1 //===- lib/Linker/LinkModules.cpp - Module Linker Implementation ----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the LLVM module linker.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Linker/Linker.h"
15 #include "llvm-c/Linker.h"
16 #include "llvm/ADT/Hashing.h"
17 #include "llvm/ADT/Optional.h"
18 #include "llvm/ADT/SetVector.h"
19 #include "llvm/ADT/SmallString.h"
20 #include "llvm/ADT/Statistic.h"
21 #include "llvm/IR/Constants.h"
22 #include "llvm/IR/DiagnosticInfo.h"
23 #include "llvm/IR/DiagnosticPrinter.h"
24 #include "llvm/IR/LLVMContext.h"
25 #include "llvm/IR/Module.h"
26 #include "llvm/IR/TypeFinder.h"
27 #include "llvm/Support/CommandLine.h"
28 #include "llvm/Support/Debug.h"
29 #include "llvm/Support/raw_ostream.h"
30 #include "llvm/Transforms/Utils/Cloning.h"
36 //===----------------------------------------------------------------------===//
37 // TypeMap implementation.
38 //===----------------------------------------------------------------------===//
41 class TypeMapTy : public ValueMapTypeRemapper {
42 /// This is a mapping from a source type to a destination type to use.
43 DenseMap<Type*, Type*> MappedTypes;
45 /// When checking to see if two subgraphs are isomorphic, we speculatively
46 /// add types to MappedTypes, but keep track of them here in case we need to
48 SmallVector<Type*, 16> SpeculativeTypes;
50 SmallVector<StructType*, 16> SpeculativeDstOpaqueTypes;
52 /// This is a list of non-opaque structs in the source module that are mapped
53 /// to an opaque struct in the destination module.
54 SmallVector<StructType*, 16> SrcDefinitionsToResolve;
56 /// This is the set of opaque types in the destination modules who are
57 /// getting a body from the source module.
58 SmallPtrSet<StructType*, 16> DstResolvedOpaqueTypes;
61 TypeMapTy(Linker::IdentifiedStructTypeSet &DstStructTypesSet)
62 : DstStructTypesSet(DstStructTypesSet) {}
64 Linker::IdentifiedStructTypeSet &DstStructTypesSet;
65 /// Indicate that the specified type in the destination module is conceptually
66 /// equivalent to the specified type in the source module.
67 void addTypeMapping(Type *DstTy, Type *SrcTy);
69 /// Produce a body for an opaque type in the dest module from a type
70 /// definition in the source module.
71 void linkDefinedTypeBodies();
73 /// Return the mapped type to use for the specified input type from the
75 Type *get(Type *SrcTy);
76 Type *get(Type *SrcTy, SmallPtrSet<StructType *, 8> &Visited);
78 void finishType(StructType *DTy, StructType *STy, ArrayRef<Type *> ETypes);
80 FunctionType *get(FunctionType *T) {
81 return cast<FunctionType>(get((Type *)T));
84 /// Dump out the type map for debugging purposes.
86 for (auto &Pair : MappedTypes) {
87 dbgs() << "TypeMap: ";
88 Pair.first->print(dbgs());
90 Pair.second->print(dbgs());
96 Type *remapType(Type *SrcTy) override { return get(SrcTy); }
98 bool areTypesIsomorphic(Type *DstTy, Type *SrcTy);
102 void TypeMapTy::addTypeMapping(Type *DstTy, Type *SrcTy) {
103 assert(SpeculativeTypes.empty());
104 assert(SpeculativeDstOpaqueTypes.empty());
106 // Check to see if these types are recursively isomorphic and establish a
107 // mapping between them if so.
108 if (!areTypesIsomorphic(DstTy, SrcTy)) {
109 // Oops, they aren't isomorphic. Just discard this request by rolling out
110 // any speculative mappings we've established.
111 for (Type *Ty : SpeculativeTypes)
112 MappedTypes.erase(Ty);
114 SrcDefinitionsToResolve.resize(SrcDefinitionsToResolve.size() -
115 SpeculativeDstOpaqueTypes.size());
116 for (StructType *Ty : SpeculativeDstOpaqueTypes)
117 DstResolvedOpaqueTypes.erase(Ty);
119 for (Type *Ty : SpeculativeTypes)
120 if (auto *STy = dyn_cast<StructType>(Ty))
124 SpeculativeTypes.clear();
125 SpeculativeDstOpaqueTypes.clear();
128 /// Recursively walk this pair of types, returning true if they are isomorphic,
129 /// false if they are not.
130 bool TypeMapTy::areTypesIsomorphic(Type *DstTy, Type *SrcTy) {
131 // Two types with differing kinds are clearly not isomorphic.
132 if (DstTy->getTypeID() != SrcTy->getTypeID())
135 // If we have an entry in the MappedTypes table, then we have our answer.
136 Type *&Entry = MappedTypes[SrcTy];
138 return Entry == DstTy;
140 // Two identical types are clearly isomorphic. Remember this
141 // non-speculatively.
142 if (DstTy == SrcTy) {
147 // Okay, we have two types with identical kinds that we haven't seen before.
149 // If this is an opaque struct type, special case it.
150 if (StructType *SSTy = dyn_cast<StructType>(SrcTy)) {
151 // Mapping an opaque type to any struct, just keep the dest struct.
152 if (SSTy->isOpaque()) {
154 SpeculativeTypes.push_back(SrcTy);
158 // Mapping a non-opaque source type to an opaque dest. If this is the first
159 // type that we're mapping onto this destination type then we succeed. Keep
160 // the dest, but fill it in later. If this is the second (different) type
161 // that we're trying to map onto the same opaque type then we fail.
162 if (cast<StructType>(DstTy)->isOpaque()) {
163 // We can only map one source type onto the opaque destination type.
164 if (!DstResolvedOpaqueTypes.insert(cast<StructType>(DstTy)).second)
166 SrcDefinitionsToResolve.push_back(SSTy);
167 SpeculativeTypes.push_back(SrcTy);
168 SpeculativeDstOpaqueTypes.push_back(cast<StructType>(DstTy));
174 // If the number of subtypes disagree between the two types, then we fail.
175 if (SrcTy->getNumContainedTypes() != DstTy->getNumContainedTypes())
178 // Fail if any of the extra properties (e.g. array size) of the type disagree.
179 if (isa<IntegerType>(DstTy))
180 return false; // bitwidth disagrees.
