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.
397 ValueMaterializerTy ValMaterializer;
399 /// Mapping of values from what they used to be in Src, to what they are now
400 /// in DstM. ValueToValueMapTy is a ValueMap, which involves some overhead
401 /// due to the use of Value handles which the Linker doesn't actually need,
402 /// but this allows us to reuse the ValueMapper code.
403 ValueToValueMapTy ValueMap;
405 // Set of items not to link in from source.
406 SmallPtrSet<const GlobalValue *, 16> DoNotLinkFromSource;
408 DiagnosticHandlerFunction DiagnosticHandler;
410 /// For symbol clashes, prefer those from Src.
413 /// Function index passed into ModuleLinker for using in function
414 /// importing/exporting handling.
415 const FunctionInfoIndex *ImportIndex;
417 /// Function to import from source module, all other functions are
418 /// imported as declarations instead of definitions.
419 Function *ImportFunction;
421 /// Set to true if the given FunctionInfoIndex contains any functions
422 /// from this source module, in which case we must conservatively assume
423 /// that any of its functions may be imported into another module
424 /// as part of a different backend compilation process.
425 bool HasExportedFunctions;
427 /// Set to true when all global value body linking is complete (including
428 /// lazy linking). Used to prevent metadata linking from creating new
430 bool DoneLinkingBodies;
432 bool HasError = false;
435 ModuleLinker(Module &DstM, Linker::IdentifiedStructTypeSet &Set, Module &SrcM,
436 DiagnosticHandlerFunction DiagnosticHandler, unsigned Flags,
437 const FunctionInfoIndex *Index = nullptr,
438 Function *FuncToImport = nullptr)
439 : DstM(DstM), SrcM(SrcM), TypeMap(Set), ValMaterializer(this),
440 DiagnosticHandler(DiagnosticHandler), Flags(Flags), ImportIndex(Index),
441 ImportFunction(FuncToImport), HasExportedFunctions(false),
442 DoneLinkingBodies(false) {
443 assert((ImportIndex || !ImportFunction) &&
444 "Expect a FunctionInfoIndex when importing");
445 // If we have a FunctionInfoIndex but no function to import,
446 // then this is the primary module being compiled in a ThinLTO
447 // backend compilation, and we need to see if it has functions that
448 // may be exported to another backend compilation.
449 if (ImportIndex && !ImportFunction)
450 HasExportedFunctions = ImportIndex->hasExportedFunctions(&SrcM);
454 Value *materializeDeclFor(Value *V);
455 void materializeInitFor(GlobalValue *New, GlobalValue *Old);
458 bool shouldOverrideFromSrc() { return Flags & Linker::OverrideFromSrc; }
459 bool shouldLinkOnlyNeeded() { return Flags & Linker::LinkOnlyNeeded; }
460 bool shouldInternalizeLinkedSymbols() {
461 return Flags & Linker::InternalizeLinkedSymbols;
464 /// Handles cloning of a global values from the source module into
465 /// the destination module, including setting the attributes and visibility.
466 GlobalValue *copyGlobalValueProto(TypeMapTy &TypeMap, const GlobalValue *SGV,
467 const GlobalValue *DGV = nullptr);
469 /// Check if we should promote the given local value to global scope.
470 bool doPromoteLocalToGlobal(const GlobalValue *SGV);
472 /// Check if all global value body linking is complete.
473 bool doneLinkingBodies() { return DoneLinkingBodies; }
475 bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
476 const GlobalValue &Src);
478 /// Helper method for setting a message and returning an error code.
479 bool emitError(const Twine &Message) {
480 DiagnosticHandler(LinkDiagnosticInfo(DS_Error, Message));
485 void emitWarning(const Twine &Message) {
486 DiagnosticHandler(LinkDiagnosticInfo(DS_Warning, Message));
489 bool getComdatLeader(Module &M, StringRef ComdatName,
490 const GlobalVariable *&GVar);
491 bool computeResultingSelectionKind(StringRef ComdatName,
492 Comdat::SelectionKind Src,
493 Comdat::SelectionKind Dst,
494 Comdat::SelectionKind &Result,
496 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
498 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
500 // Keep track of the global value members of each comdat in source.
501 DenseMap<const Comdat *, std::vector<GlobalValue *>> ComdatMembers;
503 /// Given a global in the source module, return the global in the
504 /// destination module that is being linked to, if any.
505 GlobalValue *getLinkedToGlobal(const GlobalValue *SrcGV) {
506 // If the source has no name it can't link. If it has local linkage,
507 // there is no name match-up going on.
508 if (!SrcGV->hasName() || GlobalValue::isLocalLinkage(getLinkage(SrcGV)))
511 // Otherwise see if we have a match in the destination module's symtab.
512 GlobalValue *DGV = DstM.getNamedValue(getName(SrcGV));
516 // If we found a global with the same name in the dest module, but it has
517 // internal linkage, we are really not doing any linkage here.
518 if (DGV->hasLocalLinkage())
521 // Otherwise, we do in fact link to the destination global.
525 void computeTypeMapping();
527 void upgradeMismatchedGlobalArray(StringRef Name);
528 void upgradeMismatchedGlobals();
530 bool linkIfNeeded(GlobalValue &GV);
531 bool linkAppendingVarProto(GlobalVariable *DstGV,
532 const GlobalVariable *SrcGV);
534 bool linkGlobalValueProto(GlobalValue *GV);
535 bool linkModuleFlagsMetadata();
537 void linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src);
538 bool linkFunctionBody(Function &Dst, Function &Src);
539 void linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src);
540 bool linkGlobalValueBody(GlobalValue &Src);
542 /// Functions that take care of cloning a specific global value type
543 /// into the destination module.
544 GlobalVariable *copyGlobalVariableProto(TypeMapTy &TypeMap,
545 const GlobalVariable *SGVar);
546 Function *copyFunctionProto(TypeMapTy &TypeMap, const Function *SF);
547 GlobalValue *copyGlobalAliasProto(TypeMapTy &TypeMap, const GlobalAlias *SGA);
549 /// Helper methods to check if we are importing from or potentially
550 /// exporting from the current source module.
551 bool isPerformingImport() { return ImportFunction != nullptr; }
552 bool isModuleExporting() { return HasExportedFunctions; }
554 /// If we are importing from the source module, checks if we should
555 /// import SGV as a definition, otherwise import as a declaration.
556 bool doImportAsDefinition(const GlobalValue *SGV);
558 /// Get the name for SGV that should be used in the linked destination
559 /// module. Specifically, this handles the case where we need to rename
560 /// a local that is being promoted to global scope.
561 std::string getName(const GlobalValue *SGV);
563 /// Get the new linkage for SGV that should be used in the linked destination
564 /// module. Specifically, for ThinLTO importing or exporting it may need
566 GlobalValue::LinkageTypes getLinkage(const GlobalValue *SGV);
568 /// Copies the necessary global value attributes and name from the source
569 /// to the newly cloned global value.
570 void copyGVAttributes(GlobalValue *NewGV, const GlobalValue *SrcGV);
572 /// Updates the visibility for the new global cloned from the source
573 /// and, if applicable, linked with an existing destination global.
574 /// Handles visibility change required for promoted locals.
575 void setVisibility(GlobalValue *NewGV, const GlobalValue *SGV,
576 const GlobalValue *DGV = nullptr);
578 void linkNamedMDNodes();
582 /// The LLVM SymbolTable class autorenames globals that conflict in the symbol
583 /// table. This is good for all clients except for us. Go through the trouble
584 /// to force this back.
