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 {
371 std::vector<GlobalValue *> &LazilyLinkGlobalValues;
372 ModuleLinker *ModLinker;
375 ValueMaterializerTy(TypeMapTy &TypeMap, Module *DstM,
376 std::vector<GlobalValue *> &LazilyLinkGlobalValues,
377 ModuleLinker *ModLinker)
378 : ValueMaterializer(), TypeMap(TypeMap), DstM(DstM),
379 LazilyLinkGlobalValues(LazilyLinkGlobalValues), ModLinker(ModLinker) {}
381 Value *materializeValueFor(Value *V) override;
384 class LinkDiagnosticInfo : public DiagnosticInfo {
388 LinkDiagnosticInfo(DiagnosticSeverity Severity, const Twine &Msg);
389 void print(DiagnosticPrinter &DP) const override;
391 LinkDiagnosticInfo::LinkDiagnosticInfo(DiagnosticSeverity Severity,
393 : DiagnosticInfo(DK_Linker, Severity), Msg(Msg) {}
394 void LinkDiagnosticInfo::print(DiagnosticPrinter &DP) const { DP << Msg; }
396 /// This is an implementation class for the LinkModules function, which is the
397 /// entrypoint for this file.
402 ValueMaterializerTy ValMaterializer;
404 /// Mapping of values from what they used to be in Src, to what they are now
405 /// in DstM. ValueToValueMapTy is a ValueMap, which involves some overhead
406 /// due to the use of Value handles which the Linker doesn't actually need,
407 /// but this allows us to reuse the ValueMapper code.
408 ValueToValueMapTy ValueMap;
410 struct AppendingVarInfo {
411 GlobalVariable *NewGV; // New aggregate global in dest module.
412 const Constant *DstInit; // Old initializer from dest module.
413 const Constant *SrcInit; // Old initializer from src module.
416 std::vector<AppendingVarInfo> AppendingVars;
418 // Set of items not to link in from source.
419 SmallPtrSet<const Value *, 16> DoNotLinkFromSource;
421 // Vector of GlobalValues to lazily link in.
422 std::vector<GlobalValue *> LazilyLinkGlobalValues;
424 DiagnosticHandlerFunction DiagnosticHandler;
426 /// For symbol clashes, prefer those from Src.
429 /// Function index passed into ModuleLinker for using in function
430 /// importing/exporting handling.
431 FunctionInfoIndex *ImportIndex;
433 /// Function to import from source module, all other functions are
434 /// imported as declarations instead of definitions.
435 Function *ImportFunction;
437 /// Set to true if the given FunctionInfoIndex contains any functions
438 /// from this source module, in which case we must conservatively assume
439 /// that any of its functions may be imported into another module
440 /// as part of a different backend compilation process.
441 bool HasExportedFunctions;
443 /// Set to true when all global value body linking is complete (including
444 /// lazy linking). Used to prevent metadata linking from creating new
446 bool DoneLinkingBodies;
449 ModuleLinker(Module *dstM, Linker::IdentifiedStructTypeSet &Set, Module *srcM,
450 DiagnosticHandlerFunction DiagnosticHandler, unsigned Flags,
451 FunctionInfoIndex *Index = nullptr,
452 Function *FuncToImport = nullptr)
453 : DstM(dstM), SrcM(srcM), TypeMap(Set),
454 ValMaterializer(TypeMap, DstM, LazilyLinkGlobalValues, this),
455 DiagnosticHandler(DiagnosticHandler), Flags(Flags), ImportIndex(Index),
456 ImportFunction(FuncToImport), HasExportedFunctions(false),
457 DoneLinkingBodies(false) {
458 assert((ImportIndex || !ImportFunction) &&
459 "Expect a FunctionInfoIndex when importing");
460 // If we have a FunctionInfoIndex but no function to import,
461 // then this is the primary module being compiled in a ThinLTO
462 // backend compilation, and we need to see if it has functions that
463 // may be exported to another backend compilation.
464 if (ImportIndex && !ImportFunction)
465 HasExportedFunctions = ImportIndex->hasExportedFunctions(SrcM);
470 bool shouldOverrideFromSrc() { return Flags & Linker::OverrideFromSrc; }
471 bool shouldLinkOnlyNeeded() { return Flags & Linker::LinkOnlyNeeded; }
472 bool shouldInternalizeLinkedSymbols() {
473 return Flags & Linker::InternalizeLinkedSymbols;
476 /// Handles cloning of a global values from the source module into
477 /// the destination module, including setting the attributes and visibility.
478 GlobalValue *copyGlobalValueProto(TypeMapTy &TypeMap, const GlobalValue *SGV,
479 const GlobalValue *DGV = nullptr);
481 /// Check if we should promote the given local value to global scope.
482 bool doPromoteLocalToGlobal(const GlobalValue *SGV);
484 /// Check if all global value body linking is complete.
485 bool doneLinkingBodies() { return DoneLinkingBodies; }
488 bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
489 const GlobalValue &Src);
491 /// Helper method for setting a message and returning an error code.
492 bool emitError(const Twine &Message) {
493 DiagnosticHandler(LinkDiagnosticInfo(DS_Error, Message));
497 void emitWarning(const Twine &Message) {
498 DiagnosticHandler(LinkDiagnosticInfo(DS_Warning, Message));
501 bool getComdatLeader(Module *M, StringRef ComdatName,
502 const GlobalVariable *&GVar);
503 bool computeResultingSelectionKind(StringRef ComdatName,
504 Comdat::SelectionKind Src,
505 Comdat::SelectionKind Dst,
506 Comdat::SelectionKind &Result,
508 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
510 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
512 // Keep track of the global value members of each comdat in source.
513 DenseMap<const Comdat *, std::vector<GlobalValue *>> ComdatMembers;
515 /// Given a global in the source module, return the global in the
516 /// destination module that is being linked to, if any.
517 GlobalValue *getLinkedToGlobal(const GlobalValue *SrcGV) {
518 // If the source has no name it can't link. If it has local linkage,
519 // there is no name match-up going on.
520 if (!SrcGV->hasName() || SrcGV->hasLocalLinkage())
523 // Otherwise see if we have a match in the destination module's symtab.
524 GlobalValue *DGV = DstM->getNamedValue(SrcGV->getName());
528 // If we found a global with the same name in the dest module, but it has
529 // internal linkage, we are really not doing any linkage here.
530 if (DGV->hasLocalLinkage())
533 // Otherwise, we do in fact link to the destination global.
537 void computeTypeMapping();
539 void upgradeMismatchedGlobalArray(StringRef Name);
540 void upgradeMismatchedGlobals();
542 bool linkAppendingVarProto(GlobalVariable *DstGV,
543 const GlobalVariable *SrcGV);
545 bool linkGlobalValueProto(GlobalValue *GV);
546 bool linkModuleFlagsMetadata();
548 void linkAppendingVarInit(const AppendingVarInfo &AVI);
550 void linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src);
551 bool linkFunctionBody(Function &Dst, Function &Src);
552 void linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src);
553 bool linkGlobalValueBody(GlobalValue &Src);
555 /// Functions that take care of cloning a specific global value type
556 /// into the destination module.
557 GlobalVariable *copyGlobalVariableProto(TypeMapTy &TypeMap,
558 const GlobalVariable *SGVar);
559 Function *copyFunctionProto(TypeMapTy &TypeMap, const Function *SF);
560 GlobalValue *copyGlobalAliasProto(TypeMapTy &TypeMap, const GlobalAlias *SGA);
562 /// Helper methods to check if we are importing from or potentially
563 /// exporting from the current source module.
564 bool isPerformingImport() { return ImportFunction != nullptr; }
565 bool isModuleExporting() { return HasExportedFunctions; }
567 /// If we are importing from the source module, checks if we should
568 /// import SGV as a definition, otherwise import as a declaration.
