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 GlobalValue *, 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;
439 bool HasError = false;
442 ModuleLinker(Module *dstM, Linker::IdentifiedStructTypeSet &Set, Module *srcM,
443 DiagnosticHandlerFunction DiagnosticHandler, unsigned Flags,
444 const FunctionInfoIndex *Index = nullptr,
445 Function *FuncToImport = nullptr)
446 : DstM(dstM), SrcM(srcM), TypeMap(Set), ValMaterializer(this),
447 DiagnosticHandler(DiagnosticHandler), Flags(Flags), ImportIndex(Index),
448 ImportFunction(FuncToImport), HasExportedFunctions(false),
449 DoneLinkingBodies(false) {
450 assert((ImportIndex || !ImportFunction) &&
451 "Expect a FunctionInfoIndex when importing");
452 // If we have a FunctionInfoIndex but no function to import,
453 // then this is the primary module being compiled in a ThinLTO
454 // backend compilation, and we need to see if it has functions that
455 // may be exported to another backend compilation.
456 if (ImportIndex && !ImportFunction)
457 HasExportedFunctions = ImportIndex->hasExportedFunctions(SrcM);
461 Value *materializeDeclFor(Value *V);
462 void materializeInitFor(GlobalValue *New, GlobalValue *Old);
465 bool shouldOverrideFromSrc() { return Flags & Linker::OverrideFromSrc; }
466 bool shouldLinkOnlyNeeded() { return Flags & Linker::LinkOnlyNeeded; }
467 bool shouldInternalizeLinkedSymbols() {
468 return Flags & Linker::InternalizeLinkedSymbols;
471 /// Handles cloning of a global values from the source module into
472 /// the destination module, including setting the attributes and visibility.
473 GlobalValue *copyGlobalValueProto(TypeMapTy &TypeMap, const GlobalValue *SGV,
474 const GlobalValue *DGV = nullptr);
476 /// Check if we should promote the given local value to global scope.
477 bool doPromoteLocalToGlobal(const GlobalValue *SGV);
479 /// Check if all global value body linking is complete.
480 bool doneLinkingBodies() { return DoneLinkingBodies; }
482 bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
483 const GlobalValue &Src);
485 /// Helper method for setting a message and returning an error code.
486 bool emitError(const Twine &Message) {
487 DiagnosticHandler(LinkDiagnosticInfo(DS_Error, Message));
492 void emitWarning(const Twine &Message) {
493 DiagnosticHandler(LinkDiagnosticInfo(DS_Warning, Message));
496 bool getComdatLeader(Module *M, StringRef ComdatName,
497 const GlobalVariable *&GVar);
498 bool computeResultingSelectionKind(StringRef ComdatName,
499 Comdat::SelectionKind Src,
500 Comdat::SelectionKind Dst,
501 Comdat::SelectionKind &Result,
503 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
505 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
507 // Keep track of the global value members of each comdat in source.
508 DenseMap<const Comdat *, std::vector<GlobalValue *>> ComdatMembers;
510 /// Given a global in the source module, return the global in the
511 /// destination module that is being linked to, if any.
512 GlobalValue *getLinkedToGlobal(const GlobalValue *SrcGV) {
513 // If the source has no name it can't link. If it has local linkage,
514 // there is no name match-up going on.
515 if (!SrcGV->hasName() || GlobalValue::isLocalLinkage(getLinkage(SrcGV)))
518 // Otherwise see if we have a match in the destination module's symtab.
519 GlobalValue *DGV = DstM->getNamedValue(getName(SrcGV));
523 // If we found a global with the same name in the dest module, but it has
524 // internal linkage, we are really not doing any linkage here.
525 if (DGV->hasLocalLinkage())
528 // Otherwise, we do in fact link to the destination global.
532 void computeTypeMapping();
534 void upgradeMismatchedGlobalArray(StringRef Name);
535 void upgradeMismatchedGlobals();
537 bool linkIfNeeded(GlobalValue &GV);
538 bool linkAppendingVarProto(GlobalVariable *DstGV,
539 const GlobalVariable *SrcGV);
541 bool linkGlobalValueProto(GlobalValue *GV);
542 bool linkModuleFlagsMetadata();
544 void linkAppendingVarInit(AppendingVarInfo &AVI);
546 void linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src);
547 bool linkFunctionBody(Function &Dst, Function &Src);
548 void linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src);
549 bool linkGlobalValueBody(GlobalValue &Src);
551 /// Functions that take care of cloning a specific global value type
552 /// into the destination module.
553 GlobalVariable *copyGlobalVariableProto(TypeMapTy &TypeMap,
554 const GlobalVariable *SGVar);
555 Function *copyFunctionProto(TypeMapTy &TypeMap, const Function *SF);
556 GlobalValue *copyGlobalAliasProto(TypeMapTy &TypeMap, const GlobalAlias *SGA);
558 /// Helper methods to check if we are importing from or potentially
559 /// exporting from the current source module.
560 bool isPerformingImport() { return ImportFunction != nullptr; }
561 bool isModuleExporting() { return HasExportedFunctions; }
563 /// If we are importing from the source module, checks if we should
564 /// import SGV as a definition, otherwise import as a declaration.
565 bool doImportAsDefinition(const GlobalValue *SGV);
567 /// Get the name for SGV that should be used in the linked destination
568 /// module. Specifically, this handles the case where we need to rename
569 /// a local that is being promoted to global scope.
570 std::string getName(const GlobalValue *SGV);
572 /// Get the new linkage for SGV that should be used in the linked destination
573 /// module. Specifically, for ThinLTO importing or exporting it may need
575 GlobalValue::LinkageTypes getLinkage(const GlobalValue *SGV);
577 /// Copies the necessary global value attributes and name from the source
578 /// to the newly cloned global value.
579 void copyGVAttributes(GlobalValue *NewGV, const GlobalValue *SrcGV);
581 /// Updates the visibility for the new global cloned from the source
582 /// and, if applicable, linked with an existing destination global.
583 /// Handles visibility change required for promoted locals.
584 void setVisibility(GlobalValue *NewGV, const GlobalValue *SGV,
585 const GlobalValue *DGV = nullptr);
587 void linkNamedMDNodes();
591 /// The LLVM SymbolTable class autorenames globals that conflict in the symbol
592 /// table. This is good for all clients except for us. Go through the trouble
593 /// to force this back.
594 static void forceRenaming(GlobalValue *GV, StringRef Name) {
595 // If the global doesn't force its name or if it already has the right name,
596 // there is nothing for us to do.
597 // Note that any required local to global promotion should already be done,
598 // so promoted locals will not skip this handling as their linkage is no
600 if (GV->hasLocalLinkage() || GV->getName() == Name)
603 Module *M = GV->getParent();
605 // If there is a conflict, rename the conflict.
606 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
607 GV->takeName(ConflictGV);
608 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
609 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
611 GV->setName(Name); // Force the name back
615 /// copy additional attributes (those not needed to construct a GlobalValue)
616 /// from the SrcGV to the DestGV.
