LinkModules.cpp revision 6cb8c23db1c3becdce6dfbf1b7f1677faca4251e
1//===- lib/Linker/LinkModules.cpp - Module Linker Implementation ----------===// 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 file implements the LLVM module linker. 11// 12// Specifically, this: 13// * Merges global variables between the two modules 14// * Uninit + Uninit = Init, Init + Uninit = Init, Init + Init = Error if != 15// * Merges functions between two modules 16// 17//===----------------------------------------------------------------------===// 18 19#include "llvm/Linker.h" 20#include "llvm/Constants.h" 21#include "llvm/DerivedTypes.h" 22#include "llvm/LLVMContext.h" 23#include "llvm/Module.h" 24#include "llvm/TypeSymbolTable.h" 25#include "llvm/ValueSymbolTable.h" 26#include "llvm/Instructions.h" 27#include "llvm/Assembly/Writer.h" 28#include "llvm/Support/Debug.h" 29#include "llvm/Support/ErrorHandling.h" 30#include "llvm/Support/raw_ostream.h" 31#include "llvm/System/Path.h" 32#include "llvm/Transforms/Utils/ValueMapper.h" 33#include "llvm/ADT/DenseMap.h" 34using namespace llvm; 35 36// Error - Simple wrapper function to conditionally assign to E and return true. 37// This just makes error return conditions a little bit simpler... 38static inline bool Error(std::string *E, const Twine &Message) { 39 if (E) *E = Message.str(); 40 return true; 41} 42 43// Function: ResolveTypes() 44// 45// Description: 46// Attempt to link the two specified types together. 47// 48// Inputs: 49// DestTy - The type to which we wish to resolve. 50// SrcTy - The original type which we want to resolve. 51// 52// Outputs: 53// DestST - The symbol table in which the new type should be placed. 54// 55// Return value: 56// true - There is an error and the types cannot yet be linked. 57// false - No errors. 58// 59static bool ResolveTypes(const Type *DestTy, const Type *SrcTy) { 60 if (DestTy == SrcTy) return false; // If already equal, noop 61 assert(DestTy && SrcTy && "Can't handle null types"); 62 63 if (const OpaqueType *OT = dyn_cast<OpaqueType>(DestTy)) { 64 // Type _is_ in module, just opaque... 65 const_cast<OpaqueType*>(OT)->refineAbstractTypeTo(SrcTy); 66 } else if (const OpaqueType *OT = dyn_cast<OpaqueType>(SrcTy)) { 67 const_cast<OpaqueType*>(OT)->refineAbstractTypeTo(DestTy); 68 } else { 69 return true; // Cannot link types... not-equal and neither is opaque. 70 } 71 return false; 72} 73 74/// LinkerTypeMap - This implements a map of types that is stable 75/// even if types are resolved/refined to other types. This is not a general 76/// purpose map, it is specific to the linker's use. 77namespace { 78class LinkerTypeMap : public AbstractTypeUser { 79 typedef DenseMap<const Type*, PATypeHolder> TheMapTy; 80 TheMapTy TheMap; 81 82 LinkerTypeMap(const LinkerTypeMap&); // DO NOT IMPLEMENT 83 void operator=(const LinkerTypeMap&); // DO NOT IMPLEMENT 84public: 85 LinkerTypeMap() {} 86 ~LinkerTypeMap() { 87 for (DenseMap<const Type*, PATypeHolder>::iterator I = TheMap.begin(), 88 E = TheMap.end(); I != E; ++I) 89 I->first->removeAbstractTypeUser(this); 90 } 91 92 /// lookup - Return the value for the specified type or null if it doesn't 93 /// exist. 94 const Type *lookup(const Type *Ty) const { 95 TheMapTy::const_iterator I = TheMap.find(Ty); 96 if (I != TheMap.end()) return I->second; 97 return 0; 98 } 99 100 /// erase - Remove the specified type, returning true if it was in the set. 101 bool erase(const Type *Ty) { 102 if (!TheMap.erase(Ty)) 103 return false; 104 if (Ty->isAbstract()) 105 Ty->removeAbstractTypeUser(this); 106 return true; 107 } 108 109 /// insert - This returns true if the pointer was new to the set, false if it 110 /// was already in the set. 111 bool insert(const Type *Src, const Type *Dst) { 112 if (!TheMap.insert(std::make_pair(Src, PATypeHolder(Dst))).second) 113 return false; // Already in map. 114 if (Src->isAbstract()) 115 Src->addAbstractTypeUser(this); 116 return true; 117 } 118 119protected: 120 /// refineAbstractType - The callback method invoked when an abstract type is 121 /// resolved to another type. An object must override this method to update 122 /// its internal state to reference NewType instead of OldType. 123 /// 124 virtual void refineAbstractType(const DerivedType *OldTy, 125 const Type *NewTy) { 126 TheMapTy::iterator I = TheMap.find(OldTy); 127 const Type *DstTy = I->second; 128 129 TheMap.erase(I); 130 if (OldTy->isAbstract()) 131 OldTy->removeAbstractTypeUser(this); 132 133 // Don't reinsert into the map if the key is concrete now. 134 if (NewTy->isAbstract()) 135 insert(NewTy, DstTy); 136 } 137 138 /// The other case which AbstractTypeUsers must be aware of is when a type 139 /// makes the transition from being abstract (where it has clients on it's 140 /// AbstractTypeUsers list) to concrete (where it does not). This method 141 /// notifies ATU's when this occurs for a type. 142 virtual void typeBecameConcrete(const DerivedType *AbsTy) { 143 TheMap.erase(AbsTy); 144 AbsTy->removeAbstractTypeUser(this); 145 } 146 147 // for debugging... 148 virtual void dump() const { 149 dbgs() << "AbstractTypeSet!\n"; 150 } 151}; 152} 153 154 155// RecursiveResolveTypes - This is just like ResolveTypes, except that it 156// recurses down into derived types, merging the used types if the parent types 157// are compatible. 158static bool RecursiveResolveTypesI(const Type *DstTy, const Type *SrcTy, 159 LinkerTypeMap &Pointers) { 160 if (DstTy == SrcTy) return false; // If already equal, noop 161 162 // If we found our opaque type, resolve it now! 163 if (DstTy->isOpaqueTy() || SrcTy->isOpaqueTy()) 164 return ResolveTypes(DstTy, SrcTy); 165 166 // Two types cannot be resolved together if they are of different primitive 167 // type. For example, we cannot resolve an int to a float. 168 if (DstTy->getTypeID() != SrcTy->getTypeID()) return true; 169 170 // If neither type is abstract, then they really are just different types. 