GlobalsModRef.cpp revision 198396
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/Analysis/MallocHelper.h" 27#include "llvm/Support/Compiler.h" 28#include "llvm/Support/CommandLine.h" 29#include "llvm/Support/InstIterator.h" 30#include "llvm/ADT/Statistic.h" 31#include "llvm/ADT/SCCIterator.h" 32#include <set> 33using namespace llvm; 34 35STATISTIC(NumNonAddrTakenGlobalVars, 36 "Number of global vars without address taken"); 37STATISTIC(NumNonAddrTakenFunctions,"Number of functions without address taken"); 38STATISTIC(NumNoMemFunctions, "Number of functions that do not access memory"); 39STATISTIC(NumReadMemFunctions, "Number of functions that only read memory"); 40STATISTIC(NumIndirectGlobalVars, "Number of indirect global objects"); 41 42namespace { 43 /// FunctionRecord - One instance of this structure is stored for every 44 /// function in the program. Later, the entries for these functions are 45 /// removed if the function is found to call an external function (in which 46 /// case we know nothing about it. 47 struct VISIBILITY_HIDDEN FunctionRecord { 48 /// GlobalInfo - Maintain mod/ref info for all of the globals without 49 /// addresses taken that are read or written (transitively) by this 50 /// function. 51 std::map<GlobalValue*, unsigned> GlobalInfo; 52 53 /// MayReadAnyGlobal - May read global variables, but it is not known which. 54 bool MayReadAnyGlobal; 55 56 unsigned getInfoForGlobal(GlobalValue *GV) const { 57 unsigned Effect = MayReadAnyGlobal ? AliasAnalysis::Ref : 0; 58 std::map<GlobalValue*, unsigned>::const_iterator I = GlobalInfo.find(GV); 59 if (I != GlobalInfo.end()) 60 Effect |= I->second; 61 return Effect; 62 } 63 64 /// FunctionEffect - Capture whether or not this function reads or writes to 65 /// ANY memory. If not, we can do a lot of aggressive analysis on it. 66 unsigned FunctionEffect; 67 68 FunctionRecord() : MayReadAnyGlobal (false), FunctionEffect(0) {} 69 }; 70 71 /// GlobalsModRef - The actual analysis pass. 72 class VISIBILITY_HIDDEN GlobalsModRef 73 : public ModulePass, public AliasAnalysis { 74 /// NonAddressTakenGlobals - The globals that do not have their addresses 75 /// taken. 76 std::set<GlobalValue*> NonAddressTakenGlobals; 77 78 /// IndirectGlobals - The memory pointed to by this global is known to be 79 /// 'owned' by the global. 80 std::set<GlobalValue*> IndirectGlobals; 81 82 /// AllocsForIndirectGlobals - If an instruction allocates memory for an 83 /// indirect global, this map indicates which one. 84 std::map<Value*, GlobalValue*> AllocsForIndirectGlobals; 85 86 /// FunctionInfo - For each function, keep track of what globals are 87 /// modified or read. 88 std::map<Function*, FunctionRecord> FunctionInfo; 89 90 public: 91 static char ID; 92 GlobalsModRef() : ModulePass(&ID) {} 93 94 bool runOnModule(Module &M) { 95 InitializeAliasAnalysis(this); // set up super class 96 AnalyzeGlobals(M); // find non-addr taken globals 97 AnalyzeCallGraph(getAnalysis<CallGraph>(), M); // Propagate on CG 98 return false; 99 } 100 101 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 102 AliasAnalysis::getAnalysisUsage(AU); 103 AU.addRequired<CallGraph>(); 104 AU.setPreservesAll(); // Does not transform code 105 } 106 107 //------------------------------------------------ 108 // Implement the AliasAnalysis API 109 // 110 AliasResult alias(const Value *V1, unsigned V1Size, 111 const Value *V2, unsigned V2Size); 112 ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size); 113 ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) { 114 return AliasAnalysis::getModRefInfo(CS1,CS2); 115 } 116 bool hasNoModRefInfoForCalls() const { return false; } 117 118 /// getModRefBehavior - Return the behavior of the specified function if 119 /// called from the specified call site. The call site may be null in which 120 /// case the most generic behavior of this function should be returned. 