LinkModules.cpp revision 74382b7c699120fbec5cb5603c9cf4212eb37f06
1//===- lib/Linker/LinkModules.cpp - Module Linker Implementation ----------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file implements the LLVM module linker. 11// 12// Specifically, this: 13// * Merges global variables between the two modules 14// * Uninit + Uninit = Init, Init + Uninit = Init, Init + Init = Error if != 15// * Merges functions between two modules 16// 17//===----------------------------------------------------------------------===// 18 19#include "llvm/Linker.h" 20#include "llvm/Constants.h" 21#include "llvm/DerivedTypes.h" 22#include "llvm/LLVMContext.h" 23#include "llvm/Module.h" 24#include "llvm/TypeSymbolTable.h" 25#include "llvm/ValueSymbolTable.h" 26#include "llvm/Instructions.h" 27#include "llvm/Assembly/Writer.h" 28#include "llvm/Support/ErrorHandling.h" 29#include "llvm/Support/raw_ostream.h" 30#include "llvm/System/Path.h" 31#include "llvm/ADT/DenseMap.h" 32#include <sstream> 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 errs() << "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 errs() << " Fr: " << (void*)I->first << " "; 342 I->first->dump(); 343 errs() << " To: " << (void*)I->second << " "; 344 I->second->dump(); 345 errs() << "\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 LLVMContext &Context) { 355 std::map<const Value*,Value*>::const_iterator I = ValueMap.find(In); 356 if (I != ValueMap.end()) 357 return I->second; 358 359 // Check to see if it's a constant that we are interested in transforming. 360 Value *Result = 0; 361 if (const Constant *CPV = dyn_cast<Constant>(In)) { 362 if ((!isa<DerivedType>(CPV->getType()) && !isa<ConstantExpr>(CPV)) || 363 isa<ConstantInt>(CPV) || isa<ConstantAggregateZero>(CPV)) 364 return const_cast<Constant*>(CPV); // Simple constants stay identical. 365 366 if (const ConstantArray *CPA = dyn_cast<ConstantArray>(CPV)) { 367 std::vector<Constant*> Operands(CPA->getNumOperands()); 368 for (unsigned i = 0, e = CPA->getNumOperands(); i != e; ++i) 369 Operands[i] =cast<Constant>(RemapOperand(CPA->getOperand(i), ValueMap, 370 Context)); 371 Result = 372 ConstantArray::get(cast<ArrayType>(CPA->getType()), Operands); 373 } else if (const ConstantStruct *CPS = dyn_cast<ConstantStruct>(CPV)) { 374 std::vector<Constant*> Operands(CPS->getNumOperands()); 375 for (unsigned i = 0, e = CPS->getNumOperands(); i != e; ++i) 376 Operands[i] =cast<Constant>(RemapOperand(CPS->getOperand(i), ValueMap, 377 Context)); 378 Result = 379 ConstantStruct::get(cast<StructType>(CPS->getType()), Operands); 380 } else if (isa<ConstantPointerNull>(CPV) || isa<UndefValue>(CPV)) { 381 Result = const_cast<Constant*>(CPV); 382 } else if (const ConstantVector *CP = dyn_cast<ConstantVector>(CPV)) { 383 std::vector<Constant*> Operands(CP->getNumOperands()); 384 for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i) 385 Operands[i] = cast<Constant>(RemapOperand(CP->getOperand(i), ValueMap, 386 Context)); 387 Result = ConstantVector::get(Operands); 388 } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CPV)) { 389 std::vector<Constant*> Ops; 390 for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) 391 Ops.push_back(cast<Constant>(RemapOperand(CE->getOperand(i),ValueMap, 392 Context))); 393 Result = CE->getWithOperands(Ops); 394 } else { 395 assert(!isa<GlobalValue>(CPV) && "Unmapped global?"); 396 llvm_unreachable("Unknown type of derived type constant value!"); 397 } 398 } else if (const MDNode *N = dyn_cast<MDNode>(In)) { 399 std::vector<Value*> Elems; 400 for (unsigned i = 0, e = N->getNumElements(); i !=e; ++i) 401 Elems.push_back(RemapOperand(N->getElement(i), ValueMap, Context)); 402 if (!Elems.empty()) 403 Result = MDNode::get(Context, &Elems[0], Elems.size()); 404 } else if (const MDString *MDS = dyn_cast<MDString>(In)) { 405 Result = MDString::get(Context, MDS->getString()); 406 } else if (isa<InlineAsm>(In)) { 407 Result = const_cast<Value*>(In); 408 } 409 410 // Cache the mapping in our local map structure 411 if (Result) { 412 ValueMap[In] = Result; 413 return Result; 414 } 415 416#ifndef NDEBUG 417 errs() << "LinkModules ValueMap: \n"; 418 PrintMap(ValueMap); 419 420 errs() << "Couldn't remap value: " << (void*)In << " " << *In << "\n"; 421 llvm_unreachable("Couldn't remap value!"); 422#endif 423 return 0; 424} 425 426/// ForceRenaming - The LLVM SymbolTable class autorenames globals that conflict 427/// in the symbol table. This is good for all clients except for us. Go 428/// through the trouble to force this back. 429static void ForceRenaming(GlobalValue *GV, const std::string &Name) { 430 assert(GV->getName() != Name && "Can't force rename to self"); 431 ValueSymbolTable &ST = GV->getParent()->getValueSymbolTable(); 432 433 // If there is a conflict, rename the conflict. 434 if (GlobalValue *ConflictGV = cast_or_null<GlobalValue>(ST.lookup(Name))) { 435 assert(ConflictGV->hasLocalLinkage() && 436 "Not conflicting with a static global, should link instead!"); 437 GV->takeName(ConflictGV); 438 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed 439 assert(ConflictGV->getName() != Name && "ForceRenaming didn't work"); 440 } else { 441 GV->setName(Name); // Force the name back 442 } 443} 444 445/// CopyGVAttributes - copy additional attributes (those not needed to construct 446/// a GlobalValue) from the SrcGV to the DestGV. 