LinkModules.cpp revision dce4a407a24b04eebc6a376f8e62b41aaa7b071f
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> 27using namespace llvm; 28 29 30//===----------------------------------------------------------------------===// 31// TypeMap implementation. 32//===----------------------------------------------------------------------===// 33 34namespace { 35 typedef SmallPtrSet<StructType*, 32> TypeSet; 36 37class TypeMapTy : public ValueMapTypeRemapper { 38 /// MappedTypes - This is a mapping from a source type to a destination type 39 /// to use. 40 DenseMap<Type*, Type*> MappedTypes; 41 42 /// SpeculativeTypes - When checking to see if two subgraphs are isomorphic, 43 /// we speculatively add types to MappedTypes, but keep track of them here in 44 /// case we need to roll back. 45 SmallVector<Type*, 16> SpeculativeTypes; 46 47 /// SrcDefinitionsToResolve - This is a list of non-opaque structs in the 48 /// source module that are mapped to an opaque struct in the destination 49 /// module. 50 SmallVector<StructType*, 16> SrcDefinitionsToResolve; 51 52 /// DstResolvedOpaqueTypes - This is the set of opaque types in the 53 /// destination modules who are getting a body from the source module. 54 SmallPtrSet<StructType*, 16> DstResolvedOpaqueTypes; 55 56public: 57 TypeMapTy(TypeSet &Set) : DstStructTypesSet(Set) {} 58 59 TypeSet &DstStructTypesSet; 60 /// addTypeMapping - Indicate that the specified type in the destination 61 /// module is conceptually equivalent to the specified type in the source 62 /// module. 63 void addTypeMapping(Type *DstTy, Type *SrcTy); 64 65 /// linkDefinedTypeBodies - Produce a body for an opaque type in the dest 66 /// module from a type definition in the source module. 67 void linkDefinedTypeBodies(); 68 69 /// get - Return the mapped type to use for the specified input type from the 70 /// source module. 71 Type *get(Type *SrcTy); 72 73 FunctionType *get(FunctionType *T) {return cast<FunctionType>(get((Type*)T));} 74 75 /// dump - Dump out the type map for debugging purposes. 76 void dump() const { 77 for (DenseMap<Type*, Type*>::const_iterator 78 I = MappedTypes.begin(), E = MappedTypes.end(); I != E; ++I) { 79 dbgs() << "TypeMap: "; 80 I->first->dump(); 81 dbgs() << " => "; 82 I->second->dump(); 83 dbgs() << '\n'; 84 } 85 } 86 87private: 88 Type *getImpl(Type *T); 89 /// remapType - Implement the ValueMapTypeRemapper interface. 90 Type *remapType(Type *SrcTy) override { 91 return get(SrcTy); 92 } 93 94 bool areTypesIsomorphic(Type *DstTy, Type *SrcTy); 95}; 96} 97 98void TypeMapTy::addTypeMapping(Type *DstTy, Type *SrcTy) { 99 Type *&Entry = MappedTypes[SrcTy]; 100 if (Entry) return; 101 102 if (DstTy == SrcTy) { 103 Entry = DstTy; 104 return; 105 } 106 107 // Check to see if these types are recursively isomorphic and establish a 108 // mapping between them if so. 109 if (!areTypesIsomorphic(DstTy, SrcTy)) { 110 // Oops, they aren't isomorphic. Just discard this request by rolling out 111 // any speculative mappings we've established. 112 for (unsigned i = 0, e = SpeculativeTypes.size(); i != e; ++i) 113 MappedTypes.erase(SpeculativeTypes[i]); 114 } 115 SpeculativeTypes.clear(); 116} 117 118/// areTypesIsomorphic - Recursively walk this pair of types, returning true 119/// if they are isomorphic, false if they are not. 120bool TypeMapTy::areTypesIsomorphic(Type *DstTy, Type *SrcTy) { 121 // Two types with differing kinds are clearly not isomorphic. 122 if (DstTy->getTypeID() != SrcTy->getTypeID()) return false; 123 124 // If we have an entry in the MappedTypes table, then we have our answer. 125 Type *&Entry = MappedTypes[SrcTy]; 126 if (Entry) 127 return Entry == DstTy; 128 129 // Two identical types are clearly isomorphic. Remember this 130 // non-speculatively. 131 if (DstTy == SrcTy) { 132 Entry = DstTy; 133 return true; 134 } 135 136 // Okay, we have two types with identical kinds that we haven't seen before. 137 138 // If this is an opaque struct type, special case it. 139 if (StructType *SSTy = dyn_cast<StructType>(SrcTy)) { 140 // Mapping an opaque type to any struct, just keep the dest struct. 141 if (SSTy->isOpaque()) { 142 Entry = DstTy; 143 SpeculativeTypes.push_back(SrcTy); 144 return true; 145 } 146 147 // Mapping a non-opaque source type to an opaque dest. If this is the first 148 // type that we're mapping onto this destination type then we succeed. Keep 149 // the dest, but fill it in later. This doesn't need to be speculative. If 150 // this is the second (different) type that we're trying to map onto the 151 // same opaque type then we fail. 152 if (cast<StructType>(DstTy)->isOpaque()) { 153 // We can only map one source type onto the opaque destination type. 154 if (!DstResolvedOpaqueTypes.insert(cast<StructType>(DstTy))) 155 return false; 156 SrcDefinitionsToResolve.push_back(SSTy); 157 Entry = DstTy; 158 return true; 159 } 160 } 161 162 // If the number of subtypes disagree between the two types, then we fail. 163 if (SrcTy->getNumContainedTypes() != DstTy->getNumContainedTypes()) 164 return false; 165 166 // Fail if any of the extra properties (e.g. array size) of the type disagree. 167 if (isa<IntegerType>(DstTy)) 168 return false; // bitwidth disagrees. 169 if (PointerType *PT = dyn_cast<PointerType>(DstTy)) { 170 if (PT->getAddressSpace() != cast<PointerType>(SrcTy)->getAddressSpace()) 171 return false; 172 173 } else if (FunctionType *FT = dyn_cast<FunctionType>(DstTy)) { 174 if (FT->isVarArg() != cast<FunctionType>(SrcTy)->isVarArg()) 175 return false; 176 } else if (StructType *DSTy = dyn_cast<StructType>(DstTy)) { 177 StructType *SSTy = cast<StructType>(SrcTy); 178 if (DSTy->isLiteral() != SSTy->isLiteral() || 179 DSTy->isPacked() != SSTy->isPacked()) 180 return false; 181 } else if (ArrayType *DATy = dyn_cast<ArrayType>(DstTy)) { 182 if (DATy->getNumElements() != cast<ArrayType>(SrcTy)->getNumElements()) 183 return false; 184 } else if (VectorType *DVTy = dyn_cast<VectorType>(DstTy)) { 185 if (DVTy->getNumElements() != cast<VectorType>(SrcTy)->getNumElements()) 186 return false; 187 } 188 189 // Otherwise, we speculate that these two types will line up and recursively 190 // check the subelements. 191 Entry = DstTy; 192 SpeculativeTypes.push_back(SrcTy); 193 194 for (unsigned i = 0, e = SrcTy->getNumContainedTypes(); i != e; ++i) 195 if (!areTypesIsomorphic(DstTy->getContainedType(i), 196 SrcTy->getContainedType(i))) 197 return false; 198 199 // If everything seems to have lined up, then everything is great. 200 return true; 201} 202 203/// linkDefinedTypeBodies - Produce a body for an opaque type in the dest 204/// module from a type definition in the source module. 