GlobalsModRef.cpp revision 90c579de5a383cee278acc3f7e7b9d0a656e6a35
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 // 1093b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner AliasResult alias(const Value *V1, unsigned V1Size, 1103b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner const Value *V2, unsigned V2Size); 11179fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman ModRefResult getModRefInfo(ImmutableCallSite CS, 11279fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman const Value *P, unsigned Size); 11379fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman ModRefResult getModRefInfo(ImmutableCallSite CS1, 11479fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman ImmutableCallSite CS2) { 11579fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman return AliasAnalysis::getModRefInfo(CS1, CS2); 1164a7ebfa4111305ea22fc753d4f029eed88149662Reid Spencer } 1173b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 1180af024c5d00c2a2d0e35ba33f4aaf4ed3fadfae2Chris Lattner /// getModRefBehavior - Return the behavior of the specified function if 1190af024c5d00c2a2d0e35ba33f4aaf4ed3fadfae2Chris Lattner /// called from the specified call site. The call site may be null in which 1200af024c5d00c2a2d0e35ba33f4aaf4ed3fadfae2Chris Lattner /// case the most generic behavior of this function should be returned. 121a41af344c2964573318a77e2b43eafd4d3804003Dan Gohman ModRefBehavior getModRefBehavior(const Function *F) { 122ae9f3a3b7c915f725aef5a7250e88eaeddda03c6Anton Korobeynikov if (FunctionRecord *FR = getFunctionInfo(F)) { 123fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (FR->FunctionEffect == 0) 1240af024c5d00c2a2d0e35ba33f4aaf4ed3fadfae2Chris Lattner return DoesNotAccessMemory; 125dedf2bd5a34dac25e4245f58bb902ced6b64edd9Misha Brukman else if ((FR->FunctionEffect & Mod) == 0) 126dedf2bd5a34dac25e4245f58bb902ced6b64edd9Misha Brukman return OnlyReadsMemory; 127ae9f3a3b7c915f725aef5a7250e88eaeddda03c6Anton Korobeynikov } 128a41af344c2964573318a77e2b43eafd4d3804003Dan Gohman return AliasAnalysis::getModRefBehavior(F); 129e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson } 130e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson 131e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson /// getModRefBehavior - Return the behavior of the specified function if 132e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson /// called from the specified call site. The call site may be null in which 133e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson /// case the most generic behavior of this function should be returned. 134a41af344c2964573318a77e2b43eafd4d3804003Dan Gohman ModRefBehavior getModRefBehavior(ImmutableCallSite CS) { 13579fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman const Function* F = CS.getCalledFunction(); 136a41af344c2964573318a77e2b43eafd4d3804003Dan Gohman if (!F) return AliasAnalysis::getModRefBehavior(CS); 137e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson if (FunctionRecord *FR = getFunctionInfo(F)) { 138e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson if (FR->FunctionEffect == 0) 139e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson return DoesNotAccessMemory; 140e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson else if ((FR->FunctionEffect & Mod) == 0) 141e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson return OnlyReadsMemory; 142e79422096ea5319a365d160693d0957a2a4df75eOwen Anderson } 143a41af344c2964573318a77e2b43eafd4d3804003Dan Gohman return AliasAnalysis::getModRefBehavior(CS); 144fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner } 145fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 1463b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner virtual void deleteValue(Value *V); 1473b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner virtual void copyValue(Value *From, Value *To); 1483b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 149fc570e4bff4e08aaf8efa9f90a2cdb5b885f321cChris Lattner /// getAdjustedAnalysisPointer - This method is used when a pass implements 150fc570e4bff4e08aaf8efa9f90a2cdb5b885f321cChris Lattner /// an analysis interface through multiple inheritance. If needed, it 151fc570e4bff4e08aaf8efa9f90a2cdb5b885f321cChris Lattner /// should override this to adjust the this pointer as needed for the 152fc570e4bff4e08aaf8efa9f90a2cdb5b885f321cChris Lattner /// specified pass info. 15390c579de5a383cee278acc3f7e7b9d0a656e6a35Owen Anderson virtual void *getAdjustedAnalysisPointer(AnalysisID PI) { 15490c579de5a383cee278acc3f7e7b9d0a656e6a35Owen Anderson if (PI == &AliasAnalysis::ID) 155fc570e4bff4e08aaf8efa9f90a2cdb5b885f321cChris Lattner return (AliasAnalysis*)this; 156fc570e4bff4e08aaf8efa9f90a2cdb5b885f321cChris Lattner return this; 157fc570e4bff4e08aaf8efa9f90a2cdb5b885f321cChris Lattner } 158fc570e4bff4e08aaf8efa9f90a2cdb5b885f321cChris Lattner 1593b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner private: 160fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner /// getFunctionInfo - Return the function info for the function, or null if 1619a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands /// we don't have anything useful to say about it. 16279fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman FunctionRecord *getFunctionInfo(const Function *F) { 16379fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman std::map<const Function*, FunctionRecord>::iterator I = 16479fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman FunctionInfo.find(F); 165fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (I != FunctionInfo.end()) 166fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner return &I->second; 167fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner return 0; 168fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner } 169fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 