181 if (PointerType *PT = dyn_cast<PointerType>(DstTy)) {
182 if (PT->getAddressSpace() != cast<PointerType>(SrcTy)->getAddressSpace())
185 } else if (FunctionType *FT = dyn_cast<FunctionType>(DstTy)) {
186 if (FT->isVarArg() != cast<FunctionType>(SrcTy)->isVarArg())
188 } else if (StructType *DSTy = dyn_cast<StructType>(DstTy)) {
189 StructType *SSTy = cast<StructType>(SrcTy);
190 if (DSTy->isLiteral() != SSTy->isLiteral() ||
191 DSTy->isPacked() != SSTy->isPacked())
193 } else if (ArrayType *DATy = dyn_cast<ArrayType>(DstTy)) {
194 if (DATy->getNumElements() != cast<ArrayType>(SrcTy)->getNumElements())
196 } else if (VectorType *DVTy = dyn_cast<VectorType>(DstTy)) {
197 if (DVTy->getNumElements() != cast<VectorType>(SrcTy)->getNumElements())
201 // Otherwise, we speculate that these two types will line up and recursively
202 // check the subelements.
204 SpeculativeTypes.push_back(SrcTy);
206 for (unsigned I = 0, E = SrcTy->getNumContainedTypes(); I != E; ++I)
207 if (!areTypesIsomorphic(DstTy->getContainedType(I),
208 SrcTy->getContainedType(I)))
211 // If everything seems to have lined up, then everything is great.
215 void TypeMapTy::linkDefinedTypeBodies() {
216 SmallVector<Type*, 16> Elements;
217 for (StructType *SrcSTy : SrcDefinitionsToResolve) {
218 StructType *DstSTy = cast<StructType>(MappedTypes[SrcSTy]);
219 assert(DstSTy->isOpaque());
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] = get(SrcSTy->getElementType(I));
226 DstSTy->setBody(Elements, SrcSTy->isPacked());
228 SrcDefinitionsToResolve.clear();
229 DstResolvedOpaqueTypes.clear();
232 void TypeMapTy::finishType(StructType *DTy, StructType *STy,
233 ArrayRef<Type *> ETypes) {
234 DTy->setBody(ETypes, STy->isPacked());
237 if (STy->hasName()) {
238 SmallString<16> TmpName = STy->getName();
240 DTy->setName(TmpName);
243 DstStructTypesSet.addNonOpaque(DTy);
246 Type *TypeMapTy::get(Type *Ty) {
247 SmallPtrSet<StructType *, 8> Visited;
248 return get(Ty, Visited);
251 Type *TypeMapTy::get(Type *Ty, SmallPtrSet<StructType *, 8> &Visited) {
252 // If we already have an entry for this type, return it.
253 Type **Entry = &MappedTypes[Ty];
257 // These are types that LLVM itself will unique.
258 bool IsUniqued = !isa<StructType>(Ty) || cast<StructType>(Ty)->isLiteral();
262 for (auto &Pair : MappedTypes) {
263 assert(!(Pair.first != Ty && Pair.second == Ty) &&
264 "mapping to a source type");
269 if (!IsUniqued && !Visited.insert(cast<StructType>(Ty)).second) {
270 StructType *DTy = StructType::create(Ty->getContext());
274 // If this is not a recursive type, then just map all of the elements and
275 // then rebuild the type from inside out.
276 SmallVector<Type *, 4> ElementTypes;
278 // If there are no element types to map, then the type is itself. This is
279 // true for the anonymous {} struct, things like 'float', integers, etc.
280 if (Ty->getNumContainedTypes() == 0 && IsUniqued)
283 // Remap all of the elements, keeping track of whether any of them change.
284 bool AnyChange = false;
285 ElementTypes.resize(Ty->getNumContainedTypes());
286 for (unsigned I = 0, E = Ty->getNumContainedTypes(); I != E; ++I) {
287 ElementTypes[I] = get(Ty->getContainedType(I), Visited);
288 AnyChange |= ElementTypes[I] != Ty->getContainedType(I);
291 // If we found our type while recursively processing stuff, just use it.
292 Entry = &MappedTypes[Ty];
294 if (auto *DTy = dyn_cast<StructType>(*Entry)) {
295 if (DTy->isOpaque()) {
296 auto *STy = cast<StructType>(Ty);
297 finishType(DTy, STy, ElementTypes);
303 // If all of the element types mapped directly over and the type is not
304 // a nomed struct, then the type is usable as-is.
305 if (!AnyChange && IsUniqued)
308 // Otherwise, rebuild a modified type.
309 switch (Ty->getTypeID()) {
311 llvm_unreachable("unknown derived type to remap");
312 case Type::ArrayTyID:
313 return *Entry = ArrayType::get(ElementTypes[0],
314 cast<ArrayType>(Ty)->getNumElements());
315 case Type::VectorTyID:
316 return *Entry = VectorType::get(ElementTypes[0],
317 cast<VectorType>(Ty)->getNumElements());
318 case Type::PointerTyID:
319 return *Entry = PointerType::get(ElementTypes[0],
320 cast<PointerType>(Ty)->getAddressSpace());
321 case Type::FunctionTyID:
322 return *Entry = FunctionType::get(ElementTypes[0],
323 makeArrayRef(ElementTypes).slice(1),
324 cast<FunctionType>(Ty)->isVarArg());
325 case Type::StructTyID: {
326 auto *STy = cast<StructType>(Ty);
327 bool IsPacked = STy->isPacked();
329 return *Entry = StructType::get(Ty->getContext(), ElementTypes, IsPacked);
331 // If the type is opaque, we can just use it directly.
332 if (STy->isOpaque()) {
333 DstStructTypesSet.addOpaque(STy);
337 if (StructType *OldT =
338 DstStructTypesSet.findNonOpaque(ElementTypes, IsPacked)) {
340 return *Entry = OldT;
344 DstStructTypesSet.addNonOpaque(STy);
348 StructType *DTy = StructType::create(Ty->getContext());
349 finishType(DTy, STy, ElementTypes);
355 //===----------------------------------------------------------------------===//
356 // ModuleLinker implementation.
357 //===----------------------------------------------------------------------===//
362 /// Creates prototypes for functions that are lazily linked on the fly. This
363 /// speeds up linking for modules with many/ lazily linked functions of which
365 class ValueMaterializerTy : public ValueMaterializer {
368 std::vector<Function *> &LazilyLinkFunctions;
371 ValueMaterializerTy(TypeMapTy &TypeMap, Module *DstM,
372 std::vector<Function *> &LazilyLinkFunctions)
373 : ValueMaterializer(), TypeMap(TypeMap), DstM(DstM),
374 LazilyLinkFunctions(LazilyLinkFunctions) {}
376 Value *materializeValueFor(Value *V) override;
379 class LinkDiagnosticInfo : public DiagnosticInfo {
383 LinkDiagnosticInfo(DiagnosticSeverity Severity, const Twine &Msg);
384 void print(DiagnosticPrinter &DP) const override;
386 LinkDiagnosticInfo::LinkDiagnosticInfo(DiagnosticSeverity Severity,
388 : DiagnosticInfo(DK_Linker, Severity), Msg(Msg) {}
389 void LinkDiagnosticInfo::print(DiagnosticPrinter &DP) const { DP << Msg; }
391 /// This is an implementation class for the LinkModules function, which is the
392 /// entrypoint for this file.
