LinkModules.cpp revision 47c5188789bc40671504ed1fa3a44765cefba44f
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 (DstTy->isOpaqueTy() || SrcTy->isOpaqueTy()) 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 (const MDNode *MD = dyn_cast<MDNode>(In)) { 396 if (MD->isFunctionLocal()) { 397 SmallVector<Value*, 4> Elts; 398 for (unsigned i = 0, e = MD->getNumOperands(); i != e; ++i) { 399 if (MD->getOperand(i)) 400 Elts.push_back(RemapOperand(MD->getOperand(i), ValueMap)); 401 else 402 Elts.push_back(NULL); 403 } 404 Result = MDNode::get(In->getContext(), Elts.data(), MD->getNumOperands()); 405 } else { 406 Result = const_cast<Value*>(In); 407 } 408 } else if (isa<MDString>(In) || isa<InlineAsm>(In) || isa<Instruction>(In)) { 409 Result = const_cast<Value*>(In); 410 } 411 412 // Cache the mapping in our local map structure 413 if (Result) { 414 ValueMap[In] = Result; 415 return Result; 416 } 417 418#ifndef NDEBUG 419 dbgs() << "LinkModules ValueMap: \n"; 420 PrintMap(ValueMap); 421 422 dbgs() << "Couldn't remap value: " << (void*)In << " " << *In << "\n"; 423 llvm_unreachable("Couldn't remap value!"); 424#endif 425 return 0; 426} 427 428/// ForceRenaming - The LLVM SymbolTable class autorenames globals that conflict 429/// in the symbol table. This is good for all clients except for us. Go 430/// through the trouble to force this back. 431static void ForceRenaming(GlobalValue *GV, const std::string &Name) { 432 assert(GV->getName() != Name && "Can't force rename to self"); 433 ValueSymbolTable &ST = GV->getParent()->getValueSymbolTable(); 434 435 // If there is a conflict, rename the conflict. 436 if (GlobalValue *ConflictGV = cast_or_null<GlobalValue>(ST.lookup(Name))) { 437 assert(ConflictGV->hasLocalLinkage() && 438 "Not conflicting with a static global, should link instead!"); 439 GV->takeName(ConflictGV); 440 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed 441 assert(ConflictGV->getName() != Name && "ForceRenaming didn't work"); 442 } else { 443 GV->setName(Name); // Force the name back 444 } 445} 446 447/// CopyGVAttributes - copy additional attributes (those not needed to construct 448/// a GlobalValue) from the SrcGV to the DestGV. 449static void CopyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) { 450 // Use the maximum alignment, rather than just copying the alignment of SrcGV. 451 unsigned Alignment = std::max(DestGV->getAlignment(), SrcGV->getAlignment()); 452 DestGV->copyAttributesFrom(SrcGV); 453 DestGV->setAlignment(Alignment); 454} 455 456/// GetLinkageResult - This analyzes the two global values and determines what 457/// the result will look like in the destination module. In particular, it 458/// computes the resultant linkage type, computes whether the global in the 459/// source should be copied over to the destination (replacing the existing 460/// one), and computes whether this linkage is an error or not. It also performs 461/// visibility checks: we cannot link together two symbols with different 462/// visibilities. 463static bool GetLinkageResult(GlobalValue *Dest, const GlobalValue *Src, 464 GlobalValue::LinkageTypes <, bool &LinkFromSrc, 465 std::string *Err) { 466 assert((!Dest || !Src->hasLocalLinkage()) && 467 "If Src has internal linkage, Dest shouldn't be set!"); 468 if (!Dest) { 469 // Linking something to nothing. 470 LinkFromSrc = true; 471 LT = Src->getLinkage(); 472 } else if (Src->isDeclaration()) { 473 // If Src is external or if both Src & Dest are external.. Just link the 474 // external globals, we aren't adding anything. 475 if (Src->hasDLLImportLinkage()) { 476 // If one of GVs has DLLImport linkage, result should be dllimport'ed. 477 if (Dest->isDeclaration()) { 478 LinkFromSrc = true; 479 LT = Src->getLinkage(); 480 } 481 } else if (Dest->hasExternalWeakLinkage()) { 482 // If the Dest is weak, use the source linkage. 483 LinkFromSrc = true; 484 LT = Src->getLinkage(); 485 } else { 486 LinkFromSrc = false; 487 LT = Dest->getLinkage(); 488 } 489 } else if (Dest->isDeclaration() && !Dest->hasDLLImportLinkage()) { 490 // If Dest is external but Src is not: 491 LinkFromSrc = true; 492 LT = Src->getLinkage(); 493 } else if (Src->hasAppendingLinkage() || Dest->hasAppendingLinkage()) { 494 if (Src->getLinkage() != Dest->getLinkage()) 495 return Error(Err, "Linking globals named '" + Src->getName() + 496 "': can only link appending global with another appending global!"); 497 LinkFromSrc = true; // Special cased. 498 LT = Src->getLinkage(); 499 } else if (Src->isWeakForLinker()) { 500 // At this point we know that Dest has LinkOnce, External*, Weak, Common, 501 // or DLL* linkage. 502 if (Dest->hasExternalWeakLinkage() || 503 Dest->hasAvailableExternallyLinkage() || 504 (Dest->hasLinkOnceLinkage() && 505 (Src->hasWeakLinkage() || Src->hasCommonLinkage()))) { 506 LinkFromSrc = true; 507 LT = Src->getLinkage(); 508 } else { 509 LinkFromSrc = false; 510 LT = Dest->getLinkage(); 511 } 512 } else if (Dest->isWeakForLinker()) { 513 // At this point we know that Src has External* or DLL* linkage. 