1 //===- lib/Linker/LinkModules.cpp - Module Linker Implementation ----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the LLVM module linker.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Linker/Linker.h"
15 #include "llvm-c/Linker.h"
16 #include "llvm/ADT/Hashing.h"
17 #include "llvm/ADT/Optional.h"
18 #include "llvm/ADT/SetVector.h"
19 #include "llvm/ADT/SmallString.h"
20 #include "llvm/ADT/Statistic.h"
21 #include "llvm/ADT/Triple.h"
22 #include "llvm/IR/Constants.h"
23 #include "llvm/IR/DebugInfo.h"
24 #include "llvm/IR/DiagnosticInfo.h"
25 #include "llvm/IR/DiagnosticPrinter.h"
26 #include "llvm/IR/LLVMContext.h"
27 #include "llvm/IR/Module.h"
28 #include "llvm/IR/TypeFinder.h"
29 #include "llvm/Support/CommandLine.h"
30 #include "llvm/Support/Debug.h"
31 #include "llvm/Support/raw_ostream.h"
32 #include "llvm/Transforms/Utils/Cloning.h"
38 //===----------------------------------------------------------------------===//
39 // TypeMap implementation.
40 //===----------------------------------------------------------------------===//
43 class TypeMapTy : public ValueMapTypeRemapper {
44 /// This is a mapping from a source type to a destination type to use.
45 DenseMap<Type*, Type*> MappedTypes;
47 /// When checking to see if two subgraphs are isomorphic, we speculatively
48 /// add types to MappedTypes, but keep track of them here in case we need to
50 SmallVector<Type*, 16> SpeculativeTypes;
52 SmallVector<StructType*, 16> SpeculativeDstOpaqueTypes;
54 /// This is a list of non-opaque structs in the source module that are mapped
55 /// to an opaque struct in the destination module.
56 SmallVector<StructType*, 16> SrcDefinitionsToResolve;
58 /// This is the set of opaque types in the destination modules who are
59 /// getting a body from the source module.
60 SmallPtrSet<StructType*, 16> DstResolvedOpaqueTypes;
63 TypeMapTy(Linker::IdentifiedStructTypeSet &DstStructTypesSet)
64 : DstStructTypesSet(DstStructTypesSet) {}
66 Linker::IdentifiedStructTypeSet &DstStructTypesSet;
67 /// Indicate that the specified type in the destination module is conceptually
68 /// equivalent to the specified type in the source module.
69 void addTypeMapping(Type *DstTy, Type *SrcTy);
71 /// Produce a body for an opaque type in the dest module from a type
72 /// definition in the source module.
73 void linkDefinedTypeBodies();
75 /// Return the mapped type to use for the specified input type from the
77 Type *get(Type *SrcTy);
78 Type *get(Type *SrcTy, SmallPtrSet<StructType *, 8> &Visited);
80 void finishType(StructType *DTy, StructType *STy, ArrayRef<Type *> ETypes);
82 FunctionType *get(FunctionType *T) {
83 return cast<FunctionType>(get((Type *)T));
86 /// Dump out the type map for debugging purposes.
88 for (auto &Pair : MappedTypes) {
89 dbgs() << "TypeMap: ";
90 Pair.first->print(dbgs());
92 Pair.second->print(dbgs());
98 Type *remapType(Type *SrcTy) override { return get(SrcTy); }
100 bool areTypesIsomorphic(Type *DstTy, Type *SrcTy);
104 void TypeMapTy::addTypeMapping(Type *DstTy, Type *SrcTy) {
105 assert(SpeculativeTypes.empty());
106 assert(SpeculativeDstOpaqueTypes.empty());
108 // Check to see if these types are recursively isomorphic and establish a
109 // mapping between them if so.
110 if (!areTypesIsomorphic(DstTy, SrcTy)) {
111 // Oops, they aren't isomorphic. Just discard this request by rolling out
112 // any speculative mappings we've established.
113 for (Type *Ty : SpeculativeTypes)
114 MappedTypes.erase(Ty);
116 SrcDefinitionsToResolve.resize(SrcDefinitionsToResolve.size() -
117 SpeculativeDstOpaqueTypes.size());
118 for (StructType *Ty : SpeculativeDstOpaqueTypes)
119 DstResolvedOpaqueTypes.erase(Ty);
121 for (Type *Ty : SpeculativeTypes)
122 if (auto *STy = dyn_cast<StructType>(Ty))
126 SpeculativeTypes.clear();
127 SpeculativeDstOpaqueTypes.clear();
130 /// Recursively walk this pair of types, returning true if they are isomorphic,
131 /// false if they are not.
132 bool TypeMapTy::areTypesIsomorphic(Type *DstTy, Type *SrcTy) {
133 // Two types with differing kinds are clearly not isomorphic.
134 if (DstTy->getTypeID() != SrcTy->getTypeID())
137 // If we have an entry in the MappedTypes table, then we have our answer.
138 Type *&Entry = MappedTypes[SrcTy];
140 return Entry == DstTy;
142 // Two identical types are clearly isomorphic. Remember this
143 // non-speculatively.
144 if (DstTy == SrcTy) {
149 // Okay, we have two types with identical kinds that we haven't seen before.
151 // If this is an opaque struct type, special case it.
152 if (StructType *SSTy = dyn_cast<StructType>(SrcTy)) {
153 // Mapping an opaque type to any struct, just keep the dest struct.
154 if (SSTy->isOpaque()) {
156 SpeculativeTypes.push_back(SrcTy);
160 // Mapping a non-opaque source type to an opaque dest. If this is the first
161 // type that we're mapping onto this destination type then we succeed. Keep
162 // the dest, but fill it in later. If this is the second (different) type
163 // that we're trying to map onto the same opaque type then we fail.
164 if (cast<StructType>(DstTy)->isOpaque()) {
165 // We can only map one source type onto the opaque destination type.
166 if (!DstResolvedOpaqueTypes.insert(cast<StructType>(DstTy)).second)
168 SrcDefinitionsToResolve.push_back(SSTy);
169 SpeculativeTypes.push_back(SrcTy);
170 SpeculativeDstOpaqueTypes.push_back(cast<StructType>(DstTy));
176 // If the number of subtypes disagree between the two types, then we fail.
177 if (SrcTy->getNumContainedTypes() != DstTy->getNumContainedTypes())
180 // Fail if any of the extra properties (e.g. array size) of the type disagree.
181 if (isa<IntegerType>(DstTy))
182 return false; // bitwidth disagrees.
183 if (PointerType *PT = dyn_cast<PointerType>(DstTy)) {
184 if (PT->getAddressSpace() != cast<PointerType>(SrcTy)->getAddressSpace())
187 } else if (FunctionType *FT = dyn_cast<FunctionType>(DstTy)) {
188 if (FT->isVarArg() != cast<FunctionType>(SrcTy)->isVarArg())
190 } else if (StructType *DSTy = dyn_cast<StructType>(DstTy)) {
191 StructType *SSTy = cast<StructType>(SrcTy);
192 if (DSTy->isLiteral() != SSTy->isLiteral() ||
193 DSTy->isPacked() != SSTy->isPacked())
195 } else if (ArrayType *DATy = dyn_cast<ArrayType>(DstTy)) {
196 if (DATy->getNumElements() != cast<ArrayType>(SrcTy)->getNumElements())
198 } else if (VectorType *DVTy = dyn_cast<VectorType>(DstTy)) {
199 if (DVTy->getNumElements() != cast<VectorType>(SrcTy)->getNumElements())
203 // Otherwise, we speculate that these two types will line up and recursively
204 // check the subelements.
206 SpeculativeTypes.push_back(SrcTy);
208 for (unsigned I = 0, E = SrcTy->getNumContainedTypes(); I != E; ++I)
209 if (!areTypesIsomorphic(DstTy->getContainedType(I),
210 SrcTy->getContainedType(I)))
213 // If everything seems to have lined up, then everything is great.
217 void TypeMapTy::linkDefinedTypeBodies() {
218 SmallVector<Type*, 16> Elements;
219 for (StructType *SrcSTy : SrcDefinitionsToResolve) {
220 StructType *DstSTy = cast<StructType>(MappedTypes[SrcSTy]);
221 assert(DstSTy->isOpaque());
223 // Map the body of the source type over to a new body for the dest type.
224 Elements.resize(SrcSTy->getNumElements());
225 for (unsigned I = 0, E = Elements.size(); I != E; ++I)
226 Elements[I] = get(SrcSTy->getElementType(I));
228 DstSTy->setBody(Elements, SrcSTy->isPacked());
229 DstStructTypesSet.switchToNonOpaque(DstSTy);
231 SrcDefinitionsToResolve.clear();
232 DstResolvedOpaqueTypes.clear();
235 void TypeMapTy::finishType(StructType *DTy, StructType *STy,
236 ArrayRef<Type *> ETypes) {
237 DTy->setBody(ETypes, STy->isPacked());
240 if (STy->hasName()) {
241 SmallString<16> TmpName = STy->getName();
243 DTy->setName(TmpName);
246 DstStructTypesSet.addNonOpaque(DTy);
249 Type *TypeMapTy::get(Type *Ty) {
250 SmallPtrSet<StructType *, 8> Visited;
251 return get(Ty, Visited);
254 Type *TypeMapTy::get(Type *Ty, SmallPtrSet<StructType *, 8> &Visited) {
255 // If we already have an entry for this type, return it.
