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: ";
81 I->first->print(dbgs());
83 I->second->print(dbgs());
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 void upgradeMismatchedGlobalArray(StringRef Name);
473 void upgradeMismatchedGlobals();
475 bool linkAppendingVarProto(GlobalVariable *DstGV, GlobalVariable *SrcGV);
476 bool linkGlobalProto(GlobalVariable *SrcGV);
477 bool linkFunctionProto(Function *SrcF);
478 bool linkAliasProto(GlobalAlias *SrcA);
479 bool linkModuleFlagsMetadata();
481 void linkAppendingVarInit(const AppendingVarInfo &AVI);
482 void linkGlobalInits();
483 void linkFunctionBody(Function *Dst, Function *Src);
484 void linkAliasBodies();
485 void linkNamedMDNodes();
489 /// forceRenaming - The LLVM SymbolTable class autorenames globals that conflict
490 /// in the symbol table. This is good for all clients except for us. Go
491 /// through the trouble to force this back.
492 static void forceRenaming(GlobalValue *GV, StringRef Name) {
493 // If the global doesn't force its name or if it already has the right name,
494 // there is nothing for us to do.
495 if (GV->hasLocalLinkage() || GV->getName() == Name)
498 Module *M = GV->getParent();
500 // If there is a conflict, rename the conflict.
501 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
502 GV->takeName(ConflictGV);
503 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
504 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
506 GV->setName(Name); // Force the name back
510 /// copyGVAttributes - copy additional attributes (those not needed to construct
511 /// a GlobalValue) from the SrcGV to the DestGV.
512 static void copyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) {
513 // Use the maximum alignment, rather than just copying the alignment of SrcGV.
514 auto *DestGO = dyn_cast<GlobalObject>(DestGV);
517 Alignment = std::max(DestGO->getAlignment(), SrcGV->getAlignment());
519 DestGV->copyAttributesFrom(SrcGV);
522 DestGO->setAlignment(Alignment);
524 forceRenaming(DestGV, SrcGV->getName());
527 static bool isLessConstraining(GlobalValue::VisibilityTypes a,
528 GlobalValue::VisibilityTypes b) {
529 if (a == GlobalValue::HiddenVisibility)
531 if (b == GlobalValue::HiddenVisibility)
533 if (a == GlobalValue::ProtectedVisibility)
535 if (b == GlobalValue::ProtectedVisibility)
540 Value *ValueMaterializerTy::materializeValueFor(Value *V) {
541 Function *SF = dyn_cast<Function>(V);
545 Function *DF = Function::Create(TypeMap.get(SF->getFunctionType()),
546 SF->getLinkage(), SF->getName(), DstM);
547 copyGVAttributes(DF, SF);
549 if (Comdat *SC = SF->getComdat()) {
550 Comdat *DC = DstM->getOrInsertComdat(SC->getName());
554 LazilyLinkFunctions.push_back(SF);
558 bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName,
559 const GlobalVariable *&GVar) {
560 const GlobalValue *GVal = M->getNamedValue(ComdatName);
561 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
562 GVal = GA->getBaseObject();
564 // We cannot resolve the size of the aliasee yet.