514 if (Src->hasExternalWeakLinkage()) { 515 LinkFromSrc = false; 516 LT = Dest->getLinkage(); 517 } else { 518 LinkFromSrc = true; 519 LT = GlobalValue::ExternalLinkage; 520 } 521 } else { 522 assert((Dest->hasExternalLinkage() || 523 Dest->hasDLLImportLinkage() || 524 Dest->hasDLLExportLinkage() || 525 Dest->hasExternalWeakLinkage()) && 526 (Src->hasExternalLinkage() || 527 Src->hasDLLImportLinkage() || 528 Src->hasDLLExportLinkage() || 529 Src->hasExternalWeakLinkage()) && 530 "Unexpected linkage type!"); 531 return Error(Err, "Linking globals named '" + Src->getName() + 532 "': symbol multiply defined!"); 533 } 534 535 // Check visibility 536 if (Dest && Src->getVisibility() != Dest->getVisibility()) 537 if (!Src->isDeclaration() && !Dest->isDeclaration()) 538 return Error(Err, "Linking globals named '" + Src->getName() + 539 "': symbols have different visibilities!"); 540 return false; 541} 542 543// Insert all of the named mdnoes in Src into the Dest module. 544static void LinkNamedMDNodes(Module *Dest, Module *Src) { 545 for (Module::const_named_metadata_iterator I = Src->named_metadata_begin(), 546 E = Src->named_metadata_end(); I != E; ++I) { 547 const NamedMDNode *SrcNMD = I; 548 NamedMDNode *DestNMD = Dest->getNamedMetadata(SrcNMD->getName()); 549 if (!DestNMD) 550 NamedMDNode::Create(SrcNMD, Dest); 551 else { 552 // Add Src elements into Dest node. 553 for (unsigned i = 0, e = SrcNMD->getNumOperands(); i != e; ++i) 554 DestNMD->addOperand(SrcNMD->getOperand(i)); 555 } 556 } 557} 558 559// LinkGlobals - Loop through the global variables in the src module and merge 560// them into the dest module. 561static bool LinkGlobals(Module *Dest, const Module *Src, 562 std::map<const Value*, Value*> &ValueMap, 563 std::multimap<std::string, GlobalVariable *> &AppendingVars, 564 std::string *Err) { 565 ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable(); 566 567 // Loop over all of the globals in the src module, mapping them over as we go 568 for (Module::const_global_iterator I = Src->global_begin(), 569 E = Src->global_end(); I != E; ++I) { 570 const GlobalVariable *SGV = I; 571 GlobalValue *DGV = 0; 572 573 // Check to see if may have to link the global with the global, alias or 574 // function. 575 if (SGV->hasName() && !SGV->hasLocalLinkage()) 576 DGV = cast_or_null<GlobalValue>(DestSymTab.lookup(SGV->getName())); 577 578 // If we found a global with the same name in the dest module, but it has 579 // internal linkage, we are really not doing any linkage here. 580 if (DGV && DGV->hasLocalLinkage()) 581 DGV = 0; 582 583 // If types don't agree due to opaque types, try to resolve them. 584 if (DGV && DGV->getType() != SGV->getType()) 585 RecursiveResolveTypes(SGV->getType(), DGV->getType()); 586 587 assert((SGV->hasInitializer() || SGV->hasExternalWeakLinkage() || 588 SGV->hasExternalLinkage() || SGV->hasDLLImportLinkage()) && 589 "Global must either be external or have an initializer!"); 590 591 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 592 bool LinkFromSrc = false; 593 if (GetLinkageResult(DGV, SGV, NewLinkage, LinkFromSrc, Err)) 594 return true; 595 596 if (DGV == 0) { 597 // No linking to be performed, simply create an identical version of the 598 // symbol over in the dest module... the initializer will be filled in 599 // later by LinkGlobalInits. 600 GlobalVariable *NewDGV = 601 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 602 SGV->isConstant(), SGV->getLinkage(), /*init*/0, 603 SGV->getName(), 0, false, 604 SGV->getType()->getAddressSpace()); 605 // Propagate alignment, visibility and section info. 606 CopyGVAttributes(NewDGV, SGV); 607 608 // If the LLVM runtime renamed the global, but it is an externally visible 609 // symbol, DGV must be an existing global with internal linkage. Rename 610 // it. 611 if (!NewDGV->hasLocalLinkage() && NewDGV->getName() != SGV->getName()) 612 ForceRenaming(NewDGV, SGV->getName()); 613 614 // Make sure to remember this mapping. 615 ValueMap[SGV] = NewDGV; 616 617 // Keep track that this is an appending variable. 618 if (SGV->hasAppendingLinkage()) 619 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV)); 620 continue; 621 } 622 623 // If the visibilities of the symbols disagree and the destination is a 624 // prototype, take the visibility of its input. 625 if (DGV->isDeclaration()) 626 DGV->setVisibility(SGV->getVisibility()); 627 628 if (DGV->hasAppendingLinkage()) { 629 // No linking is performed yet. Just insert a new copy of the global, and 630 // keep track of the fact that it is an appending variable in the 631 // AppendingVars map. The name is cleared out so that no linkage is 632 // performed. 633 GlobalVariable *NewDGV = 634 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 635 SGV->isConstant(), SGV->getLinkage(), /*init*/0, 636 "", 0, false, 637 SGV->getType()->getAddressSpace()); 638 639 // Set alignment allowing CopyGVAttributes merge it with alignment of SGV. 640 NewDGV->setAlignment(DGV->getAlignment()); 641 // Propagate alignment, section and visibility info. 642 CopyGVAttributes(NewDGV, SGV); 643 644 // Make sure to remember this mapping... 