1 //===- lib/Linker/LinkModules.cpp - Module Linker Implementation ----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the LLVM module linker.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Linker/Linker.h"
15 #include "llvm-c/Linker.h"
16 #include "llvm/ADT/Hashing.h"
17 #include "llvm/ADT/Optional.h"
18 #include "llvm/ADT/SetVector.h"
19 #include "llvm/ADT/SmallString.h"
20 #include "llvm/ADT/Statistic.h"
21 #include "llvm/ADT/Triple.h"
22 #include "llvm/IR/Constants.h"
23 #include "llvm/IR/DebugInfo.h"
24 #include "llvm/IR/DiagnosticInfo.h"
25 #include "llvm/IR/DiagnosticPrinter.h"
26 #include "llvm/IR/LLVMContext.h"
27 #include "llvm/IR/Module.h"
28 #include "llvm/IR/TypeFinder.h"
29 #include "llvm/Support/CommandLine.h"
30 #include "llvm/Support/Debug.h"
31 #include "llvm/Support/raw_ostream.h"
32 #include "llvm/Transforms/Utils/Cloning.h"
38 //===----------------------------------------------------------------------===//
39 // TypeMap implementation.
40 //===----------------------------------------------------------------------===//
43 class TypeMapTy : public ValueMapTypeRemapper {
44 /// This is a mapping from a source type to a destination type to use.
45 DenseMap<Type*, Type*> MappedTypes;
47 /// When checking to see if two subgraphs are isomorphic, we speculatively
48 /// add types to MappedTypes, but keep track of them here in case we need to
50 SmallVector<Type*, 16> SpeculativeTypes;
52 SmallVector<StructType*, 16> SpeculativeDstOpaqueTypes;
54 /// This is a list of non-opaque structs in the source module that are mapped
55 /// to an opaque struct in the destination module.
56 SmallVector<StructType*, 16> SrcDefinitionsToResolve;
58 /// This is the set of opaque types in the destination modules who are
59 /// getting a body from the source module.
60 SmallPtrSet<StructType*, 16> DstResolvedOpaqueTypes;
63 TypeMapTy(Linker::IdentifiedStructTypeSet &DstStructTypesSet)
64 : DstStructTypesSet(DstStructTypesSet) {}
66 Linker::IdentifiedStructTypeSet &DstStructTypesSet;
67 /// Indicate that the specified type in the destination module is conceptually
68 /// equivalent to the specified type in the source module.
69 void addTypeMapping(Type *DstTy, Type *SrcTy);
71 /// Produce a body for an opaque type in the dest module from a type
72 /// definition in the source module.
73 void linkDefinedTypeBodies();
75 /// Return the mapped type to use for the specified input type from the
77 Type *get(Type *SrcTy);
78 Type *get(Type *SrcTy, SmallPtrSet<StructType *, 8> &Visited);
80 void finishType(StructType *DTy, StructType *STy, ArrayRef<Type *> ETypes);
82 FunctionType *get(FunctionType *T) {
83 return cast<FunctionType>(get((Type *)T));
86 /// Dump out the type map for debugging purposes.
88 for (auto &Pair : MappedTypes) {
89 dbgs() << "TypeMap: ";
90 Pair.first->print(dbgs());
92 Pair.second->print(dbgs());
98 Type *remapType(Type *SrcTy) override { return get(SrcTy); }
100 bool areTypesIsomorphic(Type *DstTy, Type *SrcTy);
104 void TypeMapTy::addTypeMapping(Type *DstTy, Type *SrcTy) {
105 assert(SpeculativeTypes.empty());
106 assert(SpeculativeDstOpaqueTypes.empty());
108 // Check to see if these types are recursively isomorphic and establish a
109 // mapping between them if so.
110 if (!areTypesIsomorphic(DstTy, SrcTy)) {
111 // Oops, they aren't isomorphic. Just discard this request by rolling out
112 // any speculative mappings we've established.
113 for (Type *Ty : SpeculativeTypes)
114 MappedTypes.erase(Ty);
116 SrcDefinitionsToResolve.resize(SrcDefinitionsToResolve.size() -
117 SpeculativeDstOpaqueTypes.size());
118 for (StructType *Ty : SpeculativeDstOpaqueTypes)
119 DstResolvedOpaqueTypes.erase(Ty);
121 for (Type *Ty : SpeculativeTypes)
122 if (auto *STy = dyn_cast<StructType>(Ty))
126 SpeculativeTypes.clear();
127 SpeculativeDstOpaqueTypes.clear();
130 /// Recursively walk this pair of types, returning true if they are isomorphic,
131 /// false if they are not.
132 bool TypeMapTy::areTypesIsomorphic(Type *DstTy, Type *SrcTy) {
133 // Two types with differing kinds are clearly not isomorphic.
134 if (DstTy->getTypeID() != SrcTy->getTypeID())
137 // If we have an entry in the MappedTypes table, then we have our answer.
138 Type *&Entry = MappedTypes[SrcTy];
140 return Entry == DstTy;
142 // Two identical types are clearly isomorphic. Remember this
143 // non-speculatively.
144 if (DstTy == SrcTy) {
149 // Okay, we have two types with identical kinds that we haven't seen before.
151 // If this is an opaque struct type, special case it.
152 if (StructType *SSTy = dyn_cast<StructType>(SrcTy)) {
153 // Mapping an opaque type to any struct, just keep the dest struct.
154 if (SSTy->isOpaque()) {
156 SpeculativeTypes.push_back(SrcTy);
160 // Mapping a non-opaque source type to an opaque dest. If this is the first
161 // type that we're mapping onto this destination type then we succeed. Keep
162 // the dest, but fill it in later. If this is the second (different) type
163 // that we're trying to map onto the same opaque type then we fail.
164 if (cast<StructType>(DstTy)->isOpaque()) {
165 // We can only map one source type onto the opaque destination type.
166 if (!DstResolvedOpaqueTypes.insert(cast<StructType>(DstTy)).second)
168 SrcDefinitionsToResolve.push_back(SSTy);
169 SpeculativeTypes.push_back(SrcTy);
170 SpeculativeDstOpaqueTypes.push_back(cast<StructType>(DstTy));
176 // If the number of subtypes disagree between the two types, then we fail.
177 if (SrcTy->getNumContainedTypes() != DstTy->getNumContainedTypes())
180 // Fail if any of the extra properties (e.g. array size) of the type disagree.
181 if (isa<IntegerType>(DstTy))
182 return false; // bitwidth disagrees.
183 if (PointerType *PT = dyn_cast<PointerType>(DstTy)) {
184 if (PT->getAddressSpace() != cast<PointerType>(SrcTy)->getAddressSpace())
187 } else if (FunctionType *FT = dyn_cast<FunctionType>(DstTy)) {
188 if (FT->isVarArg() != cast<FunctionType>(SrcTy)->isVarArg())
190 } else if (StructType *DSTy = dyn_cast<StructType>(DstTy)) {
191 StructType *SSTy = cast<StructType>(SrcTy);
192 if (DSTy->isLiteral() != SSTy->isLiteral() ||
193 DSTy->isPacked() != SSTy->isPacked())
195 } else if (ArrayType *DATy = dyn_cast<ArrayType>(DstTy)) {
196 if (DATy->getNumElements() != cast<ArrayType>(SrcTy)->getNumElements())
198 } else if (VectorType *DVTy = dyn_cast<VectorType>(DstTy)) {
199 if (DVTy->getNumElements() != cast<VectorType>(SrcTy)->getNumElements())
203 // Otherwise, we speculate that these two types will line up and recursively
204 // check the subelements.
206 SpeculativeTypes.push_back(SrcTy);
208 for (unsigned I = 0, E = SrcTy->getNumContainedTypes(); I != E; ++I)
209 if (!areTypesIsomorphic(DstTy->getContainedType(I),
210 SrcTy->getContainedType(I)))
213 // If everything seems to have lined up, then everything is great.
217 void TypeMapTy::linkDefinedTypeBodies() {
218 SmallVector<Type*, 16> Elements;
219 for (StructType *SrcSTy : SrcDefinitionsToResolve) {
220 StructType *DstSTy = cast<StructType>(MappedTypes[SrcSTy]);
221 assert(DstSTy->isOpaque());
223 // Map the body of the source type over to a new body for the dest type.
224 Elements.resize(SrcSTy->getNumElements());
225 for (unsigned I = 0, E = Elements.size(); I != E; ++I)
226 Elements[I] = get(SrcSTy->getElementType(I));
228 DstSTy->setBody(Elements, SrcSTy->isPacked());
229 DstStructTypesSet.switchToNonOpaque(DstSTy);
231 SrcDefinitionsToResolve.clear();
232 DstResolvedOpaqueTypes.clear();
235 void TypeMapTy::finishType(StructType *DTy, StructType *STy,
236 ArrayRef<Type *> ETypes) {
237 DTy->setBody(ETypes, STy->isPacked());
240 if (STy->hasName()) {
241 SmallString<16> TmpName = STy->getName();
243 DTy->setName(TmpName);
246 DstStructTypesSet.addNonOpaque(DTy);
249 Type *TypeMapTy::get(Type *Ty) {
250 SmallPtrSet<StructType *, 8> Visited;
251 return get(Ty, Visited);
254 Type *TypeMapTy::get(Type *Ty, SmallPtrSet<StructType *, 8> &Visited) {
255 // If we already have an entry for this type, return it.
