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 /// linkDefinedTypeBodies - Produce a body for an opaque type in the dest
67 /// module from a type 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 // Oops, they aren't isomorphic. Just discard this request by rolling out
112 // any speculative mappings we've established.
113 for (unsigned i = 0, e = SpeculativeTypes.size(); i != e; ++i)
114 MappedTypes.erase(SpeculativeTypes[i]);
116 SpeculativeTypes.clear();
119 /// Recursively walk this pair of types, returning true if they are isomorphic,
120 /// false if they are not.
121 bool TypeMapTy::areTypesIsomorphic(Type *DstTy, Type *SrcTy) {
122 // Two types with differing kinds are clearly not isomorphic.
123 if (DstTy->getTypeID() != SrcTy->getTypeID()) return false;
125 // If we have an entry in the MappedTypes table, then we have our answer.
126 Type *&Entry = MappedTypes[SrcTy];
128 return Entry == DstTy;
130 // Two identical types are clearly isomorphic. Remember this
131 // non-speculatively.
132 if (DstTy == SrcTy) {
137 // Okay, we have two types with identical kinds that we haven't seen before.
139 // If this is an opaque struct type, special case it.
140 if (StructType *SSTy = dyn_cast<StructType>(SrcTy)) {
141 // Mapping an opaque type to any struct, just keep the dest struct.
142 if (SSTy->isOpaque()) {
144 SpeculativeTypes.push_back(SrcTy);
148 // Mapping a non-opaque source type to an opaque dest. If this is the first
149 // type that we're mapping onto this destination type then we succeed. Keep
150 // the dest, but fill it in later. This doesn't need to be speculative. If
151 // this is the second (different) type that we're trying to map onto the
152 // same opaque type then we fail.
153 if (cast<StructType>(DstTy)->isOpaque()) {
154 // We can only map one source type onto the opaque destination type.
155 if (!DstResolvedOpaqueTypes.insert(cast<StructType>(DstTy)).second)
157 SrcDefinitionsToResolve.push_back(SSTy);
163 // If the number of subtypes disagree between the two types, then we fail.
164 if (SrcTy->getNumContainedTypes() != DstTy->getNumContainedTypes())
167 // Fail if any of the extra properties (e.g. array size) of the type disagree.
168 if (isa<IntegerType>(DstTy))
169 return false; // bitwidth disagrees.
170 if (PointerType *PT = dyn_cast<PointerType>(DstTy)) {
171 if (PT->getAddressSpace() != cast<PointerType>(SrcTy)->getAddressSpace())
174 } else if (FunctionType *FT = dyn_cast<FunctionType>(DstTy)) {
175 if (FT->isVarArg() != cast<FunctionType>(SrcTy)->isVarArg())
177 } else if (StructType *DSTy = dyn_cast<StructType>(DstTy)) {
178 StructType *SSTy = cast<StructType>(SrcTy);
179 if (DSTy->isLiteral() != SSTy->isLiteral() ||
180 DSTy->isPacked() != SSTy->isPacked())
182 } else if (ArrayType *DATy = dyn_cast<ArrayType>(DstTy)) {
183 if (DATy->getNumElements() != cast<ArrayType>(SrcTy)->getNumElements())
185 } else if (VectorType *DVTy = dyn_cast<VectorType>(DstTy)) {
186 if (DVTy->getNumElements() != cast<VectorType>(SrcTy)->getNumElements())
190 // Otherwise, we speculate that these two types will line up and recursively
191 // check the subelements.
193 SpeculativeTypes.push_back(SrcTy);
195 for (unsigned i = 0, e = SrcTy->getNumContainedTypes(); i != e; ++i)
196 if (!areTypesIsomorphic(DstTy->getContainedType(i),
197 SrcTy->getContainedType(i)))
200 // If everything seems to have lined up, then everything is great.
204 /// Produce a body for an opaque type in the dest module from a type definition
205 /// in the source module.
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;
368 ValueMaterializerTy(TypeMapTy &TypeMap, Module *DstM,
369 std::vector<Function*> &LazilyLinkFunctions) :
370 ValueMaterializer(), TypeMap(TypeMap), DstM(DstM),
371 LazilyLinkFunctions(LazilyLinkFunctions) {
374 Value *materializeValueFor(Value *V) override;
378 class LinkDiagnosticInfo : public DiagnosticInfo {
382 LinkDiagnosticInfo(DiagnosticSeverity Severity, const Twine &Msg);
383 void print(DiagnosticPrinter &DP) const override;
385 LinkDiagnosticInfo::LinkDiagnosticInfo(DiagnosticSeverity Severity,
387 : DiagnosticInfo(DK_Linker, Severity), Msg(Msg) {}
388 void LinkDiagnosticInfo::print(DiagnosticPrinter &DP) const { DP << Msg; }
391 /// This is an implementation class for the LinkModules function, which is the
392 /// entrypoint for this file.
397 ValueMaterializerTy ValMaterializer;
399 /// Mapping of values from what they used to be in Src, to what they are now
400 /// in DstM. ValueToValueMapTy is a ValueMap, which involves some overhead
401 /// due to the use of Value handles which the Linker doesn't actually need,
402 /// but this allows us to reuse the ValueMapper code.
403 ValueToValueMapTy ValueMap;
405 struct AppendingVarInfo {
406 GlobalVariable *NewGV; // New aggregate global in dest module.
407 const Constant *DstInit; // Old initializer from dest module.
408 const Constant *SrcInit; // Old initializer from src module.