617 void ModuleLinker::copyGVAttributes(GlobalValue *NewGV,
618 const GlobalValue *SrcGV) {
619 auto *GA = dyn_cast<GlobalAlias>(SrcGV);
620 // Check for the special case of converting an alias (definition) to a
621 // non-alias (declaration). This can happen when we are importing and
622 // encounter a weak_any alias (weak_any defs may not be imported, see
623 // comments in ModuleLinker::getLinkage) or an alias whose base object is
624 // being imported as a declaration. In that case copy the attributes from the
626 if (GA && !dyn_cast<GlobalAlias>(NewGV)) {
627 assert(isPerformingImport() && !doImportAsDefinition(GA));
628 NewGV->copyAttributesFrom(GA->getBaseObject());
630 NewGV->copyAttributesFrom(SrcGV);
631 forceRenaming(NewGV, getName(SrcGV));
634 bool ModuleLinker::doImportAsDefinition(const GlobalValue *SGV) {
635 if (!isPerformingImport())
637 auto *GA = dyn_cast<GlobalAlias>(SGV);
639 if (GA->hasWeakAnyLinkage())
641 const GlobalObject *GO = GA->getBaseObject();
642 if (!GO->hasLinkOnceODRLinkage())
644 return doImportAsDefinition(GO);
646 // Always import GlobalVariable definitions, except for the special
647 // case of WeakAny which are imported as ExternalWeak declarations
648 // (see comments in ModuleLinker::getLinkage). The linkage changes
649 // described in ModuleLinker::getLinkage ensure the correct behavior (e.g.
650 // global variables with external linkage are transformed to
651 // available_externally definitions, which are ultimately turned into
652 // declarations after the EliminateAvailableExternally pass).
653 if (isa<GlobalVariable>(SGV) && !SGV->isDeclaration() &&
654 !SGV->hasWeakAnyLinkage())
656 // Only import the function requested for importing.
657 auto *SF = dyn_cast<Function>(SGV);
658 if (SF && SF == ImportFunction)
664 bool ModuleLinker::doPromoteLocalToGlobal(const GlobalValue *SGV) {
665 assert(SGV->hasLocalLinkage());
666 // Both the imported references and the original local variable must
668 if (!isPerformingImport() && !isModuleExporting())
671 // Local const variables never need to be promoted unless they are address
672 // taken. The imported uses can simply use the clone created in this module.
673 // For now we are conservative in determining which variables are not
674 // address taken by checking the unnamed addr flag. To be more aggressive,
675 // the address taken information must be checked earlier during parsing
676 // of the module and recorded in the function index for use when importing
678 auto *GVar = dyn_cast<GlobalVariable>(SGV);
679 if (GVar && GVar->isConstant() && GVar->hasUnnamedAddr())
682 // Eventually we only need to promote functions in the exporting module that
683 // are referenced by a potentially exported function (i.e. one that is in the
688 std::string ModuleLinker::getName(const GlobalValue *SGV) {
689 // For locals that must be promoted to global scope, ensure that
690 // the promoted name uniquely identifies the copy in the original module,
691 // using the ID assigned during combined index creation. When importing,
692 // we rename all locals (not just those that are promoted) in order to
693 // avoid naming conflicts between locals imported from different modules.
694 if (SGV->hasLocalLinkage() &&
695 (doPromoteLocalToGlobal(SGV) || isPerformingImport()))
696 return FunctionInfoIndex::getGlobalNameForLocal(
698 ImportIndex->getModuleId(SGV->getParent()->getModuleIdentifier()));
699 return SGV->getName();
702 GlobalValue::LinkageTypes ModuleLinker::getLinkage(const GlobalValue *SGV) {
703 // Any local variable that is referenced by an exported function needs
704 // to be promoted to global scope. Since we don't currently know which
705 // functions reference which local variables/functions, we must treat
706 // all as potentially exported if this module is exporting anything.
707 if (isModuleExporting()) {
708 if (SGV->hasLocalLinkage() && doPromoteLocalToGlobal(SGV))
709 return GlobalValue::ExternalLinkage;
710 return SGV->getLinkage();
713 // Otherwise, if we aren't importing, no linkage change is needed.
714 if (!isPerformingImport())
715 return SGV->getLinkage();
717 switch (SGV->getLinkage()) {
718 case GlobalValue::ExternalLinkage:
719 // External defnitions are converted to available_externally
720 // definitions upon import, so that they are available for inlining
721 // and/or optimization, but are turned into declarations later
722 // during the EliminateAvailableExternally pass.
723 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
724 return GlobalValue::AvailableExternallyLinkage;
725 // An imported external declaration stays external.
726 return SGV->getLinkage();
728 case GlobalValue::AvailableExternallyLinkage:
729 // An imported available_externally definition converts
730 // to external if imported as a declaration.
731 if (!doImportAsDefinition(SGV))
732 return GlobalValue::ExternalLinkage;
733 // An imported available_externally declaration stays that way.
734 return SGV->getLinkage();
736 case GlobalValue::LinkOnceAnyLinkage:
737 case GlobalValue::LinkOnceODRLinkage:
738 // These both stay the same when importing the definition.
739 // The ThinLTO pass will eventually force-import their definitions.
740 return SGV->getLinkage();
742 case GlobalValue::WeakAnyLinkage:
743 // Can't import weak_any definitions correctly, or we might change the
744 // program semantics, since the linker will pick the first weak_any
745 // definition and importing would change the order they are seen by the
746 // linker. The module linking caller needs to enforce this.
747 assert(!doImportAsDefinition(SGV));
748 // If imported as a declaration, it becomes external_weak.
749 return GlobalValue::ExternalWeakLinkage;
751 case GlobalValue::WeakODRLinkage:
752 // For weak_odr linkage, there is a guarantee that all copies will be
753 // equivalent, so the issue described above for weak_any does not exist,
754 // and the definition can be imported. It can be treated similarly
755 // to an imported externally visible global value.
756 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
757 return GlobalValue::AvailableExternallyLinkage;
759 return GlobalValue::ExternalLinkage;
761 case GlobalValue::AppendingLinkage:
762 // It would be incorrect to import an appending linkage variable,
763 // since it would cause global constructors/destructors to be
764 // executed multiple times. This should have already been handled
765 // by linkGlobalValueProto.
766 llvm_unreachable("Cannot import appending linkage variable");
768 case GlobalValue::InternalLinkage:
769 case GlobalValue::PrivateLinkage:
770 // If we are promoting the local to global scope, it is handled
771 // similarly to a normal externally visible global.
772 if (doPromoteLocalToGlobal(SGV)) {
773 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
774 return GlobalValue::AvailableExternallyLinkage;
776 return GlobalValue::ExternalLinkage;
778 // A non-promoted imported local definition stays local.
779 // The ThinLTO pass will eventually force-import their definitions.
780 return SGV->getLinkage();
782 case GlobalValue::ExternalWeakLinkage:
783 // External weak doesn't apply to definitions, must be a declaration.
784 assert(!doImportAsDefinition(SGV));
785 // Linkage stays external_weak.
786 return SGV->getLinkage();
788 case GlobalValue::CommonLinkage:
789 // Linkage stays common on definitions.
790 // The ThinLTO pass will eventually force-import their definitions.
791 return SGV->getLinkage();
794 llvm_unreachable("unknown linkage type");
797 /// Loop through the global variables in the src module and merge them into the
800 ModuleLinker::copyGlobalVariableProto(TypeMapTy &TypeMap,
801 const GlobalVariable *SGVar) {
802 // No linking to be performed or linking from the source: simply create an
803 // identical version of the symbol over in the dest module... the
804 // initializer will be filled in later by LinkGlobalInits.
805 GlobalVariable *NewDGV = new GlobalVariable(
806 *DstM, TypeMap.get(SGVar->getType()->getElementType()),
807 SGVar->isConstant(), getLinkage(SGVar), /*init*/ nullptr, getName(SGVar),
808 /*insertbefore*/ nullptr, SGVar->getThreadLocalMode(),
809 SGVar->getType()->getAddressSpace());
814 /// Link the function in the source module into the destination module if
815 /// needed, setting up mapping information.