205void TypeMapTy::linkDefinedTypeBodies() { 206 SmallVector<Type*, 16> Elements; 207 SmallString<16> TmpName; 208 209 // Note that processing entries in this loop (calling 'get') can add new 210 // entries to the SrcDefinitionsToResolve vector. 211 while (!SrcDefinitionsToResolve.empty()) { 212 StructType *SrcSTy = SrcDefinitionsToResolve.pop_back_val(); 213 StructType *DstSTy = cast<StructType>(MappedTypes[SrcSTy]); 214 215 // TypeMap is a many-to-one mapping, if there were multiple types that 216 // provide a body for DstSTy then previous iterations of this loop may have 217 // already handled it. Just ignore this case. 218 if (!DstSTy->isOpaque()) continue; 219 assert(!SrcSTy->isOpaque() && "Not resolving a definition?"); 220 221 // Map the body of the source type over to a new body for the dest type. 222 Elements.resize(SrcSTy->getNumElements()); 223 for (unsigned i = 0, e = Elements.size(); i != e; ++i) 224 Elements[i] = getImpl(SrcSTy->getElementType(i)); 225 226 DstSTy->setBody(Elements, SrcSTy->isPacked()); 227 228 // If DstSTy has no name or has a longer name than STy, then viciously steal 229 // STy's name. 230 if (!SrcSTy->hasName()) continue; 231 StringRef SrcName = SrcSTy->getName(); 232 233 if (!DstSTy->hasName() || DstSTy->getName().size() > SrcName.size()) { 234 TmpName.insert(TmpName.end(), SrcName.begin(), SrcName.end()); 235 SrcSTy->setName(""); 236 DstSTy->setName(TmpName.str()); 237 TmpName.clear(); 238 } 239 } 240 241 DstResolvedOpaqueTypes.clear(); 242} 243 244/// get - Return the mapped type to use for the specified input type from the 245/// source module. 246Type *TypeMapTy::get(Type *Ty) { 247 Type *Result = getImpl(Ty); 248 249 // If this caused a reference to any struct type, resolve it before returning. 250 if (!SrcDefinitionsToResolve.empty()) 251 linkDefinedTypeBodies(); 252 return Result; 253} 254 255/// getImpl - This is the recursive version of get(). 256Type *TypeMapTy::getImpl(Type *Ty) { 257 // If we already have an entry for this type, return it. 258 Type **Entry = &MappedTypes[Ty]; 259 if (*Entry) return *Entry; 260 261 // If this is not a named struct type, then just map all of the elements and 262 // then rebuild the type from inside out. 263 if (!isa<StructType>(Ty) || cast<StructType>(Ty)->isLiteral()) { 264 // If there are no element types to map, then the type is itself. This is 265 // true for the anonymous {} struct, things like 'float', integers, etc. 266 if (Ty->getNumContainedTypes() == 0) 267 return *Entry = Ty; 268 269 // Remap all of the elements, keeping track of whether any of them change. 270 bool AnyChange = false; 271 SmallVector<Type*, 4> ElementTypes; 272 ElementTypes.resize(Ty->getNumContainedTypes()); 273 for (unsigned i = 0, e = Ty->getNumContainedTypes(); i != e; ++i) { 274 ElementTypes[i] = getImpl(Ty->getContainedType(i)); 275 AnyChange |= ElementTypes[i] != Ty->getContainedType(i); 276 } 277 278 // If we found our type while recursively processing stuff, just use it. 279 Entry = &MappedTypes[Ty]; 280 if (*Entry) return *Entry; 281 282 // If all of the element types mapped directly over, then the type is usable 283 // as-is. 284 if (!AnyChange) 285 return *Entry = Ty; 286 287 // Otherwise, rebuild a modified type. 288 switch (Ty->getTypeID()) { 289 default: llvm_unreachable("unknown derived type to remap"); 290 case Type::ArrayTyID: 291 return *Entry = ArrayType::get(ElementTypes[0], 292 cast<ArrayType>(Ty)->getNumElements()); 293 case Type::VectorTyID: 294 return *Entry = VectorType::get(ElementTypes[0], 295 cast<VectorType>(Ty)->getNumElements()); 296 case Type::PointerTyID: 297 return *Entry = PointerType::get(ElementTypes[0], 298 cast<PointerType>(Ty)->getAddressSpace()); 299 case Type::FunctionTyID: 300 return *Entry = FunctionType::get(ElementTypes[0], 301 makeArrayRef(ElementTypes).slice(1), 302 cast<FunctionType>(Ty)->isVarArg()); 303 case Type::StructTyID: 304 // Note that this is only reached for anonymous structs. 305 return *Entry = StructType::get(Ty->getContext(), ElementTypes, 306 cast<StructType>(Ty)->isPacked()); 307 } 308 } 309 310 // Otherwise, this is an unmapped named struct. If the struct can be directly 311 // mapped over, just use it as-is. This happens in a case when the linked-in 312 // module has something like: 313 // %T = type {%T*, i32} 314 // @GV = global %T* null 315 // where T does not exist at all in the destination module. 316 // 317 // The other case we watch for is when the type is not in the destination 318 // module, but that it has to be rebuilt because it refers to something that 319 // is already mapped. For example, if the destination module has: 320 // %A = type { i32 } 321 // and the source module has something like 322 // %A' = type { i32 } 323 // %B = type { %A'* } 324 // @GV = global %B* null 325 // then we want to create a new type: "%B = type { %A*}" and have it take the 326 // pristine "%B" name from the source module. 327 // 328 // To determine which case this is, we have to recursively walk the type graph 329 // speculating that we'll be able to reuse it unmodified. Only if this is 330 // safe would we map the entire thing over. Because this is an optimization, 331 // and is not required for the prettiness of the linked module, we just skip 332 // it and always rebuild a type here. 333 StructType *STy = cast<StructType>(Ty); 334 335 // If the type is opaque, we can just use it directly. 336 if (STy->isOpaque()) { 337 // A named structure type from src module is used. Add it to the Set of 338 // identified structs in the destination module. 339 DstStructTypesSet.insert(STy); 340 return *Entry = STy; 341 } 342 343 // Otherwise we create a new type and resolve its body later. This will be 344 // resolved by the top level of get(). 345 SrcDefinitionsToResolve.push_back(STy); 346 StructType *DTy = StructType::create(STy->getContext()); 347 // A new identified structure type was created. Add it to the set of 348 // identified structs in the destination module. 349 DstStructTypesSet.insert(DTy); 350 DstResolvedOpaqueTypes.insert(DTy); 351 return *Entry = DTy; 352} 353 354//===----------------------------------------------------------------------===// 355// ModuleLinker implementation. 