1 //===- lib/Linker/LinkModules.cpp - Module Linker Implementation ----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the LLVM module linker.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Linker/Linker.h"
15 #include "llvm-c/Linker.h"
16 #include "llvm/ADT/Hashing.h"
17 #include "llvm/ADT/Optional.h"
18 #include "llvm/ADT/SetVector.h"
19 #include "llvm/ADT/SmallString.h"
20 #include "llvm/ADT/Statistic.h"
21 #include "llvm/ADT/Triple.h"
22 #include "llvm/IR/Constants.h"
23 #include "llvm/IR/DebugInfo.h"
24 #include "llvm/IR/DiagnosticInfo.h"
25 #include "llvm/IR/DiagnosticPrinter.h"
26 #include "llvm/IR/LLVMContext.h"
27 #include "llvm/IR/Module.h"
28 #include "llvm/IR/TypeFinder.h"
29 #include "llvm/Support/CommandLine.h"
30 #include "llvm/Support/Debug.h"
31 #include "llvm/Support/raw_ostream.h"
32 #include "llvm/Transforms/Utils/Cloning.h"
38 //===----------------------------------------------------------------------===//
39 // TypeMap implementation.
40 //===----------------------------------------------------------------------===//
43 class TypeMapTy : public ValueMapTypeRemapper {
44 /// This is a mapping from a source type to a destination type to use.
45 DenseMap<Type*, Type*> MappedTypes;
47 /// When checking to see if two subgraphs are isomorphic, we speculatively
48 /// add types to MappedTypes, but keep track of them here in case we need to
50 SmallVector<Type*, 16> SpeculativeTypes;
52 SmallVector<StructType*, 16> SpeculativeDstOpaqueTypes;
54 /// This is a list of non-opaque structs in the source module that are mapped
55 /// to an opaque struct in the destination module.
56 SmallVector<StructType*, 16> SrcDefinitionsToResolve;
58 /// This is the set of opaque types in the destination modules who are
59 /// getting a body from the source module.
60 SmallPtrSet<StructType*, 16> DstResolvedOpaqueTypes;
63 TypeMapTy(Linker::IdentifiedStructTypeSet &DstStructTypesSet)
64 : DstStructTypesSet(DstStructTypesSet) {}
66 Linker::IdentifiedStructTypeSet &DstStructTypesSet;
67 /// Indicate that the specified type in the destination module is conceptually
68 /// equivalent to the specified type in the source module.
69 void addTypeMapping(Type *DstTy, Type *SrcTy);
71 /// Produce a body for an opaque type in the dest module from a type
72 /// definition in the source module.
73 void linkDefinedTypeBodies();
75 /// Return the mapped type to use for the specified input type from the
77 Type *get(Type *SrcTy);
78 Type *get(Type *SrcTy, SmallPtrSet<StructType *, 8> &Visited);
80 void finishType(StructType *DTy, StructType *STy, ArrayRef<Type *> ETypes);
82 FunctionType *get(FunctionType *T) {
83 return cast<FunctionType>(get((Type *)T));
86 /// Dump out the type map for debugging purposes.
88 for (auto &Pair : MappedTypes) {
89 dbgs() << "TypeMap: ";
90 Pair.first->print(dbgs());
92 Pair.second->print(dbgs());
98 Type *remapType(Type *SrcTy) override { return get(SrcTy); }
100 bool areTypesIsomorphic(Type *DstTy, Type *SrcTy);
104 void TypeMapTy::addTypeMapping(Type *DstTy, Type *SrcTy) {
105 assert(SpeculativeTypes.empty());
106 assert(SpeculativeDstOpaqueTypes.empty());
108 // Check to see if these types are recursively isomorphic and establish a
109 // mapping between them if so.
110 if (!areTypesIsomorphic(DstTy, SrcTy)) {
111 // Oops, they aren't isomorphic. Just discard this request by rolling out
112 // any speculative mappings we've established.
113 for (Type *Ty : SpeculativeTypes)
114 MappedTypes.erase(Ty);
116 SrcDefinitionsToResolve.resize(SrcDefinitionsToResolve.size() -
117 SpeculativeDstOpaqueTypes.size());
118 for (StructType *Ty : SpeculativeDstOpaqueTypes)
119 DstResolvedOpaqueTypes.erase(Ty);
121 for (Type *Ty : SpeculativeTypes)
122 if (auto *STy = dyn_cast<StructType>(Ty))
126 SpeculativeTypes.clear();
127 SpeculativeDstOpaqueTypes.clear();
130 /// Recursively walk this pair of types, returning true if they are isomorphic,
131 /// false if they are not.
132 bool TypeMapTy::areTypesIsomorphic(Type *DstTy, Type *SrcTy) {
133 // Two types with differing kinds are clearly not isomorphic.
134 if (DstTy->getTypeID() != SrcTy->getTypeID())
137 // If we have an entry in the MappedTypes table, then we have our answer.
138 Type *&Entry = MappedTypes[SrcTy];
140 return Entry == DstTy;
142 // Two identical types are clearly isomorphic. Remember this
143 // non-speculatively.
144 if (DstTy == SrcTy) {
149 // Okay, we have two types with identical kinds that we haven't seen before.
151 // If this is an opaque struct type, special case it.
152 if (StructType *SSTy = dyn_cast<StructType>(SrcTy)) {
153 // Mapping an opaque type to any struct, just keep the dest struct.
154 if (SSTy->isOpaque()) {
156 SpeculativeTypes.push_back(SrcTy);
160 // Mapping a non-opaque source type to an opaque dest. If this is the first
161 // type that we're mapping onto this destination type then we succeed. Keep
162 // the dest, but fill it in later. If this is the second (different) type
163 // that we're trying to map onto the same opaque type then we fail.
164 if (cast<StructType>(DstTy)->isOpaque()) {
165 // We can only map one source type onto the opaque destination type.
166 if (!DstResolvedOpaqueTypes.insert(cast<StructType>(DstTy)).second)
168 SrcDefinitionsToResolve.push_back(SSTy);
169 SpeculativeTypes.push_back(SrcTy);
170 SpeculativeDstOpaqueTypes.push_back(cast<StructType>(DstTy));
176 // If the number of subtypes disagree between the two types, then we fail.
177 if (SrcTy->getNumContainedTypes() != DstTy->getNumContainedTypes())
180 // Fail if any of the extra properties (e.g. array size) of the type disagree.
181 if (isa<IntegerType>(DstTy))
182 return false; // bitwidth disagrees.
183 if (PointerType *PT = dyn_cast<PointerType>(DstTy)) {
184 if (PT->getAddressSpace() != cast<PointerType>(SrcTy)->getAddressSpace())
187 } else if (FunctionType *FT = dyn_cast<FunctionType>(DstTy)) {
188 if (FT->isVarArg() != cast<FunctionType>(SrcTy)->isVarArg())
190 } else if (StructType *DSTy = dyn_cast<StructType>(DstTy)) {
191 StructType *SSTy = cast<StructType>(SrcTy);
192 if (DSTy->isLiteral() != SSTy->isLiteral() ||
193 DSTy->isPacked() != SSTy->isPacked())
195 } else if (ArrayType *DATy = dyn_cast<ArrayType>(DstTy)) {
196 if (DATy->getNumElements() != cast<ArrayType>(SrcTy)->getNumElements())
198 } else if (VectorType *DVTy = dyn_cast<VectorType>(DstTy)) {
199 if (DVTy->getNumElements() != cast<VectorType>(SrcTy)->getNumElements())
203 // Otherwise, we speculate that these two types will line up and recursively
204 // check the subelements.
206 SpeculativeTypes.push_back(SrcTy);
208 for (unsigned I = 0, E = SrcTy->getNumContainedTypes(); I != E; ++I)
209 if (!areTypesIsomorphic(DstTy->getContainedType(I),
210 SrcTy->getContainedType(I)))
213 // If everything seems to have lined up, then everything is great.
217 void TypeMapTy::linkDefinedTypeBodies() {
218 SmallVector<Type*, 16> Elements;
219 for (StructType *SrcSTy : SrcDefinitionsToResolve) {
220 StructType *DstSTy = cast<StructType>(MappedTypes[SrcSTy]);
221 assert(DstSTy->isOpaque());
223 // Map the body of the source type over to a new body for the dest type.
224 Elements.resize(SrcSTy->getNumElements());
225 for (unsigned I = 0, E = Elements.size(); I != E; ++I)
226 Elements[I] = get(SrcSTy->getElementType(I));
228 DstSTy->setBody(Elements, SrcSTy->isPacked());
229 DstStructTypesSet.switchToNonOpaque(DstSTy);
231 SrcDefinitionsToResolve.clear();
232 DstResolvedOpaqueTypes.clear();
235 void TypeMapTy::finishType(StructType *DTy, StructType *STy,
236 ArrayRef<Type *> ETypes) {
237 DTy->setBody(ETypes, STy->isPacked());
240 if (STy->hasName()) {
241 SmallString<16> TmpName = STy->getName();
243 DTy->setName(TmpName);
246 DstStructTypesSet.addNonOpaque(DTy);
249 Type *TypeMapTy::get(Type *Ty) {
250 SmallPtrSet<StructType *, 8> Visited;
251 return get(Ty, Visited);
254 Type *TypeMapTy::get(Type *Ty, SmallPtrSet<StructType *, 8> &Visited) {
255 // If we already have an entry for this type, return it.
