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 Function *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;
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;
422 bool HasError = false;
425 ModuleLinker(Module &DstM, Linker::IdentifiedStructTypeSet &Set, Module &SrcM,
426 DiagnosticHandlerFunction DiagnosticHandler, unsigned Flags,
427 const FunctionInfoIndex *Index = nullptr,
428 Function *FuncToImport = nullptr)
429 : DstM(DstM), SrcM(SrcM), TypeMap(Set), ValMaterializer(this),
430 DiagnosticHandler(DiagnosticHandler), Flags(Flags), ImportIndex(Index),
431 ImportFunction(FuncToImport), HasExportedFunctions(false),
432 DoneLinkingBodies(false) {
433 assert((ImportIndex || !ImportFunction) &&
434 "Expect a FunctionInfoIndex when importing");
435 // If we have a FunctionInfoIndex but no function to import,
436 // then this is the primary module being compiled in a ThinLTO
437 // backend compilation, and we need to see if it has functions that
438 // may be exported to another backend compilation.
439 if (ImportIndex && !ImportFunction)
440 HasExportedFunctions = ImportIndex->hasExportedFunctions(&SrcM);
444 Value *materializeDeclFor(Value *V);
445 void materializeInitFor(GlobalValue *New, GlobalValue *Old);
448 bool shouldOverrideFromSrc() { return Flags & Linker::OverrideFromSrc; }
449 bool shouldLinkOnlyNeeded() { return Flags & Linker::LinkOnlyNeeded; }
450 bool shouldInternalizeLinkedSymbols() {
451 return Flags & Linker::InternalizeLinkedSymbols;
454 /// Handles cloning of a global values from the source module into
455 /// the destination module, including setting the attributes and visibility.
456 GlobalValue *copyGlobalValueProto(TypeMapTy &TypeMap, const GlobalValue *SGV,
457 const GlobalValue *DGV = nullptr);
459 /// Check if we should promote the given local value to global scope.
460 bool doPromoteLocalToGlobal(const GlobalValue *SGV);
462 /// Check if all global value body linking is complete.
463 bool doneLinkingBodies() { return DoneLinkingBodies; }
465 bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
466 const GlobalValue &Src);
468 /// Helper method for setting a message and returning an error code.
469 bool emitError(const Twine &Message) {
470 DiagnosticHandler(LinkDiagnosticInfo(DS_Error, Message));
475 void emitWarning(const Twine &Message) {
476 DiagnosticHandler(LinkDiagnosticInfo(DS_Warning, Message));
479 bool getComdatLeader(Module &M, StringRef ComdatName,
480 const GlobalVariable *&GVar);
481 bool computeResultingSelectionKind(StringRef ComdatName,
482 Comdat::SelectionKind Src,
483 Comdat::SelectionKind Dst,
484 Comdat::SelectionKind &Result,
486 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
488 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
490 // Keep track of the global value members of each comdat in source.
491 DenseMap<const Comdat *, std::vector<GlobalValue *>> ComdatMembers;
493 /// Given a global in the source module, return the global in the
494 /// destination module that is being linked to, if any.
495 GlobalValue *getLinkedToGlobal(const GlobalValue *SrcGV) {
496 // If the source has no name it can't link. If it has local linkage,
497 // there is no name match-up going on.
498 if (!SrcGV->hasName() || GlobalValue::isLocalLinkage(getLinkage(SrcGV)))
501 // Otherwise see if we have a match in the destination module's symtab.
502 GlobalValue *DGV = DstM.getNamedValue(getName(SrcGV));
506 // If we found a global with the same name in the dest module, but it has
507 // internal linkage, we are really not doing any linkage here.
508 if (DGV->hasLocalLinkage())
511 // Otherwise, we do in fact link to the destination global.
515 void computeTypeMapping();
517 void upgradeMismatchedGlobalArray(StringRef Name);
518 void upgradeMismatchedGlobals();
520 bool linkIfNeeded(GlobalValue &GV);
521 bool linkAppendingVarProto(GlobalVariable *DstGV,
522 const GlobalVariable *SrcGV);
524 bool linkGlobalValueProto(GlobalValue *GV);
525 bool linkModuleFlagsMetadata();
527 void linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src);
528 bool linkFunctionBody(Function &Dst, Function &Src);
529 void linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src);
530 bool linkGlobalValueBody(GlobalValue &Dst, GlobalValue &Src);
532 /// Functions that take care of cloning a specific global value type
533 /// into the destination module.
534 GlobalVariable *copyGlobalVariableProto(TypeMapTy &TypeMap,
535 const GlobalVariable *SGVar);
536 Function *copyFunctionProto(TypeMapTy &TypeMap, const Function *SF);
537 GlobalValue *copyGlobalAliasProto(TypeMapTy &TypeMap, const GlobalAlias *SGA);
539 /// Helper methods to check if we are importing from or potentially
540 /// exporting from the current source module.
541 bool isPerformingImport() { return ImportFunction != nullptr; }
542 bool isModuleExporting() { return HasExportedFunctions; }
544 /// If we are importing from the source module, checks if we should
545 /// import SGV as a definition, otherwise import as a declaration.
546 bool doImportAsDefinition(const GlobalValue *SGV);
548 /// Get the name for SGV that should be used in the linked destination
549 /// module. Specifically, this handles the case where we need to rename
550 /// a local that is being promoted to global scope.
551 std::string getName(const GlobalValue *SGV);
553 /// Get the new linkage for SGV that should be used in the linked destination
554 /// module. Specifically, for ThinLTO importing or exporting it may need
556 GlobalValue::LinkageTypes getLinkage(const GlobalValue *SGV);
558 /// Copies the necessary global value attributes and name from the source
559 /// to the newly cloned global value.
560 void copyGVAttributes(GlobalValue *NewGV, const GlobalValue *SrcGV);
562 /// Updates the visibility for the new global cloned from the source
563 /// and, if applicable, linked with an existing destination global.
564 /// Handles visibility change required for promoted locals.
565 void setVisibility(GlobalValue *NewGV, const GlobalValue *SGV,
566 const GlobalValue *DGV = nullptr);
568 void linkNamedMDNodes();
572 /// The LLVM SymbolTable class autorenames globals that conflict in the symbol
573 /// table. This is good for all clients except for us. Go through the trouble
574 /// to force this back.
575 static void forceRenaming(GlobalValue *GV, StringRef Name) {
576 // If the global doesn't force its name or if it already has the right name,
577 // there is nothing for us to do.
578 // Note that any required local to global promotion should already be done,
579 // so promoted locals will not skip this handling as their linkage is no
581 if (GV->hasLocalLinkage() || GV->getName() == Name)
584 Module *M = GV->getParent();
586 // If there is a conflict, rename the conflict.
587 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
588 GV->takeName(ConflictGV);
589 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
590 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
592 GV->setName(Name); // Force the name back
596 /// copy additional attributes (those not needed to construct a GlobalValue)
597 /// from the SrcGV to the DestGV.