256 Type **Entry = &MappedTypes[Ty];
260 // These are types that LLVM itself will unique.
261 bool IsUniqued = !isa<StructType>(Ty) || cast<StructType>(Ty)->isLiteral();
265 for (auto &Pair : MappedTypes) {
266 assert(!(Pair.first != Ty && Pair.second == Ty) &&
267 "mapping to a source type");
272 if (!IsUniqued && !Visited.insert(cast<StructType>(Ty)).second) {
273 StructType *DTy = StructType::create(Ty->getContext());
277 // If this is not a recursive type, then just map all of the elements and
278 // then rebuild the type from inside out.
279 SmallVector<Type *, 4> ElementTypes;
281 // If there are no element types to map, then the type is itself. This is
282 // true for the anonymous {} struct, things like 'float', integers, etc.
283 if (Ty->getNumContainedTypes() == 0 && IsUniqued)
286 // Remap all of the elements, keeping track of whether any of them change.
287 bool AnyChange = false;
288 ElementTypes.resize(Ty->getNumContainedTypes());
289 for (unsigned I = 0, E = Ty->getNumContainedTypes(); I != E; ++I) {
290 ElementTypes[I] = get(Ty->getContainedType(I), Visited);
291 AnyChange |= ElementTypes[I] != Ty->getContainedType(I);
294 // If we found our type while recursively processing stuff, just use it.
295 Entry = &MappedTypes[Ty];
297 if (auto *DTy = dyn_cast<StructType>(*Entry)) {
298 if (DTy->isOpaque()) {
299 auto *STy = cast<StructType>(Ty);
300 finishType(DTy, STy, ElementTypes);
306 // If all of the element types mapped directly over and the type is not
307 // a nomed struct, then the type is usable as-is.
308 if (!AnyChange && IsUniqued)
311 // Otherwise, rebuild a modified type.
312 switch (Ty->getTypeID()) {
314 llvm_unreachable("unknown derived type to remap");
315 case Type::ArrayTyID:
316 return *Entry = ArrayType::get(ElementTypes[0],
317 cast<ArrayType>(Ty)->getNumElements());
318 case Type::VectorTyID:
319 return *Entry = VectorType::get(ElementTypes[0],
320 cast<VectorType>(Ty)->getNumElements());
321 case Type::PointerTyID:
322 return *Entry = PointerType::get(ElementTypes[0],
323 cast<PointerType>(Ty)->getAddressSpace());
324 case Type::FunctionTyID:
325 return *Entry = FunctionType::get(ElementTypes[0],
326 makeArrayRef(ElementTypes).slice(1),
327 cast<FunctionType>(Ty)->isVarArg());
328 case Type::StructTyID: {
329 auto *STy = cast<StructType>(Ty);
330 bool IsPacked = STy->isPacked();
332 return *Entry = StructType::get(Ty->getContext(), ElementTypes, IsPacked);
334 // If the type is opaque, we can just use it directly.
335 if (STy->isOpaque()) {
336 DstStructTypesSet.addOpaque(STy);
340 if (StructType *OldT =
341 DstStructTypesSet.findNonOpaque(ElementTypes, IsPacked)) {
343 return *Entry = OldT;
347 DstStructTypesSet.addNonOpaque(STy);
351 StructType *DTy = StructType::create(Ty->getContext());
352 finishType(DTy, STy, ElementTypes);
358 //===----------------------------------------------------------------------===//
359 // ModuleLinker implementation.
360 //===----------------------------------------------------------------------===//
365 /// Creates prototypes for functions that are lazily linked on the fly. This
366 /// speeds up linking for modules with many/ lazily linked functions of which
368 class ValueMaterializerTy final : public ValueMaterializer {
369 ModuleLinker *ModLinker;
372 ValueMaterializerTy(ModuleLinker *ModLinker) : ModLinker(ModLinker) {}
374 Value *materializeDeclFor(Value *V) override;
375 void materializeInitFor(GlobalValue *New, GlobalValue *Old) override;
378 class LinkDiagnosticInfo : public DiagnosticInfo {
382 LinkDiagnosticInfo(DiagnosticSeverity Severity, const Twine &Msg);
383 void print(DiagnosticPrinter &DP) const override;
385 LinkDiagnosticInfo::LinkDiagnosticInfo(DiagnosticSeverity Severity,
387 : DiagnosticInfo(DK_Linker, Severity), Msg(Msg) {}
388 void LinkDiagnosticInfo::print(DiagnosticPrinter &DP) const { DP << Msg; }
390 /// This is an implementation class for the LinkModules function, which is the
391 /// entrypoint for this file.
396 ValueMaterializerTy ValMaterializer;
398 /// Mapping of values from what they used to be in Src, to what they are now
399 /// in DstM. ValueToValueMapTy is a ValueMap, which involves some overhead
400 /// due to the use of Value handles which the Linker doesn't actually need,
401 /// but this allows us to reuse the ValueMapper code.
402 ValueToValueMapTy ValueMap;
404 // Set of items not to link in from source.
405 SmallPtrSet<const GlobalValue *, 16> DoNotLinkFromSource;
407 DiagnosticHandlerFunction DiagnosticHandler;
409 /// For symbol clashes, prefer those from Src.
412 /// Function index passed into ModuleLinker for using in function
413 /// importing/exporting handling.
414 const FunctionInfoIndex *ImportIndex;
416 /// Function to import from source module, all other functions are
417 /// imported as declarations instead of definitions.
418 Function *ImportFunction;
420 /// Set to true if the given FunctionInfoIndex contains any functions
421 /// from this source module, in which case we must conservatively assume
422 /// that any of its functions may be imported into another module
423 /// as part of a different backend compilation process.
424 bool HasExportedFunctions;
426 /// Set to true when all global value body linking is complete (including
427 /// lazy linking). Used to prevent metadata linking from creating new
429 bool DoneLinkingBodies;
431 bool HasError = false;
434 ModuleLinker(Module *dstM, Linker::IdentifiedStructTypeSet &Set, Module *srcM,
435 DiagnosticHandlerFunction DiagnosticHandler, unsigned Flags,
436 const FunctionInfoIndex *Index = nullptr,
437 Function *FuncToImport = nullptr)
438 : DstM(dstM), SrcM(srcM), TypeMap(Set), ValMaterializer(this),
439 DiagnosticHandler(DiagnosticHandler), Flags(Flags), ImportIndex(Index),
440 ImportFunction(FuncToImport), HasExportedFunctions(false),
441 DoneLinkingBodies(false) {
442 assert((ImportIndex || !ImportFunction) &&
443 "Expect a FunctionInfoIndex when importing");
444 // If we have a FunctionInfoIndex but no function to import,
445 // then this is the primary module being compiled in a ThinLTO
446 // backend compilation, and we need to see if it has functions that
447 // may be exported to another backend compilation.
448 if (ImportIndex && !ImportFunction)
449 HasExportedFunctions = ImportIndex->hasExportedFunctions(SrcM);
453 Value *materializeDeclFor(Value *V);
454 void materializeInitFor(GlobalValue *New, GlobalValue *Old);
457 bool shouldOverrideFromSrc() { return Flags & Linker::OverrideFromSrc; }
458 bool shouldLinkOnlyNeeded() { return Flags & Linker::LinkOnlyNeeded; }
459 bool shouldInternalizeLinkedSymbols() {
460 return Flags & Linker::InternalizeLinkedSymbols;
463 /// Handles cloning of a global values from the source module into
464 /// the destination module, including setting the attributes and visibility.
465 GlobalValue *copyGlobalValueProto(TypeMapTy &TypeMap, const GlobalValue *SGV,
466 const GlobalValue *DGV = nullptr);
468 /// Check if we should promote the given local value to global scope.
469 bool doPromoteLocalToGlobal(const GlobalValue *SGV);
471 /// Check if all global value body linking is complete.
472 bool doneLinkingBodies() { return DoneLinkingBodies; }
474 bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
475 const GlobalValue &Src);
477 /// Helper method for setting a message and returning an error code.
478 bool emitError(const Twine &Message) {
479 DiagnosticHandler(LinkDiagnosticInfo(DS_Error, Message));
484 void emitWarning(const Twine &Message) {
485 DiagnosticHandler(LinkDiagnosticInfo(DS_Warning, Message));
488 bool getComdatLeader(Module *M, StringRef ComdatName,
489 const GlobalVariable *&GVar);
490 bool computeResultingSelectionKind(StringRef ComdatName,
491 Comdat::SelectionKind Src,
492 Comdat::SelectionKind Dst,
493 Comdat::SelectionKind &Result,
495 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
497 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
499 // Keep track of the global value members of each comdat in source.
500 DenseMap<const Comdat *, std::vector<GlobalValue *>> ComdatMembers;
502 /// Given a global in the source module, return the global in the
503 /// destination module that is being linked to, if any.
504 GlobalValue *getLinkedToGlobal(const GlobalValue *SrcGV) {
505 // If the source has no name it can't link. If it has local linkage,
506 // there is no name match-up going on.