397 ValueMaterializerTy ValMaterializer;
399 /// Mapping of values from what they used to be in Src, to what they are now
400 /// in DstM. ValueToValueMapTy is a ValueMap, which involves some overhead
401 /// due to the use of Value handles which the Linker doesn't actually need,
402 /// but this allows us to reuse the ValueMapper code.
403 ValueToValueMapTy ValueMap;
405 struct AppendingVarInfo {
406 GlobalVariable *NewGV; // New aggregate global in dest module.
407 const Constant *DstInit; // Old initializer from dest module.
408 const Constant *SrcInit; // Old initializer from src module.
411 std::vector<AppendingVarInfo> AppendingVars;
413 // Set of items not to link in from source.
414 SmallPtrSet<const Value *, 16> DoNotLinkFromSource;
416 // Vector of functions to lazily link in.
417 std::vector<Function *> LazilyLinkFunctions;
419 Linker::DiagnosticHandlerFunction DiagnosticHandler;
422 ModuleLinker(Module *dstM, Linker::IdentifiedStructTypeSet &Set, Module *srcM,
423 Linker::DiagnosticHandlerFunction DiagnosticHandler)
424 : DstM(dstM), SrcM(srcM), TypeMap(Set),
425 ValMaterializer(TypeMap, DstM, LazilyLinkFunctions),
426 DiagnosticHandler(DiagnosticHandler) {}
431 bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
432 const GlobalValue &Src);
434 /// Helper method for setting a message and returning an error code.
435 bool emitError(const Twine &Message) {
436 DiagnosticHandler(LinkDiagnosticInfo(DS_Error, Message));
440 void emitWarning(const Twine &Message) {
441 DiagnosticHandler(LinkDiagnosticInfo(DS_Warning, Message));
444 bool getComdatLeader(Module *M, StringRef ComdatName,
445 const GlobalVariable *&GVar);
446 bool computeResultingSelectionKind(StringRef ComdatName,
447 Comdat::SelectionKind Src,
448 Comdat::SelectionKind Dst,
449 Comdat::SelectionKind &Result,
451 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
453 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
456 /// Given a global in the source module, return the global in the
457 /// destination module that is being linked to, if any.
458 GlobalValue *getLinkedToGlobal(const GlobalValue *SrcGV) {
459 // If the source has no name it can't link. If it has local linkage,
460 // there is no name match-up going on.
461 if (!SrcGV->hasName() || SrcGV->hasLocalLinkage())
464 // Otherwise see if we have a match in the destination module's symtab.
465 GlobalValue *DGV = DstM->getNamedValue(SrcGV->getName());
469 // If we found a global with the same name in the dest module, but it has
470 // internal linkage, we are really not doing any linkage here.
471 if (DGV->hasLocalLinkage())
474 // Otherwise, we do in fact link to the destination global.
478 void computeTypeMapping();
480 void upgradeMismatchedGlobalArray(StringRef Name);
481 void upgradeMismatchedGlobals();
483 bool linkAppendingVarProto(GlobalVariable *DstGV,
484 const GlobalVariable *SrcGV);
486 bool linkGlobalValueProto(GlobalValue *GV);
487 GlobalValue *linkGlobalVariableProto(const GlobalVariable *SGVar,
489 GlobalValue *linkFunctionProto(const Function *SF, GlobalValue *DGV);
490 GlobalValue *linkGlobalAliasProto(const GlobalAlias *SGA, GlobalValue *DGV);
492 bool linkModuleFlagsMetadata();
494 void linkAppendingVarInit(const AppendingVarInfo &AVI);
495 void linkGlobalInits();
496 void linkFunctionBody(Function *Dst, Function *Src);
497 void linkAliasBodies();
498 void linkNamedMDNodes();
502 /// The LLVM SymbolTable class autorenames globals that conflict in the symbol
503 /// table. This is good for all clients except for us. Go through the trouble
504 /// to force this back.
505 static void forceRenaming(GlobalValue *GV, StringRef Name) {
506 // If the global doesn't force its name or if it already has the right name,
507 // there is nothing for us to do.
508 if (GV->hasLocalLinkage() || GV->getName() == Name)
511 Module *M = GV->getParent();
513 // If there is a conflict, rename the conflict.
514 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
515 GV->takeName(ConflictGV);
516 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
517 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
519 GV->setName(Name); // Force the name back
523 /// copy additional attributes (those not needed to construct a GlobalValue)
524 /// from the SrcGV to the DestGV.
525 static void copyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) {
526 DestGV->copyAttributesFrom(SrcGV);
527 forceRenaming(DestGV, SrcGV->getName());
530 static bool isLessConstraining(GlobalValue::VisibilityTypes a,
531 GlobalValue::VisibilityTypes b) {
532 if (a == GlobalValue::HiddenVisibility)
534 if (b == GlobalValue::HiddenVisibility)
536 if (a == GlobalValue::ProtectedVisibility)
538 if (b == GlobalValue::ProtectedVisibility)
543 Value *ValueMaterializerTy::materializeValueFor(Value *V) {
544 Function *SF = dyn_cast<Function>(V);
548 Function *DF = Function::Create(TypeMap.get(SF->getFunctionType()),
549 SF->getLinkage(), SF->getName(), DstM);
550 copyGVAttributes(DF, SF);
552 if (Comdat *SC = SF->getComdat()) {
553 Comdat *DC = DstM->getOrInsertComdat(SC->getName());
557 LazilyLinkFunctions.push_back(SF);
561 bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName,
562 const GlobalVariable *&GVar) {
563 const GlobalValue *GVal = M->getNamedValue(ComdatName);
564 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
565 GVal = GA->getBaseObject();
567 // We cannot resolve the size of the aliasee yet.