569 bool doImportAsDefinition(const GlobalValue *SGV);
571 /// Get the name for SGV that should be used in the linked destination
572 /// module. Specifically, this handles the case where we need to rename
573 /// a local that is being promoted to global scope.
574 std::string getName(const GlobalValue *SGV);
576 /// Get the new linkage for SGV that should be used in the linked destination
577 /// module. Specifically, for ThinLTO importing or exporting it may need
579 GlobalValue::LinkageTypes getLinkage(const GlobalValue *SGV);
581 /// Copies the necessary global value attributes and name from the source
582 /// to the newly cloned global value.
583 void copyGVAttributes(GlobalValue *NewGV, const GlobalValue *SrcGV);
585 /// Updates the visibility for the new global cloned from the source
586 /// and, if applicable, linked with an existing destination global.
587 /// Handles visibility change required for promoted locals.
588 void setVisibility(GlobalValue *NewGV, const GlobalValue *SGV,
589 const GlobalValue *DGV = nullptr);
591 void linkNamedMDNodes();
595 /// The LLVM SymbolTable class autorenames globals that conflict in the symbol
596 /// table. This is good for all clients except for us. Go through the trouble
597 /// to force this back.
598 static void forceRenaming(GlobalValue *GV, StringRef Name) {
599 // If the global doesn't force its name or if it already has the right name,
600 // there is nothing for us to do.
601 // Note that any required local to global promotion should already be done,
602 // so promoted locals will not skip this handling as their linkage is no
604 if (GV->hasLocalLinkage() || GV->getName() == Name)
607 Module *M = GV->getParent();
609 // If there is a conflict, rename the conflict.
610 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
611 GV->takeName(ConflictGV);
612 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
613 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
615 GV->setName(Name); // Force the name back
619 /// copy additional attributes (those not needed to construct a GlobalValue)
620 /// from the SrcGV to the DestGV.
621 void ModuleLinker::copyGVAttributes(GlobalValue *NewGV,
622 const GlobalValue *SrcGV) {
623 auto *GA = dyn_cast<GlobalAlias>(SrcGV);
624 // Check for the special case of converting an alias (definition) to a
625 // non-alias (declaration). This can happen when we are importing and
626 // encounter a weak_any alias (weak_any defs may not be imported, see
627 // comments in ModuleLinker::getLinkage) or an alias whose base object is
628 // being imported as a declaration. In that case copy the attributes from the
630 if (GA && !dyn_cast<GlobalAlias>(NewGV)) {
631 assert(isPerformingImport() && !doImportAsDefinition(GA));
632 NewGV->copyAttributesFrom(GA->getBaseObject());
634 NewGV->copyAttributesFrom(SrcGV);
635 forceRenaming(NewGV, getName(SrcGV));
638 static bool isLessConstraining(GlobalValue::VisibilityTypes a,
639 GlobalValue::VisibilityTypes b) {
640 if (a == GlobalValue::HiddenVisibility)
642 if (b == GlobalValue::HiddenVisibility)
644 if (a == GlobalValue::ProtectedVisibility)
646 if (b == GlobalValue::ProtectedVisibility)
651 bool ModuleLinker::doImportAsDefinition(const GlobalValue *SGV) {
652 if (!isPerformingImport())
654 auto *GA = dyn_cast<GlobalAlias>(SGV);
656 if (GA->hasWeakAnyLinkage())
658 return doImportAsDefinition(GA->getBaseObject());
660 // Always import GlobalVariable definitions, except for the special
661 // case of WeakAny which are imported as ExternalWeak declarations
662 // (see comments in ModuleLinker::getLinkage). The linkage changes
663 // described in ModuleLinker::getLinkage ensure the correct behavior (e.g.
664 // global variables with external linkage are transformed to
665 // available_externally definitions, which are ultimately turned into
666 // declarations after the EliminateAvailableExternally pass).
667 if (dyn_cast<GlobalVariable>(SGV) && !SGV->isDeclaration() &&
668 !SGV->hasWeakAnyLinkage())
670 // Only import the function requested for importing.
671 auto *SF = dyn_cast<Function>(SGV);
672 if (SF && SF == ImportFunction)
678 bool ModuleLinker::doPromoteLocalToGlobal(const GlobalValue *SGV) {
679 assert(SGV->hasLocalLinkage());
680 // Both the imported references and the original local variable must
682 if (!isPerformingImport() && !isModuleExporting())
685 // Local const variables never need to be promoted unless they are address
686 // taken. The imported uses can simply use the clone created in this module.
687 // For now we are conservative in determining which variables are not
688 // address taken by checking the unnamed addr flag. To be more aggressive,
689 // the address taken information must be checked earlier during parsing
690 // of the module and recorded in the function index for use when importing
692 auto *GVar = dyn_cast<GlobalVariable>(SGV);
693 if (GVar && GVar->isConstant() && GVar->hasUnnamedAddr())
696 // Eventually we only need to promote functions in the exporting module that
697 // are referenced by a potentially exported function (i.e. one that is in the
702 std::string ModuleLinker::getName(const GlobalValue *SGV) {
703 // For locals that must be promoted to global scope, ensure that
704 // the promoted name uniquely identifies the copy in the original module,
705 // using the ID assigned during combined index creation. When importing,
706 // we rename all locals (not just those that are promoted) in order to
707 // avoid naming conflicts between locals imported from different modules.
708 if (SGV->hasLocalLinkage() &&
709 (doPromoteLocalToGlobal(SGV) || isPerformingImport()))
710 return FunctionInfoIndex::getGlobalNameForLocal(
712 ImportIndex->getModuleId(SGV->getParent()->getModuleIdentifier()));
713 return SGV->getName();
716 GlobalValue::LinkageTypes ModuleLinker::getLinkage(const GlobalValue *SGV) {
717 // Any local variable that is referenced by an exported function needs
718 // to be promoted to global scope. Since we don't currently know which
719 // functions reference which local variables/functions, we must treat
720 // all as potentially exported if this module is exporting anything.
721 if (isModuleExporting()) {
722 if (SGV->hasLocalLinkage() && doPromoteLocalToGlobal(SGV))
723 return GlobalValue::ExternalLinkage;
724 return SGV->getLinkage();
727 // Otherwise, if we aren't importing, no linkage change is needed.
728 if (!isPerformingImport())
729 return SGV->getLinkage();
731 switch (SGV->getLinkage()) {
732 case GlobalValue::ExternalLinkage:
733 // External defnitions are converted to available_externally
734 // definitions upon import, so that they are available for inlining
735 // and/or optimization, but are turned into declarations later
736 // during the EliminateAvailableExternally pass.
737 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
738 return GlobalValue::AvailableExternallyLinkage;
739 // An imported external declaration stays external.
740 return SGV->getLinkage();
742 case GlobalValue::AvailableExternallyLinkage:
743 // An imported available_externally definition converts
744 // to external if imported as a declaration.
745 if (!doImportAsDefinition(SGV))
746 return GlobalValue::ExternalLinkage;
747 // An imported available_externally declaration stays that way.
748 return SGV->getLinkage();
750 case GlobalValue::LinkOnceAnyLinkage:
751 case GlobalValue::LinkOnceODRLinkage:
752 // These both stay the same when importing the definition.
753 // The ThinLTO pass will eventually force-import their definitions.
754 return SGV->getLinkage();
756 case GlobalValue::WeakAnyLinkage:
757 // Can't import weak_any definitions correctly, or we might change the
758 // program semantics, since the linker will pick the first weak_any
759 // definition and importing would change the order they are seen by the
760 // linker. The module linking caller needs to enforce this.
761 assert(!doImportAsDefinition(SGV));
762 // If imported as a declaration, it becomes external_weak.
