LinkModules.cpp revision 1a31f3b90c012b067f8509546e1e037051e6482d
1//===- lib/Linker/LinkModules.cpp - Module Linker Implementation ----------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file implements the LLVM module linker. 11// 12//===----------------------------------------------------------------------===// 13 14#include "llvm/Linker.h" 15#include "llvm/Constants.h" 16#include "llvm/DerivedTypes.h" 17#include "llvm/Instructions.h" 18#include "llvm/Module.h" 19#include "llvm/ADT/SmallPtrSet.h" 20#include "llvm/Support/raw_ostream.h" 21#include "llvm/Support/Path.h" 22#include "llvm/Transforms/Utils/Cloning.h" 23#include "llvm/Transforms/Utils/ValueMapper.h" 24using namespace llvm; 25 26//===----------------------------------------------------------------------===// 27// TypeMap implementation. 28//===----------------------------------------------------------------------===// 29 30namespace { 31class TypeMapTy : public ValueMapTypeRemapper { 32 /// MappedTypes - This is a mapping from a source type to a destination type 33 /// to use. 34 DenseMap<Type*, Type*> MappedTypes; 35 36 /// SpeculativeTypes - When checking to see if two subgraphs are isomorphic, 37 /// we speculatively add types to MappedTypes, but keep track of them here in 38 /// case we need to roll back. 39 SmallVector<Type*, 16> SpeculativeTypes; 40 41 /// SrcDefinitionsToResolve - This is a list of non-opaque structs in the 42 /// source module that are mapped to an opaque struct in the destination 43 /// module. 44 SmallVector<StructType*, 16> SrcDefinitionsToResolve; 45 46 /// DstResolvedOpaqueTypes - This is the set of opaque types in the 47 /// destination modules who are getting a body from the source module. 48 SmallPtrSet<StructType*, 16> DstResolvedOpaqueTypes; 49public: 50 51 /// addTypeMapping - Indicate that the specified type in the destination 52 /// module is conceptually equivalent to the specified type in the source 53 /// module. 54 void addTypeMapping(Type *DstTy, Type *SrcTy); 55 56 /// linkDefinedTypeBodies - Produce a body for an opaque type in the dest 57 /// module from a type definition in the source module. 58 void linkDefinedTypeBodies(); 59 60 /// get - Return the mapped type to use for the specified input type from the 61 /// source module. 62 Type *get(Type *SrcTy); 63 64 FunctionType *get(FunctionType *T) {return cast<FunctionType>(get((Type*)T));} 65 66private: 67 Type *getImpl(Type *T); 68 /// remapType - Implement the ValueMapTypeRemapper interface. 69 Type *remapType(Type *SrcTy) { 70 return get(SrcTy); 71 } 72 73 bool areTypesIsomorphic(Type *DstTy, Type *SrcTy); 74}; 75} 76 77void TypeMapTy::addTypeMapping(Type *DstTy, Type *SrcTy) { 78 Type *&Entry = MappedTypes[SrcTy]; 79 if (Entry) return; 80 81 if (DstTy == SrcTy) { 82 Entry = DstTy; 83 return; 84 } 85 86 // Check to see if these types are recursively isomorphic and establish a 87 // mapping between them if so. 88 if (!areTypesIsomorphic(DstTy, SrcTy)) { 89 // Oops, they aren't isomorphic. Just discard this request by rolling out 90 // any speculative mappings we've established. 91 for (unsigned i = 0, e = SpeculativeTypes.size(); i != e; ++i) 92 MappedTypes.erase(SpeculativeTypes[i]); 93 } 94 SpeculativeTypes.clear(); 95} 96 97/// areTypesIsomorphic - Recursively walk this pair of types, returning true 98/// if they are isomorphic, false if they are not. 99bool TypeMapTy::areTypesIsomorphic(Type *DstTy, Type *SrcTy) { 100 // Two types with differing kinds are clearly not isomorphic. 101 if (DstTy->getTypeID() != SrcTy->getTypeID()) return false; 102 103 // If we have an entry in the MappedTypes table, then we have our answer. 104 Type *&Entry = MappedTypes[SrcTy]; 105 if (Entry) 106 return Entry == DstTy; 107 108 // Two identical types are clearly isomorphic. Remember this 109 // non-speculatively. 110 if (DstTy == SrcTy) { 111 Entry = DstTy; 112 return true; 113 } 114 115 // Okay, we have two types with identical kinds that we haven't seen before. 116 117 // If this is an opaque struct type, special case it. 118 if (StructType *SSTy = dyn_cast<StructType>(SrcTy)) { 119 // Mapping an opaque type to any struct, just keep the dest struct. 120 if (SSTy->isOpaque()) { 121 Entry = DstTy; 122 SpeculativeTypes.push_back(SrcTy); 123 return true; 124 } 125 126 // Mapping a non-opaque source type to an opaque dest. If this is the first 127 // type that we're mapping onto this destination type then we succeed. Keep 128 // the dest, but fill it in later. This doesn't need to be speculative. If 129 // this is the second (different) type that we're trying to map onto the 130 // same opaque type then we fail. 131 if (cast<StructType>(DstTy)->isOpaque()) { 132 // We can only map one source type onto the opaque destination type. 133 if (!DstResolvedOpaqueTypes.insert(cast<StructType>(DstTy))) 134 return false; 135 SrcDefinitionsToResolve.push_back(SSTy); 136 Entry = DstTy; 137 return true; 138 } 139 } 140 141 // If the number of subtypes disagree between the two types, then we fail. 142 if (SrcTy->getNumContainedTypes() != DstTy->getNumContainedTypes()) 143 return false; 144 145 // Fail if any of the extra properties (e.g. array size) of the type disagree. 146 if (isa<IntegerType>(DstTy)) 147 return false; // bitwidth disagrees. 