816 Function *ModuleLinker::copyFunctionProto(TypeMapTy &TypeMap,
817 const Function *SF) {
818 // If there is no linkage to be performed or we are linking from the source,
820 return Function::Create(TypeMap.get(SF->getFunctionType()), getLinkage(SF),
824 /// Set up prototypes for any aliases that come over from the source module.
825 GlobalValue *ModuleLinker::copyGlobalAliasProto(TypeMapTy &TypeMap,
826 const GlobalAlias *SGA) {
827 // If we are importing and encounter a weak_any alias, or an alias to
828 // an object being imported as a declaration, we must import the alias
829 // as a declaration as well, which involves converting it to a non-alias.
830 // See comments in ModuleLinker::getLinkage for why we cannot import
831 // weak_any defintions.
832 if (isPerformingImport() && !doImportAsDefinition(SGA)) {
833 // Need to convert to declaration. All aliases must be definitions.
834 const GlobalValue *GVal = SGA->getBaseObject();
836 if (auto *GVar = dyn_cast<GlobalVariable>(GVal))
837 NewGV = copyGlobalVariableProto(TypeMap, GVar);
839 auto *F = dyn_cast<Function>(GVal);
841 NewGV = copyFunctionProto(TypeMap, F);
843 // Set the linkage to External or ExternalWeak (see comments in
844 // ModuleLinker::getLinkage for why WeakAny is converted to ExternalWeak).
845 if (SGA->hasWeakAnyLinkage())
846 NewGV->setLinkage(GlobalValue::ExternalWeakLinkage);
848 NewGV->setLinkage(GlobalValue::ExternalLinkage);
851 // If there is no linkage to be performed or we're linking from the source,
853 auto *Ty = TypeMap.get(SGA->getValueType());
854 return GlobalAlias::create(Ty, SGA->getType()->getPointerAddressSpace(),
855 getLinkage(SGA), getName(SGA), DstM);
858 static GlobalValue::VisibilityTypes
859 getMinVisibility(GlobalValue::VisibilityTypes A,
860 GlobalValue::VisibilityTypes B) {
861 if (A == GlobalValue::HiddenVisibility || B == GlobalValue::HiddenVisibility)
862 return GlobalValue::HiddenVisibility;
863 if (A == GlobalValue::ProtectedVisibility ||
864 B == GlobalValue::ProtectedVisibility)
865 return GlobalValue::ProtectedVisibility;
866 return GlobalValue::DefaultVisibility;
869 void ModuleLinker::setVisibility(GlobalValue *NewGV, const GlobalValue *SGV,
870 const GlobalValue *DGV) {
871 GlobalValue::VisibilityTypes Visibility = SGV->getVisibility();
873 Visibility = getMinVisibility(DGV->getVisibility(), Visibility);
874 // For promoted locals, mark them hidden so that they can later be
875 // stripped from the symbol table to reduce bloat.
876 if (SGV->hasLocalLinkage() && doPromoteLocalToGlobal(SGV))
877 Visibility = GlobalValue::HiddenVisibility;
878 NewGV->setVisibility(Visibility);
881 GlobalValue *ModuleLinker::copyGlobalValueProto(TypeMapTy &TypeMap,
882 const GlobalValue *SGV,
883 const GlobalValue *DGV) {
885 if (auto *SGVar = dyn_cast<GlobalVariable>(SGV))
886 NewGV = copyGlobalVariableProto(TypeMap, SGVar);
887 else if (auto *SF = dyn_cast<Function>(SGV))
888 NewGV = copyFunctionProto(TypeMap, SF);
890 NewGV = copyGlobalAliasProto(TypeMap, cast<GlobalAlias>(SGV));
891 copyGVAttributes(NewGV, SGV);
892 setVisibility(NewGV, SGV, DGV);
896 Value *ValueMaterializerTy::materializeDeclFor(Value *V) {
897 return ModLinker->materializeDeclFor(V);
900 Value *ModuleLinker::materializeDeclFor(Value *V) {
901 auto *SGV = dyn_cast<GlobalValue>(V);
905 // If we are done linking global value bodies (i.e. we are performing
906 // metadata linking), don't link in the global value due to this
907 // reference, simply map it to null.
908 if (doneLinkingBodies())
911 linkGlobalValueProto(SGV);
914 Value *Ret = ValueMap[SGV];
919 void ValueMaterializerTy::materializeInitFor(GlobalValue *New,
921 return ModLinker->materializeInitFor(New, Old);
924 void ModuleLinker::materializeInitFor(GlobalValue *New, GlobalValue *Old) {
925 if (auto *F = dyn_cast<Function>(New)) {
926 if (!F->isDeclaration())
928 } else if (auto *V = dyn_cast<GlobalVariable>(New)) {
929 if (V->hasInitializer())
932 auto *A = cast<GlobalAlias>(New);
937 if (Old->isDeclaration())
940 if (isPerformingImport() && !doImportAsDefinition(Old))
943 if (DoNotLinkFromSource.count(Old)) {
944 if (!New->hasExternalLinkage() && !New->hasExternalWeakLinkage() &&
945 !New->hasAppendingLinkage())
946 emitError("Declaration points to discarded value");
950 linkGlobalValueBody(*Old);
953 bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName,
954 const GlobalVariable *&GVar) {
955 const GlobalValue *GVal = M->getNamedValue(ComdatName);
956 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
957 GVal = GA->getBaseObject();
959 // We cannot resolve the size of the aliasee yet.
960 return emitError("Linking COMDATs named '" + ComdatName +
961 "': COMDAT key involves incomputable alias size.");
964 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
967 "Linking COMDATs named '" + ComdatName +
968 "': GlobalVariable required for data dependent selection!");
973 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
974 Comdat::SelectionKind Src,
975 Comdat::SelectionKind Dst,
976 Comdat::SelectionKind &Result,
978 // The ability to mix Comdat::SelectionKind::Any with
979 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
980 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
981 Dst == Comdat::SelectionKind::Largest;
982 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
983 Src == Comdat::SelectionKind::Largest;
984 if (DstAnyOrLargest && SrcAnyOrLargest) {
985 if (Dst == Comdat::SelectionKind::Largest ||
986 Src == Comdat::SelectionKind::Largest)
987 Result = Comdat::SelectionKind::Largest;
989 Result = Comdat::SelectionKind::Any;
990 } else if (Src == Dst) {
993 return emitError("Linking COMDATs named '" + ComdatName +
994 "': invalid selection kinds!");
998 case Comdat::SelectionKind::Any:
1000 LinkFromSrc = false;
1002 case Comdat::SelectionKind::NoDuplicates:
1003 return emitError("Linking COMDATs named '" + ComdatName +
1004 "': noduplicates has been violated!");
1005 case Comdat::SelectionKind::ExactMatch:
1006 case Comdat::SelectionKind::Largest:
1007 case Comdat::SelectionKind::SameSize: {
1008 const GlobalVariable *DstGV;
1009 const GlobalVariable *SrcGV;
1010 if (getComdatLeader(DstM, ComdatName, DstGV) ||
1011 getComdatLeader(SrcM, ComdatName, SrcGV))
1014 const DataLayout &DstDL = DstM->getDataLayout();
1015 const DataLayout &SrcDL = SrcM->getDataLayout();
1017 DstDL.getTypeAllocSize(DstGV->getType()->getPointerElementType());
1019 SrcDL.getTypeAllocSize(SrcGV->getType()->getPointerElementType());
1020 if (Result == Comdat::SelectionKind::ExactMatch) {
1021 if (SrcGV->getInitializer() != DstGV->getInitializer())
1022 return emitError("Linking COMDATs named '" + ComdatName +
1023 "': ExactMatch violated!");
1024 LinkFromSrc = false;
1025 } else if (Result == Comdat::SelectionKind::Largest) {
1026 LinkFromSrc = SrcSize > DstSize;
1027 } else if (Result == Comdat::SelectionKind::SameSize) {
1028 if (SrcSize != DstSize)
1029 return emitError("Linking COMDATs named '" + ComdatName +
1030 "': SameSize violated!");
1031 LinkFromSrc = false;
1033 llvm_unreachable("unknown selection kind");
1042 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
1043 Comdat::SelectionKind &Result,
1044 bool &LinkFromSrc) {
1045 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
1046 StringRef ComdatName = SrcC->getName();
1047 Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable();
1048 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
1050 if (DstCI == ComdatSymTab.end()) {
1051 // Use the comdat if it is only available in one of the modules.
