LinkModules.cpp revision 8a6411ca14e6216192ccddb18c5196a26e98e1b3
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/ErrorHandling.h" 29#include "llvm/System/Path.h" 30#include "llvm/ADT/DenseMap.h" 31#include <sstream> 32using namespace llvm; 33 34// Error - Simple wrapper function to conditionally assign to E and return true. 35// This just makes error return conditions a little bit simpler... 36static inline bool Error(std::string *E, const Twine &Message) { 37 if (E) *E = Message.str(); 38 return true; 39} 40 41// Function: ResolveTypes() 42// 43// Description: 44// Attempt to link the two specified types together. 45// 46// Inputs: 47// DestTy - The type to which we wish to resolve. 48// SrcTy - The original type which we want to resolve. 49// 50// Outputs: 51// DestST - The symbol table in which the new type should be placed. 52// 53// Return value: 54// true - There is an error and the types cannot yet be linked. 55// false - No errors. 56// 57static bool ResolveTypes(const Type *DestTy, const Type *SrcTy) { 58 if (DestTy == SrcTy) return false; // If already equal, noop 59 assert(DestTy && SrcTy && "Can't handle null types"); 60 61 if (const OpaqueType *OT = dyn_cast<OpaqueType>(DestTy)) { 62 // Type _is_ in module, just opaque... 63 const_cast<OpaqueType*>(OT)->refineAbstractTypeTo(SrcTy); 64 } else if (const OpaqueType *OT = dyn_cast<OpaqueType>(SrcTy)) { 65 const_cast<OpaqueType*>(OT)->refineAbstractTypeTo(DestTy); 66 } else { 67 return true; // Cannot link types... not-equal and neither is opaque. 68 } 69 return false; 70} 71 72/// LinkerTypeMap - This implements a map of types that is stable 73/// even if types are resolved/refined to other types. This is not a general 74/// purpose map, it is specific to the linker's use. 75namespace { 76class LinkerTypeMap : public AbstractTypeUser { 77 typedef DenseMap<const Type*, PATypeHolder> TheMapTy; 78 TheMapTy TheMap; 79 80 LinkerTypeMap(const LinkerTypeMap&); // DO NOT IMPLEMENT 81 void operator=(const LinkerTypeMap&); // DO NOT IMPLEMENT 82public: 83 LinkerTypeMap() {} 84 ~LinkerTypeMap() { 85 for (DenseMap<const Type*, PATypeHolder>::iterator I = TheMap.begin(), 86 E = TheMap.end(); I != E; ++I) 87 I->first->removeAbstractTypeUser(this); 88 } 89 90 /// lookup - Return the value for the specified type or null if it doesn't 91 /// exist. 92 const Type *lookup(const Type *Ty) const { 93 TheMapTy::const_iterator I = TheMap.find(Ty); 94 if (I != TheMap.end()) return I->second; 95 return 0; 96 } 97 98 /// erase - Remove the specified type, returning true if it was in the set. 99 bool erase(const Type *Ty) { 100 if (!TheMap.erase(Ty)) 101 return false; 102 if (Ty->isAbstract()) 103 Ty->removeAbstractTypeUser(this); 104 return true; 105 } 106 107 /// insert - This returns true if the pointer was new to the set, false if it 108 /// was already in the set. 109 bool insert(const Type *Src, const Type *Dst) { 110 if (!TheMap.insert(std::make_pair(Src, PATypeHolder(Dst))).second) 111 return false; // Already in map. 112 if (Src->isAbstract()) 113 Src->addAbstractTypeUser(this); 114 return true; 115 } 116 117protected: 118 /// refineAbstractType - The callback method invoked when an abstract type is 119 /// resolved to another type. An object must override this method to update 120 /// its internal state to reference NewType instead of OldType. 121 /// 122 virtual void refineAbstractType(const DerivedType *OldTy, 123 const Type *NewTy) { 124 TheMapTy::iterator I = TheMap.find(OldTy); 125 const Type *DstTy = I->second; 126 127 TheMap.erase(I); 128 if (OldTy->isAbstract()) 129 OldTy->removeAbstractTypeUser(this); 130 131 // Don't reinsert into the map if the key is concrete now. 132 if (NewTy->isAbstract()) 133 insert(NewTy, DstTy); 134 } 135 136 /// The other case which AbstractTypeUsers must be aware of is when a type 137 /// makes the transition from being abstract (where it has clients on it's 138 /// AbstractTypeUsers list) to concrete (where it does not). This method 139 /// notifies ATU's when this occurs for a type. 140 virtual void typeBecameConcrete(const DerivedType *AbsTy) { 141 TheMap.erase(AbsTy); 142 AbsTy->removeAbstractTypeUser(this); 143 } 144 145 // for debugging... 146 virtual void dump() const { 147 errs() << "AbstractTypeSet!\n"; 148 } 149}; 150} 151 152 153// RecursiveResolveTypes - This is just like ResolveTypes, except that it 154// recurses down into derived types, merging the used types if the parent types 155// are compatible. 156static bool RecursiveResolveTypesI(const Type *DstTy, const Type *SrcTy, 157 LinkerTypeMap &Pointers) { 158 if (DstTy == SrcTy) return false; // If already equal, noop 159 160 // If we found our opaque type, resolve it now! 161 if (isa<OpaqueType>(DstTy) || isa<OpaqueType>(SrcTy)) 162 return ResolveTypes(DstTy, SrcTy); 163 164 // Two types cannot be resolved together if they are of different primitive 165 // type. For example, we cannot resolve an int to a float. 166 if (DstTy->getTypeID() != SrcTy->getTypeID()) return true; 167 168 // If neither type is abstract, then they really are just different types. 169 if (!DstTy->isAbstract() && !SrcTy->isAbstract()) 170 return true; 171 172 // Otherwise, resolve the used type used by this derived type... 173 switch (DstTy->getTypeID()) { 174 default: 175 return true; 176 case Type::FunctionTyID: { 177 const FunctionType *DstFT = cast<FunctionType>(DstTy); 178 const FunctionType *SrcFT = cast<FunctionType>(SrcTy); 179 if (DstFT->isVarArg() != SrcFT->isVarArg() || 180 DstFT->getNumContainedTypes() != SrcFT->getNumContainedTypes()) 181 return true; 182 183 // Use TypeHolder's so recursive resolution won't break us. 184 PATypeHolder ST(SrcFT), DT(DstFT); 185 for (unsigned i = 0, e = DstFT->getNumContainedTypes(); i != e; ++i) { 186 const Type *SE = ST->getContainedType(i), *DE = DT->getContainedType(i); 187 if (SE != DE && RecursiveResolveTypesI(DE, SE, Pointers)) 188 return true; 189 } 190 return false; 191 } 192 case Type::StructTyID: { 193 const StructType *DstST = cast<StructType>(DstTy); 194 const StructType *SrcST = cast<StructType>(SrcTy); 195 if (DstST->getNumContainedTypes() != SrcST->getNumContainedTypes()) 196 return true; 197 198 PATypeHolder ST(SrcST), DT(DstST); 199 for (unsigned i = 0, e = DstST->getNumContainedTypes(); i != e; ++i) { 200 const Type *SE = ST->getContainedType(i), *DE = DT->getContainedType(i); 201 if (SE != DE && RecursiveResolveTypesI(DE, SE, Pointers)) 202 return true; 203 } 204 return false; 205 } 206 case Type::ArrayTyID: { 207 const ArrayType *DAT = cast<ArrayType>(DstTy); 208 