LinkModules.cpp revision 7bf5cf401f27ac7cafe3e2c097cf14b7bb30a653
1//===- lib/Linker/LinkModules.cpp - Module Linker Implementation ----------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file implements the LLVM module linker. 11// 12// Specifically, this: 13// * Merges global variables between the two modules 14// * Uninit + Uninit = Init, Init + Uninit = Init, Init + Init = Error if != 15// * Merges functions between two modules 16// 17//===----------------------------------------------------------------------===// 18 19#include "llvm/Linker.h" 20#include "llvm/Constants.h" 21#include "llvm/DerivedTypes.h" 22#include "llvm/LLVMContext.h" 23#include "llvm/Module.h" 24#include "llvm/TypeSymbolTable.h" 25#include "llvm/ValueSymbolTable.h" 26#include "llvm/Instructions.h" 27#include "llvm/Assembly/Writer.h" 28#include "llvm/Support/Debug.h" 29#include "llvm/Support/ErrorHandling.h" 30#include "llvm/Support/raw_ostream.h" 31#include "llvm/System/Path.h" 32#include "llvm/ADT/DenseMap.h" 33using namespace llvm; 34 35// Error - Simple wrapper function to conditionally assign to E and return true. 36// This just makes error return conditions a little bit simpler... 37static inline bool Error(std::string *E, const Twine &Message) { 38 if (E) *E = Message.str(); 39 return true; 40} 41 42// Function: ResolveTypes() 43// 44// Description: 45// Attempt to link the two specified types together. 46// 47// Inputs: 48// DestTy - The type to which we wish to resolve. 49// SrcTy - The original type which we want to resolve. 50// 51// Outputs: 52// DestST - The symbol table in which the new type should be placed. 53// 54// Return value: 55// true - There is an error and the types cannot yet be linked. 56// false - No errors. 57// 58static bool ResolveTypes(const Type *DestTy, const Type *SrcTy) { 59 if (DestTy == SrcTy) return false; // If already equal, noop 60 assert(DestTy && SrcTy && "Can't handle null types"); 61 62 if (const OpaqueType *OT = dyn_cast<OpaqueType>(DestTy)) { 63 // Type _is_ in module, just opaque... 64 const_cast<OpaqueType*>(OT)->refineAbstractTypeTo(SrcTy); 65 } else if (const OpaqueType *OT = dyn_cast<OpaqueType>(SrcTy)) { 66 const_cast<OpaqueType*>(OT)->refineAbstractTypeTo(DestTy); 67 } else { 68 return true; // Cannot link types... not-equal and neither is opaque. 69 } 70 return false; 71} 72 73/// LinkerTypeMap - This implements a map of types that is stable 74/// even if types are resolved/refined to other types. This is not a general 75/// purpose map, it is specific to the linker's use. 76namespace { 77class LinkerTypeMap : public AbstractTypeUser { 78 typedef DenseMap<const Type*, PATypeHolder> TheMapTy; 79 TheMapTy TheMap; 80 81 LinkerTypeMap(const LinkerTypeMap&); // DO NOT IMPLEMENT 82 void operator=(const LinkerTypeMap&); // DO NOT IMPLEMENT 83public: 84 LinkerTypeMap() {} 85 ~LinkerTypeMap() { 86 for (DenseMap<const Type*, PATypeHolder>::iterator I = TheMap.begin(), 87 E = TheMap.end(); I != E; ++I) 88 I->first->removeAbstractTypeUser(this); 89 } 90 91 /// lookup - Return the value for the specified type or null if it doesn't 92 /// exist. 93 const Type *lookup(const Type *Ty) const { 94 TheMapTy::const_iterator I = TheMap.find(Ty); 95 if (I != TheMap.end()) return I->second; 96 return 0; 97 } 98 99 /// erase - Remove the specified type, returning true if it was in the set. 100 bool erase(const Type *Ty) { 101 if (!TheMap.erase(Ty)) 102 return false; 103 if (Ty->isAbstract()) 104 Ty->removeAbstractTypeUser(this); 105 return true; 106 } 107 108 /// insert - This returns true if the pointer was new to the set, false if it 109 /// was already in the set. 110 bool insert(const Type *Src, const Type *Dst) { 111 if (!TheMap.insert(std::make_pair(Src, PATypeHolder(Dst))).second) 112 return false; // Already in map. 113 if (Src->isAbstract()) 114 Src->addAbstractTypeUser(this); 115 return true; 116 } 117 118protected: 119 /// refineAbstractType - The callback method invoked when an abstract type is 120 /// resolved to another type. An object must override this method to update 121 /// its internal state to reference NewType instead of OldType. 122 /// 123 virtual void refineAbstractType(const DerivedType *OldTy, 124 const Type *NewTy) { 125 TheMapTy::iterator I = TheMap.find(OldTy); 126 const Type *DstTy = I->second; 127 128 TheMap.erase(I); 129 if (OldTy->isAbstract()) 130 OldTy->removeAbstractTypeUser(this); 131 132 // Don't reinsert into the map if the key is concrete now. 133 if (NewTy->isAbstract()) 134 insert(NewTy, DstTy); 135 } 136 137 /// The other case which AbstractTypeUsers must be aware of is when a type 138 /// makes the transition from being abstract (where it has clients on it's 139 /// AbstractTypeUsers list) to concrete (where it does not). This method 140 /// notifies ATU's when this occurs for a type. 141 virtual void typeBecameConcrete(const DerivedType *AbsTy) { 142 TheMap.erase(AbsTy); 143 AbsTy->removeAbstractTypeUser(this); 144 } 145 146 // for debugging... 147 virtual void dump() const { 148 dbgs() << "AbstractTypeSet!\n"; 149 } 150}; 151} 152 153 154// RecursiveResolveTypes - This is just like ResolveTypes, except that it 155// recurses down into derived types, merging the used types if the parent types 156// are compatible. 157static bool RecursiveResolveTypesI(const Type *DstTy, const Type *SrcTy, 158 LinkerTypeMap &Pointers) { 159 if (DstTy == SrcTy) return false; // If already equal, noop 160 161 // If we found our opaque type, resolve it now! 162 if (isa<OpaqueType>(DstTy) || isa<OpaqueType>(SrcTy)) 163 return ResolveTypes(DstTy, SrcTy); 164 165 // Two types cannot be resolved together if they are of different primitive 166 // type. For example, we cannot resolve an int to a float. 167 if (DstTy->getTypeID() != SrcTy->getTypeID()) return true; 168 169 // If neither type is abstract, then they really are just different types. 