GlobalsModRef.cpp revision 212904
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<const GlobalValue*, unsigned> GlobalInfo; 51 52 /// MayReadAnyGlobal - May read global variables, but it is not known which. 53 bool MayReadAnyGlobal; 54 55 unsigned getInfoForGlobal(const GlobalValue *GV) const { 56 unsigned Effect = MayReadAnyGlobal ? AliasAnalysis::Ref : 0; 57 std::map<const GlobalValue*, unsigned>::const_iterator I = 58 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 GlobalsModRef : public ModulePass, public AliasAnalysis { 73 /// NonAddressTakenGlobals - The globals that do not have their addresses 74 /// taken. 75 std::set<const GlobalValue*> NonAddressTakenGlobals; 76 77 /// IndirectGlobals - The memory pointed to by this global is known to be 78 /// 'owned' by the global. 79 std::set<const GlobalValue*> IndirectGlobals; 80 81 /// AllocsForIndirectGlobals - If an instruction allocates memory for an 82 /// indirect global, this map indicates which one. 83 std::map<const Value*, const GlobalValue*> AllocsForIndirectGlobals; 84 85 /// FunctionInfo - For each function, keep track of what globals are 86 /// modified or read. 87 std::map<const 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(ImmutableCallSite CS, 112 const Value *P, unsigned Size); 113 ModRefResult getModRefInfo(ImmutableCallSite CS1, 114 ImmutableCallSite CS2) { 115 return AliasAnalysis::getModRefInfo(CS1, CS2); 116 } 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(const Function *F) { 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); 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(ImmutableCallSite CS) { 135 const Function* F = CS.getCalledFunction(); 136 if (!F) return AliasAnalysis::getModRefBehavior(CS); 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); 144 } 145 146 virtual void deleteValue(Value *V); 147 virtual void copyValue(Value *From, Value *To); 148 149 /// getAdjustedAnalysisPointer - This method is used when a pass implements 150 /// an analysis interface through multiple inheritance. If needed, it 151 /// should override this to adjust the this pointer as needed for the 152 /// specified pass info. 153 virtual void *getAdjustedAnalysisPointer(AnalysisID PI) { 154 if (PI == &AliasAnalysis::ID) 155 return (AliasAnalysis*)this; 156 return this; 157 } 158 159 private: 160 /// getFunctionInfo - Return the function info for the function, or null if 161 /// we don't have anything useful to say about it. 162 FunctionRecord *getFunctionInfo(const Function *F) { 163 std::map<const Function*, FunctionRecord>::iterator I = 164 FunctionInfo.find(F); 165 if (I != FunctionInfo.end()) 166 return &I->second; 167 return 0; 168 } 169 170 void AnalyzeGlobals(Module &M); 171 void AnalyzeCallGraph(CallGraph &CG, Module &M); 172 bool AnalyzeUsesOfPointer(Value *V, std::vector<Function*> &Readers, 173 std::vector<Function*> &Writers, 174 GlobalValue *OkayStoreDest = 0); 175 bool AnalyzeIndirectGlobalMemory(GlobalValue *GV); 176 }; 177} 178 179char GlobalsModRef::ID = 0; 180INITIALIZE_AG_PASS(GlobalsModRef, AliasAnalysis, 181 "globalsmodref-aa", "Simple mod/ref analysis for globals", 182 false, true, false); 183 184Pass *llvm::createGlobalsModRefPass() { return new GlobalsModRef(); } 185 186/// AnalyzeGlobals - Scan through the users of all of the internal 187/// GlobalValue's in the program. If none of them have their "address taken" 188/// (really, their address passed to something nontrivial), record this fact, 189/// and record the functions that they are used directly in. 190void GlobalsModRef::AnalyzeGlobals(Module &M) { 191 std::vector<Function*> Readers, Writers; 192 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) 193 if (I->hasLocalLinkage()) { 194 if (!AnalyzeUsesOfPointer(I, Readers, Writers)) { 195 // Remember that we are tracking this global. 