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/Linker.h" 15 #include "llvm-c/Linker.h" 16 #include "llvm/ADT/Optional.h" 17 #include "llvm/ADT/SetVector.h" 18 #include "llvm/ADT/SmallString.h" 19 #include "llvm/IR/Constants.h" 20 #include "llvm/IR/Module.h" 21 #include "llvm/IR/TypeFinder.h" 22 #include "llvm/Support/CommandLine.h" 23 #include "llvm/Support/Debug.h" 24 #include "llvm/Support/raw_ostream.h" 25 #include "llvm/Transforms/Utils/Cloning.h" 26 #include <cctype> 27 #include <tuple> 28 using namespace llvm; 29 30 31 //===----------------------------------------------------------------------===// 32 // TypeMap implementation. 33 //===----------------------------------------------------------------------===// 34 35 namespace { 36 typedef SmallPtrSet<StructType*, 32> TypeSet; 37 38 class TypeMapTy : public ValueMapTypeRemapper { 39 /// MappedTypes - This is a mapping from a source type to a destination type 40 /// to use. 41 DenseMap<Type*, Type*> MappedTypes; 42 43 /// SpeculativeTypes - When checking to see if two subgraphs are isomorphic, 44 /// we speculatively add types to MappedTypes, but keep track of them here in 45 /// case we need to roll back. 46 SmallVector<Type*, 16> SpeculativeTypes; 47 48 /// SrcDefinitionsToResolve - This is a list of non-opaque structs in the 49 /// source module that are mapped to an opaque struct in the destination 50 /// module. 51 SmallVector<StructType*, 16> SrcDefinitionsToResolve; 52 53 /// DstResolvedOpaqueTypes - This is the set of opaque types in the 54 /// destination modules who are getting a body from the source module. 55 SmallPtrSet<StructType*, 16> DstResolvedOpaqueTypes; 56 57 public: 58 TypeMapTy(TypeSet &Set) : DstStructTypesSet(Set) {} 59 60 TypeSet &DstStructTypesSet; 61 /// addTypeMapping - Indicate that the specified type in the destination 62 /// module is conceptually equivalent to the specified type in the source 63 /// module. 64 void addTypeMapping(Type *DstTy, Type *SrcTy); 65 66 /// linkDefinedTypeBodies - Produce a body for an opaque type in the dest 67 /// module from a type definition in the source module. 68 void linkDefinedTypeBodies(); 69 70 /// get - Return the mapped type to use for the specified input type from the 71 /// source module. 72 Type *get(Type *SrcTy); 73 74 FunctionType *get(FunctionType *T) {return cast<FunctionType>(get((Type*)T));} 75 76 /// dump - Dump out the type map for debugging purposes. 77 void dump() const { 78 for (DenseMap<Type*, Type*>::const_iterator 79 I = MappedTypes.begin(), E = MappedTypes.end(); I != E; ++I) { 80 dbgs() << "TypeMap: "; 81 I->first->dump(); 82 dbgs() << " => "; 83 I->second->dump(); 84 dbgs() << '\n'; 85 } 86 } 87 88 private: 89 Type *getImpl(Type *T); 90 /// remapType - Implement the ValueMapTypeRemapper interface. 91 Type *remapType(Type *SrcTy) override { 92 return get(SrcTy); 93 } 94 95 bool areTypesIsomorphic(Type *DstTy, Type *SrcTy); 96 }; 97 } 98 99 void TypeMapTy::addTypeMapping(Type *DstTy, Type *SrcTy) { 100 Type *&Entry = MappedTypes[SrcTy]; 101 if (Entry) return; 102 103 if (DstTy == SrcTy) { 104 Entry = DstTy; 105 return; 106 } 107 108 // Check to see if these types are recursively isomorphic and establish a 109 // mapping between them if so. 110 if (!areTypesIsomorphic(DstTy, SrcTy)) { 111 // Oops, they aren't isomorphic. Just discard this request by rolling out 112 // any speculative mappings we've established. 113 for (unsigned i = 0, e = SpeculativeTypes.size(); i != e; ++i) 114 MappedTypes.erase(SpeculativeTypes[i]); 115 } 116 SpeculativeTypes.clear(); 117 } 118 119 /// areTypesIsomorphic - Recursively walk this pair of types, returning true 120 /// if they are isomorphic, false if they are not. 121 bool TypeMapTy::areTypesIsomorphic(Type *DstTy, Type *SrcTy) { 122 // Two types with differing kinds are clearly not isomorphic. 123 if (DstTy->getTypeID() != SrcTy->getTypeID()) return false; 124 125 // If we have an entry in the MappedTypes table, then we have our answer. 126 Type *&Entry = MappedTypes[SrcTy]; 127 if (Entry) 128 return Entry == DstTy; 129 130 // Two identical types are clearly isomorphic. Remember this 131 // non-speculatively. 132 if (DstTy == SrcTy) { 133 Entry = DstTy; 134 return true; 135 } 136 137 // Okay, we have two types with identical kinds that we haven't seen before. 138 139 // If this is an opaque struct type, special case it. 140 if (StructType *SSTy = dyn_cast<StructType>(SrcTy)) { 141 // Mapping an opaque type to any struct, just keep the dest struct. 142 if (SSTy->isOpaque()) { 143 Entry = DstTy; 144 SpeculativeTypes.push_back(SrcTy); 145 return true; 146 } 147 148 // Mapping a non-opaque source type to an opaque dest. If this is the first 149 // type that we're mapping onto this destination type then we succeed. Keep 150 // the dest, but fill it in later. This doesn't need to be speculative. If 151 // this is the second (different) type that we're trying to map onto the 152 // same opaque type then we fail. 153 if (cast<StructType>(DstTy)->isOpaque()) { 154 // We can only map one source type onto the opaque destination type. 155 if (!DstResolvedOpaqueTypes.insert(cast<StructType>(DstTy))) 156 return false; 157 SrcDefinitionsToResolve.push_back(SSTy); 158 Entry = DstTy; 159 return true; 160 } 161 } 162 163 // If the number of subtypes disagree between the two types, then we fail. 164 if (SrcTy->getNumContainedTypes() != DstTy->getNumContainedTypes()) 165 return false; 166 167 // Fail if any of the extra properties (e.g. array size) of the type disagree. 168 if (isa<IntegerType>(DstTy)) 169 return false; // bitwidth disagrees. 170 if (PointerType *PT = dyn_cast<PointerType>(DstTy)) { 171 if (PT->getAddressSpace() != cast<PointerType>(SrcTy)->getAddressSpace()) 172 return false; 173 174 } else if (FunctionType *FT = dyn_cast<FunctionType>(DstTy)) { 175 if (FT->isVarArg() != cast<FunctionType>(SrcTy)->isVarArg()) 176 return false; 177 } else if (StructType *DSTy = dyn_cast<StructType>(DstTy)) { 178 StructType *SSTy = cast<StructType>(SrcTy); 179 if (DSTy->isLiteral() != SSTy->isLiteral() || 180 DSTy->isPacked() != SSTy->isPacked()) 181 return false; 182 } else if (ArrayType *DATy = dyn_cast<ArrayType>(DstTy)) { 183 if (DATy->getNumElements() != cast<ArrayType>(SrcTy)->getNumElements()) 184 return false; 185 } else if (VectorType *DVTy = dyn_cast<VectorType>(DstTy)) { 186 if (DVTy->getNumElements() != cast<VectorType>(SrcTy)->getNumElements()) 187 return false; 188 } 189 190 // Otherwise, we speculate that these two types will line up and recursively 191 // check the subelements. 192 Entry = DstTy; 193 SpeculativeTypes.push_back(SrcTy); 194 195 for (unsigned i = 0, e = SrcTy->getNumContainedTypes(); i != e; ++i) 196 if (!areTypesIsomorphic(DstTy->getContainedType(i), 197 SrcTy->getContainedType(i))) 198 return false; 199 200 // If everything seems to have lined up, then everything is great. 201 return true; 202 } 203 204 /// linkDefinedTypeBodies - Produce a body for an opaque type in the dest 205 /// module from a type definition in the source module. 206 void TypeMapTy::linkDefinedTypeBodies() { 207 SmallVector<Type*, 16> Elements; 208 SmallString<16> TmpName; 209 210 // Note that processing entries in this loop (calling 'get') can add new 211 // entries to the SrcDefinitionsToResolve vector. 