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/Module.h"
21 #include "llvm/IR/TypeFinder.h"
22 #include "llvm/Support/CommandLine.h"
23 #include "llvm/Support/Debug.h"
24 #include "llvm/Support/raw_ostream.h"
25 #include "llvm/Transforms/Utils/Cloning.h"
31 //===----------------------------------------------------------------------===//
32 // TypeMap implementation.
33 //===----------------------------------------------------------------------===//
36 typedef SmallPtrSet<StructType*, 32> TypeSet;
38 class TypeMapTy : public ValueMapTypeRemapper {
39 /// MappedTypes - This is a mapping from a source type to a destination type
41 DenseMap<Type*, Type*> MappedTypes;
43 /// SpeculativeTypes - When checking to see if two subgraphs are isomorphic,
44 /// we speculatively add types to MappedTypes, but keep track of them here in
45 /// case we need to roll back.
46 SmallVector<Type*, 16> SpeculativeTypes;
48 /// SrcDefinitionsToResolve - This is a list of non-opaque structs in the
49 /// source module that are mapped to an opaque struct in the destination
51 SmallVector<StructType*, 16> SrcDefinitionsToResolve;
53 /// DstResolvedOpaqueTypes - This is the set of opaque types in the
54 /// destination modules who are getting a body from the source module.
55 SmallPtrSet<StructType*, 16> DstResolvedOpaqueTypes;
58 TypeMapTy(TypeSet &Set) : DstStructTypesSet(Set) {}
60 TypeSet &DstStructTypesSet;
61 /// addTypeMapping - Indicate that the specified type in the destination
62 /// module is conceptually equivalent to the specified type in the source
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 /// get - 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 - 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: ";
89 Type *getImpl(Type *T);
90 /// remapType - 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 /// areTypesIsomorphic - Recursively walk this pair of types, returning true
120 /// if they are isomorphic, 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)))
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 /// linkDefinedTypeBodies - Produce a body for an opaque type in the dest
205 /// module from a type definition 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 /// get - Return the mapped type to use for the specified input type from the
247 Type *TypeMapTy::get(Type *Ty) {
248 Type *Result = getImpl(Ty);
250 // If this caused a reference to any struct type, resolve it before returning.
251 if (!SrcDefinitionsToResolve.empty())
252 linkDefinedTypeBodies();
256 /// getImpl - This is the recursive version of get().
257 Type *TypeMapTy::getImpl(Type *Ty) {
258 // If we already have an entry for this type, return it.
259 Type **Entry = &MappedTypes[Ty];
260 if (*Entry) return *Entry;
262 // If this is not a named struct type, then just map all of the elements and
263 // then rebuild the type from inside out.
264 if (!isa<StructType>(Ty) || cast<StructType>(Ty)->isLiteral()) {
265 // If there are no element types to map, then the type is itself. This is
266 // true for the anonymous {} struct, things like 'float', integers, etc.
267 if (Ty->getNumContainedTypes() == 0)
270 // Remap all of the elements, keeping track of whether any of them change.
271 bool AnyChange = false;
272 SmallVector<Type*, 4> ElementTypes;
273 ElementTypes.resize(Ty->getNumContainedTypes());
274 for (unsigned i = 0, e = Ty->getNumContainedTypes(); i != e; ++i) {
275 ElementTypes[i] = getImpl(Ty->getContainedType(i));
276 AnyChange |= ElementTypes[i] != Ty->getContainedType(i);
279 // If we found our type while recursively processing stuff, just use it.
280 Entry = &MappedTypes[Ty];
281 if (*Entry) return *Entry;
283 // If all of the element types mapped directly over, then the type is usable
288 // Otherwise, rebuild a modified type.
289 switch (Ty->getTypeID()) {
290 default: llvm_unreachable("unknown derived type to remap");
291 case Type::ArrayTyID:
292 return *Entry = ArrayType::get(ElementTypes[0],
293 cast<ArrayType>(Ty)->getNumElements());
294 case Type::VectorTyID:
295 return *Entry = VectorType::get(ElementTypes[0],
296 cast<VectorType>(Ty)->getNumElements());
297 case Type::PointerTyID:
298 return *Entry = PointerType::get(ElementTypes[0],
299 cast<PointerType>(Ty)->getAddressSpace());
300 case Type::FunctionTyID:
301 return *Entry = FunctionType::get(ElementTypes[0],
302 makeArrayRef(ElementTypes).slice(1),
303 cast<FunctionType>(Ty)->isVarArg());
304 case Type::StructTyID:
305 // Note that this is only reached for anonymous structs.
306 return *Entry = StructType::get(Ty->getContext(), ElementTypes,
307 cast<StructType>(Ty)->isPacked());
311 // Otherwise, this is an unmapped named struct. If the struct can be directly
312 // mapped over, just use it as-is. This happens in a case when the linked-in
313 // module has something like:
314 // %T = type {%T*, i32}
315 // @GV = global %T* null
316 // where T does not exist at all in the destination module.
318 // The other case we watch for is when the type is not in the destination
319 // module, but that it has to be rebuilt because it refers to something that
320 // is already mapped. For example, if the destination module has:
322 // and the source module has something like
323 // %A' = type { i32 }
324 // %B = type { %A'* }
325 // @GV = global %B* null
326 // then we want to create a new type: "%B = type { %A*}" and have it take the
327 // pristine "%B" name from the source module.
329 // To determine which case this is, we have to recursively walk the type graph
330 // speculating that we'll be able to reuse it unmodified. Only if this is
331 // safe would we map the entire thing over. Because this is an optimization,
332 // and is not required for the prettiness of the linked module, we just skip
333 // it and always rebuild a type here.
334 StructType *STy = cast<StructType>(Ty);
336 // If the type is opaque, we can just use it directly.
337 if (STy->isOpaque()) {
338 // A named structure type from src module is used. Add it to the Set of
339 // identified structs in the destination module.