568 return emitError("Linking COMDATs named '" + ComdatName +
569 "': COMDAT key involves incomputable alias size.");
572 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
575 "Linking COMDATs named '" + ComdatName +
576 "': GlobalVariable required for data dependent selection!");
581 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
582 Comdat::SelectionKind Src,
583 Comdat::SelectionKind Dst,
584 Comdat::SelectionKind &Result,
586 // The ability to mix Comdat::SelectionKind::Any with
587 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
588 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
589 Dst == Comdat::SelectionKind::Largest;
590 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
591 Src == Comdat::SelectionKind::Largest;
592 if (DstAnyOrLargest && SrcAnyOrLargest) {
593 if (Dst == Comdat::SelectionKind::Largest ||
594 Src == Comdat::SelectionKind::Largest)
595 Result = Comdat::SelectionKind::Largest;
597 Result = Comdat::SelectionKind::Any;
598 } else if (Src == Dst) {
601 return emitError("Linking COMDATs named '" + ComdatName +
602 "': invalid selection kinds!");
606 case Comdat::SelectionKind::Any:
610 case Comdat::SelectionKind::NoDuplicates:
611 return emitError("Linking COMDATs named '" + ComdatName +
612 "': noduplicates has been violated!");
613 case Comdat::SelectionKind::ExactMatch:
614 case Comdat::SelectionKind::Largest:
615 case Comdat::SelectionKind::SameSize: {
616 const GlobalVariable *DstGV;
617 const GlobalVariable *SrcGV;
618 if (getComdatLeader(DstM, ComdatName, DstGV) ||
619 getComdatLeader(SrcM, ComdatName, SrcGV))
622 const DataLayout *DstDL = DstM->getDataLayout();
623 const DataLayout *SrcDL = SrcM->getDataLayout();
624 if (!DstDL || !SrcDL) {
626 "Linking COMDATs named '" + ComdatName +
627 "': can't do size dependent selection without DataLayout!");
630 DstDL->getTypeAllocSize(DstGV->getType()->getPointerElementType());
632 SrcDL->getTypeAllocSize(SrcGV->getType()->getPointerElementType());
633 if (Result == Comdat::SelectionKind::ExactMatch) {
634 if (SrcGV->getInitializer() != DstGV->getInitializer())
635 return emitError("Linking COMDATs named '" + ComdatName +
636 "': ExactMatch violated!");
638 } else if (Result == Comdat::SelectionKind::Largest) {
639 LinkFromSrc = SrcSize > DstSize;
640 } else if (Result == Comdat::SelectionKind::SameSize) {
641 if (SrcSize != DstSize)
642 return emitError("Linking COMDATs named '" + ComdatName +
643 "': SameSize violated!");
646 llvm_unreachable("unknown selection kind");
655 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
656 Comdat::SelectionKind &Result,
658 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
659 StringRef ComdatName = SrcC->getName();
660 Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable();
661 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
663 if (DstCI == ComdatSymTab.end()) {
664 // Use the comdat if it is only available in one of the modules.
670 const Comdat *DstC = &DstCI->second;
671 Comdat::SelectionKind DSK = DstC->getSelectionKind();
672 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
676 bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
677 const GlobalValue &Dest,
678 const GlobalValue &Src) {
679 // We always have to add Src if it has appending linkage.
680 if (Src.hasAppendingLinkage()) {
685 bool SrcIsDeclaration = Src.isDeclarationForLinker();
686 bool DestIsDeclaration = Dest.isDeclarationForLinker();
688 if (SrcIsDeclaration) {
689 // If Src is external or if both Src & Dest are external.. Just link the
690 // external globals, we aren't adding anything.
691 if (Src.hasDLLImportStorageClass()) {
692 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
693 LinkFromSrc = DestIsDeclaration;
696 // If the Dest is weak, use the source linkage.
697 LinkFromSrc = Dest.hasExternalWeakLinkage();
701 if (DestIsDeclaration) {
702 // If Dest is external but Src is not:
707 if (Src.hasCommonLinkage()) {
708 if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
713 if (!Dest.hasCommonLinkage()) {
718 // FIXME: Make datalayout mandatory and just use getDataLayout().
719 DataLayout DL(Dest.getParent());
721 uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
722 uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
723 LinkFromSrc = SrcSize > DestSize;
727 if (Src.isWeakForLinker()) {
728 assert(!Dest.hasExternalWeakLinkage());
729 assert(!Dest.hasAvailableExternallyLinkage());
731 if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
740 if (Dest.isWeakForLinker()) {
741 assert(Src.hasExternalLinkage());
746 assert(!Src.hasExternalWeakLinkage());
747 assert(!Dest.hasExternalWeakLinkage());
748 assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
749 "Unexpected linkage type!");
750 return emitError("Linking globals named '" + Src.getName() +
751 "': symbol multiply defined!");
754 /// Loop over all of the linked values to compute type mappings. For example,
755 /// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct
756 /// types 'Foo' but one got renamed when the module was loaded into the same
758 void ModuleLinker::computeTypeMapping() {
759 for (GlobalValue &SGV : SrcM->globals()) {
760 GlobalValue *DGV = getLinkedToGlobal(&SGV);
764 if (!DGV->hasAppendingLinkage() || !SGV.hasAppendingLinkage()) {
765 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
769 // Unify the element type of appending arrays.
770 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
771 ArrayType *SAT = cast<ArrayType>(SGV.getType()->getElementType());
772 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
775 for (GlobalValue &SGV : *SrcM) {
776 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
777 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
780 for (GlobalValue &SGV : SrcM->aliases()) {
781 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
782 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
785 // Incorporate types by name, scanning all the types in the source module.
786 // At this point, the destination module may have a type "%foo = { i32 }" for
787 // example. When the source module got loaded into the same LLVMContext, if
788 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
789 std::vector<StructType *> Types = SrcM->getIdentifiedStructTypes();
790 for (StructType *ST : Types) {
794 // Check to see if there is a dot in the name followed by a digit.
795 size_t DotPos = ST->getName().rfind('.');
796 if (DotPos == 0 || DotPos == StringRef::npos ||
797 ST->getName().back() == '.' ||
798 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos + 1])))
801 // Check to see if the destination module has a struct with the prefix name.
802 StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos));
806 // Don't use it if this actually came from the source module. They're in
807 // the same LLVMContext after all. Also don't use it unless the type is
808 // actually used in the destination module. This can happen in situations
813 // %Z = type { %A } %B = type { %C.1 }
814 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
815 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
816 // %C = type { i8* } %B.3 = type { %C.1 }
818 // When we link Module B with Module A, the '%B' in Module B is
819 // used. However, that would then use '%C.1'. But when we process '%C.1',
820 // we prefer to take the '%C' version. So we are then left with both
821 // '%C.1' and '%C' being used for the same types. This leads to some
822 // variables using one type and some using the other.
823 if (TypeMap.DstStructTypesSet.hasType(DST))
824 TypeMap.addTypeMapping(DST, ST);
827 // Now that we have discovered all of the type equivalences, get a body for
828 // any 'opaque' types in the dest module that are now resolved.
829 TypeMap.linkDefinedTypeBodies();
832 static void upgradeGlobalArray(GlobalVariable *GV) {
833 ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
834 StructType *OldTy = cast<StructType>(ATy->getElementType());
835 assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
837 // Get the upgraded 3 element type.
838 PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
839 Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
841 StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
843 // Build new constants with a null third field filled in.
844 Constant *OldInitC = GV->getInitializer();
845 ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
846 if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
847 // Invalid initializer; give up.
849 std::vector<Constant *> Initializers;
850 if (OldInit && OldInit->getNumOperands()) {
851 Value *Null = Constant::getNullValue(VoidPtrTy);
852 for (Use &U : OldInit->operands()) {
853 ConstantStruct *Init = cast<ConstantStruct>(U.get());
854 Initializers.push_back(ConstantStruct::get(
855 NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
858 assert(Initializers.size() == ATy->getNumElements() &&
859 "Failed to copy all array elements");
861 // Replace the old GV with a new one.