212 while (!SrcDefinitionsToResolve.empty()) { 213 StructType *SrcSTy = SrcDefinitionsToResolve.pop_back_val(); 214 StructType *DstSTy = cast<StructType>(MappedTypes[SrcSTy]); 215 216 // TypeMap is a many-to-one mapping, if there were multiple types that 217 // provide a body for DstSTy then previous iterations of this loop may have 218 // already handled it. Just ignore this case. 219 if (!DstSTy->isOpaque()) continue; 220 assert(!SrcSTy->isOpaque() && "Not resolving a definition?"); 221 222 // Map the body of the source type over to a new body for the dest type. 223 Elements.resize(SrcSTy->getNumElements()); 224 for (unsigned i = 0, e = Elements.size(); i != e; ++i) 225 Elements[i] = getImpl(SrcSTy->getElementType(i)); 226 227 DstSTy->setBody(Elements, SrcSTy->isPacked()); 228 229 // If DstSTy has no name or has a longer name than STy, then viciously steal 230 // STy's name. 231 if (!SrcSTy->hasName()) continue; 232 StringRef SrcName = SrcSTy->getName(); 233 234 if (!DstSTy->hasName() || DstSTy->getName().size() > SrcName.size()) { 235 TmpName.insert(TmpName.end(), SrcName.begin(), SrcName.end()); 236 SrcSTy->setName(""); 237 DstSTy->setName(TmpName.str()); 238 TmpName.clear(); 239 } 240 } 241 242 DstResolvedOpaqueTypes.clear(); 243 } 244 245 /// get - Return the mapped type to use for the specified input type from the 246 /// source module. 247 Type *TypeMapTy::get(Type *Ty) { 248 Type *Result = getImpl(Ty); 249 250 // If this caused a reference to any struct type, resolve it before returning. 251 if (!SrcDefinitionsToResolve.empty()) 252 linkDefinedTypeBodies(); 253 return Result; 254 } 255 256 /// getImpl - This is the recursive version of get(). 257 Type *TypeMapTy::getImpl(Type *Ty) { 258 // If we already have an entry for this type, return it. 259 Type **Entry = &MappedTypes[Ty]; 260 if (*Entry) return *Entry; 261 262 // If this is not a named struct type, then just map all of the elements and 263 // then rebuild the type from inside out. 264 if (!isa<StructType>(Ty) || cast<StructType>(Ty)->isLiteral()) { 265 // If there are no element types to map, then the type is itself. This is 266 // true for the anonymous {} struct, things like 'float', integers, etc. 267 if (Ty->getNumContainedTypes() == 0) 268 return *Entry = Ty; 269 270 // Remap all of the elements, keeping track of whether any of them change. 271 bool AnyChange = false; 272 SmallVector<Type*, 4> ElementTypes; 273 ElementTypes.resize(Ty->getNumContainedTypes()); 274 for (unsigned i = 0, e = Ty->getNumContainedTypes(); i != e; ++i) { 275 ElementTypes[i] = getImpl(Ty->getContainedType(i)); 276 AnyChange |= ElementTypes[i] != Ty->getContainedType(i); 277 } 278 279 // If we found our type while recursively processing stuff, just use it. 280 Entry = &MappedTypes[Ty]; 281 if (*Entry) return *Entry; 282 283 // If all of the element types mapped directly over, then the type is usable 284 // as-is. 285 if (!AnyChange) 286 return *Entry = Ty; 287 288 // Otherwise, rebuild a modified type. 289 switch (Ty->getTypeID()) { 290 default: llvm_unreachable("unknown derived type to remap"); 291 case Type::ArrayTyID: 292 return *Entry = ArrayType::get(ElementTypes[0], 293 cast<ArrayType>(Ty)->getNumElements()); 294 case Type::VectorTyID: 295 return *Entry = VectorType::get(ElementTypes[0], 296 cast<VectorType>(Ty)->getNumElements()); 297 case Type::PointerTyID: 298 return *Entry = PointerType::get(ElementTypes[0], 299 cast<PointerType>(Ty)->getAddressSpace()); 300 case Type::FunctionTyID: 301 return *Entry = FunctionType::get(ElementTypes[0], 302 makeArrayRef(ElementTypes).slice(1), 303 cast<FunctionType>(Ty)->isVarArg()); 304 case Type::StructTyID: 305 // Note that this is only reached for anonymous structs. 306 return *Entry = StructType::get(Ty->getContext(), ElementTypes, 307 cast<StructType>(Ty)->isPacked()); 308 } 309 } 310 311 // Otherwise, this is an unmapped named struct. If the struct can be directly 312 // mapped over, just use it as-is. This happens in a case when the linked-in 313 // module has something like: 314 // %T = type {%T*, i32} 315 // @GV = global %T* null 316 // where T does not exist at all in the destination module. 317 // 318 // The other case we watch for is when the type is not in the destination 319 // module, but that it has to be rebuilt because it refers to something that 320 // is already mapped. For example, if the destination module has: 321 // %A = type { i32 } 322 // and the source module has something like 323 // %A' = type { i32 } 324 // %B = type { %A'* } 325 // @GV = global %B* null 326 // then we want to create a new type: "%B = type { %A*}" and have it take the 327 // pristine "%B" name from the source module. 328 // 329 // To determine which case this is, we have to recursively walk the type graph 330 // speculating that we'll be able to reuse it unmodified. Only if this is 331 // safe would we map the entire thing over. Because this is an optimization, 332 // and is not required for the prettiness of the linked module, we just skip 333 // it and always rebuild a type here. 334 StructType *STy = cast<StructType>(Ty); 335 336 // If the type is opaque, we can just use it directly. 337 if (STy->isOpaque()) { 338 // A named structure type from src module is used. Add it to the Set of 339 // identified structs in the destination module. 340 DstStructTypesSet.insert(STy); 341 return *Entry = STy; 342 } 343 344 // Otherwise we create a new type and resolve its body later. This will be 345 // resolved by the top level of get(). 346 SrcDefinitionsToResolve.push_back(STy); 347 StructType *DTy = StructType::create(STy->getContext()); 348 // A new identified structure type was created. Add it to the set of 349 // identified structs in the destination module. 350 DstStructTypesSet.insert(DTy); 351 DstResolvedOpaqueTypes.insert(DTy); 352 return *Entry = DTy; 353 } 354 355 //===----------------------------------------------------------------------===// 356 // ModuleLinker implementation. 357 //===----------------------------------------------------------------------===// 358 359 namespace { 360 class ModuleLinker; 361 362 /// ValueMaterializerTy - Creates prototypes for functions that are lazily 363 /// linked on the fly. This speeds up linking for modules with many 364 /// lazily linked functions of which few get used. 365 class ValueMaterializerTy : public ValueMaterializer { 366 TypeMapTy &TypeMap; 367 Module *DstM; 368 std::vector<Function*> &LazilyLinkFunctions; 369 public: 370 ValueMaterializerTy(TypeMapTy &TypeMap, Module *DstM, 371 std::vector<Function*> &LazilyLinkFunctions) : 372 ValueMaterializer(), TypeMap(TypeMap), DstM(DstM), 373 LazilyLinkFunctions(LazilyLinkFunctions) { 374 } 375 376 Value *materializeValueFor(Value *V) override; 377 }; 378 379 /// ModuleLinker - This is an implementation class for the LinkModules 380 /// function, which is the entrypoint for this file. 381 class ModuleLinker { 382 Module *DstM, *SrcM; 383 384 TypeMapTy TypeMap; 385 ValueMaterializerTy ValMaterializer; 386 387 /// ValueMap - Mapping of values from what they used to be in Src, to what 388 /// they are now in DstM. ValueToValueMapTy is a ValueMap, which involves 389 /// some overhead due to the use of Value handles which the Linker doesn't 390 /// actually need, but this allows us to reuse the ValueMapper code. 391 ValueToValueMapTy ValueMap; 392 393 struct AppendingVarInfo { 394 GlobalVariable *NewGV; // New aggregate global in dest module. 395 Constant *DstInit; // Old initializer from dest module. 396 Constant *SrcInit; // Old initializer from src module. 397 }; 398 399 std::vector<AppendingVarInfo> AppendingVars; 400 401 unsigned Mode; // Mode to treat source module. 402 403 // Set of items not to link in from source. 