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 /// Functions that have replaced other functions.
425 SmallPtrSet<const Function *, 16> OverridingFunctions;
427 DiagnosticHandlerFunction DiagnosticHandler;
429 /// For symbol clashes, prefer those from Src.
432 /// Function index passed into ModuleLinker for using in function
433 /// importing/exporting handling.
434 FunctionInfoIndex *ImportIndex;
436 /// Function to import from source module, all other functions are
437 /// imported as declarations instead of definitions.
438 Function *ImportFunction;
440 /// Set to true if the given FunctionInfoIndex contains any functions
441 /// from this source module, in which case we must conservatively assume
442 /// that any of its functions may be imported into another module
443 /// as part of a different backend compilation process.
444 bool HasExportedFunctions;
447 ModuleLinker(Module *dstM, Linker::IdentifiedStructTypeSet &Set, Module *srcM,
448 DiagnosticHandlerFunction DiagnosticHandler, unsigned Flags,
449 FunctionInfoIndex *Index = nullptr,
450 Function *FuncToImport = nullptr)
451 : DstM(dstM), SrcM(srcM), TypeMap(Set),
452 ValMaterializer(TypeMap, DstM, LazilyLinkGlobalValues, this),
453 DiagnosticHandler(DiagnosticHandler), Flags(Flags), ImportIndex(Index),
454 ImportFunction(FuncToImport), HasExportedFunctions(false) {
455 assert((ImportIndex || !ImportFunction) &&
456 "Expect a FunctionInfoIndex when importing");
457 // If we have a FunctionInfoIndex but no function to import,
458 // then this is the primary module being compiled in a ThinLTO
459 // backend compilation, and we need to see if it has functions that
460 // may be exported to another backend compilation.
461 if (ImportIndex && !ImportFunction)
462 HasExportedFunctions = ImportIndex->hasExportedFunctions(SrcM);
467 bool shouldOverrideFromSrc() { return Flags & Linker::OverrideFromSrc; }
468 bool shouldLinkOnlyNeeded() { return Flags & Linker::LinkOnlyNeeded; }
469 bool shouldInternalizeLinkedSymbols() {
470 return Flags & Linker::InternalizeLinkedSymbols;
473 /// Handles cloning of a global values from the source module into
474 /// the destination module, including setting the attributes and visibility.
475 GlobalValue *copyGlobalValueProto(TypeMapTy &TypeMap, const GlobalValue *SGV,
476 const GlobalValue *DGV = nullptr);
478 /// Check if we should promote the given local value to global scope.
479 bool doPromoteLocalToGlobal(const GlobalValue *SGV);
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));
491 void emitWarning(const Twine &Message) {
492 DiagnosticHandler(LinkDiagnosticInfo(DS_Warning, Message));
495 bool getComdatLeader(Module *M, StringRef ComdatName,
496 const GlobalVariable *&GVar);
497 bool computeResultingSelectionKind(StringRef ComdatName,
498 Comdat::SelectionKind Src,
499 Comdat::SelectionKind Dst,
500 Comdat::SelectionKind &Result,
502 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
504 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
507 /// Given a global in the source module, return the global in the
508 /// destination module that is being linked to, if any.
509 GlobalValue *getLinkedToGlobal(const GlobalValue *SrcGV) {
510 // If the source has no name it can't link. If it has local linkage,
511 // there is no name match-up going on.
512 if (!SrcGV->hasName() || SrcGV->hasLocalLinkage())
515 // Otherwise see if we have a match in the destination module's symtab.
516 GlobalValue *DGV = DstM->getNamedValue(SrcGV->getName());
520 // If we found a global with the same name in the dest module, but it has
521 // internal linkage, we are really not doing any linkage here.
522 if (DGV->hasLocalLinkage())
525 // Otherwise, we do in fact link to the destination global.
529 void computeTypeMapping();
531 void upgradeMismatchedGlobalArray(StringRef Name);
532 void upgradeMismatchedGlobals();
534 bool linkAppendingVarProto(GlobalVariable *DstGV,
535 const GlobalVariable *SrcGV);
537 bool linkGlobalValueProto(GlobalValue *GV);
538 bool linkModuleFlagsMetadata();
540 void linkAppendingVarInit(const AppendingVarInfo &AVI);
542 void linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src);
543 bool linkFunctionBody(Function &Dst, Function &Src);
544 void linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src);
545 bool linkGlobalValueBody(GlobalValue &Src);
547 /// Functions that take care of cloning a specific global value type
548 /// into the destination module.
549 GlobalVariable *copyGlobalVariableProto(TypeMapTy &TypeMap,
550 const GlobalVariable *SGVar);
551 Function *copyFunctionProto(TypeMapTy &TypeMap, const Function *SF);
552 GlobalValue *copyGlobalAliasProto(TypeMapTy &TypeMap, const GlobalAlias *SGA);
554 /// Helper methods to check if we are importing from or potentially
555 /// exporting from the current source module.
556 bool isPerformingImport() { return ImportFunction != nullptr; }
557 bool isModuleExporting() { return HasExportedFunctions; }
559 /// If we are importing from the source module, checks if we should
560 /// import SGV as a definition, otherwise import as a declaration.
561 bool doImportAsDefinition(const GlobalValue *SGV);
563 /// Get the name for SGV that should be used in the linked destination
564 /// module. Specifically, this handles the case where we need to rename
565 /// a local that is being promoted to global scope.
566 std::string getName(const GlobalValue *SGV);
568 /// Get the new linkage for SGV that should be used in the linked destination
569 /// module. Specifically, for ThinLTO importing or exporting it may need
571 GlobalValue::LinkageTypes getLinkage(const GlobalValue *SGV);
573 /// Copies the necessary global value attributes and name from the source
574 /// to the newly cloned global value.
575 void copyGVAttributes(GlobalValue *NewGV, const GlobalValue *SrcGV);
577 /// Updates the visibility for the new global cloned from the source
578 /// and, if applicable, linked with an existing destination global.
579 /// Handles visibility change required for promoted locals.
580 void setVisibility(GlobalValue *NewGV, const GlobalValue *SGV,
581 const GlobalValue *DGV = nullptr);
583 void linkNamedMDNodes();
584 void stripReplacedSubprograms();
588 /// The LLVM SymbolTable class autorenames globals that conflict in the symbol
589 /// table. This is good for all clients except for us. Go through the trouble
590 /// to force this back.
591 static void forceRenaming(GlobalValue *GV, StringRef Name) {
592 // If the global doesn't force its name or if it already has the right name,
593 // there is nothing for us to do.