148 if (PointerType *PT = dyn_cast<PointerType>(DstTy)) { 149 if (PT->getAddressSpace() != cast<PointerType>(SrcTy)->getAddressSpace()) 150 return false; 151 152 } else if (FunctionType *FT = dyn_cast<FunctionType>(DstTy)) { 153 if (FT->isVarArg() != cast<FunctionType>(SrcTy)->isVarArg()) 154 return false; 155 } else if (StructType *DSTy = dyn_cast<StructType>(DstTy)) { 156 StructType *SSTy = cast<StructType>(SrcTy); 157 if (DSTy->isLiteral() != SSTy->isLiteral() || 158 DSTy->isPacked() != SSTy->isPacked()) 159 return false; 160 } else if (ArrayType *DATy = dyn_cast<ArrayType>(DstTy)) { 161 if (DATy->getNumElements() != cast<ArrayType>(SrcTy)->getNumElements()) 162 return false; 163 } else if (VectorType *DVTy = dyn_cast<VectorType>(DstTy)) { 164 if (DVTy->getNumElements() != cast<ArrayType>(SrcTy)->getNumElements()) 165 return false; 166 } 167 168 // Otherwise, we speculate that these two types will line up and recursively 169 // check the subelements. 170 Entry = DstTy; 171 SpeculativeTypes.push_back(SrcTy); 172 173 for (unsigned i = 0, e = SrcTy->getNumContainedTypes(); i != e; ++i) 174 if (!areTypesIsomorphic(DstTy->getContainedType(i), 175 SrcTy->getContainedType(i))) 176 return false; 177 178 // If everything seems to have lined up, then everything is great. 179 return true; 180} 181 182/// linkDefinedTypeBodies - Produce a body for an opaque type in the dest 183/// module from a type definition in the source module. 184void TypeMapTy::linkDefinedTypeBodies() { 185 SmallVector<Type*, 16> Elements; 186 SmallString<16> TmpName; 187 188 // Note that processing entries in this loop (calling 'get') can add new 189 // entries to the SrcDefinitionsToResolve vector. 190 while (!SrcDefinitionsToResolve.empty()) { 191 StructType *SrcSTy = SrcDefinitionsToResolve.pop_back_val(); 192 StructType *DstSTy = cast<StructType>(MappedTypes[SrcSTy]); 193 194 // TypeMap is a many-to-one mapping, if there were multiple types that 195 // provide a body for DstSTy then previous iterations of this loop may have 196 // already handled it. Just ignore this case. 197 if (!DstSTy->isOpaque()) continue; 198 assert(!SrcSTy->isOpaque() && "Not resolving a definition?"); 199 200 // Map the body of the source type over to a new body for the dest type. 201 Elements.resize(SrcSTy->getNumElements()); 202 for (unsigned i = 0, e = Elements.size(); i != e; ++i) 203 Elements[i] = getImpl(SrcSTy->getElementType(i)); 204 205 DstSTy->setBody(Elements, SrcSTy->isPacked()); 206 207 // If DstSTy has no name or has a longer name than STy, then viciously steal 208 // STy's name. 209 if (!SrcSTy->hasName()) continue; 210 StringRef SrcName = SrcSTy->getName(); 211 212 if (!DstSTy->hasName() || DstSTy->getName().size() > SrcName.size()) { 213 TmpName.insert(TmpName.end(), SrcName.begin(), SrcName.end()); 214 SrcSTy->setName(""); 215 DstSTy->setName(TmpName.str()); 216 TmpName.clear(); 217 } 218 } 219 220 DstResolvedOpaqueTypes.clear(); 221} 222 223 224/// get - Return the mapped type to use for the specified input type from the 225/// source module. 226Type *TypeMapTy::get(Type *Ty) { 227 Type *Result = getImpl(Ty); 228 229 // If this caused a reference to any struct type, resolve it before returning. 230 if (!SrcDefinitionsToResolve.empty()) 231 linkDefinedTypeBodies(); 232 return Result; 233} 234 235/// getImpl - This is the recursive version of get(). 236Type *TypeMapTy::getImpl(Type *Ty) { 237 // If we already have an entry for this type, return it. 238 Type **Entry = &MappedTypes[Ty]; 239 if (*Entry) return *Entry; 240 241 // If this is not a named struct type, then just map all of the elements and 242 // then rebuild the type from inside out. 243 if (!isa<StructType>(Ty) || cast<StructType>(Ty)->isLiteral()) { 244 // If there are no element types to map, then the type is itself. This is 245 // true for the anonymous {} struct, things like 'float', integers, etc. 246 if (Ty->getNumContainedTypes() == 0) 247 return *Entry = Ty; 248 249 // Remap all of the elements, keeping track of whether any of them change. 250 bool AnyChange = false; 251 SmallVector<Type*, 4> ElementTypes; 252 ElementTypes.resize(Ty->getNumContainedTypes()); 253 for (unsigned i = 0, e = Ty->getNumContainedTypes(); i != e; ++i) { 254 ElementTypes[i] = getImpl(Ty->getContainedType(i)); 255 AnyChange |= ElementTypes[i] != Ty->getContainedType(i); 256 } 257 258 // If we found our type while recursively processing stuff, just use it. 259 Entry = &MappedTypes[Ty]; 260 if (*Entry) return *Entry; 261 262 // If all of the element types mapped directly over, then the type is usable 263 // as-is. 264 if (!AnyChange) 265 return *Entry = Ty; 266 267 // Otherwise, rebuild a modified type. 268 switch (Ty->getTypeID()) { 269 default: assert(0 && "unknown derived type to remap"); 270 case Type::ArrayTyID: 271 return *Entry = ArrayType::get(ElementTypes[0], 272 cast<ArrayType>(Ty)->getNumElements()); 273 case Type::VectorTyID: 274 return *Entry = VectorType::get(ElementTypes[0], 275 cast<VectorType>(Ty)->getNumElements()); 276 case Type::PointerTyID: 277 return *Entry = PointerType::get(ElementTypes[0], 278 cast<PointerType>(Ty)->getAddressSpace()); 279 case Type::FunctionTyID: 280 return *Entry = FunctionType::get(ElementTypes[0], 281 makeArrayRef(ElementTypes).slice(1), 282 cast<FunctionType>(Ty)->isVarArg()); 283 case Type::StructTyID: 284 // Note that this is only reached for anonymous structs. 