LinkModules.cpp revision 3472246edee4e120e3eb1ec4ad443ba884bc7ac7
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/ADT/DenseMap.h" 33using namespace llvm; 34 35// Error - Simple wrapper function to conditionally assign to E and return true. 36// This just makes error return conditions a little bit simpler... 37static inline bool Error(std::string *E, const Twine &Message) { 38 if (E) *E = Message.str(); 39 return true; 40} 41 42// Function: ResolveTypes() 43// 44// Description: 45// Attempt to link the two specified types together. 46// 47// Inputs: 48// DestTy - The type to which we wish to resolve. 49// SrcTy - The original type which we want to resolve. 50// 51// Outputs: 52// DestST - The symbol table in which the new type should be placed. 53// 54// Return value: 55// true - There is an error and the types cannot yet be linked. 56// false - No errors. 57// 58static bool ResolveTypes(const Type *DestTy, const Type *SrcTy) { 59 if (DestTy == SrcTy) return false; // If already equal, noop 60 assert(DestTy && SrcTy && "Can't handle null types"); 61 62 if (const OpaqueType *OT = dyn_cast<OpaqueType>(DestTy)) { 63 // Type _is_ in module, just opaque... 64 const_cast<OpaqueType*>(OT)->refineAbstractTypeTo(SrcTy); 65 } else if (const OpaqueType *OT = dyn_cast<OpaqueType>(SrcTy)) { 66 const_cast<OpaqueType*>(OT)->refineAbstractTypeTo(DestTy); 67 } else { 68 return true; // Cannot link types... not-equal and neither is opaque. 69 } 70 return false; 71} 72 73/// LinkerTypeMap - This implements a map of types that is stable 74/// even if types are resolved/refined to other types. This is not a general 75/// purpose map, it is specific to the linker's use. 76namespace { 77class LinkerTypeMap : public AbstractTypeUser { 78 typedef DenseMap<const Type*, PATypeHolder> TheMapTy; 79 TheMapTy TheMap; 80 81 LinkerTypeMap(const LinkerTypeMap&); // DO NOT IMPLEMENT 82 void operator=(const LinkerTypeMap&); // DO NOT IMPLEMENT 83public: 84 LinkerTypeMap() {} 85 ~LinkerTypeMap() { 86 for (DenseMap<const Type*, PATypeHolder>::iterator I = TheMap.begin(), 87 E = TheMap.end(); I != E; ++I) 88 I->first->removeAbstractTypeUser(this); 89 } 90 91 /// lookup - Return the value for the specified type or null if it doesn't 92 /// exist. 93 const Type *lookup(const Type *Ty) const { 94 TheMapTy::const_iterator I = TheMap.find(Ty); 95 if (I != TheMap.end()) return I->second; 96 return 0; 97 } 98 99 /// erase - Remove the specified type, returning true if it was in the set. 100 bool erase(const Type *Ty) { 101 if (!TheMap.erase(Ty)) 102 return false; 103 if (Ty->isAbstract()) 104 Ty->removeAbstractTypeUser(this); 105 return true; 106 } 107 108 /// insert - This returns true if the pointer was new to the set, false if it 109 /// was already in the set. 110 bool insert(const Type *Src, const Type *Dst) { 111 if (!TheMap.insert(std::make_pair(Src, PATypeHolder(Dst))).second) 112 return false; // Already in map. 113 if (Src->isAbstract()) 114 Src->addAbstractTypeUser(this); 115 return true; 116 } 117 118protected: 119 /// refineAbstractType - The callback method invoked when an abstract type is 120 /// resolved to another type. An object must override this method to update 121 /// its internal state to reference NewType instead of OldType. 122 /// 123 virtual void refineAbstractType(const DerivedType *OldTy, 124 const Type *NewTy) { 125 TheMapTy::iterator I = TheMap.find(OldTy); 126 const Type *DstTy = I->second; 127 128 TheMap.erase(I); 129 if (OldTy->isAbstract()) 130 OldTy->removeAbstractTypeUser(this); 131 132 // Don't reinsert into the map if the key is concrete now. 133 if (NewTy->isAbstract()) 134 insert(NewTy, DstTy); 135 } 136 137 /// The other case which AbstractTypeUsers must be aware of is when a type 138 /// makes the transition from being abstract (where it has clients on it's 139 /// AbstractTypeUsers list) to concrete (where it does not). This method 140 /// notifies ATU's when this occurs for a type. 141 virtual void typeBecameConcrete(const DerivedType *AbsTy) { 142 TheMap.erase(AbsTy); 143 AbsTy->removeAbstractTypeUser(this); 144 } 145 146 // for debugging... 147 virtual void dump() const { 148 dbgs() << "AbstractTypeSet!\n"; 149 } 150}; 151} 152 153 154// RecursiveResolveTypes - This is just like ResolveTypes, except that it 155// recurses down into derived types, merging the used types if the parent types 156// are compatible. 157static bool RecursiveResolveTypesI(const Type *DstTy, const Type *SrcTy, 158 LinkerTypeMap &Pointers) { 159 if (DstTy == SrcTy) return false; // If already equal, noop 160 161 // If we found our opaque type, resolve it now! 162 if (isa<OpaqueType>(DstTy) || isa<OpaqueType>(SrcTy)) 163 return ResolveTypes(DstTy, SrcTy); 164 165 // Two types cannot be resolved together if they are of different primitive 166 // type. For example, we cannot resolve an int to a float. 167 if (DstTy->getTypeID() != SrcTy->getTypeID()) return true; 168 169 // If neither type is abstract, then they really are just different types. 170 if (!DstTy->isAbstract() && !SrcTy->isAbstract()) 171 return true; 172 173 // Otherwise, resolve the used type used by this derived type... 174 switch (DstTy->getTypeID()) { 175 default: 176 return true; 177 case Type::FunctionTyID: { 178 const FunctionType *DstFT = cast<FunctionType>(DstTy); 179 const FunctionType *SrcFT = cast<FunctionType>(SrcTy); 180 if (DstFT->isVarArg() != SrcFT->isVarArg() || 181 DstFT->getNumContainedTypes() != SrcFT->getNumContainedTypes()) 182 return true; 183 184 // Use TypeHolder's so recursive resolution won't break us. 185 PATypeHolder ST(SrcFT), DT(DstFT); 186 for (unsigned i = 0, e = DstFT->getNumContainedTypes(); i != e; ++i) { 187 const Type *SE = ST->getContainedType(i), *DE = DT->getContainedType(i); 188 if (SE != DE && RecursiveResolveTypesI(DE, SE, Pointers)) 189 return true; 190 } 191 return false; 192 } 193 case Type::StructTyID: { 194 const StructType *DstST = cast<StructType>(DstTy); 195 const StructType *SrcST = cast<StructType>(SrcTy); 196 if (DstST->getNumContainedTypes() != SrcST->getNumContainedTypes()) 197 return true; 198 199 PATypeHolder ST(SrcST), DT(DstST); 200 for (unsigned i = 0, e = DstST->getNumContainedTypes(); i != e; ++i) { 201 const Type *SE = ST->getContainedType(i), *DE = DT->getContainedType(i); 202 if (SE != DE && RecursiveResolveTypesI(DE, SE, Pointers)) 203 return true; 204 } 205 return false; 206 } 207 case Type::ArrayTyID: { 208 const ArrayType *DAT = cast<ArrayType>(DstTy); 209 const ArrayType *SAT = cast<ArrayType>(SrcTy); 210 if (DAT->getNumElements() != SAT->getNumElements()) return true; 211 return RecursiveResolveTypesI(DAT->getElementType(), SAT->getElementType(), 212 Pointers); 213 } 214 case Type::VectorTyID: { 215 const VectorType *DVT = cast<VectorType>(DstTy); 216 const VectorType *SVT = cast<VectorType>(SrcTy); 217 if (DVT->getNumElements() != SVT->getNumElements()) return true; 218 return RecursiveResolveTypesI(DVT->getElementType(), SVT->getElementType(), 219 Pointers); 220 } 221 case Type::PointerTyID: { 222 const PointerType *DstPT = cast<PointerType>(DstTy); 223 const PointerType *SrcPT = cast<PointerType>(SrcTy); 224 225 if (DstPT->getAddressSpace() != SrcPT->getAddressSpace()) 226 return true; 227 228 // If this is a pointer type, check to see if we have already seen it. If 229 // so, we are in a recursive branch. Cut off the search now. We cannot use 230 // an associative container for this search, because the type pointers (keys 231 // in the container) change whenever types get resolved. 