GlobalsModRef.cpp revision e79422096ea5319a365d160693d0957a2a4df75e
13b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner//===- GlobalsModRef.cpp - Simple Mod/Ref Analysis for Globals ------------===// 22b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman// 33b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner// The LLVM Compiler Infrastructure 43b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner// 54ee451de366474b9c228b4e5fa573795a715216dChris Lattner// This file is distributed under the University of Illinois Open Source 64ee451de366474b9c228b4e5fa573795a715216dChris Lattner// License. See LICENSE.TXT for details. 72b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman// 83b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner//===----------------------------------------------------------------------===// 93b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner// 103b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner// This simple pass provides alias and mod/ref information for global values 11fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner// that do not have their address taken, and keeps track of whether functions 12fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner// read or write memory (are "pure"). For this simple (but very common) case, 13fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner// we can provide pretty accurate and useful information. 143b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner// 153b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner//===----------------------------------------------------------------------===// 163b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 173b27d68c6af2582df0962557f1fe5c3f70f46e3fChris Lattner#define DEBUG_TYPE "globalsmodref-aa" 183b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner#include "llvm/Analysis/Passes.h" 193b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner#include "llvm/Module.h" 203b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner#include "llvm/Pass.h" 213b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner#include "llvm/Instructions.h" 223b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner#include "llvm/Constants.h" 23ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner#include "llvm/DerivedTypes.h" 243b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner#include "llvm/Analysis/AliasAnalysis.h" 253b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner#include "llvm/Analysis/CallGraph.h" 26d7d83db5f22d05e5b14b6b1d838668222113c83aReid Spencer#include "llvm/Support/Compiler.h" 27551ccae044b0ff658fe629dd67edd5ffe75d10e8Reid Spencer#include "llvm/Support/CommandLine.h" 28d7d83db5f22d05e5b14b6b1d838668222113c83aReid Spencer#include "llvm/Support/InstIterator.h" 29551ccae044b0ff658fe629dd67edd5ffe75d10e8Reid Spencer#include "llvm/ADT/Statistic.h" 30551ccae044b0ff658fe629dd67edd5ffe75d10e8Reid Spencer#include "llvm/ADT/SCCIterator.h" 313b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner#include <set> 323b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattnerusing namespace llvm; 333b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 343b27d68c6af2582df0962557f1fe5c3f70f46e3fChris LattnerSTATISTIC(NumNonAddrTakenGlobalVars, 353b27d68c6af2582df0962557f1fe5c3f70f46e3fChris Lattner "Number of global vars without address taken"); 363b27d68c6af2582df0962557f1fe5c3f70f46e3fChris LattnerSTATISTIC(NumNonAddrTakenFunctions,"Number of functions without address taken"); 373b27d68c6af2582df0962557f1fe5c3f70f46e3fChris LattnerSTATISTIC(NumNoMemFunctions, "Number of functions that do not access memory"); 383b27d68c6af2582df0962557f1fe5c3f70f46e3fChris LattnerSTATISTIC(NumReadMemFunctions, "Number of functions that only read memory"); 393b27d68c6af2582df0962557f1fe5c3f70f46e3fChris LattnerSTATISTIC(NumIndirectGlobalVars, "Number of indirect global objects"); 403b27d68c6af2582df0962557f1fe5c3f70f46e3fChris Lattner 413b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattnernamespace { 42fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// FunctionRecord - One instance of this structure is stored for every 43fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// function in the program. Later, the entries for these functions are 44fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// removed if the function is found to call an external function (in which 45fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// case we know nothing about it. 46d7d83db5f22d05e5b14b6b1d838668222113c83aReid Spencer struct VISIBILITY_HIDDEN FunctionRecord { 47fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// GlobalInfo - Maintain mod/ref info for all of the globals without 48fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// addresses taken that are read or written (transitively) by this 49fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// function. 50fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner std::map<GlobalValue*, unsigned> GlobalInfo; 51fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 522bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands /// MayReadAnyGlobal - May read global variables, but it is not known which. 532bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands bool MayReadAnyGlobal; 542bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands 55fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner unsigned getInfoForGlobal(GlobalValue *GV) const { 562bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands unsigned Effect = MayReadAnyGlobal ? AliasAnalysis::Ref : 0; 57fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner std::map<GlobalValue*, unsigned>::const_iterator I = GlobalInfo.find(GV); 58fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (I != GlobalInfo.end()) 592bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands Effect |= I->second; 602bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands return Effect; 61fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner } 622b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman 63fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// FunctionEffect - Capture whether or not this function reads or writes to 64fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// ANY memory. If not, we can do a lot of aggressive analysis on it. 65fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner unsigned FunctionEffect; 66105d26acb4158daea4e54919cfd12545a3d901eaChris Lattner 672bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands FunctionRecord() : MayReadAnyGlobal (false), FunctionEffect(0) {} 68fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner }; 693b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 70fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// GlobalsModRef - The actual analysis pass. 719a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands class VISIBILITY_HIDDEN GlobalsModRef 72d7d83db5f22d05e5b14b6b1d838668222113c83aReid Spencer : public ModulePass, public AliasAnalysis { 73fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// NonAddressTakenGlobals - The globals that do not have their addresses 74fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// taken. 75fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner std::set<GlobalValue*> NonAddressTakenGlobals; 763b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 77ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner /// IndirectGlobals - The memory pointed to by this global is known to be 78ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner /// 'owned' by the global. 79ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::set<GlobalValue*> IndirectGlobals; 809a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 81ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner /// AllocsForIndirectGlobals - If an instruction allocates memory for an 82ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner /// indirect global, this map indicates which one. 83ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::map<Value*, GlobalValue*> AllocsForIndirectGlobals; 849a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 853b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner /// FunctionInfo - For each function, keep track of what globals are 863b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner /// modified or read. 87fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner std::map<Function*, FunctionRecord> FunctionInfo; 883b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 893b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner public: 901997473cf72957d0e70322e2fe6fe2ab141c58a6Devang Patel static char ID; 91ae73dc1448d25b02cabc7c64c86c64371453dda8Dan Gohman GlobalsModRef() : ModulePass(&ID) {} 921cee94f04111cfd7114979d6dfddce2669c9380dDevang Patel 93b12914bfc0f76a7a48357162d5f4c39a1343e69bChris Lattner bool runOnModule(Module &M) { 943b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner InitializeAliasAnalysis(this); // set up super class 953b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner AnalyzeGlobals(M); // find non-addr taken globals 963b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner AnalyzeCallGraph(getAnalysis<CallGraph>(), M); // Propagate on CG 973b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return false; 983b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 993b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 1003b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner virtual void getAnalysisUsage(AnalysisUsage &AU) const { 1013b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner AliasAnalysis::getAnalysisUsage(AU); 1023b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner AU.addRequired<CallGraph>(); 1033b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner AU.setPreservesAll(); // Does not transform code 1043b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 1053b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 1063b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner //------------------------------------------------ 1073b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // Implement the AliasAnalysis API 1082b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman // 1093b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner AliasResult alias(const Value *V1, unsigned V1Size, 1103b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner const Value *V2, unsigned V2Size); 1113b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size); 1124a7ebfa4111305ea22fc753d4f029eed88149662Reid Spencer ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) { 1134a7ebfa4111305ea22fc753d4f029eed88149662Reid Spencer return AliasAnalysis::getModRefInfo(CS1,CS2); 1144a7ebfa4111305ea22fc753d4f029eed88149662Reid Spencer } 1153b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner bool hasNoModRefInfoForCalls() const { return false; } 1163b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 1170af024c5d00c2a2d0e35ba33f4aaf4ed3fadfae2Chris Lattner /// getModRefBehavior - Return the behavior of the specified function if 1180af024c5d00c2a2d0e35ba33f4aaf4ed3fadfae2Chris Lattner /// called from the specified call site. The call site may be null in which 1190af024c5d00c2a2d0e35ba33f4aaf4ed3fadfae2Chris Lattner /// case the most generic behavior of this function should be returned. 120e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson ModRefBehavior getModRefBehavior(Function *F, 12141925f87d3e7fc9eb2b583267b99012dcb2774a0Chris Lattner std::vector<PointerAccessInfo> *Info) { 122ae9f3a3b7c915f725aef5a7250e88eaeddda03c6Anton Korobeynikov if (FunctionRecord *FR = getFunctionInfo(F)) { 123fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (FR->FunctionEffect == 0) 1240af024c5d00c2a2d0e35ba33f4aaf4ed3fadfae2Chris Lattner return DoesNotAccessMemory; 125dedf2bd5a34dac25e4245f58bb902ced6b64edd9Misha Brukman else if ((FR->FunctionEffect & Mod) == 0) 126dedf2bd5a34dac25e4245f58bb902ced6b64edd9Misha Brukman return OnlyReadsMemory; 127ae9f3a3b7c915f725aef5a7250e88eaeddda03c6Anton Korobeynikov } 128e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson return AliasAnalysis::getModRefBehavior(F, Info); 129e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson } 130e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson 131e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson /// getModRefBehavior - Return the behavior of the specified function if 132e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson /// called from the specified call site. The call site may be null in which 133e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson /// case the most generic behavior of this function should be returned. 