GlobalsModRef.cpp revision 198892
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/MemoryBuiltins.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 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 GlobalsModRef : public ModulePass, public AliasAnalysis { 72 /// NonAddressTakenGlobals - The globals that do not have their addresses 73 /// taken. 74 std::set<GlobalValue*> NonAddressTakenGlobals; 75 76 /// IndirectGlobals - The memory pointed to by this global is known to be 77 /// 'owned' by the global. 78 std::set<GlobalValue*> IndirectGlobals; 79 80 /// AllocsForIndirectGlobals - If an instruction allocates memory for an 81 /// indirect global, this map indicates which one. 82 std::map<Value*, GlobalValue*> AllocsForIndirectGlobals; 83 84 /// FunctionInfo - For each function, keep track of what globals are 85 /// modified or read. 86 std::map<Function*, FunctionRecord> FunctionInfo; 87 88 public: 89 static char ID; 90 GlobalsModRef() : ModulePass(&ID) {} 91 92 bool runOnModule(Module &M) { 93 InitializeAliasAnalysis(this); // set up super class 94 AnalyzeGlobals(M); // find non-addr taken globals 95 AnalyzeCallGraph(getAnalysis<CallGraph>(), M); // Propagate on CG 96 return false; 97 } 98 99 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 100 AliasAnalysis::getAnalysisUsage(AU); 101 AU.addRequired<CallGraph>(); 102 AU.setPreservesAll(); // Does not transform code 103 } 104 105 //------------------------------------------------ 106 // Implement the AliasAnalysis API 107 // 108 AliasResult alias(const Value *V1, unsigned V1Size, 109 const Value *V2, unsigned V2Size); 110 ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size); 111 ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) { 112 return AliasAnalysis::getModRefInfo(CS1,CS2); 113 } 114 bool hasNoModRefInfoForCalls() const { return false; } 115 116 /// getModRefBehavior - Return the behavior of the specified function if 117 /// called from the specified call site. The call site may be null in which 118 /// case the most generic behavior of this function should be returned. 119 ModRefBehavior getModRefBehavior(Function *F, 120 std::vector<PointerAccessInfo> *Info) { 121 if (FunctionRecord *FR = getFunctionInfo(F)) { 122 if (FR->FunctionEffect == 0) 123 return DoesNotAccessMemory; 124 else if ((FR->FunctionEffect & Mod) == 0) 125 return OnlyReadsMemory; 126 } 127 return AliasAnalysis::getModRefBehavior(F, Info); 128 } 129 130 /// getModRefBehavior - Return the behavior of the specified function if 131 /// called from the specified call site. The call site may be null in which 132 /// case the most generic behavior of this function should be returned. 133 ModRefBehavior getModRefBehavior(CallSite CS, 134 std::vector<PointerAccessInfo> *Info) { 135 Function* F = CS.getCalledFunction(); 136 if (!F) return AliasAnalysis::getModRefBehavior(CS, Info); 137 if (FunctionRecord *FR = getFunctionInfo(F)) { 138 if (FR->FunctionEffect == 0) 139 return DoesNotAccessMemory; 140 else if ((FR->FunctionEffect & Mod) == 0) 141 return OnlyReadsMemory; 142 } 143 return AliasAnalysis::getModRefBehavior(CS, Info); 144 } 145 146 virtual void deleteValue(Value *V); 147 virtual void copyValue(Value *From, Value *To); 148 149 private: 150 /// getFunctionInfo - Return the function info for the function, or null if 151 /// we don't have anything useful to say about it. 152 FunctionRecord *getFunctionInfo(Function *F) { 153 std::map<Function*, FunctionRecord>::iterator I = FunctionInfo.find(F); 154 if (I != FunctionInfo.end()) 155 return &I->second; 156 return 0; 157 } 158 159 void AnalyzeGlobals(Module &M); 160 void AnalyzeCallGraph(CallGraph &CG, Module &M); 161 bool AnalyzeUsesOfPointer(Value *V, std::vector<Function*> &Readers, 162 std::vector<Function*> &Writers, 163 GlobalValue *OkayStoreDest = 0); 164 bool