196 NonAddressTakenGlobals.insert(I); 197 ++NumNonAddrTakenFunctions; 198 } 199 Readers.clear(); Writers.clear(); 200 } 201 202 for (Module::global_iterator I = M.global_begin(), E = M.global_end(); 203 I != E; ++I) 204 if (I->hasLocalLinkage()) { 205 if (!AnalyzeUsesOfPointer(I, Readers, Writers)) { 206 // Remember that we are tracking this global, and the mod/ref fns 207 NonAddressTakenGlobals.insert(I); 208 209 for (unsigned i = 0, e = Readers.size(); i != e; ++i) 210 FunctionInfo[Readers[i]].GlobalInfo[I] |= Ref; 211 212 if (!I->isConstant()) // No need to keep track of writers to constants 213 for (unsigned i = 0, e = Writers.size(); i != e; ++i) 214 FunctionInfo[Writers[i]].GlobalInfo[I] |= Mod; 215 ++NumNonAddrTakenGlobalVars; 216 217 // If this global holds a pointer type, see if it is an indirect global. 218 if (I->getType()->getElementType()->isPointerTy() && 219 AnalyzeIndirectGlobalMemory(I)) 220 ++NumIndirectGlobalVars; 221 } 222 Readers.clear(); Writers.clear(); 223 } 224} 225 226/// AnalyzeUsesOfPointer - Look at all of the users of the specified pointer. 227/// If this is used by anything complex (i.e., the address escapes), return 228/// true. Also, while we are at it, keep track of those functions that read and 229/// write to the value. 230/// 231/// If OkayStoreDest is non-null, stores into this global are allowed. 232bool GlobalsModRef::AnalyzeUsesOfPointer(Value *V, 233 std::vector<Function*> &Readers, 234 std::vector<Function*> &Writers, 235 GlobalValue *OkayStoreDest) { 236 if (!V->getType()->isPointerTy()) return true; 237 238 for (Value::use_iterator UI = V->use_begin(), E=V->use_end(); UI != E; ++UI) { 239 User *U = *UI; 240 if (LoadInst *LI = dyn_cast<LoadInst>(U)) { 241 Readers.push_back(LI->getParent()->getParent()); 242 } else if (StoreInst *SI = dyn_cast<StoreInst>(U)) { 243 if (V == SI->getOperand(1)) { 244 Writers.push_back(SI->getParent()->getParent()); 245 } else if (SI->getOperand(1) != OkayStoreDest) { 246 return true; // Storing the pointer 247 } 248 } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(U)) { 249 if (AnalyzeUsesOfPointer(GEP, Readers, Writers)) return true; 250 } else if (BitCastInst *BCI = dyn_cast<BitCastInst>(U)) { 251 if (AnalyzeUsesOfPointer(BCI, Readers, Writers, OkayStoreDest)) 252 return true; 253 } else if (isFreeCall(U)) { 254 Writers.push_back(cast<Instruction>(U)->getParent()->getParent()); 255 } else if (CallInst *CI = dyn_cast<CallInst>(U)) { 256 // Make sure that this is just the function being called, not that it is 257 // passing into the function. 258 for (unsigned i = 0, e = CI->getNumArgOperands(); i != e; ++i) 259 if (CI->getArgOperand(i) == V) return true; 260 } else if (InvokeInst *II = dyn_cast<InvokeInst>(U)) { 261 // Make sure that this is just the function being called, not that it is 262 // passing into the function. 263 for (unsigned i = 0, e = II->getNumArgOperands(); i != e; ++i) 264 if (II->getArgOperand(i) == V) return true; 265 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) { 266 if (CE->getOpcode() == Instruction::GetElementPtr || 267 CE->getOpcode() == Instruction::BitCast) { 268 if (AnalyzeUsesOfPointer(CE, Readers, Writers)) 269 return true; 270 } else { 271 return true; 272 } 273 } else if (ICmpInst *ICI = dyn_cast<ICmpInst>(U)) { 274 if (!isa<ConstantPointerNull>(ICI->getOperand(1))) 275 return true; // Allow comparison against null. 276 } else { 277 return true; 278 } 279 } 280 281 return false; 282} 283 284/// AnalyzeIndirectGlobalMemory - We found an non-address-taken global variable 285/// which holds a pointer type. See if the global always points to non-aliased 286/// heap memory: that is, all initializers of the globals are allocations, and 287/// those allocations have no use other than initialization of the global. 