565 return emitError("Linking COMDATs named '" + ComdatName +
566 "': COMDAT key involves incomputable alias size.");
569 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
572 "Linking COMDATs named '" + ComdatName +
573 "': GlobalVariable required for data dependent selection!");
578 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
579 Comdat::SelectionKind Src,
580 Comdat::SelectionKind Dst,
581 Comdat::SelectionKind &Result,
583 // The ability to mix Comdat::SelectionKind::Any with
584 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
585 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
586 Dst == Comdat::SelectionKind::Largest;
587 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
588 Src == Comdat::SelectionKind::Largest;
589 if (DstAnyOrLargest && SrcAnyOrLargest) {
590 if (Dst == Comdat::SelectionKind::Largest ||
591 Src == Comdat::SelectionKind::Largest)
592 Result = Comdat::SelectionKind::Largest;
594 Result = Comdat::SelectionKind::Any;
595 } else if (Src == Dst) {
598 return emitError("Linking COMDATs named '" + ComdatName +
599 "': invalid selection kinds!");
603 case Comdat::SelectionKind::Any:
607 case Comdat::SelectionKind::NoDuplicates:
608 return emitError("Linking COMDATs named '" + ComdatName +
609 "': noduplicates has been violated!");
610 case Comdat::SelectionKind::ExactMatch:
611 case Comdat::SelectionKind::Largest:
612 case Comdat::SelectionKind::SameSize: {
613 const GlobalVariable *DstGV;
614 const GlobalVariable *SrcGV;
615 if (getComdatLeader(DstM, ComdatName, DstGV) ||
616 getComdatLeader(SrcM, ComdatName, SrcGV))
619 const DataLayout *DstDL = DstM->getDataLayout();
620 const DataLayout *SrcDL = SrcM->getDataLayout();
621 if (!DstDL || !SrcDL) {
623 "Linking COMDATs named '" + ComdatName +
624 "': can't do size dependent selection without DataLayout!");
627 DstDL->getTypeAllocSize(DstGV->getType()->getPointerElementType());
629 SrcDL->getTypeAllocSize(SrcGV->getType()->getPointerElementType());
630 if (Result == Comdat::SelectionKind::ExactMatch) {
631 if (SrcGV->getInitializer() != DstGV->getInitializer())
632 return emitError("Linking COMDATs named '" + ComdatName +
633 "': ExactMatch violated!");
635 } else if (Result == Comdat::SelectionKind::Largest) {
636 LinkFromSrc = SrcSize > DstSize;
637 } else if (Result == Comdat::SelectionKind::SameSize) {
638 if (SrcSize != DstSize)
639 return emitError("Linking COMDATs named '" + ComdatName +
640 "': SameSize violated!");
643 llvm_unreachable("unknown selection kind");
652 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
653 Comdat::SelectionKind &Result,
655 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
656 StringRef ComdatName = SrcC->getName();
657 Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable();
658 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
660 if (DstCI == ComdatSymTab.end()) {
661 // Use the comdat if it is only available in one of the modules.
667 const Comdat *DstC = &DstCI->second;
668 Comdat::SelectionKind DSK = DstC->getSelectionKind();
669 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
673 // FIXME: Duplicated from the gold plugin. This should be refactored somewhere.
674 static bool isDeclaration(const GlobalValue &V) {
675 if (V.hasAvailableExternallyLinkage())
678 if (V.isMaterializable())
681 return V.isDeclaration();
684 /// This analyzes the two global values and determines what the result will look
685 /// like in the destination module. In particular, it computes the resultant
686 /// linkage type and visibility, computes whether the global in the source
687 /// should be copied over to the destination (replacing the existing one), and
688 /// computes whether this linkage is an error or not.
689 bool ModuleLinker::getLinkageResult(GlobalValue *Dest, const GlobalValue *Src,
690 GlobalValue::LinkageTypes <,
691 GlobalValue::VisibilityTypes &Vis,
693 assert(Dest && "Must have two globals being queried");
694 assert(!Src->hasLocalLinkage() &&
695 "If Src has internal linkage, Dest shouldn't be set!");
697 bool SrcIsDeclaration = isDeclaration(*Src);
698 bool DestIsDeclaration = isDeclaration(*Dest);
700 if (SrcIsDeclaration) {
701 // If Src is external or if both Src & Dest are external.. Just link the
702 // external globals, we aren't adding anything.
703 if (Src->hasDLLImportStorageClass()) {
704 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
705 if (DestIsDeclaration) {
707 LT = Src->getLinkage();
709 } else if (Dest->hasExternalWeakLinkage()) {
710 // If the Dest is weak, use the source linkage.