585 static void forceRenaming(GlobalValue *GV, StringRef Name) {
586 // If the global doesn't force its name or if it already has the right name,
587 // there is nothing for us to do.
588 // Note that any required local to global promotion should already be done,
589 // so promoted locals will not skip this handling as their linkage is no
591 if (GV->hasLocalLinkage() || GV->getName() == Name)
594 Module *M = GV->getParent();
596 // If there is a conflict, rename the conflict.
597 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
598 GV->takeName(ConflictGV);
599 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
600 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
602 GV->setName(Name); // Force the name back
606 /// copy additional attributes (those not needed to construct a GlobalValue)
607 /// from the SrcGV to the DestGV.
608 void ModuleLinker::copyGVAttributes(GlobalValue *NewGV,
609 const GlobalValue *SrcGV) {
610 auto *GA = dyn_cast<GlobalAlias>(SrcGV);
611 // Check for the special case of converting an alias (definition) to a
612 // non-alias (declaration). This can happen when we are importing and
613 // encounter a weak_any alias (weak_any defs may not be imported, see
614 // comments in ModuleLinker::getLinkage) or an alias whose base object is
615 // being imported as a declaration. In that case copy the attributes from the
617 if (GA && !dyn_cast<GlobalAlias>(NewGV)) {
618 assert(isPerformingImport() && !doImportAsDefinition(GA));
619 NewGV->copyAttributesFrom(GA->getBaseObject());
621 NewGV->copyAttributesFrom(SrcGV);
622 forceRenaming(NewGV, getName(SrcGV));
625 bool ModuleLinker::doImportAsDefinition(const GlobalValue *SGV) {
626 if (!isPerformingImport())
628 auto *GA = dyn_cast<GlobalAlias>(SGV);
630 if (GA->hasWeakAnyLinkage())
632 const GlobalObject *GO = GA->getBaseObject();
633 if (!GO->hasLinkOnceODRLinkage())
635 return doImportAsDefinition(GO);
637 // Always import GlobalVariable definitions, except for the special
638 // case of WeakAny which are imported as ExternalWeak declarations
639 // (see comments in ModuleLinker::getLinkage). The linkage changes
640 // described in ModuleLinker::getLinkage ensure the correct behavior (e.g.
641 // global variables with external linkage are transformed to
642 // available_externally definitions, which are ultimately turned into
643 // declarations after the EliminateAvailableExternally pass).
644 if (isa<GlobalVariable>(SGV) && !SGV->isDeclaration() &&
645 !SGV->hasWeakAnyLinkage())
647 // Only import the function requested for importing.
648 auto *SF = dyn_cast<Function>(SGV);
649 if (SF && SF == ImportFunction)
655 bool ModuleLinker::doPromoteLocalToGlobal(const GlobalValue *SGV) {
656 assert(SGV->hasLocalLinkage());
657 // Both the imported references and the original local variable must
659 if (!isPerformingImport() && !isModuleExporting())
662 // Local const variables never need to be promoted unless they are address
663 // taken. The imported uses can simply use the clone created in this module.
664 // For now we are conservative in determining which variables are not
665 // address taken by checking the unnamed addr flag. To be more aggressive,
666 // the address taken information must be checked earlier during parsing
667 // of the module and recorded in the function index for use when importing
669 auto *GVar = dyn_cast<GlobalVariable>(SGV);
670 if (GVar && GVar->isConstant() && GVar->hasUnnamedAddr())
673 // Eventually we only need to promote functions in the exporting module that
674 // are referenced by a potentially exported function (i.e. one that is in the
679 std::string ModuleLinker::getName(const GlobalValue *SGV) {
680 // For locals that must be promoted to global scope, ensure that
681 // the promoted name uniquely identifies the copy in the original module,
682 // using the ID assigned during combined index creation. When importing,
683 // we rename all locals (not just those that are promoted) in order to
684 // avoid naming conflicts between locals imported from different modules.
685 if (SGV->hasLocalLinkage() &&
686 (doPromoteLocalToGlobal(SGV) || isPerformingImport()))
687 return FunctionInfoIndex::getGlobalNameForLocal(
689 ImportIndex->getModuleId(SGV->getParent()->getModuleIdentifier()));
690 return SGV->getName();
693 GlobalValue::LinkageTypes ModuleLinker::getLinkage(const GlobalValue *SGV) {
694 // Any local variable that is referenced by an exported function needs
695 // to be promoted to global scope. Since we don't currently know which
696 // functions reference which local variables/functions, we must treat
697 // all as potentially exported if this module is exporting anything.
698 if (isModuleExporting()) {
699 if (SGV->hasLocalLinkage() && doPromoteLocalToGlobal(SGV))
700 return GlobalValue::ExternalLinkage;
701 return SGV->getLinkage();
704 // Otherwise, if we aren't importing, no linkage change is needed.
705 if (!isPerformingImport())
706 return SGV->getLinkage();
708 switch (SGV->getLinkage()) {
709 case GlobalValue::ExternalLinkage:
710 // External defnitions are converted to available_externally
711 // definitions upon import, so that they are available for inlining
712 // and/or optimization, but are turned into declarations later
713 // during the EliminateAvailableExternally pass.
714 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
715 return GlobalValue::AvailableExternallyLinkage;
716 // An imported external declaration stays external.
717 return SGV->getLinkage();
719 case GlobalValue::AvailableExternallyLinkage:
720 // An imported available_externally definition converts
721 // to external if imported as a declaration.
722 if (!doImportAsDefinition(SGV))
723 return GlobalValue::ExternalLinkage;
724 // An imported available_externally declaration stays that way.
725 return SGV->getLinkage();
727 case GlobalValue::LinkOnceAnyLinkage:
728 case GlobalValue::LinkOnceODRLinkage:
729 // These both stay the same when importing the definition.
730 // The ThinLTO pass will eventually force-import their definitions.
731 return SGV->getLinkage();
733 case GlobalValue::WeakAnyLinkage:
734 // Can't import weak_any definitions correctly, or we might change the
735 // program semantics, since the linker will pick the first weak_any
736 // definition and importing would change the order they are seen by the
737 // linker. The module linking caller needs to enforce this.
738 assert(!doImportAsDefinition(SGV));
739 // If imported as a declaration, it becomes external_weak.
740 return GlobalValue::ExternalWeakLinkage;
742 case GlobalValue::WeakODRLinkage:
743 // For weak_odr linkage, there is a guarantee that all copies will be
744 // equivalent, so the issue described above for weak_any does not exist,
745 // and the definition can be imported. It can be treated similarly
746 // to an imported externally visible global value.
747 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
748 return GlobalValue::AvailableExternallyLinkage;
750 return GlobalValue::ExternalLinkage;
752 case GlobalValue::AppendingLinkage:
753 // It would be incorrect to import an appending linkage variable,
754 // since it would cause global constructors/destructors to be
755 // executed multiple times. This should have already been handled
756 // by linkGlobalValueProto.
757 llvm_unreachable("Cannot import appending linkage variable");
759 case GlobalValue::InternalLinkage:
760 case GlobalValue::PrivateLinkage:
761 // If we are promoting the local to global scope, it is handled
762 // similarly to a normal externally visible global.
763 if (doPromoteLocalToGlobal(SGV)) {
764 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
765 return GlobalValue::AvailableExternallyLinkage;
767 return GlobalValue::ExternalLinkage;
769 // A non-promoted imported local definition stays local.
770 // The ThinLTO pass will eventually force-import their definitions.
771 return SGV->getLinkage();
773 case GlobalValue::ExternalWeakLinkage:
774 // External weak doesn't apply to definitions, must be a declaration.
