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) {return cast<FunctionType>(get((Type*)T));}
76 /// Dump out the type map for debugging purposes.
78 for (auto &Pair : MappedTypes) {
79 dbgs() << "TypeMap: ";
80 Pair.first->print(dbgs());
82 Pair.second->print(dbgs());
88 Type *getImpl(Type *T);
89 /// Implement the ValueMapTypeRemapper interface.
90 Type *remapType(Type *SrcTy) override {
94 bool areTypesIsomorphic(Type *DstTy, Type *SrcTy);
98 void TypeMapTy::addTypeMapping(Type *DstTy, Type *SrcTy) {
99 // Check to see if these types are recursively isomorphic and establish a
100 // mapping between them if so.
101 if (areTypesIsomorphic(DstTy, SrcTy)) {
102 SpeculativeTypes.clear();
106 // Oops, they aren't isomorphic. Just discard this request by rolling out
107 // any speculative mappings we've established.
108 unsigned Removed = 0;
109 for (unsigned I = 0, E = SpeculativeTypes.size(); I != E; ++I) {
110 Type *SrcTy = SpeculativeTypes[I];
111 auto Iter = MappedTypes.find(SrcTy);
112 auto *DstTy = dyn_cast<StructType>(Iter->second);
113 if (DstTy && DstResolvedOpaqueTypes.erase(DstTy))
115 MappedTypes.erase(Iter);
117 SrcDefinitionsToResolve.resize(SrcDefinitionsToResolve.size() - Removed);
118 SpeculativeTypes.clear();
121 /// Recursively walk this pair of types, returning true if they are isomorphic,
122 /// false if they are not.
123 bool TypeMapTy::areTypesIsomorphic(Type *DstTy, Type *SrcTy) {
124 // Two types with differing kinds are clearly not isomorphic.
125 if (DstTy->getTypeID() != SrcTy->getTypeID()) return false;
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];
258 if (*Entry) return *Entry;
260 // If this is not a named struct type, then just map all of the elements and
261 // then rebuild the type from inside out.
262 if (!isa<StructType>(Ty) || cast<StructType>(Ty)->isLiteral()) {
263 // If there are no element types to map, then the type is itself. This is
264 // true for the anonymous {} struct, things like 'float', integers, etc.
265 if (Ty->getNumContainedTypes() == 0)
268 // Remap all of the elements, keeping track of whether any of them change.
269 bool AnyChange = false;
270 SmallVector<Type*, 4> ElementTypes;
271 ElementTypes.resize(Ty->getNumContainedTypes());
272 for (unsigned i = 0, e = Ty->getNumContainedTypes(); i != e; ++i) {
273 ElementTypes[i] = getImpl(Ty->getContainedType(i));
274 AnyChange |= ElementTypes[i] != Ty->getContainedType(i);
277 // If we found our type while recursively processing stuff, just use it.
278 Entry = &MappedTypes[Ty];
279 if (*Entry) return *Entry;
281 // If all of the element types mapped directly over, then the type is usable
286 // Otherwise, rebuild a modified type.
287 switch (Ty->getTypeID()) {
288 default: llvm_unreachable("unknown derived type to remap");
289 case Type::ArrayTyID:
290 return *Entry = ArrayType::get(ElementTypes[0],
291 cast<ArrayType>(Ty)->getNumElements());
292 case Type::VectorTyID:
293 return *Entry = VectorType::get(ElementTypes[0],
294 cast<VectorType>(Ty)->getNumElements());
295 case Type::PointerTyID:
296 return *Entry = PointerType::get(ElementTypes[0],
297 cast<PointerType>(Ty)->getAddressSpace());
298 case Type::FunctionTyID:
299 return *Entry = FunctionType::get(ElementTypes[0],
300 makeArrayRef(ElementTypes).slice(1),
301 cast<FunctionType>(Ty)->isVarArg());
302 case Type::StructTyID:
303 // Note that this is only reached for anonymous structs.
304 return *Entry = StructType::get(Ty->getContext(), ElementTypes,
305 cast<StructType>(Ty)->isPacked());
309 // Otherwise, this is an unmapped named struct. If the struct can be directly
310 // mapped over, just use it as-is. This happens in a case when the linked-in
311 // module has something like:
312 // %T = type {%T*, i32}
313 // @GV = global %T* null
314 // where T does not exist at all in the destination module.
316 // The other case we watch for is when the type is not in the destination
317 // module, but that it has to be rebuilt because it refers to something that
318 // is already mapped. For example, if the destination module has:
320 // and the source module has something like
321 // %A' = type { i32 }
322 // %B = type { %A'* }
323 // @GV = global %B* null
324 // then we want to create a new type: "%B = type { %A*}" and have it take the
325 // pristine "%B" name from the source module.
327 // To determine which case this is, we have to recursively walk the type graph
328 // speculating that we'll be able to reuse it unmodified. Only if this is
329 // safe would we map the entire thing over. Because this is an optimization,
330 // and is not required for the prettiness of the linked module, we just skip
331 // it and always rebuild a type here.
332 StructType *STy = cast<StructType>(Ty);
334 // If the type is opaque, we can just use it directly.
335 if (STy->isOpaque()) {
336 // A named structure type from src module is used. Add it to the Set of
337 // identified structs in the destination module.
338 DstStructTypesSet.insert(STy);
342 // Otherwise we create a new type and resolve its body later. This will be
343 // resolved by the top level of get().
344 SrcDefinitionsToResolve.push_back(STy);
345 StructType *DTy = StructType::create(STy->getContext());
346 // A new identified structure type was created. Add it to the set of
347 // identified structs in the destination module.
348 DstStructTypesSet.insert(DTy);
349 DstResolvedOpaqueTypes.insert(DTy);
353 //===----------------------------------------------------------------------===//
354 // ModuleLinker implementation.