356//===----------------------------------------------------------------------===// 357 358namespace { 359 class ModuleLinker; 360 361 /// ValueMaterializerTy - Creates prototypes for functions that are lazily 362 /// linked on the fly. This speeds up linking for modules with many 363 /// lazily linked functions of which few get used. 364 class ValueMaterializerTy : public ValueMaterializer { 365 TypeMapTy &TypeMap; 366 Module *DstM; 367 std::vector<Function*> &LazilyLinkFunctions; 368 public: 369 ValueMaterializerTy(TypeMapTy &TypeMap, Module *DstM, 370 std::vector<Function*> &LazilyLinkFunctions) : 371 ValueMaterializer(), TypeMap(TypeMap), DstM(DstM), 372 LazilyLinkFunctions(LazilyLinkFunctions) { 373 } 374 375 Value *materializeValueFor(Value *V) override; 376 }; 377 378 /// ModuleLinker - This is an implementation class for the LinkModules 379 /// function, which is the entrypoint for this file. 380 class ModuleLinker { 381 Module *DstM, *SrcM; 382 383 TypeMapTy TypeMap; 384 ValueMaterializerTy ValMaterializer; 385 386 /// ValueMap - Mapping of values from what they used to be in Src, to what 387 /// they are now in DstM. ValueToValueMapTy is a ValueMap, which involves 388 /// some overhead due to the use of Value handles which the Linker doesn't 389 /// actually need, but this allows us to reuse the ValueMapper code. 390 ValueToValueMapTy ValueMap; 391 392 std::vector<std::pair<GlobalValue *, GlobalAlias *>> ReplaceWithAlias; 393 394 struct AppendingVarInfo { 395 GlobalVariable *NewGV; // New aggregate global in dest module. 396 Constant *DstInit; // Old initializer from dest module. 397 Constant *SrcInit; // Old initializer from src module. 398 }; 399 400 std::vector<AppendingVarInfo> AppendingVars; 401 402 unsigned Mode; // Mode to treat source module. 403 404 // Set of items not to link in from source. 405 SmallPtrSet<const Value*, 16> DoNotLinkFromSource; 406 407 // Vector of functions to lazily link in. 408 std::vector<Function*> LazilyLinkFunctions; 409 410 bool SuppressWarnings; 411 412 public: 413 std::string ErrorMsg; 414 415 ModuleLinker(Module *dstM, TypeSet &Set, Module *srcM, unsigned mode, 416 bool SuppressWarnings=false) 417 : DstM(dstM), SrcM(srcM), TypeMap(Set), 418 ValMaterializer(TypeMap, DstM, LazilyLinkFunctions), Mode(mode), 419 SuppressWarnings(SuppressWarnings) {} 420 421 bool run(); 422 423 private: 424 /// emitError - Helper method for setting a message and returning an error 425 /// code. 426 bool emitError(const Twine &Message) { 427 ErrorMsg = Message.str(); 428 return true; 429 } 430 431 /// getLinkageResult - This analyzes the two global values and determines 432 /// what the result will look like in the destination module. 433 bool getLinkageResult(GlobalValue *Dest, const GlobalValue *Src, 434 GlobalValue::LinkageTypes <, 435 GlobalValue::VisibilityTypes &Vis, 436 bool &LinkFromSrc); 437 438 /// getLinkedToGlobal - Given a global in the source module, return the 439 /// global in the destination module that is being linked to, if any. 440 GlobalValue *getLinkedToGlobal(GlobalValue *SrcGV) { 441 // If the source has no name it can't link. If it has local linkage, 442 // there is no name match-up going on. 443 if (!SrcGV->hasName() || SrcGV->hasLocalLinkage()) 444 return nullptr; 445 446 // Otherwise see if we have a match in the destination module's symtab. 447 GlobalValue *DGV = DstM->getNamedValue(SrcGV->getName()); 448 if (!DGV) return nullptr; 449 450 // If we found a global with the same name in the dest module, but it has 451 // internal linkage, we are really not doing any linkage here. 452 if (DGV->hasLocalLinkage()) 453 return nullptr; 454 455 // Otherwise, we do in fact link to the destination global. 456 return DGV; 457 } 458 459 void computeTypeMapping(); 460 461 bool linkAppendingVarProto(GlobalVariable *DstGV, GlobalVariable *SrcGV); 462 bool linkGlobalProto(GlobalVariable *SrcGV); 463 bool linkFunctionProto(Function *SrcF); 464 bool linkAliasProto(GlobalAlias *SrcA); 465 bool linkModuleFlagsMetadata(); 466 467 void linkAppendingVarInit(const AppendingVarInfo &AVI); 468 void linkGlobalInits(); 469 void linkFunctionBody(Function *Dst, Function *Src); 470 void linkAliasBodies(); 471 void linkNamedMDNodes(); 472 }; 473} 474 475/// forceRenaming - The LLVM SymbolTable class autorenames globals that conflict 476/// in the symbol table. This is good for all clients except for us. Go 477/// through the trouble to force this back. 478static void forceRenaming(GlobalValue *GV, StringRef Name) { 479 // If the global doesn't force its name or if it already has the right name, 480 // there is nothing for us to do. 481 if (GV->hasLocalLinkage() || GV->getName() == Name) 482 return; 483 484 Module *M = GV->getParent(); 485 486 // If there is a conflict, rename the conflict. 487 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) { 488 GV->takeName(ConflictGV); 489 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed 490 assert(ConflictGV->getName() != Name && "forceRenaming didn't work"); 491 } else { 492 GV->setName(Name); // Force the name back 493 } 494} 495 496/// copyGVAttributes - copy additional attributes (those not needed to construct 497/// a GlobalValue) from the SrcGV to the DestGV. 498static void copyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) { 499 // Use the maximum alignment, rather than just copying the alignment of SrcGV. 500 auto *DestGO = dyn_cast<GlobalObject>(DestGV); 501 unsigned Alignment; 502 if (DestGO) 503 Alignment = std::max(DestGO->getAlignment(), SrcGV->getAlignment()); 504 505 DestGV->copyAttributesFrom(SrcGV); 506 507 if (DestGO) 508 DestGO->setAlignment(Alignment); 509 510 forceRenaming(DestGV, SrcGV->getName()); 511} 512 513static bool isLessConstraining(GlobalValue::VisibilityTypes a, 514 GlobalValue::VisibilityTypes b) { 515 if (a == GlobalValue::HiddenVisibility) 516 return false; 517 if (b == GlobalValue::HiddenVisibility) 518 return true; 519 if (a == GlobalValue::ProtectedVisibility) 520 return false; 521 if (b == GlobalValue::ProtectedVisibility) 522 return true; 523 return false; 524} 525 526Value *ValueMaterializerTy::materializeValueFor(Value *V) { 527 Function *SF = dyn_cast<Function>(V); 528 if (!SF) 529 return nullptr; 530 531 Function *DF = Function::Create(TypeMap.get(SF->getFunctionType()), 532 SF->getLinkage(), SF->getName(), DstM); 533 copyGVAttributes(DF, SF); 534 535 LazilyLinkFunctions.push_back(SF); 536 return DF; 537} 538 539 540/// getLinkageResult - This analyzes the two global values and determines what 541/// the result will look like in the destination module. In particular, it 542/// computes the resultant linkage type and visibility, computes whether the 543/// global in the source should be copied over to the destination (replacing 544/// the existing one), and computes whether this linkage is an error or not. 545bool ModuleLinker::getLinkageResult(GlobalValue *Dest, const GlobalValue *Src, 546 GlobalValue::LinkageTypes <, 547 GlobalValue::VisibilityTypes &Vis, 548 bool &LinkFromSrc) { 549 assert(Dest && "Must have two globals being queried"); 550 assert(!Src->hasLocalLinkage() && 551 "If Src has internal linkage, Dest shouldn't be set!"); 552 553 bool SrcIsDeclaration = Src->isDeclaration() && !Src->isMaterializable(); 554 bool DestIsDeclaration = Dest->isDeclaration(); 555 556 if (SrcIsDeclaration) { 557 // If Src is external or if both Src & Dest are external.. Just link the 558 // external globals, we aren't adding anything. 