404 SmallPtrSet<const Value*, 16> DoNotLinkFromSource; 405 406 // Vector of functions to lazily link in. 407 std::vector<Function*> LazilyLinkFunctions; 408 409 bool SuppressWarnings; 410 411 public: 412 std::string ErrorMsg; 413 414 ModuleLinker(Module *dstM, TypeSet &Set, Module *srcM, unsigned mode, 415 bool SuppressWarnings=false) 416 : DstM(dstM), SrcM(srcM), TypeMap(Set), 417 ValMaterializer(TypeMap, DstM, LazilyLinkFunctions), Mode(mode), 418 SuppressWarnings(SuppressWarnings) {} 419 420 bool run(); 421 422 private: 423 /// emitError - Helper method for setting a message and returning an error 424 /// code. 425 bool emitError(const Twine &Message) { 426 ErrorMsg = Message.str(); 427 return true; 428 } 429 430 bool getComdatLeader(Module *M, StringRef ComdatName, 431 const GlobalVariable *&GVar); 432 bool computeResultingSelectionKind(StringRef ComdatName, 433 Comdat::SelectionKind Src, 434 Comdat::SelectionKind Dst, 435 Comdat::SelectionKind &Result, 436 bool &LinkFromSrc); 437 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>> 438 ComdatsChosen; 439 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK, 440 bool &LinkFromSrc); 441 442 /// getLinkageResult - This analyzes the two global values and determines 443 /// what the result will look like in the destination module. 444 bool getLinkageResult(GlobalValue *Dest, const GlobalValue *Src, 445 GlobalValue::LinkageTypes <, 446 GlobalValue::VisibilityTypes &Vis, 447 bool &LinkFromSrc); 448 449 /// getLinkedToGlobal - Given a global in the source module, return the 450 /// global in the destination module that is being linked to, if any. 451 GlobalValue *getLinkedToGlobal(GlobalValue *SrcGV) { 452 // If the source has no name it can't link. If it has local linkage, 453 // there is no name match-up going on. 454 if (!SrcGV->hasName() || SrcGV->hasLocalLinkage()) 455 return nullptr; 456 457 // Otherwise see if we have a match in the destination module's symtab. 458 GlobalValue *DGV = DstM->getNamedValue(SrcGV->getName()); 459 if (!DGV) return nullptr; 460 461 // If we found a global with the same name in the dest module, but it has 462 // internal linkage, we are really not doing any linkage here. 463 if (DGV->hasLocalLinkage()) 464 return nullptr; 465 466 // Otherwise, we do in fact link to the destination global. 467 return DGV; 468 } 469 470 void computeTypeMapping(); 471 472 bool linkAppendingVarProto(GlobalVariable *DstGV, GlobalVariable *SrcGV); 473 bool linkGlobalProto(GlobalVariable *SrcGV); 474 bool linkFunctionProto(Function *SrcF); 475 bool linkAliasProto(GlobalAlias *SrcA); 476 bool linkModuleFlagsMetadata(); 477 478 void linkAppendingVarInit(const AppendingVarInfo &AVI); 479 void linkGlobalInits(); 480 void linkFunctionBody(Function *Dst, Function *Src); 481 void linkAliasBodies(); 482 void linkNamedMDNodes(); 483 }; 484 } 485 486 /// forceRenaming - The LLVM SymbolTable class autorenames globals that conflict 487 /// in the symbol table. This is good for all clients except for us. Go 488 /// through the trouble to force this back. 489 static void forceRenaming(GlobalValue *GV, StringRef Name) { 490 // If the global doesn't force its name or if it already has the right name, 491 // there is nothing for us to do. 492 if (GV->hasLocalLinkage() || GV->getName() == Name) 493 return; 494 495 Module *M = GV->getParent(); 496 497 // If there is a conflict, rename the conflict. 498 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) { 499 GV->takeName(ConflictGV); 500 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed 501 assert(ConflictGV->getName() != Name && "forceRenaming didn't work"); 502 } else { 503 GV->setName(Name); // Force the name back 504 } 505 } 506 507 /// copyGVAttributes - copy additional attributes (those not needed to construct 508 /// a GlobalValue) from the SrcGV to the DestGV. 509 static void copyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) { 510 // Use the maximum alignment, rather than just copying the alignment of SrcGV. 511 auto *DestGO = dyn_cast<GlobalObject>(DestGV); 512 unsigned Alignment; 513 if (DestGO) 514 Alignment = std::max(DestGO->getAlignment(), SrcGV->getAlignment()); 515 516 DestGV->copyAttributesFrom(SrcGV); 517 518 if (DestGO) 519 DestGO->setAlignment(Alignment); 520 521 forceRenaming(DestGV, SrcGV->getName()); 522 } 523 524 static bool isLessConstraining(GlobalValue::VisibilityTypes a, 525 GlobalValue::VisibilityTypes b) { 526 if (a == GlobalValue::HiddenVisibility) 527 return false; 528 if (b == GlobalValue::HiddenVisibility) 529 return true; 530 if (a == GlobalValue::ProtectedVisibility) 531 return false; 532 if (b == GlobalValue::ProtectedVisibility) 533 return true; 534 return false; 535 } 536 537 Value *ValueMaterializerTy::materializeValueFor(Value *V) { 538 Function *SF = dyn_cast<Function>(V); 539 if (!SF) 540 return nullptr; 541 542 Function *DF = Function::Create(TypeMap.get(SF->getFunctionType()), 543 SF->getLinkage(), SF->getName(), DstM); 544 copyGVAttributes(DF, SF); 545 546 LazilyLinkFunctions.push_back(SF); 547 return DF; 548 } 549 550 bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName, 551 const GlobalVariable *&GVar) { 552 const GlobalValue *GVal = M->getNamedValue(ComdatName); 553 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) { 554 GVal = GA->getBaseObject(); 555 if (!GVal) 556 // We cannot resolve the size of the aliasee yet. 557 return emitError("Linking COMDATs named '" + ComdatName + 558 "': COMDAT key involves incomputable alias size."); 559 } 560 561 GVar = dyn_cast_or_null<GlobalVariable>(GVal); 562 if (!GVar) 563 return emitError( 564 "Linking COMDATs named '" + ComdatName + 565 "': GlobalVariable required for data dependent selection!"); 566 567 return false; 568 } 569 570 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName, 571 Comdat::SelectionKind Src, 572 Comdat::SelectionKind Dst, 573 Comdat::SelectionKind &Result, 574 bool &LinkFromSrc) { 575 // The ability to mix Comdat::SelectionKind::Any with 576 // Comdat::SelectionKind::Largest is a behavior that comes from COFF. 577 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any || 578 Dst == Comdat::SelectionKind::Largest; 579 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any || 580 Src == Comdat::SelectionKind::Largest; 581 if (DstAnyOrLargest && SrcAnyOrLargest) { 582 if (Dst == Comdat::SelectionKind::Largest || 583 Src == Comdat::SelectionKind::Largest) 584 Result = Comdat::SelectionKind::Largest; 585 else 586 Result = Comdat::SelectionKind::Any; 587 } else if (Src == Dst) { 588 Result = Dst; 589 } else { 590 return emitError("Linking COMDATs named '" + ComdatName + 591 "': invalid selection kinds!"); 592 } 593 594 switch (Result) { 595 case Comdat::SelectionKind::Any: 596 // Go with Dst. 597 LinkFromSrc = false; 598 break; 599 case Comdat::SelectionKind::NoDuplicates: 600 return emitError("Linking COMDATs named '" + ComdatName + 601 "': noduplicates has been violated!"); 602 case Comdat::SelectionKind::ExactMatch: 603 case Comdat::SelectionKind::Largest: 604 case Comdat::SelectionKind::SameSize: { 605 const GlobalVariable *DstGV; 606 const GlobalVariable *SrcGV; 607 if (getComdatLeader(DstM, ComdatName, DstGV) || 608 getComdatLeader(SrcM, ComdatName, SrcGV)) 609 return true; 610 611 const DataLayout *DstDL = DstM->getDataLayout(); 612 const DataLayout *SrcDL = SrcM->getDataLayout(); 613 if (!DstDL || !SrcDL) { 614 return emitError( 615 "Linking COMDATs named '" + ComdatName + 616 "': can't do size dependent selection