256 Type **Entry = &MappedTypes[Ty];
260 // These are types that LLVM itself will unique.
261 bool IsUniqued = !isa<StructType>(Ty) || cast<StructType>(Ty)->isLiteral();
265 for (auto &Pair : MappedTypes) {
266 assert(!(Pair.first != Ty && Pair.second == Ty) &&
267 "mapping to a source type");
272 if (!IsUniqued && !Visited.insert(cast<StructType>(Ty)).second) {
273 StructType *DTy = StructType::create(Ty->getContext());
277 // If this is not a recursive type, then just map all of the elements and
278 // then rebuild the type from inside out.
279 SmallVector<Type *, 4> ElementTypes;
281 // If there are no element types to map, then the type is itself. This is
282 // true for the anonymous {} struct, things like 'float', integers, etc.
283 if (Ty->getNumContainedTypes() == 0 && IsUniqued)
286 // Remap all of the elements, keeping track of whether any of them change.
287 bool AnyChange = false;
288 ElementTypes.resize(Ty->getNumContainedTypes());
289 for (unsigned I = 0, E = Ty->getNumContainedTypes(); I != E; ++I) {
290 ElementTypes[I] = get(Ty->getContainedType(I), Visited);
291 AnyChange |= ElementTypes[I] != Ty->getContainedType(I);
294 // If we found our type while recursively processing stuff, just use it.
295 Entry = &MappedTypes[Ty];
297 if (auto *DTy = dyn_cast<StructType>(*Entry)) {
298 if (DTy->isOpaque()) {
299 auto *STy = cast<StructType>(Ty);
300 finishType(DTy, STy, ElementTypes);
306 // If all of the element types mapped directly over and the type is not
307 // a nomed struct, then the type is usable as-is.
308 if (!AnyChange && IsUniqued)
311 // Otherwise, rebuild a modified type.
312 switch (Ty->getTypeID()) {
314 llvm_unreachable("unknown derived type to remap");
315 case Type::ArrayTyID:
316 return *Entry = ArrayType::get(ElementTypes[0],
317 cast<ArrayType>(Ty)->getNumElements());
318 case Type::VectorTyID:
319 return *Entry = VectorType::get(ElementTypes[0],
320 cast<VectorType>(Ty)->getNumElements());
321 case Type::PointerTyID:
322 return *Entry = PointerType::get(ElementTypes[0],
323 cast<PointerType>(Ty)->getAddressSpace());
324 case Type::FunctionTyID:
325 return *Entry = FunctionType::get(ElementTypes[0],
326 makeArrayRef(ElementTypes).slice(1),
327 cast<FunctionType>(Ty)->isVarArg());
328 case Type::StructTyID: {
329 auto *STy = cast<StructType>(Ty);
330 bool IsPacked = STy->isPacked();
332 return *Entry = StructType::get(Ty->getContext(), ElementTypes, IsPacked);
334 // If the type is opaque, we can just use it directly.
335 if (STy->isOpaque()) {
336 DstStructTypesSet.addOpaque(STy);
340 if (StructType *OldT =
341 DstStructTypesSet.findNonOpaque(ElementTypes, IsPacked)) {
343 return *Entry = OldT;
347 DstStructTypesSet.addNonOpaque(STy);
351 StructType *DTy = StructType::create(Ty->getContext());
352 finishType(DTy, STy, ElementTypes);
358 //===----------------------------------------------------------------------===//
359 // ModuleLinker implementation.
360 //===----------------------------------------------------------------------===//
365 /// Creates prototypes for functions that are lazily linked on the fly. This
366 /// speeds up linking for modules with many/ lazily linked functions of which
368 class ValueMaterializerTy final : public ValueMaterializer {
371 std::vector<GlobalValue *> &LazilyLinkGlobalValues;
372 ModuleLinker *ModLinker;
375 ValueMaterializerTy(TypeMapTy &TypeMap, Module *DstM,
376 std::vector<GlobalValue *> &LazilyLinkGlobalValues,
377 ModuleLinker *ModLinker)
378 : ValueMaterializer(), TypeMap(TypeMap), DstM(DstM),
379 LazilyLinkGlobalValues(LazilyLinkGlobalValues), ModLinker(ModLinker) {}
381 Value *materializeValueFor(Value *V) override;
384 class LinkDiagnosticInfo : public DiagnosticInfo {
388 LinkDiagnosticInfo(DiagnosticSeverity Severity, const Twine &Msg);
389 void print(DiagnosticPrinter &DP) const override;
391 LinkDiagnosticInfo::LinkDiagnosticInfo(DiagnosticSeverity Severity,
393 : DiagnosticInfo(DK_Linker, Severity), Msg(Msg) {}
394 void LinkDiagnosticInfo::print(DiagnosticPrinter &DP) const { DP << Msg; }
396 /// This is an implementation class for the LinkModules function, which is the
397 /// entrypoint for this file.
402 ValueMaterializerTy ValMaterializer;
404 /// Mapping of values from what they used to be in Src, to what they are now
405 /// in DstM. ValueToValueMapTy is a ValueMap, which involves some overhead
406 /// due to the use of Value handles which the Linker doesn't actually need,
407 /// but this allows us to reuse the ValueMapper code.
408 ValueToValueMapTy ValueMap;
410 struct AppendingVarInfo {
411 GlobalVariable *NewGV; // New aggregate global in dest module.
412 const Constant *DstInit; // Old initializer from dest module.
413 const Constant *SrcInit; // Old initializer from src module.
416 std::vector<AppendingVarInfo> AppendingVars;
418 // Set of items not to link in from source.
419 SmallPtrSet<const Value *, 16> DoNotLinkFromSource;
421 // Vector of GlobalValues to lazily link in.
422 std::vector<GlobalValue *> LazilyLinkGlobalValues;
424 DiagnosticHandlerFunction DiagnosticHandler;
426 /// For symbol clashes, prefer those from Src.
429 /// Function index passed into ModuleLinker for using in function
430 /// importing/exporting handling.
431 const FunctionInfoIndex *ImportIndex;
433 /// Function to import from source module, all other functions are
434 /// imported as declarations instead of definitions.
435 Function *ImportFunction;
437 /// Set to true if the given FunctionInfoIndex contains any functions
438 /// from this source module, in which case we must conservatively assume
439 /// that any of its functions may be imported into another module
440 /// as part of a different backend compilation process.
441 bool HasExportedFunctions;
443 /// Set to true when all global value body linking is complete (including
444 /// lazy linking). Used to prevent metadata linking from creating new
446 bool DoneLinkingBodies;
449 ModuleLinker(Module *dstM, Linker::IdentifiedStructTypeSet &Set, Module *srcM,
450 DiagnosticHandlerFunction DiagnosticHandler, unsigned Flags,
451 const FunctionInfoIndex *Index = nullptr,
452 Function *FuncToImport = nullptr)
453 : DstM(dstM), SrcM(srcM), TypeMap(Set),
454 ValMaterializer(TypeMap, DstM, LazilyLinkGlobalValues, this),
455 DiagnosticHandler(DiagnosticHandler), Flags(Flags), ImportIndex(Index),
456 ImportFunction(FuncToImport), HasExportedFunctions(false),
457 DoneLinkingBodies(false) {
458 assert((ImportIndex || !ImportFunction) &&
459 "Expect a FunctionInfoIndex when importing");
460 // If we have a FunctionInfoIndex but no function to import,
461 // then this is the primary module being compiled in a ThinLTO
462 // backend compilation, and we need to see if it has functions that
463 // may be exported to another backend compilation.
464 if (ImportIndex && !ImportFunction)
465 HasExportedFunctions = ImportIndex->hasExportedFunctions(SrcM);
470 bool shouldOverrideFromSrc() { return Flags & Linker::OverrideFromSrc; }
471 bool shouldLinkOnlyNeeded() { return Flags & Linker::LinkOnlyNeeded; }
472 bool shouldInternalizeLinkedSymbols() {
473 return Flags & Linker::InternalizeLinkedSymbols;
476 /// Handles cloning of a global values from the source module into
477 /// the destination module, including setting the attributes and visibility.
478 GlobalValue *copyGlobalValueProto(TypeMapTy &TypeMap, const GlobalValue *SGV,
479 const GlobalValue *DGV = nullptr);
481 /// Check if we should promote the given local value to global scope.
482 bool doPromoteLocalToGlobal(const GlobalValue *SGV);
484 /// Check if all global value body linking is complete.
485 bool doneLinkingBodies() { return DoneLinkingBodies; }
488 bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
489 const GlobalValue &Src);
491 /// Helper method for setting a message and returning an error code.
492 bool emitError(const Twine &Message) {
493 DiagnosticHandler(LinkDiagnosticInfo(DS_Error, Message));
497 void emitWarning(const Twine &Message) {
498 DiagnosticHandler(LinkDiagnosticInfo(DS_Warning, Message));
501 bool getComdatLeader(Module *M, StringRef ComdatName,
502 const GlobalVariable *&GVar);
503 bool computeResultingSelectionKind(StringRef ComdatName,
504 Comdat::SelectionKind Src,
505 Comdat::SelectionKind Dst,
506 Comdat::SelectionKind &Result,
508 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
510 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
512 // Keep track of the global value members of each comdat in source.
513 DenseMap<const Comdat *, std::vector<GlobalValue *>> ComdatMembers;
515 /// Given a global in the source module, return the global in the
516 /// destination module that is being linked to, if any.