447static void CopyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) { 448 // Use the maximum alignment, rather than just copying the alignment of SrcGV. 449 unsigned Alignment = std::max(DestGV->getAlignment(), SrcGV->getAlignment()); 450 DestGV->copyAttributesFrom(SrcGV); 451 DestGV->setAlignment(Alignment); 452} 453 454/// GetLinkageResult - This analyzes the two global values and determines what 455/// the result will look like in the destination module. In particular, it 456/// computes the resultant linkage type, computes whether the global in the 457/// source should be copied over to the destination (replacing the existing 458/// one), and computes whether this linkage is an error or not. It also performs 459/// visibility checks: we cannot link together two symbols with different 460/// visibilities. 461static bool GetLinkageResult(GlobalValue *Dest, const GlobalValue *Src, 462 GlobalValue::LinkageTypes <, bool &LinkFromSrc, 463 std::string *Err) { 464 assert((!Dest || !Src->hasLocalLinkage()) && 465 "If Src has internal linkage, Dest shouldn't be set!"); 466 if (!Dest) { 467 // Linking something to nothing. 468 LinkFromSrc = true; 469 LT = Src->getLinkage(); 470 } else if (Src->isDeclaration()) { 471 // If Src is external or if both Src & Dest are external.. Just link the 472 // external globals, we aren't adding anything. 473 if (Src->hasDLLImportLinkage()) { 474 // If one of GVs has DLLImport linkage, result should be dllimport'ed. 475 if (Dest->isDeclaration()) { 476 LinkFromSrc = true; 477 LT = Src->getLinkage(); 478 } 479 } else if (Dest->hasExternalWeakLinkage()) { 480 // If the Dest is weak, use the source linkage. 481 LinkFromSrc = true; 482 LT = Src->getLinkage(); 483 } else { 484 LinkFromSrc = false; 485 LT = Dest->getLinkage(); 486 } 487 } else if (Dest->isDeclaration() && !Dest->hasDLLImportLinkage()) { 488 // If Dest is external but Src is not: 489 LinkFromSrc = true; 490 LT = Src->getLinkage(); 491 } else if (Src->hasAppendingLinkage() || Dest->hasAppendingLinkage()) { 492 if (Src->getLinkage() != Dest->getLinkage()) 493 return Error(Err, "Linking globals named '" + Src->getName() + 494 "': can only link appending global with another appending global!"); 495 LinkFromSrc = true; // Special cased. 496 LT = Src->getLinkage(); 497 } else if (Src->isWeakForLinker()) { 498 // At this point we know that Dest has LinkOnce, External*, Weak, Common, 499 // or DLL* linkage. 500 if (Dest->hasExternalWeakLinkage() || 501 Dest->hasAvailableExternallyLinkage() || 502 (Dest->hasLinkOnceLinkage() && 503 (Src->hasWeakLinkage() || Src->hasCommonLinkage()))) { 504 LinkFromSrc = true; 505 LT = Src->getLinkage(); 506 } else { 507 LinkFromSrc = false; 508 LT = Dest->getLinkage(); 509 } 510 } else if (Dest->isWeakForLinker()) { 511 // At this point we know that Src has External* or DLL* linkage. 512 if (Src->hasExternalWeakLinkage()) { 513 LinkFromSrc = false; 514 LT = Dest->getLinkage(); 515 } else { 516 LinkFromSrc = true; 517 LT = GlobalValue::ExternalLinkage; 518 } 519 } else { 520 assert((Dest->hasExternalLinkage() || 521 Dest->hasDLLImportLinkage() || 522 Dest->hasDLLExportLinkage() || 523 Dest->hasExternalWeakLinkage()) && 524 (Src->hasExternalLinkage() || 525 Src->hasDLLImportLinkage() || 526 Src->hasDLLExportLinkage() || 527 Src->hasExternalWeakLinkage()) && 528 "Unexpected linkage type!"); 529 return Error(Err, "Linking globals named '" + Src->getName() + 530 "': symbol multiply defined!"); 531 } 532 533 // Check visibility 534 if (Dest && Src->getVisibility() != Dest->getVisibility()) 535 if (!Src->isDeclaration() && !Dest->isDeclaration()) 536 return Error(Err, "Linking globals named '" + Src->getName() + 537 "': symbols have different visibilities!"); 538 return false; 539} 540 541// Insert all of the named mdnoes in Src into the Dest module. 542static void LinkNamedMDNodes(Module *Dest, Module *Src) { 543 for (Module::const_named_metadata_iterator I = Src->named_metadata_begin(), 544 E = Src->named_metadata_end(); I != E; ++I) { 545 const NamedMDNode *SrcNMD = I; 546 NamedMDNode *DestNMD = Dest->getNamedMetadata(SrcNMD->getName()); 547 if (!DestNMD) 548 NamedMDNode::Create(SrcNMD, Dest); 549 else { 550 // Add Src elements into Dest node. 551 for (unsigned i = 0, e = SrcNMD->getNumElements(); i != e; ++i) 552 DestNMD->addElement(SrcNMD->getElement(i)); 553 } 554 } 555} 556 557// LinkGlobals - Loop through the global variables in the src module and merge 558// them into the dest module. 559static bool LinkGlobals(Module *Dest, const Module *Src, 560 std::map<const Value*, Value*> &ValueMap, 561 std::multimap<std::string, GlobalVariable *> &AppendingVars, 562 std::string *Err) { 563 ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable(); 564 565 // Loop over all of the globals in the src module, mapping them over as we go 566 for (Module::const_global_iterator I = Src->global_begin(), 567 E = Src->global_end(); I != E; ++I) { 568 const GlobalVariable *SGV = I; 569 GlobalValue *DGV = 0; 570 571 // Check to see if may have to link the global with the global, alias or 572 // function. 