LinkModules.cpp revision 1a1d485363e82e2d5f2442b2abcc1cc204ca58cf
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//===----------------------------------------------------------------------===// 13 14#include "llvm/Linker.h" 15#include "llvm/Constants.h" 16#include "llvm/DerivedTypes.h" 17#include "llvm/Instructions.h" 18#include "llvm/Module.h" 19#include "llvm/ADT/SmallPtrSet.h" 20#include "llvm/Support/raw_ostream.h" 21#include "llvm/Support/Path.h" 22#include "llvm/Transforms/Utils/Cloning.h" 23#include "llvm/Transforms/Utils/ValueMapper.h" 24using namespace llvm; 25 26//===----------------------------------------------------------------------===// 27// TypeMap implementation. 28//===----------------------------------------------------------------------===// 29 30namespace { 31class TypeMapTy : public ValueMapTypeRemapper { 32 /// MappedTypes - This is a mapping from a source type to a destination type 33 /// to use. 34 DenseMap<Type*, Type*> MappedTypes; 35 36 /// SpeculativeTypes - When checking to see if two subgraphs are isomorphic, 37 /// we speculatively add types to MappedTypes, but keep track of them here in 38 /// case we need to roll back. 39 SmallVector<Type*, 16> SpeculativeTypes; 40 41 /// DefinitionsToResolve - This is a list of non-opaque structs in the source 42 /// module that are mapped to an opaque struct in the destination module. 43 SmallVector<StructType*, 16> DefinitionsToResolve; 44public: 45 46 /// addTypeMapping - Indicate that the specified type in the destination 47 /// module is conceptually equivalent to the specified type in the source 48 /// module. 49 void addTypeMapping(Type *DstTy, Type *SrcTy); 50 51 /// linkDefinedTypeBodies - Produce a body for an opaque type in the dest 52 /// module from a type definition in the source module. 53 void linkDefinedTypeBodies(); 54 55 /// get - Return the mapped type to use for the specified input type from the 56 /// source module. 57 Type *get(Type *SrcTy); 58 59 FunctionType *get(FunctionType *T) {return cast<FunctionType>(get((Type*)T));} 60 61private: 62 Type *getImpl(Type *T); 63 /// remapType - Implement the ValueMapTypeRemapper interface. 64 Type *remapType(Type *SrcTy) { 65 return get(SrcTy); 66 } 67 68 bool areTypesIsomorphic(Type *DstTy, Type *SrcTy); 69}; 70} 71 72void TypeMapTy::addTypeMapping(Type *DstTy, Type *SrcTy) { 73 Type *&Entry = MappedTypes[SrcTy]; 74 if (Entry) return; 75 76 if (DstTy == SrcTy) { 77 Entry = DstTy; 78 return; 79 } 80 81 // Check to see if these types are recursively isomorphic and establish a 82 // mapping between them if so. 83 if (!areTypesIsomorphic(DstTy, SrcTy)) { 84 // Oops, they aren't isomorphic. Just discard this request by rolling out 85 // any speculative mappings we've established. 86 for (unsigned i = 0, e = SpeculativeTypes.size(); i != e; ++i) 87 MappedTypes.erase(SpeculativeTypes[i]); 88 } 89 SpeculativeTypes.clear(); 90} 91 92/// areTypesIsomorphic - Recursively walk this pair of types, returning true 93/// if they are isomorphic, false if they are not. 94bool TypeMapTy::areTypesIsomorphic(Type *DstTy, Type *SrcTy) { 95 // Two types with differing kinds are clearly not isomorphic. 96 if (DstTy->getTypeID() != SrcTy->getTypeID()) return false; 97 98 // If we have an entry in the MappedTypes table, then we have our answer. 99 Type *&Entry = MappedTypes[SrcTy]; 100 if (Entry) 101 return Entry == DstTy; 102 103 // Two identical types are clearly isomorphic. Remember this 104 // non-speculatively. 105 if (DstTy == SrcTy) { 106 Entry = DstTy; 107 return true; 108 } 109 110 // Okay, we have two types with identical kinds that we haven't seen before. 111 112 // If this is an opaque struct type, special case it. 113 if (StructType *SSTy = dyn_cast<StructType>(SrcTy)) { 114 // Mapping an opaque type to any struct, just keep the dest struct. 115 if (SSTy->isOpaque()) { 116 Entry = DstTy; 117 SpeculativeTypes.push_back(SrcTy); 118 return true; 119 } 120 121 // Mapping a non-opaque source type to an opaque dest. Keep the dest, but 122 // fill it in later. This doesn't need to be speculative. 123 if (cast<StructType>(DstTy)->isOpaque()) { 124 Entry = DstTy; 125 DefinitionsToResolve.push_back(SSTy); 126 return true; 127 } 128 } 129 130 // If the number of subtypes disagree between the two types, then we fail. 131 if (SrcTy->getNumContainedTypes() != DstTy->getNumContainedTypes()) 132 return false; 133 134 // Fail if any of the extra properties (e.g. array size) of the type disagree. 135 if (isa<IntegerType>(DstTy)) 136 return false; // bitwidth disagrees. 