517 GlobalValue *getLinkedToGlobal(const GlobalValue *SrcGV) {
518 // If the source has no name it can't link. If it has local linkage,
519 // there is no name match-up going on.
520 if (!SrcGV->hasName() || GlobalValue::isLocalLinkage(getLinkage(SrcGV)))
523 // Otherwise see if we have a match in the destination module's symtab.
524 GlobalValue *DGV = DstM->getNamedValue(getName(SrcGV));
528 // If we found a global with the same name in the dest module, but it has
529 // internal linkage, we are really not doing any linkage here.
530 if (DGV->hasLocalLinkage())
533 // Otherwise, we do in fact link to the destination global.
537 void computeTypeMapping();
539 void upgradeMismatchedGlobalArray(StringRef Name);
540 void upgradeMismatchedGlobals();
542 bool linkAppendingVarProto(GlobalVariable *DstGV,
543 const GlobalVariable *SrcGV);
545 bool linkGlobalValueProto(GlobalValue *GV);
546 bool linkModuleFlagsMetadata();
548 void linkAppendingVarInit(const AppendingVarInfo &AVI);
550 void linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src);
551 bool linkFunctionBody(Function &Dst, Function &Src);
552 void linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src);
553 bool linkGlobalValueBody(GlobalValue &Src);
555 /// Functions that take care of cloning a specific global value type
556 /// into the destination module.
557 GlobalVariable *copyGlobalVariableProto(TypeMapTy &TypeMap,
558 const GlobalVariable *SGVar);
559 Function *copyFunctionProto(TypeMapTy &TypeMap, const Function *SF);
560 GlobalValue *copyGlobalAliasProto(TypeMapTy &TypeMap, const GlobalAlias *SGA);
562 /// Helper methods to check if we are importing from or potentially
563 /// exporting from the current source module.
564 bool isPerformingImport() { return ImportFunction != nullptr; }
565 bool isModuleExporting() { return HasExportedFunctions; }
567 /// If we are importing from the source module, checks if we should
568 /// import SGV as a definition, otherwise import as a declaration.
569 bool doImportAsDefinition(const GlobalValue *SGV);
571 /// Get the name for SGV that should be used in the linked destination
572 /// module. Specifically, this handles the case where we need to rename
573 /// a local that is being promoted to global scope.
574 std::string getName(const GlobalValue *SGV);
576 /// Get the new linkage for SGV that should be used in the linked destination
577 /// module. Specifically, for ThinLTO importing or exporting it may need
579 GlobalValue::LinkageTypes getLinkage(const GlobalValue *SGV);
581 /// Copies the necessary global value attributes and name from the source
582 /// to the newly cloned global value.
583 void copyGVAttributes(GlobalValue *NewGV, const GlobalValue *SrcGV);
585 /// Updates the visibility for the new global cloned from the source
586 /// and, if applicable, linked with an existing destination global.
587 /// Handles visibility change required for promoted locals.
588 void setVisibility(GlobalValue *NewGV, const GlobalValue *SGV,
589 const GlobalValue *DGV = nullptr);
591 void linkNamedMDNodes();
595 /// The LLVM SymbolTable class autorenames globals that conflict in the symbol
596 /// table. This is good for all clients except for us. Go through the trouble
597 /// to force this back.
598 static void forceRenaming(GlobalValue *GV, StringRef Name) {
599 // If the global doesn't force its name or if it already has the right name,
600 // there is nothing for us to do.
601 // Note that any required local to global promotion should already be done,
602 // so promoted locals will not skip this handling as their linkage is no
604 if (GV->hasLocalLinkage() || GV->getName() == Name)
607 Module *M = GV->getParent();
609 // If there is a conflict, rename the conflict.
610 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
611 GV->takeName(ConflictGV);
612 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
613 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
615 GV->setName(Name); // Force the name back
619 /// copy additional attributes (those not needed to construct a GlobalValue)
620 /// from the SrcGV to the DestGV.
621 void ModuleLinker::copyGVAttributes(GlobalValue *NewGV,
622 const GlobalValue *SrcGV) {
623 auto *GA = dyn_cast<GlobalAlias>(SrcGV);
624 // Check for the special case of converting an alias (definition) to a
625 // non-alias (declaration). This can happen when we are importing and
626 // encounter a weak_any alias (weak_any defs may not be imported, see
627 // comments in ModuleLinker::getLinkage) or an alias whose base object is
628 // being imported as a declaration. In that case copy the attributes from the
630 if (GA && !dyn_cast<GlobalAlias>(NewGV)) {
631 assert(isPerformingImport() && !doImportAsDefinition(GA));
632 NewGV->copyAttributesFrom(GA->getBaseObject());
634 NewGV->copyAttributesFrom(SrcGV);
635 forceRenaming(NewGV, getName(SrcGV));
638 static bool isLessConstraining(GlobalValue::VisibilityTypes a,
639 GlobalValue::VisibilityTypes b) {
640 if (a == GlobalValue::HiddenVisibility)
642 if (b == GlobalValue::HiddenVisibility)
644 if (a == GlobalValue::ProtectedVisibility)
646 if (b == GlobalValue::ProtectedVisibility)
651 bool ModuleLinker::doImportAsDefinition(const GlobalValue *SGV) {
652 if (!isPerformingImport())
654 auto *GA = dyn_cast<GlobalAlias>(SGV);
656 if (GA->hasWeakAnyLinkage())
658 const GlobalObject *GO = GA->getBaseObject();
659 if (!GO->hasLinkOnceODRLinkage())
661 return doImportAsDefinition(GO);
663 // Always import GlobalVariable definitions, except for the special
664 // case of WeakAny which are imported as ExternalWeak declarations
665 // (see comments in ModuleLinker::getLinkage). The linkage changes
666 // described in ModuleLinker::getLinkage ensure the correct behavior (e.g.
667 // global variables with external linkage are transformed to
668 // available_externally definitions, which are ultimately turned into
669 // declarations after the EliminateAvailableExternally pass).
670 if (isa<GlobalVariable>(SGV) && !SGV->isDeclaration() &&
671 !SGV->hasWeakAnyLinkage())
673 // Only import the function requested for importing.
674 auto *SF = dyn_cast<Function>(SGV);
675 if (SF && SF == ImportFunction)
681 bool ModuleLinker::doPromoteLocalToGlobal(const GlobalValue *SGV) {
682 assert(SGV->hasLocalLinkage());
683 // Both the imported references and the original local variable must
685 if (!isPerformingImport() && !isModuleExporting())
688 // Local const variables never need to be promoted unless they are address
689 // taken. The imported uses can simply use the clone created in this module.
690 // For now we are conservative in determining which variables are not
691 // address taken by checking the unnamed addr flag. To be more aggressive,
692 // the address taken information must be checked earlier during parsing
693 // of the module and recorded in the function index for use when importing
695 auto *GVar = dyn_cast<GlobalVariable>(SGV);
696 if (GVar && GVar->isConstant() && GVar->hasUnnamedAddr())
699 // Eventually we only need to promote functions in the exporting module that
700 // are referenced by a potentially exported function (i.e. one that is in the
705 std::string ModuleLinker::getName(const GlobalValue *SGV) {
706 // For locals that must be promoted to global scope, ensure that
707 // the promoted name uniquely identifies the copy in the original module,
708 // using the ID assigned during combined index creation. When importing,
709 // we rename all locals (not just those that are promoted) in order to
710 // avoid naming conflicts between locals imported from different modules.
711 if (SGV->hasLocalLinkage() &&
712 (doPromoteLocalToGlobal(SGV) || isPerformingImport()))
713 return FunctionInfoIndex::getGlobalNameForLocal(
715 ImportIndex->getModuleId(SGV->getParent()->getModuleIdentifier()));
716 return SGV->getName();
719 GlobalValue::LinkageTypes ModuleLinker::getLinkage(const GlobalValue *SGV) {
720 // Any local variable that is referenced by an exported function needs
721 // to be promoted to global scope. Since we don't currently know which
722 // functions reference which local variables/functions, we must treat
723 // all as potentially exported if this module is exporting anything.
724 if (isModuleExporting()) {
725 if (SGV->hasLocalLinkage() && doPromoteLocalToGlobal(SGV))
726 return GlobalValue::ExternalLinkage;
727 return SGV->getLinkage();
730 // Otherwise, if we aren't importing, no linkage change is needed.
731 if (!isPerformingImport())
732 return SGV->getLinkage();
734 switch (SGV->getLinkage()) {
735 case GlobalValue::ExternalLinkage:
736 // External defnitions are converted to available_externally
737 // definitions upon import, so that they are available for inlining
738 // and/or optimization, but are turned into declarations later
739 // during the EliminateAvailableExternally pass.
740 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
741 return GlobalValue::AvailableExternallyLinkage;
742 // An imported external declaration stays external.
743 return SGV->getLinkage();
745 case GlobalValue::AvailableExternallyLinkage:
746 // An imported available_externally definition converts
747 // to external if imported as a declaration.
748 if (!doImportAsDefinition(SGV))
749 return GlobalValue::ExternalLinkage;
750 // An imported available_externally declaration stays that way.
751 return SGV->getLinkage();
753 case GlobalValue::LinkOnceAnyLinkage:
754 case GlobalValue::LinkOnceODRLinkage:
755 // These both stay the same when importing the definition.
