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/Optional.h"
17 #include "llvm/ADT/SetVector.h"
18 #include "llvm/ADT/SmallString.h"
19 #include "llvm/IR/Constants.h"
20 #include "llvm/IR/DiagnosticInfo.h"
21 #include "llvm/IR/DiagnosticPrinter.h"
22 #include "llvm/IR/LLVMContext.h"
23 #include "llvm/IR/Module.h"
24 #include "llvm/IR/TypeFinder.h"
25 #include "llvm/Support/CommandLine.h"
26 #include "llvm/Support/Debug.h"
27 #include "llvm/Support/raw_ostream.h"
28 #include "llvm/Transforms/Utils/Cloning.h"
34 //===----------------------------------------------------------------------===//
35 // TypeMap implementation.
36 //===----------------------------------------------------------------------===//
39 typedef SmallPtrSet<StructType *, 32> TypeSet;
41 class TypeMapTy : public ValueMapTypeRemapper {
42 /// This is a mapping from a source type to a destination type to use.
43 DenseMap<Type*, Type*> MappedTypes;
45 /// When checking to see if two subgraphs are isomorphic, we speculatively
46 /// add types to MappedTypes, but keep track of them here in case we need to
48 SmallVector<Type*, 16> SpeculativeTypes;
50 /// This is a list of non-opaque structs in the source module that are mapped
51 /// to an opaque struct in the destination module.
52 SmallVector<StructType*, 16> SrcDefinitionsToResolve;
54 /// This is the set of opaque types in the destination modules who are
55 /// getting a body from the source module.
56 SmallPtrSet<StructType*, 16> DstResolvedOpaqueTypes;
59 TypeMapTy(TypeSet &Set) : DstStructTypesSet(Set) {}
61 TypeSet &DstStructTypesSet;
62 /// Indicate that the specified type in the destination module is conceptually
63 /// equivalent to the specified type in the source module.
64 void addTypeMapping(Type *DstTy, Type *SrcTy);
66 /// Produce a body for an opaque type in the dest module from a type
67 /// definition in the source module.
68 void linkDefinedTypeBodies();
70 /// Return the mapped type to use for the specified input type from the
72 Type *get(Type *SrcTy);
74 FunctionType *get(FunctionType *T) {
75 return cast<FunctionType>(get((Type *)T));
78 /// Dump out the type map for debugging purposes.
80 for (auto &Pair : MappedTypes) {
81 dbgs() << "TypeMap: ";
82 Pair.first->print(dbgs());
84 Pair.second->print(dbgs());
90 Type *getImpl(Type *T);
91 Type *remapType(Type *SrcTy) override { return get(SrcTy); }
93 bool areTypesIsomorphic(Type *DstTy, Type *SrcTy);
97 void TypeMapTy::addTypeMapping(Type *DstTy, Type *SrcTy) {
98 // Check to see if these types are recursively isomorphic and establish a
99 // mapping between them if so.
100 if (areTypesIsomorphic(DstTy, SrcTy)) {
101 SpeculativeTypes.clear();
105 // Oops, they aren't isomorphic. Just discard this request by rolling out
106 // any speculative mappings we've established.
107 unsigned Removed = 0;
108 for (unsigned I = 0, E = SpeculativeTypes.size(); I != E; ++I) {
109 Type *SrcTy = SpeculativeTypes[I];
110 auto Iter = MappedTypes.find(SrcTy);
111 auto *DstTy = dyn_cast<StructType>(Iter->second);
112 if (DstTy && DstResolvedOpaqueTypes.erase(DstTy))
114 MappedTypes.erase(Iter);
116 SrcDefinitionsToResolve.resize(SrcDefinitionsToResolve.size() - Removed);
117 SpeculativeTypes.clear();
120 /// Recursively walk this pair of types, returning true if they are isomorphic,
121 /// false if they are not.
122 bool TypeMapTy::areTypesIsomorphic(Type *DstTy, Type *SrcTy) {
123 // Two types with differing kinds are clearly not isomorphic.
124 if (DstTy->getTypeID() != SrcTy->getTypeID())
127 // If we have an entry in the MappedTypes table, then we have our answer.
128 Type *&Entry = MappedTypes[SrcTy];
130 return Entry == DstTy;
132 // Two identical types are clearly isomorphic. Remember this
133 // non-speculatively.
134 if (DstTy == SrcTy) {
139 // Okay, we have two types with identical kinds that we haven't seen before.
141 // If this is an opaque struct type, special case it.
142 if (StructType *SSTy = dyn_cast<StructType>(SrcTy)) {
143 // Mapping an opaque type to any struct, just keep the dest struct.
144 if (SSTy->isOpaque()) {
146 SpeculativeTypes.push_back(SrcTy);
150 // Mapping a non-opaque source type to an opaque dest. If this is the first
151 // type that we're mapping onto this destination type then we succeed. Keep
152 // the dest, but fill it in later. If this is the second (different) type
153 // that we're trying to map onto the same opaque type then we fail.
154 if (cast<StructType>(DstTy)->isOpaque()) {
155 // We can only map one source type onto the opaque destination type.
156 if (!DstResolvedOpaqueTypes.insert(cast<StructType>(DstTy)).second)
158 SrcDefinitionsToResolve.push_back(SSTy);
159 SpeculativeTypes.push_back(SrcTy);
165 // If the number of subtypes disagree between the two types, then we fail.
166 if (SrcTy->getNumContainedTypes() != DstTy->getNumContainedTypes())
169 // Fail if any of the extra properties (e.g. array size) of the type disagree.
170 if (isa<IntegerType>(DstTy))
171 return false; // bitwidth disagrees.
172 if (PointerType *PT = dyn_cast<PointerType>(DstTy)) {
173 if (PT->getAddressSpace() != cast<PointerType>(SrcTy)->getAddressSpace())
176 } else if (FunctionType *FT = dyn_cast<FunctionType>(DstTy)) {
177 if (FT->isVarArg() != cast<FunctionType>(SrcTy)->isVarArg())
179 } else if (StructType *DSTy = dyn_cast<StructType>(DstTy)) {
180 StructType *SSTy = cast<StructType>(SrcTy);
181 if (DSTy->isLiteral() != SSTy->isLiteral() ||
182 DSTy->isPacked() != SSTy->isPacked())
184 } else if (ArrayType *DATy = dyn_cast<ArrayType>(DstTy)) {
185 if (DATy->getNumElements() != cast<ArrayType>(SrcTy)->getNumElements())
187 } else if (VectorType *DVTy = dyn_cast<VectorType>(DstTy)) {
188 if (DVTy->getNumElements() != cast<VectorType>(SrcTy)->getNumElements())
192 // Otherwise, we speculate that these two types will line up and recursively
193 // check the subelements.