355 //===----------------------------------------------------------------------===//
360 /// Creates prototypes for functions that are lazily linked on the fly. This
361 /// speeds up linking for modules with many/ lazily linked functions of which
363 class ValueMaterializerTy : public ValueMaterializer {
366 std::vector<Function *> &LazilyLinkFunctions;
369 ValueMaterializerTy(TypeMapTy &TypeMap, Module *DstM,
370 std::vector<Function *> &LazilyLinkFunctions)
371 : ValueMaterializer(), TypeMap(TypeMap), DstM(DstM),
372 LazilyLinkFunctions(LazilyLinkFunctions) {}
374 Value *materializeValueFor(Value *V) override;
377 class LinkDiagnosticInfo : public DiagnosticInfo {
381 LinkDiagnosticInfo(DiagnosticSeverity Severity, const Twine &Msg);
382 void print(DiagnosticPrinter &DP) const override;
384 LinkDiagnosticInfo::LinkDiagnosticInfo(DiagnosticSeverity Severity,
386 : DiagnosticInfo(DK_Linker, Severity), Msg(Msg) {}
387 void LinkDiagnosticInfo::print(DiagnosticPrinter &DP) const { DP << Msg; }
389 /// This is an implementation class for the LinkModules function, which is the
390 /// entrypoint for this file.
395 ValueMaterializerTy ValMaterializer;
397 /// Mapping of values from what they used to be in Src, to what they are now
398 /// in DstM. ValueToValueMapTy is a ValueMap, which involves some overhead
399 /// due to the use of Value handles which the Linker doesn't actually need,
400 /// but this allows us to reuse the ValueMapper code.
401 ValueToValueMapTy ValueMap;
403 struct AppendingVarInfo {
404 GlobalVariable *NewGV; // New aggregate global in dest module.
405 const Constant *DstInit; // Old initializer from dest module.
406 const Constant *SrcInit; // Old initializer from src module.
409 std::vector<AppendingVarInfo> AppendingVars;
411 // Set of items not to link in from source.
412 SmallPtrSet<const Value *, 16> DoNotLinkFromSource;
414 // Vector of functions to lazily link in.
415 std::vector<Function *> LazilyLinkFunctions;
417 Linker::DiagnosticHandlerFunction DiagnosticHandler;
420 ModuleLinker(Module *dstM, TypeSet &Set, Module *srcM,
421 Linker::DiagnosticHandlerFunction DiagnosticHandler)
422 : DstM(dstM), SrcM(srcM), TypeMap(Set),
423 ValMaterializer(TypeMap, DstM, LazilyLinkFunctions),
424 DiagnosticHandler(DiagnosticHandler) {}
429 bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
430 const GlobalValue &Src);
432 /// Helper method for setting a message and returning an error code.
433 bool emitError(const Twine &Message) {
434 DiagnosticHandler(LinkDiagnosticInfo(DS_Error, Message));
438 void emitWarning(const Twine &Message) {
439 DiagnosticHandler(LinkDiagnosticInfo(DS_Warning, Message));
442 bool getComdatLeader(Module *M, StringRef ComdatName,
443 const GlobalVariable *&GVar);
444 bool computeResultingSelectionKind(StringRef ComdatName,
445 Comdat::SelectionKind Src,
446 Comdat::SelectionKind Dst,
447 Comdat::SelectionKind &Result,
449 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
451 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
454 /// Given a global in the source module, return the global in the
455 /// destination module that is being linked to, if any.
456 GlobalValue *getLinkedToGlobal(const GlobalValue *SrcGV) {
457 // If the source has no name it can't link. If it has local linkage,
458 // there is no name match-up going on.
459 if (!SrcGV->hasName() || SrcGV->hasLocalLinkage())
462 // Otherwise see if we have a match in the destination module's symtab.
463 GlobalValue *DGV = DstM->getNamedValue(SrcGV->getName());
467 // If we found a global with the same name in the dest module, but it has
468 // internal linkage, we are really not doing any linkage here.
469 if (DGV->hasLocalLinkage())
472 // Otherwise, we do in fact link to the destination global.
476 void computeTypeMapping();
478 void upgradeMismatchedGlobalArray(StringRef Name);
479 void upgradeMismatchedGlobals();
481 bool linkAppendingVarProto(GlobalVariable *DstGV,
482 const GlobalVariable *SrcGV);
484 bool linkGlobalValueProto(GlobalValue *GV);
485 GlobalValue *linkGlobalVariableProto(const GlobalVariable *SGVar,
486 GlobalValue *DGV, bool LinkFromSrc);
487 GlobalValue *linkFunctionProto(const Function *SF, GlobalValue *DGV,
489 GlobalValue *linkGlobalAliasProto(const GlobalAlias *SGA, GlobalValue *DGV,
492 bool linkModuleFlagsMetadata();
494 void linkAppendingVarInit(const AppendingVarInfo &AVI);
495 void linkGlobalInits();
496 void linkFunctionBody(Function *Dst, Function *Src);
497 void linkAliasBodies();
498 void linkNamedMDNodes();
502 /// The LLVM SymbolTable class autorenames globals that conflict in the symbol
503 /// table. This is good for all clients except for us. Go through the trouble
504 /// to force this back.
505 static void forceRenaming(GlobalValue *GV, StringRef Name) {
506 // If the global doesn't force its name or if it already has the right name,
507 // there is nothing for us to do.
508 if (GV->hasLocalLinkage() || GV->getName() == Name)
511 Module *M = GV->getParent();
513 // If there is a conflict, rename the conflict.
514 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
515 GV->takeName(ConflictGV);
516 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
517 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
519 GV->setName(Name); // Force the name back
523 /// copy additional attributes (those not needed to construct a GlobalValue)
524 /// from the SrcGV to the DestGV.