507 if (!SrcGV->hasName() || GlobalValue::isLocalLinkage(getLinkage(SrcGV)))
510 // Otherwise see if we have a match in the destination module's symtab.
511 GlobalValue *DGV = DstM->getNamedValue(getName(SrcGV));
515 // If we found a global with the same name in the dest module, but it has
516 // internal linkage, we are really not doing any linkage here.
517 if (DGV->hasLocalLinkage())
520 // Otherwise, we do in fact link to the destination global.
524 void computeTypeMapping();
526 void upgradeMismatchedGlobalArray(StringRef Name);
527 void upgradeMismatchedGlobals();
529 bool linkIfNeeded(GlobalValue &GV);
530 bool linkAppendingVarProto(GlobalVariable *DstGV,
531 const GlobalVariable *SrcGV);
533 bool linkGlobalValueProto(GlobalValue *GV);
534 bool linkModuleFlagsMetadata();
536 void linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src);
537 bool linkFunctionBody(Function &Dst, Function &Src);
538 void linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src);
539 bool linkGlobalValueBody(GlobalValue &Src);
541 /// Functions that take care of cloning a specific global value type
542 /// into the destination module.
543 GlobalVariable *copyGlobalVariableProto(TypeMapTy &TypeMap,
544 const GlobalVariable *SGVar);
545 Function *copyFunctionProto(TypeMapTy &TypeMap, const Function *SF);
546 GlobalValue *copyGlobalAliasProto(TypeMapTy &TypeMap, const GlobalAlias *SGA);
548 /// Helper methods to check if we are importing from or potentially
549 /// exporting from the current source module.
550 bool isPerformingImport() { return ImportFunction != nullptr; }
551 bool isModuleExporting() { return HasExportedFunctions; }
553 /// If we are importing from the source module, checks if we should
554 /// import SGV as a definition, otherwise import as a declaration.
555 bool doImportAsDefinition(const GlobalValue *SGV);
557 /// Get the name for SGV that should be used in the linked destination
558 /// module. Specifically, this handles the case where we need to rename
559 /// a local that is being promoted to global scope.
560 std::string getName(const GlobalValue *SGV);
562 /// Get the new linkage for SGV that should be used in the linked destination
563 /// module. Specifically, for ThinLTO importing or exporting it may need
565 GlobalValue::LinkageTypes getLinkage(const GlobalValue *SGV);
567 /// Copies the necessary global value attributes and name from the source
568 /// to the newly cloned global value.
569 void copyGVAttributes(GlobalValue *NewGV, const GlobalValue *SrcGV);
571 /// Updates the visibility for the new global cloned from the source
572 /// and, if applicable, linked with an existing destination global.
573 /// Handles visibility change required for promoted locals.
574 void setVisibility(GlobalValue *NewGV, const GlobalValue *SGV,
575 const GlobalValue *DGV = nullptr);
577 void linkNamedMDNodes();
581 /// The LLVM SymbolTable class autorenames globals that conflict in the symbol
582 /// table. This is good for all clients except for us. Go through the trouble
583 /// to force this back.
584 static void forceRenaming(GlobalValue *GV, StringRef Name) {
585 // If the global doesn't force its name or if it already has the right name,
586 // there is nothing for us to do.
587 // Note that any required local to global promotion should already be done,
588 // so promoted locals will not skip this handling as their linkage is no
590 if (GV->hasLocalLinkage() || GV->getName() == Name)
593 Module *M = GV->getParent();
595 // If there is a conflict, rename the conflict.
596 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
597 GV->takeName(ConflictGV);
598 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
599 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
601 GV->setName(Name); // Force the name back
605 /// copy additional attributes (those not needed to construct a GlobalValue)
606 /// from the SrcGV to the DestGV.
607 void ModuleLinker::copyGVAttributes(GlobalValue *NewGV,
608 const GlobalValue *SrcGV) {
609 auto *GA = dyn_cast<GlobalAlias>(SrcGV);
610 // Check for the special case of converting an alias (definition) to a
611 // non-alias (declaration). This can happen when we are importing and
612 // encounter a weak_any alias (weak_any defs may not be imported, see
613 // comments in ModuleLinker::getLinkage) or an alias whose base object is
614 // being imported as a declaration. In that case copy the attributes from the
616 if (GA && !dyn_cast<GlobalAlias>(NewGV)) {
617 assert(isPerformingImport() && !doImportAsDefinition(GA));
618 NewGV->copyAttributesFrom(GA->getBaseObject());
620 NewGV->copyAttributesFrom(SrcGV);
621 forceRenaming(NewGV, getName(SrcGV));
624 bool ModuleLinker::doImportAsDefinition(const GlobalValue *SGV) {
625 if (!isPerformingImport())
627 auto *GA = dyn_cast<GlobalAlias>(SGV);
629 if (GA->hasWeakAnyLinkage())
631 const GlobalObject *GO = GA->getBaseObject();
632 if (!GO->hasLinkOnceODRLinkage())
634 return doImportAsDefinition(GO);
636 // Always import GlobalVariable definitions, except for the special
637 // case of WeakAny which are imported as ExternalWeak declarations
638 // (see comments in ModuleLinker::getLinkage). The linkage changes
639 // described in ModuleLinker::getLinkage ensure the correct behavior (e.g.
640 // global variables with external linkage are transformed to
641 // available_externally definitions, which are ultimately turned into
642 // declarations after the EliminateAvailableExternally pass).
643 if (isa<GlobalVariable>(SGV) && !SGV->isDeclaration() &&
644 !SGV->hasWeakAnyLinkage())
646 // Only import the function requested for importing.
647 auto *SF = dyn_cast<Function>(SGV);
648 if (SF && SF == ImportFunction)
654 bool ModuleLinker::doPromoteLocalToGlobal(const GlobalValue *SGV) {
655 assert(SGV->hasLocalLinkage());
656 // Both the imported references and the original local variable must
658 if (!isPerformingImport() && !isModuleExporting())
661 // Local const variables never need to be promoted unless they are address
662 // taken. The imported uses can simply use the clone created in this module.
663 // For now we are conservative in determining which variables are not
664 // address taken by checking the unnamed addr flag. To be more aggressive,
665 // the address taken information must be checked earlier during parsing
666 // of the module and recorded in the function index for use when importing
668 auto *GVar = dyn_cast<GlobalVariable>(SGV);
669 if (GVar && GVar->isConstant() && GVar->hasUnnamedAddr())
672 // Eventually we only need to promote functions in the exporting module that
673 // are referenced by a potentially exported function (i.e. one that is in the
678 std::string ModuleLinker::getName(const GlobalValue *SGV) {
679 // For locals that must be promoted to global scope, ensure that
680 // the promoted name uniquely identifies the copy in the original module,
681 // using the ID assigned during combined index creation. When importing,
682 // we rename all locals (not just those that are promoted) in order to
683 // avoid naming conflicts between locals imported from different modules.
684 if (SGV->hasLocalLinkage() &&
685 (doPromoteLocalToGlobal(SGV) || isPerformingImport()))
686 return FunctionInfoIndex::getGlobalNameForLocal(
688 ImportIndex->getModuleId(SGV->getParent()->getModuleIdentifier()));
689 return SGV->getName();
692 GlobalValue::LinkageTypes ModuleLinker::getLinkage(const GlobalValue *SGV) {
693 // Any local variable that is referenced by an exported function needs
694 // to be promoted to global scope. Since we don't currently know which
695 // functions reference which local variables/functions, we must treat
696 // all as potentially exported if this module is exporting anything.
697 if (isModuleExporting()) {
698 if (SGV->hasLocalLinkage() && doPromoteLocalToGlobal(SGV))
699 return GlobalValue::ExternalLinkage;
700 return SGV->getLinkage();
703 // Otherwise, if we aren't importing, no linkage change is needed.
704 if (!isPerformingImport())
705 return SGV->getLinkage();
707 switch (SGV->getLinkage()) {
708 case GlobalValue::ExternalLinkage:
709 // External defnitions are converted to available_externally
710 // definitions upon import, so that they are available for inlining
711 // and/or optimization, but are turned into declarations later
712 // during the EliminateAvailableExternally pass.
713 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
714 return GlobalValue::AvailableExternallyLinkage;
715 // An imported external declaration stays external.
716 return SGV->getLinkage();
718 case GlobalValue::AvailableExternallyLinkage:
719 // An imported available_externally definition converts
720 // to external if imported as a declaration.
721 if (!doImportAsDefinition(SGV))
722 return GlobalValue::ExternalLinkage;
723 // An imported available_externally declaration stays that way.
724 return SGV->getLinkage();
726 case GlobalValue::LinkOnceAnyLinkage:
727 case GlobalValue::LinkOnceODRLinkage:
728 // These both stay the same when importing the definition.
729 // The ThinLTO pass will eventually force-import their definitions.
730 return SGV->getLinkage();
732 case GlobalValue::WeakAnyLinkage:
733 // Can't import weak_any definitions correctly, or we might change the
734 // program semantics, since the linker will pick the first weak_any
735 // definition and importing would change the order they are seen by the
736 // linker. The module linking caller needs to enforce this.
737 assert(!doImportAsDefinition(SGV));
738 // If imported as a declaration, it becomes external_weak.