598 void ModuleLinker::copyGVAttributes(GlobalValue *NewGV,
599 const GlobalValue *SrcGV) {
600 auto *GA = dyn_cast<GlobalAlias>(SrcGV);
601 // Check for the special case of converting an alias (definition) to a
602 // non-alias (declaration). This can happen when we are importing and
603 // encounter a weak_any alias (weak_any defs may not be imported, see
604 // comments in ModuleLinker::getLinkage) or an alias whose base object is
605 // being imported as a declaration. In that case copy the attributes from the
607 if (GA && !dyn_cast<GlobalAlias>(NewGV)) {
608 assert(isPerformingImport() && !doImportAsDefinition(GA));
609 NewGV->copyAttributesFrom(GA->getBaseObject());
611 NewGV->copyAttributesFrom(SrcGV);
612 forceRenaming(NewGV, getName(SrcGV));
615 bool ModuleLinker::doImportAsDefinition(const GlobalValue *SGV) {
616 if (!isPerformingImport())
618 auto *GA = dyn_cast<GlobalAlias>(SGV);
620 if (GA->hasWeakAnyLinkage())
622 const GlobalObject *GO = GA->getBaseObject();
623 if (!GO->hasLinkOnceODRLinkage())
625 return doImportAsDefinition(GO);
627 // Always import GlobalVariable definitions, except for the special
628 // case of WeakAny which are imported as ExternalWeak declarations
629 // (see comments in ModuleLinker::getLinkage). The linkage changes
630 // described in ModuleLinker::getLinkage ensure the correct behavior (e.g.
631 // global variables with external linkage are transformed to
632 // available_externally definitions, which are ultimately turned into
633 // declarations after the EliminateAvailableExternally pass).
634 if (isa<GlobalVariable>(SGV) && !SGV->isDeclaration() &&
635 !SGV->hasWeakAnyLinkage())
637 // Only import the function requested for importing.
638 auto *SF = dyn_cast<Function>(SGV);
639 if (SF && SF == ImportFunction)
645 bool ModuleLinker::doPromoteLocalToGlobal(const GlobalValue *SGV) {
646 assert(SGV->hasLocalLinkage());
647 // Both the imported references and the original local variable must
649 if (!isPerformingImport() && !isModuleExporting())
652 // Local const variables never need to be promoted unless they are address
653 // taken. The imported uses can simply use the clone created in this module.
654 // For now we are conservative in determining which variables are not
655 // address taken by checking the unnamed addr flag. To be more aggressive,
656 // the address taken information must be checked earlier during parsing
657 // of the module and recorded in the function index for use when importing
659 auto *GVar = dyn_cast<GlobalVariable>(SGV);
660 if (GVar && GVar->isConstant() && GVar->hasUnnamedAddr())
663 // Eventually we only need to promote functions in the exporting module that
664 // are referenced by a potentially exported function (i.e. one that is in the
669 std::string ModuleLinker::getName(const GlobalValue *SGV) {
670 // For locals that must be promoted to global scope, ensure that
671 // the promoted name uniquely identifies the copy in the original module,
672 // using the ID assigned during combined index creation. When importing,
673 // we rename all locals (not just those that are promoted) in order to
674 // avoid naming conflicts between locals imported from different modules.
675 if (SGV->hasLocalLinkage() &&
676 (doPromoteLocalToGlobal(SGV) || isPerformingImport()))
677 return FunctionInfoIndex::getGlobalNameForLocal(
679 ImportIndex->getModuleId(SGV->getParent()->getModuleIdentifier()));
680 return SGV->getName();
683 GlobalValue::LinkageTypes ModuleLinker::getLinkage(const GlobalValue *SGV) {
684 // Any local variable that is referenced by an exported function needs
685 // to be promoted to global scope. Since we don't currently know which
686 // functions reference which local variables/functions, we must treat
687 // all as potentially exported if this module is exporting anything.
688 if (isModuleExporting()) {
689 if (SGV->hasLocalLinkage() && doPromoteLocalToGlobal(SGV))
690 return GlobalValue::ExternalLinkage;
691 return SGV->getLinkage();
694 // Otherwise, if we aren't importing, no linkage change is needed.
695 if (!isPerformingImport())
696 return SGV->getLinkage();
698 switch (SGV->getLinkage()) {
699 case GlobalValue::ExternalLinkage:
700 // External defnitions are converted to available_externally
701 // definitions upon import, so that they are available for inlining
702 // and/or optimization, but are turned into declarations later
703 // during the EliminateAvailableExternally pass.
704 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
705 return GlobalValue::AvailableExternallyLinkage;
706 // An imported external declaration stays external.
707 return SGV->getLinkage();
709 case GlobalValue::AvailableExternallyLinkage:
710 // An imported available_externally definition converts
711 // to external if imported as a declaration.
712 if (!doImportAsDefinition(SGV))
713 return GlobalValue::ExternalLinkage;
714 // An imported available_externally declaration stays that way.
715 return SGV->getLinkage();
717 case GlobalValue::LinkOnceAnyLinkage:
718 case GlobalValue::LinkOnceODRLinkage:
719 // These both stay the same when importing the definition.
720 // The ThinLTO pass will eventually force-import their definitions.
721 return SGV->getLinkage();
723 case GlobalValue::WeakAnyLinkage:
724 // Can't import weak_any definitions correctly, or we might change the
725 // program semantics, since the linker will pick the first weak_any
726 // definition and importing would change the order they are seen by the
727 // linker. The module linking caller needs to enforce this.
728 assert(!doImportAsDefinition(SGV));
729 // If imported as a declaration, it becomes external_weak.
730 return GlobalValue::ExternalWeakLinkage;
732 case GlobalValue::WeakODRLinkage:
733 // For weak_odr linkage, there is a guarantee that all copies will be
734 // equivalent, so the issue described above for weak_any does not exist,
735 // and the definition can be imported. It can be treated similarly
736 // to an imported externally visible global value.
737 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
738 return GlobalValue::AvailableExternallyLinkage;
740 return GlobalValue::ExternalLinkage;
742 case GlobalValue::AppendingLinkage:
743 // It would be incorrect to import an appending linkage variable,
744 // since it would cause global constructors/destructors to be
745 // executed multiple times. This should have already been handled
746 // by linkGlobalValueProto.
747 llvm_unreachable("Cannot import appending linkage variable");
749 case GlobalValue::InternalLinkage:
750 case GlobalValue::PrivateLinkage:
751 // If we are promoting the local to global scope, it is handled
752 // similarly to a normal externally visible global.
753 if (doPromoteLocalToGlobal(SGV)) {
754 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
755 return GlobalValue::AvailableExternallyLinkage;
757 return GlobalValue::ExternalLinkage;
759 // A non-promoted imported local definition stays local.
760 // The ThinLTO pass will eventually force-import their definitions.
761 return SGV->getLinkage();
763 case GlobalValue::ExternalWeakLinkage:
764 // External weak doesn't apply to definitions, must be a declaration.
765 assert(!doImportAsDefinition(SGV));
766 // Linkage stays external_weak.
767 return SGV->getLinkage();
769 case GlobalValue::CommonLinkage:
770 // Linkage stays common on definitions.
771 // The ThinLTO pass will eventually force-import their definitions.
772 return SGV->getLinkage();
775 llvm_unreachable("unknown linkage type");
778 /// Loop through the global variables in the src module and merge them into the
781 ModuleLinker::copyGlobalVariableProto(TypeMapTy &TypeMap,
782 const GlobalVariable *SGVar) {
783 // No linking to be performed or linking from the source: simply create an
784 // identical version of the symbol over in the dest module... the
785 // initializer will be filled in later by LinkGlobalInits.