340 DstStructTypesSet.insert(STy);
344 // Otherwise we create a new type and resolve its body later. This will be
345 // resolved by the top level of get().
346 SrcDefinitionsToResolve.push_back(STy);
347 StructType *DTy = StructType::create(STy->getContext());
348 // A new identified structure type was created. Add it to the set of
349 // identified structs in the destination module.
350 DstStructTypesSet.insert(DTy);
351 DstResolvedOpaqueTypes.insert(DTy);
355 //===----------------------------------------------------------------------===//
356 // ModuleLinker implementation.
357 //===----------------------------------------------------------------------===//
362 /// ValueMaterializerTy - Creates prototypes for functions that are lazily
363 /// linked on the fly. This speeds up linking for modules with many
364 /// lazily linked functions of which few get used.
365 class ValueMaterializerTy : public ValueMaterializer {
368 std::vector<Function*> &LazilyLinkFunctions;
370 ValueMaterializerTy(TypeMapTy &TypeMap, Module *DstM,
371 std::vector<Function*> &LazilyLinkFunctions) :
372 ValueMaterializer(), TypeMap(TypeMap), DstM(DstM),
373 LazilyLinkFunctions(LazilyLinkFunctions) {
376 Value *materializeValueFor(Value *V) override;
379 /// ModuleLinker - This is an implementation class for the LinkModules
380 /// function, which is the entrypoint for this file.
385 ValueMaterializerTy ValMaterializer;
387 /// ValueMap - Mapping of values from what they used to be in Src, to what
388 /// they are now in DstM. ValueToValueMapTy is a ValueMap, which involves
389 /// some overhead due to the use of Value handles which the Linker doesn't
390 /// actually need, but this allows us to reuse the ValueMapper code.
391 ValueToValueMapTy ValueMap;
393 struct AppendingVarInfo {
394 GlobalVariable *NewGV; // New aggregate global in dest module.
395 Constant *DstInit; // Old initializer from dest module.
396 Constant *SrcInit; // Old initializer from src module.
399 std::vector<AppendingVarInfo> AppendingVars;
401 unsigned Mode; // Mode to treat source module.
403 // Set of items not to link in from source.
404 SmallPtrSet<const Value*, 16> DoNotLinkFromSource;
406 // Vector of functions to lazily link in.
407 std::vector<Function*> LazilyLinkFunctions;
409 bool SuppressWarnings;
412 std::string ErrorMsg;
414 ModuleLinker(Module *dstM, TypeSet &Set, Module *srcM, unsigned mode,
415 bool SuppressWarnings=false)
416 : DstM(dstM), SrcM(srcM), TypeMap(Set),
417 ValMaterializer(TypeMap, DstM, LazilyLinkFunctions), Mode(mode),
418 SuppressWarnings(SuppressWarnings) {}
423 /// emitError - Helper method for setting a message and returning an error
425 bool emitError(const Twine &Message) {
426 ErrorMsg = Message.str();
430 bool getComdatLeader(Module *M, StringRef ComdatName,
431 const GlobalVariable *&GVar);
432 bool computeResultingSelectionKind(StringRef ComdatName,
433 Comdat::SelectionKind Src,
434 Comdat::SelectionKind Dst,
435 Comdat::SelectionKind &Result,
437 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
439 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
442 /// getLinkageResult - This analyzes the two global values and determines
443 /// what the result will look like in the destination module.
444 bool getLinkageResult(GlobalValue *Dest, const GlobalValue *Src,
445 GlobalValue::LinkageTypes <,
446 GlobalValue::VisibilityTypes &Vis,
449 /// getLinkedToGlobal - Given a global in the source module, return the
450 /// global in the destination module that is being linked to, if any.
451 GlobalValue *getLinkedToGlobal(GlobalValue *SrcGV) {
452 // If the source has no name it can't link. If it has local linkage,
453 // there is no name match-up going on.
454 if (!SrcGV->hasName() || SrcGV->hasLocalLinkage())
457 // Otherwise see if we have a match in the destination module's symtab.
458 GlobalValue *DGV = DstM->getNamedValue(SrcGV->getName());
459 if (!DGV) return nullptr;
461 // If we found a global with the same name in the dest module, but it has
462 // internal linkage, we are really not doing any linkage here.
463 if (DGV->hasLocalLinkage())
466 // Otherwise, we do in fact link to the destination global.
470 void computeTypeMapping();
472 bool linkAppendingVarProto(GlobalVariable *DstGV, GlobalVariable *SrcGV);
473 bool linkGlobalProto(GlobalVariable *SrcGV);
474 bool linkFunctionProto(Function *SrcF);
475 bool linkAliasProto(GlobalAlias *SrcA);
476 bool linkModuleFlagsMetadata();
478 void linkAppendingVarInit(const AppendingVarInfo &AVI);
479 void linkGlobalInits();
480 void linkFunctionBody(Function *Dst, Function *Src);
481 void linkAliasBodies();
482 void linkNamedMDNodes();
486 /// forceRenaming - The LLVM SymbolTable class autorenames globals that conflict
487 /// in the symbol table. This is good for all clients except for us. Go
488 /// through the trouble to force this back.
489 static void forceRenaming(GlobalValue *GV, StringRef Name) {
490 // If the global doesn't force its name or if it already has the right name,
491 // there is nothing for us to do.
492 if (GV->hasLocalLinkage() || GV->getName() == Name)
495 Module *M = GV->getParent();
497 // If there is a conflict, rename the conflict.
498 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
499 GV->takeName(ConflictGV);
500 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
501 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
503 GV->setName(Name); // Force the name back
507 /// copyGVAttributes - copy additional attributes (those not needed to construct
508 /// a GlobalValue) from the SrcGV to the DestGV.
509 static void copyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) {
510 // Use the maximum alignment, rather than just copying the alignment of SrcGV.