170 if (!DstTy->isAbstract() && !SrcTy->isAbstract()) 171 return true; 172 173 // Otherwise, resolve the used type used by this derived type... 174 switch (DstTy->getTypeID()) { 175 default: 176 return true; 177 case Type::FunctionTyID: { 178 const FunctionType *DstFT = cast<FunctionType>(DstTy); 179 const FunctionType *SrcFT = cast<FunctionType>(SrcTy); 180 if (DstFT->isVarArg() != SrcFT->isVarArg() || 181 DstFT->getNumContainedTypes() != SrcFT->getNumContainedTypes()) 182 return true; 183 184 // Use TypeHolder's so recursive resolution won't break us. 185 PATypeHolder ST(SrcFT), DT(DstFT); 186 for (unsigned i = 0, e = DstFT->getNumContainedTypes(); i != e; ++i) { 187 const Type *SE = ST->getContainedType(i), *DE = DT->getContainedType(i); 188 if (SE != DE && RecursiveResolveTypesI(DE, SE, Pointers)) 189 return true; 190 } 191 return false; 192 } 193 case Type::StructTyID: { 194 const StructType *DstST = cast<StructType>(DstTy); 195 const StructType *SrcST = cast<StructType>(SrcTy); 196 if (DstST->getNumContainedTypes() != SrcST->getNumContainedTypes()) 197 return true; 198 199 PATypeHolder ST(SrcST), DT(DstST); 200 for (unsigned i = 0, e = DstST->getNumContainedTypes(); i != e; ++i) { 201 const Type *SE = ST->getContainedType(i), *DE = DT->getContainedType(i); 202 if (SE != DE && RecursiveResolveTypesI(DE, SE, Pointers)) 203 return true; 204 } 205 return false; 206 } 207 case Type::ArrayTyID: { 208 const ArrayType *DAT = cast<ArrayType>(DstTy); 209 const ArrayType *SAT = cast<ArrayType>(SrcTy); 210 if (DAT->getNumElements() != SAT->getNumElements()) return true; 211 return RecursiveResolveTypesI(DAT->getElementType(), SAT->getElementType(), 212 Pointers); 213 } 214 case Type::VectorTyID: { 215 const VectorType *DVT = cast<VectorType>(DstTy); 216 const VectorType *SVT = cast<VectorType>(SrcTy); 217 if (DVT->getNumElements() != SVT->getNumElements()) return true; 218 return RecursiveResolveTypesI(DVT->getElementType(), SVT->getElementType(), 219 Pointers); 220 } 221 case Type::PointerTyID: { 222 const PointerType *DstPT = cast<PointerType>(DstTy); 223 const PointerType *SrcPT = cast<PointerType>(SrcTy); 224 225 if (DstPT->getAddressSpace() != SrcPT->getAddressSpace()) 226 return true; 227 228 // If this is a pointer type, check to see if we have already seen it. If 229 // so, we are in a recursive branch. Cut off the search now. We cannot use 230 // an associative container for this search, because the type pointers (keys 231 // in the container) change whenever types get resolved. 232 if (SrcPT->isAbstract()) 233 if (const Type *ExistingDestTy = Pointers.lookup(SrcPT)) 234 return ExistingDestTy != DstPT; 235 236 if (DstPT->isAbstract()) 237 if (const Type *ExistingSrcTy = Pointers.lookup(DstPT)) 238 return ExistingSrcTy != SrcPT; 239 // Otherwise, add the current pointers to the vector to stop recursion on 240 // this pair. 241 if (DstPT->isAbstract()) 242 Pointers.insert(DstPT, SrcPT); 243 if (SrcPT->isAbstract()) 244 Pointers.insert(SrcPT, DstPT); 245 246 return RecursiveResolveTypesI(DstPT->getElementType(), 247 SrcPT->getElementType(), Pointers); 248 } 249 } 250} 251 252static bool RecursiveResolveTypes(const Type *DestTy, const Type *SrcTy) { 253 LinkerTypeMap PointerTypes; 254 return RecursiveResolveTypesI(DestTy, SrcTy, PointerTypes); 255} 256 257 258// LinkTypes - Go through the symbol table of the Src module and see if any 259// types are named in the src module that are not named in the Dst module. 260// Make sure there are no type name conflicts. 261static bool LinkTypes(Module *Dest, const Module *Src, std::string *Err) { 262 TypeSymbolTable *DestST = &Dest->getTypeSymbolTable(); 263 const TypeSymbolTable *SrcST = &Src->getTypeSymbolTable(); 264 265 // Look for a type plane for Type's... 266 TypeSymbolTable::const_iterator TI = SrcST->begin(); 267 TypeSymbolTable::const_iterator TE = SrcST->end(); 268 if (TI == TE) return false; // No named types, do nothing. 269 270 // Some types cannot be resolved immediately because they depend on other 271 // types being resolved to each other first. This contains a list of types we 272 // are waiting to recheck. 273 std::vector<std::string> DelayedTypesToResolve; 274 275 for ( ; TI != TE; ++TI ) { 276 const std::string &Name = TI->first; 277 const Type *RHS = TI->second; 278 279 // Check to see if this type name is already in the dest module. 280 Type *Entry = DestST->lookup(Name); 281 282 // If the name is just in the source module, bring it over to the dest. 283 if (Entry == 0) { 284 if (!Name.empty()) 285 DestST->insert(Name, const_cast<Type*>(RHS)); 286 } else if (ResolveTypes(Entry, RHS)) { 287 // They look different, save the types 'till later to resolve. 288 DelayedTypesToResolve.push_back(Name); 289 } 290 } 291 292 // Iteratively resolve types while we can... 293 while (!DelayedTypesToResolve.empty()) { 294 // Loop over all of the types, attempting to resolve them if possible... 295 unsigned OldSize = DelayedTypesToResolve.size(); 296 297 // Try direct resolution by name... 298 for (unsigned i = 0; i != DelayedTypesToResolve.size(); ++i) { 299 const std::string &Name = DelayedTypesToResolve[i]; 300 Type *T1 = SrcST->lookup(Name); 301 Type *T2 = DestST->lookup(Name); 302 if (!ResolveTypes(T2, T1)) { 303 // We are making progress! 304 DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i); 305 --i; 306 } 307 } 308 309 // Did we not eliminate any types? 310 if (DelayedTypesToResolve.size() == OldSize) { 311 // Attempt to resolve subelements of types. This allows us to merge these 312 // two types: { int* } and { opaque* } 313 for (unsigned i = 0, e = DelayedTypesToResolve.size(); i != e; ++i) { 314 const std::string &Name = DelayedTypesToResolve[i]; 315 if (!RecursiveResolveTypes(SrcST->lookup(Name), DestST->lookup(Name))) { 316 // We are making progress! 317 DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i); 318 319 // Go back to the main loop, perhaps we can resolve directly by name 320 // now... 321 break; 322 } 323 } 324 325 // If we STILL cannot resolve the types, then there is something wrong. 326 if (DelayedTypesToResolve.size() == OldSize) { 327 // Remove the symbol name from the destination. 328 DelayedTypesToResolve.pop_back(); 329 } 330 } 331 } 332 333 334 return false; 335} 336 337#ifndef NDEBUG 338static void PrintMap(const std::map<const Value*, Value*> &M) { 339 for (std::map<const Value*, Value*>::const_iterator I = M.begin(), E =M.end(); 340 I != E; ++I) { 341 dbgs() << " Fr: " << (void*)I->first << " "; 342 I->first->dump(); 343 dbgs() << " To: " << (void*)I->second << " "; 344 I->second->dump(); 345 dbgs() << "\n"; 346 } 347} 348#endif 349 350 351// RemapOperand - Use ValueMap to convert constants from one module to another. 352static Value *RemapOperand(const Value *In, 353 std::map<const Value*, Value*> &ValueMap) { 354 std::map<const Value*,Value*>::const_iterator I = ValueMap.find(In); 355 if (I != ValueMap.end()) 356 return I->second; 357 358 // Check to see if it's a constant that we are interested in transforming. 359 Value *Result = 0; 360 if (const Constant *CPV = dyn_cast<Constant>(In)) { 361 if ((!isa<DerivedType>(CPV->getType()) && !isa<ConstantExpr>(CPV)) || 362 isa<ConstantInt>(CPV) || isa<ConstantAggregateZero>(CPV)) 363 return const_cast<Constant*>(CPV); // Simple constants stay identical. 