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 (DenseMap<Type*, Type*>::const_iterator
79 I = MappedTypes.begin(), E = MappedTypes.end(); I != E; ++I) {
80 dbgs() << "TypeMap: ";
81 I->first->print(dbgs());
83 I->second->print(dbgs());
89 Type *getImpl(Type *T);
90 /// Implement the ValueMapTypeRemapper interface.
91 Type *remapType(Type *SrcTy) override {
95 bool areTypesIsomorphic(Type *DstTy, Type *SrcTy);
99 void TypeMapTy::addTypeMapping(Type *DstTy, Type *SrcTy) {
100 Type *&Entry = MappedTypes[SrcTy];
103 if (DstTy == SrcTy) {
108 // Check to see if these types are recursively isomorphic and establish a
109 // mapping between them if so.
110 if (areTypesIsomorphic(DstTy, SrcTy)) {
111 SpeculativeTypes.clear();
115 // Oops, they aren't isomorphic. Just discard this request by rolling out
116 // any speculative mappings we've established.
117 unsigned Removed = 0;
118 for (unsigned I = 0, E = SpeculativeTypes.size(); I != E; ++I) {
119 Type *SrcTy = SpeculativeTypes[I];
120 auto Iter = MappedTypes.find(SrcTy);
121 auto *DstTy = dyn_cast<StructType>(Iter->second);
122 if (DstTy && DstResolvedOpaqueTypes.erase(DstTy))
124 MappedTypes.erase(Iter);
126 SrcDefinitionsToResolve.resize(SrcDefinitionsToResolve.size() - Removed);
127 SpeculativeTypes.clear();
130 /// Recursively walk this pair of types, returning true if they are isomorphic,
131 /// false if they are not.
132 bool TypeMapTy::areTypesIsomorphic(Type *DstTy, Type *SrcTy) {
133 // Two types with differing kinds are clearly not isomorphic.
134 if (DstTy->getTypeID() != SrcTy->getTypeID()) return false;
136 // If we have an entry in the MappedTypes table, then we have our answer.
137 Type *&Entry = MappedTypes[SrcTy];
139 return Entry == DstTy;
141 // Two identical types are clearly isomorphic. Remember this
142 // non-speculatively.
143 if (DstTy == SrcTy) {
148 // Okay, we have two types with identical kinds that we haven't seen before.
150 // If this is an opaque struct type, special case it.
151 if (StructType *SSTy = dyn_cast<StructType>(SrcTy)) {
152 // Mapping an opaque type to any struct, just keep the dest struct.
153 if (SSTy->isOpaque()) {
155 SpeculativeTypes.push_back(SrcTy);
159 // Mapping a non-opaque source type to an opaque dest. If this is the first
160 // type that we're mapping onto this destination type then we succeed. Keep
161 // the dest, but fill it in later. If this is the second (different) type
162 // that we're trying to map onto the same opaque type then we fail.
163 if (cast<StructType>(DstTy)->isOpaque()) {
164 // We can only map one source type onto the opaque destination type.
165 if (!DstResolvedOpaqueTypes.insert(cast<StructType>(DstTy)).second)
167 SrcDefinitionsToResolve.push_back(SSTy);
168 SpeculativeTypes.push_back(SrcTy);
174 // If the number of subtypes disagree between the two types, then we fail.
175 if (SrcTy->getNumContainedTypes() != DstTy->getNumContainedTypes())
178 // Fail if any of the extra properties (e.g. array size) of the type disagree.
179 if (isa<IntegerType>(DstTy))
180 return false; // bitwidth disagrees.
181 if (PointerType *PT = dyn_cast<PointerType>(DstTy)) {
182 if (PT->getAddressSpace() != cast<PointerType>(SrcTy)->getAddressSpace())
185 } else if (FunctionType *FT = dyn_cast<FunctionType>(DstTy)) {
186 if (FT->isVarArg() != cast<FunctionType>(SrcTy)->isVarArg())
188 } else if (StructType *DSTy = dyn_cast<StructType>(DstTy)) {
189 StructType *SSTy = cast<StructType>(SrcTy);
190 if (DSTy->isLiteral() != SSTy->isLiteral() ||
191 DSTy->isPacked() != SSTy->isPacked())
193 } else if (ArrayType *DATy = dyn_cast<ArrayType>(DstTy)) {
194 if (DATy->getNumElements() != cast<ArrayType>(SrcTy)->getNumElements())
196 } else if (VectorType *DVTy = dyn_cast<VectorType>(DstTy)) {
197 if (DVTy->getNumElements() != cast<VectorType>(SrcTy)->getNumElements())
201 // Otherwise, we speculate that these two types will line up and recursively
202 // check the subelements.
204 SpeculativeTypes.push_back(SrcTy);
206 for (unsigned i = 0, e = SrcTy->getNumContainedTypes(); i != e; ++i)
207 if (!areTypesIsomorphic(DstTy->getContainedType(i),
208 SrcTy->getContainedType(i)))
211 // If everything seems to have lined up, then everything is great.
215 void TypeMapTy::linkDefinedTypeBodies() {
216 SmallVector<Type*, 16> Elements;
217 SmallString<16> TmpName;
219 // Note that processing entries in this loop (calling 'get') can add new
220 // entries to the SrcDefinitionsToResolve vector.
221 while (!SrcDefinitionsToResolve.empty()) {
222 StructType *SrcSTy = SrcDefinitionsToResolve.pop_back_val();
223 StructType *DstSTy = cast<StructType>(MappedTypes[SrcSTy]);
225 // TypeMap is a many-to-one mapping, if there were multiple types that
226 // provide a body for DstSTy then previous iterations of this loop may have
227 // already handled it. Just ignore this case.
228 if (!DstSTy->isOpaque()) continue;
229 assert(!SrcSTy->isOpaque() && "Not resolving a definition?");
231 // Map the body of the source type over to a new body for the dest type.
232 Elements.resize(SrcSTy->getNumElements());
233 for (unsigned i = 0, e = Elements.size(); i != e; ++i)
234 Elements[i] = getImpl(SrcSTy->getElementType(i));
236 DstSTy->setBody(Elements, SrcSTy->isPacked());
238 // If DstSTy has no name or has a longer name than STy, then viciously steal
240 if (!SrcSTy->hasName()) continue;
241 StringRef SrcName = SrcSTy->getName();
243 if (!DstSTy->hasName() || DstSTy->getName().size() > SrcName.size()) {
244 TmpName.insert(TmpName.end(), SrcName.begin(), SrcName.end());
246 DstSTy->setName(TmpName.str());
251 DstResolvedOpaqueTypes.clear();
254 Type *TypeMapTy::get(Type *Ty) {
255 Type *Result = getImpl(Ty);
257 // If this caused a reference to any struct type, resolve it before returning.
