GlobalsModRef.cpp revision 1cee94f04111cfd7114979d6dfddce2669c9380d
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 52fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner unsigned getInfoForGlobal(GlobalValue *GV) const { 53fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner std::map<GlobalValue*, unsigned>::const_iterator I = GlobalInfo.find(GV); 54fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (I != GlobalInfo.end()) 55fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner return I->second; 56fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner return 0; 57fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner } 582b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman 59fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// FunctionEffect - Capture whether or not this function reads or writes to 60fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// ANY memory. If not, we can do a lot of aggressive analysis on it. 61fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner unsigned FunctionEffect; 62105d26acb4158daea4e54919cfd12545a3d901eaChris Lattner 63105d26acb4158daea4e54919cfd12545a3d901eaChris Lattner FunctionRecord() : FunctionEffect(0) {} 64fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner }; 653b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 66fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// GlobalsModRef - The actual analysis pass. 67d7d83db5f22d05e5b14b6b1d838668222113c83aReid Spencer class VISIBILITY_HIDDEN GlobalsModRef 68d7d83db5f22d05e5b14b6b1d838668222113c83aReid Spencer : public ModulePass, public AliasAnalysis { 69fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// NonAddressTakenGlobals - The globals that do not have their addresses 70fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// taken. 71fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner std::set<GlobalValue*> NonAddressTakenGlobals; 723b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 73ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner /// IndirectGlobals - The memory pointed to by this global is known to be 74ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner /// 'owned' by the global. 75ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::set<GlobalValue*> IndirectGlobals; 76ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 77ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner /// AllocsForIndirectGlobals - If an instruction allocates memory for an 78ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner /// indirect global, this map indicates which one. 79ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::map<Value*, GlobalValue*> AllocsForIndirectGlobals; 80ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 813b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner /// FunctionInfo - For each function, keep track of what globals are 823b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner /// modified or read. 83fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner std::map<Function*, FunctionRecord> FunctionInfo; 843b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 853b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner public: 861997473cf72957d0e70322e2fe6fe2ab141c58a6Devang Patel static char ID; 87794fd75c67a2cdc128d67342c6d88a504d186896Devang Patel GlobalsModRef() : ModulePass((intptr_t)&ID) {} 88794fd75c67a2cdc128d67342c6d88a504d186896Devang Patel 891cee94f04111cfd7114979d6dfddce2669c9380dDevang Patel /// isAnalysis - Return true if this pass is implementing an analysis pass. 901cee94f04111cfd7114979d6dfddce2669c9380dDevang Patel virtual bool isAnalysis() const { return true; } 911cee94f04111cfd7114979d6dfddce2669c9380dDevang Patel 92b12914bfc0f76a7a48357162d5f4c39a1343e69bChris Lattner bool runOnModule(Module &M) { 933b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner InitializeAliasAnalysis(this); // set up super class 943b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner AnalyzeGlobals(M); // find non-addr taken globals 953b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner AnalyzeCallGraph(getAnalysis<CallGraph>(), M); // Propagate on CG 963b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return false; 973b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 983b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 993b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner virtual void getAnalysisUsage(AnalysisUsage &AU) const { 1003b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner AliasAnalysis::getAnalysisUsage(AU); 1013b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner AU.addRequired<CallGraph>(); 1023b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner AU.setPreservesAll(); // Does not transform code 1033b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 1043b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 1053b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner //------------------------------------------------ 1063b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // Implement the AliasAnalysis API 1072b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman // 1083b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner AliasResult alias(const Value *V1, unsigned V1Size, 1093b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner const Value *V2, unsigned V2Size); 1103b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size); 1114a7ebfa4111305ea22fc753d4f029eed88149662Reid Spencer ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) { 1124a7ebfa4111305ea22fc753d4f029eed88149662Reid Spencer return AliasAnalysis::getModRefInfo(CS1,CS2); 1134a7ebfa4111305ea22fc753d4f029eed88149662Reid Spencer } 1143b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner bool hasNoModRefInfoForCalls() const { return false; } 1153b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 1160af024c5d00c2a2d0e35ba33f4aaf4ed3fadfae2Chris Lattner /// getModRefBehavior - Return the behavior of the specified function if 1170af024c5d00c2a2d0e35ba33f4aaf4ed3fadfae2Chris Lattner /// called from the specified call site. The call site may be null in which 1180af024c5d00c2a2d0e35ba33f4aaf4ed3fadfae2Chris Lattner /// case the most generic behavior of this function should be returned. 