LinkModules.cpp revision ba7c38c36adb65d66c129270b2813fd2167488ed
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/Support/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 /// insert - This returns true if the pointer was new to the set, false if it 101 /// was already in the set. 102 bool insert(const Type *Src, const Type *Dst) { 103 if (!TheMap.insert(std::make_pair(Src, PATypeHolder(Dst))).second) 104 return false; // Already in map. 105 if (Src->isAbstract()) 106 Src->addAbstractTypeUser(this); 107 return true; 108 } 109 110protected: 111 /// refineAbstractType - The callback method invoked when an abstract type is 112 /// resolved to another type. An object must override this method to update 113 /// its internal state to reference NewType instead of OldType. 114 /// 115 virtual void refineAbstractType(const DerivedType *OldTy, 116 const Type *NewTy) { 117 TheMapTy::iterator I = TheMap.find(OldTy); 118 const Type *DstTy = I->second; 119 120 TheMap.erase(I); 121 if (OldTy->isAbstract()) 122 OldTy->removeAbstractTypeUser(this); 123 124 // Don't reinsert into the map if the key is concrete now. 125 if (NewTy->isAbstract()) 126 insert(NewTy, DstTy); 127 } 128 129 /// The other case which AbstractTypeUsers must be aware of is when a type 130 /// makes the transition from being abstract (where it has clients on it's 131 /// AbstractTypeUsers list) to concrete (where it does not). This method 132 /// notifies ATU's when this occurs for a type. 133 virtual void typeBecameConcrete(const DerivedType *AbsTy) { 134 TheMap.erase(AbsTy); 135 AbsTy->removeAbstractTypeUser(this); 136 } 137 138 // for debugging... 139 virtual void dump() const { 140 dbgs() << "AbstractTypeSet!\n"; 141 } 142}; 143} 144 145 146// RecursiveResolveTypes - This is just like ResolveTypes, except that it 147// recurses down into derived types, merging the used types if the parent types 148// are compatible. 149static bool RecursiveResolveTypesI(const Type *DstTy, const Type *SrcTy, 150 LinkerTypeMap &Pointers) { 151 if (DstTy == SrcTy) return false; // If already equal, noop 152 153 // If we found our opaque type, resolve it now! 154 if (DstTy->isOpaqueTy() || SrcTy->isOpaqueTy()) 155 return ResolveTypes(DstTy, SrcTy); 156 157 // Two types cannot be resolved together if they are of different primitive 158 // type. For example, we cannot resolve an int to a float. 159 if (DstTy->getTypeID() != SrcTy->getTypeID()) return true; 160 161 // If neither type is abstract, then they really are just different types. 162 if (!DstTy->isAbstract() && !SrcTy->isAbstract()) 163 return true; 164 165 // Otherwise, resolve the used type used by this derived type... 166 switch (DstTy->getTypeID()) { 167 default: 168 return true; 169 case Type::FunctionTyID: { 170 const FunctionType *DstFT = cast<FunctionType>(DstTy); 171 const FunctionType *SrcFT = cast<FunctionType>(SrcTy); 172 if (DstFT->isVarArg() != SrcFT->isVarArg() || 173 DstFT->getNumContainedTypes() != SrcFT->getNumContainedTypes()) 174 return true; 175 176 // Use TypeHolder's so recursive resolution won't break us. 177 PATypeHolder ST(SrcFT), DT(DstFT); 178 for (unsigned i = 0, e = DstFT->getNumContainedTypes(); i != e; ++i) { 179 const Type *SE = ST->getContainedType(i), *DE = DT->getContainedType(i); 180 if (SE != DE && RecursiveResolveTypesI(DE, SE, Pointers)) 181 return true; 182 } 183 return false; 184 } 185 case Type::StructTyID: { 186 const StructType *DstST = cast<StructType>(DstTy); 187 const StructType *SrcST = cast<StructType>(SrcTy); 188 if (DstST->getNumContainedTypes() != SrcST->getNumContainedTypes()) 189 return true; 190 191 PATypeHolder ST(SrcST), DT(DstST); 192 for (unsigned i = 0, e = DstST->getNumContainedTypes(); i != e; ++i) { 193 const Type *SE = ST->getContainedType(i), *DE = DT->getContainedType(i); 194 if (SE != DE && RecursiveResolveTypesI(DE, SE, Pointers)) 195 return true; 196 } 197 return false; 198 } 199 case Type::ArrayTyID: { 200 const ArrayType *DAT = cast<ArrayType>(DstTy); 201 const ArrayType *SAT = cast<ArrayType>(SrcTy); 202 if (DAT->getNumElements() != SAT->getNumElements()) return true; 203 return RecursiveResolveTypesI(DAT->getElementType(), SAT->getElementType(), 204 Pointers); 205 } 206 case Type::VectorTyID: { 207 const VectorType *DVT = cast<VectorType>(DstTy); 208 const VectorType *SVT = cast<VectorType>(SrcTy); 209 if (DVT->getNumElements() != SVT->getNumElements()) return true; 210 return RecursiveResolveTypesI(DVT->getElementType(), SVT->getElementType(), 211 Pointers); 212 } 213 case Type::PointerTyID: { 214 const PointerType *DstPT = cast<PointerType>(DstTy); 215 const PointerType *SrcPT = cast<PointerType>(SrcTy); 216 217 if (DstPT->getAddressSpace() != SrcPT->getAddressSpace()) 218 return true; 219 220 // If this is a pointer type, check to see if we have already seen it. If 221 // so, we are in a recursive branch. Cut off the search now. We cannot use 222 // an associative container for this search, because the type pointers (keys 223 // in the container) change whenever types get resolved. 224 if (SrcPT->isAbstract()) 225 if (const Type *ExistingDestTy = Pointers.lookup(SrcPT)) 226 return ExistingDestTy != DstPT; 227 228 if (DstPT->isAbstract()) 229 if (const Type *ExistingSrcTy = Pointers.lookup(DstPT)) 230 return ExistingSrcTy != SrcPT; 231 // Otherwise, add the current pointers to the vector to stop recursion on 232 // this pair. 233 if (DstPT->isAbstract()) 234 Pointers.insert(DstPT, SrcPT); 235 if (SrcPT->isAbstract()) 236 Pointers.insert(SrcPT, DstPT); 237 238 return RecursiveResolveTypesI(DstPT->getElementType(), 239 SrcPT->getElementType(), Pointers); 240 } 241 } 242} 243 244static bool RecursiveResolveTypes(const Type *DestTy, const Type *SrcTy) { 245 LinkerTypeMap PointerTypes; 246 return RecursiveResolveTypesI(DestTy, SrcTy, PointerTypes); 247} 248 249 250// LinkTypes - Go through the symbol table of the Src module and see if any 251// types are named in the src module that are not named in the Dst module. 252// Make sure there are no type name conflicts. 