573 if (SGV->hasName() && !SGV->hasLocalLinkage()) 574 DGV = cast_or_null<GlobalValue>(DestSymTab.lookup(SGV->getName())); 575 576 // If we found a global with the same name in the dest module, but it has 577 // internal linkage, we are really not doing any linkage here. 578 if (DGV && DGV->hasLocalLinkage()) 579 DGV = 0; 580 581 // If types don't agree due to opaque types, try to resolve them. 582 if (DGV && DGV->getType() != SGV->getType()) 583 RecursiveResolveTypes(SGV->getType(), DGV->getType()); 584 585 assert((SGV->hasInitializer() || SGV->hasExternalWeakLinkage() || 586 SGV->hasExternalLinkage() || SGV->hasDLLImportLinkage()) && 587 "Global must either be external or have an initializer!"); 588 589 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 590 bool LinkFromSrc = false; 591 if (GetLinkageResult(DGV, SGV, NewLinkage, LinkFromSrc, Err)) 592 return true; 593 594 if (DGV == 0) { 595 // No linking to be performed, simply create an identical version of the 596 // symbol over in the dest module... the initializer will be filled in 597 // later by LinkGlobalInits. 598 GlobalVariable *NewDGV = 599 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 600 SGV->isConstant(), SGV->getLinkage(), /*init*/0, 601 SGV->getName(), 0, false, 602 SGV->getType()->getAddressSpace()); 603 // Propagate alignment, visibility and section info. 604 CopyGVAttributes(NewDGV, SGV); 605 606 // If the LLVM runtime renamed the global, but it is an externally visible 607 // symbol, DGV must be an existing global with internal linkage. Rename 608 // it. 609 if (!NewDGV->hasLocalLinkage() && NewDGV->getName() != SGV->getName()) 610 ForceRenaming(NewDGV, SGV->getName()); 611 612 // Make sure to remember this mapping. 613 ValueMap[SGV] = NewDGV; 614 615 // Keep track that this is an appending variable. 616 if (SGV->hasAppendingLinkage()) 617 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV)); 618 continue; 619 } 620 621 // If the visibilities of the symbols disagree and the destination is a 622 // prototype, take the visibility of its input. 623 if (DGV->isDeclaration()) 624 DGV->setVisibility(SGV->getVisibility()); 625 626 if (DGV->hasAppendingLinkage()) { 627 // No linking is performed yet. Just insert a new copy of the global, and 628 // keep track of the fact that it is an appending variable in the 629 // AppendingVars map. The name is cleared out so that no linkage is 630 // performed. 631 GlobalVariable *NewDGV = 632 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 633 SGV->isConstant(), SGV->getLinkage(), /*init*/0, 634 "", 0, false, 635 SGV->getType()->getAddressSpace()); 636 637 // Set alignment allowing CopyGVAttributes merge it with alignment of SGV. 638 NewDGV->setAlignment(DGV->getAlignment()); 639 // Propagate alignment, section and visibility info. 640 CopyGVAttributes(NewDGV, SGV); 641 642 // Make sure to remember this mapping... 643 ValueMap[SGV] = NewDGV; 644 645 // Keep track that this is an appending variable... 646 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV)); 647 continue; 648 } 649 650 if (LinkFromSrc) { 651 if (isa<GlobalAlias>(DGV)) 652 return Error(Err, "Global-Alias Collision on '" + SGV->getName() + 653 "': symbol multiple defined"); 654 655 // If the types don't match, and if we are to link from the source, nuke 656 // DGV and create a new one of the appropriate type. Note that the thing 657 // we are replacing may be a function (if a prototype, weak, etc) or a 658 // global variable. 659 GlobalVariable *NewDGV = 660 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 661 SGV->isConstant(), NewLinkage, /*init*/0, 662 DGV->getName(), 0, false, 663 SGV->getType()->getAddressSpace()); 664 665 // Propagate alignment, section, and visibility info. 666 CopyGVAttributes(NewDGV, SGV); 667 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV, 668 DGV->getType())); 669 670 // DGV will conflict with NewDGV because they both had the same 671 // name. We must erase this now so ForceRenaming doesn't assert 672 // because DGV might not have internal linkage. 673 if (GlobalVariable *Var = dyn_cast<GlobalVariable>(DGV)) 674 Var->eraseFromParent(); 675 else 676 cast<Function>(DGV)->eraseFromParent(); 677 DGV = NewDGV; 678 679 // If the symbol table renamed the global, but it is an externally visible 680 // symbol, DGV must be an existing global with internal linkage. Rename. 681 if (NewDGV->getName() != SGV->getName() && !NewDGV->hasLocalLinkage()) 682 ForceRenaming(NewDGV, SGV->getName()); 683 684 // Inherit const as appropriate. 685 NewDGV->setConstant(SGV->isConstant()); 686 687 // Make sure to remember this mapping. 688 ValueMap[SGV] = NewDGV; 689 continue; 690 } 691 692 // Not "link from source", keep the one in the DestModule and remap the 693 // input onto it. 694 695 // Special case for const propagation. 696 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) 697 if (DGVar->isDeclaration() && SGV->isConstant() && !DGVar->isConstant()) 698 DGVar->setConstant(true); 699 700 // SGV is global, but DGV is alias. 701 if (isa<GlobalAlias>(DGV)) { 702 // The only valid mappings are: 703 // - SGV is external declaration, which is effectively a no-op. 704 // - SGV is weak, when we just need to throw SGV out. 705 if (!SGV->isDeclaration() && !SGV->isWeakForLinker()) 706 return Error(Err, "Global-Alias Collision on '" + SGV->getName() + 707 "': symbol multiple defined"); 708 } 709 710 // Set calculated linkage 711 DGV->setLinkage(NewLinkage); 712 713 // Make sure to remember this mapping... 