763 return GlobalValue::ExternalWeakLinkage;
765 case GlobalValue::WeakODRLinkage:
766 // For weak_odr linkage, there is a guarantee that all copies will be
767 // equivalent, so the issue described above for weak_any does not exist,
768 // and the definition can be imported. It can be treated similarly
769 // to an imported externally visible global value.
770 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
771 return GlobalValue::AvailableExternallyLinkage;
773 return GlobalValue::ExternalLinkage;
775 case GlobalValue::AppendingLinkage:
776 // It would be incorrect to import an appending linkage variable,
777 // since it would cause global constructors/destructors to be
778 // executed multiple times. This should have already been handled
779 // by linkGlobalValueProto.
780 llvm_unreachable("Cannot import appending linkage variable");
782 case GlobalValue::InternalLinkage:
783 case GlobalValue::PrivateLinkage:
784 // If we are promoting the local to global scope, it is handled
785 // similarly to a normal externally visible global.
786 if (doPromoteLocalToGlobal(SGV)) {
787 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
788 return GlobalValue::AvailableExternallyLinkage;
790 return GlobalValue::ExternalLinkage;
792 // A non-promoted imported local definition stays local.
793 // The ThinLTO pass will eventually force-import their definitions.
794 return SGV->getLinkage();
796 case GlobalValue::ExternalWeakLinkage:
797 // External weak doesn't apply to definitions, must be a declaration.
798 assert(!doImportAsDefinition(SGV));
799 // Linkage stays external_weak.
800 return SGV->getLinkage();
802 case GlobalValue::CommonLinkage:
803 // Linkage stays common on definitions.
804 // The ThinLTO pass will eventually force-import their definitions.
805 return SGV->getLinkage();
808 llvm_unreachable("unknown linkage type");
811 /// Loop through the global variables in the src module and merge them into the
814 ModuleLinker::copyGlobalVariableProto(TypeMapTy &TypeMap,
815 const GlobalVariable *SGVar) {
816 // No linking to be performed or linking from the source: simply create an
817 // identical version of the symbol over in the dest module... the
818 // initializer will be filled in later by LinkGlobalInits.
819 GlobalVariable *NewDGV = new GlobalVariable(
820 *DstM, TypeMap.get(SGVar->getType()->getElementType()),
821 SGVar->isConstant(), getLinkage(SGVar), /*init*/ nullptr, getName(SGVar),
822 /*insertbefore*/ nullptr, SGVar->getThreadLocalMode(),
823 SGVar->getType()->getAddressSpace());
828 /// Link the function in the source module into the destination module if
829 /// needed, setting up mapping information.
830 Function *ModuleLinker::copyFunctionProto(TypeMapTy &TypeMap,
831 const Function *SF) {
832 // If there is no linkage to be performed or we are linking from the source,
834 return Function::Create(TypeMap.get(SF->getFunctionType()), getLinkage(SF),
838 /// Set up prototypes for any aliases that come over from the source module.
839 GlobalValue *ModuleLinker::copyGlobalAliasProto(TypeMapTy &TypeMap,
840 const GlobalAlias *SGA) {
841 // If we are importing and encounter a weak_any alias, or an alias to
842 // an object being imported as a declaration, we must import the alias
843 // as a declaration as well, which involves converting it to a non-alias.
844 // See comments in ModuleLinker::getLinkage for why we cannot import
845 // weak_any defintions.
846 if (isPerformingImport() && !doImportAsDefinition(SGA)) {
847 // Need to convert to declaration. All aliases must be definitions.
848 const GlobalValue *GVal = SGA->getBaseObject();
850 if (auto *GVar = dyn_cast<GlobalVariable>(GVal))
851 NewGV = copyGlobalVariableProto(TypeMap, GVar);
853 auto *F = dyn_cast<Function>(GVal);
855 NewGV = copyFunctionProto(TypeMap, F);
857 // Set the linkage to External or ExternalWeak (see comments in
858 // ModuleLinker::getLinkage for why WeakAny is converted to ExternalWeak).
859 if (SGA->hasWeakAnyLinkage())
860 NewGV->setLinkage(GlobalValue::ExternalWeakLinkage);
862 NewGV->setLinkage(GlobalValue::ExternalLinkage);
865 // If there is no linkage to be performed or we're linking from the source,
867 auto *Ty = TypeMap.get(SGA->getValueType());
868 return GlobalAlias::create(Ty, SGA->getType()->getPointerAddressSpace(),
869 getLinkage(SGA), getName(SGA), DstM);
872 void ModuleLinker::setVisibility(GlobalValue *NewGV, const GlobalValue *SGV,
873 const GlobalValue *DGV) {
874 GlobalValue::VisibilityTypes Visibility = SGV->getVisibility();
876 Visibility = isLessConstraining(Visibility, DGV->getVisibility())
877 ? DGV->getVisibility()
879 // For promoted locals, mark them hidden so that they can later be
880 // stripped from the symbol table to reduce bloat.
881 if (SGV->hasLocalLinkage() && doPromoteLocalToGlobal(SGV))
882 Visibility = GlobalValue::HiddenVisibility;
883 NewGV->setVisibility(Visibility);
886 GlobalValue *ModuleLinker::copyGlobalValueProto(TypeMapTy &TypeMap,
887 const GlobalValue *SGV,
888 const GlobalValue *DGV) {
890 if (auto *SGVar = dyn_cast<GlobalVariable>(SGV))
891 NewGV = copyGlobalVariableProto(TypeMap, SGVar);
892 else if (auto *SF = dyn_cast<Function>(SGV))
893 NewGV = copyFunctionProto(TypeMap, SF);
895 NewGV = copyGlobalAliasProto(TypeMap, cast<GlobalAlias>(SGV));
896 copyGVAttributes(NewGV, SGV);
897 setVisibility(NewGV, SGV, DGV);
901 Value *ValueMaterializerTy::materializeValueFor(Value *V) {
902 auto *SGV = dyn_cast<GlobalValue>(V);
906 // If we are done linking global value bodies (i.e. we are performing
907 // metadata linking), don't link in the global value due to this
908 // reference, simply map it to null.
909 if (ModLinker->doneLinkingBodies())
912 GlobalValue *DGV = ModLinker->copyGlobalValueProto(TypeMap, SGV);
914 if (Comdat *SC = SGV->getComdat()) {
915 if (auto *DGO = dyn_cast<GlobalObject>(DGV)) {
916 Comdat *DC = DstM->getOrInsertComdat(SC->getName());
921 LazilyLinkGlobalValues.push_back(SGV);
925 bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName,
926 const GlobalVariable *&GVar) {
927 const GlobalValue *GVal = M->getNamedValue(ComdatName);
928 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
929 GVal = GA->getBaseObject();
931 // We cannot resolve the size of the aliasee yet.