const ArrayType *SAT = cast<ArrayType>(SrcTy); 209 if (DAT->getNumElements() != SAT->getNumElements()) return true; 210 return RecursiveResolveTypesI(DAT->getElementType(), SAT->getElementType(), 211 Pointers); 212 } 213 case Type::VectorTyID: { 214 const VectorType *DVT = cast<VectorType>(DstTy); 215 const VectorType *SVT = cast<VectorType>(SrcTy); 216 if (DVT->getNumElements() != SVT->getNumElements()) return true; 217 return RecursiveResolveTypesI(DVT->getElementType(), SVT->getElementType(), 218 Pointers); 219 } 220 case Type::PointerTyID: { 221 const PointerType *DstPT = cast<PointerType>(DstTy); 222 const PointerType *SrcPT = cast<PointerType>(SrcTy); 223 224 if (DstPT->getAddressSpace() != SrcPT->getAddressSpace()) 225 return true; 226 227 // If this is a pointer type, check to see if we have already seen it. If 228 // so, we are in a recursive branch. Cut off the search now. We cannot use 229 // an associative container for this search, because the type pointers (keys 230 // in the container) change whenever types get resolved. 231 if (SrcPT->isAbstract()) 232 if (const Type *ExistingDestTy = Pointers.lookup(SrcPT)) 233 return ExistingDestTy != DstPT; 234 235 if (DstPT->isAbstract()) 236 if (const Type *ExistingSrcTy = Pointers.lookup(DstPT)) 237 return ExistingSrcTy != SrcPT; 238 // Otherwise, add the current pointers to the vector to stop recursion on 239 // this pair. 240 if (DstPT->isAbstract()) 241 Pointers.insert(DstPT, SrcPT); 242 if (SrcPT->isAbstract()) 243 Pointers.insert(SrcPT, DstPT); 244 245 return RecursiveResolveTypesI(DstPT->getElementType(), 246 SrcPT->getElementType(), Pointers); 247 } 248 } 249} 250 251static bool RecursiveResolveTypes(const Type *DestTy, const Type *SrcTy) { 252 LinkerTypeMap PointerTypes; 253 return RecursiveResolveTypesI(DestTy, SrcTy, PointerTypes); 254} 255 256 257// LinkTypes - Go through the symbol table of the Src module and see if any 258// types are named in the src module that are not named in the Dst module. 259// Make sure there are no type name conflicts. 260static bool LinkTypes(Module *Dest, const Module *Src, std::string *Err) { 261 TypeSymbolTable *DestST = &Dest->getTypeSymbolTable(); 262 const TypeSymbolTable *SrcST = &Src->getTypeSymbolTable(); 263 264 // Look for a type plane for Type's... 265 TypeSymbolTable::const_iterator TI = SrcST->begin(); 266 TypeSymbolTable::const_iterator TE = SrcST->end(); 267 if (TI == TE) return false; // No named types, do nothing. 268 269 // Some types cannot be resolved immediately because they depend on other 270 // types being resolved to each other first. This contains a list of types we 271 // are waiting to recheck. 272 std::vector<std::string> DelayedTypesToResolve; 273 274 for ( ; TI != TE; ++TI ) { 275 const std::string &Name = TI->first; 276 const Type *RHS = TI->second; 277 278 // Check to see if this type name is already in the dest module. 279 Type *Entry = DestST->lookup(Name); 280 281 // If the name is just in the source module, bring it over to the dest. 282 if (Entry == 0) { 283 if (!Name.empty()) 284 DestST->insert(Name, const_cast<Type*>(RHS)); 285 } else if (ResolveTypes(Entry, RHS)) { 286 // They look different, save the types 'till later to resolve. 287 DelayedTypesToResolve.push_back(Name); 288 } 289 } 290 291 // Iteratively resolve types while we can... 292 while (!DelayedTypesToResolve.empty()) { 293 // Loop over all of the types, attempting to resolve them if possible... 294 unsigned OldSize = DelayedTypesToResolve.size(); 295 296 // Try direct resolution by name... 297 for (unsigned i = 0; i != DelayedTypesToResolve.size(); ++i) { 298 const std::string &Name = DelayedTypesToResolve[i]; 299 Type *T1 = SrcST->lookup(Name); 300 Type *T2 = DestST->lookup(Name); 301 if (!ResolveTypes(T2, T1)) { 302 // We are making progress! 303 DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i); 304 --i; 305 } 306 } 307 308 // Did we not eliminate any types? 309 if (DelayedTypesToResolve.size() == OldSize) { 310 // Attempt to resolve subelements of types. This allows us to merge these 311 // two types: { int* } and { opaque* } 312 for (unsigned i = 0, e = DelayedTypesToResolve.size(); i != e; ++i) { 313 const std::string &Name = DelayedTypesToResolve[i]; 314 if (!RecursiveResolveTypes(SrcST->lookup(Name), DestST->lookup(Name))) { 315 // We are making progress! 316 DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i); 317 318 // Go back to the main loop, perhaps we can resolve directly by name 319 // now... 320 break; 321 } 322 } 323 324 // If we STILL cannot resolve the types, then there is something wrong. 325 if (DelayedTypesToResolve.size() == OldSize) { 326 // Remove the symbol name from the destination. 327 DelayedTypesToResolve.pop_back(); 328 } 329 } 330 } 331 332 333 return false; 334} 335 336#ifndef NDEBUG 337static void PrintMap(const std::map<const Value*, Value*> &M) { 338 for (std::map<const Value*, Value*>::const_iterator I = M.begin(), E =M.end(); 339 I != E; ++I) { 340 errs() << " Fr: " << (void*)I->first << " "; 341 I->first->dump(); 342 errs() << " To: " << (void*)I->second << " "; 343 I->second->dump(); 344 errs() << "\n"; 345 } 346} 347#endif 348 349 350// RemapOperand - Use ValueMap to convert constants from one module to another. 351static Value *RemapOperand(const Value *In, 352 std::map<const Value*, Value*> &ValueMap, 353 LLVMContext &Context) { 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 Context)); 370 Result = 371 ConstantArray::get(cast<ArrayType>(CPA->getType()), Operands); 372 } else if (const ConstantStruct *CPS = dyn_cast<ConstantStruct>(CPV)) { 373 std::vector<Constant*> Operands(CPS->getNumOperands()); 374 for (unsigned i = 0, e = CPS->getNumOperands(); i != e; ++i) 375 Operands[i] =cast<Constant>(RemapOperand(CPS->getOperand(i), ValueMap, 376 Context)); 377 Result = 378 ConstantStruct::get(cast<StructType>(CPS->getType()), Operands); 379 } else if (isa<ConstantPointerNull>(CPV) || isa<UndefValue>(CPV)) { 380 Result = const_cast<Constant*>(CPV); 381 } else if (const ConstantVector *CP = dyn_cast<ConstantVector>(CPV)) { 382 std::vector<Constant*> Operands(CP->getNumOperands()); 383 for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i) 384 Operands[i] = cast<Constant>(RemapOperand(CP->getOperand(i), ValueMap, 385 Context)); 386 Result = ConstantVector::get(Operands); 387 } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CPV)) { 388 std::vector<Constant*> Ops; 389 for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) 390 Ops.push_back(cast<Constant>(RemapOperand(CE->getOperand(i),ValueMap, 391 Context))); 392 Result = CE->getWithOperands(Ops); 393 } else { 394 assert(!isa<GlobalValue>(CPV) && "Unmapped global?"); 395 llvm_unreachable("Unknown type of derived type constant value!"); 396 } 397 } else if (const MDNode *N = dyn_cast<MDNode>(In)) { 398 std::vector<Value*> Elems; 399 for (unsigned i = 0, e = N->getNumElements(); i !