GlobalsModRef.cpp revision 193323
1//===- GlobalsModRef.cpp - Simple Mod/Ref Analysis for Globals ------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This simple pass provides alias and mod/ref information for global values 11// that do not have their address taken, and keeps track of whether functions 12// read or write memory (are "pure"). For this simple (but very common) case, 13// we can provide pretty accurate and useful information. 14// 15//===----------------------------------------------------------------------===// 16 17#define DEBUG_TYPE "globalsmodref-aa" 18#include "llvm/Analysis/Passes.h" 19#include "llvm/Module.h" 20#include "llvm/Pass.h" 21#include "llvm/Instructions.h" 22#include "llvm/Constants.h" 23#include "llvm/DerivedTypes.h" 24#include "llvm/Analysis/AliasAnalysis.h" 25#include "llvm/Analysis/CallGraph.h" 26#include "llvm/Support/Compiler.h" 27#include "llvm/Support/CommandLine.h" 28#include "llvm/Support/InstIterator.h" 29#include "llvm/ADT/Statistic.h" 30#include "llvm/ADT/SCCIterator.h" 31#include <set> 32using namespace llvm; 33 34STATISTIC(NumNonAddrTakenGlobalVars, 35 "Number of global vars without address taken"); 36STATISTIC(NumNonAddrTakenFunctions,"Number of functions without address taken"); 37STATISTIC(NumNoMemFunctions, "Number of functions that do not access memory"); 38STATISTIC(NumReadMemFunctions, "Number of functions that only read memory"); 39STATISTIC(NumIndirectGlobalVars, "Number of indirect global objects"); 40 41namespace { 42 /// FunctionRecord - One instance of this structure is stored for every 43 /// function in the program. Later, the entries for these functions are 44 /// removed if the function is found to call an external function (in which 45 /// case we know nothing about it. 46 struct VISIBILITY_HIDDEN FunctionRecord { 47 /// GlobalInfo - Maintain mod/ref info for all of the globals without 48 /// addresses taken that are read or written (transitively) by this 49 /// function. 50 std::map<GlobalValue*, unsigned> GlobalInfo; 51 52 /// MayReadAnyGlobal - May read global variables, but it is not known which. 53 bool MayReadAnyGlobal; 54 55 unsigned getInfoForGlobal(GlobalValue *GV) const { 56 unsigned Effect = MayReadAnyGlobal ? AliasAnalysis::Ref : 0; 57 std::map<GlobalValue*, unsigned>::const_iterator I = GlobalInfo.find(GV); 58 if (I != GlobalInfo.end()) 59 Effect |= I->second; 60 return Effect; 61 } 62 63 /// FunctionEffect - Capture whether or not this function reads or writes to 64 /// ANY memory. If not, we can do a lot of aggressive analysis on it. 65 unsigned FunctionEffect; 66 67 FunctionRecord() : MayReadAnyGlobal (false), FunctionEffect(0) {} 68 }; 69 70 /// GlobalsModRef - The actual analysis pass. 71 class VISIBILITY_HIDDEN GlobalsModRef 72 : public ModulePass, public AliasAnalysis { 73 /// NonAddressTakenGlobals - The globals that do not have their addresses 74 /// taken. 75 std::set<GlobalValue*> NonAddressTakenGlobals; 76 77 /// IndirectGlobals - The memory pointed to by this global is known to be 78 /// 'owned' by the global. 79 std::set<GlobalValue*> IndirectGlobals; 80 81 /// AllocsForIndirectGlobals - If an instruction allocates memory for an 82 /// indirect global, this map indicates which one. 83 std::map<Value*, GlobalValue*> AllocsForIndirectGlobals; 84 85 /// FunctionInfo - For each function, keep track of what globals are 86 /// modified or read. 87 std::map<Function*, FunctionRecord> FunctionInfo; 88 89 public: 90 static char ID; 91 GlobalsModRef() : ModulePass(&ID) {} 92 93 bool runOnModule(Module &M) { 94 InitializeAliasAnalysis(this); // set up super class 95 AnalyzeGlobals(M); // find non-addr taken globals 96 AnalyzeCallGraph(getAnalysis<CallGraph>(), M); // Propagate on CG 97 return false; 98 } 99 