756 // The ThinLTO pass will eventually force-import their definitions.
757 return SGV->getLinkage();
759 case GlobalValue::WeakAnyLinkage:
760 // Can't import weak_any definitions correctly, or we might change the
761 // program semantics, since the linker will pick the first weak_any
762 // definition and importing would change the order they are seen by the
763 // linker. The module linking caller needs to enforce this.
764 assert(!doImportAsDefinition(SGV));
765 // If imported as a declaration, it becomes external_weak.
766 return GlobalValue::ExternalWeakLinkage;
768 case GlobalValue::WeakODRLinkage:
769 // For weak_odr linkage, there is a guarantee that all copies will be
770 // equivalent, so the issue described above for weak_any does not exist,
771 // and the definition can be imported. It can be treated similarly
772 // to an imported externally visible global value.
773 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
774 return GlobalValue::AvailableExternallyLinkage;
776 return GlobalValue::ExternalLinkage;
778 case GlobalValue::AppendingLinkage:
779 // It would be incorrect to import an appending linkage variable,
780 // since it would cause global constructors/destructors to be
781 // executed multiple times. This should have already been handled
782 // by linkGlobalValueProto.
783 llvm_unreachable("Cannot import appending linkage variable");
785 case GlobalValue::InternalLinkage:
786 case GlobalValue::PrivateLinkage:
787 // If we are promoting the local to global scope, it is handled
788 // similarly to a normal externally visible global.
789 if (doPromoteLocalToGlobal(SGV)) {
790 if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
791 return GlobalValue::AvailableExternallyLinkage;
793 return GlobalValue::ExternalLinkage;
795 // A non-promoted imported local definition stays local.
796 // The ThinLTO pass will eventually force-import their definitions.
797 return SGV->getLinkage();
799 case GlobalValue::ExternalWeakLinkage:
800 // External weak doesn't apply to definitions, must be a declaration.
801 assert(!doImportAsDefinition(SGV));
802 // Linkage stays external_weak.
803 return SGV->getLinkage();
805 case GlobalValue::CommonLinkage:
806 // Linkage stays common on definitions.
807 // The ThinLTO pass will eventually force-import their definitions.
808 return SGV->getLinkage();
811 llvm_unreachable("unknown linkage type");
814 /// Loop through the global variables in the src module and merge them into the
817 ModuleLinker::copyGlobalVariableProto(TypeMapTy &TypeMap,
818 const GlobalVariable *SGVar) {
819 // No linking to be performed or linking from the source: simply create an
820 // identical version of the symbol over in the dest module... the
821 // initializer will be filled in later by LinkGlobalInits.
822 GlobalVariable *NewDGV = new GlobalVariable(
823 *DstM, TypeMap.get(SGVar->getType()->getElementType()),
824 SGVar->isConstant(), getLinkage(SGVar), /*init*/ nullptr, getName(SGVar),
825 /*insertbefore*/ nullptr, SGVar->getThreadLocalMode(),
826 SGVar->getType()->getAddressSpace());
831 /// Link the function in the source module into the destination module if
832 /// needed, setting up mapping information.
833 Function *ModuleLinker::copyFunctionProto(TypeMapTy &TypeMap,
834 const Function *SF) {
835 // If there is no linkage to be performed or we are linking from the source,
837 return Function::Create(TypeMap.get(SF->getFunctionType()), getLinkage(SF),
841 /// Set up prototypes for any aliases that come over from the source module.
842 GlobalValue *ModuleLinker::copyGlobalAliasProto(TypeMapTy &TypeMap,
843 const GlobalAlias *SGA) {
844 // If we are importing and encounter a weak_any alias, or an alias to
845 // an object being imported as a declaration, we must import the alias
846 // as a declaration as well, which involves converting it to a non-alias.
847 // See comments in ModuleLinker::getLinkage for why we cannot import
848 // weak_any defintions.
849 if (isPerformingImport() && !doImportAsDefinition(SGA)) {
850 // Need to convert to declaration. All aliases must be definitions.
851 const GlobalValue *GVal = SGA->getBaseObject();
853 if (auto *GVar = dyn_cast<GlobalVariable>(GVal))
854 NewGV = copyGlobalVariableProto(TypeMap, GVar);
856 auto *F = dyn_cast<Function>(GVal);
858 NewGV = copyFunctionProto(TypeMap, F);
860 // Set the linkage to External or ExternalWeak (see comments in
861 // ModuleLinker::getLinkage for why WeakAny is converted to ExternalWeak).
862 if (SGA->hasWeakAnyLinkage())
863 NewGV->setLinkage(GlobalValue::ExternalWeakLinkage);
865 NewGV->setLinkage(GlobalValue::ExternalLinkage);
868 // If there is no linkage to be performed or we're linking from the source,
870 auto *Ty = TypeMap.get(SGA->getValueType());
871 return GlobalAlias::create(Ty, SGA->getType()->getPointerAddressSpace(),
872 getLinkage(SGA), getName(SGA), DstM);
875 void ModuleLinker::setVisibility(GlobalValue *NewGV, const GlobalValue *SGV,
876 const GlobalValue *DGV) {
877 GlobalValue::VisibilityTypes Visibility = SGV->getVisibility();
879 Visibility = isLessConstraining(Visibility, DGV->getVisibility())
880 ? DGV->getVisibility()
882 // For promoted locals, mark them hidden so that they can later be
883 // stripped from the symbol table to reduce bloat.
884 if (SGV->hasLocalLinkage() && doPromoteLocalToGlobal(SGV))
885 Visibility = GlobalValue::HiddenVisibility;
886 NewGV->setVisibility(Visibility);
889 GlobalValue *ModuleLinker::copyGlobalValueProto(TypeMapTy &TypeMap,
890 const GlobalValue *SGV,
891 const GlobalValue *DGV) {
893 if (auto *SGVar = dyn_cast<GlobalVariable>(SGV))
894 NewGV = copyGlobalVariableProto(TypeMap, SGVar);
895 else if (auto *SF = dyn_cast<Function>(SGV))
896 NewGV = copyFunctionProto(TypeMap, SF);
898 NewGV = copyGlobalAliasProto(TypeMap, cast<GlobalAlias>(SGV));
899 copyGVAttributes(NewGV, SGV);
900 setVisibility(NewGV, SGV, DGV);
904 Value *ValueMaterializerTy::materializeValueFor(Value *V) {
905 auto *SGV = dyn_cast<GlobalValue>(V);
909 // If we are done linking global value bodies (i.e. we are performing
910 // metadata linking), don't link in the global value due to this
911 // reference, simply map it to null.
912 if (ModLinker->doneLinkingBodies())
915 GlobalValue *DGV = ModLinker->copyGlobalValueProto(TypeMap, SGV);
917 if (Comdat *SC = SGV->getComdat()) {
918 if (auto *DGO = dyn_cast<GlobalObject>(DGV)) {
919 Comdat *DC = DstM->getOrInsertComdat(SC->getName());
924 LazilyLinkGlobalValues.push_back(SGV);
928 bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName,
929 const GlobalVariable *&GVar) {
930 const GlobalValue *GVal = M->getNamedValue(ComdatName);
931 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
932 GVal = GA->getBaseObject();
934 // We cannot resolve the size of the aliasee yet.
935 return emitError("Linking COMDATs named '" + ComdatName +
936 "': COMDAT key involves incomputable alias size.");
939 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
942 "Linking COMDATs named '" + ComdatName +
943 "': GlobalVariable required for data dependent selection!");
948 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
949 Comdat::SelectionKind Src,
950 Comdat::SelectionKind Dst,
951 Comdat::SelectionKind &Result,
953 // The ability to mix Comdat::SelectionKind::Any with
954 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
955 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
956 Dst == Comdat::SelectionKind::Largest;
957 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
958 Src == Comdat::SelectionKind::Largest;
959 if (DstAnyOrLargest && SrcAnyOrLargest) {
960 if (Dst == Comdat::SelectionKind::Largest ||
961 Src == Comdat::SelectionKind::Largest)
962 Result = Comdat::SelectionKind::Largest;
964 Result = Comdat::SelectionKind::Any;
965 } else if (Src == Dst) {
968 return emitError("Linking COMDATs named '" + ComdatName +
969 "': invalid selection kinds!");
973 case Comdat::SelectionKind::Any:
977 case Comdat::SelectionKind::NoDuplicates:
978 return emitError("Linking COMDATs named '" + ComdatName +
979 "': noduplicates has been violated!");
980 case Comdat::SelectionKind::ExactMatch:
981 case Comdat::SelectionKind::Largest:
982 case Comdat::SelectionKind::SameSize: {
983 const GlobalVariable *DstGV;
984 const GlobalVariable *SrcGV;
985 if (getComdatLeader(DstM, ComdatName, DstGV) ||
986 getComdatLeader(SrcM, ComdatName, SrcGV))
989 const DataLayout &DstDL = DstM->getDataLayout();
990 const DataLayout &SrcDL = SrcM->getDataLayout();
992 DstDL.getTypeAllocSize(DstGV->getType()->getPointerElementType());
994 SrcDL.getTypeAllocSize(SrcGV->getType()->getPointerElementType());
995 if (Result == Comdat::SelectionKind::ExactMatch) {
996 if (SrcGV->getInitializer() != DstGV->getInitializer())
997 return emitError("Linking COMDATs named '" + ComdatName +
998 "': ExactMatch violated!");
1000 } else if (Result == Comdat::SelectionKind::Largest) {
1001 LinkFromSrc = SrcSize > DstSize;
1002 } else if (Result == Comdat::SelectionKind::SameSize) {
1003 if (SrcSize != DstSize)
1004 return emitError("Linking COMDATs named '" + ComdatName +
1005 "': SameSize violated!");
1006 LinkFromSrc = false;
1008 llvm_unreachable("unknown selection kind");
1017 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
1018 Comdat::SelectionKind &Result,
1019 bool &LinkFromSrc) {
1020 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
1021 StringRef ComdatName = SrcC->getName();
1022 Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable();
1023 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
1025 if (DstCI == ComdatSymTab.end()) {
1026 // Use the comdat if it is only available in one of the modules.