364 365 if (const ConstantArray *CPA = dyn_cast<ConstantArray>(CPV)) { 366 std::vector<Constant*> Operands(CPA->getNumOperands()); 367 for (unsigned i = 0, e = CPA->getNumOperands(); i != e; ++i) 368 Operands[i] =cast<Constant>(RemapOperand(CPA->getOperand(i), ValueMap)); 369 Result = ConstantArray::get(cast<ArrayType>(CPA->getType()), Operands); 370 } else if (const ConstantStruct *CPS = dyn_cast<ConstantStruct>(CPV)) { 371 std::vector<Constant*> Operands(CPS->getNumOperands()); 372 for (unsigned i = 0, e = CPS->getNumOperands(); i != e; ++i) 373 Operands[i] =cast<Constant>(RemapOperand(CPS->getOperand(i), ValueMap)); 374 Result = ConstantStruct::get(cast<StructType>(CPS->getType()), Operands); 375 } else if (isa<ConstantPointerNull>(CPV) || isa<UndefValue>(CPV)) { 376 Result = const_cast<Constant*>(CPV); 377 } else if (const ConstantVector *CP = dyn_cast<ConstantVector>(CPV)) { 378 std::vector<Constant*> Operands(CP->getNumOperands()); 379 for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i) 380 Operands[i] = cast<Constant>(RemapOperand(CP->getOperand(i), ValueMap)); 381 Result = ConstantVector::get(Operands); 382 } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CPV)) { 383 std::vector<Constant*> Ops; 384 for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) 385 Ops.push_back(cast<Constant>(RemapOperand(CE->getOperand(i),ValueMap))); 386 Result = CE->getWithOperands(Ops); 387 } else if (const BlockAddress *CE = dyn_cast<BlockAddress>(CPV)) { 388 Result = BlockAddress::get( 389 cast<Function>(RemapOperand(CE->getFunction(), ValueMap)), 390 CE->getBasicBlock()); 391 } else { 392 assert(!isa<GlobalValue>(CPV) && "Unmapped global?"); 393 llvm_unreachable("Unknown type of derived type constant value!"); 394 } 395 } else if (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 Elts.push_back(RemapOperand(MD->getOperand(i), ValueMap)); 400 Result = MDNode::get(In->getContext(), Elts.data(), MD->getNumOperands()); 401 } else { 402 Result = const_cast<Value*>(In); 403 } 404 } else if (isa<MDString>(In) || isa<InlineAsm>(In) || isa<Instruction>(In)) { 405 Result = const_cast<Value*>(In); 406 } 407 408 // Cache the mapping in our local map structure 409 if (Result) { 410 ValueMap[In] = Result; 411 return Result; 412 } 413 414#ifndef NDEBUG 415 dbgs() << "LinkModules ValueMap: \n"; 416 PrintMap(ValueMap); 417 418 dbgs() << "Couldn't remap value: " << (void*)In << " " << *In << "\n"; 419 llvm_unreachable("Couldn't remap value!"); 420#endif 421 return 0; 422} 423 424/// ForceRenaming - The LLVM SymbolTable class autorenames globals that conflict 425/// in the symbol table. This is good for all clients except for us. Go 426/// through the trouble to force this back. 427static void ForceRenaming(GlobalValue *GV, const std::string &Name) { 428 assert(GV->getName() != Name && "Can't force rename to self"); 429 ValueSymbolTable &ST = GV->getParent()->getValueSymbolTable(); 430 431 // If there is a conflict, rename the conflict. 432 if (GlobalValue *ConflictGV = cast_or_null<GlobalValue>(ST.lookup(Name))) { 433 assert(ConflictGV->hasLocalLinkage() && 434 "Not conflicting with a static global, should link instead!"); 435 GV->takeName(ConflictGV); 436 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed 437 assert(ConflictGV->getName() != Name && "ForceRenaming didn't work"); 438 } else { 439 GV->setName(Name); // Force the name back 440 } 441} 442 443/// CopyGVAttributes - copy additional attributes (those not needed to construct 444/// a GlobalValue) from the SrcGV to the DestGV. 445static void CopyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) { 446 // Use the maximum alignment, rather than just copying the alignment of SrcGV. 447 unsigned Alignment = std::max(DestGV->getAlignment(), SrcGV->getAlignment()); 448 DestGV->copyAttributesFrom(SrcGV); 449 DestGV->setAlignment(Alignment); 450} 451 452/// GetLinkageResult - This analyzes the two global values and determines what 453/// the result will look like in the destination module. In particular, it 454/// computes the resultant linkage type, computes whether the global in the 455/// source should be copied over to the destination (replacing the existing 456/// one), and computes whether this linkage is an error or not. It also performs 457/// visibility checks: we cannot link together two symbols with different 458/// visibilities. 459static bool GetLinkageResult(GlobalValue *Dest, const GlobalValue *Src, 460 GlobalValue::LinkageTypes <, bool &LinkFromSrc, 461 std::string *Err) { 462 assert((!Dest || !Src->hasLocalLinkage()) && 463 "If Src has internal linkage, Dest shouldn't be set!"); 464 if (!Dest) { 465 // Linking something to nothing. 466 LinkFromSrc = true; 467 LT = Src->getLinkage(); 468 } else if (Src->isDeclaration()) { 469 // If Src is external or if both Src & Dest are external.. Just link the 470 // external globals, we aren't adding anything. 471 if (Src->hasDLLImportLinkage()) { 472 // If one of GVs has DLLImport linkage, result should be dllimport'ed. 473 if (Dest->isDeclaration()) { 474 LinkFromSrc = true; 475 LT = Src->getLinkage(); 476 } 477 } else if (Dest->hasExternalWeakLinkage()) { 478 // If the Dest is weak, use the source linkage. 479 LinkFromSrc = true; 480 LT = Src->getLinkage(); 481 } else { 482 LinkFromSrc = false; 483 LT = Dest->getLinkage(); 484 } 485 } else if (Dest->isDeclaration() && !Dest->hasDLLImportLinkage()) { 486 // If Dest is external but Src is not: 487 LinkFromSrc = true; 488 LT = Src->getLinkage(); 489 } else if (Src->hasAppendingLinkage() || Dest->hasAppendingLinkage()) { 490 if (Src->getLinkage() != Dest->getLinkage()) 491 return Error(Err, "Linking globals named '" + Src->getName() + 492 "': can only link appending global with another appending global!"); 493 LinkFromSrc = true; // Special cased. 494 LT = Src->getLinkage(); 495 } else if (Src->isWeakForLinker()) { 496 // At this point we know that Dest has LinkOnce, External*, Weak, Common, 497 // or DLL* linkage. 498 if (Dest->hasExternalWeakLinkage() || 499 Dest->hasAvailableExternallyLinkage() || 500 (Dest->hasLinkOnceLinkage() && 501 (Src->hasWeakLinkage() || Src->hasCommonLinkage()))) { 502 LinkFromSrc = true; 503 LT = Src->getLinkage(); 504 } else { 505 LinkFromSrc = false; 506 LT = Dest->getLinkage(); 507 } 508 } else if (Dest->isWeakForLinker()) { 509 // At this point we know that Src has External* or DLL* linkage. 510 if (Src->hasExternalWeakLinkage()) { 511 LinkFromSrc = false; 512 LT = Dest->getLinkage(); 513 } else { 514 LinkFromSrc = true; 515 LT = GlobalValue::ExternalLinkage; 516 } 517 } else { 518 assert((Dest->hasExternalLinkage() || 519 Dest->hasDLLImportLinkage() || 520 Dest->hasDLLExportLinkage() || 521 Dest->hasExternalWeakLinkage()) && 522 (Src->hasExternalLinkage() || 523 Src->hasDLLImportLinkage() || 524 Src->hasDLLExportLinkage() || 525 Src->hasExternalWeakLinkage()) && 526 "Unexpected linkage type!"); 527 return Error(Err, "Linking globals named '" + Src->getName() + 528 "': symbol multiply defined!"); 529 } 530 531 // Check visibility 532 if (Dest && Src->getVisibility() != Dest->getVisibility()) 533 if (!Src->isDeclaration() && !Dest->isDeclaration()) 534 return Error(Err, "Linking globals named '" + Src->getName() + 535 "': symbols have different visibilities!"); 536 return false; 537} 538 539// Insert all of the named mdnoes in Src into the Dest module. 