195 SpeculativeTypes.push_back(SrcTy);
197 for (unsigned I = 0, E = SrcTy->getNumContainedTypes(); I != E; ++I)
198 if (!areTypesIsomorphic(DstTy->getContainedType(I),
199 SrcTy->getContainedType(I)))
202 // If everything seems to have lined up, then everything is great.
206 void TypeMapTy::linkDefinedTypeBodies() {
207 SmallVector<Type*, 16> Elements;
208 SmallString<16> TmpName;
210 // Note that processing entries in this loop (calling 'get') can add new
211 // entries to the SrcDefinitionsToResolve vector.
212 while (!SrcDefinitionsToResolve.empty()) {
213 StructType *SrcSTy = SrcDefinitionsToResolve.pop_back_val();
214 StructType *DstSTy = cast<StructType>(MappedTypes[SrcSTy]);
216 // TypeMap is a many-to-one mapping, if there were multiple types that
217 // provide a body for DstSTy then previous iterations of this loop may have
218 // already handled it. Just ignore this case.
219 if (!DstSTy->isOpaque()) continue;
220 assert(!SrcSTy->isOpaque() && "Not resolving a definition?");
222 // Map the body of the source type over to a new body for the dest type.
223 Elements.resize(SrcSTy->getNumElements());
224 for (unsigned I = 0, E = Elements.size(); I != E; ++I)
225 Elements[I] = getImpl(SrcSTy->getElementType(I));
227 DstSTy->setBody(Elements, SrcSTy->isPacked());
229 // If DstSTy has no name or has a longer name than STy, then viciously steal
231 if (!SrcSTy->hasName()) continue;
232 StringRef SrcName = SrcSTy->getName();
234 if (!DstSTy->hasName() || DstSTy->getName().size() > SrcName.size()) {
235 TmpName.insert(TmpName.end(), SrcName.begin(), SrcName.end());
237 DstSTy->setName(TmpName.str());
242 DstResolvedOpaqueTypes.clear();
245 Type *TypeMapTy::get(Type *Ty) {
246 Type *Result = getImpl(Ty);
248 // If this caused a reference to any struct type, resolve it before returning.
249 if (!SrcDefinitionsToResolve.empty())
250 linkDefinedTypeBodies();
254 /// This is the recursive version of get().
255 Type *TypeMapTy::getImpl(Type *Ty) {
256 // If we already have an entry for this type, return it.
257 Type **Entry = &MappedTypes[Ty];
261 // If this is not a named struct type, then just map all of the elements and
262 // then rebuild the type from inside out.
263 if (!isa<StructType>(Ty) || cast<StructType>(Ty)->isLiteral()) {
264 // If there are no element types to map, then the type is itself. This is
265 // true for the anonymous {} struct, things like 'float', integers, etc.
266 if (Ty->getNumContainedTypes() == 0)
269 // Remap all of the elements, keeping track of whether any of them change.
270 bool AnyChange = false;
271 SmallVector<Type*, 4> ElementTypes;
272 ElementTypes.resize(Ty->getNumContainedTypes());
273 for (unsigned I = 0, E = Ty->getNumContainedTypes(); I != E; ++I) {
274 ElementTypes[I] = getImpl(Ty->getContainedType(I));
275 AnyChange |= ElementTypes[I] != Ty->getContainedType(I);
278 // If we found our type while recursively processing stuff, just use it.
279 Entry = &MappedTypes[Ty];
283 // If all of the element types mapped directly over, then the type is usable
288 // Otherwise, rebuild a modified type.
289 switch (Ty->getTypeID()) {
291 llvm_unreachable("unknown derived type to remap");
292 case Type::ArrayTyID:
293 return *Entry = ArrayType::get(ElementTypes[0],
294 cast<ArrayType>(Ty)->getNumElements());
295 case Type::VectorTyID:
296 return *Entry = VectorType::get(ElementTypes[0],
297 cast<VectorType>(Ty)->getNumElements());
298 case Type::PointerTyID:
299 return *Entry = PointerType::get(
300 ElementTypes[0], cast<PointerType>(Ty)->getAddressSpace());
301 case Type::FunctionTyID:
302 return *Entry = FunctionType::get(ElementTypes[0],
303 makeArrayRef(ElementTypes).slice(1),
304 cast<FunctionType>(Ty)->isVarArg());
305 case Type::StructTyID:
306 // Note that this is only reached for anonymous structs.
307 return *Entry = StructType::get(Ty->getContext(), ElementTypes,
308 cast<StructType>(Ty)->isPacked());
312 // Otherwise, this is an unmapped named struct. If the struct can be directly
313 // mapped over, just use it as-is. This happens in a case when the linked-in
314 // module has something like:
315 // %T = type {%T*, i32}
316 // @GV = global %T* null
317 // where T does not exist at all in the destination module.
319 // The other case we watch for is when the type is not in the destination
320 // module, but that it has to be rebuilt because it refers to something that
321 // is already mapped. For example, if the destination module has:
323 // and the source module has something like
324 // %A' = type { i32 }
325 // %B = type { %A'* }
326 // @GV = global %B* null
327 // then we want to create a new type: "%B = type { %A*}" and have it take the
328 // pristine "%B" name from the source module.
330 // To determine which case this is, we have to recursively walk the type graph
331 // speculating that we'll be able to reuse it unmodified. Only if this is
332 // safe would we map the entire thing over. Because this is an optimization,
333 // and is not required for the prettiness of the linked module, we just skip
334 // it and always rebuild a type here.
335 StructType *STy = cast<StructType>(Ty);
337 // If the type is opaque, we can just use it directly.
338 if (STy->isOpaque()) {
339 // A named structure type from src module is used. Add it to the Set of
340 // identified structs in the destination module.
341 DstStructTypesSet.insert(STy);
345 // Otherwise we create a new type and resolve its body later. This will be
346 // resolved by the top level of get().
347 SrcDefinitionsToResolve.push_back(STy);
348 StructType *DTy = StructType::create(STy->getContext());
349 // A new identified structure type was created. Add it to the set of
350 // identified structs in the destination module.
351 DstStructTypesSet.insert(DTy);
352 DstResolvedOpaqueTypes.insert(DTy);
356 //===----------------------------------------------------------------------===//
357 // ModuleLinker implementation.