258 if (!SrcDefinitionsToResolve.empty())
259 linkDefinedTypeBodies();
263 /// This is the recursive version of get().
264 Type *TypeMapTy::getImpl(Type *Ty) {
265 // If we already have an entry for this type, return it.
266 Type **Entry = &MappedTypes[Ty];
267 if (*Entry) return *Entry;
269 // If this is not a named struct type, then just map all of the elements and
270 // then rebuild the type from inside out.
271 if (!isa<StructType>(Ty) || cast<StructType>(Ty)->isLiteral()) {
272 // If there are no element types to map, then the type is itself. This is
273 // true for the anonymous {} struct, things like 'float', integers, etc.
274 if (Ty->getNumContainedTypes() == 0)
277 // Remap all of the elements, keeping track of whether any of them change.
278 bool AnyChange = false;
279 SmallVector<Type*, 4> ElementTypes;
280 ElementTypes.resize(Ty->getNumContainedTypes());
281 for (unsigned i = 0, e = Ty->getNumContainedTypes(); i != e; ++i) {
282 ElementTypes[i] = getImpl(Ty->getContainedType(i));
283 AnyChange |= ElementTypes[i] != Ty->getContainedType(i);
286 // If we found our type while recursively processing stuff, just use it.
287 Entry = &MappedTypes[Ty];
288 if (*Entry) return *Entry;
290 // If all of the element types mapped directly over, then the type is usable
295 // Otherwise, rebuild a modified type.
296 switch (Ty->getTypeID()) {
297 default: llvm_unreachable("unknown derived type to remap");
298 case Type::ArrayTyID:
299 return *Entry = ArrayType::get(ElementTypes[0],
300 cast<ArrayType>(Ty)->getNumElements());
301 case Type::VectorTyID:
302 return *Entry = VectorType::get(ElementTypes[0],
303 cast<VectorType>(Ty)->getNumElements());
304 case Type::PointerTyID:
305 return *Entry = PointerType::get(ElementTypes[0],
306 cast<PointerType>(Ty)->getAddressSpace());
307 case Type::FunctionTyID:
308 return *Entry = FunctionType::get(ElementTypes[0],
309 makeArrayRef(ElementTypes).slice(1),
310 cast<FunctionType>(Ty)->isVarArg());
311 case Type::StructTyID:
312 // Note that this is only reached for anonymous structs.
313 return *Entry = StructType::get(Ty->getContext(), ElementTypes,
314 cast<StructType>(Ty)->isPacked());
318 // Otherwise, this is an unmapped named struct. If the struct can be directly
319 // mapped over, just use it as-is. This happens in a case when the linked-in
320 // module has something like:
321 // %T = type {%T*, i32}
322 // @GV = global %T* null
323 // where T does not exist at all in the destination module.
325 // The other case we watch for is when the type is not in the destination
326 // module, but that it has to be rebuilt because it refers to something that
327 // is already mapped. For example, if the destination module has:
329 // and the source module has something like
330 // %A' = type { i32 }
331 // %B = type { %A'* }
332 // @GV = global %B* null
333 // then we want to create a new type: "%B = type { %A*}" and have it take the
334 // pristine "%B" name from the source module.
336 // To determine which case this is, we have to recursively walk the type graph
337 // speculating that we'll be able to reuse it unmodified. Only if this is
338 // safe would we map the entire thing over. Because this is an optimization,
339 // and is not required for the prettiness of the linked module, we just skip
340 // it and always rebuild a type here.
341 StructType *STy = cast<StructType>(Ty);
343 // If the type is opaque, we can just use it directly.
344 if (STy->isOpaque()) {
345 // A named structure type from src module is used. Add it to the Set of
346 // identified structs in the destination module.
347 DstStructTypesSet.insert(STy);
351 // Otherwise we create a new type and resolve its body later. This will be
352 // resolved by the top level of get().
353 SrcDefinitionsToResolve.push_back(STy);
354 StructType *DTy = StructType::create(STy->getContext());
355 // A new identified structure type was created. Add it to the set of
356 // identified structs in the destination module.
357 DstStructTypesSet.insert(DTy);
358 DstResolvedOpaqueTypes.insert(DTy);
362 //===----------------------------------------------------------------------===//
363 // ModuleLinker implementation.
364 //===----------------------------------------------------------------------===//
369 /// Creates prototypes for functions that are lazily linked on the fly. This
370 /// speeds up linking for modules with many/ lazily linked functions of which
372 class ValueMaterializerTy : public ValueMaterializer {
375 std::vector<Function *> &LazilyLinkFunctions;
378 ValueMaterializerTy(TypeMapTy &TypeMap, Module *DstM,
379 std::vector<Function *> &LazilyLinkFunctions)
380 : ValueMaterializer(), TypeMap(TypeMap), DstM(DstM),
381 LazilyLinkFunctions(LazilyLinkFunctions) {}
383 Value *materializeValueFor(Value *V) override;
386 class LinkDiagnosticInfo : public DiagnosticInfo {
390 LinkDiagnosticInfo(DiagnosticSeverity Severity, const Twine &Msg);
391 void print(DiagnosticPrinter &DP) const override;
393 LinkDiagnosticInfo::LinkDiagnosticInfo(DiagnosticSeverity Severity,
395 : DiagnosticInfo(DK_Linker, Severity), Msg(Msg) {}
396 void LinkDiagnosticInfo::print(DiagnosticPrinter &DP) const { DP << Msg; }
398 /// This is an implementation class for the LinkModules function, which is the
399 /// entrypoint for this file.
404 ValueMaterializerTy ValMaterializer;
406 /// Mapping of values from what they used to be in Src, to what they are now
407 /// in DstM. ValueToValueMapTy is a ValueMap, which involves some overhead
408 /// due to the use of Value handles which the Linker doesn't actually need,
409 /// but this allows us to reuse the ValueMapper code.
410 ValueToValueMapTy ValueMap;
412 struct AppendingVarInfo {
413 GlobalVariable *NewGV; // New aggregate global in dest module.
414 const Constant *DstInit; // Old initializer from dest module.