without DataLayout!"); 617 } 618 uint64_t DstSize = 619 DstDL->getTypeAllocSize(DstGV->getType()->getPointerElementType()); 620 uint64_t SrcSize = 621 SrcDL->getTypeAllocSize(SrcGV->getType()->getPointerElementType()); 622 if (Result == Comdat::SelectionKind::ExactMatch) { 623 if (SrcGV->getInitializer() != DstGV->getInitializer()) 624 return emitError("Linking COMDATs named '" + ComdatName + 625 "': ExactMatch violated!"); 626 LinkFromSrc = false; 627 } else if (Result == Comdat::SelectionKind::Largest) { 628 LinkFromSrc = SrcSize > DstSize; 629 } else if (Result == Comdat::SelectionKind::SameSize) { 630 if (SrcSize != DstSize) 631 return emitError("Linking COMDATs named '" + ComdatName + 632 "': SameSize violated!"); 633 LinkFromSrc = false; 634 } else { 635 llvm_unreachable("unknown selection kind"); 636 } 637 break; 638 } 639 } 640 641 return false; 642 } 643 644 bool ModuleLinker::getComdatResult(const Comdat *SrcC, 645 Comdat::SelectionKind &Result, 646 bool &LinkFromSrc) { 647 StringRef ComdatName = SrcC->getName(); 648 Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable(); 649 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName); 650 if (DstCI != ComdatSymTab.end()) { 651 const Comdat *DstC = &DstCI->second; 652 Comdat::SelectionKind SSK = SrcC->getSelectionKind(); 653 Comdat::SelectionKind DSK = DstC->getSelectionKind(); 654 if (computeResultingSelectionKind(ComdatName, SSK, DSK, Result, LinkFromSrc)) 655 return true; 656 } 657 return false; 658 } 659 660 /// getLinkageResult - This analyzes the two global values and determines what 661 /// the result will look like in the destination module. In particular, it 662 /// computes the resultant linkage type and visibility, computes whether the 663 /// global in the source should be copied over to the destination (replacing 664 /// the existing one), and computes whether this linkage is an error or not. 665 bool ModuleLinker::getLinkageResult(GlobalValue *Dest, const GlobalValue *Src, 666 GlobalValue::LinkageTypes <, 667 GlobalValue::VisibilityTypes &Vis, 668 bool &LinkFromSrc) { 669 assert(Dest && "Must have two globals being queried"); 670 assert(!Src->hasLocalLinkage() && 671 "If Src has internal linkage, Dest shouldn't be set!"); 672 673 bool SrcIsDeclaration = Src->isDeclaration() && !Src->isMaterializable(); 674 bool DestIsDeclaration = Dest->isDeclaration(); 675 676 if (SrcIsDeclaration) { 677 // If Src is external or if both Src & Dest are external.. Just link the 678 // external globals, we aren't adding anything. 679 if (Src->hasDLLImportStorageClass()) { 680 // If one of GVs is marked as DLLImport, result should be dllimport'ed. 681 if (DestIsDeclaration) { 682 LinkFromSrc = true; 683 LT = Src->getLinkage(); 684 } 685 } else if (Dest->hasExternalWeakLinkage()) { 686 // If the Dest is weak, use the source linkage. 687 LinkFromSrc = true; 688 LT = Src->getLinkage(); 689 } else { 690 LinkFromSrc = false; 691 LT = Dest->getLinkage(); 692 } 693 } else if (DestIsDeclaration && !Dest->hasDLLImportStorageClass()) { 694 // If Dest is external but Src is not: 695 LinkFromSrc = true; 696 LT = Src->getLinkage(); 697 } else if (Src->isWeakForLinker()) { 698 // At this point we know that Dest has LinkOnce, External*, Weak, Common, 699 // or DLL* linkage. 700 if (Dest->hasExternalWeakLinkage() || 701 Dest->hasAvailableExternallyLinkage() || 702 (Dest->hasLinkOnceLinkage() && 703 (Src->hasWeakLinkage() || Src->hasCommonLinkage()))) { 704 LinkFromSrc = true; 705 LT = Src->getLinkage(); 706 } else { 707 LinkFromSrc = false; 708 LT = Dest->getLinkage(); 709 } 710 } else if (Dest->isWeakForLinker()) { 711 // At this point we know that Src has External* or DLL* linkage. 712 if (Src->hasExternalWeakLinkage()) { 713 LinkFromSrc = false; 714 LT = Dest->getLinkage(); 715 } else { 716 LinkFromSrc = true; 717 LT = GlobalValue::ExternalLinkage; 718 } 719 } else { 720 assert((Dest->hasExternalLinkage() || Dest->hasExternalWeakLinkage()) && 721 (Src->hasExternalLinkage() || Src->hasExternalWeakLinkage()) && 722 "Unexpected linkage type!"); 723 return emitError("Linking globals named '" + Src->getName() + 724 "': symbol multiply defined!"); 725 } 726 727 // Compute the visibility. We follow the rules in the System V Application 728 // Binary Interface. 729 assert(!GlobalValue::isLocalLinkage(LT) && 730 "Symbols with local linkage should not be merged"); 731 Vis = isLessConstraining(Src->getVisibility(), Dest->getVisibility()) ? 732 Dest->getVisibility() : Src->getVisibility(); 733 return false; 734 } 735 736 /// computeTypeMapping - Loop over all of the linked values to compute type 737 /// mappings. For example, if we link "extern Foo *x" and "Foo *x = NULL", then 738 /// we have two struct types 'Foo' but one got renamed when the module was 739 /// loaded into the same LLVMContext. 740 void ModuleLinker::computeTypeMapping() { 741 // Incorporate globals. 742 for (Module::global_iterator I = SrcM->global_begin(), 743 E = SrcM->global_end(); I != E; ++I) { 744 GlobalValue *DGV = getLinkedToGlobal(I); 745 if (!DGV) continue; 746 747 if (!DGV->hasAppendingLinkage() || !I->hasAppendingLinkage()) { 748 TypeMap.addTypeMapping(DGV->getType(), I->getType()); 749 continue; 750 } 751 752 // Unify the element type of appending arrays. 753 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType()); 754 ArrayType *SAT = cast<ArrayType>(I->getType()->getElementType()); 755 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType()); 756 } 757 758 // Incorporate functions. 759 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I) { 760 if (GlobalValue *DGV = getLinkedToGlobal(I)) 761 TypeMap.addTypeMapping(DGV->getType(), I->getType()); 762 } 763 764 // Incorporate types by name, scanning all the types in the source module. 765 // At this point, the destination module may have a type "%foo = { i32 }" for 766 // example. When the source module got loaded into the same LLVMContext, if 767 // it had the same type, it would have been renamed to "%foo.42 = { i32 }". 768 TypeFinder SrcStructTypes; 769 SrcStructTypes.run(*SrcM, true); 770 SmallPtrSet<StructType*, 32> SrcStructTypesSet(SrcStructTypes.begin(), 771 SrcStructTypes.end()); 772 773 for (unsigned i = 0, e = SrcStructTypes.size(); i != e; ++i) { 774 StructType *ST = SrcStructTypes[i]; 775 if (!ST->hasName()) continue; 776 777 // Check to see if there is a dot in the name followed by a digit. 778 size_t DotPos = ST->getName().rfind('.'); 779 if (DotPos == 0 || DotPos == StringRef::npos || 780 ST->getName().back() == '.' || 781 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos+1]))) 782 continue; 783 784 // Check to see if the destination module has a struct with the prefix name. 785 if (StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos))) 786 // Don't use it if this actually came from the source module. They're in 787 // the same LLVMContext after all. Also don't use it unless the type is 788 // actually used in the destination module. This can happen in situations 789 // like this: 790 // 791 // Module A Module B 792 // -------- -------- 793 // %Z = type { %A } %B = type { %C.1 } 794 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* } 795 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] } 796 // %C = type { i8* } %B.3 = type { %C.1 } 797 // 798 // When we link Module B with Module A, the '%B' in Module B is 799 // used. However, that would then use '%C.1'. But when we process '%C.1', 800 // we prefer to take the '%C' version. So we are then left with both 801 // '%C.1' and '%C' being used for the same types. This leads to some 802 // variables using one type and some using the other. 