358 //===----------------------------------------------------------------------===//
363 /// Creates prototypes for functions that are lazily linked on the fly. This
364 /// speeds up linking for modules with many/ lazily linked functions of which
366 class ValueMaterializerTy : public ValueMaterializer {
369 std::vector<Function *> &LazilyLinkFunctions;
372 ValueMaterializerTy(TypeMapTy &TypeMap, Module *DstM,
373 std::vector<Function *> &LazilyLinkFunctions)
374 : ValueMaterializer(), TypeMap(TypeMap), DstM(DstM),
375 LazilyLinkFunctions(LazilyLinkFunctions) {}
377 Value *materializeValueFor(Value *V) override;
380 class LinkDiagnosticInfo : public DiagnosticInfo {
384 LinkDiagnosticInfo(DiagnosticSeverity Severity, const Twine &Msg);
385 void print(DiagnosticPrinter &DP) const override;
387 LinkDiagnosticInfo::LinkDiagnosticInfo(DiagnosticSeverity Severity,
389 : DiagnosticInfo(DK_Linker, Severity), Msg(Msg) {}
390 void LinkDiagnosticInfo::print(DiagnosticPrinter &DP) const { DP << Msg; }
392 /// This is an implementation class for the LinkModules function, which is the
393 /// entrypoint for this file.
398 ValueMaterializerTy ValMaterializer;
400 /// Mapping of values from what they used to be in Src, to what they are now
401 /// in DstM. ValueToValueMapTy is a ValueMap, which involves some overhead
402 /// due to the use of Value handles which the Linker doesn't actually need,
403 /// but this allows us to reuse the ValueMapper code.
404 ValueToValueMapTy ValueMap;
406 struct AppendingVarInfo {
407 GlobalVariable *NewGV; // New aggregate global in dest module.
408 const Constant *DstInit; // Old initializer from dest module.
409 const Constant *SrcInit; // Old initializer from src module.
412 std::vector<AppendingVarInfo> AppendingVars;
414 // Set of items not to link in from source.
415 SmallPtrSet<const Value *, 16> DoNotLinkFromSource;
417 // Vector of functions to lazily link in.
418 std::vector<Function *> LazilyLinkFunctions;
420 Linker::DiagnosticHandlerFunction DiagnosticHandler;
423 ModuleLinker(Module *dstM, TypeSet &Set, Module *srcM,
424 Linker::DiagnosticHandlerFunction DiagnosticHandler)
425 : DstM(dstM), SrcM(srcM), TypeMap(Set),
426 ValMaterializer(TypeMap, DstM, LazilyLinkFunctions),
427 DiagnosticHandler(DiagnosticHandler) {}
432 bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
433 const GlobalValue &Src);
435 /// Helper method for setting a message and returning an error code.
436 bool emitError(const Twine &Message) {
437 DiagnosticHandler(LinkDiagnosticInfo(DS_Error, Message));
441 void emitWarning(const Twine &Message) {
442 DiagnosticHandler(LinkDiagnosticInfo(DS_Warning, Message));
445 bool getComdatLeader(Module *M, StringRef ComdatName,
446 const GlobalVariable *&GVar);
447 bool computeResultingSelectionKind(StringRef ComdatName,
448 Comdat::SelectionKind Src,
449 Comdat::SelectionKind Dst,
450 Comdat::SelectionKind &Result,
452 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
454 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
457 /// Given a global in the source module, return the global in the
458 /// destination module that is being linked to, if any.
459 GlobalValue *getLinkedToGlobal(const GlobalValue *SrcGV) {
460 // If the source has no name it can't link. If it has local linkage,
461 // there is no name match-up going on.
462 if (!SrcGV->hasName() || SrcGV->hasLocalLinkage())
465 // Otherwise see if we have a match in the destination module's symtab.
466 GlobalValue *DGV = DstM->getNamedValue(SrcGV->getName());
470 // If we found a global with the same name in the dest module, but it has
471 // internal linkage, we are really not doing any linkage here.
472 if (DGV->hasLocalLinkage())
475 // Otherwise, we do in fact link to the destination global.
479 void computeTypeMapping();
481 void upgradeMismatchedGlobalArray(StringRef Name);
482 void upgradeMismatchedGlobals();
484 bool linkAppendingVarProto(GlobalVariable *DstGV,
485 const GlobalVariable *SrcGV);
487 bool linkGlobalValueProto(GlobalValue *GV);
488 GlobalValue *linkGlobalVariableProto(const GlobalVariable *SGVar,
489 GlobalValue *DGV, bool LinkFromSrc);
490 GlobalValue *linkFunctionProto(const Function *SF, GlobalValue *DGV,
492 GlobalValue *linkGlobalAliasProto(const GlobalAlias *SGA, GlobalValue *DGV,
495 bool linkModuleFlagsMetadata();
497 void linkAppendingVarInit(const AppendingVarInfo &AVI);
498 void linkGlobalInits();
499 void linkFunctionBody(Function *Dst, Function *Src);
500 void linkAliasBodies();
501 void linkNamedMDNodes();
505 /// The LLVM SymbolTable class autorenames globals that conflict in the symbol
506 /// table. This is good for all clients except for us. Go through the trouble
507 /// to force this back.
508 static void forceRenaming(GlobalValue *GV, StringRef Name) {
509 // If the global doesn't force its name or if it already has the right name,
510 // there is nothing for us to do.
511 if (GV->hasLocalLinkage() || GV->getName() == Name)
514 Module *M = GV->getParent();
516 // If there is a conflict, rename the conflict.
517 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
518 GV->takeName(ConflictGV);
519 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
520 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
522 GV->setName(Name); // Force the name back
526 /// copy additional attributes (those not needed to construct a GlobalValue)
527 /// from the SrcGV to the DestGV.
528 static void copyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) {
529 // Use the maximum alignment, rather than just copying the alignment of SrcGV.
530 auto *DestGO = dyn_cast<GlobalObject>(DestGV);
533 Alignment = std::max(DestGO->getAlignment(), SrcGV->getAlignment());
535 DestGV->copyAttributesFrom(SrcGV);
538 DestGO->setAlignment(Alignment);
540 forceRenaming(DestGV, SrcGV->getName());
543 static bool isLessConstraining(GlobalValue::VisibilityTypes a,
544 GlobalValue::VisibilityTypes b) {
545 if (a == GlobalValue::HiddenVisibility)
547 if (b == GlobalValue::HiddenVisibility)
549 if (a == GlobalValue::ProtectedVisibility)
551 if (b == GlobalValue::ProtectedVisibility)
556 Value *ValueMaterializerTy::materializeValueFor(Value *V) {
557 Function *SF = dyn_cast<Function>(V);
561 Function *DF = Function::Create(TypeMap.get(SF->getFunctionType()),
562 SF->getLinkage(), SF->getName(), DstM);
563 copyGVAttributes(DF, SF);
565 if (Comdat *SC = SF->getComdat()) {
566 Comdat *DC = DstM->getOrInsertComdat(SC->getName());
570 LazilyLinkFunctions.push_back(SF);
574 bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName,
575 const GlobalVariable *&GVar) {
576 const GlobalValue *GVal = M->getNamedValue(ComdatName);
577 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
578 GVal = GA->getBaseObject();
580 // We cannot resolve the size of the aliasee yet.