171 if (!DstTy->isAbstract() && !SrcTy->isAbstract()) 172 return true; 173 174 // Otherwise, resolve the used type used by this derived type... 175 switch (DstTy->getTypeID()) { 176 default: 177 return true; 178 case Type::FunctionTyID: { 179 const FunctionType *DstFT = cast<FunctionType>(DstTy); 180 const FunctionType *SrcFT = cast<FunctionType>(SrcTy); 181 if (DstFT->isVarArg() != SrcFT->isVarArg() || 182 DstFT->getNumContainedTypes() != SrcFT->getNumContainedTypes()) 183 return true; 184 185 // Use TypeHolder's so recursive resolution won't break us. 186 PATypeHolder ST(SrcFT), DT(DstFT); 187 for (unsigned i = 0, e = DstFT->getNumContainedTypes(); i != e; ++i) { 188 const Type *SE = ST->getContainedType(i), *DE = DT->getContainedType(i); 189 if (SE != DE && RecursiveResolveTypesI(DE, SE, Pointers)) 190 return true; 191 } 192 return false; 193 } 194 case Type::StructTyID: { 195 const StructType *DstST = cast<StructType>(DstTy); 196 const StructType *SrcST = cast<StructType>(SrcTy); 197 if (DstST->getNumContainedTypes() != SrcST->getNumContainedTypes()) 198 return true; 199 200 PATypeHolder ST(SrcST), DT(DstST); 201 for (unsigned i = 0, e = DstST->getNumContainedTypes(); i != e; ++i) { 202 const Type *SE = ST->getContainedType(i), *DE = DT->getContainedType(i); 203 if (SE != DE && RecursiveResolveTypesI(DE, SE, Pointers)) 204 return true; 205 } 206 return false; 207 } 208 case Type::ArrayTyID: { 209 const ArrayType *DAT = cast<ArrayType>(DstTy); 210 const ArrayType *SAT = cast<ArrayType>(SrcTy); 211 if (DAT->getNumElements() != SAT->getNumElements()) return true; 212 return RecursiveResolveTypesI(DAT->getElementType(), SAT->getElementType(), 213 Pointers); 214 } 215 case Type::VectorTyID: { 216 const VectorType *DVT = cast<VectorType>(DstTy); 217 const VectorType *SVT = cast<VectorType>(SrcTy); 218 if (DVT->getNumElements() != SVT->getNumElements()) return true; 219 return RecursiveResolveTypesI(DVT->getElementType(), SVT->getElementType(), 220 Pointers); 221 } 222 case Type::PointerTyID: { 223 const PointerType *DstPT = cast<PointerType>(DstTy); 224 const PointerType *SrcPT = cast<PointerType>(SrcTy); 225 226 if (DstPT->getAddressSpace() != SrcPT->getAddressSpace()) 227 return true; 228 229 // If this is a pointer type, check to see if we have already seen it. If 230 // so, we are in a recursive branch. Cut off the search now. We cannot use 231 // an associative container for this search, because the type pointers (keys 232 // in the container) change whenever types get resolved. 233 if (SrcPT->isAbstract()) 234 if (const Type *ExistingDestTy = Pointers.lookup(SrcPT)) 235 return ExistingDestTy != DstPT; 236 237 if (DstPT->isAbstract()) 238 if (const Type *ExistingSrcTy = Pointers.lookup(DstPT)) 239 return ExistingSrcTy != SrcPT; 240 // Otherwise, add the current pointers to the vector to stop recursion on 241 // this pair. 242 if (DstPT->isAbstract()) 243 Pointers.insert(DstPT, SrcPT); 244 if (SrcPT->isAbstract()) 245 Pointers.insert(SrcPT, DstPT); 246 247 return RecursiveResolveTypesI(DstPT->getElementType(), 248 SrcPT->getElementType(), Pointers); 249 } 250 } 251} 252 253static bool RecursiveResolveTypes(const Type *DestTy, const Type *SrcTy) { 254 LinkerTypeMap PointerTypes; 255 return RecursiveResolveTypesI(DestTy, SrcTy, PointerTypes); 256} 257 258 259// LinkTypes - Go through the symbol table of the Src module and see if any 260// types are named in the src module that are not named in the Dst module. 261// Make sure there are no type name conflicts. 262static bool LinkTypes(Module *Dest, const Module *Src, std::string *Err) { 263 TypeSymbolTable *DestST = &Dest->getTypeSymbolTable(); 264 const TypeSymbolTable *SrcST = &Src->getTypeSymbolTable(); 265 266 // Look for a type plane for Type's... 267 TypeSymbolTable::const_iterator TI = SrcST->begin(); 268 TypeSymbolTable::const_iterator TE = SrcST->end(); 269 if (TI == TE) return false; // No named types, do nothing. 270 271 // Some types cannot be resolved immediately because they depend on other 272 // types being resolved to each other first. This contains a list of types we 273 // are waiting to recheck. 274 std::vector<std::string> DelayedTypesToResolve; 275 276 for ( ; TI != TE; ++TI ) { 277 const std::string &Name = TI->first; 278 const Type *RHS = TI->second; 279 280 // Check to see if this type name is already in the dest module. 281 Type *Entry = DestST->lookup(Name); 282 283 // If the name is just in the source module, bring it over to the dest. 284 if (Entry == 0) { 285 if (!Name.empty()) 286 DestST->insert(Name, const_cast<Type*>(RHS)); 287 } else if (ResolveTypes(Entry, RHS)) { 288 // They look different, save the types 'till later to resolve. 289 DelayedTypesToResolve.push_back(Name); 290 } 291 } 292 293 // Iteratively resolve types while we can... 294 while (!DelayedTypesToResolve.empty()) { 295 // Loop over all of the types, attempting to resolve them if possible... 296 unsigned OldSize = DelayedTypesToResolve.size(); 297 298 // Try direct resolution by name... 299 for (unsigned i = 0; i != DelayedTypesToResolve.size(); ++i) { 300 const std::string &Name = DelayedTypesToResolve[i]; 301 Type *T1 = SrcST->lookup(Name); 302 Type *T2 = DestST->lookup(Name); 303 if (!ResolveTypes(T2, T1)) { 304 // We are making progress! 305 DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i); 306 --i; 307 } 308 } 309 310 // Did we not eliminate any types? 311 if (DelayedTypesToResolve.size() == OldSize) { 312 // Attempt to resolve subelements of types. This allows us to merge these 313 // two types: { int* } and { opaque* } 314 for (unsigned i = 0, e = DelayedTypesToResolve.size(); i != e; ++i) { 315 const std::string &Name = DelayedTypesToResolve[i]; 316 if (!RecursiveResolveTypes(SrcST->lookup(Name), DestST->lookup(Name))) { 317 // We are making progress! 318 DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i); 319 320 // Go back to the main loop, perhaps we can resolve directly by name 321 // now... 322 break; 323 } 324 } 325 326 // If we STILL cannot resolve the types, then there is something wrong. 327 if (DelayedTypesToResolve.size() == OldSize) { 328 // Remove the symbol name from the destination. 329 DelayedTypesToResolve.pop_back(); 330 } 331 } 332 } 333 334 335 return false; 336} 337 338/// ForceRenaming - The LLVM SymbolTable class autorenames globals that conflict 339/// in the symbol table. This is good for all clients except for us. Go 340/// through the trouble to force this back. 341static void ForceRenaming(GlobalValue *GV, const std::string &Name) { 342 assert(GV->getName() != Name && "Can't force rename to self"); 343 ValueSymbolTable &ST = GV->getParent()->getValueSymbolTable(); 344 345 // If there is a conflict, rename the conflict. 346 if (GlobalValue *ConflictGV = cast_or_null<GlobalValue>(ST.lookup(Name))) { 347 assert(ConflictGV->hasLocalLinkage() && 348 "Not conflicting with a static global, should link instead!"); 349 GV->takeName(ConflictGV); 350 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed 351 assert(ConflictGV->getName() != Name && "ForceRenaming didn't work"); 352 } else { 353 GV->setName(Name); // Force the name back 354 } 355} 356 357/// CopyGVAttributes - copy additional attributes (those not needed to construct 358/// a GlobalValue) from the SrcGV to the DestGV. 