786 GlobalVariable *NewDGV = new GlobalVariable(
787 DstM, TypeMap.get(SGVar->getType()->getElementType()),
788 SGVar->isConstant(), getLinkage(SGVar), /*init*/ nullptr, getName(SGVar),
789 /*insertbefore*/ nullptr, SGVar->getThreadLocalMode(),
790 SGVar->getType()->getAddressSpace());
795 /// Link the function in the source module into the destination module if
796 /// needed, setting up mapping information.
797 Function *ModuleLinker::copyFunctionProto(TypeMapTy &TypeMap,
798 const Function *SF) {
799 // If there is no linkage to be performed or we are linking from the source,
801 return Function::Create(TypeMap.get(SF->getFunctionType()), getLinkage(SF),
805 /// Set up prototypes for any aliases that come over from the source module.
806 GlobalValue *ModuleLinker::copyGlobalAliasProto(TypeMapTy &TypeMap,
807 const GlobalAlias *SGA) {
808 // If we are importing and encounter a weak_any alias, or an alias to
809 // an object being imported as a declaration, we must import the alias
810 // as a declaration as well, which involves converting it to a non-alias.
811 // See comments in ModuleLinker::getLinkage for why we cannot import
812 // weak_any defintions.
813 if (isPerformingImport() && !doImportAsDefinition(SGA)) {
814 // Need to convert to declaration. All aliases must be definitions.
815 const GlobalValue *GVal = SGA->getBaseObject();
817 if (auto *GVar = dyn_cast<GlobalVariable>(GVal))
818 NewGV = copyGlobalVariableProto(TypeMap, GVar);
820 auto *F = dyn_cast<Function>(GVal);
822 NewGV = copyFunctionProto(TypeMap, F);
824 // Set the linkage to External or ExternalWeak (see comments in
825 // ModuleLinker::getLinkage for why WeakAny is converted to ExternalWeak).
826 if (SGA->hasWeakAnyLinkage())
827 NewGV->setLinkage(GlobalValue::ExternalWeakLinkage);
829 NewGV->setLinkage(GlobalValue::ExternalLinkage);
832 // If there is no linkage to be performed or we're linking from the source,
834 auto *Ty = TypeMap.get(SGA->getValueType());
835 return GlobalAlias::create(Ty, SGA->getType()->getPointerAddressSpace(),
836 getLinkage(SGA), getName(SGA), &DstM);
839 static GlobalValue::VisibilityTypes
840 getMinVisibility(GlobalValue::VisibilityTypes A,
841 GlobalValue::VisibilityTypes B) {
842 if (A == GlobalValue::HiddenVisibility || B == GlobalValue::HiddenVisibility)
843 return GlobalValue::HiddenVisibility;
844 if (A == GlobalValue::ProtectedVisibility ||
845 B == GlobalValue::ProtectedVisibility)
846 return GlobalValue::ProtectedVisibility;
847 return GlobalValue::DefaultVisibility;
850 void ModuleLinker::setVisibility(GlobalValue *NewGV, const GlobalValue *SGV,
851 const GlobalValue *DGV) {
852 GlobalValue::VisibilityTypes Visibility = SGV->getVisibility();
854 Visibility = getMinVisibility(DGV->getVisibility(), Visibility);
855 // For promoted locals, mark them hidden so that they can later be
856 // stripped from the symbol table to reduce bloat.
857 if (SGV->hasLocalLinkage() && doPromoteLocalToGlobal(SGV))
858 Visibility = GlobalValue::HiddenVisibility;
859 NewGV->setVisibility(Visibility);
862 GlobalValue *ModuleLinker::copyGlobalValueProto(TypeMapTy &TypeMap,
863 const GlobalValue *SGV,
864 const GlobalValue *DGV) {
866 if (auto *SGVar = dyn_cast<GlobalVariable>(SGV))
867 NewGV = copyGlobalVariableProto(TypeMap, SGVar);
868 else if (auto *SF = dyn_cast<Function>(SGV))
869 NewGV = copyFunctionProto(TypeMap, SF);
871 NewGV = copyGlobalAliasProto(TypeMap, cast<GlobalAlias>(SGV));
872 copyGVAttributes(NewGV, SGV);
873 setVisibility(NewGV, SGV, DGV);
877 Value *ValueMaterializerTy::materializeDeclFor(Value *V) {
878 return ModLinker->materializeDeclFor(V);
881 Value *ModuleLinker::materializeDeclFor(Value *V) {
882 auto *SGV = dyn_cast<GlobalValue>(V);
886 // If we are done linking global value bodies (i.e. we are performing
887 // metadata linking), don't link in the global value due to this
888 // reference, simply map it to null.
889 if (doneLinkingBodies())
892 linkGlobalValueProto(SGV);
895 Value *Ret = ValueMap[SGV];
900 void ValueMaterializerTy::materializeInitFor(GlobalValue *New,
902 return ModLinker->materializeInitFor(New, Old);
905 void ModuleLinker::materializeInitFor(GlobalValue *New, GlobalValue *Old) {
906 if (auto *F = dyn_cast<Function>(New)) {
907 if (!F->isDeclaration())
909 } else if (auto *V = dyn_cast<GlobalVariable>(New)) {
910 if (V->hasInitializer())
913 auto *A = cast<GlobalAlias>(New);
918 if (Old->isDeclaration())
921 if (isPerformingImport() && !doImportAsDefinition(Old))
924 if (!New->hasLocalLinkage() && DoNotLinkFromSource.count(Old))
927 linkGlobalValueBody(*New, *Old);
930 bool ModuleLinker::getComdatLeader(Module &M, StringRef ComdatName,
931 const GlobalVariable *&GVar) {
932 const GlobalValue *GVal = M.getNamedValue(ComdatName);
933 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
934 GVal = GA->getBaseObject();
936 // We cannot resolve the size of the aliasee yet.
937 return emitError("Linking COMDATs named '" + ComdatName +
938 "': COMDAT key involves incomputable alias size.");
941 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
944 "Linking COMDATs named '" + ComdatName +
945 "': GlobalVariable required for data dependent selection!");
950 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
951 Comdat::SelectionKind Src,
952 Comdat::SelectionKind Dst,
953 Comdat::SelectionKind &Result,
955 // The ability to mix Comdat::SelectionKind::Any with
956 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
957 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
958 Dst == Comdat::SelectionKind::Largest;
959 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
960 Src == Comdat::SelectionKind::Largest;
961 if (DstAnyOrLargest && SrcAnyOrLargest) {
962 if (Dst == Comdat::SelectionKind::Largest ||
963 Src == Comdat::SelectionKind::Largest)
964 Result = Comdat::SelectionKind::Largest;
966 Result = Comdat::SelectionKind::Any;
967 } else if (Src == Dst) {
970 return emitError("Linking COMDATs named '" + ComdatName +
971 "': invalid selection kinds!");
975 case Comdat::SelectionKind::Any:
979 case Comdat::SelectionKind::NoDuplicates:
980 return emitError("Linking COMDATs named '" + ComdatName +
981 "': noduplicates has been violated!");
982 case Comdat::SelectionKind::ExactMatch:
983 case Comdat::SelectionKind::Largest:
984 case Comdat::SelectionKind::SameSize: {
985 const GlobalVariable *DstGV;
986 const GlobalVariable *SrcGV;
987 if (getComdatLeader(DstM, ComdatName, DstGV) ||
988 getComdatLeader(SrcM, ComdatName, SrcGV))
991 const DataLayout &DstDL = DstM.getDataLayout();
992 const DataLayout &SrcDL = SrcM.getDataLayout();
994 DstDL.getTypeAllocSize(DstGV->getType()->getPointerElementType());
996 SrcDL.getTypeAllocSize(SrcGV->getType()->getPointerElementType());
997 if (Result == Comdat::SelectionKind::ExactMatch) {
998 if (SrcGV->getInitializer() != DstGV->getInitializer())
999 return emitError("Linking COMDATs named '" + ComdatName +
1000 "': ExactMatch violated!");
1001 LinkFromSrc = false;
1002 } else if (Result == Comdat::SelectionKind::Largest) {
1003 LinkFromSrc = SrcSize > DstSize;
1004 } else if (Result == Comdat::SelectionKind::SameSize) {
1005 if (SrcSize != DstSize)
1006 return emitError("Linking COMDATs named '" + ComdatName +
1007 "': SameSize violated!");
1008 LinkFromSrc = false;
1010 llvm_unreachable("unknown selection kind");
1019 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
1020 Comdat::SelectionKind &Result,
1021 bool &LinkFromSrc) {
1022 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
1023 StringRef ComdatName = SrcC->getName();
1024 Module::ComdatSymTabType &ComdatSymTab = DstM.getComdatSymbolTable();
1025 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
1027 if (DstCI == ComdatSymTab.end()) {
1028 // Use the comdat if it is only available in one of the modules.