=e; ++i) 400 Elems.push_back(RemapOperand(N->getElement(i), ValueMap, Context)); 401 if (!Elems.empty()) 402 Result = MDNode::get(Context, &Elems[0], Elems.size()); 403 } else if (const MDString *MDS = dyn_cast<MDString>(In)) { 404 Result = MDString::get(Context, MDS->getString()); 405 } else if (isa<InlineAsm>(In)) { 406 Result = const_cast<Value*>(In); 407 } 408 409 // Cache the mapping in our local map structure 410 if (Result) { 411 ValueMap[In] = Result; 412 return Result; 413 } 414 415#ifndef NDEBUG 416 errs() << "LinkModules ValueMap: \n"; 417 PrintMap(ValueMap); 418 419 errs() << "Couldn't remap value: " << (void*)In << " " << *In << "\n"; 420 llvm_unreachable("Couldn't remap value!"); 421#endif 422 return 0; 423} 424 425/// ForceRenaming - The LLVM SymbolTable class autorenames globals that conflict 426/// in the symbol table. This is good for all clients except for us. Go 427/// through the trouble to force this back. 428static void ForceRenaming(GlobalValue *GV, const std::string &Name) { 429 assert(GV->getName() != Name && "Can't force rename to self"); 430 ValueSymbolTable &ST = GV->getParent()->getValueSymbolTable(); 431 432 // If there is a conflict, rename the conflict. 433 if (GlobalValue *ConflictGV = cast_or_null<GlobalValue>(ST.lookup(Name))) { 434 assert(ConflictGV->hasLocalLinkage() && 435 "Not conflicting with a static global, should link instead!"); 436 GV->takeName(ConflictGV); 437 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed 438 assert(ConflictGV->getName() != Name && "ForceRenaming didn't work"); 439 } else { 440 GV->setName(Name); // Force the name back 441 } 442} 443 444/// CopyGVAttributes - copy additional attributes (those not needed to construct 445/// a GlobalValue) from the SrcGV to the DestGV. 446static void CopyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) { 447 // Use the maximum alignment, rather than just copying the alignment of SrcGV. 448 unsigned Alignment = std::max(DestGV->getAlignment(), SrcGV->getAlignment()); 449 DestGV->copyAttributesFrom(SrcGV); 450 DestGV->setAlignment(Alignment); 451} 452 453/// GetLinkageResult - This analyzes the two global values and determines what 454/// the result will look like in the destination module. In particular, it 455/// computes the resultant linkage type, computes whether the global in the 456/// source should be copied over to the destination (replacing the existing 457/// one), and computes whether this linkage is an error or not. It also performs 458/// visibility checks: we cannot link together two symbols with different 459/// visibilities. 460static bool GetLinkageResult(GlobalValue *Dest, const GlobalValue *Src, 461 GlobalValue::LinkageTypes <, bool &LinkFromSrc, 462 std::string *Err) { 463 assert((!Dest || !Src->hasLocalLinkage()) && 464 "If Src has internal linkage, Dest shouldn't be set!"); 465 if (!Dest) { 466 // Linking something to nothing. 467 LinkFromSrc = true; 468 LT = Src->getLinkage(); 469 } else if (Src->isDeclaration()) { 470 // If Src is external or if both Src & Dest are external.. Just link the 471 // external globals, we aren't adding anything. 472 if (Src->hasDLLImportLinkage()) { 473 // If one of GVs has DLLImport linkage, result should be dllimport'ed. 474 if (Dest->isDeclaration()) { 475 LinkFromSrc = true; 476 LT = Src->getLinkage(); 477 } 478 } else if (Dest->hasExternalWeakLinkage()) { 479 // If the Dest is weak, use the source linkage. 480 LinkFromSrc = true; 481 LT = Src->getLinkage(); 482 } else { 483 LinkFromSrc = false; 484 LT = Dest->getLinkage(); 485 } 486 } else if (Dest->isDeclaration() && !Dest->hasDLLImportLinkage()) { 487 // If Dest is external but Src is not: 488 LinkFromSrc = true; 489 LT = Src->getLinkage(); 490 } else if (Src->hasAppendingLinkage() || Dest->hasAppendingLinkage()) { 491 if (Src->getLinkage() != Dest->getLinkage()) 492 return Error(Err, "Linking globals named '" + Src->getName() + 493 "': can only link appending global with another appending global!"); 494 LinkFromSrc = true; // Special cased. 495 LT = Src->getLinkage(); 496 } else if (Src->isWeakForLinker()) { 497 // At this point we know that Dest has LinkOnce, External*, Weak, Common, 498 // or DLL* linkage. 499 if (Dest->hasExternalWeakLinkage() || 500 Dest->hasAvailableExternallyLinkage() || 501 (Dest->hasLinkOnceLinkage() && 502 (Src->hasWeakLinkage() || Src->hasCommonLinkage()))) { 503 LinkFromSrc = true; 504 LT = Src->getLinkage(); 505 } else { 506 LinkFromSrc = false; 507 LT = Dest->getLinkage(); 508 } 509 } else if (Dest->isWeakForLinker()) { 510 // At this point we know that Src has External* or DLL* linkage. 511 if (Src->hasExternalWeakLinkage()) { 512 LinkFromSrc = false; 513 LT = Dest->getLinkage(); 514 } else { 515 LinkFromSrc = true; 516 LT = GlobalValue::ExternalLinkage; 517 } 518 } else { 519 assert((Dest->hasExternalLinkage() || 520 Dest->hasDLLImportLinkage() || 521 Dest->hasDLLExportLinkage() || 522 Dest->hasExternalWeakLinkage()) && 523 (Src->hasExternalLinkage() || 524 Src->hasDLLImportLinkage() || 525 Src->hasDLLExportLinkage() || 526 Src->hasExternalWeakLinkage()) && 527 "Unexpected linkage type!"); 528 return Error(Err, "Linking globals named '" + Src->getName() + 529 "': symbol multiply defined!"); 530 } 531 532 // Check visibility 533 if (Dest && Src->getVisibility() != Dest->getVisibility()) 534 if (!Src->isDeclaration() && !Dest->isDeclaration()) 535 return Error(Err, "Linking globals named '" + Src->getName() + 536 "': symbols have different visibilities!"); 537 return false; 538} 539 540// Insert all of the named mdnoes in Src into the Dest module. 541static void LinkNamedMDNodes(Module *Dest, Module *Src) { 542 for (Module::const_named_metadata_iterator I = Src->named_metadata_begin(), 543 E = Src->named_metadata_end(); I != E; ++I) { 544 const NamedMDNode *SrcNMD = I; 545 NamedMDNode *DestNMD = Dest->getNamedMetadata(SrcNMD->getName()); 546 if (!DestNMD) 547 NamedMDNode::Create(SrcNMD, Dest); 548 else { 549 // Add Src elements into Dest node. 550 for (unsigned i = 0, e = SrcNMD->getNumElements(); i != e; ++i) 551 DestNMD->addElement(SrcNMD->getElement(i)); 552 } 553 } 554} 555 556// LinkGlobals - Loop through the global variables in the src module and merge 557// them into the dest module. 