559 if (Src->hasDLLImportStorageClass()) { 560 // If one of GVs is marked as DLLImport, result should be dllimport'ed. 561 if (DestIsDeclaration) { 562 LinkFromSrc = true; 563 LT = Src->getLinkage(); 564 } 565 } else if (Dest->hasExternalWeakLinkage()) { 566 // If the Dest is weak, use the source linkage. 567 LinkFromSrc = true; 568 LT = Src->getLinkage(); 569 } else { 570 LinkFromSrc = false; 571 LT = Dest->getLinkage(); 572 } 573 } else if (DestIsDeclaration && !Dest->hasDLLImportStorageClass()) { 574 // If Dest is external but Src is not: 575 LinkFromSrc = true; 576 LT = Src->getLinkage(); 577 } else if (Src->isWeakForLinker()) { 578 // At this point we know that Dest has LinkOnce, External*, Weak, Common, 579 // or DLL* linkage. 580 if (Dest->hasExternalWeakLinkage() || 581 Dest->hasAvailableExternallyLinkage() || 582 (Dest->hasLinkOnceLinkage() && 583 (Src->hasWeakLinkage() || Src->hasCommonLinkage()))) { 584 LinkFromSrc = true; 585 LT = Src->getLinkage(); 586 } else { 587 LinkFromSrc = false; 588 LT = Dest->getLinkage(); 589 } 590 } else if (Dest->isWeakForLinker()) { 591 // At this point we know that Src has External* or DLL* linkage. 592 if (Src->hasExternalWeakLinkage()) { 593 LinkFromSrc = false; 594 LT = Dest->getLinkage(); 595 } else { 596 LinkFromSrc = true; 597 LT = GlobalValue::ExternalLinkage; 598 } 599 } else { 600 assert((Dest->hasExternalLinkage() || Dest->hasExternalWeakLinkage()) && 601 (Src->hasExternalLinkage() || Src->hasExternalWeakLinkage()) && 602 "Unexpected linkage type!"); 603 return emitError("Linking globals named '" + Src->getName() + 604 "': symbol multiply defined!"); 605 } 606 607 // Compute the visibility. We follow the rules in the System V Application 608 // Binary Interface. 609 assert(!GlobalValue::isLocalLinkage(LT) && 610 "Symbols with local linkage should not be merged"); 611 Vis = isLessConstraining(Src->getVisibility(), Dest->getVisibility()) ? 612 Dest->getVisibility() : Src->getVisibility(); 613 return false; 614} 615 616/// computeTypeMapping - Loop over all of the linked values to compute type 617/// mappings. For example, if we link "extern Foo *x" and "Foo *x = NULL", then 618/// we have two struct types 'Foo' but one got renamed when the module was 619/// loaded into the same LLVMContext. 620void ModuleLinker::computeTypeMapping() { 621 // Incorporate globals. 622 for (Module::global_iterator I = SrcM->global_begin(), 623 E = SrcM->global_end(); I != E; ++I) { 624 GlobalValue *DGV = getLinkedToGlobal(I); 625 if (!DGV) continue; 626 627 if (!DGV->hasAppendingLinkage() || !I->hasAppendingLinkage()) { 628 TypeMap.addTypeMapping(DGV->getType(), I->getType()); 629 continue; 630 } 631 632 // Unify the element type of appending arrays. 633 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType()); 634 ArrayType *SAT = cast<ArrayType>(I->getType()->getElementType()); 635 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType()); 636 } 637 638 // Incorporate functions. 639 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I) { 640 if (GlobalValue *DGV = getLinkedToGlobal(I)) 641 TypeMap.addTypeMapping(DGV->getType(), I->getType()); 642 } 643 644 // Incorporate types by name, scanning all the types in the source module. 645 // At this point, the destination module may have a type "%foo = { i32 }" for 646 // example. When the source module got loaded into the same LLVMContext, if 647 // it had the same type, it would have been renamed to "%foo.42 = { i32 }". 648 TypeFinder SrcStructTypes; 649 SrcStructTypes.run(*SrcM, true); 650 SmallPtrSet<StructType*, 32> SrcStructTypesSet(SrcStructTypes.begin(), 651 SrcStructTypes.end()); 652 653 for (unsigned i = 0, e = SrcStructTypes.size(); i != e; ++i) { 654 StructType *ST = SrcStructTypes[i]; 655 if (!ST->hasName()) continue; 656 657 // Check to see if there is a dot in the name followed by a digit. 658 size_t DotPos = ST->getName().rfind('.'); 659 if (DotPos == 0 || DotPos == StringRef::npos || 660 ST->getName().back() == '.' || 661 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos+1]))) 662 continue; 663 664 // Check to see if the destination module has a struct with the prefix name. 665 if (StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos))) 666 // Don't use it if this actually came from the source module. They're in 667 // the same LLVMContext after all. Also don't use it unless the type is 668 // actually used in the destination module. This can happen in situations 669 // like this: 670 // 671 // Module A Module B 672 // -------- -------- 673 // %Z = type { %A } %B = type { %C.1 } 674 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* } 675 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] } 676 // %C = type { i8* } %B.3 = type { %C.1 } 677 // 678 // When we link Module B with Module A, the '%B' in Module B is 679 // used. However, that would then use '%C.1'. But when we process '%C.1', 680 // we prefer to take the '%C' version. So we are then left with both 681 // '%C.1' and '%C' being used for the same types. This leads to some 682 // variables using one type and some using the other. 683 if (!SrcStructTypesSet.count(DST) && TypeMap.DstStructTypesSet.count(DST)) 684 TypeMap.addTypeMapping(DST, ST); 685 } 686 687 // Don't bother incorporating aliases, they aren't generally typed well. 688 689 // Now that we have discovered all of the type equivalences, get a body for 690 // any 'opaque' types in the dest module that are now resolved. 691 TypeMap.linkDefinedTypeBodies(); 692} 693 694/// linkAppendingVarProto - If there were any appending global variables, link 695/// them together now. Return true on error. 696bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV, 697 GlobalVariable *SrcGV) { 698 699 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage()) 700 return emitError("Linking globals named '" + SrcGV->getName() + 701 "': can only link appending global with another appending global!"); 702 703 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType()); 704 ArrayType *SrcTy = 705 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType())); 706 Type *EltTy = DstTy->getElementType(); 707 708 // Check to see that they two arrays agree on type. 709 if (EltTy != SrcTy->getElementType()) 710 return emitError("Appending variables with different element types!"); 711 if (DstGV->isConstant() != SrcGV->isConstant()) 712 return emitError("Appending variables linked with different const'ness!"); 713 714 if (DstGV->getAlignment() != SrcGV->getAlignment()) 715 return emitError( 716 "Appending variables with different alignment need to be linked!"); 717 718 if (DstGV->getVisibility() != SrcGV->getVisibility()) 719 return emitError( 720 "Appending variables with different visibility need to be linked!"); 721 722 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr()) 723 return emitError( 724 "Appending variables with different unnamed_addr need to be linked!"); 725 726 if (DstGV->getSection() != SrcGV->getSection()) 727 return emitError( 728 "Appending variables with different section name need to be linked!"); 729 730 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements(); 731 ArrayType *NewType = ArrayType::get(EltTy, NewSize); 732 733 // Create the new global variable. 