137 if (PointerType *PT = dyn_cast<PointerType>(DstTy)) { 138 if (PT->getAddressSpace() != cast<PointerType>(SrcTy)->getAddressSpace()) 139 return false; 140 } else if (FunctionType *FT = dyn_cast<FunctionType>(DstTy)) { 141 if (FT->isVarArg() != cast<FunctionType>(SrcTy)->isVarArg()) 142 return false; 143 } else if (StructType *DSTy = dyn_cast<StructType>(DstTy)) { 144 StructType *SSTy = cast<StructType>(SrcTy); 145 if (DSTy->isLiteral() != SSTy->isLiteral() || 146 DSTy->isPacked() != SSTy->isPacked()) 147 return false; 148 } else if (ArrayType *DATy = dyn_cast<ArrayType>(DstTy)) { 149 if (DATy->getNumElements() != cast<ArrayType>(SrcTy)->getNumElements()) 150 return false; 151 } else if (VectorType *DVTy = dyn_cast<VectorType>(DstTy)) { 152 if (DVTy->getNumElements() != cast<ArrayType>(SrcTy)->getNumElements()) 153 return false; 154 } 155 156 // Otherwise, we speculate that these two types will line up and recursively 157 // check the subelements. 158 Entry = DstTy; 159 SpeculativeTypes.push_back(SrcTy); 160 161 for (unsigned i = 0, e = SrcTy->getNumContainedTypes(); i != e; ++i) 162 if (!areTypesIsomorphic(DstTy->getContainedType(i), 163 SrcTy->getContainedType(i))) 164 return false; 165 166 // If everything seems to have lined up, then everything is great. 167 return true; 168} 169 170/// linkDefinedTypeBodies - Produce a body for an opaque type in the dest 171/// module from a type definition in the source module. 172void TypeMapTy::linkDefinedTypeBodies() { 173 SmallVector<Type*, 16> Elements; 174 SmallString<16> TmpName; 175 176 // Note that processing entries in this loop (calling 'get') can add new 177 // entries to the DefinitionsToResolve vector. 178 while (!DefinitionsToResolve.empty()) { 179 StructType *SrcSTy = DefinitionsToResolve.pop_back_val(); 180 StructType *DstSTy = cast<StructType>(MappedTypes[SrcSTy]); 181 182 // TypeMap is a many-to-one mapping, if there were multiple types that 183 // provide a body for DstSTy then previous iterations of this loop may have 184 // already handled it. Just ignore this case. 185 if (!DstSTy->isOpaque()) continue; 186 assert(!SrcSTy->isOpaque() && "Not resolving a definition?"); 187 188 // Map the body of the source type over to a new body for the dest type. 189 Elements.resize(SrcSTy->getNumElements()); 190 for (unsigned i = 0, e = Elements.size(); i != e; ++i) 191 Elements[i] = getImpl(SrcSTy->getElementType(i)); 192 193 DstSTy->setBody(Elements, SrcSTy->isPacked()); 194 195 // If DstSTy has no name or has a longer name than STy, then viciously steal 196 // STy's name. 197 if (!SrcSTy->hasName()) continue; 198 StringRef SrcName = SrcSTy->getName(); 199 200 if (!DstSTy->hasName() || DstSTy->getName().size() > SrcName.size()) { 201 TmpName.insert(TmpName.end(), SrcName.begin(), SrcName.end()); 202 SrcSTy->setName(""); 203 DstSTy->setName(TmpName.str()); 204 TmpName.clear(); 205 } 206 } 207} 208 209 210/// get - Return the mapped type to use for the specified input type from the 211/// source module. 212Type *TypeMapTy::get(Type *Ty) { 213 Type *Result = getImpl(Ty); 214 215 // If this caused a reference to any struct type, resolve it before returning. 216 if (!DefinitionsToResolve.empty()) 217 linkDefinedTypeBodies(); 218 return Result; 219} 220 221/// getImpl - This is the recursive version of get(). 222Type *TypeMapTy::getImpl(Type *Ty) { 223 // If we already have an entry for this type, return it. 224 Type **Entry = &MappedTypes[Ty]; 225 if (*Entry) return *Entry; 226 227 // If this is not a named struct type, then just map all of the elements and 228 // then rebuild the type from inside out. 229 if (!isa<StructType>(Ty) || cast<StructType>(Ty)->isLiteral()) { 230 // If there are no element types to map, then the type is itself. This is 231 // true for the anonymous {} struct, things like 'float', integers, etc. 232 if (Ty->getNumContainedTypes() == 0) 233 return *Entry = Ty; 234 235 // Remap all of the elements, keeping track of whether any of them change. 236 bool AnyChange = false; 237 SmallVector<Type*, 4> ElementTypes; 238 ElementTypes.resize(Ty->getNumContainedTypes()); 239 for (unsigned i = 0, e = Ty->getNumContainedTypes(); i != e; ++i) { 240 ElementTypes[i] = getImpl(Ty->getContainedType(i)); 241 AnyChange |= ElementTypes[i] != Ty->getContainedType(i); 242 } 243 244 // If we found our type while recursively processing stuff, just use it. 245 Entry = &MappedTypes[Ty]; 246 if (*Entry) return *Entry; 247 248 // If all of the element types mapped directly over, then the type is usable 249 // as-is. 250 if (!AnyChange) 251 return *Entry = Ty; 252 253 // Otherwise, rebuild a modified type. 254 switch (Ty->getTypeID()) { 255 default: assert(0 && "unknown derived type to remap"); 256 case Type::ArrayTyID: 257 return *Entry = ArrayType::get(ElementTypes[0], 258 cast<ArrayType>(Ty)->getNumElements()); 259 case Type::VectorTyID: 260 return *Entry = VectorType::get(ElementTypes[0], 261 cast<VectorType>(Ty)->getNumElements()); 262 case Type::PointerTyID: 263 return *Entry = PointerType::get(ElementTypes[0], 264 cast<PointerType>(Ty)->getAddressSpace()); 265 case Type::FunctionTyID: 266 return *Entry = FunctionType::get(ElementTypes[0], 267 makeArrayRef(ElementTypes).slice(1), 268 cast<FunctionType>(Ty)->isVarArg()); 269 case Type::StructTyID: 270 // Note that this is only reached for anonymous structs. 