540static void LinkNamedMDNodes(Module *Dest, Module *Src) { 541 for (Module::const_named_metadata_iterator I = Src->named_metadata_begin(), 542 E = Src->named_metadata_end(); I != E; ++I) { 543 const NamedMDNode *SrcNMD = I; 544 NamedMDNode *DestNMD = Dest->getNamedMetadata(SrcNMD->getName()); 545 if (!DestNMD) 546 NamedMDNode::Create(SrcNMD, Dest); 547 else { 548 // Add Src elements into Dest node. 549 for (unsigned i = 0, e = SrcNMD->getNumOperands(); i != e; ++i) 550 DestNMD->addOperand(SrcNMD->getOperand(i)); 551 } 552 } 553} 554 555// LinkGlobals - Loop through the global variables in the src module and merge 556// them into the dest module. 557static bool LinkGlobals(Module *Dest, const Module *Src, 558 std::map<const Value*, Value*> &ValueMap, 559 std::multimap<std::string, GlobalVariable *> &AppendingVars, 560 std::string *Err) { 561 ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable(); 562 563 // Loop over all of the globals in the src module, mapping them over as we go 564 for (Module::const_global_iterator I = Src->global_begin(), 565 E = Src->global_end(); I != E; ++I) { 566 const GlobalVariable *SGV = I; 567 GlobalValue *DGV = 0; 568 569 // Check to see if may have to link the global with the global, alias or 570 // function. 571 if (SGV->hasName() && !SGV->hasLocalLinkage()) 572 DGV = cast_or_null<GlobalValue>(DestSymTab.lookup(SGV->getName())); 573 574 // If we found a global with the same name in the dest module, but it has 575 // internal linkage, we are really not doing any linkage here. 576 if (DGV && DGV->hasLocalLinkage()) 577 DGV = 0; 578 579 // If types don't agree due to opaque types, try to resolve them. 580 if (DGV && DGV->getType() != SGV->getType()) 581 RecursiveResolveTypes(SGV->getType(), DGV->getType()); 582 583 assert((SGV->hasInitializer() || SGV->hasExternalWeakLinkage() || 584 SGV->hasExternalLinkage() || SGV->hasDLLImportLinkage()) && 585 "Global must either be external or have an initializer!"); 586 587 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 588 bool LinkFromSrc = false; 589 if (GetLinkageResult(DGV, SGV, NewLinkage, LinkFromSrc, Err)) 590 return true; 591 592 if (DGV == 0) { 593 // No linking to be performed, simply create an identical version of the 594 // symbol over in the dest module... the initializer will be filled in 595 // later by LinkGlobalInits. 596 GlobalVariable *NewDGV = 597 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 598 SGV->isConstant(), SGV->getLinkage(), /*init*/0, 599 SGV->getName(), 0, false, 600 SGV->getType()->getAddressSpace()); 601 // Propagate alignment, visibility and section info. 602 CopyGVAttributes(NewDGV, SGV); 603 604 // If the LLVM runtime renamed the global, but it is an externally visible 605 // symbol, DGV must be an existing global with internal linkage. Rename 606 // it. 607 if (!NewDGV->hasLocalLinkage() && NewDGV->getName() != SGV->getName()) 608 ForceRenaming(NewDGV, SGV->getName()); 609 610 // Make sure to remember this mapping. 611 ValueMap[SGV] = NewDGV; 612 613 // Keep track that this is an appending variable. 614 if (SGV->hasAppendingLinkage()) 615 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV)); 616 continue; 617 } 618 619 // If the visibilities of the symbols disagree and the destination is a 620 // prototype, take the visibility of its input. 621 if (DGV->isDeclaration()) 622 DGV->setVisibility(SGV->getVisibility()); 623 624 if (DGV->hasAppendingLinkage()) { 625 // No linking is performed yet. Just insert a new copy of the global, and 626 // keep track of the fact that it is an appending variable in the 627 // AppendingVars map. The name is cleared out so that no linkage is 628 // performed. 629 GlobalVariable *NewDGV = 630 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 631 SGV->isConstant(), SGV->getLinkage(), /*init*/0, 632 "", 0, false, 633 SGV->getType()->getAddressSpace()); 634 635 // Set alignment allowing CopyGVAttributes merge it with alignment of SGV. 636 NewDGV->setAlignment(DGV->getAlignment()); 637 // Propagate alignment, section and visibility info. 638 CopyGVAttributes(NewDGV, SGV); 639 640 // Make sure to remember this mapping... 641 ValueMap[SGV] = NewDGV; 642 643 // Keep track that this is an appending variable... 644 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV)); 645 continue; 646 } 647 648 if (LinkFromSrc) { 649 if (isa<GlobalAlias>(DGV)) 650 return Error(Err, "Global-Alias Collision on '" + SGV->getName() + 651 "': symbol multiple defined"); 652 653 // If the types don't match, and if we are to link from the source, nuke 654 // DGV and create a new one of the appropriate type. Note that the thing 655 // we are replacing may be a function (if a prototype, weak, etc) or a 656 // global variable. 657 GlobalVariable *NewDGV = 658 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 659 SGV->isConstant(), NewLinkage, /*init*/0, 660 DGV->getName(), 0, false, 661 SGV->getType()->getAddressSpace()); 662 663 // Propagate alignment, section, and visibility info. 664 CopyGVAttributes(NewDGV, SGV); 665 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV, 666 DGV->getType())); 667 668 // DGV will conflict with NewDGV because they both had the same 669 // name. We must erase this now so ForceRenaming doesn't assert 670 // because DGV might not have internal linkage. 671 if (GlobalVariable *Var = dyn_cast<GlobalVariable>(DGV)) 672 Var->eraseFromParent(); 673 else 674 cast<Function>(DGV)->eraseFromParent(); 675 676 // If the symbol table renamed the global, but it is an externally visible 677 // symbol, DGV must be an existing global with internal linkage. Rename. 678 if (NewDGV->getName() != SGV->getName() && !NewDGV->hasLocalLinkage()) 679 ForceRenaming(NewDGV, SGV->getName()); 680 681 // Inherit const as appropriate. 682 NewDGV->setConstant(SGV->isConstant()); 683 684 // Make sure to remember this mapping. 685 ValueMap[SGV] = NewDGV; 686 continue; 687 } 688 689 // Not "link from source", keep the one in the DestModule and remap the 690 // input onto it. 691 692 // Special case for const propagation. 693 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) 694 if (DGVar->isDeclaration() && SGV->isConstant() && !DGVar->isConstant()) 695 DGVar->setConstant(true); 696 697 // SGV is global, but DGV is alias. 698 if (isa<GlobalAlias>(DGV)) { 699 // The only valid mappings are: 700 // - SGV is external declaration, which is effectively a no-op. 701 // - SGV is weak, when we just need to throw SGV out. 702 if (!SGV->isDeclaration() && !SGV->isWeakForLinker()) 703 return Error(Err, "Global-Alias Collision on '" + SGV->getName() + 704 "': symbol multiple defined"); 705 } 706 707 // Set calculated linkage 708 DGV->setLinkage(NewLinkage); 709 710 // Make sure to remember this mapping... 