100 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 101 AliasAnalysis::getAnalysisUsage(AU); 102 AU.addRequired<CallGraph>(); 103 AU.setPreservesAll(); // Does not transform code 104 } 105 106 //------------------------------------------------ 107 // Implement the AliasAnalysis API 108 // 109 AliasResult alias(const Value *V1, unsigned V1Size, 110 const Value *V2, unsigned V2Size); 111 ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size); 112 ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) { 113 return AliasAnalysis::getModRefInfo(CS1,CS2); 114 } 115 bool hasNoModRefInfoForCalls() const { return false; } 116 117 /// getModRefBehavior - Return the behavior of the specified function if 118 /// called from the specified call site. The call site may be null in which 119 /// case the most generic behavior of this function should be returned. 120 ModRefBehavior getModRefBehavior(Function *F, 121 std::vector<PointerAccessInfo> *Info) { 122 if (FunctionRecord *FR = getFunctionInfo(F)) { 123 if (FR->FunctionEffect == 0) 124 return DoesNotAccessMemory; 125 else if ((FR->FunctionEffect & Mod) == 0) 126 return OnlyReadsMemory; 127 } 128 return AliasAnalysis::getModRefBehavior(F, Info); 129 } 130 131 /// getModRefBehavior - Return the behavior of the specified function if 132 /// called from the specified call site. The call site may be null in which 133 /// case the most generic behavior of this function should be returned. 134 ModRefBehavior getModRefBehavior(CallSite CS, 135 std::vector<PointerAccessInfo> *Info) { 136 Function* F = CS.getCalledFunction(); 137 if (!F) return AliasAnalysis::getModRefBehavior(CS, Info); 138 if (FunctionRecord *FR = getFunctionInfo(F)) { 139 if (FR->FunctionEffect == 0) 140 return DoesNotAccessMemory; 141 else if ((FR->FunctionEffect & Mod) == 0) 142 return OnlyReadsMemory; 143 } 144 return AliasAnalysis::getModRefBehavior(CS, Info); 145 } 146 147 virtual void deleteValue(Value *V); 148 virtual void copyValue(Value *From, Value *To); 149 150 private: 151 /// getFunctionInfo - Return the function info for the function, or null if 152 /// we don't have anything useful to say about it. 153 FunctionRecord *getFunctionInfo(Function *F) { 154 std::map<Function*, FunctionRecord>::iterator I = FunctionInfo.find(F); 155 if (I != FunctionInfo.end()) 156 return &I->second; 157 return 0; 158 } 159 160 void AnalyzeGlobals(Module &M); 161 void AnalyzeCallGraph(CallGraph &CG, Module &M); 162 bool AnalyzeUsesOfPointer(Value *V, std::vector<Function*> &Readers, 163 std::vector<Function*> &Writers, 164 GlobalValue *OkayStoreDest = 0); 165 bool AnalyzeIndirectGlobalMemory(GlobalValue *GV); 166 }; 167} 168 169char GlobalsModRef::ID = 0; 170static RegisterPass<GlobalsModRef> 171X("globalsmodref-aa", "Simple mod/ref analysis for globals", false, true); 172static RegisterAnalysisGroup<AliasAnalysis> Y(X); 173 174Pass *llvm::createGlobalsModRefPass() { return new GlobalsModRef(); } 175 176/// AnalyzeGlobals - Scan through the users of all of the internal 177/// GlobalValue's in the program. If none of them have their "address taken" 178/// (really, their address passed to something nontrivial), record this fact, 179/// and record the functions that they are used directly in. 180void GlobalsModRef::AnalyzeGlobals(Module &M) { 181 std::vector<Function*> Readers, Writers; 182 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) 183 if (I->hasLocalLinkage()) { 184 if (!AnalyzeUsesOfPointer(I, Readers, Writers)) { 185 // Remember that we are tracking this global. 