232 if (SrcPT->isAbstract()) 233 if (const Type *ExistingDestTy = Pointers.lookup(SrcPT)) 234 return ExistingDestTy != DstPT; 235 236 if (DstPT->isAbstract()) 237 if (const Type *ExistingSrcTy = Pointers.lookup(DstPT)) 238 return ExistingSrcTy != SrcPT; 239 // Otherwise, add the current pointers to the vector to stop recursion on 240 // this pair. 241 if (DstPT->isAbstract()) 242 Pointers.insert(DstPT, SrcPT); 243 if (SrcPT->isAbstract()) 244 Pointers.insert(SrcPT, DstPT); 245 246 return RecursiveResolveTypesI(DstPT->getElementType(), 247 SrcPT->getElementType(), Pointers); 248 } 249 } 250} 251 252static bool RecursiveResolveTypes(const Type *DestTy, const Type *SrcTy) { 253 LinkerTypeMap PointerTypes; 254 return RecursiveResolveTypesI(DestTy, SrcTy, PointerTypes); 255} 256 257 258// LinkTypes - Go through the symbol table of the Src module and see if any 259// types are named in the src module that are not named in the Dst module. 260// Make sure there are no type name conflicts. 261static bool LinkTypes(Module *Dest, const Module *Src, std::string *Err) { 262 TypeSymbolTable *DestST = &Dest->getTypeSymbolTable(); 263 const TypeSymbolTable *SrcST = &Src->getTypeSymbolTable(); 264 265 // Look for a type plane for Type's... 266 TypeSymbolTable::const_iterator TI = SrcST->begin(); 267 TypeSymbolTable::const_iterator TE = SrcST->end(); 268 if (TI == TE) return false; // No named types, do nothing. 269 270 // Some types cannot be resolved immediately because they depend on other 271 // types being resolved to each other first. This contains a list of types we 272 // are waiting to recheck. 273 std::vector<std::string> DelayedTypesToResolve; 274 275 for ( ; TI != TE; ++TI ) { 276 const std::string &Name = TI->first; 277 const Type *RHS = TI->second; 278 279 // Check to see if this type name is already in the dest module. 280 Type *Entry = DestST->lookup(Name); 281 282 // If the name is just in the source module, bring it over to the dest. 283 if (Entry == 0) { 284 if (!Name.empty()) 285 DestST->insert(Name, const_cast<Type*>(RHS)); 286 } else if (ResolveTypes(Entry, RHS)) { 287 // They look different, save the types 'till later to resolve. 288 DelayedTypesToResolve.push_back(Name); 289 } 290 } 291 292 // Iteratively resolve types while we can... 293 while (!DelayedTypesToResolve.empty()) { 294 // Loop over all of the types, attempting to resolve them if possible... 295 unsigned OldSize = DelayedTypesToResolve.size(); 296 297 // Try direct resolution by name... 298 for (unsigned i = 0; i != DelayedTypesToResolve.size(); ++i) { 299 const std::string &Name = DelayedTypesToResolve[i]; 300 Type *T1 = SrcST->lookup(Name); 301 Type *T2 = DestST->lookup(Name); 302 if (!ResolveTypes(T2, T1)) { 303 // We are making progress! 304 DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i); 305 --i; 306 } 307 } 308 309 // Did we not eliminate any types? 310 if (DelayedTypesToResolve.size() == OldSize) { 311 // Attempt to resolve subelements of types. This allows us to merge these 312 // two types: { int* } and { opaque* } 313 for (unsigned i = 0, e = DelayedTypesToResolve.size(); i != e; ++i) { 314 const std::string &Name = DelayedTypesToResolve[i]; 315 if (!RecursiveResolveTypes(SrcST->lookup(Name), DestST->lookup(Name))) { 316 // We are making progress! 317 DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i); 318 319 // Go back to the main loop, perhaps we can resolve directly by name 320 // now... 321 break; 322 } 323 } 324 325 // If we STILL cannot resolve the types, then there is something wrong. 326 if (DelayedTypesToResolve.size() == OldSize) { 327 // Remove the symbol name from the destination. 328 DelayedTypesToResolve.pop_back(); 329 } 330 } 331 } 332 333 334 return false; 335} 336 337#ifndef NDEBUG 338static void PrintMap(const std::map<const Value*, Value*> &M) { 339 for (std::map<const Value*, Value*>::const_iterator I = M.begin(), E =M.end(); 340 I != E; ++I) { 341 dbgs() << " Fr: " << (void*)I->first << " "; 342 I->first->dump(); 343 dbgs() << " To: " << (void*)I->second << " "; 344 I->second->dump(); 345 dbgs() << "\n"; 346 } 347} 348#endif 349 350 351// RemapOperand - Use ValueMap to convert constants from one module to another. 352static Value *RemapOperand(const Value *In, 353 std::map<const Value*, Value*> &ValueMap) { 354 std::map<const Value*,Value*>::const_iterator I = ValueMap.find(In); 355 if (I != ValueMap.end()) 356 return I->second; 357 358 // Check to see if it's a constant that we are interested in transforming. 359 Value *Result = 0; 360 if (const Constant *CPV = dyn_cast<Constant>(In)) { 361 if ((!isa<DerivedType>(CPV->getType()) && !isa<ConstantExpr>(CPV)) || 362 isa<ConstantInt>(CPV) || isa<ConstantAggregateZero>(CPV)) 363 return const_cast<Constant*>(CPV); // Simple constants stay identical. 364 365 if (const ConstantArray *CPA = dyn_cast<ConstantArray>(CPV)) { 366 std::vector<Constant*> Operands(CPA->getNumOperands()); 367 for (unsigned i = 0, e = CPA->getNumOperands(); i != e; ++i) 368 Operands[i] =cast<Constant>(RemapOperand(CPA->getOperand(i), ValueMap)); 369 Result = ConstantArray::get(cast<ArrayType>(CPA->getType()), Operands); 370 } else if (const ConstantStruct *CPS = dyn_cast<ConstantStruct>(CPV)) { 371 std::vector<Constant*> Operands(CPS->getNumOperands()); 372 for (unsigned i = 0, e = CPS->getNumOperands(); i != e; ++i) 373 Operands[i] =cast<Constant>(RemapOperand(CPS->getOperand(i), ValueMap)); 374 Result = ConstantStruct::get(cast<StructType>(CPS->getType()), Operands); 375 } else if (isa<ConstantPointerNull>(CPV) || isa<UndefValue>(CPV)) { 376 Result = const_cast<Constant*>(CPV); 377 } else if (const ConstantVector *CP = dyn_cast<ConstantVector>(CPV)) { 378 std::vector<Constant*> Operands(CP->getNumOperands()); 379 for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i) 380 