511 auto *DestGO = dyn_cast<GlobalObject>(DestGV);
514 Alignment = std::max(DestGO->getAlignment(), SrcGV->getAlignment());
516 DestGV->copyAttributesFrom(SrcGV);
519 DestGO->setAlignment(Alignment);
521 forceRenaming(DestGV, SrcGV->getName());
524 static bool isLessConstraining(GlobalValue::VisibilityTypes a,
525 GlobalValue::VisibilityTypes b) {
526 if (a == GlobalValue::HiddenVisibility)
528 if (b == GlobalValue::HiddenVisibility)
530 if (a == GlobalValue::ProtectedVisibility)
532 if (b == GlobalValue::ProtectedVisibility)
537 Value *ValueMaterializerTy::materializeValueFor(Value *V) {
538 Function *SF = dyn_cast<Function>(V);
542 Function *DF = Function::Create(TypeMap.get(SF->getFunctionType()),
543 SF->getLinkage(), SF->getName(), DstM);
544 copyGVAttributes(DF, SF);
546 LazilyLinkFunctions.push_back(SF);
550 bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName,
551 const GlobalVariable *&GVar) {
552 const GlobalValue *GVal = M->getNamedValue(ComdatName);
553 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
554 GVal = GA->getBaseObject();
556 // We cannot resolve the size of the aliasee yet.
557 return emitError("Linking COMDATs named '" + ComdatName +
558 "': COMDAT key involves incomputable alias size.");
561 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
564 "Linking COMDATs named '" + ComdatName +
565 "': GlobalVariable required for data dependent selection!");
570 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
571 Comdat::SelectionKind Src,
572 Comdat::SelectionKind Dst,
573 Comdat::SelectionKind &Result,
575 // The ability to mix Comdat::SelectionKind::Any with
576 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
577 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
578 Dst == Comdat::SelectionKind::Largest;
579 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
580 Src == Comdat::SelectionKind::Largest;
581 if (DstAnyOrLargest && SrcAnyOrLargest) {
582 if (Dst == Comdat::SelectionKind::Largest ||
583 Src == Comdat::SelectionKind::Largest)
584 Result = Comdat::SelectionKind::Largest;
586 Result = Comdat::SelectionKind::Any;
587 } else if (Src == Dst) {
590 return emitError("Linking COMDATs named '" + ComdatName +
591 "': invalid selection kinds!");
595 case Comdat::SelectionKind::Any:
599 case Comdat::SelectionKind::NoDuplicates:
600 return emitError("Linking COMDATs named '" + ComdatName +
601 "': noduplicates has been violated!");
602 case Comdat::SelectionKind::ExactMatch:
603 case Comdat::SelectionKind::Largest:
604 case Comdat::SelectionKind::SameSize: {
605 const GlobalVariable *DstGV;
606 const GlobalVariable *SrcGV;
607 if (getComdatLeader(DstM, ComdatName, DstGV) ||
608 getComdatLeader(SrcM, ComdatName, SrcGV))
611 const DataLayout *DstDL = DstM->getDataLayout();
612 const DataLayout *SrcDL = SrcM->getDataLayout();
613 if (!DstDL || !SrcDL) {
615 "Linking COMDATs named '" + ComdatName +
616 "': can't do size dependent selection without DataLayout!");
619 DstDL->getTypeAllocSize(DstGV->getType()->getPointerElementType());
621 SrcDL->getTypeAllocSize(SrcGV->getType()->getPointerElementType());
622 if (Result == Comdat::SelectionKind::ExactMatch) {
623 if (SrcGV->getInitializer() != DstGV->getInitializer())
624 return emitError("Linking COMDATs named '" + ComdatName +
625 "': ExactMatch violated!");
627 } else if (Result == Comdat::SelectionKind::Largest) {
628 LinkFromSrc = SrcSize > DstSize;
629 } else if (Result == Comdat::SelectionKind::SameSize) {
630 if (SrcSize != DstSize)
631 return emitError("Linking COMDATs named '" + ComdatName +
632 "': SameSize violated!");
635 llvm_unreachable("unknown selection kind");
644 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
645 Comdat::SelectionKind &Result,
647 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
648 StringRef ComdatName = SrcC->getName();
649 Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable();
650 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
652 if (DstCI == ComdatSymTab.end()) {
653 // Use the comdat if it is only available in one of the modules.
659 const Comdat *DstC = &DstCI->second;
660 Comdat::SelectionKind DSK = DstC->getSelectionKind();
661 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
665 /// getLinkageResult - This analyzes the two global values and determines what
666 /// the result will look like in the destination module. In particular, it
667 /// computes the resultant linkage type and visibility, computes whether the
668 /// global in the source should be copied over to the destination (replacing
669 /// the existing one), and computes whether this linkage is an error or not.
670 bool ModuleLinker::getLinkageResult(GlobalValue *Dest, const GlobalValue *Src,
671 GlobalValue::LinkageTypes <,
672 GlobalValue::VisibilityTypes &Vis,
674 assert(Dest && "Must have two globals being queried");
675 assert(!Src->hasLocalLinkage() &&
676 "If Src has internal linkage, Dest shouldn't be set!");
678 bool SrcIsDeclaration = Src->isDeclaration() && !Src->isMaterializable();
679 bool DestIsDeclaration = Dest->isDeclaration();
681 if (SrcIsDeclaration) {
682 // If Src is external or if both Src & Dest are external.. Just link the
683 // external globals, we aren't adding anything.
684 if (Src->hasDLLImportStorageClass()) {
685 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
686 if (DestIsDeclaration) {
688 LT = Src->getLinkage();
690 } else if (Dest->hasExternalWeakLinkage()) {
691 // If the Dest is weak, use the source linkage.
693 LT = Src->getLinkage();
696 LT = Dest->getLinkage();
698 } else if (DestIsDeclaration && !Dest->hasDLLImportStorageClass()) {
699 // If Dest is external but Src is not:
701 LT = Src->getLinkage();
702 } else if (Src->isWeakForLinker()) {
703 // At this point we know that Dest has LinkOnce, External*, Weak, Common,
705 if (Dest->hasExternalWeakLinkage() ||
706 Dest->hasAvailableExternallyLinkage() ||
707 (Dest->hasLinkOnceLinkage() &&
708 (Src->hasWeakLinkage() || Src->hasCommonLinkage()))) {
710 LT = Src->getLinkage();
713 LT = Dest->getLinkage();
715 } else if (Dest->isWeakForLinker()) {
716 // At this point we know that Src has External* or DLL* linkage.