415 const Constant *SrcInit; // Old initializer from src module.
418 std::vector<AppendingVarInfo> AppendingVars;
420 // Set of items not to link in from source.
421 SmallPtrSet<const Value *, 16> DoNotLinkFromSource;
423 // Vector of functions to lazily link in.
424 std::vector<Function *> LazilyLinkFunctions;
426 Linker::DiagnosticHandlerFunction DiagnosticHandler;
429 ModuleLinker(Module *dstM, TypeSet &Set, Module *srcM,
430 Linker::DiagnosticHandlerFunction DiagnosticHandler)
431 : DstM(dstM), SrcM(srcM), TypeMap(Set),
432 ValMaterializer(TypeMap, DstM, LazilyLinkFunctions),
433 DiagnosticHandler(DiagnosticHandler) {}
438 bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
439 const GlobalValue &Src);
441 /// Helper method for setting a message and returning an error code.
442 bool emitError(const Twine &Message) {
443 DiagnosticHandler(LinkDiagnosticInfo(DS_Error, Message));
447 void emitWarning(const Twine &Message) {
448 DiagnosticHandler(LinkDiagnosticInfo(DS_Warning, Message));
451 bool getComdatLeader(Module *M, StringRef ComdatName,
452 const GlobalVariable *&GVar);
453 bool computeResultingSelectionKind(StringRef ComdatName,
454 Comdat::SelectionKind Src,
455 Comdat::SelectionKind Dst,
456 Comdat::SelectionKind &Result,
458 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
460 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
463 /// Given a global in the source module, return the global in the
464 /// destination module that is being linked to, if any.
465 GlobalValue *getLinkedToGlobal(const GlobalValue *SrcGV) {
466 // If the source has no name it can't link. If it has local linkage,
467 // there is no name match-up going on.
468 if (!SrcGV->hasName() || SrcGV->hasLocalLinkage())
471 // Otherwise see if we have a match in the destination module's symtab.
472 GlobalValue *DGV = DstM->getNamedValue(SrcGV->getName());
476 // If we found a global with the same name in the dest module, but it has
477 // internal linkage, we are really not doing any linkage here.
478 if (DGV->hasLocalLinkage())
481 // Otherwise, we do in fact link to the destination global.
485 void computeTypeMapping();
487 void upgradeMismatchedGlobalArray(StringRef Name);
488 void upgradeMismatchedGlobals();
490 bool linkAppendingVarProto(GlobalVariable *DstGV,
491 const GlobalVariable *SrcGV);
493 bool linkGlobalValueProto(GlobalValue *GV);
494 GlobalValue *linkGlobalVariableProto(const GlobalVariable *SGVar,
495 GlobalValue *DGV, bool LinkFromSrc);
496 GlobalValue *linkFunctionProto(const Function *SF, GlobalValue *DGV,
498 GlobalValue *linkGlobalAliasProto(const GlobalAlias *SGA, GlobalValue *DGV,
501 bool linkModuleFlagsMetadata();
503 void linkAppendingVarInit(const AppendingVarInfo &AVI);
504 void linkGlobalInits();
505 void linkFunctionBody(Function *Dst, Function *Src);
506 void linkAliasBodies();
507 void linkNamedMDNodes();
511 /// The LLVM SymbolTable class autorenames globals that conflict in the symbol
512 /// table. This is good for all clients except for us. Go through the trouble
513 /// to force this back.
514 static void forceRenaming(GlobalValue *GV, StringRef Name) {
515 // If the global doesn't force its name or if it already has the right name,
516 // there is nothing for us to do.
517 if (GV->hasLocalLinkage() || GV->getName() == Name)
520 Module *M = GV->getParent();
522 // If there is a conflict, rename the conflict.
523 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
524 GV->takeName(ConflictGV);
525 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
526 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
528 GV->setName(Name); // Force the name back
532 /// copy additional attributes (those not needed to construct a GlobalValue)
533 /// from the SrcGV to the DestGV.
534 static void copyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) {
535 // Use the maximum alignment, rather than just copying the alignment of SrcGV.
536 auto *DestGO = dyn_cast<GlobalObject>(DestGV);
539 Alignment = std::max(DestGO->getAlignment(), SrcGV->getAlignment());
541 DestGV->copyAttributesFrom(SrcGV);
544 DestGO->setAlignment(Alignment);
546 forceRenaming(DestGV, SrcGV->getName());
549 static bool isLessConstraining(GlobalValue::VisibilityTypes a,
550 GlobalValue::VisibilityTypes b) {
551 if (a == GlobalValue::HiddenVisibility)
553 if (b == GlobalValue::HiddenVisibility)
555 if (a == GlobalValue::ProtectedVisibility)
557 if (b == GlobalValue::ProtectedVisibility)
562 Value *ValueMaterializerTy::materializeValueFor(Value *V) {
563 Function *SF = dyn_cast<Function>(V);
567 Function *DF = Function::Create(TypeMap.get(SF->getFunctionType()),
568 SF->getLinkage(), SF->getName(), DstM);
569 copyGVAttributes(DF, SF);
571 if (Comdat *SC = SF->getComdat()) {
572 Comdat *DC = DstM->getOrInsertComdat(SC->getName());
576 LazilyLinkFunctions.push_back(SF);
580 bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName,
581 const GlobalVariable *&GVar) {
582 const GlobalValue *GVal = M->getNamedValue(ComdatName);
583 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
584 GVal = GA->getBaseObject();
586 // We cannot resolve the size of the aliasee yet.
