GlobalsModRef.cpp revision 5cbf985dcbc89fba3208e7baf8b6f488b06d3ec9
121e463b2bf864671a87ebe386cb100ef9349a540Nate Begeman//===- GlobalsModRef.cpp - Simple Mod/Ref Analysis for Globals ------------===// 2b5f662fa0314f7e7e690aae8ebff7136cc3a5ab0Misha Brukman// 3f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman// The LLVM Compiler Infrastructure 4f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman// 54ee451de366474b9c228b4e5fa573795a715216dChris Lattner// This file was developed by the LLVM research group and is distributed under 64ee451de366474b9c228b4e5fa573795a715216dChris Lattner// the University of Illinois Open Source License. See LICENSE.TXT for details. 7b5f662fa0314f7e7e690aae8ebff7136cc3a5ab0Misha Brukman// 8f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman//===----------------------------------------------------------------------===// 9f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman// 10f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman// This simple pass provides alias and mod/ref information for global values 11f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman// that do not have their address taken, and keeps track of whether functions 12f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman// read or write memory (are "pure"). For this simple (but very common) case, 13f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman// we can provide pretty accurate and useful information. 1416e71f2f70811c69c56052dd146324fe20e31db5Chris Lattner// 15df4ed6350b2a51f71c0980e86c9078f4046ea706Chris Lattner//===----------------------------------------------------------------------===// 164c7b43b43fdf943c7298718e15ab5d6dfe345be7Chris Lattner 17b1d26f66658cff3ceb7d44a72fbc8c8e975532f9Chris Lattner#define DEBUG_TYPE "globalsmodref-aa" 18718cb665ca6ce2bc4d8e8479f46a45db91b49f86Owen Anderson#include "llvm/Analysis/Passes.h" 19f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman#include "llvm/Module.h" 20f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman#include "llvm/Pass.h" 21f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman#include "llvm/Instructions.h" 22b1d26f66658cff3ceb7d44a72fbc8c8e975532f9Chris Lattner#include "llvm/Constants.h" 23718cb665ca6ce2bc4d8e8479f46a45db91b49f86Owen Anderson#include "llvm/DerivedTypes.h" 247ce45783531cfa81bfd7be561ea7e4738e8c6ca8Evan Cheng#include "llvm/Analysis/AliasAnalysis.h" 25b1d26f66658cff3ceb7d44a72fbc8c8e975532f9Chris Lattner#include "llvm/Analysis/CallGraph.h" 26b1d26f66658cff3ceb7d44a72fbc8c8e975532f9Chris Lattner#include "llvm/Support/InstIterator.h" 27b1d26f66658cff3ceb7d44a72fbc8c8e975532f9Chris Lattner#include "llvm/Support/CommandLine.h" 28b1d26f66658cff3ceb7d44a72fbc8c8e975532f9Chris Lattner#include "llvm/ADT/Statistic.h" 29b1d26f66658cff3ceb7d44a72fbc8c8e975532f9Chris Lattner#include "llvm/ADT/SCCIterator.h" 30b1d26f66658cff3ceb7d44a72fbc8c8e975532f9Chris Lattner#include <set> 31b1d26f66658cff3ceb7d44a72fbc8c8e975532f9Chris Lattnerusing namespace llvm; 32b1d26f66658cff3ceb7d44a72fbc8c8e975532f9Chris Lattner 33b1d26f66658cff3ceb7d44a72fbc8c8e975532f9Chris LattnerSTATISTIC(NumNonAddrTakenGlobalVars, 34b1d26f66658cff3ceb7d44a72fbc8c8e975532f9Chris Lattner "Number of global vars without address taken"); 35f2ccb77ee9d8ab35866dae111fa36929689c7511Misha BrukmanSTATISTIC(NumNonAddrTakenFunctions,"Number of functions without address taken"); 3621e463b2bf864671a87ebe386cb100ef9349a540Nate BegemanSTATISTIC(NumNoMemFunctions, "Number of functions that do not access memory"); 3721e463b2bf864671a87ebe386cb100ef9349a540Nate BegemanSTATISTIC(NumReadMemFunctions, "Number of functions that only read memory"); 3821e463b2bf864671a87ebe386cb100ef9349a540Nate BegemanSTATISTIC(NumIndirectGlobalVars, "Number of indirect global objects"); 39f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman 40b410dc99774d52b4491750dab10b91cca1d661d8Chris Lattnernamespace { 4114c09b81ead8fe8b754fca2d0a8237cb810b37d6Chris Lattner /// FunctionRecord - One instance of this structure is stored for every 421e341729dd003ca33ecea4abf13134f20062c5f8Evan Cheng /// function in the program. Later, the entries for these functions are 43f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman /// removed if the function is found to call an external function (in which 44f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman /// case we know nothing about it. 45f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman struct FunctionRecord { 46f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman /// GlobalInfo - Maintain mod/ref info for all of the globals without 47f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman /// addresses taken that are read or written (transitively) by this 48f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman /// function. 