717 if (Src->hasExternalWeakLinkage()) {
719 LT = Dest->getLinkage();
722 LT = GlobalValue::ExternalLinkage;
725 assert((Dest->hasExternalLinkage() || Dest->hasExternalWeakLinkage()) &&
726 (Src->hasExternalLinkage() || Src->hasExternalWeakLinkage()) &&
727 "Unexpected linkage type!");
728 return emitError("Linking globals named '" + Src->getName() +
729 "': symbol multiply defined!");
732 // Compute the visibility. We follow the rules in the System V Application
734 assert(!GlobalValue::isLocalLinkage(LT) &&
735 "Symbols with local linkage should not be merged");
736 Vis = isLessConstraining(Src->getVisibility(), Dest->getVisibility()) ?
737 Dest->getVisibility() : Src->getVisibility();
741 /// computeTypeMapping - Loop over all of the linked values to compute type
742 /// mappings. For example, if we link "extern Foo *x" and "Foo *x = NULL", then
743 /// we have two struct types 'Foo' but one got renamed when the module was
744 /// loaded into the same LLVMContext.
745 void ModuleLinker::computeTypeMapping() {
746 // Incorporate globals.
747 for (Module::global_iterator I = SrcM->global_begin(),
748 E = SrcM->global_end(); I != E; ++I) {
749 GlobalValue *DGV = getLinkedToGlobal(I);
752 if (!DGV->hasAppendingLinkage() || !I->hasAppendingLinkage()) {
753 TypeMap.addTypeMapping(DGV->getType(), I->getType());
757 // Unify the element type of appending arrays.
758 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
759 ArrayType *SAT = cast<ArrayType>(I->getType()->getElementType());
760 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
763 // Incorporate functions.
764 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I) {
765 if (GlobalValue *DGV = getLinkedToGlobal(I))
766 TypeMap.addTypeMapping(DGV->getType(), I->getType());
769 // Incorporate types by name, scanning all the types in the source module.
770 // At this point, the destination module may have a type "%foo = { i32 }" for
771 // example. When the source module got loaded into the same LLVMContext, if
772 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
773 TypeFinder SrcStructTypes;
774 SrcStructTypes.run(*SrcM, true);
775 SmallPtrSet<StructType*, 32> SrcStructTypesSet(SrcStructTypes.begin(),
776 SrcStructTypes.end());
778 for (unsigned i = 0, e = SrcStructTypes.size(); i != e; ++i) {
779 StructType *ST = SrcStructTypes[i];
780 if (!ST->hasName()) continue;
782 // Check to see if there is a dot in the name followed by a digit.
783 size_t DotPos = ST->getName().rfind('.');
784 if (DotPos == 0 || DotPos == StringRef::npos ||
785 ST->getName().back() == '.' ||
786 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos+1])))
789 // Check to see if the destination module has a struct with the prefix name.
790 if (StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos)))
791 // Don't use it if this actually came from the source module. They're in
792 // the same LLVMContext after all. Also don't use it unless the type is
793 // actually used in the destination module. This can happen in situations
798 // %Z = type { %A } %B = type { %C.1 }
799 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
800 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
801 // %C = type { i8* } %B.3 = type { %C.1 }
803 // When we link Module B with Module A, the '%B' in Module B is
804 // used. However, that would then use '%C.1'. But when we process '%C.1',
805 // we prefer to take the '%C' version. So we are then left with both
806 // '%C.1' and '%C' being used for the same types. This leads to some
807 // variables using one type and some using the other.
808 if (!SrcStructTypesSet.count(DST) && TypeMap.DstStructTypesSet.count(DST))
809 TypeMap.addTypeMapping(DST, ST);
812 // Don't bother incorporating aliases, they aren't generally typed well.
814 // Now that we have discovered all of the type equivalences, get a body for
815 // any 'opaque' types in the dest module that are now resolved.
816 TypeMap.linkDefinedTypeBodies();
819 /// linkAppendingVarProto - If there were any appending global variables, link
820 /// them together now. Return true on error.
821 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
822 GlobalVariable *SrcGV) {
824 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
825 return emitError("Linking globals named '" + SrcGV->getName() +
826 "': can only link appending global with another appending global!");
828 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
830 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
831 Type *EltTy = DstTy->getElementType();
833 // Check to see that they two arrays agree on type.
834 if (EltTy != SrcTy->getElementType())
835 return emitError("Appending variables with different element types!");
836 if (DstGV->isConstant() != SrcGV->isConstant())
837 return emitError("Appending variables linked with different const'ness!");
839 if (DstGV->getAlignment() != SrcGV->getAlignment())
841 "Appending variables with different alignment need to be linked!");
843 if (DstGV->getVisibility() != SrcGV->getVisibility())
845 "Appending variables with different visibility need to be linked!");
847 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
849 "Appending variables with different unnamed_addr need to be linked!");
851 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
853 "Appending variables with different section name need to be linked!");
855 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements();
856 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
858 // Create the new global variable.
860 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(),
861 DstGV->getLinkage(), /*init*/nullptr, /*name*/"", DstGV,
862 DstGV->getThreadLocalMode(),
863 DstGV->getType()->getAddressSpace());
865 // Propagate alignment, visibility and section info.
866 copyGVAttributes(NG, DstGV);
868 AppendingVarInfo AVI;
870 AVI.DstInit = DstGV->getInitializer();
871 AVI.SrcInit = SrcGV->getInitializer();
872 AppendingVars.push_back(AVI);
874 // Replace any uses of the two global variables with uses of the new
876 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
878 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
879 DstGV->eraseFromParent();
881 // Track the source variable so we don't try to link it.