411 std::vector<AppendingVarInfo> AppendingVars;
413 // Set of items not to link in from source.
414 SmallPtrSet<const Value*, 16> DoNotLinkFromSource;
416 // Vector of functions to lazily link in.
417 std::vector<Function*> LazilyLinkFunctions;
419 Linker::DiagnosticHandlerFunction DiagnosticHandler;
422 ModuleLinker(Module *dstM, TypeSet &Set, Module *srcM,
423 Linker::DiagnosticHandlerFunction DiagnosticHandler)
424 : DstM(dstM), SrcM(srcM), TypeMap(Set),
425 ValMaterializer(TypeMap, DstM, LazilyLinkFunctions),
426 DiagnosticHandler(DiagnosticHandler) {}
431 bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
432 const GlobalValue &Src);
434 /// Helper method for setting a message and returning an error code.
435 bool emitError(const Twine &Message) {
436 DiagnosticHandler(LinkDiagnosticInfo(DS_Error, Message));
440 void emitWarning(const Twine &Message) {
441 DiagnosticHandler(LinkDiagnosticInfo(DS_Warning, Message));
444 bool getComdatLeader(Module *M, StringRef ComdatName,
445 const GlobalVariable *&GVar);
446 bool computeResultingSelectionKind(StringRef ComdatName,
447 Comdat::SelectionKind Src,
448 Comdat::SelectionKind Dst,
449 Comdat::SelectionKind &Result,
451 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
453 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
456 /// Given a global in the source module, return the global in the
457 /// destination module that is being linked to, if any.
458 GlobalValue *getLinkedToGlobal(const GlobalValue *SrcGV) {
459 // If the source has no name it can't link. If it has local linkage,
460 // there is no name match-up going on.
461 if (!SrcGV->hasName() || SrcGV->hasLocalLinkage())
464 // Otherwise see if we have a match in the destination module's symtab.
465 GlobalValue *DGV = DstM->getNamedValue(SrcGV->getName());
466 if (!DGV) return nullptr;
468 // If we found a global with the same name in the dest module, but it has
469 // internal linkage, we are really not doing any linkage here.
470 if (DGV->hasLocalLinkage())
473 // Otherwise, we do in fact link to the destination global.
477 void computeTypeMapping();
479 void upgradeMismatchedGlobalArray(StringRef Name);
480 void upgradeMismatchedGlobals();
482 bool linkAppendingVarProto(GlobalVariable *DstGV,
483 const GlobalVariable *SrcGV);
485 bool linkGlobalValueProto(GlobalValue *GV);
486 GlobalValue *linkGlobalVariableProto(const GlobalVariable *SGVar,
487 GlobalValue *DGV, bool LinkFromSrc);
488 GlobalValue *linkFunctionProto(const Function *SF, GlobalValue *DGV,
490 GlobalValue *linkGlobalAliasProto(const GlobalAlias *SGA, GlobalValue *DGV,
493 bool linkModuleFlagsMetadata();
495 void linkAppendingVarInit(const AppendingVarInfo &AVI);
496 void linkGlobalInits();
497 void linkFunctionBody(Function *Dst, Function *Src);
498 void linkAliasBodies();
499 void linkNamedMDNodes();
503 /// The LLVM SymbolTable class autorenames globals that conflict in the symbol
504 /// table. This is good for all clients except for us. Go through the trouble
505 /// to force this back.
506 static void forceRenaming(GlobalValue *GV, StringRef Name) {
507 // If the global doesn't force its name or if it already has the right name,
508 // there is nothing for us to do.
509 if (GV->hasLocalLinkage() || GV->getName() == Name)
512 Module *M = GV->getParent();
514 // If there is a conflict, rename the conflict.
515 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
516 GV->takeName(ConflictGV);
517 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
518 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
520 GV->setName(Name); // Force the name back
524 /// copy additional attributes (those not needed to construct a GlobalValue)
525 /// from the SrcGV to the DestGV.
526 static void copyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) {
527 // Use the maximum alignment, rather than just copying the alignment of SrcGV.
528 auto *DestGO = dyn_cast<GlobalObject>(DestGV);
531 Alignment = std::max(DestGO->getAlignment(), SrcGV->getAlignment());
533 DestGV->copyAttributesFrom(SrcGV);
536 DestGO->setAlignment(Alignment);
538 forceRenaming(DestGV, SrcGV->getName());
541 static bool isLessConstraining(GlobalValue::VisibilityTypes a,
542 GlobalValue::VisibilityTypes b) {
543 if (a == GlobalValue::HiddenVisibility)
545 if (b == GlobalValue::HiddenVisibility)
547 if (a == GlobalValue::ProtectedVisibility)
549 if (b == GlobalValue::ProtectedVisibility)
554 Value *ValueMaterializerTy::materializeValueFor(Value *V) {
555 Function *SF = dyn_cast<Function>(V);
559 Function *DF = Function::Create(TypeMap.get(SF->getFunctionType()),
560 SF->getLinkage(), SF->getName(), DstM);
561 copyGVAttributes(DF, SF);
563 if (Comdat *SC = SF->getComdat()) {
564 Comdat *DC = DstM->getOrInsertComdat(SC->getName());
568 LazilyLinkFunctions.push_back(SF);
572 bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName,
573 const GlobalVariable *&GVar) {
574 const GlobalValue *GVal = M->getNamedValue(ComdatName);
575 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
576 GVal = GA->getBaseObject();
578 // We cannot resolve the size of the aliasee yet.