359static void CopyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) { 360 // Use the maximum alignment, rather than just copying the alignment of SrcGV. 361 unsigned Alignment = std::max(DestGV->getAlignment(), SrcGV->getAlignment()); 362 DestGV->copyAttributesFrom(SrcGV); 363 DestGV->setAlignment(Alignment); 364} 365 366/// GetLinkageResult - This analyzes the two global values and determines what 367/// the result will look like in the destination module. In particular, it 368/// computes the resultant linkage type, computes whether the global in the 369/// source should be copied over to the destination (replacing the existing 370/// one), and computes whether this linkage is an error or not. It also performs 371/// visibility checks: we cannot link together two symbols with different 372/// visibilities. 373static bool GetLinkageResult(GlobalValue *Dest, const GlobalValue *Src, 374 GlobalValue::LinkageTypes <, bool &LinkFromSrc, 375 std::string *Err) { 376 assert((!Dest || !Src->hasLocalLinkage()) && 377 "If Src has internal linkage, Dest shouldn't be set!"); 378 if (!Dest) { 379 // Linking something to nothing. 380 LinkFromSrc = true; 381 LT = Src->getLinkage(); 382 } else if (Src->isDeclaration()) { 383 // If Src is external or if both Src & Dest are external.. Just link the 384 // external globals, we aren't adding anything. 385 if (Src->hasDLLImportLinkage()) { 386 // If one of GVs has DLLImport linkage, result should be dllimport'ed. 387 if (Dest->isDeclaration()) { 388 LinkFromSrc = true; 389 LT = Src->getLinkage(); 390 } 391 } else if (Dest->hasExternalWeakLinkage()) { 392 // If the Dest is weak, use the source linkage. 393 LinkFromSrc = true; 394 LT = Src->getLinkage(); 395 } else { 396 LinkFromSrc = false; 397 LT = Dest->getLinkage(); 398 } 399 } else if (Dest->isDeclaration() && !Dest->hasDLLImportLinkage()) { 400 // If Dest is external but Src is not: 401 LinkFromSrc = true; 402 LT = Src->getLinkage(); 403 } else if (Src->hasAppendingLinkage() || Dest->hasAppendingLinkage()) { 404 if (Src->getLinkage() != Dest->getLinkage()) 405 return Error(Err, "Linking globals named '" + Src->getName() + 406 "': can only link appending global with another appending global!"); 407 LinkFromSrc = true; // Special cased. 408 LT = Src->getLinkage(); 409 } else if (Src->isWeakForLinker()) { 410 // At this point we know that Dest has LinkOnce, External*, Weak, Common, 411 // or DLL* linkage. 412 if (Dest->hasExternalWeakLinkage() || 413 Dest->hasAvailableExternallyLinkage() || 414 (Dest->hasLinkOnceLinkage() && 415 (Src->hasWeakLinkage() || Src->hasCommonLinkage()))) { 416 LinkFromSrc = true; 417 LT = Src->getLinkage(); 418 } else { 419 LinkFromSrc = false; 420 LT = Dest->getLinkage(); 421 } 422 } else if (Dest->isWeakForLinker()) { 423 // At this point we know that Src has External* or DLL* linkage. 424 if (Src->hasExternalWeakLinkage()) { 425 LinkFromSrc = false; 426 LT = Dest->getLinkage(); 427 } else { 428 LinkFromSrc = true; 429 LT = GlobalValue::ExternalLinkage; 430 } 431 } else { 432 assert((Dest->hasExternalLinkage() || 433 Dest->hasDLLImportLinkage() || 434 Dest->hasDLLExportLinkage() || 435 Dest->hasExternalWeakLinkage()) && 436 (Src->hasExternalLinkage() || 437 Src->hasDLLImportLinkage() || 438 Src->hasDLLExportLinkage() || 439 Src->hasExternalWeakLinkage()) && 440 "Unexpected linkage type!"); 441 return Error(Err, "Linking globals named '" + Src->getName() + 442 "': symbol multiply defined!"); 443 } 444 445 // Check visibility 446 if (Dest && Src->getVisibility() != Dest->getVisibility()) 447 if (!Src->isDeclaration() && !Dest->isDeclaration()) 448 return Error(Err, "Linking globals named '" + Src->getName() + 449 "': symbols have different visibilities!"); 450 return false; 451} 452 453// Insert all of the named mdnoes in Src into the Dest module. 454static void LinkNamedMDNodes(Module *Dest, Module *Src, 455 ValueToValueMapTy &ValueMap) { 456 for (Module::const_named_metadata_iterator I = Src->named_metadata_begin(), 457 E = Src->named_metadata_end(); I != E; ++I) { 458 const NamedMDNode *SrcNMD = I; 459 NamedMDNode *DestNMD = Dest->getOrInsertNamedMetadata(SrcNMD->getName()); 460 // Add Src elements into Dest node. 461 for (unsigned i = 0, e = SrcNMD->getNumOperands(); i != e; ++i) 462 DestNMD->addOperand(cast<MDNode>(MapValue(SrcNMD->getOperand(i), 463 ValueMap, 464 true))); 465 } 466} 467 468// LinkGlobals - Loop through the global variables in the src module and merge 469// them into the dest module. 470static bool LinkGlobals(Module *Dest, const Module *Src, 471 ValueToValueMapTy &ValueMap, 472 std::multimap<std::string, GlobalVariable *> &AppendingVars, 473 std::string *Err) { 474 ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable(); 475 476 // Loop over all of the globals in the src module, mapping them over as we go 477 for (Module::const_global_iterator I = Src->global_begin(), 478 E = Src->global_end(); I != E; ++I) { 479 const GlobalVariable *SGV = I; 480 GlobalValue *DGV = 0; 481 482 // Check to see if may have to link the global with the global, alias or 483 // function. 484 if (SGV->hasName() && !SGV->hasLocalLinkage()) 485 DGV = cast_or_null<GlobalValue>(DestSymTab.lookup(SGV->getName())); 486 487 // If we found a global with the same name in the dest module, but it has 488 // internal linkage, we are really not doing any linkage here. 489 if (DGV && DGV->hasLocalLinkage()) 490 DGV = 0; 491 492 // If types don't agree due to opaque types, try to resolve them. 493 if (DGV && DGV->getType() != SGV->getType()) 494 RecursiveResolveTypes(SGV->getType(), DGV->getType()); 495 496 assert((SGV->hasInitializer() || SGV->hasExternalWeakLinkage() || 497 SGV->hasExternalLinkage() || SGV->hasDLLImportLinkage()) && 498 "Global must either be external or have an initializer!"); 499 500 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 501 bool LinkFromSrc = false; 502 if (GetLinkageResult(DGV, SGV, NewLinkage, LinkFromSrc, Err)) 503 return true; 504 505 if (DGV == 0) { 506 // No linking to be performed, simply create an identical version of the 507 // symbol over in the dest module... the initializer will be filled in 508 // later by LinkGlobalInits. 