LinkModules.cpp revision f44c6051e02ddb207d5928b4ef3cde956d2b5025
1//===- Linker.cpp - Module Linker Implementation --------------------------===// 2// 3// This file implements the LLVM module linker. 4// 5// Specifically, this: 6// * Merges global variables between the two modules 7// * Uninit + Uninit = Init, Init + Uninit = Init, Init + Init = Error if != 8// * Merges functions between two modules 9// 10//===----------------------------------------------------------------------===// 11 12#include "llvm/Transforms/Utils/Linker.h" 13#include "llvm/Module.h" 14#include "llvm/SymbolTable.h" 15#include "llvm/DerivedTypes.h" 16#include "llvm/iOther.h" 17#include "llvm/Constants.h" 18 19// Error - Simple wrapper function to conditionally assign to E and return true. 20// This just makes error return conditions a little bit simpler... 21// 22static inline bool Error(std::string *E, const std::string &Message) { 23 if (E) *E = Message; 24 return true; 25} 26 27// ResolveTypes - Attempt to link the two specified types together. Return true 28// if there is an error and they cannot yet be linked. 29// 30static bool ResolveTypes(const Type *DestTy, const Type *SrcTy, 31 SymbolTable *DestST, const std::string &Name) { 32 if (DestTy == SrcTy) return false; // If already equal, noop 33 34 // Does the type already exist in the module? 35 if (DestTy && !isa<OpaqueType>(DestTy)) { // Yup, the type already exists... 36 if (const OpaqueType *OT = dyn_cast<OpaqueType>(SrcTy)) { 37 const_cast<OpaqueType*>(OT)->refineAbstractTypeTo(DestTy); 38 } else { 39 return true; // Cannot link types... neither is opaque and not-equal 40 } 41 } else { // Type not in dest module. Add it now. 42 if (DestTy) // Type _is_ in module, just opaque... 43 const_cast<OpaqueType*>(cast<OpaqueType>(DestTy)) 44 ->refineAbstractTypeTo(SrcTy); 45 else if (!Name.empty()) 46 DestST->insert(Name, const_cast<Type*>(SrcTy)); 47 } 48 return false; 49} 50 51static const FunctionType *getFT(const PATypeHolder &TH) { 52 return cast<FunctionType>(TH.get()); 53} 54static const StructType *getST(const PATypeHolder &TH) { 55 return cast<StructType>(TH.get()); 56} 57 58// RecursiveResolveTypes - This is just like ResolveTypes, except that it 59// recurses down into derived types, merging the used types if the parent types 60// are compatible. 61// 62static bool RecursiveResolveTypesI(const PATypeHolder &DestTy, 63 const PATypeHolder &SrcTy, 64 SymbolTable *DestST, const std::string &Name, 65 std::vector<std::pair<PATypeHolder, PATypeHolder> > &Pointers) { 66 const Type *SrcTyT = SrcTy.get(); 67 const Type *DestTyT = DestTy.get(); 68 if (DestTyT == SrcTyT) return false; // If already equal, noop 69 70 // If we found our opaque type, resolve it now! 71 if (isa<OpaqueType>(DestTyT) || isa<OpaqueType>(SrcTyT)) 72 return ResolveTypes(DestTyT, SrcTyT, DestST, Name); 73 74 // Two types cannot be resolved together if they are of different primitive 75 // type. For example, we cannot resolve an int to a float. 76 if (DestTyT->getPrimitiveID() != SrcTyT->getPrimitiveID()) return true; 77 78 // Otherwise, resolve the used type used by this derived type... 79 switch (DestTyT->getPrimitiveID()) { 80 case Type::FunctionTyID: { 81 if (cast<FunctionType>(DestTyT)->isVarArg() != 82 cast<FunctionType>(SrcTyT)->isVarArg()) 83 return true; 84 for (unsigned i = 0, e = getFT(DestTy)->getNumContainedTypes(); i != e; ++i) 85 if (RecursiveResolveTypesI(getFT(DestTy)->getContainedType(i), 86 getFT(SrcTy)->getContainedType(i), DestST, "", 87 Pointers)) 88 return true; 89 return false; 90 } 91 case Type::StructTyID: { 92 if (getST(DestTy)->getNumContainedTypes() != 93 getST(SrcTy)->getNumContainedTypes()) return 1; 94 for (unsigned i = 0, e = getST(DestTy)->getNumContainedTypes(); i != e; ++i) 95 if (RecursiveResolveTypesI(getST(DestTy)->getContainedType(i), 96 getST(SrcTy)->getContainedType(i), DestST, "", 97 Pointers)) 98 return true; 99 return false; 100 } 101 case Type::ArrayTyID: { 102 const ArrayType *DAT = cast<ArrayType>(DestTy.get()); 103 const ArrayType *SAT = cast<ArrayType>(SrcTy.get()); 104 if (DAT->getNumElements() != SAT->getNumElements()) return true; 105 return RecursiveResolveTypesI(DAT->getElementType(), SAT->getElementType(), 106 DestST, "", Pointers); 107 } 108 case Type::PointerTyID: { 109 // If this is a pointer type, check to see if we have already seen it. If 110 // so, we are in a recursive branch. Cut off the search now. We cannot use 111 // an associative container for this search, because the type pointers (keys 112 // in the container) change whenever types get resolved... 