186 NonAddressTakenGlobals.insert(I); 187 ++NumNonAddrTakenFunctions; 188 } 189 Readers.clear(); Writers.clear(); 190 } 191 192 for (Module::global_iterator I = M.global_begin(), E = M.global_end(); 193 I != E; ++I) 194 if (I->hasLocalLinkage()) { 195 if (!AnalyzeUsesOfPointer(I, Readers, Writers)) { 196 // Remember that we are tracking this global, and the mod/ref fns 197 NonAddressTakenGlobals.insert(I); 198 199 for (unsigned i = 0, e = Readers.size(); i != e; ++i) 200 FunctionInfo[Readers[i]].GlobalInfo[I] |= Ref; 201 202 if (!I->isConstant()) // No need to keep track of writers to constants 203 for (unsigned i = 0, e = Writers.size(); i != e; ++i) 204 FunctionInfo[Writers[i]].GlobalInfo[I] |= Mod; 205 ++NumNonAddrTakenGlobalVars; 206 207 // If this global holds a pointer type, see if it is an indirect global. 208 if (isa<PointerType>(I->getType()->getElementType()) && 209 AnalyzeIndirectGlobalMemory(I)) 210 ++NumIndirectGlobalVars; 211 } 212 Readers.clear(); Writers.clear(); 213 } 214} 215 216/// AnalyzeUsesOfPointer - Look at all of the users of the specified pointer. 217/// If this is used by anything complex (i.e., the address escapes), return 218/// true. Also, while we are at it, keep track of those functions that read and 219/// write to the value. 220/// 221/// If OkayStoreDest is non-null, stores into this global are allowed. 222bool GlobalsModRef::AnalyzeUsesOfPointer(Value *V, 223 std::vector<Function*> &Readers, 224 std::vector<Function*> &Writers, 225 GlobalValue *OkayStoreDest) { 226 if (!isa<PointerType>(V->getType())) return true; 227 228 for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI) 229 if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) { 230 Readers.push_back(LI->getParent()->getParent()); 231 } else if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) { 232 if (V == SI->getOperand(1)) { 233 Writers.push_back(SI->getParent()->getParent()); 234 } else if (SI->getOperand(1) != OkayStoreDest) { 235 return true; // Storing the pointer 236 } 237 } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(*UI)) { 238 if (AnalyzeUsesOfPointer(GEP, Readers, Writers)) return true; 239 } else if (CallInst *CI = dyn_cast<CallInst>(*UI)) { 240 // Make sure that this is just the function being called, not that it is 241 // passing into the function. 242 for (unsigned i = 1, e = CI->getNumOperands(); i != e; ++i) 243 if (CI->getOperand(i) == V) return true; 244 } else if (InvokeInst *II = dyn_cast<InvokeInst>(*UI)) { 245 // Make sure that this is just the function being called, not that it is 246 // passing into the function. 247 for (unsigned i = 3, e = II->getNumOperands(); i != e; ++i) 248 if (II->getOperand(i) == V) return true; 249 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(*UI)) { 250 if (CE->getOpcode() == Instruction::GetElementPtr || 251 CE->getOpcode() == Instruction::BitCast) { 252 if (AnalyzeUsesOfPointer(CE, Readers, Writers)) 253 return true; 254 } else { 255 return true; 256 } 257 } else if (ICmpInst *ICI = dyn_cast<ICmpInst>(*UI)) { 258 if (!isa<ConstantPointerNull>(ICI->getOperand(1))) 259 return true; // Allow comparison against null. 260 } else if (FreeInst *F = dyn_cast<FreeInst>(*UI)) { 261 Writers.push_back(F->getParent()->getParent()); 262 } else { 263 return true; 264 } 265 return false; 266} 267 268/// AnalyzeIndirectGlobalMemory - We found an non-address-taken global variable 269/// which holds a pointer type. See if the global always points to non-aliased 270/// heap memory: that is, all initializers of the globals are allocations, and 271/// those allocations have no use other than initialization of the global. 272/// Further, all loads out of GV must directly use the memory, not store the 273/// pointer somewhere. If this is true, we consider the memory pointed to by 274/// GV to be owned by GV and can disambiguate other pointers from it. 275bool GlobalsModRef::AnalyzeIndirectGlobalMemory(GlobalValue *GV) { 276 // Keep track of values related to the allocation of the memory, f.e. the 277 // value produced by the malloc call and any casts. 