739 return GlobalValue::ExternalWeakLinkage;
741 case GlobalValue::WeakODRLinkage:
742 // For weak_odr linkage, there is a guarantee that all copies will be
743 // equivalent, so the issue described above for weak_any does not exist,
744 // and the definition can be imported. It can be treated similarly
745 // to an imported externally visible global value.
746 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
747 return GlobalValue::AvailableExternallyLinkage;
749 return GlobalValue::ExternalLinkage;
751 case GlobalValue::AppendingLinkage:
752 // It would be incorrect to import an appending linkage variable,
753 // since it would cause global constructors/destructors to be
754 // executed multiple times. This should have already been handled
755 // by linkGlobalValueProto.
756 llvm_unreachable("Cannot import appending linkage variable");
758 case GlobalValue::InternalLinkage:
759 case GlobalValue::PrivateLinkage:
760 // If we are promoting the local to global scope, it is handled
761 // similarly to a normal externally visible global.
762 if (doPromoteLocalToGlobal(SGV)) {
763 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
764 return GlobalValue::AvailableExternallyLinkage;
766 return GlobalValue::ExternalLinkage;
768 // A non-promoted imported local definition stays local.
769 // The ThinLTO pass will eventually force-import their definitions.
770 return SGV->getLinkage();
772 case GlobalValue::ExternalWeakLinkage:
773 // External weak doesn't apply to definitions, must be a declaration.
774 assert(!doImportAsDefinition(SGV));
775 // Linkage stays external_weak.
776 return SGV->getLinkage();
778 case GlobalValue::CommonLinkage:
779 // Linkage stays common on definitions.
780 // The ThinLTO pass will eventually force-import their definitions.
781 return SGV->getLinkage();
784 llvm_unreachable("unknown linkage type");
787 /// Loop through the global variables in the src module and merge them into the
790 ModuleLinker::copyGlobalVariableProto(TypeMapTy &TypeMap,
791 const GlobalVariable *SGVar) {
792 // No linking to be performed or linking from the source: simply create an
793 // identical version of the symbol over in the dest module... the
794 // initializer will be filled in later by LinkGlobalInits.
795 GlobalVariable *NewDGV = new GlobalVariable(
796 *DstM, TypeMap.get(SGVar->getType()->getElementType()),
797 SGVar->isConstant(), getLinkage(SGVar), /*init*/ nullptr, getName(SGVar),
798 /*insertbefore*/ nullptr, SGVar->getThreadLocalMode(),
799 SGVar->getType()->getAddressSpace());
804 /// Link the function in the source module into the destination module if
805 /// needed, setting up mapping information.
806 Function *ModuleLinker::copyFunctionProto(TypeMapTy &TypeMap,
807 const Function *SF) {
808 // If there is no linkage to be performed or we are linking from the source,
810 return Function::Create(TypeMap.get(SF->getFunctionType()), getLinkage(SF),
814 /// Set up prototypes for any aliases that come over from the source module.
815 GlobalValue *ModuleLinker::copyGlobalAliasProto(TypeMapTy &TypeMap,
816 const GlobalAlias *SGA) {
817 // If we are importing and encounter a weak_any alias, or an alias to
818 // an object being imported as a declaration, we must import the alias
819 // as a declaration as well, which involves converting it to a non-alias.
820 // See comments in ModuleLinker::getLinkage for why we cannot import
821 // weak_any defintions.
822 if (isPerformingImport() && !doImportAsDefinition(SGA)) {
823 // Need to convert to declaration. All aliases must be definitions.
824 const GlobalValue *GVal = SGA->getBaseObject();
826 if (auto *GVar = dyn_cast<GlobalVariable>(GVal))
827 NewGV = copyGlobalVariableProto(TypeMap, GVar);
829 auto *F = dyn_cast<Function>(GVal);
831 NewGV = copyFunctionProto(TypeMap, F);
833 // Set the linkage to External or ExternalWeak (see comments in
834 // ModuleLinker::getLinkage for why WeakAny is converted to ExternalWeak).
835 if (SGA->hasWeakAnyLinkage())
836 NewGV->setLinkage(GlobalValue::ExternalWeakLinkage);
838 NewGV->setLinkage(GlobalValue::ExternalLinkage);
841 // If there is no linkage to be performed or we're linking from the source,
843 auto *Ty = TypeMap.get(SGA->getValueType());
844 return GlobalAlias::create(Ty, SGA->getType()->getPointerAddressSpace(),
845 getLinkage(SGA), getName(SGA), DstM);
848 static GlobalValue::VisibilityTypes
849 getMinVisibility(GlobalValue::VisibilityTypes A,
850 GlobalValue::VisibilityTypes B) {
851 if (A == GlobalValue::HiddenVisibility || B == GlobalValue::HiddenVisibility)
852 return GlobalValue::HiddenVisibility;
853 if (A == GlobalValue::ProtectedVisibility ||
854 B == GlobalValue::ProtectedVisibility)
855 return GlobalValue::ProtectedVisibility;
856 return GlobalValue::DefaultVisibility;
859 void ModuleLinker::setVisibility(GlobalValue *NewGV, const GlobalValue *SGV,
860 const GlobalValue *DGV) {
861 GlobalValue::VisibilityTypes Visibility = SGV->getVisibility();
863 Visibility = getMinVisibility(DGV->getVisibility(), Visibility);
864 // For promoted locals, mark them hidden so that they can later be
865 // stripped from the symbol table to reduce bloat.
866 if (SGV->hasLocalLinkage() && doPromoteLocalToGlobal(SGV))
867 Visibility = GlobalValue::HiddenVisibility;
868 NewGV->setVisibility(Visibility);
871 GlobalValue *ModuleLinker::copyGlobalValueProto(TypeMapTy &TypeMap,
872 const GlobalValue *SGV,
873 const GlobalValue *DGV) {
875 if (auto *SGVar = dyn_cast<GlobalVariable>(SGV))
876 NewGV = copyGlobalVariableProto(TypeMap, SGVar);
877 else if (auto *SF = dyn_cast<Function>(SGV))
878 NewGV = copyFunctionProto(TypeMap, SF);
880 NewGV = copyGlobalAliasProto(TypeMap, cast<GlobalAlias>(SGV));
881 copyGVAttributes(NewGV, SGV);
882 setVisibility(NewGV, SGV, DGV);
886 Value *ValueMaterializerTy::materializeDeclFor(Value *V) {
887 return ModLinker->materializeDeclFor(V);
890 Value *ModuleLinker::materializeDeclFor(Value *V) {
891 auto *SGV = dyn_cast<GlobalValue>(V);
895 // If we are done linking global value bodies (i.e. we are performing
896 // metadata linking), don't link in the global value due to this
897 // reference, simply map it to null.
898 if (doneLinkingBodies())
901 linkGlobalValueProto(SGV);
904 Value *Ret = ValueMap[SGV];
909 void ValueMaterializerTy::materializeInitFor(GlobalValue *New,
911 return ModLinker->materializeInitFor(New, Old);
914 void ModuleLinker::materializeInitFor(GlobalValue *New, GlobalValue *Old) {
915 if (auto *F = dyn_cast<Function>(New)) {
916 if (!F->isDeclaration())
918 } else if (auto *V = dyn_cast<GlobalVariable>(New)) {
919 if (V->hasInitializer())
922 auto *A = cast<GlobalAlias>(New);
927 if (Old->isDeclaration())
930 if (isPerformingImport() && !doImportAsDefinition(Old))
933 if (!New->hasLocalLinkage() && DoNotLinkFromSource.count(Old))
936 linkGlobalValueBody(*Old);
939 bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName,
940 const GlobalVariable *&GVar) {
941 const GlobalValue *GVal = M->getNamedValue(ComdatName);
942 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
943 GVal = GA->getBaseObject();
945 // We cannot resolve the size of the aliasee yet.