712 LT = Src->getLinkage();
715 LT = Dest->getLinkage();
717 } else if (DestIsDeclaration) {
718 // If Dest is external but Src is not:
720 LT = Src->getLinkage();
721 } else if (Src->isWeakForLinker()) {
722 assert(!Dest->hasExternalWeakLinkage());
723 assert(!Dest->hasAvailableExternallyLinkage());
724 if (Dest->hasLinkOnceLinkage() &&
725 (Src->hasWeakLinkage() || Src->hasCommonLinkage())) {
727 LT = Src->getLinkage();
730 LT = Dest->getLinkage();
732 } else if (Dest->isWeakForLinker()) {
733 assert(!Src->hasExternalWeakLinkage());
735 LT = GlobalValue::ExternalLinkage;
737 assert(!Src->hasExternalWeakLinkage());
738 assert(!Dest->hasExternalWeakLinkage());
739 assert(Dest->hasExternalLinkage() && Src->hasExternalLinkage() &&
740 "Unexpected linkage type!");
741 return emitError("Linking globals named '" + Src->getName() +
742 "': symbol multiply defined!");
745 // Compute the visibility. We follow the rules in the System V Application
747 assert(!GlobalValue::isLocalLinkage(LT) &&
748 "Symbols with local linkage should not be merged");
749 Vis = isLessConstraining(Src->getVisibility(), Dest->getVisibility()) ?
750 Dest->getVisibility() : Src->getVisibility();
754 /// computeTypeMapping - Loop over all of the linked values to compute type
755 /// mappings. For example, if we link "extern Foo *x" and "Foo *x = NULL", then
756 /// we have two struct types 'Foo' but one got renamed when the module was
757 /// loaded into the same LLVMContext.
758 void ModuleLinker::computeTypeMapping() {
759 // Incorporate globals.
760 for (Module::global_iterator I = SrcM->global_begin(),
761 E = SrcM->global_end(); I != E; ++I) {
762 GlobalValue *DGV = getLinkedToGlobal(I);
765 if (!DGV->hasAppendingLinkage() || !I->hasAppendingLinkage()) {
766 TypeMap.addTypeMapping(DGV->getType(), I->getType());
770 // Unify the element type of appending arrays.
771 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
772 ArrayType *SAT = cast<ArrayType>(I->getType()->getElementType());
773 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
776 // Incorporate functions.
777 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I) {
778 if (GlobalValue *DGV = getLinkedToGlobal(I))
779 TypeMap.addTypeMapping(DGV->getType(), I->getType());
782 // Incorporate types by name, scanning all the types in the source module.
783 // At this point, the destination module may have a type "%foo = { i32 }" for
784 // example. When the source module got loaded into the same LLVMContext, if
785 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
786 TypeFinder SrcStructTypes;
787 SrcStructTypes.run(*SrcM, true);
788 SmallPtrSet<StructType*, 32> SrcStructTypesSet(SrcStructTypes.begin(),
789 SrcStructTypes.end());
791 for (unsigned i = 0, e = SrcStructTypes.size(); i != e; ++i) {
792 StructType *ST = SrcStructTypes[i];
793 if (!ST->hasName()) continue;
795 // Check to see if there is a dot in the name followed by a digit.
796 size_t DotPos = ST->getName().rfind('.');
797 if (DotPos == 0 || DotPos == StringRef::npos ||
798 ST->getName().back() == '.' ||
799 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos+1])))
802 // Check to see if the destination module has a struct with the prefix name.
803 if (StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos)))
804 // Don't use it if this actually came from the source module. They're in
805 // the same LLVMContext after all. Also don't use it unless the type is
806 // actually used in the destination module. This can happen in situations
811 // %Z = type { %A } %B = type { %C.1 }
812 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
813 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
814 // %C = type { i8* } %B.3 = type { %C.1 }
816 // When we link Module B with Module A, the '%B' in Module B is
817 // used. However, that would then use '%C.1'. But when we process '%C.1',
818 // we prefer to take the '%C' version. So we are then left with both
819 // '%C.1' and '%C' being used for the same types. This leads to some
820 // variables using one type and some using the other.
821 if (!SrcStructTypesSet.count(DST) && TypeMap.DstStructTypesSet.count(DST))
822 TypeMap.addTypeMapping(DST, ST);
825 // Don't bother incorporating aliases, they aren't generally typed well.