271 return *Entry = StructType::get(Ty->getContext(), ElementTypes, 272 cast<StructType>(Ty)->isPacked()); 273 } 274 } 275 276 // Otherwise, this is an unmapped named struct. If the struct can be directly 277 // mapped over, just use it as-is. This happens in a case when the linked-in 278 // module has something like: 279 // %T = type {%T*, i32} 280 // @GV = global %T* null 281 // where T does not exist at all in the destination module. 282 // 283 // The other case we watch for is when the type is not in the destination 284 // module, but that it has to be rebuilt because it refers to something that 285 // is already mapped. For example, if the destination module has: 286 // %A = type { i32 } 287 // and the source module has something like 288 // %A' = type { i32 } 289 // %B = type { %A'* } 290 // @GV = global %B* null 291 // then we want to create a new type: "%B = type { %A*}" and have it take the 292 // pristine "%B" name from the source module. 293 // 294 // To determine which case this is, we have to recursively walk the type graph 295 // speculating that we'll be able to reuse it unmodified. Only if this is 296 // safe would we map the entire thing over. Because this is an optimization, 297 // and is not required for the prettiness of the linked module, we just skip 298 // it and always rebuild a type here. 299 StructType *STy = cast<StructType>(Ty); 300 301 // If the type is opaque, we can just use it directly. 302 if (STy->isOpaque()) 303 return *Entry = STy; 304 305 // Otherwise we create a new type and resolve its body later. This will be 306 // resolved by the top level of get(). 307 DefinitionsToResolve.push_back(STy); 308 return *Entry = StructType::create(STy->getContext()); 309} 310 311 312 313//===----------------------------------------------------------------------===// 314// ModuleLinker implementation. 315//===----------------------------------------------------------------------===// 316 317namespace { 318 /// ModuleLinker - This is an implementation class for the LinkModules 319 /// function, which is the entrypoint for this file. 320 class ModuleLinker { 321 Module *DstM, *SrcM; 322 323 TypeMapTy TypeMap; 324 325 /// ValueMap - Mapping of values from what they used to be in Src, to what 326 /// they are now in DstM. ValueToValueMapTy is a ValueMap, which involves 327 /// some overhead due to the use of Value handles which the Linker doesn't 328 /// actually need, but this allows us to reuse the ValueMapper code. 329 ValueToValueMapTy ValueMap; 330 331 struct AppendingVarInfo { 332 GlobalVariable *NewGV; // New aggregate global in dest module. 333 Constant *DstInit; // Old initializer from dest module. 334 Constant *SrcInit; // Old initializer from src module. 335 }; 336 337 std::vector<AppendingVarInfo> AppendingVars; 338 339 unsigned Mode; // Mode to treat source module. 340 341 // Set of items not to link in from source. 342 SmallPtrSet<const Value*, 16> DoNotLinkFromSource; 343 344 // Vector of functions to lazily link in. 345 std::vector<Function*> LazilyLinkFunctions; 346 347 public: 348 std::string ErrorMsg; 349 350 ModuleLinker(Module *dstM, Module *srcM, unsigned mode) 351 : DstM(dstM), SrcM(srcM), Mode(mode) { } 352 353 bool run(); 354 355 private: 356 /// emitError - Helper method for setting a message and returning an error 357 /// code. 358 bool emitError(const Twine &Message) { 359 ErrorMsg = Message.str(); 360 return true; 361 } 362 363 /// getLinkageResult - This analyzes the two global values and determines 364 /// what the result will look like in the destination module. 365 bool getLinkageResult(GlobalValue *Dest, const GlobalValue *Src, 366 GlobalValue::LinkageTypes <, bool &LinkFromSrc); 367 368 /// getLinkedToGlobal - Given a global in the source module, return the 369 /// global in the destination module that is being linked to, if any. 370 GlobalValue *getLinkedToGlobal(GlobalValue *SrcGV) { 371 // If the source has no name it can't link. If it has local linkage, 372 // there is no name match-up going on. 373 if (!SrcGV->hasName() || SrcGV->hasLocalLinkage()) 374 return 0; 375 376 // Otherwise see if we have a match in the destination module's symtab. 377 GlobalValue *DGV = DstM->getNamedValue(SrcGV->getName()); 378 if (DGV == 0) return 0; 379 380 // If we found a global with the same name in the dest module, but it has 381 // internal linkage, we are really not doing any linkage here. 382 if (DGV->hasLocalLinkage()) 383 return 0; 384 385 // Otherwise, we do in fact link to the destination global. 