587 return emitError("Linking COMDATs named '" + ComdatName +
588 "': COMDAT key involves incomputable alias size.");
591 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
594 "Linking COMDATs named '" + ComdatName +
595 "': GlobalVariable required for data dependent selection!");
600 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
601 Comdat::SelectionKind Src,
602 Comdat::SelectionKind Dst,
603 Comdat::SelectionKind &Result,
605 // The ability to mix Comdat::SelectionKind::Any with
606 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
607 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
608 Dst == Comdat::SelectionKind::Largest;
609 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
610 Src == Comdat::SelectionKind::Largest;
611 if (DstAnyOrLargest && SrcAnyOrLargest) {
612 if (Dst == Comdat::SelectionKind::Largest ||
613 Src == Comdat::SelectionKind::Largest)
614 Result = Comdat::SelectionKind::Largest;
616 Result = Comdat::SelectionKind::Any;
617 } else if (Src == Dst) {
620 return emitError("Linking COMDATs named '" + ComdatName +
621 "': invalid selection kinds!");
625 case Comdat::SelectionKind::Any:
629 case Comdat::SelectionKind::NoDuplicates:
630 return emitError("Linking COMDATs named '" + ComdatName +
631 "': noduplicates has been violated!");
632 case Comdat::SelectionKind::ExactMatch:
633 case Comdat::SelectionKind::Largest:
634 case Comdat::SelectionKind::SameSize: {
635 const GlobalVariable *DstGV;
636 const GlobalVariable *SrcGV;
637 if (getComdatLeader(DstM, ComdatName, DstGV) ||
638 getComdatLeader(SrcM, ComdatName, SrcGV))
641 const DataLayout *DstDL = DstM->getDataLayout();
642 const DataLayout *SrcDL = SrcM->getDataLayout();
643 if (!DstDL || !SrcDL) {
645 "Linking COMDATs named '" + ComdatName +
646 "': can't do size dependent selection without DataLayout!");
649 DstDL->getTypeAllocSize(DstGV->getType()->getPointerElementType());
651 SrcDL->getTypeAllocSize(SrcGV->getType()->getPointerElementType());
652 if (Result == Comdat::SelectionKind::ExactMatch) {
653 if (SrcGV->getInitializer() != DstGV->getInitializer())
654 return emitError("Linking COMDATs named '" + ComdatName +
655 "': ExactMatch violated!");
657 } else if (Result == Comdat::SelectionKind::Largest) {
658 LinkFromSrc = SrcSize > DstSize;
659 } else if (Result == Comdat::SelectionKind::SameSize) {
660 if (SrcSize != DstSize)
661 return emitError("Linking COMDATs named '" + ComdatName +
662 "': SameSize violated!");
665 llvm_unreachable("unknown selection kind");
674 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
675 Comdat::SelectionKind &Result,
677 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
678 StringRef ComdatName = SrcC->getName();
679 Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable();
680 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
682 if (DstCI == ComdatSymTab.end()) {
683 // Use the comdat if it is only available in one of the modules.
689 const Comdat *DstC = &DstCI->second;
690 Comdat::SelectionKind DSK = DstC->getSelectionKind();
691 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
695 bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
696 const GlobalValue &Dest,
697 const GlobalValue &Src) {
698 // We always have to add Src if it has appending linkage.
699 if (Src.hasAppendingLinkage()) {
704 bool SrcIsDeclaration = Src.isDeclarationForLinker();
705 bool DestIsDeclaration = Dest.isDeclarationForLinker();
707 if (SrcIsDeclaration) {
708 // If Src is external or if both Src & Dest are external.. Just link the
709 // external globals, we aren't adding anything.
710 if (Src.hasDLLImportStorageClass()) {
711 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
712 LinkFromSrc = DestIsDeclaration;
715 // If the Dest is weak, use the source linkage.
716 LinkFromSrc = Dest.hasExternalWeakLinkage();
720 if (DestIsDeclaration) {
721 // If Dest is external but Src is not:
726 if (Src.hasCommonLinkage()) {
727 if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
732 if (!Dest.hasCommonLinkage()) {
737 // FIXME: Make datalayout mandatory and just use getDataLayout().
738 DataLayout DL(Dest.getParent());
740 uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
741 uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
742 LinkFromSrc = SrcSize > DestSize;
746 if (Src.isWeakForLinker()) {
747 assert(!Dest.hasExternalWeakLinkage());
748 assert(!Dest.hasAvailableExternallyLinkage());
750 if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
759 if (Dest.isWeakForLinker()) {
760 assert(Src.hasExternalLinkage());
765 assert(!Src.hasExternalWeakLinkage());
766 assert(!Dest.hasExternalWeakLinkage());
767 assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
768 "Unexpected linkage type!");
769 return emitError("Linking globals named '" + Src.getName() +
770 "': symbol multiply defined!");
773 /// Loop over all of the linked values to compute type mappings. For example,
774 /// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct
775 /// types 'Foo' but one got renamed when the module was loaded into the same
777 void ModuleLinker::computeTypeMapping() {
778 for (GlobalValue &SGV : SrcM->globals()) {
779 GlobalValue *DGV = getLinkedToGlobal(&SGV);
783 if (!DGV->hasAppendingLinkage() || !SGV.hasAppendingLinkage()) {
784 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
788 // Unify the element type of appending arrays.
789 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
790 ArrayType *SAT = cast<ArrayType>(SGV.getType()->getElementType());
791 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
794 for (GlobalValue &SGV : *SrcM) {
795 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
796 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
799 for (GlobalValue &SGV : SrcM->aliases()) {
800 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
801 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
804 // Incorporate types by name, scanning all the types in the source module.
805 // At this point, the destination module may have a type "%foo = { i32 }" for
806 // example. When the source module got loaded into the same LLVMContext, if
807 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
808 TypeFinder SrcStructTypes;
809 SrcStructTypes.run(*SrcM, true);
810 SmallPtrSet<StructType*, 32> SrcStructTypesSet(SrcStructTypes.begin(),
811 SrcStructTypes.end());
813 for (unsigned i = 0, e = SrcStructTypes.size(); i != e; ++i) {
814 StructType *ST = SrcStructTypes[i];
815 if (!ST->hasName()) continue;
817 // Check to see if there is a dot in the name followed by a digit.
818 size_t DotPos = ST->getName().rfind('.');
819 if (DotPos == 0 || DotPos == StringRef::npos ||
820 ST->getName().back() == '.' ||
821 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos+1])))
824 // Check to see if the destination module has a struct with the prefix name.
825 if (StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos)))
826 // Don't use it if this actually came from the source module. They're in
827 // the same LLVMContext after all. Also don't use it unless the type is
828 // actually used in the destination module. This can happen in situations
833 // %Z = type { %A } %B = type { %C.1 }
834 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
835 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
836 // %C = type { i8* } %B.3 = type { %C.1 }
838 // When we link Module B with Module A, the '%B' in Module B is
839 // used. However, that would then use '%C.1'. But when we process '%C.1',
840 // we prefer to take the '%C' version. So we are then left with both
841 // '%C.1' and '%C' being used for the same types. This leads to some
842 // variables using one type and some using the other.
843 if (!SrcStructTypesSet.count(DST) && TypeMap.DstStructTypesSet.count(DST))
844 TypeMap.addTypeMapping(DST, ST);
847 // Now that we have discovered all of the type equivalences, get a body for
848 // any 'opaque' types in the dest module that are now resolved.