134e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson ModRefBehavior getModRefBehavior(CallSite CS, 135e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson std::vector<PointerAccessInfo> *Info) { 136e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson Function* F = CS.getCalledFunction(); 137e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson if (!F) return AliasAnalysis::getModRefBehavior(CS, Info); 138e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson if (FunctionRecord *FR = getFunctionInfo(F)) { 139e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson if (FR->FunctionEffect == 0) 140e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson return DoesNotAccessMemory; 141e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson else if ((FR->FunctionEffect & Mod) == 0) 142e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson return OnlyReadsMemory; 143e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson } 144e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson return AliasAnalysis::getModRefBehavior(CS, Info); 145fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner } 146fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 1473b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner virtual void deleteValue(Value *V); 1483b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner virtual void copyValue(Value *From, Value *To); 1493b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 1503b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner private: 151fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// getFunctionInfo - Return the function info for the function, or null if 1529a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands /// we don't have anything useful to say about it. 153fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FunctionRecord *getFunctionInfo(Function *F) { 154fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner std::map<Function*, FunctionRecord>::iterator I = FunctionInfo.find(F); 155fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (I != FunctionInfo.end()) 156fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner return &I->second; 157fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner return 0; 158fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner } 159fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 1603b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner void AnalyzeGlobals(Module &M); 1613b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner void AnalyzeCallGraph(CallGraph &CG, Module &M); 162ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner bool AnalyzeUsesOfPointer(Value *V, std::vector<Function*> &Readers, 163ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Function*> &Writers, 164ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GlobalValue *OkayStoreDest = 0); 165ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner bool AnalyzeIndirectGlobalMemory(GlobalValue *GV); 1663b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner }; 1673b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 1683b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 169844731a7f1909f55935e3514c9e713a62d67662eDan Gohmanchar GlobalsModRef::ID = 0; 170844731a7f1909f55935e3514c9e713a62d67662eDan Gohmanstatic RegisterPass<GlobalsModRef> 171844731a7f1909f55935e3514c9e713a62d67662eDan GohmanX("globalsmodref-aa", "Simple mod/ref analysis for globals", false, true); 172844731a7f1909f55935e3514c9e713a62d67662eDan Gohmanstatic RegisterAnalysisGroup<AliasAnalysis> Y(X); 173844731a7f1909f55935e3514c9e713a62d67662eDan Gohman 1743b04a8ac455568f9b98ab7e9a43076260cb737aeChris LattnerPass *llvm::createGlobalsModRefPass() { return new GlobalsModRef(); } 1753b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 176ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// AnalyzeGlobals - Scan through the users of all of the internal 1779a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands/// GlobalValue's in the program. If none of them have their "address taken" 1783b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// (really, their address passed to something nontrivial), record this fact, 1793b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// and record the functions that they are used directly in. 1803b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattnervoid GlobalsModRef::AnalyzeGlobals(Module &M) { 1813b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner std::vector<Function*> Readers, Writers; 1823b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) 183bb46f52027416598a662dc1c58f48d9d56b1a65bRafael Espindola if (I->hasLocalLinkage()) { 184ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (!AnalyzeUsesOfPointer(I, Readers, Writers)) { 185fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner // Remember that we are tracking this global. 186fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner NonAddressTakenGlobals.insert(I); 1873b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner ++NumNonAddrTakenFunctions; 1883b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 1893b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner Readers.clear(); Writers.clear(); 1903b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 1913b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 192f5eaf3c62c7b2f2da1f85ac411c4f13bcbf131f1Chris Lattner for (Module::global_iterator I = M.global_begin(), E = M.global_end(); 193f5eaf3c62c7b2f2da1f85ac411c4f13bcbf131f1Chris Lattner I != E; ++I) 194bb46f52027416598a662dc1c58f48d9d56b1a65bRafael Espindola if (I->hasLocalLinkage()) { 195ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (!AnalyzeUsesOfPointer(I, Readers, Writers)) { 1963b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // Remember that we are tracking this global, and the mod/ref fns 197fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner NonAddressTakenGlobals.insert(I); 1989a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 199fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner for (unsigned i = 0, e = Readers.size(); i != e; ++i) 200fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FunctionInfo[Readers[i]].GlobalInfo[I] |= Ref; 201fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 202fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (!I->isConstant()) // No need to keep track of writers to constants 203fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner for (unsigned i = 0, e = Writers.size(); i != e; ++i) 204fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FunctionInfo[Writers[i]].GlobalInfo[I] |= Mod; 2053b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner ++NumNonAddrTakenGlobalVars; 2069a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 207ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // If this global holds a pointer type, see if it is an indirect global. 208ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (isa<PointerType>(I->getType()->getElementType()) && 209ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner AnalyzeIndirectGlobalMemory(I)) 210ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner ++NumIndirectGlobalVars; 2113b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 2123b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner Readers.clear(); Writers.clear(); 2133b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 2143b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 2153b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 216ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// AnalyzeUsesOfPointer - Look at all of the users of the specified pointer. 217ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// If this is used by anything complex (i.e., the address escapes), return 218ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// true. Also, while we are at it, keep track of those functions that read and 219ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// write to the value. 220ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// 221ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// If OkayStoreDest is non-null, stores into this global are allowed. 222ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattnerbool GlobalsModRef::AnalyzeUsesOfPointer(Value *V, 223ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Function*> &Readers, 224ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Function*> &Writers, 225ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GlobalValue *OkayStoreDest) { 226fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (!isa<PointerType>(V->getType())) return true; 2273b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 2283b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI) 2293b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) { 2303b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner Readers.push_back(LI->getParent()->getParent()); 2313b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } else if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) { 232ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (V == SI->getOperand(1)) { 233ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner Writers.push_back(SI->getParent()->getParent()); 234ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else if (SI->getOperand(1) != OkayStoreDest) { 235ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return true; // Storing the pointer 236ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 2373b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(*UI)) { 238ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AnalyzeUsesOfPointer(GEP, Readers, Writers)) return true; 2393b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } else if (CallInst *CI = dyn_cast<CallInst>(*UI)) { 2403b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // Make sure that this is just the function being called, not that it is 2413b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // passing into the function. 2423b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner for (unsigned i = 1, e = CI->getNumOperands(); i != e; ++i) 2433b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner if (CI->getOperand(i) == V) return true; 2443b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } else if (InvokeInst *II = dyn_cast<InvokeInst>(*UI)) { 2453b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // Make sure that this is just the function being called, not that it is 2463b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // passing into the function. 2473b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner for (unsigned i = 3, e = II->getNumOperands(); i != e; ++i) 2483b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner if (II->getOperand(i) == V) return true; 2493b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(*UI)) { 2509a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (CE->getOpcode() == Instruction::GetElementPtr || 2513da59db637a887474c1b1346c1f3ccf53b6c4663Reid Spencer CE->getOpcode() == Instruction::BitCast) { 252ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AnalyzeUsesOfPointer(CE, Readers, Writers)) 2533b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return true; 2543b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } else { 2553b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return true; 2562b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman } 257e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer } else if (ICmpInst *ICI = dyn_cast<ICmpInst>(*UI)) { 258e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer if (!isa<ConstantPointerNull>(ICI->getOperand(1))) 259ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return true; // Allow comparison against null. 260ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else if (FreeInst *F = dyn_cast<FreeInst>(*UI)) { 261ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner Writers.push_back(F->getParent()->getParent()); 2623b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } else { 2633b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return true; 2643b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 2653b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return false; 2663b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 2673b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 268ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// AnalyzeIndirectGlobalMemory - We found an non-address-taken global variable 269ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// which holds a pointer type. See if the global always points to non-aliased 270ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// heap memory: that is, all initializers of the globals are allocations, and 271ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// those allocations have no use other than initialization of the global. 272ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// Further, all loads out of GV must directly use the memory, not store the 273ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// pointer somewhere. If this is true, we consider the memory pointed to by 274ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// GV to be owned by GV and can disambiguate other pointers from it. 275ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattnerbool GlobalsModRef::AnalyzeIndirectGlobalMemory(GlobalValue *GV) { 276ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Keep track of values related to the allocation of the memory, f.e. the 277ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // value produced by the malloc call and any casts. 278ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Value*> AllocRelatedValues; 2799a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 280ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Walk the user list of the global. If we find anything other than a direct 281ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // load or store, bail out. 282ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner for (Value::use_iterator I = GV->use_begin(), E = GV->use_end(); I != E; ++I){ 283ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (LoadInst *LI = dyn_cast<LoadInst>(*I)) { 284ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // The pointer loaded from the global can only be used in simple ways: 285ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // we allow addressing of it and loading storing to it. We do *not* allow 286ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // storing the loaded pointer somewhere else or passing to a function. 287ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Function*> ReadersWriters; 288ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AnalyzeUsesOfPointer(LI, ReadersWriters, ReadersWriters)) 289ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return false; // Loaded pointer escapes. 290ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // TODO: Could try some IP mod/ref of the loaded pointer. 291ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else if (StoreInst *SI = dyn_cast<StoreInst>(*I)) { 292ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Storing the global itself. 293ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (SI->getOperand(0) == GV) return false; 2949a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 295ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // If storing the null pointer, ignore it. 296ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (isa<ConstantPointerNull>(SI->getOperand(0))) 297ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner continue; 2989a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 299ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Check the value being stored. 3005d0392c6b370758750b397e254a6c6f028479969Duncan Sands Value *Ptr = SI->getOperand(0)->getUnderlyingObject(); 301ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 302ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (isa<MallocInst>(Ptr)) { 303ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Okay, easy case. 304ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else if (CallInst *CI = dyn_cast<CallInst>(Ptr)) { 305ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner Function *F = CI->getCalledFunction(); 3065cbf985dcbc89fba3208e7baf8b6f488b06d3ec9Reid Spencer if (!F || !F->isDeclaration()) return false; // Too hard to analyze. 307ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (F->getName() != "calloc") return false; // Not calloc. 308ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else { 309ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return false; // Too hard to analyze. 310ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 3119a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 312ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Analyze all uses of the allocation. If any of them are used in a 313ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // non-simple way (e.g. stored to another global) bail out. 314ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Function*> ReadersWriters; 315ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AnalyzeUsesOfPointer(Ptr, ReadersWriters, ReadersWriters, GV)) 316ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return false; // Loaded pointer escapes. 317ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 318ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Remember that this allocation is related to the indirect global. 319ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner AllocRelatedValues.push_back(Ptr); 320ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else { 321ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Something complex, bail out. 322ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return false; 323ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 324ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 3259a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 326ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Okay, this is an indirect global. Remember all of the allocations for 327ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // this global in AllocsForIndirectGlobals. 328ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner while (!AllocRelatedValues.empty()) { 329ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner AllocsForIndirectGlobals[AllocRelatedValues.back()] = GV; 330ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner AllocRelatedValues.pop_back(); 331ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 332ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner IndirectGlobals.insert(GV); 333ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return true; 334ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner} 335ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 3363b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// AnalyzeCallGraph - At this point, we know the functions where globals are 3373b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// immediately stored to and read from. Propagate this information up the call 338fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner/// graph to all callers and compute the mod/ref info for all memory for each 3392b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman/// function. 3403b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattnervoid GlobalsModRef::AnalyzeCallGraph(CallGraph &CG, Module &M) { 3413b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // We do a bottom-up SCC traversal of the call graph. In other words, we 3423b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // visit all callees before callers (leaf-first). 3439a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands for (scc_iterator<CallGraph*> I = scc_begin(&CG), E = scc_end(&CG); I != E; 3449a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands ++I) { 3459a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands std::vector<CallGraphNode *> &SCC = *I; 346f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands assert(!SCC.empty() && "SCC with no functions?"); 3479a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 348f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands if (!SCC[0]->getFunction()) { 349f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands // Calls externally - can't say anything useful. Remove any existing 350f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands // function records (may have been created when scanning globals). 