558static bool LinkGlobals(Module *Dest, const Module *Src, 559 std::map<const Value*, Value*> &ValueMap, 560 std::multimap<std::string, GlobalVariable *> &AppendingVars, 561 std::string *Err) { 562 ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable(); 563 564 // Loop over all of the globals in the src module, mapping them over as we go 565 for (Module::const_global_iterator I = Src->global_begin(), 566 E = Src->global_end(); I != E; ++I) { 567 const GlobalVariable *SGV = I; 568 GlobalValue *DGV = 0; 569 570 // Check to see if may have to link the global with the global, alias or 571 // function. 572 if (SGV->hasName() && !SGV->hasLocalLinkage()) 573 DGV = cast_or_null<GlobalValue>(DestSymTab.lookup(SGV->getName())); 574 575 // If we found a global with the same name in the dest module, but it has 576 // internal linkage, we are really not doing any linkage here. 577 if (DGV && DGV->hasLocalLinkage()) 578 DGV = 0; 579 580 // If types don't agree due to opaque types, try to resolve them. 581 if (DGV && DGV->getType() != SGV->getType()) 582 RecursiveResolveTypes(SGV->getType(), DGV->getType()); 583 584 assert((SGV->hasInitializer() || SGV->hasExternalWeakLinkage() || 585 SGV->hasExternalLinkage() || SGV->hasDLLImportLinkage()) && 586 "Global must either be external or have an initializer!"); 587 588 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 589 bool LinkFromSrc = false; 590 if (GetLinkageResult(DGV, SGV, NewLinkage, LinkFromSrc, Err)) 591 return true; 592 593 if (DGV == 0) { 594 // No linking to be performed, simply create an identical version of the 595 // symbol over in the dest module... the initializer will be filled in 596 // later by LinkGlobalInits. 597 GlobalVariable *NewDGV = 598 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 599 SGV->isConstant(), SGV->getLinkage(), /*init*/0, 600 SGV->getName(), 0, false, 601 SGV->getType()->getAddressSpace()); 602 // Propagate alignment, visibility and section info. 603 CopyGVAttributes(NewDGV, SGV); 604 605 // If the LLVM runtime renamed the global, but it is an externally visible 606 // symbol, DGV must be an existing global with internal linkage. Rename 607 // it. 608 if (!NewDGV->hasLocalLinkage() && NewDGV->getName() != SGV->getName()) 609 ForceRenaming(NewDGV, SGV->getName()); 610 611 // Make sure to remember this mapping. 612 ValueMap[SGV] = NewDGV; 613 614 // Keep track that this is an appending variable. 615 if (SGV->hasAppendingLinkage()) 616 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV)); 617 continue; 618 } 619 620 // If the visibilities of the symbols disagree and the destination is a 621 // prototype, take the visibility of its input. 622 if (DGV->isDeclaration()) 623 DGV->setVisibility(SGV->getVisibility()); 624 625 if (DGV->hasAppendingLinkage()) { 626 // No linking is performed yet. Just insert a new copy of the global, and 627 // keep track of the fact that it is an appending variable in the 628 // AppendingVars map. The name is cleared out so that no linkage is 629 // performed. 630 GlobalVariable *NewDGV = 631 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 632 SGV->isConstant(), SGV->getLinkage(), /*init*/0, 633 "", 0, false, 634 SGV->getType()->getAddressSpace()); 635 636 // Set alignment allowing CopyGVAttributes merge it with alignment of SGV. 637 NewDGV->setAlignment(DGV->getAlignment()); 638 // Propagate alignment, section and visibility info. 639 CopyGVAttributes(NewDGV, SGV); 640 641 // Make sure to remember this mapping... 642 ValueMap[SGV] = NewDGV; 643 644 // Keep track that this is an appending variable... 645 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV)); 646 continue; 647 } 648 649 if (LinkFromSrc) { 650 if (isa<GlobalAlias>(DGV)) 651 return Error(Err, "Global-Alias Collision on '" + SGV->getName() + 652 "': symbol multiple defined"); 653 654 // If the types don't match, and if we are to link from the source, nuke 655 // DGV and create a new one of the appropriate type. Note that the thing 656 // we are replacing may be a function (if a prototype, weak, etc) or a 657 // global variable. 658 GlobalVariable *NewDGV = 659 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 660 SGV->isConstant(), NewLinkage, /*init*/0, 661 DGV->getName(), 0, false, 662 SGV->getType()->getAddressSpace()); 663 664 // Propagate alignment, section, and visibility info. 665 CopyGVAttributes(NewDGV, SGV); 666 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV, 667 DGV->getType())); 668 669 // DGV will conflict with NewDGV because they both had the same 670 // name. We must erase this now so ForceRenaming doesn't assert 671 // because DGV might not have internal linkage. 672 if (GlobalVariable *Var = dyn_cast<GlobalVariable>(DGV)) 673 Var->eraseFromParent(); 674 else 675 cast<Function>(DGV)->eraseFromParent(); 676 DGV = NewDGV; 677 678 // If the symbol table renamed the global, but it is an externally visible 679 // symbol, DGV must be an existing global with internal linkage. Rename. 680 if (NewDGV->getName() != SGV->getName() && !NewDGV->hasLocalLinkage()) 681 ForceRenaming(NewDGV, SGV->getName()); 682 683 // Inherit const as appropriate. 684 NewDGV->setConstant(SGV->isConstant()); 685 686 // Make sure to remember this mapping. 687 ValueMap[SGV] = NewDGV; 688 continue; 689 } 690 691 // Not "link from source", keep the one in the DestModule and remap the 692 // input onto it. 693 694 // Special case for const propagation. 695 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) 696 if (DGVar->isDeclaration() && SGV->isConstant() && !DGVar->isConstant()) 697 DGVar->setConstant(true); 698 699 // SGV is global, but DGV is alias. 700 if (isa<GlobalAlias>(DGV)) { 701 // The only valid mappings are: 702 // - SGV is external declaration, which is effectively a no-op. 703 // - SGV is weak, when we just need to throw SGV out. 704 if (!SGV->isDeclaration() && !SGV->isWeakForLinker()) 705 return Error(Err, "Global-Alias Collision on '" + SGV->getName() + 706 "': symbol multiple defined"); 707 } 708 709 // Set calculated linkage 710 DGV->setLinkage(NewLinkage); 711 712 // Make sure to remember this mapping... 