1703b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner void AnalyzeGlobals(Module &M); 1713b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner void AnalyzeCallGraph(CallGraph &CG, Module &M); 172ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner bool AnalyzeUsesOfPointer(Value *V, std::vector<Function*> &Readers, 173ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Function*> &Writers, 174ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GlobalValue *OkayStoreDest = 0); 175ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner bool AnalyzeIndirectGlobalMemory(GlobalValue *GV); 1763b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner }; 1773b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 1783b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 179844731a7f1909f55935e3514c9e713a62d67662eDan Gohmanchar GlobalsModRef::ID = 0; 180844731a7f1909f55935e3514c9e713a62d67662eDan Gohmanstatic RegisterPass<GlobalsModRef> 181844731a7f1909f55935e3514c9e713a62d67662eDan GohmanX("globalsmodref-aa", "Simple mod/ref analysis for globals", false, true); 182844731a7f1909f55935e3514c9e713a62d67662eDan Gohmanstatic RegisterAnalysisGroup<AliasAnalysis> Y(X); 183844731a7f1909f55935e3514c9e713a62d67662eDan Gohman 1843b04a8ac455568f9b98ab7e9a43076260cb737aeChris LattnerPass *llvm::createGlobalsModRefPass() { return new GlobalsModRef(); } 1853b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 186ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// AnalyzeGlobals - Scan through the users of all of the internal 1879a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands/// GlobalValue's in the program. If none of them have their "address taken" 1883b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// (really, their address passed to something nontrivial), record this fact, 1893b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// and record the functions that they are used directly in. 1903b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattnervoid GlobalsModRef::AnalyzeGlobals(Module &M) { 1913b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner std::vector<Function*> Readers, Writers; 1923b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) 193bb46f52027416598a662dc1c58f48d9d56b1a65bRafael Espindola if (I->hasLocalLinkage()) { 194ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (!AnalyzeUsesOfPointer(I, Readers, Writers)) { 195fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner // Remember that we are tracking this global. 196fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner NonAddressTakenGlobals.insert(I); 1973b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner ++NumNonAddrTakenFunctions; 1983b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 1993b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner Readers.clear(); Writers.clear(); 2003b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 2013b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 202f5eaf3c62c7b2f2da1f85ac411c4f13bcbf131f1Chris Lattner for (Module::global_iterator I = M.global_begin(), E = M.global_end(); 203f5eaf3c62c7b2f2da1f85ac411c4f13bcbf131f1Chris Lattner I != E; ++I) 204bb46f52027416598a662dc1c58f48d9d56b1a65bRafael Espindola if (I->hasLocalLinkage()) { 205ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (!AnalyzeUsesOfPointer(I, Readers, Writers)) { 2063b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // Remember that we are tracking this global, and the mod/ref fns 207fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner NonAddressTakenGlobals.insert(I); 2089a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 209fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner for (unsigned i = 0, e = Readers.size(); i != e; ++i) 210fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FunctionInfo[Readers[i]].GlobalInfo[I] |= Ref; 211fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 212fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner if (!I->isConstant()) // No need to keep track of writers to constants 213fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner for (unsigned i = 0, e = Writers.size(); i != e; ++i) 214fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FunctionInfo[Writers[i]].GlobalInfo[I] |= Mod; 2153b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner ++NumNonAddrTakenGlobalVars; 2169a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 217ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // If this global holds a pointer type, see if it is an indirect global. 2181df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (I->getType()->getElementType()->isPointerTy() && 219ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner AnalyzeIndirectGlobalMemory(I)) 220ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner ++NumIndirectGlobalVars; 2213b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 2223b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner Readers.clear(); Writers.clear(); 2233b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 2243b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 2253b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 226ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// AnalyzeUsesOfPointer - Look at all of the users of the specified pointer. 227ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// If this is used by anything complex (i.e., the address escapes), return 228ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// true. Also, while we are at it, keep track of those functions that read and 229ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// write to the value. 230ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// 231ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// If OkayStoreDest is non-null, stores into this global are allowed. 232ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattnerbool GlobalsModRef::AnalyzeUsesOfPointer(Value *V, 233ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Function*> &Readers, 234ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Function*> &Writers, 235ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GlobalValue *OkayStoreDest) { 2361df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (!V->getType()->isPointerTy()) return true; 2373b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 238d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif for (Value::use_iterator UI = V->use_begin(), E=V->use_end(); UI != E; ++UI) { 239d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif User *U = *UI; 240d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif if (LoadInst *LI = dyn_cast<LoadInst>(U)) { 2413b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner Readers.push_back(LI->getParent()->getParent()); 242d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif } else if (StoreInst *SI = dyn_cast<StoreInst>(U)) { 243ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (V == SI->getOperand(1)) { 244ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner Writers.push_back(SI->getParent()->getParent()); 245ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else if (SI->getOperand(1) != OkayStoreDest) { 246ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return true; // Storing the pointer 247ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 248d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(U)) { 249ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AnalyzeUsesOfPointer(GEP, Readers, Writers)) return true; 250d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif } else if (BitCastInst *BCI = dyn_cast<BitCastInst>(U)) { 25146e8312fb733338e9af4db3757a1a8beddeae15aVictor Hernandez if (AnalyzeUsesOfPointer(BCI, Readers, Writers, OkayStoreDest)) 25246e8312fb733338e9af4db3757a1a8beddeae15aVictor Hernandez return true; 253d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif } else if (isFreeCall(U)) { 254d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif Writers.push_back(cast<Instruction>(U)->getParent()->getParent()); 255d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif } else if (CallInst *CI = dyn_cast<CallInst>(U)) { 2563b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // Make sure that this is just the function being called, not that it is 2573b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // passing into the function. 25822a5b298201d62daea3e06718469d8ad017895e1Bill Wendling for (unsigned i = 0, e = CI->getNumArgOperands(); i != e; ++i) 25922a5b298201d62daea3e06718469d8ad017895e1Bill Wendling if (CI->getArgOperand(i) == V) return true; 260d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif } else if (InvokeInst *II = dyn_cast<InvokeInst>(U)) { 2613b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // Make sure that this is just the function being called, not that it is 2623b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // passing into the function. 26322a5b298201d62daea3e06718469d8ad017895e1Bill Wendling for (unsigned i = 0, e = II->getNumArgOperands(); i != e; ++i) 26422a5b298201d62daea3e06718469d8ad017895e1Bill Wendling if (II->getArgOperand(i) == V) return true; 265d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) { 2669a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (CE->getOpcode() == Instruction::GetElementPtr || 2673da59db637a887474c1b1346c1f3ccf53b6c4663Reid Spencer CE->getOpcode() == Instruction::BitCast) { 268ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AnalyzeUsesOfPointer(CE, Readers, Writers)) 2693b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return true; 2703b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } else { 2713b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return true; 2722b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman } 273d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif } else if (ICmpInst *ICI = dyn_cast<ICmpInst>(U)) { 274e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer if (!isa<ConstantPointerNull>(ICI->getOperand(1))) 275ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return true; // Allow comparison against null. 2763b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } else { 2773b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return true; 2783b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 279d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif } 280d7cc5215f131a4df933c750595d7c642df3ee5b8Gabor Greif 2813b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return false; 2823b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 2833b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 284ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// AnalyzeIndirectGlobalMemory - We found an non-address-taken global variable 285ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// which holds a pointer type. See if the global always points to non-aliased 286ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// heap memory: that is, all initializers of the globals are allocations, and 287ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// those allocations have no use other than initialization of the global. 288ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// Further, all loads out of GV must directly use the memory, not store the 289ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// pointer somewhere. If this is true, we consider the memory pointed to by 290ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner/// GV to be owned by GV and can disambiguate other pointers from it. 291ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattnerbool GlobalsModRef::AnalyzeIndirectGlobalMemory(GlobalValue *GV) { 292ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Keep track of values related to the allocation of the memory, f.e. the 293ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // value produced by the malloc call and any casts. 294ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Value*> AllocRelatedValues; 2959a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 296ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Walk the user list of the global. If we find anything other than a direct 297ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // load or store, bail out. 298ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner for (Value::use_iterator I = GV->use_begin(), E = GV->use_end(); I != E; ++I){ 2998ba992ad527e50060083e83433b7125bbaa6b737Gabor Greif User *U = *I; 3008ba992ad527e50060083e83433b7125bbaa6b737Gabor Greif if (LoadInst *LI = dyn_cast<LoadInst>(U)) { 301ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // The pointer loaded from the global can only be used in simple ways: 302ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // we allow addressing of it and loading storing to it. We do *not* allow 303ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // storing the loaded pointer somewhere else or passing to a function. 304ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Function*> ReadersWriters; 305ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AnalyzeUsesOfPointer(LI, ReadersWriters, ReadersWriters)) 306ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return false; // Loaded pointer escapes. 307ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // TODO: Could try some IP mod/ref of the loaded pointer. 3088ba992ad527e50060083e83433b7125bbaa6b737Gabor Greif } else if (StoreInst *SI = dyn_cast<StoreInst>(U)) { 309ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Storing the global itself. 310ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (SI->getOperand(0) == GV) return false; 3119a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 312ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // If storing the null pointer, ignore it. 313ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (isa<ConstantPointerNull>(SI->getOperand(0))) 314ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner continue; 3159a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 316ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Check the value being stored. 3175d0392c6b370758750b397e254a6c6f028479969Duncan Sands Value *Ptr = SI->getOperand(0)->getUnderlyingObject(); 318ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 319a276c603b82a11b0bf0b59f0517a69e4b63adeabVictor Hernandez if (isMalloc(Ptr)) { 320ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Okay, easy case. 321ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else if (CallInst *CI = dyn_cast<CallInst>(Ptr)) { 322ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner Function *F = CI->getCalledFunction(); 3235cbf985dcbc89fba3208e7baf8b6f488b06d3ec9Reid Spencer if (!F || !F->isDeclaration()) return false; // Too hard to analyze. 324ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (F->getName() != "calloc") return false; // Not calloc. 325ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else { 326ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return false; // Too hard to analyze. 327ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 3289a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 329ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Analyze all uses of the allocation. If any of them are used in a 330ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // non-simple way (e.g. stored to another global) bail out. 331ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner std::vector<Function*> ReadersWriters; 332ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AnalyzeUsesOfPointer(Ptr, ReadersWriters, ReadersWriters, GV)) 333ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return false; // Loaded pointer escapes. 334ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 335ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Remember that this allocation is related to the indirect global. 336ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner AllocRelatedValues.push_back(Ptr); 337ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } else { 338ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Something complex, bail out. 339ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return false; 340ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 341ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 3429a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 343ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Okay, this is an indirect global. Remember all of the allocations for 344ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // this global in AllocsForIndirectGlobals. 345ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner while (!AllocRelatedValues.empty()) { 346ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner AllocsForIndirectGlobals[AllocRelatedValues.back()] = GV; 347ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner AllocRelatedValues.pop_back(); 348ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 349ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner IndirectGlobals.insert(GV); 350ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return true; 351ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner} 352ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 3533b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// AnalyzeCallGraph - At this point, we know the functions where globals are 3543b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// immediately stored to and read from. Propagate this information up the call 355fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner/// graph to all callers and compute the mod/ref info for all memory for each 3562b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman/// function. 