386 return DGV; 387 } 388 389 void computeTypeMapping(); 390 391 bool linkAppendingVarProto(GlobalVariable *DstGV, GlobalVariable *SrcGV); 392 bool linkGlobalProto(GlobalVariable *SrcGV); 393 bool linkFunctionProto(Function *SrcF); 394 bool linkAliasProto(GlobalAlias *SrcA); 395 396 void linkAppendingVarInit(const AppendingVarInfo &AVI); 397 void linkGlobalInits(); 398 void linkFunctionBody(Function *Dst, Function *Src); 399 void linkAliasBodies(); 400 void linkNamedMDNodes(); 401 }; 402} 403 404 405 406/// forceRenaming - The LLVM SymbolTable class autorenames globals that conflict 407/// in the symbol table. This is good for all clients except for us. Go 408/// through the trouble to force this back. 409static void forceRenaming(GlobalValue *GV, StringRef Name) { 410 // If the global doesn't force its name or if it already has the right name, 411 // there is nothing for us to do. 412 if (GV->hasLocalLinkage() || GV->getName() == Name) 413 return; 414 415 Module *M = GV->getParent(); 416 417 // If there is a conflict, rename the conflict. 418 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) { 419 GV->takeName(ConflictGV); 420 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed 421 assert(ConflictGV->getName() != Name && "forceRenaming didn't work"); 422 } else { 423 GV->setName(Name); // Force the name back 424 } 425} 426 427/// CopyGVAttributes - copy additional attributes (those not needed to construct 428/// a GlobalValue) from the SrcGV to the DestGV. 429static void CopyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) { 430 // Use the maximum alignment, rather than just copying the alignment of SrcGV. 431 unsigned Alignment = std::max(DestGV->getAlignment(), SrcGV->getAlignment()); 432 DestGV->copyAttributesFrom(SrcGV); 433 DestGV->setAlignment(Alignment); 434 435 forceRenaming(DestGV, SrcGV->getName()); 436} 437 438/// getLinkageResult - This analyzes the two global values and determines what 439/// the result will look like in the destination module. In particular, it 440/// computes the resultant linkage type, computes whether the global in the 441/// source should be copied over to the destination (replacing the existing 442/// one), and computes whether this linkage is an error or not. It also performs 443/// visibility checks: we cannot link together two symbols with different 444/// visibilities. 445bool ModuleLinker::getLinkageResult(GlobalValue *Dest, const GlobalValue *Src, 446 GlobalValue::LinkageTypes <, 447 bool &LinkFromSrc) { 448 assert(Dest && "Must have two globals being queried"); 449 assert(!Src->hasLocalLinkage() && 450 "If Src has internal linkage, Dest shouldn't be set!"); 451 452 bool SrcIsDeclaration = Src->isDeclaration() && !Src->isMaterializable(); 453 bool DestIsDeclaration = Dest->isDeclaration(); 454 455 if (SrcIsDeclaration) { 456 // If Src is external or if both Src & Dest are external.. Just link the 457 // external globals, we aren't adding anything. 458 if (Src->hasDLLImportLinkage()) { 459 // If one of GVs has DLLImport linkage, result should be dllimport'ed. 460 if (DestIsDeclaration) { 461 LinkFromSrc = true; 462 LT = Src->getLinkage(); 463 } 464 } else if (Dest->hasExternalWeakLinkage()) { 465 // If the Dest is weak, use the source linkage. 466 LinkFromSrc = true; 467 LT = Src->getLinkage(); 468 } else { 469 LinkFromSrc = false; 470 LT = Dest->getLinkage(); 471 } 472 } else if (DestIsDeclaration && !Dest->hasDLLImportLinkage()) { 473 // If Dest is external but Src is not: 474 LinkFromSrc = true; 475 LT = Src->getLinkage(); 476 } else if (Src->isWeakForLinker()) { 477 // At this point we know that Dest has LinkOnce, External*, Weak, Common, 478 // or DLL* linkage. 479 if (Dest->hasExternalWeakLinkage() || 480 Dest->hasAvailableExternallyLinkage() || 481 (Dest->hasLinkOnceLinkage() && 482 (Src->hasWeakLinkage() || Src->hasCommonLinkage()))) { 483 LinkFromSrc = true; 484 LT = Src->getLinkage(); 485 } else { 486 LinkFromSrc = false; 487 LT = Dest->getLinkage(); 488 } 489 } else if (Dest->isWeakForLinker()) { 490 // At this point we know that Src has External* or DLL* linkage. 491 if (Src->hasExternalWeakLinkage()) { 492 LinkFromSrc = false; 493 LT = Dest->getLinkage(); 494 } else { 495 LinkFromSrc = true; 496 LT = GlobalValue::ExternalLinkage; 497 } 498 } else { 499 assert((Dest->hasExternalLinkage() || Dest->hasDLLImportLinkage() || 500 Dest->hasDLLExportLinkage() || Dest->hasExternalWeakLinkage()) && 501 (Src->hasExternalLinkage() || Src->hasDLLImportLinkage() || 502 Src->hasDLLExportLinkage() || Src->hasExternalWeakLinkage()) && 503 "Unexpected linkage type!"); 504 return emitError("Linking globals named '" + Src->getName() + 505 "': symbol multiply defined!"); 506 } 507 508 // Check visibility 509 if (Src->getVisibility() != Dest->getVisibility() && 510 !SrcIsDeclaration && !DestIsDeclaration && 511 !Src->hasAvailableExternallyLinkage() && 512 !Dest->hasAvailableExternallyLinkage()) 513 return emitError("Linking globals named '" + Src->getName() + 514 "': symbols have different visibilities!"); 515 return false; 516} 517 518/// computeTypeMapping - Loop over all of the linked values to compute type 519/// mappings. For example, if we link "extern Foo *x" and "Foo *x = NULL", then 520/// we have two struct types 'Foo' but one got renamed when the module was 521/// loaded into the same LLVMContext. 522void ModuleLinker::computeTypeMapping() { 523 // Incorporate globals. 