121 ModRefBehavior getModRefBehavior(Function *F, 122 std::vector<PointerAccessInfo> *Info) { 123 if (FunctionRecord *FR = getFunctionInfo(F)) { 124 if (FR->FunctionEffect == 0) 125 return DoesNotAccessMemory; 126 else if ((FR->FunctionEffect & Mod) == 0) 127 return OnlyReadsMemory; 128 } 129 return AliasAnalysis::getModRefBehavior(F, Info); 130 } 131 132 /// getModRefBehavior - Return the behavior of the specified function if 133 /// called from the specified call site. The call site may be null in which 134 /// case the most generic behavior of this function should be returned. 135 ModRefBehavior getModRefBehavior(CallSite CS, 136 std::vector<PointerAccessInfo> *Info) { 137 Function* F = CS.getCalledFunction(); 138 if (!F) return AliasAnalysis::getModRefBehavior(CS, Info); 139 if (FunctionRecord *FR = getFunctionInfo(F)) { 140 if (FR->FunctionEffect == 0) 141 return DoesNotAccessMemory; 142 else if ((FR->FunctionEffect & Mod) == 0) 143 return OnlyReadsMemory; 144 } 145 return AliasAnalysis::getModRefBehavior(CS, Info); 146 } 147 148 virtual void deleteValue(Value *V); 149 virtual void copyValue(Value *From, Value *To); 150 151 private: 152 /// getFunctionInfo - Return the function info for the function, or null if 153 /// we don't have anything useful to say about it. 154 FunctionRecord *getFunctionInfo(Function *F) { 155 std::map<Function*, FunctionRecord>::iterator I = FunctionInfo.find(F); 156 if (I != FunctionInfo.end()) 157 return &I->second; 158 return 0; 159 } 160 161 void AnalyzeGlobals(Module &M); 162 void AnalyzeCallGraph(CallGraph &CG, Module &M); 163 bool AnalyzeUsesOfPointer(Value *V, std::vector<Function*> &Readers, 164 std::vector<Function*> &Writers, 165 GlobalValue *OkayStoreDest = 0); 166 bool AnalyzeIndirectGlobalMemory(GlobalValue *GV); 167 }; 168} 169 170char GlobalsModRef::ID = 0; 171static RegisterPass<GlobalsModRef> 172X("globalsmodref-aa", "Simple mod/ref analysis for globals", false, true); 173static RegisterAnalysisGroup<AliasAnalysis> Y(X); 174 175Pass *llvm::createGlobalsModRefPass() { return new GlobalsModRef(); } 176 177/// AnalyzeGlobals - Scan through the users of all of the internal 178/// GlobalValue's in the program. If none of them have their "address taken" 179/// (really, their address passed to something nontrivial), record this fact, 180/// and record the functions that they are used directly in. 181void GlobalsModRef::AnalyzeGlobals(Module &M) { 182 std::vector<Function*> Readers, Writers; 183 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) 184 if (I->hasLocalLinkage()) { 185 if (!AnalyzeUsesOfPointer(I, Readers, Writers)) { 186 // Remember that we are tracking this global. 187 NonAddressTakenGlobals.insert(I); 188 ++NumNonAddrTakenFunctions; 189 } 190 Readers.clear(); Writers.clear(); 191 } 192 193 for (Module::global_iterator I = M.global_begin(), E = M.global_end(); 194 I != E; ++I) 195 if (I->hasLocalLinkage()) { 196 if (!AnalyzeUsesOfPointer(I, Readers, Writers)) { 197 // Remember that we are tracking this global, and the mod/ref fns 198 NonAddressTakenGlobals.insert(I); 199 200 for (unsigned i = 0, e = Readers.size(); i != e; ++i) 201 FunctionInfo[Readers[i]].GlobalInfo[I] |= Ref; 202 203 if (!I->isConstant()) // No need to keep track of writers to constants 204 for (unsigned i = 0, e = Writers.size(); i != e; ++i) 205 FunctionInfo[Writers[i]].GlobalInfo[I] |= Mod; 206 ++NumNonAddrTakenGlobalVars; 207 208 // If this global holds a pointer type, see if it is an indirect global. 