3573b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattnervoid GlobalsModRef::AnalyzeCallGraph(CallGraph &CG, Module &M) { 3583b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // We do a bottom-up SCC traversal of the call graph. In other words, we 3593b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // visit all callees before callers (leaf-first). 3609a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands for (scc_iterator<CallGraph*> I = scc_begin(&CG), E = scc_end(&CG); I != E; 3619a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands ++I) { 3629a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands std::vector<CallGraphNode *> &SCC = *I; 363f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands assert(!SCC.empty() && "SCC with no functions?"); 3649a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 365f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands if (!SCC[0]->getFunction()) { 366f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands // Calls externally - can't say anything useful. Remove any existing 367f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands // function records (may have been created when scanning globals). 368f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands for (unsigned i = 0, e = SCC.size(); i != e; ++i) 369f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands FunctionInfo.erase(SCC[i]->getFunction()); 37034f2a0ca17f00f9ce2081ee278685a007856fd90Duncan Sands continue; 371f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands } 372f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands 373f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands FunctionRecord &FR = FunctionInfo[SCC[0]->getFunction()]; 3743b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 3759a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands bool KnowNothing = false; 3769a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands unsigned FunctionEffect = 0; 3779a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 3789a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // Collect the mod/ref properties due to called functions. We only compute 3799a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // one mod-ref set. 3809a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands for (unsigned i = 0, e = SCC.size(); i != e && !KnowNothing; ++i) { 3819a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands Function *F = SCC[i]->getFunction(); 3829a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (!F) { 3839a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands KnowNothing = true; 384fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner break; 3853b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner } 386fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 3879a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (F->isDeclaration()) { 3889a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // Try to get mod/ref behaviour from function attributes. 389d0ac373660de64fe210e50458c7702432b3f9605Duncan Sands if (F->doesNotAccessMemory()) { 390d0ac373660de64fe210e50458c7702432b3f9605Duncan Sands // Can't do better than that! 391d0ac373660de64fe210e50458c7702432b3f9605Duncan Sands } else if (F->onlyReadsMemory()) { 3929a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands FunctionEffect |= Ref; 3932bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands if (!F->isIntrinsic()) 3941abe60b9be1b7b33e1fa422add5296d392831850Duncan Sands // This function might call back into the module and read a global - 3952bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands // consider every global as possibly being read by this function. 3962bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands FR.MayReadAnyGlobal = true; 397d0ac373660de64fe210e50458c7702432b3f9605Duncan Sands } else { 398892b84007c980e58181cd94fea7d70c5ed9642c8Duncan Sands FunctionEffect |= ModRef; 399892b84007c980e58181cd94fea7d70c5ed9642c8Duncan Sands // Can't say anything useful unless it's an intrinsic - they don't 400892b84007c980e58181cd94fea7d70c5ed9642c8Duncan Sands // read or write global variables of the kind considered here. 401892b84007c980e58181cd94fea7d70c5ed9642c8Duncan Sands KnowNothing = !F->isIntrinsic(); 4029a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } 4039a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands continue; 4049a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } 4059a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 4069a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands for (CallGraphNode::iterator CI = SCC[i]->begin(), E = SCC[i]->end(); 407f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands CI != E && !KnowNothing; ++CI) 4089a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (Function *Callee = CI->second->getFunction()) { 4099a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (FunctionRecord *CalleeFR = getFunctionInfo(Callee)) { 4109a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // Propagate function effect up. 4119a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands FunctionEffect |= CalleeFR->FunctionEffect; 4129a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 4139a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // Incorporate callee's effects on globals into our info. 41479fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman for (std::map<const GlobalValue*, unsigned>::iterator GI = 4159a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands CalleeFR->GlobalInfo.begin(), E = CalleeFR->GlobalInfo.end(); 4169a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands GI != E; ++GI) 417f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands FR.GlobalInfo[GI->first] |= GI->second; 