1032 const Comdat *DstC = &DstCI->second;
1033 Comdat::SelectionKind DSK = DstC->getSelectionKind();
1034 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
1038 bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
1039 const GlobalValue &Dest,
1040 const GlobalValue &Src) {
1041 // Should we unconditionally use the Src?
1042 if (shouldOverrideFromSrc()) {
1047 // We always have to add Src if it has appending linkage.
1048 if (Src.hasAppendingLinkage()) {
1049 // Caller should have already determined that we can't link from source
1050 // when importing (see comments in linkGlobalValueProto).
1051 assert(!isPerformingImport());
1056 bool SrcIsDeclaration = Src.isDeclarationForLinker();
1057 bool DestIsDeclaration = Dest.isDeclarationForLinker();
1059 if (isPerformingImport()) {
1060 if (isa<Function>(&Src)) {
1061 // For functions, LinkFromSrc iff this is the function requested
1062 // for importing. For variables, decide below normally.
1063 LinkFromSrc = (&Src == ImportFunction);
1067 // Check if this is an alias with an already existing definition
1068 // in Dest, which must have come from a prior importing pass from
1069 // the same Src module. Unlike imported function and variable
1070 // definitions, which are imported as available_externally and are
1071 // not definitions for the linker, that is not a valid linkage for
1072 // imported aliases which must be definitions. Simply use the existing
1074 if (isa<GlobalAlias>(&Src) && !DestIsDeclaration) {
1075 assert(isa<GlobalAlias>(&Dest));
1076 LinkFromSrc = false;
1081 if (SrcIsDeclaration) {
1082 // If Src is external or if both Src & Dest are external.. Just link the
1083 // external globals, we aren't adding anything.
1084 if (Src.hasDLLImportStorageClass()) {
1085 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
1086 LinkFromSrc = DestIsDeclaration;
1089 // If the Dest is weak, use the source linkage.
1090 LinkFromSrc = Dest.hasExternalWeakLinkage();
1094 if (DestIsDeclaration) {
1095 // If Dest is external but Src is not:
1100 if (Src.hasCommonLinkage()) {
1101 if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
1106 if (!Dest.hasCommonLinkage()) {
1107 LinkFromSrc = false;
1111 const DataLayout &DL = Dest.getParent()->getDataLayout();
1112 uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
1113 uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
1114 LinkFromSrc = SrcSize > DestSize;
1118 if (Src.isWeakForLinker()) {
1119 assert(!Dest.hasExternalWeakLinkage());
1120 assert(!Dest.hasAvailableExternallyLinkage());
1122 if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
1127 LinkFromSrc = false;
1131 if (Dest.isWeakForLinker()) {
1132 assert(Src.hasExternalLinkage());
1137 assert(!Src.hasExternalWeakLinkage());
1138 assert(!Dest.hasExternalWeakLinkage());
1139 assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
1140 "Unexpected linkage type!");
1141 return emitError("Linking globals named '" + Src.getName() +
1142 "': symbol multiply defined!");
1145 /// Loop over all of the linked values to compute type mappings. For example,
1146 /// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct
1147 /// types 'Foo' but one got renamed when the module was loaded into the same
1149 void ModuleLinker::computeTypeMapping() {
1150 for (GlobalValue &SGV : SrcM->globals()) {
1151 GlobalValue *DGV = getLinkedToGlobal(&SGV);
1155 if (!DGV->hasAppendingLinkage() || !SGV.hasAppendingLinkage()) {
1156 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1160 // Unify the element type of appending arrays.
1161 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
1162 ArrayType *SAT = cast<ArrayType>(SGV.getType()->getElementType());
1163 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
1166 for (GlobalValue &SGV : *SrcM) {
1167 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
1168 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1171 for (GlobalValue &SGV : SrcM->aliases()) {
1172 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
1173 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1176 // Incorporate types by name, scanning all the types in the source module.
1177 // At this point, the destination module may have a type "%foo = { i32 }" for
1178 // example. When the source module got loaded into the same LLVMContext, if
1179 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
1180 std::vector<StructType *> Types = SrcM->getIdentifiedStructTypes();
1181 for (StructType *ST : Types) {
1185 // Check to see if there is a dot in the name followed by a digit.
1186 size_t DotPos = ST->getName().rfind('.');
1187 if (DotPos == 0 || DotPos == StringRef::npos ||
1188 ST->getName().back() == '.' ||
1189 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos + 1])))
1192 // Check to see if the destination module has a struct with the prefix name.
1193 StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos));
1197 // Don't use it if this actually came from the source module. They're in
1198 // the same LLVMContext after all. Also don't use it unless the type is
1199 // actually used in the destination module. This can happen in situations
1202 // Module A Module B
1203 // -------- --------
1204 // %Z = type { %A } %B = type { %C.1 }
1205 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
1206 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
1207 // %C = type { i8* } %B.3 = type { %C.1 }
1209 // When we link Module B with Module A, the '%B' in Module B is
1210 // used. However, that would then use '%C.1'. But when we process '%C.1',
1211 // we prefer to take the '%C' version. So we are then left with both
1212 // '%C.1' and '%C' being used for the same types. This leads to some
1213 // variables using one type and some using the other.
1214 if (TypeMap.DstStructTypesSet.hasType(DST))
1215 TypeMap.addTypeMapping(DST, ST);
1218 // Now that we have discovered all of the type equivalences, get a body for
1219 // any 'opaque' types in the dest module that are now resolved.
1220 TypeMap.linkDefinedTypeBodies();
1223 static void upgradeGlobalArray(GlobalVariable *GV) {
1224 ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
1225 StructType *OldTy = cast<StructType>(ATy->getElementType());
1226 assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
1228 // Get the upgraded 3 element type.
1229 PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
1230 Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
1232 StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
1234 // Build new constants with a null third field filled in.
1235 Constant *OldInitC = GV->getInitializer();
1236 ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
1237 if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
1238 // Invalid initializer; give up.
1240 std::vector<Constant *> Initializers;
1241 if (OldInit && OldInit->getNumOperands()) {
1242 Value *Null = Constant::getNullValue(VoidPtrTy);
1243 for (Use &U : OldInit->operands()) {
1244 ConstantStruct *Init = cast<ConstantStruct>(U.get());
1245 Initializers.push_back(ConstantStruct::get(
1246 NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
1249 assert(Initializers.size() == ATy->getNumElements() &&
1250 "Failed to copy all array elements");
1252 // Replace the old GV with a new one.
1253 ATy = ArrayType::get(NewTy, Initializers.size());
1254 Constant *NewInit = ConstantArray::get(ATy, Initializers);
1255 GlobalVariable *NewGV = new GlobalVariable(
1256 *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
1257 GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
1258 GV->isExternallyInitialized());
1259 NewGV->copyAttributesFrom(GV);
1260 NewGV->takeName(GV);
1261 assert(GV->use_empty() && "program cannot use initializer list");
1262 GV->eraseFromParent();
1265 void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
1266 // Look for the global arrays.
1267 auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM->getNamedValue(Name));
1270 auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM->getNamedValue(Name));
1274 // Check if the types already match.
1275 auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
1277 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
1281 // Grab the element types. We can only upgrade an array of a two-field
1282 // struct. Only bother if the other one has three-fields.
1283 auto *DstEltTy = cast<StructType>(DstTy->getElementType());
1284 auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
1285 if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
1286 upgradeGlobalArray(DstGV);
1289 if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
1290 upgradeGlobalArray(SrcGV);
1292 // We can't upgrade any other differences.
1295 void ModuleLinker::upgradeMismatchedGlobals() {
1296 upgradeMismatchedGlobalArray("llvm.global_ctors");
1297 upgradeMismatchedGlobalArray("llvm.global_dtors");
1300 /// If there were any appending global variables, link them together now.
1301 /// Return true on error.
1302 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
1303 const GlobalVariable *SrcGV) {
1305 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
1306 return emitError("Linking globals named '" + SrcGV->getName() +
1307 "': can only link appending global with another appending global!");
1309 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
1311 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
1312 Type *EltTy = DstTy->getElementType();
1314 // Check to see that they two arrays agree on type.
1315 if (EltTy != SrcTy->getElementType())
1316 return emitError("Appending variables with different element types!");
1317 if (DstGV->isConstant() != SrcGV->isConstant())
1318 return emitError("Appending variables linked with different const'ness!");
1320 if (DstGV->getAlignment() != SrcGV->getAlignment())
1322 "Appending variables with different alignment need to be linked!");
1324 if (DstGV->getVisibility() != SrcGV->getVisibility())
1326 "Appending variables with different visibility need to be linked!");
1328 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
1330 "Appending variables with different unnamed_addr need to be linked!");
1332 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
1334 "Appending variables with different section name need to be linked!");
1336 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements();
1337 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
1339 // Create the new global variable.