734 GlobalVariable *NG = 735 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(), 736 DstGV->getLinkage(), /*init*/nullptr, /*name*/"", DstGV, 737 DstGV->getThreadLocalMode(), 738 DstGV->getType()->getAddressSpace()); 739 740 // Propagate alignment, visibility and section info. 741 copyGVAttributes(NG, DstGV); 742 743 AppendingVarInfo AVI; 744 AVI.NewGV = NG; 745 AVI.DstInit = DstGV->getInitializer(); 746 AVI.SrcInit = SrcGV->getInitializer(); 747 AppendingVars.push_back(AVI); 748 749 // Replace any uses of the two global variables with uses of the new 750 // global. 751 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType())); 752 753 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType())); 754 DstGV->eraseFromParent(); 755 756 // Track the source variable so we don't try to link it. 757 DoNotLinkFromSource.insert(SrcGV); 758 759 return false; 760} 761 762/// linkGlobalProto - Loop through the global variables in the src module and 763/// merge them into the dest module. 764bool ModuleLinker::linkGlobalProto(GlobalVariable *SGV) { 765 GlobalValue *DGV = getLinkedToGlobal(SGV); 766 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility; 767 bool HasUnnamedAddr = SGV->hasUnnamedAddr(); 768 769 if (DGV) { 770 // Concatenation of appending linkage variables is magic and handled later. 771 if (DGV->hasAppendingLinkage() || SGV->hasAppendingLinkage()) 772 return linkAppendingVarProto(cast<GlobalVariable>(DGV), SGV); 773 774 // Determine whether linkage of these two globals follows the source 775 // module's definition or the destination module's definition. 776 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 777 GlobalValue::VisibilityTypes NV; 778 bool LinkFromSrc = false; 779 if (getLinkageResult(DGV, SGV, NewLinkage, NV, LinkFromSrc)) 780 return true; 781 NewVisibility = NV; 782 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr(); 783 784 // If we're not linking from the source, then keep the definition that we 785 // have. 786 if (!LinkFromSrc) { 787 // Special case for const propagation. 788 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) 789 if (DGVar->isDeclaration() && SGV->isConstant() && !DGVar->isConstant()) 790 DGVar->setConstant(true); 791 792 // Set calculated linkage, visibility and unnamed_addr. 793 DGV->setLinkage(NewLinkage); 794 DGV->setVisibility(*NewVisibility); 795 DGV->setUnnamedAddr(HasUnnamedAddr); 796 797 // Make sure to remember this mapping. 798 ValueMap[SGV] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGV->getType())); 799 800 // Track the source global so that we don't attempt to copy it over when 801 // processing global initializers. 802 DoNotLinkFromSource.insert(SGV); 803 804 return false; 805 } 806 } 807 808 // No linking to be performed or linking from the source: simply create an 809 // identical version of the symbol over in the dest module... the 810 // initializer will be filled in later by LinkGlobalInits. 811 GlobalVariable *NewDGV = 812 new GlobalVariable(*DstM, TypeMap.get(SGV->getType()->getElementType()), 813 SGV->isConstant(), SGV->getLinkage(), /*init*/nullptr, 814 SGV->getName(), /*insertbefore*/nullptr, 815 SGV->getThreadLocalMode(), 816 SGV->getType()->getAddressSpace()); 817 // Propagate alignment, visibility and section info. 818 copyGVAttributes(NewDGV, SGV); 819 if (NewVisibility) 820 NewDGV->setVisibility(*NewVisibility); 821 NewDGV->setUnnamedAddr(HasUnnamedAddr); 822 823 if (DGV) { 824 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV, DGV->getType())); 825 DGV->eraseFromParent(); 826 } 827 828 // Make sure to remember this mapping. 829 ValueMap[SGV] = NewDGV; 830 return false; 831} 832 833/// linkFunctionProto - Link the function in the source module into the 834/// destination module if needed, setting up mapping information. 835bool ModuleLinker::linkFunctionProto(Function *SF) { 836 GlobalValue *DGV = getLinkedToGlobal(SF); 837 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility; 838 bool HasUnnamedAddr = SF->hasUnnamedAddr(); 839 840 if (DGV) { 841 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 842 bool LinkFromSrc = false; 843 GlobalValue::VisibilityTypes NV; 844 if (getLinkageResult(DGV, SF, NewLinkage, NV, LinkFromSrc)) 845 return true; 846 NewVisibility = NV; 847 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr(); 848 849 if (!LinkFromSrc) { 850 // Set calculated linkage 851 DGV->setLinkage(NewLinkage); 852 DGV->setVisibility(*NewVisibility); 853 DGV->setUnnamedAddr(HasUnnamedAddr); 854 855 // Make sure to remember this mapping. 856 ValueMap[SF] = ConstantExpr::getBitCast(DGV, TypeMap.get(SF->getType())); 857 858 // Track the function from the source module so we don't attempt to remap 859 // it. 860 DoNotLinkFromSource.insert(SF); 861 862 return false; 863 } 864 } 865 866 // If the function is to be lazily linked, don't create it just yet. 867 // The ValueMaterializerTy will deal with creating it if it's used. 868 if (!DGV && (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() || 869 SF->hasAvailableExternallyLinkage())) { 870 DoNotLinkFromSource.insert(SF); 871 return false; 872 } 873 874 // If there is no linkage to be performed or we are linking from the source, 875 // bring SF over. 876 Function *NewDF = Function::Create(TypeMap.get(SF->getFunctionType()), 877 SF->getLinkage(), SF->getName(), DstM); 878 copyGVAttributes(NewDF, SF); 879 if (NewVisibility) 880 NewDF->setVisibility(*NewVisibility); 881 NewDF->setUnnamedAddr(HasUnnamedAddr); 882 883 if (DGV) { 884 // Any uses of DF need to change to NewDF, with cast. 885 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, DGV->getType())); 886 DGV->eraseFromParent(); 887 } 888 889 ValueMap[SF] = NewDF; 890 return false; 891} 892 893/// LinkAliasProto - Set up prototypes for any aliases that come over from the 894/// source module. 895bool ModuleLinker::linkAliasProto(GlobalAlias *SGA) { 896 GlobalValue *DGV = getLinkedToGlobal(SGA); 897 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility; 898 899 if (DGV) { 900 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 901 GlobalValue::VisibilityTypes NV; 902 bool LinkFromSrc = false; 903 if (getLinkageResult(DGV, SGA, NewLinkage, NV, LinkFromSrc)) 904 return true; 905 NewVisibility = NV; 906 907 if (!LinkFromSrc) { 908 // Set calculated linkage. 