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/SetVector.h"
17 #include "llvm/ADT/SmallString.h"
18 #include "llvm/ADT/Triple.h"
19 #include "llvm/IR/Constants.h"
20 #include "llvm/IR/DiagnosticInfo.h"
21 #include "llvm/IR/DiagnosticPrinter.h"
22 #include "llvm/IR/LLVMContext.h"
23 #include "llvm/IR/Module.h"
24 #include "llvm/IR/TypeFinder.h"
25 #include "llvm/Transforms/Utils/Cloning.h"
28 //===----------------------------------------------------------------------===//
29 // TypeMap implementation.
30 //===----------------------------------------------------------------------===//
33 class TypeMapTy : public ValueMapTypeRemapper {
34 /// This is a mapping from a source type to a destination type to use.
35 DenseMap<Type *, Type *> MappedTypes;
37 /// When checking to see if two subgraphs are isomorphic, we speculatively
38 /// add types to MappedTypes, but keep track of them here in case we need to
40 SmallVector<Type *, 16> SpeculativeTypes;
42 SmallVector<StructType *, 16> SpeculativeDstOpaqueTypes;
44 /// This is a list of non-opaque structs in the source module that are mapped
45 /// to an opaque struct in the destination module.
46 SmallVector<StructType *, 16> SrcDefinitionsToResolve;
48 /// This is the set of opaque types in the destination modules who are
49 /// getting a body from the source module.
50 SmallPtrSet<StructType *, 16> DstResolvedOpaqueTypes;
53 TypeMapTy(Linker::IdentifiedStructTypeSet &DstStructTypesSet)
54 : DstStructTypesSet(DstStructTypesSet) {}
56 Linker::IdentifiedStructTypeSet &DstStructTypesSet;
57 /// Indicate that the specified type in the destination module is conceptually
58 /// equivalent to the specified type in the source module.
59 void addTypeMapping(Type *DstTy, Type *SrcTy);
61 /// Produce a body for an opaque type in the dest module from a type
62 /// definition in the source module.
63 void linkDefinedTypeBodies();
65 /// Return the mapped type to use for the specified input type from the
67 Type *get(Type *SrcTy);
68 Type *get(Type *SrcTy, SmallPtrSet<StructType *, 8> &Visited);
70 void finishType(StructType *DTy, StructType *STy, ArrayRef<Type *> ETypes);
72 FunctionType *get(FunctionType *T) {
73 return cast<FunctionType>(get((Type *)T));
76 /// Dump out the type map for debugging purposes.
78 for (auto &Pair : MappedTypes) {
79 dbgs() << "TypeMap: ";
80 Pair.first->print(dbgs());
82 Pair.second->print(dbgs());
88 Type *remapType(Type *SrcTy) override { return get(SrcTy); }
90 bool areTypesIsomorphic(Type *DstTy, Type *SrcTy);
94 void TypeMapTy::addTypeMapping(Type *DstTy, Type *SrcTy) {
95 assert(SpeculativeTypes.empty());
96 assert(SpeculativeDstOpaqueTypes.empty());
98 // Check to see if these types are recursively isomorphic and establish a
99 // mapping between them if so.
100 if (!areTypesIsomorphic(DstTy, SrcTy)) {
101 // Oops, they aren't isomorphic. Just discard this request by rolling out
102 // any speculative mappings we've established.
103 for (Type *Ty : SpeculativeTypes)
104 MappedTypes.erase(Ty);
106 SrcDefinitionsToResolve.resize(SrcDefinitionsToResolve.size() -
107 SpeculativeDstOpaqueTypes.size());
108 for (StructType *Ty : SpeculativeDstOpaqueTypes)
109 DstResolvedOpaqueTypes.erase(Ty);
111 for (Type *Ty : SpeculativeTypes)
112 if (auto *STy = dyn_cast<StructType>(Ty))
116 SpeculativeTypes.clear();
117 SpeculativeDstOpaqueTypes.clear();
120 /// Recursively walk this pair of types, returning true if they are isomorphic,
121 /// false if they are not.
122 bool TypeMapTy::areTypesIsomorphic(Type *DstTy, Type *SrcTy) {
123 // Two types with differing kinds are clearly not isomorphic.
124 if (DstTy->getTypeID() != SrcTy->getTypeID())
127 // If we have an entry in the MappedTypes table, then we have our answer.
128 Type *&Entry = MappedTypes[SrcTy];
130 return Entry == DstTy;
132 // Two identical types are clearly isomorphic. Remember this
133 // non-speculatively.
134 if (DstTy == SrcTy) {
139 // Okay, we have two types with identical kinds that we haven't seen before.
141 // If this is an opaque struct type, special case it.
142 if (StructType *SSTy = dyn_cast<StructType>(SrcTy)) {
143 // Mapping an opaque type to any struct, just keep the dest struct.
144 if (SSTy->isOpaque()) {
146 SpeculativeTypes.push_back(SrcTy);
150 // Mapping a non-opaque source type to an opaque dest. If this is the first
151 // type that we're mapping onto this destination type then we succeed. Keep
152 // the dest, but fill it in later. If this is the second (different) type
153 // that we're trying to map onto the same opaque type then we fail.
154 if (cast<StructType>(DstTy)->isOpaque()) {
155 // We can only map one source type onto the opaque destination type.
156 if (!DstResolvedOpaqueTypes.insert(cast<StructType>(DstTy)).second)
158 SrcDefinitionsToResolve.push_back(SSTy);
159 SpeculativeTypes.push_back(SrcTy);
160 SpeculativeDstOpaqueTypes.push_back(cast<StructType>(DstTy));
166 // If the number of subtypes disagree between the two types, then we fail.
167 if (SrcTy->getNumContainedTypes() != DstTy->getNumContainedTypes())
170 // Fail if any of the extra properties (e.g. array size) of the type disagree.
171 if (isa<IntegerType>(DstTy))
172 return false; // bitwidth disagrees.
173 if (PointerType *PT = dyn_cast<PointerType>(DstTy)) {
174 if (PT->getAddressSpace() != cast<PointerType>(SrcTy)->getAddressSpace())
177 } else if (FunctionType *FT = dyn_cast<FunctionType>(DstTy)) {
178 if (FT->isVarArg() != cast<FunctionType>(SrcTy)->isVarArg())
180 } else if (StructType *DSTy = dyn_cast<StructType>(DstTy)) {
181 StructType *SSTy = cast<StructType>(SrcTy);
182 if (DSTy->isLiteral() != SSTy->isLiteral() ||
183 DSTy->isPacked() != SSTy->isPacked())
185 } else if (ArrayType *DATy = dyn_cast<ArrayType>(DstTy)) {
186 if (DATy->getNumElements() != cast<ArrayType>(SrcTy)->getNumElements())
188 } else if (VectorType *DVTy = dyn_cast<VectorType>(DstTy)) {
189 if (DVTy->getNumElements() != cast<VectorType>(SrcTy)->getNumElements())
193 // Otherwise, we speculate that these two types will line up and recursively
194 // check the subelements.
196 SpeculativeTypes.push_back(SrcTy);
198 for (unsigned I = 0, E = SrcTy->getNumContainedTypes(); I != E; ++I)
199 if (!areTypesIsomorphic(DstTy->getContainedType(I),
200 SrcTy->getContainedType(I)))
203 // If everything seems to have lined up, then everything is great.
207 void TypeMapTy::linkDefinedTypeBodies() {
208 SmallVector<Type *, 16> Elements;
209 for (StructType *SrcSTy : SrcDefinitionsToResolve) {
210 StructType *DstSTy = cast<StructType>(MappedTypes[SrcSTy]);
211 assert(DstSTy->isOpaque());
213 // Map the body of the source type over to a new body for the dest type.
214 Elements.resize(SrcSTy->getNumElements());
215 for (unsigned I = 0, E = Elements.size(); I != E; ++I)
216 Elements[I] = get(SrcSTy->getElementType(I));
218 DstSTy->setBody(Elements, SrcSTy->isPacked());
219 DstStructTypesSet.switchToNonOpaque(DstSTy);
221 SrcDefinitionsToResolve.clear();
222 DstResolvedOpaqueTypes.clear();
225 void TypeMapTy::finishType(StructType *DTy, StructType *STy,
226 ArrayRef<Type *> ETypes) {
227 DTy->setBody(ETypes, STy->isPacked());
230 if (STy->hasName()) {
231 SmallString<16> TmpName = STy->getName();
233 DTy->setName(TmpName);
236 DstStructTypesSet.addNonOpaque(DTy);
239 Type *TypeMapTy::get(Type *Ty) {
240 SmallPtrSet<StructType *, 8> Visited;
241 return get(Ty, Visited);
244 Type *TypeMapTy::get(Type *Ty, SmallPtrSet<StructType *, 8> &Visited) {
245 // If we already have an entry for this type, return it.
246 Type **Entry = &MappedTypes[Ty];
250 // These are types that LLVM itself will unique.
251 bool IsUniqued = !isa<StructType>(Ty) || cast<StructType>(Ty)->isLiteral();
255 for (auto &Pair : MappedTypes) {
256 assert(!(Pair.first != Ty && Pair.second == Ty) &&
257 "mapping to a source type");
262 if (!IsUniqued && !Visited.insert(cast<StructType>(Ty)).second) {
263 StructType *DTy = StructType::create(Ty->getContext());
267 // If this is not a recursive type, then just map all of the elements and
268 // then rebuild the type from inside out.