862 ATy = ArrayType::get(NewTy, Initializers.size());
863 Constant *NewInit = ConstantArray::get(ATy, Initializers);
864 GlobalVariable *NewGV = new GlobalVariable(
865 *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
866 GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
867 GV->isExternallyInitialized());
868 NewGV->copyAttributesFrom(GV);
870 assert(GV->use_empty() && "program cannot use initializer list");
871 GV->eraseFromParent();
874 void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
875 // Look for the global arrays.
876 auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM->getNamedValue(Name));
879 auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM->getNamedValue(Name));
883 // Check if the types already match.
884 auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
886 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
890 // Grab the element types. We can only upgrade an array of a two-field
891 // struct. Only bother if the other one has three-fields.
892 auto *DstEltTy = cast<StructType>(DstTy->getElementType());
893 auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
894 if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
895 upgradeGlobalArray(DstGV);
898 if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
899 upgradeGlobalArray(SrcGV);
901 // We can't upgrade any other differences.
904 void ModuleLinker::upgradeMismatchedGlobals() {
905 upgradeMismatchedGlobalArray("llvm.global_ctors");
906 upgradeMismatchedGlobalArray("llvm.global_dtors");
909 /// If there were any appending global variables, link them together now.
910 /// Return true on error.
911 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
912 const GlobalVariable *SrcGV) {
914 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
915 return emitError("Linking globals named '" + SrcGV->getName() +
916 "': can only link appending global with another appending global!");
918 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
920 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
921 Type *EltTy = DstTy->getElementType();
923 // Check to see that they two arrays agree on type.
924 if (EltTy != SrcTy->getElementType())
925 return emitError("Appending variables with different element types!");
926 if (DstGV->isConstant() != SrcGV->isConstant())
927 return emitError("Appending variables linked with different const'ness!");
929 if (DstGV->getAlignment() != SrcGV->getAlignment())
931 "Appending variables with different alignment need to be linked!");
933 if (DstGV->getVisibility() != SrcGV->getVisibility())
935 "Appending variables with different visibility need to be linked!");
937 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
939 "Appending variables with different unnamed_addr need to be linked!");
941 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
943 "Appending variables with different section name need to be linked!");
945 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements();
946 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
948 // Create the new global variable.
950 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(),
951 DstGV->getLinkage(), /*init*/nullptr, /*name*/"", DstGV,
952 DstGV->getThreadLocalMode(),
953 DstGV->getType()->getAddressSpace());
955 // Propagate alignment, visibility and section info.
956 copyGVAttributes(NG, DstGV);
958 AppendingVarInfo AVI;
960 AVI.DstInit = DstGV->getInitializer();
961 AVI.SrcInit = SrcGV->getInitializer();
962 AppendingVars.push_back(AVI);
964 // Replace any uses of the two global variables with uses of the new
966 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
968 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
969 DstGV->eraseFromParent();
971 // Track the source variable so we don't try to link it.
972 DoNotLinkFromSource.insert(SrcGV);
977 bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) {
978 GlobalValue *DGV = getLinkedToGlobal(SGV);
980 // Handle the ultra special appending linkage case first.
981 if (DGV && DGV->hasAppendingLinkage())
982 return linkAppendingVarProto(cast<GlobalVariable>(DGV),
983 cast<GlobalVariable>(SGV));
985 bool LinkFromSrc = true;
987 GlobalValue::VisibilityTypes Visibility = SGV->getVisibility();
988 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
990 if (const Comdat *SC = SGV->getComdat()) {
991 Comdat::SelectionKind SK;
992 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
993 C = DstM->getOrInsertComdat(SC->getName());
994 C->setSelectionKind(SK);
996 if (shouldLinkFromSource(LinkFromSrc, *DGV, *SGV))
1001 // Track the source global so that we don't attempt to copy it over when
1002 // processing global initializers.
1003 DoNotLinkFromSource.insert(SGV);
1006 // Make sure to remember this mapping.
1008 ConstantExpr::getBitCast(DGV, TypeMap.get(SGV->getType()));
1012 Visibility = isLessConstraining(Visibility, DGV->getVisibility())
1013 ? DGV->getVisibility()
1015 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1018 if (!LinkFromSrc && !DGV)
1025 if (auto *SGVar = dyn_cast<GlobalVariable>(SGV))
1026 NewGV = linkGlobalVariableProto(SGVar, DGV);
1027 else if (auto *SF = dyn_cast<Function>(SGV))
1028 NewGV = linkFunctionProto(SF, DGV);
1030 NewGV = linkGlobalAliasProto(cast<GlobalAlias>(SGV), DGV);
1037 copyGVAttributes(NewGV, SGV);
1039 NewGV->setUnnamedAddr(HasUnnamedAddr);
1040 NewGV->setVisibility(Visibility);
1042 if (auto *NewGO = dyn_cast<GlobalObject>(NewGV)) {
1044 NewGO->setComdat(C);
1046 if (DGV && DGV->hasCommonLinkage() && SGV->hasCommonLinkage())
1047 NewGO->setAlignment(std::max(DGV->getAlignment(), SGV->getAlignment()));
1050 if (auto *NewGVar = dyn_cast<GlobalVariable>(NewGV)) {
1051 auto *DGVar = dyn_cast_or_null<GlobalVariable>(DGV);
1052 auto *SGVar = dyn_cast<GlobalVariable>(SGV);
1053 if (DGVar && SGVar && DGVar->isDeclaration() && SGVar->isDeclaration() &&
1054 (!DGVar->isConstant() || !SGVar->isConstant()))
1055 NewGVar->setConstant(false);
1058 // Make sure to remember this mapping.
1061 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewGV, DGV->getType()));
1062 DGV->eraseFromParent();
1064 ValueMap[SGV] = NewGV;
1070 /// Loop through the global variables in the src module and merge them into the
1072 GlobalValue *ModuleLinker::linkGlobalVariableProto(const GlobalVariable *SGVar,
1074 // No linking to be performed or linking from the source: simply create an
1075 // identical version of the symbol over in the dest module... the
1076 // initializer will be filled in later by LinkGlobalInits.
1077 GlobalVariable *NewDGV = new GlobalVariable(
1078 *DstM, TypeMap.get(SGVar->getType()->getElementType()),
1079 SGVar->isConstant(), SGVar->getLinkage(), /*init*/ nullptr,
1080 SGVar->getName(), /*insertbefore*/ nullptr, SGVar->getThreadLocalMode(),
1081 SGVar->getType()->getAddressSpace());
1086 /// Link the function in the source module into the destination module if
1087 /// needed, setting up mapping information.
1088 GlobalValue *ModuleLinker::linkFunctionProto(const Function *SF,
1090 // If the function is to be lazily linked, don't create it just yet.
1091 // The ValueMaterializerTy will deal with creating it if it's used.