645 ValueMap[SGV] = NewDGV; 646 647 // Keep track that this is an appending variable... 648 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV)); 649 continue; 650 } 651 652 if (LinkFromSrc) { 653 if (isa<GlobalAlias>(DGV)) 654 return Error(Err, "Global-Alias Collision on '" + SGV->getName() + 655 "': symbol multiple defined"); 656 657 // If the types don't match, and if we are to link from the source, nuke 658 // DGV and create a new one of the appropriate type. Note that the thing 659 // we are replacing may be a function (if a prototype, weak, etc) or a 660 // global variable. 661 GlobalVariable *NewDGV = 662 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 663 SGV->isConstant(), NewLinkage, /*init*/0, 664 DGV->getName(), 0, false, 665 SGV->getType()->getAddressSpace()); 666 667 // Propagate alignment, section, and visibility info. 668 CopyGVAttributes(NewDGV, SGV); 669 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV, 670 DGV->getType())); 671 672 // DGV will conflict with NewDGV because they both had the same 673 // name. We must erase this now so ForceRenaming doesn't assert 674 // because DGV might not have internal linkage. 675 if (GlobalVariable *Var = dyn_cast<GlobalVariable>(DGV)) 676 Var->eraseFromParent(); 677 else 678 cast<Function>(DGV)->eraseFromParent(); 679 680 // If the symbol table renamed the global, but it is an externally visible 681 // symbol, DGV must be an existing global with internal linkage. Rename. 682 if (NewDGV->getName() != SGV->getName() && !NewDGV->hasLocalLinkage()) 683 ForceRenaming(NewDGV, SGV->getName()); 684 685 // Inherit const as appropriate. 686 NewDGV->setConstant(SGV->isConstant()); 687 688 // Make sure to remember this mapping. 689 ValueMap[SGV] = NewDGV; 690 continue; 691 } 692 693 // Not "link from source", keep the one in the DestModule and remap the 694 // input onto it. 695 696 // Special case for const propagation. 697 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) 698 if (DGVar->isDeclaration() && SGV->isConstant() && !DGVar->isConstant()) 699 DGVar->setConstant(true); 700 701 // SGV is global, but DGV is alias. 702 if (isa<GlobalAlias>(DGV)) { 703 // The only valid mappings are: 704 // - SGV is external declaration, which is effectively a no-op. 705 // - SGV is weak, when we just need to throw SGV out. 706 if (!SGV->isDeclaration() && !SGV->isWeakForLinker()) 707 return Error(Err, "Global-Alias Collision on '" + SGV->getName() + 708 "': symbol multiple defined"); 709 } 710 711 // Set calculated linkage 712 DGV->setLinkage(NewLinkage); 713 714 // Make sure to remember this mapping... 715 ValueMap[SGV] = ConstantExpr::getBitCast(DGV, SGV->getType()); 716 } 717 return false; 718} 719 720static GlobalValue::LinkageTypes 721CalculateAliasLinkage(const GlobalValue *SGV, const GlobalValue *DGV) { 722 GlobalValue::LinkageTypes SL = SGV->getLinkage(); 723 GlobalValue::LinkageTypes DL = DGV->getLinkage(); 724 if (SL == GlobalValue::ExternalLinkage || DL == GlobalValue::ExternalLinkage) 725 return GlobalValue::ExternalLinkage; 726 else if (SL == GlobalValue::WeakAnyLinkage || 727 DL == GlobalValue::WeakAnyLinkage) 728 return GlobalValue::WeakAnyLinkage; 729 else if (SL == GlobalValue::WeakODRLinkage || 730 DL == GlobalValue::WeakODRLinkage) 731 return GlobalValue::WeakODRLinkage; 732 else if (SL == GlobalValue::InternalLinkage && 733 DL == GlobalValue::InternalLinkage) 734 return GlobalValue::InternalLinkage; 735 else if (SL == GlobalValue::LinkerPrivateLinkage && 736 DL == GlobalValue::LinkerPrivateLinkage) 737 return GlobalValue::LinkerPrivateLinkage; 738 else { 739 assert (SL == GlobalValue::PrivateLinkage && 740 DL == GlobalValue::PrivateLinkage && "Unexpected linkage type"); 741 return GlobalValue::PrivateLinkage; 742 } 743} 744 745// LinkAlias - Loop through the alias in the src module and link them into the 746// dest module. We're assuming, that all functions/global variables were already 747// linked in. 748static bool LinkAlias(Module *Dest, const Module *Src, 749 std::map<const Value*, Value*> &ValueMap, 750 std::string *Err) { 751 // Loop over all alias in the src module 752 for (Module::const_alias_iterator I = Src->alias_begin(), 753 E = Src->alias_end(); I != E; ++I) { 754 const GlobalAlias *SGA = I; 755 const GlobalValue *SAliasee = SGA->getAliasedGlobal(); 756 GlobalAlias *NewGA = NULL; 757 758 // Globals were already linked, thus we can just query ValueMap for variant 759 // of SAliasee in Dest. 760 std::map<const Value*,Value*>::const_iterator VMI = ValueMap.find(SAliasee); 761 assert(VMI != ValueMap.end() && "Aliasee not linked"); 762 GlobalValue* DAliasee = cast<GlobalValue>(VMI->second); 763 GlobalValue* DGV = NULL; 764 765 // Try to find something 'similar' to SGA in destination module. 