1057 const Comdat *DstC = &DstCI->second;
1058 Comdat::SelectionKind DSK = DstC->getSelectionKind();
1059 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
1063 bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
1064 const GlobalValue &Dest,
1065 const GlobalValue &Src) {
1066 // Should we unconditionally use the Src?
1067 if (shouldOverrideFromSrc()) {
1072 // We always have to add Src if it has appending linkage.
1073 if (Src.hasAppendingLinkage()) {
1074 // Caller should have already determined that we can't link from source
1075 // when importing (see comments in linkGlobalValueProto).
1076 assert(!isPerformingImport());
1081 bool SrcIsDeclaration = Src.isDeclarationForLinker();
1082 bool DestIsDeclaration = Dest.isDeclarationForLinker();
1084 if (isPerformingImport()) {
1085 if (isa<Function>(&Src)) {
1086 // For functions, LinkFromSrc iff this is the function requested
1087 // for importing. For variables, decide below normally.
1088 LinkFromSrc = (&Src == ImportFunction);
1092 // Check if this is an alias with an already existing definition
1093 // in Dest, which must have come from a prior importing pass from
1094 // the same Src module. Unlike imported function and variable
1095 // definitions, which are imported as available_externally and are
1096 // not definitions for the linker, that is not a valid linkage for
1097 // imported aliases which must be definitions. Simply use the existing
1099 if (isa<GlobalAlias>(&Src) && !DestIsDeclaration) {
1100 assert(isa<GlobalAlias>(&Dest));
1101 LinkFromSrc = false;
1106 if (SrcIsDeclaration) {
1107 // If Src is external or if both Src & Dest are external.. Just link the
1108 // external globals, we aren't adding anything.
1109 if (Src.hasDLLImportStorageClass()) {
1110 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
1111 LinkFromSrc = DestIsDeclaration;
1114 // If the Dest is weak, use the source linkage.
1115 LinkFromSrc = Dest.hasExternalWeakLinkage();
1119 if (DestIsDeclaration) {
1120 // If Dest is external but Src is not:
1125 if (Src.hasCommonLinkage()) {
1126 if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
1131 if (!Dest.hasCommonLinkage()) {
1132 LinkFromSrc = false;
1136 const DataLayout &DL = Dest.getParent()->getDataLayout();
1137 uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
1138 uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
1139 LinkFromSrc = SrcSize > DestSize;
1143 if (Src.isWeakForLinker()) {
1144 assert(!Dest.hasExternalWeakLinkage());
1145 assert(!Dest.hasAvailableExternallyLinkage());
1147 if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
1152 LinkFromSrc = false;
1156 if (Dest.isWeakForLinker()) {
1157 assert(Src.hasExternalLinkage());
1162 assert(!Src.hasExternalWeakLinkage());
1163 assert(!Dest.hasExternalWeakLinkage());
1164 assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
1165 "Unexpected linkage type!");
1166 return emitError("Linking globals named '" + Src.getName() +
1167 "': symbol multiply defined!");
1170 /// Loop over all of the linked values to compute type mappings. For example,
1171 /// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct
1172 /// types 'Foo' but one got renamed when the module was loaded into the same
1174 void ModuleLinker::computeTypeMapping() {
1175 for (GlobalValue &SGV : SrcM->globals()) {
1176 GlobalValue *DGV = getLinkedToGlobal(&SGV);
1180 if (!DGV->hasAppendingLinkage() || !SGV.hasAppendingLinkage()) {
1181 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1185 // Unify the element type of appending arrays.
1186 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
1187 ArrayType *SAT = cast<ArrayType>(SGV.getType()->getElementType());
1188 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
1191 for (GlobalValue &SGV : *SrcM) {
1192 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
1193 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1196 for (GlobalValue &SGV : SrcM->aliases()) {
1197 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
1198 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1201 // Incorporate types by name, scanning all the types in the source module.
1202 // At this point, the destination module may have a type "%foo = { i32 }" for
1203 // example. When the source module got loaded into the same LLVMContext, if
1204 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
1205 std::vector<StructType *> Types = SrcM->getIdentifiedStructTypes();
1206 for (StructType *ST : Types) {
1210 // Check to see if there is a dot in the name followed by a digit.
1211 size_t DotPos = ST->getName().rfind('.');
1212 if (DotPos == 0 || DotPos == StringRef::npos ||
1213 ST->getName().back() == '.' ||
1214 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos + 1])))
1217 // Check to see if the destination module has a struct with the prefix name.
1218 StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos));
1222 // Don't use it if this actually came from the source module. They're in
1223 // the same LLVMContext after all. Also don't use it unless the type is
1224 // actually used in the destination module. This can happen in situations
1227 // Module A Module B
1228 // -------- --------
1229 // %Z = type { %A } %B = type { %C.1 }
1230 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
1231 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
1232 // %C = type { i8* } %B.3 = type { %C.1 }
1234 // When we link Module B with Module A, the '%B' in Module B is
1235 // used. However, that would then use '%C.1'. But when we process '%C.1',
1236 // we prefer to take the '%C' version. So we are then left with both
1237 // '%C.1' and '%C' being used for the same types. This leads to some
1238 // variables using one type and some using the other.
1239 if (TypeMap.DstStructTypesSet.hasType(DST))
1240 TypeMap.addTypeMapping(DST, ST);
1243 // Now that we have discovered all of the type equivalences, get a body for
1244 // any 'opaque' types in the dest module that are now resolved.
1245 TypeMap.linkDefinedTypeBodies();
1248 static void upgradeGlobalArray(GlobalVariable *GV) {
1249 ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
1250 StructType *OldTy = cast<StructType>(ATy->getElementType());
1251 assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
1253 // Get the upgraded 3 element type.
1254 PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
1255 Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
1257 StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
1259 // Build new constants with a null third field filled in.
1260 Constant *OldInitC = GV->getInitializer();
1261 ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
1262 if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
1263 // Invalid initializer; give up.
1265 std::vector<Constant *> Initializers;
1266 if (OldInit && OldInit->getNumOperands()) {
1267 Value *Null = Constant::getNullValue(VoidPtrTy);
1268 for (Use &U : OldInit->operands()) {
1269 ConstantStruct *Init = cast<ConstantStruct>(U.get());
1270 Initializers.push_back(ConstantStruct::get(
1271 NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
1274 assert(Initializers.size() == ATy->getNumElements() &&
1275 "Failed to copy all array elements");
1277 // Replace the old GV with a new one.