278 std::vector<Value*> AllocRelatedValues; 279 280 // Walk the user list of the global. If we find anything other than a direct 281 // load or store, bail out. 282 for (Value::use_iterator I = GV->use_begin(), E = GV->use_end(); I != E; ++I){ 283 if (LoadInst *LI = dyn_cast<LoadInst>(*I)) { 284 // The pointer loaded from the global can only be used in simple ways: 285 // we allow addressing of it and loading storing to it. We do *not* allow 286 // storing the loaded pointer somewhere else or passing to a function. 287 std::vector<Function*> ReadersWriters; 288 if (AnalyzeUsesOfPointer(LI, ReadersWriters, ReadersWriters)) 289 return false; // Loaded pointer escapes. 290 // TODO: Could try some IP mod/ref of the loaded pointer. 291 } else if (StoreInst *SI = dyn_cast<StoreInst>(*I)) { 292 // Storing the global itself. 293 if (SI->getOperand(0) == GV) return false; 294 295 // If storing the null pointer, ignore it. 296 if (isa<ConstantPointerNull>(SI->getOperand(0))) 297 continue; 298 299 // Check the value being stored. 300 Value *Ptr = SI->getOperand(0)->getUnderlyingObject(); 301 302 if (isa<MallocInst>(Ptr)) { 303 // Okay, easy case. 304 } else if (CallInst *CI = dyn_cast<CallInst>(Ptr)) { 305 Function *F = CI->getCalledFunction(); 306 if (!F || !F->isDeclaration()) return false; // Too hard to analyze. 307 if (F->getName() != "calloc") return false; // Not calloc. 308 } else { 309 return false; // Too hard to analyze. 310 } 311 312 // Analyze all uses of the allocation. If any of them are used in a 313 // non-simple way (e.g. stored to another global) bail out. 314 std::vector<Function*> ReadersWriters; 315 if (AnalyzeUsesOfPointer(Ptr, ReadersWriters, ReadersWriters, GV)) 316 return false; // Loaded pointer escapes. 317 318 // Remember that this allocation is related to the indirect global. 319 AllocRelatedValues.push_back(Ptr); 320 } else { 321 // Something complex, bail out. 322 return false; 323 } 324 } 325 326 // Okay, this is an indirect global. Remember all of the allocations for 327 // this global in AllocsForIndirectGlobals. 328 while (!AllocRelatedValues.empty()) { 329 AllocsForIndirectGlobals[AllocRelatedValues.back()] = GV; 330 AllocRelatedValues.pop_back(); 331 } 332 IndirectGlobals.insert(GV); 333 return true; 334} 335 336/// AnalyzeCallGraph - At this point, we know the functions where globals are 337/// immediately stored to and read from. Propagate this information up the call 338/// graph to all callers and compute the mod/ref info for all memory for each 339/// function. 340void GlobalsModRef::AnalyzeCallGraph(CallGraph &CG, Module &M) { 341 // We do a bottom-up SCC traversal of the call graph. In other words, we 342 // visit all callees before callers (leaf-first). 343 for (scc_iterator<CallGraph*> I = scc_begin(&CG), E = scc_end(&CG); I != E; 344 ++I) { 345 std::vector<CallGraphNode *> &SCC = *I; 346 assert(!SCC.empty() && "SCC with no functions?"); 347 348 if (!SCC[0]->getFunction()) { 349 // Calls externally - can't say anything useful. Remove any existing 350 // function records (may have been created when scanning globals). 351 for (unsigned i = 0, e = SCC.size(); i != e; ++i) 352 FunctionInfo.erase(SCC[i]->getFunction()); 353 continue; 354 } 355 356 FunctionRecord &FR = FunctionInfo[SCC[0]->getFunction()]; 357 358 bool KnowNothing = false; 359 unsigned FunctionEffect = 0; 360 361 // Collect the mod/ref properties due to called functions. We only compute 362 // one mod-ref set. 363 for (unsigned i = 0, e = SCC.size(); i != e && !KnowNothing; ++i) { 364 Function *F = SCC[i]->getFunction(); 365 if (!F) { 366 KnowNothing = true; 367 break; 368 } 369 370 if (F->isDeclaration()) { 371 // Try to get mod/ref behaviour from function attributes. 