932 return emitError("Linking COMDATs named '" + ComdatName +
933 "': COMDAT key involves incomputable alias size.");
936 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
939 "Linking COMDATs named '" + ComdatName +
940 "': GlobalVariable required for data dependent selection!");
945 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
946 Comdat::SelectionKind Src,
947 Comdat::SelectionKind Dst,
948 Comdat::SelectionKind &Result,
950 // The ability to mix Comdat::SelectionKind::Any with
951 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
952 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
953 Dst == Comdat::SelectionKind::Largest;
954 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
955 Src == Comdat::SelectionKind::Largest;
956 if (DstAnyOrLargest && SrcAnyOrLargest) {
957 if (Dst == Comdat::SelectionKind::Largest ||
958 Src == Comdat::SelectionKind::Largest)
959 Result = Comdat::SelectionKind::Largest;
961 Result = Comdat::SelectionKind::Any;
962 } else if (Src == Dst) {
965 return emitError("Linking COMDATs named '" + ComdatName +
966 "': invalid selection kinds!");
970 case Comdat::SelectionKind::Any:
974 case Comdat::SelectionKind::NoDuplicates:
975 return emitError("Linking COMDATs named '" + ComdatName +
976 "': noduplicates has been violated!");
977 case Comdat::SelectionKind::ExactMatch:
978 case Comdat::SelectionKind::Largest:
979 case Comdat::SelectionKind::SameSize: {
980 const GlobalVariable *DstGV;
981 const GlobalVariable *SrcGV;
982 if (getComdatLeader(DstM, ComdatName, DstGV) ||
983 getComdatLeader(SrcM, ComdatName, SrcGV))
986 const DataLayout &DstDL = DstM->getDataLayout();
987 const DataLayout &SrcDL = SrcM->getDataLayout();
989 DstDL.getTypeAllocSize(DstGV->getType()->getPointerElementType());
991 SrcDL.getTypeAllocSize(SrcGV->getType()->getPointerElementType());
992 if (Result == Comdat::SelectionKind::ExactMatch) {
993 if (SrcGV->getInitializer() != DstGV->getInitializer())
994 return emitError("Linking COMDATs named '" + ComdatName +
995 "': ExactMatch violated!");
997 } else if (Result == Comdat::SelectionKind::Largest) {
998 LinkFromSrc = SrcSize > DstSize;
999 } else if (Result == Comdat::SelectionKind::SameSize) {
1000 if (SrcSize != DstSize)
1001 return emitError("Linking COMDATs named '" + ComdatName +
1002 "': SameSize violated!");
1003 LinkFromSrc = false;
1005 llvm_unreachable("unknown selection kind");
1014 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
1015 Comdat::SelectionKind &Result,
1016 bool &LinkFromSrc) {
1017 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
1018 StringRef ComdatName = SrcC->getName();
1019 Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable();
1020 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
1022 if (DstCI == ComdatSymTab.end()) {
1023 // Use the comdat if it is only available in one of the modules.
1029 const Comdat *DstC = &DstCI->second;
1030 Comdat::SelectionKind DSK = DstC->getSelectionKind();
1031 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
1035 bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
1036 const GlobalValue &Dest,
1037 const GlobalValue &Src) {
1038 // Should we unconditionally use the Src?
1039 if (shouldOverrideFromSrc()) {
1044 // We always have to add Src if it has appending linkage.
1045 if (Src.hasAppendingLinkage()) {
1046 // Caller should have already determined that we can't link from source
1047 // when importing (see comments in linkGlobalValueProto).
1048 assert(!isPerformingImport());
1053 bool SrcIsDeclaration = Src.isDeclarationForLinker();
1054 bool DestIsDeclaration = Dest.isDeclarationForLinker();
1056 if (isPerformingImport()) {
1057 if (isa<Function>(&Src)) {
1058 // For functions, LinkFromSrc iff this is the function requested
1059 // for importing. For variables, decide below normally.
1060 LinkFromSrc = (&Src == ImportFunction);
1064 // Check if this is an alias with an already existing definition
1065 // in Dest, which must have come from a prior importing pass from
1066 // the same Src module. Unlike imported function and variable
1067 // definitions, which are imported as available_externally and are
1068 // not definitions for the linker, that is not a valid linkage for
1069 // imported aliases which must be definitions. Simply use the existing
1071 if (isa<GlobalAlias>(&Src) && !DestIsDeclaration) {
1072 assert(isa<GlobalAlias>(&Dest));
1073 LinkFromSrc = false;
1078 if (SrcIsDeclaration) {
1079 // If Src is external or if both Src & Dest are external.. Just link the
1080 // external globals, we aren't adding anything.
1081 if (Src.hasDLLImportStorageClass()) {
1082 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
1083 LinkFromSrc = DestIsDeclaration;
1086 // If the Dest is weak, use the source linkage.
1087 LinkFromSrc = Dest.hasExternalWeakLinkage();
1091 if (DestIsDeclaration) {
1092 // If Dest is external but Src is not:
1097 if (Src.hasCommonLinkage()) {
1098 if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
1103 if (!Dest.hasCommonLinkage()) {
1104 LinkFromSrc = false;
1108 const DataLayout &DL = Dest.getParent()->getDataLayout();
1109 uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
1110 uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
1111 LinkFromSrc = SrcSize > DestSize;
1115 if (Src.isWeakForLinker()) {
1116 assert(!Dest.hasExternalWeakLinkage());
1117 assert(!Dest.hasAvailableExternallyLinkage());
1119 if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
1124 LinkFromSrc = false;
1128 if (Dest.isWeakForLinker()) {
1129 assert(Src.hasExternalLinkage());
1134 assert(!Src.hasExternalWeakLinkage());
1135 assert(!Dest.hasExternalWeakLinkage());
1136 assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
1137 "Unexpected linkage type!");
1138 return emitError("Linking globals named '" + Src.getName() +
1139 "': symbol multiply defined!");
1142 /// Loop over all of the linked values to compute type mappings. For example,
1143 /// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct
1144 /// types 'Foo' but one got renamed when the module was loaded into the same
1146 void ModuleLinker::computeTypeMapping() {
1147 for (GlobalValue &SGV : SrcM->globals()) {
1148 GlobalValue *DGV = getLinkedToGlobal(&SGV);
1152 if (!DGV->hasAppendingLinkage() || !SGV.hasAppendingLinkage()) {
1153 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1157 // Unify the element type of appending arrays.
1158 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
1159 ArrayType *SAT = cast<ArrayType>(SGV.getType()->getElementType());
1160 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
1163 for (GlobalValue &SGV : *SrcM) {
1164 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
1165 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1168 for (GlobalValue &SGV : SrcM->aliases()) {
1169 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
1170 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1173 // Incorporate types by name, scanning all the types in the source module.
1174 // At this point, the destination module may have a type "%foo = { i32 }" for
1175 // example. When the source module got loaded into the same LLVMContext, if
1176 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
1177 std::vector<StructType *> Types = SrcM->getIdentifiedStructTypes();
1178 for (StructType *ST : Types) {
1182 // Check to see if there is a dot in the name followed by a digit.
1183 size_t DotPos = ST->getName().rfind('.');
1184 if (DotPos == 0 || DotPos == StringRef::npos ||
1185 ST->getName().back() == '.' ||
1186 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos + 1])))
1189 // Check to see if the destination module has a struct with the prefix name.
1190 StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos));
1194 // Don't use it if this actually came from the source module. They're in
1195 // the same LLVMContext after all. Also don't use it unless the type is
1196 // actually used in the destination module. This can happen in situations
1199 // Module A Module B
1200 // -------- --------
1201 // %Z = type { %A } %B = type { %C.1 }
1202 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
1203 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
1204 // %C = type { i8* } %B.3 = type { %C.1 }
1206 // When we link Module B with Module A, the '%B' in Module B is
1207 // used. However, that would then use '%C.1'. But when we process '%C.1',
1208 // we prefer to take the '%C' version. So we are then left with both
1209 // '%C.1' and '%C' being used for the same types. This leads to some
1210 // variables using one type and some using the other.
1211 if (TypeMap.DstStructTypesSet.hasType(DST))
1212 TypeMap.addTypeMapping(DST, ST);
1215 // Now that we have discovered all of the type equivalences, get a body for
1216 // any 'opaque' types in the dest module that are now resolved.
1217 TypeMap.linkDefinedTypeBodies();
1220 static void upgradeGlobalArray(GlobalVariable *GV) {
1221 ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
1222 StructType *OldTy = cast<StructType>(ATy->getElementType());
1223 assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
1225 // Get the upgraded 3 element type.
1226 PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
1227 Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
1229 StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
1231 // Build new constants with a null third field filled in.