1278 ATy = ArrayType::get(NewTy, Initializers.size());
1279 Constant *NewInit = ConstantArray::get(ATy, Initializers);
1280 GlobalVariable *NewGV = new GlobalVariable(
1281 *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
1282 GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
1283 GV->isExternallyInitialized());
1284 NewGV->copyAttributesFrom(GV);
1285 NewGV->takeName(GV);
1286 assert(GV->use_empty() && "program cannot use initializer list");
1287 GV->eraseFromParent();
1290 void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
1291 // Look for the global arrays.
1292 auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM->getNamedValue(Name));
1295 auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM->getNamedValue(Name));
1299 // Check if the types already match.
1300 auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
1302 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
1306 // Grab the element types. We can only upgrade an array of a two-field
1307 // struct. Only bother if the other one has three-fields.
1308 auto *DstEltTy = cast<StructType>(DstTy->getElementType());
1309 auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
1310 if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
1311 upgradeGlobalArray(DstGV);
1314 if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
1315 upgradeGlobalArray(SrcGV);
1317 // We can't upgrade any other differences.
1320 void ModuleLinker::upgradeMismatchedGlobals() {
1321 upgradeMismatchedGlobalArray("llvm.global_ctors");
1322 upgradeMismatchedGlobalArray("llvm.global_dtors");
1325 /// If there were any appending global variables, link them together now.
1326 /// Return true on error.
1327 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
1328 const GlobalVariable *SrcGV) {
1330 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
1331 Type *EltTy = SrcTy->getElementType();
1333 uint64_t NewSize = SrcTy->getNumElements();
1335 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
1336 NewSize += DstTy->getNumElements();
1338 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
1340 "Linking globals named '" + SrcGV->getName() +
1341 "': can only link appending global with another appending global!");
1343 // Check to see that they two arrays agree on type.
1344 if (EltTy != DstTy->getElementType())
1345 return emitError("Appending variables with different element types!");
1346 if (DstGV->isConstant() != SrcGV->isConstant())
1347 return emitError("Appending variables linked with different const'ness!");
1349 if (DstGV->getAlignment() != SrcGV->getAlignment())
1351 "Appending variables with different alignment need to be linked!");
1353 if (DstGV->getVisibility() != SrcGV->getVisibility())
1355 "Appending variables with different visibility need to be linked!");
1357 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
1359 "Appending variables with different unnamed_addr need to be linked!");
1361 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
1363 "Appending variables with different section name need to be linked!");
1366 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
1368 // Create the new global variable.
1369 GlobalVariable *NG = new GlobalVariable(
1370 *DstM, NewType, SrcGV->isConstant(), SrcGV->getLinkage(),
1371 /*init*/ nullptr, /*name*/ "", DstGV, SrcGV->getThreadLocalMode(),
1372 SrcGV->getType()->getAddressSpace());
1374 // Propagate alignment, visibility and section info.
1375 copyGVAttributes(NG, SrcGV);
1377 AppendingVarInfo AVI;
1379 AVI.DstInit = DstGV ? DstGV->getInitializer() : nullptr;
1380 AVI.SrcInit = SrcGV->getInitializer();
1381 AppendingVars.push_back(AVI);
1383 // Replace any uses of the two global variables with uses of the new
1385 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
1388 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
1389 DstGV->eraseFromParent();
1392 // Track the source variable so we don't try to link it.
1393 DoNotLinkFromSource.insert(SrcGV);
1398 bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) {
1399 GlobalValue *DGV = getLinkedToGlobal(SGV);
1401 // Handle the ultra special appending linkage case first.
1402 assert(!DGV || SGV->hasAppendingLinkage() == DGV->hasAppendingLinkage());
1403 if (SGV->hasAppendingLinkage() && isPerformingImport()) {
1404 // Don't want to append to global_ctors list, for example, when we
1405 // are importing for ThinLTO, otherwise the global ctors and dtors
1406 // get executed multiple times for local variables (the latter causing
1408 DoNotLinkFromSource.insert(SGV);
1411 if (SGV->hasAppendingLinkage())
1412 return linkAppendingVarProto(cast_or_null<GlobalVariable>(DGV),
1413 cast<GlobalVariable>(SGV));
1415 bool LinkFromSrc = true;
1416 Comdat *C = nullptr;
1417 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
1419 if (const Comdat *SC = SGV->getComdat()) {
1420 Comdat::SelectionKind SK;
1421 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1422 C = DstM->getOrInsertComdat(SC->getName());
1423 C->setSelectionKind(SK);
1425 if (shouldLinkFromSource(LinkFromSrc, *DGV, *SGV))
1430 // Track the source global so that we don't attempt to copy it over when
1431 // processing global initializers.
1432 DoNotLinkFromSource.insert(SGV);
1435 // Make sure to remember this mapping.
1437 ConstantExpr::getBitCast(DGV, TypeMap.get(SGV->getType()));
1441 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1444 if (!LinkFromSrc && DGV) {
1446 // When linking from source we setVisibility from copyGlobalValueProto.
1447 setVisibility(NewGV, SGV, DGV);
1449 NewGV = copyGlobalValueProto(TypeMap, SGV, DGV);
1451 if (isPerformingImport() && !doImportAsDefinition(SGV))
1452 DoNotLinkFromSource.insert(SGV);
1455 NewGV->setUnnamedAddr(HasUnnamedAddr);
1457 if (auto *NewGO = dyn_cast<GlobalObject>(NewGV)) {
1458 if (C && LinkFromSrc)
1459 NewGO->setComdat(C);
1461 if (DGV && DGV->hasCommonLinkage() && SGV->hasCommonLinkage())
1462 NewGO->setAlignment(std::max(DGV->getAlignment(), SGV->getAlignment()));
1465 if (auto *NewGVar = dyn_cast<GlobalVariable>(NewGV)) {
1466 auto *DGVar = dyn_cast_or_null<GlobalVariable>(DGV);
1467 auto *SGVar = dyn_cast<GlobalVariable>(SGV);
1468 if (DGVar && SGVar && DGVar->isDeclaration() && SGVar->isDeclaration() &&
1469 (!DGVar->isConstant() || !SGVar->isConstant()))
1470 NewGVar->setConstant(false);
1473 // Make sure to remember this mapping.
1476 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewGV, DGV->getType()));
1477 DGV->eraseFromParent();
1479 ValueMap[SGV] = NewGV;
1485 static void getArrayElements(const Constant *C,
1486 SmallVectorImpl<Constant *> &Dest) {
1487 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1489 for (unsigned i = 0; i != NumElements; ++i)
1490 Dest.push_back(C->getAggregateElement(i));
1493 void ModuleLinker::linkAppendingVarInit(AppendingVarInfo &AVI) {
1494 // Merge the initializer.
1495 SmallVector<Constant *, 16> DstElements;
1497 getArrayElements(AVI.DstInit, DstElements);
1499 SmallVector<Constant *, 16> SrcElements;
1500 getArrayElements(AVI.SrcInit, SrcElements);
1502 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
1504 StringRef Name = AVI.NewGV->getName();
1505 bool IsNewStructor =
1506 (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
1507 cast<StructType>(NewType->getElementType())->getNumElements() == 3;
1509 for (auto *V : SrcElements) {
1510 if (IsNewStructor) {
1512 dyn_cast<GlobalValue>(V->getAggregateElement(2)->stripPointerCasts());
1513 if (DoNotLinkFromSource.count(Key))
1516 DstElements.push_back(
1517 MapValue(V, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1519 if (DstElements.size() != NewType->getNumElements()) {
1520 NewType = ArrayType::get(NewType->getElementType(), DstElements.size());
1521 GlobalVariable *Old = AVI.NewGV;
1522 GlobalVariable *NG = new GlobalVariable(
1523 *DstM, NewType, Old->isConstant(), Old->getLinkage(), /*init*/ nullptr,
1524 /*name*/ "", Old, Old->getThreadLocalMode(),
1525 Old->getType()->getAddressSpace());
1526 copyGVAttributes(NG, Old);
1527 AVI.NewGV->replaceAllUsesWith(
1528 ConstantExpr::getBitCast(NG, AVI.NewGV->getType()));
1529 AVI.NewGV->eraseFromParent();
1533 AVI.NewGV->setInitializer(ConstantArray::get(NewType, DstElements));
1536 /// Update the initializers in the Dest module now that all globals that may be
1537 /// referenced are in Dest.