594 // Note that any required local to global promotion should already be done,
595 // so promoted locals will not skip this handling as their linkage is no
597 if (GV->hasLocalLinkage() || GV->getName() == Name)
600 Module *M = GV->getParent();
602 // If there is a conflict, rename the conflict.
603 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
604 GV->takeName(ConflictGV);
605 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
606 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
608 GV->setName(Name); // Force the name back
612 /// copy additional attributes (those not needed to construct a GlobalValue)
613 /// from the SrcGV to the DestGV.
614 void ModuleLinker::copyGVAttributes(GlobalValue *NewGV,
615 const GlobalValue *SrcGV) {
616 auto *GA = dyn_cast<GlobalAlias>(SrcGV);
617 // Check for the special case of converting an alias (definition) to a
618 // non-alias (declaration). This can happen when we are importing and
619 // encounter a weak_any alias (weak_any defs may not be imported, see
620 // comments in ModuleLinker::getLinkage) or an alias whose base object is
621 // being imported as a declaration. In that case copy the attributes from the
623 if (GA && !dyn_cast<GlobalAlias>(NewGV)) {
624 assert(isPerformingImport() &&
625 (GA->hasWeakAnyLinkage() ||
626 !doImportAsDefinition(GA->getBaseObject())));
627 NewGV->copyAttributesFrom(GA->getBaseObject());
629 NewGV->copyAttributesFrom(SrcGV);
630 forceRenaming(NewGV, getName(SrcGV));
633 static bool isLessConstraining(GlobalValue::VisibilityTypes a,
634 GlobalValue::VisibilityTypes b) {
635 if (a == GlobalValue::HiddenVisibility)
637 if (b == GlobalValue::HiddenVisibility)
639 if (a == GlobalValue::ProtectedVisibility)
641 if (b == GlobalValue::ProtectedVisibility)
646 bool ModuleLinker::doImportAsDefinition(const GlobalValue *SGV) {
647 if (!isPerformingImport())
649 // Always import GlobalVariable definitions. The linkage changes
650 // described in ModuleLinker::getLinkage ensure the correct behavior (e.g.
651 // global variables with external linkage are transformed to
652 // available_externally defintions, which are ultimately turned into
653 // declaratios after the EliminateAvailableExternally pass).
654 if (dyn_cast<GlobalVariable>(SGV) && !SGV->isDeclaration())
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))
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))
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 assert(false && "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))
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() && (SGA->hasWeakAnyLinkage() ||
833 !doImportAsDefinition(SGA->getBaseObject()))) {
834 // Need to convert to declaration. All aliases must be definitions.
835 const GlobalValue *GVal = SGA->getBaseObject();
837 if (auto *GVar = dyn_cast<GlobalVariable>(GVal))
838 NewGV = copyGlobalVariableProto(TypeMap, GVar);
840 auto *F = dyn_cast<Function>(GVal);
842 NewGV = copyFunctionProto(TypeMap, F);
844 // Set the linkage to External or ExternalWeak (see comments in
845 // ModuleLinker::getLinkage for why WeakAny is converted to ExternalWeak).
846 if (SGA->hasWeakAnyLinkage())
847 NewGV->setLinkage(GlobalValue::ExternalWeakLinkage);
849 NewGV->setLinkage(GlobalValue::ExternalLinkage);
850 // Don't attempt to link body, needs to be a declaration.
851 DoNotLinkFromSource.insert(SGA);
854 // If there is no linkage to be performed or we're linking from the source,
856 auto *Ty = TypeMap.get(SGA->getValueType());
857 return GlobalAlias::create(Ty, SGA->getType()->getPointerAddressSpace(),
858 getLinkage(SGA), getName(SGA), DstM);
861 void ModuleLinker::setVisibility(GlobalValue *NewGV, const GlobalValue *SGV,
862 const GlobalValue *DGV) {
863 GlobalValue::VisibilityTypes Visibility = SGV->getVisibility();
865 Visibility = isLessConstraining(Visibility, DGV->getVisibility())
866 ? DGV->getVisibility()
868 // For promoted locals, mark them hidden so that they can later be
869 // stripped from the symbol table to reduce bloat.
870 if (SGV->hasLocalLinkage() && doPromoteLocalToGlobal(SGV))
871 Visibility = GlobalValue::HiddenVisibility;
872 NewGV->setVisibility(Visibility);
875 GlobalValue *ModuleLinker::copyGlobalValueProto(TypeMapTy &TypeMap,
876 const GlobalValue *SGV,
877 const GlobalValue *DGV) {
879 if (auto *SGVar = dyn_cast<GlobalVariable>(SGV))
880 NewGV = copyGlobalVariableProto(TypeMap, SGVar);
881 else if (auto *SF = dyn_cast<Function>(SGV))
882 NewGV = copyFunctionProto(TypeMap, SF);
884 NewGV = copyGlobalAliasProto(TypeMap, cast<GlobalAlias>(SGV));
885 copyGVAttributes(NewGV, SGV);
886 setVisibility(NewGV, SGV, DGV);
890 Value *ValueMaterializerTy::materializeValueFor(Value *V) {
891 auto *SGV = dyn_cast<GlobalValue>(V);
895 GlobalValue *DGV = ModLinker->copyGlobalValueProto(TypeMap, SGV);
897 if (Comdat *SC = SGV->getComdat()) {
898 if (auto *DGO = dyn_cast<GlobalObject>(DGV)) {
899 Comdat *DC = DstM->getOrInsertComdat(SC->getName());
904 LazilyLinkGlobalValues.push_back(SGV);
908 bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName,
909 const GlobalVariable *&GVar) {
910 const GlobalValue *GVal = M->getNamedValue(ComdatName);
911 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
912 GVal = GA->getBaseObject();
914 // We cannot resolve the size of the aliasee yet.