113 // 114 for (unsigned i = 0, e = Pointers.size(); i != e; ++i) 115 if (Pointers[i].first == DestTy) 116 return Pointers[i].second != SrcTy; 117 118 // Otherwise, add the current pointers to the vector to stop recursion on 119 // this pair. 120 Pointers.push_back(std::make_pair(DestTyT, SrcTyT)); 121 bool Result = 122 RecursiveResolveTypesI(cast<PointerType>(DestTy.get())->getElementType(), 123 cast<PointerType>(SrcTy.get())->getElementType(), 124 DestST, "", Pointers); 125 Pointers.pop_back(); 126 return Result; 127 } 128 default: assert(0 && "Unexpected type!"); return true; 129 } 130} 131 132static bool RecursiveResolveTypes(const PATypeHolder &DestTy, 133 const PATypeHolder &SrcTy, 134 SymbolTable *DestST, const std::string &Name){ 135 std::vector<std::pair<PATypeHolder, PATypeHolder> > PointerTypes; 136 return RecursiveResolveTypesI(DestTy, SrcTy, DestST, Name, PointerTypes); 137} 138 139 140// LinkTypes - Go through the symbol table of the Src module and see if any 141// types are named in the src module that are not named in the Dst module. 142// Make sure there are no type name conflicts. 143// 144static bool LinkTypes(Module *Dest, const Module *Src, std::string *Err) { 145 SymbolTable *DestST = &Dest->getSymbolTable(); 146 const SymbolTable *SrcST = &Src->getSymbolTable(); 147 148 // Look for a type plane for Type's... 149 SymbolTable::const_iterator PI = SrcST->find(Type::TypeTy); 150 if (PI == SrcST->end()) return false; // No named types, do nothing. 151 152 // Some types cannot be resolved immediately becuse they depend on other types 153 // being resolved to each other first. This contains a list of types we are 154 // waiting to recheck. 155 std::vector<std::string> DelayedTypesToResolve; 156 157 const SymbolTable::VarMap &VM = PI->second; 158 for (SymbolTable::type_const_iterator I = VM.begin(), E = VM.end(); 159 I != E; ++I) { 160 const std::string &Name = I->first; 161 Type *RHS = cast<Type>(I->second); 162 163 // Check to see if this type name is already in the dest module... 164 Type *Entry = cast_or_null<Type>(DestST->lookup(Type::TypeTy, Name)); 165 166 if (ResolveTypes(Entry, RHS, DestST, Name)) { 167 // They look different, save the types 'till later to resolve. 168 DelayedTypesToResolve.push_back(Name); 169 } 170 } 171 172 // Iteratively resolve types while we can... 173 while (!DelayedTypesToResolve.empty()) { 174 // Loop over all of the types, attempting to resolve them if possible... 175 unsigned OldSize = DelayedTypesToResolve.size(); 176 177 // Try direct resolution by name... 178 for (unsigned i = 0; i != DelayedTypesToResolve.size(); ++i) { 179 const std::string &Name = DelayedTypesToResolve[i]; 180 Type *T1 = cast<Type>(VM.find(Name)->second); 181 Type *T2 = cast<Type>(DestST->lookup(Type::TypeTy, Name)); 182 if (!ResolveTypes(T2, T1, DestST, Name)) { 183 // We are making progress! 184 DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i); 185 --i; 186 } 187 } 188 189 // Did we not eliminate any types? 190 if (DelayedTypesToResolve.size() == OldSize) { 191 // Attempt to resolve subelements of types. This allows us to merge these 192 // two types: { int* } and { opaque* } 193 for (unsigned i = 0, e = DelayedTypesToResolve.size(); i != e; ++i) { 194 const std::string &Name = DelayedTypesToResolve[i]; 195 PATypeHolder T1(cast<Type>(VM.find(Name)->second)); 196 PATypeHolder T2(cast<Type>(DestST->lookup(Type::TypeTy, Name))); 197 198 if (!RecursiveResolveTypes(T2, T1, DestST, Name)) { 199 // We are making progress! 200 DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i); 201 202 // Go back to the main loop, perhaps we can resolve directly by name 203 // now... 204 break; 205 } 206 } 207 208 // If we STILL cannot resolve the types, then there is something wrong. 209 // Report the error. 