579 return emitError("Linking COMDATs named '" + ComdatName +
580 "': COMDAT key involves incomputable alias size.");
583 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
586 "Linking COMDATs named '" + ComdatName +
587 "': GlobalVariable required for data dependent selection!");
592 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
593 Comdat::SelectionKind Src,
594 Comdat::SelectionKind Dst,
595 Comdat::SelectionKind &Result,
597 // The ability to mix Comdat::SelectionKind::Any with
598 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
599 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
600 Dst == Comdat::SelectionKind::Largest;
601 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
602 Src == Comdat::SelectionKind::Largest;
603 if (DstAnyOrLargest && SrcAnyOrLargest) {
604 if (Dst == Comdat::SelectionKind::Largest ||
605 Src == Comdat::SelectionKind::Largest)
606 Result = Comdat::SelectionKind::Largest;
608 Result = Comdat::SelectionKind::Any;
609 } else if (Src == Dst) {
612 return emitError("Linking COMDATs named '" + ComdatName +
613 "': invalid selection kinds!");
617 case Comdat::SelectionKind::Any:
621 case Comdat::SelectionKind::NoDuplicates:
622 return emitError("Linking COMDATs named '" + ComdatName +
623 "': noduplicates has been violated!");
624 case Comdat::SelectionKind::ExactMatch:
625 case Comdat::SelectionKind::Largest:
626 case Comdat::SelectionKind::SameSize: {
627 const GlobalVariable *DstGV;
628 const GlobalVariable *SrcGV;
629 if (getComdatLeader(DstM, ComdatName, DstGV) ||
630 getComdatLeader(SrcM, ComdatName, SrcGV))
633 const DataLayout *DstDL = DstM->getDataLayout();
634 const DataLayout *SrcDL = SrcM->getDataLayout();
635 if (!DstDL || !SrcDL) {
637 "Linking COMDATs named '" + ComdatName +
638 "': can't do size dependent selection without DataLayout!");
641 DstDL->getTypeAllocSize(DstGV->getType()->getPointerElementType());
643 SrcDL->getTypeAllocSize(SrcGV->getType()->getPointerElementType());
644 if (Result == Comdat::SelectionKind::ExactMatch) {
645 if (SrcGV->getInitializer() != DstGV->getInitializer())
646 return emitError("Linking COMDATs named '" + ComdatName +
647 "': ExactMatch violated!");
649 } else if (Result == Comdat::SelectionKind::Largest) {
650 LinkFromSrc = SrcSize > DstSize;
651 } else if (Result == Comdat::SelectionKind::SameSize) {
652 if (SrcSize != DstSize)
653 return emitError("Linking COMDATs named '" + ComdatName +
654 "': SameSize violated!");
657 llvm_unreachable("unknown selection kind");
666 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
667 Comdat::SelectionKind &Result,
669 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
670 StringRef ComdatName = SrcC->getName();
671 Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable();
672 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
674 if (DstCI == ComdatSymTab.end()) {
675 // Use the comdat if it is only available in one of the modules.
681 const Comdat *DstC = &DstCI->second;
682 Comdat::SelectionKind DSK = DstC->getSelectionKind();
683 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
687 bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
688 const GlobalValue &Dest,
689 const GlobalValue &Src) {
690 // We always have to add Src if it has appending linkage.
691 if (Src.hasAppendingLinkage()) {
696 bool SrcIsDeclaration = Src.isDeclarationForLinker();
697 bool DestIsDeclaration = Dest.isDeclarationForLinker();
699 if (SrcIsDeclaration) {
700 // If Src is external or if both Src & Dest are external.. Just link the
701 // external globals, we aren't adding anything.
702 if (Src.hasDLLImportStorageClass()) {
703 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
704 LinkFromSrc = DestIsDeclaration;
707 // If the Dest is weak, use the source linkage.
708 LinkFromSrc = Dest.hasExternalWeakLinkage();
712 if (DestIsDeclaration) {
713 // If Dest is external but Src is not:
718 if (Src.hasCommonLinkage()) {
719 if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
724 if (!Dest.hasCommonLinkage()) {
729 // FIXME: Make datalayout mandatory and just use getDataLayout().
730 DataLayout DL(Dest.getParent());
732 uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
733 uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
734 LinkFromSrc = SrcSize > DestSize;
738 if (Src.isWeakForLinker()) {
739 assert(!Dest.hasExternalWeakLinkage());
740 assert(!Dest.hasAvailableExternallyLinkage());
742 if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
751 if (Dest.isWeakForLinker()) {
752 assert(Src.hasExternalLinkage());
757 assert(!Src.hasExternalWeakLinkage());
758 assert(!Dest.hasExternalWeakLinkage());
759 assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
760 "Unexpected linkage type!");
761 return emitError("Linking globals named '" + Src.getName() +
762 "': symbol multiply defined!");
765 /// Loop over all of the linked values to compute type mappings. For example,
766 /// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct
767 /// types 'Foo' but one got renamed when the module was loaded into the same
769 void ModuleLinker::computeTypeMapping() {
770 for (GlobalValue &SGV : SrcM->globals()) {
771 GlobalValue *DGV = getLinkedToGlobal(&SGV);
775 if (!DGV->hasAppendingLinkage() || !SGV.hasAppendingLinkage()) {
776 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
780 // Unify the element type of appending arrays.
781 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
782 ArrayType *SAT = cast<ArrayType>(SGV.getType()->getElementType());
783 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
786 for (GlobalValue &SGV : *SrcM) {
787 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
788 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
791 // Incorporate types by name, scanning all the types in the source module.