1092 if (!DGV && (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() ||
1093 SF->hasAvailableExternallyLinkage())) {
1094 DoNotLinkFromSource.insert(SF);
1098 // If there is no linkage to be performed or we are linking from the source,
1100 return Function::Create(TypeMap.get(SF->getFunctionType()), SF->getLinkage(),
1101 SF->getName(), DstM);
1104 /// Set up prototypes for any aliases that come over from the source module.
1105 GlobalValue *ModuleLinker::linkGlobalAliasProto(const GlobalAlias *SGA,
1107 // If there is no linkage to be performed or we're linking from the source,
1109 auto *PTy = cast<PointerType>(TypeMap.get(SGA->getType()));
1110 return GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(),
1111 SGA->getLinkage(), SGA->getName(), DstM);
1114 static void getArrayElements(const Constant *C,
1115 SmallVectorImpl<Constant *> &Dest) {
1116 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1118 for (unsigned i = 0; i != NumElements; ++i)
1119 Dest.push_back(C->getAggregateElement(i));
1122 void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) {
1123 // Merge the initializer.
1124 SmallVector<Constant *, 16> DstElements;
1125 getArrayElements(AVI.DstInit, DstElements);
1127 SmallVector<Constant *, 16> SrcElements;
1128 getArrayElements(AVI.SrcInit, SrcElements);
1130 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
1132 StringRef Name = AVI.NewGV->getName();
1133 bool IsNewStructor =
1134 (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
1135 cast<StructType>(NewType->getElementType())->getNumElements() == 3;
1137 for (auto *V : SrcElements) {
1138 if (IsNewStructor) {
1139 Constant *Key = V->getAggregateElement(2);
1140 if (DoNotLinkFromSource.count(Key))
1143 DstElements.push_back(
1144 MapValue(V, ValueMap, RF_None, &TypeMap, &ValMaterializer));
1146 if (IsNewStructor) {
1147 NewType = ArrayType::get(NewType->getElementType(), DstElements.size());
1148 AVI.NewGV->mutateType(PointerType::get(NewType, 0));
1151 AVI.NewGV->setInitializer(ConstantArray::get(NewType, DstElements));
1154 /// Update the initializers in the Dest module now that all globals that may be
1155 /// referenced are in Dest.
1156 void ModuleLinker::linkGlobalInits() {
1157 // Loop over all of the globals in the src module, mapping them over as we go
1158 for (Module::const_global_iterator I = SrcM->global_begin(),
1159 E = SrcM->global_end(); I != E; ++I) {
1161 // Only process initialized GV's or ones not already in dest.
1162 if (!I->hasInitializer() || DoNotLinkFromSource.count(I)) continue;
1164 // Grab destination global variable.
1165 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[I]);
1166 // Figure out what the initializer looks like in the dest module.
1167 DGV->setInitializer(MapValue(I->getInitializer(), ValueMap,
1168 RF_None, &TypeMap, &ValMaterializer));
1172 /// Copy the source function over into the dest function and fix up references
1173 /// to values. At this point we know that Dest is an external function, and
1174 /// that Src is not.
1175 void ModuleLinker::linkFunctionBody(Function *Dst, Function *Src) {
1176 assert(Src && Dst && Dst->isDeclaration() && !Src->isDeclaration());
1178 // Go through and convert function arguments over, remembering the mapping.
1179 Function::arg_iterator DI = Dst->arg_begin();
1180 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1181 I != E; ++I, ++DI) {
1182 DI->setName(I->getName()); // Copy the name over.
1184 // Add a mapping to our mapping.
1188 // Splice the body of the source function into the dest function.
1189 Dst->getBasicBlockList().splice(Dst->end(), Src->getBasicBlockList());
1191 // At this point, all of the instructions and values of the function are now
1192 // copied over. The only problem is that they are still referencing values in
1193 // the Source function as operands. Loop through all of the operands of the
1194 // functions and patch them up to point to the local versions.
1195 for (Function::iterator BB = Dst->begin(), BE = Dst->end(); BB != BE; ++BB)
1196 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
1197 RemapInstruction(I, ValueMap, RF_IgnoreMissingEntries, &TypeMap,
1200 // There is no need to map the arguments anymore.
1201 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1207 /// Insert all of the aliases in Src into the Dest module.
1208 void ModuleLinker::linkAliasBodies() {
1209 for (Module::alias_iterator I = SrcM->alias_begin(), E = SrcM->alias_end();
1211 if (DoNotLinkFromSource.count(I))
1213 if (Constant *Aliasee = I->getAliasee()) {
1214 GlobalAlias *DA = cast<GlobalAlias>(ValueMap[I]);
1216 MapValue(Aliasee, ValueMap, RF_None, &TypeMap, &ValMaterializer);
1217 DA->setAliasee(Val);
1222 /// Insert all of the named MDNodes in Src into the Dest module.
1223 void ModuleLinker::linkNamedMDNodes() {
1224 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1225 for (Module::const_named_metadata_iterator I = SrcM->named_metadata_begin(),
1226 E = SrcM->named_metadata_end(); I != E; ++I) {
1227 // Don't link module flags here. Do them separately.
1228 if (&*I == SrcModFlags) continue;
1229 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(I->getName());
1230 // Add Src elements into Dest node.
1231 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
1232 DestNMD->addOperand(MapValue(I->getOperand(i), ValueMap,
1233 RF_None, &TypeMap, &ValMaterializer));
1237 /// Merge the linker flags in Src into the Dest module.
1238 bool ModuleLinker::linkModuleFlagsMetadata() {
1239 // If the source module has no module flags, we are done.
1240 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1241 if (!SrcModFlags) return false;
1243 // If the destination module doesn't have module flags yet, then just copy
1244 // over the source module's flags.
1245 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
1246 if (DstModFlags->getNumOperands() == 0) {
1247 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1248 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1253 // First build a map of the existing module flags and requirements.
1254 DenseMap<MDString*, MDNode*> Flags;
1255 SmallSetVector<MDNode*, 16> Requirements;
1256 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1257 MDNode *Op = DstModFlags->getOperand(I);
1258 ConstantInt *Behavior = cast<ConstantInt>(Op->getOperand(0));
1259 MDString *ID = cast<MDString>(Op->getOperand(1));
1261 if (Behavior->getZExtValue() == Module::Require) {
1262 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1268 // Merge in the flags from the source module, and also collect its set of
1270 bool HasErr = false;
1271 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1272 MDNode *SrcOp = SrcModFlags->getOperand(I);
1273 ConstantInt *SrcBehavior = cast<ConstantInt>(SrcOp->getOperand(0));
1274 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1275 MDNode *DstOp = Flags.lookup(ID);
1276 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1278 // If this is a requirement, add it and continue.
1279 if (SrcBehaviorValue == Module::Require) {
1280 // If the destination module does not already have this requirement, add
1282 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1283 DstModFlags->addOperand(SrcOp);
1288 // If there is no existing flag with this ID, just add it.