256 Type **Entry = &MappedTypes[Ty];
260 // These are types that LLVM itself will unique.
261 bool IsUniqued = !isa<StructType>(Ty) || cast<StructType>(Ty)->isLiteral();
265 for (auto &Pair : MappedTypes) {
266 assert(!(Pair.first != Ty && Pair.second == Ty) &&
267 "mapping to a source type");
272 if (!IsUniqued && !Visited.insert(cast<StructType>(Ty)).second) {
273 StructType *DTy = StructType::create(Ty->getContext());
277 // If this is not a recursive type, then just map all of the elements and
278 // then rebuild the type from inside out.
279 SmallVector<Type *, 4> ElementTypes;
281 // If there are no element types to map, then the type is itself. This is
282 // true for the anonymous {} struct, things like 'float', integers, etc.
283 if (Ty->getNumContainedTypes() == 0 && IsUniqued)
286 // Remap all of the elements, keeping track of whether any of them change.
287 bool AnyChange = false;
288 ElementTypes.resize(Ty->getNumContainedTypes());
289 for (unsigned I = 0, E = Ty->getNumContainedTypes(); I != E; ++I) {
290 ElementTypes[I] = get(Ty->getContainedType(I), Visited);
291 AnyChange |= ElementTypes[I] != Ty->getContainedType(I);
294 // If we found our type while recursively processing stuff, just use it.
295 Entry = &MappedTypes[Ty];
297 if (auto *DTy = dyn_cast<StructType>(*Entry)) {
298 if (DTy->isOpaque()) {
299 auto *STy = cast<StructType>(Ty);
300 finishType(DTy, STy, ElementTypes);
306 // If all of the element types mapped directly over and the type is not
307 // a nomed struct, then the type is usable as-is.
308 if (!AnyChange && IsUniqued)
311 // Otherwise, rebuild a modified type.
312 switch (Ty->getTypeID()) {
314 llvm_unreachable("unknown derived type to remap");
315 case Type::ArrayTyID:
316 return *Entry = ArrayType::get(ElementTypes[0],
317 cast<ArrayType>(Ty)->getNumElements());
318 case Type::VectorTyID:
319 return *Entry = VectorType::get(ElementTypes[0],
320 cast<VectorType>(Ty)->getNumElements());
321 case Type::PointerTyID:
322 return *Entry = PointerType::get(ElementTypes[0],
323 cast<PointerType>(Ty)->getAddressSpace());
324 case Type::FunctionTyID:
325 return *Entry = FunctionType::get(ElementTypes[0],
326 makeArrayRef(ElementTypes).slice(1),
327 cast<FunctionType>(Ty)->isVarArg());
328 case Type::StructTyID: {
329 auto *STy = cast<StructType>(Ty);
330 bool IsPacked = STy->isPacked();
332 return *Entry = StructType::get(Ty->getContext(), ElementTypes, IsPacked);
334 // If the type is opaque, we can just use it directly.
335 if (STy->isOpaque()) {
336 DstStructTypesSet.addOpaque(STy);
340 if (StructType *OldT =
341 DstStructTypesSet.findNonOpaque(ElementTypes, IsPacked)) {
343 return *Entry = OldT;
347 DstStructTypesSet.addNonOpaque(STy);
351 StructType *DTy = StructType::create(Ty->getContext());
352 finishType(DTy, STy, ElementTypes);
358 //===----------------------------------------------------------------------===//
359 // ModuleLinker implementation.
360 //===----------------------------------------------------------------------===//
365 /// Creates prototypes for functions that are lazily linked on the fly. This
366 /// speeds up linking for modules with many/ lazily linked functions of which
368 class ValueMaterializerTy final : public ValueMaterializer {
369 ModuleLinker *ModLinker;
372 ValueMaterializerTy(ModuleLinker *ModLinker) : ModLinker(ModLinker) {}
374 Value *materializeDeclFor(Value *V) override;
375 void materializeInitFor(GlobalValue *New, GlobalValue *Old) override;
378 class LinkDiagnosticInfo : public DiagnosticInfo {
382 LinkDiagnosticInfo(DiagnosticSeverity Severity, const Twine &Msg);
383 void print(DiagnosticPrinter &DP) const override;
385 LinkDiagnosticInfo::LinkDiagnosticInfo(DiagnosticSeverity Severity,
387 : DiagnosticInfo(DK_Linker, Severity), Msg(Msg) {}
388 void LinkDiagnosticInfo::print(DiagnosticPrinter &DP) const { DP << Msg; }
390 /// This is an implementation class for the LinkModules function, which is the
391 /// entrypoint for this file.
396 ValueMaterializerTy ValMaterializer;
398 /// Mapping of values from what they used to be in Src, to what they are now
399 /// in DstM. ValueToValueMapTy is a ValueMap, which involves some overhead
400 /// due to the use of Value handles which the Linker doesn't actually need,
401 /// but this allows us to reuse the ValueMapper code.
402 ValueToValueMapTy ValueMap;
404 struct AppendingVarInfo {
405 GlobalVariable *NewGV; // New aggregate global in dest module.
406 const Constant *DstInit; // Old initializer from dest module.
407 const Constant *SrcInit; // Old initializer from src module.
410 std::vector<AppendingVarInfo> AppendingVars;
412 // Set of items not to link in from source.
413 SmallPtrSet<const Value *, 16> DoNotLinkFromSource;
415 DiagnosticHandlerFunction DiagnosticHandler;
417 /// For symbol clashes, prefer those from Src.
420 /// Function index passed into ModuleLinker for using in function
421 /// importing/exporting handling.
422 const FunctionInfoIndex *ImportIndex;
424 /// Function to import from source module, all other functions are
425 /// imported as declarations instead of definitions.
426 Function *ImportFunction;
428 /// Set to true if the given FunctionInfoIndex contains any functions
429 /// from this source module, in which case we must conservatively assume
430 /// that any of its functions may be imported into another module
431 /// as part of a different backend compilation process.
432 bool HasExportedFunctions;
434 /// Set to true when all global value body linking is complete (including
435 /// lazy linking). Used to prevent metadata linking from creating new
437 bool DoneLinkingBodies;
440 ModuleLinker(Module *dstM, Linker::IdentifiedStructTypeSet &Set, Module *srcM,
441 DiagnosticHandlerFunction DiagnosticHandler, unsigned Flags,
442 const FunctionInfoIndex *Index = nullptr,
443 Function *FuncToImport = nullptr)
444 : DstM(dstM), SrcM(srcM), TypeMap(Set), ValMaterializer(this),
445 DiagnosticHandler(DiagnosticHandler), Flags(Flags), ImportIndex(Index),
446 ImportFunction(FuncToImport), HasExportedFunctions(false),
447 DoneLinkingBodies(false) {
448 assert((ImportIndex || !ImportFunction) &&
449 "Expect a FunctionInfoIndex when importing");
450 // If we have a FunctionInfoIndex but no function to import,
451 // then this is the primary module being compiled in a ThinLTO
452 // backend compilation, and we need to see if it has functions that
453 // may be exported to another backend compilation.
454 if (ImportIndex && !ImportFunction)
455 HasExportedFunctions = ImportIndex->hasExportedFunctions(SrcM);
459 Value *materializeDeclFor(Value *V);
460 void materializeInitFor(GlobalValue *New, GlobalValue *Old);
463 bool shouldOverrideFromSrc() { return Flags & Linker::OverrideFromSrc; }
464 bool shouldLinkOnlyNeeded() { return Flags & Linker::LinkOnlyNeeded; }
465 bool shouldInternalizeLinkedSymbols() {
466 return Flags & Linker::InternalizeLinkedSymbols;
469 /// Handles cloning of a global values from the source module into
470 /// the destination module, including setting the attributes and visibility.
471 GlobalValue *copyGlobalValueProto(TypeMapTy &TypeMap, const GlobalValue *SGV,
472 const GlobalValue *DGV = nullptr);
474 /// Check if we should promote the given local value to global scope.
475 bool doPromoteLocalToGlobal(const GlobalValue *SGV);
477 /// Check if all global value body linking is complete.
478 bool doneLinkingBodies() { return DoneLinkingBodies; }
480 bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
481 const GlobalValue &Src);
483 /// Helper method for setting a message and returning an error code.
484 bool emitError(const Twine &Message) {
485 DiagnosticHandler(LinkDiagnosticInfo(DS_Error, Message));
489 void emitWarning(const Twine &Message) {
490 DiagnosticHandler(LinkDiagnosticInfo(DS_Warning, Message));
493 bool getComdatLeader(Module *M, StringRef ComdatName,
494 const GlobalVariable *&GVar);
495 bool computeResultingSelectionKind(StringRef ComdatName,
496 Comdat::SelectionKind Src,
497 Comdat::SelectionKind Dst,
498 Comdat::SelectionKind &Result,
500 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
502 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
504 // Keep track of the global value members of each comdat in source.
505 DenseMap<const Comdat *, std::vector<GlobalValue *>> ComdatMembers;
507 /// Given a global in the source module, return the global in the
508 /// destination module that is being linked to, if any.
509 GlobalValue *getLinkedToGlobal(const GlobalValue *SrcGV) {
510 // If the source has no name it can't link. If it has local linkage,
511 // there is no name match-up going on.
512 if (!SrcGV->hasName() || GlobalValue::isLocalLinkage(getLinkage(SrcGV)))
515 // Otherwise see if we have a match in the destination module's symtab.