792 // At this point, the destination module may have a type "%foo = { i32 }" for
793 // example. When the source module got loaded into the same LLVMContext, if
794 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
795 TypeFinder SrcStructTypes;
796 SrcStructTypes.run(*SrcM, true);
797 SmallPtrSet<StructType*, 32> SrcStructTypesSet(SrcStructTypes.begin(),
798 SrcStructTypes.end());
800 for (unsigned i = 0, e = SrcStructTypes.size(); i != e; ++i) {
801 StructType *ST = SrcStructTypes[i];
802 if (!ST->hasName()) continue;
804 // Check to see if there is a dot in the name followed by a digit.
805 size_t DotPos = ST->getName().rfind('.');
806 if (DotPos == 0 || DotPos == StringRef::npos ||
807 ST->getName().back() == '.' ||
808 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos+1])))
811 // Check to see if the destination module has a struct with the prefix name.
812 if (StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos)))
813 // Don't use it if this actually came from the source module. They're in
814 // the same LLVMContext after all. Also don't use it unless the type is
815 // actually used in the destination module. This can happen in situations
820 // %Z = type { %A } %B = type { %C.1 }
821 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
822 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
823 // %C = type { i8* } %B.3 = type { %C.1 }
825 // When we link Module B with Module A, the '%B' in Module B is
826 // used. However, that would then use '%C.1'. But when we process '%C.1',
827 // we prefer to take the '%C' version. So we are then left with both
828 // '%C.1' and '%C' being used for the same types. This leads to some
829 // variables using one type and some using the other.
830 if (!SrcStructTypesSet.count(DST) && TypeMap.DstStructTypesSet.count(DST))
831 TypeMap.addTypeMapping(DST, ST);
834 // Don't bother incorporating aliases, they aren't generally typed well.
836 // Now that we have discovered all of the type equivalences, get a body for
837 // any 'opaque' types in the dest module that are now resolved.
838 TypeMap.linkDefinedTypeBodies();
841 static void upgradeGlobalArray(GlobalVariable *GV) {
842 ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
843 StructType *OldTy = cast<StructType>(ATy->getElementType());
844 assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
846 // Get the upgraded 3 element type.
847 PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
848 Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
850 StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
852 // Build new constants with a null third field filled in.
853 Constant *OldInitC = GV->getInitializer();
854 ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
855 if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
856 // Invalid initializer; give up.
858 std::vector<Constant *> Initializers;
859 if (OldInit && OldInit->getNumOperands()) {
860 Value *Null = Constant::getNullValue(VoidPtrTy);
861 for (Use &U : OldInit->operands()) {
862 ConstantStruct *Init = cast<ConstantStruct>(U.get());
863 Initializers.push_back(ConstantStruct::get(
864 NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
867 assert(Initializers.size() == ATy->getNumElements() &&
868 "Failed to copy all array elements");
870 // Replace the old GV with a new one.
871 ATy = ArrayType::get(NewTy, Initializers.size());
872 Constant *NewInit = ConstantArray::get(ATy, Initializers);
873 GlobalVariable *NewGV = new GlobalVariable(
874 *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
875 GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
876 GV->isExternallyInitialized());
877 NewGV->copyAttributesFrom(GV);
879 assert(GV->use_empty() && "program cannot use initializer list");
880 GV->eraseFromParent();
883 void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
884 // Look for the global arrays.
885 auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM->getNamedValue(Name));
888 auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM->getNamedValue(Name));
892 // Check if the types already match.
893 auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
895 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
899 // Grab the element types. We can only upgrade an array of a two-field
900 // struct. Only bother if the other one has three-fields.
901 auto *DstEltTy = cast<StructType>(DstTy->getElementType());
902 auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
903 if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
904 upgradeGlobalArray(DstGV);
907 if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
908 upgradeGlobalArray(SrcGV);
910 // We can't upgrade any other differences.
913 void ModuleLinker::upgradeMismatchedGlobals() {
914 upgradeMismatchedGlobalArray("llvm.global_ctors");
915 upgradeMismatchedGlobalArray("llvm.global_dtors");
918 /// If there were any appending global variables, link them together now.
919 /// Return true on error.
920 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
921 const GlobalVariable *SrcGV) {
923 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
924 return emitError("Linking globals named '" + SrcGV->getName() +
925 "': can only link appending global with another appending global!");
927 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
929 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
930 Type *EltTy = DstTy->getElementType();
932 // Check to see that they two arrays agree on type.
933 if (EltTy != SrcTy->getElementType())
934 return emitError("Appending variables with different element types!");
935 if (DstGV->isConstant() != SrcGV->isConstant())
936 return emitError("Appending variables linked with different const'ness!");
938 if (DstGV->getAlignment() != SrcGV->getAlignment())
940 "Appending variables with different alignment need to be linked!");
942 if (DstGV->getVisibility() != SrcGV->getVisibility())
944 "Appending variables with different visibility need to be linked!");
946 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
948 "Appending variables with different unnamed_addr need to be linked!");
950 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
952 "Appending variables with different section name need to be linked!");
954 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements();
955 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
957 // Create the new global variable.
959 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(),
960 DstGV->getLinkage(), /*init*/nullptr, /*name*/"", DstGV,
961 DstGV->getThreadLocalMode(),
962 DstGV->getType()->getAddressSpace());
964 // Propagate alignment, visibility and section info.