AnalyzeIndirectGlobalMemory(GlobalValue *GV); 165 }; 166} 167 168char GlobalsModRef::ID = 0; 169static RegisterPass<GlobalsModRef> 170X("globalsmodref-aa", "Simple mod/ref analysis for globals", false, true); 171static RegisterAnalysisGroup<AliasAnalysis> Y(X); 172 173Pass *llvm::createGlobalsModRefPass() { return new GlobalsModRef(); } 174 175/// AnalyzeGlobals - Scan through the users of all of the internal 176/// GlobalValue's in the program. If none of them have their "address taken" 177/// (really, their address passed to something nontrivial), record this fact, 178/// and record the functions that they are used directly in. 179void GlobalsModRef::AnalyzeGlobals(Module &M) { 180 std::vector<Function*> Readers, Writers; 181 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) 182 if (I->hasLocalLinkage()) { 183 if (!AnalyzeUsesOfPointer(I, Readers, Writers)) { 184 // Remember that we are tracking this global. 185 NonAddressTakenGlobals.insert(I); 186 ++NumNonAddrTakenFunctions; 187 } 188 Readers.clear(); Writers.clear(); 189 } 190 191 for (Module::global_iterator I = M.global_begin(), E = M.global_end(); 192 I != E; ++I) 193 if (I->hasLocalLinkage()) { 194 if (!AnalyzeUsesOfPointer(I, Readers, Writers)) { 195 // Remember that we are tracking this global, and the mod/ref fns 196 NonAddressTakenGlobals.insert(I); 197 198 for (unsigned i = 0, e = Readers.size(); i != e; ++i) 199 FunctionInfo[Readers[i]].GlobalInfo[I] |= Ref; 200 201 if (!I->isConstant()) // No need to keep track of writers to constants 202 for (unsigned i = 0, e = Writers.size(); i != e; ++i) 203 FunctionInfo[Writers[i]].GlobalInfo[I] |= Mod; 204 ++NumNonAddrTakenGlobalVars; 205 206 // If this global holds a pointer type, see if it is an indirect global. 207 if (isa<PointerType>(I->getType()->getElementType()) && 208 AnalyzeIndirectGlobalMemory(I)) 209 ++NumIndirectGlobalVars; 210 } 211 Readers.clear(); Writers.clear(); 212 } 213} 214 215/// AnalyzeUsesOfPointer - Look at all of the users of the specified pointer. 216/// If this is used by anything complex (i.e., the address escapes), return 217/// true. Also, while we are at it, keep track of those functions that read and 218/// write to the value. 219/// 220/// If OkayStoreDest is non-null, stores into this global are allowed. 221bool GlobalsModRef::AnalyzeUsesOfPointer(Value *V, 222 std::vector<Function*> &Readers, 223 std::vector<Function*> &Writers, 224 GlobalValue *OkayStoreDest) { 225 if (!isa<PointerType>(V->getType())) return true; 226 227 for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI) 228 if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) { 229 Readers.push_back(LI->getParent()->getParent()); 230 } else if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) { 231 if (V == SI->getOperand(1)) { 232 Writers.push_back(SI->getParent()->getParent()); 233 } else if (SI->getOperand(1) != OkayStoreDest) { 234 return true; // Storing the pointer 235 } 236 } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(*UI)) { 237 if (AnalyzeUsesOfPointer(GEP, Readers, Writers)) return true; 238 } else if (BitCastInst *BCI = dyn_cast<BitCastInst>(*UI)) { 239 if (AnalyzeUsesOfPointer(BCI, Readers, Writers, OkayStoreDest)) 240 return true; 241 } else if (isFreeCall(*UI)) { 242 Writers.push_back(cast<Instruction>(*UI)->getParent()->getParent()); 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 { 265 return true; 266 } 267 return false; 268} 269 270/// AnalyzeIndirectGlobalMemory - We found an non-address-taken global variable 271/// which holds a pointer type. See if the global always points to non-aliased 272/// heap memory: that is, all initializers of the globals are allocations, and 273/// those allocations have no use other than initialization of the global. 