525 static void copyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) {
526 // Use the maximum alignment, rather than just copying the alignment of SrcGV.
527 auto *DestGO = dyn_cast<GlobalObject>(DestGV);
530 Alignment = std::max(DestGO->getAlignment(), SrcGV->getAlignment());
532 DestGV->copyAttributesFrom(SrcGV);
535 DestGO->setAlignment(Alignment);
537 forceRenaming(DestGV, SrcGV->getName());
540 static bool isLessConstraining(GlobalValue::VisibilityTypes a,
541 GlobalValue::VisibilityTypes b) {
542 if (a == GlobalValue::HiddenVisibility)
544 if (b == GlobalValue::HiddenVisibility)
546 if (a == GlobalValue::ProtectedVisibility)
548 if (b == GlobalValue::ProtectedVisibility)
553 Value *ValueMaterializerTy::materializeValueFor(Value *V) {
554 Function *SF = dyn_cast<Function>(V);
558 Function *DF = Function::Create(TypeMap.get(SF->getFunctionType()),
559 SF->getLinkage(), SF->getName(), DstM);
560 copyGVAttributes(DF, SF);
562 if (Comdat *SC = SF->getComdat()) {
563 Comdat *DC = DstM->getOrInsertComdat(SC->getName());
567 LazilyLinkFunctions.push_back(SF);
571 bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName,
572 const GlobalVariable *&GVar) {
573 const GlobalValue *GVal = M->getNamedValue(ComdatName);
574 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
575 GVal = GA->getBaseObject();
577 // We cannot resolve the size of the aliasee yet.
578 return emitError("Linking COMDATs named '" + ComdatName +
579 "': COMDAT key involves incomputable alias size.");
582 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
585 "Linking COMDATs named '" + ComdatName +
586 "': GlobalVariable required for data dependent selection!");
591 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
592 Comdat::SelectionKind Src,
593 Comdat::SelectionKind Dst,
594 Comdat::SelectionKind &Result,
596 // The ability to mix Comdat::SelectionKind::Any with
597 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
598 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
599 Dst == Comdat::SelectionKind::Largest;
600 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
601 Src == Comdat::SelectionKind::Largest;
602 if (DstAnyOrLargest && SrcAnyOrLargest) {
603 if (Dst == Comdat::SelectionKind::Largest ||
604 Src == Comdat::SelectionKind::Largest)
605 Result = Comdat::SelectionKind::Largest;
607 Result = Comdat::SelectionKind::Any;
608 } else if (Src == Dst) {
611 return emitError("Linking COMDATs named '" + ComdatName +
612 "': invalid selection kinds!");
616 case Comdat::SelectionKind::Any:
620 case Comdat::SelectionKind::NoDuplicates:
621 return emitError("Linking COMDATs named '" + ComdatName +
622 "': noduplicates has been violated!");
623 case Comdat::SelectionKind::ExactMatch:
624 case Comdat::SelectionKind::Largest:
625 case Comdat::SelectionKind::SameSize: {
626 const GlobalVariable *DstGV;
627 const GlobalVariable *SrcGV;
628 if (getComdatLeader(DstM, ComdatName, DstGV) ||
629 getComdatLeader(SrcM, ComdatName, SrcGV))
632 const DataLayout *DstDL = DstM->getDataLayout();
633 const DataLayout *SrcDL = SrcM->getDataLayout();
634 if (!DstDL || !SrcDL) {
636 "Linking COMDATs named '" + ComdatName +
637 "': can't do size dependent selection without DataLayout!");
640 DstDL->getTypeAllocSize(DstGV->getType()->getPointerElementType());
642 SrcDL->getTypeAllocSize(SrcGV->getType()->getPointerElementType());
643 if (Result == Comdat::SelectionKind::ExactMatch) {
644 if (SrcGV->getInitializer() != DstGV->getInitializer())
645 return emitError("Linking COMDATs named '" + ComdatName +
646 "': ExactMatch violated!");
648 } else if (Result == Comdat::SelectionKind::Largest) {
649 LinkFromSrc = SrcSize > DstSize;
650 } else if (Result == Comdat::SelectionKind::SameSize) {
651 if (SrcSize != DstSize)
652 return emitError("Linking COMDATs named '" + ComdatName +
653 "': SameSize violated!");
656 llvm_unreachable("unknown selection kind");
665 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
666 Comdat::SelectionKind &Result,
668 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
669 StringRef ComdatName = SrcC->getName();
670 Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable();
671 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
673 if (DstCI == ComdatSymTab.end()) {
674 // Use the comdat if it is only available in one of the modules.
680 const Comdat *DstC = &DstCI->second;
681 Comdat::SelectionKind DSK = DstC->getSelectionKind();
682 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
686 bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
687 const GlobalValue &Dest,
688 const GlobalValue &Src) {
689 // We always have to add Src if it has appending linkage.
690 if (Src.hasAppendingLinkage()) {
695 bool SrcIsDeclaration = Src.isDeclarationForLinker();
696 bool DestIsDeclaration = Dest.isDeclarationForLinker();
698 if (SrcIsDeclaration) {
699 // If Src is external or if both Src & Dest are external.. Just link the
700 // external globals, we aren't adding anything.
701 if (Src.hasDLLImportStorageClass()) {
702 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
703 LinkFromSrc = DestIsDeclaration;
706 // If the Dest is weak, use the source linkage.
707 LinkFromSrc = Dest.hasExternalWeakLinkage();
711 if (DestIsDeclaration) {
712 // If Dest is external but Src is not:
717 if (Src.hasCommonLinkage()) {
718 if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
723 if (!Dest.hasCommonLinkage()) {
728 // FIXME: Make datalayout mandatory and just use getDataLayout().