882 DoNotLinkFromSource.insert(SrcGV);
887 /// linkGlobalProto - Loop through the global variables in the src module and
888 /// merge them into the dest module.
889 bool ModuleLinker::linkGlobalProto(GlobalVariable *SGV) {
890 GlobalValue *DGV = getLinkedToGlobal(SGV);
891 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
892 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
894 bool LinkFromSrc = false;
895 Comdat *DC = nullptr;
896 if (const Comdat *SC = SGV->getComdat()) {
897 Comdat::SelectionKind SK;
898 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
899 DC = DstM->getOrInsertComdat(SC->getName());
900 DC->setSelectionKind(SK);
905 // Concatenation of appending linkage variables is magic and handled later.
906 if (DGV->hasAppendingLinkage() || SGV->hasAppendingLinkage())
907 return linkAppendingVarProto(cast<GlobalVariable>(DGV), SGV);
909 // Determine whether linkage of these two globals follows the source
910 // module's definition or the destination module's definition.
911 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
912 GlobalValue::VisibilityTypes NV;
913 if (getLinkageResult(DGV, SGV, NewLinkage, NV, LinkFromSrc))
916 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
918 // If we're not linking from the source, then keep the definition that we
921 // Special case for const propagation.
922 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV))
923 if (DGVar->isDeclaration() && SGV->isConstant() &&
924 !DGVar->isConstant())
925 DGVar->setConstant(true);
927 // Set calculated linkage, visibility and unnamed_addr.
928 DGV->setLinkage(NewLinkage);
929 DGV->setVisibility(*NewVisibility);
930 DGV->setUnnamedAddr(HasUnnamedAddr);
935 // Make sure to remember this mapping.
936 ValueMap[SGV] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGV->getType()));
938 // Track the source global so that we don't attempt to copy it over when
939 // processing global initializers.
940 DoNotLinkFromSource.insert(SGV);
946 // If the Comdat this variable was inside of wasn't selected, skip it.
947 if (DC && !DGV && !LinkFromSrc) {
948 DoNotLinkFromSource.insert(SGV);
952 // No linking to be performed or linking from the source: simply create an
953 // identical version of the symbol over in the dest module... the
954 // initializer will be filled in later by LinkGlobalInits.
955 GlobalVariable *NewDGV =
956 new GlobalVariable(*DstM, TypeMap.get(SGV->getType()->getElementType()),
957 SGV->isConstant(), SGV->getLinkage(), /*init*/nullptr,
958 SGV->getName(), /*insertbefore*/nullptr,
959 SGV->getThreadLocalMode(),
960 SGV->getType()->getAddressSpace());
961 // Propagate alignment, visibility and section info.
962 copyGVAttributes(NewDGV, SGV);
964 NewDGV->setVisibility(*NewVisibility);
965 NewDGV->setUnnamedAddr(HasUnnamedAddr);
968 NewDGV->setComdat(DC);
971 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV, DGV->getType()));
972 DGV->eraseFromParent();
975 // Make sure to remember this mapping.
976 ValueMap[SGV] = NewDGV;
980 /// linkFunctionProto - Link the function in the source module into the
981 /// destination module if needed, setting up mapping information.
982 bool ModuleLinker::linkFunctionProto(Function *SF) {
983 GlobalValue *DGV = getLinkedToGlobal(SF);
984 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
985 bool HasUnnamedAddr = SF->hasUnnamedAddr();
987 bool LinkFromSrc = false;
988 Comdat *DC = nullptr;
989 if (const Comdat *SC = SF->getComdat()) {
990 Comdat::SelectionKind SK;
991 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
992 DC = DstM->getOrInsertComdat(SC->getName());
993 DC->setSelectionKind(SK);
998 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
999 GlobalValue::VisibilityTypes NV;
1000 if (getLinkageResult(DGV, SF, NewLinkage, NV, LinkFromSrc))
1003 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1006 // Set calculated linkage
1007 DGV->setLinkage(NewLinkage);
1008 DGV->setVisibility(*NewVisibility);
1009 DGV->setUnnamedAddr(HasUnnamedAddr);
1014 // Make sure to remember this mapping.
1015 ValueMap[SF] = ConstantExpr::getBitCast(DGV, TypeMap.get(SF->getType()));
1017 // Track the function from the source module so we don't attempt to remap
1019 DoNotLinkFromSource.insert(SF);
1025 // If the function is to be lazily linked, don't create it just yet.
1026 // The ValueMaterializerTy will deal with creating it if it's used.
1027 if (!DGV && (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() ||
1028 SF->hasAvailableExternallyLinkage())) {
1029 DoNotLinkFromSource.insert(SF);
1033 // If the Comdat this function was inside of wasn't selected, skip it.
1034 if (DC && !DGV && !LinkFromSrc) {
1035 DoNotLinkFromSource.insert(SF);
1039 // If there is no linkage to be performed or we are linking from the source,
1041 Function *NewDF = Function::Create(TypeMap.get(SF->getFunctionType()),
1042 SF->getLinkage(), SF->getName(), DstM);
1043 copyGVAttributes(NewDF, SF);
1045 NewDF->setVisibility(*NewVisibility);
1046 NewDF->setUnnamedAddr(HasUnnamedAddr);
1049 NewDF->setComdat(DC);
1052 // Any uses of DF need to change to NewDF, with cast.
1053 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, DGV->getType()));
1054 DGV->eraseFromParent();
1057 ValueMap[SF] = NewDF;
1061 /// LinkAliasProto - Set up prototypes for any aliases that come over from the
1063 bool ModuleLinker::linkAliasProto(GlobalAlias *SGA) {
1064 GlobalValue *DGV = getLinkedToGlobal(SGA);
1065 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
1066 bool HasUnnamedAddr = SGA->hasUnnamedAddr();
1068 bool LinkFromSrc = false;
1069 Comdat *DC = nullptr;
1070 if (const Comdat *SC = SGA->getComdat()) {
1071 Comdat::SelectionKind SK;
1072 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1073 DC = DstM->getOrInsertComdat(SC->getName());
1074 DC->setSelectionKind(SK);
1079 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
1080 GlobalValue::VisibilityTypes NV;
1081 if (getLinkageResult(DGV, SGA, NewLinkage, NV, LinkFromSrc))
1084 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1087 // Set calculated linkage.