1340 GlobalVariable *NG =
1341 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(),
1342 DstGV->getLinkage(), /*init*/nullptr, /*name*/"", DstGV,
1343 DstGV->getThreadLocalMode(),
1344 DstGV->getType()->getAddressSpace());
1346 // Propagate alignment, visibility and section info.
1347 copyGVAttributes(NG, DstGV);
1349 AppendingVarInfo AVI;
1351 AVI.DstInit = DstGV->getInitializer();
1352 AVI.SrcInit = SrcGV->getInitializer();
1353 AppendingVars.push_back(AVI);
1355 // Replace any uses of the two global variables with uses of the new
1357 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
1359 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
1360 DstGV->eraseFromParent();
1362 // Track the source variable so we don't try to link it.
1363 DoNotLinkFromSource.insert(SrcGV);
1368 bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) {
1369 GlobalValue *DGV = getLinkedToGlobal(SGV);
1371 // Handle the ultra special appending linkage case first.
1372 assert(!DGV || SGV->hasAppendingLinkage() == DGV->hasAppendingLinkage());
1373 if (SGV->hasAppendingLinkage() && isPerformingImport()) {
1374 // Don't want to append to global_ctors list, for example, when we
1375 // are importing for ThinLTO, otherwise the global ctors and dtors
1376 // get executed multiple times for local variables (the latter causing
1378 DoNotLinkFromSource.insert(SGV);
1381 if (DGV && DGV->hasAppendingLinkage())
1382 return linkAppendingVarProto(cast<GlobalVariable>(DGV),
1383 cast<GlobalVariable>(SGV));
1385 bool LinkFromSrc = true;
1386 Comdat *C = nullptr;
1387 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
1389 if (const Comdat *SC = SGV->getComdat()) {
1390 Comdat::SelectionKind SK;
1391 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1392 C = DstM->getOrInsertComdat(SC->getName());
1393 C->setSelectionKind(SK);
1394 ComdatMembers[SC].push_back(SGV);
1396 if (shouldLinkFromSource(LinkFromSrc, *DGV, *SGV))
1401 // Track the source global so that we don't attempt to copy it over when
1402 // processing global initializers.
1403 DoNotLinkFromSource.insert(SGV);
1406 // Make sure to remember this mapping.
1408 ConstantExpr::getBitCast(DGV, TypeMap.get(SGV->getType()));
1412 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1414 if (!LinkFromSrc && !DGV)
1420 // When linking from source we setVisibility from copyGlobalValueProto.
1421 setVisibility(NewGV, SGV, DGV);
1423 // If the GV is to be lazily linked, don't create it just yet.
1424 // The ValueMaterializerTy will deal with creating it if it's used.
1425 if (!DGV && !shouldOverrideFromSrc() && SGV != ImportFunction &&
1426 (SGV->hasLocalLinkage() || SGV->hasLinkOnceLinkage() ||
1427 SGV->hasAvailableExternallyLinkage())) {
1428 DoNotLinkFromSource.insert(SGV);
1432 // When we only want to link in unresolved dependencies, blacklist
1433 // the symbol unless unless DestM has a matching declaration (DGV).
1434 if (shouldLinkOnlyNeeded() && !(DGV && DGV->isDeclaration())) {
1435 DoNotLinkFromSource.insert(SGV);
1439 NewGV = copyGlobalValueProto(TypeMap, SGV, DGV);
1441 if (isPerformingImport() && !doImportAsDefinition(SGV))
1442 DoNotLinkFromSource.insert(SGV);
1445 NewGV->setUnnamedAddr(HasUnnamedAddr);
1447 if (auto *NewGO = dyn_cast<GlobalObject>(NewGV)) {
1449 NewGO->setComdat(C);
1451 if (DGV && DGV->hasCommonLinkage() && SGV->hasCommonLinkage())
1452 NewGO->setAlignment(std::max(DGV->getAlignment(), SGV->getAlignment()));
1455 if (auto *NewGVar = dyn_cast<GlobalVariable>(NewGV)) {
1456 auto *DGVar = dyn_cast_or_null<GlobalVariable>(DGV);
1457 auto *SGVar = dyn_cast<GlobalVariable>(SGV);
1458 if (DGVar && SGVar && DGVar->isDeclaration() && SGVar->isDeclaration() &&
1459 (!DGVar->isConstant() || !SGVar->isConstant()))
1460 NewGVar->setConstant(false);
1463 // Make sure to remember this mapping.
1466 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewGV, DGV->getType()));
1467 DGV->eraseFromParent();
1469 ValueMap[SGV] = NewGV;
1475 static void getArrayElements(const Constant *C,
1476 SmallVectorImpl<Constant *> &Dest) {
1477 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1479 for (unsigned i = 0; i != NumElements; ++i)
1480 Dest.push_back(C->getAggregateElement(i));
1483 void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) {
1484 // Merge the initializer.
1485 SmallVector<Constant *, 16> DstElements;
1486 getArrayElements(AVI.DstInit, DstElements);
1488 SmallVector<Constant *, 16> SrcElements;
1489 getArrayElements(AVI.SrcInit, SrcElements);
1491 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
1493 StringRef Name = AVI.NewGV->getName();
1494 bool IsNewStructor =
1495 (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
1496 cast<StructType>(NewType->getElementType())->getNumElements() == 3;
1498 for (auto *V : SrcElements) {
1499 if (IsNewStructor) {
1500 Constant *Key = V->getAggregateElement(2);
1501 if (DoNotLinkFromSource.count(Key))
1504 DstElements.push_back(
1505 MapValue(V, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1507 if (IsNewStructor) {
1508 NewType = ArrayType::get(NewType->getElementType(), DstElements.size());
1509 AVI.NewGV->mutateType(PointerType::get(NewType, 0));
1512 AVI.NewGV->setInitializer(ConstantArray::get(NewType, DstElements));
1515 /// Update the initializers in the Dest module now that all globals that may be
1516 /// referenced are in Dest.
1517 void ModuleLinker::linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src) {
1518 // Figure out what the initializer looks like in the dest module.
1519 Dst.setInitializer(MapValue(Src.getInitializer(), ValueMap,
1520 RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1523 /// Copy the source function over into the dest function and fix up references
1524 /// to values. At this point we know that Dest is an external function, and
1525 /// that Src is not.
1526 bool ModuleLinker::linkFunctionBody(Function &Dst, Function &Src) {
1527 assert(Dst.isDeclaration() && !Src.isDeclaration());
1529 // Materialize if needed.
1530 if (std::error_code EC = Src.materialize())
1531 return emitError(EC.message());
1533 // Link in the prefix data.
1534 if (Src.hasPrefixData())
1535 Dst.setPrefixData(MapValue(Src.getPrefixData(), ValueMap,
1536 RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1538 // Link in the prologue data.
1539 if (Src.hasPrologueData())
1540 Dst.setPrologueData(MapValue(Src.getPrologueData(), ValueMap,
1541 RF_MoveDistinctMDs, &TypeMap,
1544 // Link in the personality function.
1545 if (Src.hasPersonalityFn())
1546 Dst.setPersonalityFn(MapValue(Src.getPersonalityFn(), ValueMap,
1547 RF_MoveDistinctMDs, &TypeMap,
1550 // Go through and convert function arguments over, remembering the mapping.
1551 Function::arg_iterator DI = Dst.arg_begin();
1552 for (Argument &Arg : Src.args()) {
1553 DI->setName(Arg.getName()); // Copy the name over.
1555 // Add a mapping to our mapping.
1556 ValueMap[&Arg] = &*DI;
1560 // Copy over the metadata attachments.
1561 SmallVector<std::pair<unsigned, MDNode *>, 8> MDs;
1562 Src.getAllMetadata(MDs);
1563 for (const auto &I : MDs)
1564 Dst.setMetadata(I.first, MapMetadata(I.second, ValueMap, RF_MoveDistinctMDs,
1565 &TypeMap, &ValMaterializer));
1567 // Splice the body of the source function into the dest function.
1568 Dst.getBasicBlockList().splice(Dst.end(), Src.getBasicBlockList());
1570 // At this point, all of the instructions and values of the function are now
1571 // copied over. The only problem is that they are still referencing values in
1572 // the Source function as operands. Loop through all of the operands of the
1573 // functions and patch them up to point to the local versions.
1574 for (BasicBlock &BB : Dst)
1575 for (Instruction &I : BB)
1576 RemapInstruction(&I, ValueMap,
1577 RF_IgnoreMissingEntries | RF_MoveDistinctMDs, &TypeMap,
1580 // There is no need to map the arguments anymore.
1581 for (Argument &Arg : Src.args())
1582 ValueMap.erase(&Arg);
1584 Src.dematerialize();
1588 void ModuleLinker::linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src) {
1589 Constant *Aliasee = Src.getAliasee();
1590 Constant *Val = MapValue(Aliasee, ValueMap, RF_MoveDistinctMDs, &TypeMap,
1592 Dst.setAliasee(Val);
1595 bool ModuleLinker::linkGlobalValueBody(GlobalValue &Src) {
1596 Value *Dst = ValueMap[&Src];
1598 if (const Comdat *SC = Src.getComdat()) {
1599 // To ensure that we don't generate an incomplete comdat group,
1600 // we must materialize and map in any other members that are not
1601 // yet materialized in Dst, which also ensures their definitions
1602 // are linked in. Otherwise, linkonce and other lazy linked GVs will
1603 // not be materialized if they aren't referenced.