775 assert(!doImportAsDefinition(SGV));
776 // Linkage stays external_weak.
777 return SGV->getLinkage();
779 case GlobalValue::CommonLinkage:
780 // Linkage stays common on definitions.
781 // The ThinLTO pass will eventually force-import their definitions.
782 return SGV->getLinkage();
785 llvm_unreachable("unknown linkage type");
788 /// Loop through the global variables in the src module and merge them into the
791 ModuleLinker::copyGlobalVariableProto(TypeMapTy &TypeMap,
792 const GlobalVariable *SGVar) {
793 // No linking to be performed or linking from the source: simply create an
794 // identical version of the symbol over in the dest module... the
795 // initializer will be filled in later by LinkGlobalInits.
796 GlobalVariable *NewDGV = new GlobalVariable(
797 DstM, TypeMap.get(SGVar->getType()->getElementType()),
798 SGVar->isConstant(), getLinkage(SGVar), /*init*/ nullptr, getName(SGVar),
799 /*insertbefore*/ nullptr, SGVar->getThreadLocalMode(),
800 SGVar->getType()->getAddressSpace());
805 /// Link the function in the source module into the destination module if
806 /// needed, setting up mapping information.
807 Function *ModuleLinker::copyFunctionProto(TypeMapTy &TypeMap,
808 const Function *SF) {
809 // If there is no linkage to be performed or we are linking from the source,
811 return Function::Create(TypeMap.get(SF->getFunctionType()), getLinkage(SF),
815 /// Set up prototypes for any aliases that come over from the source module.
816 GlobalValue *ModuleLinker::copyGlobalAliasProto(TypeMapTy &TypeMap,
817 const GlobalAlias *SGA) {
818 // If we are importing and encounter a weak_any alias, or an alias to
819 // an object being imported as a declaration, we must import the alias
820 // as a declaration as well, which involves converting it to a non-alias.
821 // See comments in ModuleLinker::getLinkage for why we cannot import
822 // weak_any defintions.
823 if (isPerformingImport() && !doImportAsDefinition(SGA)) {
824 // Need to convert to declaration. All aliases must be definitions.
825 const GlobalValue *GVal = SGA->getBaseObject();
827 if (auto *GVar = dyn_cast<GlobalVariable>(GVal))
828 NewGV = copyGlobalVariableProto(TypeMap, GVar);
830 auto *F = dyn_cast<Function>(GVal);
832 NewGV = copyFunctionProto(TypeMap, F);
834 // Set the linkage to External or ExternalWeak (see comments in
835 // ModuleLinker::getLinkage for why WeakAny is converted to ExternalWeak).
836 if (SGA->hasWeakAnyLinkage())
837 NewGV->setLinkage(GlobalValue::ExternalWeakLinkage);
839 NewGV->setLinkage(GlobalValue::ExternalLinkage);
842 // If there is no linkage to be performed or we're linking from the source,
844 auto *Ty = TypeMap.get(SGA->getValueType());
845 return GlobalAlias::create(Ty, SGA->getType()->getPointerAddressSpace(),
846 getLinkage(SGA), getName(SGA), &DstM);
849 static GlobalValue::VisibilityTypes
850 getMinVisibility(GlobalValue::VisibilityTypes A,
851 GlobalValue::VisibilityTypes B) {
852 if (A == GlobalValue::HiddenVisibility || B == GlobalValue::HiddenVisibility)
853 return GlobalValue::HiddenVisibility;
854 if (A == GlobalValue::ProtectedVisibility ||
855 B == GlobalValue::ProtectedVisibility)
856 return GlobalValue::ProtectedVisibility;
857 return GlobalValue::DefaultVisibility;
860 void ModuleLinker::setVisibility(GlobalValue *NewGV, const GlobalValue *SGV,
861 const GlobalValue *DGV) {
862 GlobalValue::VisibilityTypes Visibility = SGV->getVisibility();
864 Visibility = getMinVisibility(DGV->getVisibility(), Visibility);
865 // For promoted locals, mark them hidden so that they can later be
866 // stripped from the symbol table to reduce bloat.
867 if (SGV->hasLocalLinkage() && doPromoteLocalToGlobal(SGV))
868 Visibility = GlobalValue::HiddenVisibility;
869 NewGV->setVisibility(Visibility);
872 GlobalValue *ModuleLinker::copyGlobalValueProto(TypeMapTy &TypeMap,
873 const GlobalValue *SGV,
874 const GlobalValue *DGV) {
876 if (auto *SGVar = dyn_cast<GlobalVariable>(SGV))
877 NewGV = copyGlobalVariableProto(TypeMap, SGVar);
878 else if (auto *SF = dyn_cast<Function>(SGV))
879 NewGV = copyFunctionProto(TypeMap, SF);
881 NewGV = copyGlobalAliasProto(TypeMap, cast<GlobalAlias>(SGV));
882 copyGVAttributes(NewGV, SGV);
883 setVisibility(NewGV, SGV, DGV);
887 Value *ValueMaterializerTy::materializeDeclFor(Value *V) {
888 return ModLinker->materializeDeclFor(V);
891 Value *ModuleLinker::materializeDeclFor(Value *V) {
892 auto *SGV = dyn_cast<GlobalValue>(V);
896 // If we are done linking global value bodies (i.e. we are performing
897 // metadata linking), don't link in the global value due to this
898 // reference, simply map it to null.
899 if (doneLinkingBodies())
902 linkGlobalValueProto(SGV);
905 Value *Ret = ValueMap[SGV];
910 void ValueMaterializerTy::materializeInitFor(GlobalValue *New,
912 return ModLinker->materializeInitFor(New, Old);
915 void ModuleLinker::materializeInitFor(GlobalValue *New, GlobalValue *Old) {
916 if (auto *F = dyn_cast<Function>(New)) {
917 if (!F->isDeclaration())
919 } else if (auto *V = dyn_cast<GlobalVariable>(New)) {
920 if (V->hasInitializer())
923 auto *A = cast<GlobalAlias>(New);
928 if (Old->isDeclaration())
931 if (isPerformingImport() && !doImportAsDefinition(Old))
934 if (!New->hasLocalLinkage() && DoNotLinkFromSource.count(Old))
937 linkGlobalValueBody(*Old);
940 bool ModuleLinker::getComdatLeader(Module &M, StringRef ComdatName,
941 const GlobalVariable *&GVar) {
942 const GlobalValue *GVal = M.getNamedValue(ComdatName);
943 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
944 GVal = GA->getBaseObject();
946 // We cannot resolve the size of the aliasee yet.