766 if (!DGV && !SGA->hasLocalLinkage()) { 767 DGV = Dest->getNamedAlias(SGA->getName()); 768 769 // If types don't agree due to opaque types, try to resolve them. 770 if (DGV && DGV->getType() != SGA->getType()) 771 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 772 } 773 774 if (!DGV && !SGA->hasLocalLinkage()) { 775 DGV = Dest->getGlobalVariable(SGA->getName()); 776 777 // If types don't agree due to opaque types, try to resolve them. 778 if (DGV && DGV->getType() != SGA->getType()) 779 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 780 } 781 782 if (!DGV && !SGA->hasLocalLinkage()) { 783 DGV = Dest->getFunction(SGA->getName()); 784 785 // If types don't agree due to opaque types, try to resolve them. 786 if (DGV && DGV->getType() != SGA->getType()) 787 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 788 } 789 790 // No linking to be performed on internal stuff. 791 if (DGV && DGV->hasLocalLinkage()) 792 DGV = NULL; 793 794 if (GlobalAlias *DGA = dyn_cast_or_null<GlobalAlias>(DGV)) { 795 // Types are known to be the same, check whether aliasees equal. As 796 // globals are already linked we just need query ValueMap to find the 797 // mapping. 798 if (DAliasee == DGA->getAliasedGlobal()) { 799 // This is just two copies of the same alias. Propagate linkage, if 800 // necessary. 801 DGA->setLinkage(CalculateAliasLinkage(SGA, DGA)); 802 803 NewGA = DGA; 804 // Proceed to 'common' steps 805 } else 806 return Error(Err, "Alias Collision on '" + SGA->getName()+ 807 "': aliases have different aliasees"); 808 } else if (GlobalVariable *DGVar = dyn_cast_or_null<GlobalVariable>(DGV)) { 809 // The only allowed way is to link alias with external declaration or weak 810 // symbol.. 811 if (DGVar->isDeclaration() || DGVar->isWeakForLinker()) { 812 // But only if aliasee is global too... 813 if (!isa<GlobalVariable>(DAliasee)) 814 return Error(Err, "Global-Alias Collision on '" + SGA->getName() + 815 "': aliasee is not global variable"); 816 817 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 818 SGA->getName(), DAliasee, Dest); 819 CopyGVAttributes(NewGA, SGA); 820 821 // Any uses of DGV need to change to NewGA, with cast, if needed. 822 if (SGA->getType() != DGVar->getType()) 823 DGVar->replaceAllUsesWith(ConstantExpr::getBitCast(NewGA, 824 DGVar->getType())); 825 else 826 DGVar->replaceAllUsesWith(NewGA); 827 828 // DGVar will conflict with NewGA because they both had the same 829 // name. We must erase this now so ForceRenaming doesn't assert 830 // because DGV might not have internal linkage. 831 DGVar->eraseFromParent(); 832 833 // Proceed to 'common' steps 834 } else 835 return Error(Err, "Global-Alias Collision on '" + SGA->getName() + 836 "': symbol multiple defined"); 837 } else if (Function *DF = dyn_cast_or_null<Function>(DGV)) { 838 // The only allowed way is to link alias with external declaration or weak 839 // symbol... 840 if (DF->isDeclaration() || DF->isWeakForLinker()) { 841 // But only if aliasee is function too... 842 if (!isa<Function>(DAliasee)) 843 return Error(Err, "Function-Alias Collision on '" + SGA->getName() + 844 "': aliasee is not function"); 845 846 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 847 SGA->getName(), DAliasee, Dest); 848 CopyGVAttributes(NewGA, SGA); 849 850 // Any uses of DF need to change to NewGA, with cast, if needed. 851 if (SGA->getType() != DF->getType()) 852 DF->replaceAllUsesWith(ConstantExpr::getBitCast(NewGA, 853 DF->getType())); 854 else 855 DF->replaceAllUsesWith(NewGA); 856 857 // DF will conflict with NewGA because they both had the same 858 // name. We must erase this now so ForceRenaming doesn't assert 859 // because DF might not have internal linkage. 860 DF->eraseFromParent(); 861 862 // Proceed to 'common' steps 863 } else 864 return Error(Err, "Function-Alias Collision on '" + SGA->getName() + 865 "': symbol multiple defined"); 866 } else { 867 // No linking to be performed, simply create an identical version of the 868 // alias over in the dest module... 869 Constant *Aliasee = DAliasee; 870 // Fixup aliases to bitcasts. Note that aliases to GEPs are still broken 871 // by this, but aliases to GEPs are broken to a lot of other things, so 872 // it's less important. 873 if (SGA->getType() != DAliasee->getType()) 874 Aliasee = ConstantExpr::getBitCast(DAliasee, SGA->getType()); 875 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 876 SGA->getName(), Aliasee, Dest); 877 CopyGVAttributes(NewGA, SGA); 878 879 // Proceed to 'common' steps 880 } 881 882 assert(NewGA && "No alias was created in destination module!"); 883 884 // If the symbol table renamed the alias, but it is an externally visible 885 // symbol, DGA must be an global value with internal linkage. Rename it. 886 if (NewGA->getName() != SGA->getName() && 887 !NewGA->hasLocalLinkage()) 888 ForceRenaming(NewGA, SGA->getName()); 889 890 // Remember this mapping so uses in the source module get remapped 891 // later by RemapOperand. 