946 return emitError("Linking COMDATs named '" + ComdatName +
947 "': COMDAT key involves incomputable alias size.");
950 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
953 "Linking COMDATs named '" + ComdatName +
954 "': GlobalVariable required for data dependent selection!");
959 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
960 Comdat::SelectionKind Src,
961 Comdat::SelectionKind Dst,
962 Comdat::SelectionKind &Result,
964 // The ability to mix Comdat::SelectionKind::Any with
965 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
966 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
967 Dst == Comdat::SelectionKind::Largest;
968 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
969 Src == Comdat::SelectionKind::Largest;
970 if (DstAnyOrLargest && SrcAnyOrLargest) {
971 if (Dst == Comdat::SelectionKind::Largest ||
972 Src == Comdat::SelectionKind::Largest)
973 Result = Comdat::SelectionKind::Largest;
975 Result = Comdat::SelectionKind::Any;
976 } else if (Src == Dst) {
979 return emitError("Linking COMDATs named '" + ComdatName +
980 "': invalid selection kinds!");
984 case Comdat::SelectionKind::Any:
988 case Comdat::SelectionKind::NoDuplicates:
989 return emitError("Linking COMDATs named '" + ComdatName +
990 "': noduplicates has been violated!");
991 case Comdat::SelectionKind::ExactMatch:
992 case Comdat::SelectionKind::Largest:
993 case Comdat::SelectionKind::SameSize: {
994 const GlobalVariable *DstGV;
995 const GlobalVariable *SrcGV;
996 if (getComdatLeader(DstM, ComdatName, DstGV) ||
997 getComdatLeader(SrcM, ComdatName, SrcGV))
1000 const DataLayout &DstDL = DstM->getDataLayout();
1001 const DataLayout &SrcDL = SrcM->getDataLayout();
1003 DstDL.getTypeAllocSize(DstGV->getType()->getPointerElementType());
1005 SrcDL.getTypeAllocSize(SrcGV->getType()->getPointerElementType());
1006 if (Result == Comdat::SelectionKind::ExactMatch) {
1007 if (SrcGV->getInitializer() != DstGV->getInitializer())
1008 return emitError("Linking COMDATs named '" + ComdatName +
1009 "': ExactMatch violated!");
1010 LinkFromSrc = false;
1011 } else if (Result == Comdat::SelectionKind::Largest) {
1012 LinkFromSrc = SrcSize > DstSize;
1013 } else if (Result == Comdat::SelectionKind::SameSize) {
1014 if (SrcSize != DstSize)
1015 return emitError("Linking COMDATs named '" + ComdatName +
1016 "': SameSize violated!");
1017 LinkFromSrc = false;
1019 llvm_unreachable("unknown selection kind");
1028 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
1029 Comdat::SelectionKind &Result,
1030 bool &LinkFromSrc) {
1031 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
1032 StringRef ComdatName = SrcC->getName();
1033 Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable();
1034 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
1036 if (DstCI == ComdatSymTab.end()) {
1037 // Use the comdat if it is only available in one of the modules.
1043 const Comdat *DstC = &DstCI->second;
1044 Comdat::SelectionKind DSK = DstC->getSelectionKind();
1045 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
1049 bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
1050 const GlobalValue &Dest,
1051 const GlobalValue &Src) {
1052 // Should we unconditionally use the Src?
1053 if (shouldOverrideFromSrc()) {
1058 // We always have to add Src if it has appending linkage.
1059 if (Src.hasAppendingLinkage()) {
1060 // Caller should have already determined that we can't link from source
1061 // when importing (see comments in linkGlobalValueProto).
1062 assert(!isPerformingImport());
1067 bool SrcIsDeclaration = Src.isDeclarationForLinker();
1068 bool DestIsDeclaration = Dest.isDeclarationForLinker();
1070 if (isPerformingImport()) {
1071 if (isa<Function>(&Src)) {
1072 // For functions, LinkFromSrc iff this is the function requested
1073 // for importing. For variables, decide below normally.
1074 LinkFromSrc = (&Src == ImportFunction);
1078 // Check if this is an alias with an already existing definition
1079 // in Dest, which must have come from a prior importing pass from
1080 // the same Src module. Unlike imported function and variable
1081 // definitions, which are imported as available_externally and are
1082 // not definitions for the linker, that is not a valid linkage for
1083 // imported aliases which must be definitions. Simply use the existing
1085 if (isa<GlobalAlias>(&Src) && !DestIsDeclaration) {
1086 assert(isa<GlobalAlias>(&Dest));
1087 LinkFromSrc = false;
1092 if (SrcIsDeclaration) {
1093 // If Src is external or if both Src & Dest are external.. Just link the
1094 // external globals, we aren't adding anything.
1095 if (Src.hasDLLImportStorageClass()) {
1096 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
1097 LinkFromSrc = DestIsDeclaration;
1100 // If the Dest is weak, use the source linkage.
1101 LinkFromSrc = Dest.hasExternalWeakLinkage();
1105 if (DestIsDeclaration) {
1106 // If Dest is external but Src is not:
1111 if (Src.hasCommonLinkage()) {
1112 if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
1117 if (!Dest.hasCommonLinkage()) {
1118 LinkFromSrc = false;
1122 const DataLayout &DL = Dest.getParent()->getDataLayout();
1123 uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
1124 uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
1125 LinkFromSrc = SrcSize > DestSize;
1129 if (Src.isWeakForLinker()) {
1130 assert(!Dest.hasExternalWeakLinkage());
1131 assert(!Dest.hasAvailableExternallyLinkage());
1133 if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
1138 LinkFromSrc = false;
1142 if (Dest.isWeakForLinker()) {
1143 assert(Src.hasExternalLinkage());
1148 assert(!Src.hasExternalWeakLinkage());
1149 assert(!Dest.hasExternalWeakLinkage());
1150 assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
1151 "Unexpected linkage type!");
1152 return emitError("Linking globals named '" + Src.getName() +
1153 "': symbol multiply defined!");
1156 /// Loop over all of the linked values to compute type mappings. For example,
1157 /// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct
1158 /// types 'Foo' but one got renamed when the module was loaded into the same
1160 void ModuleLinker::computeTypeMapping() {
1161 for (GlobalValue &SGV : SrcM->globals()) {
1162 GlobalValue *DGV = getLinkedToGlobal(&SGV);
1166 if (!DGV->hasAppendingLinkage() || !SGV.hasAppendingLinkage()) {
1167 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1171 // Unify the element type of appending arrays.
1172 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
1173 ArrayType *SAT = cast<ArrayType>(SGV.getType()->getElementType());
1174 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
1177 for (GlobalValue &SGV : *SrcM) {
1178 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
1179 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1182 for (GlobalValue &SGV : SrcM->aliases()) {
1183 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
1184 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1187 // Incorporate types by name, scanning all the types in the source module.
1188 // At this point, the destination module may have a type "%foo = { i32 }" for
1189 // example. When the source module got loaded into the same LLVMContext, if
1190 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
1191 std::vector<StructType *> Types = SrcM->getIdentifiedStructTypes();
1192 for (StructType *ST : Types) {
1196 // Check to see if there is a dot in the name followed by a digit.
1197 size_t DotPos = ST->getName().rfind('.');
1198 if (DotPos == 0 || DotPos == StringRef::npos ||
1199 ST->getName().back() == '.' ||
1200 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos + 1])))
1203 // Check to see if the destination module has a struct with the prefix name.
1204 StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos));
1208 // Don't use it if this actually came from the source module. They're in
1209 // the same LLVMContext after all. Also don't use it unless the type is
1210 // actually used in the destination module. This can happen in situations
1213 // Module A Module B
1214 // -------- --------
1215 // %Z = type { %A } %B = type { %C.1 }
1216 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
1217 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
1218 // %C = type { i8* } %B.3 = type { %C.1 }
1220 // When we link Module B with Module A, the '%B' in Module B is
1221 // used. However, that would then use '%C.1'. But when we process '%C.1',
1222 // we prefer to take the '%C' version. So we are then left with both
1223 // '%C.1' and '%C' being used for the same types. This leads to some
1224 // variables using one type and some using the other.
1225 if (TypeMap.DstStructTypesSet.hasType(DST))
1226 TypeMap.addTypeMapping(DST, ST);
1229 // Now that we have discovered all of the type equivalences, get a body for
1230 // any 'opaque' types in the dest module that are now resolved.
1231 TypeMap.linkDefinedTypeBodies();
1234 static void upgradeGlobalArray(GlobalVariable *GV) {
1235 ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
1236 StructType *OldTy = cast<StructType>(ATy->getElementType());
1237 assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
1239 // Get the upgraded 3 element type.
1240 PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
1241 Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
1243 StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
1245 // Build new constants with a null third field filled in.
1246 Constant *OldInitC = GV->getInitializer();
1247 ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
1248 if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
1249 // Invalid initializer; give up.
1251 std::vector<Constant *> Initializers;
1252 if (OldInit && OldInit->getNumOperands()) {
1253 Value *Null = Constant::getNullValue(VoidPtrTy);
1254 for (Use &U : OldInit->operands()) {
1255 ConstantStruct *Init = cast<ConstantStruct>(U.get());
1256 Initializers.push_back(ConstantStruct::get(
1257 NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
1260 assert(Initializers.size() == ATy->getNumElements() &&
1261 "Failed to copy all array elements");
1263 // Replace the old GV with a new one.
1264 ATy = ArrayType::get(NewTy, Initializers.size());
1265 Constant *NewInit = ConstantArray::get(ATy, Initializers);
1266 GlobalVariable *NewGV = new GlobalVariable(
1267 *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
1268 GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
1269 GV->isExternallyInitialized());
1270 NewGV->copyAttributesFrom(GV);
1271 NewGV->takeName(GV);
1272 assert(GV->use_empty() && "program cannot use initializer list");
1273 GV->eraseFromParent();
1276 void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
1277 // Look for the global arrays.
1278 auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM->getNamedValue(Name));
1281 auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM->getNamedValue(Name));
1285 // Check if the types already match.
1286 auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
1288 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
1292 // Grab the element types. We can only upgrade an array of a two-field
1293 // struct. Only bother if the other one has three-fields.
1294 auto *DstEltTy = cast<StructType>(DstTy->getElementType());
1295 auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
1296 if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
1297 upgradeGlobalArray(DstGV);
1300 if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
1301 upgradeGlobalArray(SrcGV);
1303 // We can't upgrade any other differences.