524 for (Module::global_iterator I = SrcM->global_begin(), 525 E = SrcM->global_end(); I != E; ++I) { 526 GlobalValue *DGV = getLinkedToGlobal(I); 527 if (DGV == 0) continue; 528 529 if (!DGV->hasAppendingLinkage() || !I->hasAppendingLinkage()) { 530 TypeMap.addTypeMapping(DGV->getType(), I->getType()); 531 continue; 532 } 533 534 // Unify the element type of appending arrays. 535 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType()); 536 ArrayType *SAT = cast<ArrayType>(I->getType()->getElementType()); 537 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType()); 538 } 539 540 // Incorporate functions. 541 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I) { 542 if (GlobalValue *DGV = getLinkedToGlobal(I)) 543 TypeMap.addTypeMapping(DGV->getType(), I->getType()); 544 } 545 546 // Don't bother incorporating aliases, they aren't generally typed well. 547 548 // Now that we have discovered all of the type equivalences, get a body for 549 // any 'opaque' types in the dest module that are now resolved. 550 TypeMap.linkDefinedTypeBodies(); 551} 552 553/// linkAppendingVarProto - If there were any appending global variables, link 554/// them together now. Return true on error. 555bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV, 556 GlobalVariable *SrcGV) { 557 558 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage()) 559 return emitError("Linking globals named '" + SrcGV->getName() + 560 "': can only link appending global with another appending global!"); 561 562 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType()); 563 ArrayType *SrcTy = 564 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType())); 565 Type *EltTy = DstTy->getElementType(); 566 567 // Check to see that they two arrays agree on type. 568 if (EltTy != SrcTy->getElementType()) 569 return emitError("Appending variables with different element types!"); 570 if (DstGV->isConstant() != SrcGV->isConstant()) 571 return emitError("Appending variables linked with different const'ness!"); 572 573 if (DstGV->getAlignment() != SrcGV->getAlignment()) 574 return emitError( 575 "Appending variables with different alignment need to be linked!"); 576 577 if (DstGV->getVisibility() != SrcGV->getVisibility()) 578 return emitError( 579 "Appending variables with different visibility need to be linked!"); 580 581 if (DstGV->getSection() != SrcGV->getSection()) 582 return emitError( 583 "Appending variables with different section name need to be linked!"); 584 585 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements(); 586 ArrayType *NewType = ArrayType::get(EltTy, NewSize); 587 588 // Create the new global variable. 589 GlobalVariable *NG = 590 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(), 591 DstGV->getLinkage(), /*init*/0, /*name*/"", DstGV, 592 DstGV->isThreadLocal(), 593 DstGV->getType()->getAddressSpace()); 594 595 // Propagate alignment, visibility and section info. 596 CopyGVAttributes(NG, DstGV); 597 598 AppendingVarInfo AVI; 599 AVI.NewGV = NG; 600 AVI.DstInit = DstGV->getInitializer(); 601 AVI.SrcInit = SrcGV->getInitializer(); 602 AppendingVars.push_back(AVI); 603 604 // Replace any uses of the two global variables with uses of the new 605 // global. 606 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType())); 607 608 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType())); 609 DstGV->eraseFromParent(); 610 611 // Track the source variable so we don't try to link it. 612 DoNotLinkFromSource.insert(SrcGV); 613 614 return false; 615} 616 617/// linkGlobalProto - Loop through the global variables in the src module and 618/// merge them into the dest module. 619bool ModuleLinker::linkGlobalProto(GlobalVariable *SGV) { 620 GlobalValue *DGV = getLinkedToGlobal(SGV); 621 622 if (DGV) { 623 // Concatenation of appending linkage variables is magic and handled later. 624 if (DGV->hasAppendingLinkage() || SGV->hasAppendingLinkage()) 625 return linkAppendingVarProto(cast<GlobalVariable>(DGV), SGV); 626 627 // Determine whether linkage of these two globals follows the source 628 // module's definition or the destination module's definition. 629 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 630 bool LinkFromSrc = false; 631 if (getLinkageResult(DGV, SGV, NewLinkage, LinkFromSrc)) 632 return true; 633 634 // If we're not linking from the source, then keep the definition that we 635 // have. 636 if (!LinkFromSrc) { 637 // Special case for const propagation. 638 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) 639 if (DGVar->isDeclaration() && SGV->isConstant() && !DGVar->isConstant()) 640 DGVar->setConstant(true); 641 642 // Set calculated linkage. 643 DGV->setLinkage(NewLinkage); 644 645 // Make sure to remember this mapping. 646 ValueMap[SGV] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGV->getType())); 647 648 // Track the source global so that we don't attempt to copy it over when 649 // processing global initializers. 