915 return emitError("Linking COMDATs named '" + ComdatName +
916 "': COMDAT key involves incomputable alias size.");
919 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
922 "Linking COMDATs named '" + ComdatName +
923 "': GlobalVariable required for data dependent selection!");
928 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
929 Comdat::SelectionKind Src,
930 Comdat::SelectionKind Dst,
931 Comdat::SelectionKind &Result,
933 // The ability to mix Comdat::SelectionKind::Any with
934 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
935 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
936 Dst == Comdat::SelectionKind::Largest;
937 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
938 Src == Comdat::SelectionKind::Largest;
939 if (DstAnyOrLargest && SrcAnyOrLargest) {
940 if (Dst == Comdat::SelectionKind::Largest ||
941 Src == Comdat::SelectionKind::Largest)
942 Result = Comdat::SelectionKind::Largest;
944 Result = Comdat::SelectionKind::Any;
945 } else if (Src == Dst) {
948 return emitError("Linking COMDATs named '" + ComdatName +
949 "': invalid selection kinds!");
953 case Comdat::SelectionKind::Any:
957 case Comdat::SelectionKind::NoDuplicates:
958 return emitError("Linking COMDATs named '" + ComdatName +
959 "': noduplicates has been violated!");
960 case Comdat::SelectionKind::ExactMatch:
961 case Comdat::SelectionKind::Largest:
962 case Comdat::SelectionKind::SameSize: {
963 const GlobalVariable *DstGV;
964 const GlobalVariable *SrcGV;
965 if (getComdatLeader(DstM, ComdatName, DstGV) ||
966 getComdatLeader(SrcM, ComdatName, SrcGV))
969 const DataLayout &DstDL = DstM->getDataLayout();
970 const DataLayout &SrcDL = SrcM->getDataLayout();
972 DstDL.getTypeAllocSize(DstGV->getType()->getPointerElementType());
974 SrcDL.getTypeAllocSize(SrcGV->getType()->getPointerElementType());
975 if (Result == Comdat::SelectionKind::ExactMatch) {
976 if (SrcGV->getInitializer() != DstGV->getInitializer())
977 return emitError("Linking COMDATs named '" + ComdatName +
978 "': ExactMatch violated!");
980 } else if (Result == Comdat::SelectionKind::Largest) {
981 LinkFromSrc = SrcSize > DstSize;
982 } else if (Result == Comdat::SelectionKind::SameSize) {
983 if (SrcSize != DstSize)
984 return emitError("Linking COMDATs named '" + ComdatName +
985 "': SameSize violated!");
988 llvm_unreachable("unknown selection kind");
997 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
998 Comdat::SelectionKind &Result,
1000 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
1001 StringRef ComdatName = SrcC->getName();
1002 Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable();
1003 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
1005 if (DstCI == ComdatSymTab.end()) {
1006 // Use the comdat if it is only available in one of the modules.
1012 const Comdat *DstC = &DstCI->second;
1013 Comdat::SelectionKind DSK = DstC->getSelectionKind();
1014 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
1018 bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
1019 const GlobalValue &Dest,
1020 const GlobalValue &Src) {
1021 // Should we unconditionally use the Src?
1022 if (shouldOverrideFromSrc()) {
1027 // We always have to add Src if it has appending linkage.
1028 if (Src.hasAppendingLinkage()) {
1029 // Caller should have already determined that we can't link from source
1030 // when importing (see comments in linkGlobalValueProto).
1031 assert(!isPerformingImport());
1036 bool SrcIsDeclaration = Src.isDeclarationForLinker();
1037 bool DestIsDeclaration = Dest.isDeclarationForLinker();
1039 if (isPerformingImport()) {
1040 if (isa<Function>(&Src)) {
1041 // For functions, LinkFromSrc iff this is the function requested
1042 // for importing. For variables, decide below normally.
1043 LinkFromSrc = (&Src == ImportFunction);
1047 // Check if this is an alias with an already existing definition
1048 // in Dest, which must have come from a prior importing pass from
1049 // the same Src module. Unlike imported function and variable
1050 // definitions, which are imported as available_externally and are
1051 // not definitions for the linker, that is not a valid linkage for
1052 // imported aliases which must be definitions. Simply use the existing
1054 if (isa<GlobalAlias>(&Src) && !DestIsDeclaration) {
1055 assert(isa<GlobalAlias>(&Dest));
1056 LinkFromSrc = false;
1061 if (SrcIsDeclaration) {
1062 // If Src is external or if both Src & Dest are external.. Just link the
1063 // external globals, we aren't adding anything.
1064 if (Src.hasDLLImportStorageClass()) {
1065 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
1066 LinkFromSrc = DestIsDeclaration;
1069 // If the Dest is weak, use the source linkage.
1070 LinkFromSrc = Dest.hasExternalWeakLinkage();
1074 if (DestIsDeclaration) {
1075 // If Dest is external but Src is not:
1080 if (Src.hasCommonLinkage()) {
1081 if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
1086 if (!Dest.hasCommonLinkage()) {
1087 LinkFromSrc = false;
1091 const DataLayout &DL = Dest.getParent()->getDataLayout();
1092 uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
1093 uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
1094 LinkFromSrc = SrcSize > DestSize;
1098 if (Src.isWeakForLinker()) {
1099 assert(!Dest.hasExternalWeakLinkage());
1100 assert(!Dest.hasAvailableExternallyLinkage());
1102 if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
1107 LinkFromSrc = false;
1111 if (Dest.isWeakForLinker()) {
1112 assert(Src.hasExternalLinkage());
1117 assert(!Src.hasExternalWeakLinkage());
1118 assert(!Dest.hasExternalWeakLinkage());
1119 assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
1120 "Unexpected linkage type!");
1121 return emitError("Linking globals named '" + Src.getName() +
1122 "': symbol multiply defined!");
1125 /// Loop over all of the linked values to compute type mappings. For example,
1126 /// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct
1127 /// types 'Foo' but one got renamed when the module was loaded into the same
1129 void ModuleLinker::computeTypeMapping() {
1130 for (GlobalValue &SGV : SrcM->globals()) {
1131 GlobalValue *DGV = getLinkedToGlobal(&SGV);
1135 if (!DGV->hasAppendingLinkage() || !SGV.hasAppendingLinkage()) {
1136 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1140 // Unify the element type of appending arrays.
1141 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
1142 ArrayType *SAT = cast<ArrayType>(SGV.getType()->getElementType());
1143 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
1146 for (GlobalValue &SGV : *SrcM) {
1147 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
1148 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1151 for (GlobalValue &SGV : SrcM->aliases()) {
1152 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
1153 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
1156 // Incorporate types by name, scanning all the types in the source module.
1157 // At this point, the destination module may have a type "%foo = { i32 }" for
1158 // example. When the source module got loaded into the same LLVMContext, if
1159 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
1160 std::vector<StructType *> Types = SrcM->getIdentifiedStructTypes();
1161 for (StructType *ST : Types) {
1165 // Check to see if there is a dot in the name followed by a digit.
1166 size_t DotPos = ST->getName().rfind('.');
1167 if (DotPos == 0 || DotPos == StringRef::npos ||
1168 ST->getName().back() == '.' ||
1169 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos + 1])))
1172 // Check to see if the destination module has a struct with the prefix name.