892 ValueMap[SGA] = NewGA; 893 } 894 895 return false; 896} 897 898 899// LinkGlobalInits - Update the initializers in the Dest module now that all 900// globals that may be referenced are in Dest. 901static bool LinkGlobalInits(Module *Dest, const Module *Src, 902 std::map<const Value*, Value*> &ValueMap, 903 std::string *Err) { 904 // Loop over all of the globals in the src module, mapping them over as we go 905 for (Module::const_global_iterator I = Src->global_begin(), 906 E = Src->global_end(); I != E; ++I) { 907 const GlobalVariable *SGV = I; 908 909 if (SGV->hasInitializer()) { // Only process initialized GV's 910 // Figure out what the initializer looks like in the dest module... 911 Constant *SInit = 912 cast<Constant>(RemapOperand(SGV->getInitializer(), ValueMap)); 913 // Grab destination global variable or alias. 914 GlobalValue *DGV = cast<GlobalValue>(ValueMap[SGV]->stripPointerCasts()); 915 916 // If dest if global variable, check that initializers match. 917 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) { 918 if (DGVar->hasInitializer()) { 919 if (SGV->hasExternalLinkage()) { 920 if (DGVar->getInitializer() != SInit) 921 return Error(Err, "Global Variable Collision on '" + 922 SGV->getName() + 923 "': global variables have different initializers"); 924 } else if (DGVar->isWeakForLinker()) { 925 // Nothing is required, mapped values will take the new global 926 // automatically. 927 } else if (SGV->isWeakForLinker()) { 928 // Nothing is required, mapped values will take the new global 929 // automatically. 930 } else if (DGVar->hasAppendingLinkage()) { 931 llvm_unreachable("Appending linkage unimplemented!"); 932 } else { 933 llvm_unreachable("Unknown linkage!"); 934 } 935 } else { 936 // Copy the initializer over now... 937 DGVar->setInitializer(SInit); 938 } 939 } else { 940 // Destination is alias, the only valid situation is when source is 941 // weak. Also, note, that we already checked linkage in LinkGlobals(), 942 // thus we assert here. 943 // FIXME: Should we weaken this assumption, 'dereference' alias and 944 // check for initializer of aliasee? 945 assert(SGV->isWeakForLinker()); 946 } 947 } 948 } 949 return false; 950} 951 952// LinkFunctionProtos - Link the functions together between the two modules, 953// without doing function bodies... this just adds external function prototypes 954// to the Dest function... 955// 956static bool LinkFunctionProtos(Module *Dest, const Module *Src, 957 std::map<const Value*, Value*> &ValueMap, 958 std::string *Err) { 959 ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable(); 960 961 // Loop over all of the functions in the src module, mapping them over 962 for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) { 963 const Function *SF = I; // SrcFunction 964 GlobalValue *DGV = 0; 965 966 // Check to see if may have to link the function with the global, alias or 967 // function. 968 if (SF->hasName() && !SF->hasLocalLinkage()) 969 DGV = cast_or_null<GlobalValue>(DestSymTab.lookup(SF->getName())); 970 971 // If we found a global with the same name in the dest module, but it has 972 // internal linkage, we are really not doing any linkage here. 973 if (DGV && DGV->hasLocalLinkage()) 974 DGV = 0; 975 976 // If types don't agree due to opaque types, try to resolve them. 977 if (DGV && DGV->getType() != SF->getType()) 978 RecursiveResolveTypes(SF->getType(), DGV->getType()); 979 980 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 981 bool LinkFromSrc = false; 982 if (GetLinkageResult(DGV, SF, NewLinkage, LinkFromSrc, Err)) 983 return true; 984 985 // If there is no linkage to be performed, just bring over SF without 986 // modifying it. 987 if (DGV == 0) { 988 // Function does not already exist, simply insert an function signature 989 // identical to SF into the dest module. 990 Function *NewDF = Function::Create(SF->getFunctionType(), 991 SF->getLinkage(), 992 SF->getName(), Dest); 993 CopyGVAttributes(NewDF, SF); 994 995 // If the LLVM runtime renamed the function, but it is an externally 996 // visible symbol, DF must be an existing function with internal linkage. 997 // Rename it. 998 if (!NewDF->hasLocalLinkage() && NewDF->getName() != SF->getName()) 999 ForceRenaming(NewDF, SF->getName()); 1000 1001 // ... and remember this mapping... 1002 ValueMap[SF] = NewDF; 1003 continue; 1004 } 1005 1006 // If the visibilities of the symbols disagree and the destination is a 1007 // prototype, take the visibility of its input. 1008 if (DGV->isDeclaration()) 1009 DGV->setVisibility(SF->getVisibility()); 1010 1011 if (LinkFromSrc) { 1012 if (isa<GlobalAlias>(DGV)) 1013 return Error(Err, "Function-Alias Collision on '" + SF->getName() + 1014 "': symbol multiple defined"); 1015 1016 // We have a definition of the same name but different type in the 1017 // source module. Copy the prototype to the destination and replace 1018 // uses of the destination's prototype with the new prototype. 