714 ValueMap[SGV] = ConstantExpr::getBitCast(DGV, SGV->getType()); 715 } 716 return false; 717} 718 719static GlobalValue::LinkageTypes 720CalculateAliasLinkage(const GlobalValue *SGV, const GlobalValue *DGV) { 721 GlobalValue::LinkageTypes SL = SGV->getLinkage(); 722 GlobalValue::LinkageTypes DL = DGV->getLinkage(); 723 if (SL == GlobalValue::ExternalLinkage || DL == GlobalValue::ExternalLinkage) 724 return GlobalValue::ExternalLinkage; 725 else if (SL == GlobalValue::WeakAnyLinkage || 726 DL == GlobalValue::WeakAnyLinkage) 727 return GlobalValue::WeakAnyLinkage; 728 else if (SL == GlobalValue::WeakODRLinkage || 729 DL == GlobalValue::WeakODRLinkage) 730 return GlobalValue::WeakODRLinkage; 731 else if (SL == GlobalValue::InternalLinkage && 732 DL == GlobalValue::InternalLinkage) 733 return GlobalValue::InternalLinkage; 734 else if (SL == GlobalValue::LinkerPrivateLinkage && 735 DL == GlobalValue::LinkerPrivateLinkage) 736 return GlobalValue::LinkerPrivateLinkage; 737 else { 738 assert (SL == GlobalValue::PrivateLinkage && 739 DL == GlobalValue::PrivateLinkage && "Unexpected linkage type"); 740 return GlobalValue::PrivateLinkage; 741 } 742} 743 744// LinkAlias - Loop through the alias in the src module and link them into the 745// dest module. We're assuming, that all functions/global variables were already 746// linked in. 747static bool LinkAlias(Module *Dest, const Module *Src, 748 std::map<const Value*, Value*> &ValueMap, 749 std::string *Err) { 750 // Loop over all alias in the src module 751 for (Module::const_alias_iterator I = Src->alias_begin(), 752 E = Src->alias_end(); I != E; ++I) { 753 const GlobalAlias *SGA = I; 754 const GlobalValue *SAliasee = SGA->getAliasedGlobal(); 755 GlobalAlias *NewGA = NULL; 756 757 // Globals were already linked, thus we can just query ValueMap for variant 758 // of SAliasee in Dest. 759 std::map<const Value*,Value*>::const_iterator VMI = ValueMap.find(SAliasee); 760 assert(VMI != ValueMap.end() && "Aliasee not linked"); 761 GlobalValue* DAliasee = cast<GlobalValue>(VMI->second); 762 GlobalValue* DGV = NULL; 763 764 // Try to find something 'similar' to SGA in destination module. 765 if (!DGV && !SGA->hasLocalLinkage()) { 766 DGV = Dest->getNamedAlias(SGA->getName()); 767 768 // If types don't agree due to opaque types, try to resolve them. 769 if (DGV && DGV->getType() != SGA->getType()) 770 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 771 } 772 773 if (!DGV && !SGA->hasLocalLinkage()) { 774 DGV = Dest->getGlobalVariable(SGA->getName()); 775 776 // If types don't agree due to opaque types, try to resolve them. 777 if (DGV && DGV->getType() != SGA->getType()) 778 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 779 } 780 781 if (!DGV && !SGA->hasLocalLinkage()) { 782 DGV = Dest->getFunction(SGA->getName()); 783 784 // If types don't agree due to opaque types, try to resolve them. 785 if (DGV && DGV->getType() != SGA->getType()) 786 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 787 } 788 789 // No linking to be performed on internal stuff. 790 if (DGV && DGV->hasLocalLinkage()) 791 DGV = NULL; 792 793 if (GlobalAlias *DGA = dyn_cast_or_null<GlobalAlias>(DGV)) { 794 // Types are known to be the same, check whether aliasees equal. As 795 // globals are already linked we just need query ValueMap to find the 796 // mapping. 797 if (DAliasee == DGA->getAliasedGlobal()) { 798 // This is just two copies of the same alias. Propagate linkage, if 799 // necessary. 800 DGA->setLinkage(CalculateAliasLinkage(SGA, DGA)); 801 802 NewGA = DGA; 803 // Proceed to 'common' steps 804 } else 805 return Error(Err, "Alias Collision on '" + SGA->getName()+ 806 "': aliases have different aliasees"); 807 } else if (GlobalVariable *DGVar = dyn_cast_or_null<GlobalVariable>(DGV)) { 808 // The only allowed way is to link alias with external declaration or weak 809 // symbol.. 810 if (DGVar->isDeclaration() || DGVar->isWeakForLinker()) { 811 // But only if aliasee is global too... 812 if (!isa<GlobalVariable>(DAliasee)) 813 return Error(Err, "Global-Alias Collision on '" + SGA->getName() + 814 "': aliasee is not global variable"); 815 816 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 817 SGA->getName(), DAliasee, Dest); 818 CopyGVAttributes(NewGA, SGA); 819 820 // Any uses of DGV need to change to NewGA, with cast, if needed. 821 if (SGA->getType() != DGVar->getType()) 822 DGVar->replaceAllUsesWith(ConstantExpr::getBitCast(NewGA, 823 DGVar->getType())); 824 else 825 DGVar->replaceAllUsesWith(NewGA); 826 827 // DGVar will conflict with NewGA because they both had the same 828 // name. We must erase this now so ForceRenaming doesn't assert 829 // because DGV might not have internal linkage. 830 DGVar->eraseFromParent(); 831 832 // Proceed to 'common' steps 833 } else 834 return Error(Err, "Global-Alias Collision on '" + SGA->getName() + 835 "': symbol multiple defined"); 836 } else if (Function *DF = dyn_cast_or_null<Function>(DGV)) { 837 // The only allowed way is to link alias with external declaration or weak 838 // symbol... 839 if (DF->isDeclaration() || DF->isWeakForLinker()) { 840 // But only if aliasee is function too... 841 if (!isa<Function>(DAliasee)) 842 return Error(Err, "Function-Alias Collision on '" + SGA->getName() + 843 "': aliasee is not function"); 844 845 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 846 SGA->getName(), DAliasee, Dest); 847 CopyGVAttributes(NewGA, SGA); 848 849 // Any uses of DF need to change to NewGA, with cast, if needed. 