Operands[i] = cast<Constant>(RemapOperand(CP->getOperand(i), ValueMap)); 381 Result = ConstantVector::get(Operands); 382 } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CPV)) { 383 std::vector<Constant*> Ops; 384 for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) 385 Ops.push_back(cast<Constant>(RemapOperand(CE->getOperand(i),ValueMap))); 386 Result = CE->getWithOperands(Ops); 387 } else if (const BlockAddress *CE = dyn_cast<BlockAddress>(CPV)) { 388 Result = BlockAddress::get( 389 cast<Function>(RemapOperand(CE->getFunction(), ValueMap)), 390 CE->getBasicBlock()); 391 } else { 392 assert(!isa<GlobalValue>(CPV) && "Unmapped global?"); 393 llvm_unreachable("Unknown type of derived type constant value!"); 394 } 395 } else if (isa<MetadataBase>(In)) { 396 Result = const_cast<Value*>(In); 397 } else if (isa<InlineAsm>(In)) { 398 Result = const_cast<Value*>(In); 399 } 400 401 // Cache the mapping in our local map structure 402 if (Result) { 403 ValueMap[In] = Result; 404 return Result; 405 } 406 407#ifndef NDEBUG 408 dbgs() << "LinkModules ValueMap: \n"; 409 PrintMap(ValueMap); 410 411 dbgs() << "Couldn't remap value: " << (void*)In << " " << *In << "\n"; 412 llvm_unreachable("Couldn't remap value!"); 413#endif 414 return 0; 415} 416 417/// ForceRenaming - The LLVM SymbolTable class autorenames globals that conflict 418/// in the symbol table. This is good for all clients except for us. Go 419/// through the trouble to force this back. 420static void ForceRenaming(GlobalValue *GV, const std::string &Name) { 421 assert(GV->getName() != Name && "Can't force rename to self"); 422 ValueSymbolTable &ST = GV->getParent()->getValueSymbolTable(); 423 424 // If there is a conflict, rename the conflict. 425 if (GlobalValue *ConflictGV = cast_or_null<GlobalValue>(ST.lookup(Name))) { 426 assert(ConflictGV->hasLocalLinkage() && 427 "Not conflicting with a static global, should link instead!"); 428 GV->takeName(ConflictGV); 429 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed 430 assert(ConflictGV->getName() != Name && "ForceRenaming didn't work"); 431 } else { 432 GV->setName(Name); // Force the name back 433 } 434} 435 436/// CopyGVAttributes - copy additional attributes (those not needed to construct 437/// a GlobalValue) from the SrcGV to the DestGV. 438static void CopyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) { 439 // Use the maximum alignment, rather than just copying the alignment of SrcGV. 440 unsigned Alignment = std::max(DestGV->getAlignment(), SrcGV->getAlignment()); 441 DestGV->copyAttributesFrom(SrcGV); 442 DestGV->setAlignment(Alignment); 443} 444 445/// GetLinkageResult - This analyzes the two global values and determines what 446/// the result will look like in the destination module. In particular, it 447/// computes the resultant linkage type, computes whether the global in the 448/// source should be copied over to the destination (replacing the existing 449/// one), and computes whether this linkage is an error or not. It also performs 450/// visibility checks: we cannot link together two symbols with different 451/// visibilities. 452static bool GetLinkageResult(GlobalValue *Dest, const GlobalValue *Src, 453 GlobalValue::LinkageTypes <, bool &LinkFromSrc, 454 std::string *Err) { 455 assert((!Dest || !Src->hasLocalLinkage()) && 456 "If Src has internal linkage, Dest shouldn't be set!"); 457 if (!Dest) { 458 // Linking something to nothing. 459 LinkFromSrc = true; 460 LT = Src->getLinkage(); 461 } else if (Src->isDeclaration()) { 462 // If Src is external or if both Src & Dest are external.. Just link the 463 // external globals, we aren't adding anything. 464 if (Src->hasDLLImportLinkage()) { 465 // If one of GVs has DLLImport linkage, result should be dllimport'ed. 466 if (Dest->isDeclaration()) { 467 LinkFromSrc = true; 468 LT = Src->getLinkage(); 469 } 470 } else if (Dest->hasExternalWeakLinkage()) { 471 // If the Dest is weak, use the source linkage. 472 LinkFromSrc = true; 473 LT = Src->getLinkage(); 474 } else { 475 LinkFromSrc = false; 476 LT = Dest->getLinkage(); 477 } 478 } else if (Dest->isDeclaration() && !Dest->hasDLLImportLinkage()) { 479 // If Dest is external but Src is not: 480 LinkFromSrc = true; 481 LT = Src->getLinkage(); 482 } else if (Src->hasAppendingLinkage() || Dest->hasAppendingLinkage()) { 483 if (Src->getLinkage() != Dest->getLinkage()) 484 return Error(Err, "Linking globals named '" + Src->getName() + 485 "': can only link appending global with another appending global!"); 486 LinkFromSrc = true; // Special cased. 487 LT = Src->getLinkage(); 488 } else if (Src->isWeakForLinker()) { 489 // At this point we know that Dest has LinkOnce, External*, Weak, Common, 490 // or DLL* linkage. 491 if (Dest->hasExternalWeakLinkage() || 492 Dest->hasAvailableExternallyLinkage() || 493 (Dest->hasLinkOnceLinkage() && 494 (Src->hasWeakLinkage() || Src->hasCommonLinkage()))) { 495 LinkFromSrc = true; 496 LT = Src->getLinkage(); 497 } else { 498 LinkFromSrc = false; 499 LT = Dest->getLinkage(); 500 } 501 } else if (Dest->isWeakForLinker()) { 502 // At this point we know that Src has External* or DLL* linkage. 503 if (Src->hasExternalWeakLinkage()) { 504 LinkFromSrc = false; 505 LT = Dest->getLinkage(); 506 } else { 507 LinkFromSrc = true; 508 LT = GlobalValue::ExternalLinkage; 509 } 510 } else { 511 assert((Dest->hasExternalLinkage() || 512 Dest->hasDLLImportLinkage() || 513 Dest->hasDLLExportLinkage() || 514 Dest->hasExternalWeakLinkage()) && 515 (Src->hasExternalLinkage() || 516 Src->hasDLLImportLinkage() || 517 Src->hasDLLExportLinkage() || 518 Src->hasExternalWeakLinkage()) && 519 "Unexpected linkage type!"); 520 return Error(Err, "Linking globals named '" + Src->getName() + 521 "': symbol multiply defined!"); 522 } 523 524 // Check visibility 525 if (Dest && Src->getVisibility() != Dest->getVisibility()) 526 if (!Src->isDeclaration() && !Dest->isDeclaration()) 527 return Error(Err, "Linking globals named '" + Src->getName() + 528 "': symbols have different visibilities!"); 529 return false; 530} 531 532// Insert all of the named mdnoes in Src into the Dest module. 533static void LinkNamedMDNodes(Module *Dest, Module *Src) { 534 for (Module::const_named_metadata_iterator I = Src->named_metadata_begin(), 535 E = Src->named_metadata_end(); I != E; ++I) { 536 const NamedMDNode *SrcNMD = I; 537 NamedMDNode *DestNMD = Dest->getNamedMetadata(SrcNMD->getName()); 538 if (!DestNMD) 539 NamedMDNode::Create(SrcNMD, Dest); 540 else { 541 // Add Src elements into Dest node. 542 for (unsigned i = 0, e = SrcNMD->getNumOperands(); i != e; ++i) 543 DestNMD->addOperand(SrcNMD->getOperand(i)); 544 } 545 } 546} 547 548// LinkGlobals - Loop through the global variables in the src module and merge 549// them into the dest module. 