49f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman std::map<GlobalValue*, unsigned> GlobalInfo; 50f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman 51f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman unsigned getInfoForGlobal(GlobalValue *GV) const { 52f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman std::map<GlobalValue*, unsigned>::const_iterator I = GlobalInfo.find(GV); 531e341729dd003ca33ecea4abf13134f20062c5f8Evan Cheng if (I != GlobalInfo.end()) 54f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman return I->second; 55f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman return 0; 56f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman } 579a1ceaedc282f0cae31f2723f4d6c00c7b88fe90Chris Lattner 58f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman /// FunctionEffect - Capture whether or not this function reads or writes to 59f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman /// ANY memory. If not, we can do a lot of aggressive analysis on it. 60f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman unsigned FunctionEffect; 61f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman 62cb90de37a720b0b00d6303b49b8df6d5ac5f34f9Nate Begeman FunctionRecord() : FunctionEffect(0) {} 631e341729dd003ca33ecea4abf13134f20062c5f8Evan Cheng }; 64cb90de37a720b0b00d6303b49b8df6d5ac5f34f9Nate Begeman 65cb90de37a720b0b00d6303b49b8df6d5ac5f34f9Nate Begeman /// GlobalsModRef - The actual analysis pass. 66cb90de37a720b0b00d6303b49b8df6d5ac5f34f9Nate Begeman class GlobalsModRef : public ModulePass, public AliasAnalysis { 67cb90de37a720b0b00d6303b49b8df6d5ac5f34f9Nate Begeman /// NonAddressTakenGlobals - The globals that do not have their addresses 689a1ceaedc282f0cae31f2723f4d6c00c7b88fe90Chris Lattner /// taken. 69cb90de37a720b0b00d6303b49b8df6d5ac5f34f9Nate Begeman std::set<GlobalValue*> NonAddressTakenGlobals; 70cb90de37a720b0b00d6303b49b8df6d5ac5f34f9Nate Begeman 71cb90de37a720b0b00d6303b49b8df6d5ac5f34f9Nate Begeman /// IndirectGlobals - The memory pointed to by this global is known to be 72cb90de37a720b0b00d6303b49b8df6d5ac5f34f9Nate Begeman /// 'owned' by the global. 73eb5d47d99db0d9e4fc11f136fbacbd507c71a4c2Chris Lattner std::set<GlobalValue*> IndirectGlobals; 74eb5d47d99db0d9e4fc11f136fbacbd507c71a4c2Chris Lattner 751e341729dd003ca33ecea4abf13134f20062c5f8Evan Cheng /// AllocsForIndirectGlobals - If an instruction allocates memory for an 76f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman /// indirect global, this map indicates which one. 77f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman std::map<Value*, GlobalValue*> AllocsForIndirectGlobals; 78f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman 79f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman /// FunctionInfo - For each function, keep track of what globals are 80f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman /// modified or read. 81f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman std::map<Function*, FunctionRecord> FunctionInfo; 827af0248af47fbd86ec65d308adda22ec367accc4Nate Begeman 831e341729dd003ca33ecea4abf13134f20062c5f8Evan Cheng public: 847af0248af47fbd86ec65d308adda22ec367accc4Nate Begeman bool runOnModule(Module &M) { 857af0248af47fbd86ec65d308adda22ec367accc4Nate Begeman InitializeAliasAnalysis(this); // set up super class 867af0248af47fbd86ec65d308adda22ec367accc4Nate Begeman AnalyzeGlobals(M); // find non-addr taken globals 877af0248af47fbd86ec65d308adda22ec367accc4Nate Begeman AnalyzeCallGraph(getAnalysis<CallGraph>(), M); // Propagate on CG 887af0248af47fbd86ec65d308adda22ec367accc4Nate Begeman return false; 897af0248af47fbd86ec65d308adda22ec367accc4Nate Begeman } 90f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman 91f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman virtual void getAnalysisUsage(AnalysisUsage &AU) const { 92f2ccb77ee9d8ab35866dae111fa36929689c7511Misha Brukman AliasAnalysis::getAnalysisUsage(AU); 93043870dd85ea41e8972c304b122070a417c8a4bcChris Lattner AU.addRequired<CallGraph>(); 94408396014742a05cad1c91949d2226169e3f9d80Chris Lattner AU.setPreservesAll(); // Does not transform code 959c09c9ec9dab61450800b42cbf746164aa076b88Chris Lattner } 96408396014742a05cad1c91949d2226169e3f9d80Chris Lattner 97408396014742a05cad1c91949d2226169e3f9d80Chris Lattner //------------------------------------------------ 98408396014742a05cad1c91949d2226169e3f9d80Chris Lattner // Implement the AliasAnalysis API 99408396014742a05cad1c91949d2226169e3f9d80Chris Lattner // 100408396014742a05cad1c91949d2226169e3f9d80Chris Lattner AliasResult alias(const Value *V1, unsigned V1Size, 101408396014742a05cad1c91949d2226169e3f9d80Chris Lattner const Value *V2, unsigned V2Size); 1028aa797aa51cd4ea1ec6f46f4891a6897944b75b2Chris Lattner ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size); 1038aa797aa51cd4ea1ec6f46f4891a6897944b75b2Chris Lattner ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) { 1048aa797aa51cd4ea1ec6f46f4891a6897944b75b2Chris Lattner return AliasAnalysis::getModRefInfo(CS1,CS2); 105408396014742a05cad1c91949d2226169e3f9d80Chris Lattner } 106408396014742a05cad1c91949d2226169e3f9d80Chris Lattner bool hasNoModRefInfoForCalls() const { return false; } 107408396014742a05cad1c91949d2226169e3f9d80Chris Lattner 108408396014742a05cad1c91949d2226169e3f9d80Chris Lattner /// getModRefBehavior - Return the behavior of the specified function if 109408396014742a05cad1c91949d2226169e3f9d80Chris Lattner /// called from the specified call site. The call site may be null in which 1106524287c53cf727a8ef33517403fcb1bbd7adff9Chris Lattner /// case the most generic behavior of this function should be returned. 