947 return emitError("Linking COMDATs named '" + ComdatName +
948 "': COMDAT key involves incomputable alias size.");
951 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
954 "Linking COMDATs named '" + ComdatName +
955 "': GlobalVariable required for data dependent selection!");
960 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
961 Comdat::SelectionKind Src,
962 Comdat::SelectionKind Dst,
963 Comdat::SelectionKind &Result,
965 // The ability to mix Comdat::SelectionKind::Any with
966 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
967 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
968 Dst == Comdat::SelectionKind::Largest;
969 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
970 Src == Comdat::SelectionKind::Largest;
971 if (DstAnyOrLargest && SrcAnyOrLargest) {
972 if (Dst == Comdat::SelectionKind::Largest ||
973 Src == Comdat::SelectionKind::Largest)
974 Result = Comdat::SelectionKind::Largest;
976 Result = Comdat::SelectionKind::Any;
977 } else if (Src == Dst) {
980 return emitError("Linking COMDATs named '" + ComdatName +
981 "': invalid selection kinds!");
985 case Comdat::SelectionKind::Any:
989 case Comdat::SelectionKind::NoDuplicates:
990 return emitError("Linking COMDATs named '" + ComdatName +
991 "': noduplicates has been violated!");
992 case Comdat::SelectionKind::ExactMatch:
993 case Comdat::SelectionKind::Largest:
994 case Comdat::SelectionKind::SameSize: {
995 const GlobalVariable *DstGV;
996 const GlobalVariable *SrcGV;
997 if (getComdatLeader(DstM, ComdatName, DstGV) ||
998 getComdatLeader(SrcM, ComdatName, SrcGV))
1001 const DataLayout &DstDL = DstM.getDataLayout();
1002 const DataLayout &SrcDL = SrcM.getDataLayout();
1004 DstDL.getTypeAllocSize(DstGV->getType()->getPointerElementType());
1006 SrcDL.getTypeAllocSize(SrcGV->getType()->getPointerElementType());
1007 if (Result == Comdat::SelectionKind::ExactMatch) {
1008 if (SrcGV->getInitializer() != DstGV->getInitializer())
1009 return emitError("Linking COMDATs named '" + ComdatName +
1010 "': ExactMatch violated!");
1011 LinkFromSrc = false;
1012 } else if (Result == Comdat::SelectionKind::Largest) {
1013 LinkFromSrc = SrcSize > DstSize;
1014 } else if (Result == Comdat::SelectionKind::SameSize) {
1015 if (SrcSize != DstSize)
1016 return emitError("Linking COMDATs named '" + ComdatName +
1017 "': SameSize violated!");
1018 LinkFromSrc = false;
1020 llvm_unreachable("unknown selection kind");
1029 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
1030 Comdat::SelectionKind &Result,
1031 bool &LinkFromSrc) {
1032 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
1033 StringRef ComdatName = SrcC->getName();
1034 Module::ComdatSymTabType &ComdatSymTab = DstM.getComdatSymbolTable();
1035 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
1037 if (DstCI == ComdatSymTab.end()) {
1038 // Use the comdat if it is only available in one of the modules.
1044 const Comdat *DstC = &DstCI->second;
1045 Comdat::SelectionKind DSK = DstC->getSelectionKind();
1046 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
1050 bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
1051 const GlobalValue &Dest,
1052 const GlobalValue &Src) {
1053 // Should we unconditionally use the Src?
1054 if (shouldOverrideFromSrc()) {
1059 // We always have to add Src if it has appending linkage.
1060 if (Src.hasAppendingLinkage()) {
1061 // Caller should have already determined that we can't link from source
1062 // when importing (see comments in linkGlobalValueProto).
1063 assert(!isPerformingImport());
1068 bool SrcIsDeclaration = Src.isDeclarationForLinker();
1069 bool DestIsDeclaration = Dest.isDeclarationForLinker();
1071 if (isPerformingImport()) {
1072 if (isa<Function>(&Src)) {
1073 // For functions, LinkFromSrc iff this is the function requested
1074 // for importing. For variables, decide below normally.
1075 LinkFromSrc = (&Src == ImportFunction);
1079 // Check if this is an alias with an already existing definition
1080 // in Dest, which must have come from a prior importing pass from
1081 // the same Src module. Unlike imported function and variable
1082 // definitions, which are imported as available_externally and are
1083 // not definitions for the linker, that is not a valid linkage for
1084 // imported aliases which must be definitions. Simply use the existing
1086 if (isa<GlobalAlias>(&Src) && !DestIsDeclaration) {
1087 assert(isa<GlobalAlias>(&Dest));
1088 LinkFromSrc = false;
1093 if (SrcIsDeclaration) {
1094 // If Src is external or if both Src & Dest are external.. Just link the
1095 // external globals, we aren't adding anything.
1096 if (Src.hasDLLImportStorageClass()) {
1097 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
1098 LinkFromSrc = DestIsDeclaration;
1101 // If the Dest is weak, use the source linkage.
1102 LinkFromSrc = Dest.hasExternalWeakLinkage();
1106 if (DestIsDeclaration) {
1107 // If Dest is external but Src is not:
1112 if (Src.hasCommonLinkage()) {
1113 if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
1118 if (!Dest.hasCommonLinkage()) {
1119 LinkFromSrc = false;
1123 const DataLayout &DL = Dest.getParent()->getDataLayout();
1124 uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
1125 uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
1126 LinkFromSrc = SrcSize > DestSize;
1130 if (Src.isWeakForLinker()) {
1131 assert(!Dest.hasExternalWeakLinkage());
1132 assert(!Dest.hasAvailableExternallyLinkage());
1134 if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
1139 LinkFromSrc = false;
1143 if (Dest.isWeakForLinker()) {
1144 assert(Src.hasExternalLinkage());
1149 assert(!Src.hasExternalWeakLinkage());
1150 assert(!Dest.hasExternalWeakLinkage());
1151 assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
1152 "Unexpected linkage type!");
1153 return emitError("Linking globals named '" + Src.getName() +
1154 "': symbol multiply defined!");
1157 /// Loop over all of the linked values to compute type mappings. For example,
1158 /// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct
1159 /// types 'Foo' but one got renamed when the module was loaded into the same
1161 void ModuleLinker::computeTypeMapping() {
1162 for (GlobalValue &SGV : SrcM.globals()) {
1163 GlobalValue *DGV = getLinkedToGlobal(&SGV);
1167 if (!DGV->hasAppendingLinkage() || !SGV.hasAppendingLinkage()) {
1168 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1172 // Unify the element type of appending arrays.
1173 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
1174 ArrayType *SAT = cast<ArrayType>(SGV.getType()->getElementType());
1175 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
1178 for (GlobalValue &SGV : SrcM) {
1179 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
1180 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1183 for (GlobalValue &SGV : SrcM.aliases()) {
1184 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
1185 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1188 // Incorporate types by name, scanning all the types in the source module.
1189 // At this point, the destination module may have a type "%foo = { i32 }" for
1190 // example. When the source module got loaded into the same LLVMContext, if
1191 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
1192 std::vector<StructType *> Types = SrcM.getIdentifiedStructTypes();
1193 for (StructType *ST : Types) {
1197 // Check to see if there is a dot in the name followed by a digit.
1198 size_t DotPos = ST->getName().rfind('.');
1199 if (DotPos == 0 || DotPos == StringRef::npos ||
1200 ST->getName().back() == '.' ||
1201 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos + 1])))
1204 // Check to see if the destination module has a struct with the prefix name.
1205 StructType *DST = DstM.getTypeByName(ST->getName().substr(0, DotPos));
1209 // Don't use it if this actually came from the source module. They're in
1210 // the same LLVMContext after all. Also don't use it unless the type is
1211 // actually used in the destination module. This can happen in situations
1214 // Module A Module B
1215 // -------- --------
1216 // %Z = type { %A } %B = type { %C.1 }
1217 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
1218 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
1219 // %C = type { i8* } %B.3 = type { %C.1 }
1221 // When we link Module B with Module A, the '%B' in Module B is
1222 // used. However, that would then use '%C.1'. But when we process '%C.1',
1223 // we prefer to take the '%C' version. So we are then left with both
1224 // '%C.1' and '%C' being used for the same types. This leads to some
1225 // variables using one type and some using the other.
1226 if (TypeMap.DstStructTypesSet.hasType(DST))
1227 TypeMap.addTypeMapping(DST, ST);
1230 // Now that we have discovered all of the type equivalences, get a body for
1231 // any 'opaque' types in the dest module that are now resolved.