803 if (!SrcStructTypesSet.count(DST) && TypeMap.DstStructTypesSet.count(DST)) 804 TypeMap.addTypeMapping(DST, ST); 805 } 806 807 // Don't bother incorporating aliases, they aren't generally typed well. 808 809 // Now that we have discovered all of the type equivalences, get a body for 810 // any 'opaque' types in the dest module that are now resolved. 811 TypeMap.linkDefinedTypeBodies(); 812 } 813 814 /// linkAppendingVarProto - If there were any appending global variables, link 815 /// them together now. Return true on error. 816 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV, 817 GlobalVariable *SrcGV) { 818 819 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage()) 820 return emitError("Linking globals named '" + SrcGV->getName() + 821 "': can only link appending global with another appending global!"); 822 823 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType()); 824 ArrayType *SrcTy = 825 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType())); 826 Type *EltTy = DstTy->getElementType(); 827 828 // Check to see that they two arrays agree on type. 829 if (EltTy != SrcTy->getElementType()) 830 return emitError("Appending variables with different element types!"); 831 if (DstGV->isConstant() != SrcGV->isConstant()) 832 return emitError("Appending variables linked with different const'ness!"); 833 834 if (DstGV->getAlignment() != SrcGV->getAlignment()) 835 return emitError( 836 "Appending variables with different alignment need to be linked!"); 837 838 if (DstGV->getVisibility() != SrcGV->getVisibility()) 839 return emitError( 840 "Appending variables with different visibility need to be linked!"); 841 842 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr()) 843 return emitError( 844 "Appending variables with different unnamed_addr need to be linked!"); 845 846 if (StringRef(DstGV->getSection()) != SrcGV->getSection()) 847 return emitError( 848 "Appending variables with different section name need to be linked!"); 849 850 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements(); 851 ArrayType *NewType = ArrayType::get(EltTy, NewSize); 852 853 // Create the new global variable. 854 GlobalVariable *NG = 855 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(), 856 DstGV->getLinkage(), /*init*/nullptr, /*name*/"", DstGV, 857 DstGV->getThreadLocalMode(), 858 DstGV->getType()->getAddressSpace()); 859 860 // Propagate alignment, visibility and section info. 861 copyGVAttributes(NG, DstGV); 862 863 AppendingVarInfo AVI; 864 AVI.NewGV = NG; 865 AVI.DstInit = DstGV->getInitializer(); 866 AVI.SrcInit = SrcGV->getInitializer(); 867 AppendingVars.push_back(AVI); 868 869 // Replace any uses of the two global variables with uses of the new 870 // global. 871 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType())); 872 873 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType())); 874 DstGV->eraseFromParent(); 875 876 // Track the source variable so we don't try to link it. 877 DoNotLinkFromSource.insert(SrcGV); 878 879 return false; 880 } 881 882 /// linkGlobalProto - Loop through the global variables in the src module and 883 /// merge them into the dest module. 884 bool ModuleLinker::linkGlobalProto(GlobalVariable *SGV) { 885 GlobalValue *DGV = getLinkedToGlobal(SGV); 886 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility; 887 bool HasUnnamedAddr = SGV->hasUnnamedAddr(); 888 889 bool LinkFromSrc = false; 890 Comdat *DC = nullptr; 891 if (const Comdat *SC = SGV->getComdat()) { 892 Comdat::SelectionKind SK; 893 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC]; 894 DC = DstM->getOrInsertComdat(SC->getName()); 895 DC->setSelectionKind(SK); 896 } 897 898 if (DGV) { 899 if (!DC) { 900 // Concatenation of appending linkage variables is magic and handled later. 901 if (DGV->hasAppendingLinkage() || SGV->hasAppendingLinkage()) 902 return linkAppendingVarProto(cast<GlobalVariable>(DGV), SGV); 903 904 // Determine whether linkage of these two globals follows the source 905 // module's definition or the destination module's definition. 906 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 907 GlobalValue::VisibilityTypes NV; 908 if (getLinkageResult(DGV, SGV, NewLinkage, NV, LinkFromSrc)) 909 return true; 910 NewVisibility = NV; 911 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr(); 912 913 // If we're not linking from the source, then keep the definition that we 914 // have. 915 if (!LinkFromSrc) { 916 // Special case for const propagation. 917 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) 918 if (DGVar->isDeclaration() && SGV->isConstant() && 919 !DGVar->isConstant()) 920 DGVar->setConstant(true); 921 922 // Set calculated linkage, visibility and unnamed_addr. 923 DGV->setLinkage(NewLinkage); 924 DGV->setVisibility(*NewVisibility); 925 DGV->setUnnamedAddr(HasUnnamedAddr); 926 } 927 } 928 929 if (!LinkFromSrc) { 930 // Make sure to remember this mapping. 931 ValueMap[SGV] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGV->getType())); 932 933 // Track the source global so that we don't attempt to copy it over when 934 // processing global initializers. 935 DoNotLinkFromSource.insert(SGV); 936 937 return false; 938 } 939 } 940 941 // If the Comdat this variable was inside of wasn't selected, skip it. 942 if (DC && !DGV && !LinkFromSrc) { 943 DoNotLinkFromSource.insert(SGV); 944 return false; 945 } 946 947 // No linking to be performed or linking from the source: simply create an 948 // identical version of the symbol over in the dest module... the 949 // initializer will be filled in later by LinkGlobalInits. 950 GlobalVariable *NewDGV = 951 new GlobalVariable(*DstM, TypeMap.get(SGV->getType()->getElementType()), 952 SGV->isConstant(), SGV->getLinkage(), /*init*/nullptr, 953 SGV->getName(), /*insertbefore*/nullptr, 954 SGV->getThreadLocalMode(), 955 SGV->getType()->getAddressSpace()); 956 // Propagate alignment, visibility and section info. 957 copyGVAttributes(NewDGV, SGV); 958 if (NewVisibility) 959 NewDGV->setVisibility(*NewVisibility); 960 NewDGV->setUnnamedAddr(HasUnnamedAddr); 961 962 if (DC) 963 NewDGV->setComdat(DC); 964 965 if (DGV) { 966 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV, DGV->getType())); 967 DGV->eraseFromParent(); 968 } 969 970 // Make sure to remember this mapping. 971 ValueMap[SGV] = NewDGV; 972 return false; 973 } 974 975 /// linkFunctionProto - Link the function in the source module into the 976 /// destination module if needed, setting up mapping information. 977 bool ModuleLinker::linkFunctionProto(Function *SF) { 978 GlobalValue *DGV = getLinkedToGlobal(SF); 979 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility; 980 bool HasUnnamedAddr = SF->hasUnnamedAddr(); 981 982 bool LinkFromSrc = false; 983 Comdat *DC = nullptr; 984 if (const Comdat *SC = SF->getComdat()) { 985 Comdat::SelectionKind SK; 986 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC]; 987 DC = DstM->getOrInsertComdat(SC->getName()); 988 DC->setSelectionKind(SK); 989 } 990 991 if (DGV) { 992 if (!DC) { 993 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 994 GlobalValue::VisibilityTypes NV; 995 if (getLinkageResult(DGV, SF, NewLinkage, NV, LinkFromSrc)) 996 return true; 997 NewVisibility = NV; 998 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr(); 999 1000 if (!LinkFromSrc) { 1001 // Set calculated linkage 1002 DGV->setLinkage(NewLinkage); 1003 DGV->setVisibility(*NewVisibility); 1004 DGV->setUnnamedAddr(HasUnnamedAddr); 1005 } 1006 } 1007 1008 if (!LinkFromSrc) { 1009 // Make sure to remember this mapping. 