274/// Further, all loads out of GV must directly use the memory, not store the 275/// pointer somewhere. If this is true, we consider the memory pointed to by 276/// GV to be owned by GV and can disambiguate other pointers from it. 277bool GlobalsModRef::AnalyzeIndirectGlobalMemory(GlobalValue *GV) { 278 // Keep track of values related to the allocation of the memory, f.e. the 279 // value produced by the malloc call and any casts. 280 std::vector<Value*> AllocRelatedValues; 281 282 // Walk the user list of the global. If we find anything other than a direct 283 // load or store, bail out. 284 for (Value::use_iterator I = GV->use_begin(), E = GV->use_end(); I != E; ++I){ 285 if (LoadInst *LI = dyn_cast<LoadInst>(*I)) { 286 // The pointer loaded from the global can only be used in simple ways: 287 // we allow addressing of it and loading storing to it. We do *not* allow 288 // storing the loaded pointer somewhere else or passing to a function. 289 std::vector<Function*> ReadersWriters; 290 if (AnalyzeUsesOfPointer(LI, ReadersWriters, ReadersWriters)) 291 return false; // Loaded pointer escapes. 292 // TODO: Could try some IP mod/ref of the loaded pointer. 293 } else if (StoreInst *SI = dyn_cast<StoreInst>(*I)) { 294 // Storing the global itself. 295 if (SI->getOperand(0) == GV) return false; 296 297 // If storing the null pointer, ignore it. 298 if (isa<ConstantPointerNull>(SI->getOperand(0))) 299 continue; 300 301 // Check the value being stored. 302 Value *Ptr = SI->getOperand(0)->getUnderlyingObject(); 303 304 if (isMalloc(Ptr)) { 305 // Okay, easy case. 306 } else if (CallInst *CI = dyn_cast<CallInst>(Ptr)) { 307 Function *F = CI->getCalledFunction(); 308 if (!F || !F->isDeclaration()) return false; // Too hard to analyze. 309 if (F->getName() != "calloc") return false; // Not calloc. 310 } else { 311 return false; // Too hard to analyze. 312 } 313 314 // Analyze all uses of the allocation. If any of them are used in a 315 // non-simple way (e.g. stored to another global) bail out. 316 std::vector<Function*> ReadersWriters; 317 if (AnalyzeUsesOfPointer(Ptr, ReadersWriters, ReadersWriters, GV)) 318 return false; // Loaded pointer escapes. 319 320 // Remember that this allocation is related to the indirect global. 321 AllocRelatedValues.push_back(Ptr); 322 } else { 323 // Something complex, bail out. 324 return false; 325 } 326 } 327 328 // Okay, this is an indirect global. Remember all of the allocations for 329 // this global in AllocsForIndirectGlobals. 330 while (!AllocRelatedValues.empty()) { 331 AllocsForIndirectGlobals[AllocRelatedValues.back()] = GV; 332 AllocRelatedValues.pop_back(); 333 } 334 IndirectGlobals.insert(GV); 335 return true; 336} 337 338/// AnalyzeCallGraph - At this point, we know the functions where globals are 339/// immediately stored to and read from. Propagate this information up the call 340/// graph to all callers and compute the mod/ref info for all memory for each 341/// function. 342void GlobalsModRef::AnalyzeCallGraph(CallGraph &CG, Module &M) { 343 // We do a bottom-up SCC traversal of the call graph. In other words, we 344 // visit all callees before callers (leaf-first). 345 for (scc_iterator<CallGraph*> I = scc_begin(&CG), E = scc_end(&CG); I != E; 346 ++I) { 347 std::vector<CallGraphNode *> &SCC = *I; 348 assert(!SCC.empty() && "SCC with no functions?"); 349 350 if (!SCC[0]->getFunction()) { 351 // Calls externally - can't say anything useful. Remove any existing 352 // function records (may have been created when scanning globals). 353 for (unsigned i = 0, e = SCC.size(); i != e; ++i) 354 FunctionInfo.erase(SCC[i]->getFunction()); 355 continue; 356 } 357 358 FunctionRecord &FR = FunctionInfo[SCC[0]->getFunction()]; 359 360 bool KnowNothing = false; 361 unsigned FunctionEffect = 0; 362 363 // Collect the mod/ref properties due to called functions. We only compute 364 // one mod-ref set. 365 for (unsigned i = 0, e = SCC.size(); i != e && !KnowNothing; ++i) { 366 Function *F = SCC[i]->getFunction(); 367 if (!F) { 368 KnowNothing = true; 369 break; 370 } 371 372 if (F->isDeclaration()) { 373 // Try to get mod/ref behaviour from function attributes. 