1538 void ModuleLinker::linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src) {
1539 // Figure out what the initializer looks like in the dest module.
1540 Dst.setInitializer(MapValue(Src.getInitializer(), ValueMap,
1541 RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1544 /// Copy the source function over into the dest function and fix up references
1545 /// to values. At this point we know that Dest is an external function, and
1546 /// that Src is not.
1547 bool ModuleLinker::linkFunctionBody(Function &Dst, Function &Src) {
1548 assert(Dst.isDeclaration() && !Src.isDeclaration());
1550 // Materialize if needed.
1551 if (std::error_code EC = Src.materialize())
1552 return emitError(EC.message());
1554 // Link in the prefix data.
1555 if (Src.hasPrefixData())
1556 Dst.setPrefixData(MapValue(Src.getPrefixData(), ValueMap,
1557 RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1559 // Link in the prologue data.
1560 if (Src.hasPrologueData())
1561 Dst.setPrologueData(MapValue(Src.getPrologueData(), ValueMap,
1562 RF_MoveDistinctMDs, &TypeMap,
1565 // Link in the personality function.
1566 if (Src.hasPersonalityFn())
1567 Dst.setPersonalityFn(MapValue(Src.getPersonalityFn(), ValueMap,
1568 RF_MoveDistinctMDs, &TypeMap,
1571 // Go through and convert function arguments over, remembering the mapping.
1572 Function::arg_iterator DI = Dst.arg_begin();
1573 for (Argument &Arg : Src.args()) {
1574 DI->setName(Arg.getName()); // Copy the name over.
1576 // Add a mapping to our mapping.
1577 ValueMap[&Arg] = &*DI;
1581 // Copy over the metadata attachments.
1582 SmallVector<std::pair<unsigned, MDNode *>, 8> MDs;
1583 Src.getAllMetadata(MDs);
1584 for (const auto &I : MDs)
1585 Dst.setMetadata(I.first, MapMetadata(I.second, ValueMap, RF_MoveDistinctMDs,
1586 &TypeMap, &ValMaterializer));
1588 // Splice the body of the source function into the dest function.
1589 Dst.getBasicBlockList().splice(Dst.end(), Src.getBasicBlockList());
1591 // At this point, all of the instructions and values of the function are now
1592 // copied over. The only problem is that they are still referencing values in
1593 // the Source function as operands. Loop through all of the operands of the
1594 // functions and patch them up to point to the local versions.
1595 for (BasicBlock &BB : Dst)
1596 for (Instruction &I : BB)
1597 RemapInstruction(&I, ValueMap,
1598 RF_IgnoreMissingEntries | RF_MoveDistinctMDs, &TypeMap,
1601 // There is no need to map the arguments anymore.
1602 for (Argument &Arg : Src.args())
1603 ValueMap.erase(&Arg);
1605 Src.dematerialize();
1609 void ModuleLinker::linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src) {
1610 Constant *Aliasee = Src.getAliasee();
1611 Constant *Val = MapValue(Aliasee, ValueMap, RF_MoveDistinctMDs, &TypeMap,
1613 Dst.setAliasee(Val);
1616 bool ModuleLinker::linkGlobalValueBody(GlobalValue &Src) {
1617 Value *Dst = ValueMap[&Src];
1619 if (const Comdat *SC = Src.getComdat()) {
1620 // To ensure that we don't generate an incomplete comdat group,
1621 // we must materialize and map in any other members that are not
1622 // yet materialized in Dst, which also ensures their definitions
1623 // are linked in. Otherwise, linkonce and other lazy linked GVs will
1624 // not be materialized if they aren't referenced.
1625 for (auto *SGV : ComdatMembers[SC]) {
1626 auto *DGV = cast_or_null<GlobalValue>(ValueMap[SGV]);
1627 if (DGV && !DGV->isDeclaration())
1629 MapValue(SGV, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer);
1632 if (shouldInternalizeLinkedSymbols())
1633 if (auto *DGV = dyn_cast<GlobalValue>(Dst))
1634 DGV->setLinkage(GlobalValue::InternalLinkage);
1635 if (auto *F = dyn_cast<Function>(&Src))
1636 return linkFunctionBody(cast<Function>(*Dst), *F);
1637 if (auto *GVar = dyn_cast<GlobalVariable>(&Src)) {
1638 linkGlobalInit(cast<GlobalVariable>(*Dst), *GVar);
1641 linkAliasBody(cast<GlobalAlias>(*Dst), cast<GlobalAlias>(Src));
1645 /// Insert all of the named MDNodes in Src into the Dest module.
1646 void ModuleLinker::linkNamedMDNodes() {
1647 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1648 for (const NamedMDNode &NMD : SrcM->named_metadata()) {
1649 // Don't link module flags here. Do them separately.
1650 if (&NMD == SrcModFlags)
1652 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(NMD.getName());
1653 // Add Src elements into Dest node.
1654 for (const MDNode *op : NMD.operands())
1655 DestNMD->addOperand(MapMetadata(
1656 op, ValueMap, RF_MoveDistinctMDs | RF_NullMapMissingGlobalValues,
1657 &TypeMap, &ValMaterializer));
1661 /// Merge the linker flags in Src into the Dest module.
1662 bool ModuleLinker::linkModuleFlagsMetadata() {
1663 // If the source module has no module flags, we are done.
1664 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1665 if (!SrcModFlags) return false;
1667 // If the destination module doesn't have module flags yet, then just copy
1668 // over the source module's flags.
1669 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
1670 if (DstModFlags->getNumOperands() == 0) {
1671 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1672 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1677 // First build a map of the existing module flags and requirements.
1678 DenseMap<MDString *, std::pair<MDNode *, unsigned>> Flags;
1679 SmallSetVector<MDNode*, 16> Requirements;
1680 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1681 MDNode *Op = DstModFlags->getOperand(I);
1682 ConstantInt *Behavior = mdconst::extract<ConstantInt>(Op->getOperand(0));
1683 MDString *ID = cast<MDString>(Op->getOperand(1));
1685 if (Behavior->getZExtValue() == Module::Require) {
1686 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1688 Flags[ID] = std::make_pair(Op, I);
1692 // Merge in the flags from the source module, and also collect its set of
1694 bool HasErr = false;
1695 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1696 MDNode *SrcOp = SrcModFlags->getOperand(I);
1697 ConstantInt *SrcBehavior =
1698 mdconst::extract<ConstantInt>(SrcOp->getOperand(0));
1699 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1702 std::tie(DstOp, DstIndex) = Flags.lookup(ID);
1703 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1705 // If this is a requirement, add it and continue.
1706 if (SrcBehaviorValue == Module::Require) {
1707 // If the destination module does not already have this requirement, add
1709 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1710 DstModFlags->addOperand(SrcOp);
1715 // If there is no existing flag with this ID, just add it.