516 GlobalValue *DGV = DstM->getNamedValue(getName(SrcGV));
520 // If we found a global with the same name in the dest module, but it has
521 // internal linkage, we are really not doing any linkage here.
522 if (DGV->hasLocalLinkage())
525 // Otherwise, we do in fact link to the destination global.
529 void computeTypeMapping();
531 void upgradeMismatchedGlobalArray(StringRef Name);
532 void upgradeMismatchedGlobals();
534 bool linkAppendingVarProto(GlobalVariable *DstGV,
535 const GlobalVariable *SrcGV);
537 bool linkGlobalValueProto(GlobalValue *GV);
538 bool linkModuleFlagsMetadata();
540 void linkAppendingVarInit(AppendingVarInfo &AVI);
542 void linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src);
543 bool linkFunctionBody(Function &Dst, Function &Src);
544 void linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src);
545 bool linkGlobalValueBody(GlobalValue &Src);
547 /// Functions that take care of cloning a specific global value type
548 /// into the destination module.
549 GlobalVariable *copyGlobalVariableProto(TypeMapTy &TypeMap,
550 const GlobalVariable *SGVar);
551 Function *copyFunctionProto(TypeMapTy &TypeMap, const Function *SF);
552 GlobalValue *copyGlobalAliasProto(TypeMapTy &TypeMap, const GlobalAlias *SGA);
554 /// Helper methods to check if we are importing from or potentially
555 /// exporting from the current source module.
556 bool isPerformingImport() { return ImportFunction != nullptr; }
557 bool isModuleExporting() { return HasExportedFunctions; }
559 /// If we are importing from the source module, checks if we should
560 /// import SGV as a definition, otherwise import as a declaration.
561 bool doImportAsDefinition(const GlobalValue *SGV);
563 /// Get the name for SGV that should be used in the linked destination
564 /// module. Specifically, this handles the case where we need to rename
565 /// a local that is being promoted to global scope.
566 std::string getName(const GlobalValue *SGV);
568 /// Get the new linkage for SGV that should be used in the linked destination
569 /// module. Specifically, for ThinLTO importing or exporting it may need
571 GlobalValue::LinkageTypes getLinkage(const GlobalValue *SGV);
573 /// Copies the necessary global value attributes and name from the source
574 /// to the newly cloned global value.
575 void copyGVAttributes(GlobalValue *NewGV, const GlobalValue *SrcGV);
577 /// Updates the visibility for the new global cloned from the source
578 /// and, if applicable, linked with an existing destination global.
579 /// Handles visibility change required for promoted locals.
580 void setVisibility(GlobalValue *NewGV, const GlobalValue *SGV,
581 const GlobalValue *DGV = nullptr);
583 void linkNamedMDNodes();
587 /// The LLVM SymbolTable class autorenames globals that conflict in the symbol
588 /// table. This is good for all clients except for us. Go through the trouble
589 /// to force this back.
590 static void forceRenaming(GlobalValue *GV, StringRef Name) {
591 // If the global doesn't force its name or if it already has the right name,
592 // there is nothing for us to do.
593 // Note that any required local to global promotion should already be done,
594 // so promoted locals will not skip this handling as their linkage is no
596 if (GV->hasLocalLinkage() || GV->getName() == Name)
599 Module *M = GV->getParent();
601 // If there is a conflict, rename the conflict.
602 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
603 GV->takeName(ConflictGV);
604 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
605 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
607 GV->setName(Name); // Force the name back
611 /// copy additional attributes (those not needed to construct a GlobalValue)
612 /// from the SrcGV to the DestGV.
613 void ModuleLinker::copyGVAttributes(GlobalValue *NewGV,
614 const GlobalValue *SrcGV) {
615 auto *GA = dyn_cast<GlobalAlias>(SrcGV);
616 // Check for the special case of converting an alias (definition) to a
617 // non-alias (declaration). This can happen when we are importing and
618 // encounter a weak_any alias (weak_any defs may not be imported, see
619 // comments in ModuleLinker::getLinkage) or an alias whose base object is
620 // being imported as a declaration. In that case copy the attributes from the
622 if (GA && !dyn_cast<GlobalAlias>(NewGV)) {
623 assert(isPerformingImport() && !doImportAsDefinition(GA));
624 NewGV->copyAttributesFrom(GA->getBaseObject());
626 NewGV->copyAttributesFrom(SrcGV);
627 forceRenaming(NewGV, getName(SrcGV));
630 bool ModuleLinker::doImportAsDefinition(const GlobalValue *SGV) {
631 if (!isPerformingImport())
633 auto *GA = dyn_cast<GlobalAlias>(SGV);
635 if (GA->hasWeakAnyLinkage())
637 const GlobalObject *GO = GA->getBaseObject();
638 if (!GO->hasLinkOnceODRLinkage())
640 return doImportAsDefinition(GO);
642 // Always import GlobalVariable definitions, except for the special
643 // case of WeakAny which are imported as ExternalWeak declarations
644 // (see comments in ModuleLinker::getLinkage). The linkage changes
645 // described in ModuleLinker::getLinkage ensure the correct behavior (e.g.
646 // global variables with external linkage are transformed to
647 // available_externally definitions, which are ultimately turned into
648 // declarations after the EliminateAvailableExternally pass).
649 if (isa<GlobalVariable>(SGV) && !SGV->isDeclaration() &&
650 !SGV->hasWeakAnyLinkage())
652 // Only import the function requested for importing.
653 auto *SF = dyn_cast<Function>(SGV);
654 if (SF && SF == ImportFunction)
660 bool ModuleLinker::doPromoteLocalToGlobal(const GlobalValue *SGV) {
661 assert(SGV->hasLocalLinkage());
662 // Both the imported references and the original local variable must
664 if (!isPerformingImport() && !isModuleExporting())
667 // Local const variables never need to be promoted unless they are address
668 // taken. The imported uses can simply use the clone created in this module.
669 // For now we are conservative in determining which variables are not
670 // address taken by checking the unnamed addr flag. To be more aggressive,
671 // the address taken information must be checked earlier during parsing
672 // of the module and recorded in the function index for use when importing
674 auto *GVar = dyn_cast<GlobalVariable>(SGV);
675 if (GVar && GVar->isConstant() && GVar->hasUnnamedAddr())
678 // Eventually we only need to promote functions in the exporting module that
679 // are referenced by a potentially exported function (i.e. one that is in the
684 std::string ModuleLinker::getName(const GlobalValue *SGV) {
685 // For locals that must be promoted to global scope, ensure that
686 // the promoted name uniquely identifies the copy in the original module,
687 // using the ID assigned during combined index creation. When importing,
688 // we rename all locals (not just those that are promoted) in order to
689 // avoid naming conflicts between locals imported from different modules.
690 if (SGV->hasLocalLinkage() &&
691 (doPromoteLocalToGlobal(SGV) || isPerformingImport()))
692 return FunctionInfoIndex::getGlobalNameForLocal(
694 ImportIndex->getModuleId(SGV->getParent()->getModuleIdentifier()));
695 return SGV->getName();
698 GlobalValue::LinkageTypes ModuleLinker::getLinkage(const GlobalValue *SGV) {
699 // Any local variable that is referenced by an exported function needs
700 // to be promoted to global scope. Since we don't currently know which
701 // functions reference which local variables/functions, we must treat
702 // all as potentially exported if this module is exporting anything.
703 if (isModuleExporting()) {
704 if (SGV->hasLocalLinkage() && doPromoteLocalToGlobal(SGV))
705 return GlobalValue::ExternalLinkage;
706 return SGV->getLinkage();
709 // Otherwise, if we aren't importing, no linkage change is needed.
710 if (!isPerformingImport())
711 return SGV->getLinkage();
713 switch (SGV->getLinkage()) {
714 case GlobalValue::ExternalLinkage:
715 // External defnitions are converted to available_externally
716 // definitions upon import, so that they are available for inlining
717 // and/or optimization, but are turned into declarations later
718 // during the EliminateAvailableExternally pass.
719 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
720 return GlobalValue::AvailableExternallyLinkage;
721 // An imported external declaration stays external.
722 return SGV->getLinkage();
724 case GlobalValue::AvailableExternallyLinkage:
725 // An imported available_externally definition converts
726 // to external if imported as a declaration.
727 if (!doImportAsDefinition(SGV))
728 return GlobalValue::ExternalLinkage;
729 // An imported available_externally declaration stays that way.
730 return SGV->getLinkage();
732 case GlobalValue::LinkOnceAnyLinkage:
733 case GlobalValue::LinkOnceODRLinkage:
734 // These both stay the same when importing the definition.
735 // The ThinLTO pass will eventually force-import their definitions.
736 return SGV->getLinkage();
738 case GlobalValue::WeakAnyLinkage:
739 // Can't import weak_any definitions correctly, or we might change the
740 // program semantics, since the linker will pick the first weak_any
741 // definition and importing would change the order they are seen by the
742 // linker. The module linking caller needs to enforce this.
743 assert(!doImportAsDefinition(SGV));
744 // If imported as a declaration, it becomes external_weak.
745 return GlobalValue::ExternalWeakLinkage;
747 case GlobalValue::WeakODRLinkage:
748 // For weak_odr linkage, there is a guarantee that all copies will be
749 // equivalent, so the issue described above for weak_any does not exist,
750 // and the definition can be imported. It can be treated similarly
751 // to an imported externally visible global value.