269 SmallVector<Type *, 4> ElementTypes;
271 // If there are no element types to map, then the type is itself. This is
272 // true for the anonymous {} struct, things like 'float', integers, etc.
273 if (Ty->getNumContainedTypes() == 0 && IsUniqued)
276 // Remap all of the elements, keeping track of whether any of them change.
277 bool AnyChange = false;
278 ElementTypes.resize(Ty->getNumContainedTypes());
279 for (unsigned I = 0, E = Ty->getNumContainedTypes(); I != E; ++I) {
280 ElementTypes[I] = get(Ty->getContainedType(I), Visited);
281 AnyChange |= ElementTypes[I] != Ty->getContainedType(I);
284 // If we found our type while recursively processing stuff, just use it.
285 Entry = &MappedTypes[Ty];
287 if (auto *DTy = dyn_cast<StructType>(*Entry)) {
288 if (DTy->isOpaque()) {
289 auto *STy = cast<StructType>(Ty);
290 finishType(DTy, STy, ElementTypes);
296 // If all of the element types mapped directly over and the type is not
297 // a nomed struct, then the type is usable as-is.
298 if (!AnyChange && IsUniqued)
301 // Otherwise, rebuild a modified type.
302 switch (Ty->getTypeID()) {
304 llvm_unreachable("unknown derived type to remap");
305 case Type::ArrayTyID:
306 return *Entry = ArrayType::get(ElementTypes[0],
307 cast<ArrayType>(Ty)->getNumElements());
308 case Type::VectorTyID:
309 return *Entry = VectorType::get(ElementTypes[0],
310 cast<VectorType>(Ty)->getNumElements());
311 case Type::PointerTyID:
312 return *Entry = PointerType::get(ElementTypes[0],
313 cast<PointerType>(Ty)->getAddressSpace());
314 case Type::FunctionTyID:
315 return *Entry = FunctionType::get(ElementTypes[0],
316 makeArrayRef(ElementTypes).slice(1),
317 cast<FunctionType>(Ty)->isVarArg());
318 case Type::StructTyID: {
319 auto *STy = cast<StructType>(Ty);
320 bool IsPacked = STy->isPacked();
322 return *Entry = StructType::get(Ty->getContext(), ElementTypes, IsPacked);
324 // If the type is opaque, we can just use it directly.
325 if (STy->isOpaque()) {
326 DstStructTypesSet.addOpaque(STy);
330 if (StructType *OldT =
331 DstStructTypesSet.findNonOpaque(ElementTypes, IsPacked)) {
333 return *Entry = OldT;
337 DstStructTypesSet.addNonOpaque(STy);
341 StructType *DTy = StructType::create(Ty->getContext());
342 finishType(DTy, STy, ElementTypes);
348 //===----------------------------------------------------------------------===//
349 // ModuleLinker implementation.
350 //===----------------------------------------------------------------------===//
355 /// Creates prototypes for functions that are lazily linked on the fly. This
356 /// speeds up linking for modules with many/ lazily linked functions of which
358 class ValueMaterializerTy final : public ValueMaterializer {
359 ModuleLinker *ModLinker;
362 ValueMaterializerTy(ModuleLinker *ModLinker) : ModLinker(ModLinker) {}
364 Value *materializeDeclFor(Value *V) override;
365 void materializeInitFor(GlobalValue *New, GlobalValue *Old) override;
368 class LinkDiagnosticInfo : public DiagnosticInfo {
372 LinkDiagnosticInfo(DiagnosticSeverity Severity, const Twine &Msg);
373 void print(DiagnosticPrinter &DP) const override;
375 LinkDiagnosticInfo::LinkDiagnosticInfo(DiagnosticSeverity Severity,
377 : DiagnosticInfo(DK_Linker, Severity), Msg(Msg) {}
378 void LinkDiagnosticInfo::print(DiagnosticPrinter &DP) const { DP << Msg; }
380 /// This is an implementation class for the LinkModules function, which is the
381 /// entrypoint for this file.
387 ValueMaterializerTy ValMaterializer;
389 /// Mapping of values from what they used to be in Src, to what they are now
390 /// in DstM. ValueToValueMapTy is a ValueMap, which involves some overhead
391 /// due to the use of Value handles which the Linker doesn't actually need,
392 /// but this allows us to reuse the ValueMapper code.
393 ValueToValueMapTy ValueMap;
395 // Set of items not to link in from source.
396 SmallPtrSet<const GlobalValue *, 16> DoNotLinkFromSource;
398 DiagnosticHandlerFunction DiagnosticHandler;
400 /// For symbol clashes, prefer those from Src.
403 /// Function index passed into ModuleLinker for using in function
404 /// importing/exporting handling.
405 const FunctionInfoIndex *ImportIndex;
407 /// Function to import from source module, all other functions are
408 /// imported as declarations instead of definitions.
409 DenseSet<const GlobalValue *> *ImportFunction;
411 /// Set to true if the given FunctionInfoIndex contains any functions
412 /// from this source module, in which case we must conservatively assume
413 /// that any of its functions may be imported into another module
414 /// as part of a different backend compilation process.
415 bool HasExportedFunctions = false;
417 /// Set to true when all global value body linking is complete (including
418 /// lazy linking). Used to prevent metadata linking from creating new
420 bool DoneLinkingBodies = false;
422 bool HasError = false;
425 ModuleLinker(Module &DstM, Linker::IdentifiedStructTypeSet &Set, Module &SrcM,
426 DiagnosticHandlerFunction DiagnosticHandler, unsigned Flags,
427 const FunctionInfoIndex *Index = nullptr,
428 DenseSet<const GlobalValue *> *FuncToImport = nullptr)
429 : DstM(DstM), SrcM(SrcM), TypeMap(Set), ValMaterializer(this),
430 DiagnosticHandler(DiagnosticHandler), Flags(Flags), ImportIndex(Index),
431 ImportFunction(FuncToImport) {
432 assert((ImportIndex || !ImportFunction) &&
433 "Expect a FunctionInfoIndex when importing");
434 // If we have a FunctionInfoIndex but no function to import,
435 // then this is the primary module being compiled in a ThinLTO
436 // backend compilation, and we need to see if it has functions that
437 // may be exported to another backend compilation.
438 if (ImportIndex && !ImportFunction)
439 HasExportedFunctions = ImportIndex->hasExportedFunctions(&SrcM);
443 Value *materializeDeclFor(Value *V);
444 void materializeInitFor(GlobalValue *New, GlobalValue *Old);
447 bool shouldOverrideFromSrc() { return Flags & Linker::OverrideFromSrc; }
448 bool shouldLinkOnlyNeeded() { return Flags & Linker::LinkOnlyNeeded; }
449 bool shouldInternalizeLinkedSymbols() {
450 return Flags & Linker::InternalizeLinkedSymbols;
453 /// Handles cloning of a global values from the source module into
454 /// the destination module, including setting the attributes and visibility.
455 GlobalValue *copyGlobalValueProto(TypeMapTy &TypeMap, const GlobalValue *SGV,
456 const GlobalValue *DGV, bool ForDefinition);
458 /// Check if we should promote the given local value to global scope.
459 bool doPromoteLocalToGlobal(const GlobalValue *SGV);
461 bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
462 const GlobalValue &Src);
464 /// Helper method for setting a message and returning an error code.
465 bool emitError(const Twine &Message) {
466 DiagnosticHandler(LinkDiagnosticInfo(DS_Error, Message));
471 void emitWarning(const Twine &Message) {
472 DiagnosticHandler(LinkDiagnosticInfo(DS_Warning, Message));
475 bool getComdatLeader(Module &M, StringRef ComdatName,
476 const GlobalVariable *&GVar);
477 bool computeResultingSelectionKind(StringRef ComdatName,
478 Comdat::SelectionKind Src,
479 Comdat::SelectionKind Dst,
480 Comdat::SelectionKind &Result,
482 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
484 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
486 // Keep track of the global value members of each comdat in source.
487 DenseMap<const Comdat *, std::vector<GlobalValue *>> ComdatMembers;
489 /// Given a global in the source module, return the global in the
490 /// destination module that is being linked to, if any.
491 GlobalValue *getLinkedToGlobal(const GlobalValue *SrcGV) {
492 // If the source has no name it can't link. If it has local linkage,
493 // there is no name match-up going on.
494 if (!SrcGV->hasName() || GlobalValue::isLocalLinkage(getLinkage(SrcGV)))
497 // Otherwise see if we have a match in the destination module's symtab.
498 GlobalValue *DGV = DstM.getNamedValue(getName(SrcGV));
502 // If we found a global with the same name in the dest module, but it has
503 // internal linkage, we are really not doing any linkage here.
504 if (DGV->hasLocalLinkage())
507 // Otherwise, we do in fact link to the destination global.