849 TypeMap.linkDefinedTypeBodies();
852 static void upgradeGlobalArray(GlobalVariable *GV) {
853 ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
854 StructType *OldTy = cast<StructType>(ATy->getElementType());
855 assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
857 // Get the upgraded 3 element type.
858 PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
859 Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
861 StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
863 // Build new constants with a null third field filled in.
864 Constant *OldInitC = GV->getInitializer();
865 ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
866 if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
867 // Invalid initializer; give up.
869 std::vector<Constant *> Initializers;
870 if (OldInit && OldInit->getNumOperands()) {
871 Value *Null = Constant::getNullValue(VoidPtrTy);
872 for (Use &U : OldInit->operands()) {
873 ConstantStruct *Init = cast<ConstantStruct>(U.get());
874 Initializers.push_back(ConstantStruct::get(
875 NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
878 assert(Initializers.size() == ATy->getNumElements() &&
879 "Failed to copy all array elements");
881 // Replace the old GV with a new one.
882 ATy = ArrayType::get(NewTy, Initializers.size());
883 Constant *NewInit = ConstantArray::get(ATy, Initializers);
884 GlobalVariable *NewGV = new GlobalVariable(
885 *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
886 GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
887 GV->isExternallyInitialized());
888 NewGV->copyAttributesFrom(GV);
890 assert(GV->use_empty() && "program cannot use initializer list");
891 GV->eraseFromParent();
894 void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
895 // Look for the global arrays.
896 auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM->getNamedValue(Name));
899 auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM->getNamedValue(Name));
903 // Check if the types already match.
904 auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
906 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
910 // Grab the element types. We can only upgrade an array of a two-field
911 // struct. Only bother if the other one has three-fields.
912 auto *DstEltTy = cast<StructType>(DstTy->getElementType());
913 auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
914 if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
915 upgradeGlobalArray(DstGV);
918 if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
919 upgradeGlobalArray(SrcGV);
921 // We can't upgrade any other differences.
924 void ModuleLinker::upgradeMismatchedGlobals() {
925 upgradeMismatchedGlobalArray("llvm.global_ctors");
926 upgradeMismatchedGlobalArray("llvm.global_dtors");
929 /// If there were any appending global variables, link them together now.
930 /// Return true on error.
931 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
932 const GlobalVariable *SrcGV) {
934 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
935 return emitError("Linking globals named '" + SrcGV->getName() +
936 "': can only link appending global with another appending global!");
938 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
940 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
941 Type *EltTy = DstTy->getElementType();
943 // Check to see that they two arrays agree on type.
944 if (EltTy != SrcTy->getElementType())
945 return emitError("Appending variables with different element types!");
946 if (DstGV->isConstant() != SrcGV->isConstant())
947 return emitError("Appending variables linked with different const'ness!");
949 if (DstGV->getAlignment() != SrcGV->getAlignment())
951 "Appending variables with different alignment need to be linked!");
953 if (DstGV->getVisibility() != SrcGV->getVisibility())
955 "Appending variables with different visibility need to be linked!");
957 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
959 "Appending variables with different unnamed_addr need to be linked!");
961 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
963 "Appending variables with different section name need to be linked!");
965 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements();
966 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
968 // Create the new global variable.
970 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(),
971 DstGV->getLinkage(), /*init*/nullptr, /*name*/"", DstGV,
972 DstGV->getThreadLocalMode(),
973 DstGV->getType()->getAddressSpace());
975 // Propagate alignment, visibility and section info.
976 copyGVAttributes(NG, DstGV);
978 AppendingVarInfo AVI;
980 AVI.DstInit = DstGV->getInitializer();
981 AVI.SrcInit = SrcGV->getInitializer();
982 AppendingVars.push_back(AVI);
984 // Replace any uses of the two global variables with uses of the new
986 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
988 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
989 DstGV->eraseFromParent();
991 // Track the source variable so we don't try to link it.
992 DoNotLinkFromSource.insert(SrcGV);
997 bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) {
998 GlobalValue *DGV = getLinkedToGlobal(SGV);
1000 // Handle the ultra special appending linkage case first.
1001 if (DGV && DGV->hasAppendingLinkage())
1002 return linkAppendingVarProto(cast<GlobalVariable>(DGV),
1003 cast<GlobalVariable>(SGV));
1005 bool LinkFromSrc = true;
1006 Comdat *C = nullptr;
1007 GlobalValue::VisibilityTypes Visibility = SGV->getVisibility();
1008 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
1010 if (const Comdat *SC = SGV->getComdat()) {
1011 Comdat::SelectionKind SK;
1012 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1013 C = DstM->getOrInsertComdat(SC->getName());
1014 C->setSelectionKind(SK);
1016 if (shouldLinkFromSource(LinkFromSrc, *DGV, *SGV))
1021 // Track the source global so that we don't attempt to copy it over when
1022 // processing global initializers.
1023 DoNotLinkFromSource.insert(SGV);
1026 // Make sure to remember this mapping.
1028 ConstantExpr::getBitCast(DGV, TypeMap.get(SGV->getType()));
1032 Visibility = isLessConstraining(Visibility, DGV->getVisibility())
1033 ? DGV->getVisibility()
1035 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1038 if (!LinkFromSrc && !DGV)
1042 if (auto *SGVar = dyn_cast<GlobalVariable>(SGV)) {
1043 NewGV = linkGlobalVariableProto(SGVar, DGV, LinkFromSrc);
1046 } else if (auto *SF = dyn_cast<Function>(SGV)) {
1047 NewGV = linkFunctionProto(SF, DGV, LinkFromSrc);
1049 NewGV = linkGlobalAliasProto(cast<GlobalAlias>(SGV), DGV, LinkFromSrc);
1054 copyGVAttributes(NewGV, SGV);
1056 NewGV->setUnnamedAddr(HasUnnamedAddr);
1057 NewGV->setVisibility(Visibility);
1059 if (auto *NewGO = dyn_cast<GlobalObject>(NewGV)) {
1061 NewGO->setComdat(C);
1064 // Make sure to remember this mapping.