351f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands for (unsigned i = 0, e = SCC.size(); i != e; ++i) 352f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands FunctionInfo.erase(SCC[i]->getFunction()); 35334f2a0ca17f00f9ce2081ee278685a007856fd90Duncan Sands continue; 354f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands } 355f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands 356f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands FunctionRecord &FR = FunctionInfo[SCC[0]->getFunction()]; 3573b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 3589a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands bool KnowNothing = false; 3599a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands unsigned FunctionEffect = 0; 3609a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 3619a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // Collect the mod/ref properties due to called functions. We only compute 3629a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // one mod-ref set. 3639a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands for (unsigned i = 0, e = SCC.size(); i != e && !KnowNothing; ++i) { 3649a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands Function *F = SCC[i]->getFunction(); 3659a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (!F) { 3669a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands KnowNothing = true; 367fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner break; 3683b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 369fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 3709a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (F->isDeclaration()) { 3719a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // Try to get mod/ref behaviour from function attributes. 372d0ac373660de64fe210e50458c7702432b3f9605Duncan Sands if (F->doesNotAccessMemory()) { 373d0ac373660de64fe210e50458c7702432b3f9605Duncan Sands // Can't do better than that! 374d0ac373660de64fe210e50458c7702432b3f9605Duncan Sands } else if (F->onlyReadsMemory()) { 3759a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands FunctionEffect |= Ref; 3762bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands if (!F->isIntrinsic()) 3771abe60b9be1b7b33e1fa422add5296d392831850Duncan Sands // This function might call back into the module and read a global - 3782bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands // consider every global as possibly being read by this function. 3792bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands FR.MayReadAnyGlobal = true; 380d0ac373660de64fe210e50458c7702432b3f9605Duncan Sands } else { 381892b84007c980e58181cd94fea7d70c5ed9642c8Duncan Sands FunctionEffect |= ModRef; 382892b84007c980e58181cd94fea7d70c5ed9642c8Duncan Sands // Can't say anything useful unless it's an intrinsic - they don't 383892b84007c980e58181cd94fea7d70c5ed9642c8Duncan Sands // read or write global variables of the kind considered here. 384892b84007c980e58181cd94fea7d70c5ed9642c8Duncan Sands KnowNothing = !F->isIntrinsic(); 3859a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } 3869a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands continue; 3879a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } 3889a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 3899a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands for (CallGraphNode::iterator CI = SCC[i]->begin(), E = SCC[i]->end(); 390f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands CI != E && !KnowNothing; ++CI) 3919a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (Function *Callee = CI->second->getFunction()) { 3929a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (FunctionRecord *CalleeFR = getFunctionInfo(Callee)) { 3939a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // Propagate function effect up. 3949a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands FunctionEffect |= CalleeFR->FunctionEffect; 3959a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 3969a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // Incorporate callee's effects on globals into our info. 3979a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands for (std::map<GlobalValue*, unsigned>::iterator GI = 3989a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands CalleeFR->GlobalInfo.begin(), E = CalleeFR->GlobalInfo.end(); 3999a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands GI != E; ++GI) 400f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands FR.GlobalInfo[GI->first] |= GI->second; 4012bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands FR.MayReadAnyGlobal |= CalleeFR->MayReadAnyGlobal; 4029a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } else { 4039a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // Can't say anything about it. However, if it is inside our SCC, 4049a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // then nothing needs to be done. 4059a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands CallGraphNode *CalleeNode = CG[Callee]; 4069a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (std::find(SCC.begin(), SCC.end(), CalleeNode) == SCC.end()) 4079a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands KnowNothing = true; 4089a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } 4099a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } else { 4109a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands KnowNothing = true; 4119a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } 4129a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } 4139a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 4149a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // If we can't say anything useful about this SCC, remove all SCC functions 4159a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // from the FunctionInfo map. 4169a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (KnowNothing) { 4179a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands for (unsigned i = 0, e = SCC.size(); i != e; ++i) 4189a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands FunctionInfo.erase(SCC[i]->getFunction()); 419b070beee77cf9a0befd06a4fdacb824b1da0b55aDuncan Sands continue; 4209a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } 4212b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman 4229a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // Scan the function bodies for explicit loads or stores. 423fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner for (unsigned i = 0, e = SCC.size(); i != e && FunctionEffect != ModRef;++i) 424fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner for (inst_iterator II = inst_begin(SCC[i]->getFunction()), 4252b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman E = inst_end(SCC[i]->getFunction()); 426fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner II != E && FunctionEffect != ModRef; ++II) 427b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands if (isa<LoadInst>(*II)) { 428fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FunctionEffect |= Ref; 429b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands if (cast<LoadInst>(*II).isVolatile()) 430b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands // Volatile loads may have side-effects, so mark them as writing 431b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands // memory (for example, a flag inside the processor). 432b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands FunctionEffect |= Mod; 433b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands } else if (isa<StoreInst>(*II)) { 434fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FunctionEffect |= Mod; 435b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands if (cast<StoreInst>(*II).isVolatile()) 436b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands // Treat volatile stores as reading memory somewhere. 437b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands FunctionEffect |= Ref; 438b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands } else if (isa<MallocInst>(*II) || isa<FreeInst>(*II)) { 4393fe4d3cb5bd5ea7948faeed8451b61380d928808Chris Lattner FunctionEffect |= ModRef; 440b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands } 441fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 4429a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if ((FunctionEffect & Mod) == 0) 4439a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands ++NumReadMemFunctions; 4449a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (FunctionEffect == 0) 4459a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands ++NumNoMemFunctions; 446f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands FR.FunctionEffect = FunctionEffect; 447fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 4489a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // Finally, now that we know the full effect on this SCC, clone the 4499a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // information to each function in the SCC. 4509a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands for (unsigned i = 1, e = SCC.size(); i != e; ++i) 451f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands FunctionInfo[SCC[i]->getFunction()] = FR; 4529a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } 4533b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 4543b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 4553b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 4563b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 4573b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// alias - If one of the pointers is to a global that we are tracking, and the 4583b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// other is some random pointer, we know there cannot be an alias, because the 4593b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// address of the global isn't taken. 4603b04a8ac455568f9b98ab7e9a43076260cb737aeChris LattnerAliasAnalysis::AliasResult 4613b04a8ac455568f9b98ab7e9a43076260cb737aeChris LattnerGlobalsModRef::alias(const Value *V1, unsigned V1Size, 4623b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner const Value *V2, unsigned V2Size) { 463ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Get the base object these pointers point to. 4645d0392c6b370758750b397e254a6c6f028479969Duncan Sands Value *UV1 = const_cast<Value*>(V1->getUnderlyingObject()); 4655d0392c6b370758750b397e254a6c6f028479969Duncan Sands Value *UV2 = const_cast<Value*>(V2->getUnderlyingObject()); 4669a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 467ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // If either of the underlying values is a global, they may be non-addr-taken 468ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // globals, which we can answer queries about. 469ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GlobalValue *GV1 = dyn_cast<GlobalValue>(UV1); 470ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GlobalValue *GV2 = dyn_cast<GlobalValue>(UV2); 471ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (GV1 || GV2) { 472ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // If the global's address is taken, pretend we don't know it's a pointer to 473ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // the global. 474ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (GV1 && !NonAddressTakenGlobals.count(GV1)) GV1 = 0; 475ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (GV2 && !NonAddressTakenGlobals.count(GV2)) GV2 = 0; 476ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 477ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // If the the two pointers are derived from two different non-addr-taken 478ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // globals, or if one is and the other isn't, we know these can't alias. 479ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if ((GV1 || GV2) && GV1 != GV2) 480ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return NoAlias; 481ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 482ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Otherwise if they are both derived from the same addr-taken global, we 483ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // can't know the two accesses don't overlap. 484ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 4859a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 486ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // These pointers may be based on the memory owned by an indirect global. If 487ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // so, we may be able to handle this. First check to see if the base pointer 488ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // is a direct load from an indirect global. 489ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GV1 = GV2 = 0; 490ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (LoadInst *LI = dyn_cast<LoadInst>(UV1)) 491ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0))) 492ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (IndirectGlobals.count(GV)) 493ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GV1 = GV; 494ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (LoadInst *LI = dyn_cast<LoadInst>(UV2)) 495ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0))) 496ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (IndirectGlobals.count(GV)) 497ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GV2 = GV; 4989a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 499ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // These pointers may also be from an allocation for the indirect global. If 500ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // so, also handle them. 501ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AllocsForIndirectGlobals.count(UV1)) 502ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GV1 = AllocsForIndirectGlobals[UV1]; 503ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AllocsForIndirectGlobals.count(UV2)) 504ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GV2 = AllocsForIndirectGlobals[UV2]; 5059a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 506ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Now that we know whether the two pointers are related to indirect globals, 507ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // use this to disambiguate the pointers. If either pointer is based on an 508ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // indirect global and if they are not both based on the same indirect global, 509ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // they cannot alias. 5103b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner if ((GV1 || GV2) && GV1 != GV2) 5113b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return NoAlias; 5129a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 5133b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return AliasAnalysis::alias(V1, V1Size, V2, V2Size); 5143b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 5153b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 5163b04a8ac455568f9b98ab7e9a43076260cb737aeChris LattnerAliasAnalysis::ModRefResult 5173b04a8ac455568f9b98ab7e9a43076260cb737aeChris LattnerGlobalsModRef::getModRefInfo(CallSite CS, Value *P, unsigned Size) { 5183b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner unsigned Known = ModRef; 5193b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 5203b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // If we are asking for mod/ref info of a direct call with a pointer to a 521fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner // global we are tracking, return information if we have it. 5225d0392c6b370758750b397e254a6c6f028479969Duncan Sands if (GlobalValue *GV = dyn_cast<GlobalValue>(P->getUnderlyingObject())) 523bb46f52027416598a662dc1c58f48d9d56b1a65bRafael Espindola if (GV->hasLocalLinkage()) 524fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (Function *F = CS.getCalledFunction()) 525fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (NonAddressTakenGlobals.count(GV)) 526fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (FunctionRecord *FR = getFunctionInfo(F)) 527fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner Known = FR->getInfoForGlobal(GV); 5283b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 5293b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner if (Known == NoModRef) 5303b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return NoModRef; // No need to query other mod/ref analyses 5313b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return ModRefResult(Known & AliasAnalysis::getModRefInfo(CS, P, Size)); 5323b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 5333b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 5343b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 5353b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner//===----------------------------------------------------------------------===// 5363b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner// Methods to update the analysis as a result of the client transformation. 5373b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner// 5383b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattnervoid GlobalsModRef::deleteValue(Value *V) { 539ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) { 540ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (NonAddressTakenGlobals.erase(GV)) { 541ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // This global might be an indirect global. If so, remove it and remove 542ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // any AllocRelatedValues for it. 543ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (IndirectGlobals.erase(GV)) { 544ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Remove any entries in AllocsForIndirectGlobals for this global. 545ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner for (std::map<Value*, GlobalValue*>::iterator 546ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner I = AllocsForIndirectGlobals.begin(), 547ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner E = AllocsForIndirectGlobals.end(); I != E; ) { 548ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (I->second == GV) { 549ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner AllocsForIndirectGlobals.erase(I++); 550ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else { 551ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner ++I; 552ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 553ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 554ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 555ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 556ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 5579a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 558ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Otherwise, if this is an allocation related to an indirect global, remove 559ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // it. 560ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner AllocsForIndirectGlobals.erase(V); 5619a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 562cd883f203d23c7e44b12dff62df2e6d65d8f231cChris Lattner AliasAnalysis::deleteValue(V); 5633b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 5643b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 5653b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattnervoid GlobalsModRef::copyValue(Value *From, Value *To) { 566cd883f203d23c7e44b12dff62df2e6d65d8f231cChris Lattner AliasAnalysis::copyValue(From, To); 5673b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 568