372 if (F->doesNotAccessMemory()) { 373 // Can't do better than that! 374 } else if (F->onlyReadsMemory()) { 375 FunctionEffect |= Ref; 376 if (!F->isIntrinsic()) 377 // This function might call back into the module and read a global - 378 // consider every global as possibly being read by this function. 379 FR.MayReadAnyGlobal = true; 380 } else { 381 FunctionEffect |= ModRef; 382 // Can't say anything useful unless it's an intrinsic - they don't 383 // read or write global variables of the kind considered here. 384 KnowNothing = !F->isIntrinsic(); 385 } 386 continue; 387 } 388 389 for (CallGraphNode::iterator CI = SCC[i]->begin(), E = SCC[i]->end(); 390 CI != E && !KnowNothing; ++CI) 391 if (Function *Callee = CI->second->getFunction()) { 392 if (FunctionRecord *CalleeFR = getFunctionInfo(Callee)) { 393 // Propagate function effect up. 394 FunctionEffect |= CalleeFR->FunctionEffect; 395 396 // Incorporate callee's effects on globals into our info. 397 for (std::map<GlobalValue*, unsigned>::iterator GI = 398 CalleeFR->GlobalInfo.begin(), E = CalleeFR->GlobalInfo.end(); 399 GI != E; ++GI) 400 FR.GlobalInfo[GI->first] |= GI->second; 401 FR.MayReadAnyGlobal |= CalleeFR->MayReadAnyGlobal; 402 } else { 403 // Can't say anything about it. However, if it is inside our SCC, 404 // then nothing needs to be done. 405 CallGraphNode *CalleeNode = CG[Callee]; 406 if (std::find(SCC.begin(), SCC.end(), CalleeNode) == SCC.end()) 407 KnowNothing = true; 408 } 409 } else { 410 KnowNothing = true; 411 } 412 } 413 414 // If we can't say anything useful about this SCC, remove all SCC functions 415 // from the FunctionInfo map. 416 if (KnowNothing) { 417 for (unsigned i = 0, e = SCC.size(); i != e; ++i) 418 FunctionInfo.erase(SCC[i]->getFunction()); 419 continue; 420 } 421 422 // Scan the function bodies for explicit loads or stores. 423 for (unsigned i = 0, e = SCC.size(); i != e && FunctionEffect != ModRef;++i) 424 for (inst_iterator II = inst_begin(SCC[i]->getFunction()), 425 E = inst_end(SCC[i]->getFunction()); 426 II != E && FunctionEffect != ModRef; ++II) 427 if (isa<LoadInst>(*II)) { 428 FunctionEffect |= Ref; 429 if (cast<LoadInst>(*II).isVolatile()) 430 // Volatile loads may have side-effects, so mark them as writing 431 // memory (for example, a flag inside the processor). 432 FunctionEffect |= Mod; 433 } else if (isa<StoreInst>(*II)) { 434 FunctionEffect |= Mod; 435 if (cast<StoreInst>(*II).isVolatile()) 436 // Treat volatile stores as reading memory somewhere. 437 FunctionEffect |= Ref; 438 } else if (isa<MallocInst>(*II) || isa<FreeInst>(*II)) { 439 FunctionEffect |= ModRef; 440 } 441 442 if ((FunctionEffect & Mod) == 0) 443 ++NumReadMemFunctions; 444 if (FunctionEffect == 0) 445 ++NumNoMemFunctions; 446 FR.FunctionEffect = FunctionEffect; 447 448 // Finally, now that we know the full effect on this SCC, clone the 449 // information to each function in the SCC. 450 for (unsigned i = 1, e = SCC.size(); i != e; ++i) 451 FunctionInfo[SCC[i]->getFunction()] = FR; 452 } 453} 454 455 456 457/// alias - If one of the pointers is to a global that we are tracking, and the 458/// other is some random pointer, we know there cannot be an alias, because the 459/// address of the global isn't taken. 460AliasAnalysis::AliasResult 461GlobalsModRef::alias(const Value *V1, unsigned V1Size, 462 const Value *V2, unsigned V2Size) { 463 // Get the base object these pointers point to. 464 Value *UV1 = const_cast<Value*>(V1->getUnderlyingObject()); 465 Value *UV2 = const_cast<Value*>(V2->getUnderlyingObject()); 466 467 // If either of the underlying values is a global, they may be non-addr-taken 468 // globals, which we can answer queries about. 