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/IR/PassManager.h" 18 #include "llvm/IR/ValueHandle.h" 19 #include "llvm/Pass.h" 20 #include "llvm/Support/Compiler.h" 21 #include <list> 22 23 namespace llvm { 24 class CallGraph; 25 class Function; 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 { 32 class FunctionInfo; 33 34 const DataLayout &DL; 35 std::function<const TargetLibraryInfo &(Function &F)> GetTLI; 36 37 /// The globals that do not have their addresses taken. 38 SmallPtrSet<const GlobalValue *, 8> NonAddressTakenGlobals; 39 40 /// Are there functions with local linkage that may modify globals. 41 bool UnknownFunctionsWithLocalLinkage = false; 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 LLVM_ABI DeletionCallbackHandle final : CallbackVH { 61 GlobalsAAResult *GAR; 62 std::list<DeletionCallbackHandle>::iterator I; 63 DeletionCallbackHandlefinal64 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( 77 const DataLayout &DL, 78 std::function<const TargetLibraryInfo &(Function &F)> GetTLI); 79 80 friend struct RecomputeGlobalsAAPass; 81 82 public: 83 LLVM_ABI GlobalsAAResult(GlobalsAAResult &&Arg); 84 LLVM_ABI ~GlobalsAAResult(); 85 86 LLVM_ABI bool invalidate(Module &M, const PreservedAnalyses &PA, 87 ModuleAnalysisManager::Invalidator &); 88 89 LLVM_ABI static GlobalsAAResult 90 analyzeModule(Module &M, 91 std::function<const TargetLibraryInfo &(Function &F)> GetTLI, 92 CallGraph &CG); 93 94 //------------------------------------------------ 95 // Implement the AliasAnalysis API 96 // 97 LLVM_ABI AliasResult alias(const MemoryLocation &LocA, 98 const MemoryLocation &LocB, AAQueryInfo &AAQI, 99 const Instruction *CtxI); 100 101 using AAResultBase::getModRefInfo; 102 LLVM_ABI ModRefInfo getModRefInfo(const CallBase *Call, 103 const MemoryLocation &Loc, 104 AAQueryInfo &AAQI); 105 106 using AAResultBase::getMemoryEffects; 107 /// getMemoryEffects - Return the behavior of the specified function if 108 /// called from the specified call site. The call site may be null in which 109 /// case the most generic behavior of this function should be returned. 110 LLVM_ABI MemoryEffects getMemoryEffects(const Function *F); 111 112 private: 113 FunctionInfo *getFunctionInfo(const Function *F); 114 115 void AnalyzeGlobals(Module &M); 116 void AnalyzeCallGraph(CallGraph &CG, Module &M); 117 bool AnalyzeUsesOfPointer(Value *V, 118 SmallPtrSetImpl<Function *> *Readers = nullptr, 119 SmallPtrSetImpl<Function *> *Writers = nullptr, 120 GlobalValue *OkayStoreDest = nullptr); 121 bool AnalyzeIndirectGlobalMemory(GlobalVariable *GV); 122 void CollectSCCMembership(CallGraph &CG); 123 124 bool isNonEscapingGlobalNoAlias(const GlobalValue *GV, const Value *V, 125 const Instruction *CtxI); 126 ModRefInfo getModRefInfoForArgument(const CallBase *Call, 127 const GlobalValue *GV, AAQueryInfo &AAQI); 128 }; 129 130 /// Analysis pass providing a never-invalidated alias analysis result. 131 class GlobalsAA : public AnalysisInfoMixin<GlobalsAA> { 132 friend AnalysisInfoMixin<GlobalsAA>; 133 LLVM_ABI static AnalysisKey Key; 134 135 public: 136 typedef GlobalsAAResult Result; 137 138 LLVM_ABI GlobalsAAResult run(Module &M, ModuleAnalysisManager &AM); 139 }; 140 141 struct RecomputeGlobalsAAPass : PassInfoMixin<RecomputeGlobalsAAPass> { 142 LLVM_ABI PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM); 143 }; 144 145 /// Legacy wrapper pass to provide the GlobalsAAResult object. 146 class LLVM_ABI GlobalsAAWrapperPass : public ModulePass { 147 std::unique_ptr<GlobalsAAResult> Result; 148 149 public: 150 static char ID; 151 152 GlobalsAAWrapperPass(); 153 getResult()154 GlobalsAAResult &getResult() { return *Result; } getResult()155 const GlobalsAAResult &getResult() const { return *Result; } 156 157 bool runOnModule(Module &M) override; 158 bool doFinalization(Module &M) override; 159 void getAnalysisUsage(AnalysisUsage &AU) const override; 160 }; 161 162 //===--------------------------------------------------------------------===// 163 // 164 // createGlobalsAAWrapperPass - This pass provides alias and mod/ref info for 165 // global values that do not have their addresses taken. 166 // 167 LLVM_ABI ModulePass *createGlobalsAAWrapperPass(); 168 } 169 170 #endif 171