550static bool LinkGlobals(Module *Dest, const Module *Src, 551 std::map<const Value*, Value*> &ValueMap, 552 std::multimap<std::string, GlobalVariable *> &AppendingVars, 553 std::string *Err) { 554 ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable(); 555 556 // Loop over all of the globals in the src module, mapping them over as we go 557 for (Module::const_global_iterator I = Src->global_begin(), 558 E = Src->global_end(); I != E; ++I) { 559 const GlobalVariable *SGV = I; 560 GlobalValue *DGV = 0; 561 562 // Check to see if may have to link the global with the global, alias or 563 // function. 564 if (SGV->hasName() && !SGV->hasLocalLinkage()) 565 DGV = cast_or_null<GlobalValue>(DestSymTab.lookup(SGV->getName())); 566 567 // If we found a global with the same name in the dest module, but it has 568 // internal linkage, we are really not doing any linkage here. 569 if (DGV && DGV->hasLocalLinkage()) 570 DGV = 0; 571 572 // If types don't agree due to opaque types, try to resolve them. 573 if (DGV && DGV->getType() != SGV->getType()) 574 RecursiveResolveTypes(SGV->getType(), DGV->getType()); 575 576 assert((SGV->hasInitializer() || SGV->hasExternalWeakLinkage() || 577 SGV->hasExternalLinkage() || SGV->hasDLLImportLinkage()) && 578 "Global must either be external or have an initializer!"); 579 580 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 581 bool LinkFromSrc = false; 582 if (GetLinkageResult(DGV, SGV, NewLinkage, LinkFromSrc, Err)) 583 return true; 584 585 if (DGV == 0) { 586 // No linking to be performed, simply create an identical version of the 587 // symbol over in the dest module... the initializer will be filled in 588 // later by LinkGlobalInits. 589 GlobalVariable *NewDGV = 590 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 591 SGV->isConstant(), SGV->getLinkage(), /*init*/0, 592 SGV->getName(), 0, false, 593 SGV->getType()->getAddressSpace()); 594 // Propagate alignment, visibility and section info. 595 CopyGVAttributes(NewDGV, SGV); 596 597 // If the LLVM runtime renamed the global, but it is an externally visible 598 // symbol, DGV must be an existing global with internal linkage. Rename 599 // it. 600 if (!NewDGV->hasLocalLinkage() && NewDGV->getName() != SGV->getName()) 601 ForceRenaming(NewDGV, SGV->getName()); 602 603 // Make sure to remember this mapping. 604 ValueMap[SGV] = NewDGV; 605 606 // Keep track that this is an appending variable. 607 if (SGV->hasAppendingLinkage()) 608 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV)); 609 continue; 610 } 611 612 // If the visibilities of the symbols disagree and the destination is a 613 // prototype, take the visibility of its input. 614 if (DGV->isDeclaration()) 615 DGV->setVisibility(SGV->getVisibility()); 616 617 if (DGV->hasAppendingLinkage()) { 618 // No linking is performed yet. Just insert a new copy of the global, and 619 // keep track of the fact that it is an appending variable in the 620 // AppendingVars map. The name is cleared out so that no linkage is 621 // performed. 622 GlobalVariable *NewDGV = 623 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 624 SGV->isConstant(), SGV->getLinkage(), /*init*/0, 625 "", 0, false, 626 SGV->getType()->getAddressSpace()); 627 628 // Set alignment allowing CopyGVAttributes merge it with alignment of SGV. 629 NewDGV->setAlignment(DGV->getAlignment()); 630 // Propagate alignment, section and visibility info. 631 CopyGVAttributes(NewDGV, SGV); 632 633 // Make sure to remember this mapping... 634 ValueMap[SGV] = NewDGV; 635 636 // Keep track that this is an appending variable... 637 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV)); 638 continue; 639 } 640 641 if (LinkFromSrc) { 642 if (isa<GlobalAlias>(DGV)) 643 return Error(Err, "Global-Alias Collision on '" + SGV->getName() + 644 "': symbol multiple defined"); 645 646 // If the types don't match, and if we are to link from the source, nuke 647 // DGV and create a new one of the appropriate type. Note that the thing 648 // we are replacing may be a function (if a prototype, weak, etc) or a 649 // global variable. 650 GlobalVariable *NewDGV = 651 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 652 SGV->isConstant(), NewLinkage, /*init*/0, 653 DGV->getName(), 0, false, 654 SGV->getType()->getAddressSpace()); 655 656 // Propagate alignment, section, and visibility info. 657 CopyGVAttributes(NewDGV, SGV); 658 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV, 659 DGV->getType())); 660 661 // DGV will conflict with NewDGV because they both had the same 662 // name. We must erase this now so ForceRenaming doesn't assert 663 // because DGV might not have internal linkage. 664 if (GlobalVariable *Var = dyn_cast<GlobalVariable>(DGV)) 665 Var->eraseFromParent(); 666 else 667 cast<Function>(DGV)->eraseFromParent(); 668 669 // If the symbol table renamed the global, but it is an externally visible 670 // symbol, DGV must be an existing global with internal linkage. Rename. 671 if (NewDGV->getName() != SGV->getName() && !NewDGV->hasLocalLinkage()) 672 ForceRenaming(NewDGV, SGV->getName()); 673 674 // Inherit const as appropriate. 675 NewDGV->setConstant(SGV->isConstant()); 676 677 // Make sure to remember this mapping. 678 ValueMap[SGV] = NewDGV; 679 continue; 680 } 681 682 // Not "link from source", keep the one in the DestModule and remap the 683 // input onto it. 684 685 // Special case for const propagation. 686 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) 687 if (DGVar->isDeclaration() && SGV->isConstant() && !DGVar->isConstant()) 688 DGVar->setConstant(true); 689 690 // SGV is global, but DGV is alias. 691 if (isa<GlobalAlias>(DGV)) { 692 // The only valid mappings are: 693 // - SGV is external declaration, which is effectively a no-op. 694 // - SGV is weak, when we just need to throw SGV out. 695 if (!SGV->isDeclaration() && !SGV->isWeakForLinker()) 696 return Error(Err, "Global-Alias Collision on '" + SGV->getName() + 697 "': symbol multiple defined"); 698 } 699 700 // Set calculated linkage 701 DGV->setLinkage(NewLinkage); 702 703 // Make sure to remember this mapping... 