650 DoNotLinkFromSource.insert(SGV); 651 652 return false; 653 } 654 } 655 656 // No linking to be performed or linking from the source: simply create an 657 // identical version of the symbol over in the dest module... the 658 // initializer will be filled in later by LinkGlobalInits. 659 GlobalVariable *NewDGV = 660 new GlobalVariable(*DstM, TypeMap.get(SGV->getType()->getElementType()), 661 SGV->isConstant(), SGV->getLinkage(), /*init*/0, 662 SGV->getName(), /*insertbefore*/0, 663 SGV->isThreadLocal(), 664 SGV->getType()->getAddressSpace()); 665 // Propagate alignment, visibility and section info. 666 CopyGVAttributes(NewDGV, SGV); 667 668 if (DGV) { 669 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV, DGV->getType())); 670 DGV->eraseFromParent(); 671 } 672 673 // Make sure to remember this mapping. 674 ValueMap[SGV] = NewDGV; 675 return false; 676} 677 678/// linkFunctionProto - Link the function in the source module into the 679/// destination module if needed, setting up mapping information. 680bool ModuleLinker::linkFunctionProto(Function *SF) { 681 GlobalValue *DGV = getLinkedToGlobal(SF); 682 683 if (DGV) { 684 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 685 bool LinkFromSrc = false; 686 if (getLinkageResult(DGV, SF, NewLinkage, LinkFromSrc)) 687 return true; 688 689 if (!LinkFromSrc) { 690 // Set calculated linkage 691 DGV->setLinkage(NewLinkage); 692 693 // Make sure to remember this mapping. 694 ValueMap[SF] = ConstantExpr::getBitCast(DGV, TypeMap.get(SF->getType())); 695 696 // Track the function from the source module so we don't attempt to remap 697 // it. 698 DoNotLinkFromSource.insert(SF); 699 700 return false; 701 } 702 } 703 704 // If there is no linkage to be performed or we are linking from the source, 705 // bring SF over. 706 Function *NewDF = Function::Create(TypeMap.get(SF->getFunctionType()), 707 SF->getLinkage(), SF->getName(), DstM); 708 CopyGVAttributes(NewDF, SF); 709 710 if (DGV) { 711 // Any uses of DF need to change to NewDF, with cast. 712 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, DGV->getType())); 713 DGV->eraseFromParent(); 714 } else { 715 // Internal, LO_ODR, or LO linkage - stick in set to ignore and lazily link. 716 if (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() || 717 SF->hasAvailableExternallyLinkage()) { 718 DoNotLinkFromSource.insert(SF); 719 LazilyLinkFunctions.push_back(SF); 720 } 721 } 722 723 ValueMap[SF] = NewDF; 724 return false; 725} 726 727/// LinkAliasProto - Set up prototypes for any aliases that come over from the 728/// source module. 729bool ModuleLinker::linkAliasProto(GlobalAlias *SGA) { 730 GlobalValue *DGV = getLinkedToGlobal(SGA); 731 732 if (DGV) { 733 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 734 bool LinkFromSrc = false; 735 if (getLinkageResult(DGV, SGA, NewLinkage, LinkFromSrc)) 736 return true; 737 738 if (!LinkFromSrc) { 739 // Set calculated linkage. 740 DGV->setLinkage(NewLinkage); 741 742 // Make sure to remember this mapping. 743 ValueMap[SGA] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGA->getType())); 744 745 // Track the alias from the source module so we don't attempt to remap it. 746 DoNotLinkFromSource.insert(SGA); 747 748 return false; 749 } 750 } 751 752 // If there is no linkage to be performed or we're linking from the source, 753 // bring over SGA. 754 GlobalAlias *NewDA = new GlobalAlias(TypeMap.get(SGA->getType()), 755 SGA->getLinkage(), SGA->getName(), 756 /*aliasee*/0, DstM); 757 CopyGVAttributes(NewDA, SGA); 758 759 if (DGV) { 760 // Any uses of DGV need to change to NewDA, with cast. 761 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDA, DGV->getType())); 762 DGV->eraseFromParent(); 763 } 764 765 ValueMap[SGA] = NewDA; 766 return false; 767} 768 769void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) { 770 // Merge the initializer. 771 SmallVector<Constant*, 16> Elements; 772 if (ConstantArray *I = dyn_cast<ConstantArray>(AVI.DstInit)) { 773 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) 774 Elements.push_back(I->getOperand(i)); 775 } else { 776 assert(isa<ConstantAggregateZero>(AVI.DstInit)); 777 ArrayType *DstAT = cast<ArrayType>(AVI.DstInit->getType()); 778 Type *EltTy = DstAT->getElementType(); 779 Elements.append(DstAT->getNumElements(), Constant::getNullValue(EltTy)); 780 } 781 782 Constant *SrcInit = MapValue(AVI.SrcInit, ValueMap, RF_None, &TypeMap); 783 if (const ConstantArray *I = dyn_cast<ConstantArray>(SrcInit)) { 784 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) 785 Elements.push_back(I->getOperand(i)); 786 } else { 787 assert(isa<ConstantAggregateZero>(SrcInit)); 788 ArrayType *SrcAT = cast<ArrayType>(SrcInit->getType()); 789 Type *EltTy = SrcAT->getElementType(); 790 Elements.append(SrcAT->getNumElements(), Constant::getNullValue(EltTy)); 791 } 792 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType()); 793 AVI.NewGV->setInitializer(ConstantArray::get(NewType, Elements)); 794} 795 796 797// linkGlobalInits - Update the initializers in the Dest module now that all 798// globals that may be referenced are in Dest. 799void ModuleLinker::linkGlobalInits() { 800 // Loop over all of the globals in the src module, mapping them over as we go 801 for (Module::const_global_iterator I = SrcM->global_begin(), 802 E = SrcM->global_end(); I != E; ++I) { 803 804 // Only process initialized GV's or ones not already in dest. 805 if (!I->hasInitializer() || DoNotLinkFromSource.count(I)) continue; 806 807 // Grab destination global variable. 