1717 Flags[ID] = std::make_pair(SrcOp, DstModFlags->getNumOperands());
1718 DstModFlags->addOperand(SrcOp);
1722 // Otherwise, perform a merge.
1723 ConstantInt *DstBehavior =
1724 mdconst::extract<ConstantInt>(DstOp->getOperand(0));
1725 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1727 // If either flag has override behavior, handle it first.
1728 if (DstBehaviorValue == Module::Override) {
1729 // Diagnose inconsistent flags which both have override behavior.
1730 if (SrcBehaviorValue == Module::Override &&
1731 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1732 HasErr |= emitError("linking module flags '" + ID->getString() +
1733 "': IDs have conflicting override values");
1736 } else if (SrcBehaviorValue == Module::Override) {
1737 // Update the destination flag to that of the source.
1738 DstModFlags->setOperand(DstIndex, SrcOp);
1739 Flags[ID].first = SrcOp;
1743 // Diagnose inconsistent merge behavior types.
1744 if (SrcBehaviorValue != DstBehaviorValue) {
1745 HasErr |= emitError("linking module flags '" + ID->getString() +
1746 "': IDs have conflicting behaviors");
1750 auto replaceDstValue = [&](MDNode *New) {
1751 Metadata *FlagOps[] = {DstOp->getOperand(0), ID, New};
1752 MDNode *Flag = MDNode::get(DstM->getContext(), FlagOps);
1753 DstModFlags->setOperand(DstIndex, Flag);
1754 Flags[ID].first = Flag;
1757 // Perform the merge for standard behavior types.
1758 switch (SrcBehaviorValue) {
1759 case Module::Require:
1760 case Module::Override: llvm_unreachable("not possible");
1761 case Module::Error: {
1762 // Emit an error if the values differ.
1763 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1764 HasErr |= emitError("linking module flags '" + ID->getString() +
1765 "': IDs have conflicting values");
1769 case Module::Warning: {
1770 // Emit a warning if the values differ.
1771 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1772 emitWarning("linking module flags '" + ID->getString() +
1773 "': IDs have conflicting values");
1777 case Module::Append: {
1778 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1779 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1780 SmallVector<Metadata *, 8> MDs;
1781 MDs.reserve(DstValue->getNumOperands() + SrcValue->getNumOperands());
1782 MDs.append(DstValue->op_begin(), DstValue->op_end());
1783 MDs.append(SrcValue->op_begin(), SrcValue->op_end());
1785 replaceDstValue(MDNode::get(DstM->getContext(), MDs));
1788 case Module::AppendUnique: {
1789 SmallSetVector<Metadata *, 16> Elts;
1790 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1791 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1792 Elts.insert(DstValue->op_begin(), DstValue->op_end());
1793 Elts.insert(SrcValue->op_begin(), SrcValue->op_end());
1795 replaceDstValue(MDNode::get(DstM->getContext(),
1796 makeArrayRef(Elts.begin(), Elts.end())));
1802 // Check all of the requirements.
1803 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1804 MDNode *Requirement = Requirements[I];
1805 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1806 Metadata *ReqValue = Requirement->getOperand(1);
1808 MDNode *Op = Flags[Flag].first;
1809 if (!Op || Op->getOperand(2) != ReqValue) {
1810 HasErr |= emitError("linking module flags '" + Flag->getString() +
1811 "': does not have the required value");
1819 // This function returns true if the triples match.
1820 static bool triplesMatch(const Triple &T0, const Triple &T1) {
1821 // If vendor is apple, ignore the version number.
1822 if (T0.getVendor() == Triple::Apple)
1823 return T0.getArch() == T1.getArch() &&
1824 T0.getSubArch() == T1.getSubArch() &&
1825 T0.getVendor() == T1.getVendor() &&
1826 T0.getOS() == T1.getOS();
1831 // This function returns the merged triple.
1832 static std::string mergeTriples(const Triple &SrcTriple, const Triple &DstTriple) {
1833 // If vendor is apple, pick the triple with the larger version number.
1834 if (SrcTriple.getVendor() == Triple::Apple)
1835 if (DstTriple.isOSVersionLT(SrcTriple))
1836 return SrcTriple.str();
1838 return DstTriple.str();
1841 bool ModuleLinker::linkIfNeeded(GlobalValue &GV) {
1842 GlobalValue *DGV = getLinkedToGlobal(&GV);
1844 if (shouldLinkOnlyNeeded() && !(DGV && DGV->isDeclaration()))
1847 if (DGV && !GV.hasLocalLinkage()) {
1848 GlobalValue::VisibilityTypes Visibility =
1849 getMinVisibility(DGV->getVisibility(), GV.getVisibility());
1850 DGV->setVisibility(Visibility);
1851 GV.setVisibility(Visibility);
1854 if (const Comdat *SC = GV.getComdat()) {
1856 Comdat::SelectionKind SK;
1857 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1859 DoNotLinkFromSource.insert(&GV);
1864 if (!DGV && !shouldOverrideFromSrc() &&
1865 (GV.hasLocalLinkage() || GV.hasLinkOnceLinkage() ||
1866 GV.hasAvailableExternallyLinkage())) {
1869 MapValue(&GV, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer);
1873 bool ModuleLinker::run() {
1874 assert(DstM && "Null destination module");
1875 assert(SrcM && "Null source module");
1877 // Inherit the target data from the source module if the destination module
1878 // doesn't have one already.
1879 if (DstM->getDataLayout().isDefault())
1880 DstM->setDataLayout(SrcM->getDataLayout());
1882 if (SrcM->getDataLayout() != DstM->getDataLayout()) {
1883 emitWarning("Linking two modules of different data layouts: '" +
1884 SrcM->getModuleIdentifier() + "' is '" +
1885 SrcM->getDataLayoutStr() + "' whereas '" +
1886 DstM->getModuleIdentifier() + "' is '" +
1887 DstM->getDataLayoutStr() + "'\n");
1890 // Copy the target triple from the source to dest if the dest's is empty.
1891 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
1892 DstM->setTargetTriple(SrcM->getTargetTriple());
1894 Triple SrcTriple(SrcM->getTargetTriple()), DstTriple(DstM->getTargetTriple());
1896 if (!SrcM->getTargetTriple().empty() && !triplesMatch(SrcTriple, DstTriple))
1897 emitWarning("Linking two modules of different target triples: " +
1898 SrcM->getModuleIdentifier() + "' is '" +
1899 SrcM->getTargetTriple() + "' whereas '" +
1900 DstM->getModuleIdentifier() + "' is '" +
1901 DstM->getTargetTriple() + "'\n");
1903 DstM->setTargetTriple(mergeTriples(SrcTriple, DstTriple));
1905 // Append the module inline asm string.
1906 if (!SrcM->getModuleInlineAsm().empty()) {
1907 if (DstM->getModuleInlineAsm().empty())
1908 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
1910 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
1911 SrcM->getModuleInlineAsm());
1914 // Loop over all of the linked values to compute type mappings.
1915 computeTypeMapping();
1917 ComdatsChosen.clear();
1918 for (const auto &SMEC : SrcM->getComdatSymbolTable()) {
1919 const Comdat &C = SMEC.getValue();
1920 if (ComdatsChosen.count(&C))
1922 Comdat::SelectionKind SK;
1924 if (getComdatResult(&C, SK, LinkFromSrc))
1926 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1929 // Upgrade mismatched global arrays.