288/// Further, all loads out of GV must directly use the memory, not store the 289/// pointer somewhere. If this is true, we consider the memory pointed to by 290/// GV to be owned by GV and can disambiguate other pointers from it. 291bool GlobalsModRef::AnalyzeIndirectGlobalMemory(GlobalValue *GV) { 292 // Keep track of values related to the allocation of the memory, f.e. the 293 // value produced by the malloc call and any casts. 294 std::vector<Value*> AllocRelatedValues; 295 296 // Walk the user list of the global. If we find anything other than a direct 297 // load or store, bail out. 298 for (Value::use_iterator I = GV->use_begin(), E = GV->use_end(); I != E; ++I){ 299 User *U = *I; 300 if (LoadInst *LI = dyn_cast<LoadInst>(U)) { 301 // The pointer loaded from the global can only be used in simple ways: 302 // we allow addressing of it and loading storing to it. We do *not* allow 303 // storing the loaded pointer somewhere else or passing to a function. 304 std::vector<Function*> ReadersWriters; 305 if (AnalyzeUsesOfPointer(LI, ReadersWriters, ReadersWriters)) 306 return false; // Loaded pointer escapes. 307 // TODO: Could try some IP mod/ref of the loaded pointer. 308 } else if (StoreInst *SI = dyn_cast<StoreInst>(U)) { 309 // Storing the global itself. 310 if (SI->getOperand(0) == GV) return false; 311 312 // If storing the null pointer, ignore it. 313 if (isa<ConstantPointerNull>(SI->getOperand(0))) 314 continue; 315 316 // Check the value being stored. 317 Value *Ptr = SI->getOperand(0)->getUnderlyingObject(); 318 319 if (isMalloc(Ptr)) { 320 // Okay, easy case. 321 } else if (CallInst *CI = dyn_cast<CallInst>(Ptr)) { 322 Function *F = CI->getCalledFunction(); 323 if (!F || !F->isDeclaration()) return false; // Too hard to analyze. 324 if (F->getName() != "calloc") return false; // Not calloc. 325 } else { 326 return false; // Too hard to analyze. 327 } 328 329 // Analyze all uses of the allocation. If any of them are used in a 330 // non-simple way (e.g. stored to another global) bail out. 331 std::vector<Function*> ReadersWriters; 332 if (AnalyzeUsesOfPointer(Ptr, ReadersWriters, ReadersWriters, GV)) 333 return false; // Loaded pointer escapes. 334 335 // Remember that this allocation is related to the indirect global. 336 AllocRelatedValues.push_back(Ptr); 337 } else { 338 // Something complex, bail out. 339 return false; 340 } 341 } 342 343 // Okay, this is an indirect global. Remember all of the allocations for 344 // this global in AllocsForIndirectGlobals. 345 while (!AllocRelatedValues.empty()) { 346 AllocsForIndirectGlobals[AllocRelatedValues.back()] = GV; 347 AllocRelatedValues.pop_back(); 348 } 349 IndirectGlobals.insert(GV); 350 return true; 351} 352 353/// AnalyzeCallGraph - At this point, we know the functions where globals are 354/// immediately stored to and read from. Propagate this information up the call 355/// graph to all callers and compute the mod/ref info for all memory for each 356/// function. 357void GlobalsModRef::AnalyzeCallGraph(CallGraph &CG, Module &M) { 358 // We do a bottom-up SCC traversal of the call graph. In other words, we 359 // visit all callees before callers (leaf-first). 360 for (scc_iterator<CallGraph*> I = scc_begin(&CG), E = scc_end(&CG); I != E; 361 ++I) { 362 std::vector<CallGraphNode *> &SCC = *I; 363 assert(!SCC.empty() && "SCC with no functions?"); 364 365 if (!SCC[0]->getFunction()) { 366 // Calls externally - can't say anything useful. Remove any existing 367 // function records (may have been created when scanning globals). 368 for (unsigned i = 0, e = SCC.size(); i != e; ++i) 369 FunctionInfo.erase(SCC[i]->getFunction()); 370 continue; 371 } 372 373 FunctionRecord &FR = FunctionInfo[SCC[0]->getFunction()]; 374 375 bool KnowNothing = false; 376 unsigned FunctionEffect = 0; 377 378 // Collect the mod/ref properties due to called functions. We only compute 379 // one mod-ref set. 380 for (unsigned i = 0, e = SCC.size(); i != e && !KnowNothing; ++i) { 381 Function *F = SCC[i]->getFunction(); 382 if (!F) { 383 KnowNothing = true; 384 break; 385 } 386 387 if (F->isDeclaration()) { 388 // Try to get mod/ref behaviour from function attributes. 