253static bool LinkTypes(Module *Dest, const Module *Src, std::string *Err) { 254 TypeSymbolTable *DestST = &Dest->getTypeSymbolTable(); 255 const TypeSymbolTable *SrcST = &Src->getTypeSymbolTable(); 256 257 // Look for a type plane for Type's... 258 TypeSymbolTable::const_iterator TI = SrcST->begin(); 259 TypeSymbolTable::const_iterator TE = SrcST->end(); 260 if (TI == TE) return false; // No named types, do nothing. 261 262 // Some types cannot be resolved immediately because they depend on other 263 // types being resolved to each other first. This contains a list of types we 264 // are waiting to recheck. 265 std::vector<std::string> DelayedTypesToResolve; 266 267 for ( ; TI != TE; ++TI ) { 268 const std::string &Name = TI->first; 269 const Type *RHS = TI->second; 270 271 // Check to see if this type name is already in the dest module. 272 Type *Entry = DestST->lookup(Name); 273 274 // If the name is just in the source module, bring it over to the dest. 275 if (Entry == 0) { 276 if (!Name.empty()) 277 DestST->insert(Name, const_cast<Type*>(RHS)); 278 } else if (ResolveTypes(Entry, RHS)) { 279 // They look different, save the types 'till later to resolve. 280 DelayedTypesToResolve.push_back(Name); 281 } 282 } 283 284 // Iteratively resolve types while we can... 285 while (!DelayedTypesToResolve.empty()) { 286 // Loop over all of the types, attempting to resolve them if possible... 287 unsigned OldSize = DelayedTypesToResolve.size(); 288 289 // Try direct resolution by name... 290 for (unsigned i = 0; i != DelayedTypesToResolve.size(); ++i) { 291 const std::string &Name = DelayedTypesToResolve[i]; 292 Type *T1 = SrcST->lookup(Name); 293 Type *T2 = DestST->lookup(Name); 294 if (!ResolveTypes(T2, T1)) { 295 // We are making progress! 296 DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i); 297 --i; 298 } 299 } 300 301 // Did we not eliminate any types? 302 if (DelayedTypesToResolve.size() == OldSize) { 303 // Attempt to resolve subelements of types. This allows us to merge these 304 // two types: { int* } and { opaque* } 305 for (unsigned i = 0, e = DelayedTypesToResolve.size(); i != e; ++i) { 306 const std::string &Name = DelayedTypesToResolve[i]; 307 if (!RecursiveResolveTypes(SrcST->lookup(Name), DestST->lookup(Name))) { 308 // We are making progress! 309 DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i); 310 311 // Go back to the main loop, perhaps we can resolve directly by name 312 // now... 313 break; 314 } 315 } 316 317 // If we STILL cannot resolve the types, then there is something wrong. 318 if (DelayedTypesToResolve.size() == OldSize) { 319 // Remove the symbol name from the destination. 320 DelayedTypesToResolve.pop_back(); 321 } 322 } 323 } 324 325 326 return false; 327} 328 329/// ForceRenaming - The LLVM SymbolTable class autorenames globals that conflict 330/// in the symbol table. This is good for all clients except for us. Go 331/// through the trouble to force this back. 332static void ForceRenaming(GlobalValue *GV, const std::string &Name) { 333 assert(GV->getName() != Name && "Can't force rename to self"); 334 ValueSymbolTable &ST = GV->getParent()->getValueSymbolTable(); 335 336 // If there is a conflict, rename the conflict. 337 if (GlobalValue *ConflictGV = cast_or_null<GlobalValue>(ST.lookup(Name))) { 338 assert(ConflictGV->hasLocalLinkage() && 339 "Not conflicting with a static global, should link instead!"); 340 GV->takeName(ConflictGV); 341 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed 342 assert(ConflictGV->getName() != Name && "ForceRenaming didn't work"); 343 } else { 344 GV->setName(Name); // Force the name back 345 } 346} 347 348/// CopyGVAttributes - copy additional attributes (those not needed to construct 349/// a GlobalValue) from the SrcGV to the DestGV. 350static void CopyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) { 351 // Use the maximum alignment, rather than just copying the alignment of SrcGV. 352 unsigned Alignment = std::max(DestGV->getAlignment(), SrcGV->getAlignment()); 353 DestGV->copyAttributesFrom(SrcGV); 354 DestGV->setAlignment(Alignment); 355} 356 357/// GetLinkageResult - This analyzes the two global values and determines what 358/// the result will look like in the destination module. In particular, it 359/// computes the resultant linkage type, computes whether the global in the 360/// source should be copied over to the destination (replacing the existing 361/// one), and computes whether this linkage is an error or not. It also performs 362/// visibility checks: we cannot link together two symbols with different 363/// visibilities. 364static bool GetLinkageResult(GlobalValue *Dest, const GlobalValue *Src, 365 GlobalValue::LinkageTypes <, bool &LinkFromSrc, 366 std::string *Err) { 367 assert((!Dest || !Src->hasLocalLinkage()) && 368 "If Src has internal linkage, Dest shouldn't be set!"); 369 if (!Dest) { 370 // Linking something to nothing. 371 LinkFromSrc = true; 372 LT = Src->getLinkage(); 373 } else if (Src->isDeclaration()) { 374 // If Src is external or if both Src & Dest are external.. Just link the 375 // external globals, we aren't adding anything. 376 if (Src->hasDLLImportLinkage()) { 377 // If one of GVs has DLLImport linkage, result should be dllimport'ed. 378 if (Dest->isDeclaration()) { 379 LinkFromSrc = true; 380 LT = Src->getLinkage(); 381 } 382 } else if (Dest->hasExternalWeakLinkage()) { 383 // If the Dest is weak, use the source linkage. 384 LinkFromSrc = true; 385 LT = Src->getLinkage(); 386 } else { 387 LinkFromSrc = false; 388 LT = Dest->getLinkage(); 389 } 390 } else if (Dest->isDeclaration() && !Dest->hasDLLImportLinkage()) { 391 // If Dest is external but Src is not: 392 LinkFromSrc = true; 393 LT = Src->getLinkage(); 394 } else if (Src->hasAppendingLinkage() || Dest->hasAppendingLinkage()) { 395 if (Src->getLinkage() != Dest->getLinkage()) 396 return Error(Err, "Linking globals named '" + Src->getName() + 397 "': can only link appending global with another appending global!"); 398 LinkFromSrc = true; // Special cased. 