1067 DGV->replaceAllUsesWith(
1068 ConstantExpr::getBitCast(NewGV, DGV->getType()));
1069 DGV->eraseFromParent();
1071 ValueMap[SGV] = NewGV;
1078 /// Loop through the global variables in the src module and merge them into the
1080 GlobalValue *ModuleLinker::linkGlobalVariableProto(const GlobalVariable *SGVar,
1083 unsigned Alignment = 0;
1084 bool ClearConstant = false;
1087 if (DGV->hasCommonLinkage() && SGVar->hasCommonLinkage())
1088 Alignment = std::max(SGVar->getAlignment(), DGV->getAlignment());
1090 auto *DGVar = dyn_cast<GlobalVariable>(DGV);
1091 if (!SGVar->isConstant() || (DGVar && !DGVar->isConstant()))
1092 ClearConstant = true;
1096 if (auto *NewGVar = dyn_cast<GlobalVariable>(DGV)) {
1098 NewGVar->setAlignment(Alignment);
1099 if (NewGVar->isDeclaration() && ClearConstant)
1100 NewGVar->setConstant(false);
1105 // No linking to be performed or linking from the source: simply create an
1106 // identical version of the symbol over in the dest module... the
1107 // initializer will be filled in later by LinkGlobalInits.
1108 GlobalVariable *NewDGV = new GlobalVariable(
1109 *DstM, TypeMap.get(SGVar->getType()->getElementType()),
1110 SGVar->isConstant(), SGVar->getLinkage(), /*init*/ nullptr,
1111 SGVar->getName(), /*insertbefore*/ nullptr, SGVar->getThreadLocalMode(),
1112 SGVar->getType()->getAddressSpace());
1115 NewDGV->setAlignment(Alignment);
1120 /// Link the function in the source module into the destination module if
1121 /// needed, setting up mapping information.
1122 GlobalValue *ModuleLinker::linkFunctionProto(const Function *SF,
1128 // If the function is to be lazily linked, don't create it just yet.
1129 // The ValueMaterializerTy will deal with creating it if it's used.
1130 if (!DGV && (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() ||
1131 SF->hasAvailableExternallyLinkage())) {
1132 DoNotLinkFromSource.insert(SF);
1136 // If there is no linkage to be performed or we are linking from the source,
1138 return Function::Create(TypeMap.get(SF->getFunctionType()), SF->getLinkage(),
1139 SF->getName(), DstM);
1142 /// Set up prototypes for any aliases that come over from the source module.
1143 GlobalValue *ModuleLinker::linkGlobalAliasProto(const GlobalAlias *SGA,
1149 // If there is no linkage to be performed or we're linking from the source,
1151 auto *PTy = cast<PointerType>(TypeMap.get(SGA->getType()));
1152 return GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(),
1153 SGA->getLinkage(), SGA->getName(), DstM);
1156 static void getArrayElements(const Constant *C,
1157 SmallVectorImpl<Constant *> &Dest) {
1158 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1160 for (unsigned i = 0; i != NumElements; ++i)
1161 Dest.push_back(C->getAggregateElement(i));
1164 void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) {
1165 // Merge the initializer.
1166 SmallVector<Constant *, 16> DstElements;
1167 getArrayElements(AVI.DstInit, DstElements);
1169 SmallVector<Constant *, 16> SrcElements;
1170 getArrayElements(AVI.SrcInit, SrcElements);
1172 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
1174 StringRef Name = AVI.NewGV->getName();
1175 bool IsNewStructor =
1176 (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
1177 cast<StructType>(NewType->getElementType())->getNumElements() == 3;
1179 for (auto *V : SrcElements) {
1180 if (IsNewStructor) {
1181 Constant *Key = V->getAggregateElement(2);
1182 if (DoNotLinkFromSource.count(Key))
1185 DstElements.push_back(
1186 MapValue(V, ValueMap, RF_None, &TypeMap, &ValMaterializer));
1188 if (IsNewStructor) {
1189 NewType = ArrayType::get(NewType->getElementType(), DstElements.size());
1190 AVI.NewGV->mutateType(PointerType::get(NewType, 0));
1193 AVI.NewGV->setInitializer(ConstantArray::get(NewType, DstElements));
1196 /// Update the initializers in the Dest module now that all globals that may be
1197 /// referenced are in Dest.
1198 void ModuleLinker::linkGlobalInits() {
1199 // Loop over all of the globals in the src module, mapping them over as we go
1200 for (Module::const_global_iterator I = SrcM->global_begin(),
1201 E = SrcM->global_end(); I != E; ++I) {
1203 // Only process initialized GV's or ones not already in dest.
1204 if (!I->hasInitializer() || DoNotLinkFromSource.count(I)) continue;
1206 // Grab destination global variable.
1207 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[I]);
1208 // Figure out what the initializer looks like in the dest module.
1209 DGV->setInitializer(MapValue(I->getInitializer(), ValueMap,
1210 RF_None, &TypeMap, &ValMaterializer));
1214 /// Copy the source function over into the dest function and fix up references
1215 /// to values. At this point we know that Dest is an external function, and
1216 /// that Src is not.
1217 void ModuleLinker::linkFunctionBody(Function *Dst, Function *Src) {
1218 assert(Src && Dst && Dst->isDeclaration() && !Src->isDeclaration());
1220 // Go through and convert function arguments over, remembering the mapping.
1221 Function::arg_iterator DI = Dst->arg_begin();
1222 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1223 I != E; ++I, ++DI) {
1224 DI->setName(I->getName()); // Copy the name over.
1226 // Add a mapping to our mapping.
1230 // Splice the body of the source function into the dest function.
1231 Dst->getBasicBlockList().splice(Dst->end(), Src->getBasicBlockList());
1233 // At this point, all of the instructions and values of the function are now
1234 // copied over. The only problem is that they are still referencing values in
1235 // the Source function as operands. Loop through all of the operands of the
1236 // functions and patch them up to point to the local versions.
1237 for (Function::iterator BB = Dst->begin(), BE = Dst->end(); BB != BE; ++BB)
1238 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
1239 RemapInstruction(I, ValueMap, RF_IgnoreMissingEntries, &TypeMap,
1242 // There is no need to map the arguments anymore.
1243 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1249 /// Insert all of the aliases in Src into the Dest module.
1250 void ModuleLinker::linkAliasBodies() {
1251 for (Module::alias_iterator I = SrcM->alias_begin(), E = SrcM->alias_end();
1253 if (DoNotLinkFromSource.count(I))
1255 if (Constant *Aliasee = I->getAliasee()) {
1256 GlobalAlias *DA = cast<GlobalAlias>(ValueMap[I]);
1258 MapValue(Aliasee, ValueMap, RF_None, &TypeMap, &ValMaterializer);
1259 DA->setAliasee(Val);
1264 /// Insert all of the named MDNodes in Src into the Dest module.