389 if (F->doesNotAccessMemory()) { 390 // Can't do better than that! 391 } else if (F->onlyReadsMemory()) { 392 FunctionEffect |= Ref; 393 if (!F->isIntrinsic()) 394 // This function might call back into the module and read a global - 395 // consider every global as possibly being read by this function. 396 FR.MayReadAnyGlobal = true; 397 } else { 398 FunctionEffect |= ModRef; 399 // Can't say anything useful unless it's an intrinsic - they don't 400 // read or write global variables of the kind considered here. 401 KnowNothing = !F->isIntrinsic(); 402 } 403 continue; 404 } 405 406 for (CallGraphNode::iterator CI = SCC[i]->begin(), E = SCC[i]->end(); 407 CI != E && !KnowNothing; ++CI) 408 if (Function *Callee = CI->second->getFunction()) { 409 if (FunctionRecord *CalleeFR = getFunctionInfo(Callee)) { 410 // Propagate function effect up. 411 FunctionEffect |= CalleeFR->FunctionEffect; 412 413 // Incorporate callee's effects on globals into our info. 414 for (std::map<const GlobalValue*, unsigned>::iterator GI = 415 CalleeFR->GlobalInfo.begin(), E = CalleeFR->GlobalInfo.end(); 416 GI != E; ++GI) 417 FR.GlobalInfo[GI->first] |= GI->second; 418 FR.MayReadAnyGlobal |= CalleeFR->MayReadAnyGlobal; 419 } else { 420 // Can't say anything about it. However, if it is inside our SCC, 421 // then nothing needs to be done. 422 CallGraphNode *CalleeNode = CG[Callee]; 423 if (std::find(SCC.begin(), SCC.end(), CalleeNode) == SCC.end()) 424 KnowNothing = true; 425 } 426 } else { 427 KnowNothing = true; 428 } 429 } 430 431 // If we can't say anything useful about this SCC, remove all SCC functions 432 // from the FunctionInfo map. 433 if (KnowNothing) { 434 for (unsigned i = 0, e = SCC.size(); i != e; ++i) 435 FunctionInfo.erase(SCC[i]->getFunction()); 436 continue; 437 } 438 439 // Scan the function bodies for explicit loads or stores. 440 for (unsigned i = 0, e = SCC.size(); i != e && FunctionEffect != ModRef;++i) 441 for (inst_iterator II = inst_begin(SCC[i]->getFunction()), 442 E = inst_end(SCC[i]->getFunction()); 443 II != E && FunctionEffect != ModRef; ++II) 444 if (isa<LoadInst>(*II)) { 445 FunctionEffect |= Ref; 446 if (cast<LoadInst>(*II).isVolatile()) 447 // Volatile loads may have side-effects, so mark them as writing 448 // memory (for example, a flag inside the processor). 449 FunctionEffect |= Mod; 450 } else if (isa<StoreInst>(*II)) { 451 FunctionEffect |= Mod; 452 if (cast<StoreInst>(*II).isVolatile()) 453 // Treat volatile stores as reading memory somewhere. 454 FunctionEffect |= Ref; 455 } else if (isMalloc(&cast<Instruction>(*II)) || 456 isFreeCall(&cast<Instruction>(*II))) { 457 FunctionEffect |= ModRef; 458 } 459 460 if ((FunctionEffect & Mod) == 0) 461 ++NumReadMemFunctions; 462 if (FunctionEffect == 0) 463 ++NumNoMemFunctions; 464 FR.FunctionEffect = FunctionEffect; 465 466 // Finally, now that we know the full effect on this SCC, clone the 467 // information to each function in the SCC. 468 for (unsigned i = 1, e = SCC.size(); i != e; ++i) 469 FunctionInfo[SCC[i]->getFunction()] = FR; 470 } 471} 472 473 474 475/// alias - If one of the pointers is to a global that we are tracking, and the 476/// other is some random pointer, we know there cannot be an alias, because the 477/// address of the global isn't taken. 478AliasAnalysis::AliasResult 479GlobalsModRef::alias(const Value *V1, unsigned V1Size, 480 const Value *V2, unsigned V2Size) { 481 // Get the base object these pointers point to. 482 const Value *UV1 = V1->getUnderlyingObject(); 483 const Value *UV2 = V2->getUnderlyingObject(); 484 485 // If either of the underlying values is a global, they may be non-addr-taken 486 // globals, which we can answer queries about. 