1034 const Comdat *DstC = &DstCI->second;
1035 Comdat::SelectionKind DSK = DstC->getSelectionKind();
1036 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
1040 bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
1041 const GlobalValue &Dest,
1042 const GlobalValue &Src) {
1043 // Should we unconditionally use the Src?
1044 if (shouldOverrideFromSrc()) {
1049 // We always have to add Src if it has appending linkage.
1050 if (Src.hasAppendingLinkage()) {
1051 // Caller should have already determined that we can't link from source
1052 // when importing (see comments in linkGlobalValueProto).
1053 assert(!isPerformingImport());
1058 bool SrcIsDeclaration = Src.isDeclarationForLinker();
1059 bool DestIsDeclaration = Dest.isDeclarationForLinker();
1061 if (isPerformingImport()) {
1062 if (isa<Function>(&Src)) {
1063 // For functions, LinkFromSrc iff this is the function requested
1064 // for importing. For variables, decide below normally.
1065 LinkFromSrc = (&Src == ImportFunction);
1069 // Check if this is an alias with an already existing definition
1070 // in Dest, which must have come from a prior importing pass from
1071 // the same Src module. Unlike imported function and variable
1072 // definitions, which are imported as available_externally and are
1073 // not definitions for the linker, that is not a valid linkage for
1074 // imported aliases which must be definitions. Simply use the existing
1076 if (isa<GlobalAlias>(&Src) && !DestIsDeclaration) {
1077 assert(isa<GlobalAlias>(&Dest));
1078 LinkFromSrc = false;
1083 if (SrcIsDeclaration) {
1084 // If Src is external or if both Src & Dest are external.. Just link the
1085 // external globals, we aren't adding anything.
1086 if (Src.hasDLLImportStorageClass()) {
1087 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
1088 LinkFromSrc = DestIsDeclaration;
1091 // If the Dest is weak, use the source linkage.
1092 LinkFromSrc = Dest.hasExternalWeakLinkage();
1096 if (DestIsDeclaration) {
1097 // If Dest is external but Src is not:
1102 if (Src.hasCommonLinkage()) {
1103 if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
1108 if (!Dest.hasCommonLinkage()) {
1109 LinkFromSrc = false;
1113 const DataLayout &DL = Dest.getParent()->getDataLayout();
1114 uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
1115 uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
1116 LinkFromSrc = SrcSize > DestSize;
1120 if (Src.isWeakForLinker()) {
1121 assert(!Dest.hasExternalWeakLinkage());
1122 assert(!Dest.hasAvailableExternallyLinkage());
1124 if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
1129 LinkFromSrc = false;
1133 if (Dest.isWeakForLinker()) {
1134 assert(Src.hasExternalLinkage());
1139 assert(!Src.hasExternalWeakLinkage());
1140 assert(!Dest.hasExternalWeakLinkage());
1141 assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
1142 "Unexpected linkage type!");
1143 return emitError("Linking globals named '" + Src.getName() +
1144 "': symbol multiply defined!");
1147 /// Loop over all of the linked values to compute type mappings. For example,
1148 /// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct
1149 /// types 'Foo' but one got renamed when the module was loaded into the same
1151 void ModuleLinker::computeTypeMapping() {
1152 for (GlobalValue &SGV : SrcM.globals()) {
1153 GlobalValue *DGV = getLinkedToGlobal(&SGV);
1157 if (!DGV->hasAppendingLinkage() || !SGV.hasAppendingLinkage()) {
1158 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1162 // Unify the element type of appending arrays.
1163 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
1164 ArrayType *SAT = cast<ArrayType>(SGV.getType()->getElementType());
1165 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
1168 for (GlobalValue &SGV : SrcM) {
1169 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
1170 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1173 for (GlobalValue &SGV : SrcM.aliases()) {
1174 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
1175 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1178 // Incorporate types by name, scanning all the types in the source module.
1179 // At this point, the destination module may have a type "%foo = { i32 }" for
1180 // example. When the source module got loaded into the same LLVMContext, if
1181 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
1182 std::vector<StructType *> Types = SrcM.getIdentifiedStructTypes();
1183 for (StructType *ST : Types) {
1187 // Check to see if there is a dot in the name followed by a digit.
1188 size_t DotPos = ST->getName().rfind('.');
1189 if (DotPos == 0 || DotPos == StringRef::npos ||
1190 ST->getName().back() == '.' ||
1191 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos + 1])))
1194 // Check to see if the destination module has a struct with the prefix name.
1195 StructType *DST = DstM.getTypeByName(ST->getName().substr(0, DotPos));
1199 // Don't use it if this actually came from the source module. They're in
1200 // the same LLVMContext after all. Also don't use it unless the type is
1201 // actually used in the destination module. This can happen in situations
1204 // Module A Module B
1205 // -------- --------
1206 // %Z = type { %A } %B = type { %C.1 }
1207 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
1208 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
1209 // %C = type { i8* } %B.3 = type { %C.1 }
1211 // When we link Module B with Module A, the '%B' in Module B is
1212 // used. However, that would then use '%C.1'. But when we process '%C.1',
1213 // we prefer to take the '%C' version. So we are then left with both
1214 // '%C.1' and '%C' being used for the same types. This leads to some
1215 // variables using one type and some using the other.
1216 if (TypeMap.DstStructTypesSet.hasType(DST))
1217 TypeMap.addTypeMapping(DST, ST);
1220 // Now that we have discovered all of the type equivalences, get a body for
1221 // any 'opaque' types in the dest module that are now resolved.
1222 TypeMap.linkDefinedTypeBodies();
1225 static void upgradeGlobalArray(GlobalVariable *GV) {
1226 ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
1227 StructType *OldTy = cast<StructType>(ATy->getElementType());
1228 assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
1230 // Get the upgraded 3 element type.
1231 PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
1232 Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
1234 StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
1236 // Build new constants with a null third field filled in.
1237 Constant *OldInitC = GV->getInitializer();
1238 ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
1239 if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
1240 // Invalid initializer; give up.
