GlobalsModRef.cpp revision ce665bd2e2b581ab0858d1afe359192bac96b868
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" 26f006b183e2d2bebcf6968d1dd7350397c95b0325Victor Hernandez#include "llvm/Analysis/MemoryBuiltins.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. 466726b6d75a8b679068a58cb954ba97cf9d1690baNick Lewycky struct 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. 5079fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman std::map<const GlobalValue*, unsigned> GlobalInfo; 51fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 522bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands /// MayReadAnyGlobal - May read global variables, but it is not known which. 532bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands bool MayReadAnyGlobal; 542bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands 5579fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman unsigned getInfoForGlobal(const GlobalValue *GV) const { 562bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands unsigned Effect = MayReadAnyGlobal ? AliasAnalysis::Ref : 0; 5779fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman std::map<const GlobalValue*, unsigned>::const_iterator I = 5879fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman GlobalInfo.find(GV); 59fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (I != GlobalInfo.end()) 602bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands Effect |= I->second; 612bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands return Effect; 62fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner } 632b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman 64fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// FunctionEffect - Capture whether or not this function reads or writes to 65fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// ANY memory. If not, we can do a lot of aggressive analysis on it. 66fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner unsigned FunctionEffect; 67105d26acb4158daea4e54919cfd12545a3d901eaChris Lattner 682bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands FunctionRecord() : MayReadAnyGlobal (false), FunctionEffect(0) {} 69fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner }; 703b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 71fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// GlobalsModRef - The actual analysis pass. 726726b6d75a8b679068a58cb954ba97cf9d1690baNick Lewycky class GlobalsModRef : public ModulePass, public AliasAnalysis { 73fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// NonAddressTakenGlobals - The globals that do not have their addresses 74fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// taken. 7579fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman std::set<const GlobalValue*> NonAddressTakenGlobals; 763b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 77ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner /// IndirectGlobals - The memory pointed to by this global is known to be 78ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner /// 'owned' by the global. 7979fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman std::set<const GlobalValue*> IndirectGlobals; 809a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 81ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner /// AllocsForIndirectGlobals - If an instruction allocates memory for an 82ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner /// indirect global, this map indicates which one. 8379fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman std::map<const Value*, const GlobalValue*> AllocsForIndirectGlobals; 849a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 853b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner /// FunctionInfo - For each function, keep track of what globals are 863b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner /// modified or read. 8779fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman std::map<const Function*, FunctionRecord> FunctionInfo; 883b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 893b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner public: 901997473cf72957d0e70322e2fe6fe2ab141c58a6Devang Patel static char ID; 9190c579de5a383cee278acc3f7e7b9d0a656e6a35Owen Anderson 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 // 109b2143b6247901ae4eca2192ee134564c4f5f7853Dan Gohman AliasResult alias(const Location &LocA, const Location &LocB); 11079fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman ModRefResult getModRefInfo(ImmutableCallSite CS, 111b2143b6247901ae4eca2192ee134564c4f5f7853Dan Gohman const Location &Loc); 11279fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman ModRefResult getModRefInfo(ImmutableCallSite CS1, 11379fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman ImmutableCallSite CS2) { 11479fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman return AliasAnalysis::getModRefInfo(CS1, CS2); 1154a7ebfa4111305ea22fc753d4f029eed88149662Reid Spencer } 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. 120a41af344c2964573318a77e2b43eafd4d3804003Dan Gohman ModRefBehavior getModRefBehavior(const Function *F) { 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 } 127a41af344c2964573318a77e2b43eafd4d3804003Dan Gohman return AliasAnalysis::getModRefBehavior(F); 128e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson } 129e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson 130e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson /// getModRefBehavior - Return the behavior of the specified function if 131e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson /// called from the specified call site. The call site may be null in which 132e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson /// case the most generic behavior of this function should be returned. 