1173 StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos));
1177 // Don't use it if this actually came from the source module. They're in
1178 // the same LLVMContext after all. Also don't use it unless the type is
1179 // actually used in the destination module. This can happen in situations
1182 // Module A Module B
1183 // -------- --------
1184 // %Z = type { %A } %B = type { %C.1 }
1185 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
1186 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
1187 // %C = type { i8* } %B.3 = type { %C.1 }
1189 // When we link Module B with Module A, the '%B' in Module B is
1190 // used. However, that would then use '%C.1'. But when we process '%C.1',
1191 // we prefer to take the '%C' version. So we are then left with both
1192 // '%C.1' and '%C' being used for the same types. This leads to some
1193 // variables using one type and some using the other.
1194 if (TypeMap.DstStructTypesSet.hasType(DST))
1195 TypeMap.addTypeMapping(DST, ST);
1198 // Now that we have discovered all of the type equivalences, get a body for
1199 // any 'opaque' types in the dest module that are now resolved.
1200 TypeMap.linkDefinedTypeBodies();
1203 static void upgradeGlobalArray(GlobalVariable *GV) {
1204 ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
1205 StructType *OldTy = cast<StructType>(ATy->getElementType());
1206 assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
1208 // Get the upgraded 3 element type.
1209 PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
1210 Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
1212 StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
1214 // Build new constants with a null third field filled in.
1215 Constant *OldInitC = GV->getInitializer();
1216 ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
1217 if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
1218 // Invalid initializer; give up.
1220 std::vector<Constant *> Initializers;
1221 if (OldInit && OldInit->getNumOperands()) {
1222 Value *Null = Constant::getNullValue(VoidPtrTy);
1223 for (Use &U : OldInit->operands()) {
1224 ConstantStruct *Init = cast<ConstantStruct>(U.get());
1225 Initializers.push_back(ConstantStruct::get(
1226 NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
1229 assert(Initializers.size() == ATy->getNumElements() &&
1230 "Failed to copy all array elements");
1232 // Replace the old GV with a new one.
1233 ATy = ArrayType::get(NewTy, Initializers.size());
1234 Constant *NewInit = ConstantArray::get(ATy, Initializers);
1235 GlobalVariable *NewGV = new GlobalVariable(
1236 *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
1237 GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
1238 GV->isExternallyInitialized());
1239 NewGV->copyAttributesFrom(GV);
1240 NewGV->takeName(GV);
1241 assert(GV->use_empty() && "program cannot use initializer list");
1242 GV->eraseFromParent();
1245 void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
1246 // Look for the global arrays.
1247 auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM->getNamedValue(Name));
1250 auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM->getNamedValue(Name));
1254 // Check if the types already match.
1255 auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
1257 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
1261 // Grab the element types. We can only upgrade an array of a two-field
1262 // struct. Only bother if the other one has three-fields.
1263 auto *DstEltTy = cast<StructType>(DstTy->getElementType());
1264 auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
1265 if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
1266 upgradeGlobalArray(DstGV);
1269 if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
1270 upgradeGlobalArray(SrcGV);
1272 // We can't upgrade any other differences.
1275 void ModuleLinker::upgradeMismatchedGlobals() {
1276 upgradeMismatchedGlobalArray("llvm.global_ctors");
1277 upgradeMismatchedGlobalArray("llvm.global_dtors");
1280 /// If there were any appending global variables, link them together now.
1281 /// Return true on error.
1282 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
1283 const GlobalVariable *SrcGV) {
1285 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
1286 return emitError("Linking globals named '" + SrcGV->getName() +
1287 "': can only link appending global with another appending global!");
1289 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
1291 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
1292 Type *EltTy = DstTy->getElementType();
1294 // Check to see that they two arrays agree on type.
1295 if (EltTy != SrcTy->getElementType())
1296 return emitError("Appending variables with different element types!");
1297 if (DstGV->isConstant() != SrcGV->isConstant())
1298 return emitError("Appending variables linked with different const'ness!");
1300 if (DstGV->getAlignment() != SrcGV->getAlignment())
1302 "Appending variables with different alignment need to be linked!");
1304 if (DstGV->getVisibility() != SrcGV->getVisibility())
1306 "Appending variables with different visibility need to be linked!");
1308 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
1310 "Appending variables with different unnamed_addr need to be linked!");
1312 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
1314 "Appending variables with different section name need to be linked!");
1316 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements();
1317 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
1319 // Create the new global variable.
1320 GlobalVariable *NG =
1321 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(),
1322 DstGV->getLinkage(), /*init*/nullptr, /*name*/"", DstGV,
1323 DstGV->getThreadLocalMode(),
1324 DstGV->getType()->getAddressSpace());
1326 // Propagate alignment, visibility and section info.
1327 copyGVAttributes(NG, DstGV);
1329 AppendingVarInfo AVI;
1331 AVI.DstInit = DstGV->getInitializer();
1332 AVI.SrcInit = SrcGV->getInitializer();
1333 AppendingVars.push_back(AVI);
1335 // Replace any uses of the two global variables with uses of the new
1337 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
1339 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
1340 DstGV->eraseFromParent();
1342 // Track the source variable so we don't try to link it.
1343 DoNotLinkFromSource.insert(SrcGV);
1348 bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) {
1349 GlobalValue *DGV = getLinkedToGlobal(SGV);
1351 // Handle the ultra special appending linkage case first.
1352 assert(!DGV || SGV->hasAppendingLinkage() == DGV->hasAppendingLinkage());
1353 if (SGV->hasAppendingLinkage() && isPerformingImport()) {
1354 // Don't want to append to global_ctors list, for example, when we
1355 // are importing for ThinLTO, otherwise the global ctors and dtors
1356 // get executed multiple times for local variables (the latter causing
1358 DoNotLinkFromSource.insert(SGV);
1361 if (DGV && DGV->hasAppendingLinkage())
1362 return linkAppendingVarProto(cast<GlobalVariable>(DGV),
1363 cast<GlobalVariable>(SGV));
1365 bool LinkFromSrc = true;
1366 Comdat *C = nullptr;
1367 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
1369 if (const Comdat *SC = SGV->getComdat()) {
1370 Comdat::SelectionKind SK;
1371 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1372 C = DstM->getOrInsertComdat(SC->getName());
1373 C->setSelectionKind(SK);
1375 if (shouldLinkFromSource(LinkFromSrc, *DGV, *SGV))
1380 // Track the source global so that we don't attempt to copy it over when
1381 // processing global initializers.
1382 DoNotLinkFromSource.insert(SGV);
1385 // Make sure to remember this mapping.
1387 ConstantExpr::getBitCast(DGV, TypeMap.get(SGV->getType()));
1391 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1393 if (!LinkFromSrc && !DGV)
1399 // When linking from source we setVisibility from copyGlobalValueProto.
1400 setVisibility(NewGV, SGV, DGV);
1402 // If the GV is to be lazily linked, don't create it just yet.
1403 // The ValueMaterializerTy will deal with creating it if it's used.