850 if (SGA->getType() != DF->getType()) 851 DF->replaceAllUsesWith(ConstantExpr::getBitCast(NewGA, 852 DF->getType())); 853 else 854 DF->replaceAllUsesWith(NewGA); 855 856 // DF will conflict with NewGA because they both had the same 857 // name. We must erase this now so ForceRenaming doesn't assert 858 // because DF might not have internal linkage. 859 DF->eraseFromParent(); 860 861 // Proceed to 'common' steps 862 } else 863 return Error(Err, "Function-Alias Collision on '" + SGA->getName() + 864 "': symbol multiple defined"); 865 } else { 866 // No linking to be performed, simply create an identical version of the 867 // alias over in the dest module... 868 869 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 870 SGA->getName(), DAliasee, Dest); 871 CopyGVAttributes(NewGA, SGA); 872 873 // Proceed to 'common' steps 874 } 875 876 assert(NewGA && "No alias was created in destination module!"); 877 878 // If the symbol table renamed the alias, but it is an externally visible 879 // symbol, DGA must be an global value with internal linkage. Rename it. 880 if (NewGA->getName() != SGA->getName() && 881 !NewGA->hasLocalLinkage()) 882 ForceRenaming(NewGA, SGA->getName()); 883 884 // Remember this mapping so uses in the source module get remapped 885 // later by RemapOperand. 886 ValueMap[SGA] = NewGA; 887 } 888 889 return false; 890} 891 892 893// LinkGlobalInits - Update the initializers in the Dest module now that all 894// globals that may be referenced are in Dest. 895static bool LinkGlobalInits(Module *Dest, const Module *Src, 896 std::map<const Value*, Value*> &ValueMap, 897 std::string *Err) { 898 // Loop over all of the globals in the src module, mapping them over as we go 899 for (Module::const_global_iterator I = Src->global_begin(), 900 E = Src->global_end(); I != E; ++I) { 901 const GlobalVariable *SGV = I; 902 903 if (SGV->hasInitializer()) { // Only process initialized GV's 904 // Figure out what the initializer looks like in the dest module... 905 Constant *SInit = 906 cast<Constant>(RemapOperand(SGV->getInitializer(), ValueMap, 907 Dest->getContext())); 908 // Grab destination global variable or alias. 909 GlobalValue *DGV = cast<GlobalValue>(ValueMap[SGV]->stripPointerCasts()); 910 911 // If dest if global variable, check that initializers match. 912 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) { 913 if (DGVar->hasInitializer()) { 914 if (SGV->hasExternalLinkage()) { 915 if (DGVar->getInitializer() != SInit) 916 return Error(Err, "Global Variable Collision on '" + 917 SGV->getName() + 918 "': global variables have different initializers"); 919 } else if (DGVar->isWeakForLinker()) { 920 // Nothing is required, mapped values will take the new global 921 // automatically. 922 } else if (SGV->isWeakForLinker()) { 923 // Nothing is required, mapped values will take the new global 924 // automatically. 925 } else if (DGVar->hasAppendingLinkage()) { 926 llvm_unreachable("Appending linkage unimplemented!"); 927 } else { 928 llvm_unreachable("Unknown linkage!"); 929 } 930 } else { 931 // Copy the initializer over now... 932 DGVar->setInitializer(SInit); 933 } 934 } else { 935 // Destination is alias, the only valid situation is when source is 936 // weak. Also, note, that we already checked linkage in LinkGlobals(), 937 // thus we assert here. 938 // FIXME: Should we weaken this assumption, 'dereference' alias and 939 // check for initializer of aliasee? 940 assert(SGV->isWeakForLinker()); 941 } 942 } 943 } 944 return false; 945} 946 947// LinkFunctionProtos - Link the functions together between the two modules, 948// without doing function bodies... this just adds external function prototypes 949// to the Dest function... 950// 951static bool LinkFunctionProtos(Module *Dest, const Module *Src, 952 std::map<const Value*, Value*> &ValueMap, 953 std::string *Err) { 954 ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable(); 955 956 // Loop over all of the functions in the src module, mapping them over 957 for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) { 958 const Function *SF = I; // SrcFunction 959 GlobalValue *DGV = 0; 960 961 // Check to see if may have to link the function with the global, alias or 962 // function. 963 if (SF->hasName() && !SF->hasLocalLinkage()) 964 DGV = cast_or_null<GlobalValue>(DestSymTab.lookup(SF->getName())); 965 966 // If we found a global with the same name in the dest module, but it has 967 // internal linkage, we are really not doing any linkage here. 968 if (DGV && DGV->hasLocalLinkage()) 969 DGV = 0; 970 971 // If types don't agree due to opaque types, try to resolve them. 972 if (DGV && DGV->getType() != SF->getType()) 973 RecursiveResolveTypes(SF->getType(), DGV->getType()); 974 975 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 976 bool LinkFromSrc = false; 977 if (GetLinkageResult(DGV, SF, NewLinkage, LinkFromSrc, Err)) 978 return true; 979 980 // If there is no linkage to be performed, just bring over SF without 981 // modifying it. 982 if (DGV == 0) { 983 // Function does not already exist, simply insert an function signature 984 // identical to SF into the dest module. 