729 DataLayout DL(Dest.getParent());
731 uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
732 uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
733 LinkFromSrc = SrcSize > DestSize;
737 if (Src.isWeakForLinker()) {
738 assert(!Dest.hasExternalWeakLinkage());
739 assert(!Dest.hasAvailableExternallyLinkage());
741 if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
750 if (Dest.isWeakForLinker()) {
751 assert(Src.hasExternalLinkage());
756 assert(!Src.hasExternalWeakLinkage());
757 assert(!Dest.hasExternalWeakLinkage());
758 assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
759 "Unexpected linkage type!");
760 return emitError("Linking globals named '" + Src.getName() +
761 "': symbol multiply defined!");
764 /// Loop over all of the linked values to compute type mappings. For example,
765 /// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct
766 /// types 'Foo' but one got renamed when the module was loaded into the same
768 void ModuleLinker::computeTypeMapping() {
769 for (GlobalValue &SGV : SrcM->globals()) {
770 GlobalValue *DGV = getLinkedToGlobal(&SGV);
774 if (!DGV->hasAppendingLinkage() || !SGV.hasAppendingLinkage()) {
775 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
779 // Unify the element type of appending arrays.
780 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
781 ArrayType *SAT = cast<ArrayType>(SGV.getType()->getElementType());
782 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
785 for (GlobalValue &SGV : *SrcM) {
786 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
787 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
790 for (GlobalValue &SGV : SrcM->aliases()) {
791 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
792 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
795 // Incorporate types by name, scanning all the types in the source module.
796 // At this point, the destination module may have a type "%foo = { i32 }" for
797 // example. When the source module got loaded into the same LLVMContext, if
798 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
799 TypeFinder SrcStructTypes;
800 SrcStructTypes.run(*SrcM, true);
801 SmallPtrSet<StructType*, 32> SrcStructTypesSet(SrcStructTypes.begin(),
802 SrcStructTypes.end());
804 for (unsigned i = 0, e = SrcStructTypes.size(); i != e; ++i) {
805 StructType *ST = SrcStructTypes[i];
806 if (!ST->hasName()) continue;
808 // Check to see if there is a dot in the name followed by a digit.
809 size_t DotPos = ST->getName().rfind('.');
810 if (DotPos == 0 || DotPos == StringRef::npos ||
811 ST->getName().back() == '.' ||
812 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos+1])))
815 // Check to see if the destination module has a struct with the prefix name.
816 if (StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos)))
817 // Don't use it if this actually came from the source module. They're in
818 // the same LLVMContext after all. Also don't use it unless the type is
819 // actually used in the destination module. This can happen in situations
824 // %Z = type { %A } %B = type { %C.1 }
825 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
826 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
827 // %C = type { i8* } %B.3 = type { %C.1 }
829 // When we link Module B with Module A, the '%B' in Module B is
830 // used. However, that would then use '%C.1'. But when we process '%C.1',
831 // we prefer to take the '%C' version. So we are then left with both
832 // '%C.1' and '%C' being used for the same types. This leads to some
833 // variables using one type and some using the other.
834 if (!SrcStructTypesSet.count(DST) && TypeMap.DstStructTypesSet.count(DST))
835 TypeMap.addTypeMapping(DST, ST);
838 // Now that we have discovered all of the type equivalences, get a body for
839 // any 'opaque' types in the dest module that are now resolved.
840 TypeMap.linkDefinedTypeBodies();
843 static void upgradeGlobalArray(GlobalVariable *GV) {
844 ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
845 StructType *OldTy = cast<StructType>(ATy->getElementType());
846 assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
848 // Get the upgraded 3 element type.
849 PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
850 Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
852 StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
854 // Build new constants with a null third field filled in.
855 Constant *OldInitC = GV->getInitializer();
856 ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
857 if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
858 // Invalid initializer; give up.
860 std::vector<Constant *> Initializers;
861 if (OldInit && OldInit->getNumOperands()) {
862 Value *Null = Constant::getNullValue(VoidPtrTy);
863 for (Use &U : OldInit->operands()) {
864 ConstantStruct *Init = cast<ConstantStruct>(U.get());
865 Initializers.push_back(ConstantStruct::get(
866 NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
869 assert(Initializers.size() == ATy->getNumElements() &&
870 "Failed to copy all array elements");
872 // Replace the old GV with a new one.
873 ATy = ArrayType::get(NewTy, Initializers.size());
874 Constant *NewInit = ConstantArray::get(ATy, Initializers);
875 GlobalVariable *NewGV = new GlobalVariable(
876 *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
877 GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
878 GV->isExternallyInitialized());
879 NewGV->copyAttributesFrom(GV);
881 assert(GV->use_empty() && "program cannot use initializer list");
882 GV->eraseFromParent();
885 void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
886 // Look for the global arrays.
887 auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM->getNamedValue(Name));
890 auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM->getNamedValue(Name));
894 // Check if the types already match.
895 auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
897 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
901 // Grab the element types. We can only upgrade an array of a two-field
902 // struct. Only bother if the other one has three-fields.
903 auto *DstEltTy = cast<StructType>(DstTy->getElementType());
904 auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
905 if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
906 upgradeGlobalArray(DstGV);
909 if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
910 upgradeGlobalArray(SrcGV);
912 // We can't upgrade any other differences.
915 void ModuleLinker::upgradeMismatchedGlobals() {
916 upgradeMismatchedGlobalArray("llvm.global_ctors");
917 upgradeMismatchedGlobalArray("llvm.global_dtors");
920 /// If there were any appending global variables, link them together now.
921 /// Return true on error.
922 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
923 const GlobalVariable *SrcGV) {
925 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
926 return emitError("Linking globals named '" + SrcGV->getName() +
927 "': can only link appending global with another appending global!");
929 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
931 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
932 Type *EltTy = DstTy->getElementType();
934 // Check to see that they two arrays agree on type.
