout &DL, 80 std::function<const TargetLibraryInfo &(Function &F)> GetTLI); 81 82 public: 83 GlobalsAAResult(GlobalsAAResult &&Arg); 84 ~GlobalsAAResult(); 85 86 static GlobalsAAResult 87 analyzeModule(Module &M, 88 std::function<const TargetLibraryInfo &(Function &F)> GetTLI, 89 CallGraph &CG); 90 91 //------------------------------------------------ 92 // Implement the AliasAnalysis API 93 // 94 AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB, 95 AAQueryInfo &AAQI); 96 97 using AAResultBase::getModRefInfo; 98 ModRefInfo getModRefInfo(const CallBase *Call, const MemoryLocation &Loc, 99 AAQueryInfo &AAQI); 100 101 /// getModRefBehavior - Return the behavior of the specified function if 102 /// called from the specified call site. The call site may be null in which 103 /// case the most generic behavior of this function should be returned. 104 FunctionModRefBehavior getModRefBehavior(const Function *F); 105 106 /// getModRefBehavior - Return the behavior of the specified function if 107 /// called from the specified call site. The call site may be null in which 108 /// case the most generic behavior of this function should be returned. 109 FunctionModRefBehavior getModRefBehavior(const CallBase *Call); 110 111 private: 112 FunctionInfo *getFunctionInfo(const Function *F); 113 114 void AnalyzeGlobals(Module &M); 115 void AnalyzeCallGraph(CallGraph &CG, Module &M); 116 bool AnalyzeUsesOfPointer(Value *V, 117 SmallPtrSetImpl<Function *> *Readers = nullptr, 118 SmallPtrSetImpl<Function *> *Writers = nullptr, 119 GlobalValue *OkayStoreDest = nullptr); 120 bool AnalyzeIndirectGlobalMemory(GlobalVariable *GV); 121 void CollectSCCMembership(CallGraph &CG); 122 123 bool isNonEscapingGlobalNoAlias(const GlobalValue *GV, const Value *V); 124 ModRefInfo getModRefInfoForArgument(const CallBase *Call, 125 const GlobalValue *GV, AAQueryInfo &AAQI); 126 }; 127 128 /// Analysis pass providing a never-invalidated alias analysis result. 129 class GlobalsAA : public AnalysisInfoMixin<GlobalsAA> { 130 friend AnalysisInfoMixin<GlobalsAA>; 131 static AnalysisKey Key; 132 133 public: 134 typedef GlobalsAAResult Result; 135 136 GlobalsAAResult run(Module &M, ModuleAnalysisManager &AM); 137 }; 138 139 /// Legacy wrapper pass to provide the GlobalsAAResult object. 140 class GlobalsAAWrapperPass : public ModulePass { 141 std::unique_ptr<GlobalsAAResult> Result; 142 143 public: 144 static char ID; 145 146 GlobalsAAWrapperPass(); 147 148 GlobalsAAResult &getResult() { return *Result; } 149 const GlobalsAAResult &getResult() const { return *Result; } 150 151 bool runOnModule(Module &M) override; 152 bool doFinalization(Module &M) override; 153 void getAnalysisUsage(AnalysisUsage &AU) const override; 154 }; 155 156 //===--------------------------------------------------------------------===// 157 // 158 // createGlobalsAAWrapperPass - This pass provides alias and mod/ref info for 159 // global values that do not have their addresses taken. 160 // 161 ModulePass *createGlobalsAAWrapperPass(); 162 } 163 164 #endif 165