210 if (DelayedTypesToResolve.size() == OldSize) { 211 // Build up an error message of all of the mismatched types. 212 std::string ErrorMessage; 213 for (unsigned i = 0, e = DelayedTypesToResolve.size(); i != e; ++i) { 214 const std::string &Name = DelayedTypesToResolve[i]; 215 const Type *T1 = cast<Type>(VM.find(Name)->second); 216 const Type *T2 = cast<Type>(DestST->lookup(Type::TypeTy, Name)); 217 ErrorMessage += " Type named '" + Name + 218 "' conflicts.\n Src='" + T1->getDescription() + 219 "'.\n Dest='" + T2->getDescription() + "'\n"; 220 } 221 return Error(Err, "Type conflict between types in modules:\n" + 222 ErrorMessage); 223 } 224 } 225 } 226 227 228 return false; 229} 230 231static void PrintMap(const std::map<const Value*, Value*> &M) { 232 for (std::map<const Value*, Value*>::const_iterator I = M.begin(), E =M.end(); 233 I != E; ++I) { 234 std::cerr << " Fr: " << (void*)I->first << " "; 235 I->first->dump(); 236 std::cerr << " To: " << (void*)I->second << " "; 237 I->second->dump(); 238 std::cerr << "\n"; 239 } 240} 241 242 243// RemapOperand - Use LocalMap and GlobalMap to convert references from one 244// module to another. This is somewhat sophisticated in that it can 245// automatically handle constant references correctly as well... 246// 247static Value *RemapOperand(const Value *In, 248 std::map<const Value*, Value*> &LocalMap, 249 std::map<const Value*, Value*> *GlobalMap) { 250 std::map<const Value*,Value*>::const_iterator I = LocalMap.find(In); 251 if (I != LocalMap.end()) return I->second; 252 253 if (GlobalMap) { 254 I = GlobalMap->find(In); 255 if (I != GlobalMap->end()) return I->second; 256 } 257 258 // Check to see if it's a constant that we are interesting in transforming... 259 if (const Constant *CPV = dyn_cast<Constant>(In)) { 260 if (!isa<DerivedType>(CPV->getType()) && !isa<ConstantExpr>(CPV)) 261 return const_cast<Constant*>(CPV); // Simple constants stay identical... 262 263 Constant *Result = 0; 264 265 if (const ConstantArray *CPA = dyn_cast<ConstantArray>(CPV)) { 266 const std::vector<Use> &Ops = CPA->getValues(); 267 std::vector<Constant*> Operands(Ops.size()); 268 for (unsigned i = 0, e = Ops.size(); i != e; ++i) 269 Operands[i] = 270 cast<Constant>(RemapOperand(Ops[i], LocalMap, GlobalMap)); 271 Result = ConstantArray::get(cast<ArrayType>(CPA->getType()), Operands); 272 } else if (const ConstantStruct *CPS = dyn_cast<ConstantStruct>(CPV)) { 273 const std::vector<Use> &Ops = CPS->getValues(); 274 std::vector<Constant*> Operands(Ops.size()); 275 for (unsigned i = 0; i < Ops.size(); ++i) 276 Operands[i] = 277 cast<Constant>(RemapOperand(Ops[i], LocalMap, GlobalMap)); 278 Result = ConstantStruct::get(cast<StructType>(CPS->getType()), Operands); 279 } else if (isa<ConstantPointerNull>(CPV)) { 280 Result = const_cast<Constant*>(CPV); 281 } else if (const ConstantPointerRef *CPR = 282 dyn_cast<ConstantPointerRef>(CPV)) { 283 Value *V = RemapOperand(CPR->getValue(), LocalMap, GlobalMap); 284 Result = ConstantPointerRef::get(cast<GlobalValue>(V)); 285 } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CPV)) { 286 if (CE->getOpcode() == Instruction::GetElementPtr) { 287 Value *Ptr = RemapOperand(CE->getOperand(0), LocalMap, GlobalMap); 288 std::vector<Constant*> Indices; 289 Indices.reserve(CE->getNumOperands()-1); 290 for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i) 291 Indices.push_back(cast<Constant>(RemapOperand(CE->getOperand(i), 292 LocalMap, GlobalMap))); 293 294 Result = ConstantExpr::getGetElementPtr(cast<Constant>(Ptr), Indices); 295 } else if (CE->getNumOperands() == 1) { 296 // Cast instruction 297 assert(CE->getOpcode() == Instruction::Cast); 298 Value *V = RemapOperand(CE->getOperand(0), LocalMap, GlobalMap); 299 Result = ConstantExpr::getCast(cast<Constant>(V), CE->getType()); 300 } else if (CE->getNumOperands() == 2) { 301 // Binary operator... 302 Value *V1 = RemapOperand(CE->getOperand(0), LocalMap, GlobalMap); 303 Value *V2 = RemapOperand(CE->getOperand(1), LocalMap, GlobalMap); 304 305 Result = ConstantExpr::get(CE->getOpcode(), cast<Constant>(V1), 306 cast<Constant>(V2)); 307 } else { 308 assert(0 && "Unknown constant expr type!"); 309 } 310 311 } else { 312 assert(0 && "Unknown type of derived type constant value!"); 313 } 314 315 // Cache the mapping in our local map structure... 