713 ValueMap[SGV] = ConstantExpr::getBitCast(DGV, SGV->getType()); 714 } 715 return false; 716} 717 718static GlobalValue::LinkageTypes 719CalculateAliasLinkage(const GlobalValue *SGV, const GlobalValue *DGV) { 720 GlobalValue::LinkageTypes SL = SGV->getLinkage(); 721 GlobalValue::LinkageTypes DL = DGV->getLinkage(); 722 if (SL == GlobalValue::ExternalLinkage || DL == GlobalValue::ExternalLinkage) 723 return GlobalValue::ExternalLinkage; 724 else if (SL == GlobalValue::WeakAnyLinkage || 725 DL == GlobalValue::WeakAnyLinkage) 726 return GlobalValue::WeakAnyLinkage; 727 else if (SL == GlobalValue::WeakODRLinkage || 728 DL == GlobalValue::WeakODRLinkage) 729 return GlobalValue::WeakODRLinkage; 730 else if (SL == GlobalValue::InternalLinkage && 731 DL == GlobalValue::InternalLinkage) 732 return GlobalValue::InternalLinkage; 733 else if (SL == GlobalValue::LinkerPrivateLinkage && 734 DL == GlobalValue::LinkerPrivateLinkage) 735 return GlobalValue::LinkerPrivateLinkage; 736 else { 737 assert (SL == GlobalValue::PrivateLinkage && 738 DL == GlobalValue::PrivateLinkage && "Unexpected linkage type"); 739 return GlobalValue::PrivateLinkage; 740 } 741} 742 743// LinkAlias - Loop through the alias in the src module and link them into the 744// dest module. We're assuming, that all functions/global variables were already 745// linked in. 746static bool LinkAlias(Module *Dest, const Module *Src, 747 std::map<const Value*, Value*> &ValueMap, 748 std::string *Err) { 749 // Loop over all alias in the src module 750 for (Module::const_alias_iterator I = Src->alias_begin(), 751 E = Src->alias_end(); I != E; ++I) { 752 const GlobalAlias *SGA = I; 753 const GlobalValue *SAliasee = SGA->getAliasedGlobal(); 754 GlobalAlias *NewGA = NULL; 755 756 // Globals were already linked, thus we can just query ValueMap for variant 757 // of SAliasee in Dest. 758 std::map<const Value*,Value*>::const_iterator VMI = ValueMap.find(SAliasee); 759 assert(VMI != ValueMap.end() && "Aliasee not linked"); 760 GlobalValue* DAliasee = cast<GlobalValue>(VMI->second); 761 GlobalValue* DGV = NULL; 762 763 // Try to find something 'similar' to SGA in destination module. 764 if (!DGV && !SGA->hasLocalLinkage()) { 765 DGV = Dest->getNamedAlias(SGA->getName()); 766 767 // If types don't agree due to opaque types, try to resolve them. 768 if (DGV && DGV->getType() != SGA->getType()) 769 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 770 } 771 772 if (!DGV && !SGA->hasLocalLinkage()) { 773 DGV = Dest->getGlobalVariable(SGA->getName()); 774 775 // If types don't agree due to opaque types, try to resolve them. 776 if (DGV && DGV->getType() != SGA->getType()) 777 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 778 } 779 780 if (!DGV && !SGA->hasLocalLinkage()) { 781 DGV = Dest->getFunction(SGA->getName()); 782 783 // If types don't agree due to opaque types, try to resolve them. 784 if (DGV && DGV->getType() != SGA->getType()) 785 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 786 } 787 788 // No linking to be performed on internal stuff. 789 if (DGV && DGV->hasLocalLinkage()) 790 DGV = NULL; 791 792 if (GlobalAlias *DGA = dyn_cast_or_null<GlobalAlias>(DGV)) { 793 // Types are known to be the same, check whether aliasees equal. As 794 // globals are already linked we just need query ValueMap to find the 795 // mapping. 796 if (DAliasee == DGA->getAliasedGlobal()) { 797 // This is just two copies of the same alias. Propagate linkage, if 798 // necessary. 799 DGA->setLinkage(CalculateAliasLinkage(SGA, DGA)); 800 801 NewGA = DGA; 802 // Proceed to 'common' steps 803 } else 804 return Error(Err, "Alias Collision on '" + SGA->getName()+ 805 "': aliases have different aliasees"); 806 } else if (GlobalVariable *DGVar = dyn_cast_or_null<GlobalVariable>(DGV)) { 807 // The only allowed way is to link alias with external declaration or weak 808 // symbol.. 809 if (DGVar->isDeclaration() || DGVar->isWeakForLinker()) { 810 // But only if aliasee is global too... 811 if (!isa<GlobalVariable>(DAliasee)) 812 return Error(Err, "Global-Alias Collision on '" + SGA->getName() + 813 "': aliasee is not global variable"); 814 815 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 816 SGA->getName(), DAliasee, Dest); 817 CopyGVAttributes(NewGA, SGA); 818 819 // Any uses of DGV need to change to NewGA, with cast, if needed. 820 if (SGA->getType() != DGVar->getType()) 821 DGVar->replaceAllUsesWith(ConstantExpr::getBitCast(NewGA, 822 DGVar->getType())); 823 else 824 DGVar->replaceAllUsesWith(NewGA); 825 826 // DGVar will conflict with NewGA because they both had the same 827 // name. We must erase this now so ForceRenaming doesn't assert 828 // because DGV might not have internal linkage. 829 DGVar->eraseFromParent(); 830 831 // Proceed to 'common' steps 832 } else 833 return Error(Err, "Global-Alias Collision on '" + SGA->getName() + 834 "': symbol multiple defined"); 835 } else if (Function *DF = dyn_cast_or_null<Function>(DGV)) { 836 // The only allowed way is to link alias with external declaration or weak 837 // symbol... 838 if (DF->isDeclaration() || DF->isWeakForLinker()) { 839 // But only if aliasee is function too... 840 if (!isa<Function>(DAliasee)) 841 return Error(Err, "Function-Alias Collision on '" + SGA->getName() + 842 "': aliasee is not function"); 843 844 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 845 SGA->getName(), DAliasee, Dest); 846 CopyGVAttributes(NewGA, SGA); 847 848 // Any uses of DF need to change to NewGA, with cast, if needed. 849 if (SGA->getType() != DF->getType()) 850 DF->replaceAllUsesWith(ConstantExpr::getBitCast(NewGA, 851 DF->getType())); 852 else 853 DF->replaceAllUsesWith(NewGA); 854 855 // DF will conflict with NewGA because they both had the same 856 // name. We must erase this now so ForceRenaming doesn't assert 857 // because DF might not have internal linkage. 858 DF->eraseFromParent(); 859 860 // Proceed to 'common' steps 861 } else 862 return Error(Err, "Function-Alias Collision on '" + SGA->getName() + 863 "': symbol multiple defined"); 864 } else { 865 // No linking to be performed, simply create an identical version of the 866 // alias over in the dest module... 867 868 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 869 SGA->getName(), DAliasee, Dest); 870 CopyGVAttributes(NewGA, SGA); 871 872 // Proceed to 'common' steps 873 } 874 875 assert(NewGA && "No alias was created in destination module!"); 876 877 // If the symbol table renamed the alias, but it is an externally visible 878 // symbol, DGA must be an global value with internal linkage. Rename it. 879 if (NewGA->getName() != SGA->getName() && 880 !NewGA->hasLocalLinkage()) 881 ForceRenaming(NewGA, SGA->getName()); 882 883 // Remember this mapping so uses in the source module get remapped 884 // later by RemapOperand. 