1019 Function *NewDF = Function::Create(SF->getFunctionType(), NewLinkage, 1020 SF->getName(), Dest); 1021 CopyGVAttributes(NewDF, SF); 1022 1023 // Any uses of DF need to change to NewDF, with cast 1024 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, 1025 DGV->getType())); 1026 1027 // DF will conflict with NewDF because they both had the same. We must 1028 // erase this now so ForceRenaming doesn't assert because DF might 1029 // not have internal linkage. 1030 if (GlobalVariable *Var = dyn_cast<GlobalVariable>(DGV)) 1031 Var->eraseFromParent(); 1032 else 1033 cast<Function>(DGV)->eraseFromParent(); 1034 1035 // If the symbol table renamed the function, but it is an externally 1036 // visible symbol, DF must be an existing function with internal 1037 // linkage. Rename it. 1038 if (NewDF->getName() != SF->getName() && !NewDF->hasLocalLinkage()) 1039 ForceRenaming(NewDF, SF->getName()); 1040 1041 // Remember this mapping so uses in the source module get remapped 1042 // later by RemapOperand. 1043 ValueMap[SF] = NewDF; 1044 continue; 1045 } 1046 1047 // Not "link from source", keep the one in the DestModule and remap the 1048 // input onto it. 1049 1050 if (isa<GlobalAlias>(DGV)) { 1051 // The only valid mappings are: 1052 // - SF is external declaration, which is effectively a no-op. 1053 // - SF is weak, when we just need to throw SF out. 1054 if (!SF->isDeclaration() && !SF->isWeakForLinker()) 1055 return Error(Err, "Function-Alias Collision on '" + SF->getName() + 1056 "': symbol multiple defined"); 1057 } 1058 1059 // Set calculated linkage 1060 DGV->setLinkage(NewLinkage); 1061 1062 // Make sure to remember this mapping. 1063 ValueMap[SF] = ConstantExpr::getBitCast(DGV, SF->getType()); 1064 } 1065 return false; 1066} 1067 1068// LinkFunctionBody - Copy the source function over into the dest function and 1069// fix up references to values. At this point we know that Dest is an external 1070// function, and that Src is not. 1071static bool LinkFunctionBody(Function *Dest, Function *Src, 1072 std::map<const Value*, Value*> &ValueMap, 1073 std::string *Err) { 1074 assert(Src && Dest && Dest->isDeclaration() && !Src->isDeclaration()); 1075 1076 // Go through and convert function arguments over, remembering the mapping. 1077 Function::arg_iterator DI = Dest->arg_begin(); 1078 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 1079 I != E; ++I, ++DI) { 1080 DI->setName(I->getName()); // Copy the name information over... 1081 1082 // Add a mapping to our local map 1083 ValueMap[I] = DI; 1084 } 1085 1086 // Splice the body of the source function into the dest function. 1087 Dest->getBasicBlockList().splice(Dest->end(), Src->getBasicBlockList()); 1088 1089 // At this point, all of the instructions and values of the function are now 1090 // copied over. The only problem is that they are still referencing values in 1091 // the Source function as operands. Loop through all of the operands of the 1092 // functions and patch them up to point to the local versions... 1093 // 1094 for (Function::iterator BB = Dest->begin(), BE = Dest->end(); BB != BE; ++BB) 1095 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) 1096 for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end(); 1097 OI != OE; ++OI) 1098 if (!isa<Instruction>(*OI) && !isa<BasicBlock>(*OI)) 1099 *OI = RemapOperand(*OI, ValueMap); 1100 1101 // There is no need to map the arguments anymore. 1102 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 1103 I != E; ++I) 1104 ValueMap.erase(I); 1105 1106 return false; 1107} 1108 1109 1110// LinkFunctionBodies - Link in the function bodies that are defined in the 1111// source module into the DestModule. This consists basically of copying the 1112// function over and fixing up references to values. 1113static bool LinkFunctionBodies(Module *Dest, Module *Src, 1114 std::map<const Value*, Value*> &ValueMap, 1115 std::string *Err) { 1116 1117 // Loop over all of the functions in the src module, mapping them over as we 1118 // go 1119 for (Module::iterator SF = Src->begin(), E = Src->end(); SF != E; ++SF) { 1120 if (!SF->isDeclaration()) { // No body if function is external 1121 Function *DF = dyn_cast<Function>(ValueMap[SF]); // Destination function 1122 1123 // DF not external SF external? 1124 if (DF && DF->isDeclaration()) 1125 // Only provide the function body if there isn't one already. 1126 if (LinkFunctionBody(DF, SF, ValueMap, Err)) 1127 return true; 1128 } 1129 } 1130 return false; 1131} 1132 1133// LinkAppendingVars - If there were any appending global variables, link them 1134// together now. Return true on error. 1135static bool LinkAppendingVars(Module *M, 1136 std::multimap<std::string, GlobalVariable *> &AppendingVars, 1137 std::string *ErrorMsg) { 1138 if (AppendingVars.empty()) return false; // Nothing to do. 1139 1140 // Loop over the multimap of appending vars, processing any variables with the 1141 // same name, forming a new appending global variable with both of the 1142 // initializers merged together, then rewrite references to the old variables 1143 // and delete them. 1144 std::vector<Constant*> Inits; 1145 while (AppendingVars.size() > 1) { 1146 // Get the first two elements in the map... 1147 std::multimap<std::string, 1148 GlobalVariable*>::iterator Second = AppendingVars.begin(), First=Second++; 1149 1150 // If the first two elements are for different names, there is no pair... 1151 // Otherwise there is a pair, so link them together... 