133a41af344c2964573318a77e2b43eafd4d3804003Dan Gohman ModRefBehavior getModRefBehavior(ImmutableCallSite CS) { 13479fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman const Function* F = CS.getCalledFunction(); 135a41af344c2964573318a77e2b43eafd4d3804003Dan Gohman if (!F) return AliasAnalysis::getModRefBehavior(CS); 136e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson if (FunctionRecord *FR = getFunctionInfo(F)) { 137e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson if (FR->FunctionEffect == 0) 138e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson return DoesNotAccessMemory; 139e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson else if ((FR->FunctionEffect & Mod) == 0) 140e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson return OnlyReadsMemory; 141e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson } 142a41af344c2964573318a77e2b43eafd4d3804003Dan Gohman return AliasAnalysis::getModRefBehavior(CS); 143fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner } 144fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 1453b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner virtual void deleteValue(Value *V); 1463b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner virtual void copyValue(Value *From, Value *To); 1473b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 148fc570e4bff4e08aaf8efa9f90a2cdb5b885f321cChris Lattner /// getAdjustedAnalysisPointer - This method is used when a pass implements 149fc570e4bff4e08aaf8efa9f90a2cdb5b885f321cChris Lattner /// an analysis interface through multiple inheritance. If needed, it 150fc570e4bff4e08aaf8efa9f90a2cdb5b885f321cChris Lattner /// should override this to adjust the this pointer as needed for the 151fc570e4bff4e08aaf8efa9f90a2cdb5b885f321cChris Lattner /// specified pass info. 15290c579de5a383cee278acc3f7e7b9d0a656e6a35Owen Anderson virtual void *getAdjustedAnalysisPointer(AnalysisID PI) { 15390c579de5a383cee278acc3f7e7b9d0a656e6a35Owen Anderson if (PI == &AliasAnalysis::ID) 154fc570e4bff4e08aaf8efa9f90a2cdb5b885f321cChris Lattner return (AliasAnalysis*)this; 155fc570e4bff4e08aaf8efa9f90a2cdb5b885f321cChris Lattner return this; 156fc570e4bff4e08aaf8efa9f90a2cdb5b885f321cChris Lattner } 157fc570e4bff4e08aaf8efa9f90a2cdb5b885f321cChris Lattner 1583b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner private: 159fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// getFunctionInfo - Return the function info for the function, or null if 1609a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands /// we don't have anything useful to say about it. 16179fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman FunctionRecord *getFunctionInfo(const Function *F) { 16279fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman std::map<const Function*, FunctionRecord>::iterator I = 16379fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman FunctionInfo.find(F); 164fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (I != FunctionInfo.end()) 165fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner return &I->second; 166fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner return 0; 167fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner } 168fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 1693b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner void AnalyzeGlobals(Module &M); 1703b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner void AnalyzeCallGraph(CallGraph &CG, Module &M); 171ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner bool AnalyzeUsesOfPointer(Value *V, std::vector<Function*> &Readers, 172ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Function*> &Writers, 173ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GlobalValue *OkayStoreDest = 0); 174ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner bool AnalyzeIndirectGlobalMemory(GlobalValue *GV); 1753b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner }; 1763b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 1773b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 178844731a7f1909f55935e3514c9e713a62d67662eDan Gohmanchar GlobalsModRef::ID = 0; 17902dd53e1c5b941ca5f60fca1b95ebcaf9ccd1dfcOwen AndersonINITIALIZE_AG_PASS(GlobalsModRef, AliasAnalysis, 18002dd53e1c5b941ca5f60fca1b95ebcaf9ccd1dfcOwen Anderson "globalsmodref-aa", "Simple mod/ref analysis for globals", 181ce665bd2e2b581ab0858d1afe359192bac96b868Owen Anderson false, true, false) 182844731a7f1909f55935e3514c9e713a62d67662eDan Gohman 1833b04a8ac455568f9b98ab7e9a43076260cb737aeChris LattnerPass *llvm::createGlobalsModRefPass() { return new GlobalsModRef(); } 1843b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 185ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// AnalyzeGlobals - Scan through the users of all of the internal 1869a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands/// GlobalValue's in the program. If none of them have their "address taken" 1873b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// (really, their address passed to something nontrivial), record this fact, 1883b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// and record the functions that they are used directly in. 1893b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattnervoid GlobalsModRef::AnalyzeGlobals(Module &M) { 1903b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner std::vector<Function*> Readers, Writers; 1913b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) 192bb46f52027416598a662dc1c58f48d9d56b1a65bRafael Espindola if (I->hasLocalLinkage()) { 193ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (!AnalyzeUsesOfPointer(I, Readers, Writers)) { 194fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner // Remember that we are tracking this global. 195fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner NonAddressTakenGlobals.insert(I); 1963b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner ++NumNonAddrTakenFunctions; 1973b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 1983b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner Readers.clear(); Writers.clear(); 1993b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 2003b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 201f5eaf3c62c7b2f2da1f85ac411c4f13bcbf131f1Chris Lattner for (Module::global_iterator I = M.global_begin(), E = M.global_end(); 202f5eaf3c62c7b2f2da1f85ac411c4f13bcbf131f1Chris Lattner I != E; ++I) 203bb46f52027416598a662dc1c58f48d9d56b1a65bRafael Espindola if (I->hasLocalLinkage()) { 204ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (!AnalyzeUsesOfPointer(I, Readers, Writers)) { 2053b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // Remember that we are tracking this global, and the mod/ref fns 206fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner NonAddressTakenGlobals.insert(I); 2079a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 208fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner for (unsigned i = 0, e = Readers.size(); i != e; ++i) 209fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FunctionInfo[Readers[i]].GlobalInfo[I] |= Ref; 210fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 211fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (!I->isConstant()) // No need to keep track of writers to constants 212fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner for (unsigned i = 0, e = Writers.size(); i != e; ++i) 213fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FunctionInfo[Writers[i]].GlobalInfo[I] |= Mod; 2143b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner ++NumNonAddrTakenGlobalVars; 2159a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 216ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // If this global holds a pointer type, see if it is an indirect global. 2171df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (I->getType()->getElementType()->isPointerTy() && 218ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner AnalyzeIndirectGlobalMemory(I)) 219ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner ++NumIndirectGlobalVars; 2203b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 2213b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner Readers.clear(); Writers.clear(); 2223b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 2233b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 2243b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 225ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// AnalyzeUsesOfPointer - Look at all of the users of the specified pointer. 226ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// If this is used by anything complex (i.e., the address escapes), return 227ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// true. Also, while we are at it, keep track of those functions that read and 228ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// write to the value. 229ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// 230ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// If OkayStoreDest is non-null, stores into this global are allowed. 231ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattnerbool GlobalsModRef::AnalyzeUsesOfPointer(Value *V, 232ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Function*> &Readers, 233ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Function*> &Writers, 234ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GlobalValue *OkayStoreDest) { 2351df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (!V->getType()->isPointerTy()) return true; 2363b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 237d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif for (Value::use_iterator UI = V->use_begin(), E=V->use_end(); UI != E; ++UI) { 238d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif User *U = *UI; 239d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif if (LoadInst *LI = dyn_cast<LoadInst>(U)) { 2403b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner Readers.push_back(LI->getParent()->getParent()); 241d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif } else if (StoreInst *SI = dyn_cast<StoreInst>(U)) { 242ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (V == SI->getOperand(1)) { 243ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner Writers.push_back(SI->getParent()->getParent()); 244ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else if (SI->getOperand(1) != OkayStoreDest) { 245ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return true; // Storing the pointer 246ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 247d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(U)) { 248ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AnalyzeUsesOfPointer(GEP, Readers, Writers)) return true; 249d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif } else if (BitCastInst *BCI = dyn_cast<BitCastInst>(U)) { 25046e8312fb733338e9af4db3757a1a8beddeae15aVictor Hernandez if (AnalyzeUsesOfPointer(BCI, Readers, Writers, OkayStoreDest)) 25146e8312fb733338e9af4db3757a1a8beddeae15aVictor Hernandez return true; 252d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif } else if (isFreeCall(U)) { 253d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif Writers.push_back(cast<Instruction>(U)->getParent()->getParent()); 254d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif } else if (CallInst *CI = dyn_cast<CallInst>(U)) { 2553b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // Make sure that this is just the function being called, not that it is 2563b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // passing into the function. 25722a5b298201d62daea3e06718469d8ad017895e1Bill Wendling for (unsigned i = 0, e = CI->getNumArgOperands(); i != e; ++i) 25822a5b298201d62daea3e06718469d8ad017895e1Bill Wendling if (CI->getArgOperand(i) == V) return true; 259d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif } else if (InvokeInst *II = dyn_cast<InvokeInst>(U)) { 2603b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // Make sure that this is just the function being called, not that it is 2613b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // passing into the function. 