1306 void ModuleLinker::upgradeMismatchedGlobals() {
1307 upgradeMismatchedGlobalArray("llvm.global_ctors");
1308 upgradeMismatchedGlobalArray("llvm.global_dtors");
1311 static void getArrayElements(const Constant *C,
1312 SmallVectorImpl<Constant *> &Dest) {
1313 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1315 for (unsigned i = 0; i != NumElements; ++i)
1316 Dest.push_back(C->getAggregateElement(i));
1319 /// If there were any appending global variables, link them together now.
1320 /// Return true on error.
1321 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
1322 const GlobalVariable *SrcGV) {
1324 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
1325 Type *EltTy = SrcTy->getElementType();
1328 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
1330 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
1332 "Linking globals named '" + SrcGV->getName() +
1333 "': can only link appending global with another appending global!");
1335 // Check to see that they two arrays agree on type.
1336 if (EltTy != DstTy->getElementType())
1337 return emitError("Appending variables with different element types!");
1338 if (DstGV->isConstant() != SrcGV->isConstant())
1339 return emitError("Appending variables linked with different const'ness!");
1341 if (DstGV->getAlignment() != SrcGV->getAlignment())
1343 "Appending variables with different alignment need to be linked!");
1345 if (DstGV->getVisibility() != SrcGV->getVisibility())
1347 "Appending variables with different visibility need to be linked!");
1349 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
1351 "Appending variables with different unnamed_addr need to be linked!");
1353 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
1355 "Appending variables with different section name need to be linked!");
1358 SmallVector<Constant *, 16> DstElements;
1360 getArrayElements(DstGV->getInitializer(), DstElements);
1362 SmallVector<Constant *, 16> SrcElements;
1363 getArrayElements(SrcGV->getInitializer(), SrcElements);
1365 StringRef Name = SrcGV->getName();
1366 bool IsNewStructor =
1367 (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
1368 cast<StructType>(EltTy)->getNumElements() == 3;
1371 std::remove_if(SrcElements.begin(), SrcElements.end(),
1372 [this](Constant *E) {
1373 auto *Key = dyn_cast<GlobalValue>(
1374 E->getAggregateElement(2)->stripPointerCasts());
1375 return DoNotLinkFromSource.count(Key);
1378 uint64_t NewSize = DstElements.size() + SrcElements.size();
1379 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
1381 // Create the new global variable.
1382 GlobalVariable *NG = new GlobalVariable(
1383 *DstM, NewType, SrcGV->isConstant(), SrcGV->getLinkage(),
1384 /*init*/ nullptr, /*name*/ "", DstGV, SrcGV->getThreadLocalMode(),
1385 SrcGV->getType()->getAddressSpace());
1387 // Propagate alignment, visibility and section info.
1388 copyGVAttributes(NG, SrcGV);
1390 // Replace any uses of the two global variables with uses of the new
1392 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
1394 for (auto *V : SrcElements) {
1395 DstElements.push_back(
1396 MapValue(V, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1399 NG->setInitializer(ConstantArray::get(NewType, DstElements));
1402 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
1403 DstGV->eraseFromParent();
1409 bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) {
1410 GlobalValue *DGV = getLinkedToGlobal(SGV);
1412 // Handle the ultra special appending linkage case first.
1413 assert(!DGV || SGV->hasAppendingLinkage() == DGV->hasAppendingLinkage());
1414 if (SGV->hasAppendingLinkage() && isPerformingImport()) {
1415 // Don't want to append to global_ctors list, for example, when we
1416 // are importing for ThinLTO, otherwise the global ctors and dtors
1417 // get executed multiple times for local variables (the latter causing
1419 DoNotLinkFromSource.insert(SGV);
1422 if (SGV->hasAppendingLinkage())
1423 return linkAppendingVarProto(cast_or_null<GlobalVariable>(DGV),
1424 cast<GlobalVariable>(SGV));
1426 bool LinkFromSrc = true;
1427 Comdat *C = nullptr;
1428 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
1430 if (const Comdat *SC = SGV->getComdat()) {
1431 Comdat::SelectionKind SK;
1432 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1433 C = DstM->getOrInsertComdat(SC->getName());
1434 C->setSelectionKind(SK);
1435 if (SGV->hasInternalLinkage())
1438 if (shouldLinkFromSource(LinkFromSrc, *DGV, *SGV))
1443 // Track the source global so that we don't attempt to copy it over when
1444 // processing global initializers.
1445 DoNotLinkFromSource.insert(SGV);
1448 // Make sure to remember this mapping.
1450 ConstantExpr::getBitCast(DGV, TypeMap.get(SGV->getType()));
1454 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1457 if (!LinkFromSrc && DGV) {
1459 // When linking from source we setVisibility from copyGlobalValueProto.
1460 setVisibility(NewGV, SGV, DGV);
1462 NewGV = copyGlobalValueProto(TypeMap, SGV, DGV);
1464 if (isPerformingImport() && !doImportAsDefinition(SGV))
1465 DoNotLinkFromSource.insert(SGV);
1468 NewGV->setUnnamedAddr(HasUnnamedAddr);
1470 if (auto *NewGO = dyn_cast<GlobalObject>(NewGV)) {
1471 if (C && LinkFromSrc)
1472 NewGO->setComdat(C);
1474 if (DGV && DGV->hasCommonLinkage() && SGV->hasCommonLinkage())
1475 NewGO->setAlignment(std::max(DGV->getAlignment(), SGV->getAlignment()));
1478 if (auto *NewGVar = dyn_cast<GlobalVariable>(NewGV)) {
1479 auto *DGVar = dyn_cast_or_null<GlobalVariable>(DGV);
1480 auto *SGVar = dyn_cast<GlobalVariable>(SGV);
1481 if (DGVar && SGVar && DGVar->isDeclaration() && SGVar->isDeclaration() &&
1482 (!DGVar->isConstant() || !SGVar->isConstant()))
1483 NewGVar->setConstant(false);
1486 // Make sure to remember this mapping.
1489 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewGV, DGV->getType()));
1490 DGV->eraseFromParent();
1492 ValueMap[SGV] = NewGV;
1498 /// Update the initializers in the Dest module now that all globals that may be
1499 /// referenced are in Dest.
1500 void ModuleLinker::linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src) {
1501 // Figure out what the initializer looks like in the dest module.
1502 Dst.setInitializer(MapValue(Src.getInitializer(), ValueMap,
1503 RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1506 /// Copy the source function over into the dest function and fix up references
1507 /// to values. At this point we know that Dest is an external function, and
1508 /// that Src is not.
1509 bool ModuleLinker::linkFunctionBody(Function &Dst, Function &Src) {
1510 assert(Dst.isDeclaration() && !Src.isDeclaration());
1512 // Materialize if needed.
1513 if (std::error_code EC = Src.materialize())
1514 return emitError(EC.message());
1516 // Link in the prefix data.
1517 if (Src.hasPrefixData())
1518 Dst.setPrefixData(MapValue(Src.getPrefixData(), ValueMap,
1519 RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1521 // Link in the prologue data.
1522 if (Src.hasPrologueData())
1523 Dst.setPrologueData(MapValue(Src.getPrologueData(), ValueMap,
1524 RF_MoveDistinctMDs, &TypeMap,
1527 // Link in the personality function.
1528 if (Src.hasPersonalityFn())
1529 Dst.setPersonalityFn(MapValue(Src.getPersonalityFn(), ValueMap,
1530 RF_MoveDistinctMDs, &TypeMap,
1533 // Go through and convert function arguments over, remembering the mapping.
1534 Function::arg_iterator DI = Dst.arg_begin();
1535 for (Argument &Arg : Src.args()) {
1536 DI->setName(Arg.getName()); // Copy the name over.
1538 // Add a mapping to our mapping.
1539 ValueMap[&Arg] = &*DI;
1543 // Copy over the metadata attachments.
1544 SmallVector<std::pair<unsigned, MDNode *>, 8> MDs;
1545 Src.getAllMetadata(MDs);
1546 for (const auto &I : MDs)
1547 Dst.setMetadata(I.first, MapMetadata(I.second, ValueMap, RF_MoveDistinctMDs,
1548 &TypeMap, &ValMaterializer));
1550 // Splice the body of the source function into the dest function.
1551 Dst.getBasicBlockList().splice(Dst.end(), Src.getBasicBlockList());
1553 // At this point, all of the instructions and values of the function are now
1554 // copied over. The only problem is that they are still referencing values in
1555 // the Source function as operands. Loop through all of the operands of the
1556 // functions and patch them up to point to the local versions.
1557 for (BasicBlock &BB : Dst)
1558 for (Instruction &I : BB)
1559 RemapInstruction(&I, ValueMap,
1560 RF_IgnoreMissingEntries | RF_MoveDistinctMDs, &TypeMap,
1563 // There is no need to map the arguments anymore.
1564 for (Argument &Arg : Src.args())
1565 ValueMap.erase(&Arg);
1567 Src.dematerialize();
1571 void ModuleLinker::linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src) {
1572 Constant *Aliasee = Src.getAliasee();
1573 Constant *Val = MapValue(Aliasee, ValueMap, RF_MoveDistinctMDs, &TypeMap,
1575 Dst.setAliasee(Val);
1578 bool ModuleLinker::linkGlobalValueBody(GlobalValue &Src) {
1579 Value *Dst = ValueMap[&Src];
1581 if (const Comdat *SC = Src.getComdat()) {
1582 // To ensure that we don't generate an incomplete comdat group,
1583 // we must materialize and map in any other members that are not
1584 // yet materialized in Dst, which also ensures their definitions
1585 // are linked in. Otherwise, linkonce and other lazy linked GVs will
1586 // not be materialized if they aren't referenced.