1604 for (auto *SGV : ComdatMembers[SC]) {
1607 Value *NewV = ValMaterializer.materializeValueFor(SGV);
1608 ValueMap[SGV] = NewV;
1611 if (shouldInternalizeLinkedSymbols())
1612 if (auto *DGV = dyn_cast<GlobalValue>(Dst))
1613 DGV->setLinkage(GlobalValue::InternalLinkage);
1614 if (auto *F = dyn_cast<Function>(&Src))
1615 return linkFunctionBody(cast<Function>(*Dst), *F);
1616 if (auto *GVar = dyn_cast<GlobalVariable>(&Src)) {
1617 linkGlobalInit(cast<GlobalVariable>(*Dst), *GVar);
1620 linkAliasBody(cast<GlobalAlias>(*Dst), cast<GlobalAlias>(Src));
1624 /// Insert all of the named MDNodes in Src into the Dest module.
1625 void ModuleLinker::linkNamedMDNodes() {
1626 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1627 for (const NamedMDNode &NMD : SrcM->named_metadata()) {
1628 // Don't link module flags here. Do them separately.
1629 if (&NMD == SrcModFlags)
1631 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(NMD.getName());
1632 // Add Src elements into Dest node.
1633 for (const MDNode *op : NMD.operands())
1634 DestNMD->addOperand(MapMetadata(
1635 op, ValueMap, RF_MoveDistinctMDs | RF_NullMapMissingGlobalValues,
1636 &TypeMap, &ValMaterializer));
1640 /// Merge the linker flags in Src into the Dest module.
1641 bool ModuleLinker::linkModuleFlagsMetadata() {
1642 // If the source module has no module flags, we are done.
1643 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1644 if (!SrcModFlags) return false;
1646 // If the destination module doesn't have module flags yet, then just copy
1647 // over the source module's flags.
1648 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
1649 if (DstModFlags->getNumOperands() == 0) {
1650 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1651 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1656 // First build a map of the existing module flags and requirements.
1657 DenseMap<MDString *, std::pair<MDNode *, unsigned>> Flags;
1658 SmallSetVector<MDNode*, 16> Requirements;
1659 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1660 MDNode *Op = DstModFlags->getOperand(I);
1661 ConstantInt *Behavior = mdconst::extract<ConstantInt>(Op->getOperand(0));
1662 MDString *ID = cast<MDString>(Op->getOperand(1));
1664 if (Behavior->getZExtValue() == Module::Require) {
1665 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1667 Flags[ID] = std::make_pair(Op, I);
1671 // Merge in the flags from the source module, and also collect its set of
1673 bool HasErr = false;
1674 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1675 MDNode *SrcOp = SrcModFlags->getOperand(I);
1676 ConstantInt *SrcBehavior =
1677 mdconst::extract<ConstantInt>(SrcOp->getOperand(0));
1678 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1681 std::tie(DstOp, DstIndex) = Flags.lookup(ID);
1682 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1684 // If this is a requirement, add it and continue.
1685 if (SrcBehaviorValue == Module::Require) {
1686 // If the destination module does not already have this requirement, add
1688 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1689 DstModFlags->addOperand(SrcOp);
1694 // If there is no existing flag with this ID, just add it.
1696 Flags[ID] = std::make_pair(SrcOp, DstModFlags->getNumOperands());
1697 DstModFlags->addOperand(SrcOp);
1701 // Otherwise, perform a merge.
1702 ConstantInt *DstBehavior =
1703 mdconst::extract<ConstantInt>(DstOp->getOperand(0));
1704 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1706 // If either flag has override behavior, handle it first.
1707 if (DstBehaviorValue == Module::Override) {
1708 // Diagnose inconsistent flags which both have override behavior.
1709 if (SrcBehaviorValue == Module::Override &&
1710 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1711 HasErr |= emitError("linking module flags '" + ID->getString() +
1712 "': IDs have conflicting override values");
1715 } else if (SrcBehaviorValue == Module::Override) {
1716 // Update the destination flag to that of the source.
1717 DstModFlags->setOperand(DstIndex, SrcOp);
1718 Flags[ID].first = SrcOp;
1722 // Diagnose inconsistent merge behavior types.
1723 if (SrcBehaviorValue != DstBehaviorValue) {
1724 HasErr |= emitError("linking module flags '" + ID->getString() +
1725 "': IDs have conflicting behaviors");
1729 auto replaceDstValue = [&](MDNode *New) {
1730 Metadata *FlagOps[] = {DstOp->getOperand(0), ID, New};
1731 MDNode *Flag = MDNode::get(DstM->getContext(), FlagOps);
1732 DstModFlags->setOperand(DstIndex, Flag);
1733 Flags[ID].first = Flag;
1736 // Perform the merge for standard behavior types.
1737 switch (SrcBehaviorValue) {
1738 case Module::Require:
1739 case Module::Override: llvm_unreachable("not possible");
1740 case Module::Error: {
1741 // Emit an error if the values differ.
1742 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1743 HasErr |= emitError("linking module flags '" + ID->getString() +
1744 "': IDs have conflicting values");
1748 case Module::Warning: {
1749 // Emit a warning if the values differ.
1750 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1751 emitWarning("linking module flags '" + ID->getString() +
1752 "': IDs have conflicting values");
1756 case Module::Append: {
1757 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1758 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1759 SmallVector<Metadata *, 8> MDs;
1760 MDs.reserve(DstValue->getNumOperands() + SrcValue->getNumOperands());
1761 MDs.append(DstValue->op_begin(), DstValue->op_end());
1762 MDs.append(SrcValue->op_begin(), SrcValue->op_end());
1764 replaceDstValue(MDNode::get(DstM->getContext(), MDs));
1767 case Module::AppendUnique: {
1768 SmallSetVector<Metadata *, 16> Elts;
1769 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1770 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1771 Elts.insert(DstValue->op_begin(), DstValue->op_end());
1772 Elts.insert(SrcValue->op_begin(), SrcValue->op_end());
1774 replaceDstValue(MDNode::get(DstM->getContext(),
1775 makeArrayRef(Elts.begin(), Elts.end())));
1781 // Check all of the requirements.
1782 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1783 MDNode *Requirement = Requirements[I];
1784 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1785 Metadata *ReqValue = Requirement->getOperand(1);
1787 MDNode *Op = Flags[Flag].first;
1788 if (!Op || Op->getOperand(2) != ReqValue) {
1789 HasErr |= emitError("linking module flags '" + Flag->getString() +
1790 "': does not have the required value");
1798 // This function returns true if the triples match.
1799 static bool triplesMatch(const Triple &T0, const Triple &T1) {
1800 // If vendor is apple, ignore the version number.
1801 if (T0.getVendor() == Triple::Apple)
1802 return T0.getArch() == T1.getArch() &&
1803 T0.getSubArch() == T1.getSubArch() &&
1804 T0.getVendor() == T1.getVendor() &&
1805 T0.getOS() == T1.getOS();
1810 // This function returns the merged triple.
1811 static std::string mergeTriples(const Triple &SrcTriple, const Triple &DstTriple) {
1812 // If vendor is apple, pick the triple with the larger version number.
1813 if (SrcTriple.getVendor() == Triple::Apple)
1814 if (DstTriple.isOSVersionLT(SrcTriple))
1815 return SrcTriple.str();
1817 return DstTriple.str();
1820 bool ModuleLinker::run() {
1821 assert(DstM && "Null destination module");
1822 assert(SrcM && "Null source module");
1824 // Inherit the target data from the source module if the destination module
1825 // doesn't have one already.
1826 if (DstM->getDataLayout().isDefault())
1827 DstM->setDataLayout(SrcM->getDataLayout());
1829 if (SrcM->getDataLayout() != DstM->getDataLayout()) {
1830 emitWarning("Linking two modules of different data layouts: '" +
1831 SrcM->getModuleIdentifier() + "' is '" +
1832 SrcM->getDataLayoutStr() + "' whereas '" +
1833 DstM->getModuleIdentifier() + "' is '" +
1834 DstM->getDataLayoutStr() + "'\n");
1837 // Copy the target triple from the source to dest if the dest's is empty.
1838 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
1839 DstM->setTargetTriple(SrcM->getTargetTriple());
1841 Triple SrcTriple(SrcM->getTargetTriple()), DstTriple(DstM->getTargetTriple());
1843 if (!SrcM->getTargetTriple().empty() && !triplesMatch(SrcTriple, DstTriple))
1844 emitWarning("Linking two modules of different target triples: " +
1845 SrcM->getModuleIdentifier() + "' is '" +
1846 SrcM->getTargetTriple() + "' whereas '" +
1847 DstM->getModuleIdentifier() + "' is '" +
1848 DstM->getTargetTriple() + "'\n");
1850 DstM->setTargetTriple(mergeTriples(SrcTriple, DstTriple));
1852 // Append the module inline asm string.
1853 if (!SrcM->getModuleInlineAsm().empty()) {
1854 if (DstM->getModuleInlineAsm().empty())
1855 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
1857 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
1858 SrcM->getModuleInlineAsm());
1861 // Loop over all of the linked values to compute type mappings.