509 GlobalVariable *NewDGV = 510 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 511 SGV->isConstant(), SGV->getLinkage(), /*init*/0, 512 SGV->getName(), 0, false, 513 SGV->getType()->getAddressSpace()); 514 // Propagate alignment, visibility and section info. 515 CopyGVAttributes(NewDGV, SGV); 516 517 // If the LLVM runtime renamed the global, but it is an externally visible 518 // symbol, DGV must be an existing global with internal linkage. Rename 519 // it. 520 if (!NewDGV->hasLocalLinkage() && NewDGV->getName() != SGV->getName()) 521 ForceRenaming(NewDGV, SGV->getName()); 522 523 // Make sure to remember this mapping. 524 ValueMap[SGV] = NewDGV; 525 526 // Keep track that this is an appending variable. 527 if (SGV->hasAppendingLinkage()) 528 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV)); 529 continue; 530 } 531 532 // If the visibilities of the symbols disagree and the destination is a 533 // prototype, take the visibility of its input. 534 if (DGV->isDeclaration()) 535 DGV->setVisibility(SGV->getVisibility()); 536 537 if (DGV->hasAppendingLinkage()) { 538 // No linking is performed yet. Just insert a new copy of the global, and 539 // keep track of the fact that it is an appending variable in the 540 // AppendingVars map. The name is cleared out so that no linkage is 541 // performed. 542 GlobalVariable *NewDGV = 543 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 544 SGV->isConstant(), SGV->getLinkage(), /*init*/0, 545 "", 0, false, 546 SGV->getType()->getAddressSpace()); 547 548 // Set alignment allowing CopyGVAttributes merge it with alignment of SGV. 549 NewDGV->setAlignment(DGV->getAlignment()); 550 // Propagate alignment, section and visibility info. 551 CopyGVAttributes(NewDGV, SGV); 552 553 // Make sure to remember this mapping... 554 ValueMap[SGV] = NewDGV; 555 556 // Keep track that this is an appending variable... 557 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV)); 558 continue; 559 } 560 561 if (LinkFromSrc) { 562 if (isa<GlobalAlias>(DGV)) 563 return Error(Err, "Global-Alias Collision on '" + SGV->getName() + 564 "': symbol multiple defined"); 565 566 // If the types don't match, and if we are to link from the source, nuke 567 // DGV and create a new one of the appropriate type. Note that the thing 568 // we are replacing may be a function (if a prototype, weak, etc) or a 569 // global variable. 570 GlobalVariable *NewDGV = 571 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 572 SGV->isConstant(), NewLinkage, /*init*/0, 573 DGV->getName(), 0, false, 574 SGV->getType()->getAddressSpace()); 575 576 // Propagate alignment, section, and visibility info. 577 CopyGVAttributes(NewDGV, SGV); 578 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV, 579 DGV->getType())); 580 581 // DGV will conflict with NewDGV because they both had the same 582 // name. We must erase this now so ForceRenaming doesn't assert 583 // because DGV might not have internal linkage. 584 if (GlobalVariable *Var = dyn_cast<GlobalVariable>(DGV)) 585 Var->eraseFromParent(); 586 else 587 cast<Function>(DGV)->eraseFromParent(); 588 589 // If the symbol table renamed the global, but it is an externally visible 590 // symbol, DGV must be an existing global with internal linkage. Rename. 591 if (NewDGV->getName() != SGV->getName() && !NewDGV->hasLocalLinkage()) 592 ForceRenaming(NewDGV, SGV->getName()); 593 594 // Inherit const as appropriate. 595 NewDGV->setConstant(SGV->isConstant()); 596 597 // Make sure to remember this mapping. 598 ValueMap[SGV] = NewDGV; 599 continue; 600 } 601 602 // Not "link from source", keep the one in the DestModule and remap the 603 // input onto it. 604 605 // Special case for const propagation. 606 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) 607 if (DGVar->isDeclaration() && SGV->isConstant() && !DGVar->isConstant()) 608 DGVar->setConstant(true); 609 610 // SGV is global, but DGV is alias. 611 if (isa<GlobalAlias>(DGV)) { 612 // The only valid mappings are: 613 // - SGV is external declaration, which is effectively a no-op. 614 // - SGV is weak, when we just need to throw SGV out. 615 if (!SGV->isDeclaration() && !SGV->isWeakForLinker()) 616 return Error(Err, "Global-Alias Collision on '" + SGV->getName() + 617 "': symbol multiple defined"); 618 } 619 620 // Set calculated linkage 621 DGV->setLinkage(NewLinkage); 622 623 // Make sure to remember this mapping... 624 ValueMap[SGV] = ConstantExpr::getBitCast(DGV, SGV->getType()); 625 } 626 return false; 627} 628 629static GlobalValue::LinkageTypes 630CalculateAliasLinkage(const GlobalValue *SGV, const GlobalValue *DGV) { 631 GlobalValue::LinkageTypes SL = SGV->getLinkage(); 632 GlobalValue::LinkageTypes DL = DGV->getLinkage(); 633 if (SL == GlobalValue::ExternalLinkage || DL == GlobalValue::ExternalLinkage) 634 return GlobalValue::ExternalLinkage; 635 else if (SL == GlobalValue::WeakAnyLinkage || 636 DL == GlobalValue::WeakAnyLinkage) 637 return GlobalValue::WeakAnyLinkage; 638 else if (SL == GlobalValue::WeakODRLinkage || 639 DL == GlobalValue::WeakODRLinkage) 640 return GlobalValue::WeakODRLinkage; 641 else if (SL == GlobalValue::InternalLinkage && 642 DL == GlobalValue::InternalLinkage) 643 return GlobalValue::InternalLinkage; 644 else if (SL == GlobalValue::LinkerPrivateLinkage && 645 DL == GlobalValue::LinkerPrivateLinkage) 646 return GlobalValue::LinkerPrivateLinkage; 647 else if (SL == GlobalValue::LinkerPrivateWeakLinkage && 648 DL == GlobalValue::LinkerPrivateWeakLinkage) 649 return GlobalValue::LinkerPrivateWeakLinkage; 650 else if (SL == GlobalValue::LinkerPrivateWeakDefAutoLinkage && 651 DL == GlobalValue::LinkerPrivateWeakDefAutoLinkage) 652 return GlobalValue::LinkerPrivateWeakDefAutoLinkage; 653 else { 654 assert (SL == GlobalValue::PrivateLinkage && 655 DL == GlobalValue::PrivateLinkage && "Unexpected linkage type"); 656 return GlobalValue::PrivateLinkage; 657 } 658} 659 660// LinkAlias - Loop through the alias in the src module and link them into the 661// dest module. We're assuming, that all functions/global variables were already 662// linked in. 663static bool LinkAlias(Module *Dest, const Module *Src, 664 ValueToValueMapTy &ValueMap, 665 std::string *Err) { 666 // Loop over all alias in the src module 667 for (Module::const_alias_iterator I = Src->alias_begin(), 668 E = Src->alias_end(); I != E; ++I) { 669 const GlobalAlias *SGA = I; 670 const GlobalValue *SAliasee = SGA->getAliasedGlobal(); 671 GlobalAlias *NewGA = NULL; 672 673 // Globals were already linked, thus we can just query ValueMap for variant 674 // of SAliasee in Dest. 675 ValueToValueMapTy::const_iterator VMI = ValueMap.find(SAliasee); 676 assert(VMI != ValueMap.end() && "Aliasee not linked"); 677 GlobalValue* DAliasee = cast<GlobalValue>(VMI->second); 678 GlobalValue* DGV = NULL; 679 680 // Try to find something 'similar' to SGA in destination module. 