1010 ValueMap[SF] = ConstantExpr::getBitCast(DGV, TypeMap.get(SF->getType())); 1011 1012 // Track the function from the source module so we don't attempt to remap 1013 // it. 1014 DoNotLinkFromSource.insert(SF); 1015 1016 return false; 1017 } 1018 } 1019 1020 // If the function is to be lazily linked, don't create it just yet. 1021 // The ValueMaterializerTy will deal with creating it if it's used. 1022 if (!DGV && (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() || 1023 SF->hasAvailableExternallyLinkage())) { 1024 DoNotLinkFromSource.insert(SF); 1025 return false; 1026 } 1027 1028 // If the Comdat this function was inside of wasn't selected, skip it. 1029 if (DC && !DGV && !LinkFromSrc) { 1030 DoNotLinkFromSource.insert(SF); 1031 return false; 1032 } 1033 1034 // If there is no linkage to be performed or we are linking from the source, 1035 // bring SF over. 1036 Function *NewDF = Function::Create(TypeMap.get(SF->getFunctionType()), 1037 SF->getLinkage(), SF->getName(), DstM); 1038 copyGVAttributes(NewDF, SF); 1039 if (NewVisibility) 1040 NewDF->setVisibility(*NewVisibility); 1041 NewDF->setUnnamedAddr(HasUnnamedAddr); 1042 1043 if (DC) 1044 NewDF->setComdat(DC); 1045 1046 if (DGV) { 1047 // Any uses of DF need to change to NewDF, with cast. 1048 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, DGV->getType())); 1049 DGV->eraseFromParent(); 1050 } 1051 1052 ValueMap[SF] = NewDF; 1053 return false; 1054 } 1055 1056 /// LinkAliasProto - Set up prototypes for any aliases that come over from the 1057 /// source module. 1058 bool ModuleLinker::linkAliasProto(GlobalAlias *SGA) { 1059 GlobalValue *DGV = getLinkedToGlobal(SGA); 1060 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility; 1061 bool HasUnnamedAddr = SGA->hasUnnamedAddr(); 1062 1063 bool LinkFromSrc = false; 1064 Comdat *DC = nullptr; 1065 if (const Comdat *SC = SGA->getComdat()) { 1066 Comdat::SelectionKind SK; 1067 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC]; 1068 DC = DstM->getOrInsertComdat(SC->getName()); 1069 DC->setSelectionKind(SK); 1070 } 1071 1072 if (DGV) { 1073 if (!DC) { 1074 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 1075 GlobalValue::VisibilityTypes NV; 1076 if (getLinkageResult(DGV, SGA, NewLinkage, NV, LinkFromSrc)) 1077 return true; 1078 NewVisibility = NV; 1079 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr(); 1080 1081 if (!LinkFromSrc) { 1082 // Set calculated linkage. 1083 DGV->setLinkage(NewLinkage); 1084 DGV->setVisibility(*NewVisibility); 1085 DGV->setUnnamedAddr(HasUnnamedAddr); 1086 } 1087 } 1088 1089 if (!LinkFromSrc) { 1090 // Make sure to remember this mapping. 1091 ValueMap[SGA] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGA->getType())); 1092 1093 // Track the alias from the source module so we don't attempt to remap it. 1094 DoNotLinkFromSource.insert(SGA); 1095 1096 return false; 1097 } 1098 } 1099 1100 // If the Comdat this alias was inside of wasn't selected, skip it. 1101 if (DC && !DGV && !LinkFromSrc) { 1102 DoNotLinkFromSource.insert(SGA); 1103 return false; 1104 } 1105 1106 // If there is no linkage to be performed or we're linking from the source, 1107 // bring over SGA. 1108 auto *PTy = cast<PointerType>(TypeMap.get(SGA->getType())); 1109 auto *NewDA = 1110 GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(), 1111 SGA->getLinkage(), SGA->getName(), DstM); 1112 copyGVAttributes(NewDA, SGA); 1113 if (NewVisibility) 1114 NewDA->setVisibility(*NewVisibility); 1115 NewDA->setUnnamedAddr(HasUnnamedAddr); 1116 1117 if (DGV) { 1118 // Any uses of DGV need to change to NewDA, with cast. 1119 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDA, DGV->getType())); 1120 DGV->eraseFromParent(); 1121 } 1122 1123 ValueMap[SGA] = NewDA; 1124 return false; 1125 } 1126 1127 static void getArrayElements(Constant *C, SmallVectorImpl<Constant*> &Dest) { 1128 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements(); 1129 1130 for (unsigned i = 0; i != NumElements; ++i) 1131 Dest.push_back(C->getAggregateElement(i)); 1132 } 1133 1134 void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) { 1135 // Merge the initializer. 1136 SmallVector<Constant*, 16> Elements; 1137 getArrayElements(AVI.DstInit, Elements); 1138 1139 Constant *SrcInit = MapValue(AVI.SrcInit, ValueMap, RF_None, &TypeMap, &ValMaterializer); 1140 getArrayElements(SrcInit, Elements); 1141 1142 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType()); 1143 AVI.NewGV->setInitializer(ConstantArray::get(NewType, Elements)); 1144 } 1145 1146 /// linkGlobalInits - Update the initializers in the Dest module now that all 1147 /// globals that may be referenced are in Dest. 1148 void ModuleLinker::linkGlobalInits() { 1149 // Loop over all of the globals in the src module, mapping them over as we go 1150 for (Module::const_global_iterator I = SrcM->global_begin(), 1151 E = SrcM->global_end(); I != E; ++I) { 1152 1153 // Only process initialized GV's or ones not already in dest. 1154 if (!I->hasInitializer() || DoNotLinkFromSource.count(I)) continue; 1155 1156 // Grab destination global variable. 1157 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[I]); 1158 // Figure out what the initializer looks like in the dest module. 1159 DGV->setInitializer(MapValue(I->getInitializer(), ValueMap, 1160 RF_None, &TypeMap, &ValMaterializer)); 1161 } 1162 } 1163 1164 /// linkFunctionBody - Copy the source function over into the dest function and 1165 /// fix up references to values. At this point we know that Dest is an external 1166 /// function, and that Src is not. 1167 void ModuleLinker::linkFunctionBody(Function *Dst, Function *Src) { 1168 assert(Src && Dst && Dst->isDeclaration() && !Src->isDeclaration()); 1169 1170 // Go through and convert function arguments over, remembering the mapping. 1171 Function::arg_iterator DI = Dst->arg_begin(); 1172 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 1173 I != E; ++I, ++DI) { 1174 DI->setName(I->getName()); // Copy the name over. 1175 1176 // Add a mapping to our mapping. 1177 ValueMap[I] = DI; 1178 } 1179 1180 if (Mode == Linker::DestroySource) { 1181 // Splice the body of the source function into the dest function. 1182 Dst->getBasicBlockList().splice(Dst->end(), Src->getBasicBlockList()); 1183 1184 // At this point, all of the instructions and values of the function are now 1185 // copied over. The only problem is that they are still referencing values in 1186 // the Source function as operands. Loop through all of the operands of the 1187 // functions and patch them up to point to the local versions. 1188 for (Function::iterator BB = Dst->begin(), BE = Dst->end(); BB != BE; ++BB) 1189 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) 1190 RemapInstruction(I, ValueMap, RF_IgnoreMissingEntries, 1191 &TypeMap, &ValMaterializer); 1192 1193 } else { 1194 // Clone the body of the function into the dest function. 1195 SmallVector<ReturnInst*, 8> Returns; // Ignore returns. 1196 CloneFunctionInto(Dst, Src, ValueMap, false, Returns, "", nullptr, 1197 &TypeMap, &ValMaterializer); 1198 } 1199 1200 // There is no need to map the arguments anymore. 1201 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 1202 I != E; ++I) 1203 ValueMap.erase(I); 1204 1205 } 1206 1207 /// linkAliasBodies - Insert all of the aliases in Src into the Dest module. 