1930 upgradeMismatchedGlobals();
1932 for (GlobalVariable &GV : SrcM->globals())
1933 if (const Comdat *SC = GV.getComdat())
1934 ComdatMembers[SC].push_back(&GV);
1936 for (Function &SF : *SrcM)
1937 if (const Comdat *SC = SF.getComdat())
1938 ComdatMembers[SC].push_back(&SF);
1940 for (GlobalAlias &GA : SrcM->aliases())
1941 if (const Comdat *SC = GA.getComdat())
1942 ComdatMembers[SC].push_back(&GA);
1944 // Insert all of the globals in src into the DstM module... without linking
1945 // initializers (which could refer to functions not yet mapped over).
1946 for (GlobalVariable &GV : SrcM->globals())
1947 if (linkIfNeeded(GV))
1950 for (Function &SF : *SrcM)
1951 if (linkIfNeeded(SF))
1954 for (GlobalAlias &GA : SrcM->aliases())
1955 if (linkIfNeeded(GA))
1958 for (AppendingVarInfo &AppendingVar : AppendingVars)
1959 linkAppendingVarInit(AppendingVar);
1961 for (const auto &Entry : DstM->getComdatSymbolTable()) {
1962 const Comdat &C = Entry.getValue();
1963 if (C.getSelectionKind() == Comdat::Any)
1965 const GlobalValue *GV = SrcM->getNamedValue(C.getName());
1967 MapValue(GV, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer);
1970 // Note that we are done linking global value bodies. This prevents
1971 // metadata linking from creating new references.
1972 DoneLinkingBodies = true;
1974 // Remap all of the named MDNodes in Src into the DstM module. We do this
1975 // after linking GlobalValues so that MDNodes that reference GlobalValues
1976 // are properly remapped.
1979 // Merge the module flags into the DstM module.
1980 if (linkModuleFlagsMetadata())
1986 Linker::StructTypeKeyInfo::KeyTy::KeyTy(ArrayRef<Type *> E, bool P)
1987 : ETypes(E), IsPacked(P) {}
1989 Linker::StructTypeKeyInfo::KeyTy::KeyTy(const StructType *ST)
1990 : ETypes(ST->elements()), IsPacked(ST->isPacked()) {}
1992 bool Linker::StructTypeKeyInfo::KeyTy::operator==(const KeyTy &That) const {
1993 if (IsPacked != That.IsPacked)
1995 if (ETypes != That.ETypes)
2000 bool Linker::StructTypeKeyInfo::KeyTy::operator!=(const KeyTy &That) const {
2001 return !this->operator==(That);
2004 StructType *Linker::StructTypeKeyInfo::getEmptyKey() {
2005 return DenseMapInfo<StructType *>::getEmptyKey();
2008 StructType *Linker::StructTypeKeyInfo::getTombstoneKey() {
2009 return DenseMapInfo<StructType *>::getTombstoneKey();
2012 unsigned Linker::StructTypeKeyInfo::getHashValue(const KeyTy &Key) {
2013 return hash_combine(hash_combine_range(Key.ETypes.begin(), Key.ETypes.end()),
2017 unsigned Linker::StructTypeKeyInfo::getHashValue(const StructType *ST) {
2018 return getHashValue(KeyTy(ST));
2021 bool Linker::StructTypeKeyInfo::isEqual(const KeyTy &LHS,
2022 const StructType *RHS) {
2023 if (RHS == getEmptyKey() || RHS == getTombstoneKey())
2025 return LHS == KeyTy(RHS);
2028 bool Linker::StructTypeKeyInfo::isEqual(const StructType *LHS,
2029 const StructType *RHS) {
2030 if (RHS == getEmptyKey())
2031 return LHS == getEmptyKey();
2033 if (RHS == getTombstoneKey())
2034 return LHS == getTombstoneKey();
2036 return KeyTy(LHS) == KeyTy(RHS);
2039 void Linker::IdentifiedStructTypeSet::addNonOpaque(StructType *Ty) {
2040 assert(!Ty->isOpaque());
2041 NonOpaqueStructTypes.insert(Ty);
2044 void Linker::IdentifiedStructTypeSet::switchToNonOpaque(StructType *Ty) {
2045 assert(!Ty->isOpaque());
2046 NonOpaqueStructTypes.insert(Ty);
2047 bool Removed = OpaqueStructTypes.erase(Ty);
2052 void Linker::IdentifiedStructTypeSet::addOpaque(StructType *Ty) {
2053 assert(Ty->isOpaque());
2054 OpaqueStructTypes.insert(Ty);
2058 Linker::IdentifiedStructTypeSet::findNonOpaque(ArrayRef<Type *> ETypes,
2060 Linker::StructTypeKeyInfo::KeyTy Key(ETypes, IsPacked);
2061 auto I = NonOpaqueStructTypes.find_as(Key);
2062 if (I == NonOpaqueStructTypes.end())
2067 bool Linker::IdentifiedStructTypeSet::hasType(StructType *Ty) {
2069 return OpaqueStructTypes.count(Ty);
2070 auto I = NonOpaqueStructTypes.find(Ty);
2071 if (I == NonOpaqueStructTypes.end())
2076 void Linker::init(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
2077 this->Composite = M;
2078 this->DiagnosticHandler = DiagnosticHandler;
2080 TypeFinder StructTypes;
2081 StructTypes.run(*M, true);
2082 for (StructType *Ty : StructTypes) {
2084 IdentifiedStructTypes.addOpaque(Ty);
2086 IdentifiedStructTypes.addNonOpaque(Ty);
2090 Linker::Linker(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
2091 init(M, DiagnosticHandler);
2094 Linker::Linker(Module *M) {
2095 init(M, [this](const DiagnosticInfo &DI) {
2096 Composite->getContext().diagnose(DI);
2100 void Linker::deleteModule() {
2102 Composite = nullptr;
2105 bool Linker::linkInModule(Module *Src, unsigned Flags,
2106 const FunctionInfoIndex *Index,
2107 Function *FuncToImport) {
2108 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,
2109 DiagnosticHandler, Flags, Index, FuncToImport);
2110 bool RetCode = TheLinker.run();
2111 Composite->dropTriviallyDeadConstantArrays();
2115 void Linker::setModule(Module *Dst) {
2116 init(Dst, DiagnosticHandler);
2119 //===----------------------------------------------------------------------===//
2120 // LinkModules entrypoint.
2121 //===----------------------------------------------------------------------===//
2123 /// This function links two modules together, with the resulting Dest module
2124 /// modified to be the composite of the two input modules. If an error occurs,
2125 /// true is returned and ErrorMsg (if not null) is set to indicate the problem.
2126 /// Upon failure, the Dest module could be in a modified state, and shouldn't be
2127 /// relied on to be consistent.
2128 bool Linker::LinkModules(Module *Dest, Module *Src,
2129 DiagnosticHandlerFunction DiagnosticHandler,
2131 Linker L(Dest, DiagnosticHandler);
2132 return L.linkInModule(Src, Flags);
2135 bool Linker::LinkModules(Module *Dest, Module *Src, unsigned Flags) {
2137 return L.linkInModule(Src, Flags);
2140 //===----------------------------------------------------------------------===//
2142 //===----------------------------------------------------------------------===//
2144 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
2145 LLVMLinkerMode Unused, char **OutMessages) {
2146 Module *D = unwrap(Dest);
2147 std::string Message;
2148 raw_string_ostream Stream(Message);
2149 DiagnosticPrinterRawOStream DP(Stream);
2151 LLVMBool Result = Linker::LinkModules(
2152 D, unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); });
2154 if (OutMessages && Result) {
2156 *OutMessages = strdup(Message.c_str());