711 ValueMap[SGV] = ConstantExpr::getBitCast(DGV, SGV->getType()); 712 } 713 return false; 714} 715 716static GlobalValue::LinkageTypes 717CalculateAliasLinkage(const GlobalValue *SGV, const GlobalValue *DGV) { 718 GlobalValue::LinkageTypes SL = SGV->getLinkage(); 719 GlobalValue::LinkageTypes DL = DGV->getLinkage(); 720 if (SL == GlobalValue::ExternalLinkage || DL == GlobalValue::ExternalLinkage) 721 return GlobalValue::ExternalLinkage; 722 else if (SL == GlobalValue::WeakAnyLinkage || 723 DL == GlobalValue::WeakAnyLinkage) 724 return GlobalValue::WeakAnyLinkage; 725 else if (SL == GlobalValue::WeakODRLinkage || 726 DL == GlobalValue::WeakODRLinkage) 727 return GlobalValue::WeakODRLinkage; 728 else if (SL == GlobalValue::InternalLinkage && 729 DL == GlobalValue::InternalLinkage) 730 return GlobalValue::InternalLinkage; 731 else if (SL == GlobalValue::LinkerPrivateLinkage && 732 DL == GlobalValue::LinkerPrivateLinkage) 733 return GlobalValue::LinkerPrivateLinkage; 734 else { 735 assert (SL == GlobalValue::PrivateLinkage && 736 DL == GlobalValue::PrivateLinkage && "Unexpected linkage type"); 737 return GlobalValue::PrivateLinkage; 738 } 739} 740 741// LinkAlias - Loop through the alias in the src module and link them into the 742// dest module. We're assuming, that all functions/global variables were already 743// linked in. 744static bool LinkAlias(Module *Dest, const Module *Src, 745 std::map<const Value*, Value*> &ValueMap, 746 std::string *Err) { 747 // Loop over all alias in the src module 748 for (Module::const_alias_iterator I = Src->alias_begin(), 749 E = Src->alias_end(); I != E; ++I) { 750 const GlobalAlias *SGA = I; 751 const GlobalValue *SAliasee = SGA->getAliasedGlobal(); 752 GlobalAlias *NewGA = NULL; 753 754 // Globals were already linked, thus we can just query ValueMap for variant 755 // of SAliasee in Dest. 756 std::map<const Value*,Value*>::const_iterator VMI = ValueMap.find(SAliasee); 757 assert(VMI != ValueMap.end() && "Aliasee not linked"); 758 GlobalValue* DAliasee = cast<GlobalValue>(VMI->second); 759 GlobalValue* DGV = NULL; 760 761 // Try to find something 'similar' to SGA in destination module. 762 if (!DGV && !SGA->hasLocalLinkage()) { 763 DGV = Dest->getNamedAlias(SGA->getName()); 764 765 // If types don't agree due to opaque types, try to resolve them. 766 if (DGV && DGV->getType() != SGA->getType()) 767 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 768 } 769 770 if (!DGV && !SGA->hasLocalLinkage()) { 771 DGV = Dest->getGlobalVariable(SGA->getName()); 772 773 // If types don't agree due to opaque types, try to resolve them. 774 if (DGV && DGV->getType() != SGA->getType()) 775 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 776 } 777 778 if (!DGV && !SGA->hasLocalLinkage()) { 779 DGV = Dest->getFunction(SGA->getName()); 780 781 // If types don't agree due to opaque types, try to resolve them. 782 if (DGV && DGV->getType() != SGA->getType()) 783 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 784 } 785 786 // No linking to be performed on internal stuff. 787 if (DGV && DGV->hasLocalLinkage()) 788 DGV = NULL; 789 790 if (GlobalAlias *DGA = dyn_cast_or_null<GlobalAlias>(DGV)) { 791 // Types are known to be the same, check whether aliasees equal. As 792 // globals are already linked we just need query ValueMap to find the 793 // mapping. 794 if (DAliasee == DGA->getAliasedGlobal()) { 795 // This is just two copies of the same alias. Propagate linkage, if 796 // necessary. 797 DGA->setLinkage(CalculateAliasLinkage(SGA, DGA)); 798 799 NewGA = DGA; 800 // Proceed to 'common' steps 801 } else 802 return Error(Err, "Alias Collision on '" + SGA->getName()+ 803 "': aliases have different aliasees"); 804 } else if (GlobalVariable *DGVar = dyn_cast_or_null<GlobalVariable>(DGV)) { 805 // The only allowed way is to link alias with external declaration or weak 806 // symbol.. 807 if (DGVar->isDeclaration() || DGVar->isWeakForLinker()) { 808 // But only if aliasee is global too... 809 if (!isa<GlobalVariable>(DAliasee)) 810 return Error(Err, "Global-Alias Collision on '" + SGA->getName() + 811 "': aliasee is not global variable"); 812 813 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 814 SGA->getName(), DAliasee, Dest); 815 CopyGVAttributes(NewGA, SGA); 816 817 // Any uses of DGV need to change to NewGA, with cast, if needed. 818 if (SGA->getType() != DGVar->getType()) 819 DGVar->replaceAllUsesWith(ConstantExpr::getBitCast(NewGA, 820 DGVar->getType())); 821 else 822 DGVar->replaceAllUsesWith(NewGA); 823 824 // DGVar will conflict with NewGA because they both had the same 825 // name. We must erase this now so ForceRenaming doesn't assert 826 // because DGV might not have internal linkage. 827 DGVar->eraseFromParent(); 828 829 // Proceed to 'common' steps 830 } else 831 return Error(Err, "Global-Alias Collision on '" + SGA->getName() + 832 "': symbol multiple defined"); 833 } else if (Function *DF = dyn_cast_or_null<Function>(DGV)) { 834 // The only allowed way is to link alias with external declaration or weak 835 // symbol... 836 if (DF->isDeclaration() || DF->isWeakForLinker()) { 837 // But only if aliasee is function too... 838 if (!isa<Function>(DAliasee)) 839 return Error(Err, "Function-Alias Collision on '" + SGA->getName() + 840 "': aliasee is not function"); 841 842 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 843 SGA->getName(), DAliasee, Dest); 844 CopyGVAttributes(NewGA, SGA); 845 846 // Any uses of DF need to change to NewGA, with cast, if needed. 847 if (SGA->getType() != DF->getType()) 848 DF->replaceAllUsesWith(ConstantExpr::getBitCast(NewGA, 849 DF->getType())); 850 else 851 DF->replaceAllUsesWith(NewGA); 852 853 // DF will conflict with NewGA because they both had the same 854 // name. We must erase this now so ForceRenaming doesn't assert 855 // because DF might not have internal linkage. 856 DF->eraseFromParent(); 857 858 // Proceed to 'common' steps 859 } else 860 return Error(Err, "Function-Alias Collision on '" + SGA->getName() + 861 "': symbol multiple defined"); 862 } else { 863 // No linking to be performed, simply create an identical version of the 864 // alias over in the dest module... 865 Constant *Aliasee = DAliasee; 866 // Fixup aliases to bitcasts. Note that aliases to GEPs are still broken 867 // by this, but aliases to GEPs are broken to a lot of other things, so 868 // it's less important. 869 if (SGA->getType() != DAliasee->getType()) 870 Aliasee = ConstantExpr::getBitCast(DAliasee, SGA->getType()); 871 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 872 SGA->getName(), Aliasee, Dest); 873 CopyGVAttributes(NewGA, SGA); 874 875 // Proceed to 'common' steps 876 } 877 878 assert(NewGA && "No alias was created in destination module!"); 879 880 // If the symbol table renamed the alias, but it is an externally visible 881 // symbol, DGA must be an global value with internal linkage. Rename it. 882 if (NewGA->getName() != SGA->getName() && 883 !NewGA->hasLocalLinkage()) 884 ForceRenaming(NewGA, SGA->getName()); 885 886 // Remember this mapping so uses in the source module get remapped 887 // later by RemapOperand. 