111408396014742a05cad1c91949d2226169e3f9d80Chris Lattner virtual ModRefBehavior getModRefBehavior(Function *F, CallSite CS, 1126524287c53cf727a8ef33517403fcb1bbd7adff9Chris Lattner std::vector<PointerAccessInfo> *Info) { 1136524287c53cf727a8ef33517403fcb1bbd7adff9Chris Lattner if (FunctionRecord *FR = getFunctionInfo(F)) 1146524287c53cf727a8ef33517403fcb1bbd7adff9Chris Lattner if (FR->FunctionEffect == 0) 1156524287c53cf727a8ef33517403fcb1bbd7adff9Chris Lattner return DoesNotAccessMemory; 1163b478b31e297208ef2c9f74750a8a603eb3726fbNate Begeman else if ((FR->FunctionEffect & Mod) == 0) 1176524287c53cf727a8ef33517403fcb1bbd7adff9Chris Lattner return OnlyReadsMemory; 1186524287c53cf727a8ef33517403fcb1bbd7adff9Chris Lattner return AliasAnalysis::getModRefBehavior(F, CS, Info); 1196524287c53cf727a8ef33517403fcb1bbd7adff9Chris Lattner } 1208aa797aa51cd4ea1ec6f46f4891a6897944b75b2Chris Lattner 1218aa797aa51cd4ea1ec6f46f4891a6897944b75b2Chris Lattner virtual void deleteValue(Value *V); 1228aa797aa51cd4ea1ec6f46f4891a6897944b75b2Chris Lattner virtual void copyValue(Value *From, Value *To); 1236524287c53cf727a8ef33517403fcb1bbd7adff9Chris Lattner 1246524287c53cf727a8ef33517403fcb1bbd7adff9Chris Lattner private: 1256524287c53cf727a8ef33517403fcb1bbd7adff9Chris Lattner /// getFunctionInfo - Return the function info for the function, or null if 1266524287c53cf727a8ef33517403fcb1bbd7adff9Chris Lattner /// the function calls an external function (in which case we don't have 1276524287c53cf727a8ef33517403fcb1bbd7adff9Chris Lattner /// anything useful to say about it). 1286524287c53cf727a8ef33517403fcb1bbd7adff9Chris Lattner FunctionRecord *getFunctionInfo(Function *F) { 129408396014742a05cad1c91949d2226169e3f9d80Chris Lattner std::map<Function*, FunctionRecord>::iterator I = FunctionInfo.find(F); 130043870dd85ea41e8972c304b122070a417c8a4bcChris Lattner if (I != FunctionInfo.end()) 131043870dd85ea41e8972c304b122070a417c8a4bcChris Lattner return &I->second; 13221e463b2bf864671a87ebe386cb100ef9349a540Nate Begeman return 0; 133043870dd85ea41e8972c304b122070a417c8a4bcChris Lattner } 134043870dd85ea41e8972c304b122070a417c8a4bcChris Lattner 135043870dd85ea41e8972c304b122070a417c8a4bcChris Lattner void AnalyzeGlobals(Module &M); 136043870dd85ea41e8972c304b122070a417c8a4bcChris Lattner void AnalyzeCallGraph(CallGraph &CG, Module &M); 137043870dd85ea41e8972c304b122070a417c8a4bcChris Lattner void AnalyzeSCC(std::vector<CallGraphNode *> &SCC); 1389a1ceaedc282f0cae31f2723f4d6c00c7b88fe90Chris Lattner bool AnalyzeUsesOfPointer(Value *V, std::vector<Function*> &Readers, 139043870dd85ea41e8972c304b122070a417c8a4bcChris Lattner std::vector<Function*> &Writers, 140043870dd85ea41e8972c304b122070a417c8a4bcChris Lattner GlobalValue *OkayStoreDest = 0); 141043870dd85ea41e8972c304b122070a417c8a4bcChris Lattner bool AnalyzeIndirectGlobalMemory(GlobalValue *GV); 142043870dd85ea41e8972c304b122070a417c8a4bcChris Lattner }; 143043870dd85ea41e8972c304b122070a417c8a4bcChris Lattner 144043870dd85ea41e8972c304b122070a417c8a4bcChris Lattner RegisterPass<GlobalsModRef> X("globalsmodref-aa", 145043870dd85ea41e8972c304b122070a417c8a4bcChris Lattner "Simple mod/ref analysis for globals"); 146043870dd85ea41e8972c304b122070a417c8a4bcChris Lattner RegisterAnalysisGroup<AliasAnalysis> Y(X); 147043870dd85ea41e8972c304b122070a417c8a4bcChris Lattner} 148043870dd85ea41e8972c304b122070a417c8a4bcChris Lattner 149043870dd85ea41e8972c304b122070a417c8a4bcChris LattnerPass *llvm::createGlobalsModRefPass() { return new GlobalsModRef(); } 150043870dd85ea41e8972c304b122070a417c8a4bcChris Lattner 1516ce7dc2a97260eea5fba414332796464912b9359Evan Cheng/// getUnderlyingObject - This traverses the use chain to figure out what object 1526ce7dc2a97260eea5fba414332796464912b9359Evan Cheng/// the specified value points to. If the value points to, or is derived from, 153e53f4a055f74bded20d6129b4724ddd17fd199f6Chris Lattner/// a global object, return it. 154e53f4a055f74bded20d6129b4724ddd17fd199f6Chris Lattnerstatic Value *getUnderlyingObject(Value *V) { 155f73823000e2d5d6e1cf65bdf5a107297e18d35fbChris Lattner if (!isa<PointerType>(V->getType())) return V; 156f73823000e2d5d6e1cf65bdf5a107297e18d35fbChris Lattner 157043870dd85ea41e8972c304b122070a417c8a4bcChris Lattner // If we are at some type of object... return it. 158043870dd85ea41e8972c304b122070a417c8a4bcChris Lattner if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) return GV; 1599a1ceaedc282f0cae31f2723f4d6c00c7b88fe90Chris Lattner 1609a1ceaedc282f0cae31f2723f4d6c00c7b88fe90Chris Lattner // Traverse through different addressing mechanisms. 