752 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
753 return GlobalValue::AvailableExternallyLinkage;
755 return GlobalValue::ExternalLinkage;
757 case GlobalValue::AppendingLinkage:
758 // It would be incorrect to import an appending linkage variable,
759 // since it would cause global constructors/destructors to be
760 // executed multiple times. This should have already been handled
761 // by linkGlobalValueProto.
762 llvm_unreachable("Cannot import appending linkage variable");
764 case GlobalValue::InternalLinkage:
765 case GlobalValue::PrivateLinkage:
766 // If we are promoting the local to global scope, it is handled
767 // similarly to a normal externally visible global.
768 if (doPromoteLocalToGlobal(SGV)) {
769 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
770 return GlobalValue::AvailableExternallyLinkage;
772 return GlobalValue::ExternalLinkage;
774 // A non-promoted imported local definition stays local.
775 // The ThinLTO pass will eventually force-import their definitions.
776 return SGV->getLinkage();
778 case GlobalValue::ExternalWeakLinkage:
779 // External weak doesn't apply to definitions, must be a declaration.
780 assert(!doImportAsDefinition(SGV));
781 // Linkage stays external_weak.
782 return SGV->getLinkage();
784 case GlobalValue::CommonLinkage:
785 // Linkage stays common on definitions.
786 // The ThinLTO pass will eventually force-import their definitions.
787 return SGV->getLinkage();
790 llvm_unreachable("unknown linkage type");
793 /// Loop through the global variables in the src module and merge them into the
796 ModuleLinker::copyGlobalVariableProto(TypeMapTy &TypeMap,
797 const GlobalVariable *SGVar) {
798 // No linking to be performed or linking from the source: simply create an
799 // identical version of the symbol over in the dest module... the
800 // initializer will be filled in later by LinkGlobalInits.
801 GlobalVariable *NewDGV = new GlobalVariable(
802 *DstM, TypeMap.get(SGVar->getType()->getElementType()),
803 SGVar->isConstant(), getLinkage(SGVar), /*init*/ nullptr, getName(SGVar),
804 /*insertbefore*/ nullptr, SGVar->getThreadLocalMode(),
805 SGVar->getType()->getAddressSpace());
810 /// Link the function in the source module into the destination module if
811 /// needed, setting up mapping information.
812 Function *ModuleLinker::copyFunctionProto(TypeMapTy &TypeMap,
813 const Function *SF) {
814 // If there is no linkage to be performed or we are linking from the source,
816 return Function::Create(TypeMap.get(SF->getFunctionType()), getLinkage(SF),
820 /// Set up prototypes for any aliases that come over from the source module.
821 GlobalValue *ModuleLinker::copyGlobalAliasProto(TypeMapTy &TypeMap,
822 const GlobalAlias *SGA) {
823 // If we are importing and encounter a weak_any alias, or an alias to
824 // an object being imported as a declaration, we must import the alias
825 // as a declaration as well, which involves converting it to a non-alias.
826 // See comments in ModuleLinker::getLinkage for why we cannot import
827 // weak_any defintions.
828 if (isPerformingImport() && !doImportAsDefinition(SGA)) {
829 // Need to convert to declaration. All aliases must be definitions.
830 const GlobalValue *GVal = SGA->getBaseObject();
832 if (auto *GVar = dyn_cast<GlobalVariable>(GVal))
833 NewGV = copyGlobalVariableProto(TypeMap, GVar);
835 auto *F = dyn_cast<Function>(GVal);
837 NewGV = copyFunctionProto(TypeMap, F);
839 // Set the linkage to External or ExternalWeak (see comments in
840 // ModuleLinker::getLinkage for why WeakAny is converted to ExternalWeak).
841 if (SGA->hasWeakAnyLinkage())
842 NewGV->setLinkage(GlobalValue::ExternalWeakLinkage);
844 NewGV->setLinkage(GlobalValue::ExternalLinkage);
847 // If there is no linkage to be performed or we're linking from the source,
849 auto *Ty = TypeMap.get(SGA->getValueType());
850 return GlobalAlias::create(Ty, SGA->getType()->getPointerAddressSpace(),
851 getLinkage(SGA), getName(SGA), DstM);
854 static GlobalValue::VisibilityTypes
855 getMinVisibility(GlobalValue::VisibilityTypes A,
856 GlobalValue::VisibilityTypes B) {
857 if (A == GlobalValue::HiddenVisibility || B == GlobalValue::HiddenVisibility)
858 return GlobalValue::HiddenVisibility;
859 if (A == GlobalValue::ProtectedVisibility ||
860 B == GlobalValue::ProtectedVisibility)
861 return GlobalValue::ProtectedVisibility;
862 return GlobalValue::DefaultVisibility;
865 void ModuleLinker::setVisibility(GlobalValue *NewGV, const GlobalValue *SGV,
866 const GlobalValue *DGV) {
867 GlobalValue::VisibilityTypes Visibility = SGV->getVisibility();
869 Visibility = getMinVisibility(DGV->getVisibility(), Visibility);
870 // For promoted locals, mark them hidden so that they can later be
871 // stripped from the symbol table to reduce bloat.
872 if (SGV->hasLocalLinkage() && doPromoteLocalToGlobal(SGV))
873 Visibility = GlobalValue::HiddenVisibility;
874 NewGV->setVisibility(Visibility);
877 GlobalValue *ModuleLinker::copyGlobalValueProto(TypeMapTy &TypeMap,
878 const GlobalValue *SGV,
879 const GlobalValue *DGV) {
881 if (auto *SGVar = dyn_cast<GlobalVariable>(SGV))
882 NewGV = copyGlobalVariableProto(TypeMap, SGVar);
883 else if (auto *SF = dyn_cast<Function>(SGV))
884 NewGV = copyFunctionProto(TypeMap, SF);
886 NewGV = copyGlobalAliasProto(TypeMap, cast<GlobalAlias>(SGV));
887 copyGVAttributes(NewGV, SGV);
888 setVisibility(NewGV, SGV, DGV);
892 Value *ValueMaterializerTy::materializeDeclFor(Value *V) {
893 return ModLinker->materializeDeclFor(V);
896 Value *ModuleLinker::materializeDeclFor(Value *V) {
897 auto *SGV = dyn_cast<GlobalValue>(V);
901 // If we are done linking global value bodies (i.e. we are performing
902 // metadata linking), don't link in the global value due to this
903 // reference, simply map it to null.
904 if (doneLinkingBodies())
907 GlobalValue *DGV = copyGlobalValueProto(TypeMap, SGV);
909 if (Comdat *SC = SGV->getComdat()) {
910 if (auto *DGO = dyn_cast<GlobalObject>(DGV)) {
911 Comdat *DC = DstM->getOrInsertComdat(SC->getName());
919 void ValueMaterializerTy::materializeInitFor(GlobalValue *New,
921 return ModLinker->materializeInitFor(New, Old);
924 void ModuleLinker::materializeInitFor(GlobalValue *New, GlobalValue *Old) {
925 if (isPerformingImport() && !doImportAsDefinition(Old))
928 // Skip declarations that ValueMaterializer may have created in
929 // case we link in only some of SrcM.
930 if (shouldLinkOnlyNeeded() && Old->isDeclaration())
933 assert(!Old->isDeclaration() && "users should not pass down decls");
934 linkGlobalValueBody(*Old);
937 bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName,
938 const GlobalVariable *&GVar) {
939 const GlobalValue *GVal = M->getNamedValue(ComdatName);
940 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
941 GVal = GA->getBaseObject();
943 // We cannot resolve the size of the aliasee yet.
944 return emitError("Linking COMDATs named '" + ComdatName +
945 "': COMDAT key involves incomputable alias size.");
948 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
951 "Linking COMDATs named '" + ComdatName +
952 "': GlobalVariable required for data dependent selection!");
957 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
958 Comdat::SelectionKind Src,
959 Comdat::SelectionKind Dst,
960 Comdat::SelectionKind &Result,
962 // The ability to mix Comdat::SelectionKind::Any with
963 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
964 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
965 Dst == Comdat::SelectionKind::Largest;
966 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
967 Src == Comdat::SelectionKind::Largest;
968 if (DstAnyOrLargest && SrcAnyOrLargest) {
969 if (Dst == Comdat::SelectionKind::Largest ||
970 Src == Comdat::SelectionKind::Largest)
971 Result = Comdat::SelectionKind::Largest;
973 Result = Comdat::SelectionKind::Any;
974 } else if (Src == Dst) {
977 return emitError("Linking COMDATs named '" + ComdatName +
978 "': invalid selection kinds!");
982 case Comdat::SelectionKind::Any:
986 case Comdat::SelectionKind::NoDuplicates:
987 return emitError("Linking COMDATs named '" + ComdatName +
988 "': noduplicates has been violated!");
989 case Comdat::SelectionKind::ExactMatch:
990 case Comdat::SelectionKind::Largest:
991 case Comdat::SelectionKind::SameSize: {
992 const GlobalVariable *DstGV;
993 const GlobalVariable *SrcGV;
994 if (getComdatLeader(DstM, ComdatName, DstGV) ||
995 getComdatLeader(SrcM, ComdatName, SrcGV))
998 const DataLayout &DstDL = DstM->getDataLayout();
999 const DataLayout &SrcDL = SrcM->getDataLayout();
1001 DstDL.getTypeAllocSize(DstGV->getType()->getPointerElementType());
1003 SrcDL.getTypeAllocSize(SrcGV->getType()->getPointerElementType());
1004 if (Result == Comdat::SelectionKind::ExactMatch) {
1005 if (SrcGV->getInitializer() != DstGV->getInitializer())
1006 return emitError("Linking COMDATs named '" + ComdatName +
1007 "': ExactMatch violated!");
1008 LinkFromSrc = false;
1009 } else if (Result == Comdat::SelectionKind::Largest) {
1010 LinkFromSrc = SrcSize > DstSize;
1011 } else if (Result == Comdat::SelectionKind::SameSize) {
1012 if (SrcSize != DstSize)
1013 return emitError("Linking COMDATs named '" + ComdatName +
1014 "': SameSize violated!");
1015 LinkFromSrc = false;
1017 llvm_unreachable("unknown selection kind");
1026 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
1027 Comdat::SelectionKind &Result,
1028 bool &LinkFromSrc) {
1029 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
1030 StringRef ComdatName = SrcC->getName();
1031 Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable();
1032 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
1034 if (DstCI == ComdatSymTab.end()) {
1035 // Use the comdat if it is only available in one of the modules.