888 ValueMap[SGA] = NewGA; 889 } 890 891 return false; 892} 893 894 895// LinkGlobalInits - Update the initializers in the Dest module now that all 896// globals that may be referenced are in Dest. 897static bool LinkGlobalInits(Module *Dest, const Module *Src, 898 std::map<const Value*, Value*> &ValueMap, 899 std::string *Err) { 900 // Loop over all of the globals in the src module, mapping them over as we go 901 for (Module::const_global_iterator I = Src->global_begin(), 902 E = Src->global_end(); I != E; ++I) { 903 const GlobalVariable *SGV = I; 904 905 if (SGV->hasInitializer()) { // Only process initialized GV's 906 // Figure out what the initializer looks like in the dest module... 907 Constant *SInit = 908 cast<Constant>(RemapOperand(SGV->getInitializer(), ValueMap)); 909 // Grab destination global variable or alias. 910 GlobalValue *DGV = cast<GlobalValue>(ValueMap[SGV]->stripPointerCasts()); 911 912 // If dest if global variable, check that initializers match. 913 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) { 914 if (DGVar->hasInitializer()) { 915 if (SGV->hasExternalLinkage()) { 916 if (DGVar->getInitializer() != SInit) 917 return Error(Err, "Global Variable Collision on '" + 918 SGV->getName() + 919 "': global variables have different initializers"); 920 } else if (DGVar->isWeakForLinker()) { 921 // Nothing is required, mapped values will take the new global 922 // automatically. 923 } else if (SGV->isWeakForLinker()) { 924 // Nothing is required, mapped values will take the new global 925 // automatically. 926 } else if (DGVar->hasAppendingLinkage()) { 927 llvm_unreachable("Appending linkage unimplemented!"); 928 } else { 929 llvm_unreachable("Unknown linkage!"); 930 } 931 } else { 932 // Copy the initializer over now... 933 DGVar->setInitializer(SInit); 934 } 935 } else { 936 // Destination is alias, the only valid situation is when source is 937 // weak. Also, note, that we already checked linkage in LinkGlobals(), 938 // thus we assert here. 939 // FIXME: Should we weaken this assumption, 'dereference' alias and 940 // check for initializer of aliasee? 941 assert(SGV->isWeakForLinker()); 942 } 943 } 944 } 945 return false; 946} 947 948// LinkFunctionProtos - Link the functions together between the two modules, 949// without doing function bodies... this just adds external function prototypes 950// to the Dest function... 951// 952static bool LinkFunctionProtos(Module *Dest, const Module *Src, 953 std::map<const Value*, Value*> &ValueMap, 954 std::string *Err) { 955 ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable(); 956 957 // Loop over all of the functions in the src module, mapping them over 958 for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) { 959 const Function *SF = I; // SrcFunction 960 GlobalValue *DGV = 0; 961 962 // Check to see if may have to link the function with the global, alias or 963 // function. 964 if (SF->hasName() && !SF->hasLocalLinkage()) 965 DGV = cast_or_null<GlobalValue>(DestSymTab.lookup(SF->getName())); 966 967 // If we found a global with the same name in the dest module, but it has 968 // internal linkage, we are really not doing any linkage here. 969 if (DGV && DGV->hasLocalLinkage()) 970 DGV = 0; 971 972 // If types don't agree due to opaque types, try to resolve them. 973 if (DGV && DGV->getType() != SF->getType()) 974 RecursiveResolveTypes(SF->getType(), DGV->getType()); 975 976 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 977 bool LinkFromSrc = false; 978 if (GetLinkageResult(DGV, SF, NewLinkage, LinkFromSrc, Err)) 979 return true; 980 981 // If there is no linkage to be performed, just bring over SF without 982 // modifying it. 983 if (DGV == 0) { 984 // Function does not already exist, simply insert an function signature 985 // identical to SF into the dest module. 986 Function *NewDF = Function::Create(SF->getFunctionType(), 987 SF->getLinkage(), 988 SF->getName(), Dest); 989 CopyGVAttributes(NewDF, SF); 990 991 // If the LLVM runtime renamed the function, but it is an externally 992 // visible symbol, DF must be an existing function with internal linkage. 993 // Rename it. 994 if (!NewDF->hasLocalLinkage() && NewDF->getName() != SF->getName()) 995 ForceRenaming(NewDF, SF->getName()); 996 997 // ... and remember this mapping... 998 ValueMap[SF] = NewDF; 999 continue; 1000 } 1001 1002 // If the visibilities of the symbols disagree and the destination is a 1003 // prototype, take the visibility of its input. 1004 if (DGV->isDeclaration()) 1005 DGV->setVisibility(SF->getVisibility()); 1006 1007 if (LinkFromSrc) { 1008 if (isa<GlobalAlias>(DGV)) 1009 return Error(Err, "Function-Alias Collision on '" + SF->getName() + 1010 "': symbol multiple defined"); 1011 1012 // We have a definition of the same name but different type in the 1013 // source module. Copy the prototype to the destination and replace 1014 // uses of the destination's prototype with the new prototype. 1015 Function *NewDF = Function::Create(SF->getFunctionType(), NewLinkage, 1016 SF->getName(), Dest); 1017 CopyGVAttributes(NewDF, SF); 1018 1019 // Any uses of DF need to change to NewDF, with cast 1020 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, 1021 DGV->getType())); 1022 1023 // DF will conflict with NewDF because they both had the same. We must 1024 // erase this now so ForceRenaming doesn't assert because DF might 1025 // not have internal linkage. 1026 if (GlobalVariable *Var = dyn_cast<GlobalVariable>(DGV)) 1027 Var->eraseFromParent(); 1028 else 1029 cast<Function>(DGV)->eraseFromParent(); 1030 1031 // If the symbol table renamed the function, but it is an externally 1032 // visible symbol, DF must be an existing function with internal 1033 // linkage. Rename it. 1034 if (NewDF->getName() != SF->getName() && !NewDF->hasLocalLinkage()) 1035 ForceRenaming(NewDF, SF->getName()); 1036 1037 // Remember this mapping so uses in the source module get remapped 1038 // later by RemapOperand. 1039 ValueMap[SF] = NewDF; 1040 continue; 1041 } 1042 1043 // Not "link from source", keep the one in the DestModule and remap the 1044 // input onto it. 1045 1046 if (isa<GlobalAlias>(DGV)) { 1047 // The only valid mappings are: 1048 // - SF is external declaration, which is effectively a no-op. 1049 // - SF is weak, when we just need to throw SF out. 1050 if (!SF->isDeclaration() && !SF->isWeakForLinker()) 1051 return Error(Err, "Function-Alias Collision on '" + SF->getName() + 1052 "': symbol multiple defined"); 1053 } 1054 1055 // Set calculated linkage 1056 DGV->setLinkage(NewLinkage); 1057 1058 // Make sure to remember this mapping. 