209 if (isa<PointerType>(I->getType()->getElementType()) && 210 AnalyzeIndirectGlobalMemory(I)) 211 ++NumIndirectGlobalVars; 212 } 213 Readers.clear(); Writers.clear(); 214 } 215} 216 217/// AnalyzeUsesOfPointer - Look at all of the users of the specified pointer. 218/// If this is used by anything complex (i.e., the address escapes), return 219/// true. Also, while we are at it, keep track of those functions that read and 220/// write to the value. 221/// 222/// If OkayStoreDest is non-null, stores into this global are allowed. 223bool GlobalsModRef::AnalyzeUsesOfPointer(Value *V, 224 std::vector<Function*> &Readers, 225 std::vector<Function*> &Writers, 226 GlobalValue *OkayStoreDest) { 227 if (!isa<PointerType>(V->getType())) return true; 228 229 for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI) 230 if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) { 231 Readers.push_back(LI->getParent()->getParent()); 232 } else if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) { 233 if (V == SI->getOperand(1)) { 234 Writers.push_back(SI->getParent()->getParent()); 235 } else if (SI->getOperand(1) != OkayStoreDest) { 236 return true; // Storing the pointer 237 } 238 } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(*UI)) { 239 if (AnalyzeUsesOfPointer(GEP, Readers, Writers)) return true; 240 } else if (BitCastInst *BCI = dyn_cast<BitCastInst>(*UI)) { 241 if (AnalyzeUsesOfPointer(BCI, Readers, Writers, OkayStoreDest)) 242 return true; 243 } else if (CallInst *CI = dyn_cast<CallInst>(*UI)) { 244 // Make sure that this is just the function being called, not that it is 245 // passing into the function. 246 for (unsigned i = 1, e = CI->getNumOperands(); i != e; ++i) 247 if (CI->getOperand(i) == V) return true; 248 } else if (InvokeInst *II = dyn_cast<InvokeInst>(*UI)) { 249 // Make sure that this is just the function being called, not that it is 250 // passing into the function. 251 for (unsigned i = 3, e = II->getNumOperands(); i != e; ++i) 252 if (II->getOperand(i) == V) return true; 253 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(*UI)) { 254 if (CE->getOpcode() == Instruction::GetElementPtr || 255 CE->getOpcode() == Instruction::BitCast) { 256 if (AnalyzeUsesOfPointer(CE, Readers, Writers)) 257 return true; 258 } else { 259 return true; 260 } 261 } else if (ICmpInst *ICI = dyn_cast<ICmpInst>(*UI)) { 262 if (!isa<ConstantPointerNull>(ICI->getOperand(1))) 263 return true; // Allow comparison against null. 264 } else if (FreeInst *F = dyn_cast<FreeInst>(*UI)) { 265 Writers.push_back(F->getParent()->getParent()); 266 } else { 267 return true; 268 } 269 return false; 270} 271 272/// AnalyzeIndirectGlobalMemory - We found an non-address-taken global variable 273/// which holds a pointer type. See if the global always points to non-aliased 274/// heap memory: that is, all initializers of the globals are allocations, and 275/// those allocations have no use other than initialization of the global. 276/// Further, all loads out of GV must directly use the memory, not store the 277/// pointer somewhere. If this is true, we consider the memory pointed to by 278/// GV to be owned by GV and can disambiguate other pointers from it. 279bool GlobalsModRef::AnalyzeIndirectGlobalMemory(GlobalValue *GV) { 280 // Keep track of values related to the allocation of the memory, f.e. the 281 // value produced by the malloc call and any casts. 