511 void computeTypeMapping();
513 void upgradeMismatchedGlobalArray(StringRef Name);
514 void upgradeMismatchedGlobals();
516 bool linkIfNeeded(GlobalValue &GV);
517 bool linkAppendingVarProto(GlobalVariable *DstGV,
518 const GlobalVariable *SrcGV);
520 bool linkGlobalValueProto(GlobalValue *GV);
521 bool linkModuleFlagsMetadata();
523 void linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src);
524 bool linkFunctionBody(Function &Dst, Function &Src);
525 void linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src);
526 bool linkGlobalValueBody(GlobalValue &Dst, GlobalValue &Src);
528 /// Functions that take care of cloning a specific global value type
529 /// into the destination module.
530 GlobalVariable *copyGlobalVariableProto(TypeMapTy &TypeMap,
531 const GlobalVariable *SGVar);
532 Function *copyFunctionProto(TypeMapTy &TypeMap, const Function *SF);
533 GlobalValue *copyGlobalAliasProto(TypeMapTy &TypeMap, const GlobalAlias *SGA);
535 /// Helper methods to check if we are importing from or potentially
536 /// exporting from the current source module.
537 bool isPerformingImport() { return ImportFunction != nullptr; }
538 bool isModuleExporting() { return HasExportedFunctions; }
540 /// If we are importing from the source module, checks if we should
541 /// import SGV as a definition, otherwise import as a declaration.
542 bool doImportAsDefinition(const GlobalValue *SGV);
544 /// Get the name for SGV that should be used in the linked destination
545 /// module. Specifically, this handles the case where we need to rename
546 /// a local that is being promoted to global scope.
547 std::string getName(const GlobalValue *SGV);
549 /// Get the new linkage for SGV that should be used in the linked destination
550 /// module. Specifically, for ThinLTO importing or exporting it may need
552 GlobalValue::LinkageTypes getLinkage(const GlobalValue *SGV);
554 /// Copies the necessary global value attributes and name from the source
555 /// to the newly cloned global value.
556 void copyGVAttributes(GlobalValue *NewGV, const GlobalValue *SrcGV);
558 /// Updates the visibility for the new global cloned from the source
559 /// and, if applicable, linked with an existing destination global.
560 /// Handles visibility change required for promoted locals.
561 void setVisibility(GlobalValue *NewGV, const GlobalValue *SGV,
562 const GlobalValue *DGV = nullptr);
564 void linkNamedMDNodes();
568 /// The LLVM SymbolTable class autorenames globals that conflict in the symbol
569 /// table. This is good for all clients except for us. Go through the trouble
570 /// to force this back.
571 static void forceRenaming(GlobalValue *GV, StringRef Name) {
572 // If the global doesn't force its name or if it already has the right name,
573 // there is nothing for us to do.
574 // Note that any required local to global promotion should already be done,
575 // so promoted locals will not skip this handling as their linkage is no
577 if (GV->hasLocalLinkage() || GV->getName() == Name)
580 Module *M = GV->getParent();
582 // If there is a conflict, rename the conflict.
583 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
584 GV->takeName(ConflictGV);
585 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
586 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
588 GV->setName(Name); // Force the name back
592 /// copy additional attributes (those not needed to construct a GlobalValue)
593 /// from the SrcGV to the DestGV.
594 void ModuleLinker::copyGVAttributes(GlobalValue *NewGV,
595 const GlobalValue *SrcGV) {
596 NewGV->copyAttributesFrom(SrcGV);
597 forceRenaming(NewGV, getName(SrcGV));
600 bool ModuleLinker::doImportAsDefinition(const GlobalValue *SGV) {
601 if (!isPerformingImport())
603 auto *GA = dyn_cast<GlobalAlias>(SGV);
605 if (GA->hasWeakAnyLinkage())
607 const GlobalObject *GO = GA->getBaseObject();
608 if (!GO->hasLinkOnceODRLinkage())
610 return doImportAsDefinition(GO);
612 // Always import GlobalVariable definitions, except for the special
613 // case of WeakAny which are imported as ExternalWeak declarations
614 // (see comments in ModuleLinker::getLinkage). The linkage changes
615 // described in ModuleLinker::getLinkage ensure the correct behavior (e.g.
616 // global variables with external linkage are transformed to
617 // available_externally definitions, which are ultimately turned into
618 // declarations after the EliminateAvailableExternally pass).
619 if (isa<GlobalVariable>(SGV) && !SGV->isDeclaration() &&
620 !SGV->hasWeakAnyLinkage())
622 // Only import the function requested for importing.
623 auto *SF = dyn_cast<Function>(SGV);
624 if (SF && ImportFunction->count(SF))
630 bool ModuleLinker::doPromoteLocalToGlobal(const GlobalValue *SGV) {
631 assert(SGV->hasLocalLinkage());
632 // Both the imported references and the original local variable must
634 if (!isPerformingImport() && !isModuleExporting())
637 // Local const variables never need to be promoted unless they are address
638 // taken. The imported uses can simply use the clone created in this module.
639 // For now we are conservative in determining which variables are not
640 // address taken by checking the unnamed addr flag. To be more aggressive,
641 // the address taken information must be checked earlier during parsing
642 // of the module and recorded in the function index for use when importing
644 auto *GVar = dyn_cast<GlobalVariable>(SGV);
645 if (GVar && GVar->isConstant() && GVar->hasUnnamedAddr())
648 // Eventually we only need to promote functions in the exporting module that
649 // are referenced by a potentially exported function (i.e. one that is in the
654 std::string ModuleLinker::getName(const GlobalValue *SGV) {
655 // For locals that must be promoted to global scope, ensure that
656 // the promoted name uniquely identifies the copy in the original module,
657 // using the ID assigned during combined index creation. When importing,
658 // we rename all locals (not just those that are promoted) in order to
659 // avoid naming conflicts between locals imported from different modules.
660 if (SGV->hasLocalLinkage() &&
661 (doPromoteLocalToGlobal(SGV) || isPerformingImport()))
662 return FunctionInfoIndex::getGlobalNameForLocal(
664 ImportIndex->getModuleId(SGV->getParent()->getModuleIdentifier()));
665 return SGV->getName();
668 GlobalValue::LinkageTypes ModuleLinker::getLinkage(const GlobalValue *SGV) {
669 // Any local variable that is referenced by an exported function needs
670 // to be promoted to global scope. Since we don't currently know which
671 // functions reference which local variables/functions, we must treat
672 // all as potentially exported if this module is exporting anything.
673 if (isModuleExporting()) {
674 if (SGV->hasLocalLinkage() && doPromoteLocalToGlobal(SGV))
675 return GlobalValue::ExternalLinkage;
676 return SGV->getLinkage();
679 // Otherwise, if we aren't importing, no linkage change is needed.
680 if (!isPerformingImport())
681 return SGV->getLinkage();
683 switch (SGV->getLinkage()) {
684 case GlobalValue::ExternalLinkage:
685 // External defnitions are converted to available_externally
686 // definitions upon import, so that they are available for inlining
687 // and/or optimization, but are turned into declarations later
688 // during the EliminateAvailableExternally pass.
689 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
690 return GlobalValue::AvailableExternallyLinkage;
691 // An imported external declaration stays external.
692 return SGV->getLinkage();
694 case GlobalValue::AvailableExternallyLinkage:
695 // An imported available_externally definition converts
696 // to external if imported as a declaration.
697 if (!doImportAsDefinition(SGV))
698 return GlobalValue::ExternalLinkage;
699 // An imported available_externally declaration stays that way.
700 return SGV->getLinkage();
702 case GlobalValue::LinkOnceAnyLinkage:
703 case GlobalValue::LinkOnceODRLinkage:
704 // These both stay the same when importing the definition.
705 // The ThinLTO pass will eventually force-import their definitions.
706 return SGV->getLinkage();
708 case GlobalValue::WeakAnyLinkage:
709 // Can't import weak_any definitions correctly, or we might change the
710 // program semantics, since the linker will pick the first weak_any
711 // definition and importing would change the order they are seen by the
712 // linker. The module linking caller needs to enforce this.
713 assert(!doImportAsDefinition(SGV));
714 // If imported as a declaration, it becomes external_weak.
715 return GlobalValue::ExternalWeakLinkage;
717 case GlobalValue::WeakODRLinkage:
718 // For weak_odr linkage, there is a guarantee that all copies will be
719 // equivalent, so the issue described above for weak_any does not exist,
720 // and the definition can be imported. It can be treated similarly
721 // to an imported externally visible global value.
722 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
723 return GlobalValue::AvailableExternallyLinkage;
725 return GlobalValue::ExternalLinkage;
727 case GlobalValue::AppendingLinkage:
728 // It would be incorrect to import an appending linkage variable,
729 // since it would cause global constructors/destructors to be
730 // executed multiple times. This should have already been handled
731 // by linkGlobalValueProto.
732 llvm_unreachable("Cannot import appending linkage variable");
734 case GlobalValue::InternalLinkage:
735 case GlobalValue::PrivateLinkage:
736 // If we are promoting the local to global scope, it is handled
737 // similarly to a normal externally visible global.
738 if (doPromoteLocalToGlobal(SGV)) {
739 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
740 return GlobalValue::AvailableExternallyLinkage;
742 return GlobalValue::ExternalLinkage;
744 // A non-promoted imported local definition stays local.
745 // The ThinLTO pass will eventually force-import their definitions.