909 DGV->setLinkage(NewLinkage); 910 DGV->setVisibility(*NewVisibility); 911 912 // Make sure to remember this mapping. 913 ValueMap[SGA] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGA->getType())); 914 915 // Track the alias from the source module so we don't attempt to remap it. 916 DoNotLinkFromSource.insert(SGA); 917 918 return false; 919 } 920 } 921 922 // If there is no linkage to be performed or we're linking from the source, 923 // bring over SGA. 924 auto *PTy = cast<PointerType>(TypeMap.get(SGA->getType())); 925 auto *NewDA = 926 GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(), 927 SGA->getLinkage(), SGA->getName(), DstM); 928 copyGVAttributes(NewDA, SGA); 929 if (NewVisibility) 930 NewDA->setVisibility(*NewVisibility); 931 932 if (DGV) 933 ReplaceWithAlias.push_back(std::make_pair(DGV, NewDA)); 934 935 ValueMap[SGA] = NewDA; 936 return false; 937} 938 939static void getArrayElements(Constant *C, SmallVectorImpl<Constant*> &Dest) { 940 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements(); 941 942 for (unsigned i = 0; i != NumElements; ++i) 943 Dest.push_back(C->getAggregateElement(i)); 944} 945 946void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) { 947 // Merge the initializer. 948 SmallVector<Constant*, 16> Elements; 949 getArrayElements(AVI.DstInit, Elements); 950 951 Constant *SrcInit = MapValue(AVI.SrcInit, ValueMap, RF_None, &TypeMap, &ValMaterializer); 952 getArrayElements(SrcInit, Elements); 953 954 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType()); 955 AVI.NewGV->setInitializer(ConstantArray::get(NewType, Elements)); 956} 957 958/// linkGlobalInits - Update the initializers in the Dest module now that all 959/// globals that may be referenced are in Dest. 960void ModuleLinker::linkGlobalInits() { 961 // Loop over all of the globals in the src module, mapping them over as we go 962 for (Module::const_global_iterator I = SrcM->global_begin(), 963 E = SrcM->global_end(); I != E; ++I) { 964 965 // Only process initialized GV's or ones not already in dest. 966 if (!I->hasInitializer() || DoNotLinkFromSource.count(I)) continue; 967 968 // Grab destination global variable. 969 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[I]); 970 // Figure out what the initializer looks like in the dest module. 971 DGV->setInitializer(MapValue(I->getInitializer(), ValueMap, 972 RF_None, &TypeMap, &ValMaterializer)); 973 } 974} 975 976/// linkFunctionBody - Copy the source function over into the dest function and 977/// fix up references to values. At this point we know that Dest is an external 978/// function, and that Src is not. 979void ModuleLinker::linkFunctionBody(Function *Dst, Function *Src) { 980 assert(Src && Dst && Dst->isDeclaration() && !Src->isDeclaration()); 981 982 // Go through and convert function arguments over, remembering the mapping. 983 Function::arg_iterator DI = Dst->arg_begin(); 984 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 985 I != E; ++I, ++DI) { 986 DI->setName(I->getName()); // Copy the name over. 987 988 // Add a mapping to our mapping. 989 ValueMap[I] = DI; 990 } 991 992 if (Mode == Linker::DestroySource) { 993 // Splice the body of the source function into the dest function. 994 Dst->getBasicBlockList().splice(Dst->end(), Src->getBasicBlockList()); 995 996 // At this point, all of the instructions and values of the function are now 997 // copied over. The only problem is that they are still referencing values in 998 // the Source function as operands. Loop through all of the operands of the 999 // functions and patch them up to point to the local versions. 1000 for (Function::iterator BB = Dst->begin(), BE = Dst->end(); BB != BE; ++BB) 1001 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) 1002 RemapInstruction(I, ValueMap, RF_IgnoreMissingEntries, 1003 &TypeMap, &ValMaterializer); 1004 1005 } else { 1006 // Clone the body of the function into the dest function. 1007 SmallVector<ReturnInst*, 8> Returns; // Ignore returns. 1008 CloneFunctionInto(Dst, Src, ValueMap, false, Returns, "", nullptr, 1009 &TypeMap, &ValMaterializer); 1010 } 1011 1012 // There is no need to map the arguments anymore. 1013 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 1014 I != E; ++I) 1015 ValueMap.erase(I); 1016 1017} 1018 1019static GlobalObject &getGlobalObjectInExpr(Constant &C) { 1020 auto *GO = dyn_cast<GlobalObject>(&C); 1021 if (GO) 1022 return *GO; 1023 auto *GA = dyn_cast<GlobalAlias>(&C); 1024 if (GA) 1025 return *GA->getAliasee(); 1026 auto &CE = cast<ConstantExpr>(C); 1027 assert(CE.getOpcode() == Instruction::BitCast || 1028 CE.getOpcode() == Instruction::AddrSpaceCast); 1029 return getGlobalObjectInExpr(*CE.getOperand(0)); 1030} 1031 1032/// linkAliasBodies - Insert all of the aliases in Src into the Dest module. 1033void ModuleLinker::linkAliasBodies() { 1034 for (Module::alias_iterator I = SrcM->alias_begin(), E = SrcM->alias_end(); 1035 I != E; ++I) { 1036 if (DoNotLinkFromSource.count(I)) 1037 continue; 1038 if (Constant *Aliasee = I->getAliasee()) { 1039 GlobalAlias *DA = cast<GlobalAlias>(ValueMap[I]); 1040 Constant *Val = 1041 MapValue(Aliasee, ValueMap, RF_None, &TypeMap, &ValMaterializer); 1042 DA->setAliasee(&getGlobalObjectInExpr(*Val)); 1043 } 1044 } 1045 1046 // Any uses of DGV need to change to NewDA, with cast. 1047 for (auto &Pair : ReplaceWithAlias) { 1048 GlobalValue *DGV = Pair.first; 1049 GlobalAlias *NewDA = Pair.second; 1050 1051 for (auto *User : DGV->users()) { 1052 if (auto *GA = dyn_cast<GlobalAlias>(User)) { 1053 if (GA == NewDA) 1054 report_fatal_error("Linking these modules creates an alias cycle."); 1055 } 1056 } 1057 1058 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDA, DGV->getType())); 1059 DGV->eraseFromParent(); 1060 } 1061} 1062 1063/// linkNamedMDNodes - Insert all of the named MDNodes in Src into the Dest 1064/// module. 1065void ModuleLinker::linkNamedMDNodes() { 1066 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata(); 1067 for (Module::const_named_metadata_iterator I = SrcM->named_metadata_begin(), 1068 E = SrcM->named_metadata_end(); I != E; ++I) { 1069 // Don't link module flags here. Do them separately. 1070 if (&*I == SrcModFlags) continue; 1071 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(I->getName()); 1072 // Add Src elements into Dest node. 1073 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) 1074 DestNMD->addOperand(MapValue(I->getOperand(i), ValueMap, 1075 RF_None, &TypeMap, &ValMaterializer)); 1076 } 1077} 1078 1079/// linkModuleFlagsMetadata - Merge the linker flags in Src into the Dest 1080/// module. 