581 return emitError("Linking COMDATs named '" + ComdatName +
582 "': COMDAT key involves incomputable alias size.");
585 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
588 "Linking COMDATs named '" + ComdatName +
589 "': GlobalVariable required for data dependent selection!");
594 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
595 Comdat::SelectionKind Src,
596 Comdat::SelectionKind Dst,
597 Comdat::SelectionKind &Result,
599 // The ability to mix Comdat::SelectionKind::Any with
600 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
601 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
602 Dst == Comdat::SelectionKind::Largest;
603 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
604 Src == Comdat::SelectionKind::Largest;
605 if (DstAnyOrLargest && SrcAnyOrLargest) {
606 if (Dst == Comdat::SelectionKind::Largest ||
607 Src == Comdat::SelectionKind::Largest)
608 Result = Comdat::SelectionKind::Largest;
610 Result = Comdat::SelectionKind::Any;
611 } else if (Src == Dst) {
614 return emitError("Linking COMDATs named '" + ComdatName +
615 "': invalid selection kinds!");
619 case Comdat::SelectionKind::Any:
623 case Comdat::SelectionKind::NoDuplicates:
624 return emitError("Linking COMDATs named '" + ComdatName +
625 "': noduplicates has been violated!");
626 case Comdat::SelectionKind::ExactMatch:
627 case Comdat::SelectionKind::Largest:
628 case Comdat::SelectionKind::SameSize: {
629 const GlobalVariable *DstGV;
630 const GlobalVariable *SrcGV;
631 if (getComdatLeader(DstM, ComdatName, DstGV) ||
632 getComdatLeader(SrcM, ComdatName, SrcGV))
635 const DataLayout *DstDL = DstM->getDataLayout();
636 const DataLayout *SrcDL = SrcM->getDataLayout();
637 if (!DstDL || !SrcDL) {
639 "Linking COMDATs named '" + ComdatName +
640 "': can't do size dependent selection without DataLayout!");
643 DstDL->getTypeAllocSize(DstGV->getType()->getPointerElementType());
645 SrcDL->getTypeAllocSize(SrcGV->getType()->getPointerElementType());
646 if (Result == Comdat::SelectionKind::ExactMatch) {
647 if (SrcGV->getInitializer() != DstGV->getInitializer())
648 return emitError("Linking COMDATs named '" + ComdatName +
649 "': ExactMatch violated!");
651 } else if (Result == Comdat::SelectionKind::Largest) {
652 LinkFromSrc = SrcSize > DstSize;
653 } else if (Result == Comdat::SelectionKind::SameSize) {
654 if (SrcSize != DstSize)
655 return emitError("Linking COMDATs named '" + ComdatName +
656 "': SameSize violated!");
659 llvm_unreachable("unknown selection kind");
668 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
669 Comdat::SelectionKind &Result,
671 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
672 StringRef ComdatName = SrcC->getName();
673 Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable();
674 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
676 if (DstCI == ComdatSymTab.end()) {
677 // Use the comdat if it is only available in one of the modules.
683 const Comdat *DstC = &DstCI->second;
684 Comdat::SelectionKind DSK = DstC->getSelectionKind();
685 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
689 bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
690 const GlobalValue &Dest,
691 const GlobalValue &Src) {
692 // We always have to add Src if it has appending linkage.
693 if (Src.hasAppendingLinkage()) {
698 bool SrcIsDeclaration = Src.isDeclarationForLinker();
699 bool DestIsDeclaration = Dest.isDeclarationForLinker();
701 if (SrcIsDeclaration) {
702 // If Src is external or if both Src & Dest are external.. Just link the
703 // external globals, we aren't adding anything.
704 if (Src.hasDLLImportStorageClass()) {
705 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
706 LinkFromSrc = DestIsDeclaration;
709 // If the Dest is weak, use the source linkage.
710 LinkFromSrc = Dest.hasExternalWeakLinkage();
714 if (DestIsDeclaration) {
715 // If Dest is external but Src is not:
720 if (Src.hasCommonLinkage()) {
721 if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
726 if (!Dest.hasCommonLinkage()) {
731 // FIXME: Make datalayout mandatory and just use getDataLayout().
732 DataLayout DL(Dest.getParent());
734 uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
735 uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
736 LinkFromSrc = SrcSize > DestSize;
740 if (Src.isWeakForLinker()) {
741 assert(!Dest.hasExternalWeakLinkage());
742 assert(!Dest.hasAvailableExternallyLinkage());
744 if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
753 if (Dest.isWeakForLinker()) {
754 assert(Src.hasExternalLinkage());
759 assert(!Src.hasExternalWeakLinkage());
760 assert(!Dest.hasExternalWeakLinkage());
761 assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
762 "Unexpected linkage type!");
763 return emitError("Linking globals named '" + Src.getName() +
764 "': symbol multiply defined!");
767 /// Loop over all of the linked values to compute type mappings. For example,
768 /// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct
769 /// types 'Foo' but one got renamed when the module was loaded into the same
771 void ModuleLinker::computeTypeMapping() {
772 for (GlobalValue &SGV : SrcM->globals()) {
773 GlobalValue *DGV = getLinkedToGlobal(&SGV);
777 if (!DGV->hasAppendingLinkage() || !SGV.hasAppendingLinkage()) {
778 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
782 // Unify the element type of appending arrays.
783 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
784 ArrayType *SAT = cast<ArrayType>(SGV.getType()->getElementType());
785 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
788 for (GlobalValue &SGV : *SrcM) {
789 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
790 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
793 for (GlobalValue &SGV : SrcM->aliases()) {
794 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
795 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
798 // Incorporate types by name, scanning all the types in the source module.
799 // At this point, the destination module may have a type "%foo = { i32 }" for
800 // example. When the source module got loaded into the same LLVMContext, if
801 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
802 TypeFinder SrcStructTypes;
803 SrcStructTypes.run(*SrcM, true);
804 SmallPtrSet<StructType*, 32> SrcStructTypesSet(SrcStructTypes.begin(),
805 SrcStructTypes.end());
807 for (unsigned i = 0, e = SrcStructTypes.size(); i != e; ++i) {
808 StructType *ST = SrcStructTypes[i];
809 if (!ST->hasName()) continue;
811 // Check to see if there is a dot in the name followed by a digit.