1059 ValueMap[SF] = ConstantExpr::getBitCast(DGV, SF->getType()); 1060 } 1061 return false; 1062} 1063 1064// LinkFunctionBody - Copy the source function over into the dest function and 1065// fix up references to values. At this point we know that Dest is an external 1066// function, and that Src is not. 1067static bool LinkFunctionBody(Function *Dest, Function *Src, 1068 std::map<const Value*, Value*> &ValueMap, 1069 std::string *Err) { 1070 assert(Src && Dest && Dest->isDeclaration() && !Src->isDeclaration()); 1071 1072 // Go through and convert function arguments over, remembering the mapping. 1073 Function::arg_iterator DI = Dest->arg_begin(); 1074 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 1075 I != E; ++I, ++DI) { 1076 DI->setName(I->getName()); // Copy the name information over... 1077 1078 // Add a mapping to our local map 1079 ValueMap[I] = DI; 1080 } 1081 1082 // Splice the body of the source function into the dest function. 1083 Dest->getBasicBlockList().splice(Dest->end(), Src->getBasicBlockList()); 1084 1085 // At this point, all of the instructions and values of the function are now 1086 // copied over. The only problem is that they are still referencing values in 1087 // the Source function as operands. Loop through all of the operands of the 1088 // functions and patch them up to point to the local versions... 1089 // 1090 for (Function::iterator BB = Dest->begin(), BE = Dest->end(); BB != BE; ++BB) 1091 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) 1092 for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end(); 1093 OI != OE; ++OI) 1094 if (!isa<Instruction>(*OI) && !isa<BasicBlock>(*OI)) 1095 *OI = RemapOperand(*OI, ValueMap); 1096 1097 // There is no need to map the arguments anymore. 1098 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 1099 I != E; ++I) 1100 ValueMap.erase(I); 1101 1102 return false; 1103} 1104 1105 1106// LinkFunctionBodies - Link in the function bodies that are defined in the 1107// source module into the DestModule. This consists basically of copying the 1108// function over and fixing up references to values. 1109static bool LinkFunctionBodies(Module *Dest, Module *Src, 1110 std::map<const Value*, Value*> &ValueMap, 1111 std::string *Err) { 1112 1113 // Loop over all of the functions in the src module, mapping them over as we 1114 // go 1115 for (Module::iterator SF = Src->begin(), E = Src->end(); SF != E; ++SF) { 1116 if (!SF->isDeclaration()) { // No body if function is external 1117 Function *DF = dyn_cast<Function>(ValueMap[SF]); // Destination function 1118 1119 // DF not external SF external? 1120 if (DF && DF->isDeclaration()) 1121 // Only provide the function body if there isn't one already. 1122 if (LinkFunctionBody(DF, SF, ValueMap, Err)) 1123 return true; 1124 } 1125 } 1126 return false; 1127} 1128 1129// LinkAppendingVars - If there were any appending global variables, link them 1130// together now. Return true on error. 1131static bool LinkAppendingVars(Module *M, 1132 std::multimap<std::string, GlobalVariable *> &AppendingVars, 1133 std::string *ErrorMsg) { 1134 if (AppendingVars.empty()) return false; // Nothing to do. 1135 1136 // Loop over the multimap of appending vars, processing any variables with the 1137 // same name, forming a new appending global variable with both of the 1138 // initializers merged together, then rewrite references to the old variables 1139 // and delete them. 1140 std::vector<Constant*> Inits; 1141 while (AppendingVars.size() > 1) { 1142 // Get the first two elements in the map... 1143 std::multimap<std::string, 1144 GlobalVariable*>::iterator Second = AppendingVars.begin(), First=Second++; 1145 1146 // If the first two elements are for different names, there is no pair... 1147 // Otherwise there is a pair, so link them together... 1148 if (First->first == Second->first) { 1149 GlobalVariable *G1 = First->second, *G2 = Second->second; 1150 const ArrayType *T1 = cast<ArrayType>(G1->getType()->getElementType()); 1151 const ArrayType *T2 = cast<ArrayType>(G2->getType()->getElementType()); 1152 1153 // Check to see that they two arrays agree on type... 1154 if (T1->getElementType() != T2->getElementType()) 1155 return Error(ErrorMsg, 1156 "Appending variables with different element types need to be linked!"); 1157 if (G1->isConstant() != G2->isConstant()) 1158 return Error(ErrorMsg, 1159 "Appending variables linked with different const'ness!"); 1160 1161 if (G1->getAlignment() != G2->getAlignment()) 1162 return Error(ErrorMsg, 1163 "Appending variables with different alignment need to be linked!"); 1164 1165 if (G1->getVisibility() != G2->getVisibility()) 1166 return Error(ErrorMsg, 1167 "Appending variables with different visibility need to be linked!"); 1168 1169 if (G1->getSection() != G2->getSection()) 1170 return Error(ErrorMsg, 1171 "Appending variables with different section name need to be linked!"); 1172 1173 unsigned NewSize = T1->getNumElements() + T2->getNumElements(); 1174 ArrayType *NewType = ArrayType::get(T1->getElementType(), 1175 NewSize); 1176 1177 G1->setName(""); // Clear G1's name in case of a conflict! 1178 1179 // Create the new global variable... 1180 GlobalVariable *NG = 1181 new GlobalVariable(*M, NewType, G1->isConstant(), G1->getLinkage(), 1182 /*init*/0, First->first, 0, G1->isThreadLocal(), 1183 G1->getType()->getAddressSpace()); 1184 1185 // Propagate alignment, visibility and section info. 1186 CopyGVAttributes(NG, G1); 1187 1188 // Merge the initializer... 1189 Inits.reserve(NewSize); 1190 if (ConstantArray *I = dyn_cast<ConstantArray>(G1->getInitializer())) { 1191 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i) 1192 Inits.push_back(I->getOperand(i)); 1193 } else { 1194 assert(isa<ConstantAggregateZero>(G1->getInitializer())); 1195 Constant *CV = Constant::getNullValue(T1->getElementType()); 1196 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i) 1197 Inits.push_back(CV); 1198 } 1199 if (ConstantArray *I = dyn_cast<ConstantArray>(G2->getInitializer())) { 1200 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i) 1201 Inits.push_back(I->getOperand(i)); 1202 } else { 1203 assert(isa<ConstantAggregateZero>(G2->getInitializer())); 1204 Constant *CV = Constant::getNullValue(T2->getElementType()); 1205 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i) 1206 Inits.push_back(CV); 1207 } 1208 NG->setInitializer(ConstantArray::get(NewType, Inits)); 1209 Inits.clear(); 1210 1211 // Replace any uses of the two global variables with uses of the new 1212 // global... 