1619a1ceaedc282f0cae31f2723f4d6c00c7b88fe90Chris Lattner if (Instruction *I = dyn_cast<Instruction>(V)) { 1629a1ceaedc282f0cae31f2723f4d6c00c7b88fe90Chris Lattner if (isa<BitCastInst>(I) || isa<GetElementPtrInst>(I)) 163043870dd85ea41e8972c304b122070a417c8a4bcChris Lattner return getUnderlyingObject(I->getOperand(0)); 164043870dd85ea41e8972c304b122070a417c8a4bcChris Lattner } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) { 165bbf1c72d51a77bf54c9c684b90a78e59f0b70b2fChris Lattner if (CE->getOpcode() == Instruction::BitCast || 166bbf1c72d51a77bf54c9c684b90a78e59f0b70b2fChris Lattner CE->getOpcode() == Instruction::GetElementPtr) 167bbf1c72d51a77bf54c9c684b90a78e59f0b70b2fChris Lattner return getUnderlyingObject(CE->getOperand(0)); 168c0f64ffab93d11fb27a3b8a0707b77400918a20eEvan Cheng } 169bbf1c72d51a77bf54c9c684b90a78e59f0b70b2fChris Lattner 170c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner // Othewise, we don't know what this is, return it as the base pointer. 171c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner return V; 172c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner} 173c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner 174c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner/// AnalyzeGlobals - Scan through the users of all of the internal 175c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner/// GlobalValue's in the program. If none of them have their "Address taken" 176c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner/// (really, their address passed to something nontrivial), record this fact, 177c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner/// and record the functions that they are used directly in. 178bfd2ec4a8ef51ebe982363a7e8d7156fdb3827d8Evan Chengvoid GlobalsModRef::AnalyzeGlobals(Module &M) { 179c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner std::vector<Function*> Readers, Writers; 180c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) 181c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner if (I->hasInternalLinkage()) { 182c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner if (!AnalyzeUsesOfPointer(I, Readers, Writers)) { 183c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner // Remember that we are tracking this global. 184c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner NonAddressTakenGlobals.insert(I); 185bfd2ec4a8ef51ebe982363a7e8d7156fdb3827d8Evan Cheng ++NumNonAddrTakenFunctions; 186c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner } 1878aa797aa51cd4ea1ec6f46f4891a6897944b75b2Chris Lattner Readers.clear(); Writers.clear(); 188c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner } 189289c2d5f4566d8d7722e3934f4763d3df92886f3Chris Lattner 190c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner for (Module::global_iterator I = M.global_begin(), E = M.global_end(); 1918aa797aa51cd4ea1ec6f46f4891a6897944b75b2Chris Lattner I != E; ++I) 192c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner if (I->hasInternalLinkage()) { 193c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner if (!AnalyzeUsesOfPointer(I, Readers, Writers)) { 1947c4fe259f8bfeae542cfef25c1f1e9b1ff25a39bChris Lattner // Remember that we are tracking this global, and the mod/ref fns 195c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner NonAddressTakenGlobals.insert(I); 196c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner for (unsigned i = 0, e = Readers.size(); i != e; ++i) 197c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner FunctionInfo[Readers[i]].GlobalInfo[I] |= Ref; 198c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner 199c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner if (!I->isConstant()) // No need to keep track of writers to constants 200c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner for (unsigned i = 0, e = Writers.size(); i != e; ++i) 201c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner FunctionInfo[Writers[i]].GlobalInfo[I] |= Mod; 202c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner ++NumNonAddrTakenGlobalVars; 203c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner 204c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner // If this global holds a pointer type, see if it is an indirect global. 205bfd2ec4a8ef51ebe982363a7e8d7156fdb3827d8Evan Cheng if (isa<PointerType>(I->getType()->getElementType()) && 206c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner AnalyzeIndirectGlobalMemory(I)) 207c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner ++NumIndirectGlobalVars; 208289c2d5f4566d8d7722e3934f4763d3df92886f3Chris Lattner } 209289c2d5f4566d8d7722e3934f4763d3df92886f3Chris Lattner Readers.clear(); Writers.clear(); 210c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner } 2118aa797aa51cd4ea1ec6f46f4891a6897944b75b2Chris Lattner} 212c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner 213c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner/// AnalyzeUsesOfPointer - Look at all of the users of the specified pointer. 