827 // Now that we have discovered all of the type equivalences, get a body for
828 // any 'opaque' types in the dest module that are now resolved.
829 TypeMap.linkDefinedTypeBodies();
832 static void upgradeGlobalArray(GlobalVariable *GV) {
833 ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
834 StructType *OldTy = cast<StructType>(ATy->getElementType());
835 assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
837 // Get the upgraded 3 element type.
838 PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
839 Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
841 StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
843 // Build new constants with a null third field filled in.
844 Constant *OldInitC = GV->getInitializer();
845 ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
846 if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
847 // Invalid initializer; give up.
849 std::vector<Constant *> Initializers;
850 if (OldInit && OldInit->getNumOperands()) {
851 Value *Null = Constant::getNullValue(VoidPtrTy);
852 for (Use &U : OldInit->operands()) {
853 ConstantStruct *Init = cast<ConstantStruct>(U.get());
854 Initializers.push_back(ConstantStruct::get(
855 NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
858 assert(Initializers.size() == ATy->getNumElements() &&
859 "Failed to copy all array elements");
861 // Replace the old GV with a new one.
862 ATy = ArrayType::get(NewTy, Initializers.size());
863 Constant *NewInit = ConstantArray::get(ATy, Initializers);
864 GlobalVariable *NewGV = new GlobalVariable(
865 *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
866 GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
867 GV->isExternallyInitialized());
868 NewGV->copyAttributesFrom(GV);
870 assert(GV->use_empty() && "program cannot use initializer list");
871 GV->eraseFromParent();
874 void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
875 // Look for the global arrays.
876 auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM->getNamedValue(Name));
879 auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM->getNamedValue(Name));
883 // Check if the types already match.
884 auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
886 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
890 // Grab the element types. We can only upgrade an array of a two-field
891 // struct. Only bother if the other one has three-fields.
892 auto *DstEltTy = cast<StructType>(DstTy->getElementType());
893 auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
894 if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
895 upgradeGlobalArray(DstGV);
898 if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
899 upgradeGlobalArray(SrcGV);
901 // We can't upgrade any other differences.
904 void ModuleLinker::upgradeMismatchedGlobals() {
905 upgradeMismatchedGlobalArray("llvm.global_ctors");
906 upgradeMismatchedGlobalArray("llvm.global_dtors");
909 /// linkAppendingVarProto - If there were any appending global variables, link
910 /// them together now. Return true on error.
911 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
912 GlobalVariable *SrcGV) {
914 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
915 return emitError("Linking globals named '" + SrcGV->getName() +
916 "': can only link appending global with another appending global!");
918 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
920 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
921 Type *EltTy = DstTy->getElementType();
923 // Check to see that they two arrays agree on type.
924 if (EltTy != SrcTy->getElementType())
925 return emitError("Appending variables with different element types!");
926 if (DstGV->isConstant() != SrcGV->isConstant())
927 return emitError("Appending variables linked with different const'ness!");
929 if (DstGV->getAlignment() != SrcGV->getAlignment())
931 "Appending variables with different alignment need to be linked!");
933 if (DstGV->getVisibility() != SrcGV->getVisibility())
935 "Appending variables with different visibility need to be linked!");
937 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
939 "Appending variables with different unnamed_addr need to be linked!");
941 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
943 "Appending variables with different section name need to be linked!");
945 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements();
946 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
948 // Create the new global variable.
950 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(),
951 DstGV->getLinkage(), /*init*/nullptr, /*name*/"", DstGV,
952 DstGV->getThreadLocalMode(),
953 DstGV->getType()->getAddressSpace());
955 // Propagate alignment, visibility and section info.
956 copyGVAttributes(NG, DstGV);
958 AppendingVarInfo AVI;
960 AVI.DstInit = DstGV->getInitializer();
961 AVI.SrcInit = SrcGV->getInitializer();
962 AppendingVars.push_back(AVI);
964 // Replace any uses of the two global variables with uses of the new
966 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
968 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
969 DstGV->eraseFromParent();
971 // Track the source variable so we don't try to link it.