1081bool ModuleLinker::linkModuleFlagsMetadata() { 1082 // If the source module has no module flags, we are done. 1083 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata(); 1084 if (!SrcModFlags) return false; 1085 1086 // If the destination module doesn't have module flags yet, then just copy 1087 // over the source module's flags. 1088 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata(); 1089 if (DstModFlags->getNumOperands() == 0) { 1090 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) 1091 DstModFlags->addOperand(SrcModFlags->getOperand(I)); 1092 1093 return false; 1094 } 1095 1096 // First build a map of the existing module flags and requirements. 1097 DenseMap<MDString*, MDNode*> Flags; 1098 SmallSetVector<MDNode*, 16> Requirements; 1099 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) { 1100 MDNode *Op = DstModFlags->getOperand(I); 1101 ConstantInt *Behavior = cast<ConstantInt>(Op->getOperand(0)); 1102 MDString *ID = cast<MDString>(Op->getOperand(1)); 1103 1104 if (Behavior->getZExtValue() == Module::Require) { 1105 Requirements.insert(cast<MDNode>(Op->getOperand(2))); 1106 } else { 1107 Flags[ID] = Op; 1108 } 1109 } 1110 1111 // Merge in the flags from the source module, and also collect its set of 1112 // requirements. 1113 bool HasErr = false; 1114 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) { 1115 MDNode *SrcOp = SrcModFlags->getOperand(I); 1116 ConstantInt *SrcBehavior = cast<ConstantInt>(SrcOp->getOperand(0)); 1117 MDString *ID = cast<MDString>(SrcOp->getOperand(1)); 1118 MDNode *DstOp = Flags.lookup(ID); 1119 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue(); 1120 1121 // If this is a requirement, add it and continue. 1122 if (SrcBehaviorValue == Module::Require) { 1123 // If the destination module does not already have this requirement, add 1124 // it. 1125 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) { 1126 DstModFlags->addOperand(SrcOp); 1127 } 1128 continue; 1129 } 1130 1131 // If there is no existing flag with this ID, just add it. 1132 if (!DstOp) { 1133 Flags[ID] = SrcOp; 1134 DstModFlags->addOperand(SrcOp); 1135 continue; 1136 } 1137 1138 // Otherwise, perform a merge. 1139 ConstantInt *DstBehavior = cast<ConstantInt>(DstOp->getOperand(0)); 1140 unsigned DstBehaviorValue = DstBehavior->getZExtValue(); 1141 1142 // If either flag has override behavior, handle it first. 1143 if (DstBehaviorValue == Module::Override) { 1144 // Diagnose inconsistent flags which both have override behavior. 1145 if (SrcBehaviorValue == Module::Override && 1146 SrcOp->getOperand(2) != DstOp->getOperand(2)) { 1147 HasErr |= emitError("linking module flags '" + ID->getString() + 1148 "': IDs have conflicting override values"); 1149 } 1150 continue; 1151 } else if (SrcBehaviorValue == Module::Override) { 1152 // Update the destination flag to that of the source. 1153 DstOp->replaceOperandWith(0, SrcBehavior); 1154 DstOp->replaceOperandWith(2, SrcOp->getOperand(2)); 1155 continue; 1156 } 1157 1158 // Diagnose inconsistent merge behavior types. 1159 if (SrcBehaviorValue != DstBehaviorValue) { 1160 HasErr |= emitError("linking module flags '" + ID->getString() + 1161 "': IDs have conflicting behaviors"); 1162 continue; 1163 } 1164 1165 // Perform the merge for standard behavior types. 1166 switch (SrcBehaviorValue) { 1167 case Module::Require: 1168 case Module::Override: assert(0 && "not possible"); break; 1169 case Module::Error: { 1170 // Emit an error if the values differ. 1171 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) { 1172 HasErr |= emitError("linking module flags '" + ID->getString() + 1173 "': IDs have conflicting values"); 1174 } 1175 continue; 1176 } 1177 case Module::Warning: { 1178 // Emit a warning if the values differ. 1179 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) { 1180 if (!SuppressWarnings) { 1181 errs() << "WARNING: linking module flags '" << ID->getString() 1182 << "': IDs have conflicting values"; 1183 } 1184 } 1185 continue; 1186 } 1187 case Module::Append: { 1188 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2)); 1189 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2)); 1190 unsigned NumOps = DstValue->getNumOperands() + SrcValue->getNumOperands(); 1191 Value **VP, **Values = VP = new Value*[NumOps]; 1192 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i, ++VP) 1193 *VP = DstValue->getOperand(i); 1194 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i, ++VP) 1195 *VP = SrcValue->getOperand(i); 1196 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(), 1197 ArrayRef<Value*>(Values, 1198 NumOps))); 1199 delete[] Values; 1200 break; 1201 } 1202 case Module::AppendUnique: { 1203 SmallSetVector<Value*, 16> Elts; 1204 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2)); 1205 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2)); 1206 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i) 1207 Elts.insert(DstValue->getOperand(i)); 1208 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i) 1209 Elts.insert(SrcValue->getOperand(i)); 1210 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(), 1211 ArrayRef<Value*>(Elts.begin(), 1212 Elts.end()))); 1213 break; 1214 } 1215 } 1216 } 1217 1218 // Check all of the requirements. 1219 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) { 1220 MDNode *Requirement = Requirements[I]; 1221 MDString *Flag = cast<MDString>(Requirement->getOperand(0)); 1222 Value *ReqValue = Requirement->getOperand(1); 1223 1224 MDNode *Op = Flags[Flag]; 1225 if (!Op || Op->getOperand(2) != ReqValue) { 1226 HasErr |= emitError("linking module flags '" + Flag->getString() + 1227 "': does not have the required value"); 1228 continue; 1229 } 1230 } 1231 1232 return HasErr; 1233} 1234 1235bool ModuleLinker::run() { 1236 assert(DstM && "Null destination module"); 1237 assert(SrcM && "Null source module"); 1238 1239 // Inherit the target data from the source module if the destination module 1240 // doesn't have one already. 1241 if (!DstM->getDataLayout() && SrcM->getDataLayout()) 1242 DstM->setDataLayout(SrcM->getDataLayout()); 1243 1244 // Copy the target triple from the source to dest if the dest's is empty. 