965 copyGVAttributes(NG, DstGV);
967 AppendingVarInfo AVI;
969 AVI.DstInit = DstGV->getInitializer();
970 AVI.SrcInit = SrcGV->getInitializer();
971 AppendingVars.push_back(AVI);
973 // Replace any uses of the two global variables with uses of the new
975 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
977 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
978 DstGV->eraseFromParent();
980 // Track the source variable so we don't try to link it.
981 DoNotLinkFromSource.insert(SrcGV);
986 bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) {
987 GlobalValue *DGV = getLinkedToGlobal(SGV);
989 // Handle the ultra special appending linkage case first.
990 if (DGV && DGV->hasAppendingLinkage())
991 return linkAppendingVarProto(cast<GlobalVariable>(DGV),
992 cast<GlobalVariable>(SGV));
994 bool LinkFromSrc = true;
996 GlobalValue::VisibilityTypes Visibility = SGV->getVisibility();
997 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
999 if (const Comdat *SC = SGV->getComdat()) {
1000 Comdat::SelectionKind SK;
1001 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1002 C = DstM->getOrInsertComdat(SC->getName());
1003 C->setSelectionKind(SK);
1005 if (shouldLinkFromSource(LinkFromSrc, *DGV, *SGV))
1010 // Track the source global so that we don't attempt to copy it over when
1011 // processing global initializers.
1012 DoNotLinkFromSource.insert(SGV);
1015 // Make sure to remember this mapping.
1017 ConstantExpr::getBitCast(DGV, TypeMap.get(SGV->getType()));
1021 Visibility = isLessConstraining(Visibility, DGV->getVisibility())
1022 ? DGV->getVisibility()
1024 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1027 if (!LinkFromSrc && !DGV)
1031 if (auto *SGVar = dyn_cast<GlobalVariable>(SGV)) {
1032 NewGV = linkGlobalVariableProto(SGVar, DGV, LinkFromSrc);
1035 } else if (auto *SF = dyn_cast<Function>(SGV)) {
1036 NewGV = linkFunctionProto(SF, DGV, LinkFromSrc);
1038 NewGV = linkGlobalAliasProto(cast<GlobalAlias>(SGV), DGV, LinkFromSrc);
1043 copyGVAttributes(NewGV, SGV);
1045 NewGV->setUnnamedAddr(HasUnnamedAddr);
1046 NewGV->setVisibility(Visibility);
1048 if (auto *NewGO = dyn_cast<GlobalObject>(NewGV)) {
1050 NewGO->setComdat(C);
1053 // Make sure to remember this mapping.
1056 DGV->replaceAllUsesWith(
1057 ConstantExpr::getBitCast(NewGV, DGV->getType()));
1058 DGV->eraseFromParent();
1060 ValueMap[SGV] = NewGV;
1067 /// Loop through the global variables in the src module and merge them into the
1069 GlobalValue *ModuleLinker::linkGlobalVariableProto(const GlobalVariable *SGVar,
1072 unsigned Alignment = 0;
1073 bool ClearConstant = false;
1076 if (DGV->hasCommonLinkage() && SGVar->hasCommonLinkage())
1077 Alignment = std::max(SGVar->getAlignment(), DGV->getAlignment());
1079 auto *DGVar = dyn_cast<GlobalVariable>(DGV);
1080 if (!SGVar->isConstant() || (DGVar && !DGVar->isConstant()))
1081 ClearConstant = true;
1085 if (auto *NewGVar = dyn_cast<GlobalVariable>(DGV)) {
1087 NewGVar->setAlignment(Alignment);
1088 if (NewGVar->isDeclaration() && ClearConstant)
1089 NewGVar->setConstant(false);
1094 // No linking to be performed or linking from the source: simply create an
1095 // identical version of the symbol over in the dest module... the
1096 // initializer will be filled in later by LinkGlobalInits.
1097 GlobalVariable *NewDGV = new GlobalVariable(
1098 *DstM, TypeMap.get(SGVar->getType()->getElementType()),
1099 SGVar->isConstant(), SGVar->getLinkage(), /*init*/ nullptr,
1100 SGVar->getName(), /*insertbefore*/ nullptr, SGVar->getThreadLocalMode(),
1101 SGVar->getType()->getAddressSpace());
1104 NewDGV->setAlignment(Alignment);
1109 /// Link the function in the source module into the destination module if
1110 /// needed, setting up mapping information.
1111 GlobalValue *ModuleLinker::linkFunctionProto(const Function *SF,
1117 // If the function is to be lazily linked, don't create it just yet.
1118 // The ValueMaterializerTy will deal with creating it if it's used.
1119 if (!DGV && (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() ||
1120 SF->hasAvailableExternallyLinkage())) {
1121 DoNotLinkFromSource.insert(SF);
1125 // If there is no linkage to be performed or we are linking from the source,
1127 return Function::Create(TypeMap.get(SF->getFunctionType()), SF->getLinkage(),
1128 SF->getName(), DstM);
1131 /// Set up prototypes for any aliases that come over from the source module.
1132 GlobalValue *ModuleLinker::linkGlobalAliasProto(const GlobalAlias *SGA,
1138 // If there is no linkage to be performed or we're linking from the source,
1140 auto *PTy = cast<PointerType>(TypeMap.get(SGA->getType()));
1141 return GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(),
1142 SGA->getLinkage(), SGA->getName(), DstM);
1145 static void getArrayElements(const Constant *C,
1146 SmallVectorImpl<Constant *> &Dest) {
1147 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1149 for (unsigned i = 0; i != NumElements; ++i)
1150 Dest.push_back(C->getAggregateElement(i));
1153 void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) {
1154 // Merge the initializer.