1088 DGV->setLinkage(NewLinkage);
1089 DGV->setVisibility(*NewVisibility);
1090 DGV->setUnnamedAddr(HasUnnamedAddr);
1095 // Make sure to remember this mapping.
1096 ValueMap[SGA] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGA->getType()));
1098 // Track the alias from the source module so we don't attempt to remap it.
1099 DoNotLinkFromSource.insert(SGA);
1105 // If the Comdat this alias was inside of wasn't selected, skip it.
1106 if (DC && !DGV && !LinkFromSrc) {
1107 DoNotLinkFromSource.insert(SGA);
1111 // If there is no linkage to be performed or we're linking from the source,
1113 auto *PTy = cast<PointerType>(TypeMap.get(SGA->getType()));
1115 GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(),
1116 SGA->getLinkage(), SGA->getName(), DstM);
1117 copyGVAttributes(NewDA, SGA);
1119 NewDA->setVisibility(*NewVisibility);
1120 NewDA->setUnnamedAddr(HasUnnamedAddr);
1123 // Any uses of DGV need to change to NewDA, with cast.
1124 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDA, DGV->getType()));
1125 DGV->eraseFromParent();
1128 ValueMap[SGA] = NewDA;
1132 static void getArrayElements(Constant *C, SmallVectorImpl<Constant*> &Dest) {
1133 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1135 for (unsigned i = 0; i != NumElements; ++i)
1136 Dest.push_back(C->getAggregateElement(i));
1139 void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) {
1140 // Merge the initializer.
1141 SmallVector<Constant*, 16> Elements;
1142 getArrayElements(AVI.DstInit, Elements);
1144 Constant *SrcInit = MapValue(AVI.SrcInit, ValueMap, RF_None, &TypeMap, &ValMaterializer);
1145 getArrayElements(SrcInit, Elements);
1147 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
1148 AVI.NewGV->setInitializer(ConstantArray::get(NewType, Elements));
1151 /// linkGlobalInits - Update the initializers in the Dest module now that all
1152 /// globals that may be referenced are in Dest.
1153 void ModuleLinker::linkGlobalInits() {
1154 // Loop over all of the globals in the src module, mapping them over as we go
1155 for (Module::const_global_iterator I = SrcM->global_begin(),
1156 E = SrcM->global_end(); I != E; ++I) {
1158 // Only process initialized GV's or ones not already in dest.
1159 if (!I->hasInitializer() || DoNotLinkFromSource.count(I)) continue;
1161 // Grab destination global variable.
1162 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[I]);
1163 // Figure out what the initializer looks like in the dest module.
1164 DGV->setInitializer(MapValue(I->getInitializer(), ValueMap,
1165 RF_None, &TypeMap, &ValMaterializer));
1169 /// linkFunctionBody - Copy the source function over into the dest function and
1170 /// fix up references to values. At this point we know that Dest is an external
1171 /// function, and that Src is not.
1172 void ModuleLinker::linkFunctionBody(Function *Dst, Function *Src) {
1173 assert(Src && Dst && Dst->isDeclaration() && !Src->isDeclaration());
1175 // Go through and convert function arguments over, remembering the mapping.
1176 Function::arg_iterator DI = Dst->arg_begin();
1177 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1178 I != E; ++I, ++DI) {
1179 DI->setName(I->getName()); // Copy the name over.
1181 // Add a mapping to our mapping.
1185 if (Mode == Linker::DestroySource) {
1186 // Splice the body of the source function into the dest function.
1187 Dst->getBasicBlockList().splice(Dst->end(), Src->getBasicBlockList());
1189 // At this point, all of the instructions and values of the function are now
1190 // copied over. The only problem is that they are still referencing values in
1191 // the Source function as operands. Loop through all of the operands of the
1192 // functions and patch them up to point to the local versions.
1193 for (Function::iterator BB = Dst->begin(), BE = Dst->end(); BB != BE; ++BB)
1194 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
1195 RemapInstruction(I, ValueMap, RF_IgnoreMissingEntries,
1196 &TypeMap, &ValMaterializer);
1199 // Clone the body of the function into the dest function.
1200 SmallVector<ReturnInst*, 8> Returns; // Ignore returns.
1201 CloneFunctionInto(Dst, Src, ValueMap, false, Returns, "", nullptr,
1202 &TypeMap, &ValMaterializer);
1205 // There is no need to map the arguments anymore.
1206 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1212 /// linkAliasBodies - Insert all of the aliases in Src into the Dest module.
1213 void ModuleLinker::linkAliasBodies() {
1214 for (Module::alias_iterator I = SrcM->alias_begin(), E = SrcM->alias_end();
1216 if (DoNotLinkFromSource.count(I))
1218 if (Constant *Aliasee = I->getAliasee()) {
1219 GlobalAlias *DA = cast<GlobalAlias>(ValueMap[I]);
1221 MapValue(Aliasee, ValueMap, RF_None, &TypeMap, &ValMaterializer);
1222 DA->setAliasee(Val);
1227 /// linkNamedMDNodes - Insert all of the named MDNodes in Src into the Dest
1229 void ModuleLinker::linkNamedMDNodes() {
1230 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1231 for (Module::const_named_metadata_iterator I = SrcM->named_metadata_begin(),
1232 E = SrcM->named_metadata_end(); I != E; ++I) {
1233 // Don't link module flags here. Do them separately.
1234 if (&*I == SrcModFlags) continue;
1235 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(I->getName());
1236 // Add Src elements into Dest node.