282 std::vector<Value*> AllocRelatedValues; 283 284 // Walk the user list of the global. If we find anything other than a direct 285 // load or store, bail out. 286 for (Value::use_iterator I = GV->use_begin(), E = GV->use_end(); I != E; ++I){ 287 if (LoadInst *LI = dyn_cast<LoadInst>(*I)) { 288 // The pointer loaded from the global can only be used in simple ways: 289 // we allow addressing of it and loading storing to it. We do *not* allow 290 // storing the loaded pointer somewhere else or passing to a function. 291 std::vector<Function*> ReadersWriters; 292 if (AnalyzeUsesOfPointer(LI, ReadersWriters, ReadersWriters)) 293 return false; // Loaded pointer escapes. 294 // TODO: Could try some IP mod/ref of the loaded pointer. 295 } else if (StoreInst *SI = dyn_cast<StoreInst>(*I)) { 296 // Storing the global itself. 297 if (SI->getOperand(0) == GV) return false; 298 299 // If storing the null pointer, ignore it. 300 if (isa<ConstantPointerNull>(SI->getOperand(0))) 301 continue; 302 303 // Check the value being stored. 304 Value *Ptr = SI->getOperand(0)->getUnderlyingObject(); 305 306 if (isMalloc(Ptr)) { 307 // Okay, easy case. 308 } else if (CallInst *CI = dyn_cast<CallInst>(Ptr)) { 309 Function *F = CI->getCalledFunction(); 310 if (!F || !F->isDeclaration()) return false; // Too hard to analyze. 311 if (F->getName() != "calloc") return false; // Not calloc. 312 } else { 313 return false; // Too hard to analyze. 314 } 315 316 // Analyze all uses of the allocation. If any of them are used in a 317 // non-simple way (e.g. stored to another global) bail out. 318 std::vector<Function*> ReadersWriters; 319 if (AnalyzeUsesOfPointer(Ptr, ReadersWriters, ReadersWriters, GV)) 320 return false; // Loaded pointer escapes. 321 322 // Remember that this allocation is related to the indirect global. 323 AllocRelatedValues.push_back(Ptr); 324 } else { 325 // Something complex, bail out. 326 return false; 327 } 328 } 329 330 // Okay, this is an indirect global. Remember all of the allocations for 331 // this global in AllocsForIndirectGlobals. 332 while (!AllocRelatedValues.empty()) { 333 AllocsForIndirectGlobals[AllocRelatedValues.back()] = GV; 334 AllocRelatedValues.pop_back(); 335 } 336 IndirectGlobals.insert(GV); 337 return true; 338} 339 340/// AnalyzeCallGraph - At this point, we know the functions where globals are 341/// immediately stored to and read from. Propagate this information up the call 342/// graph to all callers and compute the mod/ref info for all memory for each 343/// function. 344void GlobalsModRef::AnalyzeCallGraph(CallGraph &CG, Module &M) { 345 // We do a bottom-up SCC traversal of the call graph. In other words, we 346 // visit all callees before callers (leaf-first). 347 for (scc_iterator<CallGraph*> I = scc_begin(&CG), E = scc_end(&CG); I != E; 348 ++I) { 349 std::vector<CallGraphNode *> &SCC = *I; 350 assert(!SCC.empty() && "SCC with no functions?"); 351 352 if (!SCC[0]->getFunction()) { 353 // Calls externally - can't say anything useful. Remove any existing 354 // function records (may have been created when scanning globals). 355 for (unsigned i = 0, e = SCC.size(); i != e; ++i) 356 FunctionInfo.erase(SCC[i]->getFunction()); 357 continue; 358 } 359 360 FunctionRecord &FR = FunctionInfo[SCC[0]->getFunction()]; 361 362 bool KnowNothing = false; 363 unsigned FunctionEffect = 0; 364 365 // Collect the mod/ref properties due to called functions. We only compute 366 // one mod-ref set. 367 for (unsigned i = 0, e = SCC.size(); i != e && !KnowNothing; ++i) { 368 Function *F = SCC[i]->getFunction(); 369 if (!F) { 370 KnowNothing = true; 371 break; 372 } 373 374 if (F->isDeclaration()) { 375 // Try to get mod/ref behaviour from function attributes. 