374 if (F->doesNotAccessMemory()) { 375 // Can't do better than that! 376 } else if (F->onlyReadsMemory()) { 377 FunctionEffect |= Ref; 378 if (!F->isIntrinsic()) 379 // This function might call back into the module and read a global - 380 // consider every global as possibly being read by this function. 381 FR.MayReadAnyGlobal = true; 382 } else { 383 FunctionEffect |= ModRef; 384 // Can't say anything useful unless it's an intrinsic - they don't 385 // read or write global variables of the kind considered here. 386 KnowNothing = !F->isIntrinsic(); 387 } 388 continue; 389 } 390 391 for (CallGraphNode::iterator CI = SCC[i]->begin(), E = SCC[i]->end(); 392 CI != E && !KnowNothing; ++CI) 393 if (Function *Callee = CI->second->getFunction()) { 394 if (FunctionRecord *CalleeFR = getFunctionInfo(Callee)) { 395 // Propagate function effect up. 396 FunctionEffect |= CalleeFR->FunctionEffect; 397 398 // Incorporate callee's effects on globals into our info. 399 for (std::map<GlobalValue*, unsigned>::iterator GI = 400 CalleeFR->GlobalInfo.begin(), E = CalleeFR->GlobalInfo.end(); 401 GI != E; ++GI) 402 FR.GlobalInfo[GI->first] |= GI->second; 403 FR.MayReadAnyGlobal |= CalleeFR->MayReadAnyGlobal; 404 } else { 405 // Can't say anything about it. However, if it is inside our SCC, 406 // then nothing needs to be done. 407 CallGraphNode *CalleeNode = CG[Callee]; 408 if (std::find(SCC.begin(), SCC.end(), CalleeNode) == SCC.end()) 409 KnowNothing = true; 410 } 411 } else { 412 KnowNothing = true; 413 } 414 } 415 416 // If we can't say anything useful about this SCC, remove all SCC functions 417 // from the FunctionInfo map. 418 if (KnowNothing) { 419 for (unsigned i = 0, e = SCC.size(); i != e; ++i) 420 FunctionInfo.erase(SCC[i]->getFunction()); 421 continue; 422 } 423 424 // Scan the function bodies for explicit loads or stores. 425 for (unsigned i = 0, e = SCC.size(); i != e && FunctionEffect != ModRef;++i) 426 for (inst_iterator II = inst_begin(SCC[i]->getFunction()), 427 E = inst_end(SCC[i]->getFunction()); 428 II != E && FunctionEffect != ModRef; ++II) 429 if (isa<LoadInst>(*II)) { 430 FunctionEffect |= Ref; 431 if (cast<LoadInst>(*II).isVolatile()) 432 // Volatile loads may have side-effects, so mark them as writing 433 // memory (for example, a flag inside the processor). 434 FunctionEffect |= Mod; 435 } else if (isa<StoreInst>(*II)) { 436 FunctionEffect |= Mod; 437 if (cast<StoreInst>(*II).isVolatile()) 438 // Treat volatile stores as reading memory somewhere. 439 FunctionEffect |= Ref; 440 } else if (isMalloc(&cast<Instruction>(*II)) || 441 isFreeCall(&cast<Instruction>(*II))) { 442 FunctionEffect |= ModRef; 443 } 444 445 if ((FunctionEffect & Mod) == 0) 446 ++NumReadMemFunctions; 447 if (FunctionEffect == 0) 448 ++NumNoMemFunctions; 449 FR.FunctionEffect = FunctionEffect; 450 451 // Finally, now that we know the full effect on this SCC, clone the 452 // information to each function in the SCC. 453 for (unsigned i = 1, e = SCC.size(); i != e; ++i) 454 FunctionInfo[SCC[i]->getFunction()] = FR; 455 } 456} 457 458 459 460/// alias - If one of the pointers is to a global that we are tracking, and the 461/// other is some random pointer, we know there cannot be an alias, because the 462/// address of the global isn't taken. 463AliasAnalysis::AliasResult 464GlobalsModRef::alias(const Value *V1, unsigned V1Size, 465 const Value *V2, unsigned V2Size) { 466 // Get the base object these pointers point to. 467 Value *UV1 = const_cast<Value*>(V1->getUnderlyingObject()); 468 Value *UV2 = const_cast<Value*>(V2->getUnderlyingObject()); 469 470 // If either of the underlying values is a global, they may be non-addr-taken 471 // globals, which we can answer queries about. 