1155 SmallVector<Constant *, 16> DstElements;
1156 getArrayElements(AVI.DstInit, DstElements);
1158 SmallVector<Constant *, 16> SrcElements;
1159 getArrayElements(AVI.SrcInit, SrcElements);
1161 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
1163 StringRef Name = AVI.NewGV->getName();
1164 bool IsNewStructor =
1165 (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
1166 cast<StructType>(NewType->getElementType())->getNumElements() == 3;
1168 for (auto *V : SrcElements) {
1169 if (IsNewStructor) {
1170 Constant *Key = V->getAggregateElement(2);
1171 if (DoNotLinkFromSource.count(Key))
1174 DstElements.push_back(
1175 MapValue(V, ValueMap, RF_None, &TypeMap, &ValMaterializer));
1177 if (IsNewStructor) {
1178 NewType = ArrayType::get(NewType->getElementType(), DstElements.size());
1179 AVI.NewGV->mutateType(PointerType::get(NewType, 0));
1182 AVI.NewGV->setInitializer(ConstantArray::get(NewType, DstElements));
1185 /// Update the initializers in the Dest module now that all globals that may be
1186 /// referenced are in Dest.
1187 void ModuleLinker::linkGlobalInits() {
1188 // Loop over all of the globals in the src module, mapping them over as we go
1189 for (Module::const_global_iterator I = SrcM->global_begin(),
1190 E = SrcM->global_end(); I != E; ++I) {
1192 // Only process initialized GV's or ones not already in dest.
1193 if (!I->hasInitializer() || DoNotLinkFromSource.count(I)) continue;
1195 // Grab destination global variable.
1196 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[I]);
1197 // Figure out what the initializer looks like in the dest module.
1198 DGV->setInitializer(MapValue(I->getInitializer(), ValueMap,
1199 RF_None, &TypeMap, &ValMaterializer));
1203 /// Copy the source function over into the dest function and fix up references
1204 /// to values. At this point we know that Dest is an external function, and
1205 /// that Src is not.
1206 void ModuleLinker::linkFunctionBody(Function *Dst, Function *Src) {
1207 assert(Src && Dst && Dst->isDeclaration() && !Src->isDeclaration());
1209 // Go through and convert function arguments over, remembering the mapping.
1210 Function::arg_iterator DI = Dst->arg_begin();
1211 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1212 I != E; ++I, ++DI) {
1213 DI->setName(I->getName()); // Copy the name over.
1215 // Add a mapping to our mapping.
1219 // Splice the body of the source function into the dest function.
1220 Dst->getBasicBlockList().splice(Dst->end(), Src->getBasicBlockList());
1222 // At this point, all of the instructions and values of the function are now
1223 // copied over. The only problem is that they are still referencing values in
1224 // the Source function as operands. Loop through all of the operands of the
1225 // functions and patch them up to point to the local versions.
1226 for (Function::iterator BB = Dst->begin(), BE = Dst->end(); BB != BE; ++BB)
1227 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
1228 RemapInstruction(I, ValueMap, RF_IgnoreMissingEntries, &TypeMap,
1231 // There is no need to map the arguments anymore.
1232 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1238 /// Insert all of the aliases in Src into the Dest module.
1239 void ModuleLinker::linkAliasBodies() {
1240 for (Module::alias_iterator I = SrcM->alias_begin(), E = SrcM->alias_end();
1242 if (DoNotLinkFromSource.count(I))
1244 if (Constant *Aliasee = I->getAliasee()) {
1245 GlobalAlias *DA = cast<GlobalAlias>(ValueMap[I]);
1247 MapValue(Aliasee, ValueMap, RF_None, &TypeMap, &ValMaterializer);
1248 DA->setAliasee(Val);
1253 /// Insert all of the named MDNodes in Src into the Dest module.
1254 void ModuleLinker::linkNamedMDNodes() {
1255 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1256 for (Module::const_named_metadata_iterator I = SrcM->named_metadata_begin(),
1257 E = SrcM->named_metadata_end(); I != E; ++I) {
1258 // Don't link module flags here. Do them separately.
1259 if (&*I == SrcModFlags) continue;
1260 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(I->getName());
1261 // Add Src elements into Dest node.
1262 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
1263 DestNMD->addOperand(MapValue(I->getOperand(i), ValueMap,
1264 RF_None, &TypeMap, &ValMaterializer));
1268 /// Merge the linker flags in Src into the Dest module.
1269 bool ModuleLinker::linkModuleFlagsMetadata() {
1270 // If the source module has no module flags, we are done.
1271 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1272 if (!SrcModFlags) return false;
1274 // If the destination module doesn't have module flags yet, then just copy
1275 // over the source module's flags.
1276 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
1277 if (DstModFlags->getNumOperands() == 0) {
1278 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1279 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1284 // First build a map of the existing module flags and requirements.
1285 DenseMap<MDString*, MDNode*> Flags;
1286 SmallSetVector<MDNode*, 16> Requirements;
1287 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1288 MDNode *Op = DstModFlags->getOperand(I);
1289 ConstantInt *Behavior = cast<ConstantInt>(Op->getOperand(0));
1290 MDString *ID = cast<MDString>(Op->getOperand(1));
1292 if (Behavior->getZExtValue() == Module::Require) {
1293 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1299 // Merge in the flags from the source module, and also collect its set of
1301 bool HasErr = false;
1302 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1303 MDNode *SrcOp = SrcModFlags->getOperand(I);
1304 ConstantInt *SrcBehavior = cast<ConstantInt>(SrcOp->getOperand(0));
1305 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1306 MDNode *DstOp = Flags.lookup(ID);
1307 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1309 // If this is a requirement, add it and continue.