1404 if (!DGV && !shouldOverrideFromSrc() && SGV != ImportFunction &&
1405 (SGV->hasLocalLinkage() || SGV->hasLinkOnceLinkage() ||
1406 SGV->hasAvailableExternallyLinkage())) {
1407 DoNotLinkFromSource.insert(SGV);
1411 // When we only want to link in unresolved dependencies, blacklist
1412 // the symbol unless unless DestM has a matching declaration (DGV).
1413 if (shouldLinkOnlyNeeded() && !(DGV && DGV->isDeclaration())) {
1414 DoNotLinkFromSource.insert(SGV);
1418 NewGV = copyGlobalValueProto(TypeMap, SGV, DGV);
1420 if (DGV && isa<Function>(DGV))
1421 if (auto *NewF = dyn_cast<Function>(NewGV))
1422 OverridingFunctions.insert(NewF);
1425 NewGV->setUnnamedAddr(HasUnnamedAddr);
1427 if (auto *NewGO = dyn_cast<GlobalObject>(NewGV)) {
1429 NewGO->setComdat(C);
1431 if (DGV && DGV->hasCommonLinkage() && SGV->hasCommonLinkage())
1432 NewGO->setAlignment(std::max(DGV->getAlignment(), SGV->getAlignment()));
1435 if (auto *NewGVar = dyn_cast<GlobalVariable>(NewGV)) {
1436 auto *DGVar = dyn_cast_or_null<GlobalVariable>(DGV);
1437 auto *SGVar = dyn_cast<GlobalVariable>(SGV);
1438 if (DGVar && SGVar && DGVar->isDeclaration() && SGVar->isDeclaration() &&
1439 (!DGVar->isConstant() || !SGVar->isConstant()))
1440 NewGVar->setConstant(false);
1443 // Make sure to remember this mapping.
1446 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewGV, DGV->getType()));
1447 DGV->eraseFromParent();
1449 ValueMap[SGV] = NewGV;
1455 static void getArrayElements(const Constant *C,
1456 SmallVectorImpl<Constant *> &Dest) {
1457 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1459 for (unsigned i = 0; i != NumElements; ++i)
1460 Dest.push_back(C->getAggregateElement(i));
1463 void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) {
1464 // Merge the initializer.
1465 SmallVector<Constant *, 16> DstElements;
1466 getArrayElements(AVI.DstInit, DstElements);
1468 SmallVector<Constant *, 16> SrcElements;
1469 getArrayElements(AVI.SrcInit, SrcElements);
1471 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
1473 StringRef Name = AVI.NewGV->getName();
1474 bool IsNewStructor =
1475 (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
1476 cast<StructType>(NewType->getElementType())->getNumElements() == 3;
1478 for (auto *V : SrcElements) {
1479 if (IsNewStructor) {
1480 Constant *Key = V->getAggregateElement(2);
1481 if (DoNotLinkFromSource.count(Key))
1484 DstElements.push_back(
1485 MapValue(V, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1487 if (IsNewStructor) {
1488 NewType = ArrayType::get(NewType->getElementType(), DstElements.size());
1489 AVI.NewGV->mutateType(PointerType::get(NewType, 0));
1492 AVI.NewGV->setInitializer(ConstantArray::get(NewType, DstElements));
1495 /// Update the initializers in the Dest module now that all globals that may be
1496 /// referenced are in Dest.
1497 void ModuleLinker::linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src) {
1498 // Figure out what the initializer looks like in the dest module.
1499 Dst.setInitializer(MapValue(Src.getInitializer(), ValueMap,
1500 RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1503 /// Copy the source function over into the dest function and fix up references
1504 /// to values. At this point we know that Dest is an external function, and
1505 /// that Src is not.
1506 bool ModuleLinker::linkFunctionBody(Function &Dst, Function &Src) {
1507 assert(Dst.isDeclaration() && !Src.isDeclaration());
1509 // Materialize if needed.
1510 if (std::error_code EC = Src.materialize())
1511 return emitError(EC.message());
1513 // Link in the prefix data.
1514 if (Src.hasPrefixData())
1515 Dst.setPrefixData(MapValue(Src.getPrefixData(), ValueMap,
1516 RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1518 // Link in the prologue data.
1519 if (Src.hasPrologueData())
1520 Dst.setPrologueData(MapValue(Src.getPrologueData(), ValueMap,
1521 RF_MoveDistinctMDs, &TypeMap,
1524 // Link in the personality function.
1525 if (Src.hasPersonalityFn())
1526 Dst.setPersonalityFn(MapValue(Src.getPersonalityFn(), ValueMap,
1527 RF_MoveDistinctMDs, &TypeMap,
1530 // Go through and convert function arguments over, remembering the mapping.
1531 Function::arg_iterator DI = Dst.arg_begin();
1532 for (Argument &Arg : Src.args()) {
1533 DI->setName(Arg.getName()); // Copy the name over.
1535 // Add a mapping to our mapping.
1536 ValueMap[&Arg] = &*DI;
1540 // Copy over the metadata attachments.
1541 SmallVector<std::pair<unsigned, MDNode *>, 8> MDs;
1542 Src.getAllMetadata(MDs);
1543 for (const auto &I : MDs)
1544 Dst.setMetadata(I.first, MapMetadata(I.second, ValueMap, RF_MoveDistinctMDs,
1545 &TypeMap, &ValMaterializer));
1547 // Splice the body of the source function into the dest function.
1548 Dst.getBasicBlockList().splice(Dst.end(), Src.getBasicBlockList());
1550 // At this point, all of the instructions and values of the function are now
1551 // copied over. The only problem is that they are still referencing values in
1552 // the Source function as operands. Loop through all of the operands of the
1553 // functions and patch them up to point to the local versions.
1554 for (BasicBlock &BB : Dst)
1555 for (Instruction &I : BB)
1556 RemapInstruction(&I, ValueMap,
1557 RF_IgnoreMissingEntries | RF_MoveDistinctMDs, &TypeMap,
1560 // There is no need to map the arguments anymore.
1561 for (Argument &Arg : Src.args())
1562 ValueMap.erase(&Arg);
1564 Src.dematerialize();
1568 void ModuleLinker::linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src) {
1569 Constant *Aliasee = Src.getAliasee();
1570 Constant *Val = MapValue(Aliasee, ValueMap, RF_MoveDistinctMDs, &TypeMap,
1572 Dst.setAliasee(Val);
1575 bool ModuleLinker::linkGlobalValueBody(GlobalValue &Src) {
1576 Value *Dst = ValueMap[&Src];
1578 if (shouldInternalizeLinkedSymbols())
1579 if (auto *DGV = dyn_cast<GlobalValue>(Dst))
1580 DGV->setLinkage(GlobalValue::InternalLinkage);
1581 if (auto *F = dyn_cast<Function>(&Src))
1582 return linkFunctionBody(cast<Function>(*Dst), *F);
1583 if (auto *GVar = dyn_cast<GlobalVariable>(&Src)) {
1584 linkGlobalInit(cast<GlobalVariable>(*Dst), *GVar);
1587 linkAliasBody(cast<GlobalAlias>(*Dst), cast<GlobalAlias>(Src));
1591 /// Insert all of the named MDNodes in Src into the Dest module.