399 LT = Src->getLinkage(); 400 } else if (Src->isWeakForLinker()) { 401 // At this point we know that Dest has LinkOnce, External*, Weak, Common, 402 // or DLL* linkage. 403 if (Dest->hasExternalWeakLinkage() || 404 Dest->hasAvailableExternallyLinkage() || 405 (Dest->hasLinkOnceLinkage() && 406 (Src->hasWeakLinkage() || Src->hasCommonLinkage()))) { 407 LinkFromSrc = true; 408 LT = Src->getLinkage(); 409 } else { 410 LinkFromSrc = false; 411 LT = Dest->getLinkage(); 412 } 413 } else if (Dest->isWeakForLinker()) { 414 // At this point we know that Src has External* or DLL* linkage. 415 if (Src->hasExternalWeakLinkage()) { 416 LinkFromSrc = false; 417 LT = Dest->getLinkage(); 418 } else { 419 LinkFromSrc = true; 420 LT = GlobalValue::ExternalLinkage; 421 } 422 } else { 423 assert((Dest->hasExternalLinkage() || 424 Dest->hasDLLImportLinkage() || 425 Dest->hasDLLExportLinkage() || 426 Dest->hasExternalWeakLinkage()) && 427 (Src->hasExternalLinkage() || 428 Src->hasDLLImportLinkage() || 429 Src->hasDLLExportLinkage() || 430 Src->hasExternalWeakLinkage()) && 431 "Unexpected linkage type!"); 432 return Error(Err, "Linking globals named '" + Src->getName() + 433 "': symbol multiply defined!"); 434 } 435 436 // Check visibility 437 if (Dest && Src->getVisibility() != Dest->getVisibility()) 438 if (!Src->isDeclaration() && !Dest->isDeclaration()) 439 return Error(Err, "Linking globals named '" + Src->getName() + 440 "': symbols have different visibilities!"); 441 return false; 442} 443 444// Insert all of the named mdnoes in Src into the Dest module. 445static void LinkNamedMDNodes(Module *Dest, Module *Src, 446 ValueToValueMapTy &ValueMap) { 447 for (Module::const_named_metadata_iterator I = Src->named_metadata_begin(), 448 E = Src->named_metadata_end(); I != E; ++I) { 449 const NamedMDNode *SrcNMD = I; 450 NamedMDNode *DestNMD = Dest->getOrInsertNamedMetadata(SrcNMD->getName()); 451 // Add Src elements into Dest node. 452 for (unsigned i = 0, e = SrcNMD->getNumOperands(); i != e; ++i) 453 DestNMD->addOperand(cast<MDNode>(MapValue(SrcNMD->getOperand(i), 454 ValueMap))); 455 } 456} 457 458// LinkGlobals - Loop through the global variables in the src module and merge 459// them into the dest module. 460static bool LinkGlobals(Module *Dest, const Module *Src, 461 ValueToValueMapTy &ValueMap, 462 std::multimap<std::string, GlobalVariable *> &AppendingVars, 463 std::string *Err) { 464 ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable(); 465 466 // Loop over all of the globals in the src module, mapping them over as we go 467 for (Module::const_global_iterator I = Src->global_begin(), 468 E = Src->global_end(); I != E; ++I) { 469 const GlobalVariable *SGV = I; 470 GlobalValue *DGV = 0; 471 472 // Check to see if may have to link the global with the global, alias or 473 // function. 474 if (SGV->hasName() && !SGV->hasLocalLinkage()) 475 DGV = cast_or_null<GlobalValue>(DestSymTab.lookup(SGV->getName())); 476 477 // If we found a global with the same name in the dest module, but it has 478 // internal linkage, we are really not doing any linkage here. 479 if (DGV && DGV->hasLocalLinkage()) 480 DGV = 0; 481 482 // If types don't agree due to opaque types, try to resolve them. 483 if (DGV && DGV->getType() != SGV->getType()) 484 RecursiveResolveTypes(SGV->getType(), DGV->getType()); 485 486 assert((SGV->hasInitializer() || SGV->hasExternalWeakLinkage() || 487 SGV->hasExternalLinkage() || SGV->hasDLLImportLinkage()) && 488 "Global must either be external or have an initializer!"); 489 490 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 491 bool LinkFromSrc = false; 492 if (GetLinkageResult(DGV, SGV, NewLinkage, LinkFromSrc, Err)) 493 return true; 494 495 if (DGV == 0) { 496 // No linking to be performed, simply create an identical version of the 497 // symbol over in the dest module... the initializer will be filled in 498 // later by LinkGlobalInits. 499 GlobalVariable *NewDGV = 500 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 501 SGV->isConstant(), SGV->getLinkage(), /*init*/0, 502 SGV->getName(), 0, false, 503 SGV->getType()->getAddressSpace()); 504 // Propagate alignment, visibility and section info. 505 CopyGVAttributes(NewDGV, SGV); 506 507 // If the LLVM runtime renamed the global, but it is an externally visible 508 // symbol, DGV must be an existing global with internal linkage. Rename 509 // it. 510 if (!NewDGV->hasLocalLinkage() && NewDGV->getName() != SGV->getName()) 511 ForceRenaming(NewDGV, SGV->getName()); 512 513 // Make sure to remember this mapping. 514 ValueMap[SGV] = NewDGV; 515 516 // Keep track that this is an appending variable. 517 if (SGV->hasAppendingLinkage()) 518 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV)); 519 continue; 520 } 521 522 bool HasUnnamedAddr = SGV->hasUnnamedAddr() && DGV->hasUnnamedAddr(); 523 524 // If the visibilities of the symbols disagree and the destination is a 525 // prototype, take the visibility of its input. 526 if (DGV->isDeclaration()) 527 DGV->setVisibility(SGV->getVisibility()); 528 529 if (DGV->hasAppendingLinkage()) { 530 // No linking is performed yet. Just insert a new copy of the global, and 531 // keep track of the fact that it is an appending variable in the 532 // AppendingVars map. The name is cleared out so that no linkage is 533 // performed. 534 GlobalVariable *NewDGV = 535 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 536 SGV->isConstant(), SGV->getLinkage(), /*init*/0, 537 "", 0, false, 538 SGV->getType()->getAddressSpace()); 539 540 // Set alignment allowing CopyGVAttributes merge it with alignment of SGV. 541 NewDGV->setAlignment(DGV->getAlignment()); 542 // Propagate alignment, section and visibility info. 543 CopyGVAttributes(NewDGV, SGV); 544 545 // Make sure to remember this mapping... 546 ValueMap[SGV] = NewDGV; 547 548 // Keep track that this is an appending variable... 