1310 if (SrcBehaviorValue == Module::Require) {
1311 // If the destination module does not already have this requirement, add
1313 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1314 DstModFlags->addOperand(SrcOp);
1319 // If there is no existing flag with this ID, just add it.
1322 DstModFlags->addOperand(SrcOp);
1326 // Otherwise, perform a merge.
1327 ConstantInt *DstBehavior = cast<ConstantInt>(DstOp->getOperand(0));
1328 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1330 // If either flag has override behavior, handle it first.
1331 if (DstBehaviorValue == Module::Override) {
1332 // Diagnose inconsistent flags which both have override behavior.
1333 if (SrcBehaviorValue == Module::Override &&
1334 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1335 HasErr |= emitError("linking module flags '" + ID->getString() +
1336 "': IDs have conflicting override values");
1339 } else if (SrcBehaviorValue == Module::Override) {
1340 // Update the destination flag to that of the source.
1341 DstOp->replaceOperandWith(0, SrcBehavior);
1342 DstOp->replaceOperandWith(2, SrcOp->getOperand(2));
1346 // Diagnose inconsistent merge behavior types.
1347 if (SrcBehaviorValue != DstBehaviorValue) {
1348 HasErr |= emitError("linking module flags '" + ID->getString() +
1349 "': IDs have conflicting behaviors");
1353 // Perform the merge for standard behavior types.
1354 switch (SrcBehaviorValue) {
1355 case Module::Require:
1356 case Module::Override: llvm_unreachable("not possible");
1357 case Module::Error: {
1358 // Emit an error if the values differ.
1359 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1360 HasErr |= emitError("linking module flags '" + ID->getString() +
1361 "': IDs have conflicting values");
1365 case Module::Warning: {
1366 // Emit a warning if the values differ.
1367 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1368 emitWarning("linking module flags '" + ID->getString() +
1369 "': IDs have conflicting values");
1373 case Module::Append: {
1374 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1375 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1376 unsigned NumOps = DstValue->getNumOperands() + SrcValue->getNumOperands();
1377 Value **VP, **Values = VP = new Value*[NumOps];
1378 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i, ++VP)
1379 *VP = DstValue->getOperand(i);
1380 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i, ++VP)
1381 *VP = SrcValue->getOperand(i);
1382 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1383 ArrayRef<Value*>(Values,
1388 case Module::AppendUnique: {
1389 SmallSetVector<Value*, 16> Elts;
1390 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1391 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1392 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i)
1393 Elts.insert(DstValue->getOperand(i));
1394 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i)
1395 Elts.insert(SrcValue->getOperand(i));
1396 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1397 ArrayRef<Value*>(Elts.begin(),
1404 // Check all of the requirements.
1405 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1406 MDNode *Requirement = Requirements[I];
1407 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1408 Value *ReqValue = Requirement->getOperand(1);
1410 MDNode *Op = Flags[Flag];
1411 if (!Op || Op->getOperand(2) != ReqValue) {
1412 HasErr |= emitError("linking module flags '" + Flag->getString() +
1413 "': does not have the required value");
1421 bool ModuleLinker::run() {
1422 assert(DstM && "Null destination module");
1423 assert(SrcM && "Null source module");
1425 // Inherit the target data from the source module if the destination module
1426 // doesn't have one already.
1427 if (!DstM->getDataLayout() && SrcM->getDataLayout())
1428 DstM->setDataLayout(SrcM->getDataLayout());
1430 // Copy the target triple from the source to dest if the dest's is empty.
1431 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
1432 DstM->setTargetTriple(SrcM->getTargetTriple());
1434 if (SrcM->getDataLayout() && DstM->getDataLayout() &&
1435 *SrcM->getDataLayout() != *DstM->getDataLayout()) {
1436 emitWarning("Linking two modules of different data layouts: '" +
1437 SrcM->getModuleIdentifier() + "' is '" +
1438 SrcM->getDataLayoutStr() + "' whereas '" +
1439 DstM->getModuleIdentifier() + "' is '" +
1440 DstM->getDataLayoutStr() + "'\n");
1442 if (!SrcM->getTargetTriple().empty() &&
1443 DstM->getTargetTriple() != SrcM->getTargetTriple()) {
1444 emitWarning("Linking two modules of different target triples: " +
1445 SrcM->getModuleIdentifier() + "' is '" +
1446 SrcM->getTargetTriple() + "' whereas '" +
1447 DstM->getModuleIdentifier() + "' is '" +
1448 DstM->getTargetTriple() + "'\n");
1451 // Append the module inline asm string.
1452 if (!SrcM->getModuleInlineAsm().empty()) {
1453 if (DstM->getModuleInlineAsm().empty())
1454 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
1456 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
1457 SrcM->getModuleInlineAsm());
1460 // Loop over all of the linked values to compute type mappings.
1461 computeTypeMapping();
1463 ComdatsChosen.clear();
1464 for (const auto &SMEC : SrcM->getComdatSymbolTable()) {
1465 const Comdat &C = SMEC.getValue();
1466 if (ComdatsChosen.count(&C))
1468 Comdat::SelectionKind SK;
1470 if (getComdatResult(&C, SK, LinkFromSrc))
1472 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1475 // Upgrade mismatched global arrays.