4182bb4a4d31590c1d3c7b620d7ab6959af05920cd5Duncan Sands FR.MayReadAnyGlobal |= CalleeFR->MayReadAnyGlobal; 4199a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } else { 4209a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // Can't say anything about it. However, if it is inside our SCC, 4219a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // then nothing needs to be done. 4229a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands CallGraphNode *CalleeNode = CG[Callee]; 4239a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (std::find(SCC.begin(), SCC.end(), CalleeNode) == SCC.end()) 4249a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands KnowNothing = true; 4259a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } 4269a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } else { 4279a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands KnowNothing = true; 4289a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } 4299a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } 4309a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 4319a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // If we can't say anything useful about this SCC, remove all SCC functions 4329a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // from the FunctionInfo map. 4339a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (KnowNothing) { 4349a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands for (unsigned i = 0, e = SCC.size(); i != e; ++i) 4359a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands FunctionInfo.erase(SCC[i]->getFunction()); 436b070beee77cf9a0befd06a4fdacb824b1da0b55aDuncan Sands continue; 4379a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } 4382b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman 4399a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // Scan the function bodies for explicit loads or stores. 440fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner for (unsigned i = 0, e = SCC.size(); i != e && FunctionEffect != ModRef;++i) 441fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner for (inst_iterator II = inst_begin(SCC[i]->getFunction()), 4422b37d7cf28b1382420b5e4007042feeb66d21ac8Misha Brukman E = inst_end(SCC[i]->getFunction()); 443fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner II != E && FunctionEffect != ModRef; ++II) 444b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands if (isa<LoadInst>(*II)) { 445fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FunctionEffect |= Ref; 446b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands if (cast<LoadInst>(*II).isVolatile()) 447b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands // Volatile loads may have side-effects, so mark them as writing 448b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands // memory (for example, a flag inside the processor). 449b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands FunctionEffect |= Mod; 450b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands } else if (isa<StoreInst>(*II)) { 451fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner FunctionEffect |= Mod; 452b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands if (cast<StoreInst>(*II).isVolatile()) 453b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands // Treat volatile stores as reading memory somewhere. 454b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands FunctionEffect |= Ref; 455046e78ce55a7c3d82b7b6758d2d77f2d99f970bfVictor Hernandez } else if (isMalloc(&cast<Instruction>(*II)) || 45666284e063a1e46500acae48bdc0e4a00652021d1Victor Hernandez isFreeCall(&cast<Instruction>(*II))) { 4573fe4d3cb5bd5ea7948faeed8451b61380d928808Chris Lattner FunctionEffect |= ModRef; 458b8ca4ff6439c1543a0c6729cbcd6c70c3be7dc3cDuncan Sands } 459fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 4609a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if ((FunctionEffect & Mod) == 0) 4619a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands ++NumReadMemFunctions; 4629a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands if (FunctionEffect == 0) 4639a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands ++NumNoMemFunctions; 464f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands FR.FunctionEffect = FunctionEffect; 465fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner 4669a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // Finally, now that we know the full effect on this SCC, clone the 4679a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands // information to each function in the SCC. 4689a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands for (unsigned i = 1, e = SCC.size(); i != e; ++i) 469f423abc289bca6c0b0cbb3c28bfb2f844bc7398fDuncan Sands FunctionInfo[SCC[i]->getFunction()] = FR; 4709a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands } 4713b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 4723b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 4733b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 4743b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 4753b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// alias - If one of the pointers is to a global that we are tracking, and the 4763b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// other is some random pointer, we know there cannot be an alias, because the 4773b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner/// address of the global isn't taken. 