285 return *Entry = StructType::get(Ty->getContext(), ElementTypes, 286 cast<StructType>(Ty)->isPacked()); 287 } 288 } 289 290 // Otherwise, this is an unmapped named struct. If the struct can be directly 291 // mapped over, just use it as-is. This happens in a case when the linked-in 292 // module has something like: 293 // %T = type {%T*, i32} 294 // @GV = global %T* null 295 // where T does not exist at all in the destination module. 296 // 297 // The other case we watch for is when the type is not in the destination 298 // module, but that it has to be rebuilt because it refers to something that 299 // is already mapped. For example, if the destination module has: 300 // %A = type { i32 } 301 // and the source module has something like 302 // %A' = type { i32 } 303 // %B = type { %A'* } 304 // @GV = global %B* null 305 // then we want to create a new type: "%B = type { %A*}" and have it take the 306 // pristine "%B" name from the source module. 307 // 308 // To determine which case this is, we have to recursively walk the type graph 309 // speculating that we'll be able to reuse it unmodified. Only if this is 310 // safe would we map the entire thing over. Because this is an optimization, 311 // and is not required for the prettiness of the linked module, we just skip 312 // it and always rebuild a type here. 313 StructType *STy = cast<StructType>(Ty); 314 315 // If the type is opaque, we can just use it directly. 316 if (STy->isOpaque()) 317 return *Entry = STy; 318 319 // Otherwise we create a new type and resolve its body later. This will be 320 // resolved by the top level of get(). 321 SrcDefinitionsToResolve.push_back(STy); 322 StructType *DTy = StructType::create(STy->getContext()); 323 DstResolvedOpaqueTypes.insert(DTy); 324 return *Entry = DTy; 325} 326 327 328 329//===----------------------------------------------------------------------===// 330// ModuleLinker implementation. 331//===----------------------------------------------------------------------===// 332 333namespace { 334 /// ModuleLinker - This is an implementation class for the LinkModules 335 /// function, which is the entrypoint for this file. 336 class ModuleLinker { 337 Module *DstM, *SrcM; 338 339 TypeMapTy TypeMap; 340 341 /// ValueMap - Mapping of values from what they used to be in Src, to what 342 /// they are now in DstM. ValueToValueMapTy is a ValueMap, which involves 343 /// some overhead due to the use of Value handles which the Linker doesn't 344 /// actually need, but this allows us to reuse the ValueMapper code. 345 ValueToValueMapTy ValueMap; 346 347 struct AppendingVarInfo { 348 GlobalVariable *NewGV; // New aggregate global in dest module. 349 Constant *DstInit; // Old initializer from dest module. 350 Constant *SrcInit; // Old initializer from src module. 351 }; 352 353 std::vector<AppendingVarInfo> AppendingVars; 354 355 unsigned Mode; // Mode to treat source module. 356 357 // Set of items not to link in from source. 358 SmallPtrSet<const Value*, 16> DoNotLinkFromSource; 359 360 // Vector of functions to lazily link in. 361 std::vector<Function*> LazilyLinkFunctions; 362 363 public: 364 std::string ErrorMsg; 365 366 ModuleLinker(Module *dstM, Module *srcM, unsigned mode) 367 : DstM(dstM), SrcM(srcM), Mode(mode) { } 368 369 bool run(); 370 371 private: 372 /// emitError - Helper method for setting a message and returning an error 373 /// code. 374 bool emitError(const Twine &Message) { 375 ErrorMsg = Message.str(); 376 return true; 377 } 378 379 /// getLinkageResult - This analyzes the two global values and determines 380 /// what the result will look like in the destination module. 381 bool getLinkageResult(GlobalValue *Dest, const GlobalValue *Src, 382 GlobalValue::LinkageTypes <, bool &LinkFromSrc); 383 384 /// getLinkedToGlobal - Given a global in the source module, return the 385 /// global in the destination module that is being linked to, if any. 386 GlobalValue *getLinkedToGlobal(GlobalValue *SrcGV) { 387 // If the source has no name it can't link. If it has local linkage, 388 // there is no name match-up going on. 389 if (!SrcGV->hasName() || SrcGV->hasLocalLinkage()) 390 return 0; 391 392 // Otherwise see if we have a match in the destination module's symtab. 393 GlobalValue *DGV = DstM->getNamedValue(SrcGV->getName()); 394 if (DGV == 0) return 0; 395 396 // If we found a global with the same name in the dest module, but it has 397 // internal linkage, we are really not doing any linkage here. 398 if (DGV->hasLocalLinkage()) 399 return 0; 400 401 // Otherwise, we do in fact link to the destination global. 