812 size_t DotPos = ST->getName().rfind('.');
813 if (DotPos == 0 || DotPos == StringRef::npos ||
814 ST->getName().back() == '.' ||
815 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos+1])))
818 // Check to see if the destination module has a struct with the prefix name.
819 if (StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos)))
820 // Don't use it if this actually came from the source module. They're in
821 // the same LLVMContext after all. Also don't use it unless the type is
822 // actually used in the destination module. This can happen in situations
827 // %Z = type { %A } %B = type { %C.1 }
828 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
829 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
830 // %C = type { i8* } %B.3 = type { %C.1 }
832 // When we link Module B with Module A, the '%B' in Module B is
833 // used. However, that would then use '%C.1'. But when we process '%C.1',
834 // we prefer to take the '%C' version. So we are then left with both
835 // '%C.1' and '%C' being used for the same types. This leads to some
836 // variables using one type and some using the other.
837 if (!SrcStructTypesSet.count(DST) && TypeMap.DstStructTypesSet.count(DST))
838 TypeMap.addTypeMapping(DST, ST);
841 // Now that we have discovered all of the type equivalences, get a body for
842 // any 'opaque' types in the dest module that are now resolved.
843 TypeMap.linkDefinedTypeBodies();
846 static void upgradeGlobalArray(GlobalVariable *GV) {
847 ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
848 StructType *OldTy = cast<StructType>(ATy->getElementType());
849 assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
851 // Get the upgraded 3 element type.
852 PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
853 Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
855 StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
857 // Build new constants with a null third field filled in.
858 Constant *OldInitC = GV->getInitializer();
859 ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
860 if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
861 // Invalid initializer; give up.
863 std::vector<Constant *> Initializers;
864 if (OldInit && OldInit->getNumOperands()) {
865 Value *Null = Constant::getNullValue(VoidPtrTy);
866 for (Use &U : OldInit->operands()) {
867 ConstantStruct *Init = cast<ConstantStruct>(U.get());
868 Initializers.push_back(ConstantStruct::get(
869 NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
872 assert(Initializers.size() == ATy->getNumElements() &&
873 "Failed to copy all array elements");
875 // Replace the old GV with a new one.
876 ATy = ArrayType::get(NewTy, Initializers.size());
877 Constant *NewInit = ConstantArray::get(ATy, Initializers);
878 GlobalVariable *NewGV = new GlobalVariable(
879 *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
880 GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
881 GV->isExternallyInitialized());
882 NewGV->copyAttributesFrom(GV);
884 assert(GV->use_empty() && "program cannot use initializer list");
885 GV->eraseFromParent();
888 void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
889 // Look for the global arrays.
890 auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM->getNamedValue(Name));
893 auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM->getNamedValue(Name));
897 // Check if the types already match.
898 auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
900 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
904 // Grab the element types. We can only upgrade an array of a two-field
905 // struct. Only bother if the other one has three-fields.
906 auto *DstEltTy = cast<StructType>(DstTy->getElementType());
907 auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
908 if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
909 upgradeGlobalArray(DstGV);
912 if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
913 upgradeGlobalArray(SrcGV);
915 // We can't upgrade any other differences.
918 void ModuleLinker::upgradeMismatchedGlobals() {
919 upgradeMismatchedGlobalArray("llvm.global_ctors");
920 upgradeMismatchedGlobalArray("llvm.global_dtors");
923 /// If there were any appending global variables, link them together now.
924 /// Return true on error.
925 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
926 const GlobalVariable *SrcGV) {
928 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
929 return emitError("Linking globals named '" + SrcGV->getName() +
930 "': can only link appending global with another appending global!");
932 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
934 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
935 Type *EltTy = DstTy->getElementType();
937 // Check to see that they two arrays agree on type.
938 if (EltTy != SrcTy->getElementType())
939 return emitError("Appending variables with different element types!");
940 if (DstGV->isConstant() != SrcGV->isConstant())
941 return emitError("Appending variables linked with different const'ness!");
943 if (DstGV->getAlignment() != SrcGV->getAlignment())
945 "Appending variables with different alignment need to be linked!");
947 if (DstGV->getVisibility() != SrcGV->getVisibility())
949 "Appending variables with different visibility need to be linked!");
951 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
953 "Appending variables with different unnamed_addr need to be linked!");
955 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
957 "Appending variables with different section name need to be linked!");
959 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements();
960 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
962 // Create the new global variable.
964 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(),
965 DstGV->getLinkage(), /*init*/nullptr, /*name*/"", DstGV,
966 DstGV->getThreadLocalMode(),
967 DstGV->getType()->getAddressSpace());
969 // Propagate alignment, visibility and section info.
970 copyGVAttributes(NG, DstGV);
972 AppendingVarInfo AVI;
974 AVI.DstInit = DstGV->getInitializer();
975 AVI.SrcInit = SrcGV->getInitializer();
976 AppendingVars.push_back(AVI);
978 // Replace any uses of the two global variables with uses of the new
980 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
982 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
983 DstGV->eraseFromParent();
985 // Track the source variable so we don't try to link it.
986 DoNotLinkFromSource.insert(SrcGV);
991 bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) {
992 GlobalValue *DGV = getLinkedToGlobal(SGV);
994 // Handle the ultra special appending linkage case first.
995 if (DGV && DGV->hasAppendingLinkage())
996 return linkAppendingVarProto(cast<GlobalVariable>(DGV),
997 cast<GlobalVariable>(SGV));
999 bool LinkFromSrc = true;
1000 Comdat *C = nullptr;
1001 GlobalValue::VisibilityTypes Visibility = SGV->getVisibility();
1002 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
1004 if (const Comdat *SC = SGV->getComdat()) {
1005 Comdat::SelectionKind SK;
1006 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1007 C = DstM->getOrInsertComdat(SC->getName());
1008 C->setSelectionKind(SK);
1010 if (shouldLinkFromSource(LinkFromSrc, *DGV, *SGV))
1015 // Track the source global so that we don't attempt to copy it over when
1016 // processing global initializers.
1017 DoNotLinkFromSource.insert(SGV);
1020 // Make sure to remember this mapping.
1022 ConstantExpr::getBitCast(DGV, TypeMap.get(SGV->getType()));
1026 Visibility = isLessConstraining(Visibility, DGV->getVisibility())
1027 ? DGV->getVisibility()
1029 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1032 if (!LinkFromSrc && !DGV)
1036 if (auto *SGVar = dyn_cast<GlobalVariable>(SGV)) {
1037 NewGV = linkGlobalVariableProto(SGVar, DGV, LinkFromSrc);
1040 } else if (auto *SF = dyn_cast<Function>(SGV)) {
1041 NewGV = linkFunctionProto(SF, DGV, LinkFromSrc);
1043 NewGV = linkGlobalAliasProto(cast<GlobalAlias>(SGV), DGV, LinkFromSrc);
1048 copyGVAttributes(NewGV, SGV);
1050 NewGV->setUnnamedAddr(HasUnnamedAddr);
1051 NewGV->setVisibility(Visibility);
1053 if (auto *NewGO = dyn_cast<GlobalObject>(NewGV)) {
1055 NewGO->setComdat(C);
1058 // Make sure to remember this mapping.