1245 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty()) 1246 DstM->setTargetTriple(SrcM->getTargetTriple()); 1247 1248 if (SrcM->getDataLayout() && DstM->getDataLayout() && 1249 *SrcM->getDataLayout() != *DstM->getDataLayout()) { 1250 if (!SuppressWarnings) { 1251 errs() << "WARNING: Linking two modules of different data layouts: '" 1252 << SrcM->getModuleIdentifier() << "' is '" 1253 << SrcM->getDataLayoutStr() << "' whereas '" 1254 << DstM->getModuleIdentifier() << "' is '" 1255 << DstM->getDataLayoutStr() << "'\n"; 1256 } 1257 } 1258 if (!SrcM->getTargetTriple().empty() && 1259 DstM->getTargetTriple() != SrcM->getTargetTriple()) { 1260 if (!SuppressWarnings) { 1261 errs() << "WARNING: Linking two modules of different target triples: " 1262 << SrcM->getModuleIdentifier() << "' is '" 1263 << SrcM->getTargetTriple() << "' whereas '" 1264 << DstM->getModuleIdentifier() << "' is '" 1265 << DstM->getTargetTriple() << "'\n"; 1266 } 1267 } 1268 1269 // Append the module inline asm string. 1270 if (!SrcM->getModuleInlineAsm().empty()) { 1271 if (DstM->getModuleInlineAsm().empty()) 1272 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm()); 1273 else 1274 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+ 1275 SrcM->getModuleInlineAsm()); 1276 } 1277 1278 // Loop over all of the linked values to compute type mappings. 1279 computeTypeMapping(); 1280 1281 // Insert all of the globals in src into the DstM module... without linking 1282 // initializers (which could refer to functions not yet mapped over). 1283 for (Module::global_iterator I = SrcM->global_begin(), 1284 E = SrcM->global_end(); I != E; ++I) 1285 if (linkGlobalProto(I)) 1286 return true; 1287 1288 // Link the functions together between the two modules, without doing function 1289 // bodies... this just adds external function prototypes to the DstM 1290 // function... We do this so that when we begin processing function bodies, 1291 // all of the global values that may be referenced are available in our 1292 // ValueMap. 1293 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I) 1294 if (linkFunctionProto(I)) 1295 return true; 1296 1297 // If there were any aliases, link them now. 1298 for (Module::alias_iterator I = SrcM->alias_begin(), 1299 E = SrcM->alias_end(); I != E; ++I) 1300 if (linkAliasProto(I)) 1301 return true; 1302 1303 for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i) 1304 linkAppendingVarInit(AppendingVars[i]); 1305 1306 // Link in the function bodies that are defined in the source module into 1307 // DstM. 1308 for (Module::iterator SF = SrcM->begin(), E = SrcM->end(); SF != E; ++SF) { 1309 // Skip if not linking from source. 1310 if (DoNotLinkFromSource.count(SF)) continue; 1311 1312 Function *DF = cast<Function>(ValueMap[SF]); 1313 if (SF->hasPrefixData()) { 1314 // Link in the prefix data. 1315 DF->setPrefixData(MapValue( 1316 SF->getPrefixData(), ValueMap, RF_None, &TypeMap, &ValMaterializer)); 1317 } 1318 1319 // Skip if no body (function is external) or materialize. 1320 if (SF->isDeclaration()) { 1321 if (!SF->isMaterializable()) 1322 continue; 1323 if (SF->Materialize(&ErrorMsg)) 1324 return true; 1325 } 1326 1327 linkFunctionBody(DF, SF); 1328 SF->Dematerialize(); 1329 } 1330 1331 // Resolve all uses of aliases with aliasees. 1332 linkAliasBodies(); 1333 1334 // Remap all of the named MDNodes in Src into the DstM module. We do this 1335 // after linking GlobalValues so that MDNodes that reference GlobalValues 1336 // are properly remapped. 1337 linkNamedMDNodes(); 1338 1339 // Merge the module flags into the DstM module. 1340 if (linkModuleFlagsMetadata()) 1341 return true; 1342 1343 // Update the initializers in the DstM module now that all globals that may 1344 // be referenced are in DstM. 1345 linkGlobalInits(); 1346 1347 // Process vector of lazily linked in functions. 1348 bool LinkedInAnyFunctions; 1349 do { 1350 LinkedInAnyFunctions = false; 1351 1352 for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(), 1353 E = LazilyLinkFunctions.end(); I != E; ++I) { 1354 Function *SF = *I; 1355 if (!SF) 1356 continue; 1357 1358 Function *DF = cast<Function>(ValueMap[SF]); 1359 if (SF->hasPrefixData()) { 1360 // Link in the prefix data. 1361 DF->setPrefixData(MapValue(SF->getPrefixData(), 1362 ValueMap, 1363 RF_None, 1364 &TypeMap, 1365 &ValMaterializer)); 1366 } 1367 1368 // Materialize if necessary. 1369 if (SF->isDeclaration()) { 1370 if (!SF->isMaterializable()) 1371 continue; 1372 if (SF->Materialize(&ErrorMsg)) 1373 return true; 1374 } 1375 1376 // Erase from vector *before* the function body is linked - linkFunctionBody could 1377 // invalidate I. 1378 LazilyLinkFunctions.erase(I); 1379 1380 // Link in function body. 1381 linkFunctionBody(DF, SF); 1382 SF->Dematerialize(); 1383 1384 // Set flag to indicate we may have more functions to lazily link in 1385 // since we linked in a function. 1386 LinkedInAnyFunctions = true; 1387 break; 1388 } 1389 } while (LinkedInAnyFunctions); 1390 1391 // Now that all of the types from the source are used, resolve any structs 1392 // copied over to the dest that didn't exist there. 1393 TypeMap.linkDefinedTypeBodies(); 1394 1395 return false; 1396} 1397 1398Linker::Linker(Module *M, bool SuppressWarnings) 1399 : Composite(M), SuppressWarnings(SuppressWarnings) { 1400 TypeFinder StructTypes; 1401 StructTypes.run(*M, true); 1402 IdentifiedStructTypes.insert(StructTypes.begin(), StructTypes.end()); 1403} 1404 1405Linker::~Linker() { 1406} 1407 1408void Linker::deleteModule() { 1409 delete Composite; 1410 Composite = nullptr; 1411} 1412 1413bool Linker::linkInModule(Module *Src, unsigned Mode, std::string *ErrorMsg) { 1414 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src, Mode, 1415 SuppressWarnings); 1416 if (TheLinker.run()) { 1417 if (ErrorMsg) 1418 *ErrorMsg = TheLinker.ErrorMsg; 1419 return true; 1420 } 1421 return false; 1422} 1423 1424//===----------------------------------------------------------------------===// 1425// LinkModules entrypoint. 1426//===----------------------------------------------------------------------===// 1427 1428/// LinkModules - This function links two modules together, with the resulting 1429/// Dest module modified to be the composite of the two input modules. If an 1430/// error occurs, true is returned and ErrorMsg (if not null) is set to indicate 1431/// the problem. Upon failure, the Dest module could be in a modified state, 1432/// and shouldn't be relied on to be consistent. 1433bool Linker::LinkModules(Module *Dest, Module *Src, unsigned Mode, 1434 std::string *ErrorMsg) { 1435 Linker L(Dest); 1436 return L.linkInModule(Src, Mode, ErrorMsg); 1437} 1438 1439//===----------------------------------------------------------------------===// 1440// C API. 1441//===----------------------------------------------------------------------===// 1442 1443LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src, 1444 LLVMLinkerMode Mode, char **OutMessages) { 1445 std::string Messages; 1446 LLVMBool Result = Linker::LinkModules(unwrap(Dest), unwrap(Src), 1447 Mode, OutMessages? &Messages : nullptr); 1448 if (OutMessages) 1449 *OutMessages = strdup(Messages.c_str()); 1450 return Result; 1451} 1452