1265 void ModuleLinker::linkNamedMDNodes() {
1266 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1267 for (Module::const_named_metadata_iterator I = SrcM->named_metadata_begin(),
1268 E = SrcM->named_metadata_end(); I != E; ++I) {
1269 // Don't link module flags here. Do them separately.
1270 if (&*I == SrcModFlags) continue;
1271 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(I->getName());
1272 // Add Src elements into Dest node.
1273 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
1274 DestNMD->addOperand(MapValue(I->getOperand(i), ValueMap,
1275 RF_None, &TypeMap, &ValMaterializer));
1279 /// Merge the linker flags in Src into the Dest module.
1280 bool ModuleLinker::linkModuleFlagsMetadata() {
1281 // If the source module has no module flags, we are done.
1282 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1283 if (!SrcModFlags) return false;
1285 // If the destination module doesn't have module flags yet, then just copy
1286 // over the source module's flags.
1287 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
1288 if (DstModFlags->getNumOperands() == 0) {
1289 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1290 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1295 // First build a map of the existing module flags and requirements.
1296 DenseMap<MDString*, MDNode*> Flags;
1297 SmallSetVector<MDNode*, 16> Requirements;
1298 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1299 MDNode *Op = DstModFlags->getOperand(I);
1300 ConstantInt *Behavior = cast<ConstantInt>(Op->getOperand(0));
1301 MDString *ID = cast<MDString>(Op->getOperand(1));
1303 if (Behavior->getZExtValue() == Module::Require) {
1304 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1310 // Merge in the flags from the source module, and also collect its set of
1312 bool HasErr = false;
1313 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1314 MDNode *SrcOp = SrcModFlags->getOperand(I);
1315 ConstantInt *SrcBehavior = cast<ConstantInt>(SrcOp->getOperand(0));
1316 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1317 MDNode *DstOp = Flags.lookup(ID);
1318 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1320 // If this is a requirement, add it and continue.
1321 if (SrcBehaviorValue == Module::Require) {
1322 // If the destination module does not already have this requirement, add
1324 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1325 DstModFlags->addOperand(SrcOp);
1330 // If there is no existing flag with this ID, just add it.
1333 DstModFlags->addOperand(SrcOp);
1337 // Otherwise, perform a merge.
1338 ConstantInt *DstBehavior = cast<ConstantInt>(DstOp->getOperand(0));
1339 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1341 // If either flag has override behavior, handle it first.
1342 if (DstBehaviorValue == Module::Override) {
1343 // Diagnose inconsistent flags which both have override behavior.
1344 if (SrcBehaviorValue == Module::Override &&
1345 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1346 HasErr |= emitError("linking module flags '" + ID->getString() +
1347 "': IDs have conflicting override values");
1350 } else if (SrcBehaviorValue == Module::Override) {
1351 // Update the destination flag to that of the source.
1352 DstOp->replaceOperandWith(0, SrcBehavior);
1353 DstOp->replaceOperandWith(2, SrcOp->getOperand(2));
1357 // Diagnose inconsistent merge behavior types.
1358 if (SrcBehaviorValue != DstBehaviorValue) {
1359 HasErr |= emitError("linking module flags '" + ID->getString() +
1360 "': IDs have conflicting behaviors");
1364 // Perform the merge for standard behavior types.
1365 switch (SrcBehaviorValue) {
1366 case Module::Require:
1367 case Module::Override: llvm_unreachable("not possible");
1368 case Module::Error: {
1369 // Emit an error if the values differ.
1370 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1371 HasErr |= emitError("linking module flags '" + ID->getString() +
1372 "': IDs have conflicting values");
1376 case Module::Warning: {
1377 // Emit a warning if the values differ.
1378 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1379 emitWarning("linking module flags '" + ID->getString() +
1380 "': IDs have conflicting values");
1384 case Module::Append: {
1385 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1386 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1387 unsigned NumOps = DstValue->getNumOperands() + SrcValue->getNumOperands();
1388 Value **VP, **Values = VP = new Value*[NumOps];
1389 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i, ++VP)
1390 *VP = DstValue->getOperand(i);
1391 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i, ++VP)
1392 *VP = SrcValue->getOperand(i);
1393 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1394 ArrayRef<Value*>(Values,
1399 case Module::AppendUnique: {
1400 SmallSetVector<Value*, 16> Elts;
1401 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1402 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1403 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i)
1404 Elts.insert(DstValue->getOperand(i));
1405 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i)
1406 Elts.insert(SrcValue->getOperand(i));
1407 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1408 ArrayRef<Value*>(Elts.begin(),
1415 // Check all of the requirements.
1416 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1417 MDNode *Requirement = Requirements[I];
1418 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1419 Value *ReqValue = Requirement->getOperand(1);
1421 MDNode *Op = Flags[Flag];
1422 if (!Op || Op->getOperand(2) != ReqValue) {
1423 HasErr |= emitError("linking module flags '" + Flag->getString() +
1424 "': does not have the required value");
1432 bool ModuleLinker::run() {
1433 assert(DstM && "Null destination module");
1434 assert(SrcM && "Null source module");
1436 // Inherit the target data from the source module if the destination module
1437 // doesn't have one already.
1438 if (!DstM->getDataLayout() && SrcM->getDataLayout())
1439 DstM->setDataLayout(SrcM->getDataLayout());
1441 // Copy the target triple from the source to dest if the dest's is empty.
1442 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
1443 DstM->setTargetTriple(SrcM->getTargetTriple());
1445 if (SrcM->getDataLayout() && DstM->getDataLayout() &&
1446 *SrcM->getDataLayout() != *DstM->getDataLayout()) {
1447 emitWarning("Linking two modules of different data layouts: '" +
1448 SrcM->getModuleIdentifier() + "' is '" +
1449 SrcM->getDataLayoutStr() + "' whereas '" +
1450 DstM->getModuleIdentifier() + "' is '" +
1451 DstM->getDataLayoutStr() + "'\n");
1453 if (!SrcM->getTargetTriple().empty() &&
1454 DstM->getTargetTriple() != SrcM->getTargetTriple()) {
1455 emitWarning("Linking two modules of different target triples: " +
1456 SrcM->getModuleIdentifier() + "' is '" +
1457 SrcM->getTargetTriple() + "' whereas '" +
1458 DstM->getModuleIdentifier() + "' is '" +
1459 DstM->getTargetTriple() + "'\n");
1462 // Append the module inline asm string.