681 if (!DGV && !SGA->hasLocalLinkage()) { 682 DGV = Dest->getNamedAlias(SGA->getName()); 683 684 // If types don't agree due to opaque types, try to resolve them. 685 if (DGV && DGV->getType() != SGA->getType()) 686 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 687 } 688 689 if (!DGV && !SGA->hasLocalLinkage()) { 690 DGV = Dest->getGlobalVariable(SGA->getName()); 691 692 // If types don't agree due to opaque types, try to resolve them. 693 if (DGV && DGV->getType() != SGA->getType()) 694 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 695 } 696 697 if (!DGV && !SGA->hasLocalLinkage()) { 698 DGV = Dest->getFunction(SGA->getName()); 699 700 // If types don't agree due to opaque types, try to resolve them. 701 if (DGV && DGV->getType() != SGA->getType()) 702 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 703 } 704 705 // No linking to be performed on internal stuff. 706 if (DGV && DGV->hasLocalLinkage()) 707 DGV = NULL; 708 709 if (GlobalAlias *DGA = dyn_cast_or_null<GlobalAlias>(DGV)) { 710 // Types are known to be the same, check whether aliasees equal. As 711 // globals are already linked we just need query ValueMap to find the 712 // mapping. 713 if (DAliasee == DGA->getAliasedGlobal()) { 714 // This is just two copies of the same alias. Propagate linkage, if 715 // necessary. 716 DGA->setLinkage(CalculateAliasLinkage(SGA, DGA)); 717 718 NewGA = DGA; 719 // Proceed to 'common' steps 720 } else 721 return Error(Err, "Alias Collision on '" + SGA->getName()+ 722 "': aliases have different aliasees"); 723 } else if (GlobalVariable *DGVar = dyn_cast_or_null<GlobalVariable>(DGV)) { 724 // The only allowed way is to link alias with external declaration or weak 725 // symbol.. 726 if (DGVar->isDeclaration() || DGVar->isWeakForLinker()) { 727 // But only if aliasee is global too... 728 if (!isa<GlobalVariable>(DAliasee)) 729 return Error(Err, "Global-Alias Collision on '" + SGA->getName() + 730 "': aliasee is not global variable"); 731 732 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 733 SGA->getName(), DAliasee, Dest); 734 CopyGVAttributes(NewGA, SGA); 735 736 // Any uses of DGV need to change to NewGA, with cast, if needed. 737 if (SGA->getType() != DGVar->getType()) 738 DGVar->replaceAllUsesWith(ConstantExpr::getBitCast(NewGA, 739 DGVar->getType())); 740 else 741 DGVar->replaceAllUsesWith(NewGA); 742 743 // DGVar will conflict with NewGA because they both had the same 744 // name. We must erase this now so ForceRenaming doesn't assert 745 // because DGV might not have internal linkage. 746 DGVar->eraseFromParent(); 747 748 // Proceed to 'common' steps 749 } else 750 return Error(Err, "Global-Alias Collision on '" + SGA->getName() + 751 "': symbol multiple defined"); 752 } else if (Function *DF = dyn_cast_or_null<Function>(DGV)) { 753 // The only allowed way is to link alias with external declaration or weak 754 // symbol... 755 if (DF->isDeclaration() || DF->isWeakForLinker()) { 756 // But only if aliasee is function too... 757 if (!isa<Function>(DAliasee)) 758 return Error(Err, "Function-Alias Collision on '" + SGA->getName() + 759 "': aliasee is not function"); 760 761 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 762 SGA->getName(), DAliasee, Dest); 763 CopyGVAttributes(NewGA, SGA); 764 765 // Any uses of DF need to change to NewGA, with cast, if needed. 766 if (SGA->getType() != DF->getType()) 767 DF->replaceAllUsesWith(ConstantExpr::getBitCast(NewGA, 768 DF->getType())); 769 else 770 DF->replaceAllUsesWith(NewGA); 771 772 // DF will conflict with NewGA because they both had the same 773 // name. We must erase this now so ForceRenaming doesn't assert 774 // because DF might not have internal linkage. 775 DF->eraseFromParent(); 776 777 // Proceed to 'common' steps 778 } else 779 return Error(Err, "Function-Alias Collision on '" + SGA->getName() + 780 "': symbol multiple defined"); 781 } else { 782 // No linking to be performed, simply create an identical version of the 783 // alias over in the dest module... 784 Constant *Aliasee = DAliasee; 785 // Fixup aliases to bitcasts. Note that aliases to GEPs are still broken 786 // by this, but aliases to GEPs are broken to a lot of other things, so 787 // it's less important. 788 if (SGA->getType() != DAliasee->getType()) 789 Aliasee = ConstantExpr::getBitCast(DAliasee, SGA->getType()); 790 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 791 SGA->getName(), Aliasee, Dest); 792 CopyGVAttributes(NewGA, SGA); 793 794 // Proceed to 'common' steps 795 } 796 797 assert(NewGA && "No alias was created in destination module!"); 798 799 // If the symbol table renamed the alias, but it is an externally visible 800 // symbol, DGA must be an global value with internal linkage. Rename it. 801 if (NewGA->getName() != SGA->getName() && 802 !NewGA->hasLocalLinkage()) 803 ForceRenaming(NewGA, SGA->getName()); 804 805 // Remember this mapping so uses in the source module get remapped 806 // later by MapValue. 807 ValueMap[SGA] = NewGA; 808 } 809 810 return false; 811} 812 813 814// LinkGlobalInits - Update the initializers in the Dest module now that all 815// globals that may be referenced are in Dest. 816static bool LinkGlobalInits(Module *Dest, const Module *Src, 817 ValueToValueMapTy &ValueMap, 818 std::string *Err) { 819 // Loop over all of the globals in the src module, mapping them over as we go 820 for (Module::const_global_iterator I = Src->global_begin(), 821 E = Src->global_end(); I != E; ++I) { 822 const GlobalVariable *SGV = I; 823 824 if (SGV->hasInitializer()) { // Only process initialized GV's 825 // Figure out what the initializer looks like in the dest module... 826 Constant *SInit = 827 cast<Constant>(MapValue(SGV->getInitializer(), ValueMap, true)); 828 // Grab destination global variable or alias. 829 GlobalValue *DGV = cast<GlobalValue>(ValueMap[SGV]->stripPointerCasts()); 830 831 // If dest if global variable, check that initializers match. 832 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) { 833 if (DGVar->hasInitializer()) { 834 if (SGV->hasExternalLinkage()) { 835 if (DGVar->getInitializer() != SInit) 836 return Error(Err, "Global Variable Collision on '" + 837 SGV->getName() + 838 "': global variables have different initializers"); 839 } else if (DGVar->isWeakForLinker()) { 840 // Nothing is required, mapped values will take the new global 841 // automatically. 