746 return SGV->getLinkage();
748 case GlobalValue::ExternalWeakLinkage:
749 // External weak doesn't apply to definitions, must be a declaration.
750 assert(!doImportAsDefinition(SGV));
751 // Linkage stays external_weak.
752 return SGV->getLinkage();
754 case GlobalValue::CommonLinkage:
755 // Linkage stays common on definitions.
756 // The ThinLTO pass will eventually force-import their definitions.
757 return SGV->getLinkage();
760 llvm_unreachable("unknown linkage type");
763 /// Loop through the global variables in the src module and merge them into the
766 ModuleLinker::copyGlobalVariableProto(TypeMapTy &TypeMap,
767 const GlobalVariable *SGVar) {
768 // No linking to be performed or linking from the source: simply create an
769 // identical version of the symbol over in the dest module... the
770 // initializer will be filled in later by LinkGlobalInits.
771 GlobalVariable *NewDGV =
772 new GlobalVariable(DstM, TypeMap.get(SGVar->getType()->getElementType()),
773 SGVar->isConstant(), GlobalValue::ExternalLinkage,
774 /*init*/ nullptr, getName(SGVar),
775 /*insertbefore*/ nullptr, SGVar->getThreadLocalMode(),
776 SGVar->getType()->getAddressSpace());
781 /// Link the function in the source module into the destination module if
782 /// needed, setting up mapping information.
783 Function *ModuleLinker::copyFunctionProto(TypeMapTy &TypeMap,
784 const Function *SF) {
785 // If there is no linkage to be performed or we are linking from the source,
787 return Function::Create(TypeMap.get(SF->getFunctionType()),
788 GlobalValue::ExternalLinkage, getName(SF), &DstM);
791 /// Set up prototypes for any aliases that come over from the source module.
792 GlobalValue *ModuleLinker::copyGlobalAliasProto(TypeMapTy &TypeMap,
793 const GlobalAlias *SGA) {
794 // If we are importing and encounter a weak_any alias, or an alias to
795 // an object being imported as a declaration, we must import the alias
796 // as a declaration as well, which involves converting it to a non-alias.
797 // See comments in ModuleLinker::getLinkage for why we cannot import
798 // weak_any defintions.
799 if (isPerformingImport() && !doImportAsDefinition(SGA)) {
800 // Need to convert to declaration. All aliases must be definitions.
801 const GlobalValue *GVal = SGA->getBaseObject();
803 if (auto *GVar = dyn_cast<GlobalVariable>(GVal))
804 NewGV = copyGlobalVariableProto(TypeMap, GVar);
806 auto *F = dyn_cast<Function>(GVal);
808 NewGV = copyFunctionProto(TypeMap, F);
810 // Set the linkage to External or ExternalWeak (see comments in
811 // ModuleLinker::getLinkage for why WeakAny is converted to ExternalWeak).
812 if (SGA->hasWeakAnyLinkage())
813 NewGV->setLinkage(GlobalValue::ExternalWeakLinkage);
815 NewGV->setLinkage(GlobalValue::ExternalLinkage);
818 // If there is no linkage to be performed or we're linking from the source,
820 auto *Ty = TypeMap.get(SGA->getValueType());
821 return GlobalAlias::create(Ty, SGA->getType()->getPointerAddressSpace(),
822 GlobalValue::ExternalLinkage, getName(SGA), &DstM);
825 static GlobalValue::VisibilityTypes
826 getMinVisibility(GlobalValue::VisibilityTypes A,
827 GlobalValue::VisibilityTypes B) {
828 if (A == GlobalValue::HiddenVisibility || B == GlobalValue::HiddenVisibility)
829 return GlobalValue::HiddenVisibility;
830 if (A == GlobalValue::ProtectedVisibility ||
831 B == GlobalValue::ProtectedVisibility)
832 return GlobalValue::ProtectedVisibility;
833 return GlobalValue::DefaultVisibility;
836 void ModuleLinker::setVisibility(GlobalValue *NewGV, const GlobalValue *SGV,
837 const GlobalValue *DGV) {
838 GlobalValue::VisibilityTypes Visibility = SGV->getVisibility();
840 Visibility = getMinVisibility(DGV->getVisibility(), Visibility);
841 // For promoted locals, mark them hidden so that they can later be
842 // stripped from the symbol table to reduce bloat.
843 if (SGV->hasLocalLinkage() && doPromoteLocalToGlobal(SGV))
844 Visibility = GlobalValue::HiddenVisibility;
845 NewGV->setVisibility(Visibility);
848 GlobalValue *ModuleLinker::copyGlobalValueProto(TypeMapTy &TypeMap,
849 const GlobalValue *SGV,
850 const GlobalValue *DGV,
851 bool ForDefinition) {
853 if (auto *SGVar = dyn_cast<GlobalVariable>(SGV)) {
854 NewGV = copyGlobalVariableProto(TypeMap, SGVar);
855 } else if (auto *SF = dyn_cast<Function>(SGV)) {
856 NewGV = copyFunctionProto(TypeMap, SF);
859 NewGV = copyGlobalAliasProto(TypeMap, cast<GlobalAlias>(SGV));
861 NewGV = new GlobalVariable(
862 DstM, TypeMap.get(SGV->getType()->getElementType()),
863 /*isConstant*/ false, GlobalValue::ExternalLinkage,
864 /*init*/ nullptr, getName(SGV),
865 /*insertbefore*/ nullptr, SGV->getThreadLocalMode(),
866 SGV->getType()->getAddressSpace());
870 NewGV->setLinkage(getLinkage(SGV));
871 else if (SGV->hasAvailableExternallyLinkage() || SGV->hasWeakLinkage() ||
872 SGV->hasLinkOnceLinkage())
873 NewGV->setLinkage(GlobalValue::ExternalWeakLinkage);
875 copyGVAttributes(NewGV, SGV);
876 setVisibility(NewGV, SGV, DGV);
880 Value *ValueMaterializerTy::materializeDeclFor(Value *V) {
881 return ModLinker->materializeDeclFor(V);
884 Value *ModuleLinker::materializeDeclFor(Value *V) {
885 auto *SGV = dyn_cast<GlobalValue>(V);
889 // If we are done linking global value bodies (i.e. we are performing
890 // metadata linking), don't link in the global value due to this
891 // reference, simply map it to null.
892 if (DoneLinkingBodies)
895 linkGlobalValueProto(SGV);
898 Value *Ret = ValueMap[SGV];
903 void ValueMaterializerTy::materializeInitFor(GlobalValue *New,
905 return ModLinker->materializeInitFor(New, Old);
908 void ModuleLinker::materializeInitFor(GlobalValue *New, GlobalValue *Old) {
909 if (auto *F = dyn_cast<Function>(New)) {
910 if (!F->isDeclaration())
912 } else if (auto *V = dyn_cast<GlobalVariable>(New)) {
913 if (V->hasInitializer())
916 auto *A = cast<GlobalAlias>(New);
921 if (Old->isDeclaration())
924 if (isPerformingImport() && !doImportAsDefinition(Old))
927 if (!New->hasLocalLinkage() && DoNotLinkFromSource.count(Old))
930 linkGlobalValueBody(*New, *Old);
933 bool ModuleLinker::getComdatLeader(Module &M, StringRef ComdatName,
934 const GlobalVariable *&GVar) {
935 const GlobalValue *GVal = M.getNamedValue(ComdatName);
936 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
937 GVal = GA->getBaseObject();
939 // We cannot resolve the size of the aliasee yet.
940 return emitError("Linking COMDATs named '" + ComdatName +
941 "': COMDAT key involves incomputable alias size.");
944 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
947 "Linking COMDATs named '" + ComdatName +
948 "': GlobalVariable required for data dependent selection!");
953 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
954 Comdat::SelectionKind Src,
955 Comdat::SelectionKind Dst,
956 Comdat::SelectionKind &Result,
958 // The ability to mix Comdat::SelectionKind::Any with
959 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
960 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
961 Dst == Comdat::SelectionKind::Largest;
962 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
963 Src == Comdat::SelectionKind::Largest;
964 if (DstAnyOrLargest && SrcAnyOrLargest) {
965 if (Dst == Comdat::SelectionKind::Largest ||
966 Src == Comdat::SelectionKind::Largest)
967 Result = Comdat::SelectionKind::Largest;
969 Result = Comdat::SelectionKind::Any;
970 } else if (Src == Dst) {
973 return emitError("Linking COMDATs named '" + ComdatName +
974 "': invalid selection kinds!");
978 case Comdat::SelectionKind::Any:
982 case Comdat::SelectionKind::NoDuplicates:
983 return emitError("Linking COMDATs named '" + ComdatName +
984 "': noduplicates has been violated!");
985 case Comdat::SelectionKind::ExactMatch:
986 case Comdat::SelectionKind::Largest:
987 case Comdat::SelectionKind::SameSize: {
988 const GlobalVariable *DstGV;
989 const GlobalVariable *SrcGV;
990 if (getComdatLeader(DstM, ComdatName, DstGV) ||
991 getComdatLeader(SrcM, ComdatName, SrcGV))
994 const DataLayout &DstDL = DstM.getDataLayout();
995 const DataLayout &SrcDL = SrcM.getDataLayout();
997 DstDL.getTypeAllocSize(DstGV->getType()->getPointerElementType());
999 SrcDL.getTypeAllocSize(SrcGV->getType()->getPointerElementType());
1000 if (Result == Comdat::SelectionKind::ExactMatch) {
1001 if (SrcGV->getInitializer() != DstGV->getInitializer())
1002 return emitError("Linking COMDATs named '" + ComdatName +
1003 "': ExactMatch violated!");
1004 LinkFromSrc = false;
1005 } else if (Result == Comdat::SelectionKind::Largest) {
1006 LinkFromSrc = SrcSize > DstSize;
1007 } else if (Result == Comdat::SelectionKind::SameSize) {
1008 if (SrcSize != DstSize)
1009 return emitError("Linking COMDATs named '" + ComdatName +
1010 "': SameSize violated!");
1011 LinkFromSrc = false;
1013 llvm_unreachable("unknown selection kind");
1022 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
1023 Comdat::SelectionKind &Result,
1024 bool &LinkFromSrc) {
1025 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
1026 StringRef ComdatName = SrcC->getName();
1027 Module::ComdatSymTabType &ComdatSymTab = DstM.getComdatSymbolTable();
1028 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
1030 if (DstCI == ComdatSymTab.end()) {
1031 // Use the comdat if it is only available in one of the modules.