26222a5b298201d62daea3e06718469d8ad017895e1Bill Wendling for (unsigned i = 0, e = II->getNumArgOperands(); i != e; ++i) 26322a5b298201d62daea3e06718469d8ad017895e1Bill Wendling if (II->getArgOperand(i) == V) return true; 264d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) { 2659a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (CE->getOpcode() == Instruction::GetElementPtr || 2663da59db637a887474c1b1346c1f3ccf53b6c4663Reid Spencer CE->getOpcode() == Instruction::BitCast) { 267ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AnalyzeUsesOfPointer(CE, Readers, Writers)) 2683b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return true; 2693b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } else { 2703b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return true; 2712b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman } 272d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif } else if (ICmpInst *ICI = dyn_cast<ICmpInst>(U)) { 273e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer if (!isa<ConstantPointerNull>(ICI->getOperand(1))) 274ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return true; // Allow comparison against null. 2753b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } else { 2763b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return true; 2773b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 278d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif } 279d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif 2803b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return false; 2813b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 2823b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 283ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// AnalyzeIndirectGlobalMemory - We found an non-address-taken global variable 284ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// which holds a pointer type. See if the global always points to non-aliased 285ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// heap memory: that is, all initializers of the globals are allocations, and 286ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// those allocations have no use other than initialization of the global. 287ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// Further, all loads out of GV must directly use the memory, not store the 288ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// pointer somewhere. If this is true, we consider the memory pointed to by 289ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// GV to be owned by GV and can disambiguate other pointers from it. 290ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattnerbool GlobalsModRef::AnalyzeIndirectGlobalMemory(GlobalValue *GV) { 291ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Keep track of values related to the allocation of the memory, f.e. the 292ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // value produced by the malloc call and any casts. 293ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Value*> AllocRelatedValues; 2949a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 295ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Walk the user list of the global. If we find anything other than a direct 296ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // load or store, bail out. 297ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner for (Value::use_iterator I = GV->use_begin(), E = GV->use_end(); I != E; ++I){ 2988ba992ad527e50060083e83433b7125bbaa6b737Gabor Greif User *U = *I; 2998ba992ad527e50060083e83433b7125bbaa6b737Gabor Greif if (LoadInst *LI = dyn_cast<LoadInst>(U)) { 300ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // The pointer loaded from the global can only be used in simple ways: 301ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // we allow addressing of it and loading storing to it. We do *not* allow 302ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // storing the loaded pointer somewhere else or passing to a function. 303ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Function*> ReadersWriters; 304ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AnalyzeUsesOfPointer(LI, ReadersWriters, ReadersWriters)) 305ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return false; // Loaded pointer escapes. 306ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // TODO: Could try some IP mod/ref of the loaded pointer. 3078ba992ad527e50060083e83433b7125bbaa6b737Gabor Greif } else if (StoreInst *SI = dyn_cast<StoreInst>(U)) { 308ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Storing the global itself. 309ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (SI->getOperand(0) == GV) return false; 3109a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 311ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // If storing the null pointer, ignore it. 312ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (isa<ConstantPointerNull>(SI->getOperand(0))) 313ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner continue; 3149a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 315ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Check the value being stored. 3165d0392c6b370758750b397e254a6c6f028479969Duncan Sands Value *Ptr = SI->getOperand(0)->getUnderlyingObject(); 317ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 318a276c603b82a11b0bf0b59f0517a69e4b63adeabVictor Hernandez if (isMalloc(Ptr)) { 319ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Okay, easy case. 320ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else if (CallInst *CI = dyn_cast<CallInst>(Ptr)) { 321ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner Function *F = CI->getCalledFunction(); 3225cbf985dcbc89fba3208e7baf8b6f488b06d3ec9Reid Spencer if (!F || !F->isDeclaration()) return false; // Too hard to analyze. 323ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (F->getName() != "calloc") return false; // Not calloc. 324ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else { 325ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return false; // Too hard to analyze. 326ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 3279a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 328ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Analyze all uses of the allocation. If any of them are used in a 329ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // non-simple way (e.g. stored to another global) bail out. 330ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Function*> ReadersWriters; 331ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AnalyzeUsesOfPointer(Ptr, ReadersWriters, ReadersWriters, GV)) 332ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return false; // Loaded pointer escapes. 333ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 334ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Remember that this allocation is related to the indirect global. 335ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner AllocRelatedValues.push_back(Ptr); 336ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else { 337ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Something complex, bail out. 338ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return false; 339ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 340ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 3419a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 342ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Okay, this is an indirect global. Remember all of the allocations for 343ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // this global in AllocsForIndirectGlobals. 344ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner while (!AllocRelatedValues.empty()) { 345ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner AllocsForIndirectGlobals[AllocRelatedValues.back()] = GV; 346ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner AllocRelatedValues.pop_back(); 347ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 348ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner IndirectGlobals.insert(GV); 349ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return true; 350ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner} 351ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 3523b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// AnalyzeCallGraph - At this point, we know the functions where globals are 3533b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// immediately stored to and read from. Propagate this information up the call 354fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner/// graph to all callers and compute the mod/ref info for all memory for each 3552b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman/// function. 3563b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattnervoid GlobalsModRef::AnalyzeCallGraph(CallGraph &CG, Module &M) { 3573b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // We do a bottom-up SCC traversal of the call graph. In other words, we 3583b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // visit all callees before callers (leaf-first). 3599a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands for (scc_iterator<CallGraph*> I = scc_begin(&CG), E = scc_end(&CG); I != E; 3609a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands ++I) { 3619a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands std::vector<CallGraphNode *> &SCC = *I; 362f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands assert(!SCC.empty() && "SCC with no functions?"); 3639a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 364f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands if (!SCC[0]->getFunction()) { 365f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands // Calls externally - can't say anything useful. Remove any existing 366f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands // function records (may have been created when scanning globals). 367f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands for (unsigned i = 0, e = SCC.size(); i != e; ++i) 368f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands FunctionInfo.erase(SCC[i]->getFunction()); 36934f2a0ca17f00f9ce2081ee278685a007856fd90Duncan Sands continue; 370f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands } 371f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands 372f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands FunctionRecord &FR = FunctionInfo[SCC[0]->getFunction()]; 3733b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 3749a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands bool KnowNothing = false; 3759a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands unsigned FunctionEffect = 0; 3769a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 3779a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // Collect the mod/ref properties due to called functions. We only compute 3789a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // one mod-ref set. 3799a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands for (unsigned i = 0, e = SCC.size(); i != e && !KnowNothing; ++i) { 3809a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands Function *F = SCC[i]->getFunction(); 3819a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (!F) { 3829a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands KnowNothing = true; 383fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner break; 3843b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 385fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 3869a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (F->isDeclaration()) { 3879a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // Try to get mod/ref behaviour from function attributes. 