935 if (EltTy != SrcTy->getElementType())
936 return emitError("Appending variables with different element types!");
937 if (DstGV->isConstant() != SrcGV->isConstant())
938 return emitError("Appending variables linked with different const'ness!");
940 if (DstGV->getAlignment() != SrcGV->getAlignment())
942 "Appending variables with different alignment need to be linked!");
944 if (DstGV->getVisibility() != SrcGV->getVisibility())
946 "Appending variables with different visibility need to be linked!");
948 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
950 "Appending variables with different unnamed_addr need to be linked!");
952 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
954 "Appending variables with different section name need to be linked!");
956 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements();
957 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
959 // Create the new global variable.
961 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(),
962 DstGV->getLinkage(), /*init*/nullptr, /*name*/"", DstGV,
963 DstGV->getThreadLocalMode(),
964 DstGV->getType()->getAddressSpace());
966 // Propagate alignment, visibility and section info.
967 copyGVAttributes(NG, DstGV);
969 AppendingVarInfo AVI;
971 AVI.DstInit = DstGV->getInitializer();
972 AVI.SrcInit = SrcGV->getInitializer();
973 AppendingVars.push_back(AVI);
975 // Replace any uses of the two global variables with uses of the new
977 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
979 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
980 DstGV->eraseFromParent();
982 // Track the source variable so we don't try to link it.
983 DoNotLinkFromSource.insert(SrcGV);
988 bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) {
989 GlobalValue *DGV = getLinkedToGlobal(SGV);
991 // Handle the ultra special appending linkage case first.
992 if (DGV && DGV->hasAppendingLinkage())
993 return linkAppendingVarProto(cast<GlobalVariable>(DGV),
994 cast<GlobalVariable>(SGV));
996 bool LinkFromSrc = true;
998 GlobalValue::VisibilityTypes Visibility = SGV->getVisibility();
999 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
1001 if (const Comdat *SC = SGV->getComdat()) {
1002 Comdat::SelectionKind SK;
1003 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1004 C = DstM->getOrInsertComdat(SC->getName());
1005 C->setSelectionKind(SK);
1007 if (shouldLinkFromSource(LinkFromSrc, *DGV, *SGV))
1012 // Track the source global so that we don't attempt to copy it over when
1013 // processing global initializers.
1014 DoNotLinkFromSource.insert(SGV);
1017 // Make sure to remember this mapping.
1019 ConstantExpr::getBitCast(DGV, TypeMap.get(SGV->getType()));
1023 Visibility = isLessConstraining(Visibility, DGV->getVisibility())
1024 ? DGV->getVisibility()
1026 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1029 if (!LinkFromSrc && !DGV)
1033 if (auto *SGVar = dyn_cast<GlobalVariable>(SGV)) {
1034 NewGV = linkGlobalVariableProto(SGVar, DGV, LinkFromSrc);
1037 } else if (auto *SF = dyn_cast<Function>(SGV)) {
1038 NewGV = linkFunctionProto(SF, DGV, LinkFromSrc);
1040 NewGV = linkGlobalAliasProto(cast<GlobalAlias>(SGV), DGV, LinkFromSrc);
1045 copyGVAttributes(NewGV, SGV);
1047 NewGV->setUnnamedAddr(HasUnnamedAddr);
1048 NewGV->setVisibility(Visibility);
1050 if (auto *NewGO = dyn_cast<GlobalObject>(NewGV)) {
1052 NewGO->setComdat(C);
1055 // Make sure to remember this mapping.
1058 DGV->replaceAllUsesWith(
1059 ConstantExpr::getBitCast(NewGV, DGV->getType()));
1060 DGV->eraseFromParent();
1062 ValueMap[SGV] = NewGV;
1069 /// Loop through the global variables in the src module and merge them into the
1071 GlobalValue *ModuleLinker::linkGlobalVariableProto(const GlobalVariable *SGVar,
1074 unsigned Alignment = 0;
1075 bool ClearConstant = false;
1078 if (DGV->hasCommonLinkage() && SGVar->hasCommonLinkage())
1079 Alignment = std::max(SGVar->getAlignment(), DGV->getAlignment());
1081 auto *DGVar = dyn_cast<GlobalVariable>(DGV);
1082 if (!SGVar->isConstant() || (DGVar && !DGVar->isConstant()))
1083 ClearConstant = true;
1087 if (auto *NewGVar = dyn_cast<GlobalVariable>(DGV)) {
1089 NewGVar->setAlignment(Alignment);
1090 if (NewGVar->isDeclaration() && ClearConstant)
1091 NewGVar->setConstant(false);
1096 // No linking to be performed or linking from the source: simply create an
1097 // identical version of the symbol over in the dest module... the
1098 // initializer will be filled in later by LinkGlobalInits.
1099 GlobalVariable *NewDGV = new GlobalVariable(
1100 *DstM, TypeMap.get(SGVar->getType()->getElementType()),
1101 SGVar->isConstant(), SGVar->getLinkage(), /*init*/ nullptr,
1102 SGVar->getName(), /*insertbefore*/ nullptr, SGVar->getThreadLocalMode(),
1103 SGVar->getType()->getAddressSpace());
1106 NewDGV->setAlignment(Alignment);
1111 /// Link the function in the source module into the destination module if
1112 /// needed, setting up mapping information.
1113 GlobalValue *ModuleLinker::linkFunctionProto(const Function *SF,
1119 // If the function is to be lazily linked, don't create it just yet.
1120 // The ValueMaterializerTy will deal with creating it if it's used.