1232 Constant *OldInitC = GV->getInitializer();
1233 ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
1234 if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
1235 // Invalid initializer; give up.
1237 std::vector<Constant *> Initializers;
1238 if (OldInit && OldInit->getNumOperands()) {
1239 Value *Null = Constant::getNullValue(VoidPtrTy);
1240 for (Use &U : OldInit->operands()) {
1241 ConstantStruct *Init = cast<ConstantStruct>(U.get());
1242 Initializers.push_back(ConstantStruct::get(
1243 NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
1246 assert(Initializers.size() == ATy->getNumElements() &&
1247 "Failed to copy all array elements");
1249 // Replace the old GV with a new one.
1250 ATy = ArrayType::get(NewTy, Initializers.size());
1251 Constant *NewInit = ConstantArray::get(ATy, Initializers);
1252 GlobalVariable *NewGV = new GlobalVariable(
1253 *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
1254 GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
1255 GV->isExternallyInitialized());
1256 NewGV->copyAttributesFrom(GV);
1257 NewGV->takeName(GV);
1258 assert(GV->use_empty() && "program cannot use initializer list");
1259 GV->eraseFromParent();
1262 void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
1263 // Look for the global arrays.
1264 auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM->getNamedValue(Name));
1267 auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM->getNamedValue(Name));
1271 // Check if the types already match.
1272 auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
1274 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
1278 // Grab the element types. We can only upgrade an array of a two-field
1279 // struct. Only bother if the other one has three-fields.
1280 auto *DstEltTy = cast<StructType>(DstTy->getElementType());
1281 auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
1282 if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
1283 upgradeGlobalArray(DstGV);
1286 if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
1287 upgradeGlobalArray(SrcGV);
1289 // We can't upgrade any other differences.
1292 void ModuleLinker::upgradeMismatchedGlobals() {
1293 upgradeMismatchedGlobalArray("llvm.global_ctors");
1294 upgradeMismatchedGlobalArray("llvm.global_dtors");
1297 /// If there were any appending global variables, link them together now.
1298 /// Return true on error.
1299 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
1300 const GlobalVariable *SrcGV) {
1302 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
1303 return emitError("Linking globals named '" + SrcGV->getName() +
1304 "': can only link appending global with another appending global!");
1306 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
1308 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
1309 Type *EltTy = DstTy->getElementType();
1311 // Check to see that they two arrays agree on type.
1312 if (EltTy != SrcTy->getElementType())
1313 return emitError("Appending variables with different element types!");
1314 if (DstGV->isConstant() != SrcGV->isConstant())
1315 return emitError("Appending variables linked with different const'ness!");
1317 if (DstGV->getAlignment() != SrcGV->getAlignment())
1319 "Appending variables with different alignment need to be linked!");
1321 if (DstGV->getVisibility() != SrcGV->getVisibility())
1323 "Appending variables with different visibility need to be linked!");
1325 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
1327 "Appending variables with different unnamed_addr need to be linked!");
1329 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
1331 "Appending variables with different section name need to be linked!");
1333 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements();
1334 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
1336 // Create the new global variable.
1337 GlobalVariable *NG =
1338 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(),
1339 DstGV->getLinkage(), /*init*/nullptr, /*name*/"", DstGV,
1340 DstGV->getThreadLocalMode(),
1341 DstGV->getType()->getAddressSpace());
1343 // Propagate alignment, visibility and section info.
1344 copyGVAttributes(NG, DstGV);
1346 AppendingVarInfo AVI;
1348 AVI.DstInit = DstGV->getInitializer();
1349 AVI.SrcInit = SrcGV->getInitializer();
1350 AppendingVars.push_back(AVI);
1352 // Replace any uses of the two global variables with uses of the new
1354 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
1356 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
1357 DstGV->eraseFromParent();
1359 // Track the source variable so we don't try to link it.
1360 DoNotLinkFromSource.insert(SrcGV);
1365 bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) {
1366 GlobalValue *DGV = getLinkedToGlobal(SGV);
1368 // Handle the ultra special appending linkage case first.
1369 assert(!DGV || SGV->hasAppendingLinkage() == DGV->hasAppendingLinkage());
1370 if (SGV->hasAppendingLinkage() && isPerformingImport()) {
1371 // Don't want to append to global_ctors list, for example, when we
1372 // are importing for ThinLTO, otherwise the global ctors and dtors
1373 // get executed multiple times for local variables (the latter causing
1375 DoNotLinkFromSource.insert(SGV);
1378 if (DGV && DGV->hasAppendingLinkage())
1379 return linkAppendingVarProto(cast<GlobalVariable>(DGV),
1380 cast<GlobalVariable>(SGV));
1382 bool LinkFromSrc = true;
1383 Comdat *C = nullptr;
1384 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
1386 if (const Comdat *SC = SGV->getComdat()) {
1387 Comdat::SelectionKind SK;
1388 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1389 C = DstM->getOrInsertComdat(SC->getName());
1390 C->setSelectionKind(SK);
1391 ComdatMembers[SC].push_back(SGV);
1393 if (shouldLinkFromSource(LinkFromSrc, *DGV, *SGV))
1398 // Track the source global so that we don't attempt to copy it over when
1399 // processing global initializers.
1400 DoNotLinkFromSource.insert(SGV);
1403 // Make sure to remember this mapping.
1405 ConstantExpr::getBitCast(DGV, TypeMap.get(SGV->getType()));
1409 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1411 if (!LinkFromSrc && !DGV)
1417 // When linking from source we setVisibility from copyGlobalValueProto.
1418 setVisibility(NewGV, SGV, DGV);
1420 // If the GV is to be lazily linked, don't create it just yet.
1421 // The ValueMaterializerTy will deal with creating it if it's used.
1422 if (!DGV && !shouldOverrideFromSrc() && SGV != ImportFunction &&
1423 (SGV->hasLocalLinkage() || SGV->hasLinkOnceLinkage() ||
1424 SGV->hasAvailableExternallyLinkage())) {
1425 DoNotLinkFromSource.insert(SGV);
1429 // When we only want to link in unresolved dependencies, blacklist
1430 // the symbol unless unless DestM has a matching declaration (DGV).
1431 if (shouldLinkOnlyNeeded() && !(DGV && DGV->isDeclaration())) {
1432 DoNotLinkFromSource.insert(SGV);
1436 NewGV = copyGlobalValueProto(TypeMap, SGV, DGV);
1438 if (isPerformingImport() && !doImportAsDefinition(SGV))
1439 DoNotLinkFromSource.insert(SGV);
1442 NewGV->setUnnamedAddr(HasUnnamedAddr);
1444 if (auto *NewGO = dyn_cast<GlobalObject>(NewGV)) {
1446 NewGO->setComdat(C);
1448 if (DGV && DGV->hasCommonLinkage() && SGV->hasCommonLinkage())
1449 NewGO->setAlignment(std::max(DGV->getAlignment(), SGV->getAlignment()));
1452 if (auto *NewGVar = dyn_cast<GlobalVariable>(NewGV)) {
1453 auto *DGVar = dyn_cast_or_null<GlobalVariable>(DGV);
1454 auto *SGVar = dyn_cast<GlobalVariable>(SGV);
1455 if (DGVar && SGVar && DGVar->isDeclaration() && SGVar->isDeclaration() &&
1456 (!DGVar->isConstant() || !SGVar->isConstant()))
1457 NewGVar->setConstant(false);
1460 // Make sure to remember this mapping.
1463 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewGV, DGV->getType()));
1464 DGV->eraseFromParent();
1466 ValueMap[SGV] = NewGV;
1472 static void getArrayElements(const Constant *C,
1473 SmallVectorImpl<Constant *> &Dest) {
1474 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1476 for (unsigned i = 0; i != NumElements; ++i)
1477 Dest.push_back(C->getAggregateElement(i));
1480 void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) {
1481 // Merge the initializer.