842 } else if (SGV->isWeakForLinker()) { 843 // Nothing is required, mapped values will take the new global 844 // automatically. 845 } else if (DGVar->hasAppendingLinkage()) { 846 llvm_unreachable("Appending linkage unimplemented!"); 847 } else { 848 llvm_unreachable("Unknown linkage!"); 849 } 850 } else { 851 // Copy the initializer over now... 852 DGVar->setInitializer(SInit); 853 } 854 } else { 855 // Destination is alias, the only valid situation is when source is 856 // weak. Also, note, that we already checked linkage in LinkGlobals(), 857 // thus we assert here. 858 // FIXME: Should we weaken this assumption, 'dereference' alias and 859 // check for initializer of aliasee? 860 assert(SGV->isWeakForLinker()); 861 } 862 } 863 } 864 return false; 865} 866 867// LinkFunctionProtos - Link the functions together between the two modules, 868// without doing function bodies... this just adds external function prototypes 869// to the Dest function... 870// 871static bool LinkFunctionProtos(Module *Dest, const Module *Src, 872 ValueToValueMapTy &ValueMap, 873 std::string *Err) { 874 ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable(); 875 876 // Loop over all of the functions in the src module, mapping them over 877 for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) { 878 const Function *SF = I; // SrcFunction 879 GlobalValue *DGV = 0; 880 881 // Check to see if may have to link the function with the global, alias or 882 // function. 883 if (SF->hasName() && !SF->hasLocalLinkage()) 884 DGV = cast_or_null<GlobalValue>(DestSymTab.lookup(SF->getName())); 885 886 // If we found a global with the same name in the dest module, but it has 887 // internal linkage, we are really not doing any linkage here. 888 if (DGV && DGV->hasLocalLinkage()) 889 DGV = 0; 890 891 // If types don't agree due to opaque types, try to resolve them. 892 if (DGV && DGV->getType() != SF->getType()) 893 RecursiveResolveTypes(SF->getType(), DGV->getType()); 894 895 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 896 bool LinkFromSrc = false; 897 if (GetLinkageResult(DGV, SF, NewLinkage, LinkFromSrc, Err)) 898 return true; 899 900 // If there is no linkage to be performed, just bring over SF without 901 // modifying it. 902 if (DGV == 0) { 903 // Function does not already exist, simply insert an function signature 904 // identical to SF into the dest module. 905 Function *NewDF = Function::Create(SF->getFunctionType(), 906 SF->getLinkage(), 907 SF->getName(), Dest); 908 CopyGVAttributes(NewDF, SF); 909 910 // If the LLVM runtime renamed the function, but it is an externally 911 // visible symbol, DF must be an existing function with internal linkage. 912 // Rename it. 913 if (!NewDF->hasLocalLinkage() && NewDF->getName() != SF->getName()) 914 ForceRenaming(NewDF, SF->getName()); 915 916 // ... and remember this mapping... 917 ValueMap[SF] = NewDF; 918 continue; 919 } 920 921 // If the visibilities of the symbols disagree and the destination is a 922 // prototype, take the visibility of its input. 923 if (DGV->isDeclaration()) 924 DGV->setVisibility(SF->getVisibility()); 925 926 if (LinkFromSrc) { 927 if (isa<GlobalAlias>(DGV)) 928 return Error(Err, "Function-Alias Collision on '" + SF->getName() + 929 "': symbol multiple defined"); 930 931 // We have a definition of the same name but different type in the 932 // source module. Copy the prototype to the destination and replace 933 // uses of the destination's prototype with the new prototype. 934 Function *NewDF = Function::Create(SF->getFunctionType(), NewLinkage, 935 SF->getName(), Dest); 936 CopyGVAttributes(NewDF, SF); 937 938 // Any uses of DF need to change to NewDF, with cast 939 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, 940 DGV->getType())); 941 942 // DF will conflict with NewDF because they both had the same. We must 943 // erase this now so ForceRenaming doesn't assert because DF might 944 // not have internal linkage. 945 if (GlobalVariable *Var = dyn_cast<GlobalVariable>(DGV)) 946 Var->eraseFromParent(); 947 else 948 cast<Function>(DGV)->eraseFromParent(); 949 950 // If the symbol table renamed the function, but it is an externally 951 // visible symbol, DF must be an existing function with internal 952 // linkage. Rename it. 953 if (NewDF->getName() != SF->getName() && !NewDF->hasLocalLinkage()) 954 ForceRenaming(NewDF, SF->getName()); 955 956 // Remember this mapping so uses in the source module get remapped 957 // later by MapValue. 958 ValueMap[SF] = NewDF; 959 continue; 960 } 961 962 // Not "link from source", keep the one in the DestModule and remap the 963 // input onto it. 964 965 if (isa<GlobalAlias>(DGV)) { 966 // The only valid mappings are: 967 // - SF is external declaration, which is effectively a no-op. 968 // - SF is weak, when we just need to throw SF out. 969 if (!SF->isDeclaration() && !SF->isWeakForLinker()) 970 return Error(Err, "Function-Alias Collision on '" + SF->getName() + 971 "': symbol multiple defined"); 972 } 973 974 // Set calculated linkage 975 DGV->setLinkage(NewLinkage); 976 977 // Make sure to remember this mapping. 978 ValueMap[SF] = ConstantExpr::getBitCast(DGV, SF->getType()); 979 } 980 return false; 981} 982 983// LinkFunctionBody - Copy the source function over into the dest function and 984// fix up references to values. At this point we know that Dest is an external 985// function, and that Src is not. 986static bool LinkFunctionBody(Function *Dest, Function *Src, 987 ValueToValueMapTy &ValueMap, 988 std::string *Err) { 989 assert(Src && Dest && Dest->isDeclaration() && !Src->isDeclaration()); 990 991 // Go through and convert function arguments over, remembering the mapping. 992 Function::arg_iterator DI = Dest->arg_begin(); 993 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 994 I != E; ++I, ++DI) { 995 DI->setName(I->getName()); // Copy the name information over... 996 997 // Add a mapping to our local map 998 ValueMap[I] = DI; 999 } 1000 1001 // Splice the body of the source function into the dest function. 1002 Dest->getBasicBlockList().splice(Dest->end(), Src->getBasicBlockList()); 1003 1004 // At this point, all of the instructions and values of the function are now 1005 // copied over. The only problem is that they are still referencing values in 1006 // the Source function as operands. Loop through all of the operands of the 1007 // functions and patch them up to point to the local versions... 