1061 DGV->replaceAllUsesWith(
1062 ConstantExpr::getBitCast(NewGV, DGV->getType()));
1063 DGV->eraseFromParent();
1065 ValueMap[SGV] = NewGV;
1072 /// Loop through the global variables in the src module and merge them into the
1074 GlobalValue *ModuleLinker::linkGlobalVariableProto(const GlobalVariable *SGVar,
1077 unsigned Alignment = 0;
1078 bool ClearConstant = false;
1081 if (DGV->hasCommonLinkage() && SGVar->hasCommonLinkage())
1082 Alignment = std::max(SGVar->getAlignment(), DGV->getAlignment());
1084 auto *DGVar = dyn_cast<GlobalVariable>(DGV);
1085 if (!SGVar->isConstant() || (DGVar && !DGVar->isConstant()))
1086 ClearConstant = true;
1090 if (auto *NewGVar = dyn_cast<GlobalVariable>(DGV)) {
1092 NewGVar->setAlignment(Alignment);
1093 if (NewGVar->isDeclaration() && ClearConstant)
1094 NewGVar->setConstant(false);
1099 // No linking to be performed or linking from the source: simply create an
1100 // identical version of the symbol over in the dest module... the
1101 // initializer will be filled in later by LinkGlobalInits.
1102 GlobalVariable *NewDGV = new GlobalVariable(
1103 *DstM, TypeMap.get(SGVar->getType()->getElementType()),
1104 SGVar->isConstant(), SGVar->getLinkage(), /*init*/ nullptr,
1105 SGVar->getName(), /*insertbefore*/ nullptr, SGVar->getThreadLocalMode(),
1106 SGVar->getType()->getAddressSpace());
1109 NewDGV->setAlignment(Alignment);
1114 /// Link the function in the source module into the destination module if
1115 /// needed, setting up mapping information.
1116 GlobalValue *ModuleLinker::linkFunctionProto(const Function *SF,
1122 // If the function is to be lazily linked, don't create it just yet.
1123 // The ValueMaterializerTy will deal with creating it if it's used.
1124 if (!DGV && (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() ||
1125 SF->hasAvailableExternallyLinkage())) {
1126 DoNotLinkFromSource.insert(SF);
1130 // If there is no linkage to be performed or we are linking from the source,
1132 return Function::Create(TypeMap.get(SF->getFunctionType()), SF->getLinkage(),
1133 SF->getName(), DstM);
1136 /// Set up prototypes for any aliases that come over from the source module.
1137 GlobalValue *ModuleLinker::linkGlobalAliasProto(const GlobalAlias *SGA,
1143 // If there is no linkage to be performed or we're linking from the source,
1145 auto *PTy = cast<PointerType>(TypeMap.get(SGA->getType()));
1146 return GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(),
1147 SGA->getLinkage(), SGA->getName(), DstM);
1150 static void getArrayElements(const Constant *C,
1151 SmallVectorImpl<Constant *> &Dest) {
1152 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1154 for (unsigned i = 0; i != NumElements; ++i)
1155 Dest.push_back(C->getAggregateElement(i));
1158 void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) {
1159 // Merge the initializer.
1160 SmallVector<Constant *, 16> DstElements;
1161 getArrayElements(AVI.DstInit, DstElements);
1163 SmallVector<Constant *, 16> SrcElements;
1164 getArrayElements(AVI.SrcInit, SrcElements);
1166 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
1168 StringRef Name = AVI.NewGV->getName();
1169 bool IsNewStructor =
1170 (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
1171 cast<StructType>(NewType->getElementType())->getNumElements() == 3;
1173 for (auto *V : SrcElements) {
1174 if (IsNewStructor) {
1175 Constant *Key = V->getAggregateElement(2);
1176 if (DoNotLinkFromSource.count(Key))
1179 DstElements.push_back(
1180 MapValue(V, ValueMap, RF_None, &TypeMap, &ValMaterializer));
1182 if (IsNewStructor) {
1183 NewType = ArrayType::get(NewType->getElementType(), DstElements.size());
1184 AVI.NewGV->mutateType(PointerType::get(NewType, 0));
1187 AVI.NewGV->setInitializer(ConstantArray::get(NewType, DstElements));
1190 /// Update the initializers in the Dest module now that all globals that may be
1191 /// referenced are in Dest.
1192 void ModuleLinker::linkGlobalInits() {
1193 // Loop over all of the globals in the src module, mapping them over as we go
1194 for (Module::const_global_iterator I = SrcM->global_begin(),
1195 E = SrcM->global_end(); I != E; ++I) {
1197 // Only process initialized GV's or ones not already in dest.
1198 if (!I->hasInitializer() || DoNotLinkFromSource.count(I)) continue;
1200 // Grab destination global variable.
1201 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[I]);
1202 // Figure out what the initializer looks like in the dest module.
1203 DGV->setInitializer(MapValue(I->getInitializer(), ValueMap,
1204 RF_None, &TypeMap, &ValMaterializer));
1208 /// Copy the source function over into the dest function and fix up references
1209 /// to values. At this point we know that Dest is an external function, and
1210 /// that Src is not.
1211 void ModuleLinker::linkFunctionBody(Function *Dst, Function *Src) {
1212 assert(Src && Dst && Dst->isDeclaration() && !Src->isDeclaration());
1214 // Go through and convert function arguments over, remembering the mapping.
1215 Function::arg_iterator DI = Dst->arg_begin();
1216 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1217 I != E; ++I, ++DI) {
1218 DI->setName(I->getName()); // Copy the name over.
1220 // Add a mapping to our mapping.
1224 // Splice the body of the source function into the dest function.
1225 Dst->getBasicBlockList().splice(Dst->end(), Src->getBasicBlockList());
1227 // At this point, all of the instructions and values of the function are now
1228 // copied over. The only problem is that they are still referencing values in
1229 // the Source function as operands. Loop through all of the operands of the
1230 // functions and patch them up to point to the local versions.
1231 for (Function::iterator BB = Dst->begin(), BE = Dst->end(); BB != BE; ++BB)
1232 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
1233 RemapInstruction(I, ValueMap, RF_IgnoreMissingEntries, &TypeMap,
1236 // There is no need to map the arguments anymore.