1592 void ModuleLinker::linkNamedMDNodes() {
1593 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1594 for (const NamedMDNode &NMD : SrcM->named_metadata()) {
1595 // Don't link module flags here. Do them separately.
1596 if (&NMD == SrcModFlags)
1598 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(NMD.getName());
1599 // Add Src elements into Dest node.
1600 for (const MDNode *op : NMD.operands())
1601 DestNMD->addOperand(MapMetadata(op, ValueMap, RF_MoveDistinctMDs,
1602 &TypeMap, &ValMaterializer));
1606 /// Drop DISubprograms that have been superseded.
1608 /// FIXME: this creates an asymmetric result: we strip functions from losing
1609 /// subprograms in DstM, but leave losing subprograms in SrcM.
1610 /// TODO: Remove this logic once the backend can correctly determine canonical
1612 void ModuleLinker::stripReplacedSubprograms() {
1613 // Avoid quadratic runtime by returning early when there's nothing to do.
1614 if (OverridingFunctions.empty())
1617 // Move the functions now, so the set gets cleared even on early returns.
1618 auto Functions = std::move(OverridingFunctions);
1619 OverridingFunctions.clear();
1621 // Drop functions from subprograms if they've been overridden by the new
1623 NamedMDNode *CompileUnits = DstM->getNamedMetadata("llvm.dbg.cu");
1626 for (unsigned I = 0, E = CompileUnits->getNumOperands(); I != E; ++I) {
1627 auto *CU = cast<DICompileUnit>(CompileUnits->getOperand(I));
1628 assert(CU && "Expected valid compile unit");
1630 for (DISubprogram *SP : CU->getSubprograms()) {
1631 if (!SP || !SP->getFunction() || !Functions.count(SP->getFunction()))
1634 // Prevent DebugInfoFinder from tagging this as the canonical subprogram,
1635 // since the canonical one is in the incoming module.
1636 SP->replaceFunction(nullptr);
1641 /// Merge the linker flags in Src into the Dest module.
1642 bool ModuleLinker::linkModuleFlagsMetadata() {
1643 // If the source module has no module flags, we are done.
1644 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1645 if (!SrcModFlags) return false;
1647 // If the destination module doesn't have module flags yet, then just copy
1648 // over the source module's flags.
1649 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
1650 if (DstModFlags->getNumOperands() == 0) {
1651 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1652 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1657 // First build a map of the existing module flags and requirements.
1658 DenseMap<MDString *, std::pair<MDNode *, unsigned>> Flags;
1659 SmallSetVector<MDNode*, 16> Requirements;
1660 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1661 MDNode *Op = DstModFlags->getOperand(I);
1662 ConstantInt *Behavior = mdconst::extract<ConstantInt>(Op->getOperand(0));
1663 MDString *ID = cast<MDString>(Op->getOperand(1));
1665 if (Behavior->getZExtValue() == Module::Require) {
1666 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1668 Flags[ID] = std::make_pair(Op, I);
1672 // Merge in the flags from the source module, and also collect its set of
1674 bool HasErr = false;
1675 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1676 MDNode *SrcOp = SrcModFlags->getOperand(I);
1677 ConstantInt *SrcBehavior =
1678 mdconst::extract<ConstantInt>(SrcOp->getOperand(0));
1679 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1682 std::tie(DstOp, DstIndex) = Flags.lookup(ID);
1683 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1685 // If this is a requirement, add it and continue.
1686 if (SrcBehaviorValue == Module::Require) {
1687 // If the destination module does not already have this requirement, add
1689 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1690 DstModFlags->addOperand(SrcOp);
1695 // If there is no existing flag with this ID, just add it.
1697 Flags[ID] = std::make_pair(SrcOp, DstModFlags->getNumOperands());
1698 DstModFlags->addOperand(SrcOp);
1702 // Otherwise, perform a merge.
1703 ConstantInt *DstBehavior =
1704 mdconst::extract<ConstantInt>(DstOp->getOperand(0));
1705 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1707 // If either flag has override behavior, handle it first.
1708 if (DstBehaviorValue == Module::Override) {
1709 // Diagnose inconsistent flags which both have override behavior.
1710 if (SrcBehaviorValue == Module::Override &&
1711 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1712 HasErr |= emitError("linking module flags '" + ID->getString() +
1713 "': IDs have conflicting override values");
1716 } else if (SrcBehaviorValue == Module::Override) {
1717 // Update the destination flag to that of the source.
1718 DstModFlags->setOperand(DstIndex, SrcOp);
1719 Flags[ID].first = SrcOp;
1723 // Diagnose inconsistent merge behavior types.
1724 if (SrcBehaviorValue != DstBehaviorValue) {
1725 HasErr |= emitError("linking module flags '" + ID->getString() +
1726 "': IDs have conflicting behaviors");
1730 auto replaceDstValue = [&](MDNode *New) {
1731 Metadata *FlagOps[] = {DstOp->getOperand(0), ID, New};
1732 MDNode *Flag = MDNode::get(DstM->getContext(), FlagOps);
1733 DstModFlags->setOperand(DstIndex, Flag);
1734 Flags[ID].first = Flag;
1737 // Perform the merge for standard behavior types.
1738 switch (SrcBehaviorValue) {
1739 case Module::Require:
1740 case Module::Override: llvm_unreachable("not possible");
1741 case Module::Error: {
1742 // Emit an error if the values differ.
1743 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1744 HasErr |= emitError("linking module flags '" + ID->getString() +
1745 "': IDs have conflicting values");
1749 case Module::Warning: {
1750 // Emit a warning if the values differ.