2148aa797aa51cd4ea1ec6f46f4891a6897944b75b2Chris Lattner/// If this is used by anything complex (i.e., the address escapes), return 215c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner/// true. Also, while we are at it, keep track of those functions that read and 216c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner/// write to the value. 217c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner/// 21813e8b51e3ec014c5d7ae83afdf3b8fd29c3a461dDale Johannesen/// If OkayStoreDest is non-null, stores into this global are allowed. 21913e8b51e3ec014c5d7ae83afdf3b8fd29c3a461dDale Johannesenbool GlobalsModRef::AnalyzeUsesOfPointer(Value *V, 22013e8b51e3ec014c5d7ae83afdf3b8fd29c3a461dDale Johannesen std::vector<Function*> &Readers, 22113e8b51e3ec014c5d7ae83afdf3b8fd29c3a461dDale Johannesen std::vector<Function*> &Writers, 2228aa797aa51cd4ea1ec6f46f4891a6897944b75b2Chris Lattner GlobalValue *OkayStoreDest) { 22313e8b51e3ec014c5d7ae83afdf3b8fd29c3a461dDale Johannesen if (!isa<PointerType>(V->getType())) return true; 22413e8b51e3ec014c5d7ae83afdf3b8fd29c3a461dDale Johannesen 22513e8b51e3ec014c5d7ae83afdf3b8fd29c3a461dDale Johannesen for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI) 22613e8b51e3ec014c5d7ae83afdf3b8fd29c3a461dDale Johannesen if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) { 22713e8b51e3ec014c5d7ae83afdf3b8fd29c3a461dDale Johannesen Readers.push_back(LI->getParent()->getParent()); 228c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner } else if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) { 229c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner if (V == SI->getOperand(1)) { 230c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner Writers.push_back(SI->getParent()->getParent()); 231c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner } else if (SI->getOperand(1) != OkayStoreDest) { 232b5cdaa257e167a08a8a54ea9249d847ccc415ce0Evan Cheng return true; // Storing the pointer 233c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner } 234b5cdaa257e167a08a8a54ea9249d847ccc415ce0Evan Cheng } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(*UI)) { 235c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner if (AnalyzeUsesOfPointer(GEP, Readers, Writers)) return true; 236289c2d5f4566d8d7722e3934f4763d3df92886f3Chris Lattner } else if (CallInst *CI = dyn_cast<CallInst>(*UI)) { 237b5cdaa257e167a08a8a54ea9249d847ccc415ce0Evan Cheng // Make sure that this is just the function being called, not that it is 238c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner // passing into the function. 239c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner for (unsigned i = 1, e = CI->getNumOperands(); i != e; ++i) 240c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner if (CI->getOperand(i) == V) return true; 241c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner } else if (InvokeInst *II = dyn_cast<InvokeInst>(*UI)) { 242c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner // Make sure that this is just the function being called, not that it is 243c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner // passing into the function. 244b5cdaa257e167a08a8a54ea9249d847ccc415ce0Evan Cheng for (unsigned i = 3, e = II->getNumOperands(); i != e; ++i) 245c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner if (II->getOperand(i) == V) return true; 246289c2d5f4566d8d7722e3934f4763d3df92886f3Chris Lattner } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(*UI)) { 247b5cdaa257e167a08a8a54ea9249d847ccc415ce0Evan Cheng if (CE->getOpcode() == Instruction::GetElementPtr || 248c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner CE->getOpcode() == Instruction::BitCast) { 249c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner if (AnalyzeUsesOfPointer(CE, Readers, Writers)) 250c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner return true; 251b5cdaa257e167a08a8a54ea9249d847ccc415ce0Evan Cheng } else { 252c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner return true; 253c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner } 254b5cdaa257e167a08a8a54ea9249d847ccc415ce0Evan Cheng } else if (ICmpInst *ICI = dyn_cast<ICmpInst>(*UI)) { 255b5cdaa257e167a08a8a54ea9249d847ccc415ce0Evan Cheng if (!isa<ConstantPointerNull>(ICI->getOperand(1))) 256b5cdaa257e167a08a8a54ea9249d847ccc415ce0Evan Cheng return true; // Allow comparison against null. 257b5cdaa257e167a08a8a54ea9249d847ccc415ce0Evan Cheng } else if (FreeInst *F = dyn_cast<FreeInst>(*UI)) { 2582dc7723474c54efcbcac6265dad0a7271902f1a5Chris Lattner Writers.push_back(F->getParent()->getParent()); 2592dc7723474c54efcbcac6265dad0a7271902f1a5Chris Lattner } else { 26054108068b71a7dbc48f4ebf1b2d7d87ca541070aChris Lattner return true; 26154108068b71a7dbc48f4ebf1b2d7d87ca541070aChris Lattner } 2622dc7723474c54efcbcac6265dad0a7271902f1a5Chris Lattner return false; 26354108068b71a7dbc48f4ebf1b2d7d87ca541070aChris Lattner} 2642dc7723474c54efcbcac6265dad0a7271902f1a5Chris Lattner 26554108068b71a7dbc48f4ebf1b2d7d87ca541070aChris Lattner/// AnalyzeIndirectGlobalMemory - We found an non-address-taken global variable 266c0f64ffab93d11fb27a3b8a0707b77400918a20eEvan Cheng/// which holds a pointer type. See if the global always points to non-aliased 26754108068b71a7dbc48f4ebf1b2d7d87ca541070aChris Lattner/// heap memory: that is, all initializers of the globals are allocations, and 268c0f64ffab93d11fb27a3b8a0707b77400918a20eEvan Cheng/// those allocations have no use other than initialization of the global. 