487 const GlobalValue *GV1 = dyn_cast<GlobalValue>(UV1); 488 const GlobalValue *GV2 = dyn_cast<GlobalValue>(UV2); 489 if (GV1 || GV2) { 490 // If the global's address is taken, pretend we don't know it's a pointer to 491 // the global. 492 if (GV1 && !NonAddressTakenGlobals.count(GV1)) GV1 = 0; 493 if (GV2 && !NonAddressTakenGlobals.count(GV2)) GV2 = 0; 494 495 // If the two pointers are derived from two different non-addr-taken 496 // globals, or if one is and the other isn't, we know these can't alias. 497 if ((GV1 || GV2) && GV1 != GV2) 498 return NoAlias; 499 500 // Otherwise if they are both derived from the same addr-taken global, we 501 // can't know the two accesses don't overlap. 502 } 503 504 // These pointers may be based on the memory owned by an indirect global. If 505 // so, we may be able to handle this. First check to see if the base pointer 506 // is a direct load from an indirect global. 507 GV1 = GV2 = 0; 508 if (const LoadInst *LI = dyn_cast<LoadInst>(UV1)) 509 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0))) 510 if (IndirectGlobals.count(GV)) 511 GV1 = GV; 512 if (const LoadInst *LI = dyn_cast<LoadInst>(UV2)) 513 if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getOperand(0))) 514 if (IndirectGlobals.count(GV)) 515 GV2 = GV; 516 517 // These pointers may also be from an allocation for the indirect global. If 518 // so, also handle them. 519 if (AllocsForIndirectGlobals.count(UV1)) 520 GV1 = AllocsForIndirectGlobals[UV1]; 521 if (AllocsForIndirectGlobals.count(UV2)) 522 GV2 = AllocsForIndirectGlobals[UV2]; 523 524 // Now that we know whether the two pointers are related to indirect globals, 525 // use this to disambiguate the pointers. If either pointer is based on an 526 // indirect global and if they are not both based on the same indirect global, 527 // they cannot alias. 528 if ((GV1 || GV2) && GV1 != GV2) 529 return NoAlias; 530 531 return AliasAnalysis::alias(V1, V1Size, V2, V2Size); 532} 533 534AliasAnalysis::ModRefResult 535GlobalsModRef::getModRefInfo(ImmutableCallSite CS, 536 const Value *P, unsigned Size) { 537 unsigned Known = ModRef; 538 539 // If we are asking for mod/ref info of a direct call with a pointer to a 540 // global we are tracking, return information if we have it. 541 if (const GlobalValue *GV = dyn_cast<GlobalValue>(P->getUnderlyingObject())) 542 if (GV->hasLocalLinkage()) 543 if (const Function *F = CS.getCalledFunction()) 544 if (NonAddressTakenGlobals.count(GV)) 545 if (const FunctionRecord *FR = getFunctionInfo(F)) 546 Known = FR->getInfoForGlobal(GV); 547 548 if (Known == NoModRef) 549 return NoModRef; // No need to query other mod/ref analyses 550 return ModRefResult(Known & AliasAnalysis::getModRefInfo(CS, P, Size)); 551} 552 553 554//===----------------------------------------------------------------------===// 555// Methods to update the analysis as a result of the client transformation. 556// 557void GlobalsModRef::deleteValue(Value *V) { 558 if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) { 559 if (NonAddressTakenGlobals.erase(GV)) { 560 // This global might be an indirect global. If so, remove it and remove 561 // any AllocRelatedValues for it. 562 if (IndirectGlobals.erase(GV)) { 563 // Remove any entries in AllocsForIndirectGlobals for this global. 564 for (std::map<const Value*, const GlobalValue*>::iterator 565 I = AllocsForIndirectGlobals.begin(), 566 E = AllocsForIndirectGlobals.end(); I != E; ) { 567 if (I->second == GV) { 568 AllocsForIndirectGlobals.erase(I++); 569 } else { 570 ++I; 571 } 572 } 573 } 574 } 575 } 576 577 // Otherwise, if this is an allocation related to an indirect global, remove 578 // it. 579 AllocsForIndirectGlobals.erase(V); 580 581 AliasAnalysis::deleteValue(V); 582} 583 584void GlobalsModRef::copyValue(Value *From, Value *To) { 585 AliasAnalysis::copyValue(From, To); 586} 587