1208 void ModuleLinker::linkAliasBodies() { 1209 for (Module::alias_iterator I = SrcM->alias_begin(), E = SrcM->alias_end(); 1210 I != E; ++I) { 1211 if (DoNotLinkFromSource.count(I)) 1212 continue; 1213 if (Constant *Aliasee = I->getAliasee()) { 1214 GlobalAlias *DA = cast<GlobalAlias>(ValueMap[I]); 1215 Constant *Val = 1216 MapValue(Aliasee, ValueMap, RF_None, &TypeMap, &ValMaterializer); 1217 DA->setAliasee(Val); 1218 } 1219 } 1220 } 1221 1222 /// linkNamedMDNodes - Insert all of the named MDNodes in Src into the Dest 1223 /// module. 1224 void ModuleLinker::linkNamedMDNodes() { 1225 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata(); 1226 for (Module::const_named_metadata_iterator I = SrcM->named_metadata_begin(), 1227 E = SrcM->named_metadata_end(); I != E; ++I) { 1228 // Don't link module flags here. Do them separately. 1229 if (&*I == SrcModFlags) continue; 1230 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(I->getName()); 1231 // Add Src elements into Dest node. 1232 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) 1233 DestNMD->addOperand(MapValue(I->getOperand(i), ValueMap, 1234 RF_None, &TypeMap, &ValMaterializer)); 1235 } 1236 } 1237 1238 /// linkModuleFlagsMetadata - Merge the linker flags in Src into the Dest 1239 /// module. 1240 bool ModuleLinker::linkModuleFlagsMetadata() { 1241 // If the source module has no module flags, we are done. 1242 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata(); 1243 if (!SrcModFlags) return false; 1244 1245 // If the destination module doesn't have module flags yet, then just copy 1246 // over the source module's flags. 1247 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata(); 1248 if (DstModFlags->getNumOperands() == 0) { 1249 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) 1250 DstModFlags->addOperand(SrcModFlags->getOperand(I)); 1251 1252 return false; 1253 } 1254 1255 // First build a map of the existing module flags and requirements. 1256 DenseMap<MDString*, MDNode*> Flags; 1257 SmallSetVector<MDNode*, 16> Requirements; 1258 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) { 1259 MDNode *Op = DstModFlags->getOperand(I); 1260 ConstantInt *Behavior = cast<ConstantInt>(Op->getOperand(0)); 1261 MDString *ID = cast<MDString>(Op->getOperand(1)); 1262 1263 if (Behavior->getZExtValue() == Module::Require) { 1264 Requirements.insert(cast<MDNode>(Op->getOperand(2))); 1265 } else { 1266 Flags[ID] = Op; 1267 } 1268 } 1269 1270 // Merge in the flags from the source module, and also collect its set of 1271 // requirements. 1272 bool HasErr = false; 1273 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) { 1274 MDNode *SrcOp = SrcModFlags->getOperand(I); 1275 ConstantInt *SrcBehavior = cast<ConstantInt>(SrcOp->getOperand(0)); 1276 MDString *ID = cast<MDString>(SrcOp->getOperand(1)); 1277 MDNode *DstOp = Flags.lookup(ID); 1278 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue(); 1279 1280 // If this is a requirement, add it and continue. 1281 if (SrcBehaviorValue == Module::Require) { 1282 // If the destination module does not already have this requirement, add 1283 // it. 1284 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) { 1285 DstModFlags->addOperand(SrcOp); 1286 } 1287 continue; 1288 } 1289 1290 // If there is no existing flag with this ID, just add it. 1291 if (!DstOp) { 1292 Flags[ID] = SrcOp; 1293 DstModFlags->addOperand(SrcOp); 1294 continue; 1295 } 1296 1297 // Otherwise, perform a merge. 1298 ConstantInt *DstBehavior = cast<ConstantInt>(DstOp->getOperand(0)); 1299 unsigned DstBehaviorValue = DstBehavior->getZExtValue(); 1300 1301 // If either flag has override behavior, handle it first. 1302 if (DstBehaviorValue == Module::Override) { 1303 // Diagnose inconsistent flags which both have override behavior. 1304 if (SrcBehaviorValue == Module::Override && 1305 SrcOp->getOperand(2) != DstOp->getOperand(2)) { 1306 HasErr |= emitError("linking module flags '" + ID->getString() + 1307 "': IDs have conflicting override values"); 1308 } 1309 continue; 1310 } else if (SrcBehaviorValue == Module::Override) { 1311 // Update the destination flag to that of the source. 1312 DstOp->replaceOperandWith(0, SrcBehavior); 1313 DstOp->replaceOperandWith(2, SrcOp->getOperand(2)); 1314 continue; 1315 } 1316 1317 // Diagnose inconsistent merge behavior types. 1318 if (SrcBehaviorValue != DstBehaviorValue) { 1319 HasErr |= emitError("linking module flags '" + ID->getString() + 1320 "': IDs have conflicting behaviors"); 1321 continue; 1322 } 1323 1324 // Perform the merge for standard behavior types. 1325 switch (SrcBehaviorValue) { 1326 case Module::Require: 1327 case Module::Override: llvm_unreachable("not possible"); 1328 case Module::Error: { 1329 // Emit an error if the values differ. 1330 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) { 1331 HasErr |= emitError("linking module flags '" + ID->getString() + 1332 "': IDs have conflicting values"); 1333 } 1334 continue; 1335 } 1336 case Module::Warning: { 1337 // Emit a warning if the values differ. 1338 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) { 1339 if (!SuppressWarnings) { 1340 errs() << "WARNING: linking module flags '" << ID->getString() 1341 << "': IDs have conflicting values"; 1342 } 1343 } 1344 continue; 1345 } 1346 case Module::Append: { 1347 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2)); 1348 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2)); 1349 unsigned NumOps = DstValue->getNumOperands() + SrcValue->getNumOperands(); 1350 Value **VP, **Values = VP = new Value*[NumOps]; 1351 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i, ++VP) 1352 *VP = DstValue->getOperand(i); 1353 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i, ++VP) 1354 *VP = SrcValue->getOperand(i); 1355 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(), 1356 ArrayRef<Value*>(Values, 1357 NumOps))); 1358 delete[] Values; 1359 break; 1360 } 1361 case Module::AppendUnique: { 1362 SmallSetVector<Value*, 16> Elts; 1363 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2)); 1364 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2)); 1365 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i) 1366 Elts.insert(DstValue->getOperand(i)); 1367 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i) 1368 Elts.insert(SrcValue->getOperand(i)); 1369 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(), 1370 ArrayRef<Value*>(Elts.begin(), 1371 Elts.end()))); 1372 break; 1373 } 1374 } 1375 } 1376 1377 // Check all of the requirements. 1378 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) { 1379 MDNode *Requirement = Requirements[I]; 1380 MDString *Flag = cast<MDString>(Requirement->getOperand(0)); 1381 Value *ReqValue = Requirement->getOperand(1); 1382 1383 MDNode *Op = Flags[Flag]; 1384 if (!Op || Op->getOperand(2) != ReqValue) { 1385 HasErr |= emitError("linking module flags '" + Flag->getString() + 1386 "': does not have the required value"); 1387 continue; 1388 } 1389 } 1390 1391 return HasErr; 1392 } 1393 1394 bool ModuleLinker::run() { 1395 assert(DstM && "Null destination module"); 1396 assert(SrcM && "Null source module"); 1397 1398 // Inherit the target data from the source module if the destination module 1399 // doesn't have one already. 1400 if (!DstM->getDataLayout() && SrcM->getDataLayout()) 1401 DstM->setDataLayout(SrcM->getDataLayout()); 1402 1403 // Copy the target triple from the source to dest if the dest's is empty. 