316 if (GlobalMap) 317 GlobalMap->insert(std::make_pair(In, Result)); 318 else 319 LocalMap.insert(std::make_pair(In, Result)); 320 return Result; 321 } 322 323 std::cerr << "XXX LocalMap: \n"; 324 PrintMap(LocalMap); 325 326 if (GlobalMap) { 327 std::cerr << "XXX GlobalMap: \n"; 328 PrintMap(*GlobalMap); 329 } 330 331 std::cerr << "Couldn't remap value: " << (void*)In << " " << *In << "\n"; 332 assert(0 && "Couldn't remap value!"); 333 return 0; 334} 335 336/// FindGlobalNamed - Look in the specified symbol table for a global with the 337/// specified name and type. If an exactly matching global does not exist, see 338/// if there is a global which is "type compatible" with the specified 339/// name/type. This allows us to resolve things like '%x = global int*' with 340/// '%x = global opaque*'. 341/// 342static GlobalValue *FindGlobalNamed(const std::string &Name, const Type *Ty, 343 SymbolTable *ST) { 344 // See if an exact match exists in the symbol table... 345 if (Value *V = ST->lookup(Ty, Name)) return cast<GlobalValue>(V); 346 347 // It doesn't exist exactly, scan through all of the type planes in the symbol 348 // table, checking each of them for a type-compatible version. 349 // 350 for (SymbolTable::iterator I = ST->begin(), E = ST->end(); I != E; ++I) 351 if (I->first->getType() != Type::TypeTy) { 352 SymbolTable::VarMap &VM = I->second; 353 // Does this type plane contain an entry with the specified name? 354 SymbolTable::type_iterator TI = VM.find(Name); 355 if (TI != VM.end()) { 356 // Determine whether we can fold the two types together, resolving them. 357 // If so, we can use this value. 358 if (!RecursiveResolveTypes(Ty, I->first, ST, "")) 359 return cast<GlobalValue>(TI->second); 360 } 361 } 362 return 0; // Otherwise, nothing could be found. 363} 364 365 366// LinkGlobals - Loop through the global variables in the src module and merge 367// them into the dest module. 368// 369static bool LinkGlobals(Module *Dest, const Module *Src, 370 std::map<const Value*, Value*> &ValueMap, 371 std::multimap<std::string, GlobalVariable *> &AppendingVars, 372 std::string *Err) { 373 // We will need a module level symbol table if the src module has a module 374 // level symbol table... 375 SymbolTable *ST = (SymbolTable*)&Dest->getSymbolTable(); 376 377 // Loop over all of the globals in the src module, mapping them over as we go 378 // 379 for (Module::const_giterator I = Src->gbegin(), E = Src->gend(); I != E; ++I){ 380 const GlobalVariable *SGV = I; 381 GlobalVariable *DGV = 0; 382 if (SGV->hasName()) { 383 // A same named thing is a global variable, because the only two things 384 // that may be in a module level symbol table are Global Vars and 385 // Functions, and they both have distinct, nonoverlapping, possible types. 386 // 387 DGV = cast_or_null<GlobalVariable>(FindGlobalNamed(SGV->getName(), 388 SGV->getType(), ST)); 389 } 390 391 assert(SGV->hasInitializer() || SGV->hasExternalLinkage() && 392 "Global must either be external or have an initializer!"); 393 394 bool SGExtern = SGV->isExternal(); 395 bool DGExtern = DGV ? DGV->isExternal() : false; 396 397 if (!DGV || DGV->hasInternalLinkage() || SGV->hasInternalLinkage()) { 398 // No linking to be performed, simply create an identical version of the 399 // symbol over in the dest module... the initializer will be filled in 400 // later by LinkGlobalInits... 401 // 402 GlobalVariable *NewDGV = 403 new GlobalVariable(SGV->getType()->getElementType(), 404 SGV->isConstant(), SGV->getLinkage(), /*init*/0, 405 SGV->getName(), Dest); 406 407 // If the LLVM runtime renamed the global, but it is an externally visible 408 // symbol, DGV must be an existing global with internal linkage. Rename 409 // it. 410 if (NewDGV->getName() != SGV->getName() && !NewDGV->hasInternalLinkage()){ 411 assert(DGV && DGV->getName() == SGV->getName() && 412 DGV->hasInternalLinkage()); 413 DGV->setName(""); 414 NewDGV->setName(SGV->getName()); // Force the name back 415 DGV->setName(SGV->getName()); // This will cause a renaming 416 assert(NewDGV->getName() == SGV->getName() && 417 DGV->getName() != SGV->getName()); 418 } 419 420 // Make sure to remember this mapping... 