1037 const Comdat *DstC = &DstCI->second;
1038 Comdat::SelectionKind DSK = DstC->getSelectionKind();
1039 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
1043 bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
1044 const GlobalValue &Dest,
1045 const GlobalValue &Src) {
1046 // Should we unconditionally use the Src?
1047 if (shouldOverrideFromSrc()) {
1052 // We always have to add Src if it has appending linkage.
1053 if (Src.hasAppendingLinkage()) {
1054 // Caller should have already determined that we can't link from source
1055 // when importing (see comments in linkGlobalValueProto).
1056 assert(!isPerformingImport());
1061 bool SrcIsDeclaration = Src.isDeclarationForLinker();
1062 bool DestIsDeclaration = Dest.isDeclarationForLinker();
1064 if (isPerformingImport()) {
1065 if (isa<Function>(&Src)) {
1066 // For functions, LinkFromSrc iff this is the function requested
1067 // for importing. For variables, decide below normally.
1068 LinkFromSrc = ImportFunction->count(&Src);
1072 // Check if this is an alias with an already existing definition
1073 // in Dest, which must have come from a prior importing pass from
1074 // the same Src module. Unlike imported function and variable
1075 // definitions, which are imported as available_externally and are
1076 // not definitions for the linker, that is not a valid linkage for
1077 // imported aliases which must be definitions. Simply use the existing
1079 if (isa<GlobalAlias>(&Src) && !DestIsDeclaration) {
1080 assert(isa<GlobalAlias>(&Dest));
1081 LinkFromSrc = false;
1086 if (SrcIsDeclaration) {
1087 // If Src is external or if both Src & Dest are external.. Just link the
1088 // external globals, we aren't adding anything.
1089 if (Src.hasDLLImportStorageClass()) {
1090 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
1091 LinkFromSrc = DestIsDeclaration;
1094 // If the Dest is weak, use the source linkage.
1095 LinkFromSrc = Dest.hasExternalWeakLinkage();
1099 if (DestIsDeclaration) {
1100 // If Dest is external but Src is not:
1105 if (Src.hasCommonLinkage()) {
1106 if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
1111 if (!Dest.hasCommonLinkage()) {
1112 LinkFromSrc = false;
1116 const DataLayout &DL = Dest.getParent()->getDataLayout();
1117 uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
1118 uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
1119 LinkFromSrc = SrcSize > DestSize;
1123 if (Src.isWeakForLinker()) {
1124 assert(!Dest.hasExternalWeakLinkage());
1125 assert(!Dest.hasAvailableExternallyLinkage());
1127 if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
1132 LinkFromSrc = false;
1136 if (Dest.isWeakForLinker()) {
1137 assert(Src.hasExternalLinkage());
1142 assert(!Src.hasExternalWeakLinkage());
1143 assert(!Dest.hasExternalWeakLinkage());
1144 assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
1145 "Unexpected linkage type!");
1146 return emitError("Linking globals named '" + Src.getName() +
1147 "': symbol multiply defined!");
1150 /// Loop over all of the linked values to compute type mappings. For example,
1151 /// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct
1152 /// types 'Foo' but one got renamed when the module was loaded into the same
1154 void ModuleLinker::computeTypeMapping() {
1155 for (GlobalValue &SGV : SrcM.globals()) {
1156 GlobalValue *DGV = getLinkedToGlobal(&SGV);
1160 if (!DGV->hasAppendingLinkage() || !SGV.hasAppendingLinkage()) {
1161 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1165 // Unify the element type of appending arrays.
1166 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
1167 ArrayType *SAT = cast<ArrayType>(SGV.getType()->getElementType());
1168 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
1171 for (GlobalValue &SGV : SrcM) {
1172 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
1173 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1176 for (GlobalValue &SGV : SrcM.aliases()) {
1177 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
1178 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1181 // Incorporate types by name, scanning all the types in the source module.
1182 // At this point, the destination module may have a type "%foo = { i32 }" for
1183 // example. When the source module got loaded into the same LLVMContext, if
1184 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
1185 std::vector<StructType *> Types = SrcM.getIdentifiedStructTypes();
1186 for (StructType *ST : Types) {
1190 // Check to see if there is a dot in the name followed by a digit.
1191 size_t DotPos = ST->getName().rfind('.');
1192 if (DotPos == 0 || DotPos == StringRef::npos ||
1193 ST->getName().back() == '.' ||
1194 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos + 1])))
1197 // Check to see if the destination module has a struct with the prefix name.
1198 StructType *DST = DstM.getTypeByName(ST->getName().substr(0, DotPos));
1202 // Don't use it if this actually came from the source module. They're in
1203 // the same LLVMContext after all. Also don't use it unless the type is
1204 // actually used in the destination module. This can happen in situations
1207 // Module A Module B
1208 // -------- --------
1209 // %Z = type { %A } %B = type { %C.1 }
1210 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
1211 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
1212 // %C = type { i8* } %B.3 = type { %C.1 }
1214 // When we link Module B with Module A, the '%B' in Module B is
1215 // used. However, that would then use '%C.1'. But when we process '%C.1',
1216 // we prefer to take the '%C' version. So we are then left with both
1217 // '%C.1' and '%C' being used for the same types. This leads to some
1218 // variables using one type and some using the other.
1219 if (TypeMap.DstStructTypesSet.hasType(DST))
1220 TypeMap.addTypeMapping(DST, ST);
1223 // Now that we have discovered all of the type equivalences, get a body for
1224 // any 'opaque' types in the dest module that are now resolved.
1225 TypeMap.linkDefinedTypeBodies();
1228 static void upgradeGlobalArray(GlobalVariable *GV) {
1229 ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
1230 StructType *OldTy = cast<StructType>(ATy->getElementType());
1231 assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
1233 // Get the upgraded 3 element type.
1234 PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
1235 Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
1237 StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
1239 // Build new constants with a null third field filled in.
1240 Constant *OldInitC = GV->getInitializer();
1241 ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
1242 if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
1243 // Invalid initializer; give up.
1245 std::vector<Constant *> Initializers;
1246 if (OldInit && OldInit->getNumOperands()) {
1247 Value *Null = Constant::getNullValue(VoidPtrTy);
1248 for (Use &U : OldInit->operands()) {
1249 ConstantStruct *Init = cast<ConstantStruct>(U.get());
1250 Initializers.push_back(ConstantStruct::get(
1251 NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
1254 assert(Initializers.size() == ATy->getNumElements() &&
1255 "Failed to copy all array elements");
1257 // Replace the old GV with a new one.
1258 ATy = ArrayType::get(NewTy, Initializers.size());
1259 Constant *NewInit = ConstantArray::get(ATy, Initializers);
1260 GlobalVariable *NewGV = new GlobalVariable(
1261 *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
1262 GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
1263 GV->isExternallyInitialized());
1264 NewGV->copyAttributesFrom(GV);
1265 NewGV->takeName(GV);
1266 assert(GV->use_empty() && "program cannot use initializer list");
1267 GV->eraseFromParent();
1270 void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
1271 // Look for the global arrays.
1272 auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM.getNamedValue(Name));
1275 auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM.getNamedValue(Name));
1279 // Check if the types already match.
1280 auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
1282 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
1286 // Grab the element types. We can only upgrade an array of a two-field
1287 // struct. Only bother if the other one has three-fields.
1288 auto *DstEltTy = cast<StructType>(DstTy->getElementType());
1289 auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
1290 if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
1291 upgradeGlobalArray(DstGV);
1294 if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
1295 upgradeGlobalArray(SrcGV);
1297 // We can't upgrade any other differences.
1300 void ModuleLinker::upgradeMismatchedGlobals() {
1301 upgradeMismatchedGlobalArray("llvm.global_ctors");
1302 upgradeMismatchedGlobalArray("llvm.global_dtors");
1305 static void getArrayElements(const Constant *C,
1306 SmallVectorImpl<Constant *> &Dest) {
1307 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1309 for (unsigned i = 0; i != NumElements; ++i)
1310 Dest.push_back(C->getAggregateElement(i));
1313 /// If there were any appending global variables, link them together now.