985 Function *NewDF = Function::Create(SF->getFunctionType(), 986 SF->getLinkage(), 987 SF->getName(), Dest); 988 CopyGVAttributes(NewDF, SF); 989 990 // If the LLVM runtime renamed the function, but it is an externally 991 // visible symbol, DF must be an existing function with internal linkage. 992 // Rename it. 993 if (!NewDF->hasLocalLinkage() && NewDF->getName() != SF->getName()) 994 ForceRenaming(NewDF, SF->getName()); 995 996 // ... and remember this mapping... 997 ValueMap[SF] = NewDF; 998 continue; 999 } 1000 1001 // If the visibilities of the symbols disagree and the destination is a 1002 // prototype, take the visibility of its input. 1003 if (DGV->isDeclaration()) 1004 DGV->setVisibility(SF->getVisibility()); 1005 1006 if (LinkFromSrc) { 1007 if (isa<GlobalAlias>(DGV)) 1008 return Error(Err, "Function-Alias Collision on '" + SF->getName() + 1009 "': symbol multiple defined"); 1010 1011 // We have a definition of the same name but different type in the 1012 // source module. Copy the prototype to the destination and replace 1013 // uses of the destination's prototype with the new prototype. 1014 Function *NewDF = Function::Create(SF->getFunctionType(), NewLinkage, 1015 SF->getName(), Dest); 1016 CopyGVAttributes(NewDF, SF); 1017 1018 // Any uses of DF need to change to NewDF, with cast 1019 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, 1020 DGV->getType())); 1021 1022 // DF will conflict with NewDF because they both had the same. We must 1023 // erase this now so ForceRenaming doesn't assert because DF might 1024 // not have internal linkage. 1025 if (GlobalVariable *Var = dyn_cast<GlobalVariable>(DGV)) 1026 Var->eraseFromParent(); 1027 else 1028 cast<Function>(DGV)->eraseFromParent(); 1029 1030 // If the symbol table renamed the function, but it is an externally 1031 // visible symbol, DF must be an existing function with internal 1032 // linkage. Rename it. 1033 if (NewDF->getName() != SF->getName() && !NewDF->hasLocalLinkage()) 1034 ForceRenaming(NewDF, SF->getName()); 1035 1036 // Remember this mapping so uses in the source module get remapped 1037 // later by RemapOperand. 1038 ValueMap[SF] = NewDF; 1039 continue; 1040 } 1041 1042 // Not "link from source", keep the one in the DestModule and remap the 1043 // input onto it. 1044 1045 if (isa<GlobalAlias>(DGV)) { 1046 // The only valid mappings are: 1047 // - SF is external declaration, which is effectively a no-op. 1048 // - SF is weak, when we just need to throw SF out. 1049 if (!SF->isDeclaration() && !SF->isWeakForLinker()) 1050 return Error(Err, "Function-Alias Collision on '" + SF->getName() + 1051 "': symbol multiple defined"); 1052 } 1053 1054 // Set calculated linkage 1055 DGV->setLinkage(NewLinkage); 1056 1057 // Make sure to remember this mapping. 1058 ValueMap[SF] = ConstantExpr::getBitCast(DGV, SF->getType()); 1059 } 1060 return false; 1061} 1062 1063// LinkFunctionBody - Copy the source function over into the dest function and 1064// fix up references to values. At this point we know that Dest is an external 1065// function, and that Src is not. 1066static bool LinkFunctionBody(Function *Dest, Function *Src, 1067 std::map<const Value*, Value*> &ValueMap, 1068 std::string *Err) { 1069 assert(Src && Dest && Dest->isDeclaration() && !Src->isDeclaration()); 1070 1071 // Go through and convert function arguments over, remembering the mapping. 1072 Function::arg_iterator DI = Dest->arg_begin(); 1073 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 1074 I != E; ++I, ++DI) { 1075 DI->setName(I->getName()); // Copy the name information over... 1076 1077 // Add a mapping to our local map 1078 ValueMap[I] = DI; 1079 } 1080 1081 // Splice the body of the source function into the dest function. 1082 Dest->getBasicBlockList().splice(Dest->end(), Src->getBasicBlockList()); 1083 1084 // At this point, all of the instructions and values of the function are now 1085 // copied over. The only problem is that they are still referencing values in 1086 // the Source function as operands. Loop through all of the operands of the 1087 // functions and patch them up to point to the local versions... 1088 // 1089 for (Function::iterator BB = Dest->begin(), BE = Dest->end(); BB != BE; ++BB) 1090 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) 1091 for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end(); 1092 OI != OE; ++OI) 1093 if (!isa<Instruction>(*OI) && !isa<BasicBlock>(*OI)) 1094 *OI = RemapOperand(*OI, ValueMap, Dest->getContext()); 1095 1096 // There is no need to map the arguments anymore. 1097 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 1098 I != E; ++I) 1099 ValueMap.erase(I); 1100 1101 return false; 1102} 1103 1104 1105// LinkFunctionBodies - Link in the function bodies that are defined in the 1106// source module into the DestModule. This consists basically of copying the 1107// function over and fixing up references to values. 1108static bool LinkFunctionBodies(Module *Dest, Module *Src, 1109 std::map<const Value*, Value*> &ValueMap, 1110 std::string *Err) { 1111 1112 // Loop over all of the functions in the src module, mapping them over as we 1113 // go 1114 for (Module::iterator SF = Src->begin(), E = Src->end(); SF != E; ++SF) { 1115 if (!SF->isDeclaration()) { // No body if function is external 1116 Function *DF = dyn_cast<Function>(ValueMap[SF]); // Destination function 1117 1118 // DF not external SF external? 