1237 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1243 /// Insert all of the aliases in Src into the Dest module.
1244 void ModuleLinker::linkAliasBodies() {
1245 for (Module::alias_iterator I = SrcM->alias_begin(), E = SrcM->alias_end();
1247 if (DoNotLinkFromSource.count(I))
1249 if (Constant *Aliasee = I->getAliasee()) {
1250 GlobalAlias *DA = cast<GlobalAlias>(ValueMap[I]);
1252 MapValue(Aliasee, ValueMap, RF_None, &TypeMap, &ValMaterializer);
1253 DA->setAliasee(Val);
1258 /// Insert all of the named MDNodes in Src into the Dest module.
1259 void ModuleLinker::linkNamedMDNodes() {
1260 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1261 for (Module::const_named_metadata_iterator I = SrcM->named_metadata_begin(),
1262 E = SrcM->named_metadata_end(); I != E; ++I) {
1263 // Don't link module flags here. Do them separately.
1264 if (&*I == SrcModFlags) continue;
1265 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(I->getName());
1266 // Add Src elements into Dest node.
1267 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
1268 DestNMD->addOperand(MapValue(I->getOperand(i), ValueMap,
1269 RF_None, &TypeMap, &ValMaterializer));
1273 /// Merge the linker flags in Src into the Dest module.
1274 bool ModuleLinker::linkModuleFlagsMetadata() {
1275 // If the source module has no module flags, we are done.
1276 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1277 if (!SrcModFlags) return false;
1279 // If the destination module doesn't have module flags yet, then just copy
1280 // over the source module's flags.
1281 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
1282 if (DstModFlags->getNumOperands() == 0) {
1283 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1284 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1289 // First build a map of the existing module flags and requirements.
1290 DenseMap<MDString*, MDNode*> Flags;
1291 SmallSetVector<MDNode*, 16> Requirements;
1292 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1293 MDNode *Op = DstModFlags->getOperand(I);
1294 ConstantInt *Behavior = cast<ConstantInt>(Op->getOperand(0));
1295 MDString *ID = cast<MDString>(Op->getOperand(1));
1297 if (Behavior->getZExtValue() == Module::Require) {
1298 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1304 // Merge in the flags from the source module, and also collect its set of
1306 bool HasErr = false;
1307 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1308 MDNode *SrcOp = SrcModFlags->getOperand(I);
1309 ConstantInt *SrcBehavior = cast<ConstantInt>(SrcOp->getOperand(0));
1310 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1311 MDNode *DstOp = Flags.lookup(ID);
1312 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1314 // If this is a requirement, add it and continue.
1315 if (SrcBehaviorValue == Module::Require) {
1316 // If the destination module does not already have this requirement, add
1318 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1319 DstModFlags->addOperand(SrcOp);
1324 // If there is no existing flag with this ID, just add it.
1327 DstModFlags->addOperand(SrcOp);
1331 // Otherwise, perform a merge.
1332 ConstantInt *DstBehavior = cast<ConstantInt>(DstOp->getOperand(0));
1333 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1335 // If either flag has override behavior, handle it first.
1336 if (DstBehaviorValue == Module::Override) {
1337 // Diagnose inconsistent flags which both have override behavior.
1338 if (SrcBehaviorValue == Module::Override &&
1339 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1340 HasErr |= emitError("linking module flags '" + ID->getString() +
1341 "': IDs have conflicting override values");
1344 } else if (SrcBehaviorValue == Module::Override) {
1345 // Update the destination flag to that of the source.
1346 DstOp->replaceOperandWith(0, SrcBehavior);
1347 DstOp->replaceOperandWith(2, SrcOp->getOperand(2));
1351 // Diagnose inconsistent merge behavior types.
1352 if (SrcBehaviorValue != DstBehaviorValue) {
1353 HasErr |= emitError("linking module flags '" + ID->getString() +
1354 "': IDs have conflicting behaviors");
1358 // Perform the merge for standard behavior types.
1359 switch (SrcBehaviorValue) {
1360 case Module::Require:
1361 case Module::Override: llvm_unreachable("not possible");
1362 case Module::Error: {
1363 // Emit an error if the values differ.
1364 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1365 HasErr |= emitError("linking module flags '" + ID->getString() +
1366 "': IDs have conflicting values");
1370 case Module::Warning: {
1371 // Emit a warning if the values differ.
1372 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1373 emitWarning("linking module flags '" + ID->getString() +
1374 "': IDs have conflicting values");
1378 case Module::Append: {
1379 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1380 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1381 unsigned NumOps = DstValue->getNumOperands() + SrcValue->getNumOperands();
1382 Value **VP, **Values = VP = new Value*[NumOps];
1383 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i, ++VP)
1384 *VP = DstValue->getOperand(i);
1385 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i, ++VP)
1386 *VP = SrcValue->getOperand(i);
1387 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1388 ArrayRef<Value*>(Values,
1393 case Module::AppendUnique: {
1394 SmallSetVector<Value*, 16> Elts;
1395 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1396 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1397 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i)
1398 Elts.insert(DstValue->getOperand(i));
1399 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i)
1400 Elts.insert(SrcValue->getOperand(i));
1401 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1402 ArrayRef<Value*>(Elts.begin(),
1409 // Check all of the requirements.
1410 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1411 MDNode *Requirement = Requirements[I];
1412 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1413 Value *ReqValue = Requirement->getOperand(1);
1415 MDNode *Op = Flags[Flag];
1416 if (!Op || Op->getOperand(2) != ReqValue) {
1417 HasErr |= emitError("linking module flags '" + Flag->getString() +
1418 "': does not have the required value");
1426 bool ModuleLinker::run() {
1427 assert(DstM && "Null destination module");
1428 assert(SrcM && "Null source module");
1430 // Inherit the target data from the source module if the destination module
1431 // doesn't have one already.
1432 if (!DstM->getDataLayout() && SrcM->getDataLayout())
1433 DstM->setDataLayout(SrcM->getDataLayout());
1435 // Copy the target triple from the source to dest if the dest's is empty.
1436 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
1437 DstM->setTargetTriple(SrcM->getTargetTriple());
1439 if (SrcM->getDataLayout() && DstM->getDataLayout() &&
1440 *SrcM->getDataLayout() != *DstM->getDataLayout()) {
1441 emitWarning("Linking two modules of different data layouts: '" +
1442 SrcM->getModuleIdentifier() + "' is '" +
1443 SrcM->getDataLayoutStr() + "' whereas '" +
1444 DstM->getModuleIdentifier() + "' is '" +
1445 DstM->getDataLayoutStr() + "'\n");
1447 if (!SrcM->getTargetTriple().empty() &&
1448 DstM->getTargetTriple() != SrcM->getTargetTriple()) {
1449 emitWarning("Linking two modules of different target triples: " +
1450 SrcM->getModuleIdentifier() + "' is '" +
1451 SrcM->getTargetTriple() + "' whereas '" +
1452 DstM->getModuleIdentifier() + "' is '" +
1453 DstM->getTargetTriple() + "'\n");
1456 // Append the module inline asm string.