421 ValueMap.insert(std::make_pair(SGV, NewDGV)); 422 if (SGV->hasAppendingLinkage()) 423 // Keep track that this is an appending variable... 424 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV)); 425 426 } else if (SGV->isExternal()) { 427 // If SGV is external or if both SGV & DGV are external.. Just link the 428 // external globals, we aren't adding anything. 429 ValueMap.insert(std::make_pair(SGV, DGV)); 430 431 } else if (DGV->isExternal()) { // If DGV is external but SGV is not... 432 ValueMap.insert(std::make_pair(SGV, DGV)); 433 DGV->setLinkage(SGV->getLinkage()); // Inherit linkage! 434 } else if (SGV->getLinkage() != DGV->getLinkage()) { 435 return Error(Err, "Global variables named '" + SGV->getName() + 436 "' have different linkage specifiers!"); 437 } else if (SGV->hasExternalLinkage()) { 438 // Allow linking two exactly identical external global variables... 439 if (SGV->isConstant() != DGV->isConstant() || 440 SGV->getInitializer() != DGV->getInitializer()) 441 return Error(Err, "Global Variable Collision on '" + 442 SGV->getType()->getDescription() + " %" + SGV->getName() + 443 "' - Global variables differ in const'ness"); 444 ValueMap.insert(std::make_pair(SGV, DGV)); 445 } else if (SGV->hasLinkOnceLinkage()) { 446 // If the global variable has a name, and that name is already in use in 447 // the Dest module, make sure that the name is a compatible global 448 // variable... 449 // 450 // Check to see if the two GV's have the same Const'ness... 451 if (SGV->isConstant() != DGV->isConstant()) 452 return Error(Err, "Global Variable Collision on '" + 453 SGV->getType()->getDescription() + " %" + SGV->getName() + 454 "' - Global variables differ in const'ness"); 455 456 // Okay, everything is cool, remember the mapping... 457 ValueMap.insert(std::make_pair(SGV, DGV)); 458 } else if (SGV->hasAppendingLinkage()) { 459 // No linking is performed yet. Just insert a new copy of the global, and 460 // keep track of the fact that it is an appending variable in the 461 // AppendingVars map. The name is cleared out so that no linkage is 462 // performed. 463 GlobalVariable *NewDGV = 464 new GlobalVariable(SGV->getType()->getElementType(), 465 SGV->isConstant(), SGV->getLinkage(), /*init*/0, 466 "", Dest); 467 468 // Make sure to remember this mapping... 469 ValueMap.insert(std::make_pair(SGV, NewDGV)); 470 471 // Keep track that this is an appending variable... 472 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV)); 473 } else { 474 assert(0 && "Unknown linkage!"); 475 } 476 } 477 return false; 478} 479 480 481// LinkGlobalInits - Update the initializers in the Dest module now that all 482// globals that may be referenced are in Dest. 483// 484static bool LinkGlobalInits(Module *Dest, const Module *Src, 485 std::map<const Value*, Value*> &ValueMap, 486 std::string *Err) { 487 488 // Loop over all of the globals in the src module, mapping them over as we go 489 // 490 for (Module::const_giterator I = Src->gbegin(), E = Src->gend(); I != E; ++I){ 491 const GlobalVariable *SGV = I; 492 493 if (SGV->hasInitializer()) { // Only process initialized GV's 494 // Figure out what the initializer looks like in the dest module... 495 Constant *SInit = 496 cast<Constant>(RemapOperand(SGV->getInitializer(), ValueMap, 0)); 497 498 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[SGV]); 499 if (DGV->hasInitializer()) { 500 assert(SGV->getLinkage() == DGV->getLinkage()); 501 if (SGV->hasExternalLinkage()) { 502 if (DGV->getInitializer() != SInit) 503 return Error(Err, "Global Variable Collision on '" + 504 SGV->getType()->getDescription() +"':%"+SGV->getName()+ 505 " - Global variables have different initializers"); 506 } else if (DGV->hasLinkOnceLinkage()) { 507 // Nothing is required, mapped values will take the new global 508 // automatically. 509 } else if (DGV->hasAppendingLinkage()) { 510 assert(0 && "Appending linkage unimplemented!"); 511 } else { 512 assert(0 && "Unknown linkage!"); 513 } 514 } else { 515 // Copy the initializer over now... 516 DGV->setInitializer(SInit); 517 } 518 } 519 } 520 return false; 521} 522 523// LinkFunctionProtos - Link the functions together between the two modules, 524// without doing function bodies... this just adds external function prototypes 525// to the Dest function... 