1314 /// Return true on error.
1315 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
1316 const GlobalVariable *SrcGV) {
1318 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
1319 Type *EltTy = SrcTy->getElementType();
1322 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
1324 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
1326 "Linking globals named '" + SrcGV->getName() +
1327 "': can only link appending global with another appending global!");
1329 // Check to see that they two arrays agree on type.
1330 if (EltTy != DstTy->getElementType())
1331 return emitError("Appending variables with different element types!");
1332 if (DstGV->isConstant() != SrcGV->isConstant())
1333 return emitError("Appending variables linked with different const'ness!");
1335 if (DstGV->getAlignment() != SrcGV->getAlignment())
1337 "Appending variables with different alignment need to be linked!");
1339 if (DstGV->getVisibility() != SrcGV->getVisibility())
1341 "Appending variables with different visibility need to be linked!");
1343 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
1345 "Appending variables with different unnamed_addr need to be linked!");
1347 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
1349 "Appending variables with different section name need to be linked!");
1352 SmallVector<Constant *, 16> DstElements;
1354 getArrayElements(DstGV->getInitializer(), DstElements);
1356 SmallVector<Constant *, 16> SrcElements;
1357 getArrayElements(SrcGV->getInitializer(), SrcElements);
1359 StringRef Name = SrcGV->getName();
1360 bool IsNewStructor =
1361 (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
1362 cast<StructType>(EltTy)->getNumElements() == 3;
1365 std::remove_if(SrcElements.begin(), SrcElements.end(),
1366 [this](Constant *E) {
1367 auto *Key = dyn_cast<GlobalValue>(
1368 E->getAggregateElement(2)->stripPointerCasts());
1369 return DoNotLinkFromSource.count(Key);
1372 uint64_t NewSize = DstElements.size() + SrcElements.size();
1373 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
1375 // Create the new global variable.
1376 GlobalVariable *NG = new GlobalVariable(
1377 DstM, NewType, SrcGV->isConstant(), SrcGV->getLinkage(),
1378 /*init*/ nullptr, /*name*/ "", DstGV, SrcGV->getThreadLocalMode(),
1379 SrcGV->getType()->getAddressSpace());
1381 // Propagate alignment, visibility and section info.
1382 copyGVAttributes(NG, SrcGV);
1384 // Replace any uses of the two global variables with uses of the new
1386 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
1388 for (auto *V : SrcElements) {
1389 DstElements.push_back(
1390 MapValue(V, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1393 NG->setInitializer(ConstantArray::get(NewType, DstElements));
1396 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
1397 DstGV->eraseFromParent();
1403 bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) {
1404 GlobalValue *DGV = getLinkedToGlobal(SGV);
1406 // Handle the ultra special appending linkage case first.
1407 assert(!DGV || SGV->hasAppendingLinkage() == DGV->hasAppendingLinkage());
1408 if (SGV->hasAppendingLinkage() && isPerformingImport()) {
1409 // Don't want to append to global_ctors list, for example, when we
1410 // are importing for ThinLTO, otherwise the global ctors and dtors
1411 // get executed multiple times for local variables (the latter causing
1413 DoNotLinkFromSource.insert(SGV);
1416 if (SGV->hasAppendingLinkage())
1417 return linkAppendingVarProto(cast_or_null<GlobalVariable>(DGV),
1418 cast<GlobalVariable>(SGV));
1420 bool LinkFromSrc = true;
1421 Comdat *C = nullptr;
1422 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
1424 if (const Comdat *SC = SGV->getComdat()) {
1425 Comdat::SelectionKind SK;
1426 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1427 C = DstM.getOrInsertComdat(SC->getName());
1428 C->setSelectionKind(SK);
1429 if (SGV->hasLocalLinkage())
1432 if (shouldLinkFromSource(LinkFromSrc, *DGV, *SGV))
1437 // Track the source global so that we don't attempt to copy it over when
1438 // processing global initializers.
1439 DoNotLinkFromSource.insert(SGV);
1442 // Make sure to remember this mapping.
1444 ConstantExpr::getBitCast(DGV, TypeMap.get(SGV->getType()));
1448 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1451 if (!LinkFromSrc && DGV) {
1453 // When linking from source we setVisibility from copyGlobalValueProto.
1454 setVisibility(NewGV, SGV, DGV);
1456 NewGV = copyGlobalValueProto(TypeMap, SGV, DGV, LinkFromSrc);
1458 if (isPerformingImport() && !doImportAsDefinition(SGV))
1459 DoNotLinkFromSource.insert(SGV);
1462 NewGV->setUnnamedAddr(HasUnnamedAddr);
1464 if (auto *NewGO = dyn_cast<GlobalObject>(NewGV)) {
1465 if (C && LinkFromSrc)
1466 NewGO->setComdat(C);
1468 if (DGV && DGV->hasCommonLinkage() && SGV->hasCommonLinkage())
1469 NewGO->setAlignment(std::max(DGV->getAlignment(), SGV->getAlignment()));
1472 if (auto *NewGVar = dyn_cast<GlobalVariable>(NewGV)) {
1473 auto *DGVar = dyn_cast_or_null<GlobalVariable>(DGV);
1474 auto *SGVar = dyn_cast<GlobalVariable>(SGV);
1475 if (DGVar && SGVar && DGVar->isDeclaration() && SGVar->isDeclaration() &&
1476 (!DGVar->isConstant() || !SGVar->isConstant()))
1477 NewGVar->setConstant(false);
1480 // Make sure to remember this mapping.
1483 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewGV, DGV->getType()));
1484 DGV->eraseFromParent();
1486 ValueMap[SGV] = NewGV;
1492 /// Update the initializers in the Dest module now that all globals that may be
1493 /// referenced are in Dest.
1494 void ModuleLinker::linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src) {
1495 // Figure out what the initializer looks like in the dest module.
1496 Dst.setInitializer(MapValue(Src.getInitializer(), ValueMap,
1497 RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1500 /// Copy the source function over into the dest function and fix up references
1501 /// to values. At this point we know that Dest is an external function, and
1502 /// that Src is not.
1503 bool ModuleLinker::linkFunctionBody(Function &Dst, Function &Src) {
1504 assert(Dst.isDeclaration() && !Src.isDeclaration());
1506 // Materialize if needed.
1507 if (std::error_code EC = Src.materialize())
1508 return emitError(EC.message());
1510 // Link in the prefix data.
1511 if (Src.hasPrefixData())
1512 Dst.setPrefixData(MapValue(Src.getPrefixData(), ValueMap,
1513 RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1515 // Link in the prologue data.
1516 if (Src.hasPrologueData())
1517 Dst.setPrologueData(MapValue(Src.getPrologueData(), ValueMap,
1518 RF_MoveDistinctMDs, &TypeMap,
1521 // Link in the personality function.
1522 if (Src.hasPersonalityFn())
1523 Dst.setPersonalityFn(MapValue(Src.getPersonalityFn(), ValueMap,
1524 RF_MoveDistinctMDs, &TypeMap,
1527 // Go through and convert function arguments over, remembering the mapping.
1528 Function::arg_iterator DI = Dst.arg_begin();
1529 for (Argument &Arg : Src.args()) {
1530 DI->setName(Arg.getName()); // Copy the name over.
1532 // Add a mapping to our mapping.
1533 ValueMap[&Arg] = &*DI;
1537 // Copy over the metadata attachments.
1538 SmallVector<std::pair<unsigned, MDNode *>, 8> MDs;
1539 Src.getAllMetadata(MDs);
1540 for (const auto &I : MDs)
1541 Dst.setMetadata(I.first, MapMetadata(I.second, ValueMap, RF_MoveDistinctMDs,
1542 &TypeMap, &ValMaterializer));
1544 // Splice the body of the source function into the dest function.
1545 Dst.getBasicBlockList().splice(Dst.end(), Src.getBasicBlockList());
1547 // At this point, all of the instructions and values of the function are now
1548 // copied over. The only problem is that they are still referencing values in
1549 // the Source function as operands. Loop through all of the operands of the
1550 // functions and patch them up to point to the local versions.
1551 for (BasicBlock &BB : Dst)
1552 for (Instruction &I : BB)
1553 RemapInstruction(&I, ValueMap,
1554 RF_IgnoreMissingEntries | RF_MoveDistinctMDs, &TypeMap,
1557 // There is no need to map the arguments anymore.
1558 for (Argument &Arg : Src.args())
1559 ValueMap.erase(&Arg);
1561 Src.dematerialize();
1565 void ModuleLinker::linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src) {
1566 Constant *Aliasee = Src.getAliasee();
1567 Constant *Val = MapValue(Aliasee, ValueMap, RF_MoveDistinctMDs, &TypeMap,
1569 Dst.setAliasee(Val);
1572 bool ModuleLinker::linkGlobalValueBody(GlobalValue &Dst, GlobalValue &Src) {
1573 if (const Comdat *SC = Src.getComdat()) {
1574 // To ensure that we don't generate an incomplete comdat group,
1575 // we must materialize and map in any other members that are not
1576 // yet materialized in Dst, which also ensures their definitions
1577 // are linked in. Otherwise, linkonce and other lazy linked GVs will
1578 // not be materialized if they aren't referenced.