1121 if (!DGV && (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() ||
1122 SF->hasAvailableExternallyLinkage())) {
1123 DoNotLinkFromSource.insert(SF);
1127 // If there is no linkage to be performed or we are linking from the source,
1129 return Function::Create(TypeMap.get(SF->getFunctionType()), SF->getLinkage(),
1130 SF->getName(), DstM);
1133 /// Set up prototypes for any aliases that come over from the source module.
1134 GlobalValue *ModuleLinker::linkGlobalAliasProto(const GlobalAlias *SGA,
1140 // If there is no linkage to be performed or we're linking from the source,
1142 auto *PTy = cast<PointerType>(TypeMap.get(SGA->getType()));
1143 return GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(),
1144 SGA->getLinkage(), SGA->getName(), DstM);
1147 static void getArrayElements(const Constant *C,
1148 SmallVectorImpl<Constant *> &Dest) {
1149 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1151 for (unsigned i = 0; i != NumElements; ++i)
1152 Dest.push_back(C->getAggregateElement(i));
1155 void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) {
1156 // Merge the initializer.
1157 SmallVector<Constant *, 16> DstElements;
1158 getArrayElements(AVI.DstInit, DstElements);
1160 SmallVector<Constant *, 16> SrcElements;
1161 getArrayElements(AVI.SrcInit, SrcElements);
1163 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
1165 StringRef Name = AVI.NewGV->getName();
1166 bool IsNewStructor =
1167 (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
1168 cast<StructType>(NewType->getElementType())->getNumElements() == 3;
1170 for (auto *V : SrcElements) {
1171 if (IsNewStructor) {
1172 Constant *Key = V->getAggregateElement(2);
1173 if (DoNotLinkFromSource.count(Key))
1176 DstElements.push_back(
1177 MapValue(V, ValueMap, RF_None, &TypeMap, &ValMaterializer));
1179 if (IsNewStructor) {
1180 NewType = ArrayType::get(NewType->getElementType(), DstElements.size());
1181 AVI.NewGV->mutateType(PointerType::get(NewType, 0));
1184 AVI.NewGV->setInitializer(ConstantArray::get(NewType, DstElements));
1187 /// Update the initializers in the Dest module now that all globals that may be
1188 /// referenced are in Dest.
1189 void ModuleLinker::linkGlobalInits() {
1190 // Loop over all of the globals in the src module, mapping them over as we go
1191 for (Module::const_global_iterator I = SrcM->global_begin(),
1192 E = SrcM->global_end(); I != E; ++I) {
1194 // Only process initialized GV's or ones not already in dest.
1195 if (!I->hasInitializer() || DoNotLinkFromSource.count(I)) continue;
1197 // Grab destination global variable.
1198 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[I]);
1199 // Figure out what the initializer looks like in the dest module.
1200 DGV->setInitializer(MapValue(I->getInitializer(), ValueMap,
1201 RF_None, &TypeMap, &ValMaterializer));
1205 /// Copy the source function over into the dest function and fix up references
1206 /// to values. At this point we know that Dest is an external function, and
1207 /// that Src is not.
1208 void ModuleLinker::linkFunctionBody(Function *Dst, Function *Src) {
1209 assert(Src && Dst && Dst->isDeclaration() && !Src->isDeclaration());
1211 // Go through and convert function arguments over, remembering the mapping.
1212 Function::arg_iterator DI = Dst->arg_begin();
1213 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1214 I != E; ++I, ++DI) {
1215 DI->setName(I->getName()); // Copy the name over.
1217 // Add a mapping to our mapping.
1221 // Splice the body of the source function into the dest function.
1222 Dst->getBasicBlockList().splice(Dst->end(), Src->getBasicBlockList());
1224 // At this point, all of the instructions and values of the function are now
1225 // copied over. The only problem is that they are still referencing values in
1226 // the Source function as operands. Loop through all of the operands of the
1227 // functions and patch them up to point to the local versions.
1228 for (Function::iterator BB = Dst->begin(), BE = Dst->end(); BB != BE; ++BB)
1229 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
1230 RemapInstruction(I, ValueMap, RF_IgnoreMissingEntries, &TypeMap,
1233 // There is no need to map the arguments anymore.
1234 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1240 /// Insert all of the aliases in Src into the Dest module.
1241 void ModuleLinker::linkAliasBodies() {
1242 for (Module::alias_iterator I = SrcM->alias_begin(), E = SrcM->alias_end();
1244 if (DoNotLinkFromSource.count(I))
1246 if (Constant *Aliasee = I->getAliasee()) {
1247 GlobalAlias *DA = cast<GlobalAlias>(ValueMap[I]);
1249 MapValue(Aliasee, ValueMap, RF_None, &TypeMap, &ValMaterializer);
1250 DA->setAliasee(Val);
1255 /// Insert all of the named MDNodes in Src into the Dest module.
1256 void ModuleLinker::linkNamedMDNodes() {
1257 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1258 for (Module::const_named_metadata_iterator I = SrcM->named_metadata_begin(),
1259 E = SrcM->named_metadata_end(); I != E; ++I) {
1260 // Don't link module flags here. Do them separately.
1261 if (&*I == SrcModFlags) continue;
1262 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(I->getName());
1263 // Add Src elements into Dest node.
1264 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
1265 DestNMD->addOperand(MapValue(I->getOperand(i), ValueMap,
1266 RF_None, &TypeMap, &ValMaterializer));
1270 /// Merge the linker flags in Src into the Dest module.
1271 bool ModuleLinker::linkModuleFlagsMetadata() {
1272 // If the source module has no module flags, we are done.
1273 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1274 if (!SrcModFlags) return false;
1276 // If the destination module doesn't have module flags yet, then just copy
1277 // over the source module's flags.
1278 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
1279 if (DstModFlags->getNumOperands() == 0) {
1280 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1281 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1286 // First build a map of the existing module flags and requirements.