1751 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1752 emitWarning("linking module flags '" + ID->getString() +
1753 "': IDs have conflicting values");
1757 case Module::Append: {
1758 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1759 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1760 SmallVector<Metadata *, 8> MDs;
1761 MDs.reserve(DstValue->getNumOperands() + SrcValue->getNumOperands());
1762 MDs.append(DstValue->op_begin(), DstValue->op_end());
1763 MDs.append(SrcValue->op_begin(), SrcValue->op_end());
1765 replaceDstValue(MDNode::get(DstM->getContext(), MDs));
1768 case Module::AppendUnique: {
1769 SmallSetVector<Metadata *, 16> Elts;
1770 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1771 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1772 Elts.insert(DstValue->op_begin(), DstValue->op_end());
1773 Elts.insert(SrcValue->op_begin(), SrcValue->op_end());
1775 replaceDstValue(MDNode::get(DstM->getContext(),
1776 makeArrayRef(Elts.begin(), Elts.end())));
1782 // Check all of the requirements.
1783 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1784 MDNode *Requirement = Requirements[I];
1785 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1786 Metadata *ReqValue = Requirement->getOperand(1);
1788 MDNode *Op = Flags[Flag].first;
1789 if (!Op || Op->getOperand(2) != ReqValue) {
1790 HasErr |= emitError("linking module flags '" + Flag->getString() +
1791 "': does not have the required value");
1799 // This function returns true if the triples match.
1800 static bool triplesMatch(const Triple &T0, const Triple &T1) {
1801 // If vendor is apple, ignore the version number.
1802 if (T0.getVendor() == Triple::Apple)
1803 return T0.getArch() == T1.getArch() &&
1804 T0.getSubArch() == T1.getSubArch() &&
1805 T0.getVendor() == T1.getVendor() &&
1806 T0.getOS() == T1.getOS();
1811 // This function returns the merged triple.
1812 static std::string mergeTriples(const Triple &SrcTriple, const Triple &DstTriple) {
1813 // If vendor is apple, pick the triple with the larger version number.
1814 if (SrcTriple.getVendor() == Triple::Apple)
1815 if (DstTriple.isOSVersionLT(SrcTriple))
1816 return SrcTriple.str();
1818 return DstTriple.str();
1821 bool ModuleLinker::run() {
1822 assert(DstM && "Null destination module");
1823 assert(SrcM && "Null source module");
1825 // Inherit the target data from the source module if the destination module
1826 // doesn't have one already.
1827 if (DstM->getDataLayout().isDefault())
1828 DstM->setDataLayout(SrcM->getDataLayout());
1830 if (SrcM->getDataLayout() != DstM->getDataLayout()) {
1831 emitWarning("Linking two modules of different data layouts: '" +
1832 SrcM->getModuleIdentifier() + "' is '" +
1833 SrcM->getDataLayoutStr() + "' whereas '" +
1834 DstM->getModuleIdentifier() + "' is '" +
1835 DstM->getDataLayoutStr() + "'\n");
1838 // Copy the target triple from the source to dest if the dest's is empty.
1839 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
1840 DstM->setTargetTriple(SrcM->getTargetTriple());
1842 Triple SrcTriple(SrcM->getTargetTriple()), DstTriple(DstM->getTargetTriple());
1844 if (!SrcM->getTargetTriple().empty() && !triplesMatch(SrcTriple, DstTriple))
1845 emitWarning("Linking two modules of different target triples: " +
1846 SrcM->getModuleIdentifier() + "' is '" +
1847 SrcM->getTargetTriple() + "' whereas '" +
1848 DstM->getModuleIdentifier() + "' is '" +
1849 DstM->getTargetTriple() + "'\n");
1851 DstM->setTargetTriple(mergeTriples(SrcTriple, DstTriple));
1853 // Append the module inline asm string.
1854 if (!SrcM->getModuleInlineAsm().empty()) {
1855 if (DstM->getModuleInlineAsm().empty())
1856 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
1858 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
1859 SrcM->getModuleInlineAsm());
1862 // Loop over all of the linked values to compute type mappings.
1863 computeTypeMapping();
1865 ComdatsChosen.clear();
1866 for (const auto &SMEC : SrcM->getComdatSymbolTable()) {
1867 const Comdat &C = SMEC.getValue();
1868 if (ComdatsChosen.count(&C))
1870 Comdat::SelectionKind SK;
1872 if (getComdatResult(&C, SK, LinkFromSrc))
1874 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1877 // Upgrade mismatched global arrays.
1878 upgradeMismatchedGlobals();
1880 // Insert all of the globals in src into the DstM module... without linking
1881 // initializers (which could refer to functions not yet mapped over).
1882 for (GlobalVariable &GV : SrcM->globals())
1883 if (linkGlobalValueProto(&GV))
1886 // Link the functions together between the two modules, without doing function
1887 // bodies... this just adds external function prototypes to the DstM
1888 // function... We do this so that when we begin processing function bodies,
1889 // all of the global values that may be referenced are available in our
1891 for (Function &F :*SrcM)
1892 if (linkGlobalValueProto(&F))
1895 // If there were any aliases, link them now.
1896 for (GlobalAlias &GA : SrcM->aliases())
1897 if (linkGlobalValueProto(&GA))
1900 for (const AppendingVarInfo &AppendingVar : AppendingVars)
1901 linkAppendingVarInit(AppendingVar);
1903 for (const auto &Entry : DstM->getComdatSymbolTable()) {
1904 const Comdat &C = Entry.getValue();
1905 if (C.getSelectionKind() == Comdat::Any)
1907 const GlobalValue *GV = SrcM->getNamedValue(C.getName());
1909 MapValue(GV, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer);
1912 // Strip replaced subprograms before mapping any metadata -- so that we're
1913 // not changing metadata from the source module (note that
1914 // linkGlobalValueBody() eventually calls RemapInstruction() and therefore
1915 // MapMetadata()) -- but after linking global value protocols -- so that
1916 // OverridingFunctions has been built.
1917 stripReplacedSubprograms();
1919 // Link in the function bodies that are defined in the source module into
1921 for (Function &SF : *SrcM) {
1922 // Skip if no body (function is external).
1923 if (SF.isDeclaration())
1926 // Skip if not linking from source.
1927 if (DoNotLinkFromSource.count(&SF))
1930 // When importing, only materialize the function requested for import.
1931 if (isPerformingImport() && &SF != ImportFunction)
1934 if (linkGlobalValueBody(SF))
1938 // Resolve all uses of aliases with aliasees.
1939 for (GlobalAlias &Src : SrcM->aliases()) {
1940 if (DoNotLinkFromSource.count(&Src))
1942 linkGlobalValueBody(Src);
1945 // Remap all of the named MDNodes in Src into the DstM module. We do this
1946 // after linking GlobalValues so that MDNodes that reference GlobalValues
1947 // are properly remapped.
1950 // Merge the module flags into the DstM module.
1951 if (linkModuleFlagsMetadata())
1954 // Update the initializers in the DstM module now that all globals that may
1955 // be referenced are in DstM.
1956 for (GlobalVariable &Src : SrcM->globals()) {
1957 // Only process initialized GV's or ones not already in dest.