1587 for (auto *SGV : ComdatMembers[SC]) {
1588 auto *DGV = cast_or_null<GlobalValue>(ValueMap[SGV]);
1589 if (DGV && !DGV->isDeclaration())
1591 MapValue(SGV, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer);
1594 if (shouldInternalizeLinkedSymbols())
1595 if (auto *DGV = dyn_cast<GlobalValue>(Dst))
1596 DGV->setLinkage(GlobalValue::InternalLinkage);
1597 if (auto *F = dyn_cast<Function>(&Src))
1598 return linkFunctionBody(cast<Function>(*Dst), *F);
1599 if (auto *GVar = dyn_cast<GlobalVariable>(&Src)) {
1600 linkGlobalInit(cast<GlobalVariable>(*Dst), *GVar);
1603 linkAliasBody(cast<GlobalAlias>(*Dst), cast<GlobalAlias>(Src));
1607 /// Insert all of the named MDNodes in Src into the Dest module.
1608 void ModuleLinker::linkNamedMDNodes() {
1609 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1610 for (const NamedMDNode &NMD : SrcM->named_metadata()) {
1611 // Don't link module flags here. Do them separately.
1612 if (&NMD == SrcModFlags)
1614 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(NMD.getName());
1615 // Add Src elements into Dest node.
1616 for (const MDNode *op : NMD.operands())
1617 DestNMD->addOperand(MapMetadata(
1618 op, ValueMap, RF_MoveDistinctMDs | RF_NullMapMissingGlobalValues,
1619 &TypeMap, &ValMaterializer));
1623 /// Merge the linker flags in Src into the Dest module.
1624 bool ModuleLinker::linkModuleFlagsMetadata() {
1625 // If the source module has no module flags, we are done.
1626 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1627 if (!SrcModFlags) return false;
1629 // If the destination module doesn't have module flags yet, then just copy
1630 // over the source module's flags.
1631 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
1632 if (DstModFlags->getNumOperands() == 0) {
1633 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1634 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1639 // First build a map of the existing module flags and requirements.
1640 DenseMap<MDString *, std::pair<MDNode *, unsigned>> Flags;
1641 SmallSetVector<MDNode*, 16> Requirements;
1642 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1643 MDNode *Op = DstModFlags->getOperand(I);
1644 ConstantInt *Behavior = mdconst::extract<ConstantInt>(Op->getOperand(0));
1645 MDString *ID = cast<MDString>(Op->getOperand(1));
1647 if (Behavior->getZExtValue() == Module::Require) {
1648 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1650 Flags[ID] = std::make_pair(Op, I);
1654 // Merge in the flags from the source module, and also collect its set of
1656 bool HasErr = false;
1657 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1658 MDNode *SrcOp = SrcModFlags->getOperand(I);
1659 ConstantInt *SrcBehavior =
1660 mdconst::extract<ConstantInt>(SrcOp->getOperand(0));
1661 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1664 std::tie(DstOp, DstIndex) = Flags.lookup(ID);
1665 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1667 // If this is a requirement, add it and continue.
1668 if (SrcBehaviorValue == Module::Require) {
1669 // If the destination module does not already have this requirement, add
1671 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1672 DstModFlags->addOperand(SrcOp);
1677 // If there is no existing flag with this ID, just add it.
1679 Flags[ID] = std::make_pair(SrcOp, DstModFlags->getNumOperands());
1680 DstModFlags->addOperand(SrcOp);
1684 // Otherwise, perform a merge.
1685 ConstantInt *DstBehavior =
1686 mdconst::extract<ConstantInt>(DstOp->getOperand(0));
1687 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1689 // If either flag has override behavior, handle it first.
1690 if (DstBehaviorValue == Module::Override) {
1691 // Diagnose inconsistent flags which both have override behavior.
1692 if (SrcBehaviorValue == Module::Override &&
1693 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1694 HasErr |= emitError("linking module flags '" + ID->getString() +
1695 "': IDs have conflicting override values");
1698 } else if (SrcBehaviorValue == Module::Override) {
1699 // Update the destination flag to that of the source.
1700 DstModFlags->setOperand(DstIndex, SrcOp);
1701 Flags[ID].first = SrcOp;
1705 // Diagnose inconsistent merge behavior types.
1706 if (SrcBehaviorValue != DstBehaviorValue) {
1707 HasErr |= emitError("linking module flags '" + ID->getString() +
1708 "': IDs have conflicting behaviors");
1712 auto replaceDstValue = [&](MDNode *New) {
1713 Metadata *FlagOps[] = {DstOp->getOperand(0), ID, New};
1714 MDNode *Flag = MDNode::get(DstM->getContext(), FlagOps);
1715 DstModFlags->setOperand(DstIndex, Flag);
1716 Flags[ID].first = Flag;
1719 // Perform the merge for standard behavior types.
1720 switch (SrcBehaviorValue) {
1721 case Module::Require:
1722 case Module::Override: llvm_unreachable("not possible");
1723 case Module::Error: {
1724 // Emit an error if the values differ.
1725 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1726 HasErr |= emitError("linking module flags '" + ID->getString() +
1727 "': IDs have conflicting values");
1731 case Module::Warning: {
1732 // Emit a warning if the values differ.
1733 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1734 emitWarning("linking module flags '" + ID->getString() +
1735 "': IDs have conflicting values");
1739 case Module::Append: {
1740 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1741 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1742 SmallVector<Metadata *, 8> MDs;
1743 MDs.reserve(DstValue->getNumOperands() + SrcValue->getNumOperands());
1744 MDs.append(DstValue->op_begin(), DstValue->op_end());
1745 MDs.append(SrcValue->op_begin(), SrcValue->op_end());
1747 replaceDstValue(MDNode::get(DstM->getContext(), MDs));
1750 case Module::AppendUnique: {
1751 SmallSetVector<Metadata *, 16> Elts;
1752 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1753 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1754 Elts.insert(DstValue->op_begin(), DstValue->op_end());
1755 Elts.insert(SrcValue->op_begin(), SrcValue->op_end());
1757 replaceDstValue(MDNode::get(DstM->getContext(),
1758 makeArrayRef(Elts.begin(), Elts.end())));
1764 // Check all of the requirements.
1765 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1766 MDNode *Requirement = Requirements[I];
1767 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1768 Metadata *ReqValue = Requirement->getOperand(1);
1770 MDNode *Op = Flags[Flag].first;
1771 if (!Op || Op->getOperand(2) != ReqValue) {
1772 HasErr |= emitError("linking module flags '" + Flag->getString() +
1773 "': does not have the required value");
1781 // This function returns true if the triples match.
1782 static bool triplesMatch(const Triple &T0, const Triple &T1) {
1783 // If vendor is apple, ignore the version number.
1784 if (T0.getVendor() == Triple::Apple)
1785 return T0.getArch() == T1.getArch() &&
1786 T0.getSubArch() == T1.getSubArch() &&
1787 T0.getVendor() == T1.getVendor() &&
1788 T0.getOS() == T1.getOS();
1793 // This function returns the merged triple.
1794 static std::string mergeTriples(const Triple &SrcTriple, const Triple &DstTriple) {
1795 // If vendor is apple, pick the triple with the larger version number.
1796 if (SrcTriple.getVendor() == Triple::Apple)
1797 if (DstTriple.isOSVersionLT(SrcTriple))
1798 return SrcTriple.str();
1800 return DstTriple.str();
1803 bool ModuleLinker::linkIfNeeded(GlobalValue &GV) {
1804 GlobalValue *DGV = getLinkedToGlobal(&GV);
1806 if (shouldLinkOnlyNeeded() && !(DGV && DGV->isDeclaration()))
1809 if (DGV && !GV.hasLocalLinkage()) {
1810 GlobalValue::VisibilityTypes Visibility =
1811 getMinVisibility(DGV->getVisibility(), GV.getVisibility());
1812 DGV->setVisibility(Visibility);
1813 GV.setVisibility(Visibility);
1816 if (const Comdat *SC = GV.getComdat()) {
1818 Comdat::SelectionKind SK;
1819 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1821 DoNotLinkFromSource.insert(&GV);
1826 if (!DGV && !shouldOverrideFromSrc() &&
1827 (GV.hasLocalLinkage() || GV.hasLinkOnceLinkage() ||
1828 GV.hasAvailableExternallyLinkage())) {
1831 MapValue(&GV, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer);
1835 bool ModuleLinker::run() {
1836 assert(DstM && "Null destination module");
1837 assert(SrcM && "Null source module");
1839 // Inherit the target data from the source module if the destination module
1840 // doesn't have one already.