549 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV)); 550 continue; 551 } 552 553 if (LinkFromSrc) { 554 if (isa<GlobalAlias>(DGV)) 555 return Error(Err, "Global-Alias Collision on '" + SGV->getName() + 556 "': symbol multiple defined"); 557 558 // If the types don't match, and if we are to link from the source, nuke 559 // DGV and create a new one of the appropriate type. Note that the thing 560 // we are replacing may be a function (if a prototype, weak, etc) or a 561 // global variable. 562 GlobalVariable *NewDGV = 563 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 564 SGV->isConstant(), NewLinkage, /*init*/0, 565 DGV->getName(), 0, false, 566 SGV->getType()->getAddressSpace()); 567 568 // Set the unnamed_addr. 569 NewDGV->setUnnamedAddr(HasUnnamedAddr); 570 571 // Propagate alignment, section, and visibility info. 572 CopyGVAttributes(NewDGV, SGV); 573 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV, 574 DGV->getType())); 575 576 // DGV will conflict with NewDGV because they both had the same 577 // name. We must erase this now so ForceRenaming doesn't assert 578 // because DGV might not have internal linkage. 579 if (GlobalVariable *Var = dyn_cast<GlobalVariable>(DGV)) 580 Var->eraseFromParent(); 581 else 582 cast<Function>(DGV)->eraseFromParent(); 583 584 // If the symbol table renamed the global, but it is an externally visible 585 // symbol, DGV must be an existing global with internal linkage. Rename. 586 if (NewDGV->getName() != SGV->getName() && !NewDGV->hasLocalLinkage()) 587 ForceRenaming(NewDGV, SGV->getName()); 588 589 // Inherit const as appropriate. 590 NewDGV->setConstant(SGV->isConstant()); 591 592 // Make sure to remember this mapping. 593 ValueMap[SGV] = NewDGV; 594 continue; 595 } 596 597 // Not "link from source", keep the one in the DestModule and remap the 598 // input onto it. 599 600 // Special case for const propagation. 601 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) 602 if (DGVar->isDeclaration() && SGV->isConstant() && !DGVar->isConstant()) 603 DGVar->setConstant(true); 604 605 // SGV is global, but DGV is alias. 606 if (isa<GlobalAlias>(DGV)) { 607 // The only valid mappings are: 608 // - SGV is external declaration, which is effectively a no-op. 609 // - SGV is weak, when we just need to throw SGV out. 610 if (!SGV->isDeclaration() && !SGV->isWeakForLinker()) 611 return Error(Err, "Global-Alias Collision on '" + SGV->getName() + 612 "': symbol multiple defined"); 613 } 614 615 // Set calculated linkage and unnamed_addr 616 DGV->setLinkage(NewLinkage); 617 DGV->setUnnamedAddr(HasUnnamedAddr); 618 619 // Make sure to remember this mapping... 620 ValueMap[SGV] = ConstantExpr::getBitCast(DGV, SGV->getType()); 621 } 622 return false; 623} 624 625static GlobalValue::LinkageTypes 626CalculateAliasLinkage(const GlobalValue *SGV, const GlobalValue *DGV) { 627 GlobalValue::LinkageTypes SL = SGV->getLinkage(); 628 GlobalValue::LinkageTypes DL = DGV->getLinkage(); 629 if (SL == GlobalValue::ExternalLinkage || DL == GlobalValue::ExternalLinkage) 630 return GlobalValue::ExternalLinkage; 631 else if (SL == GlobalValue::WeakAnyLinkage || 632 DL == GlobalValue::WeakAnyLinkage) 633 return GlobalValue::WeakAnyLinkage; 634 else if (SL == GlobalValue::WeakODRLinkage || 635 DL == GlobalValue::WeakODRLinkage) 636 return GlobalValue::WeakODRLinkage; 637 else if (SL == GlobalValue::InternalLinkage && 638 DL == GlobalValue::InternalLinkage) 639 return GlobalValue::InternalLinkage; 640 else if (SL == GlobalValue::LinkerPrivateLinkage && 641 DL == GlobalValue::LinkerPrivateLinkage) 642 return GlobalValue::LinkerPrivateLinkage; 643 else if (SL == GlobalValue::LinkerPrivateWeakLinkage && 644 DL == GlobalValue::LinkerPrivateWeakLinkage) 645 return GlobalValue::LinkerPrivateWeakLinkage; 646 else if (SL == GlobalValue::LinkerPrivateWeakDefAutoLinkage && 647 DL == GlobalValue::LinkerPrivateWeakDefAutoLinkage) 648 return GlobalValue::LinkerPrivateWeakDefAutoLinkage; 649 else { 650 assert (SL == GlobalValue::PrivateLinkage && 651 DL == GlobalValue::PrivateLinkage && "Unexpected linkage type"); 652 return GlobalValue::PrivateLinkage; 653 } 654} 655 656// LinkAlias - Loop through the alias in the src module and link them into the 657// dest module. We're assuming, that all functions/global variables were already 658// linked in. 659static bool LinkAlias(Module *Dest, const Module *Src, 660 ValueToValueMapTy &ValueMap, 661 std::string *Err) { 662 // Loop over all alias in the src module 663 for (Module::const_alias_iterator I = Src->alias_begin(), 664 E = Src->alias_end(); I != E; ++I) { 665 const GlobalAlias *SGA = I; 666 const GlobalValue *SAliasee = SGA->getAliasedGlobal(); 667 GlobalAlias *NewGA = NULL; 668 669 // Globals were already linked, thus we can just query ValueMap for variant 670 // of SAliasee in Dest. 671 ValueToValueMapTy::const_iterator VMI = ValueMap.find(SAliasee); 672 assert(VMI != ValueMap.end() && "Aliasee not linked"); 673 GlobalValue* DAliasee = cast<GlobalValue>(VMI->second); 674 GlobalValue* DGV = NULL; 675 676 // Fixup aliases to bitcasts. Note that aliases to GEPs are still broken 677 // by this, but aliases to GEPs are broken to a lot of other things, so 678 // it's less important. 679 Constant *DAliaseeConst = DAliasee; 680 if (SGA->getType() != DAliasee->getType()) 681 DAliaseeConst = ConstantExpr::getBitCast(DAliasee, SGA->getType()); 682 683 // Try to find something 'similar' to SGA in destination module. 684 if (!DGV && !SGA->hasLocalLinkage()) { 685 DGV = Dest->getNamedAlias(SGA->getName()); 686 687 // If types don't agree due to opaque types, try to resolve them. 688 if (DGV && DGV->getType() != SGA->getType()) 689 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 690 } 691 692 if (!DGV && !SGA->hasLocalLinkage()) { 693 DGV = Dest->getGlobalVariable(SGA->getName()); 694 695 // If types don't agree due to opaque types, try to resolve them. 696 if (DGV && DGV->getType() != SGA->getType()) 697 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 698 } 699 700 if (!DGV && !SGA->hasLocalLinkage()) { 701 DGV = Dest->getFunction(SGA->getName()); 702 703 // If types don't agree due to opaque types, try to resolve them. 704 if (DGV && DGV->getType() != SGA->getType()) 705 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 706 } 707 708 // No linking to be performed on internal stuff. 