704 ValueMap[SGV] = ConstantExpr::getBitCast(DGV, SGV->getType()); 705 } 706 return false; 707} 708 709static GlobalValue::LinkageTypes 710CalculateAliasLinkage(const GlobalValue *SGV, const GlobalValue *DGV) { 711 GlobalValue::LinkageTypes SL = SGV->getLinkage(); 712 GlobalValue::LinkageTypes DL = DGV->getLinkage(); 713 if (SL == GlobalValue::ExternalLinkage || DL == GlobalValue::ExternalLinkage) 714 return GlobalValue::ExternalLinkage; 715 else if (SL == GlobalValue::WeakAnyLinkage || 716 DL == GlobalValue::WeakAnyLinkage) 717 return GlobalValue::WeakAnyLinkage; 718 else if (SL == GlobalValue::WeakODRLinkage || 719 DL == GlobalValue::WeakODRLinkage) 720 return GlobalValue::WeakODRLinkage; 721 else if (SL == GlobalValue::InternalLinkage && 722 DL == GlobalValue::InternalLinkage) 723 return GlobalValue::InternalLinkage; 724 else if (SL == GlobalValue::LinkerPrivateLinkage && 725 DL == GlobalValue::LinkerPrivateLinkage) 726 return GlobalValue::LinkerPrivateLinkage; 727 else { 728 assert (SL == GlobalValue::PrivateLinkage && 729 DL == GlobalValue::PrivateLinkage && "Unexpected linkage type"); 730 return GlobalValue::PrivateLinkage; 731 } 732} 733 734// LinkAlias - Loop through the alias in the src module and link them into the 735// dest module. We're assuming, that all functions/global variables were already 736// linked in. 737static bool LinkAlias(Module *Dest, const Module *Src, 738 std::map<const Value*, Value*> &ValueMap, 739 std::string *Err) { 740 // Loop over all alias in the src module 741 for (Module::const_alias_iterator I = Src->alias_begin(), 742 E = Src->alias_end(); I != E; ++I) { 743 const GlobalAlias *SGA = I; 744 const GlobalValue *SAliasee = SGA->getAliasedGlobal(); 745 GlobalAlias *NewGA = NULL; 746 747 // Globals were already linked, thus we can just query ValueMap for variant 748 // of SAliasee in Dest. 749 std::map<const Value*,Value*>::const_iterator VMI = ValueMap.find(SAliasee); 750 assert(VMI != ValueMap.end() && "Aliasee not linked"); 751 GlobalValue* DAliasee = cast<GlobalValue>(VMI->second); 752 GlobalValue* DGV = NULL; 753 754 // Try to find something 'similar' to SGA in destination module. 755 if (!DGV && !SGA->hasLocalLinkage()) { 756 DGV = Dest->getNamedAlias(SGA->getName()); 757 758 // If types don't agree due to opaque types, try to resolve them. 759 if (DGV && DGV->getType() != SGA->getType()) 760 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 761 } 762 763 if (!DGV && !SGA->hasLocalLinkage()) { 764 DGV = Dest->getGlobalVariable(SGA->getName()); 765 766 // If types don't agree due to opaque types, try to resolve them. 767 if (DGV && DGV->getType() != SGA->getType()) 768 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 769 } 770 771 if (!DGV && !SGA->hasLocalLinkage()) { 772 DGV = Dest->getFunction(SGA->getName()); 773 774 // If types don't agree due to opaque types, try to resolve them. 775 if (DGV && DGV->getType() != SGA->getType()) 776 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 777 } 778 779 // No linking to be performed on internal stuff. 780 if (DGV && DGV->hasLocalLinkage()) 781 DGV = NULL; 782 783 if (GlobalAlias *DGA = dyn_cast_or_null<GlobalAlias>(DGV)) { 784 // Types are known to be the same, check whether aliasees equal. As 785 // globals are already linked we just need query ValueMap to find the 786 // mapping. 787 if (DAliasee == DGA->getAliasedGlobal()) { 788 // This is just two copies of the same alias. Propagate linkage, if 789 // necessary. 790 DGA->setLinkage(CalculateAliasLinkage(SGA, DGA)); 791 792 NewGA = DGA; 793 // Proceed to 'common' steps 794 } else 795 return Error(Err, "Alias Collision on '" + SGA->getName()+ 796 "': aliases have different aliasees"); 797 } else if (GlobalVariable *DGVar = dyn_cast_or_null<GlobalVariable>(DGV)) { 798 // The only allowed way is to link alias with external declaration or weak 799 // symbol.. 800 if (DGVar->isDeclaration() || DGVar->isWeakForLinker()) { 801 // But only if aliasee is global too... 802 if (!isa<GlobalVariable>(DAliasee)) 803 return Error(Err, "Global-Alias Collision on '" + SGA->getName() + 804 "': aliasee is not global variable"); 805 806 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 807 SGA->getName(), DAliasee, Dest); 808 CopyGVAttributes(NewGA, SGA); 809 810 // Any uses of DGV need to change to NewGA, with cast, if needed. 811 if (SGA->getType() != DGVar->getType()) 812 DGVar->replaceAllUsesWith(ConstantExpr::getBitCast(NewGA, 813 DGVar->getType())); 814 else 815 DGVar->replaceAllUsesWith(NewGA); 816 817 // DGVar will conflict with NewGA because they both had the same 818 // name. We must erase this now so ForceRenaming doesn't assert 819 // because DGV might not have internal linkage. 820 DGVar->eraseFromParent(); 821 822 // Proceed to 'common' steps 823 } else 824 return Error(Err, "Global-Alias Collision on '" + SGA->getName() + 825 "': symbol multiple defined"); 826 } else if (Function *DF = dyn_cast_or_null<Function>(DGV)) { 827 // The only allowed way is to link alias with external declaration or weak 828 // symbol... 829 if (DF->isDeclaration() || DF->isWeakForLinker()) { 830 // But only if aliasee is function too... 831 if (!isa<Function>(DAliasee)) 832 return Error(Err, "Function-Alias Collision on '" + SGA->getName() + 833 "': aliasee is not function"); 834 835 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 836 SGA->getName(), DAliasee, Dest); 837 CopyGVAttributes(NewGA, SGA); 838 839 // Any uses of DF need to change to NewGA, with cast, if needed. 840 if (SGA->getType() != DF->getType()) 841 DF->replaceAllUsesWith(ConstantExpr::getBitCast(NewGA, 842 DF->getType())); 843 else 844 DF->replaceAllUsesWith(NewGA); 845 846 // DF will conflict with NewGA because they both had the same 847 // name. We must erase this now so ForceRenaming doesn't assert 848 // because DF might not have internal linkage. 849 DF->eraseFromParent(); 850 851 // Proceed to 'common' steps 852 } else 853 return Error(Err, "Function-Alias Collision on '" + SGA->getName() + 854 "': symbol multiple defined"); 855 } else { 856 // No linking to be performed, simply create an identical version of the 857 // alias over in the dest module... 858 Constant *Aliasee = DAliasee; 859 // Fixup aliases to bitcasts. Note that aliases to GEPs are still broken 860 // by this, but aliases to GEPs are broken to a lot of other things, so 861 // it's less important. 862 if (SGA->getType() != DAliasee->getType()) 863 Aliasee = ConstantExpr::getBitCast(DAliasee, SGA->getType()); 864 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 865 SGA->getName(), Aliasee, Dest); 866 CopyGVAttributes(NewGA, SGA); 867 868 // Proceed to 'common' steps 869 } 870 871 assert(NewGA && "No alias was created in destination module!"); 872 873 // If the symbol table renamed the alias, but it is an externally visible 874 // symbol, DGA must be an global value with internal linkage. Rename it. 875 if (NewGA->getName() != SGA->getName() && 876 !NewGA->hasLocalLinkage()) 877 ForceRenaming(NewGA, SGA->getName()); 878 879 // Remember this mapping so uses in the source module get remapped 880 // later by RemapOperand. 