1291 DstModFlags->addOperand(SrcOp);
1295 // Otherwise, perform a merge.
1296 ConstantInt *DstBehavior = cast<ConstantInt>(DstOp->getOperand(0));
1297 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1299 // If either flag has override behavior, handle it first.
1300 if (DstBehaviorValue == Module::Override) {
1301 // Diagnose inconsistent flags which both have override behavior.
1302 if (SrcBehaviorValue == Module::Override &&
1303 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1304 HasErr |= emitError("linking module flags '" + ID->getString() +
1305 "': IDs have conflicting override values");
1308 } else if (SrcBehaviorValue == Module::Override) {
1309 // Update the destination flag to that of the source.
1310 DstOp->replaceOperandWith(0, SrcBehavior);
1311 DstOp->replaceOperandWith(2, SrcOp->getOperand(2));
1315 // Diagnose inconsistent merge behavior types.
1316 if (SrcBehaviorValue != DstBehaviorValue) {
1317 HasErr |= emitError("linking module flags '" + ID->getString() +
1318 "': IDs have conflicting behaviors");
1322 // Perform the merge for standard behavior types.
1323 switch (SrcBehaviorValue) {
1324 case Module::Require:
1325 case Module::Override: llvm_unreachable("not possible");
1326 case Module::Error: {
1327 // Emit an error if the values differ.
1328 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1329 HasErr |= emitError("linking module flags '" + ID->getString() +
1330 "': IDs have conflicting values");
1334 case Module::Warning: {
1335 // Emit a warning if the values differ.
1336 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1337 emitWarning("linking module flags '" + ID->getString() +
1338 "': IDs have conflicting values");
1342 case Module::Append: {
1343 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1344 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1345 unsigned NumOps = DstValue->getNumOperands() + SrcValue->getNumOperands();
1346 Value **VP, **Values = VP = new Value*[NumOps];
1347 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i, ++VP)
1348 *VP = DstValue->getOperand(i);
1349 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i, ++VP)
1350 *VP = SrcValue->getOperand(i);
1351 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1352 ArrayRef<Value*>(Values,
1357 case Module::AppendUnique: {
1358 SmallSetVector<Value*, 16> Elts;
1359 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1360 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1361 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i)
1362 Elts.insert(DstValue->getOperand(i));
1363 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i)
1364 Elts.insert(SrcValue->getOperand(i));
1365 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1366 ArrayRef<Value*>(Elts.begin(),
1373 // Check all of the requirements.
1374 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1375 MDNode *Requirement = Requirements[I];
1376 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1377 Value *ReqValue = Requirement->getOperand(1);
1379 MDNode *Op = Flags[Flag];
1380 if (!Op || Op->getOperand(2) != ReqValue) {
1381 HasErr |= emitError("linking module flags '" + Flag->getString() +
1382 "': does not have the required value");
1390 bool ModuleLinker::run() {
1391 assert(DstM && "Null destination module");
1392 assert(SrcM && "Null source module");
1394 // Inherit the target data from the source module if the destination module
1395 // doesn't have one already.
1396 if (!DstM->getDataLayout() && SrcM->getDataLayout())
1397 DstM->setDataLayout(SrcM->getDataLayout());
1399 // Copy the target triple from the source to dest if the dest's is empty.
1400 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
1401 DstM->setTargetTriple(SrcM->getTargetTriple());
1403 if (SrcM->getDataLayout() && DstM->getDataLayout() &&
1404 *SrcM->getDataLayout() != *DstM->getDataLayout()) {
1405 emitWarning("Linking two modules of different data layouts: '" +
1406 SrcM->getModuleIdentifier() + "' is '" +
1407 SrcM->getDataLayoutStr() + "' whereas '" +
1408 DstM->getModuleIdentifier() + "' is '" +
1409 DstM->getDataLayoutStr() + "'\n");
1411 if (!SrcM->getTargetTriple().empty() &&
1412 DstM->getTargetTriple() != SrcM->getTargetTriple()) {
1413 emitWarning("Linking two modules of different target triples: " +
1414 SrcM->getModuleIdentifier() + "' is '" +
1415 SrcM->getTargetTriple() + "' whereas '" +
1416 DstM->getModuleIdentifier() + "' is '" +
1417 DstM->getTargetTriple() + "'\n");
1420 // Append the module inline asm string.
1421 if (!SrcM->getModuleInlineAsm().empty()) {
1422 if (DstM->getModuleInlineAsm().empty())
1423 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
1425 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
1426 SrcM->getModuleInlineAsm());
1429 // Loop over all of the linked values to compute type mappings.
1430 computeTypeMapping();
1432 ComdatsChosen.clear();
1433 for (const auto &SMEC : SrcM->getComdatSymbolTable()) {
1434 const Comdat &C = SMEC.getValue();
1435 if (ComdatsChosen.count(&C))
1437 Comdat::SelectionKind SK;
1439 if (getComdatResult(&C, SK, LinkFromSrc))
1441 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1444 // Upgrade mismatched global arrays.
1445 upgradeMismatchedGlobals();
1447 // Insert all of the globals in src into the DstM module... without linking
1448 // initializers (which could refer to functions not yet mapped over).
1449 for (Module::global_iterator I = SrcM->global_begin(),
1450 E = SrcM->global_end(); I != E; ++I)
1451 if (linkGlobalValueProto(I))
1454 // Link the functions together between the two modules, without doing function
1455 // bodies... this just adds external function prototypes to the DstM
1456 // function... We do this so that when we begin processing function bodies,
1457 // all of the global values that may be referenced are available in our
1459 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I)
1460 if (linkGlobalValueProto(I))
1463 // If there were any aliases, link them now.
1464 for (Module::alias_iterator I = SrcM->alias_begin(),
1465 E = SrcM->alias_end(); I != E; ++I)
1466 if (linkGlobalValueProto(I))
1469 for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i)
1470 linkAppendingVarInit(AppendingVars[i]);
1472 // Link in the function bodies that are defined in the source module into
1474 for (Module::iterator SF = SrcM->begin(), E = SrcM->end(); SF != E; ++SF) {
1475 // Skip if not linking from source.
1476 if (DoNotLinkFromSource.count(SF)) continue;
1478 Function *DF = cast<Function>(ValueMap[SF]);
1480 // Link in the prefix data.
1481 if (SF->hasPrefixData())
1482 DF->setPrefixData(MapValue(
1483 SF->getPrefixData(), ValueMap, RF_None, &TypeMap, &ValMaterializer));
1485 // Link in the prologue data.
1486 if (SF->hasPrologueData())
1487 DF->setPrologueData(MapValue(
1488 SF->getPrologueData(), ValueMap, RF_None, &TypeMap, &ValMaterializer));
1490 // Materialize if needed.
1491 if (std::error_code EC = SF->materialize())
1492 return emitError(EC.message());
1494 // Skip if no body (function is external).