1841 if (DstM->getDataLayout().isDefault())
1842 DstM->setDataLayout(SrcM->getDataLayout());
1844 if (SrcM->getDataLayout() != DstM->getDataLayout()) {
1845 emitWarning("Linking two modules of different data layouts: '" +
1846 SrcM->getModuleIdentifier() + "' is '" +
1847 SrcM->getDataLayoutStr() + "' whereas '" +
1848 DstM->getModuleIdentifier() + "' is '" +
1849 DstM->getDataLayoutStr() + "'\n");
1852 // Copy the target triple from the source to dest if the dest's is empty.
1853 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
1854 DstM->setTargetTriple(SrcM->getTargetTriple());
1856 Triple SrcTriple(SrcM->getTargetTriple()), DstTriple(DstM->getTargetTriple());
1858 if (!SrcM->getTargetTriple().empty() && !triplesMatch(SrcTriple, DstTriple))
1859 emitWarning("Linking two modules of different target triples: " +
1860 SrcM->getModuleIdentifier() + "' is '" +
1861 SrcM->getTargetTriple() + "' whereas '" +
1862 DstM->getModuleIdentifier() + "' is '" +
1863 DstM->getTargetTriple() + "'\n");
1865 DstM->setTargetTriple(mergeTriples(SrcTriple, DstTriple));
1867 // Append the module inline asm string.
1868 if (!SrcM->getModuleInlineAsm().empty()) {
1869 if (DstM->getModuleInlineAsm().empty())
1870 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
1872 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
1873 SrcM->getModuleInlineAsm());
1876 // Loop over all of the linked values to compute type mappings.
1877 computeTypeMapping();
1879 ComdatsChosen.clear();
1880 for (const auto &SMEC : SrcM->getComdatSymbolTable()) {
1881 const Comdat &C = SMEC.getValue();
1882 if (ComdatsChosen.count(&C))
1884 Comdat::SelectionKind SK;
1886 if (getComdatResult(&C, SK, LinkFromSrc))
1888 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1891 // Upgrade mismatched global arrays.
1892 upgradeMismatchedGlobals();
1894 for (GlobalVariable &GV : SrcM->globals())
1895 if (const Comdat *SC = GV.getComdat())
1896 ComdatMembers[SC].push_back(&GV);
1898 for (Function &SF : *SrcM)
1899 if (const Comdat *SC = SF.getComdat())
1900 ComdatMembers[SC].push_back(&SF);
1902 for (GlobalAlias &GA : SrcM->aliases())
1903 if (const Comdat *SC = GA.getComdat())
1904 ComdatMembers[SC].push_back(&GA);
1906 // Insert all of the globals in src into the DstM module... without linking
1907 // initializers (which could refer to functions not yet mapped over).
1908 for (GlobalVariable &GV : SrcM->globals())
1909 if (linkIfNeeded(GV))
1912 for (Function &SF : *SrcM)
1913 if (linkIfNeeded(SF))
1916 for (GlobalAlias &GA : SrcM->aliases())
1917 if (linkIfNeeded(GA))
1920 for (const auto &Entry : DstM->getComdatSymbolTable()) {
1921 const Comdat &C = Entry.getValue();
1922 if (C.getSelectionKind() == Comdat::Any)
1924 const GlobalValue *GV = SrcM->getNamedValue(C.getName());
1926 MapValue(GV, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer);
1929 // Note that we are done linking global value bodies. This prevents
1930 // metadata linking from creating new references.
1931 DoneLinkingBodies = true;
1933 // Remap all of the named MDNodes in Src into the DstM module. We do this
1934 // after linking GlobalValues so that MDNodes that reference GlobalValues
1935 // are properly remapped.
1938 // Merge the module flags into the DstM module.
1939 if (linkModuleFlagsMetadata())
1945 Linker::StructTypeKeyInfo::KeyTy::KeyTy(ArrayRef<Type *> E, bool P)
1946 : ETypes(E), IsPacked(P) {}
1948 Linker::StructTypeKeyInfo::KeyTy::KeyTy(const StructType *ST)
1949 : ETypes(ST->elements()), IsPacked(ST->isPacked()) {}
1951 bool Linker::StructTypeKeyInfo::KeyTy::operator==(const KeyTy &That) const {
1952 if (IsPacked != That.IsPacked)
1954 if (ETypes != That.ETypes)
1959 bool Linker::StructTypeKeyInfo::KeyTy::operator!=(const KeyTy &That) const {
1960 return !this->operator==(That);
1963 StructType *Linker::StructTypeKeyInfo::getEmptyKey() {
1964 return DenseMapInfo<StructType *>::getEmptyKey();
1967 StructType *Linker::StructTypeKeyInfo::getTombstoneKey() {
1968 return DenseMapInfo<StructType *>::getTombstoneKey();
1971 unsigned Linker::StructTypeKeyInfo::getHashValue(const KeyTy &Key) {
1972 return hash_combine(hash_combine_range(Key.ETypes.begin(), Key.ETypes.end()),
1976 unsigned Linker::StructTypeKeyInfo::getHashValue(const StructType *ST) {
1977 return getHashValue(KeyTy(ST));
1980 bool Linker::StructTypeKeyInfo::isEqual(const KeyTy &LHS,
1981 const StructType *RHS) {
1982 if (RHS == getEmptyKey() || RHS == getTombstoneKey())
1984 return LHS == KeyTy(RHS);
1987 bool Linker::StructTypeKeyInfo::isEqual(const StructType *LHS,
1988 const StructType *RHS) {
1989 if (RHS == getEmptyKey())
1990 return LHS == getEmptyKey();
1992 if (RHS == getTombstoneKey())
1993 return LHS == getTombstoneKey();
1995 return KeyTy(LHS) == KeyTy(RHS);
1998 void Linker::IdentifiedStructTypeSet::addNonOpaque(StructType *Ty) {
1999 assert(!Ty->isOpaque());
2000 NonOpaqueStructTypes.insert(Ty);
2003 void Linker::IdentifiedStructTypeSet::switchToNonOpaque(StructType *Ty) {
2004 assert(!Ty->isOpaque());
2005 NonOpaqueStructTypes.insert(Ty);
2006 bool Removed = OpaqueStructTypes.erase(Ty);
2011 void Linker::IdentifiedStructTypeSet::addOpaque(StructType *Ty) {
2012 assert(Ty->isOpaque());
2013 OpaqueStructTypes.insert(Ty);
2017 Linker::IdentifiedStructTypeSet::findNonOpaque(ArrayRef<Type *> ETypes,
2019 Linker::StructTypeKeyInfo::KeyTy Key(ETypes, IsPacked);
2020 auto I = NonOpaqueStructTypes.find_as(Key);
2021 if (I == NonOpaqueStructTypes.end())
2026 bool Linker::IdentifiedStructTypeSet::hasType(StructType *Ty) {
2028 return OpaqueStructTypes.count(Ty);
2029 auto I = NonOpaqueStructTypes.find(Ty);
2030 if (I == NonOpaqueStructTypes.end())
2035 void Linker::init(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
2036 this->Composite = M;
2037 this->DiagnosticHandler = DiagnosticHandler;
2039 TypeFinder StructTypes;
2040 StructTypes.run(*M, true);
2041 for (StructType *Ty : StructTypes) {
2043 IdentifiedStructTypes.addOpaque(Ty);
2045 IdentifiedStructTypes.addNonOpaque(Ty);
2049 Linker::Linker(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
2050 init(M, DiagnosticHandler);
2053 Linker::Linker(Module *M) {
2054 init(M, [this](const DiagnosticInfo &DI) {
2055 Composite->getContext().diagnose(DI);
2059 void Linker::deleteModule() {
2061 Composite = nullptr;
2064 bool Linker::linkInModule(Module *Src, unsigned Flags,
2065 const FunctionInfoIndex *Index,
2066 Function *FuncToImport) {
2067 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,
2068 DiagnosticHandler, Flags, Index, FuncToImport);
2069 bool RetCode = TheLinker.run();
2070 Composite->dropTriviallyDeadConstantArrays();
2074 //===----------------------------------------------------------------------===//
2075 // LinkModules entrypoint.
2076 //===----------------------------------------------------------------------===//
2078 /// This function links two modules together, with the resulting Dest module
2079 /// modified to be the composite of the two input modules. If an error occurs,
2080 /// true is returned and ErrorMsg (if not null) is set to indicate the problem.
2081 /// Upon failure, the Dest module could be in a modified state, and shouldn't be
2082 /// relied on to be consistent.
2083 bool Linker::LinkModules(Module *Dest, Module *Src,
2084 DiagnosticHandlerFunction DiagnosticHandler,
2086 Linker L(Dest, DiagnosticHandler);
2087 return L.linkInModule(Src, Flags);
2090 bool Linker::LinkModules(Module *Dest, Module *Src, unsigned Flags) {
2092 return L.linkInModule(Src, Flags);
2095 //===----------------------------------------------------------------------===//
2097 //===----------------------------------------------------------------------===//
2099 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
2100 LLVMLinkerMode Unused, char **OutMessages) {
2101 Module *D = unwrap(Dest);
2102 std::string Message;
2103 raw_string_ostream Stream(Message);
2104 DiagnosticPrinterRawOStream DP(Stream);
2106 LLVMBool Result = Linker::LinkModules(
2107 D, unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); });
2109 if (OutMessages && Result) {
2111 *OutMessages = strdup(Message.c_str());