1237 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
1238 DestNMD->addOperand(MapValue(I->getOperand(i), ValueMap,
1239 RF_None, &TypeMap, &ValMaterializer));
1243 /// linkModuleFlagsMetadata - Merge the linker flags in Src into the Dest
1245 bool ModuleLinker::linkModuleFlagsMetadata() {
1246 // If the source module has no module flags, we are done.
1247 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1248 if (!SrcModFlags) return false;
1250 // If the destination module doesn't have module flags yet, then just copy
1251 // over the source module's flags.
1252 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
1253 if (DstModFlags->getNumOperands() == 0) {
1254 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1255 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1260 // First build a map of the existing module flags and requirements.
1261 DenseMap<MDString*, MDNode*> Flags;
1262 SmallSetVector<MDNode*, 16> Requirements;
1263 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1264 MDNode *Op = DstModFlags->getOperand(I);
1265 ConstantInt *Behavior = cast<ConstantInt>(Op->getOperand(0));
1266 MDString *ID = cast<MDString>(Op->getOperand(1));
1268 if (Behavior->getZExtValue() == Module::Require) {
1269 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1275 // Merge in the flags from the source module, and also collect its set of
1277 bool HasErr = false;
1278 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1279 MDNode *SrcOp = SrcModFlags->getOperand(I);
1280 ConstantInt *SrcBehavior = cast<ConstantInt>(SrcOp->getOperand(0));
1281 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1282 MDNode *DstOp = Flags.lookup(ID);
1283 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1285 // If this is a requirement, add it and continue.
1286 if (SrcBehaviorValue == Module::Require) {
1287 // If the destination module does not already have this requirement, add
1289 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1290 DstModFlags->addOperand(SrcOp);
1295 // If there is no existing flag with this ID, just add it.
1298 DstModFlags->addOperand(SrcOp);
1302 // Otherwise, perform a merge.
1303 ConstantInt *DstBehavior = cast<ConstantInt>(DstOp->getOperand(0));
1304 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1306 // If either flag has override behavior, handle it first.
1307 if (DstBehaviorValue == Module::Override) {
1308 // Diagnose inconsistent flags which both have override behavior.
1309 if (SrcBehaviorValue == Module::Override &&
1310 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1311 HasErr |= emitError("linking module flags '" + ID->getString() +
1312 "': IDs have conflicting override values");
1315 } else if (SrcBehaviorValue == Module::Override) {
1316 // Update the destination flag to that of the source.
1317 DstOp->replaceOperandWith(0, SrcBehavior);
1318 DstOp->replaceOperandWith(2, SrcOp->getOperand(2));
1322 // Diagnose inconsistent merge behavior types.
1323 if (SrcBehaviorValue != DstBehaviorValue) {
1324 HasErr |= emitError("linking module flags '" + ID->getString() +
1325 "': IDs have conflicting behaviors");
1329 // Perform the merge for standard behavior types.
1330 switch (SrcBehaviorValue) {
1331 case Module::Require:
1332 case Module::Override: llvm_unreachable("not possible");
1333 case Module::Error: {
1334 // Emit an error if the values differ.
1335 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1336 HasErr |= emitError("linking module flags '" + ID->getString() +
1337 "': IDs have conflicting values");
1341 case Module::Warning: {
1342 // Emit a warning if the values differ.
1343 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1344 if (!SuppressWarnings) {
1345 errs() << "WARNING: linking module flags '" << ID->getString()
1346 << "': IDs have conflicting values";
1351 case Module::Append: {
1352 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1353 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1354 unsigned NumOps = DstValue->getNumOperands() + SrcValue->getNumOperands();
1355 Value **VP, **Values = VP = new Value*[NumOps];
1356 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i, ++VP)
1357 *VP = DstValue->getOperand(i);
1358 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i, ++VP)
1359 *VP = SrcValue->getOperand(i);
1360 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1361 ArrayRef<Value*>(Values,
1366 case Module::AppendUnique: {
1367 SmallSetVector<Value*, 16> Elts;
1368 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1369 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1370 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i)
1371 Elts.insert(DstValue->getOperand(i));
1372 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i)
1373 Elts.insert(SrcValue->getOperand(i));
1374 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1375 ArrayRef<Value*>(Elts.begin(),
1382 // Check all of the requirements.
1383 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1384 MDNode *Requirement = Requirements[I];
1385 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1386 Value *ReqValue = Requirement->getOperand(1);
1388 MDNode *Op = Flags[Flag];
1389 if (!Op || Op->getOperand(2) != ReqValue) {
1390 HasErr |= emitError("linking module flags '" + Flag->getString() +
1391 "': does not have the required value");
1399 bool ModuleLinker::run() {
1400 assert(DstM && "Null destination module");
1401 assert(SrcM && "Null source module");
1403 // Inherit the target data from the source module if the destination module
1404 // doesn't have one already.
1405 if (!DstM->getDataLayout() && SrcM->getDataLayout())
1406 DstM->setDataLayout(SrcM->getDataLayout());
1408 // Copy the target triple from the source to dest if the dest's is empty.
1409 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
1410 DstM->setTargetTriple(SrcM->getTargetTriple());
1412 if (SrcM->getDataLayout() && DstM->getDataLayout() &&
1413 *SrcM->getDataLayout() != *DstM->getDataLayout()) {
1414 if (!SuppressWarnings) {
1415 errs() << "WARNING: Linking two modules of different data layouts: '"
1416 << SrcM->getModuleIdentifier() << "' is '"
1417 << SrcM->getDataLayoutStr() << "' whereas '"
1418 << DstM->getModuleIdentifier() << "' is '"
1419 << DstM->getDataLayoutStr() << "'\n";
1422 if (!SrcM->getTargetTriple().empty() &&
1423 DstM->getTargetTriple() != SrcM->getTargetTriple()) {
1424 if (!SuppressWarnings) {
1425 errs() << "WARNING: Linking two modules of different target triples: "
1426 << SrcM->getModuleIdentifier() << "' is '"
1427 << SrcM->getTargetTriple() << "' whereas '"
1428 << DstM->getModuleIdentifier() << "' is '"
1429 << DstM->getTargetTriple() << "'\n";
1433 // Append the module inline asm string.