709 if (DGV && DGV->hasLocalLinkage()) 710 DGV = NULL; 711 712 if (GlobalAlias *DGA = dyn_cast_or_null<GlobalAlias>(DGV)) { 713 // Types are known to be the same, check whether aliasees equal. As 714 // globals are already linked we just need query ValueMap to find the 715 // mapping. 716 if (DAliasee == DGA->getAliasedGlobal()) { 717 // This is just two copies of the same alias. Propagate linkage, if 718 // necessary. 719 DGA->setLinkage(CalculateAliasLinkage(SGA, DGA)); 720 721 NewGA = DGA; 722 // Proceed to 'common' steps 723 } else 724 return Error(Err, "Alias Collision on '" + SGA->getName()+ 725 "': aliases have different aliasees"); 726 } else if (GlobalVariable *DGVar = dyn_cast_or_null<GlobalVariable>(DGV)) { 727 // The only allowed way is to link alias with external declaration or weak 728 // symbol.. 729 if (DGVar->isDeclaration() || DGVar->isWeakForLinker()) { 730 // But only if aliasee is global too... 731 if (!isa<GlobalVariable>(DAliasee)) 732 return Error(Err, "Global-Alias Collision on '" + SGA->getName() + 733 "': aliasee is not global variable"); 734 735 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 736 SGA->getName(), DAliaseeConst, Dest); 737 CopyGVAttributes(NewGA, SGA); 738 739 // Any uses of DGV need to change to NewGA, with cast, if needed. 740 if (SGA->getType() != DGVar->getType()) 741 DGVar->replaceAllUsesWith(ConstantExpr::getBitCast(NewGA, 742 DGVar->getType())); 743 else 744 DGVar->replaceAllUsesWith(NewGA); 745 746 // DGVar will conflict with NewGA because they both had the same 747 // name. We must erase this now so ForceRenaming doesn't assert 748 // because DGV might not have internal linkage. 749 DGVar->eraseFromParent(); 750 751 // Proceed to 'common' steps 752 } else 753 return Error(Err, "Global-Alias Collision on '" + SGA->getName() + 754 "': symbol multiple defined"); 755 } else if (Function *DF = dyn_cast_or_null<Function>(DGV)) { 756 // The only allowed way is to link alias with external declaration or weak 757 // symbol... 758 if (DF->isDeclaration() || DF->isWeakForLinker()) { 759 // But only if aliasee is function too... 760 if (!isa<Function>(DAliasee)) 761 return Error(Err, "Function-Alias Collision on '" + SGA->getName() + 762 "': aliasee is not function"); 763 764 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 765 SGA->getName(), DAliaseeConst, Dest); 766 CopyGVAttributes(NewGA, SGA); 767 768 // Any uses of DF need to change to NewGA, with cast, if needed. 769 if (SGA->getType() != DF->getType()) 770 DF->replaceAllUsesWith(ConstantExpr::getBitCast(NewGA, 771 DF->getType())); 772 else 773 DF->replaceAllUsesWith(NewGA); 774 775 // DF will conflict with NewGA because they both had the same 776 // name. We must erase this now so ForceRenaming doesn't assert 777 // because DF might not have internal linkage. 778 DF->eraseFromParent(); 779 780 // Proceed to 'common' steps 781 } else 782 return Error(Err, "Function-Alias Collision on '" + SGA->getName() + 783 "': symbol multiple defined"); 784 } else { 785 // No linking to be performed, simply create an identical version of the 786 // alias over in the dest module... 787 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 788 SGA->getName(), DAliaseeConst, Dest); 789 CopyGVAttributes(NewGA, SGA); 790 791 // Proceed to 'common' steps 792 } 793 794 assert(NewGA && "No alias was created in destination module!"); 795 796 // If the symbol table renamed the alias, but it is an externally visible 797 // symbol, DGA must be an global value with internal linkage. Rename it. 798 if (NewGA->getName() != SGA->getName() && 799 !NewGA->hasLocalLinkage()) 800 ForceRenaming(NewGA, SGA->getName()); 801 802 // Remember this mapping so uses in the source module get remapped 803 // later by MapValue. 804 ValueMap[SGA] = NewGA; 805 } 806 807 return false; 808} 809 810 811// LinkGlobalInits - Update the initializers in the Dest module now that all 812// globals that may be referenced are in Dest. 813static bool LinkGlobalInits(Module *Dest, const Module *Src, 814 ValueToValueMapTy &ValueMap, 815 std::string *Err) { 816 // Loop over all of the globals in the src module, mapping them over as we go 817 for (Module::const_global_iterator I = Src->global_begin(), 818 E = Src->global_end(); I != E; ++I) { 819 const GlobalVariable *SGV = I; 820 821 if (SGV->hasInitializer()) { // Only process initialized GV's 822 // Figure out what the initializer looks like in the dest module. 823 Constant *SInit = 824 cast<Constant>(MapValue(SGV->getInitializer(), ValueMap)); 825 // Grab destination global variable or alias. 826 GlobalValue *DGV = cast<GlobalValue>(ValueMap[SGV]->stripPointerCasts()); 827 828 // If dest if global variable, check that initializers match. 829 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) { 830 if (DGVar->hasInitializer()) { 831 if (SGV->hasExternalLinkage()) { 832 if (DGVar->getInitializer() != SInit) 833 return Error(Err, "Global Variable Collision on '" + 834 SGV->getName() + 835 "': global variables have different initializers"); 836 } else if (DGVar->isWeakForLinker()) { 837 // Nothing is required, mapped values will take the new global 838 // automatically. 839 } else if (SGV->isWeakForLinker()) { 840 // Nothing is required, mapped values will take the new global 841 // automatically. 842 } else if (DGVar->hasAppendingLinkage()) { 843 llvm_unreachable("Appending linkage unimplemented!"); 844 } else { 845 llvm_unreachable("Unknown linkage!"); 846 } 847 } else { 848 // Copy the initializer over now... 849 DGVar->setInitializer(SInit); 850 } 851 } else { 852 // Destination is alias, the only valid situation is when source is 853 // weak. Also, note, that we already checked linkage in LinkGlobals(), 854 // thus we assert here. 855 // FIXME: Should we weaken this assumption, 'dereference' alias and 856 // check for initializer of aliasee? 