1958 if (!Src.hasInitializer() || DoNotLinkFromSource.count(&Src))
1960 linkGlobalValueBody(Src);
1963 // Process vector of lazily linked in functions.
1964 while (!LazilyLinkGlobalValues.empty()) {
1965 GlobalValue *SGV = LazilyLinkGlobalValues.back();
1966 LazilyLinkGlobalValues.pop_back();
1967 if (isPerformingImport() && !doImportAsDefinition(SGV))
1970 // Skip declarations that ValueMaterializer may have created in
1971 // case we link in only some of SrcM.
1972 if (shouldLinkOnlyNeeded() && SGV->isDeclaration())
1975 assert(!SGV->isDeclaration() && "users should not pass down decls");
1976 if (linkGlobalValueBody(*SGV))
1983 Linker::StructTypeKeyInfo::KeyTy::KeyTy(ArrayRef<Type *> E, bool P)
1984 : ETypes(E), IsPacked(P) {}
1986 Linker::StructTypeKeyInfo::KeyTy::KeyTy(const StructType *ST)
1987 : ETypes(ST->elements()), IsPacked(ST->isPacked()) {}
1989 bool Linker::StructTypeKeyInfo::KeyTy::operator==(const KeyTy &That) const {
1990 if (IsPacked != That.IsPacked)
1992 if (ETypes != That.ETypes)
1997 bool Linker::StructTypeKeyInfo::KeyTy::operator!=(const KeyTy &That) const {
1998 return !this->operator==(That);
2001 StructType *Linker::StructTypeKeyInfo::getEmptyKey() {
2002 return DenseMapInfo<StructType *>::getEmptyKey();
2005 StructType *Linker::StructTypeKeyInfo::getTombstoneKey() {
2006 return DenseMapInfo<StructType *>::getTombstoneKey();
2009 unsigned Linker::StructTypeKeyInfo::getHashValue(const KeyTy &Key) {
2010 return hash_combine(hash_combine_range(Key.ETypes.begin(), Key.ETypes.end()),
2014 unsigned Linker::StructTypeKeyInfo::getHashValue(const StructType *ST) {
2015 return getHashValue(KeyTy(ST));
2018 bool Linker::StructTypeKeyInfo::isEqual(const KeyTy &LHS,
2019 const StructType *RHS) {
2020 if (RHS == getEmptyKey() || RHS == getTombstoneKey())
2022 return LHS == KeyTy(RHS);
2025 bool Linker::StructTypeKeyInfo::isEqual(const StructType *LHS,
2026 const StructType *RHS) {
2027 if (RHS == getEmptyKey())
2028 return LHS == getEmptyKey();
2030 if (RHS == getTombstoneKey())
2031 return LHS == getTombstoneKey();
2033 return KeyTy(LHS) == KeyTy(RHS);
2036 void Linker::IdentifiedStructTypeSet::addNonOpaque(StructType *Ty) {
2037 assert(!Ty->isOpaque());
2038 NonOpaqueStructTypes.insert(Ty);
2041 void Linker::IdentifiedStructTypeSet::switchToNonOpaque(StructType *Ty) {
2042 assert(!Ty->isOpaque());
2043 NonOpaqueStructTypes.insert(Ty);
2044 bool Removed = OpaqueStructTypes.erase(Ty);
2049 void Linker::IdentifiedStructTypeSet::addOpaque(StructType *Ty) {
2050 assert(Ty->isOpaque());
2051 OpaqueStructTypes.insert(Ty);
2055 Linker::IdentifiedStructTypeSet::findNonOpaque(ArrayRef<Type *> ETypes,
2057 Linker::StructTypeKeyInfo::KeyTy Key(ETypes, IsPacked);
2058 auto I = NonOpaqueStructTypes.find_as(Key);
2059 if (I == NonOpaqueStructTypes.end())
2064 bool Linker::IdentifiedStructTypeSet::hasType(StructType *Ty) {
2066 return OpaqueStructTypes.count(Ty);
2067 auto I = NonOpaqueStructTypes.find(Ty);
2068 if (I == NonOpaqueStructTypes.end())
2073 void Linker::init(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
2074 this->Composite = M;
2075 this->DiagnosticHandler = DiagnosticHandler;
2077 TypeFinder StructTypes;
2078 StructTypes.run(*M, true);
2079 for (StructType *Ty : StructTypes) {
2081 IdentifiedStructTypes.addOpaque(Ty);
2083 IdentifiedStructTypes.addNonOpaque(Ty);
2087 Linker::Linker(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
2088 init(M, DiagnosticHandler);
2091 Linker::Linker(Module *M) {
2092 init(M, [this](const DiagnosticInfo &DI) {
2093 Composite->getContext().diagnose(DI);
2097 void Linker::deleteModule() {
2099 Composite = nullptr;
2102 bool Linker::linkInModule(Module *Src, unsigned Flags, FunctionInfoIndex *Index,
2103 Function *FuncToImport) {
2104 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,
2105 DiagnosticHandler, Flags, Index, FuncToImport);
2106 bool RetCode = TheLinker.run();
2107 Composite->dropTriviallyDeadConstantArrays();
2111 void Linker::setModule(Module *Dst) {
2112 init(Dst, DiagnosticHandler);
2115 //===----------------------------------------------------------------------===//
2116 // LinkModules entrypoint.
2117 //===----------------------------------------------------------------------===//
2119 /// This function links two modules together, with the resulting Dest module
2120 /// modified to be the composite of the two input modules. If an error occurs,
2121 /// true is returned and ErrorMsg (if not null) is set to indicate the problem.
2122 /// Upon failure, the Dest module could be in a modified state, and shouldn't be
2123 /// relied on to be consistent.
2124 bool Linker::LinkModules(Module *Dest, Module *Src,
2125 DiagnosticHandlerFunction DiagnosticHandler,
2127 Linker L(Dest, DiagnosticHandler);
2128 return L.linkInModule(Src, Flags);
2131 bool Linker::LinkModules(Module *Dest, Module *Src, unsigned Flags) {
2133 return L.linkInModule(Src, Flags);
2136 //===----------------------------------------------------------------------===//
2138 //===----------------------------------------------------------------------===//
2140 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
2141 LLVMLinkerMode Unused, char **OutMessages) {
2142 Module *D = unwrap(Dest);
2143 std::string Message;
2144 raw_string_ostream Stream(Message);
2145 DiagnosticPrinterRawOStream DP(Stream);
2147 LLVMBool Result = Linker::LinkModules(
2148 D, unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); });
2150 if (OutMessages && Result) {
2152 *OutMessages = strdup(Message.c_str());