1482 SmallVector<Constant *, 16> DstElements;
1483 getArrayElements(AVI.DstInit, DstElements);
1485 SmallVector<Constant *, 16> SrcElements;
1486 getArrayElements(AVI.SrcInit, SrcElements);
1488 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
1490 StringRef Name = AVI.NewGV->getName();
1491 bool IsNewStructor =
1492 (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
1493 cast<StructType>(NewType->getElementType())->getNumElements() == 3;
1495 for (auto *V : SrcElements) {
1496 if (IsNewStructor) {
1497 Constant *Key = V->getAggregateElement(2);
1498 if (DoNotLinkFromSource.count(Key))
1501 DstElements.push_back(
1502 MapValue(V, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1504 if (IsNewStructor) {
1505 NewType = ArrayType::get(NewType->getElementType(), DstElements.size());
1506 AVI.NewGV->mutateType(PointerType::get(NewType, 0));
1509 AVI.NewGV->setInitializer(ConstantArray::get(NewType, DstElements));
1512 /// Update the initializers in the Dest module now that all globals that may be
1513 /// referenced are in Dest.
1514 void ModuleLinker::linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src) {
1515 // Figure out what the initializer looks like in the dest module.
1516 Dst.setInitializer(MapValue(Src.getInitializer(), ValueMap,
1517 RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1520 /// Copy the source function over into the dest function and fix up references
1521 /// to values. At this point we know that Dest is an external function, and
1522 /// that Src is not.
1523 bool ModuleLinker::linkFunctionBody(Function &Dst, Function &Src) {
1524 assert(Dst.isDeclaration() && !Src.isDeclaration());
1526 // Materialize if needed.
1527 if (std::error_code EC = Src.materialize())
1528 return emitError(EC.message());
1530 // Link in the prefix data.
1531 if (Src.hasPrefixData())
1532 Dst.setPrefixData(MapValue(Src.getPrefixData(), ValueMap,
1533 RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1535 // Link in the prologue data.
1536 if (Src.hasPrologueData())
1537 Dst.setPrologueData(MapValue(Src.getPrologueData(), ValueMap,
1538 RF_MoveDistinctMDs, &TypeMap,
1541 // Link in the personality function.
1542 if (Src.hasPersonalityFn())
1543 Dst.setPersonalityFn(MapValue(Src.getPersonalityFn(), ValueMap,
1544 RF_MoveDistinctMDs, &TypeMap,
1547 // Go through and convert function arguments over, remembering the mapping.
1548 Function::arg_iterator DI = Dst.arg_begin();
1549 for (Argument &Arg : Src.args()) {
1550 DI->setName(Arg.getName()); // Copy the name over.
1552 // Add a mapping to our mapping.
1553 ValueMap[&Arg] = &*DI;
1557 // Copy over the metadata attachments.
1558 SmallVector<std::pair<unsigned, MDNode *>, 8> MDs;
1559 Src.getAllMetadata(MDs);
1560 for (const auto &I : MDs)
1561 Dst.setMetadata(I.first, MapMetadata(I.second, ValueMap, RF_MoveDistinctMDs,
1562 &TypeMap, &ValMaterializer));
1564 // Splice the body of the source function into the dest function.
1565 Dst.getBasicBlockList().splice(Dst.end(), Src.getBasicBlockList());
1567 // At this point, all of the instructions and values of the function are now
1568 // copied over. The only problem is that they are still referencing values in
1569 // the Source function as operands. Loop through all of the operands of the
1570 // functions and patch them up to point to the local versions.
1571 for (BasicBlock &BB : Dst)
1572 for (Instruction &I : BB)
1573 RemapInstruction(&I, ValueMap,
1574 RF_IgnoreMissingEntries | RF_MoveDistinctMDs, &TypeMap,
1577 // There is no need to map the arguments anymore.
1578 for (Argument &Arg : Src.args())
1579 ValueMap.erase(&Arg);
1581 Src.dematerialize();
1585 void ModuleLinker::linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src) {
1586 Constant *Aliasee = Src.getAliasee();
1587 Constant *Val = MapValue(Aliasee, ValueMap, RF_MoveDistinctMDs, &TypeMap,
1589 Dst.setAliasee(Val);
1592 bool ModuleLinker::linkGlobalValueBody(GlobalValue &Src) {
1593 Value *Dst = ValueMap[&Src];
1595 if (const Comdat *SC = Src.getComdat()) {
1596 // To ensure that we don't generate an incomplete comdat group,
1597 // we must materialize and map in any other members that are not
1598 // yet materialized in Dst, which also ensures their definitions
1599 // are linked in. Otherwise, linkonce and other lazy linked GVs will
1600 // not be materialized if they aren't referenced.
1601 for (auto *SGV : ComdatMembers[SC]) {
1604 Value *NewV = ValMaterializer.materializeValueFor(SGV);
1605 ValueMap[SGV] = NewV;
1608 if (shouldInternalizeLinkedSymbols())
1609 if (auto *DGV = dyn_cast<GlobalValue>(Dst))
1610 DGV->setLinkage(GlobalValue::InternalLinkage);
1611 if (auto *F = dyn_cast<Function>(&Src))
1612 return linkFunctionBody(cast<Function>(*Dst), *F);
1613 if (auto *GVar = dyn_cast<GlobalVariable>(&Src)) {
1614 linkGlobalInit(cast<GlobalVariable>(*Dst), *GVar);
1617 linkAliasBody(cast<GlobalAlias>(*Dst), cast<GlobalAlias>(Src));
1621 /// Insert all of the named MDNodes in Src into the Dest module.
1622 void ModuleLinker::linkNamedMDNodes() {
1623 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1624 for (const NamedMDNode &NMD : SrcM->named_metadata()) {
1625 // Don't link module flags here. Do them separately.
1626 if (&NMD == SrcModFlags)
1628 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(NMD.getName());
1629 // Add Src elements into Dest node.
1630 for (const MDNode *op : NMD.operands())
1631 DestNMD->addOperand(MapMetadata(
1632 op, ValueMap, RF_MoveDistinctMDs | RF_NullMapMissingGlobalValues,
1633 &TypeMap, &ValMaterializer));
1637 /// Merge the linker flags in Src into the Dest module.
1638 bool ModuleLinker::linkModuleFlagsMetadata() {
1639 // If the source module has no module flags, we are done.
1640 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1641 if (!SrcModFlags) return false;
1643 // If the destination module doesn't have module flags yet, then just copy
1644 // over the source module's flags.
1645 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
1646 if (DstModFlags->getNumOperands() == 0) {
1647 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1648 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1653 // First build a map of the existing module flags and requirements.
1654 DenseMap<MDString *, std::pair<MDNode *, unsigned>> Flags;
1655 SmallSetVector<MDNode*, 16> Requirements;
1656 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1657 MDNode *Op = DstModFlags->getOperand(I);
1658 ConstantInt *Behavior = mdconst::extract<ConstantInt>(Op->getOperand(0));
1659 MDString *ID = cast<MDString>(Op->getOperand(1));
1661 if (Behavior->getZExtValue() == Module::Require) {
1662 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1664 Flags[ID] = std::make_pair(Op, I);
1668 // Merge in the flags from the source module, and also collect its set of
1670 bool HasErr = false;
1671 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1672 MDNode *SrcOp = SrcModFlags->getOperand(I);
1673 ConstantInt *SrcBehavior =
1674 mdconst::extract<ConstantInt>(SrcOp->getOperand(0));
1675 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1678 std::tie(DstOp, DstIndex) = Flags.lookup(ID);
1679 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1681 // If this is a requirement, add it and continue.