1232 TypeMap.linkDefinedTypeBodies();
1235 static void upgradeGlobalArray(GlobalVariable *GV) {
1236 ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
1237 StructType *OldTy = cast<StructType>(ATy->getElementType());
1238 assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
1240 // Get the upgraded 3 element type.
1241 PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
1242 Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
1244 StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
1246 // Build new constants with a null third field filled in.
1247 Constant *OldInitC = GV->getInitializer();
1248 ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
1249 if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
1250 // Invalid initializer; give up.
1252 std::vector<Constant *> Initializers;
1253 if (OldInit && OldInit->getNumOperands()) {
1254 Value *Null = Constant::getNullValue(VoidPtrTy);
1255 for (Use &U : OldInit->operands()) {
1256 ConstantStruct *Init = cast<ConstantStruct>(U.get());
1257 Initializers.push_back(ConstantStruct::get(
1258 NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
1261 assert(Initializers.size() == ATy->getNumElements() &&
1262 "Failed to copy all array elements");
1264 // Replace the old GV with a new one.
1265 ATy = ArrayType::get(NewTy, Initializers.size());
1266 Constant *NewInit = ConstantArray::get(ATy, Initializers);
1267 GlobalVariable *NewGV = new GlobalVariable(
1268 *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
1269 GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
1270 GV->isExternallyInitialized());
1271 NewGV->copyAttributesFrom(GV);
1272 NewGV->takeName(GV);
1273 assert(GV->use_empty() && "program cannot use initializer list");
1274 GV->eraseFromParent();
1277 void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
1278 // Look for the global arrays.
1279 auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM.getNamedValue(Name));
1282 auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM.getNamedValue(Name));
1286 // Check if the types already match.
1287 auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
1289 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
1293 // Grab the element types. We can only upgrade an array of a two-field
1294 // struct. Only bother if the other one has three-fields.
1295 auto *DstEltTy = cast<StructType>(DstTy->getElementType());
1296 auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
1297 if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
1298 upgradeGlobalArray(DstGV);
1301 if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
1302 upgradeGlobalArray(SrcGV);
1304 // We can't upgrade any other differences.
1307 void ModuleLinker::upgradeMismatchedGlobals() {
1308 upgradeMismatchedGlobalArray("llvm.global_ctors");
1309 upgradeMismatchedGlobalArray("llvm.global_dtors");
1312 static void getArrayElements(const Constant *C,
1313 SmallVectorImpl<Constant *> &Dest) {
1314 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1316 for (unsigned i = 0; i != NumElements; ++i)
1317 Dest.push_back(C->getAggregateElement(i));
1320 /// If there were any appending global variables, link them together now.
1321 /// Return true on error.
1322 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
1323 const GlobalVariable *SrcGV) {
1325 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
1326 Type *EltTy = SrcTy->getElementType();
1329 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
1331 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
1333 "Linking globals named '" + SrcGV->getName() +
1334 "': can only link appending global with another appending global!");
1336 // Check to see that they two arrays agree on type.
1337 if (EltTy != DstTy->getElementType())
1338 return emitError("Appending variables with different element types!");
1339 if (DstGV->isConstant() != SrcGV->isConstant())
1340 return emitError("Appending variables linked with different const'ness!");
1342 if (DstGV->getAlignment() != SrcGV->getAlignment())
1344 "Appending variables with different alignment need to be linked!");
1346 if (DstGV->getVisibility() != SrcGV->getVisibility())
1348 "Appending variables with different visibility need to be linked!");
1350 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
1352 "Appending variables with different unnamed_addr need to be linked!");
1354 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
1356 "Appending variables with different section name need to be linked!");
1359 SmallVector<Constant *, 16> DstElements;
1361 getArrayElements(DstGV->getInitializer(), DstElements);
1363 SmallVector<Constant *, 16> SrcElements;
1364 getArrayElements(SrcGV->getInitializer(), SrcElements);
1366 StringRef Name = SrcGV->getName();
1367 bool IsNewStructor =
1368 (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
1369 cast<StructType>(EltTy)->getNumElements() == 3;
1372 std::remove_if(SrcElements.begin(), SrcElements.end(),
1373 [this](Constant *E) {
1374 auto *Key = dyn_cast<GlobalValue>(
1375 E->getAggregateElement(2)->stripPointerCasts());
1376 return DoNotLinkFromSource.count(Key);
1379 uint64_t NewSize = DstElements.size() + SrcElements.size();
1380 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
1382 // Create the new global variable.
1383 GlobalVariable *NG = new GlobalVariable(
1384 DstM, NewType, SrcGV->isConstant(), SrcGV->getLinkage(),
1385 /*init*/ nullptr, /*name*/ "", DstGV, SrcGV->getThreadLocalMode(),
1386 SrcGV->getType()->getAddressSpace());
1388 // Propagate alignment, visibility and section info.
1389 copyGVAttributes(NG, SrcGV);
1391 // Replace any uses of the two global variables with uses of the new
1393 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
1395 for (auto *V : SrcElements) {
1396 DstElements.push_back(
1397 MapValue(V, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1400 NG->setInitializer(ConstantArray::get(NewType, DstElements));
1403 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
1404 DstGV->eraseFromParent();
1410 bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) {
1411 GlobalValue *DGV = getLinkedToGlobal(SGV);
1413 // Handle the ultra special appending linkage case first.
1414 assert(!DGV || SGV->hasAppendingLinkage() == DGV->hasAppendingLinkage());
1415 if (SGV->hasAppendingLinkage() && isPerformingImport()) {
1416 // Don't want to append to global_ctors list, for example, when we
1417 // are importing for ThinLTO, otherwise the global ctors and dtors
1418 // get executed multiple times for local variables (the latter causing
1420 DoNotLinkFromSource.insert(SGV);
1423 if (SGV->hasAppendingLinkage())
1424 return linkAppendingVarProto(cast_or_null<GlobalVariable>(DGV),
1425 cast<GlobalVariable>(SGV));
1427 bool LinkFromSrc = true;
1428 Comdat *C = nullptr;
1429 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
1431 if (const Comdat *SC = SGV->getComdat()) {
1432 Comdat::SelectionKind SK;
1433 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1434 C = DstM.getOrInsertComdat(SC->getName());
1435 C->setSelectionKind(SK);
1436 if (SGV->hasInternalLinkage())
1439 if (shouldLinkFromSource(LinkFromSrc, *DGV, *SGV))
1444 // Track the source global so that we don't attempt to copy it over when
1445 // processing global initializers.
1446 DoNotLinkFromSource.insert(SGV);
1449 // Make sure to remember this mapping.
1451 ConstantExpr::getBitCast(DGV, TypeMap.get(SGV->getType()));
1455 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1458 if (!LinkFromSrc && DGV) {
1460 // When linking from source we setVisibility from copyGlobalValueProto.
1461 setVisibility(NewGV, SGV, DGV);
1463 NewGV = copyGlobalValueProto(TypeMap, SGV, DGV);
1465 if (isPerformingImport() && !doImportAsDefinition(SGV))
1466 DoNotLinkFromSource.insert(SGV);
1469 NewGV->setUnnamedAddr(HasUnnamedAddr);
1471 if (auto *NewGO = dyn_cast<GlobalObject>(NewGV)) {
1472 if (C && LinkFromSrc)
1473 NewGO->setComdat(C);
1475 if (DGV && DGV->hasCommonLinkage() && SGV->hasCommonLinkage())
1476 NewGO->setAlignment(std::max(DGV->getAlignment(), SGV->getAlignment()));
1479 if (auto *NewGVar = dyn_cast<GlobalVariable>(NewGV)) {
1480 auto *DGVar = dyn_cast_or_null<GlobalVariable>(DGV);
1481 auto *SGVar = dyn_cast<GlobalVariable>(SGV);
1482 if (DGVar && SGVar && DGVar->isDeclaration() && SGVar->isDeclaration() &&
1483 (!DGVar->isConstant() || !SGVar->isConstant()))
1484 NewGVar->setConstant(false);
1487 // Make sure to remember this mapping.