881 ValueMap[SGA] = NewGA; 882 } 883 884 return false; 885} 886 887 888// LinkGlobalInits - Update the initializers in the Dest module now that all 889// globals that may be referenced are in Dest. 890static bool LinkGlobalInits(Module *Dest, const Module *Src, 891 std::map<const Value*, Value*> &ValueMap, 892 std::string *Err) { 893 // Loop over all of the globals in the src module, mapping them over as we go 894 for (Module::const_global_iterator I = Src->global_begin(), 895 E = Src->global_end(); I != E; ++I) { 896 const GlobalVariable *SGV = I; 897 898 if (SGV->hasInitializer()) { // Only process initialized GV's 899 // Figure out what the initializer looks like in the dest module... 900 Constant *SInit = 901 cast<Constant>(RemapOperand(SGV->getInitializer(), ValueMap)); 902 // Grab destination global variable or alias. 903 GlobalValue *DGV = cast<GlobalValue>(ValueMap[SGV]->stripPointerCasts()); 904 905 // If dest if global variable, check that initializers match. 906 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) { 907 if (DGVar->hasInitializer()) { 908 if (SGV->hasExternalLinkage()) { 909 if (DGVar->getInitializer() != SInit) 910 return Error(Err, "Global Variable Collision on '" + 911 SGV->getName() + 912 "': global variables have different initializers"); 913 } else if (DGVar->isWeakForLinker()) { 914 // Nothing is required, mapped values will take the new global 915 // automatically. 916 } else if (SGV->isWeakForLinker()) { 917 // Nothing is required, mapped values will take the new global 918 // automatically. 919 } else if (DGVar->hasAppendingLinkage()) { 920 llvm_unreachable("Appending linkage unimplemented!"); 921 } else { 922 llvm_unreachable("Unknown linkage!"); 923 } 924 } else { 925 // Copy the initializer over now... 926 DGVar->setInitializer(SInit); 927 } 928 } else { 929 // Destination is alias, the only valid situation is when source is 930 // weak. Also, note, that we already checked linkage in LinkGlobals(), 931 // thus we assert here. 932 // FIXME: Should we weaken this assumption, 'dereference' alias and 933 // check for initializer of aliasee? 934 assert(SGV->isWeakForLinker()); 935 } 936 } 937 } 938 return false; 939} 940 941// LinkFunctionProtos - Link the functions together between the two modules, 942// without doing function bodies... this just adds external function prototypes 943// to the Dest function... 944// 945static bool LinkFunctionProtos(Module *Dest, const Module *Src, 946 std::map<const Value*, Value*> &ValueMap, 947 std::string *Err) { 948 ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable(); 949 950 // Loop over all of the functions in the src module, mapping them over 951 for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) { 952 const Function *SF = I; // SrcFunction 953 GlobalValue *DGV = 0; 954 955 // Check to see if may have to link the function with the global, alias or 956 // function. 957 if (SF->hasName() && !SF->hasLocalLinkage()) 958 DGV = cast_or_null<GlobalValue>(DestSymTab.lookup(SF->getName())); 959 960 // If we found a global with the same name in the dest module, but it has 961 // internal linkage, we are really not doing any linkage here. 962 if (DGV && DGV->hasLocalLinkage()) 963 DGV = 0; 964 965 // If types don't agree due to opaque types, try to resolve them. 966 if (DGV && DGV->getType() != SF->getType()) 967 RecursiveResolveTypes(SF->getType(), DGV->getType()); 968 969 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 970 bool LinkFromSrc = false; 971 if (GetLinkageResult(DGV, SF, NewLinkage, LinkFromSrc, Err)) 972 return true; 973 974 // If there is no linkage to be performed, just bring over SF without 975 // modifying it. 976 if (DGV == 0) { 977 // Function does not already exist, simply insert an function signature 978 // identical to SF into the dest module. 979 Function *NewDF = Function::Create(SF->getFunctionType(), 980 SF->getLinkage(), 981 SF->getName(), Dest); 982 CopyGVAttributes(NewDF, SF); 983 984 // If the LLVM runtime renamed the function, but it is an externally 985 // visible symbol, DF must be an existing function with internal linkage. 986 // Rename it. 987 if (!NewDF->hasLocalLinkage() && NewDF->getName() != SF->getName()) 988 ForceRenaming(NewDF, SF->getName()); 989 990 // ... and remember this mapping... 991 ValueMap[SF] = NewDF; 992 continue; 993 } 994 995 // If the visibilities of the symbols disagree and the destination is a 996 // prototype, take the visibility of its input. 997 if (DGV->isDeclaration()) 998 DGV->setVisibility(SF->getVisibility()); 999 1000 if (LinkFromSrc) { 1001 if (isa<GlobalAlias>(DGV)) 1002 return Error(Err, "Function-Alias Collision on '" + SF->getName() + 1003 "': symbol multiple defined"); 1004 1005 // We have a definition of the same name but different type in the 1006 // source module. Copy the prototype to the destination and replace 1007 // uses of the destination's prototype with the new prototype. 1008 Function *NewDF = Function::Create(SF->getFunctionType(), NewLinkage, 1009 SF->getName(), Dest); 1010 CopyGVAttributes(NewDF, SF); 1011 1012 // Any uses of DF need to change to NewDF, with cast 1013 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, 1014 DGV->getType())); 1015 1016 // DF will conflict with NewDF because they both had the same. We must 1017 // erase this now so ForceRenaming doesn't assert because DF might 1018 // not have internal linkage. 1019 if (GlobalVariable *Var = dyn_cast<GlobalVariable>(DGV)) 1020 Var->eraseFromParent(); 1021 else 1022 cast<Function>(DGV)->eraseFromParent(); 1023 1024 // If the symbol table renamed the function, but it is an externally 1025 // visible symbol, DF must be an existing function with internal 1026 // linkage. Rename it. 1027 if (NewDF->getName() != SF->getName() && !NewDF->hasLocalLinkage()) 1028 ForceRenaming(NewDF, SF->getName()); 1029 1030 // Remember this mapping so uses in the source module get remapped 1031 // later by RemapOperand. 1032 ValueMap[SF] = NewDF; 1033 continue; 1034 } 1035 1036 // Not "link from source", keep the one in the DestModule and remap the 1037 // input onto it. 1038 1039 if (isa<GlobalAlias>(DGV)) { 1040 // The only valid mappings are: 1041 // - SF is external declaration, which is effectively a no-op. 1042 // - SF is weak, when we just need to throw SF out. 1043 if (!SF->isDeclaration() && !SF->isWeakForLinker()) 1044 return Error(Err, "Function-Alias Collision on '" + SF->getName() + 1045 "': symbol multiple defined"); 1046 } 1047 1048 // Set calculated linkage 1049 DGV->setLinkage(NewLinkage); 1050 1051 // Make sure to remember this mapping. 