26918258c640466274c26e89016e361ec411ff78520Chris Lattner/// Further, all loads out of GV must directly use the memory, not store the 270b5cdaa257e167a08a8a54ea9249d847ccc415ce0Evan Cheng/// pointer somewhere. If this is true, we consider the memory pointed to by 2712dc7723474c54efcbcac6265dad0a7271902f1a5Chris Lattner/// GV to be owned by GV and can disambiguate other pointers from it. 272c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattnerbool GlobalsModRef::AnalyzeIndirectGlobalMemory(GlobalValue *GV) { 273879d09cf130f3760a08865913c04d9ff328fad5fChris Lattner // Keep track of values related to the allocation of the memory, f.e. the 274c0f64ffab93d11fb27a3b8a0707b77400918a20eEvan Cheng // value produced by the malloc call and any casts. 27518258c640466274c26e89016e361ec411ff78520Chris Lattner std::vector<Value*> AllocRelatedValues; 276c0f64ffab93d11fb27a3b8a0707b77400918a20eEvan Cheng 277b5cdaa257e167a08a8a54ea9249d847ccc415ce0Evan Cheng // Walk the user list of the global. If we find anything other than a direct 278c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner // load or store, bail out. 279c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner for (Value::use_iterator I = GV->use_begin(), E = GV->use_end(); I != E; ++I){ 280d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson if (LoadInst *LI = dyn_cast<LoadInst>(*I)) { 281d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson // The pointer loaded from the global can only be used in simple ways: 282d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson // we allow addressing of it and loading storing to it. We do *not* allow 283d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson // storing the loaded pointer somewhere else or passing to a function. 284d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson std::vector<Function*> ReadersWriters; 285d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson if (AnalyzeUsesOfPointer(LI, ReadersWriters, ReadersWriters)) 286d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson return false; // Loaded pointer escapes. 287d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson // TODO: Could try some IP mod/ref of the loaded pointer. 288d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson } else if (StoreInst *SI = dyn_cast<StoreInst>(*I)) { 289d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson // Storing the global itself. 290d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson if (SI->getOperand(0) == GV) return false; 291d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson 292d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson // If storing the null pointer, ignore it. 293d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson if (isa<ConstantPointerNull>(SI->getOperand(0))) 294d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson continue; 295d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson 296d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson // Check the value being stored. 297d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson Value *Ptr = getUnderlyingObject(SI->getOperand(0)); 298d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson 299d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson if (isa<MallocInst>(Ptr)) { 300d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson // Okay, easy case. 301d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson } else if (CallInst *CI = dyn_cast<CallInst>(Ptr)) { 302d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson Function *F = CI->getCalledFunction(); 303d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson if (!F || !F->isDeclaration()) return false; // Too hard to analyze. 304d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson if (F->getName() != "calloc") return false; // Not calloc. 305d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson } else { 306d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson return false; // Too hard to analyze. 