1579 for (auto *SGV : ComdatMembers[SC]) {
1580 auto *DGV = cast_or_null<GlobalValue>(ValueMap[SGV]);
1581 if (DGV && !DGV->isDeclaration())
1583 MapValue(SGV, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer);
1586 if (shouldInternalizeLinkedSymbols())
1587 if (auto *DGV = dyn_cast<GlobalValue>(&Dst))
1588 DGV->setLinkage(GlobalValue::InternalLinkage);
1589 if (auto *F = dyn_cast<Function>(&Src))
1590 return linkFunctionBody(cast<Function>(Dst), *F);
1591 if (auto *GVar = dyn_cast<GlobalVariable>(&Src)) {
1592 linkGlobalInit(cast<GlobalVariable>(Dst), *GVar);
1595 linkAliasBody(cast<GlobalAlias>(Dst), cast<GlobalAlias>(Src));
1599 /// Insert all of the named MDNodes in Src into the Dest module.
1600 void ModuleLinker::linkNamedMDNodes() {
1601 const NamedMDNode *SrcModFlags = SrcM.getModuleFlagsMetadata();
1602 for (const NamedMDNode &NMD : SrcM.named_metadata()) {
1603 // Don't link module flags here. Do them separately.
1604 if (&NMD == SrcModFlags)
1606 NamedMDNode *DestNMD = DstM.getOrInsertNamedMetadata(NMD.getName());
1607 // Add Src elements into Dest node.
1608 for (const MDNode *op : NMD.operands())
1609 DestNMD->addOperand(MapMetadata(
1610 op, ValueMap, RF_MoveDistinctMDs | RF_NullMapMissingGlobalValues,
1611 &TypeMap, &ValMaterializer));
1615 /// Merge the linker flags in Src into the Dest module.
1616 bool ModuleLinker::linkModuleFlagsMetadata() {
1617 // If the source module has no module flags, we are done.
1618 const NamedMDNode *SrcModFlags = SrcM.getModuleFlagsMetadata();
1622 // If the destination module doesn't have module flags yet, then just copy
1623 // over the source module's flags.
1624 NamedMDNode *DstModFlags = DstM.getOrInsertModuleFlagsMetadata();
1625 if (DstModFlags->getNumOperands() == 0) {
1626 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1627 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1632 // First build a map of the existing module flags and requirements.
1633 DenseMap<MDString *, std::pair<MDNode *, unsigned>> Flags;
1634 SmallSetVector<MDNode *, 16> Requirements;
1635 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1636 MDNode *Op = DstModFlags->getOperand(I);
1637 ConstantInt *Behavior = mdconst::extract<ConstantInt>(Op->getOperand(0));
1638 MDString *ID = cast<MDString>(Op->getOperand(1));
1640 if (Behavior->getZExtValue() == Module::Require) {
1641 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1643 Flags[ID] = std::make_pair(Op, I);
1647 // Merge in the flags from the source module, and also collect its set of
1649 bool HasErr = false;
1650 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1651 MDNode *SrcOp = SrcModFlags->getOperand(I);
1652 ConstantInt *SrcBehavior =
1653 mdconst::extract<ConstantInt>(SrcOp->getOperand(0));
1654 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1657 std::tie(DstOp, DstIndex) = Flags.lookup(ID);
1658 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1660 // If this is a requirement, add it and continue.
1661 if (SrcBehaviorValue == Module::Require) {
1662 // If the destination module does not already have this requirement, add
1664 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1665 DstModFlags->addOperand(SrcOp);
1670 // If there is no existing flag with this ID, just add it.
1672 Flags[ID] = std::make_pair(SrcOp, DstModFlags->getNumOperands());
1673 DstModFlags->addOperand(SrcOp);
1677 // Otherwise, perform a merge.
1678 ConstantInt *DstBehavior =
1679 mdconst::extract<ConstantInt>(DstOp->getOperand(0));
1680 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1682 // If either flag has override behavior, handle it first.
1683 if (DstBehaviorValue == Module::Override) {
1684 // Diagnose inconsistent flags which both have override behavior.
1685 if (SrcBehaviorValue == Module::Override &&
1686 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1687 HasErr |= emitError("linking module flags '" + ID->getString() +
1688 "': IDs have conflicting override values");
1691 } else if (SrcBehaviorValue == Module::Override) {
1692 // Update the destination flag to that of the source.
1693 DstModFlags->setOperand(DstIndex, SrcOp);
1694 Flags[ID].first = SrcOp;
1698 // Diagnose inconsistent merge behavior types.
1699 if (SrcBehaviorValue != DstBehaviorValue) {
1700 HasErr |= emitError("linking module flags '" + ID->getString() +
1701 "': IDs have conflicting behaviors");
1705 auto replaceDstValue = [&](MDNode *New) {
1706 Metadata *FlagOps[] = {DstOp->getOperand(0), ID, New};
1707 MDNode *Flag = MDNode::get(DstM.getContext(), FlagOps);
1708 DstModFlags->setOperand(DstIndex, Flag);
1709 Flags[ID].first = Flag;
1712 // Perform the merge for standard behavior types.
1713 switch (SrcBehaviorValue) {
1714 case Module::Require:
1715 case Module::Override:
1716 llvm_unreachable("not possible");
1717 case Module::Error: {
1718 // Emit an error if the values differ.
1719 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1720 HasErr |= emitError("linking module flags '" + ID->getString() +
1721 "': IDs have conflicting values");
1725 case Module::Warning: {
1726 // Emit a warning if the values differ.
1727 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1728 emitWarning("linking module flags '" + ID->getString() +
1729 "': IDs have conflicting values");
1733 case Module::Append: {
1734 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1735 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1736 SmallVector<Metadata *, 8> MDs;
1737 MDs.reserve(DstValue->getNumOperands() + SrcValue->getNumOperands());
1738 MDs.append(DstValue->op_begin(), DstValue->op_end());
1739 MDs.append(SrcValue->op_begin(), SrcValue->op_end());
1741 replaceDstValue(MDNode::get(DstM.getContext(), MDs));
1744 case Module::AppendUnique: {
1745 SmallSetVector<Metadata *, 16> Elts;
1746 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1747 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1748 Elts.insert(DstValue->op_begin(), DstValue->op_end());
1749 Elts.insert(SrcValue->op_begin(), SrcValue->op_end());
1751 replaceDstValue(MDNode::get(DstM.getContext(),
1752 makeArrayRef(Elts.begin(), Elts.end())));
1758 // Check all of the requirements.
1759 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1760 MDNode *Requirement = Requirements[I];
1761 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1762 Metadata *ReqValue = Requirement->getOperand(1);
1764 MDNode *Op = Flags[Flag].first;
1765 if (!Op || Op->getOperand(2) != ReqValue) {
1766 HasErr |= emitError("linking module flags '" + Flag->getString() +
1767 "': does not have the required value");
1775 // This function returns true if the triples match.
1776 static bool triplesMatch(const Triple &T0, const Triple &T1) {
1777 // If vendor is apple, ignore the version number.
1778 if (T0.getVendor() == Triple::Apple)
1779 return T0.getArch() == T1.getArch() && T0.getSubArch() == T1.getSubArch() &&
1780 T0.getVendor() == T1.getVendor() && T0.getOS() == T1.getOS();
1785 // This function returns the merged triple.
1786 static std::string mergeTriples(const Triple &SrcTriple,
1787 const Triple &DstTriple) {
1788 // If vendor is apple, pick the triple with the larger version number.
1789 if (SrcTriple.getVendor() == Triple::Apple)
1790 if (DstTriple.isOSVersionLT(SrcTriple))
1791 return SrcTriple.str();
1793 return DstTriple.str();
1796 bool ModuleLinker::linkIfNeeded(GlobalValue &GV) {
1797 GlobalValue *DGV = getLinkedToGlobal(&GV);
1799 if (shouldLinkOnlyNeeded() && !(DGV && DGV->isDeclaration()))
1802 if (DGV && !GV.hasLocalLinkage()) {
1803 GlobalValue::VisibilityTypes Visibility =
1804 getMinVisibility(DGV->getVisibility(), GV.getVisibility());
1805 DGV->setVisibility(Visibility);
1806 GV.setVisibility(Visibility);
1809 if (const Comdat *SC = GV.getComdat()) {
1811 Comdat::SelectionKind SK;
1812 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1814 DoNotLinkFromSource.insert(&GV);
1819 if (!DGV && !shouldOverrideFromSrc() &&
1820 (GV.hasLocalLinkage() || GV.hasLinkOnceLinkage() ||
1821 GV.hasAvailableExternallyLinkage())) {
1824 MapValue(&GV, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer);
1828 bool ModuleLinker::run() {
1829 // Inherit the target data from the source module if the destination module
1830 // doesn't have one already.
1831 if (DstM.getDataLayout().isDefault())
1832 DstM.setDataLayout(SrcM.getDataLayout());
1834 if (SrcM.getDataLayout() != DstM.getDataLayout()) {
1835 emitWarning("Linking two modules of different data layouts: '" +
1836 SrcM.getModuleIdentifier() + "' is '" +
1837 SrcM.getDataLayoutStr() + "' whereas '" +
1838 DstM.getModuleIdentifier() + "' is '" +
1839 DstM.getDataLayoutStr() + "'\n");
1842 // Copy the target triple from the source to dest if the dest's is empty.