1041 const Comdat *DstC = &DstCI->second;
1042 Comdat::SelectionKind DSK = DstC->getSelectionKind();
1043 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
1047 bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
1048 const GlobalValue &Dest,
1049 const GlobalValue &Src) {
1050 // Should we unconditionally use the Src?
1051 if (shouldOverrideFromSrc()) {
1056 // We always have to add Src if it has appending linkage.
1057 if (Src.hasAppendingLinkage()) {
1058 // Caller should have already determined that we can't link from source
1059 // when importing (see comments in linkGlobalValueProto).
1060 assert(!isPerformingImport());
1065 bool SrcIsDeclaration = Src.isDeclarationForLinker();
1066 bool DestIsDeclaration = Dest.isDeclarationForLinker();
1068 if (isPerformingImport()) {
1069 if (isa<Function>(&Src)) {
1070 // For functions, LinkFromSrc iff this is the function requested
1071 // for importing. For variables, decide below normally.
1072 LinkFromSrc = (&Src == ImportFunction);
1076 // Check if this is an alias with an already existing definition
1077 // in Dest, which must have come from a prior importing pass from
1078 // the same Src module. Unlike imported function and variable
1079 // definitions, which are imported as available_externally and are
1080 // not definitions for the linker, that is not a valid linkage for
1081 // imported aliases which must be definitions. Simply use the existing
1083 if (isa<GlobalAlias>(&Src) && !DestIsDeclaration) {
1084 assert(isa<GlobalAlias>(&Dest));
1085 LinkFromSrc = false;
1090 if (SrcIsDeclaration) {
1091 // If Src is external or if both Src & Dest are external.. Just link the
1092 // external globals, we aren't adding anything.
1093 if (Src.hasDLLImportStorageClass()) {
1094 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
1095 LinkFromSrc = DestIsDeclaration;
1098 // If the Dest is weak, use the source linkage.
1099 LinkFromSrc = Dest.hasExternalWeakLinkage();
1103 if (DestIsDeclaration) {
1104 // If Dest is external but Src is not:
1109 if (Src.hasCommonLinkage()) {
1110 if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
1115 if (!Dest.hasCommonLinkage()) {
1116 LinkFromSrc = false;
1120 const DataLayout &DL = Dest.getParent()->getDataLayout();
1121 uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
1122 uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
1123 LinkFromSrc = SrcSize > DestSize;
1127 if (Src.isWeakForLinker()) {
1128 assert(!Dest.hasExternalWeakLinkage());
1129 assert(!Dest.hasAvailableExternallyLinkage());
1131 if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
1136 LinkFromSrc = false;
1140 if (Dest.isWeakForLinker()) {
1141 assert(Src.hasExternalLinkage());
1146 assert(!Src.hasExternalWeakLinkage());
1147 assert(!Dest.hasExternalWeakLinkage());
1148 assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
1149 "Unexpected linkage type!");
1150 return emitError("Linking globals named '" + Src.getName() +
1151 "': symbol multiply defined!");
1154 /// Loop over all of the linked values to compute type mappings. For example,
1155 /// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct
1156 /// types 'Foo' but one got renamed when the module was loaded into the same
1158 void ModuleLinker::computeTypeMapping() {
1159 for (GlobalValue &SGV : SrcM->globals()) {
1160 GlobalValue *DGV = getLinkedToGlobal(&SGV);
1164 if (!DGV->hasAppendingLinkage() || !SGV.hasAppendingLinkage()) {
1165 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1169 // Unify the element type of appending arrays.
1170 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
1171 ArrayType *SAT = cast<ArrayType>(SGV.getType()->getElementType());
1172 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
1175 for (GlobalValue &SGV : *SrcM) {
1176 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
1177 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1180 for (GlobalValue &SGV : SrcM->aliases()) {
1181 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
1182 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1185 // Incorporate types by name, scanning all the types in the source module.
1186 // At this point, the destination module may have a type "%foo = { i32 }" for
1187 // example. When the source module got loaded into the same LLVMContext, if
1188 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
1189 std::vector<StructType *> Types = SrcM->getIdentifiedStructTypes();
1190 for (StructType *ST : Types) {
1194 // Check to see if there is a dot in the name followed by a digit.
1195 size_t DotPos = ST->getName().rfind('.');
1196 if (DotPos == 0 || DotPos == StringRef::npos ||
1197 ST->getName().back() == '.' ||
1198 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos + 1])))
1201 // Check to see if the destination module has a struct with the prefix name.
1202 StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos));
1206 // Don't use it if this actually came from the source module. They're in
1207 // the same LLVMContext after all. Also don't use it unless the type is
1208 // actually used in the destination module. This can happen in situations
1211 // Module A Module B
1212 // -------- --------
1213 // %Z = type { %A } %B = type { %C.1 }
1214 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
1215 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
1216 // %C = type { i8* } %B.3 = type { %C.1 }
1218 // When we link Module B with Module A, the '%B' in Module B is
1219 // used. However, that would then use '%C.1'. But when we process '%C.1',
1220 // we prefer to take the '%C' version. So we are then left with both
1221 // '%C.1' and '%C' being used for the same types. This leads to some
1222 // variables using one type and some using the other.
1223 if (TypeMap.DstStructTypesSet.hasType(DST))
1224 TypeMap.addTypeMapping(DST, ST);
1227 // Now that we have discovered all of the type equivalences, get a body for
1228 // any 'opaque' types in the dest module that are now resolved.
1229 TypeMap.linkDefinedTypeBodies();
1232 static void upgradeGlobalArray(GlobalVariable *GV) {
1233 ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
1234 StructType *OldTy = cast<StructType>(ATy->getElementType());
1235 assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
1237 // Get the upgraded 3 element type.
1238 PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
1239 Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
1241 StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
1243 // Build new constants with a null third field filled in.
1244 Constant *OldInitC = GV->getInitializer();
1245 ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
1246 if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
1247 // Invalid initializer; give up.
1249 std::vector<Constant *> Initializers;
1250 if (OldInit && OldInit->getNumOperands()) {
1251 Value *Null = Constant::getNullValue(VoidPtrTy);
1252 for (Use &U : OldInit->operands()) {
1253 ConstantStruct *Init = cast<ConstantStruct>(U.get());
1254 Initializers.push_back(ConstantStruct::get(
1255 NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
1258 assert(Initializers.size() == ATy->getNumElements() &&
1259 "Failed to copy all array elements");
1261 // Replace the old GV with a new one.
1262 ATy = ArrayType::get(NewTy, Initializers.size());
1263 Constant *NewInit = ConstantArray::get(ATy, Initializers);
1264 GlobalVariable *NewGV = new GlobalVariable(
1265 *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
1266 GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
1267 GV->isExternallyInitialized());
1268 NewGV->copyAttributesFrom(GV);
1269 NewGV->takeName(GV);
1270 assert(GV->use_empty() && "program cannot use initializer list");
1271 GV->eraseFromParent();
1274 void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
1275 // Look for the global arrays.
1276 auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM->getNamedValue(Name));
1279 auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM->getNamedValue(Name));
1283 // Check if the types already match.
1284 auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
1286 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
1290 // Grab the element types. We can only upgrade an array of a two-field
1291 // struct. Only bother if the other one has three-fields.
1292 auto *DstEltTy = cast<StructType>(DstTy->getElementType());
1293 auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
1294 if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
1295 upgradeGlobalArray(DstGV);
1298 if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
1299 upgradeGlobalArray(SrcGV);
1301 // We can't upgrade any other differences.
1304 void ModuleLinker::upgradeMismatchedGlobals() {
1305 upgradeMismatchedGlobalArray("llvm.global_ctors");
1306 upgradeMismatchedGlobalArray("llvm.global_dtors");
1309 /// If there were any appending global variables, link them together now.
1310 /// Return true on error.
1311 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
1312 const GlobalVariable *SrcGV) {
1314 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
1315 Type *EltTy = SrcTy->getElementType();
1317 uint64_t NewSize = SrcTy->getNumElements();
1319 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
1320 NewSize += DstTy->getNumElements();
1322 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
1324 "Linking globals named '" + SrcGV->getName() +
1325 "': can only link appending global with another appending global!");
1327 // Check to see that they two arrays agree on type.