388d0ac373660de64fe210e50458c7702432b3f9605Duncan Sands if (F->doesNotAccessMemory()) { 389d0ac373660de64fe210e50458c7702432b3f9605Duncan Sands // Can't do better than that! 390d0ac373660de64fe210e50458c7702432b3f9605Duncan Sands } else if (F->onlyReadsMemory()) { 3919a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands FunctionEffect |= Ref; 3922bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands if (!F->isIntrinsic()) 3931abe60b9be1b7b33e1fa422add5296d392831850Duncan Sands // This function might call back into the module and read a global - 3942bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands // consider every global as possibly being read by this function. 3952bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands FR.MayReadAnyGlobal = true; 396d0ac373660de64fe210e50458c7702432b3f9605Duncan Sands } else { 397892b84007c980e58181cd94fea7d70c5ed9642c8Duncan Sands FunctionEffect |= ModRef; 398892b84007c980e58181cd94fea7d70c5ed9642c8Duncan Sands // Can't say anything useful unless it's an intrinsic - they don't 399892b84007c980e58181cd94fea7d70c5ed9642c8Duncan Sands // read or write global variables of the kind considered here. 400892b84007c980e58181cd94fea7d70c5ed9642c8Duncan Sands KnowNothing = !F->isIntrinsic(); 4019a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } 4029a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands continue; 4039a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } 4049a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 4059a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands for (CallGraphNode::iterator CI = SCC[i]->begin(), E = SCC[i]->end(); 406f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands CI != E && !KnowNothing; ++CI) 4079a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (Function *Callee = CI->second->getFunction()) { 4089a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (FunctionRecord *CalleeFR = getFunctionInfo(Callee)) { 4099a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // Propagate function effect up. 4109a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands FunctionEffect |= CalleeFR->FunctionEffect; 4119a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 4129a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // Incorporate callee's effects on globals into our info. 41379fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman for (std::map<const GlobalValue*, unsigned>::iterator GI = 4149a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands CalleeFR->GlobalInfo.begin(), E = CalleeFR->GlobalInfo.end(); 4159a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands GI != E; ++GI) 416f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands FR.GlobalInfo[GI->first] |= GI->second; 4172bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands FR.MayReadAnyGlobal |= CalleeFR->MayReadAnyGlobal; 4189a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } else { 4199a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // Can't say anything about it. However, if it is inside our SCC, 4209a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // then nothing needs to be done. 4219a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands CallGraphNode *CalleeNode = CG[Callee]; 4229a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (std::find(SCC.begin(), SCC.end(), CalleeNode) == SCC.end()) 4239a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands KnowNothing = true; 4249a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } 4259a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } else { 4269a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands KnowNothing = true; 4279a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } 4289a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } 4299a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 4309a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // If we can't say anything useful about this SCC, remove all SCC functions 4319a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // from the FunctionInfo map. 4329a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (KnowNothing) { 4339a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands for (unsigned i = 0, e = SCC.size(); i != e; ++i) 4349a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands FunctionInfo.erase(SCC[i]->getFunction()); 435b070beee77cf9a0befd06a4fdacb824b1da0b55aDuncan Sands continue; 4369a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } 4372b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman 4389a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // Scan the function bodies for explicit loads or stores. 439fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner for (unsigned i = 0, e = SCC.size(); i != e && FunctionEffect != ModRef;++i) 440fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner for (inst_iterator II = inst_begin(SCC[i]->getFunction()), 4412b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman E = inst_end(SCC[i]->getFunction()); 442fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner II != E && FunctionEffect != ModRef; ++II) 443b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands if (isa<LoadInst>(*II)) { 444fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FunctionEffect |= Ref; 445b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands if (cast<LoadInst>(*II).isVolatile()) 446b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands // Volatile loads may have side-effects, so mark them as writing 447b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands // memory (for example, a flag inside the processor). 448b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands FunctionEffect |= Mod; 449b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands } else if (isa<StoreInst>(*II)) { 450fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FunctionEffect |= Mod; 451b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands if (cast<StoreInst>(*II).isVolatile()) 452b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands // Treat volatile stores as reading memory somewhere. 