526// 527static bool LinkFunctionProtos(Module *Dest, const Module *Src, 528 std::map<const Value*, Value*> &ValueMap, 529 std::string *Err) { 530 SymbolTable *ST = (SymbolTable*)&Dest->getSymbolTable(); 531 532 // Loop over all of the functions in the src module, mapping them over as we 533 // go 534 // 535 for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) { 536 const Function *SF = I; // SrcFunction 537 Function *DF = 0; 538 if (SF->hasName()) 539 // The same named thing is a Function, because the only two things 540 // that may be in a module level symbol table are Global Vars and 541 // Functions, and they both have distinct, nonoverlapping, possible types. 542 // 543 DF = cast_or_null<Function>(FindGlobalNamed(SF->getName(), SF->getType(), 544 ST)); 545 546 if (!DF || SF->hasInternalLinkage() || DF->hasInternalLinkage()) { 547 // Function does not already exist, simply insert an function signature 548 // identical to SF into the dest module... 549 Function *NewDF = new Function(SF->getFunctionType(), SF->getLinkage(), 550 SF->getName(), Dest); 551 552 // If the LLVM runtime renamed the function, but it is an externally 553 // visible symbol, DF must be an existing function with internal linkage. 554 // Rename it. 555 if (NewDF->getName() != SF->getName() && !NewDF->hasInternalLinkage()) { 556 assert(DF && DF->getName() == SF->getName() &&DF->hasInternalLinkage()); 557 DF->setName(""); 558 NewDF->setName(SF->getName()); // Force the name back 559 DF->setName(SF->getName()); // This will cause a renaming 560 assert(NewDF->getName() == SF->getName() && 561 DF->getName() != SF->getName()); 562 } 563 564 // ... and remember this mapping... 565 ValueMap.insert(std::make_pair(SF, NewDF)); 566 } else if (SF->isExternal()) { 567 // If SF is external or if both SF & DF are external.. Just link the 568 // external functions, we aren't adding anything. 569 ValueMap.insert(std::make_pair(SF, DF)); 570 } else if (DF->isExternal()) { // If DF is external but SF is not... 571 // Link the external functions, update linkage qualifiers 572 ValueMap.insert(std::make_pair(SF, DF)); 573 DF->setLinkage(SF->getLinkage()); 574 575 } else if (SF->getLinkage() != DF->getLinkage()) { 576 return Error(Err, "Functions named '" + SF->getName() + 577 "' have different linkage specifiers!"); 578 } else if (SF->hasExternalLinkage()) { 579 // The function is defined in both modules!! 580 return Error(Err, "Function '" + 581 SF->getFunctionType()->getDescription() + "':\"" + 582 SF->getName() + "\" - Function is already defined!"); 583 } else if (SF->hasLinkOnceLinkage()) { 584 // Completely ignore the source function. 585 ValueMap.insert(std::make_pair(SF, DF)); 586 } else { 587 assert(0 && "Unknown linkage configuration found!"); 588 } 589 } 590 return false; 591} 592 593// LinkFunctionBody - Copy the source function over into the dest function and 594// fix up references to values. At this point we know that Dest is an external 595// function, and that Src is not. 596// 597static bool LinkFunctionBody(Function *Dest, const Function *Src, 598 std::map<const Value*, Value*> &GlobalMap, 599 std::string *Err) { 600 assert(Src && Dest && Dest->isExternal() && !Src->isExternal()); 601 std::map<const Value*, Value*> LocalMap; // Map for function local values 602 603 // Go through and convert function arguments over... 604 Function::aiterator DI = Dest->abegin(); 605 for (Function::const_aiterator I = Src->abegin(), E = Src->aend(); 606 I != E; ++I, ++DI) { 607 DI->setName(I->getName()); // Copy the name information over... 608 609 // Add a mapping to our local map 610 LocalMap.insert(std::make_pair(I, DI)); 611 } 612 613 // Loop over all of the basic blocks, copying the instructions over... 614 // 615 for (Function::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) { 616 // Create new basic block and add to mapping and the Dest function... 