402 return DGV; 403 } 404 405 void computeTypeMapping(); 406 407 bool linkAppendingVarProto(GlobalVariable *DstGV, GlobalVariable *SrcGV); 408 bool linkGlobalProto(GlobalVariable *SrcGV); 409 bool linkFunctionProto(Function *SrcF); 410 bool linkAliasProto(GlobalAlias *SrcA); 411 412 void linkAppendingVarInit(const AppendingVarInfo &AVI); 413 void linkGlobalInits(); 414 void linkFunctionBody(Function *Dst, Function *Src); 415 void linkAliasBodies(); 416 void linkNamedMDNodes(); 417 }; 418} 419 420 421 422/// forceRenaming - The LLVM SymbolTable class autorenames globals that conflict 423/// in the symbol table. This is good for all clients except for us. Go 424/// through the trouble to force this back. 425static void forceRenaming(GlobalValue *GV, StringRef Name) { 426 // If the global doesn't force its name or if it already has the right name, 427 // there is nothing for us to do. 428 if (GV->hasLocalLinkage() || GV->getName() == Name) 429 return; 430 431 Module *M = GV->getParent(); 432 433 // If there is a conflict, rename the conflict. 434 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) { 435 GV->takeName(ConflictGV); 436 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed 437 assert(ConflictGV->getName() != Name && "forceRenaming didn't work"); 438 } else { 439 GV->setName(Name); // Force the name back 440 } 441} 442 443/// CopyGVAttributes - copy additional attributes (those not needed to construct 444/// a GlobalValue) from the SrcGV to the DestGV. 445static void CopyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) { 446 // Use the maximum alignment, rather than just copying the alignment of SrcGV. 447 unsigned Alignment = std::max(DestGV->getAlignment(), SrcGV->getAlignment()); 448 DestGV->copyAttributesFrom(SrcGV); 449 DestGV->setAlignment(Alignment); 450 451 forceRenaming(DestGV, SrcGV->getName()); 452} 453 454/// getLinkageResult - This analyzes the two global values and determines what 455/// the result will look like in the destination module. In particular, it 456/// computes the resultant linkage type, computes whether the global in the 457/// source should be copied over to the destination (replacing the existing 458/// one), and computes whether this linkage is an error or not. It also performs 459/// visibility checks: we cannot link together two symbols with different 460/// visibilities. 461bool ModuleLinker::getLinkageResult(GlobalValue *Dest, const GlobalValue *Src, 462 GlobalValue::LinkageTypes <, 463 bool &LinkFromSrc) { 464 assert(Dest && "Must have two globals being queried"); 465 assert(!Src->hasLocalLinkage() && 466 "If Src has internal linkage, Dest shouldn't be set!"); 467 468 bool SrcIsDeclaration = Src->isDeclaration() && !Src->isMaterializable(); 469 bool DestIsDeclaration = Dest->isDeclaration(); 470 471 if (SrcIsDeclaration) { 472 // If Src is external or if both Src & Dest are external.. Just link the 473 // external globals, we aren't adding anything. 474 if (Src->hasDLLImportLinkage()) { 475 // If one of GVs has DLLImport linkage, result should be dllimport'ed. 476 if (DestIsDeclaration) { 477 LinkFromSrc = true; 478 LT = Src->getLinkage(); 479 } 480 } else if (Dest->hasExternalWeakLinkage()) { 481 // If the Dest is weak, use the source linkage. 482 LinkFromSrc = true; 483 LT = Src->getLinkage(); 484 } else { 485 LinkFromSrc = false; 486 LT = Dest->getLinkage(); 487 } 488 } else if (DestIsDeclaration && !Dest->hasDLLImportLinkage()) { 489 // If Dest is external but Src is not: 490 LinkFromSrc = true; 491 LT = Src->getLinkage(); 492 } else if (Src->isWeakForLinker()) { 493 // At this point we know that Dest has LinkOnce, External*, Weak, Common, 494 // or DLL* linkage. 495 if (Dest->hasExternalWeakLinkage() || 496 Dest->hasAvailableExternallyLinkage() || 497 (Dest->hasLinkOnceLinkage() && 498 (Src->hasWeakLinkage() || Src->hasCommonLinkage()))) { 499 LinkFromSrc = true; 500 LT = Src->getLinkage(); 501 } else { 502 LinkFromSrc = false; 503 LT = Dest->getLinkage(); 504 } 505 } else if (Dest->isWeakForLinker()) { 506 // At this point we know that Src has External* or DLL* linkage. 507 if (Src->hasExternalWeakLinkage()) { 508 LinkFromSrc = false; 509 LT = Dest->getLinkage(); 510 } else { 511 LinkFromSrc = true; 512 LT = GlobalValue::ExternalLinkage; 513 } 514 } else { 515 assert((Dest->hasExternalLinkage() || Dest->hasDLLImportLinkage() || 516 Dest->hasDLLExportLinkage() || Dest->hasExternalWeakLinkage()) && 517 (Src->hasExternalLinkage() || Src->hasDLLImportLinkage() || 518 Src->hasDLLExportLinkage() || Src->hasExternalWeakLinkage()) && 519 "Unexpected linkage type!"); 520 return emitError("Linking globals named '" + Src->getName() + 521 "': symbol multiply defined!"); 522 } 523 524 // Check visibility 525 if (Src->getVisibility() != Dest->getVisibility() && 526 !SrcIsDeclaration && !DestIsDeclaration && 527 !Src->hasAvailableExternallyLinkage() && 528 !Dest->hasAvailableExternallyLinkage()) 529 return emitError("Linking globals named '" + Src->getName() + 530 "': symbols have different visibilities!"); 531 return false; 532} 533 534/// computeTypeMapping - Loop over all of the linked values to compute type 535/// mappings. For example, if we link "extern Foo *x" and "Foo *x = NULL", then 536/// we have two struct types 'Foo' but one got renamed when the module was 537/// loaded into the same LLVMContext. 538void ModuleLinker::computeTypeMapping() { 539 // Incorporate globals. 540 for (Module::global_iterator I = SrcM->global_begin(), 541 E = SrcM->global_end(); I != E; ++I) { 542 GlobalValue *DGV = getLinkedToGlobal(I); 543 if (DGV == 0) continue; 544 545 if (!DGV->hasAppendingLinkage() || !I->hasAppendingLinkage()) { 546 TypeMap.addTypeMapping(DGV->getType(), I->getType()); 547 continue; 548 } 549 550 // Unify the element type of appending arrays. 