1490 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewGV, DGV->getType()));
1491 DGV->eraseFromParent();
1493 ValueMap[SGV] = NewGV;
1499 /// Update the initializers in the Dest module now that all globals that may be
1500 /// referenced are in Dest.
1501 void ModuleLinker::linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src) {
1502 // Figure out what the initializer looks like in the dest module.
1503 Dst.setInitializer(MapValue(Src.getInitializer(), ValueMap,
1504 RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1507 /// Copy the source function over into the dest function and fix up references
1508 /// to values. At this point we know that Dest is an external function, and
1509 /// that Src is not.
1510 bool ModuleLinker::linkFunctionBody(Function &Dst, Function &Src) {
1511 assert(Dst.isDeclaration() && !Src.isDeclaration());
1513 // Materialize if needed.
1514 if (std::error_code EC = Src.materialize())
1515 return emitError(EC.message());
1517 // Link in the prefix data.
1518 if (Src.hasPrefixData())
1519 Dst.setPrefixData(MapValue(Src.getPrefixData(), ValueMap,
1520 RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1522 // Link in the prologue data.
1523 if (Src.hasPrologueData())
1524 Dst.setPrologueData(MapValue(Src.getPrologueData(), ValueMap,
1525 RF_MoveDistinctMDs, &TypeMap,
1528 // Link in the personality function.
1529 if (Src.hasPersonalityFn())
1530 Dst.setPersonalityFn(MapValue(Src.getPersonalityFn(), ValueMap,
1531 RF_MoveDistinctMDs, &TypeMap,
1534 // Go through and convert function arguments over, remembering the mapping.
1535 Function::arg_iterator DI = Dst.arg_begin();
1536 for (Argument &Arg : Src.args()) {
1537 DI->setName(Arg.getName()); // Copy the name over.
1539 // Add a mapping to our mapping.
1540 ValueMap[&Arg] = &*DI;
1544 // Copy over the metadata attachments.
1545 SmallVector<std::pair<unsigned, MDNode *>, 8> MDs;
1546 Src.getAllMetadata(MDs);
1547 for (const auto &I : MDs)
1548 Dst.setMetadata(I.first, MapMetadata(I.second, ValueMap, RF_MoveDistinctMDs,
1549 &TypeMap, &ValMaterializer));
1551 // Splice the body of the source function into the dest function.
1552 Dst.getBasicBlockList().splice(Dst.end(), Src.getBasicBlockList());
1554 // At this point, all of the instructions and values of the function are now
1555 // copied over. The only problem is that they are still referencing values in
1556 // the Source function as operands. Loop through all of the operands of the
1557 // functions and patch them up to point to the local versions.
1558 for (BasicBlock &BB : Dst)
1559 for (Instruction &I : BB)
1560 RemapInstruction(&I, ValueMap,
1561 RF_IgnoreMissingEntries | RF_MoveDistinctMDs, &TypeMap,
1564 // There is no need to map the arguments anymore.
1565 for (Argument &Arg : Src.args())
1566 ValueMap.erase(&Arg);
1568 Src.dematerialize();
1572 void ModuleLinker::linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src) {
1573 Constant *Aliasee = Src.getAliasee();
1574 Constant *Val = MapValue(Aliasee, ValueMap, RF_MoveDistinctMDs, &TypeMap,
1576 Dst.setAliasee(Val);
1579 bool ModuleLinker::linkGlobalValueBody(GlobalValue &Src) {
1580 Value *Dst = ValueMap[&Src];
1582 if (const Comdat *SC = Src.getComdat()) {
1583 // To ensure that we don't generate an incomplete comdat group,
1584 // we must materialize and map in any other members that are not
1585 // yet materialized in Dst, which also ensures their definitions
1586 // are linked in. Otherwise, linkonce and other lazy linked GVs will
1587 // not be materialized if they aren't referenced.
1588 for (auto *SGV : ComdatMembers[SC]) {
1589 auto *DGV = cast_or_null<GlobalValue>(ValueMap[SGV]);
1590 if (DGV && !DGV->isDeclaration())
1592 MapValue(SGV, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer);
1595 if (shouldInternalizeLinkedSymbols())
1596 if (auto *DGV = dyn_cast<GlobalValue>(Dst))
1597 DGV->setLinkage(GlobalValue::InternalLinkage);
1598 if (auto *F = dyn_cast<Function>(&Src))
1599 return linkFunctionBody(cast<Function>(*Dst), *F);
1600 if (auto *GVar = dyn_cast<GlobalVariable>(&Src)) {
1601 linkGlobalInit(cast<GlobalVariable>(*Dst), *GVar);
1604 linkAliasBody(cast<GlobalAlias>(*Dst), cast<GlobalAlias>(Src));
1608 /// Insert all of the named MDNodes in Src into the Dest module.
1609 void ModuleLinker::linkNamedMDNodes() {
1610 const NamedMDNode *SrcModFlags = SrcM.getModuleFlagsMetadata();
1611 for (const NamedMDNode &NMD : SrcM.named_metadata()) {
1612 // Don't link module flags here. Do them separately.
1613 if (&NMD == SrcModFlags)
1615 NamedMDNode *DestNMD = DstM.getOrInsertNamedMetadata(NMD.getName());
1616 // Add Src elements into Dest node.
1617 for (const MDNode *op : NMD.operands())
1618 DestNMD->addOperand(MapMetadata(
1619 op, ValueMap, RF_MoveDistinctMDs | RF_NullMapMissingGlobalValues,
1620 &TypeMap, &ValMaterializer));
1624 /// Merge the linker flags in Src into the Dest module.
1625 bool ModuleLinker::linkModuleFlagsMetadata() {
1626 // If the source module has no module flags, we are done.
1627 const NamedMDNode *SrcModFlags = SrcM.getModuleFlagsMetadata();
1628 if (!SrcModFlags) return false;
1630 // If the destination module doesn't have module flags yet, then just copy
1631 // over the source module's flags.
1632 NamedMDNode *DstModFlags = DstM.getOrInsertModuleFlagsMetadata();
1633 if (DstModFlags->getNumOperands() == 0) {
1634 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1635 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1640 // First build a map of the existing module flags and requirements.
1641 DenseMap<MDString *, std::pair<MDNode *, unsigned>> Flags;
1642 SmallSetVector<MDNode*, 16> Requirements;
1643 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1644 MDNode *Op = DstModFlags->getOperand(I);
1645 ConstantInt *Behavior = mdconst::extract<ConstantInt>(Op->getOperand(0));
1646 MDString *ID = cast<MDString>(Op->getOperand(1));
1648 if (Behavior->getZExtValue() == Module::Require) {
1649 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1651 Flags[ID] = std::make_pair(Op, I);
1655 // Merge in the flags from the source module, and also collect its set of
1657 bool HasErr = false;
1658 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1659 MDNode *SrcOp = SrcModFlags->getOperand(I);
1660 ConstantInt *SrcBehavior =
1661 mdconst::extract<ConstantInt>(SrcOp->getOperand(0));
1662 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1665 std::tie(DstOp, DstIndex) = Flags.lookup(ID);
1666 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1668 // If this is a requirement, add it and continue.