307d10fd9791c20fd8368fa0ce94b626b769c6c8ba0Owen Anderson } 308ef13982aa7f3e57e82cd48370e79033dff0da295Chris Lattner 309ef13982aa7f3e57e82cd48370e79033dff0da295Chris Lattner // Analyze all uses of the allocation. If any of them are used in a 310ef13982aa7f3e57e82cd48370e79033dff0da295Chris Lattner // non-simple way (e.g. stored to another global) bail out. 311ef13982aa7f3e57e82cd48370e79033dff0da295Chris Lattner std::vector<Function*> ReadersWriters; 312126f17a17625876adb63f06d043fc1b1e4f0361cEvan Cheng if (AnalyzeUsesOfPointer(Ptr, ReadersWriters, ReadersWriters, GV)) 313ef13982aa7f3e57e82cd48370e79033dff0da295Chris Lattner return false; // Loaded pointer escapes. 314ef13982aa7f3e57e82cd48370e79033dff0da295Chris Lattner 315ef13982aa7f3e57e82cd48370e79033dff0da295Chris Lattner // Remember that this allocation is related to the indirect global. 316ef13982aa7f3e57e82cd48370e79033dff0da295Chris Lattner AllocRelatedValues.push_back(Ptr); 317ef13982aa7f3e57e82cd48370e79033dff0da295Chris Lattner } else { 318ef13982aa7f3e57e82cd48370e79033dff0da295Chris Lattner // Something complex, bail out. 319ef13982aa7f3e57e82cd48370e79033dff0da295Chris Lattner return false; 320c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner } 321c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner } 3227c4fe259f8bfeae542cfef25c1f1e9b1ff25a39bChris Lattner 3237c4fe259f8bfeae542cfef25c1f1e9b1ff25a39bChris Lattner // Okay, this is an indirect global. Remember all of the allocations for 32418258c640466274c26e89016e361ec411ff78520Chris Lattner // this global in AllocsForIndirectGlobals. 3257c4fe259f8bfeae542cfef25c1f1e9b1ff25a39bChris Lattner while (!AllocRelatedValues.empty()) { 326c50e2bcdf7bff1f9681ab80e52691f274950fab5Chris Lattner AllocsForIndirectGlobals[AllocRelatedValues.back()] = GV; 327 AllocRelatedValues.pop_back(); 328 } 329 IndirectGlobals.insert(GV); 330 return true; 331} 332 333/// AnalyzeCallGraph - At this point, we know the functions where globals are 334/// immediately stored to and read from. Propagate this information up the call 335/// graph to all callers and compute the mod/ref info for all memory for each 336/// function. 337void GlobalsModRef::AnalyzeCallGraph(CallGraph &CG, Module &M) { 338 // We do a bottom-up SCC traversal of the call graph. In other words, we 339 // visit all callees before callers (leaf-first). 340 for (scc_iterator<CallGraph*> I = scc_begin(&CG), E = scc_end(&CG); I!=E; ++I) 341 if ((*I).size() != 1) { 342 AnalyzeSCC(*I); 343 } else if (Function *F = (*I)[0]->getFunction()) { 344 if (!F->isDeclaration()) { 345 // Nonexternal function. 346 AnalyzeSCC(*I); 347 } else { 348 // Otherwise external function. Handle intrinsics and other special 349 // cases here. 350 if (getAnalysis<AliasAnalysis>().doesNotAccessMemory(F)) 351 // If it does not access memory, process the function, causing us to 352 // realize it doesn't do anything (the body is empty). 353 AnalyzeSCC(*I); 354 else { 355 // Otherwise, don't process it. This will cause us to conservatively 356 // assume the worst. 357 } 358 } 359 } else { 360 // Do not process the external node, assume the worst. 361 } 362} 363 364void GlobalsModRef::AnalyzeSCC(std::vector<CallGraphNode *> &SCC) { 365 assert(!SCC.empty() && "SCC with no functions?"); 366 FunctionRecord &FR = FunctionInfo[SCC[0]->getFunction()]; 367 368 bool CallsExternal = false; 369 unsigned FunctionEffect = 0; 370 371 // Collect the mod/ref properties due to called functions. We only compute 372 // one mod-ref set 373 for (unsigned i = 0, e = SCC.size(); i != e && !CallsExternal; ++i) 374 for (CallGraphNode::iterator CI = SCC[i]->begin(), E = SCC[i]->end(); 375 CI != E; ++CI) 376 if (Function *Callee = CI->second->getFunction()) { 377 if (FunctionRecord *CalleeFR = getFunctionInfo(Callee)) { 378 // Propagate function effect up. 379 FunctionEffect |= CalleeFR->FunctionEffect; 380 381 // Incorporate callee's effects on globals into our info. 382 for (std::map<GlobalValue*, unsigned>::iterator GI = 383 CalleeFR->GlobalInfo.begin(), E = CalleeFR->GlobalInfo.end(); 384 GI != E; ++GI) 385 FR.GlobalInfo[GI->first] |= GI->second; 386 387 } else { 388 // Okay, if we can't say anything about it, maybe some other alias 389 // analysis can. 390 ModRefBehavior MRB = 391 AliasAnalysis::getModRefBehavior(Callee, CallSite()); 392 if (MRB != DoesNotAccessMemory) { 393 // FIXME: could make this more aggressive for functions that just 394 // read memory. We should just say they read all globals. 395 CallsExternal = true; 396 break; 397 } 398 } 399 } else { 400 CallsExternal = true; 401 break; 402 } 403 404 // If this SCC calls an external function, we can't say anything about it, so 405 // remove all SCC functions from the FunctionInfo map. 406 if (CallsExternal) { 407 for (unsigned i = 0, e = SCC.size(); i != e; ++i) 408 FunctionInfo.erase(SCC[i]->getFunction()); 409 return; 410 } 411 412 // Otherwise, unless we already know that this function mod/refs memory, scan 413 // the function bodies to see if there are any explicit loads or stores. 