1119 if (DF && DF->isDeclaration()) 1120 // Only provide the function body if there isn't one already. 1121 if (LinkFunctionBody(DF, SF, ValueMap, Err)) 1122 return true; 1123 } 1124 } 1125 return false; 1126} 1127 1128// LinkAppendingVars - If there were any appending global variables, link them 1129// together now. Return true on error. 1130static bool LinkAppendingVars(Module *M, 1131 std::multimap<std::string, GlobalVariable *> &AppendingVars, 1132 std::string *ErrorMsg) { 1133 if (AppendingVars.empty()) return false; // Nothing to do. 1134 1135 // Loop over the multimap of appending vars, processing any variables with the 1136 // same name, forming a new appending global variable with both of the 1137 // initializers merged together, then rewrite references to the old variables 1138 // and delete them. 1139 std::vector<Constant*> Inits; 1140 while (AppendingVars.size() > 1) { 1141 // Get the first two elements in the map... 1142 std::multimap<std::string, 1143 GlobalVariable*>::iterator Second = AppendingVars.begin(), First=Second++; 1144 1145 // If the first two elements are for different names, there is no pair... 1146 // Otherwise there is a pair, so link them together... 1147 if (First->first == Second->first) { 1148 GlobalVariable *G1 = First->second, *G2 = Second->second; 1149 const ArrayType *T1 = cast<ArrayType>(G1->getType()->getElementType()); 1150 const ArrayType *T2 = cast<ArrayType>(G2->getType()->getElementType()); 1151 1152 // Check to see that they two arrays agree on type... 1153 if (T1->getElementType() != T2->getElementType()) 1154 return Error(ErrorMsg, 1155 "Appending variables with different element types need to be linked!"); 1156 if (G1->isConstant() != G2->isConstant()) 1157 return Error(ErrorMsg, 1158 "Appending variables linked with different const'ness!"); 1159 1160 if (G1->getAlignment() != G2->getAlignment()) 1161 return Error(ErrorMsg, 1162 "Appending variables with different alignment need to be linked!"); 1163 1164 if (G1->getVisibility() != G2->getVisibility()) 1165 return Error(ErrorMsg, 1166 "Appending variables with different visibility need to be linked!"); 1167 1168 if (G1->getSection() != G2->getSection()) 1169 return Error(ErrorMsg, 1170 "Appending variables with different section name need to be linked!"); 1171 1172 unsigned NewSize = T1->getNumElements() + T2->getNumElements(); 1173 ArrayType *NewType = ArrayType::get(T1->getElementType(), 1174 NewSize); 1175 1176 G1->setName(""); // Clear G1's name in case of a conflict! 1177 1178 // Create the new global variable... 1179 GlobalVariable *NG = 1180 new GlobalVariable(*M, NewType, G1->isConstant(), G1->getLinkage(), 1181 /*init*/0, First->first, 0, G1->isThreadLocal(), 1182 G1->getType()->getAddressSpace()); 1183 1184 // Propagate alignment, visibility and section info. 1185 CopyGVAttributes(NG, G1); 1186 1187 // Merge the initializer... 1188 Inits.reserve(NewSize); 1189 if (ConstantArray *I = dyn_cast<ConstantArray>(G1->getInitializer())) { 1190 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i) 1191 Inits.push_back(I->getOperand(i)); 1192 } else { 1193 assert(isa<ConstantAggregateZero>(G1->getInitializer())); 1194 Constant *CV = Constant::getNullValue(T1->getElementType()); 1195 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i) 1196 Inits.push_back(CV); 1197 } 1198 if (ConstantArray *I = dyn_cast<ConstantArray>(G2->getInitializer())) { 1199 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i) 1200 Inits.push_back(I->getOperand(i)); 1201 } else { 1202 assert(isa<ConstantAggregateZero>(G2->getInitializer())); 1203 Constant *CV = Constant::getNullValue(T2->getElementType()); 1204 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i) 1205 Inits.push_back(CV); 1206 } 1207 NG->setInitializer(ConstantArray::get(NewType, Inits)); 1208 Inits.clear(); 1209 1210 // Replace any uses of the two global variables with uses of the new 1211 // global... 1212 1213 // FIXME: This should rewrite simple/straight-forward uses such as 1214 // getelementptr instructions to not use the Cast! 1215 G1->replaceAllUsesWith(ConstantExpr::getBitCast(NG, 1216 G1->getType())); 1217 G2->replaceAllUsesWith(ConstantExpr::getBitCast(NG, 1218 G2->getType())); 1219 1220 // Remove the two globals from the module now... 1221 M->getGlobalList().erase(G1); 1222 M->getGlobalList().erase(G2); 1223 1224 // Put the new global into the AppendingVars map so that we can handle 1225 // linking of more than two vars... 1226 Second->second = NG; 1227 } 1228 AppendingVars.erase(First); 1229 } 1230 1231 return false; 1232} 1233 1234static bool ResolveAliases(Module *Dest) { 1235 for (Module::alias_iterator I = Dest->alias_begin(), E = Dest->alias_end(); 1236 I != E; ++I) 1237 if (const GlobalValue *GV = I->resolveAliasedGlobal()) 1238 if (GV != I && !GV->isDeclaration()) 1239 I->replaceAllUsesWith(const_cast<GlobalValue*>(GV)); 1240 1241 return false; 1242} 1243 1244// LinkModules - This function links two modules together, with the resulting 1245// left module modified to be the composite of the two input modules. If an 1246// error occurs, true is returned and ErrorMsg (if not null) is set to indicate 1247// the problem. Upon failure, the Dest module could be in a modified state, and 1248// shouldn't be relied on to be consistent. 