1476 upgradeMismatchedGlobals();
1478 // Insert all of the globals in src into the DstM module... without linking
1479 // initializers (which could refer to functions not yet mapped over).
1480 for (Module::global_iterator I = SrcM->global_begin(),
1481 E = SrcM->global_end(); I != E; ++I)
1482 if (linkGlobalValueProto(I))
1485 // Link the functions together between the two modules, without doing function
1486 // bodies... this just adds external function prototypes to the DstM
1487 // function... We do this so that when we begin processing function bodies,
1488 // all of the global values that may be referenced are available in our
1490 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I)
1491 if (linkGlobalValueProto(I))
1494 // If there were any aliases, link them now.
1495 for (Module::alias_iterator I = SrcM->alias_begin(),
1496 E = SrcM->alias_end(); I != E; ++I)
1497 if (linkGlobalValueProto(I))
1500 for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i)
1501 linkAppendingVarInit(AppendingVars[i]);
1503 // Link in the function bodies that are defined in the source module into
1505 for (Module::iterator SF = SrcM->begin(), E = SrcM->end(); SF != E; ++SF) {
1506 // Skip if not linking from source.
1507 if (DoNotLinkFromSource.count(SF)) continue;
1509 Function *DF = cast<Function>(ValueMap[SF]);
1510 if (SF->hasPrefixData()) {
1511 // Link in the prefix data.
1512 DF->setPrefixData(MapValue(
1513 SF->getPrefixData(), ValueMap, RF_None, &TypeMap, &ValMaterializer));
1516 // Materialize if needed.
1517 if (std::error_code EC = SF->materialize())
1518 return emitError(EC.message());
1520 // Skip if no body (function is external).
1521 if (SF->isDeclaration())
1524 linkFunctionBody(DF, SF);
1525 SF->Dematerialize();
1528 // Resolve all uses of aliases with aliasees.
1531 // Remap all of the named MDNodes in Src into the DstM module. We do this
1532 // after linking GlobalValues so that MDNodes that reference GlobalValues
1533 // are properly remapped.
1536 // Merge the module flags into the DstM module.
1537 if (linkModuleFlagsMetadata())
1540 // Update the initializers in the DstM module now that all globals that may
1541 // be referenced are in DstM.
1544 // Process vector of lazily linked in functions.
1545 bool LinkedInAnyFunctions;
1547 LinkedInAnyFunctions = false;
1549 for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(),
1550 E = LazilyLinkFunctions.end(); I != E; ++I) {
1555 Function *DF = cast<Function>(ValueMap[SF]);
1556 if (SF->hasPrefixData()) {
1557 // Link in the prefix data.
1558 DF->setPrefixData(MapValue(SF->getPrefixData(),
1565 // Materialize if needed.
1566 if (std::error_code EC = SF->materialize())
1567 return emitError(EC.message());
1569 // Skip if no body (function is external).
1570 if (SF->isDeclaration())
1573 // Erase from vector *before* the function body is linked - linkFunctionBody could
1575 LazilyLinkFunctions.erase(I);
1577 // Link in function body.
1578 linkFunctionBody(DF, SF);
1579 SF->Dematerialize();
1581 // Set flag to indicate we may have more functions to lazily link in
1582 // since we linked in a function.
1583 LinkedInAnyFunctions = true;
1586 } while (LinkedInAnyFunctions);
1588 // Now that all of the types from the source are used, resolve any structs
1589 // copied over to the dest that didn't exist there.
1590 TypeMap.linkDefinedTypeBodies();
1595 void Linker::init(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
1596 this->Composite = M;
1597 this->DiagnosticHandler = DiagnosticHandler;
1599 TypeFinder StructTypes;
1600 StructTypes.run(*M, true);
1601 IdentifiedStructTypes.insert(StructTypes.begin(), StructTypes.end());
1604 Linker::Linker(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
1605 init(M, DiagnosticHandler);
1608 Linker::Linker(Module *M) {
1609 init(M, [this](const DiagnosticInfo &DI) {
1610 Composite->getContext().diagnose(DI);
1617 void Linker::deleteModule() {
1619 Composite = nullptr;
1622 bool Linker::linkInModule(Module *Src) {
1623 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,
1625 return TheLinker.run();
1628 //===----------------------------------------------------------------------===//
1629 // LinkModules entrypoint.
1630 //===----------------------------------------------------------------------===//
1632 /// This function links two modules together, with the resulting Dest module
1633 /// modified to be the composite of the two input modules. If an error occurs,
1634 /// true is returned and ErrorMsg (if not null) is set to indicate the problem.
1635 /// Upon failure, the Dest module could be in a modified state, and shouldn't be
1636 /// relied on to be consistent.
1637 bool Linker::LinkModules(Module *Dest, Module *Src,
1638 DiagnosticHandlerFunction DiagnosticHandler) {
1639 Linker L(Dest, DiagnosticHandler);
1640 return L.linkInModule(Src);
1643 bool Linker::LinkModules(Module *Dest, Module *Src) {
1645 return L.linkInModule(Src);
1648 //===----------------------------------------------------------------------===//
1650 //===----------------------------------------------------------------------===//
1652 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
1653 LLVMLinkerMode Mode, char **OutMessages) {
1654 Module *D = unwrap(Dest);
1655 std::string Message;
1656 raw_string_ostream Stream(Message);
1657 DiagnosticPrinterRawOStream DP(Stream);
1659 LLVMBool Result = Linker::LinkModules(
1660 D, unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); });
1662 if (OutMessages && Result)
1663 *OutMessages = strdup(Message.c_str());