551 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType()); 552 ArrayType *SAT = cast<ArrayType>(I->getType()->getElementType()); 553 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType()); 554 } 555 556 // Incorporate functions. 557 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I) { 558 if (GlobalValue *DGV = getLinkedToGlobal(I)) 559 TypeMap.addTypeMapping(DGV->getType(), I->getType()); 560 } 561 562 // Incorporate types by name, scanning all the types in the source module. 563 // At this point, the destination module may have a type "%foo = { i32 }" for 564 // example. When the source module got loaded into the same LLVMContext, if 565 // it had the same type, it would have been renamed to "%foo.42 = { i32 }". 566 // Though it isn't required for correctness, attempt to link these up to clean 567 // up the IR. 568 std::vector<StructType*> SrcStructTypes; 569 SrcM->findUsedStructTypes(SrcStructTypes); 570 571 SmallPtrSet<StructType*, 32> SrcStructTypesSet(SrcStructTypes.begin(), 572 SrcStructTypes.end()); 573 574 for (unsigned i = 0, e = SrcStructTypes.size(); i != e; ++i) { 575 StructType *ST = SrcStructTypes[i]; 576 if (!ST->hasName()) continue; 577 578 // Check to see if there is a dot in the name followed by a digit. 579 size_t DotPos = ST->getName().rfind('.'); 580 if (DotPos == 0 || DotPos == StringRef::npos || 581 ST->getName().back() == '.' || !isdigit(ST->getName()[DotPos+1])) 582 continue; 583 584 // Check to see if the destination module has a struct with the prefix name. 585 if (StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos))) 586 // Don't use it if this actually came from the source module. They're in 587 // the same LLVMContext after all. 588 if (!SrcStructTypesSet.count(DST)) 589 TypeMap.addTypeMapping(DST, ST); 590 } 591 592 593 // Don't bother incorporating aliases, they aren't generally typed well. 594 595 // Now that we have discovered all of the type equivalences, get a body for 596 // any 'opaque' types in the dest module that are now resolved. 597 TypeMap.linkDefinedTypeBodies(); 598} 599 600/// linkAppendingVarProto - If there were any appending global variables, link 601/// them together now. Return true on error. 602bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV, 603 GlobalVariable *SrcGV) { 604 605 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage()) 606 return emitError("Linking globals named '" + SrcGV->getName() + 607 "': can only link appending global with another appending global!"); 608 609 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType()); 610 ArrayType *SrcTy = 611 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType())); 612 Type *EltTy = DstTy->getElementType(); 613 614 // Check to see that they two arrays agree on type. 615 if (EltTy != SrcTy->getElementType()) 616 return emitError("Appending variables with different element types!"); 617 if (DstGV->isConstant() != SrcGV->isConstant()) 618 return emitError("Appending variables linked with different const'ness!"); 619 620 if (DstGV->getAlignment() != SrcGV->getAlignment()) 621 return emitError( 622 "Appending variables with different alignment need to be linked!"); 623 624 if (DstGV->getVisibility() != SrcGV->getVisibility()) 625 return emitError( 626 "Appending variables with different visibility need to be linked!"); 627 628 if (DstGV->getSection() != SrcGV->getSection()) 629 return emitError( 630 "Appending variables with different section name need to be linked!"); 631 632 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements(); 633 ArrayType *NewType = ArrayType::get(EltTy, NewSize); 634 635 // Create the new global variable. 636 GlobalVariable *NG = 637 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(), 638 DstGV->getLinkage(), /*init*/0, /*name*/"", DstGV, 639 DstGV->isThreadLocal(), 640 DstGV->getType()->getAddressSpace()); 641 642 // Propagate alignment, visibility and section info. 643 CopyGVAttributes(NG, DstGV); 644 645 AppendingVarInfo AVI; 646 AVI.NewGV = NG; 647 AVI.DstInit = DstGV->getInitializer(); 648 AVI.SrcInit = SrcGV->getInitializer(); 649 AppendingVars.push_back(AVI); 650 651 // Replace any uses of the two global variables with uses of the new 652 // global. 653 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType())); 654 655 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType())); 656 DstGV->eraseFromParent(); 657 658 // Track the source variable so we don't try to link it. 659 DoNotLinkFromSource.insert(SrcGV); 660 661 return false; 662} 663 664/// linkGlobalProto - Loop through the global variables in the src module and 665/// merge them into the dest module. 666bool ModuleLinker::linkGlobalProto(GlobalVariable *SGV) { 667 GlobalValue *DGV = getLinkedToGlobal(SGV); 668 669 if (DGV) { 670 // Concatenation of appending linkage variables is magic and handled later. 671 if (DGV->hasAppendingLinkage() || SGV->hasAppendingLinkage()) 672 return linkAppendingVarProto(cast<GlobalVariable>(DGV), SGV); 673 674 // Determine whether linkage of these two globals follows the source 675 // module's definition or the destination module's definition. 