1457 if (!SrcM->getModuleInlineAsm().empty()) {
1458 if (DstM->getModuleInlineAsm().empty())
1459 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
1461 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
1462 SrcM->getModuleInlineAsm());
1465 // Loop over all of the linked values to compute type mappings.
1466 computeTypeMapping();
1468 ComdatsChosen.clear();
1469 for (const auto &SMEC : SrcM->getComdatSymbolTable()) {
1470 const Comdat &C = SMEC.getValue();
1471 if (ComdatsChosen.count(&C))
1473 Comdat::SelectionKind SK;
1475 if (getComdatResult(&C, SK, LinkFromSrc))
1477 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1480 // Upgrade mismatched global arrays.
1481 upgradeMismatchedGlobals();
1483 // Insert all of the globals in src into the DstM module... without linking
1484 // initializers (which could refer to functions not yet mapped over).
1485 for (Module::global_iterator I = SrcM->global_begin(),
1486 E = SrcM->global_end(); I != E; ++I)
1487 if (linkGlobalValueProto(I))
1490 // Link the functions together between the two modules, without doing function
1491 // bodies... this just adds external function prototypes to the DstM
1492 // function... We do this so that when we begin processing function bodies,
1493 // all of the global values that may be referenced are available in our
1495 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I)
1496 if (linkGlobalValueProto(I))
1499 // If there were any aliases, link them now.
1500 for (Module::alias_iterator I = SrcM->alias_begin(),
1501 E = SrcM->alias_end(); I != E; ++I)
1502 if (linkGlobalValueProto(I))
1505 for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i)
1506 linkAppendingVarInit(AppendingVars[i]);
1508 // Link in the function bodies that are defined in the source module into
1510 for (Module::iterator SF = SrcM->begin(), E = SrcM->end(); SF != E; ++SF) {
1511 // Skip if not linking from source.
1512 if (DoNotLinkFromSource.count(SF)) continue;
1514 Function *DF = cast<Function>(ValueMap[SF]);
1515 if (SF->hasPrefixData()) {
1516 // Link in the prefix data.
1517 DF->setPrefixData(MapValue(
1518 SF->getPrefixData(), ValueMap, RF_None, &TypeMap, &ValMaterializer));
1521 // Materialize if needed.
1522 if (std::error_code EC = SF->materialize())
1523 return emitError(EC.message());
1525 // Skip if no body (function is external).
1526 if (SF->isDeclaration())
1529 linkFunctionBody(DF, SF);
1530 SF->Dematerialize();
1533 // Resolve all uses of aliases with aliasees.
1536 // Remap all of the named MDNodes in Src into the DstM module. We do this
1537 // after linking GlobalValues so that MDNodes that reference GlobalValues
1538 // are properly remapped.
1541 // Merge the module flags into the DstM module.
1542 if (linkModuleFlagsMetadata())
1545 // Update the initializers in the DstM module now that all globals that may
1546 // be referenced are in DstM.
1549 // Process vector of lazily linked in functions.
1550 bool LinkedInAnyFunctions;
1552 LinkedInAnyFunctions = false;
1554 for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(),
1555 E = LazilyLinkFunctions.end(); I != E; ++I) {
1560 Function *DF = cast<Function>(ValueMap[SF]);
1561 if (SF->hasPrefixData()) {
1562 // Link in the prefix data.
1563 DF->setPrefixData(MapValue(SF->getPrefixData(),
1570 // Materialize if needed.
1571 if (std::error_code EC = SF->materialize())
1572 return emitError(EC.message());
1574 // Skip if no body (function is external).
1575 if (SF->isDeclaration())
1578 // Erase from vector *before* the function body is linked - linkFunctionBody could
1580 LazilyLinkFunctions.erase(I);
1582 // Link in function body.
1583 linkFunctionBody(DF, SF);
1584 SF->Dematerialize();
1586 // Set flag to indicate we may have more functions to lazily link in
1587 // since we linked in a function.
1588 LinkedInAnyFunctions = true;
1591 } while (LinkedInAnyFunctions);
1593 // Now that all of the types from the source are used, resolve any structs
1594 // copied over to the dest that didn't exist there.
1595 TypeMap.linkDefinedTypeBodies();
1600 void Linker::init(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
1601 this->Composite = M;
1602 this->DiagnosticHandler = DiagnosticHandler;
1604 TypeFinder StructTypes;
1605 StructTypes.run(*M, true);
1606 IdentifiedStructTypes.insert(StructTypes.begin(), StructTypes.end());
1609 Linker::Linker(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
1610 init(M, DiagnosticHandler);
1613 Linker::Linker(Module *M) {
1614 init(M, [this](const DiagnosticInfo &DI) {
1615 Composite->getContext().diagnose(DI);
1622 void Linker::deleteModule() {
1624 Composite = nullptr;
1627 bool Linker::linkInModule(Module *Src) {
1628 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,
1630 return TheLinker.run();
1633 //===----------------------------------------------------------------------===//
1634 // LinkModules entrypoint.
1635 //===----------------------------------------------------------------------===//
1637 /// This function links two modules together, with the resulting Dest module
1638 /// modified to be the composite of the two input modules. If an error occurs,
1639 /// true is returned and ErrorMsg (if not null) is set to indicate the problem.
1640 /// Upon failure, the Dest module could be in a modified state, and shouldn't be
1641 /// relied on to be consistent.
1642 bool Linker::LinkModules(Module *Dest, Module *Src,
1643 DiagnosticHandlerFunction DiagnosticHandler) {
1644 Linker L(Dest, DiagnosticHandler);
1645 return L.linkInModule(Src);
1648 bool Linker::LinkModules(Module *Dest, Module *Src) {
1650 return L.linkInModule(Src);
1653 //===----------------------------------------------------------------------===//
1655 //===----------------------------------------------------------------------===//
1657 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
1658 LLVMLinkerMode Mode, char **OutMessages) {
1659 Module *D = unwrap(Dest);
1660 std::string Message;
1661 raw_string_ostream Stream(Message);
1662 DiagnosticPrinterRawOStream DP(Stream);
1664 LLVMBool Result = Linker::LinkModules(
1665 D, unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); });
1667 if (OutMessages && Result)
1668 *OutMessages = strdup(Message.c_str());