11941925f87d3e7fc9eb2b583267b99012dcb2774a0Chris Lattner virtual ModRefBehavior getModRefBehavior(Function *F, CallSite CS, 12041925f87d3e7fc9eb2b583267b99012dcb2774a0Chris Lattner std::vector<PointerAccessInfo> *Info) { 121ae9f3a3b7c915f725aef5a7250e88eaeddda03c6Anton Korobeynikov if (FunctionRecord *FR = getFunctionInfo(F)) { 122fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (FR->FunctionEffect == 0) 1230af024c5d00c2a2d0e35ba33f4aaf4ed3fadfae2Chris Lattner return DoesNotAccessMemory; 124dedf2bd5a34dac25e4245f58bb902ced6b64edd9Misha Brukman else if ((FR->FunctionEffect & Mod) == 0) 125dedf2bd5a34dac25e4245f58bb902ced6b64edd9Misha Brukman return OnlyReadsMemory; 126ae9f3a3b7c915f725aef5a7250e88eaeddda03c6Anton Korobeynikov } 1272b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman return AliasAnalysis::getModRefBehavior(F, CS, Info); 128fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner } 129fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 1303b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner virtual void deleteValue(Value *V); 1313b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner virtual void copyValue(Value *From, Value *To); 1323b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 1333b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner private: 134fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// getFunctionInfo - Return the function info for the function, or null if 135fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// the function calls an external function (in which case we don't have 136fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// anything useful to say about it). 137fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FunctionRecord *getFunctionInfo(Function *F) { 138fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner std::map<Function*, FunctionRecord>::iterator I = FunctionInfo.find(F); 139fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (I != FunctionInfo.end()) 140fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner return &I->second; 141fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner return 0; 142fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner } 143fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 1443b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner void AnalyzeGlobals(Module &M); 1453b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner void AnalyzeCallGraph(CallGraph &CG, Module &M); 146fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner void AnalyzeSCC(std::vector<CallGraphNode *> &SCC); 147ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner bool AnalyzeUsesOfPointer(Value *V, std::vector<Function*> &Readers, 148ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Function*> &Writers, 149ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GlobalValue *OkayStoreDest = 0); 150ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner bool AnalyzeIndirectGlobalMemory(GlobalValue *GV); 1513b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner }; 1522b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman 1531997473cf72957d0e70322e2fe6fe2ab141c58a6Devang Patel char GlobalsModRef::ID = 0; 1547f8897f22e88271cfa114998a4d6088e7c8e8e11Chris Lattner RegisterPass<GlobalsModRef> X("globalsmodref-aa", 1557f8897f22e88271cfa114998a4d6088e7c8e8e11Chris Lattner "Simple mod/ref analysis for globals"); 156a5370172b64bed5daf8e2869d7bf7cb52f80d6b7Chris Lattner RegisterAnalysisGroup<AliasAnalysis> Y(X); 1573b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 1583b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 1593b04a8ac455568f9b98ab7e9a43076260cb737aeChris LattnerPass *llvm::createGlobalsModRefPass() { return new GlobalsModRef(); } 1603b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 161ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// getUnderlyingObject - This traverses the use chain to figure out what object 162ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// the specified value points to. If the value points to, or is derived from, 163ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// a global object, return it. 164ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattnerstatic Value *getUnderlyingObject(Value *V) { 165ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (!isa<PointerType>(V->getType())) return V; 166ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 167ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // If we are at some type of object... return it. 168ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) return GV; 169ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 170ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Traverse through different addressing mechanisms. 171ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (Instruction *I = dyn_cast<Instruction>(V)) { 1723da59db637a887474c1b1346c1f3ccf53b6c4663Reid Spencer if (isa<BitCastInst>(I) || isa<GetElementPtrInst>(I)) 173ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return getUnderlyingObject(I->getOperand(0)); 174ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) { 1753da59db637a887474c1b1346c1f3ccf53b6c4663Reid Spencer if (CE->getOpcode() == Instruction::BitCast || 176ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner CE->getOpcode() == Instruction::GetElementPtr) 177ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return getUnderlyingObject(CE->getOperand(0)); 178ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 179ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 180ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Othewise, we don't know what this is, return it as the base pointer. 181ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return V; 182ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner} 1833b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 184ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// AnalyzeGlobals - Scan through the users of all of the internal 1853b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// GlobalValue's in the program. If none of them have their "Address taken" 1863b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// (really, their address passed to something nontrivial), record this fact, 1873b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// and record the functions that they are used directly in. 1883b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattnervoid GlobalsModRef::AnalyzeGlobals(Module &M) { 1893b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner std::vector<Function*> Readers, Writers; 1903b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) 1913b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner if (I->hasInternalLinkage()) { 192ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (!AnalyzeUsesOfPointer(I, Readers, Writers)) { 193fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner // Remember that we are tracking this global. 194fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner NonAddressTakenGlobals.insert(I); 1953b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner ++NumNonAddrTakenFunctions; 1963b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 1973b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner Readers.clear(); Writers.clear(); 1983b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 1993b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 200f5eaf3c62c7b2f2da1f85ac411c4f13bcbf131f1Chris Lattner for (Module::global_iterator I = M.global_begin(), E = M.global_end(); 201f5eaf3c62c7b2f2da1f85ac411c4f13bcbf131f1Chris Lattner I != E; ++I) 2023b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner if (I->hasInternalLinkage()) { 203ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (!AnalyzeUsesOfPointer(I, Readers, Writers)) { 2043b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // Remember that we are tracking this global, and the mod/ref fns 205fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner NonAddressTakenGlobals.insert(I); 206fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner for (unsigned i = 0, e = Readers.size(); i != e; ++i) 207fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FunctionInfo[Readers[i]].GlobalInfo[I] |= Ref; 208fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 209fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (!I->isConstant()) // No need to keep track of writers to constants 210fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner for (unsigned i = 0, e = Writers.size(); i != e; ++i) 211fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FunctionInfo[Writers[i]].GlobalInfo[I] |= Mod; 2123b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner ++NumNonAddrTakenGlobalVars; 213ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 214ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // If this global holds a pointer type, see if it is an indirect global. 215ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (isa<PointerType>(I->getType()->getElementType()) && 216ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner AnalyzeIndirectGlobalMemory(I)) 217ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner ++NumIndirectGlobalVars; 2183b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 2193b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner Readers.clear(); Writers.clear(); 2203b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 2213b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 2223b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 223ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// AnalyzeUsesOfPointer - Look at all of the users of the specified pointer. 224ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// If this is used by anything complex (i.e., the address escapes), return 225ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// true. Also, while we are at it, keep track of those functions that read and 226ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// write to the value. 227ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// 228ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// If OkayStoreDest is non-null, stores into this global are allowed. 229ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattnerbool GlobalsModRef::AnalyzeUsesOfPointer(Value *V, 230ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Function*> &Readers, 231ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Function*> &Writers, 232ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GlobalValue *OkayStoreDest) { 233fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (!isa<PointerType>(V->getType())) return true; 2343b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 2353b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI) 2363b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) { 2373b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner Readers.push_back(LI->getParent()->getParent()); 2383b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } else if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) { 239ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (V == SI->getOperand(1)) { 240ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner Writers.push_back(SI->getParent()->getParent()); 241ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else if (SI->getOperand(1) != OkayStoreDest) { 242ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return true; // Storing the pointer 243ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 2443b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(*UI)) { 245ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AnalyzeUsesOfPointer(GEP, Readers, Writers)) return true; 2463b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } else if (CallInst *CI = dyn_cast<CallInst>(*UI)) { 2473b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // Make sure that this is just the function being called, not that it is 2483b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // passing into the function. 2493b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner for (unsigned i = 1, e = CI->getNumOperands(); i != e; ++i) 2503b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner if (CI->getOperand(i) == V) return true; 2513b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } else if (InvokeInst *II = dyn_cast<InvokeInst>(*UI)) { 2523b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // Make sure that this is just the function being called, not that it is 2533b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // passing into the function. 2543b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner for (unsigned i = 3, e = II->getNumOperands(); i != e; ++i) 2553b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner if (II->getOperand(i) == V) return true; 2563b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(*UI)) { 2573da59db637a887474c1b1346c1f3ccf53b6c4663Reid Spencer if (CE->getOpcode() == Instruction::GetElementPtr || 2583da59db637a887474c1b1346c1f3ccf53b6c4663Reid Spencer CE->getOpcode() == Instruction::BitCast) { 259ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AnalyzeUsesOfPointer(CE, Readers, Writers)) 2603b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return true; 2613b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } else { 2623b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return true; 2632b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman } 264e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer } else if (ICmpInst *ICI = dyn_cast<ICmpInst>(*UI)) { 265e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer if (!isa<ConstantPointerNull>(ICI->getOperand(1))) 266ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return true; // Allow comparison against null. 267ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else if (FreeInst *F = dyn_cast<FreeInst>(*UI)) { 268ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner Writers.push_back(F->getParent()->getParent()); 2693b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } else { 2703b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return true; 2713b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 2723b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return false; 2733b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 2743b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 275ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// AnalyzeIndirectGlobalMemory - We found an non-address-taken global variable 276ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// which holds a pointer type. See if the global always points to non-aliased 277ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// heap memory: that is, all initializers of the globals are allocations, and 278ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// those allocations have no use other than initialization of the global. 279ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// Further, all loads out of GV must directly use the memory, not store the 280ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// pointer somewhere. If this is true, we consider the memory pointed to by 281ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// GV to be owned by GV and can disambiguate other pointers from it. 282ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattnerbool GlobalsModRef::AnalyzeIndirectGlobalMemory(GlobalValue *GV) { 283ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Keep track of values related to the allocation of the memory, f.e. the 284ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // value produced by the malloc call and any casts. 285ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Value*> AllocRelatedValues; 286ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 287ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Walk the user list of the global. If we find anything other than a direct 288ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // load or store, bail out. 289ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner for (Value::use_iterator I = GV->use_begin(), E = GV->use_end(); I != E; ++I){ 290ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (LoadInst *LI = dyn_cast<LoadInst>(*I)) { 291ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // The pointer loaded from the global can only be used in simple ways: 292ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // we allow addressing of it and loading storing to it. We do *not* allow 293ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // storing the loaded pointer somewhere else or passing to a function. 294ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Function*> ReadersWriters; 295ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AnalyzeUsesOfPointer(LI, ReadersWriters, ReadersWriters)) 296ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return false; // Loaded pointer escapes. 297ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // TODO: Could try some IP mod/ref of the loaded pointer. 298ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else if (StoreInst *SI = dyn_cast<StoreInst>(*I)) { 299ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Storing the global itself. 300ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (SI->getOperand(0) == GV) return false; 301ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 302ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // If storing the null pointer, ignore it. 303ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (isa<ConstantPointerNull>(SI->getOperand(0))) 304ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner continue; 305ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 306ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Check the value being stored. 307ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner Value *Ptr = getUnderlyingObject(SI->getOperand(0)); 308ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 309ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (isa<MallocInst>(Ptr)) { 310ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Okay, easy case. 311ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else if (CallInst *CI = dyn_cast<CallInst>(Ptr)) { 312ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner Function *F = CI->getCalledFunction(); 3135cbf985dcbc89fba3208e7baf8b6f488b06d3ec9Reid Spencer if (!F || !F->isDeclaration()) return false; // Too hard to analyze. 314ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (F->getName() != "calloc") return false; // Not calloc. 315ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else { 316ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return false; // Too hard to analyze. 317ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 318ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 319ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Analyze all uses of the allocation. If any of them are used in a 320ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // non-simple way (e.g. stored to another global) bail out. 321ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Function*> ReadersWriters; 322ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AnalyzeUsesOfPointer(Ptr, ReadersWriters, ReadersWriters, GV)) 323ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return false; // Loaded pointer escapes. 324ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 325ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Remember that this allocation is related to the indirect global. 326ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner AllocRelatedValues.push_back(Ptr); 327ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else { 328ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Something complex, bail out. 329ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return false; 330ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 331ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 332ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 333ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Okay, this is an indirect global. Remember all of the allocations for 334ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // this global in AllocsForIndirectGlobals. 335ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner while (!AllocRelatedValues.empty()) { 336ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner AllocsForIndirectGlobals[AllocRelatedValues.back()] = GV; 337ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner AllocRelatedValues.pop_back(); 338ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 339ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner IndirectGlobals.insert(GV); 340ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return true; 341ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner} 342ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 3433b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// AnalyzeCallGraph - At this point, we know the functions where globals are 3443b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// immediately stored to and read from. Propagate this information up the call 345fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner/// graph to all callers and compute the mod/ref info for all memory for each 3462b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman/// function. 3473b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattnervoid GlobalsModRef::AnalyzeCallGraph(CallGraph &CG, Module &M) { 3483b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // We do a bottom-up SCC traversal of the call graph. In other words, we 3493b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // visit all callees before callers (leaf-first). 350fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner for (scc_iterator<CallGraph*> I = scc_begin(&CG), E = scc_end(&CG); I!=E; ++I) 351105d26acb4158daea4e54919cfd12545a3d901eaChris Lattner if ((*I).size() != 1) { 352fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner AnalyzeSCC(*I); 353105d26acb4158daea4e54919cfd12545a3d901eaChris Lattner } else if (Function *F = (*I)[0]->getFunction()) { 3545cbf985dcbc89fba3208e7baf8b6f488b06d3ec9Reid Spencer if (!F->isDeclaration()) { 355105d26acb4158daea4e54919cfd12545a3d901eaChris Lattner // Nonexternal function. 356105d26acb4158daea4e54919cfd12545a3d901eaChris Lattner AnalyzeSCC(*I); 357105d26acb4158daea4e54919cfd12545a3d901eaChris Lattner } else { 358105d26acb4158daea4e54919cfd12545a3d901eaChris Lattner // Otherwise external function. Handle intrinsics and other special 359105d26acb4158daea4e54919cfd12545a3d901eaChris Lattner // cases here. 360105d26acb4158daea4e54919cfd12545a3d901eaChris Lattner if (getAnalysis<AliasAnalysis>().doesNotAccessMemory(F)) 361105d26acb4158daea4e54919cfd12545a3d901eaChris Lattner // If it does not access memory, process the function, causing us to 362105d26acb4158daea4e54919cfd12545a3d901eaChris Lattner // realize it doesn't do anything (the body is empty). 363105d26acb4158daea4e54919cfd12545a3d901eaChris Lattner AnalyzeSCC(*I); 364105d26acb4158daea4e54919cfd12545a3d901eaChris Lattner else { 365105d26acb4158daea4e54919cfd12545a3d901eaChris Lattner // Otherwise, don't process it. This will cause us to conservatively 366105d26acb4158daea4e54919cfd12545a3d901eaChris Lattner // assume the worst. 367105d26acb4158daea4e54919cfd12545a3d901eaChris Lattner } 368105d26acb4158daea4e54919cfd12545a3d901eaChris Lattner } 369105d26acb4158daea4e54919cfd12545a3d901eaChris Lattner } else { 370105d26acb4158daea4e54919cfd12545a3d901eaChris Lattner // Do not process the external node, assume the worst. 371105d26acb4158daea4e54919cfd12545a3d901eaChris Lattner } 372fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner} 373fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 374fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattnervoid GlobalsModRef::AnalyzeSCC(std::vector<CallGraphNode *> &SCC) { 375fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner assert(!SCC.empty() && "SCC with no functions?"); 376fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FunctionRecord &FR = FunctionInfo[SCC[0]->getFunction()]; 377fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 378fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner bool CallsExternal = false; 379fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner unsigned FunctionEffect = 0; 380fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 381fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner // Collect the mod/ref properties due to called functions. We only compute 382fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner // one mod-ref set 383fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner for (unsigned i = 0, e = SCC.size(); i != e && !CallsExternal; ++i) 384fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner for (CallGraphNode::iterator CI = SCC[i]->begin(), E = SCC[i]->end(); 385fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner CI != E; ++CI) 386d85340f4ec587e22b0239617f3b747a6df113894Chris Lattner if (Function *Callee = CI->second->getFunction()) { 387fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (FunctionRecord *CalleeFR = getFunctionInfo(Callee)) { 388fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner // Propagate function effect up. 389fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FunctionEffect |= CalleeFR->FunctionEffect; 390fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 391fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner // Incorporate callee's effects on globals into our info. 392fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner for (std::map<GlobalValue*, unsigned>::iterator GI = 393fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner CalleeFR->GlobalInfo.begin(), E = CalleeFR->GlobalInfo.end(); 394fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner GI != E; ++GI) 395fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FR.GlobalInfo[GI->first] |= GI->second; 3963b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 3973b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } else { 398ec6518ddc2baa110ffdadc9ba8625ae968f746beChris Lattner // Okay, if we can't say anything about it, maybe some other alias 399ec6518ddc2baa110ffdadc9ba8625ae968f746beChris Lattner // analysis can. 400ec6518ddc2baa110ffdadc9ba8625ae968f746beChris Lattner ModRefBehavior MRB = 401dff6710717b159f089c76a07eda074eb6347eb92Duncan Sands AliasAnalysis::getModRefBehavior(Callee); 402ec6518ddc2baa110ffdadc9ba8625ae968f746beChris Lattner if (MRB != DoesNotAccessMemory) { 40362da315c859eb20e0ad38c034f71901ac6558d4dChris Lattner // FIXME: could make this more aggressive for functions that just 40462da315c859eb20e0ad38c034f71901ac6558d4dChris Lattner // read memory. We should just say they read all globals. 