469 GlobalValue *GV1 = dyn_cast<GlobalValue>(UV1); 470 GlobalValue *GV2 = dyn_cast<GlobalValue>(UV2); 471 if (GV1 || GV2) { 472 // If the global's address is taken, pretend we don't know it's a pointer to 473 // the global. 474 if (GV1 && !NonAddressTakenGlobals.count(GV1)) GV1 = 0; 475 if (GV2 && !NonAddressTakenGlobals.count(GV2)) GV2 = 0; 476 477 // If the the two pointers are derived from two different non-addr-taken 478 // globals, or if one is and the other isn't, we know these can't alias. 479 if ((GV1 || GV2) && GV1 != GV2) 480 return NoAlias; 481 482 // Otherwise if they are both derived from the same addr-taken global, we 483 // can't know the two accesses don't overlap. 484 } 485 486 // These pointers may be based on the memory owned by an indirect global. If 487 // so, we may be able to handle this. First check to see if the base pointer 488 // is a direct load from an indirect global. 489 GV1 = GV2 = 0; 490 if (LoadInst *LI = dyn_cast<LoadInst>(UV1)) 491 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0))) 492 if (IndirectGlobals.count(GV)) 493 GV1 = GV; 494 if (LoadInst *LI = dyn_cast<LoadInst>(UV2)) 495 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0))) 496 if (IndirectGlobals.count(GV)) 497 GV2 = GV; 498 499 // These pointers may also be from an allocation for the indirect global. If 500 // so, also handle them. 501 if (AllocsForIndirectGlobals.count(UV1)) 502 GV1 = AllocsForIndirectGlobals[UV1]; 503 if (AllocsForIndirectGlobals.count(UV2)) 504 GV2 = AllocsForIndirectGlobals[UV2]; 505 506 // Now that we know whether the two pointers are related to indirect globals, 507 // use this to disambiguate the pointers. If either pointer is based on an 508 // indirect global and if they are not both based on the same indirect global, 509 // they cannot alias. 510 if ((GV1 || GV2) && GV1 != GV2) 511 return NoAlias; 512 513 return AliasAnalysis::alias(V1, V1Size, V2, V2Size); 514} 515 516AliasAnalysis::ModRefResult 517GlobalsModRef::getModRefInfo(CallSite CS, Value *P, unsigned Size) { 518 unsigned Known = ModRef; 519 520 // If we are asking for mod/ref info of a direct call with a pointer to a 521 // global we are tracking, return information if we have it. 522 if (GlobalValue *GV = dyn_cast<GlobalValue>(P->getUnderlyingObject())) 523 if (GV->hasLocalLinkage()) 524 if (Function *F = CS.getCalledFunction()) 525 if (NonAddressTakenGlobals.count(GV)) 526 if (FunctionRecord *FR = getFunctionInfo(F)) 527 Known = FR->getInfoForGlobal(GV); 528 529 if (Known == NoModRef) 530 return NoModRef; // No need to query other mod/ref analyses 531 return ModRefResult(Known & AliasAnalysis::getModRefInfo(CS, P, Size)); 532} 533 534 535//===----------------------------------------------------------------------===// 536// Methods to update the analysis as a result of the client transformation. 537// 538void GlobalsModRef::deleteValue(Value *V) { 539 if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) { 540 if (NonAddressTakenGlobals.erase(GV)) { 541 // This global might be an indirect global. If so, remove it and remove 542 // any AllocRelatedValues for it. 543 if (IndirectGlobals.erase(GV)) { 544 // Remove any entries in AllocsForIndirectGlobals for this global. 545 for (std::map<Value*, GlobalValue*>::iterator 546 I = AllocsForIndirectGlobals.begin(), 547 E = AllocsForIndirectGlobals.end(); I != E; ) { 548 if (I->second == GV) { 549 AllocsForIndirectGlobals.erase(I++); 550 } else { 551 ++I; 552 } 553 } 554 } 555 } 556 } 557 558 // Otherwise, if this is an allocation related to an indirect global, remove 559 // it. 560 AllocsForIndirectGlobals.erase(V); 561 562 AliasAnalysis::deleteValue(V); 563} 564 565void GlobalsModRef::copyValue(Value *From, Value *To) { 566 AliasAnalysis::copyValue(From, To); 567} 568