1682 if (SrcBehaviorValue == Module::Require) {
1683 // If the destination module does not already have this requirement, add
1685 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1686 DstModFlags->addOperand(SrcOp);
1691 // If there is no existing flag with this ID, just add it.
1693 Flags[ID] = std::make_pair(SrcOp, DstModFlags->getNumOperands());
1694 DstModFlags->addOperand(SrcOp);
1698 // Otherwise, perform a merge.
1699 ConstantInt *DstBehavior =
1700 mdconst::extract<ConstantInt>(DstOp->getOperand(0));
1701 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1703 // If either flag has override behavior, handle it first.
1704 if (DstBehaviorValue == Module::Override) {
1705 // Diagnose inconsistent flags which both have override behavior.
1706 if (SrcBehaviorValue == Module::Override &&
1707 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1708 HasErr |= emitError("linking module flags '" + ID->getString() +
1709 "': IDs have conflicting override values");
1712 } else if (SrcBehaviorValue == Module::Override) {
1713 // Update the destination flag to that of the source.
1714 DstModFlags->setOperand(DstIndex, SrcOp);
1715 Flags[ID].first = SrcOp;
1719 // Diagnose inconsistent merge behavior types.
1720 if (SrcBehaviorValue != DstBehaviorValue) {
1721 HasErr |= emitError("linking module flags '" + ID->getString() +
1722 "': IDs have conflicting behaviors");
1726 auto replaceDstValue = [&](MDNode *New) {
1727 Metadata *FlagOps[] = {DstOp->getOperand(0), ID, New};
1728 MDNode *Flag = MDNode::get(DstM->getContext(), FlagOps);
1729 DstModFlags->setOperand(DstIndex, Flag);
1730 Flags[ID].first = Flag;
1733 // Perform the merge for standard behavior types.
1734 switch (SrcBehaviorValue) {
1735 case Module::Require:
1736 case Module::Override: llvm_unreachable("not possible");
1737 case Module::Error: {
1738 // Emit an error if the values differ.
1739 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1740 HasErr |= emitError("linking module flags '" + ID->getString() +
1741 "': IDs have conflicting values");
1745 case Module::Warning: {
1746 // Emit a warning if the values differ.
1747 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1748 emitWarning("linking module flags '" + ID->getString() +
1749 "': IDs have conflicting values");
1753 case Module::Append: {
1754 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1755 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1756 SmallVector<Metadata *, 8> MDs;
1757 MDs.reserve(DstValue->getNumOperands() + SrcValue->getNumOperands());
1758 MDs.append(DstValue->op_begin(), DstValue->op_end());
1759 MDs.append(SrcValue->op_begin(), SrcValue->op_end());
1761 replaceDstValue(MDNode::get(DstM->getContext(), MDs));
1764 case Module::AppendUnique: {
1765 SmallSetVector<Metadata *, 16> Elts;
1766 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1767 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1768 Elts.insert(DstValue->op_begin(), DstValue->op_end());
1769 Elts.insert(SrcValue->op_begin(), SrcValue->op_end());
1771 replaceDstValue(MDNode::get(DstM->getContext(),
1772 makeArrayRef(Elts.begin(), Elts.end())));
1778 // Check all of the requirements.
1779 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1780 MDNode *Requirement = Requirements[I];
1781 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1782 Metadata *ReqValue = Requirement->getOperand(1);
1784 MDNode *Op = Flags[Flag].first;
1785 if (!Op || Op->getOperand(2) != ReqValue) {
1786 HasErr |= emitError("linking module flags '" + Flag->getString() +
1787 "': does not have the required value");
1795 // This function returns true if the triples match.
1796 static bool triplesMatch(const Triple &T0, const Triple &T1) {
1797 // If vendor is apple, ignore the version number.
1798 if (T0.getVendor() == Triple::Apple)
1799 return T0.getArch() == T1.getArch() &&
1800 T0.getSubArch() == T1.getSubArch() &&
1801 T0.getVendor() == T1.getVendor() &&
1802 T0.getOS() == T1.getOS();
1807 // This function returns the merged triple.
1808 static std::string mergeTriples(const Triple &SrcTriple, const Triple &DstTriple) {
1809 // If vendor is apple, pick the triple with the larger version number.
1810 if (SrcTriple.getVendor() == Triple::Apple)
1811 if (DstTriple.isOSVersionLT(SrcTriple))
1812 return SrcTriple.str();
1814 return DstTriple.str();
1817 bool ModuleLinker::run() {
1818 assert(DstM && "Null destination module");
1819 assert(SrcM && "Null source module");
1821 // Inherit the target data from the source module if the destination module
1822 // doesn't have one already.
1823 if (DstM->getDataLayout().isDefault())
1824 DstM->setDataLayout(SrcM->getDataLayout());
1826 if (SrcM->getDataLayout() != DstM->getDataLayout()) {
1827 emitWarning("Linking two modules of different data layouts: '" +
1828 SrcM->getModuleIdentifier() + "' is '" +
1829 SrcM->getDataLayoutStr() + "' whereas '" +
1830 DstM->getModuleIdentifier() + "' is '" +
1831 DstM->getDataLayoutStr() + "'\n");
1834 // Copy the target triple from the source to dest if the dest's is empty.
1835 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
1836 DstM->setTargetTriple(SrcM->getTargetTriple());
1838 Triple SrcTriple(SrcM->getTargetTriple()), DstTriple(DstM->getTargetTriple());
1840 if (!SrcM->getTargetTriple().empty() && !triplesMatch(SrcTriple, DstTriple))
1841 emitWarning("Linking two modules of different target triples: " +
1842 SrcM->getModuleIdentifier() + "' is '" +
1843 SrcM->getTargetTriple() + "' whereas '" +
1844 DstM->getModuleIdentifier() + "' is '" +
1845 DstM->getTargetTriple() + "'\n");
1847 DstM->setTargetTriple(mergeTriples(SrcTriple, DstTriple));
1849 // Append the module inline asm string.
1850 if (!SrcM->getModuleInlineAsm().empty()) {
1851 if (DstM->getModuleInlineAsm().empty())
1852 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
1854 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
1855 SrcM->getModuleInlineAsm());
1858 // Loop over all of the linked values to compute type mappings.
1859 computeTypeMapping();
1861 ComdatsChosen.clear();
1862 for (const auto &SMEC : SrcM->getComdatSymbolTable()) {
1863 const Comdat &C = SMEC.getValue();
1864 if (ComdatsChosen.count(&C))
1866 Comdat::SelectionKind SK;
1868 if (getComdatResult(&C, SK, LinkFromSrc))
1870 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1873 // Upgrade mismatched global arrays.
1874 upgradeMismatchedGlobals();
1876 // Insert all of the globals in src into the DstM module... without linking
1877 // initializers (which could refer to functions not yet mapped over).
1878 for (GlobalVariable &GV : SrcM->globals())
1879 if (linkGlobalValueProto(&GV))
1882 // Link the functions together between the two modules, without doing function
1883 // bodies... this just adds external function prototypes to the DstM
1884 // function... We do this so that when we begin processing function bodies,
1885 // all of the global values that may be referenced are available in our
1887 for (Function &F :*SrcM)
1888 if (linkGlobalValueProto(&F))
1891 // If there were any aliases, link them now.
1892 for (GlobalAlias &GA : SrcM->aliases())
1893 if (linkGlobalValueProto(&GA))
1896 for (const AppendingVarInfo &AppendingVar : AppendingVars)
1897 linkAppendingVarInit(AppendingVar);
1899 for (const auto &Entry : DstM->getComdatSymbolTable()) {
1900 const Comdat &C = Entry.getValue();
1901 if (C.getSelectionKind() == Comdat::Any)
1903 const GlobalValue *GV = SrcM->getNamedValue(C.getName());
1905 MapValue(GV, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer);
1908 // Link in the function bodies that are defined in the source module into
1910 for (Function &SF : *SrcM) {
1911 // Skip if no body (function is external).