1249bool 1250Linker::LinkModules(Module *Dest, Module *Src, std::string *ErrorMsg) { 1251 assert(Dest != 0 && "Invalid Destination module"); 1252 assert(Src != 0 && "Invalid Source Module"); 1253 1254 if (Dest->getDataLayout().empty()) { 1255 if (!Src->getDataLayout().empty()) { 1256 Dest->setDataLayout(Src->getDataLayout()); 1257 } else { 1258 std::string DataLayout; 1259 1260 if (Dest->getEndianness() == Module::AnyEndianness) { 1261 if (Src->getEndianness() == Module::BigEndian) 1262 DataLayout.append("E"); 1263 else if (Src->getEndianness() == Module::LittleEndian) 1264 DataLayout.append("e"); 1265 } 1266 1267 if (Dest->getPointerSize() == Module::AnyPointerSize) { 1268 if (Src->getPointerSize() == Module::Pointer64) 1269 DataLayout.append(DataLayout.length() == 0 ? "p:64:64" : "-p:64:64"); 1270 else if (Src->getPointerSize() == Module::Pointer32) 1271 DataLayout.append(DataLayout.length() == 0 ? "p:32:32" : "-p:32:32"); 1272 } 1273 Dest->setDataLayout(DataLayout); 1274 } 1275 } 1276 1277 // Copy the target triple from the source to dest if the dest's is empty. 1278 if (Dest->getTargetTriple().empty() && !Src->getTargetTriple().empty()) 1279 Dest->setTargetTriple(Src->getTargetTriple()); 1280 1281 if (!Src->getDataLayout().empty() && !Dest->getDataLayout().empty() && 1282 Src->getDataLayout() != Dest->getDataLayout()) 1283 errs() << "WARNING: Linking two modules of different data layouts!\n"; 1284 if (!Src->getTargetTriple().empty() && 1285 Dest->getTargetTriple() != Src->getTargetTriple()) 1286 errs() << "WARNING: Linking two modules of different target triples!\n"; 1287 1288 // Append the module inline asm string. 1289 if (!Src->getModuleInlineAsm().empty()) { 1290 if (Dest->getModuleInlineAsm().empty()) 1291 Dest->setModuleInlineAsm(Src->getModuleInlineAsm()); 1292 else 1293 Dest->setModuleInlineAsm(Dest->getModuleInlineAsm()+"\n"+ 1294 Src->getModuleInlineAsm()); 1295 } 1296 1297 // Update the destination module's dependent libraries list with the libraries 1298 // from the source module. There's no opportunity for duplicates here as the 1299 // Module ensures that duplicate insertions are discarded. 1300 for (Module::lib_iterator SI = Src->lib_begin(), SE = Src->lib_end(); 1301 SI != SE; ++SI) 1302 Dest->addLibrary(*SI); 1303 1304 // LinkTypes - Go through the symbol table of the Src module and see if any 1305 // types are named in the src module that are not named in the Dst module. 1306 // Make sure there are no type name conflicts. 1307 if (LinkTypes(Dest, Src, ErrorMsg)) 1308 return true; 1309 1310 // ValueMap - Mapping of values from what they used to be in Src, to what they 1311 // are now in Dest. 1312 std::map<const Value*, Value*> ValueMap; 1313 1314 // AppendingVars - Keep track of global variables in the destination module 1315 // with appending linkage. After the module is linked together, they are 1316 // appended and the module is rewritten. 1317 std::multimap<std::string, GlobalVariable *> AppendingVars; 1318 for (Module::global_iterator I = Dest->global_begin(), E = Dest->global_end(); 1319 I != E; ++I) { 1320 // Add all of the appending globals already in the Dest module to 1321 // AppendingVars. 1322 if (I->hasAppendingLinkage()) 1323 AppendingVars.insert(std::make_pair(I->getName(), I)); 1324 } 1325 1326 // Insert all of the named mdnoes in Src into the Dest module. 1327 LinkNamedMDNodes(Dest, Src); 1328 1329 // Insert all of the globals in src into the Dest module... without linking 1330 // initializers (which could refer to functions not yet mapped over). 1331 if (LinkGlobals(Dest, Src, ValueMap, AppendingVars, ErrorMsg)) 1332 return true; 1333 1334 // Link the functions together between the two modules, without doing function 1335 // bodies... this just adds external function prototypes to the Dest 1336 // function... We do this so that when we begin processing function bodies, 1337 // all of the global values that may be referenced are available in our 1338 // ValueMap. 1339 if (LinkFunctionProtos(Dest, Src, ValueMap, ErrorMsg)) 1340 return true; 1341 1342 // If there were any alias, link them now. We really need to do this now, 1343 // because all of the aliases that may be referenced need to be available in 1344 // ValueMap 1345 if (LinkAlias(Dest, Src, ValueMap, ErrorMsg)) return true; 1346 1347 // Update the initializers in the Dest module now that all globals that may 1348 // be referenced are in Dest. 1349 if (LinkGlobalInits(Dest, Src, ValueMap, ErrorMsg)) return true; 1350 1351 // Link in the function bodies that are defined in the source module into the 1352 // DestModule. This consists basically of copying the function over and 1353 // fixing up references to values. 1354 if (LinkFunctionBodies(Dest, Src, ValueMap, ErrorMsg)) return true; 1355 1356 // If there were any appending global variables, link them together now. 1357 if (LinkAppendingVars(Dest, AppendingVars, ErrorMsg)) return true; 1358 1359 // Resolve all uses of aliases with aliasees 1360 if (ResolveAliases(Dest)) return true; 1361 1362 // If the source library's module id is in the dependent library list of the 1363 // destination library, remove it since that module is now linked in. 1364 sys::Path modId; 1365 modId.set(Src->getModuleIdentifier()); 1366 if (!modId.isEmpty()) 1367 Dest->removeLibrary(modId.getBasename()); 1368 1369 return false; 1370} 1371 1372// vim: sw=2 1373