1669 if (SrcBehaviorValue == Module::Require) {
1670 // If the destination module does not already have this requirement, add
1672 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1673 DstModFlags->addOperand(SrcOp);
1678 // If there is no existing flag with this ID, just add it.
1680 Flags[ID] = std::make_pair(SrcOp, DstModFlags->getNumOperands());
1681 DstModFlags->addOperand(SrcOp);
1685 // Otherwise, perform a merge.
1686 ConstantInt *DstBehavior =
1687 mdconst::extract<ConstantInt>(DstOp->getOperand(0));
1688 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1690 // If either flag has override behavior, handle it first.
1691 if (DstBehaviorValue == Module::Override) {
1692 // Diagnose inconsistent flags which both have override behavior.
1693 if (SrcBehaviorValue == Module::Override &&
1694 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1695 HasErr |= emitError("linking module flags '" + ID->getString() +
1696 "': IDs have conflicting override values");
1699 } else if (SrcBehaviorValue == Module::Override) {
1700 // Update the destination flag to that of the source.
1701 DstModFlags->setOperand(DstIndex, SrcOp);
1702 Flags[ID].first = SrcOp;
1706 // Diagnose inconsistent merge behavior types.
1707 if (SrcBehaviorValue != DstBehaviorValue) {
1708 HasErr |= emitError("linking module flags '" + ID->getString() +
1709 "': IDs have conflicting behaviors");
1713 auto replaceDstValue = [&](MDNode *New) {
1714 Metadata *FlagOps[] = {DstOp->getOperand(0), ID, New};
1715 MDNode *Flag = MDNode::get(DstM.getContext(), FlagOps);
1716 DstModFlags->setOperand(DstIndex, Flag);
1717 Flags[ID].first = Flag;
1720 // Perform the merge for standard behavior types.
1721 switch (SrcBehaviorValue) {
1722 case Module::Require:
1723 case Module::Override: llvm_unreachable("not possible");
1724 case Module::Error: {
1725 // Emit an error if the values differ.
1726 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1727 HasErr |= emitError("linking module flags '" + ID->getString() +
1728 "': IDs have conflicting values");
1732 case Module::Warning: {
1733 // Emit a warning if the values differ.
1734 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1735 emitWarning("linking module flags '" + ID->getString() +
1736 "': IDs have conflicting values");
1740 case Module::Append: {
1741 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1742 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1743 SmallVector<Metadata *, 8> MDs;
1744 MDs.reserve(DstValue->getNumOperands() + SrcValue->getNumOperands());
1745 MDs.append(DstValue->op_begin(), DstValue->op_end());
1746 MDs.append(SrcValue->op_begin(), SrcValue->op_end());
1748 replaceDstValue(MDNode::get(DstM.getContext(), MDs));
1751 case Module::AppendUnique: {
1752 SmallSetVector<Metadata *, 16> Elts;
1753 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1754 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1755 Elts.insert(DstValue->op_begin(), DstValue->op_end());
1756 Elts.insert(SrcValue->op_begin(), SrcValue->op_end());
1758 replaceDstValue(MDNode::get(DstM.getContext(),
1759 makeArrayRef(Elts.begin(), Elts.end())));
1765 // Check all of the requirements.
1766 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1767 MDNode *Requirement = Requirements[I];
1768 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1769 Metadata *ReqValue = Requirement->getOperand(1);
1771 MDNode *Op = Flags[Flag].first;
1772 if (!Op || Op->getOperand(2) != ReqValue) {
1773 HasErr |= emitError("linking module flags '" + Flag->getString() +
1774 "': does not have the required value");
1782 // This function returns true if the triples match.
1783 static bool triplesMatch(const Triple &T0, const Triple &T1) {
1784 // If vendor is apple, ignore the version number.
1785 if (T0.getVendor() == Triple::Apple)
1786 return T0.getArch() == T1.getArch() &&
1787 T0.getSubArch() == T1.getSubArch() &&
1788 T0.getVendor() == T1.getVendor() &&
1789 T0.getOS() == T1.getOS();
1794 // This function returns the merged triple.
1795 static std::string mergeTriples(const Triple &SrcTriple, const Triple &DstTriple) {
1796 // If vendor is apple, pick the triple with the larger version number.
1797 if (SrcTriple.getVendor() == Triple::Apple)
1798 if (DstTriple.isOSVersionLT(SrcTriple))
1799 return SrcTriple.str();
1801 return DstTriple.str();
1804 bool ModuleLinker::linkIfNeeded(GlobalValue &GV) {
1805 GlobalValue *DGV = getLinkedToGlobal(&GV);
1807 if (shouldLinkOnlyNeeded() && !(DGV && DGV->isDeclaration()))
1810 if (DGV && !GV.hasLocalLinkage()) {
1811 GlobalValue::VisibilityTypes Visibility =
1812 getMinVisibility(DGV->getVisibility(), GV.getVisibility());
1813 DGV->setVisibility(Visibility);
1814 GV.setVisibility(Visibility);
1817 if (const Comdat *SC = GV.getComdat()) {
1819 Comdat::SelectionKind SK;
1820 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1822 DoNotLinkFromSource.insert(&GV);
1827 if (!DGV && !shouldOverrideFromSrc() &&
1828 (GV.hasLocalLinkage() || GV.hasLinkOnceLinkage() ||
1829 GV.hasAvailableExternallyLinkage())) {
1832 MapValue(&GV, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer);
1836 bool ModuleLinker::run() {
1837 // Inherit the target data from the source module if the destination module
1838 // doesn't have one already.
1839 if (DstM.getDataLayout().isDefault())
1840 DstM.setDataLayout(SrcM.getDataLayout());
1842 if (SrcM.getDataLayout() != DstM.getDataLayout()) {
1843 emitWarning("Linking two modules of different data layouts: '" +
1844 SrcM.getModuleIdentifier() + "' is '" +
1845 SrcM.getDataLayoutStr() + "' whereas '" +
1846 DstM.getModuleIdentifier() + "' is '" +
1847 DstM.getDataLayoutStr() + "'\n");
1850 // Copy the target triple from the source to dest if the dest's is empty.
1851 if (DstM.getTargetTriple().empty() && !SrcM.getTargetTriple().empty())
1852 DstM.setTargetTriple(SrcM.getTargetTriple());
1854 Triple SrcTriple(SrcM.getTargetTriple()), DstTriple(DstM.getTargetTriple());
1856 if (!SrcM.getTargetTriple().empty() && !triplesMatch(SrcTriple, DstTriple))
1857 emitWarning("Linking two modules of different target triples: " +
1858 SrcM.getModuleIdentifier() + "' is '" + SrcM.getTargetTriple() +
1859 "' whereas '" + DstM.getModuleIdentifier() + "' is '" +
1860 DstM.getTargetTriple() + "'\n");
1862 DstM.setTargetTriple(mergeTriples(SrcTriple, DstTriple));
1864 // Append the module inline asm string.
1865 if (!SrcM.getModuleInlineAsm().empty()) {
1866 if (DstM.getModuleInlineAsm().empty())
1867 DstM.setModuleInlineAsm(SrcM.getModuleInlineAsm());
1869 DstM.setModuleInlineAsm(DstM.getModuleInlineAsm() + "\n" +
1870 SrcM.getModuleInlineAsm());
1873 // Loop over all of the linked values to compute type mappings.