676 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 677 bool LinkFromSrc = false; 678 if (getLinkageResult(DGV, SGV, NewLinkage, LinkFromSrc)) 679 return true; 680 681 // If we're not linking from the source, then keep the definition that we 682 // have. 683 if (!LinkFromSrc) { 684 // Special case for const propagation. 685 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) 686 if (DGVar->isDeclaration() && SGV->isConstant() && !DGVar->isConstant()) 687 DGVar->setConstant(true); 688 689 // Set calculated linkage. 690 DGV->setLinkage(NewLinkage); 691 692 // Make sure to remember this mapping. 693 ValueMap[SGV] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGV->getType())); 694 695 // Track the source global so that we don't attempt to copy it over when 696 // processing global initializers. 697 DoNotLinkFromSource.insert(SGV); 698 699 return false; 700 } 701 } 702 703 // No linking to be performed or linking from the source: simply create an 704 // identical version of the symbol over in the dest module... the 705 // initializer will be filled in later by LinkGlobalInits. 706 GlobalVariable *NewDGV = 707 new GlobalVariable(*DstM, TypeMap.get(SGV->getType()->getElementType()), 708 SGV->isConstant(), SGV->getLinkage(), /*init*/0, 709 SGV->getName(), /*insertbefore*/0, 710 SGV->isThreadLocal(), 711 SGV->getType()->getAddressSpace()); 712 // Propagate alignment, visibility and section info. 713 CopyGVAttributes(NewDGV, SGV); 714 715 if (DGV) { 716 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV, DGV->getType())); 717 DGV->eraseFromParent(); 718 } 719 720 // Make sure to remember this mapping. 721 ValueMap[SGV] = NewDGV; 722 return false; 723} 724 725/// linkFunctionProto - Link the function in the source module into the 726/// destination module if needed, setting up mapping information. 727bool ModuleLinker::linkFunctionProto(Function *SF) { 728 GlobalValue *DGV = getLinkedToGlobal(SF); 729 730 if (DGV) { 731 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 732 bool LinkFromSrc = false; 733 if (getLinkageResult(DGV, SF, NewLinkage, LinkFromSrc)) 734 return true; 735 736 if (!LinkFromSrc) { 737 // Set calculated linkage 738 DGV->setLinkage(NewLinkage); 739 740 // Make sure to remember this mapping. 741 ValueMap[SF] = ConstantExpr::getBitCast(DGV, TypeMap.get(SF->getType())); 742 743 // Track the function from the source module so we don't attempt to remap 744 // it. 745 DoNotLinkFromSource.insert(SF); 746 747 return false; 748 } 749 } 750 751 // If there is no linkage to be performed or we are linking from the source, 752 // bring SF over. 753 Function *NewDF = Function::Create(TypeMap.get(SF->getFunctionType()), 754 SF->getLinkage(), SF->getName(), DstM); 755 CopyGVAttributes(NewDF, SF); 756 757 if (DGV) { 758 // Any uses of DF need to change to NewDF, with cast. 759 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, DGV->getType())); 760 DGV->eraseFromParent(); 761 } else { 762 // Internal, LO_ODR, or LO linkage - stick in set to ignore and lazily link. 763 if (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() || 764 SF->hasAvailableExternallyLinkage()) { 765 DoNotLinkFromSource.insert(SF); 766 LazilyLinkFunctions.push_back(SF); 767 } 768 } 769 770 ValueMap[SF] = NewDF; 771 return false; 772} 773 774/// LinkAliasProto - Set up prototypes for any aliases that come over from the 775/// source module. 776bool ModuleLinker::linkAliasProto(GlobalAlias *SGA) { 777 GlobalValue *DGV = getLinkedToGlobal(SGA); 778 779 if (DGV) { 780 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 781 bool LinkFromSrc = false; 782 if (getLinkageResult(DGV, SGA, NewLinkage, LinkFromSrc)) 783 return true; 784 785 if (!LinkFromSrc) { 786 // Set calculated linkage. 787 DGV->setLinkage(NewLinkage); 788 789 // Make sure to remember this mapping. 790 ValueMap[SGA] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGA->getType())); 791 792 // Track the alias from the source module so we don't attempt to remap it. 793 DoNotLinkFromSource.insert(SGA); 794 795 return false; 796 } 797 } 798 799 // If there is no linkage to be performed or we're linking from the source, 800 // bring over SGA. 801 GlobalAlias *NewDA = new GlobalAlias(TypeMap.get(SGA->getType()), 802 SGA->getLinkage(), SGA->getName(), 803 /*aliasee*/0, DstM); 804 CopyGVAttributes(NewDA, SGA); 805 806 if (DGV) { 807 // Any uses of DGV need to change to NewDA, with cast. 808 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDA, DGV->getType())); 809 DGV->eraseFromParent(); 810 } 811 812 ValueMap[SGA] = NewDA; 813 return false; 814} 815 816void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) { 817 // Merge the initializer. 