4783b04a8ac455568f9b98ab7e9a43076260cb737aeChris LattnerAliasAnalysis::AliasResult 4793b04a8ac455568f9b98ab7e9a43076260cb737aeChris LattnerGlobalsModRef::alias(const Value *V1, unsigned V1Size, 4803b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner const Value *V2, unsigned V2Size) { 481ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Get the base object these pointers point to. 48279fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman const Value *UV1 = V1->getUnderlyingObject(); 48379fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman const Value *UV2 = V2->getUnderlyingObject(); 4849a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 485ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // If either of the underlying values is a global, they may be non-addr-taken 486ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // globals, which we can answer queries about. 48779fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman const GlobalValue *GV1 = dyn_cast<GlobalValue>(UV1); 48879fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman const GlobalValue *GV2 = dyn_cast<GlobalValue>(UV2); 489ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (GV1 || GV2) { 490ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // If the global's address is taken, pretend we don't know it's a pointer to 491ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // the global. 492ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (GV1 && !NonAddressTakenGlobals.count(GV1)) GV1 = 0; 493ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (GV2 && !NonAddressTakenGlobals.count(GV2)) GV2 = 0; 494ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 495f451cb870efcf9e0302d25ed05f4cac6bb494e42Dan Gohman // If the two pointers are derived from two different non-addr-taken 496ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // globals, or if one is and the other isn't, we know these can't alias. 497ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if ((GV1 || GV2) && GV1 != GV2) 498ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner return NoAlias; 499ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner 500ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Otherwise if they are both derived from the same addr-taken global, we 501ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // can't know the two accesses don't overlap. 502ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner } 5039a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 504ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // These pointers may be based on the memory owned by an indirect global. If 505ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // so, we may be able to handle this. First check to see if the base pointer 506ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // is a direct load from an indirect global. 507ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GV1 = GV2 = 0; 50879fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman if (const LoadInst *LI = dyn_cast<LoadInst>(UV1)) 509ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0))) 510ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (IndirectGlobals.count(GV)) 511ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GV1 = GV; 51279fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman if (const LoadInst *LI = dyn_cast<LoadInst>(UV2)) 51379fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0))) 514ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (IndirectGlobals.count(GV)) 515ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GV2 = GV; 5169a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 517ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // These pointers may also be from an allocation for the indirect global. If 518ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // so, also handle them. 519ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AllocsForIndirectGlobals.count(UV1)) 520ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GV1 = AllocsForIndirectGlobals[UV1]; 521ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner if (AllocsForIndirectGlobals.count(UV2)) 522ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner GV2 = AllocsForIndirectGlobals[UV2]; 5239a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 524ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // Now that we know whether the two pointers are related to indirect globals, 525ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // use this to disambiguate the pointers. If either pointer is based on an 526ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // indirect global and if they are not both based on the same indirect global, 527ab38358fa08bcb4c7c1fc1409bc01408b49de933Chris Lattner // they cannot alias. 5283b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner if ((GV1 || GV2) && GV1 != GV2) 5293b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return NoAlias; 5309a036b945c67aeb44093c6c515e4b85e21094335Duncan Sands 5313b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return AliasAnalysis::alias(V1, V1Size, V2, V2Size); 5323b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner} 5333b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 5343b04a8ac455568f9b98ab7e9a43076260cb737aeChris LattnerAliasAnalysis::ModRefResult 53579fca6fea87be7221843031870bbf2c9ae1fc555Dan GohmanGlobalsModRef::getModRefInfo(ImmutableCallSite CS, 53679fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman const Value *P, unsigned Size) { 5373b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner unsigned Known = ModRef; 5383b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner 5393b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner // If we are asking for mod/ref info of a direct call with a pointer to a 540fe98f27e807b478d85240240cb19b6673aaaafb8Chris Lattner // global we are tracking, return information if we have it. 54179fca6fea87be7221843031870bbf2c9ae1fc555Dan Gohman if (const GlobalValue *GV = dyn_cast<GlobalValue>(P->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 5503b04a8ac455568f9b98ab7e9a43076260cb737aeChris Lattner return ModRefResult(Known & AliasAnalysis::getModRefInfo(CS, P, Size)); 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