1434 if (!SrcM->getModuleInlineAsm().empty()) {
1435 if (DstM->getModuleInlineAsm().empty())
1436 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
1438 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
1439 SrcM->getModuleInlineAsm());
1442 // Loop over all of the linked values to compute type mappings.
1443 computeTypeMapping();
1445 ComdatsChosen.clear();
1446 for (const StringMapEntry<llvm::Comdat> &SMEC : SrcM->getComdatSymbolTable()) {
1447 const Comdat &C = SMEC.getValue();
1448 if (ComdatsChosen.count(&C))
1450 Comdat::SelectionKind SK;
1452 if (getComdatResult(&C, SK, LinkFromSrc))
1454 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1457 // Insert all of the globals in src into the DstM module... without linking
1458 // initializers (which could refer to functions not yet mapped over).
1459 for (Module::global_iterator I = SrcM->global_begin(),
1460 E = SrcM->global_end(); I != E; ++I)
1461 if (linkGlobalProto(I))
1464 // Link the functions together between the two modules, without doing function
1465 // bodies... this just adds external function prototypes to the DstM
1466 // function... We do this so that when we begin processing function bodies,
1467 // all of the global values that may be referenced are available in our
1469 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I)
1470 if (linkFunctionProto(I))
1473 // If there were any aliases, link them now.
1474 for (Module::alias_iterator I = SrcM->alias_begin(),
1475 E = SrcM->alias_end(); I != E; ++I)
1476 if (linkAliasProto(I))
1479 for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i)
1480 linkAppendingVarInit(AppendingVars[i]);
1482 // Link in the function bodies that are defined in the source module into
1484 for (Module::iterator SF = SrcM->begin(), E = SrcM->end(); SF != E; ++SF) {
1485 // Skip if not linking from source.
1486 if (DoNotLinkFromSource.count(SF)) continue;
1488 Function *DF = cast<Function>(ValueMap[SF]);
1489 if (SF->hasPrefixData()) {
1490 // Link in the prefix data.
1491 DF->setPrefixData(MapValue(
1492 SF->getPrefixData(), ValueMap, RF_None, &TypeMap, &ValMaterializer));
1495 // Skip if no body (function is external) or materialize.
1496 if (SF->isDeclaration()) {
1497 if (!SF->isMaterializable())
1499 if (SF->Materialize(&ErrorMsg))
1503 linkFunctionBody(DF, SF);
1504 SF->Dematerialize();
1507 // Resolve all uses of aliases with aliasees.
1510 // Remap all of the named MDNodes in Src into the DstM module. We do this
1511 // after linking GlobalValues so that MDNodes that reference GlobalValues
1512 // are properly remapped.
1515 // Merge the module flags into the DstM module.
1516 if (linkModuleFlagsMetadata())
1519 // Update the initializers in the DstM module now that all globals that may
1520 // be referenced are in DstM.
1523 // Process vector of lazily linked in functions.
1524 bool LinkedInAnyFunctions;
1526 LinkedInAnyFunctions = false;
1528 for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(),
1529 E = LazilyLinkFunctions.end(); I != E; ++I) {
1534 Function *DF = cast<Function>(ValueMap[SF]);
1535 if (SF->hasPrefixData()) {
1536 // Link in the prefix data.
1537 DF->setPrefixData(MapValue(SF->getPrefixData(),
1544 // Materialize if necessary.
1545 if (SF->isDeclaration()) {
1546 if (!SF->isMaterializable())
1548 if (SF->Materialize(&ErrorMsg))
1552 // Erase from vector *before* the function body is linked - linkFunctionBody could
1554 LazilyLinkFunctions.erase(I);
1556 // Link in function body.
1557 linkFunctionBody(DF, SF);
1558 SF->Dematerialize();
1560 // Set flag to indicate we may have more functions to lazily link in
1561 // since we linked in a function.
1562 LinkedInAnyFunctions = true;
1565 } while (LinkedInAnyFunctions);
1567 // Now that all of the types from the source are used, resolve any structs
1568 // copied over to the dest that didn't exist there.
1569 TypeMap.linkDefinedTypeBodies();
1574 Linker::Linker(Module *M, bool SuppressWarnings)
1575 : Composite(M), SuppressWarnings(SuppressWarnings) {
1576 TypeFinder StructTypes;
1577 StructTypes.run(*M, true);
1578 IdentifiedStructTypes.insert(StructTypes.begin(), StructTypes.end());
1584 void Linker::deleteModule() {
1586 Composite = nullptr;
1589 bool Linker::linkInModule(Module *Src, unsigned Mode, std::string *ErrorMsg) {
1590 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src, Mode,
1592 if (TheLinker.run()) {
1594 *ErrorMsg = TheLinker.ErrorMsg;
1600 //===----------------------------------------------------------------------===//
1601 // LinkModules entrypoint.
1602 //===----------------------------------------------------------------------===//
1604 /// LinkModules - This function links two modules together, with the resulting
1605 /// Dest module modified to be the composite of the two input modules. If an
1606 /// error occurs, true is returned and ErrorMsg (if not null) is set to indicate
1607 /// the problem. Upon failure, the Dest module could be in a modified state,
1608 /// and shouldn't be relied on to be consistent.
1609 bool Linker::LinkModules(Module *Dest, Module *Src, unsigned Mode,
1610 std::string *ErrorMsg) {
1612 return L.linkInModule(Src, Mode, ErrorMsg);
1615 //===----------------------------------------------------------------------===//
1617 //===----------------------------------------------------------------------===//
1619 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
1620 LLVMLinkerMode Mode, char **OutMessages) {
1621 std::string Messages;
1622 LLVMBool Result = Linker::LinkModules(unwrap(Dest), unwrap(Src),
1623 Mode, OutMessages? &Messages : nullptr);
1625 *OutMessages = strdup(Messages.c_str());