1242 std::vector<Constant *> Initializers;
1243 if (OldInit && OldInit->getNumOperands()) {
1244 Value *Null = Constant::getNullValue(VoidPtrTy);
1245 for (Use &U : OldInit->operands()) {
1246 ConstantStruct *Init = cast<ConstantStruct>(U.get());
1247 Initializers.push_back(ConstantStruct::get(
1248 NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
1251 assert(Initializers.size() == ATy->getNumElements() &&
1252 "Failed to copy all array elements");
1254 // Replace the old GV with a new one.
1255 ATy = ArrayType::get(NewTy, Initializers.size());
1256 Constant *NewInit = ConstantArray::get(ATy, Initializers);
1257 GlobalVariable *NewGV = new GlobalVariable(
1258 *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
1259 GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
1260 GV->isExternallyInitialized());
1261 NewGV->copyAttributesFrom(GV);
1262 NewGV->takeName(GV);
1263 assert(GV->use_empty() && "program cannot use initializer list");
1264 GV->eraseFromParent();
1267 void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
1268 // Look for the global arrays.
1269 auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM.getNamedValue(Name));
1272 auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM.getNamedValue(Name));
1276 // Check if the types already match.
1277 auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
1279 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
1283 // Grab the element types. We can only upgrade an array of a two-field
1284 // struct. Only bother if the other one has three-fields.
1285 auto *DstEltTy = cast<StructType>(DstTy->getElementType());
1286 auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
1287 if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
1288 upgradeGlobalArray(DstGV);
1291 if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
1292 upgradeGlobalArray(SrcGV);
1294 // We can't upgrade any other differences.
1297 void ModuleLinker::upgradeMismatchedGlobals() {
1298 upgradeMismatchedGlobalArray("llvm.global_ctors");
1299 upgradeMismatchedGlobalArray("llvm.global_dtors");
1302 static void getArrayElements(const Constant *C,
1303 SmallVectorImpl<Constant *> &Dest) {
1304 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1306 for (unsigned i = 0; i != NumElements; ++i)
1307 Dest.push_back(C->getAggregateElement(i));
1310 /// If there were any appending global variables, link them together now.
1311 /// Return true on error.
1312 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
1313 const GlobalVariable *SrcGV) {
1315 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
1316 Type *EltTy = SrcTy->getElementType();
1319 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
1321 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
1323 "Linking globals named '" + SrcGV->getName() +
1324 "': can only link appending global with another appending global!");
1326 // Check to see that they two arrays agree on type.
1327 if (EltTy != DstTy->getElementType())
1328 return emitError("Appending variables with different element types!");
1329 if (DstGV->isConstant() != SrcGV->isConstant())
1330 return emitError("Appending variables linked with different const'ness!");
1332 if (DstGV->getAlignment() != SrcGV->getAlignment())
1334 "Appending variables with different alignment need to be linked!");
1336 if (DstGV->getVisibility() != SrcGV->getVisibility())
1338 "Appending variables with different visibility need to be linked!");
1340 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
1342 "Appending variables with different unnamed_addr need to be linked!");
1344 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
1346 "Appending variables with different section name need to be linked!");
1349 SmallVector<Constant *, 16> DstElements;
1351 getArrayElements(DstGV->getInitializer(), DstElements);
1353 SmallVector<Constant *, 16> SrcElements;
1354 getArrayElements(SrcGV->getInitializer(), SrcElements);
1356 StringRef Name = SrcGV->getName();
1357 bool IsNewStructor =
1358 (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
1359 cast<StructType>(EltTy)->getNumElements() == 3;
1362 std::remove_if(SrcElements.begin(), SrcElements.end(),
1363 [this](Constant *E) {
1364 auto *Key = dyn_cast<GlobalValue>(
1365 E->getAggregateElement(2)->stripPointerCasts());
1366 return DoNotLinkFromSource.count(Key);
1369 uint64_t NewSize = DstElements.size() + SrcElements.size();
1370 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
1372 // Create the new global variable.
1373 GlobalVariable *NG = new GlobalVariable(
1374 DstM, NewType, SrcGV->isConstant(), SrcGV->getLinkage(),
1375 /*init*/ nullptr, /*name*/ "", DstGV, SrcGV->getThreadLocalMode(),
1376 SrcGV->getType()->getAddressSpace());
1378 // Propagate alignment, visibility and section info.
1379 copyGVAttributes(NG, SrcGV);
1381 // Replace any uses of the two global variables with uses of the new
1383 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
1385 for (auto *V : SrcElements) {
1386 DstElements.push_back(
1387 MapValue(V, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1390 NG->setInitializer(ConstantArray::get(NewType, DstElements));
1393 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
1394 DstGV->eraseFromParent();
1400 bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) {
1401 GlobalValue *DGV = getLinkedToGlobal(SGV);
1403 // Handle the ultra special appending linkage case first.
1404 assert(!DGV || SGV->hasAppendingLinkage() == DGV->hasAppendingLinkage());
1405 if (SGV->hasAppendingLinkage() && isPerformingImport()) {
1406 // Don't want to append to global_ctors list, for example, when we
1407 // are importing for ThinLTO, otherwise the global ctors and dtors
1408 // get executed multiple times for local variables (the latter causing
1410 DoNotLinkFromSource.insert(SGV);
1413 if (SGV->hasAppendingLinkage())
1414 return linkAppendingVarProto(cast_or_null<GlobalVariable>(DGV),
1415 cast<GlobalVariable>(SGV));
1417 bool LinkFromSrc = true;
1418 Comdat *C = nullptr;
1419 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
1421 if (const Comdat *SC = SGV->getComdat()) {
1422 Comdat::SelectionKind SK;
1423 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1424 C = DstM.getOrInsertComdat(SC->getName());
1425 C->setSelectionKind(SK);
1426 if (SGV->hasInternalLinkage())
1429 if (shouldLinkFromSource(LinkFromSrc, *DGV, *SGV))
1434 // Track the source global so that we don't attempt to copy it over when
1435 // processing global initializers.
1436 DoNotLinkFromSource.insert(SGV);
1439 // Make sure to remember this mapping.
1441 ConstantExpr::getBitCast(DGV, TypeMap.get(SGV->getType()));
1445 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1448 if (!LinkFromSrc && DGV) {
1450 // When linking from source we setVisibility from copyGlobalValueProto.
1451 setVisibility(NewGV, SGV, DGV);
1453 NewGV = copyGlobalValueProto(TypeMap, SGV, DGV);
1455 if (isPerformingImport() && !doImportAsDefinition(SGV))
1456 DoNotLinkFromSource.insert(SGV);
1459 NewGV->setUnnamedAddr(HasUnnamedAddr);
1461 if (auto *NewGO = dyn_cast<GlobalObject>(NewGV)) {
1462 if (C && LinkFromSrc)
1463 NewGO->setComdat(C);
1465 if (DGV && DGV->hasCommonLinkage() && SGV->hasCommonLinkage())
1466 NewGO->setAlignment(std::max(DGV->getAlignment(), SGV->getAlignment()));
1469 if (auto *NewGVar = dyn_cast<GlobalVariable>(NewGV)) {
1470 auto *DGVar = dyn_cast_or_null<GlobalVariable>(DGV);
1471 auto *SGVar = dyn_cast<GlobalVariable>(SGV);
1472 if (DGVar && SGVar && DGVar->isDeclaration() && SGVar->isDeclaration() &&
1473 (!DGVar->isConstant() || !SGVar->isConstant()))
1474 NewGVar->setConstant(false);
1477 // Make sure to remember this mapping.