1287 DenseMap<MDString*, MDNode*> Flags;
1288 SmallSetVector<MDNode*, 16> Requirements;
1289 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1290 MDNode *Op = DstModFlags->getOperand(I);
1291 ConstantInt *Behavior = cast<ConstantInt>(Op->getOperand(0));
1292 MDString *ID = cast<MDString>(Op->getOperand(1));
1294 if (Behavior->getZExtValue() == Module::Require) {
1295 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1301 // Merge in the flags from the source module, and also collect its set of
1303 bool HasErr = false;
1304 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1305 MDNode *SrcOp = SrcModFlags->getOperand(I);
1306 ConstantInt *SrcBehavior = cast<ConstantInt>(SrcOp->getOperand(0));
1307 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1308 MDNode *DstOp = Flags.lookup(ID);
1309 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1311 // If this is a requirement, add it and continue.
1312 if (SrcBehaviorValue == Module::Require) {
1313 // If the destination module does not already have this requirement, add
1315 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1316 DstModFlags->addOperand(SrcOp);
1321 // If there is no existing flag with this ID, just add it.
1324 DstModFlags->addOperand(SrcOp);
1328 // Otherwise, perform a merge.
1329 ConstantInt *DstBehavior = cast<ConstantInt>(DstOp->getOperand(0));
1330 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1332 // If either flag has override behavior, handle it first.
1333 if (DstBehaviorValue == Module::Override) {
1334 // Diagnose inconsistent flags which both have override behavior.
1335 if (SrcBehaviorValue == Module::Override &&
1336 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1337 HasErr |= emitError("linking module flags '" + ID->getString() +
1338 "': IDs have conflicting override values");
1341 } else if (SrcBehaviorValue == Module::Override) {
1342 // Update the destination flag to that of the source.
1343 DstOp->replaceOperandWith(0, SrcBehavior);
1344 DstOp->replaceOperandWith(2, SrcOp->getOperand(2));
1348 // Diagnose inconsistent merge behavior types.
1349 if (SrcBehaviorValue != DstBehaviorValue) {
1350 HasErr |= emitError("linking module flags '" + ID->getString() +
1351 "': IDs have conflicting behaviors");
1355 // Perform the merge for standard behavior types.
1356 switch (SrcBehaviorValue) {
1357 case Module::Require:
1358 case Module::Override: llvm_unreachable("not possible");
1359 case Module::Error: {
1360 // Emit an error if the values differ.
1361 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1362 HasErr |= emitError("linking module flags '" + ID->getString() +
1363 "': IDs have conflicting values");
1367 case Module::Warning: {
1368 // Emit a warning if the values differ.
1369 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1370 emitWarning("linking module flags '" + ID->getString() +
1371 "': IDs have conflicting values");
1375 case Module::Append: {
1376 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1377 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1378 unsigned NumOps = DstValue->getNumOperands() + SrcValue->getNumOperands();
1379 Value **VP, **Values = VP = new Value*[NumOps];
1380 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i, ++VP)
1381 *VP = DstValue->getOperand(i);
1382 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i, ++VP)
1383 *VP = SrcValue->getOperand(i);
1384 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1385 ArrayRef<Value*>(Values,
1390 case Module::AppendUnique: {
1391 SmallSetVector<Value*, 16> Elts;
1392 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1393 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1394 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i)
1395 Elts.insert(DstValue->getOperand(i));
1396 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i)
1397 Elts.insert(SrcValue->getOperand(i));
1398 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1399 ArrayRef<Value*>(Elts.begin(),
1406 // Check all of the requirements.
1407 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1408 MDNode *Requirement = Requirements[I];
1409 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1410 Value *ReqValue = Requirement->getOperand(1);
1412 MDNode *Op = Flags[Flag];
1413 if (!Op || Op->getOperand(2) != ReqValue) {
1414 HasErr |= emitError("linking module flags '" + Flag->getString() +
1415 "': does not have the required value");
1423 bool ModuleLinker::run() {
1424 assert(DstM && "Null destination module");
1425 assert(SrcM && "Null source module");
1427 // Inherit the target data from the source module if the destination module
1428 // doesn't have one already.
1429 if (!DstM->getDataLayout() && SrcM->getDataLayout())
1430 DstM->setDataLayout(SrcM->getDataLayout());
1432 // Copy the target triple from the source to dest if the dest's is empty.
1433 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
1434 DstM->setTargetTriple(SrcM->getTargetTriple());
1436 if (SrcM->getDataLayout() && DstM->getDataLayout() &&
1437 *SrcM->getDataLayout() != *DstM->getDataLayout()) {
1438 emitWarning("Linking two modules of different data layouts: '" +
1439 SrcM->getModuleIdentifier() + "' is '" +
1440 SrcM->getDataLayoutStr() + "' whereas '" +
1441 DstM->getModuleIdentifier() + "' is '" +
1442 DstM->getDataLayoutStr() + "'\n");
1444 if (!SrcM->getTargetTriple().empty() &&
1445 DstM->getTargetTriple() != SrcM->getTargetTriple()) {
1446 emitWarning("Linking two modules of different target triples: " +
1447 SrcM->getModuleIdentifier() + "' is '" +
1448 SrcM->getTargetTriple() + "' whereas '" +
1449 DstM->getModuleIdentifier() + "' is '" +
1450 DstM->getTargetTriple() + "'\n");
1453 // Append the module inline asm string.
1454 if (!SrcM->getModuleInlineAsm().empty()) {
1455 if (DstM->getModuleInlineAsm().empty())
1456 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
1458 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
1459 SrcM->getModuleInlineAsm());
1462 // Loop over all of the linked values to compute type mappings.
1463 computeTypeMapping();
1465 ComdatsChosen.clear();
1466 for (const auto &SMEC : SrcM->getComdatSymbolTable()) {
1467 const Comdat &C = SMEC.getValue();
1468 if (ComdatsChosen.count(&C))
1470 Comdat::SelectionKind SK;
1472 if (getComdatResult(&C, SK, LinkFromSrc))
1474 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1477 // Upgrade mismatched global arrays.