1328 if (EltTy != DstTy->getElementType())
1329 return emitError("Appending variables with different element types!");
1330 if (DstGV->isConstant() != SrcGV->isConstant())
1331 return emitError("Appending variables linked with different const'ness!");
1333 if (DstGV->getAlignment() != SrcGV->getAlignment())
1335 "Appending variables with different alignment need to be linked!");
1337 if (DstGV->getVisibility() != SrcGV->getVisibility())
1339 "Appending variables with different visibility need to be linked!");
1341 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
1343 "Appending variables with different unnamed_addr need to be linked!");
1345 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
1347 "Appending variables with different section name need to be linked!");
1350 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
1352 // Create the new global variable.
1353 GlobalVariable *NG = new GlobalVariable(
1354 *DstM, NewType, SrcGV->isConstant(), SrcGV->getLinkage(),
1355 /*init*/ nullptr, /*name*/ "", DstGV, SrcGV->getThreadLocalMode(),
1356 SrcGV->getType()->getAddressSpace());
1358 // Propagate alignment, visibility and section info.
1359 copyGVAttributes(NG, SrcGV);
1361 AppendingVarInfo AVI;
1363 AVI.DstInit = DstGV ? DstGV->getInitializer() : nullptr;
1364 AVI.SrcInit = SrcGV->getInitializer();
1365 AppendingVars.push_back(AVI);
1367 // Replace any uses of the two global variables with uses of the new
1369 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
1372 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
1373 DstGV->eraseFromParent();
1376 // Track the source variable so we don't try to link it.
1377 DoNotLinkFromSource.insert(SrcGV);
1382 bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) {
1383 GlobalValue *DGV = getLinkedToGlobal(SGV);
1385 // Handle the ultra special appending linkage case first.
1386 assert(!DGV || SGV->hasAppendingLinkage() == DGV->hasAppendingLinkage());
1387 if (SGV->hasAppendingLinkage() && isPerformingImport()) {
1388 // Don't want to append to global_ctors list, for example, when we
1389 // are importing for ThinLTO, otherwise the global ctors and dtors
1390 // get executed multiple times for local variables (the latter causing
1392 DoNotLinkFromSource.insert(SGV);
1395 if (SGV->hasAppendingLinkage())
1396 return linkAppendingVarProto(cast_or_null<GlobalVariable>(DGV),
1397 cast<GlobalVariable>(SGV));
1399 bool LinkFromSrc = true;
1400 Comdat *C = nullptr;
1401 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
1403 if (const Comdat *SC = SGV->getComdat()) {
1404 Comdat::SelectionKind SK;
1405 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1406 C = DstM->getOrInsertComdat(SC->getName());
1407 C->setSelectionKind(SK);
1408 ComdatMembers[SC].push_back(SGV);
1410 if (shouldLinkFromSource(LinkFromSrc, *DGV, *SGV))
1415 // Track the source global so that we don't attempt to copy it over when
1416 // processing global initializers.
1417 DoNotLinkFromSource.insert(SGV);
1420 // Make sure to remember this mapping.
1422 ConstantExpr::getBitCast(DGV, TypeMap.get(SGV->getType()));
1426 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1428 if (!LinkFromSrc && !DGV)
1434 // When linking from source we setVisibility from copyGlobalValueProto.
1435 setVisibility(NewGV, SGV, DGV);
1437 // If the GV is to be lazily linked, don't create it just yet.
1438 // The ValueMaterializerTy will deal with creating it if it's used.
1439 if (!DGV && !shouldOverrideFromSrc() && SGV != ImportFunction &&
1440 (SGV->hasLocalLinkage() || SGV->hasLinkOnceLinkage() ||
1441 SGV->hasAvailableExternallyLinkage())) {
1442 DoNotLinkFromSource.insert(SGV);
1446 // When we only want to link in unresolved dependencies, blacklist
1447 // the symbol unless unless DestM has a matching declaration (DGV).
1448 if (shouldLinkOnlyNeeded() && !(DGV && DGV->isDeclaration())) {
1449 DoNotLinkFromSource.insert(SGV);
1453 NewGV = copyGlobalValueProto(TypeMap, SGV, DGV);
1455 if (isPerformingImport() && !doImportAsDefinition(SGV))
1456 DoNotLinkFromSource.insert(SGV);
1459 NewGV->setUnnamedAddr(HasUnnamedAddr);
1461 if (auto *NewGO = dyn_cast<GlobalObject>(NewGV)) {
1463 NewGO->setComdat(C);
1465 if (DGV && DGV->hasCommonLinkage() && SGV->hasCommonLinkage())
1466 NewGO->setAlignment(std::max(DGV->getAlignment(), SGV->getAlignment()));
1469 if (auto *NewGVar = dyn_cast<GlobalVariable>(NewGV)) {
1470 auto *DGVar = dyn_cast_or_null<GlobalVariable>(DGV);
1471 auto *SGVar = dyn_cast<GlobalVariable>(SGV);
1472 if (DGVar && SGVar && DGVar->isDeclaration() && SGVar->isDeclaration() &&
1473 (!DGVar->isConstant() || !SGVar->isConstant()))
1474 NewGVar->setConstant(false);
1477 // Make sure to remember this mapping.
1480 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewGV, DGV->getType()));
1481 DGV->eraseFromParent();
1483 ValueMap[SGV] = NewGV;
1489 static void getArrayElements(const Constant *C,
1490 SmallVectorImpl<Constant *> &Dest) {
1491 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1493 for (unsigned i = 0; i != NumElements; ++i)
1494 Dest.push_back(C->getAggregateElement(i));
1497 void ModuleLinker::linkAppendingVarInit(AppendingVarInfo &AVI) {
1498 // Merge the initializer.
1499 SmallVector<Constant *, 16> DstElements;
1501 getArrayElements(AVI.DstInit, DstElements);
1503 SmallVector<Constant *, 16> SrcElements;
1504 getArrayElements(AVI.SrcInit, SrcElements);
1506 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
1508 StringRef Name = AVI.NewGV->getName();
1509 bool IsNewStructor =
1510 (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
1511 cast<StructType>(NewType->getElementType())->getNumElements() == 3;
1513 for (auto *V : SrcElements) {
1514 if (IsNewStructor) {
1515 Constant *Key = V->getAggregateElement(2);
1516 if (DoNotLinkFromSource.count(Key))
1519 DstElements.push_back(
1520 MapValue(V, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1522 if (DstElements.size() != NewType->getNumElements()) {
1523 NewType = ArrayType::get(NewType->getElementType(), DstElements.size());
1524 GlobalVariable *Old = AVI.NewGV;
1525 GlobalVariable *NG = new GlobalVariable(
1526 *DstM, NewType, Old->isConstant(), Old->getLinkage(), /*init*/ nullptr,
1527 /*name*/ "", Old, Old->getThreadLocalMode(),
1528 Old->getType()->getAddressSpace());
1529 copyGVAttributes(NG, Old);
1530 AVI.NewGV->replaceAllUsesWith(
1531 ConstantExpr::getBitCast(NG, AVI.NewGV->getType()));
1532 AVI.NewGV->eraseFromParent();
1536 AVI.NewGV->setInitializer(ConstantArray::get(NewType, DstElements));
1539 /// Update the initializers in the Dest module now that all globals that may be
1540 /// referenced are in Dest.
1541 void ModuleLinker::linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src) {
1542 // Figure out what the initializer looks like in the dest module.
1543 Dst.setInitializer(MapValue(Src.getInitializer(), ValueMap,
1544 RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1547 /// Copy the source function over into the dest function and fix up references
1548 /// to values. At this point we know that Dest is an external function, and
1549 /// that Src is not.
1550 bool ModuleLinker::linkFunctionBody(Function &Dst, Function &Src) {
1551 assert(Dst.isDeclaration() && !Src.isDeclaration());
1553 // Materialize if needed.
1554 if (std::error_code EC = Src.materialize())
1555 return emitError(EC.message());
1557 // Link in the prefix data.
1558 if (Src.hasPrefixData())
1559 Dst.setPrefixData(MapValue(Src.getPrefixData(), ValueMap,
1560 RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1562 // Link in the prologue data.
1563 if (Src.hasPrologueData())
1564 Dst.setPrologueData(MapValue(Src.getPrologueData(), ValueMap,
1565 RF_MoveDistinctMDs, &TypeMap,
1568 // Link in the personality function.
1569 if (Src.hasPersonalityFn())
1570 Dst.setPersonalityFn(MapValue(Src.getPersonalityFn(), ValueMap,
1571 RF_MoveDistinctMDs, &TypeMap,
1574 // Go through and convert function arguments over, remembering the mapping.
1575 Function::arg_iterator DI = Dst.arg_begin();
1576 for (Argument &Arg : Src.args()) {
1577 DI->setName(Arg.getName()); // Copy the name over.
1579 // Add a mapping to our mapping.
1580 ValueMap[&Arg] = &*DI;
1584 // Copy over the metadata attachments.
1585 SmallVector<std::pair<unsigned, MDNode *>, 8> MDs;
1586 Src.getAllMetadata(MDs);
1587 for (const auto &I : MDs)
1588 Dst.setMetadata(I.first, MapMetadata(I.second, ValueMap, RF_MoveDistinctMDs,
1589 &TypeMap, &ValMaterializer));
1591 // Splice the body of the source function into the dest function.
1592 Dst.getBasicBlockList().splice(Dst.end(), Src.getBasicBlockList());
1594 // At this point, all of the instructions and values of the function are now
1595 // copied over. The only problem is that they are still referencing values in
1596 // the Source function as operands. Loop through all of the operands of the
1597 // functions and patch them up to point to the local versions.