1213 1214 // FIXME: This should rewrite simple/straight-forward uses such as 1215 // getelementptr instructions to not use the Cast! 1216 G1->replaceAllUsesWith(ConstantExpr::getBitCast(NG, 1217 G1->getType())); 1218 G2->replaceAllUsesWith(ConstantExpr::getBitCast(NG, 1219 G2->getType())); 1220 1221 // Remove the two globals from the module now... 1222 M->getGlobalList().erase(G1); 1223 M->getGlobalList().erase(G2); 1224 1225 // Put the new global into the AppendingVars map so that we can handle 1226 // linking of more than two vars... 1227 Second->second = NG; 1228 } 1229 AppendingVars.erase(First); 1230 } 1231 1232 return false; 1233} 1234 1235static bool ResolveAliases(Module *Dest) { 1236 for (Module::alias_iterator I = Dest->alias_begin(), E = Dest->alias_end(); 1237 I != E; ++I) 1238 // We can't sue resolveGlobalAlias here because we need to preserve 1239 // bitcasts and GEPs. 1240 if (const Constant *C = I->getAliasee()) { 1241 while (dyn_cast<GlobalAlias>(C)) 1242 C = cast<GlobalAlias>(C)->getAliasee(); 1243 const GlobalValue *GV = dyn_cast<GlobalValue>(C); 1244 if (C != I && !(GV && GV->isDeclaration())) 1245 I->replaceAllUsesWith(const_cast<Constant*>(C)); 1246 } 1247 1248 return false; 1249} 1250 1251// LinkModules - This function links two modules together, with the resulting 1252// left module modified to be the composite of the two input modules. If an 1253// error occurs, true is returned and ErrorMsg (if not null) is set to indicate 1254// the problem. Upon failure, the Dest module could be in a modified state, and 1255// shouldn't be relied on to be consistent. 1256bool 1257Linker::LinkModules(Module *Dest, Module *Src, std::string *ErrorMsg) { 1258 assert(Dest != 0 && "Invalid Destination module"); 1259 assert(Src != 0 && "Invalid Source Module"); 1260 1261 if (Dest->getDataLayout().empty()) { 1262 if (!Src->getDataLayout().empty()) { 1263 Dest->setDataLayout(Src->getDataLayout()); 1264 } else { 1265 std::string DataLayout; 1266 1267 if (Dest->getEndianness() == Module::AnyEndianness) { 1268 if (Src->getEndianness() == Module::BigEndian) 1269 DataLayout.append("E"); 1270 else if (Src->getEndianness() == Module::LittleEndian) 1271 DataLayout.append("e"); 1272 } 1273 1274 if (Dest->getPointerSize() == Module::AnyPointerSize) { 1275 if (Src->getPointerSize() == Module::Pointer64) 1276 DataLayout.append(DataLayout.length() == 0 ? "p:64:64" : "-p:64:64"); 1277 else if (Src->getPointerSize() == Module::Pointer32) 1278 DataLayout.append(DataLayout.length() == 0 ? "p:32:32" : "-p:32:32"); 1279 } 1280 Dest->setDataLayout(DataLayout); 1281 } 1282 } 1283 1284 // Copy the target triple from the source to dest if the dest's is empty. 1285 if (Dest->getTargetTriple().empty() && !Src->getTargetTriple().empty()) 1286 Dest->setTargetTriple(Src->getTargetTriple()); 1287 1288 if (!Src->getDataLayout().empty() && !Dest->getDataLayout().empty() && 1289 Src->getDataLayout() != Dest->getDataLayout()) 1290 errs() << "WARNING: Linking two modules of different data layouts!\n"; 1291 if (!Src->getTargetTriple().empty() && 1292 Dest->getTargetTriple() != Src->getTargetTriple()) 1293 errs() << "WARNING: Linking two modules of different target triples!\n"; 1294 1295 // Append the module inline asm string. 1296 if (!Src->getModuleInlineAsm().empty()) { 1297 if (Dest->getModuleInlineAsm().empty()) 1298 Dest->setModuleInlineAsm(Src->getModuleInlineAsm()); 1299 else 1300 Dest->setModuleInlineAsm(Dest->getModuleInlineAsm()+"\n"+ 1301 Src->getModuleInlineAsm()); 1302 } 1303 1304 // Update the destination module's dependent libraries list with the libraries 1305 // from the source module. There's no opportunity for duplicates here as the 1306 // Module ensures that duplicate insertions are discarded. 1307 for (Module::lib_iterator SI = Src->lib_begin(), SE = Src->lib_end(); 1308 SI != SE; ++SI) 1309 Dest->addLibrary(*SI); 1310 1311 // LinkTypes - Go through the symbol table of the Src module and see if any 1312 // types are named in the src module that are not named in the Dst module. 1313 // Make sure there are no type name conflicts. 1314 if (LinkTypes(Dest, Src, ErrorMsg)) 1315 return true; 1316 1317 // ValueMap - Mapping of values from what they used to be in Src, to what they 1318 // are now in Dest. 1319 std::map<const Value*, Value*> ValueMap; 1320 1321 // AppendingVars - Keep track of global variables in the destination module 1322 // with appending linkage. After the module is linked together, they are 1323 // appended and the module is rewritten. 1324 std::multimap<std::string, GlobalVariable *> AppendingVars; 1325 for (Module::global_iterator I = Dest->global_begin(), E = Dest->global_end(); 1326 I != E; ++I) { 1327 // Add all of the appending globals already in the Dest module to 1328 // AppendingVars. 1329 if (I->hasAppendingLinkage()) 1330 AppendingVars.insert(std::make_pair(I->getName(), I)); 1331 } 1332 1333 // Insert all of the named mdnoes in Src into the Dest module. 1334 LinkNamedMDNodes(Dest, Src); 1335 1336 // Insert all of the globals in src into the Dest module... without linking 1337 // initializers (which could refer to functions not yet mapped over). 1338 if (LinkGlobals(Dest, Src, ValueMap, AppendingVars, ErrorMsg)) 1339 return true; 1340 1341 // Link the functions together between the two modules, without doing function 1342 // bodies... this just adds external function prototypes to the Dest 1343 // function... We do this so that when we begin processing function bodies, 1344 // all of the global values that may be referenced are available in our 1345 // ValueMap. 1346 if (LinkFunctionProtos(Dest, Src, ValueMap, ErrorMsg)) 1347 return true; 1348 1349 // If there were any alias, link them now. We really need to do this now, 1350 // because all of the aliases that may be referenced need to be available in 1351 // ValueMap 1352 if (LinkAlias(Dest, Src, ValueMap, ErrorMsg)) return true; 1353 1354 // Update the initializers in the Dest module now that all globals that may 1355 // be referenced are in Dest. 1356 if (LinkGlobalInits(Dest, Src, ValueMap, ErrorMsg)) return true; 1357 1358 // Link in the function bodies that are defined in the source module into the 1359 // DestModule. This consists basically of copying the function over and 1360 // fixing up references to values. 1361 if (LinkFunctionBodies(Dest, Src, ValueMap, ErrorMsg)) return true; 1362 1363 // If there were any appending global variables, link them together now. 1364 if (LinkAppendingVars(Dest, AppendingVars, ErrorMsg)) return true; 1365 1366 // Resolve all uses of aliases with aliasees 1367 if (ResolveAliases(Dest)) return true; 1368 1369 // If the source library's module id is in the dependent library list of the 1370 // destination library, remove it since that module is now linked in. 1371 sys::Path modId; 1372 modId.set(Src->getModuleIdentifier()); 1373 if (!modId.isEmpty()) 1374 Dest->removeLibrary(modId.getBasename()); 1375 1376 return false; 1377} 1378 1379// vim: sw=2 1380