1862 computeTypeMapping();
1864 ComdatsChosen.clear();
1865 for (const auto &SMEC : SrcM->getComdatSymbolTable()) {
1866 const Comdat &C = SMEC.getValue();
1867 if (ComdatsChosen.count(&C))
1869 Comdat::SelectionKind SK;
1871 if (getComdatResult(&C, SK, LinkFromSrc))
1873 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1876 // Upgrade mismatched global arrays.
1877 upgradeMismatchedGlobals();
1879 // Insert all of the globals in src into the DstM module... without linking
1880 // initializers (which could refer to functions not yet mapped over).
1881 for (GlobalVariable &GV : SrcM->globals())
1882 if (linkGlobalValueProto(&GV))
1885 // Link the functions together between the two modules, without doing function
1886 // bodies... this just adds external function prototypes to the DstM
1887 // function... We do this so that when we begin processing function bodies,
1888 // all of the global values that may be referenced are available in our
1890 for (Function &F :*SrcM)
1891 if (linkGlobalValueProto(&F))
1894 // If there were any aliases, link them now.
1895 for (GlobalAlias &GA : SrcM->aliases())
1896 if (linkGlobalValueProto(&GA))
1899 for (const AppendingVarInfo &AppendingVar : AppendingVars)
1900 linkAppendingVarInit(AppendingVar);
1902 for (const auto &Entry : DstM->getComdatSymbolTable()) {
1903 const Comdat &C = Entry.getValue();
1904 if (C.getSelectionKind() == Comdat::Any)
1906 const GlobalValue *GV = SrcM->getNamedValue(C.getName());
1908 MapValue(GV, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer);
1911 // Link in the function bodies that are defined in the source module into
1913 for (Function &SF : *SrcM) {
1914 // Skip if no body (function is external).
1915 if (SF.isDeclaration())
1918 // Skip if not linking from source.
1919 if (DoNotLinkFromSource.count(&SF))
1922 if (linkGlobalValueBody(SF))
1926 // Resolve all uses of aliases with aliasees.
1927 for (GlobalAlias &Src : SrcM->aliases()) {
1928 if (DoNotLinkFromSource.count(&Src))
1930 linkGlobalValueBody(Src);
1933 // Update the initializers in the DstM module now that all globals that may
1934 // be referenced are in DstM.
1935 for (GlobalVariable &Src : SrcM->globals()) {
1936 // Only process initialized GV's or ones not already in dest.
1937 if (!Src.hasInitializer() || DoNotLinkFromSource.count(&Src))
1939 linkGlobalValueBody(Src);
1942 // Process vector of lazily linked in functions.
1943 while (!LazilyLinkGlobalValues.empty()) {
1944 GlobalValue *SGV = LazilyLinkGlobalValues.back();
1945 LazilyLinkGlobalValues.pop_back();
1946 if (isPerformingImport() && !doImportAsDefinition(SGV))
1949 // Skip declarations that ValueMaterializer may have created in
1950 // case we link in only some of SrcM.
1951 if (shouldLinkOnlyNeeded() && SGV->isDeclaration())
1954 assert(!SGV->isDeclaration() && "users should not pass down decls");
1955 if (linkGlobalValueBody(*SGV))
1959 // Note that we are done linking global value bodies. This prevents
1960 // metadata linking from creating new references.
1961 DoneLinkingBodies = true;
1963 // Remap all of the named MDNodes in Src into the DstM module. We do this
1964 // after linking GlobalValues so that MDNodes that reference GlobalValues
1965 // are properly remapped.
1968 // Merge the module flags into the DstM module.
1969 if (linkModuleFlagsMetadata())
1975 Linker::StructTypeKeyInfo::KeyTy::KeyTy(ArrayRef<Type *> E, bool P)
1976 : ETypes(E), IsPacked(P) {}
1978 Linker::StructTypeKeyInfo::KeyTy::KeyTy(const StructType *ST)
1979 : ETypes(ST->elements()), IsPacked(ST->isPacked()) {}
1981 bool Linker::StructTypeKeyInfo::KeyTy::operator==(const KeyTy &That) const {
1982 if (IsPacked != That.IsPacked)
1984 if (ETypes != That.ETypes)
1989 bool Linker::StructTypeKeyInfo::KeyTy::operator!=(const KeyTy &That) const {
1990 return !this->operator==(That);
1993 StructType *Linker::StructTypeKeyInfo::getEmptyKey() {
1994 return DenseMapInfo<StructType *>::getEmptyKey();
1997 StructType *Linker::StructTypeKeyInfo::getTombstoneKey() {
1998 return DenseMapInfo<StructType *>::getTombstoneKey();
2001 unsigned Linker::StructTypeKeyInfo::getHashValue(const KeyTy &Key) {
2002 return hash_combine(hash_combine_range(Key.ETypes.begin(), Key.ETypes.end()),
2006 unsigned Linker::StructTypeKeyInfo::getHashValue(const StructType *ST) {
2007 return getHashValue(KeyTy(ST));
2010 bool Linker::StructTypeKeyInfo::isEqual(const KeyTy &LHS,
2011 const StructType *RHS) {
2012 if (RHS == getEmptyKey() || RHS == getTombstoneKey())
2014 return LHS == KeyTy(RHS);
2017 bool Linker::StructTypeKeyInfo::isEqual(const StructType *LHS,
2018 const StructType *RHS) {
2019 if (RHS == getEmptyKey())
2020 return LHS == getEmptyKey();
2022 if (RHS == getTombstoneKey())
2023 return LHS == getTombstoneKey();
2025 return KeyTy(LHS) == KeyTy(RHS);
2028 void Linker::IdentifiedStructTypeSet::addNonOpaque(StructType *Ty) {
2029 assert(!Ty->isOpaque());
2030 NonOpaqueStructTypes.insert(Ty);
2033 void Linker::IdentifiedStructTypeSet::switchToNonOpaque(StructType *Ty) {
2034 assert(!Ty->isOpaque());
2035 NonOpaqueStructTypes.insert(Ty);
2036 bool Removed = OpaqueStructTypes.erase(Ty);
2041 void Linker::IdentifiedStructTypeSet::addOpaque(StructType *Ty) {
2042 assert(Ty->isOpaque());
2043 OpaqueStructTypes.insert(Ty);
2047 Linker::IdentifiedStructTypeSet::findNonOpaque(ArrayRef<Type *> ETypes,
2049 Linker::StructTypeKeyInfo::KeyTy Key(ETypes, IsPacked);
2050 auto I = NonOpaqueStructTypes.find_as(Key);
2051 if (I == NonOpaqueStructTypes.end())
2056 bool Linker::IdentifiedStructTypeSet::hasType(StructType *Ty) {
2058 return OpaqueStructTypes.count(Ty);
2059 auto I = NonOpaqueStructTypes.find(Ty);
2060 if (I == NonOpaqueStructTypes.end())
2065 void Linker::init(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
2066 this->Composite = M;
2067 this->DiagnosticHandler = DiagnosticHandler;
2069 TypeFinder StructTypes;
2070 StructTypes.run(*M, true);
2071 for (StructType *Ty : StructTypes) {
2073 IdentifiedStructTypes.addOpaque(Ty);
2075 IdentifiedStructTypes.addNonOpaque(Ty);
2079 Linker::Linker(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
2080 init(M, DiagnosticHandler);
2083 Linker::Linker(Module *M) {
2084 init(M, [this](const DiagnosticInfo &DI) {
2085 Composite->getContext().diagnose(DI);
2089 void Linker::deleteModule() {
2091 Composite = nullptr;
2094 bool Linker::linkInModule(Module *Src, unsigned Flags,
2095 const FunctionInfoIndex *Index,
2096 Function *FuncToImport) {
2097 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,
2098 DiagnosticHandler, Flags, Index, FuncToImport);
2099 bool RetCode = TheLinker.run();
2100 Composite->dropTriviallyDeadConstantArrays();
2104 void Linker::setModule(Module *Dst) {
2105 init(Dst, DiagnosticHandler);
2108 //===----------------------------------------------------------------------===//
2109 // LinkModules entrypoint.
2110 //===----------------------------------------------------------------------===//
2112 /// This function links two modules together, with the resulting Dest module
2113 /// modified to be the composite of the two input modules. If an error occurs,
2114 /// true is returned and ErrorMsg (if not null) is set to indicate the problem.
2115 /// Upon failure, the Dest module could be in a modified state, and shouldn't be
2116 /// relied on to be consistent.
2117 bool Linker::LinkModules(Module *Dest, Module *Src,
2118 DiagnosticHandlerFunction DiagnosticHandler,
2120 Linker L(Dest, DiagnosticHandler);
2121 return L.linkInModule(Src, Flags);
2124 bool Linker::LinkModules(Module *Dest, Module *Src, unsigned Flags) {
2126 return L.linkInModule(Src, Flags);
2129 //===----------------------------------------------------------------------===//
2131 //===----------------------------------------------------------------------===//
2133 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
2134 LLVMLinkerMode Unused, char **OutMessages) {
2135 Module *D = unwrap(Dest);
2136 std::string Message;
2137 raw_string_ostream Stream(Message);
2138 DiagnosticPrinterRawOStream DP(Stream);
2140 LLVMBool Result = Linker::LinkModules(
2141 D, unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); });
2143 if (OutMessages && Result) {
2145 *OutMessages = strdup(Message.c_str());