453b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands FunctionEffect |= Ref; 454046e78ce55a7c3d82b7b6758d2d77f2d99f970bfVictor Hernandez } else if (isMalloc(&cast<Instruction>(*II)) || 45566284e063a1e46500acae48bdc0e4a00652021d1Victor Hernandez isFreeCall(&cast<Instruction>(*II))) { 4563fe4d3cb5bd5ea7948faeed8451b61380d928808Chris Lattner FunctionEffect |= ModRef; 457b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands } 458fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 4599a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if ((FunctionEffect & Mod) == 0) 4609a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands ++NumReadMemFunctions; 4619a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (FunctionEffect == 0) 4629a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands ++NumNoMemFunctions; 463f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands FR.FunctionEffect = FunctionEffect; 464fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 4659a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // Finally, now that we know the full effect on this SCC, clone the 4669a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // information to each function in the SCC. 4679a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands for (unsigned i = 1, e = SCC.size(); i != e; ++i) 468f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands FunctionInfo[SCC[i]->getFunction()] = FR; 4699a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } 4703b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 4713b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 4723b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 4733b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 4743b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// alias - If one of the pointers is to a global that we are tracking, and the 4753b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// other is some random pointer, we know there cannot be an alias, because the 4763b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// address of the global isn't taken. 4773b04a8ac455568f9b98ab7e9a43076260cb737aeChris LattnerAliasAnalysis::AliasResult 478b2143b6247901ae4eca2192ee134564c4f5f7853Dan GohmanGlobalsModRef::alias(const Location &LocA, 479b2143b6247901ae4eca2192ee134564c4f5f7853Dan Gohman const Location &LocB) { 480ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Get the base object these pointers point to. 481b2143b6247901ae4eca2192ee134564c4f5f7853Dan Gohman const Value *UV1 = LocA.Ptr->getUnderlyingObject(); 482b2143b6247901ae4eca2192ee134564c4f5f7853Dan Gohman const Value *UV2 = LocB.Ptr->getUnderlyingObject(); 4839a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 484ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // If either of the underlying values is a global, they may be non-addr-taken 485ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // globals, which we can answer queries about. 48679fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman const GlobalValue *GV1 = dyn_cast<GlobalValue>(UV1); 48779fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman const GlobalValue *GV2 = dyn_cast<GlobalValue>(UV2); 488ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (GV1 || GV2) { 489ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // If the global's address is taken, pretend we don't know it's a pointer to 490ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // the global. 491ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (GV1 && !NonAddressTakenGlobals.count(GV1)) GV1 = 0; 492ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (GV2 && !NonAddressTakenGlobals.count(GV2)) GV2 = 0; 493ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 494f451cb870efcf9e0302d25ed05f4cac6bb494e42Dan Gohman // If the two pointers are derived from two different non-addr-taken 495ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // globals, or if one is and the other isn't, we know these can't alias. 496ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if ((GV1 || GV2) && GV1 != GV2) 497ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return NoAlias; 498ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 499ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Otherwise if they are both derived from the same addr-taken global, we 500ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // can't know the two accesses don't overlap. 501ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 5029a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 503ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // These pointers may be based on the memory owned by an indirect global. If 504ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // so, we may be able to handle this. First check to see if the base pointer 505ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // is a direct load from an indirect global. 506ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GV1 = GV2 = 0; 50779fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman if (const LoadInst *LI = dyn_cast<LoadInst>(UV1)) 508ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0))) 509ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (IndirectGlobals.count(GV)) 510ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GV1 = GV; 51179fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman if (const LoadInst *LI = dyn_cast<LoadInst>(UV2)) 51279fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0))) 513ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (IndirectGlobals.count(GV)) 514ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GV2 = GV; 5159a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 516ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // These pointers may also be from an allocation for the indirect global. If 517ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // so, also handle them. 518ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AllocsForIndirectGlobals.count(UV1)) 519ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GV1 = AllocsForIndirectGlobals[UV1]; 520ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AllocsForIndirectGlobals.count(UV2)) 521ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GV2 = AllocsForIndirectGlobals[UV2]; 5229a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 523ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Now that we know whether the two pointers are related to indirect globals, 524ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // use this to disambiguate the pointers. If either pointer is based on an 525ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // indirect global and if they are not both based on the same indirect global, 526ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // they cannot alias. 