1404 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty()) 1405 DstM->setTargetTriple(SrcM->getTargetTriple()); 1406 1407 if (SrcM->getDataLayout() && DstM->getDataLayout() && 1408 *SrcM->getDataLayout() != *DstM->getDataLayout()) { 1409 if (!SuppressWarnings) { 1410 errs() << "WARNING: Linking two modules of different data layouts: '" 1411 << SrcM->getModuleIdentifier() << "' is '" 1412 << SrcM->getDataLayoutStr() << "' whereas '" 1413 << DstM->getModuleIdentifier() << "' is '" 1414 << DstM->getDataLayoutStr() << "'\n"; 1415 } 1416 } 1417 if (!SrcM->getTargetTriple().empty() && 1418 DstM->getTargetTriple() != SrcM->getTargetTriple()) { 1419 if (!SuppressWarnings) { 1420 errs() << "WARNING: Linking two modules of different target triples: " 1421 << SrcM->getModuleIdentifier() << "' is '" 1422 << SrcM->getTargetTriple() << "' whereas '" 1423 << DstM->getModuleIdentifier() << "' is '" 1424 << DstM->getTargetTriple() << "'\n"; 1425 } 1426 } 1427 1428 // Append the module inline asm string. 1429 if (!SrcM->getModuleInlineAsm().empty()) { 1430 if (DstM->getModuleInlineAsm().empty()) 1431 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm()); 1432 else 1433 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+ 1434 SrcM->getModuleInlineAsm()); 1435 } 1436 1437 // Loop over all of the linked values to compute type mappings. 1438 computeTypeMapping(); 1439 1440 ComdatsChosen.clear(); 1441 for (const StringMapEntry<llvm::Comdat> &SMEC : SrcM->getComdatSymbolTable()) { 1442 const Comdat &C = SMEC.getValue(); 1443 if (ComdatsChosen.count(&C)) 1444 continue; 1445 Comdat::SelectionKind SK; 1446 bool LinkFromSrc; 1447 if (getComdatResult(&C, SK, LinkFromSrc)) 1448 return true; 1449 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc); 1450 } 1451 1452 // Insert all of the globals in src into the DstM module... without linking 1453 // initializers (which could refer to functions not yet mapped over). 1454 for (Module::global_iterator I = SrcM->global_begin(), 1455 E = SrcM->global_end(); I != E; ++I) 1456 if (linkGlobalProto(I)) 1457 return true; 1458 1459 // Link the functions together between the two modules, without doing function 1460 // bodies... this just adds external function prototypes to the DstM 1461 // function... We do this so that when we begin processing function bodies, 1462 // all of the global values that may be referenced are available in our 1463 // ValueMap. 1464 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I) 1465 if (linkFunctionProto(I)) 1466 return true; 1467 1468 // If there were any aliases, link them now. 1469 for (Module::alias_iterator I = SrcM->alias_begin(), 1470 E = SrcM->alias_end(); I != E; ++I) 1471 if (linkAliasProto(I)) 1472 return true; 1473 1474 for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i) 1475 linkAppendingVarInit(AppendingVars[i]); 1476 1477 // Link in the function bodies that are defined in the source module into 1478 // DstM. 1479 for (Module::iterator SF = SrcM->begin(), E = SrcM->end(); SF != E; ++SF) { 1480 // Skip if not linking from source. 1481 if (DoNotLinkFromSource.count(SF)) continue; 1482 1483 Function *DF = cast<Function>(ValueMap[SF]); 1484 if (SF->hasPrefixData()) { 1485 // Link in the prefix data. 1486 DF->setPrefixData(MapValue( 1487 SF->getPrefixData(), ValueMap, RF_None, &TypeMap, &ValMaterializer)); 1488 } 1489 1490 // Skip if no body (function is external) or materialize. 1491 if (SF->isDeclaration()) { 1492 if (!SF->isMaterializable()) 1493 continue; 1494 if (SF->Materialize(&ErrorMsg)) 1495 return true; 1496 } 1497 1498 linkFunctionBody(DF, SF); 1499 SF->Dematerialize(); 1500 } 1501 1502 // Resolve all uses of aliases with aliasees. 1503 linkAliasBodies(); 1504 1505 // Remap all of the named MDNodes in Src into the DstM module. We do this 1506 // after linking GlobalValues so that MDNodes that reference GlobalValues 1507 // are properly remapped. 1508 linkNamedMDNodes(); 1509 1510 // Merge the module flags into the DstM module. 1511 if (linkModuleFlagsMetadata()) 1512 return true; 1513 1514 // Update the initializers in the DstM module now that all globals that may 1515 // be referenced are in DstM. 1516 linkGlobalInits(); 1517 1518 // Process vector of lazily linked in functions. 1519 bool LinkedInAnyFunctions; 1520 do { 1521 LinkedInAnyFunctions = false; 1522 1523 for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(), 1524 E = LazilyLinkFunctions.end(); I != E; ++I) { 1525 Function *SF = *I; 1526 if (!SF) 1527 continue; 1528 1529 Function *DF = cast<Function>(ValueMap[SF]); 1530 if (SF->hasPrefixData()) { 1531 // Link in the prefix data. 1532 DF->setPrefixData(MapValue(SF->getPrefixData(), 1533 ValueMap, 1534 RF_None, 1535 &TypeMap, 1536 &ValMaterializer)); 1537 } 1538 1539 // Materialize if necessary. 1540 if (SF->isDeclaration()) { 1541 if (!SF->isMaterializable()) 1542 continue; 1543 if (SF->Materialize(&ErrorMsg)) 1544 return true; 1545 } 1546 1547 // Erase from vector *before* the function body is linked - linkFunctionBody could 1548 // invalidate I. 1549 LazilyLinkFunctions.erase(I); 1550 1551 // Link in function body. 1552 linkFunctionBody(DF, SF); 1553 SF->Dematerialize(); 1554 1555 // Set flag to indicate we may have more functions to lazily link in 1556 // since we linked in a function. 1557 LinkedInAnyFunctions = true; 1558 break; 1559 } 1560 } while (LinkedInAnyFunctions); 1561 1562 // Now that all of the types from the source are used, resolve any structs 1563 // copied over to the dest that didn't exist there. 1564 TypeMap.linkDefinedTypeBodies(); 1565 1566 return false; 1567 } 1568 1569 Linker::Linker(Module *M, bool SuppressWarnings) 1570 : Composite(M), SuppressWarnings(SuppressWarnings) { 1571 TypeFinder StructTypes; 1572 StructTypes.run(*M, true); 1573 IdentifiedStructTypes.insert(StructTypes.begin(), StructTypes.end()); 1574 } 1575 1576 Linker::~Linker() { 1577 } 1578 1579 void Linker::deleteModule() { 1580 delete Composite; 1581 Composite = nullptr; 1582 } 1583 1584 bool Linker::linkInModule(Module *Src, unsigned Mode, std::string *ErrorMsg) { 1585 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src, Mode, 1586 SuppressWarnings); 1587 if (TheLinker.run()) { 1588 if (ErrorMsg) 1589 *ErrorMsg = TheLinker.ErrorMsg; 1590 return true; 1591 } 1592 return false; 1593 } 1594 1595 //===----------------------------------------------------------------------===// 1596 // LinkModules entrypoint. 1597 //===----------------------------------------------------------------------===// 1598 1599 /// LinkModules - This function links two modules together, with the resulting 1600 /// Dest module modified to be the composite of the two input modules. If an 1601 /// error occurs, true is returned and ErrorMsg (if not null) is set to indicate 1602 /// the problem. Upon failure, the Dest module could be in a modified state, 1603 /// and shouldn't be relied on to be consistent. 1604 bool Linker::LinkModules(Module *Dest, Module *Src, unsigned Mode, 1605 std::string *ErrorMsg) { 1606 Linker L(Dest); 1607 return L.linkInModule(Src, Mode, ErrorMsg); 1608 } 1609 1610 //===----------------------------------------------------------------------===// 1611 // C API. 1612 //===----------------------------------------------------------------------===// 1613 1614 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src, 1615 LLVMLinkerMode Mode, char **OutMessages) { 1616 std::string Messages; 1617 LLVMBool Result = Linker::LinkModules(unwrap(Dest), unwrap(Src), 1618 Mode, OutMessages? &Messages : nullptr); 1619 if (OutMessages) 1620 *OutMessages = strdup(Messages.c_str()); 1621 return Result; 1622 } 1623