857 assert(SGV->isWeakForLinker()); 858 } 859 } 860 } 861 return false; 862} 863 864// LinkFunctionProtos - Link the functions together between the two modules, 865// without doing function bodies... this just adds external function prototypes 866// to the Dest function... 867// 868static bool LinkFunctionProtos(Module *Dest, const Module *Src, 869 ValueToValueMapTy &ValueMap, 870 std::string *Err) { 871 ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable(); 872 873 // Loop over all of the functions in the src module, mapping them over 874 for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) { 875 const Function *SF = I; // SrcFunction 876 GlobalValue *DGV = 0; 877 878 // Check to see if may have to link the function with the global, alias or 879 // function. 880 if (SF->hasName() && !SF->hasLocalLinkage()) 881 DGV = cast_or_null<GlobalValue>(DestSymTab.lookup(SF->getName())); 882 883 // If we found a global with the same name in the dest module, but it has 884 // internal linkage, we are really not doing any linkage here. 885 if (DGV && DGV->hasLocalLinkage()) 886 DGV = 0; 887 888 // If types don't agree due to opaque types, try to resolve them. 889 if (DGV && DGV->getType() != SF->getType()) 890 RecursiveResolveTypes(SF->getType(), DGV->getType()); 891 892 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 893 bool LinkFromSrc = false; 894 if (GetLinkageResult(DGV, SF, NewLinkage, LinkFromSrc, Err)) 895 return true; 896 897 // If there is no linkage to be performed, just bring over SF without 898 // modifying it. 899 if (DGV == 0) { 900 // Function does not already exist, simply insert an function signature 901 // identical to SF into the dest module. 902 Function *NewDF = Function::Create(SF->getFunctionType(), 903 SF->getLinkage(), 904 SF->getName(), Dest); 905 CopyGVAttributes(NewDF, SF); 906 907 // If the LLVM runtime renamed the function, but it is an externally 908 // visible symbol, DF must be an existing function with internal linkage. 909 // Rename it. 910 if (!NewDF->hasLocalLinkage() && NewDF->getName() != SF->getName()) 911 ForceRenaming(NewDF, SF->getName()); 912 913 // ... and remember this mapping... 914 ValueMap[SF] = NewDF; 915 continue; 916 } 917 918 // If the visibilities of the symbols disagree and the destination is a 919 // prototype, take the visibility of its input. 920 if (DGV->isDeclaration()) 921 DGV->setVisibility(SF->getVisibility()); 922 923 if (LinkFromSrc) { 924 if (isa<GlobalAlias>(DGV)) 925 return Error(Err, "Function-Alias Collision on '" + SF->getName() + 926 "': symbol multiple defined"); 927 928 // We have a definition of the same name but different type in the 929 // source module. Copy the prototype to the destination and replace 930 // uses of the destination's prototype with the new prototype. 931 Function *NewDF = Function::Create(SF->getFunctionType(), NewLinkage, 932 SF->getName(), Dest); 933 CopyGVAttributes(NewDF, SF); 934 935 // Any uses of DF need to change to NewDF, with cast 936 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, 937 DGV->getType())); 938 939 // DF will conflict with NewDF because they both had the same. We must 940 // erase this now so ForceRenaming doesn't assert because DF might 941 // not have internal linkage. 942 if (GlobalVariable *Var = dyn_cast<GlobalVariable>(DGV)) 943 Var->eraseFromParent(); 944 else 945 cast<Function>(DGV)->eraseFromParent(); 946 947 // If the symbol table renamed the function, but it is an externally 948 // visible symbol, DF must be an existing function with internal 949 // linkage. Rename it. 950 if (NewDF->getName() != SF->getName() && !NewDF->hasLocalLinkage()) 951 ForceRenaming(NewDF, SF->getName()); 952 953 // Remember this mapping so uses in the source module get remapped 954 // later by MapValue. 955 ValueMap[SF] = NewDF; 956 continue; 957 } 958 959 // Not "link from source", keep the one in the DestModule and remap the 960 // input onto it. 961 962 if (isa<GlobalAlias>(DGV)) { 963 // The only valid mappings are: 964 // - SF is external declaration, which is effectively a no-op. 965 // - SF is weak, when we just need to throw SF out. 966 if (!SF->isDeclaration() && !SF->isWeakForLinker()) 967 return Error(Err, "Function-Alias Collision on '" + SF->getName() + 968 "': symbol multiple defined"); 969 } 970 971 // Set calculated linkage 972 DGV->setLinkage(NewLinkage); 973 974 // Make sure to remember this mapping. 975 ValueMap[SF] = ConstantExpr::getBitCast(DGV, SF->getType()); 976 } 977 return false; 978} 979 980// LinkFunctionBody - Copy the source function over into the dest function and 981// fix up references to values. At this point we know that Dest is an external 982// function, and that Src is not. 983static bool LinkFunctionBody(Function *Dest, Function *Src, 984 ValueToValueMapTy &ValueMap, 985 std::string *Err) { 986 assert(Src && Dest && Dest->isDeclaration() && !Src->isDeclaration()); 987 988 // Go through and convert function arguments over, remembering the mapping. 989 Function::arg_iterator DI = Dest->arg_begin(); 990 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 991 I != E; ++I, ++DI) { 992 DI->setName(I->getName()); // Copy the name information over... 993 994 // Add a mapping to our local map 995 ValueMap[I] = DI; 996 } 997 998 // Splice the body of the source function into the dest function. 999 Dest->getBasicBlockList().splice(Dest->end(), Src->getBasicBlockList()); 1000 1001 // At this point, all of the instructions and values of the function are now 1002 // copied over. The only problem is that they are still referencing values in 1003 // the Source function as operands. Loop through all of the operands of the 1004 // functions and patch them up to point to the local versions. 1005 for (Function::iterator BB = Dest->begin(), BE = Dest->end(); BB != BE; ++BB) 1006 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) 1007 RemapInstruction(I, ValueMap, RF_IgnoreMissingEntries); 1008 1009 // There is no need to map the arguments anymore. 