1463 if (!SrcM->getModuleInlineAsm().empty()) {
1464 if (DstM->getModuleInlineAsm().empty())
1465 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
1467 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
1468 SrcM->getModuleInlineAsm());
1471 // Loop over all of the linked values to compute type mappings.
1472 computeTypeMapping();
1474 ComdatsChosen.clear();
1475 for (const auto &SMEC : SrcM->getComdatSymbolTable()) {
1476 const Comdat &C = SMEC.getValue();
1477 if (ComdatsChosen.count(&C))
1479 Comdat::SelectionKind SK;
1481 if (getComdatResult(&C, SK, LinkFromSrc))
1483 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1486 // Upgrade mismatched global arrays.
1487 upgradeMismatchedGlobals();
1489 // Insert all of the globals in src into the DstM module... without linking
1490 // initializers (which could refer to functions not yet mapped over).
1491 for (Module::global_iterator I = SrcM->global_begin(),
1492 E = SrcM->global_end(); I != E; ++I)
1493 if (linkGlobalValueProto(I))
1496 // Link the functions together between the two modules, without doing function
1497 // bodies... this just adds external function prototypes to the DstM
1498 // function... We do this so that when we begin processing function bodies,
1499 // all of the global values that may be referenced are available in our
1501 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I)
1502 if (linkGlobalValueProto(I))
1505 // If there were any aliases, link them now.
1506 for (Module::alias_iterator I = SrcM->alias_begin(),
1507 E = SrcM->alias_end(); I != E; ++I)
1508 if (linkGlobalValueProto(I))
1511 for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i)
1512 linkAppendingVarInit(AppendingVars[i]);
1514 // Link in the function bodies that are defined in the source module into
1516 for (Module::iterator SF = SrcM->begin(), E = SrcM->end(); SF != E; ++SF) {
1517 // Skip if not linking from source.
1518 if (DoNotLinkFromSource.count(SF)) continue;
1520 Function *DF = cast<Function>(ValueMap[SF]);
1521 if (SF->hasPrefixData()) {
1522 // Link in the prefix data.
1523 DF->setPrefixData(MapValue(
1524 SF->getPrefixData(), ValueMap, RF_None, &TypeMap, &ValMaterializer));
1527 // Materialize if needed.
1528 if (std::error_code EC = SF->materialize())
1529 return emitError(EC.message());
1531 // Skip if no body (function is external).
1532 if (SF->isDeclaration())
1535 linkFunctionBody(DF, SF);
1536 SF->Dematerialize();
1539 // Resolve all uses of aliases with aliasees.
1542 // Remap all of the named MDNodes in Src into the DstM module. We do this
1543 // after linking GlobalValues so that MDNodes that reference GlobalValues
1544 // are properly remapped.
1547 // Merge the module flags into the DstM module.
1548 if (linkModuleFlagsMetadata())
1551 // Update the initializers in the DstM module now that all globals that may
1552 // be referenced are in DstM.
1555 // Process vector of lazily linked in functions.
1556 bool LinkedInAnyFunctions;
1558 LinkedInAnyFunctions = false;
1560 for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(),
1561 E = LazilyLinkFunctions.end(); I != E; ++I) {
1566 Function *DF = cast<Function>(ValueMap[SF]);
1567 if (SF->hasPrefixData()) {
1568 // Link in the prefix data.
1569 DF->setPrefixData(MapValue(SF->getPrefixData(),
1576 // Materialize if needed.
1577 if (std::error_code EC = SF->materialize())
1578 return emitError(EC.message());
1580 // Skip if no body (function is external).
1581 if (SF->isDeclaration())
1584 // Erase from vector *before* the function body is linked - linkFunctionBody could
1586 LazilyLinkFunctions.erase(I);
1588 // Link in function body.
1589 linkFunctionBody(DF, SF);
1590 SF->Dematerialize();
1592 // Set flag to indicate we may have more functions to lazily link in
1593 // since we linked in a function.
1594 LinkedInAnyFunctions = true;
1597 } while (LinkedInAnyFunctions);
1599 // Now that all of the types from the source are used, resolve any structs
1600 // copied over to the dest that didn't exist there.
1601 TypeMap.linkDefinedTypeBodies();
1606 void Linker::init(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
1607 this->Composite = M;
1608 this->DiagnosticHandler = DiagnosticHandler;
1610 TypeFinder StructTypes;
1611 StructTypes.run(*M, true);
1612 IdentifiedStructTypes.insert(StructTypes.begin(), StructTypes.end());
1615 Linker::Linker(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
1616 init(M, DiagnosticHandler);
1619 Linker::Linker(Module *M) {
1620 init(M, [this](const DiagnosticInfo &DI) {
1621 Composite->getContext().diagnose(DI);
1628 void Linker::deleteModule() {
1630 Composite = nullptr;
1633 bool Linker::linkInModule(Module *Src) {
1634 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,
1636 return TheLinker.run();
1639 //===----------------------------------------------------------------------===//
1640 // LinkModules entrypoint.
1641 //===----------------------------------------------------------------------===//
1643 /// This function links two modules together, with the resulting Dest module
1644 /// modified to be the composite of the two input modules. If an error occurs,
1645 /// true is returned and ErrorMsg (if not null) is set to indicate the problem.
1646 /// Upon failure, the Dest module could be in a modified state, and shouldn't be
1647 /// relied on to be consistent.
1648 bool Linker::LinkModules(Module *Dest, Module *Src,
1649 DiagnosticHandlerFunction DiagnosticHandler) {
1650 Linker L(Dest, DiagnosticHandler);
1651 return L.linkInModule(Src);
1654 bool Linker::LinkModules(Module *Dest, Module *Src) {
1656 return L.linkInModule(Src);
1659 //===----------------------------------------------------------------------===//
1661 //===----------------------------------------------------------------------===//
1663 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
1664 LLVMLinkerMode Mode, char **OutMessages) {
1665 Module *D = unwrap(Dest);
1666 std::string Message;
1667 raw_string_ostream Stream(Message);
1668 DiagnosticPrinterRawOStream DP(Stream);
1670 LLVMBool Result = Linker::LinkModules(
1671 D, unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); });
1673 if (OutMessages && Result)
1674 *OutMessages = strdup(Message.c_str());