5273b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner if ((GV1 || GV2) && GV1 != GV2) 5283b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return NoAlias; 5299a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 530b2143b6247901ae4eca2192ee134564c4f5f7853Dan Gohman return AliasAnalysis::alias(LocA, LocB); 5313b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 5323b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 5333b04a8ac455568f9b98ab7e9a43076260cb737aeChris LattnerAliasAnalysis::ModRefResult 53479fca6fea87be7221843031870bbf2c9ae1fc555Dan GohmanGlobalsModRef::getModRefInfo(ImmutableCallSite CS, 535b2143b6247901ae4eca2192ee134564c4f5f7853Dan Gohman const Location &Loc) { 5363b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner unsigned Known = ModRef; 5373b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 5383b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // If we are asking for mod/ref info of a direct call with a pointer to a 539fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner // global we are tracking, return information if we have it. 540b2143b6247901ae4eca2192ee134564c4f5f7853Dan Gohman if (const GlobalValue *GV = 541b2143b6247901ae4eca2192ee134564c4f5f7853Dan Gohman dyn_cast<GlobalValue>(Loc.Ptr->getUnderlyingObject())) 542bb46f52027416598a662dc1c58f48d9d56b1a65bRafael Espindola if (GV->hasLocalLinkage()) 54379fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman if (const Function *F = CS.getCalledFunction()) 544fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (NonAddressTakenGlobals.count(GV)) 54579fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman if (const FunctionRecord *FR = getFunctionInfo(F)) 546fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner Known = FR->getInfoForGlobal(GV); 5473b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 5483b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner if (Known == NoModRef) 5493b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return NoModRef; // No need to query other mod/ref analyses 550b2143b6247901ae4eca2192ee134564c4f5f7853Dan Gohman return ModRefResult(Known & AliasAnalysis::getModRefInfo(CS, Loc)); 5513b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 5523b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 5533b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 5543b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner//===----------------------------------------------------------------------===// 5553b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner// Methods to update the analysis as a result of the client transformation. 5563b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner// 5573b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattnervoid GlobalsModRef::deleteValue(Value *V) { 558ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) { 559ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (NonAddressTakenGlobals.erase(GV)) { 560ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // This global might be an indirect global. If so, remove it and remove 561ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // any AllocRelatedValues for it. 562ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (IndirectGlobals.erase(GV)) { 563ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Remove any entries in AllocsForIndirectGlobals for this global. 56479fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman for (std::map<const Value*, const GlobalValue*>::iterator 565ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner I = AllocsForIndirectGlobals.begin(), 566ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner E = AllocsForIndirectGlobals.end(); I != E; ) { 567ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (I->second == GV) { 568ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner AllocsForIndirectGlobals.erase(I++); 569ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else { 570ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner ++I; 571ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 572ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 573ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 574ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 575ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 5769a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 577ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Otherwise, if this is an allocation related to an indirect global, remove 578ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // it. 579ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner AllocsForIndirectGlobals.erase(V); 5809a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 581cd883f203d23c7e44b12dff62df2e6d65d8f231cChris Lattner AliasAnalysis::deleteValue(V); 5823b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 5833b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 5843b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattnervoid GlobalsModRef::copyValue(Value *From, Value *To) { 585cd883f203d23c7e44b12dff62df2e6d65d8f231cChris Lattner AliasAnalysis::copyValue(From, To); 5863b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 587