1874 computeTypeMapping();
1876 ComdatsChosen.clear();
1877 for (const auto &SMEC : SrcM.getComdatSymbolTable()) {
1878 const Comdat &C = SMEC.getValue();
1879 if (ComdatsChosen.count(&C))
1881 Comdat::SelectionKind SK;
1883 if (getComdatResult(&C, SK, LinkFromSrc))
1885 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1888 // Upgrade mismatched global arrays.
1889 upgradeMismatchedGlobals();
1891 for (GlobalVariable &GV : SrcM.globals())
1892 if (const Comdat *SC = GV.getComdat())
1893 ComdatMembers[SC].push_back(&GV);
1895 for (Function &SF : SrcM)
1896 if (const Comdat *SC = SF.getComdat())
1897 ComdatMembers[SC].push_back(&SF);
1899 for (GlobalAlias &GA : SrcM.aliases())
1900 if (const Comdat *SC = GA.getComdat())
1901 ComdatMembers[SC].push_back(&GA);
1903 // Insert all of the globals in src into the DstM module... without linking
1904 // initializers (which could refer to functions not yet mapped over).
1905 for (GlobalVariable &GV : SrcM.globals())
1906 if (linkIfNeeded(GV))
1909 for (Function &SF : SrcM)
1910 if (linkIfNeeded(SF))
1913 for (GlobalAlias &GA : SrcM.aliases())
1914 if (linkIfNeeded(GA))
1917 for (const auto &Entry : DstM.getComdatSymbolTable()) {
1918 const Comdat &C = Entry.getValue();
1919 if (C.getSelectionKind() == Comdat::Any)
1921 const GlobalValue *GV = SrcM.getNamedValue(C.getName());
1923 MapValue(GV, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer);
1926 // Note that we are done linking global value bodies. This prevents
1927 // metadata linking from creating new references.
1928 DoneLinkingBodies = true;
1930 // Remap all of the named MDNodes in Src into the DstM module. We do this
1931 // after linking GlobalValues so that MDNodes that reference GlobalValues
1932 // are properly remapped.
1935 // Merge the module flags into the DstM module.
1936 if (linkModuleFlagsMetadata())
1942 Linker::StructTypeKeyInfo::KeyTy::KeyTy(ArrayRef<Type *> E, bool P)
1943 : ETypes(E), IsPacked(P) {}
1945 Linker::StructTypeKeyInfo::KeyTy::KeyTy(const StructType *ST)
1946 : ETypes(ST->elements()), IsPacked(ST->isPacked()) {}
1948 bool Linker::StructTypeKeyInfo::KeyTy::operator==(const KeyTy &That) const {
1949 if (IsPacked != That.IsPacked)
1951 if (ETypes != That.ETypes)
1956 bool Linker::StructTypeKeyInfo::KeyTy::operator!=(const KeyTy &That) const {
1957 return !this->operator==(That);
1960 StructType *Linker::StructTypeKeyInfo::getEmptyKey() {
1961 return DenseMapInfo<StructType *>::getEmptyKey();
1964 StructType *Linker::StructTypeKeyInfo::getTombstoneKey() {
1965 return DenseMapInfo<StructType *>::getTombstoneKey();
1968 unsigned Linker::StructTypeKeyInfo::getHashValue(const KeyTy &Key) {
1969 return hash_combine(hash_combine_range(Key.ETypes.begin(), Key.ETypes.end()),
1973 unsigned Linker::StructTypeKeyInfo::getHashValue(const StructType *ST) {
1974 return getHashValue(KeyTy(ST));
1977 bool Linker::StructTypeKeyInfo::isEqual(const KeyTy &LHS,
1978 const StructType *RHS) {
1979 if (RHS == getEmptyKey() || RHS == getTombstoneKey())
1981 return LHS == KeyTy(RHS);
1984 bool Linker::StructTypeKeyInfo::isEqual(const StructType *LHS,
1985 const StructType *RHS) {
1986 if (RHS == getEmptyKey())
1987 return LHS == getEmptyKey();
1989 if (RHS == getTombstoneKey())
1990 return LHS == getTombstoneKey();
1992 return KeyTy(LHS) == KeyTy(RHS);
1995 void Linker::IdentifiedStructTypeSet::addNonOpaque(StructType *Ty) {
1996 assert(!Ty->isOpaque());
1997 NonOpaqueStructTypes.insert(Ty);
2000 void Linker::IdentifiedStructTypeSet::switchToNonOpaque(StructType *Ty) {
2001 assert(!Ty->isOpaque());
2002 NonOpaqueStructTypes.insert(Ty);
2003 bool Removed = OpaqueStructTypes.erase(Ty);
2008 void Linker::IdentifiedStructTypeSet::addOpaque(StructType *Ty) {
2009 assert(Ty->isOpaque());
2010 OpaqueStructTypes.insert(Ty);
2014 Linker::IdentifiedStructTypeSet::findNonOpaque(ArrayRef<Type *> ETypes,
2016 Linker::StructTypeKeyInfo::KeyTy Key(ETypes, IsPacked);
2017 auto I = NonOpaqueStructTypes.find_as(Key);
2018 if (I == NonOpaqueStructTypes.end())
2023 bool Linker::IdentifiedStructTypeSet::hasType(StructType *Ty) {
2025 return OpaqueStructTypes.count(Ty);
2026 auto I = NonOpaqueStructTypes.find(Ty);
2027 if (I == NonOpaqueStructTypes.end())
2032 Linker::Linker(Module &M, DiagnosticHandlerFunction DiagnosticHandler)
2033 : Composite(M), DiagnosticHandler(DiagnosticHandler) {
2034 TypeFinder StructTypes;
2035 StructTypes.run(M, true);
2036 for (StructType *Ty : StructTypes) {
2038 IdentifiedStructTypes.addOpaque(Ty);
2040 IdentifiedStructTypes.addNonOpaque(Ty);
2044 Linker::Linker(Module &M)
2045 : Linker(M, [this](const DiagnosticInfo &DI) {
2046 Composite.getContext().diagnose(DI);
2049 bool Linker::linkInModule(Module &Src, unsigned Flags,
2050 const FunctionInfoIndex *Index,
2051 Function *FuncToImport) {
2052 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,
2053 DiagnosticHandler, Flags, Index, FuncToImport);
2054 bool RetCode = TheLinker.run();
2055 Composite.dropTriviallyDeadConstantArrays();
2059 //===----------------------------------------------------------------------===//
2060 // LinkModules entrypoint.
2061 //===----------------------------------------------------------------------===//
2063 /// This function links two modules together, with the resulting Dest module
2064 /// modified to be the composite of the two input modules. If an error occurs,
2065 /// true is returned and ErrorMsg (if not null) is set to indicate the problem.
2066 /// Upon failure, the Dest module could be in a modified state, and shouldn't be
2067 /// relied on to be consistent.
2068 bool Linker::linkModules(Module &Dest, Module &Src,
2069 DiagnosticHandlerFunction DiagnosticHandler,
2071 Linker L(Dest, DiagnosticHandler);
2072 return L.linkInModule(Src, Flags);
2075 bool Linker::linkModules(Module &Dest, Module &Src, unsigned Flags) {
2077 return L.linkInModule(Src, Flags);
2080 //===----------------------------------------------------------------------===//
2082 //===----------------------------------------------------------------------===//
2084 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
2085 LLVMLinkerMode Unused, char **OutMessages) {
2086 Module *D = unwrap(Dest);
2087 std::string Message;
2088 raw_string_ostream Stream(Message);
2089 DiagnosticPrinterRawOStream DP(Stream);
2091 LLVMBool Result = Linker::linkModules(
2092 *D, *unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); });
2094 if (OutMessages && Result) {
2096 *OutMessages = strdup(Message.c_str());