1052 ValueMap[SF] = ConstantExpr::getBitCast(DGV, SF->getType()); 1053 } 1054 return false; 1055} 1056 1057// LinkFunctionBody - Copy the source function over into the dest function and 1058// fix up references to values. At this point we know that Dest is an external 1059// function, and that Src is not. 1060static bool LinkFunctionBody(Function *Dest, Function *Src, 1061 std::map<const Value*, Value*> &ValueMap, 1062 std::string *Err) { 1063 assert(Src && Dest && Dest->isDeclaration() && !Src->isDeclaration()); 1064 1065 // Go through and convert function arguments over, remembering the mapping. 1066 Function::arg_iterator DI = Dest->arg_begin(); 1067 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 1068 I != E; ++I, ++DI) { 1069 DI->setName(I->getName()); // Copy the name information over... 1070 1071 // Add a mapping to our local map 1072 ValueMap[I] = DI; 1073 } 1074 1075 // Splice the body of the source function into the dest function. 1076 Dest->getBasicBlockList().splice(Dest->end(), Src->getBasicBlockList()); 1077 1078 // At this point, all of the instructions and values of the function are now 1079 // copied over. The only problem is that they are still referencing values in 1080 // the Source function as operands. Loop through all of the operands of the 1081 // functions and patch them up to point to the local versions... 1082 // 1083 for (Function::iterator BB = Dest->begin(), BE = Dest->end(); BB != BE; ++BB) 1084 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) 1085 for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end(); 1086 OI != OE; ++OI) 1087 if (!isa<Instruction>(*OI) && !isa<BasicBlock>(*OI)) 1088 *OI = RemapOperand(*OI, ValueMap); 1089 1090 // There is no need to map the arguments anymore. 1091 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 1092 I != E; ++I) 1093 ValueMap.erase(I); 1094 1095 return false; 1096} 1097 1098 1099// LinkFunctionBodies - Link in the function bodies that are defined in the 1100// source module into the DestModule. This consists basically of copying the 1101// function over and fixing up references to values. 1102static bool LinkFunctionBodies(Module *Dest, Module *Src, 1103 std::map<const Value*, Value*> &ValueMap, 1104 std::string *Err) { 1105 1106 // Loop over all of the functions in the src module, mapping them over as we 1107 // go 1108 for (Module::iterator SF = Src->begin(), E = Src->end(); SF != E; ++SF) { 1109 if (!SF->isDeclaration()) { // No body if function is external 1110 Function *DF = dyn_cast<Function>(ValueMap[SF]); // Destination function 1111 1112 // DF not external SF external? 1113 if (DF && DF->isDeclaration()) 1114 // Only provide the function body if there isn't one already. 1115 if (LinkFunctionBody(DF, SF, ValueMap, Err)) 1116 return true; 1117 } 1118 } 1119 return false; 1120} 1121 1122// LinkAppendingVars - If there were any appending global variables, link them 1123// together now. Return true on error. 1124static bool LinkAppendingVars(Module *M, 1125 std::multimap<std::string, GlobalVariable *> &AppendingVars, 1126 std::string *ErrorMsg) { 1127 if (AppendingVars.empty()) return false; // Nothing to do. 1128 1129 // Loop over the multimap of appending vars, processing any variables with the 1130 // same name, forming a new appending global variable with both of the 1131 // initializers merged together, then rewrite references to the old variables 1132 // and delete them. 1133 std::vector<Constant*> Inits; 1134 while (AppendingVars.size() > 1) { 1135 // Get the first two elements in the map... 1136 std::multimap<std::string, 1137 GlobalVariable*>::iterator Second = AppendingVars.begin(), First=Second++; 1138 1139 // If the first two elements are for different names, there is no pair... 1140 // Otherwise there is a pair, so link them together... 1141 if (First->first == Second->first) { 1142 GlobalVariable *G1 = First->second, *G2 = Second->second; 1143 const ArrayType *T1 = cast<ArrayType>(G1->getType()->getElementType()); 1144 const ArrayType *T2 = cast<ArrayType>(G2->getType()->getElementType()); 1145 1146 // Check to see that they two arrays agree on type... 1147 if (T1->getElementType() != T2->getElementType()) 1148 return Error(ErrorMsg, 1149 "Appending variables with different element types need to be linked!"); 1150 if (G1->isConstant() != G2->isConstant()) 1151 return Error(ErrorMsg, 1152 "Appending variables linked with different const'ness!"); 1153 1154 if (G1->getAlignment() != G2->getAlignment()) 1155 return Error(ErrorMsg, 1156 "Appending variables with different alignment need to be linked!"); 1157 1158 if (G1->getVisibility() != G2->getVisibility()) 1159 return Error(ErrorMsg, 1160 "Appending variables with different visibility need to be linked!"); 1161 1162 if (G1->getSection() != G2->getSection()) 1163 return Error(ErrorMsg, 1164 "Appending variables with different section name need to be linked!"); 1165 1166 unsigned NewSize = T1->getNumElements() + T2->getNumElements(); 1167 ArrayType *NewType = ArrayType::get(T1->getElementType(), 1168 NewSize); 1169 1170 G1->setName(""); // Clear G1's name in case of a conflict! 1171 1172 // Create the new global variable... 1173 GlobalVariable *NG = 1174 new GlobalVariable(*M, NewType, G1->isConstant(), G1->getLinkage(), 1175 /*init*/0, First->first, 0, G1->isThreadLocal(), 1176 G1->getType()->getAddressSpace()); 1177 1178 // Propagate alignment, visibility and section info. 1179 CopyGVAttributes(NG, G1); 1180 1181 // Merge the initializer... 1182 Inits.reserve(NewSize); 1183 if (ConstantArray *I = dyn_cast<ConstantArray>(G1->getInitializer())) { 1184 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i) 1185 Inits.push_back(I->getOperand(i)); 1186 } else { 1187 assert(isa<ConstantAggregateZero>(G1->getInitializer())); 1188 Constant *CV = Constant::getNullValue(T1->getElementType()); 1189 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i) 1190 Inits.push_back(CV); 1191 } 1192 if (ConstantArray *I = dyn_cast<ConstantArray>(G2->getInitializer())) { 1193 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i) 1194 Inits.push_back(I->getOperand(i)); 1195 } else { 1196 assert(isa<ConstantAggregateZero>(G2->getInitializer())); 1197 Constant *CV = Constant::getNullValue(T2->getElementType()); 1198 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i) 1199 Inits.push_back(CV); 1200 } 1201 NG->setInitializer(ConstantArray::get(NewType, Inits)); 1202 Inits.clear(); 1203 1204 // Replace any uses of the two global variables with uses of the new 1205 // global... 