1008 // 1009 // This is the same as RemapInstruction, except that it avoids remapping 1010 // instruction and basic block operands. 1011 // 1012 for (Function::iterator BB = Dest->begin(), BE = Dest->end(); BB != BE; ++BB) 1013 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) { 1014 // Remap operands. 1015 for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end(); 1016 OI != OE; ++OI) 1017 if (!isa<Instruction>(*OI) && !isa<BasicBlock>(*OI)) 1018 *OI = MapValue(*OI, ValueMap, true); 1019 1020 // Remap attached metadata. 1021 SmallVector<std::pair<unsigned, MDNode *>, 4> MDs; 1022 I->getAllMetadata(MDs); 1023 for (SmallVectorImpl<std::pair<unsigned, MDNode *> >::iterator 1024 MI = MDs.begin(), ME = MDs.end(); MI != ME; ++MI) { 1025 Value *Old = MI->second; 1026 if (!isa<Instruction>(Old) && !isa<BasicBlock>(Old)) { 1027 Value *New = MapValue(Old, ValueMap, true); 1028 if (New != Old) 1029 I->setMetadata(MI->first, cast<MDNode>(New)); 1030 } 1031 } 1032 } 1033 1034 // There is no need to map the arguments anymore. 1035 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 1036 I != E; ++I) 1037 ValueMap.erase(I); 1038 1039 return false; 1040} 1041 1042 1043// LinkFunctionBodies - Link in the function bodies that are defined in the 1044// source module into the DestModule. This consists basically of copying the 1045// function over and fixing up references to values. 1046static bool LinkFunctionBodies(Module *Dest, Module *Src, 1047 ValueToValueMapTy &ValueMap, 1048 std::string *Err) { 1049 1050 // Loop over all of the functions in the src module, mapping them over as we 1051 // go 1052 for (Module::iterator SF = Src->begin(), E = Src->end(); SF != E; ++SF) { 1053 if (!SF->isDeclaration()) { // No body if function is external 1054 Function *DF = dyn_cast<Function>(ValueMap[SF]); // Destination function 1055 1056 // DF not external SF external? 1057 if (DF && DF->isDeclaration()) 1058 // Only provide the function body if there isn't one already. 1059 if (LinkFunctionBody(DF, SF, ValueMap, Err)) 1060 return true; 1061 } 1062 } 1063 return false; 1064} 1065 1066// LinkAppendingVars - If there were any appending global variables, link them 1067// together now. Return true on error. 1068static bool LinkAppendingVars(Module *M, 1069 std::multimap<std::string, GlobalVariable *> &AppendingVars, 1070 std::string *ErrorMsg) { 1071 if (AppendingVars.empty()) return false; // Nothing to do. 1072 1073 // Loop over the multimap of appending vars, processing any variables with the 1074 // same name, forming a new appending global variable with both of the 1075 // initializers merged together, then rewrite references to the old variables 1076 // and delete them. 1077 std::vector<Constant*> Inits; 1078 while (AppendingVars.size() > 1) { 1079 // Get the first two elements in the map... 1080 std::multimap<std::string, 1081 GlobalVariable*>::iterator Second = AppendingVars.begin(), First=Second++; 1082 1083 // If the first two elements are for different names, there is no pair... 1084 // Otherwise there is a pair, so link them together... 1085 if (First->first == Second->first) { 1086 GlobalVariable *G1 = First->second, *G2 = Second->second; 1087 const ArrayType *T1 = cast<ArrayType>(G1->getType()->getElementType()); 1088 const ArrayType *T2 = cast<ArrayType>(G2->getType()->getElementType()); 1089 1090 // Check to see that they two arrays agree on type... 1091 if (T1->getElementType() != T2->getElementType()) 1092 return Error(ErrorMsg, 1093 "Appending variables with different element types need to be linked!"); 1094 if (G1->isConstant() != G2->isConstant()) 1095 return Error(ErrorMsg, 1096 "Appending variables linked with different const'ness!"); 1097 1098 if (G1->getAlignment() != G2->getAlignment()) 1099 return Error(ErrorMsg, 1100 "Appending variables with different alignment need to be linked!"); 1101 1102 if (G1->getVisibility() != G2->getVisibility()) 1103 return Error(ErrorMsg, 1104 "Appending variables with different visibility need to be linked!"); 1105 1106 if (G1->getSection() != G2->getSection()) 1107 return Error(ErrorMsg, 1108 "Appending variables with different section name need to be linked!"); 1109 1110 unsigned NewSize = T1->getNumElements() + T2->getNumElements(); 1111 ArrayType *NewType = ArrayType::get(T1->getElementType(), 1112 NewSize); 1113 1114 G1->setName(""); // Clear G1's name in case of a conflict! 1115 1116 // Create the new global variable... 1117 GlobalVariable *NG = 1118 new GlobalVariable(*M, NewType, G1->isConstant(), G1->getLinkage(), 1119 /*init*/0, First->first, 0, G1->isThreadLocal(), 1120 G1->getType()->getAddressSpace()); 1121 1122 // Propagate alignment, visibility and section info. 1123 CopyGVAttributes(NG, G1); 1124 1125 // Merge the initializer... 1126 Inits.reserve(NewSize); 1127 if (ConstantArray *I = dyn_cast<ConstantArray>(G1->getInitializer())) { 1128 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i) 1129 Inits.push_back(I->getOperand(i)); 1130 } else { 1131 assert(isa<ConstantAggregateZero>(G1->getInitializer())); 1132 Constant *CV = Constant::getNullValue(T1->getElementType()); 1133 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i) 1134 Inits.push_back(CV); 1135 } 1136 if (ConstantArray *I = dyn_cast<ConstantArray>(G2->getInitializer())) { 1137 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i) 1138 Inits.push_back(I->getOperand(i)); 1139 } else { 1140 assert(isa<ConstantAggregateZero>(G2->getInitializer())); 1141 Constant *CV = Constant::getNullValue(T2->getElementType()); 1142 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i) 1143 Inits.push_back(CV); 1144 } 1145 NG->setInitializer(ConstantArray::get(NewType, Inits)); 1146 Inits.clear(); 1147 1148 // Replace any uses of the two global variables with uses of the new 1149 // global... 1150 1151 // FIXME: This should rewrite simple/straight-forward uses such as 1152 // getelementptr instructions to not use the Cast! 1153 G1->replaceAllUsesWith(ConstantExpr::getBitCast(NG, 1154 G1->getType())); 1155 G2->replaceAllUsesWith(ConstantExpr::getBitCast(NG, 1156 G2->getType())); 1157 1158 // Remove the two globals from the module now... 1159 M->getGlobalList().erase(G1); 1160 M->getGlobalList().erase(G2); 1161 1162 // Put the new global into the AppendingVars map so that we can handle 1163 // linking of more than two vars... 1164 Second->second = NG; 1165 } 1166 AppendingVars.erase(First); 1167 } 1168 1169 return false; 1170} 1171 1172static bool ResolveAliases(Module *Dest) { 1173 for (Module::alias_iterator I = Dest->alias_begin(), E = Dest->alias_end(); 1174 I != E; ++I) 1175 // We can't sue resolveGlobalAlias here because we need to preserve 1176 // bitcasts and GEPs. 1177 if (const Constant *C = I->getAliasee()) { 1178 while (dyn_cast<GlobalAlias>(C)) 1179 C = cast<GlobalAlias>(C)->getAliasee(); 1180 const GlobalValue *GV = dyn_cast<GlobalValue>(C); 1181 if (C != I && !