1152 if (First->first == Second->first) { 1153 GlobalVariable *G1 = First->second, *G2 = Second->second; 1154 const ArrayType *T1 = cast<ArrayType>(G1->getType()->getElementType()); 1155 const ArrayType *T2 = cast<ArrayType>(G2->getType()->getElementType()); 1156 1157 // Check to see that they two arrays agree on type... 1158 if (T1->getElementType() != T2->getElementType()) 1159 return Error(ErrorMsg, 1160 "Appending variables with different element types need to be linked!"); 1161 if (G1->isConstant() != G2->isConstant()) 1162 return Error(ErrorMsg, 1163 "Appending variables linked with different const'ness!"); 1164 1165 if (G1->getAlignment() != G2->getAlignment()) 1166 return Error(ErrorMsg, 1167 "Appending variables with different alignment need to be linked!"); 1168 1169 if (G1->getVisibility() != G2->getVisibility()) 1170 return Error(ErrorMsg, 1171 "Appending variables with different visibility need to be linked!"); 1172 1173 if (G1->getSection() != G2->getSection()) 1174 return Error(ErrorMsg, 1175 "Appending variables with different section name need to be linked!"); 1176 1177 unsigned NewSize = T1->getNumElements() + T2->getNumElements(); 1178 ArrayType *NewType = ArrayType::get(T1->getElementType(), 1179 NewSize); 1180 1181 G1->setName(""); // Clear G1's name in case of a conflict! 1182 1183 // Create the new global variable... 1184 GlobalVariable *NG = 1185 new GlobalVariable(*M, NewType, G1->isConstant(), G1->getLinkage(), 1186 /*init*/0, First->first, 0, G1->isThreadLocal(), 1187 G1->getType()->getAddressSpace()); 1188 1189 // Propagate alignment, visibility and section info. 1190 CopyGVAttributes(NG, G1); 1191 1192 // Merge the initializer... 1193 Inits.reserve(NewSize); 1194 if (ConstantArray *I = dyn_cast<ConstantArray>(G1->getInitializer())) { 1195 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i) 1196 Inits.push_back(I->getOperand(i)); 1197 } else { 1198 assert(isa<ConstantAggregateZero>(G1->getInitializer())); 1199 Constant *CV = Constant::getNullValue(T1->getElementType()); 1200 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i) 1201 Inits.push_back(CV); 1202 } 1203 if (ConstantArray *I = dyn_cast<ConstantArray>(G2->getInitializer())) { 1204 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i) 1205 Inits.push_back(I->getOperand(i)); 1206 } else { 1207 assert(isa<ConstantAggregateZero>(G2->getInitializer())); 1208 Constant *CV = Constant::getNullValue(T2->getElementType()); 1209 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i) 1210 Inits.push_back(CV); 1211 } 1212 NG->setInitializer(ConstantArray::get(NewType, Inits)); 1213 Inits.clear(); 1214 1215 // Replace any uses of the two global variables with uses of the new 1216 // global... 1217 1218 // FIXME: This should rewrite simple/straight-forward uses such as 1219 // getelementptr instructions to not use the Cast! 1220 G1->replaceAllUsesWith(ConstantExpr::getBitCast(NG, 1221 G1->getType())); 1222 G2->replaceAllUsesWith(ConstantExpr::getBitCast(NG, 1223 G2->getType())); 1224 1225 // Remove the two globals from the module now... 1226 M->getGlobalList().erase(G1); 1227 M->getGlobalList().erase(G2); 1228 1229 // Put the new global into the AppendingVars map so that we can handle 1230 // linking of more than two vars... 1231 Second->second = NG; 1232 } 1233 AppendingVars.erase(First); 1234 } 1235 1236 return false; 1237} 1238 1239static bool ResolveAliases(Module *Dest) { 1240 for (Module::alias_iterator I = Dest->alias_begin(), E = Dest->alias_end(); 1241 I != E; ++I) 1242 // We can't sue resolveGlobalAlias here because we need to preserve 1243 // bitcasts and GEPs. 1244 if (const Constant *C = I->getAliasee()) { 1245 while (dyn_cast<GlobalAlias>(C)) 1246 C = cast<GlobalAlias>(C)->getAliasee(); 1247 const GlobalValue *GV = dyn_cast<GlobalValue>(C); 1248 if (C != I && !(GV && GV->isDeclaration())) 1249 I->replaceAllUsesWith(const_cast<Constant*>(C)); 1250 } 1251 1252 return false; 1253} 1254 1255// LinkModules - This function links two modules together, with the resulting 1256// left module modified to be the composite of the two input modules. If an 1257// error occurs, true is returned and ErrorMsg (if not null) is set to indicate 1258// the problem. Upon failure, the Dest module could be in a modified state, and 1259// shouldn't be relied on to be consistent. 