617 BasicBlock *DBB = new BasicBlock(I->getName(), Dest); 618 LocalMap.insert(std::make_pair(I, DBB)); 619 620 // Loop over all of the instructions in the src basic block, copying them 621 // over. Note that this is broken in a strict sense because the cloned 622 // instructions will still be referencing values in the Src module, not 623 // the remapped values. In our case, however, we will not get caught and 624 // so we can delay patching the values up until later... 625 // 626 for (BasicBlock::const_iterator II = I->begin(), IE = I->end(); 627 II != IE; ++II) { 628 Instruction *DI = II->clone(); 629 DI->setName(II->getName()); 630 DBB->getInstList().push_back(DI); 631 LocalMap.insert(std::make_pair(II, DI)); 632 } 633 } 634 635 // At this point, all of the instructions and values of the function are now 636 // copied over. The only problem is that they are still referencing values in 637 // the Source function as operands. Loop through all of the operands of the 638 // functions and patch them up to point to the local versions... 639 // 640 for (Function::iterator BB = Dest->begin(), BE = Dest->end(); BB != BE; ++BB) 641 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) 642 for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end(); 643 OI != OE; ++OI) 644 *OI = RemapOperand(*OI, LocalMap, &GlobalMap); 645 646 return false; 647} 648 649 650// LinkFunctionBodies - Link in the function bodies that are defined in the 651// source module into the DestModule. This consists basically of copying the 652// function over and fixing up references to values. 653// 654static bool LinkFunctionBodies(Module *Dest, const Module *Src, 655 std::map<const Value*, Value*> &ValueMap, 656 std::string *Err) { 657 658 // Loop over all of the functions in the src module, mapping them over as we 659 // go 660 // 661 for (Module::const_iterator SF = Src->begin(), E = Src->end(); SF != E; ++SF){ 662 if (!SF->isExternal()) { // No body if function is external 663 Function *DF = cast<Function>(ValueMap[SF]); // Destination function 664 665 // DF not external SF external? 666 if (!DF->isExternal()) { 667 if (DF->hasLinkOnceLinkage()) continue; // No relinkage for link-once! 668 if (Err) 669 *Err = "Function '" + (SF->hasName() ? SF->getName() :std::string("")) 670 + "' body multiply defined!"; 671 return true; 672 } 673 674 if (LinkFunctionBody(DF, SF, ValueMap, Err)) return true; 675 } 676 } 677 return false; 678} 679 680// LinkAppendingVars - If there were any appending global variables, link them 681// together now. Return true on error. 682// 683static bool LinkAppendingVars(Module *M, 684 std::multimap<std::string, GlobalVariable *> &AppendingVars, 685 std::string *ErrorMsg) { 686 if (AppendingVars.empty()) return false; // Nothing to do. 687 688 // Loop over the multimap of appending vars, processing any variables with the 689 // same name, forming a new appending global variable with both of the 690 // initializers merged together, then rewrite references to the old variables 691 // and delete them. 692 // 693 std::vector<Constant*> Inits; 694 while (AppendingVars.size() > 1) { 695 // Get the first two elements in the map... 696 std::multimap<std::string, 697 GlobalVariable*>::iterator Second = AppendingVars.begin(), First=Second++; 698 699 // If the first two elements are for different names, there is no pair... 700 // Otherwise there is a pair, so link them together... 701 if (First->first == Second->first) { 702 GlobalVariable *G1 = First->second, *G2 = Second->second; 703 const ArrayType *T1 = cast<ArrayType>(G1->getType()->getElementType()); 704 const ArrayType *T2 = cast<ArrayType>(G2->getType()->getElementType()); 705 706 // Check to see that they two arrays agree on type... 707 if (T1->getElementType() != T2->getElementType()) 708 return Error(ErrorMsg, 709 "Appending variables with different element types need to be linked!"); 710 if (G1->isConstant() != G2->isConstant()) 711 return Error(ErrorMsg, 712 "Appending variables linked with different const'ness!"); 713 714 unsigned NewSize = T1->getNumElements() + T2->getNumElements(); 715 ArrayType *NewType = ArrayType::get(T1->getElementType(), NewSize); 716 717 // Create the new global variable... 718 GlobalVariable *NG = 719 new GlobalVariable(NewType, G1->isConstant(), G1->getLinkage(), 720 /*init*/0, First->first, M); 721 722 // Merge the initializer... 