885 ValueMap[SGA] = NewGA; 886 } 887 888 return false; 889} 890 891 892// LinkGlobalInits - Update the initializers in the Dest module now that all 893// globals that may be referenced are in Dest. 894static bool LinkGlobalInits(Module *Dest, const Module *Src, 895 std::map<const Value*, Value*> &ValueMap, 896 std::string *Err) { 897 // Loop over all of the globals in the src module, mapping them over as we go 898 for (Module::const_global_iterator I = Src->global_begin(), 899 E = Src->global_end(); I != E; ++I) { 900 const GlobalVariable *SGV = I; 901 902 if (SGV->hasInitializer()) { // Only process initialized GV's 903 // Figure out what the initializer looks like in the dest module... 904 Constant *SInit = 905 cast<Constant>(RemapOperand(SGV->getInitializer(), ValueMap, 906 Dest->getContext())); 907 // Grab destination global variable or alias. 908 GlobalValue *DGV = cast<GlobalValue>(ValueMap[SGV]->stripPointerCasts()); 909 910 // If dest if global variable, check that initializers match. 911 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) { 912 if (DGVar->hasInitializer()) { 913 if (SGV->hasExternalLinkage()) { 914 if (DGVar->getInitializer() != SInit) 915 return Error(Err, "Global Variable Collision on '" + 916 SGV->getName() + 917 "': global variables have different initializers"); 918 } else if (DGVar->isWeakForLinker()) { 919 // Nothing is required, mapped values will take the new global 920 // automatically. 921 } else if (SGV->isWeakForLinker()) { 922 // Nothing is required, mapped values will take the new global 923 // automatically. 924 } else if (DGVar->hasAppendingLinkage()) { 925 llvm_unreachable("Appending linkage unimplemented!"); 926 } else { 927 llvm_unreachable("Unknown linkage!"); 928 } 929 } else { 930 // Copy the initializer over now... 931 DGVar->setInitializer(SInit); 932 } 933 } else { 934 // Destination is alias, the only valid situation is when source is 935 // weak. Also, note, that we already checked linkage in LinkGlobals(), 936 // thus we assert here. 937 // FIXME: Should we weaken this assumption, 'dereference' alias and 938 // check for initializer of aliasee? 939 assert(SGV->isWeakForLinker()); 940 } 941 } 942 } 943 return false; 944} 945 946// LinkFunctionProtos - Link the functions together between the two modules, 947// without doing function bodies... this just adds external function prototypes 948// to the Dest function... 949// 950static bool LinkFunctionProtos(Module *Dest, const Module *Src, 951 std::map<const Value*, Value*> &ValueMap, 952 std::string *Err) { 953 ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable(); 954 955 // Loop over all of the functions in the src module, mapping them over 956 for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) { 957 const Function *SF = I; // SrcFunction 958 GlobalValue *DGV = 0; 959 960 // Check to see if may have to link the function with the global, alias or 961 // function. 962 if (SF->hasName() && !SF->hasLocalLinkage()) 963 DGV = cast_or_null<GlobalValue>(DestSymTab.lookup(SF->getName())); 964 965 // If we found a global with the same name in the dest module, but it has 966 // internal linkage, we are really not doing any linkage here. 967 if (DGV && DGV->hasLocalLinkage()) 968 DGV = 0; 969 970 // If types don't agree due to opaque types, try to resolve them. 971 if (DGV && DGV->getType() != SF->getType()) 972 RecursiveResolveTypes(SF->getType(), DGV->getType()); 973 974 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 975 bool LinkFromSrc = false; 976 if (GetLinkageResult(DGV, SF, NewLinkage, LinkFromSrc, Err)) 977 return true; 978 979 // If there is no linkage to be performed, just bring over SF without 980 // modifying it. 981 if (DGV == 0) { 982 // Function does not already exist, simply insert an function signature 983 // identical to SF into the dest module. 984 Function *NewDF = Function::Create(SF->getFunctionType(), 985 SF->getLinkage(), 986 SF->getName(), Dest); 987 CopyGVAttributes(NewDF, SF); 988 989 // If the LLVM runtime renamed the function, but it is an externally 990 // visible symbol, DF must be an existing function with internal linkage. 991 // Rename it. 992 if (!NewDF->hasLocalLinkage() && NewDF->getName() != SF->getName()) 993 ForceRenaming(NewDF, SF->getName()); 994 995 // ... and remember this mapping... 996 ValueMap[SF] = NewDF; 997 continue; 998 } 999 1000 // If the visibilities of the symbols disagree and the destination is a 1001 // prototype, take the visibility of its input. 1002 if (DGV->isDeclaration()) 1003 DGV->setVisibility(SF->getVisibility()); 1004 1005 if (LinkFromSrc) { 1006 if (isa<GlobalAlias>(DGV)) 1007 return Error(Err, "Function-Alias Collision on '" + SF->getName() + 1008 "': symbol multiple defined"); 1009 1010 // We have a definition of the same name but different type in the 1011 // source module. Copy the prototype to the destination and replace 1012 // uses of the destination's prototype with the new prototype. 1013 Function *NewDF = Function::Create(SF->getFunctionType(), NewLinkage, 1014 SF->getName(), Dest); 1015 CopyGVAttributes(NewDF, SF); 1016 1017 // Any uses of DF need to change to NewDF, with cast 1018 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, 1019 DGV->getType())); 1020 1021 // DF will conflict with NewDF because they both had the same. We must 1022 // erase this now so ForceRenaming doesn't assert because DF might 1023 // not have internal linkage. 1024 if (GlobalVariable *Var = dyn_cast<GlobalVariable>(DGV)) 1025 Var->eraseFromParent(); 1026 else 1027 cast<Function>(DGV)->eraseFromParent(); 1028 1029 // If the symbol table renamed the function, but it is an externally 1030 // visible symbol, DF must be an existing function with internal 1031 // linkage. Rename it. 1032 if (NewDF->getName() != SF->getName() && !NewDF->hasLocalLinkage()) 1033 ForceRenaming(NewDF, SF->getName()); 1034 1035 // Remember this mapping so uses in the source module get remapped 1036 // later by RemapOperand. 1037 ValueMap[SF] = NewDF; 1038 continue; 1039 } 1040 1041 // Not "link from source", keep the one in the DestModule and remap the 1042 // input onto it. 1043 1044 if (isa<GlobalAlias>(DGV)) { 1045 // The only valid mappings are: 1046 // - SF is external declaration, which is effectively a no-op. 1047 // - SF is weak, when we just need to throw SF out. 1048 if (!SF->isDeclaration() && !SF->isWeakForLinker()) 1049 return Error(Err, "Function-Alias Collision on '" + SF->getName() + 1050 "': symbol multiple defined"); 1051 } 1052 1053 // Set calculated linkage 1054 DGV->setLinkage(NewLinkage); 1055 1056 // Make sure to remember this mapping. 