40562da315c859eb20e0ad38c034f71901ac6558d4dChris Lattner CallsExternal = true; 40662da315c859eb20e0ad38c034f71901ac6558d4dChris Lattner break; 407ec6518ddc2baa110ffdadc9ba8625ae968f746beChris Lattner } 4083b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 409fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner } else { 410fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner CallsExternal = true; 411fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner break; 4123b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 413fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 414fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner // If this SCC calls an external function, we can't say anything about it, so 415fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner // remove all SCC functions from the FunctionInfo map. 416fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (CallsExternal) { 4173b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner for (unsigned i = 0, e = SCC.size(); i != e; ++i) 418fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FunctionInfo.erase(SCC[i]->getFunction()); 419fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner return; 4203b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 4212b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman 422fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner // Otherwise, unless we already know that this function mod/refs memory, scan 423fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner // the function bodies to see if there are any explicit loads or stores. 424fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (FunctionEffect != ModRef) { 425fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner for (unsigned i = 0, e = SCC.size(); i != e && FunctionEffect != ModRef;++i) 426fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner for (inst_iterator II = inst_begin(SCC[i]->getFunction()), 4272b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman E = inst_end(SCC[i]->getFunction()); 428fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner II != E && FunctionEffect != ModRef; ++II) 429fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (isa<LoadInst>(*II)) 430fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FunctionEffect |= Ref; 431fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner else if (isa<StoreInst>(*II)) 432fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FunctionEffect |= Mod; 4333fe4d3cb5bd5ea7948faeed8451b61380d928808Chris Lattner else if (isa<MallocInst>(*II) || isa<FreeInst>(*II)) 4343fe4d3cb5bd5ea7948faeed8451b61380d928808Chris Lattner FunctionEffect |= ModRef; 435fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner } 436fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 437fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if ((FunctionEffect & Mod) == 0) 438fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner ++NumReadMemFunctions; 439fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (FunctionEffect == 0) 440fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner ++NumNoMemFunctions; 441fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FR.FunctionEffect = FunctionEffect; 442fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 443fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner // Finally, now that we know the full effect on this SCC, clone the 444fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner // information to each function in the SCC. 445fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner for (unsigned i = 1, e = SCC.size(); i != e; ++i) 446fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FunctionInfo[SCC[i]->getFunction()] = FR; 4473b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 4483b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 4493b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 4503b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 4513b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// alias - If one of the pointers is to a global that we are tracking, and the 4523b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// other is some random pointer, we know there cannot be an alias, because the 4533b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// address of the global isn't taken. 4543b04a8ac455568f9b98ab7e9a43076260cb737aeChris LattnerAliasAnalysis::AliasResult 4553b04a8ac455568f9b98ab7e9a43076260cb737aeChris LattnerGlobalsModRef::alias(const Value *V1, unsigned V1Size, 4563b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner const Value *V2, unsigned V2Size) { 457ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Get the base object these pointers point to. 458ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner Value *UV1 = getUnderlyingObject(const_cast<Value*>(V1)); 459ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner Value *UV2 = getUnderlyingObject(const_cast<Value*>(V2)); 460ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 461ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // If either of the underlying values is a global, they may be non-addr-taken 462ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // globals, which we can answer queries about. 463ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GlobalValue *GV1 = dyn_cast<GlobalValue>(UV1); 464ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GlobalValue *GV2 = dyn_cast<GlobalValue>(UV2); 465ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (GV1 || GV2) { 466ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // If the global's address is taken, pretend we don't know it's a pointer to 467ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // the global. 468ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (GV1 && !NonAddressTakenGlobals.count(GV1)) GV1 = 0; 469ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (GV2 && !NonAddressTakenGlobals.count(GV2)) GV2 = 0; 470ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 471ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // If the the two pointers are derived from two different non-addr-taken 472ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // globals, or if one is and the other isn't, we know these can't alias. 473ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if ((GV1 || GV2) && GV1 != GV2) 474ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return NoAlias; 475ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 476ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Otherwise if they are both derived from the same addr-taken global, we 477ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // can't know the two accesses don't overlap. 478ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 479ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 480ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // These pointers may be based on the memory owned by an indirect global. If 481ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // so, we may be able to handle this. First check to see if the base pointer 482ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // is a direct load from an indirect global. 483ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GV1 = GV2 = 0; 484ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (LoadInst *LI = dyn_cast<LoadInst>(UV1)) 485ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0))) 486ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (IndirectGlobals.count(GV)) 487ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GV1 = GV; 488ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (LoadInst *LI = dyn_cast<LoadInst>(UV2)) 489ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0))) 490ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (IndirectGlobals.count(GV)) 491ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GV2 = GV; 492ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 493ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // These pointers may also be from an allocation for the indirect global. If 494ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // so, also handle them. 495ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AllocsForIndirectGlobals.count(UV1)) 496ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GV1 = AllocsForIndirectGlobals[UV1]; 497ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AllocsForIndirectGlobals.count(UV2)) 498ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GV2 = AllocsForIndirectGlobals[UV2]; 499ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 500ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Now that we know whether the two pointers are related to indirect globals, 501ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // use this to disambiguate the pointers. If either pointer is based on an 502ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // indirect global and if they are not both based on the same indirect global, 503ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // they cannot alias. 5043b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner if ((GV1 || GV2) && GV1 != GV2) 5053b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return NoAlias; 506ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 5073b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return AliasAnalysis::alias(V1, V1Size, V2, V2Size); 5083b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 5093b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 5103b04a8ac455568f9b98ab7e9a43076260cb737aeChris LattnerAliasAnalysis::ModRefResult 5113b04a8ac455568f9b98ab7e9a43076260cb737aeChris LattnerGlobalsModRef::getModRefInfo(CallSite CS, Value *P, unsigned Size) { 5123b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner unsigned Known = ModRef; 5133b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 5143b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // If we are asking for mod/ref info of a direct call with a pointer to a 515fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner // global we are tracking, return information if we have it. 516ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (GlobalValue *GV = dyn_cast<GlobalValue>(getUnderlyingObject(P))) 5173b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner if (GV->hasInternalLinkage()) 518fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (Function *F = CS.getCalledFunction()) 519fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (NonAddressTakenGlobals.count(GV)) 520fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (FunctionRecord *FR = getFunctionInfo(F)) 521fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner Known = FR->getInfoForGlobal(GV); 5223b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 5233b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner if (Known == NoModRef) 5243b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return NoModRef; // No need to query other mod/ref analyses 5253b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return ModRefResult(Known & AliasAnalysis::getModRefInfo(CS, P, Size)); 5263b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 5273b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 5283b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 5293b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner//===----------------------------------------------------------------------===// 5303b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner// Methods to update the analysis as a result of the client transformation. 5313b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner// 5323b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattnervoid GlobalsModRef::deleteValue(Value *V) { 533ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) { 534ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (NonAddressTakenGlobals.erase(GV)) { 535ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // This global might be an indirect global. If so, remove it and remove 536ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // any AllocRelatedValues for it. 537ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (IndirectGlobals.erase(GV)) { 538ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Remove any entries in AllocsForIndirectGlobals for this global. 539ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner for (std::map<Value*, GlobalValue*>::iterator 540ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner I = AllocsForIndirectGlobals.begin(), 541ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner E = AllocsForIndirectGlobals.end(); I != E; ) { 542ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (I->second == GV) { 543ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner AllocsForIndirectGlobals.erase(I++); 544ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else { 545ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner ++I; 546ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 547ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 548ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 549ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 550ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 551ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 552ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Otherwise, if this is an allocation related to an indirect global, remove 553ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // it. 554ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner AllocsForIndirectGlobals.erase(V); 555cd883f203d23c7e44b12dff62df2e6d65d8f231cChris Lattner 556cd883f203d23c7e44b12dff62df2e6d65d8f231cChris Lattner AliasAnalysis::deleteValue(V); 5573b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 5583b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 5593b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattnervoid GlobalsModRef::copyValue(Value *From, Value *To) { 560cd883f203d23c7e44b12dff62df2e6d65d8f231cChris Lattner AliasAnalysis::copyValue(From, To); 5613b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 562