1598 for (BasicBlock &BB : Dst)
1599 for (Instruction &I : BB)
1600 RemapInstruction(&I, ValueMap,
1601 RF_IgnoreMissingEntries | RF_MoveDistinctMDs, &TypeMap,
1604 // There is no need to map the arguments anymore.
1605 for (Argument &Arg : Src.args())
1606 ValueMap.erase(&Arg);
1608 Src.dematerialize();
1612 void ModuleLinker::linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src) {
1613 Constant *Aliasee = Src.getAliasee();
1614 Constant *Val = MapValue(Aliasee, ValueMap, RF_MoveDistinctMDs, &TypeMap,
1616 Dst.setAliasee(Val);
1619 bool ModuleLinker::linkGlobalValueBody(GlobalValue &Src) {
1620 Value *Dst = ValueMap[&Src];
1622 if (const Comdat *SC = Src.getComdat()) {
1623 // To ensure that we don't generate an incomplete comdat group,
1624 // we must materialize and map in any other members that are not
1625 // yet materialized in Dst, which also ensures their definitions
1626 // are linked in. Otherwise, linkonce and other lazy linked GVs will
1627 // not be materialized if they aren't referenced.
1628 for (auto *SGV : ComdatMembers[SC]) {
1629 auto *DGV = cast_or_null<GlobalValue>(ValueMap[SGV]);
1630 if (DGV && !DGV->isDeclaration())
1632 MapValue(SGV, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer);
1635 if (shouldInternalizeLinkedSymbols())
1636 if (auto *DGV = dyn_cast<GlobalValue>(Dst))
1637 DGV->setLinkage(GlobalValue::InternalLinkage);
1638 if (auto *F = dyn_cast<Function>(&Src))
1639 return linkFunctionBody(cast<Function>(*Dst), *F);
1640 if (auto *GVar = dyn_cast<GlobalVariable>(&Src)) {
1641 linkGlobalInit(cast<GlobalVariable>(*Dst), *GVar);
1644 linkAliasBody(cast<GlobalAlias>(*Dst), cast<GlobalAlias>(Src));
1648 /// Insert all of the named MDNodes in Src into the Dest module.
1649 void ModuleLinker::linkNamedMDNodes() {
1650 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1651 for (const NamedMDNode &NMD : SrcM->named_metadata()) {
1652 // Don't link module flags here. Do them separately.
1653 if (&NMD == SrcModFlags)
1655 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(NMD.getName());
1656 // Add Src elements into Dest node.
1657 for (const MDNode *op : NMD.operands())
1658 DestNMD->addOperand(MapMetadata(
1659 op, ValueMap, RF_MoveDistinctMDs | RF_NullMapMissingGlobalValues,
1660 &TypeMap, &ValMaterializer));
1664 /// Merge the linker flags in Src into the Dest module.
1665 bool ModuleLinker::linkModuleFlagsMetadata() {
1666 // If the source module has no module flags, we are done.
1667 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1668 if (!SrcModFlags) return false;
1670 // If the destination module doesn't have module flags yet, then just copy
1671 // over the source module's flags.
1672 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
1673 if (DstModFlags->getNumOperands() == 0) {
1674 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1675 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1680 // First build a map of the existing module flags and requirements.
1681 DenseMap<MDString *, std::pair<MDNode *, unsigned>> Flags;
1682 SmallSetVector<MDNode*, 16> Requirements;
1683 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1684 MDNode *Op = DstModFlags->getOperand(I);
1685 ConstantInt *Behavior = mdconst::extract<ConstantInt>(Op->getOperand(0));
1686 MDString *ID = cast<MDString>(Op->getOperand(1));
1688 if (Behavior->getZExtValue() == Module::Require) {
1689 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1691 Flags[ID] = std::make_pair(Op, I);
1695 // Merge in the flags from the source module, and also collect its set of
1697 bool HasErr = false;
1698 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1699 MDNode *SrcOp = SrcModFlags->getOperand(I);
1700 ConstantInt *SrcBehavior =
1701 mdconst::extract<ConstantInt>(SrcOp->getOperand(0));
1702 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1705 std::tie(DstOp, DstIndex) = Flags.lookup(ID);
1706 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1708 // If this is a requirement, add it and continue.
1709 if (SrcBehaviorValue == Module::Require) {
1710 // If the destination module does not already have this requirement, add
1712 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1713 DstModFlags->addOperand(SrcOp);
1718 // If there is no existing flag with this ID, just add it.
1720 Flags[ID] = std::make_pair(SrcOp, DstModFlags->getNumOperands());
1721 DstModFlags->addOperand(SrcOp);
1725 // Otherwise, perform a merge.
1726 ConstantInt *DstBehavior =
1727 mdconst::extract<ConstantInt>(DstOp->getOperand(0));
1728 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1730 // If either flag has override behavior, handle it first.
1731 if (DstBehaviorValue == Module::Override) {
1732 // Diagnose inconsistent flags which both have override behavior.
1733 if (SrcBehaviorValue == Module::Override &&
1734 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1735 HasErr |= emitError("linking module flags '" + ID->getString() +
1736 "': IDs have conflicting override values");
1739 } else if (SrcBehaviorValue == Module::Override) {
1740 // Update the destination flag to that of the source.
1741 DstModFlags->setOperand(DstIndex, SrcOp);
1742 Flags[ID].first = SrcOp;
1746 // Diagnose inconsistent merge behavior types.
1747 if (SrcBehaviorValue != DstBehaviorValue) {
1748 HasErr |= emitError("linking module flags '" + ID->getString() +
1749 "': IDs have conflicting behaviors");
1753 auto replaceDstValue = [&](MDNode *New) {
1754 Metadata *FlagOps[] = {DstOp->getOperand(0), ID, New};
1755 MDNode *Flag = MDNode::get(DstM->getContext(), FlagOps);
1756 DstModFlags->setOperand(DstIndex, Flag);
1757 Flags[ID].first = Flag;
1760 // Perform the merge for standard behavior types.
1761 switch (SrcBehaviorValue) {
1762 case Module::Require:
1763 case Module::Override: llvm_unreachable("not possible");
1764 case Module::Error: {
1765 // Emit an error if the values differ.
1766 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1767 HasErr |= emitError("linking module flags '" + ID->getString() +
1768 "': IDs have conflicting values");
1772 case Module::Warning: {
1773 // Emit a warning if the values differ.
1774 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1775 emitWarning("linking module flags '" + ID->getString() +
1776 "': IDs have conflicting values");
1780 case Module::Append: {
1781 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1782 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1783 SmallVector<Metadata *, 8> MDs;
1784 MDs.reserve(DstValue->getNumOperands() + SrcValue->getNumOperands());
1785 MDs.append(DstValue->op_begin(), DstValue->op_end());
1786 MDs.append(SrcValue->op_begin(), SrcValue->op_end());
1788 replaceDstValue(MDNode::get(DstM->getContext(), MDs));
1791 case Module::AppendUnique: {
1792 SmallSetVector<Metadata *, 16> Elts;
1793 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1794 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1795 Elts.insert(DstValue->op_begin(), DstValue->op_end());
1796 Elts.insert(SrcValue->op_begin(), SrcValue->op_end());
1798 replaceDstValue(MDNode::get(DstM->getContext(),
1799 makeArrayRef(Elts.begin(), Elts.end())));
1805 // Check all of the requirements.
1806 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1807 MDNode *Requirement = Requirements[I];
1808 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1809 Metadata *ReqValue = Requirement->getOperand(1);
1811 MDNode *Op = Flags[Flag].first;
1812 if (!Op || Op->getOperand(2) != ReqValue) {
1813 HasErr |= emitError("linking module flags '" + Flag->getString() +
1814 "': does not have the required value");
1822 // This function returns true if the triples match.
1823 static bool triplesMatch(const Triple &T0, const Triple &T1) {
1824 // If vendor is apple, ignore the version number.
1825 if (T0.getVendor() == Triple::Apple)
1826 return T0.getArch() == T1.getArch() &&
1827 T0.getSubArch() == T1.getSubArch() &&
1828 T0.getVendor() == T1.getVendor() &&
1829 T0.getOS() == T1.getOS();
1834 // This function returns the merged triple.
1835 static std::string mergeTriples(const Triple &SrcTriple, const Triple &DstTriple) {
1836 // If vendor is apple, pick the triple with the larger version number.
1837 if (SrcTriple.getVendor() == Triple::Apple)
1838 if (DstTriple.isOSVersionLT(SrcTriple))
1839 return SrcTriple.str();
1841 return DstTriple.str();
1844 bool ModuleLinker::run() {
1845 assert(DstM && "Null destination module");
1846 assert(SrcM && "Null source module");
1848 // Inherit the target data from the source module if the destination module
1849 // doesn't have one already.
1850 if (DstM->getDataLayout().isDefault())
1851 DstM->setDataLayout(SrcM->getDataLayout());
1853 if (SrcM->getDataLayout() != DstM->getDataLayout()) {
1854 emitWarning("Linking two modules of different data layouts: '" +
1855 SrcM->getModuleIdentifier() + "' is '" +
1856 SrcM->getDataLayoutStr() + "' whereas '" +
1857 DstM->getModuleIdentifier() + "' is '" +
1858 DstM->getDataLayoutStr() + "'\n");
1861 // Copy the target triple from the source to dest if the dest's is empty.