808 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[I]); 809 // Figure out what the initializer looks like in the dest module. 810 DGV->setInitializer(MapValue(I->getInitializer(), ValueMap, 811 RF_None, &TypeMap)); 812 } 813} 814 815// linkFunctionBody - Copy the source function over into the dest function and 816// fix up references to values. At this point we know that Dest is an external 817// function, and that Src is not. 818void ModuleLinker::linkFunctionBody(Function *Dst, Function *Src) { 819 assert(Src && Dst && Dst->isDeclaration() && !Src->isDeclaration()); 820 821 // Go through and convert function arguments over, remembering the mapping. 822 Function::arg_iterator DI = Dst->arg_begin(); 823 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 824 I != E; ++I, ++DI) { 825 DI->setName(I->getName()); // Copy the name over. 826 827 // Add a mapping to our mapping. 828 ValueMap[I] = DI; 829 } 830 831 if (Mode == Linker::DestroySource) { 832 // Splice the body of the source function into the dest function. 833 Dst->getBasicBlockList().splice(Dst->end(), Src->getBasicBlockList()); 834 835 // At this point, all of the instructions and values of the function are now 836 // copied over. The only problem is that they are still referencing values in 837 // the Source function as operands. Loop through all of the operands of the 838 // functions and patch them up to point to the local versions. 839 for (Function::iterator BB = Dst->begin(), BE = Dst->end(); BB != BE; ++BB) 840 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) 841 RemapInstruction(I, ValueMap, RF_IgnoreMissingEntries, &TypeMap); 842 843 } else { 844 // Clone the body of the function into the dest function. 845 SmallVector<ReturnInst*, 8> Returns; // Ignore returns. 846 CloneFunctionInto(Dst, Src, ValueMap, false, Returns); 847 } 848 849 // There is no need to map the arguments anymore. 850 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 851 I != E; ++I) 852 ValueMap.erase(I); 853 854} 855 856 857void ModuleLinker::linkAliasBodies() { 858 for (Module::alias_iterator I = SrcM->alias_begin(), E = SrcM->alias_end(); 859 I != E; ++I) { 860 if (DoNotLinkFromSource.count(I)) 861 continue; 862 if (Constant *Aliasee = I->getAliasee()) { 863 GlobalAlias *DA = cast<GlobalAlias>(ValueMap[I]); 864 DA->setAliasee(MapValue(Aliasee, ValueMap, RF_None, &TypeMap)); 865 } 866 } 867} 868 869/// linkNamedMDNodes - Insert all of the named mdnodes in Src into the Dest 870/// module. 871void ModuleLinker::linkNamedMDNodes() { 872 for (Module::const_named_metadata_iterator I = SrcM->named_metadata_begin(), 873 E = SrcM->named_metadata_end(); I != E; ++I) { 874 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(I->getName()); 875 // Add Src elements into Dest node. 876 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) 877 DestNMD->addOperand(MapValue(I->getOperand(i), ValueMap, 878 RF_None, &TypeMap)); 879 } 880} 881 882bool ModuleLinker::run() { 883 assert(DstM && "Null Destination module"); 884 assert(SrcM && "Null Source Module"); 885 886 // Inherit the target data from the source module if the destination module 887 // doesn't have one already. 888 if (DstM->getDataLayout().empty() && !SrcM->getDataLayout().empty()) 889 DstM->setDataLayout(SrcM->getDataLayout()); 890 891 // Copy the target triple from the source to dest if the dest's is empty. 892 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty()) 893 DstM->setTargetTriple(SrcM->getTargetTriple()); 894 895 if (!SrcM->getDataLayout().empty() && !DstM->getDataLayout().empty() && 896 SrcM->getDataLayout() != DstM->getDataLayout()) 897 errs() << "WARNING: Linking two modules of different data layouts!\n"; 898 if (!SrcM->getTargetTriple().empty() && 899 DstM->getTargetTriple() != SrcM->getTargetTriple()) { 900 errs() << "WARNING: Linking two modules of different target triples: "; 901 if (!SrcM->getModuleIdentifier().empty()) 902 errs() << SrcM->getModuleIdentifier() << ": "; 903 errs() << "'" << SrcM->getTargetTriple() << "' and '" 904 << DstM->getTargetTriple() << "'\n"; 905 } 906 907 // Append the module inline asm string. 908 if (!SrcM->getModuleInlineAsm().empty()) { 909 if (DstM->getModuleInlineAsm().empty()) 910 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm()); 911 else 912 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+ 913 SrcM->getModuleInlineAsm()); 914 } 915 916 // Update the destination module's dependent libraries list with the libraries 917 // from the source module. There's no opportunity for duplicates here as the 918 // Module ensures that duplicate insertions are discarded. 