376 if (F->doesNotAccessMemory()) { 377 // Can't do better than that! 378 } else if (F->onlyReadsMemory()) { 379 FunctionEffect |= Ref; 380 if (!F->isIntrinsic()) 381 // This function might call back into the module and read a global - 382 // consider every global as possibly being read by this function. 383 FR.MayReadAnyGlobal = true; 384 } else { 385 FunctionEffect |= ModRef; 386 // Can't say anything useful unless it's an intrinsic - they don't 387 // read or write global variables of the kind considered here. 388 KnowNothing = !F->isIntrinsic(); 389 } 390 continue; 391 } 392 393 for (CallGraphNode::iterator CI = SCC[i]->begin(), E = SCC[i]->end(); 394 CI != E && !KnowNothing; ++CI) 395 if (Function *Callee = CI->second->getFunction()) { 396 if (FunctionRecord *CalleeFR = getFunctionInfo(Callee)) { 397 // Propagate function effect up. 398 FunctionEffect |= CalleeFR->FunctionEffect; 399 400 // Incorporate callee's effects on globals into our info. 401 for (std::map<GlobalValue*, unsigned>::iterator GI = 402 CalleeFR->GlobalInfo.begin(), E = CalleeFR->GlobalInfo.end(); 403 GI != E; ++GI) 404 FR.GlobalInfo[GI->first] |= GI->second; 405 FR.MayReadAnyGlobal |= CalleeFR->MayReadAnyGlobal; 406 } else { 407 // Can't say anything about it. However, if it is inside our SCC, 408 // then nothing needs to be done. 409 CallGraphNode *CalleeNode = CG[Callee]; 410 if (std::find(SCC.begin(), SCC.end(), CalleeNode) == SCC.end()) 411 KnowNothing = true; 412 } 413 } else { 414 KnowNothing = true; 415 } 416 } 417 418 // If we can't say anything useful about this SCC, remove all SCC functions 419 // from the FunctionInfo map. 420 if (KnowNothing) { 421 for (unsigned i = 0, e = SCC.size(); i != e; ++i) 422 FunctionInfo.erase(SCC[i]->getFunction()); 423 continue; 424 } 425 426 // Scan the function bodies for explicit loads or stores. 427 for (unsigned i = 0, e = SCC.size(); i != e && FunctionEffect != ModRef;++i) 428 for (inst_iterator II = inst_begin(SCC[i]->getFunction()), 429 E = inst_end(SCC[i]->getFunction()); 430 II != E && FunctionEffect != ModRef; ++II) 431 if (isa<LoadInst>(*II)) { 432 FunctionEffect |= Ref; 433 if (cast<LoadInst>(*II).isVolatile()) 434 // Volatile loads may have side-effects, so mark them as writing 435 // memory (for example, a flag inside the processor). 436 FunctionEffect |= Mod; 437 } else if (isa<StoreInst>(*II)) { 438 FunctionEffect |= Mod; 439 if (cast<StoreInst>(*II).isVolatile()) 440 // Treat volatile stores as reading memory somewhere. 441 FunctionEffect |= Ref; 442 } else if (isMalloc(&cast<Instruction>(*II)) || isa<FreeInst>(*II)) { 443 FunctionEffect |= ModRef; 444 } 445 446 if ((FunctionEffect & Mod) == 0) 447 ++NumReadMemFunctions; 448 if (FunctionEffect == 0) 449 ++NumNoMemFunctions; 450 FR.FunctionEffect = FunctionEffect; 451 452 // Finally, now that we know the full effect on this SCC, clone the 453 // information to each function in the SCC. 454 for (unsigned i = 1, e = SCC.size(); i != e; ++i) 455 FunctionInfo[SCC[i]->getFunction()] = FR; 456 } 457} 458 459 460 461/// alias - If one of the pointers is to a global that we are tracking, and the 462/// other is some random pointer, we know there cannot be an alias, because the 463/// address of the global isn't taken. 464AliasAnalysis::AliasResult 465GlobalsModRef::alias(const Value *V1, unsigned V1Size, 466 const Value *V2, unsigned V2Size) { 467 // Get the base object these pointers point to. 468 Value *UV1 = const_cast<Value*>(V1->getUnderlyingObject()); 469 Value *UV2 = const_cast<Value*>(V2->getUnderlyingObject()); 470 471 // If either of the underlying values is a global, they may be non-addr-taken 472 // globals, which we can answer queries about. 