472 GlobalValue *GV1 = dyn_cast<GlobalValue>(UV1); 473 GlobalValue *GV2 = dyn_cast<GlobalValue>(UV2); 474 if (GV1 || GV2) { 475 // If the global's address is taken, pretend we don't know it's a pointer to 476 // the global. 477 if (GV1 && !NonAddressTakenGlobals.count(GV1)) GV1 = 0; 478 if (GV2 && !NonAddressTakenGlobals.count(GV2)) GV2 = 0; 479 480 // If the the two pointers are derived from two different non-addr-taken 481 // globals, or if one is and the other isn't, we know these can't alias. 482 if ((GV1 || GV2) && GV1 != GV2) 483 return NoAlias; 484 485 // Otherwise if they are both derived from the same addr-taken global, we 486 // can't know the two accesses don't overlap. 487 } 488 489 // These pointers may be based on the memory owned by an indirect global. If 490 // so, we may be able to handle this. First check to see if the base pointer 491 // is a direct load from an indirect global. 492 GV1 = GV2 = 0; 493 if (LoadInst *LI = dyn_cast<LoadInst>(UV1)) 494 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0))) 495 if (IndirectGlobals.count(GV)) 496 GV1 = GV; 497 if (LoadInst *LI = dyn_cast<LoadInst>(UV2)) 498 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0))) 499 if (IndirectGlobals.count(GV)) 500 GV2 = GV; 501 502 // These pointers may also be from an allocation for the indirect global. If 503 // so, also handle them. 504 if (AllocsForIndirectGlobals.count(UV1)) 505 GV1 = AllocsForIndirectGlobals[UV1]; 506 if (AllocsForIndirectGlobals.count(UV2)) 507 GV2 = AllocsForIndirectGlobals[UV2]; 508 509 // Now that we know whether the two pointers are related to indirect globals, 510 // use this to disambiguate the pointers. If either pointer is based on an 511 // indirect global and if they are not both based on the same indirect global, 512 // they cannot alias. 513 if ((GV1 || GV2) && GV1 != GV2) 514 return NoAlias; 515 516 return AliasAnalysis::alias(V1, V1Size, V2, V2Size); 517} 518 519AliasAnalysis::ModRefResult 520GlobalsModRef::getModRefInfo(CallSite CS, Value *P, unsigned Size) { 521 unsigned Known = ModRef; 522 523 // If we are asking for mod/ref info of a direct call with a pointer to a 524 // global we are tracking, return information if we have it. 525 if (GlobalValue *GV = dyn_cast<GlobalValue>(P->getUnderlyingObject())) 526 if (GV->hasLocalLinkage()) 527 if (Function *F = CS.getCalledFunction()) 528 if (NonAddressTakenGlobals.count(GV)) 529 if (FunctionRecord *FR = getFunctionInfo(F)) 530 Known = FR->getInfoForGlobal(GV); 531 532 if (Known == NoModRef) 533 return NoModRef; // No need to query other mod/ref analyses 534 return ModRefResult(Known & AliasAnalysis::getModRefInfo(CS, P, Size)); 535} 536 537 538//===----------------------------------------------------------------------===// 539// Methods to update the analysis as a result of the client transformation. 540// 541void GlobalsModRef::deleteValue(Value *V) { 542 if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) { 543 if (NonAddressTakenGlobals.erase(GV)) { 544 // This global might be an indirect global. If so, remove it and remove 545 // any AllocRelatedValues for it. 546 if (IndirectGlobals.erase(GV)) { 547 // Remove any entries in AllocsForIndirectGlobals for this global. 548 for (std::map<Value*, GlobalValue*>::iterator 549 I = AllocsForIndirectGlobals.begin(), 550 E = AllocsForIndirectGlobals.end(); I != E; ) { 551 if (I->second == GV) { 552 AllocsForIndirectGlobals.erase(I++); 553 } else { 554 ++I; 555 } 556 } 557 } 558 } 559 } 560 561 // Otherwise, if this is an allocation related to an indirect global, remove 562 // it. 563 AllocsForIndirectGlobals.erase(V); 564 565 AliasAnalysis::deleteValue(V); 566} 567 568void GlobalsModRef::copyValue(Value *From, Value *To) { 569 AliasAnalysis::copyValue(From, To); 570} 571