1843 if (DstM.getTargetTriple().empty() && !SrcM.getTargetTriple().empty())
1844 DstM.setTargetTriple(SrcM.getTargetTriple());
1846 Triple SrcTriple(SrcM.getTargetTriple()), DstTriple(DstM.getTargetTriple());
1848 if (!SrcM.getTargetTriple().empty() && !triplesMatch(SrcTriple, DstTriple))
1849 emitWarning("Linking two modules of different target triples: " +
1850 SrcM.getModuleIdentifier() + "' is '" + SrcM.getTargetTriple() +
1851 "' whereas '" + DstM.getModuleIdentifier() + "' is '" +
1852 DstM.getTargetTriple() + "'\n");
1854 DstM.setTargetTriple(mergeTriples(SrcTriple, DstTriple));
1856 // Append the module inline asm string.
1857 if (!SrcM.getModuleInlineAsm().empty()) {
1858 if (DstM.getModuleInlineAsm().empty())
1859 DstM.setModuleInlineAsm(SrcM.getModuleInlineAsm());
1861 DstM.setModuleInlineAsm(DstM.getModuleInlineAsm() + "\n" +
1862 SrcM.getModuleInlineAsm());
1865 // Loop over all of the linked values to compute type mappings.
1866 computeTypeMapping();
1868 ComdatsChosen.clear();
1869 for (const auto &SMEC : SrcM.getComdatSymbolTable()) {
1870 const Comdat &C = SMEC.getValue();
1871 if (ComdatsChosen.count(&C))
1873 Comdat::SelectionKind SK;
1875 if (getComdatResult(&C, SK, LinkFromSrc))
1877 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1880 // Upgrade mismatched global arrays.
1881 upgradeMismatchedGlobals();
1883 for (GlobalVariable &GV : SrcM.globals())
1884 if (const Comdat *SC = GV.getComdat())
1885 ComdatMembers[SC].push_back(&GV);
1887 for (Function &SF : SrcM)
1888 if (const Comdat *SC = SF.getComdat())
1889 ComdatMembers[SC].push_back(&SF);
1891 for (GlobalAlias &GA : SrcM.aliases())
1892 if (const Comdat *SC = GA.getComdat())
1893 ComdatMembers[SC].push_back(&GA);
1895 // Insert all of the globals in src into the DstM module... without linking
1896 // initializers (which could refer to functions not yet mapped over).
1897 for (GlobalVariable &GV : SrcM.globals())
1898 if (linkIfNeeded(GV))
1901 for (Function &SF : SrcM)
1902 if (linkIfNeeded(SF))
1905 for (GlobalAlias &GA : SrcM.aliases())
1906 if (linkIfNeeded(GA))
1909 for (const auto &Entry : DstM.getComdatSymbolTable()) {
1910 const Comdat &C = Entry.getValue();
1911 if (C.getSelectionKind() == Comdat::Any)
1913 const GlobalValue *GV = SrcM.getNamedValue(C.getName());
1915 MapValue(GV, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer);
1918 // Note that we are done linking global value bodies. This prevents
1919 // metadata linking from creating new references.
1920 DoneLinkingBodies = true;
1922 // Remap all of the named MDNodes in Src into the DstM module. We do this
1923 // after linking GlobalValues so that MDNodes that reference GlobalValues
1924 // are properly remapped.
1927 // Merge the module flags into the DstM module.
1928 if (linkModuleFlagsMetadata())
1934 Linker::StructTypeKeyInfo::KeyTy::KeyTy(ArrayRef<Type *> E, bool P)
1935 : ETypes(E), IsPacked(P) {}
1937 Linker::StructTypeKeyInfo::KeyTy::KeyTy(const StructType *ST)
1938 : ETypes(ST->elements()), IsPacked(ST->isPacked()) {}
1940 bool Linker::StructTypeKeyInfo::KeyTy::operator==(const KeyTy &That) const {
1941 if (IsPacked != That.IsPacked)
1943 if (ETypes != That.ETypes)
1948 bool Linker::StructTypeKeyInfo::KeyTy::operator!=(const KeyTy &That) const {
1949 return !this->operator==(That);
1952 StructType *Linker::StructTypeKeyInfo::getEmptyKey() {
1953 return DenseMapInfo<StructType *>::getEmptyKey();
1956 StructType *Linker::StructTypeKeyInfo::getTombstoneKey() {
1957 return DenseMapInfo<StructType *>::getTombstoneKey();
1960 unsigned Linker::StructTypeKeyInfo::getHashValue(const KeyTy &Key) {
1961 return hash_combine(hash_combine_range(Key.ETypes.begin(), Key.ETypes.end()),
1965 unsigned Linker::StructTypeKeyInfo::getHashValue(const StructType *ST) {
1966 return getHashValue(KeyTy(ST));
1969 bool Linker::StructTypeKeyInfo::isEqual(const KeyTy &LHS,
1970 const StructType *RHS) {
1971 if (RHS == getEmptyKey() || RHS == getTombstoneKey())
1973 return LHS == KeyTy(RHS);
1976 bool Linker::StructTypeKeyInfo::isEqual(const StructType *LHS,
1977 const StructType *RHS) {
1978 if (RHS == getEmptyKey())
1979 return LHS == getEmptyKey();
1981 if (RHS == getTombstoneKey())
1982 return LHS == getTombstoneKey();
1984 return KeyTy(LHS) == KeyTy(RHS);
1987 void Linker::IdentifiedStructTypeSet::addNonOpaque(StructType *Ty) {
1988 assert(!Ty->isOpaque());
1989 NonOpaqueStructTypes.insert(Ty);
1992 void Linker::IdentifiedStructTypeSet::switchToNonOpaque(StructType *Ty) {
1993 assert(!Ty->isOpaque());
1994 NonOpaqueStructTypes.insert(Ty);
1995 bool Removed = OpaqueStructTypes.erase(Ty);
2000 void Linker::IdentifiedStructTypeSet::addOpaque(StructType *Ty) {
2001 assert(Ty->isOpaque());
2002 OpaqueStructTypes.insert(Ty);
2006 Linker::IdentifiedStructTypeSet::findNonOpaque(ArrayRef<Type *> ETypes,
2008 Linker::StructTypeKeyInfo::KeyTy Key(ETypes, IsPacked);
2009 auto I = NonOpaqueStructTypes.find_as(Key);
2010 if (I == NonOpaqueStructTypes.end())
2015 bool Linker::IdentifiedStructTypeSet::hasType(StructType *Ty) {
2017 return OpaqueStructTypes.count(Ty);
2018 auto I = NonOpaqueStructTypes.find(Ty);
2019 if (I == NonOpaqueStructTypes.end())
2024 Linker::Linker(Module &M, DiagnosticHandlerFunction DiagnosticHandler)
2025 : Composite(M), DiagnosticHandler(DiagnosticHandler) {
2026 TypeFinder StructTypes;
2027 StructTypes.run(M, true);
2028 for (StructType *Ty : StructTypes) {
2030 IdentifiedStructTypes.addOpaque(Ty);
2032 IdentifiedStructTypes.addNonOpaque(Ty);
2036 Linker::Linker(Module &M)
2037 : Linker(M, [this](const DiagnosticInfo &DI) {
2038 Composite.getContext().diagnose(DI);
2041 bool Linker::linkInModule(Module &Src, unsigned Flags,
2042 const FunctionInfoIndex *Index,
2043 DenseSet<const GlobalValue *> *FuncToImport) {
2044 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,
2045 DiagnosticHandler, Flags, Index, FuncToImport);
2046 bool RetCode = TheLinker.run();
2047 Composite.dropTriviallyDeadConstantArrays();
2051 //===----------------------------------------------------------------------===//
2052 // LinkModules entrypoint.
2053 //===----------------------------------------------------------------------===//
2055 /// This function links two modules together, with the resulting Dest module
2056 /// modified to be the composite of the two input modules. If an error occurs,
2057 /// true is returned and ErrorMsg (if not null) is set to indicate the problem.
2058 /// Upon failure, the Dest module could be in a modified state, and shouldn't be
2059 /// relied on to be consistent.
2060 bool Linker::linkModules(Module &Dest, Module &Src,
2061 DiagnosticHandlerFunction DiagnosticHandler,
2063 Linker L(Dest, DiagnosticHandler);
2064 return L.linkInModule(Src, Flags);
2067 bool Linker::linkModules(Module &Dest, Module &Src, unsigned Flags) {
2069 return L.linkInModule(Src, Flags);
2072 //===----------------------------------------------------------------------===//
2074 //===----------------------------------------------------------------------===//
2076 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
2077 LLVMLinkerMode Unused, char **OutMessages) {
2078 Module *D = unwrap(Dest);
2079 std::string Message;
2080 raw_string_ostream Stream(Message);
2081 DiagnosticPrinterRawOStream DP(Stream);
2083 LLVMBool Result = Linker::linkModules(
2084 *D, *unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); });
2086 if (OutMessages && Result) {
2088 *OutMessages = strdup(Message.c_str());