919 for (Module::lib_iterator SI = SrcM->lib_begin(), SE = SrcM->lib_end(); 920 SI != SE; ++SI) 921 DstM->addLibrary(*SI); 922 923 // If the source library's module id is in the dependent library list of the 924 // destination library, remove it since that module is now linked in. 925 StringRef ModuleId = SrcM->getModuleIdentifier(); 926 if (!ModuleId.empty()) 927 DstM->removeLibrary(sys::path::stem(ModuleId)); 928 929 // Loop over all of the linked values to compute type mappings. 930 computeTypeMapping(); 931 932 // Insert all of the globals in src into the DstM module... without linking 933 // initializers (which could refer to functions not yet mapped over). 934 for (Module::global_iterator I = SrcM->global_begin(), 935 E = SrcM->global_end(); I != E; ++I) 936 if (linkGlobalProto(I)) 937 return true; 938 939 // Link the functions together between the two modules, without doing function 940 // bodies... this just adds external function prototypes to the DstM 941 // function... We do this so that when we begin processing function bodies, 942 // all of the global values that may be referenced are available in our 943 // ValueMap. 944 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I) 945 if (linkFunctionProto(I)) 946 return true; 947 948 // If there were any aliases, link them now. 949 for (Module::alias_iterator I = SrcM->alias_begin(), 950 E = SrcM->alias_end(); I != E; ++I) 951 if (linkAliasProto(I)) 952 return true; 953 954 for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i) 955 linkAppendingVarInit(AppendingVars[i]); 956 957 // Update the initializers in the DstM module now that all globals that may 958 // be referenced are in DstM. 959 linkGlobalInits(); 960 961 // Link in the function bodies that are defined in the source module into 962 // DstM. 963 for (Module::iterator SF = SrcM->begin(), E = SrcM->end(); SF != E; ++SF) { 964 965 // Skip if not linking from source. 966 if (DoNotLinkFromSource.count(SF)) continue; 967 968 // Skip if no body (function is external) or materialize. 969 if (SF->isDeclaration()) { 970 if (!SF->isMaterializable()) 971 continue; 972 if (SF->Materialize(&ErrorMsg)) 973 return true; 974 } 975 976 linkFunctionBody(cast<Function>(ValueMap[SF]), SF); 977 } 978 979 // Resolve all uses of aliases with aliasees. 980 linkAliasBodies(); 981 982 // Remap all of the named mdnoes in Src into the DstM module. We do this 983 // after linking GlobalValues so that MDNodes that reference GlobalValues 984 // are properly remapped. 985 linkNamedMDNodes(); 986 987 // Process vector of lazily linked in functions. 988 bool LinkedInAnyFunctions; 989 do { 990 LinkedInAnyFunctions = false; 991 992 for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(), 993 E = LazilyLinkFunctions.end(); I != E; ++I) { 994 if (!*I) 995 continue; 996 997 Function *SF = *I; 998 Function *DF = cast<Function>(ValueMap[SF]); 999 1000 if (!DF->use_empty()) { 1001 1002 // Materialize if necessary. 1003 if (SF->isDeclaration()) { 1004 if (!SF->isMaterializable()) 1005 continue; 1006 if (SF->Materialize(&ErrorMsg)) 1007 return true; 1008 } 1009 1010 // Link in function body. 1011 linkFunctionBody(DF, SF); 1012 1013 // "Remove" from vector by setting the element to 0. 1014 *I = 0; 1015 1016 // Set flag to indicate we may have more functions to lazily link in 1017 // since we linked in a function. 1018 LinkedInAnyFunctions = true; 1019 } 1020 } 1021 } while (LinkedInAnyFunctions); 1022 1023 // Remove any prototypes of functions that were not actually linked in. 1024 for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(), 1025 E = LazilyLinkFunctions.end(); I != E; ++I) { 1026 if (!*I) 1027 continue; 1028 1029 Function *SF = *I; 1030 Function *DF = cast<Function>(ValueMap[SF]); 1031 if (DF->use_empty()) 1032 DF->eraseFromParent(); 1033 } 1034 1035 // Now that all of the types from the source are used, resolve any structs 1036 // copied over to the dest that didn't exist there. 1037 TypeMap.linkDefinedTypeBodies(); 1038 1039 return false; 1040} 1041 1042//===----------------------------------------------------------------------===// 1043// LinkModules entrypoint. 1044//===----------------------------------------------------------------------===// 1045 1046// LinkModules - This function links two modules together, with the resulting 1047// left module modified to be the composite of the two input modules. If an 1048// error occurs, true is returned and ErrorMsg (if not null) is set to indicate 1049// the problem. Upon failure, the Dest module could be in a modified state, and 1050// shouldn't be relied on to be consistent. 1051bool Linker::LinkModules(Module *Dest, Module *Src, unsigned Mode, 1052 std::string *ErrorMsg) { 1053 ModuleLinker TheLinker(Dest, Src, Mode); 1054 if (TheLinker.run()) { 1055 if (ErrorMsg) *ErrorMsg = TheLinker.ErrorMsg; 1056 return true; 1057 } 1058 1059 return false; 1060} 1061