1478 upgradeMismatchedGlobals();
1480 // Insert all of the globals in src into the DstM module... without linking
1481 // initializers (which could refer to functions not yet mapped over).
1482 for (Module::global_iterator I = SrcM->global_begin(),
1483 E = SrcM->global_end(); I != E; ++I)
1484 if (linkGlobalValueProto(I))
1487 // Link the functions together between the two modules, without doing function
1488 // bodies... this just adds external function prototypes to the DstM
1489 // function... We do this so that when we begin processing function bodies,
1490 // all of the global values that may be referenced are available in our
1492 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I)
1493 if (linkGlobalValueProto(I))
1496 // If there were any aliases, link them now.
1497 for (Module::alias_iterator I = SrcM->alias_begin(),
1498 E = SrcM->alias_end(); I != E; ++I)
1499 if (linkGlobalValueProto(I))
1502 for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i)
1503 linkAppendingVarInit(AppendingVars[i]);
1505 // Link in the function bodies that are defined in the source module into
1507 for (Module::iterator SF = SrcM->begin(), E = SrcM->end(); SF != E; ++SF) {
1508 // Skip if not linking from source.
1509 if (DoNotLinkFromSource.count(SF)) continue;
1511 Function *DF = cast<Function>(ValueMap[SF]);
1512 if (SF->hasPrefixData()) {
1513 // Link in the prefix data.
1514 DF->setPrefixData(MapValue(
1515 SF->getPrefixData(), ValueMap, RF_None, &TypeMap, &ValMaterializer));
1518 // Materialize if needed.
1519 if (std::error_code EC = SF->materialize())
1520 return emitError(EC.message());
1522 // Skip if no body (function is external).
1523 if (SF->isDeclaration())
1526 linkFunctionBody(DF, SF);
1527 SF->Dematerialize();
1530 // Resolve all uses of aliases with aliasees.
1533 // Remap all of the named MDNodes in Src into the DstM module. We do this
1534 // after linking GlobalValues so that MDNodes that reference GlobalValues
1535 // are properly remapped.
1538 // Merge the module flags into the DstM module.
1539 if (linkModuleFlagsMetadata())
1542 // Update the initializers in the DstM module now that all globals that may
1543 // be referenced are in DstM.
1546 // Process vector of lazily linked in functions.
1547 bool LinkedInAnyFunctions;
1549 LinkedInAnyFunctions = false;
1551 for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(),
1552 E = LazilyLinkFunctions.end(); I != E; ++I) {
1557 Function *DF = cast<Function>(ValueMap[SF]);
1558 if (SF->hasPrefixData()) {
1559 // Link in the prefix data.
1560 DF->setPrefixData(MapValue(SF->getPrefixData(),
1567 // Materialize if needed.
1568 if (std::error_code EC = SF->materialize())
1569 return emitError(EC.message());
1571 // Skip if no body (function is external).
1572 if (SF->isDeclaration())
1575 // Erase from vector *before* the function body is linked - linkFunctionBody could
1577 LazilyLinkFunctions.erase(I);
1579 // Link in function body.
1580 linkFunctionBody(DF, SF);
1581 SF->Dematerialize();
1583 // Set flag to indicate we may have more functions to lazily link in
1584 // since we linked in a function.
1585 LinkedInAnyFunctions = true;
1588 } while (LinkedInAnyFunctions);
1590 // Now that all of the types from the source are used, resolve any structs
1591 // copied over to the dest that didn't exist there.
1592 TypeMap.linkDefinedTypeBodies();
1597 void Linker::init(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
1598 this->Composite = M;
1599 this->DiagnosticHandler = DiagnosticHandler;
1601 TypeFinder StructTypes;
1602 StructTypes.run(*M, true);
1603 IdentifiedStructTypes.insert(StructTypes.begin(), StructTypes.end());
1606 Linker::Linker(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
1607 init(M, DiagnosticHandler);
1610 Linker::Linker(Module *M) {
1611 init(M, [this](const DiagnosticInfo &DI) {
1612 Composite->getContext().diagnose(DI);
1619 void Linker::deleteModule() {
1621 Composite = nullptr;
1624 bool Linker::linkInModule(Module *Src) {
1625 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,
1627 return TheLinker.run();
1630 //===----------------------------------------------------------------------===//
1631 // LinkModules entrypoint.
1632 //===----------------------------------------------------------------------===//
1634 /// This function links two modules together, with the resulting Dest module
1635 /// modified to be the composite of the two input modules. If an error occurs,
1636 /// true is returned and ErrorMsg (if not null) is set to indicate the problem.
1637 /// Upon failure, the Dest module could be in a modified state, and shouldn't be
1638 /// relied on to be consistent.
1639 bool Linker::LinkModules(Module *Dest, Module *Src,
1640 DiagnosticHandlerFunction DiagnosticHandler) {
1641 Linker L(Dest, DiagnosticHandler);
1642 return L.linkInModule(Src);
1645 bool Linker::LinkModules(Module *Dest, Module *Src) {
1647 return L.linkInModule(Src);
1650 //===----------------------------------------------------------------------===//
1652 //===----------------------------------------------------------------------===//
1654 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
1655 LLVMLinkerMode Mode, char **OutMessages) {
1656 Module *D = unwrap(Dest);
1657 std::string Message;
1658 raw_string_ostream Stream(Message);
1659 DiagnosticPrinterRawOStream DP(Stream);
1661 LLVMBool Result = Linker::LinkModules(
1662 D, unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); });
1664 if (OutMessages && Result)
1665 *OutMessages = strdup(Message.c_str());