1206 1207 // FIXME: This should rewrite simple/straight-forward uses such as 1208 // getelementptr instructions to not use the Cast! 1209 G1->replaceAllUsesWith(ConstantExpr::getBitCast(NG, 1210 G1->getType())); 1211 G2->replaceAllUsesWith(ConstantExpr::getBitCast(NG, 1212 G2->getType())); 1213 1214 // Remove the two globals from the module now... 1215 M->getGlobalList().erase(G1); 1216 M->getGlobalList().erase(G2); 1217 1218 // Put the new global into the AppendingVars map so that we can handle 1219 // linking of more than two vars... 1220 Second->second = NG; 1221 } 1222 AppendingVars.erase(First); 1223 } 1224 1225 return false; 1226} 1227 1228static bool ResolveAliases(Module *Dest) { 1229 for (Module::alias_iterator I = Dest->alias_begin(), E = Dest->alias_end(); 1230 I != E; ++I) 1231 // We can't sue resolveGlobalAlias here because we need to preserve 1232 // bitcasts and GEPs. 1233 if (const Constant *C = I->getAliasee()) { 1234 while (dyn_cast<GlobalAlias>(C)) 1235 C = cast<GlobalAlias>(C)->getAliasee(); 1236 const GlobalValue *GV = dyn_cast<GlobalValue>(C); 1237 if (C != I && !(GV && GV->isDeclaration())) 1238 I->replaceAllUsesWith(const_cast<Constant*>(C)); 1239 } 1240 1241 return false; 1242} 1243 1244// LinkModules - This function links two modules together, with the resulting 1245// left module modified to be the composite of the two input modules. If an 1246// error occurs, true is returned and ErrorMsg (if not null) is set to indicate 1247// the problem. Upon failure, the Dest module could be in a modified state, and 1248// shouldn't be relied on to be consistent. 1249bool 1250Linker::LinkModules(Module *Dest, Module *Src, std::string *ErrorMsg) { 1251 assert(Dest != 0 && "Invalid Destination module"); 1252 assert(Src != 0 && "Invalid Source Module"); 1253 1254 if (Dest->getDataLayout().empty()) { 1255 if (!Src->getDataLayout().empty()) { 1256 Dest->setDataLayout(Src->getDataLayout()); 1257 } else { 1258 std::string DataLayout; 1259 1260 if (Dest->getEndianness() == Module::AnyEndianness) { 1261 if (Src->getEndianness() == Module::BigEndian) 1262 DataLayout.append("E"); 1263 else if (Src->getEndianness() == Module::LittleEndian) 1264 DataLayout.append("e"); 1265 } 1266 1267 if (Dest->getPointerSize() == Module::AnyPointerSize) { 1268 if (Src->getPointerSize() == Module::Pointer64) 1269 DataLayout.append(DataLayout.length() == 0 ? "p:64:64" : "-p:64:64"); 1270 else if (Src->getPointerSize() == Module::Pointer32) 1271 DataLayout.append(DataLayout.length() == 0 ? "p:32:32" : "-p:32:32"); 1272 } 1273 Dest->setDataLayout(DataLayout); 1274 } 1275 } 1276 1277 // Copy the target triple from the source to dest if the dest's is empty. 1278 if (Dest->getTargetTriple().empty() && !Src->getTargetTriple().empty()) 1279 Dest->setTargetTriple(Src->getTargetTriple()); 1280 1281 if (!Src->getDataLayout().empty() && !Dest->getDataLayout().empty() && 1282 Src->getDataLayout() != Dest->getDataLayout()) 1283 errs() << "WARNING: Linking two modules of different data layouts!\n"; 1284 if (!Src->getTargetTriple().empty() && 1285 Dest->getTargetTriple() != Src->getTargetTriple()) 1286 errs() << "WARNING: Linking two modules of different target triples!\n"; 1287 1288 // Append the module inline asm string. 1289 if (!Src->getModuleInlineAsm().empty()) { 1290 if (Dest->getModuleInlineAsm().empty()) 1291 Dest->setModuleInlineAsm(Src->getModuleInlineAsm()); 1292 else 1293 Dest->setModuleInlineAsm(Dest->getModuleInlineAsm()+"\n"+ 1294 Src->getModuleInlineAsm()); 1295 } 1296 1297 // Update the destination module's dependent libraries list with the libraries 1298 // from the source module. There's no opportunity for duplicates here as the 1299 // Module ensures that duplicate insertions are discarded. 1300 for (Module::lib_iterator SI = Src->lib_begin(), SE = Src->lib_end(); 1301 SI != SE; ++SI) 1302 Dest->addLibrary(*SI); 1303 1304 // LinkTypes - Go through the symbol table of the Src module and see if any 1305 // types are named in the src module that are not named in the Dst module. 1306 // Make sure there are no type name conflicts. 1307 if (LinkTypes(Dest, Src, ErrorMsg)) 1308 return true; 1309 1310 // ValueMap - Mapping of values from what they used to be in Src, to what they 1311 // are now in Dest. 1312 std::map<const Value*, Value*> ValueMap; 1313 1314 // AppendingVars - Keep track of global variables in the destination module 1315 // with appending linkage. After the module is linked together, they are 1316 // appended and the module is rewritten. 1317 std::multimap<std::string, GlobalVariable *> AppendingVars; 1318 for (Module::global_iterator I = Dest->global_begin(), E = Dest->global_end(); 1319 I != E; ++I) { 1320 // Add all of the appending globals already in the Dest module to 1321 // AppendingVars. 1322 if (I->hasAppendingLinkage()) 1323 AppendingVars.insert(std::make_pair(I->getName(), I)); 1324 } 1325 1326 // Insert all of the named mdnoes in Src into the Dest module. 1327 LinkNamedMDNodes(Dest, Src); 1328 1329 // Insert all of the globals in src into the Dest module... without linking 1330 // initializers (which could refer to functions not yet mapped over). 1331 if (LinkGlobals(Dest, Src, ValueMap, AppendingVars, ErrorMsg)) 1332 return true; 1333 1334 // Link the functions together between the two modules, without doing function 1335 // bodies... this just adds external function prototypes to the Dest 1336 // function... We do this so that when we begin processing function bodies, 1337 // all of the global values that may be referenced are available in our 1338 // ValueMap. 1339 if (LinkFunctionProtos(Dest, Src, ValueMap, ErrorMsg)) 1340 return true; 1341 1342 // If there were any alias, link them now. We really need to do this now, 1343 // because all of the aliases that may be referenced need to be available in 1344 // ValueMap 1345 if (LinkAlias(Dest, Src, ValueMap, ErrorMsg)) return true; 1346 1347 // Update the initializers in the Dest module now that all globals that may 1348 // be referenced are in Dest. 1349 if (LinkGlobalInits(Dest, Src, ValueMap, ErrorMsg)) return true; 1350 1351 // Link in the function bodies that are defined in the source module into the 1352 // DestModule. This consists basically of copying the function over and 1353 // fixing up references to values. 1354 if (LinkFunctionBodies(Dest, Src, ValueMap, ErrorMsg)) return true; 1355 1356 // If there were any appending global variables, link them together now. 1357 if (LinkAppendingVars(Dest, AppendingVars, ErrorMsg)) return true; 1358 1359 // Resolve all uses of aliases with aliasees 1360 if (ResolveAliases(Dest)) return true; 1361 1362 // If the source library's module id is in the dependent library list of the 1363 // destination library, remove it since that module is now linked in. 1364 sys::Path modId; 1365 modId.set(Src->getModuleIdentifier()); 1366 if (!modId.isEmpty()) 1367 Dest->removeLibrary(modId.getBasename()); 1368 1369 return false; 1370} 1371 1372// vim: sw=2 1373