1912 if (SF.isDeclaration())
1915 // Skip if not linking from source.
1916 if (DoNotLinkFromSource.count(&SF))
1919 if (linkGlobalValueBody(SF))
1923 // Resolve all uses of aliases with aliasees.
1924 for (GlobalAlias &Src : SrcM->aliases()) {
1925 if (DoNotLinkFromSource.count(&Src))
1927 linkGlobalValueBody(Src);
1930 // Update the initializers in the DstM module now that all globals that may
1931 // be referenced are in DstM.
1932 for (GlobalVariable &Src : SrcM->globals()) {
1933 // Only process initialized GV's or ones not already in dest.
1934 if (!Src.hasInitializer() || DoNotLinkFromSource.count(&Src))
1936 linkGlobalValueBody(Src);
1939 // Process vector of lazily linked in functions.
1940 while (!LazilyLinkGlobalValues.empty()) {
1941 GlobalValue *SGV = LazilyLinkGlobalValues.back();
1942 LazilyLinkGlobalValues.pop_back();
1943 if (isPerformingImport() && !doImportAsDefinition(SGV))
1946 // Skip declarations that ValueMaterializer may have created in
1947 // case we link in only some of SrcM.
1948 if (shouldLinkOnlyNeeded() && SGV->isDeclaration())
1951 assert(!SGV->isDeclaration() && "users should not pass down decls");
1952 if (linkGlobalValueBody(*SGV))
1956 // Note that we are done linking global value bodies. This prevents
1957 // metadata linking from creating new references.
1958 DoneLinkingBodies = true;
1960 // Remap all of the named MDNodes in Src into the DstM module. We do this
1961 // after linking GlobalValues so that MDNodes that reference GlobalValues
1962 // are properly remapped.
1965 // Merge the module flags into the DstM module.
1966 if (linkModuleFlagsMetadata())
1972 Linker::StructTypeKeyInfo::KeyTy::KeyTy(ArrayRef<Type *> E, bool P)
1973 : ETypes(E), IsPacked(P) {}
1975 Linker::StructTypeKeyInfo::KeyTy::KeyTy(const StructType *ST)
1976 : ETypes(ST->elements()), IsPacked(ST->isPacked()) {}
1978 bool Linker::StructTypeKeyInfo::KeyTy::operator==(const KeyTy &That) const {
1979 if (IsPacked != That.IsPacked)
1981 if (ETypes != That.ETypes)
1986 bool Linker::StructTypeKeyInfo::KeyTy::operator!=(const KeyTy &That) const {
1987 return !this->operator==(That);
1990 StructType *Linker::StructTypeKeyInfo::getEmptyKey() {
1991 return DenseMapInfo<StructType *>::getEmptyKey();
1994 StructType *Linker::StructTypeKeyInfo::getTombstoneKey() {
1995 return DenseMapInfo<StructType *>::getTombstoneKey();
1998 unsigned Linker::StructTypeKeyInfo::getHashValue(const KeyTy &Key) {
1999 return hash_combine(hash_combine_range(Key.ETypes.begin(), Key.ETypes.end()),
2003 unsigned Linker::StructTypeKeyInfo::getHashValue(const StructType *ST) {
2004 return getHashValue(KeyTy(ST));
2007 bool Linker::StructTypeKeyInfo::isEqual(const KeyTy &LHS,
2008 const StructType *RHS) {
2009 if (RHS == getEmptyKey() || RHS == getTombstoneKey())
2011 return LHS == KeyTy(RHS);
2014 bool Linker::StructTypeKeyInfo::isEqual(const StructType *LHS,
2015 const StructType *RHS) {
2016 if (RHS == getEmptyKey())
2017 return LHS == getEmptyKey();
2019 if (RHS == getTombstoneKey())
2020 return LHS == getTombstoneKey();
2022 return KeyTy(LHS) == KeyTy(RHS);
2025 void Linker::IdentifiedStructTypeSet::addNonOpaque(StructType *Ty) {
2026 assert(!Ty->isOpaque());
2027 NonOpaqueStructTypes.insert(Ty);
2030 void Linker::IdentifiedStructTypeSet::switchToNonOpaque(StructType *Ty) {
2031 assert(!Ty->isOpaque());
2032 NonOpaqueStructTypes.insert(Ty);
2033 bool Removed = OpaqueStructTypes.erase(Ty);
2038 void Linker::IdentifiedStructTypeSet::addOpaque(StructType *Ty) {
2039 assert(Ty->isOpaque());
2040 OpaqueStructTypes.insert(Ty);
2044 Linker::IdentifiedStructTypeSet::findNonOpaque(ArrayRef<Type *> ETypes,
2046 Linker::StructTypeKeyInfo::KeyTy Key(ETypes, IsPacked);
2047 auto I = NonOpaqueStructTypes.find_as(Key);
2048 if (I == NonOpaqueStructTypes.end())
2053 bool Linker::IdentifiedStructTypeSet::hasType(StructType *Ty) {
2055 return OpaqueStructTypes.count(Ty);
2056 auto I = NonOpaqueStructTypes.find(Ty);
2057 if (I == NonOpaqueStructTypes.end())
2062 void Linker::init(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
2063 this->Composite = M;
2064 this->DiagnosticHandler = DiagnosticHandler;
2066 TypeFinder StructTypes;
2067 StructTypes.run(*M, true);
2068 for (StructType *Ty : StructTypes) {
2070 IdentifiedStructTypes.addOpaque(Ty);
2072 IdentifiedStructTypes.addNonOpaque(Ty);
2076 Linker::Linker(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
2077 init(M, DiagnosticHandler);
2080 Linker::Linker(Module *M) {
2081 init(M, [this](const DiagnosticInfo &DI) {
2082 Composite->getContext().diagnose(DI);
2086 void Linker::deleteModule() {
2088 Composite = nullptr;
2091 bool Linker::linkInModule(Module *Src, unsigned Flags, FunctionInfoIndex *Index,
2092 Function *FuncToImport) {
2093 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,
2094 DiagnosticHandler, Flags, Index, FuncToImport);
2095 bool RetCode = TheLinker.run();
2096 Composite->dropTriviallyDeadConstantArrays();
2100 void Linker::setModule(Module *Dst) {
2101 init(Dst, DiagnosticHandler);
2104 //===----------------------------------------------------------------------===//
2105 // LinkModules entrypoint.
2106 //===----------------------------------------------------------------------===//
2108 /// This function links two modules together, with the resulting Dest module
2109 /// modified to be the composite of the two input modules. If an error occurs,
2110 /// true is returned and ErrorMsg (if not null) is set to indicate the problem.
2111 /// Upon failure, the Dest module could be in a modified state, and shouldn't be
2112 /// relied on to be consistent.
2113 bool Linker::LinkModules(Module *Dest, Module *Src,
2114 DiagnosticHandlerFunction DiagnosticHandler,
2116 Linker L(Dest, DiagnosticHandler);
2117 return L.linkInModule(Src, Flags);
2120 bool Linker::LinkModules(Module *Dest, Module *Src, unsigned Flags) {
2122 return L.linkInModule(Src, Flags);
2125 //===----------------------------------------------------------------------===//
2127 //===----------------------------------------------------------------------===//
2129 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
2130 LLVMLinkerMode Unused, char **OutMessages) {
2131 Module *D = unwrap(Dest);
2132 std::string Message;
2133 raw_string_ostream Stream(Message);
2134 DiagnosticPrinterRawOStream DP(Stream);
2136 LLVMBool Result = Linker::LinkModules(
2137 D, unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); });
2139 if (OutMessages && Result) {
2141 *OutMessages = strdup(Message.c_str());