(GV && GV->isDeclaration())) 1182 I->replaceAllUsesWith(const_cast<Constant*>(C)); 1183 } 1184 1185 return false; 1186} 1187 1188// LinkModules - This function links two modules together, with the resulting 1189// left module modified to be the composite of the two input modules. If an 1190// error occurs, true is returned and ErrorMsg (if not null) is set to indicate 1191// the problem. Upon failure, the Dest module could be in a modified state, and 1192// shouldn't be relied on to be consistent. 1193bool 1194Linker::LinkModules(Module *Dest, Module *Src, std::string *ErrorMsg) { 1195 assert(Dest != 0 && "Invalid Destination module"); 1196 assert(Src != 0 && "Invalid Source Module"); 1197 1198 if (Dest->getDataLayout().empty()) { 1199 if (!Src->getDataLayout().empty()) { 1200 Dest->setDataLayout(Src->getDataLayout()); 1201 } else { 1202 std::string DataLayout; 1203 1204 if (Dest->getEndianness() == Module::AnyEndianness) { 1205 if (Src->getEndianness() == Module::BigEndian) 1206 DataLayout.append("E"); 1207 else if (Src->getEndianness() == Module::LittleEndian) 1208 DataLayout.append("e"); 1209 } 1210 1211 if (Dest->getPointerSize() == Module::AnyPointerSize) { 1212 if (Src->getPointerSize() == Module::Pointer64) 1213 DataLayout.append(DataLayout.length() == 0 ? "p:64:64" : "-p:64:64"); 1214 else if (Src->getPointerSize() == Module::Pointer32) 1215 DataLayout.append(DataLayout.length() == 0 ? "p:32:32" : "-p:32:32"); 1216 } 1217 Dest->setDataLayout(DataLayout); 1218 } 1219 } 1220 1221 // Copy the target triple from the source to dest if the dest's is empty. 1222 if (Dest->getTargetTriple().empty() && !Src->getTargetTriple().empty()) 1223 Dest->setTargetTriple(Src->getTargetTriple()); 1224 1225 if (!Src->getDataLayout().empty() && !Dest->getDataLayout().empty() && 1226 Src->getDataLayout() != Dest->getDataLayout()) 1227 errs() << "WARNING: Linking two modules of different data layouts!\n"; 1228 if (!Src->getTargetTriple().empty() && 1229 Dest->getTargetTriple() != Src->getTargetTriple()) 1230 errs() << "WARNING: Linking two modules of different target triples!\n"; 1231 1232 // Append the module inline asm string. 1233 if (!Src->getModuleInlineAsm().empty()) { 1234 if (Dest->getModuleInlineAsm().empty()) 1235 Dest->setModuleInlineAsm(Src->getModuleInlineAsm()); 1236 else 1237 Dest->setModuleInlineAsm(Dest->getModuleInlineAsm()+"\n"+ 1238 Src->getModuleInlineAsm()); 1239 } 1240 1241 // Update the destination module's dependent libraries list with the libraries 1242 // from the source module. There's no opportunity for duplicates here as the 1243 // Module ensures that duplicate insertions are discarded. 1244 for (Module::lib_iterator SI = Src->lib_begin(), SE = Src->lib_end(); 1245 SI != SE; ++SI) 1246 Dest->addLibrary(*SI); 1247 1248 // LinkTypes - Go through the symbol table of the Src module and see if any 1249 // types are named in the src module that are not named in the Dst module. 1250 // Make sure there are no type name conflicts. 1251 if (LinkTypes(Dest, Src, ErrorMsg)) 1252 return true; 1253 1254 // ValueMap - Mapping of values from what they used to be in Src, to what they 1255 // are now in Dest. ValueToValueMapTy is a ValueMap, which involves some 1256 // overhead due to the use of Value handles which the Linker doesn't actually 1257 // need, but this allows us to reuse the ValueMapper code. 1258 ValueToValueMapTy ValueMap; 1259 1260 // AppendingVars - Keep track of global variables in the destination module 1261 // with appending linkage. After the module is linked together, they are 1262 // appended and the module is rewritten. 1263 std::multimap<std::string, GlobalVariable *> AppendingVars; 1264 for (Module::global_iterator I = Dest->global_begin(), E = Dest->global_end(); 1265 I != E; ++I) { 1266 // Add all of the appending globals already in the Dest module to 1267 // AppendingVars. 1268 if (I->hasAppendingLinkage()) 1269 AppendingVars.insert(std::make_pair(I->getName(), I)); 1270 } 1271 1272 // Insert all of the globals in src into the Dest module... without linking 1273 // initializers (which could refer to functions not yet mapped over). 1274 if (LinkGlobals(Dest, Src, ValueMap, AppendingVars, ErrorMsg)) 1275 return true; 1276 1277 // Link the functions together between the two modules, without doing function 1278 // bodies... this just adds external function prototypes to the Dest 1279 // function... We do this so that when we begin processing function bodies, 1280 // all of the global values that may be referenced are available in our 1281 // ValueMap. 1282 if (LinkFunctionProtos(Dest, Src, ValueMap, ErrorMsg)) 1283 return true; 1284 1285 // If there were any alias, link them now. We really need to do this now, 1286 // because all of the aliases that may be referenced need to be available in 1287 // ValueMap 1288 if (LinkAlias(Dest, Src, ValueMap, ErrorMsg)) return true; 1289 1290 // Update the initializers in the Dest module now that all globals that may 1291 // be referenced are in Dest. 1292 if (LinkGlobalInits(Dest, Src, ValueMap, ErrorMsg)) return true; 1293 1294 // Link in the function bodies that are defined in the source module into the 1295 // DestModule. This consists basically of copying the function over and 1296 // fixing up references to values. 1297 if (LinkFunctionBodies(Dest, Src, ValueMap, ErrorMsg)) return true; 1298 1299 // If there were any appending global variables, link them together now. 1300 if (LinkAppendingVars(Dest, AppendingVars, ErrorMsg)) return true; 1301 1302 // Resolve all uses of aliases with aliasees 1303 if (ResolveAliases(Dest)) return true; 1304 1305 // Remap all of the named mdnoes in Src into the Dest module. We do this 1306 // after linking GlobalValues so that MDNodes that reference GlobalValues 1307 // are properly remapped. 1308 LinkNamedMDNodes(Dest, Src, ValueMap); 1309 1310 // If the source library's module id is in the dependent library list of the 1311 // destination library, remove it since that module is now linked in. 1312 sys::Path modId; 1313 modId.set(Src->getModuleIdentifier()); 1314 if (!modId.isEmpty()) 1315 Dest->removeLibrary(modId.getBasename()); 1316 1317 return false; 1318} 1319 1320// vim: sw=2 1321