1057 ValueMap[SF] = ConstantExpr::getBitCast(DGV, SF->getType()); 1058 } 1059 return false; 1060} 1061 1062// LinkFunctionBody - Copy the source function over into the dest function and 1063// fix up references to values. At this point we know that Dest is an external 1064// function, and that Src is not. 1065static bool LinkFunctionBody(Function *Dest, Function *Src, 1066 std::map<const Value*, Value*> &ValueMap, 1067 std::string *Err) { 1068 assert(Src && Dest && Dest->isDeclaration() && !Src->isDeclaration()); 1069 1070 // Go through and convert function arguments over, remembering the mapping. 1071 Function::arg_iterator DI = Dest->arg_begin(); 1072 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 1073 I != E; ++I, ++DI) { 1074 DI->setName(I->getName()); // Copy the name information over... 1075 1076 // Add a mapping to our local map 1077 ValueMap[I] = DI; 1078 } 1079 1080 // Splice the body of the source function into the dest function. 1081 Dest->getBasicBlockList().splice(Dest->end(), Src->getBasicBlockList()); 1082 1083 // At this point, all of the instructions and values of the function are now 1084 // copied over. The only problem is that they are still referencing values in 1085 // the Source function as operands. Loop through all of the operands of the 1086 // functions and patch them up to point to the local versions... 1087 // 1088 for (Function::iterator BB = Dest->begin(), BE = Dest->end(); BB != BE; ++BB) 1089 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) 1090 for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end(); 1091 OI != OE; ++OI) 1092 if (!isa<Instruction>(*OI) && !isa<BasicBlock>(*OI)) 1093 *OI = RemapOperand(*OI, ValueMap, Dest->getContext()); 1094 1095 // There is no need to map the arguments anymore. 1096 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 1097 I != E; ++I) 1098 ValueMap.erase(I); 1099 1100 return false; 1101} 1102 1103 1104// LinkFunctionBodies - Link in the function bodies that are defined in the 1105// source module into the DestModule. This consists basically of copying the 1106// function over and fixing up references to values. 1107static bool LinkFunctionBodies(Module *Dest, Module *Src, 1108 std::map<const Value*, Value*> &ValueMap, 1109 std::string *Err) { 1110 1111 // Loop over all of the functions in the src module, mapping them over as we 1112 // go 1113 for (Module::iterator SF = Src->begin(), E = Src->end(); SF != E; ++SF) { 1114 if (!SF->isDeclaration()) { // No body if function is external 1115 Function *DF = dyn_cast<Function>(ValueMap[SF]); // Destination function 1116 1117 // DF not external SF external? 1118 if (DF && DF->isDeclaration()) 1119 // Only provide the function body if there isn't one already. 1120 if (LinkFunctionBody(DF, SF, ValueMap, Err)) 1121 return true; 1122 } 1123 } 1124 return false; 1125} 1126 1127// LinkAppendingVars - If there were any appending global variables, link them 1128// together now. Return true on error. 1129static bool LinkAppendingVars(Module *M, 1130 std::multimap<std::string, GlobalVariable *> &AppendingVars, 1131 std::string *ErrorMsg) { 1132 if (AppendingVars.empty()) return false; // Nothing to do. 1133 1134 // Loop over the multimap of appending vars, processing any variables with the 1135 // same name, forming a new appending global variable with both of the 1136 // initializers merged together, then rewrite references to the old variables 1137 // and delete them. 1138 std::vector<Constant*> Inits; 1139 while (AppendingVars.size() > 1) { 1140 // Get the first two elements in the map... 1141 std::multimap<std::string, 1142 GlobalVariable*>::iterator Second = AppendingVars.begin(), First=Second++; 1143 1144 // If the first two elements are for different names, there is no pair... 1145 // Otherwise there is a pair, so link them together... 1146 if (First->first == Second->first) { 1147 GlobalVariable *G1 = First->second, *G2 = Second->second; 1148 const ArrayType *T1 = cast<ArrayType>(G1->getType()->getElementType()); 1149 const ArrayType *T2 = cast<ArrayType>(G2->getType()->getElementType()); 1150 1151 // Check to see that they two arrays agree on type... 1152 if (T1->getElementType() != T2->getElementType()) 1153 return Error(ErrorMsg, 1154 "Appending variables with different element types need to be linked!"); 1155 if (G1->isConstant() != G2->isConstant()) 1156 return Error(ErrorMsg, 1157 "Appending variables linked with different const'ness!"); 1158 1159 if (G1->getAlignment() != G2->getAlignment()) 1160 return Error(ErrorMsg, 1161 "Appending variables with different alignment need to be linked!"); 1162 1163 if (G1->getVisibility() != G2->getVisibility()) 1164 return Error(ErrorMsg, 1165 "Appending variables with different visibility need to be linked!"); 1166 1167 if (G1->getSection() != G2->getSection()) 1168 return Error(ErrorMsg, 1169 "Appending variables with different section name need to be linked!"); 1170 1171 unsigned NewSize = T1->getNumElements() + T2->getNumElements(); 1172 ArrayType *NewType = ArrayType::get(T1->getElementType(), 1173 NewSize); 1174 1175 G1->setName(""); // Clear G1's name in case of a conflict! 1176 1177 // Create the new global variable... 1178 GlobalVariable *NG = 1179 new GlobalVariable(*M, NewType, G1->isConstant(), G1->getLinkage(), 1180 /*init*/0, First->first, 0, G1->isThreadLocal(), 1181 G1->getType()->getAddressSpace()); 1182 1183 // Propagate alignment, visibility and section info. 1184 CopyGVAttributes(NG, G1); 1185 1186 // Merge the initializer... 1187 Inits.reserve(NewSize); 1188 if (ConstantArray *I = dyn_cast<ConstantArray>(G1->getInitializer())) { 1189 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i) 1190 Inits.push_back(I->getOperand(i)); 1191 } else { 1192 assert(isa<ConstantAggregateZero>(G1->getInitializer())); 1193 Constant *CV = Constant::getNullValue(T1->getElementType()); 1194 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i) 1195 Inits.push_back(CV); 1196 } 1197 if (ConstantArray *I = dyn_cast<ConstantArray>(G2->getInitializer())) { 1198 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i) 1199 Inits.push_back(I->getOperand(i)); 1200 } else { 1201 assert(isa<ConstantAggregateZero>(G2->getInitializer())); 1202 Constant *CV = Constant::getNullValue(T2->getElementType()); 1203 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i) 1204 Inits.push_back(CV); 1205 } 1206 NG->setInitializer(ConstantArray::get(NewType, Inits)); 1207 Inits.clear(); 1208 1209 // Replace any uses of the two global variables with uses of the new 1210 // global... 