723 Inits.reserve(NewSize); 724 ConstantArray *I = cast<ConstantArray>(G1->getInitializer()); 725 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i) 726 Inits.push_back(cast<Constant>(I->getValues()[i])); 727 I = cast<ConstantArray>(G2->getInitializer()); 728 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i) 729 Inits.push_back(cast<Constant>(I->getValues()[i])); 730 NG->setInitializer(ConstantArray::get(NewType, Inits)); 731 Inits.clear(); 732 733 // Replace any uses of the two global variables with uses of the new 734 // global... 735 736 // FIXME: This should rewrite simple/straight-forward uses such as 737 // getelementptr instructions to not use the Cast! 738 ConstantPointerRef *NGCP = ConstantPointerRef::get(NG); 739 G1->replaceAllUsesWith(ConstantExpr::getCast(NGCP, G1->getType())); 740 G2->replaceAllUsesWith(ConstantExpr::getCast(NGCP, G2->getType())); 741 742 // Remove the two globals from the module now... 743 M->getGlobalList().erase(G1); 744 M->getGlobalList().erase(G2); 745 746 // Put the new global into the AppendingVars map so that we can handle 747 // linking of more than two vars... 748 Second->second = NG; 749 } 750 AppendingVars.erase(First); 751 } 752 753 return false; 754} 755 756 757// LinkModules - This function links two modules together, with the resulting 758// left module modified to be the composite of the two input modules. If an 759// error occurs, true is returned and ErrorMsg (if not null) is set to indicate 760// the problem. Upon failure, the Dest module could be in a modified state, and 761// shouldn't be relied on to be consistent. 762// 763bool LinkModules(Module *Dest, const Module *Src, std::string *ErrorMsg) { 764 if (Dest->getEndianness() != Src->getEndianness()) 765 std::cerr << "WARNING: Linking two modules of different endianness!\n"; 766 if (Dest->getPointerSize() != Src->getPointerSize()) 767 std::cerr << "WARNING: Linking two modules of different pointer size!\n"; 768 769 // LinkTypes - Go through the symbol table of the Src module and see if any 770 // types are named in the src module that are not named in the Dst module. 771 // Make sure there are no type name conflicts. 772 // 773 if (LinkTypes(Dest, Src, ErrorMsg)) return true; 774 775 // ValueMap - Mapping of values from what they used to be in Src, to what they 776 // are now in Dest. 777 // 778 std::map<const Value*, Value*> ValueMap; 779 780 // AppendingVars - Keep track of global variables in the destination module 781 // with appending linkage. After the module is linked together, they are 782 // appended and the module is rewritten. 783 // 784 std::multimap<std::string, GlobalVariable *> AppendingVars; 785 786 // Add all of the appending globals already in the Dest module to 787 // AppendingVars. 788 for (Module::giterator I = Dest->gbegin(), E = Dest->gend(); I != E; ++I) 789 if (I->hasAppendingLinkage()) 790 AppendingVars.insert(std::make_pair(I->getName(), I)); 791 792 // Insert all of the globals in src into the Dest module... without linking 793 // initializers (which could refer to functions not yet mapped over). 794 // 795 if (LinkGlobals(Dest, Src, ValueMap, AppendingVars, ErrorMsg)) return true; 796 797 // Link the functions together between the two modules, without doing function 798 // bodies... this just adds external function prototypes to the Dest 799 // function... We do this so that when we begin processing function bodies, 800 // all of the global values that may be referenced are available in our 801 // ValueMap. 802 // 803 if (LinkFunctionProtos(Dest, Src, ValueMap, ErrorMsg)) return true; 804 805 // Update the initializers in the Dest module now that all globals that may 806 // be referenced are in Dest. 807 // 808 if (LinkGlobalInits(Dest, Src, ValueMap, ErrorMsg)) return true; 809 810 // Link in the function bodies that are defined in the source module into the 811 // DestModule. This consists basically of copying the function over and 812 // fixing up references to values. 813 // 814 if (LinkFunctionBodies(Dest, Src, ValueMap, ErrorMsg)) return true; 815 816 // If there were any appending global variables, link them together now. 817 // 818 if (LinkAppendingVars(Dest, AppendingVars, ErrorMsg)) return true; 819 820 return false; 821} 822 823