1480 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewGV, DGV->getType()));
1481 DGV->eraseFromParent();
1483 ValueMap[SGV] = NewGV;
1489 /// Update the initializers in the Dest module now that all globals that may be
1490 /// referenced are in Dest.
1491 void ModuleLinker::linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src) {
1492 // Figure out what the initializer looks like in the dest module.
1493 Dst.setInitializer(MapValue(Src.getInitializer(), ValueMap,
1494 RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1497 /// Copy the source function over into the dest function and fix up references
1498 /// to values. At this point we know that Dest is an external function, and
1499 /// that Src is not.
1500 bool ModuleLinker::linkFunctionBody(Function &Dst, Function &Src) {
1501 assert(Dst.isDeclaration() && !Src.isDeclaration());
1503 // Materialize if needed.
1504 if (std::error_code EC = Src.materialize())
1505 return emitError(EC.message());
1507 // Link in the prefix data.
1508 if (Src.hasPrefixData())
1509 Dst.setPrefixData(MapValue(Src.getPrefixData(), ValueMap,
1510 RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1512 // Link in the prologue data.
1513 if (Src.hasPrologueData())
1514 Dst.setPrologueData(MapValue(Src.getPrologueData(), ValueMap,
1515 RF_MoveDistinctMDs, &TypeMap,
1518 // Link in the personality function.
1519 if (Src.hasPersonalityFn())
1520 Dst.setPersonalityFn(MapValue(Src.getPersonalityFn(), ValueMap,
1521 RF_MoveDistinctMDs, &TypeMap,
1524 // Go through and convert function arguments over, remembering the mapping.
1525 Function::arg_iterator DI = Dst.arg_begin();
1526 for (Argument &Arg : Src.args()) {
1527 DI->setName(Arg.getName()); // Copy the name over.
1529 // Add a mapping to our mapping.
1530 ValueMap[&Arg] = &*DI;
1534 // Copy over the metadata attachments.
1535 SmallVector<std::pair<unsigned, MDNode *>, 8> MDs;
1536 Src.getAllMetadata(MDs);
1537 for (const auto &I : MDs)
1538 Dst.setMetadata(I.first, MapMetadata(I.second, ValueMap, RF_MoveDistinctMDs,
1539 &TypeMap, &ValMaterializer));
1541 // Splice the body of the source function into the dest function.
1542 Dst.getBasicBlockList().splice(Dst.end(), Src.getBasicBlockList());
1544 // At this point, all of the instructions and values of the function are now
1545 // copied over. The only problem is that they are still referencing values in
1546 // the Source function as operands. Loop through all of the operands of the
1547 // functions and patch them up to point to the local versions.
1548 for (BasicBlock &BB : Dst)
1549 for (Instruction &I : BB)
1550 RemapInstruction(&I, ValueMap,
1551 RF_IgnoreMissingEntries | RF_MoveDistinctMDs, &TypeMap,
1554 // There is no need to map the arguments anymore.
1555 for (Argument &Arg : Src.args())
1556 ValueMap.erase(&Arg);
1558 Src.dematerialize();
1562 void ModuleLinker::linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src) {
1563 Constant *Aliasee = Src.getAliasee();
1564 Constant *Val = MapValue(Aliasee, ValueMap, RF_MoveDistinctMDs, &TypeMap,
1566 Dst.setAliasee(Val);
1569 bool ModuleLinker::linkGlobalValueBody(GlobalValue &Dst, GlobalValue &Src) {
1570 if (const Comdat *SC = Src.getComdat()) {
1571 // To ensure that we don't generate an incomplete comdat group,
1572 // we must materialize and map in any other members that are not
1573 // yet materialized in Dst, which also ensures their definitions
1574 // are linked in. Otherwise, linkonce and other lazy linked GVs will
1575 // not be materialized if they aren't referenced.
1576 for (auto *SGV : ComdatMembers[SC]) {
1577 auto *DGV = cast_or_null<GlobalValue>(ValueMap[SGV]);
1578 if (DGV && !DGV->isDeclaration())
1580 MapValue(SGV, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer);
1583 if (shouldInternalizeLinkedSymbols())
1584 if (auto *DGV = dyn_cast<GlobalValue>(&Dst))
1585 DGV->setLinkage(GlobalValue::InternalLinkage);
1586 if (auto *F = dyn_cast<Function>(&Src))
1587 return linkFunctionBody(cast<Function>(Dst), *F);
1588 if (auto *GVar = dyn_cast<GlobalVariable>(&Src)) {
1589 linkGlobalInit(cast<GlobalVariable>(Dst), *GVar);
1592 linkAliasBody(cast<GlobalAlias>(Dst), cast<GlobalAlias>(Src));
1596 /// Insert all of the named MDNodes in Src into the Dest module.
1597 void ModuleLinker::linkNamedMDNodes() {
1598 const NamedMDNode *SrcModFlags = SrcM.getModuleFlagsMetadata();
1599 for (const NamedMDNode &NMD : SrcM.named_metadata()) {
1600 // Don't link module flags here. Do them separately.
1601 if (&NMD == SrcModFlags)
1603 NamedMDNode *DestNMD = DstM.getOrInsertNamedMetadata(NMD.getName());
1604 // Add Src elements into Dest node.
1605 for (const MDNode *op : NMD.operands())
1606 DestNMD->addOperand(MapMetadata(
1607 op, ValueMap, RF_MoveDistinctMDs | RF_NullMapMissingGlobalValues,
1608 &TypeMap, &ValMaterializer));
1612 /// Merge the linker flags in Src into the Dest module.
1613 bool ModuleLinker::linkModuleFlagsMetadata() {
1614 // If the source module has no module flags, we are done.
1615 const NamedMDNode *SrcModFlags = SrcM.getModuleFlagsMetadata();
1619 // If the destination module doesn't have module flags yet, then just copy
1620 // over the source module's flags.
1621 NamedMDNode *DstModFlags = DstM.getOrInsertModuleFlagsMetadata();
1622 if (DstModFlags->getNumOperands() == 0) {
1623 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1624 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1629 // First build a map of the existing module flags and requirements.
1630 DenseMap<MDString *, std::pair<MDNode *, unsigned>> Flags;
1631 SmallSetVector<MDNode *, 16> Requirements;
1632 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1633 MDNode *Op = DstModFlags->getOperand(I);
1634 ConstantInt *Behavior = mdconst::extract<ConstantInt>(Op->getOperand(0));
1635 MDString *ID = cast<MDString>(Op->getOperand(1));
1637 if (Behavior->getZExtValue() == Module::Require) {
1638 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1640 Flags[ID] = std::make_pair(Op, I);
1644 // Merge in the flags from the source module, and also collect its set of
1646 bool HasErr = false;
1647 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1648 MDNode *SrcOp = SrcModFlags->getOperand(I);
1649 ConstantInt *SrcBehavior =
1650 mdconst::extract<ConstantInt>(SrcOp->getOperand(0));
1651 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1654 std::tie(DstOp, DstIndex) = Flags.lookup(ID);
1655 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1657 // If this is a requirement, add it and continue.
1658 if (SrcBehaviorValue == Module::Require) {
1659 // If the destination module does not already have this requirement, add
1661 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1662 DstModFlags->addOperand(SrcOp);
1667 // If there is no existing flag with this ID, just add it.