1010 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 1011 I != E; ++I) 1012 ValueMap.erase(I); 1013 1014 return false; 1015} 1016 1017 1018// LinkFunctionBodies - Link in the function bodies that are defined in the 1019// source module into the DestModule. This consists basically of copying the 1020// function over and fixing up references to values. 1021static bool LinkFunctionBodies(Module *Dest, Module *Src, 1022 ValueToValueMapTy &ValueMap, 1023 std::string *Err) { 1024 1025 // Loop over all of the functions in the src module, mapping them over as we 1026 // go 1027 for (Module::iterator SF = Src->begin(), E = Src->end(); SF != E; ++SF) { 1028 if (!SF->isDeclaration()) { // No body if function is external 1029 Function *DF = dyn_cast<Function>(ValueMap[SF]); // Destination function 1030 1031 // DF not external SF external? 1032 if (DF && DF->isDeclaration()) 1033 // Only provide the function body if there isn't one already. 1034 if (LinkFunctionBody(DF, SF, ValueMap, Err)) 1035 return true; 1036 } 1037 } 1038 return false; 1039} 1040 1041// LinkAppendingVars - If there were any appending global variables, link them 1042// together now. Return true on error. 1043static bool LinkAppendingVars(Module *M, 1044 std::multimap<std::string, GlobalVariable *> &AppendingVars, 1045 std::string *ErrorMsg) { 1046 if (AppendingVars.empty()) return false; // Nothing to do. 1047 1048 // Loop over the multimap of appending vars, processing any variables with the 1049 // same name, forming a new appending global variable with both of the 1050 // initializers merged together, then rewrite references to the old variables 1051 // and delete them. 1052 std::vector<Constant*> Inits; 1053 while (AppendingVars.size() > 1) { 1054 // Get the first two elements in the map... 1055 std::multimap<std::string, 1056 GlobalVariable*>::iterator Second = AppendingVars.begin(), First=Second++; 1057 1058 // If the first two elements are for different names, there is no pair... 1059 // Otherwise there is a pair, so link them together... 1060 if (First->first == Second->first) { 1061 GlobalVariable *G1 = First->second, *G2 = Second->second; 1062 const ArrayType *T1 = cast<ArrayType>(G1->getType()->getElementType()); 1063 const ArrayType *T2 = cast<ArrayType>(G2->getType()->getElementType()); 1064 1065 // Check to see that they two arrays agree on type... 1066 if (T1->getElementType() != T2->getElementType()) 1067 return Error(ErrorMsg, 1068 "Appending variables with different element types need to be linked!"); 1069 if (G1->isConstant() != G2->isConstant()) 1070 return Error(ErrorMsg, 1071 "Appending variables linked with different const'ness!"); 1072 1073 if (G1->getAlignment() != G2->getAlignment()) 1074 return Error(ErrorMsg, 1075 "Appending variables with different alignment need to be linked!"); 1076 1077 if (G1->getVisibility() != G2->getVisibility()) 1078 return Error(ErrorMsg, 1079 "Appending variables with different visibility need to be linked!"); 1080 1081 if (G1->getSection() != G2->getSection()) 1082 return Error(ErrorMsg, 1083 "Appending variables with different section name need to be linked!"); 1084 1085 unsigned NewSize = T1->getNumElements() + T2->getNumElements(); 1086 ArrayType *NewType = ArrayType::get(T1->getElementType(), 1087 NewSize); 1088 1089 G1->setName(""); // Clear G1's name in case of a conflict! 1090 1091 // Create the new global variable... 1092 GlobalVariable *NG = 1093 new GlobalVariable(*M, NewType, G1->isConstant(), G1->getLinkage(), 1094 /*init*/0, First->first, 0, G1->isThreadLocal(), 1095 G1->getType()->getAddressSpace()); 1096 1097 // Propagate alignment, visibility and section info. 1098 CopyGVAttributes(NG, G1); 1099 1100 // Merge the initializer... 1101 Inits.reserve(NewSize); 1102 if (ConstantArray *I = dyn_cast<ConstantArray>(G1->getInitializer())) { 1103 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i) 1104 Inits.push_back(I->getOperand(i)); 1105 } else { 1106 assert(isa<ConstantAggregateZero>(G1->getInitializer())); 1107 Constant *CV = Constant::getNullValue(T1->getElementType()); 1108 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i) 1109 Inits.push_back(CV); 1110 } 1111 if (ConstantArray *I = dyn_cast<ConstantArray>(G2->getInitializer())) { 1112 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i) 1113 Inits.push_back(I->getOperand(i)); 1114 } else { 1115 assert(isa<ConstantAggregateZero>(G2->getInitializer())); 1116 Constant *CV = Constant::getNullValue(T2->getElementType()); 1117 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i) 1118 Inits.push_back(CV); 1119 } 1120 NG->setInitializer(ConstantArray::get(NewType, Inits)); 1121 Inits.clear(); 1122 1123 // Replace any uses of the two global variables with uses of the new 1124 // global... 1125 1126 // FIXME: This should rewrite simple/straight-forward uses such as 1127 // getelementptr instructions to not use the Cast! 1128 G1->replaceAllUsesWith(ConstantExpr::getBitCast(NG, 1129 G1->getType())); 1130 G2->replaceAllUsesWith(ConstantExpr::getBitCast(NG, 1131 G2->getType())); 1132 1133 // Remove the two globals from the module now... 1134 M->getGlobalList().erase(G1); 1135 M->getGlobalList().erase(G2); 1136 1137 // Put the new global into the AppendingVars map so that we can handle 1138 // linking of more than two vars... 1139 Second->second = NG; 1140 } 1141 AppendingVars.erase(First); 1142 } 1143 1144 return false; 1145} 1146 1147static bool ResolveAliases(Module *Dest) { 1148 for (Module::alias_iterator I = Dest->alias_begin(), E = Dest->alias_end(); 1149 I != E; ++I) 1150 // We can't sue resolveGlobalAlias here because we need to preserve 1151 // bitcasts and GEPs. 1152 if (const Constant *C = I->getAliasee()) { 1153 while (dyn_cast<GlobalAlias>(C)) 1154 C = cast<GlobalAlias>(C)->getAliasee(); 1155 const GlobalValue *GV = dyn_cast<GlobalValue>(C); 1156 if (C != I && !(GV && GV->isDeclaration())) 1157 I->replaceAllUsesWith(const_cast<Constant*>(C)); 1158 } 1159 1160 return false; 1161} 1162 1163// LinkModules - This function links two modules together, with the resulting 1164// left module modified to be the composite of the two input modules. If an 1165// error occurs, true is returned and ErrorMsg (if not null) is set to indicate 1166// the problem. Upon failure, the Dest module could be in a modified state, and 1167// shouldn't be relied on to be consistent. 