1495 if (SF->isDeclaration())
1498 linkFunctionBody(DF, SF);
1499 SF->Dematerialize();
1502 // Resolve all uses of aliases with aliasees.
1505 // Remap all of the named MDNodes in Src into the DstM module. We do this
1506 // after linking GlobalValues so that MDNodes that reference GlobalValues
1507 // are properly remapped.
1510 // Merge the module flags into the DstM module.
1511 if (linkModuleFlagsMetadata())
1514 // Update the initializers in the DstM module now that all globals that may
1515 // be referenced are in DstM.
1518 // Process vector of lazily linked in functions.
1519 bool LinkedInAnyFunctions;
1521 LinkedInAnyFunctions = false;
1523 for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(),
1524 E = LazilyLinkFunctions.end(); I != E; ++I) {
1529 Function *DF = cast<Function>(ValueMap[SF]);
1530 if (SF->hasPrefixData()) {
1531 // Link in the prefix data.
1532 DF->setPrefixData(MapValue(SF->getPrefixData(),
1539 // Materialize if needed.
1540 if (std::error_code EC = SF->materialize())
1541 return emitError(EC.message());
1543 // Skip if no body (function is external).
1544 if (SF->isDeclaration())
1547 // Erase from vector *before* the function body is linked - linkFunctionBody could
1549 LazilyLinkFunctions.erase(I);
1551 // Link in function body.
1552 linkFunctionBody(DF, SF);
1553 SF->Dematerialize();
1555 // Set flag to indicate we may have more functions to lazily link in
1556 // since we linked in a function.
1557 LinkedInAnyFunctions = true;
1560 } while (LinkedInAnyFunctions);
1565 Linker::StructTypeKeyInfo::KeyTy::KeyTy(ArrayRef<Type *> E, bool P)
1566 : ETypes(E), IsPacked(P) {}
1568 Linker::StructTypeKeyInfo::KeyTy::KeyTy(const StructType *ST)
1569 : ETypes(ST->elements()), IsPacked(ST->isPacked()) {}
1571 bool Linker::StructTypeKeyInfo::KeyTy::operator==(const KeyTy &That) const {
1572 if (IsPacked != That.IsPacked)
1574 if (ETypes != That.ETypes)
1579 bool Linker::StructTypeKeyInfo::KeyTy::operator!=(const KeyTy &That) const {
1580 return !this->operator==(That);
1583 StructType *Linker::StructTypeKeyInfo::getEmptyKey() {
1584 return DenseMapInfo<StructType *>::getEmptyKey();
1587 StructType *Linker::StructTypeKeyInfo::getTombstoneKey() {
1588 return DenseMapInfo<StructType *>::getTombstoneKey();
1591 unsigned Linker::StructTypeKeyInfo::getHashValue(const KeyTy &Key) {
1592 return hash_combine(hash_combine_range(Key.ETypes.begin(), Key.ETypes.end()),
1596 unsigned Linker::StructTypeKeyInfo::getHashValue(const StructType *ST) {
1597 return getHashValue(KeyTy(ST));
1600 bool Linker::StructTypeKeyInfo::isEqual(const KeyTy &LHS,
1601 const StructType *RHS) {
1602 if (RHS == getEmptyKey() || RHS == getTombstoneKey())
1604 return LHS == KeyTy(RHS);
1607 bool Linker::StructTypeKeyInfo::isEqual(const StructType *LHS,
1608 const StructType *RHS) {
1609 if (RHS == getEmptyKey())
1610 return LHS == getEmptyKey();
1612 if (RHS == getTombstoneKey())
1613 return LHS == getTombstoneKey();
1615 return KeyTy(LHS) == KeyTy(RHS);
1618 void Linker::IdentifiedStructTypeSet::addNonOpaque(StructType *Ty) {
1619 assert(!Ty->isOpaque());
1620 bool &Entry = NonOpaqueStructTypes[Ty];
1624 void Linker::IdentifiedStructTypeSet::addOpaque(StructType *Ty) {
1625 assert(Ty->isOpaque());
1626 OpaqueStructTypes.insert(Ty);
1630 Linker::IdentifiedStructTypeSet::findNonOpaque(ArrayRef<Type *> ETypes,
1632 Linker::StructTypeKeyInfo::KeyTy Key(ETypes, IsPacked);
1633 auto I = NonOpaqueStructTypes.find_as(Key);
1634 if (I == NonOpaqueStructTypes.end())
1639 bool Linker::IdentifiedStructTypeSet::hasType(StructType *Ty) {
1641 return OpaqueStructTypes.count(Ty);
1642 auto I = NonOpaqueStructTypes.find(Ty);
1643 if (I == NonOpaqueStructTypes.end())
1645 return I->first == Ty;
1648 void Linker::init(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
1649 this->Composite = M;
1650 this->DiagnosticHandler = DiagnosticHandler;
1652 TypeFinder StructTypes;
1653 StructTypes.run(*M, true);
1654 for (StructType *Ty : StructTypes) {
1656 IdentifiedStructTypes.addOpaque(Ty);
1658 IdentifiedStructTypes.addNonOpaque(Ty);
1662 Linker::Linker(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
1663 init(M, DiagnosticHandler);
1666 Linker::Linker(Module *M) {
1667 init(M, [this](const DiagnosticInfo &DI) {
1668 Composite->getContext().diagnose(DI);
1675 void Linker::deleteModule() {
1677 Composite = nullptr;
1680 bool Linker::linkInModule(Module *Src) {
1681 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,
1683 return TheLinker.run();
1686 //===----------------------------------------------------------------------===//
1687 // LinkModules entrypoint.
1688 //===----------------------------------------------------------------------===//
1690 /// This function links two modules together, with the resulting Dest module
1691 /// modified to be the composite of the two input modules. If an error occurs,
1692 /// true is returned and ErrorMsg (if not null) is set to indicate the problem.
1693 /// Upon failure, the Dest module could be in a modified state, and shouldn't be
1694 /// relied on to be consistent.
1695 bool Linker::LinkModules(Module *Dest, Module *Src,
1696 DiagnosticHandlerFunction DiagnosticHandler) {
1697 Linker L(Dest, DiagnosticHandler);
1698 return L.linkInModule(Src);
1701 bool Linker::LinkModules(Module *Dest, Module *Src) {
1703 return L.linkInModule(Src);
1706 //===----------------------------------------------------------------------===//
1708 //===----------------------------------------------------------------------===//
1710 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
1711 LLVMLinkerMode Mode, char **OutMessages) {
1712 Module *D = unwrap(Dest);
1713 std::string Message;
1714 raw_string_ostream Stream(Message);
1715 DiagnosticPrinterRawOStream DP(Stream);
1717 LLVMBool Result = Linker::LinkModules(
1718 D, unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); });
1720 if (OutMessages && Result)
1721 *OutMessages = strdup(Message.c_str());