1669 Flags[ID] = std::make_pair(SrcOp, DstModFlags->getNumOperands());
1670 DstModFlags->addOperand(SrcOp);
1674 // Otherwise, perform a merge.
1675 ConstantInt *DstBehavior =
1676 mdconst::extract<ConstantInt>(DstOp->getOperand(0));
1677 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1679 // If either flag has override behavior, handle it first.
1680 if (DstBehaviorValue == Module::Override) {
1681 // Diagnose inconsistent flags which both have override behavior.
1682 if (SrcBehaviorValue == Module::Override &&
1683 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1684 HasErr |= emitError("linking module flags '" + ID->getString() +
1685 "': IDs have conflicting override values");
1688 } else if (SrcBehaviorValue == Module::Override) {
1689 // Update the destination flag to that of the source.
1690 DstModFlags->setOperand(DstIndex, SrcOp);
1691 Flags[ID].first = SrcOp;
1695 // Diagnose inconsistent merge behavior types.
1696 if (SrcBehaviorValue != DstBehaviorValue) {
1697 HasErr |= emitError("linking module flags '" + ID->getString() +
1698 "': IDs have conflicting behaviors");
1702 auto replaceDstValue = [&](MDNode *New) {
1703 Metadata *FlagOps[] = {DstOp->getOperand(0), ID, New};
1704 MDNode *Flag = MDNode::get(DstM.getContext(), FlagOps);
1705 DstModFlags->setOperand(DstIndex, Flag);
1706 Flags[ID].first = Flag;
1709 // Perform the merge for standard behavior types.
1710 switch (SrcBehaviorValue) {
1711 case Module::Require:
1712 case Module::Override:
1713 llvm_unreachable("not possible");
1714 case Module::Error: {
1715 // Emit an error if the values differ.
1716 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1717 HasErr |= emitError("linking module flags '" + ID->getString() +
1718 "': IDs have conflicting values");
1722 case Module::Warning: {
1723 // Emit a warning if the values differ.
1724 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1725 emitWarning("linking module flags '" + ID->getString() +
1726 "': IDs have conflicting values");
1730 case Module::Append: {
1731 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1732 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1733 SmallVector<Metadata *, 8> MDs;
1734 MDs.reserve(DstValue->getNumOperands() + SrcValue->getNumOperands());
1735 MDs.append(DstValue->op_begin(), DstValue->op_end());
1736 MDs.append(SrcValue->op_begin(), SrcValue->op_end());
1738 replaceDstValue(MDNode::get(DstM.getContext(), MDs));
1741 case Module::AppendUnique: {
1742 SmallSetVector<Metadata *, 16> Elts;
1743 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1744 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1745 Elts.insert(DstValue->op_begin(), DstValue->op_end());
1746 Elts.insert(SrcValue->op_begin(), SrcValue->op_end());
1748 replaceDstValue(MDNode::get(DstM.getContext(),
1749 makeArrayRef(Elts.begin(), Elts.end())));
1755 // Check all of the requirements.
1756 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1757 MDNode *Requirement = Requirements[I];
1758 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1759 Metadata *ReqValue = Requirement->getOperand(1);
1761 MDNode *Op = Flags[Flag].first;
1762 if (!Op || Op->getOperand(2) != ReqValue) {
1763 HasErr |= emitError("linking module flags '" + Flag->getString() +
1764 "': does not have the required value");
1772 // This function returns true if the triples match.
1773 static bool triplesMatch(const Triple &T0, const Triple &T1) {
1774 // If vendor is apple, ignore the version number.
1775 if (T0.getVendor() == Triple::Apple)
1776 return T0.getArch() == T1.getArch() && T0.getSubArch() == T1.getSubArch() &&
1777 T0.getVendor() == T1.getVendor() && T0.getOS() == T1.getOS();
1782 // This function returns the merged triple.
1783 static std::string mergeTriples(const Triple &SrcTriple,
1784 const Triple &DstTriple) {
1785 // If vendor is apple, pick the triple with the larger version number.
1786 if (SrcTriple.getVendor() == Triple::Apple)
1787 if (DstTriple.isOSVersionLT(SrcTriple))
1788 return SrcTriple.str();
1790 return DstTriple.str();
1793 bool ModuleLinker::linkIfNeeded(GlobalValue &GV) {
1794 GlobalValue *DGV = getLinkedToGlobal(&GV);
1796 if (shouldLinkOnlyNeeded() && !(DGV && DGV->isDeclaration()))
1799 if (DGV && !GV.hasLocalLinkage()) {
1800 GlobalValue::VisibilityTypes Visibility =
1801 getMinVisibility(DGV->getVisibility(), GV.getVisibility());
1802 DGV->setVisibility(Visibility);
1803 GV.setVisibility(Visibility);
1806 if (const Comdat *SC = GV.getComdat()) {
1808 Comdat::SelectionKind SK;
1809 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1811 DoNotLinkFromSource.insert(&GV);
1816 if (!DGV && !shouldOverrideFromSrc() &&
1817 (GV.hasLocalLinkage() || GV.hasLinkOnceLinkage() ||
1818 GV.hasAvailableExternallyLinkage())) {
1821 MapValue(&GV, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer);
1825 bool ModuleLinker::run() {
1826 // Inherit the target data from the source module if the destination module
1827 // doesn't have one already.
1828 if (DstM.getDataLayout().isDefault())
1829 DstM.setDataLayout(SrcM.getDataLayout());
1831 if (SrcM.getDataLayout() != DstM.getDataLayout()) {
1832 emitWarning("Linking two modules of different data layouts: '" +
1833 SrcM.getModuleIdentifier() + "' is '" +
1834 SrcM.getDataLayoutStr() + "' whereas '" +
1835 DstM.getModuleIdentifier() + "' is '" +
1836 DstM.getDataLayoutStr() + "'\n");
1839 // Copy the target triple from the source to dest if the dest's is empty.
1840 if (DstM.getTargetTriple().empty() && !SrcM.getTargetTriple().empty())
1841 DstM.setTargetTriple(SrcM.getTargetTriple());
1843 Triple SrcTriple(SrcM.getTargetTriple()), DstTriple(DstM.getTargetTriple());
1845 if (!SrcM.getTargetTriple().empty() && !triplesMatch(SrcTriple, DstTriple))
1846 emitWarning("Linking two modules of different target triples: " +
1847 SrcM.getModuleIdentifier() + "' is '" + SrcM.getTargetTriple() +
1848 "' whereas '" + DstM.getModuleIdentifier() + "' is '" +
1849 DstM.getTargetTriple() + "'\n");
1851 DstM.setTargetTriple(mergeTriples(SrcTriple, DstTriple));
1853 // Append the module inline asm string.
1854 if (!SrcM.getModuleInlineAsm().empty()) {
1855 if (DstM.getModuleInlineAsm().empty())
1856 DstM.setModuleInlineAsm(SrcM.getModuleInlineAsm());
1858 DstM.setModuleInlineAsm(DstM.getModuleInlineAsm() + "\n" +
1859 SrcM.getModuleInlineAsm());
1862 // Loop over all of the linked values to compute type mappings.
1863 computeTypeMapping();
1865 ComdatsChosen.clear();
1866 for (const auto &SMEC : SrcM.getComdatSymbolTable()) {
1867 const Comdat &C = SMEC.getValue();
1868 if (ComdatsChosen.count(&C))
1870 Comdat::SelectionKind SK;
1872 if (getComdatResult(&C, SK, LinkFromSrc))
1874 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1877 // Upgrade mismatched global arrays.