1260bool 1261Linker::LinkModules(Module *Dest, Module *Src, std::string *ErrorMsg) { 1262 assert(Dest != 0 && "Invalid Destination module"); 1263 assert(Src != 0 && "Invalid Source Module"); 1264 1265 if (Dest->getDataLayout().empty()) { 1266 if (!Src->getDataLayout().empty()) { 1267 Dest->setDataLayout(Src->getDataLayout()); 1268 } else { 1269 std::string DataLayout; 1270 1271 if (Dest->getEndianness() == Module::AnyEndianness) { 1272 if (Src->getEndianness() == Module::BigEndian) 1273 DataLayout.append("E"); 1274 else if (Src->getEndianness() == Module::LittleEndian) 1275 DataLayout.append("e"); 1276 } 1277 1278 if (Dest->getPointerSize() == Module::AnyPointerSize) { 1279 if (Src->getPointerSize() == Module::Pointer64) 1280 DataLayout.append(DataLayout.length() == 0 ? "p:64:64" : "-p:64:64"); 1281 else if (Src->getPointerSize() == Module::Pointer32) 1282 DataLayout.append(DataLayout.length() == 0 ? "p:32:32" : "-p:32:32"); 1283 } 1284 Dest->setDataLayout(DataLayout); 1285 } 1286 } 1287 1288 // Copy the target triple from the source to dest if the dest's is empty. 1289 if (Dest->getTargetTriple().empty() && !Src->getTargetTriple().empty()) 1290 Dest->setTargetTriple(Src->getTargetTriple()); 1291 1292 if (!Src->getDataLayout().empty() && !Dest->getDataLayout().empty() && 1293 Src->getDataLayout() != Dest->getDataLayout()) 1294 errs() << "WARNING: Linking two modules of different data layouts!\n"; 1295 if (!Src->getTargetTriple().empty() && 1296 Dest->getTargetTriple() != Src->getTargetTriple()) 1297 errs() << "WARNING: Linking two modules of different target triples!\n"; 1298 1299 // Append the module inline asm string. 1300 if (!Src->getModuleInlineAsm().empty()) { 1301 if (Dest->getModuleInlineAsm().empty()) 1302 Dest->setModuleInlineAsm(Src->getModuleInlineAsm()); 1303 else 1304 Dest->setModuleInlineAsm(Dest->getModuleInlineAsm()+"\n"+ 1305 Src->getModuleInlineAsm()); 1306 } 1307 1308 // Update the destination module's dependent libraries list with the libraries 1309 // from the source module. There's no opportunity for duplicates here as the 1310 // Module ensures that duplicate insertions are discarded. 1311 for (Module::lib_iterator SI = Src->lib_begin(), SE = Src->lib_end(); 1312 SI != SE; ++SI) 1313 Dest->addLibrary(*SI); 1314 1315 // LinkTypes - Go through the symbol table of the Src module and see if any 1316 // types are named in the src module that are not named in the Dst module. 1317 // Make sure there are no type name conflicts. 1318 if (LinkTypes(Dest, Src, ErrorMsg)) 1319 return true; 1320 1321 // ValueMap - Mapping of values from what they used to be in Src, to what they 1322 // are now in Dest. 1323 std::map<const Value*, Value*> ValueMap; 1324 1325 // AppendingVars - Keep track of global variables in the destination module 1326 // with appending linkage. After the module is linked together, they are 1327 // appended and the module is rewritten. 1328 std::multimap<std::string, GlobalVariable *> AppendingVars; 1329 for (Module::global_iterator I = Dest->global_begin(), E = Dest->global_end(); 1330 I != E; ++I) { 1331 // Add all of the appending globals already in the Dest module to 1332 // AppendingVars. 1333 if (I->hasAppendingLinkage()) 1334 AppendingVars.insert(std::make_pair(I->getName(), I)); 1335 } 1336 1337 // Insert all of the named mdnoes in Src into the Dest module. 1338 LinkNamedMDNodes(Dest, Src); 1339 1340 // Insert all of the globals in src into the Dest module... without linking 1341 // initializers (which could refer to functions not yet mapped over). 1342 if (LinkGlobals(Dest, Src, ValueMap, AppendingVars, ErrorMsg)) 1343 return true; 1344 1345 // Link the functions together between the two modules, without doing function 1346 // bodies... this just adds external function prototypes to the Dest 1347 // function... We do this so that when we begin processing function bodies, 1348 // all of the global values that may be referenced are available in our 1349 // ValueMap. 1350 if (LinkFunctionProtos(Dest, Src, ValueMap, ErrorMsg)) 1351 return true; 1352 1353 // If there were any alias, link them now. We really need to do this now, 1354 // because all of the aliases that may be referenced need to be available in 1355 // ValueMap 1356 if (LinkAlias(Dest, Src, ValueMap, ErrorMsg)) return true; 1357 1358 // Update the initializers in the Dest module now that all globals that may 1359 // be referenced are in Dest. 1360 if (LinkGlobalInits(Dest, Src, ValueMap, ErrorMsg)) return true; 1361 1362 // Link in the function bodies that are defined in the source module into the 1363 // DestModule. This consists basically of copying the function over and 1364 // fixing up references to values. 1365 if (LinkFunctionBodies(Dest, Src, ValueMap, ErrorMsg)) return true; 1366 1367 // If there were any appending global variables, link them together now. 1368 if (LinkAppendingVars(Dest, AppendingVars, ErrorMsg)) return true; 1369 1370 // Resolve all uses of aliases with aliasees 1371 if (ResolveAliases(Dest)) return true; 1372 1373 // If the source library's module id is in the dependent library list of the 1374 // destination library, remove it since that module is now linked in. 1375 sys::Path modId; 1376 modId.set(Src->getModuleIdentifier()); 1377 if (!modId.isEmpty()) 1378 Dest->removeLibrary(modId.getBasename()); 1379 1380 return false; 1381} 1382 1383// vim: sw=2 1384