473 GlobalValue *GV1 = dyn_cast<GlobalValue>(UV1); 474 GlobalValue *GV2 = dyn_cast<GlobalValue>(UV2); 475 if (GV1 || GV2) { 476 // If the global's address is taken, pretend we don't know it's a pointer to 477 // the global. 478 if (GV1 && !NonAddressTakenGlobals.count(GV1)) GV1 = 0; 479 if (GV2 && !NonAddressTakenGlobals.count(GV2)) GV2 = 0; 480 481 // If the the two pointers are derived from two different non-addr-taken 482 // globals, or if one is and the other isn't, we know these can't alias. 483 if ((GV1 || GV2) && GV1 != GV2) 484 return NoAlias; 485 486 // Otherwise if they are both derived from the same addr-taken global, we 487 // can't know the two accesses don't overlap. 488 } 489 490 // These pointers may be based on the memory owned by an indirect global. If 491 // so, we may be able to handle this. First check to see if the base pointer 492 // is a direct load from an indirect global. 493 GV1 = GV2 = 0; 494 if (LoadInst *LI = dyn_cast<LoadInst>(UV1)) 495 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0))) 496 if (IndirectGlobals.count(GV)) 497 GV1 = GV; 498 if (LoadInst *LI = dyn_cast<LoadInst>(UV2)) 499 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0))) 500 if (IndirectGlobals.count(GV)) 501 GV2 = GV; 502 503 // These pointers may also be from an allocation for the indirect global. If 504 // so, also handle them. 505 if (AllocsForIndirectGlobals.count(UV1)) 506 GV1 = AllocsForIndirectGlobals[UV1]; 507 if (AllocsForIndirectGlobals.count(UV2)) 508 GV2 = AllocsForIndirectGlobals[UV2]; 509 510 // Now that we know whether the two pointers are related to indirect globals, 511 // use this to disambiguate the pointers. If either pointer is based on an 512 // indirect global and if they are not both based on the same indirect global, 513 // they cannot alias. 514 if ((GV1 || GV2) && GV1 != GV2) 515 return NoAlias; 516 517 return AliasAnalysis::alias(V1, V1Size, V2, V2Size); 518} 519 520AliasAnalysis::ModRefResult 521GlobalsModRef::getModRefInfo(CallSite CS, Value *P, unsigned Size) { 522 unsigned Known = ModRef; 523 524 // If we are asking for mod/ref info of a direct call with a pointer to a 525 // global we are tracking, return information if we have it. 526 if (GlobalValue *GV = dyn_cast<GlobalValue>(P->getUnderlyingObject())) 527 if (GV->hasLocalLinkage()) 528 if (Function *F = CS.getCalledFunction()) 529 if (NonAddressTakenGlobals.count(GV)) 530 if (FunctionRecord *FR = getFunctionInfo(F)) 531 Known = FR->getInfoForGlobal(GV); 532 533 if (Known == NoModRef) 534 return NoModRef; // No need to query other mod/ref analyses 535 return ModRefResult(Known & AliasAnalysis::getModRefInfo(CS, P, Size)); 536} 537 538 539//===----------------------------------------------------------------------===// 540// Methods to update the analysis as a result of the client transformation. 541// 542void GlobalsModRef::deleteValue(Value *V) { 543 if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) { 544 if (NonAddressTakenGlobals.erase(GV)) { 545 // This global might be an indirect global. If so, remove it and remove 546 // any AllocRelatedValues for it. 547 if (IndirectGlobals.erase(GV)) { 548 // Remove any entries in AllocsForIndirectGlobals for this global. 549 for (std::map<Value*, GlobalValue*>::iterator 550 I = AllocsForIndirectGlobals.begin(), 551 E = AllocsForIndirectGlobals.end(); I != E; ) { 552 if (I->second == GV) { 553 AllocsForIndirectGlobals.erase(I++); 554 } else { 555 ++I; 556 } 557 } 558 } 559 } 560 } 561 562 // Otherwise, if this is an allocation related to an indirect global, remove 563 // it. 564 AllocsForIndirectGlobals.erase(V); 565 566 AliasAnalysis::deleteValue(V); 567} 568 569void GlobalsModRef::copyValue(Value *From, Value *To) { 570 AliasAnalysis::copyValue(From, To); 571} 572