1168bool 1169Linker::LinkModules(Module *Dest, Module *Src, std::string *ErrorMsg) { 1170 assert(Dest != 0 && "Invalid Destination module"); 1171 assert(Src != 0 && "Invalid Source Module"); 1172 1173 if (Dest->getDataLayout().empty()) { 1174 if (!Src->getDataLayout().empty()) { 1175 Dest->setDataLayout(Src->getDataLayout()); 1176 } else { 1177 std::string DataLayout; 1178 1179 if (Dest->getEndianness() == Module::AnyEndianness) { 1180 if (Src->getEndianness() == Module::BigEndian) 1181 DataLayout.append("E"); 1182 else if (Src->getEndianness() == Module::LittleEndian) 1183 DataLayout.append("e"); 1184 } 1185 1186 if (Dest->getPointerSize() == Module::AnyPointerSize) { 1187 if (Src->getPointerSize() == Module::Pointer64) 1188 DataLayout.append(DataLayout.length() == 0 ? "p:64:64" : "-p:64:64"); 1189 else if (Src->getPointerSize() == Module::Pointer32) 1190 DataLayout.append(DataLayout.length() == 0 ? "p:32:32" : "-p:32:32"); 1191 } 1192 Dest->setDataLayout(DataLayout); 1193 } 1194 } 1195 1196 // Copy the target triple from the source to dest if the dest's is empty. 1197 if (Dest->getTargetTriple().empty() && !Src->getTargetTriple().empty()) 1198 Dest->setTargetTriple(Src->getTargetTriple()); 1199 1200 if (!Src->getDataLayout().empty() && !Dest->getDataLayout().empty() && 1201 Src->getDataLayout() != Dest->getDataLayout()) 1202 errs() << "WARNING: Linking two modules of different data layouts!\n"; 1203 if (!Src->getTargetTriple().empty() && 1204 Dest->getTargetTriple() != Src->getTargetTriple()) { 1205 errs() << "WARNING: Linking two modules of different target triples: "; 1206 if (!Src->getModuleIdentifier().empty()) 1207 errs() << Src->getModuleIdentifier() << ": "; 1208 errs() << "'" << Src->getTargetTriple() << "' and '" 1209 << Dest->getTargetTriple() << "'\n"; 1210 } 1211 1212 // Append the module inline asm string. 1213 if (!Src->getModuleInlineAsm().empty()) { 1214 if (Dest->getModuleInlineAsm().empty()) 1215 Dest->setModuleInlineAsm(Src->getModuleInlineAsm()); 1216 else 1217 Dest->setModuleInlineAsm(Dest->getModuleInlineAsm()+"\n"+ 1218 Src->getModuleInlineAsm()); 1219 } 1220 1221 // Update the destination module's dependent libraries list with the libraries 1222 // from the source module. There's no opportunity for duplicates here as the 1223 // Module ensures that duplicate insertions are discarded. 1224 for (Module::lib_iterator SI = Src->lib_begin(), SE = Src->lib_end(); 1225 SI != SE; ++SI) 1226 Dest->addLibrary(*SI); 1227 1228 // LinkTypes - Go through the symbol table of the Src module and see if any 1229 // types are named in the src module that are not named in the Dst module. 1230 // Make sure there are no type name conflicts. 1231 if (LinkTypes(Dest, Src, ErrorMsg)) 1232 return true; 1233 1234 // ValueMap - Mapping of values from what they used to be in Src, to what they 1235 // are now in Dest. ValueToValueMapTy is a ValueMap, which involves some 1236 // overhead due to the use of Value handles which the Linker doesn't actually 1237 // need, but this allows us to reuse the ValueMapper code. 1238 ValueToValueMapTy ValueMap; 1239 1240 // AppendingVars - Keep track of global variables in the destination module 1241 // with appending linkage. After the module is linked together, they are 1242 // appended and the module is rewritten. 1243 std::multimap<std::string, GlobalVariable *> AppendingVars; 1244 for (Module::global_iterator I = Dest->global_begin(), E = Dest->global_end(); 1245 I != E; ++I) { 1246 // Add all of the appending globals already in the Dest module to 1247 // AppendingVars. 1248 if (I->hasAppendingLinkage()) 1249 AppendingVars.insert(std::make_pair(I->getName(), I)); 1250 } 1251 1252 // Insert all of the globals in src into the Dest module... without linking 1253 // initializers (which could refer to functions not yet mapped over). 1254 if (LinkGlobals(Dest, Src, ValueMap, AppendingVars, ErrorMsg)) 1255 return true; 1256 1257 // Link the functions together between the two modules, without doing function 1258 // bodies... this just adds external function prototypes to the Dest 1259 // function... We do this so that when we begin processing function bodies, 1260 // all of the global values that may be referenced are available in our 1261 // ValueMap. 1262 if (LinkFunctionProtos(Dest, Src, ValueMap, ErrorMsg)) 1263 return true; 1264 1265 // If there were any alias, link them now. We really need to do this now, 1266 // because all of the aliases that may be referenced need to be available in 1267 // ValueMap 1268 if (LinkAlias(Dest, Src, ValueMap, ErrorMsg)) return true; 1269 1270 // Update the initializers in the Dest module now that all globals that may 1271 // be referenced are in Dest. 1272 if (LinkGlobalInits(Dest, Src, ValueMap, ErrorMsg)) return true; 1273 1274 // Link in the function bodies that are defined in the source module into the 1275 // DestModule. This consists basically of copying the function over and 1276 // fixing up references to values. 1277 if (LinkFunctionBodies(Dest, Src, ValueMap, ErrorMsg)) return true; 1278 1279 // If there were any appending global variables, link them together now. 1280 if (LinkAppendingVars(Dest, AppendingVars, ErrorMsg)) return true; 1281 1282 // Resolve all uses of aliases with aliasees 1283 if (ResolveAliases(Dest)) return true; 1284 1285 // Remap all of the named mdnoes in Src into the Dest module. We do this 1286 // after linking GlobalValues so that MDNodes that reference GlobalValues 1287 // are properly remapped. 1288 LinkNamedMDNodes(Dest, Src, ValueMap); 1289 1290 // If the source library's module id is in the dependent library list of the 1291 // destination library, remove it since that module is now linked in. 1292 const std::string &modId = Src->getModuleIdentifier(); 1293 if (!modId.empty()) 1294 Dest->removeLibrary(sys::path::stem(modId)); 1295 1296 return false; 1297} 1298 1299// vim: sw=2 1300