1211 1212 // FIXME: This should rewrite simple/straight-forward uses such as 1213 // getelementptr instructions to not use the Cast! 1214 G1->replaceAllUsesWith(ConstantExpr::getBitCast(NG, 1215 G1->getType())); 1216 G2->replaceAllUsesWith(ConstantExpr::getBitCast(NG, 1217 G2->getType())); 1218 1219 // Remove the two globals from the module now... 1220 M->getGlobalList().erase(G1); 1221 M->getGlobalList().erase(G2); 1222 1223 // Put the new global into the AppendingVars map so that we can handle 1224 // linking of more than two vars... 1225 Second->second = NG; 1226 } 1227 AppendingVars.erase(First); 1228 } 1229 1230 return false; 1231} 1232 1233static bool ResolveAliases(Module *Dest) { 1234 for (Module::alias_iterator I = Dest->alias_begin(), E = Dest->alias_end(); 1235 I != E; ++I) 1236 if (const GlobalValue *GV = I->resolveAliasedGlobal()) 1237 if (GV != I && !GV->isDeclaration()) 1238 I->replaceAllUsesWith(const_cast<GlobalValue*>(GV)); 1239 1240 return false; 1241} 1242 1243// LinkModules - This function links two modules together, with the resulting 1244// left module modified to be the composite of the two input modules. If an 1245// error occurs, true is returned and ErrorMsg (if not null) is set to indicate 1246// the problem. Upon failure, the Dest module could be in a modified state, and 1247// shouldn't be relied on to be consistent. 1248bool 1249Linker::LinkModules(Module *Dest, Module *Src, std::string *ErrorMsg) { 1250 assert(Dest != 0 && "Invalid Destination module"); 1251 assert(Src != 0 && "Invalid Source Module"); 1252 1253 if (Dest->getDataLayout().empty()) { 1254 if (!Src->getDataLayout().empty()) { 1255 Dest->setDataLayout(Src->getDataLayout()); 1256 } else { 1257 std::string DataLayout; 1258 1259 if (Dest->getEndianness() == Module::AnyEndianness) { 1260 if (Src->getEndianness() == Module::BigEndian) 1261 DataLayout.append("E"); 1262 else if (Src->getEndianness() == Module::LittleEndian) 1263 DataLayout.append("e"); 1264 } 1265 1266 if (Dest->getPointerSize() == Module::AnyPointerSize) { 1267 if (Src->getPointerSize() == Module::Pointer64) 1268 DataLayout.append(DataLayout.length() == 0 ? "p:64:64" : "-p:64:64"); 1269 else if (Src->getPointerSize() == Module::Pointer32) 1270 DataLayout.append(DataLayout.length() == 0 ? "p:32:32" : "-p:32:32"); 1271 } 1272 Dest->setDataLayout(DataLayout); 1273 } 1274 } 1275 1276 // Copy the target triple from the source to dest if the dest's is empty. 1277 if (Dest->getTargetTriple().empty() && !Src->getTargetTriple().empty()) 1278 Dest->setTargetTriple(Src->getTargetTriple()); 1279 1280 if (!Src->getDataLayout().empty() && !Dest->getDataLayout().empty() && 1281 Src->getDataLayout() != Dest->getDataLayout()) 1282 errs() << "WARNING: Linking two modules of different data layouts!\n"; 1283 if (!Src->getTargetTriple().empty() && 1284 Dest->getTargetTriple() != Src->getTargetTriple()) 1285 errs() << "WARNING: Linking two modules of different target triples!\n"; 1286 1287 // Append the module inline asm string. 1288 if (!Src->getModuleInlineAsm().empty()) { 1289 if (Dest->getModuleInlineAsm().empty()) 1290 Dest->setModuleInlineAsm(Src->getModuleInlineAsm()); 1291 else 1292 Dest->setModuleInlineAsm(Dest->getModuleInlineAsm()+"\n"+ 1293 Src->getModuleInlineAsm()); 1294 } 1295 1296 // Update the destination module's dependent libraries list with the libraries 1297 // from the source module. There's no opportunity for duplicates here as the 1298 // Module ensures that duplicate insertions are discarded. 1299 for (Module::lib_iterator SI = Src->lib_begin(), SE = Src->lib_end(); 1300 SI != SE; ++SI) 1301 Dest->addLibrary(*SI); 1302 1303 // LinkTypes - Go through the symbol table of the Src module and see if any 1304 // types are named in the src module that are not named in the Dst module. 1305 // Make sure there are no type name conflicts. 1306 if (LinkTypes(Dest, Src, ErrorMsg)) 1307 return true; 1308 1309 // ValueMap - Mapping of values from what they used to be in Src, to what they 1310 // are now in Dest. 1311 std::map<const Value*, Value*> ValueMap; 1312 1313 // AppendingVars - Keep track of global variables in the destination module 1314 // with appending linkage. After the module is linked together, they are 1315 // appended and the module is rewritten. 1316 std::multimap<std::string, GlobalVariable *> AppendingVars; 1317 for (Module::global_iterator I = Dest->global_begin(), E = Dest->global_end(); 1318 I != E; ++I) { 1319 // Add all of the appending globals already in the Dest module to 1320 // AppendingVars. 1321 if (I->hasAppendingLinkage()) 1322 AppendingVars.insert(std::make_pair(I->getName(), I)); 1323 } 1324 1325 // Insert all of the named mdnoes in Src into the Dest module. 1326 LinkNamedMDNodes(Dest, Src); 1327 1328 // Insert all of the globals in src into the Dest module... without linking 1329 // initializers (which could refer to functions not yet mapped over). 1330 if (LinkGlobals(Dest, Src, ValueMap, AppendingVars, ErrorMsg)) 1331 return true; 1332 1333 // Link the functions together between the two modules, without doing function 1334 // bodies... this just adds external function prototypes to the Dest 1335 // function... We do this so that when we begin processing function bodies, 1336 // all of the global values that may be referenced are available in our 1337 // ValueMap. 1338 if (LinkFunctionProtos(Dest, Src, ValueMap, ErrorMsg)) 1339 return true; 1340 1341 // If there were any alias, link them now. We really need to do this now, 1342 // because all of the aliases that may be referenced need to be available in 1343 // ValueMap 1344 if (LinkAlias(Dest, Src, ValueMap, ErrorMsg)) return true; 1345 1346 // Update the initializers in the Dest module now that all globals that may 1347 // be referenced are in Dest. 1348 if (LinkGlobalInits(Dest, Src, ValueMap, ErrorMsg)) return true; 1349 1350 // Link in the function bodies that are defined in the source module into the 1351 // DestModule. This consists basically of copying the function over and 1352 // fixing up references to values. 1353 if (LinkFunctionBodies(Dest, Src, ValueMap, ErrorMsg)) return true; 1354 1355 // If there were any appending global variables, link them together now. 1356 if (LinkAppendingVars(Dest, AppendingVars, ErrorMsg)) return true; 1357 1358 // Resolve all uses of aliases with aliasees 1359 if (ResolveAliases(Dest)) return true; 1360 1361 // If the source library's module id is in the dependent library list of the 1362 // destination library, remove it since that module is now linked in. 1363 sys::Path modId; 1364 modId.set(Src->getModuleIdentifier()); 1365 if (!modId.isEmpty()) 1366 Dest->removeLibrary(modId.getBasename()); 1367 1368 return false; 1369} 1370 1371// vim: sw=2 1372