1878 upgradeMismatchedGlobals();
1880 for (GlobalVariable &GV : SrcM.globals())
1881 if (const Comdat *SC = GV.getComdat())
1882 ComdatMembers[SC].push_back(&GV);
1884 for (Function &SF : SrcM)
1885 if (const Comdat *SC = SF.getComdat())
1886 ComdatMembers[SC].push_back(&SF);
1888 for (GlobalAlias &GA : SrcM.aliases())
1889 if (const Comdat *SC = GA.getComdat())
1890 ComdatMembers[SC].push_back(&GA);
1892 // Insert all of the globals in src into the DstM module... without linking
1893 // initializers (which could refer to functions not yet mapped over).
1894 for (GlobalVariable &GV : SrcM.globals())
1895 if (linkIfNeeded(GV))
1898 for (Function &SF : SrcM)
1899 if (linkIfNeeded(SF))
1902 for (GlobalAlias &GA : SrcM.aliases())
1903 if (linkIfNeeded(GA))
1906 for (const auto &Entry : DstM.getComdatSymbolTable()) {
1907 const Comdat &C = Entry.getValue();
1908 if (C.getSelectionKind() == Comdat::Any)
1910 const GlobalValue *GV = SrcM.getNamedValue(C.getName());
1912 MapValue(GV, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer);
1915 // Note that we are done linking global value bodies. This prevents
1916 // metadata linking from creating new references.
1917 DoneLinkingBodies = true;
1919 // Remap all of the named MDNodes in Src into the DstM module. We do this
1920 // after linking GlobalValues so that MDNodes that reference GlobalValues
1921 // are properly remapped.
1924 // Merge the module flags into the DstM module.
1925 if (linkModuleFlagsMetadata())
1931 Linker::StructTypeKeyInfo::KeyTy::KeyTy(ArrayRef<Type *> E, bool P)
1932 : ETypes(E), IsPacked(P) {}
1934 Linker::StructTypeKeyInfo::KeyTy::KeyTy(const StructType *ST)
1935 : ETypes(ST->elements()), IsPacked(ST->isPacked()) {}
1937 bool Linker::StructTypeKeyInfo::KeyTy::operator==(const KeyTy &That) const {
1938 if (IsPacked != That.IsPacked)
1940 if (ETypes != That.ETypes)
1945 bool Linker::StructTypeKeyInfo::KeyTy::operator!=(const KeyTy &That) const {
1946 return !this->operator==(That);
1949 StructType *Linker::StructTypeKeyInfo::getEmptyKey() {
1950 return DenseMapInfo<StructType *>::getEmptyKey();
1953 StructType *Linker::StructTypeKeyInfo::getTombstoneKey() {
1954 return DenseMapInfo<StructType *>::getTombstoneKey();
1957 unsigned Linker::StructTypeKeyInfo::getHashValue(const KeyTy &Key) {
1958 return hash_combine(hash_combine_range(Key.ETypes.begin(), Key.ETypes.end()),
1962 unsigned Linker::StructTypeKeyInfo::getHashValue(const StructType *ST) {
1963 return getHashValue(KeyTy(ST));
1966 bool Linker::StructTypeKeyInfo::isEqual(const KeyTy &LHS,
1967 const StructType *RHS) {
1968 if (RHS == getEmptyKey() || RHS == getTombstoneKey())
1970 return LHS == KeyTy(RHS);
1973 bool Linker::StructTypeKeyInfo::isEqual(const StructType *LHS,
1974 const StructType *RHS) {
1975 if (RHS == getEmptyKey())
1976 return LHS == getEmptyKey();
1978 if (RHS == getTombstoneKey())
1979 return LHS == getTombstoneKey();
1981 return KeyTy(LHS) == KeyTy(RHS);
1984 void Linker::IdentifiedStructTypeSet::addNonOpaque(StructType *Ty) {
1985 assert(!Ty->isOpaque());
1986 NonOpaqueStructTypes.insert(Ty);
1989 void Linker::IdentifiedStructTypeSet::switchToNonOpaque(StructType *Ty) {
1990 assert(!Ty->isOpaque());
1991 NonOpaqueStructTypes.insert(Ty);
1992 bool Removed = OpaqueStructTypes.erase(Ty);
1997 void Linker::IdentifiedStructTypeSet::addOpaque(StructType *Ty) {
1998 assert(Ty->isOpaque());
1999 OpaqueStructTypes.insert(Ty);
2003 Linker::IdentifiedStructTypeSet::findNonOpaque(ArrayRef<Type *> ETypes,
2005 Linker::StructTypeKeyInfo::KeyTy Key(ETypes, IsPacked);
2006 auto I = NonOpaqueStructTypes.find_as(Key);
2007 if (I == NonOpaqueStructTypes.end())
2012 bool Linker::IdentifiedStructTypeSet::hasType(StructType *Ty) {
2014 return OpaqueStructTypes.count(Ty);
2015 auto I = NonOpaqueStructTypes.find(Ty);
2016 if (I == NonOpaqueStructTypes.end())
2021 Linker::Linker(Module &M, DiagnosticHandlerFunction DiagnosticHandler)
2022 : Composite(M), DiagnosticHandler(DiagnosticHandler) {
2023 TypeFinder StructTypes;
2024 StructTypes.run(M, true);
2025 for (StructType *Ty : StructTypes) {
2027 IdentifiedStructTypes.addOpaque(Ty);
2029 IdentifiedStructTypes.addNonOpaque(Ty);
2033 Linker::Linker(Module &M)
2034 : Linker(M, [this](const DiagnosticInfo &DI) {
2035 Composite.getContext().diagnose(DI);
2038 bool Linker::linkInModule(Module &Src, unsigned Flags,
2039 const FunctionInfoIndex *Index,
2040 Function *FuncToImport) {
2041 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,
2042 DiagnosticHandler, Flags, Index, FuncToImport);
2043 bool RetCode = TheLinker.run();
2044 Composite.dropTriviallyDeadConstantArrays();
2048 //===----------------------------------------------------------------------===//
2049 // LinkModules entrypoint.
2050 //===----------------------------------------------------------------------===//
2052 /// This function links two modules together, with the resulting Dest module
2053 /// modified to be the composite of the two input modules. If an error occurs,
2054 /// true is returned and ErrorMsg (if not null) is set to indicate the problem.
2055 /// Upon failure, the Dest module could be in a modified state, and shouldn't be
2056 /// relied on to be consistent.
2057 bool Linker::linkModules(Module &Dest, Module &Src,
2058 DiagnosticHandlerFunction DiagnosticHandler,
2060 Linker L(Dest, DiagnosticHandler);
2061 return L.linkInModule(Src, Flags);
2064 bool Linker::linkModules(Module &Dest, Module &Src, unsigned Flags) {
2066 return L.linkInModule(Src, Flags);
2069 //===----------------------------------------------------------------------===//
2071 //===----------------------------------------------------------------------===//
2073 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
2074 LLVMLinkerMode Unused, char **OutMessages) {
2075 Module *D = unwrap(Dest);
2076 std::string Message;
2077 raw_string_ostream Stream(Message);
2078 DiagnosticPrinterRawOStream DP(Stream);
2080 LLVMBool Result = Linker::linkModules(
2081 *D, *unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); });
2083 if (OutMessages && Result) {
2085 *OutMessages = strdup(Message.c_str());