1862 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
1863 DstM->setTargetTriple(SrcM->getTargetTriple());
1865 Triple SrcTriple(SrcM->getTargetTriple()), DstTriple(DstM->getTargetTriple());
1867 if (!SrcM->getTargetTriple().empty() && !triplesMatch(SrcTriple, DstTriple))
1868 emitWarning("Linking two modules of different target triples: " +
1869 SrcM->getModuleIdentifier() + "' is '" +
1870 SrcM->getTargetTriple() + "' whereas '" +
1871 DstM->getModuleIdentifier() + "' is '" +
1872 DstM->getTargetTriple() + "'\n");
1874 DstM->setTargetTriple(mergeTriples(SrcTriple, DstTriple));
1876 // Append the module inline asm string.
1877 if (!SrcM->getModuleInlineAsm().empty()) {
1878 if (DstM->getModuleInlineAsm().empty())
1879 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
1881 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
1882 SrcM->getModuleInlineAsm());
1885 // Loop over all of the linked values to compute type mappings.
1886 computeTypeMapping();
1888 ComdatsChosen.clear();
1889 for (const auto &SMEC : SrcM->getComdatSymbolTable()) {
1890 const Comdat &C = SMEC.getValue();
1891 if (ComdatsChosen.count(&C))
1893 Comdat::SelectionKind SK;
1895 if (getComdatResult(&C, SK, LinkFromSrc))
1897 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1900 // Upgrade mismatched global arrays.
1901 upgradeMismatchedGlobals();
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 (linkGlobalValueProto(&GV))
1909 // Link the functions together between the two modules, without doing function
1910 // bodies... this just adds external function prototypes to the DstM
1911 // function... We do this so that when we begin processing function bodies,
1912 // all of the global values that may be referenced are available in our
1914 for (Function &F :*SrcM)
1915 if (linkGlobalValueProto(&F))
1918 // If there were any aliases, link them now.
1919 for (GlobalAlias &GA : SrcM->aliases())
1920 if (linkGlobalValueProto(&GA))
1923 for (AppendingVarInfo &AppendingVar : AppendingVars)
1924 linkAppendingVarInit(AppendingVar);
1926 for (const auto &Entry : DstM->getComdatSymbolTable()) {
1927 const Comdat &C = Entry.getValue();
1928 if (C.getSelectionKind() == Comdat::Any)
1930 const GlobalValue *GV = SrcM->getNamedValue(C.getName());
1932 MapValue(GV, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer);
1935 // Link in the function bodies that are defined in the source module into
1937 for (Function &SF : *SrcM) {
1938 // Skip if no body (function is external).
1939 if (SF.isDeclaration())
1942 // Skip if not linking from source.
1943 if (DoNotLinkFromSource.count(&SF))
1946 if (linkGlobalValueBody(SF))
1950 // Resolve all uses of aliases with aliasees.
1951 for (GlobalAlias &Src : SrcM->aliases()) {
1952 if (DoNotLinkFromSource.count(&Src))
1954 linkGlobalValueBody(Src);
1957 // Update the initializers in the DstM module now that all globals that may
1958 // be referenced are in DstM.
1959 for (GlobalVariable &Src : SrcM->globals()) {
1960 // Only process initialized GV's or ones not already in dest.
1961 if (!Src.hasInitializer() || DoNotLinkFromSource.count(&Src))
1963 linkGlobalValueBody(Src);
1966 // Note that we are done linking global value bodies. This prevents
1967 // metadata linking from creating new references.
1968 DoneLinkingBodies = true;
1970 // Remap all of the named MDNodes in Src into the DstM module. We do this
1971 // after linking GlobalValues so that MDNodes that reference GlobalValues
1972 // are properly remapped.
1975 // Merge the module flags into the DstM module.
1976 if (linkModuleFlagsMetadata())
1982 Linker::StructTypeKeyInfo::KeyTy::KeyTy(ArrayRef<Type *> E, bool P)
1983 : ETypes(E), IsPacked(P) {}
1985 Linker::StructTypeKeyInfo::KeyTy::KeyTy(const StructType *ST)
1986 : ETypes(ST->elements()), IsPacked(ST->isPacked()) {}
1988 bool Linker::StructTypeKeyInfo::KeyTy::operator==(const KeyTy &That) const {
1989 if (IsPacked != That.IsPacked)
1991 if (ETypes != That.ETypes)
1996 bool Linker::StructTypeKeyInfo::KeyTy::operator!=(const KeyTy &That) const {
1997 return !this->operator==(That);
2000 StructType *Linker::StructTypeKeyInfo::getEmptyKey() {
2001 return DenseMapInfo<StructType *>::getEmptyKey();
2004 StructType *Linker::StructTypeKeyInfo::getTombstoneKey() {
2005 return DenseMapInfo<StructType *>::getTombstoneKey();
2008 unsigned Linker::StructTypeKeyInfo::getHashValue(const KeyTy &Key) {
2009 return hash_combine(hash_combine_range(Key.ETypes.begin(), Key.ETypes.end()),
2013 unsigned Linker::StructTypeKeyInfo::getHashValue(const StructType *ST) {
2014 return getHashValue(KeyTy(ST));
2017 bool Linker::StructTypeKeyInfo::isEqual(const KeyTy &LHS,
2018 const StructType *RHS) {
2019 if (RHS == getEmptyKey() || RHS == getTombstoneKey())
2021 return LHS == KeyTy(RHS);
2024 bool Linker::StructTypeKeyInfo::isEqual(const StructType *LHS,
2025 const StructType *RHS) {
2026 if (RHS == getEmptyKey())
2027 return LHS == getEmptyKey();
2029 if (RHS == getTombstoneKey())
2030 return LHS == getTombstoneKey();
2032 return KeyTy(LHS) == KeyTy(RHS);
2035 void Linker::IdentifiedStructTypeSet::addNonOpaque(StructType *Ty) {
2036 assert(!Ty->isOpaque());
2037 NonOpaqueStructTypes.insert(Ty);
2040 void Linker::IdentifiedStructTypeSet::switchToNonOpaque(StructType *Ty) {
2041 assert(!Ty->isOpaque());
2042 NonOpaqueStructTypes.insert(Ty);
2043 bool Removed = OpaqueStructTypes.erase(Ty);
2048 void Linker::IdentifiedStructTypeSet::addOpaque(StructType *Ty) {
2049 assert(Ty->isOpaque());
2050 OpaqueStructTypes.insert(Ty);
2054 Linker::IdentifiedStructTypeSet::findNonOpaque(ArrayRef<Type *> ETypes,
2056 Linker::StructTypeKeyInfo::KeyTy Key(ETypes, IsPacked);
2057 auto I = NonOpaqueStructTypes.find_as(Key);
2058 if (I == NonOpaqueStructTypes.end())
2063 bool Linker::IdentifiedStructTypeSet::hasType(StructType *Ty) {
2065 return OpaqueStructTypes.count(Ty);
2066 auto I = NonOpaqueStructTypes.find(Ty);
2067 if (I == NonOpaqueStructTypes.end())
2072 void Linker::init(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
2073 this->Composite = M;
2074 this->DiagnosticHandler = DiagnosticHandler;
2076 TypeFinder StructTypes;
2077 StructTypes.run(*M, true);
2078 for (StructType *Ty : StructTypes) {
2080 IdentifiedStructTypes.addOpaque(Ty);
2082 IdentifiedStructTypes.addNonOpaque(Ty);
2086 Linker::Linker(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
2087 init(M, DiagnosticHandler);
2090 Linker::Linker(Module *M) {
2091 init(M, [this](const DiagnosticInfo &DI) {
2092 Composite->getContext().diagnose(DI);
2096 void Linker::deleteModule() {
2098 Composite = nullptr;
2101 bool Linker::linkInModule(Module *Src, unsigned Flags,
2102 const FunctionInfoIndex *Index,
2103 Function *FuncToImport) {
2104 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,
2105 DiagnosticHandler, Flags, Index, FuncToImport);
2106 bool RetCode = TheLinker.run();
2107 Composite->dropTriviallyDeadConstantArrays();
2111 void Linker::setModule(Module *Dst) {
2112 init(Dst, DiagnosticHandler);
2115 //===----------------------------------------------------------------------===//
2116 // LinkModules entrypoint.
2117 //===----------------------------------------------------------------------===//
2119 /// This function links two modules together, with the resulting Dest module
2120 /// modified to be the composite of the two input modules. If an error occurs,
2121 /// true is returned and ErrorMsg (if not null) is set to indicate the problem.
2122 /// Upon failure, the Dest module could be in a modified state, and shouldn't be
2123 /// relied on to be consistent.
2124 bool Linker::LinkModules(Module *Dest, Module *Src,
2125 DiagnosticHandlerFunction DiagnosticHandler,
2127 Linker L(Dest, DiagnosticHandler);
2128 return L.linkInModule(Src, Flags);
2131 bool Linker::LinkModules(Module *Dest, Module *Src, unsigned Flags) {
2133 return L.linkInModule(Src, Flags);
2136 //===----------------------------------------------------------------------===//
2138 //===----------------------------------------------------------------------===//
2140 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
2141 LLVMLinkerMode Unused, char **OutMessages) {
2142 Module *D = unwrap(Dest);
2143 std::string Message;
2144 raw_string_ostream Stream(Message);
2145 DiagnosticPrinterRawOStream DP(Stream);
2147 LLVMBool Result = Linker::LinkModules(
2148 D, unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); });
2150 if (OutMessages && Result) {
2152 *OutMessages = strdup(Message.c_str());