414 if (FunctionEffect != ModRef) { 415 for (unsigned i = 0, e = SCC.size(); i != e && FunctionEffect != ModRef;++i) 416 for (inst_iterator II = inst_begin(SCC[i]->getFunction()), 417 E = inst_end(SCC[i]->getFunction()); 418 II != E && FunctionEffect != ModRef; ++II) 419 if (isa<LoadInst>(*II)) 420 FunctionEffect |= Ref; 421 else if (isa<StoreInst>(*II)) 422 FunctionEffect |= Mod; 423 else if (isa<MallocInst>(*II) || isa<FreeInst>(*II)) 424 FunctionEffect |= ModRef; 425 } 426 427 if ((FunctionEffect & Mod) == 0) 428 ++NumReadMemFunctions; 429 if (FunctionEffect == 0) 430 ++NumNoMemFunctions; 431 FR.FunctionEffect = FunctionEffect; 432 433 // Finally, now that we know the full effect on this SCC, clone the 434 // information to each function in the SCC. 435 for (unsigned i = 1, e = SCC.size(); i != e; ++i) 436 FunctionInfo[SCC[i]->getFunction()] = FR; 437} 438 439 440 441/// alias - If one of the pointers is to a global that we are tracking, and the 442/// other is some random pointer, we know there cannot be an alias, because the 443/// address of the global isn't taken. 444AliasAnalysis::AliasResult 445GlobalsModRef::alias(const Value *V1, unsigned V1Size, 446 const Value *V2, unsigned V2Size) { 447 // Get the base object these pointers point to. 448 Value *UV1 = getUnderlyingObject(const_cast<Value*>(V1)); 449 Value *UV2 = getUnderlyingObject(const_cast<Value*>(V2)); 450 451 // If either of the underlying values is a global, they may be non-addr-taken 452 // globals, which we can answer queries about. 453 GlobalValue *GV1 = dyn_cast<GlobalValue>(UV1); 454 GlobalValue *GV2 = dyn_cast<GlobalValue>(UV2); 455 if (GV1 || GV2) { 456 // If the global's address is taken, pretend we don't know it's a pointer to 457 // the global. 458 if (GV1 && !NonAddressTakenGlobals.count(GV1)) GV1 = 0; 459 if (GV2 && !NonAddressTakenGlobals.count(GV2)) GV2 = 0; 460 461 // If the the two pointers are derived from two different non-addr-taken 462 // globals, or if one is and the other isn't, we know these can't alias. 463 if ((GV1 || GV2) && GV1 != GV2) 464 return NoAlias; 465 466 // Otherwise if they are both derived from the same addr-taken global, we 467 // can't know the two accesses don't overlap. 468 } 469 470 // These pointers may be based on the memory owned by an indirect global. If 471 // so, we may be able to handle this. First check to see if the base pointer 472 // is a direct load from an indirect global. 473 GV1 = GV2 = 0; 474 if (LoadInst *LI = dyn_cast<LoadInst>(UV1)) 475 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0))) 476 if (IndirectGlobals.count(GV)) 477 GV1 = GV; 478 if (LoadInst *LI = dyn_cast<LoadInst>(UV2)) 479 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0))) 480 if (IndirectGlobals.count(GV)) 481 GV2 = GV; 482 483 // These pointers may also be from an allocation for the indirect global. If 484 // so, also handle them. 485 if (AllocsForIndirectGlobals.count(UV1)) 486 GV1 = AllocsForIndirectGlobals[UV1]; 487 if (AllocsForIndirectGlobals.count(UV2)) 488 GV2 = AllocsForIndirectGlobals[UV2]; 489 490 // Now that we know whether the two pointers are related to indirect globals, 491 // use this to disambiguate the pointers. If either pointer is based on an 492 // indirect global and if they are not both based on the same indirect global, 493 // they cannot alias. 494 if ((GV1 || GV2) && GV1 != GV2) 495 return NoAlias; 496 497 return AliasAnalysis::alias(V1, V1Size, V2, V2Size); 498} 499 500AliasAnalysis::ModRefResult 501GlobalsModRef::getModRefInfo(CallSite CS, Value *P, unsigned Size) { 502 unsigned Known = ModRef; 503 504 // If we are asking for mod/ref info of a direct call with a pointer to a 505 // global we are tracking, return information if we have it. 506 if (GlobalValue *GV = dyn_cast<GlobalValue>(getUnderlyingObject(P))) 507 if (GV->hasInternalLinkage()) 508 if (Function *F = CS.getCalledFunction()) 509 if (NonAddressTakenGlobals.count(GV)) 510 if (FunctionRecord *FR = getFunctionInfo(F)) 511 Known = FR->getInfoForGlobal(GV); 512 513 if (Known == NoModRef) 514 return NoModRef; // No need to query other mod/ref analyses 515 return ModRefResult(Known & AliasAnalysis::getModRefInfo(CS, P, Size)); 516} 517 518 519//===----------------------------------------------------------------------===// 520// Methods to update the analysis as a result of the client transformation. 521// 522void GlobalsModRef::deleteValue(Value *V) { 523 if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) { 524 if (NonAddressTakenGlobals.erase(GV)) { 525 // This global might be an indirect global. If so, remove it and remove 526 // any AllocRelatedValues for it. 527 if (IndirectGlobals.erase(GV)) { 528 // Remove any entries in AllocsForIndirectGlobals for this global. 529 for (std::map<Value*, GlobalValue*>::iterator 530 I = AllocsForIndirectGlobals.begin(), 531 E = AllocsForIndirectGlobals.end(); I != E; ) { 532 if (I->second == GV) { 533 AllocsForIndirectGlobals.erase(I++); 534 } else { 535 ++I; 536 } 537 } 538 } 539 } 540 } 541 542 // Otherwise, if this is an allocation related to an indirect global, remove 543 // it. 544 AllocsForIndirectGlobals.erase(V); 545} 546 547void GlobalsModRef::copyValue(Value *From, Value *To) { 548} 549