818 SmallVector<Constant*, 16> Elements; 819 if (ConstantArray *I = dyn_cast<ConstantArray>(AVI.DstInit)) { 820 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) 821 Elements.push_back(I->getOperand(i)); 822 } else { 823 assert(isa<ConstantAggregateZero>(AVI.DstInit)); 824 ArrayType *DstAT = cast<ArrayType>(AVI.DstInit->getType()); 825 Type *EltTy = DstAT->getElementType(); 826 Elements.append(DstAT->getNumElements(), Constant::getNullValue(EltTy)); 827 } 828 829 Constant *SrcInit = MapValue(AVI.SrcInit, ValueMap, RF_None, &TypeMap); 830 if (const ConstantArray *I = dyn_cast<ConstantArray>(SrcInit)) { 831 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) 832 Elements.push_back(I->getOperand(i)); 833 } else { 834 assert(isa<ConstantAggregateZero>(SrcInit)); 835 ArrayType *SrcAT = cast<ArrayType>(SrcInit->getType()); 836 Type *EltTy = SrcAT->getElementType(); 837 Elements.append(SrcAT->getNumElements(), Constant::getNullValue(EltTy)); 838 } 839 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType()); 840 AVI.NewGV->setInitializer(ConstantArray::get(NewType, Elements)); 841} 842 843 844// linkGlobalInits - Update the initializers in the Dest module now that all 845// globals that may be referenced are in Dest. 846void ModuleLinker::linkGlobalInits() { 847 // Loop over all of the globals in the src module, mapping them over as we go 848 for (Module::const_global_iterator I = SrcM->global_begin(), 849 E = SrcM->global_end(); I != E; ++I) { 850 851 // Only process initialized GV's or ones not already in dest. 852 if (!I->hasInitializer() || DoNotLinkFromSource.count(I)) continue; 853 854 // Grab destination global variable. 855 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[I]); 856 // Figure out what the initializer looks like in the dest module. 857 DGV->setInitializer(MapValue(I->getInitializer(), ValueMap, 858 RF_None, &TypeMap)); 859 } 860} 861 862// linkFunctionBody - Copy the source function over into the dest function and 863// fix up references to values. At this point we know that Dest is an external 864// function, and that Src is not. 865void ModuleLinker::linkFunctionBody(Function *Dst, Function *Src) { 866 assert(Src && Dst && Dst->isDeclaration() && !Src->isDeclaration()); 867 868 // Go through and convert function arguments over, remembering the mapping. 869 Function::arg_iterator DI = Dst->arg_begin(); 870 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 871 I != E; ++I, ++DI) { 872 DI->setName(I->getName()); // Copy the name over. 873 874 // Add a mapping to our mapping. 875 ValueMap[I] = DI; 876 } 877 878 if (Mode == Linker::DestroySource) { 879 // Splice the body of the source function into the dest function. 880 Dst->getBasicBlockList().splice(Dst->end(), Src->getBasicBlockList()); 881 882 // At this point, all of the instructions and values of the function are now 883 // copied over. The only problem is that they are still referencing values in 884 // the Source function as operands. Loop through all of the operands of the 885 // functions and patch them up to point to the local versions. 886 for (Function::iterator BB = Dst->begin(), BE = Dst->end(); BB != BE; ++BB) 887 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) 888 RemapInstruction(I, ValueMap, RF_IgnoreMissingEntries, &TypeMap); 889 890 } else { 891 // Clone the body of the function into the dest function. 892 SmallVector<ReturnInst*, 8> Returns; // Ignore returns. 893 CloneFunctionInto(Dst, Src, ValueMap, false, Returns); 894 } 895 896 // There is no need to map the arguments anymore. 897 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 898 I != E; ++I) 899 ValueMap.erase(I); 900 901} 902 903 904void ModuleLinker::linkAliasBodies() { 905 for (Module::alias_iterator I = SrcM->alias_begin(), E = SrcM->alias_end(); 906 I != E; ++I) { 907 if (DoNotLinkFromSource.count(I)) 908 continue; 909 if (Constant *Aliasee = I->getAliasee()) { 910 GlobalAlias *DA = cast<GlobalAlias>(ValueMap[I]); 911 DA->setAliasee(MapValue(Aliasee, ValueMap, RF_None, &TypeMap)); 912 } 913 } 914} 915 916/// linkNamedMDNodes - Insert all of the named mdnodes in Src into the Dest 917/// module. 918void ModuleLinker::linkNamedMDNodes() { 919 for (Module::const_named_metadata_iterator I = SrcM->named_metadata_begin(), 920 E = SrcM->named_metadata_end(); I != E; ++I) { 921 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(I->getName()); 922 // Add Src elements into Dest node. 923 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) 924 DestNMD->addOperand(MapValue(I->getOperand(i), ValueMap, 925 RF_None, &TypeMap)); 926 } 927} 928 929bool ModuleLinker::run() { 930 assert(DstM && "Null Destination module"); 931 assert(SrcM && "Null Source Module"); 932 933 // Inherit the target data from the source module if the destination module 934 // doesn't have one already. 935 if (DstM->getDataLayout().empty() && !SrcM->getDataLayout().empty()) 936 DstM->setDataLayout(SrcM->getDataLayout()); 937 938 // Copy the target triple from the source to dest if the dest's is empty. 939 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty()) 940 DstM->setTargetTriple(SrcM->getTargetTriple()); 941 942 if (!SrcM->getDataLayout().empty() && !DstM->getDataLayout().empty() && 943 SrcM->getDataLayout() != DstM->getDataLayout()) 944 errs() << "WARNING: Linking two modules of different data layouts!\n"; 945 if (!SrcM->getTargetTriple().empty() && 946 DstM->getTargetTriple() != SrcM->getTargetTriple()) { 947 errs() << "WARNING: Linking two modules of different target triples: "; 948 if (!SrcM->getModuleIdentifier().empty()) 949 errs() << SrcM->getModuleIdentifier() << ": "; 950 errs() << "'" << SrcM->getTargetTriple() << "' and '" 951 << DstM->getTargetTriple() << "'\n"; 952 } 953 954 // Append the module inline asm string. 955 if (!SrcM->getModuleInlineAsm().empty()) { 956 if (DstM->getModuleInlineAsm().empty()) 957 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm()); 958 else 959 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+ 960 SrcM->getModuleInlineAsm()); 961 } 962 963 // Update the destination module's dependent libraries list with the libraries 964 // from the source module. There's no opportunity for duplicates here as the 965 // Module ensures that duplicate insertions are discarded. 966 for (Module::lib_iterator SI = SrcM->lib_begin(), SE = SrcM->lib_end(); 967 SI != SE; ++SI) 968 DstM->addLibrary(*SI); 969 970 // If the source library's module id is in the dependent library list of the 971 // destination library, remove it since that module is now linked in. 972 StringRef ModuleId = SrcM->getModuleIdentifier(); 973 if (!ModuleId.empty()) 974 DstM->removeLibrary(sys::path::stem(ModuleId)); 975 976 // Loop over all of the linked values to compute type mappings. 977 computeTypeMapping(); 978 979 // Insert all of the globals in src into the DstM module... without linking 980 // initializers (which could refer to functions not yet mapped over). 981 for (Module::global_iterator I = SrcM->global_begin(), 982 E = SrcM->global_end(); I != E; ++I) 983 if (linkGlobalProto(I)) 984 return true; 985 986 // Link the functions together between the two modules, without doing function 987 // bodies... this just adds external function prototypes to the DstM 988 // function... We do this so that when we begin processing function bodies, 989 // all of the global values that may be referenced are available in our 990 // ValueMap. 991 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I) 992 if (linkFunctionProto(I)) 993 return true; 994 995 // If there were any aliases, link them now. 996 for (Module::alias_iterator I = SrcM->alias_begin(), 997 E = SrcM->alias_end(); I != E; ++I) 998 if (linkAliasProto(I)) 999 return true; 1000 1001 for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i) 1002 linkAppendingVarInit(AppendingVars[i]); 1003 1004 // Update the initializers in the DstM module now that all globals that may 1005 // be referenced are in DstM. 1006 linkGlobalInits(); 1007 1008 // Link in the function bodies that are defined in the source module into 1009 // DstM. 1010 for (Module::iterator SF = SrcM->begin(), E = SrcM->end(); SF != E; ++SF) { 1011 1012 // Skip if not linking from source. 1013 if (DoNotLinkFromSource.count(SF)) continue; 1014 1015 // Skip if no body (function is external) or materialize. 1016 if (SF->isDeclaration()) { 1017 if (!SF->isMaterializable()) 1018 continue; 1019 if (SF->Materialize(&ErrorMsg)) 1020 return true; 1021 } 1022 1023 linkFunctionBody(cast<Function>(ValueMap[SF]), SF); 1024 } 1025 1026 // Resolve all uses of aliases with aliasees. 1027 linkAliasBodies(); 1028 1029 // Remap all of the named mdnoes in Src into the DstM module. We do this 1030 // after linking GlobalValues so that MDNodes that reference GlobalValues 1031 // are properly remapped. 1032 linkNamedMDNodes(); 1033 1034 // Process vector of lazily linked in functions. 1035 bool LinkedInAnyFunctions; 1036 do { 1037 LinkedInAnyFunctions = false; 1038 1039 for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(), 1040 E = LazilyLinkFunctions.end(); I != E; ++I) { 1041 if (!*I) 1042 continue; 1043 1044 Function *SF = *I; 1045 Function *DF = cast<Function>(ValueMap[SF]); 1046 1047 if (!DF->use_empty()) { 1048 1049 // Materialize if necessary. 1050 if (SF->isDeclaration()) { 1051 if (!SF->isMaterializable()) 1052 continue; 1053 if (SF->Materialize(&ErrorMsg)) 1054 return true; 1055 } 1056 1057 // Link in function body. 1058 linkFunctionBody(DF, SF); 1059 1060 // "Remove" from vector by setting the element to 0. 1061 *I = 0; 1062 1063 // Set flag to indicate we may have more functions to lazily link in 1064 // since we linked in a function. 1065 LinkedInAnyFunctions = true; 1066 } 1067 } 1068 } while (LinkedInAnyFunctions); 1069 1070 // Remove any prototypes of functions that were not actually linked in. 1071 for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(), 1072 E = LazilyLinkFunctions.end(); I != E; ++I) { 1073 if (!*I) 1074 continue; 1075 1076 Function *SF = *I; 1077 Function *DF = cast<Function>(ValueMap[SF]); 1078 if (DF->use_empty()) 1079 DF->eraseFromParent(); 1080 } 1081 1082 // Now that all of the types from the source are used, resolve any structs 1083 // copied over to the dest that didn't exist there. 1084 TypeMap.linkDefinedTypeBodies(); 1085 1086 return false; 1087} 1088 1089//===----------------------------------------------------------------------===// 1090// LinkModules entrypoint. 1091//===----------------------------------------------------------------------===// 1092 1093// LinkModules - This function links two modules together, with the resulting 1094// left module modified to be the composite of the two input modules. If an 1095// error occurs, true is returned and ErrorMsg (if not null) is set to indicate 1096// the problem. Upon failure, the Dest module could be in a modified state, and 1097// shouldn't be relied on to be consistent. 1098bool Linker::LinkModules(Module *Dest, Module *Src, unsigned Mode, 1099 std::string *ErrorMsg) { 1100 ModuleLinker TheLinker(Dest, Src, Mode); 1101 if (TheLinker.run()) { 1102 if (ErrorMsg) *ErrorMsg = TheLinker.ErrorMsg; 1103 return true; 1104 } 1105 1106 return false; 1107} 1108