972 DoNotLinkFromSource.insert(SrcGV);
977 /// linkGlobalProto - Loop through the global variables in the src module and
978 /// merge them into the dest module.
979 bool ModuleLinker::linkGlobalProto(GlobalVariable *SGV) {
980 GlobalValue *DGV = getLinkedToGlobal(SGV);
981 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
982 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
984 bool LinkFromSrc = false;
985 Comdat *DC = nullptr;
986 if (const Comdat *SC = SGV->getComdat()) {
987 Comdat::SelectionKind SK;
988 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
989 DC = DstM->getOrInsertComdat(SC->getName());
990 DC->setSelectionKind(SK);
995 // Concatenation of appending linkage variables is magic and handled later.
996 if (DGV->hasAppendingLinkage() || SGV->hasAppendingLinkage())
997 return linkAppendingVarProto(cast<GlobalVariable>(DGV), SGV);
999 // Determine whether linkage of these two globals follows the source
1000 // module's definition or the destination module's definition.
1001 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
1002 GlobalValue::VisibilityTypes NV;
1003 if (getLinkageResult(DGV, SGV, NewLinkage, NV, LinkFromSrc))
1006 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1008 // If we're not linking from the source, then keep the definition that we
1011 // Special case for const propagation.
1012 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV))
1013 if (DGVar->isDeclaration() && SGV->isConstant() &&
1014 !DGVar->isConstant())
1015 DGVar->setConstant(true);
1017 // Set calculated linkage, visibility and unnamed_addr.
1018 DGV->setLinkage(NewLinkage);
1019 DGV->setVisibility(*NewVisibility);
1020 DGV->setUnnamedAddr(HasUnnamedAddr);
1025 // Make sure to remember this mapping.
1026 ValueMap[SGV] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGV->getType()));
1028 // Track the source global so that we don't attempt to copy it over when
1029 // processing global initializers.
1030 DoNotLinkFromSource.insert(SGV);
1036 // If the Comdat this variable was inside of wasn't selected, skip it.
1037 if (DC && !DGV && !LinkFromSrc) {
1038 DoNotLinkFromSource.insert(SGV);
1042 // No linking to be performed or linking from the source: simply create an
1043 // identical version of the symbol over in the dest module... the
1044 // initializer will be filled in later by LinkGlobalInits.
1045 GlobalVariable *NewDGV =
1046 new GlobalVariable(*DstM, TypeMap.get(SGV->getType()->getElementType()),
1047 SGV->isConstant(), SGV->getLinkage(), /*init*/nullptr,
1048 SGV->getName(), /*insertbefore*/nullptr,
1049 SGV->getThreadLocalMode(),
1050 SGV->getType()->getAddressSpace());
1051 // Propagate alignment, visibility and section info.
1052 copyGVAttributes(NewDGV, SGV);
1054 NewDGV->setVisibility(*NewVisibility);
1055 NewDGV->setUnnamedAddr(HasUnnamedAddr);
1058 NewDGV->setComdat(DC);
1061 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV, DGV->getType()));
1062 DGV->eraseFromParent();
1065 // Make sure to remember this mapping.
1066 ValueMap[SGV] = NewDGV;
1070 /// linkFunctionProto - Link the function in the source module into the
1071 /// destination module if needed, setting up mapping information.
1072 bool ModuleLinker::linkFunctionProto(Function *SF) {
1073 GlobalValue *DGV = getLinkedToGlobal(SF);
1074 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
1075 bool HasUnnamedAddr = SF->hasUnnamedAddr();
1077 bool LinkFromSrc = false;
1078 Comdat *DC = nullptr;
1079 if (const Comdat *SC = SF->getComdat()) {
1080 Comdat::SelectionKind SK;
1081 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1082 DC = DstM->getOrInsertComdat(SC->getName());
1083 DC->setSelectionKind(SK);
1088 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
1089 GlobalValue::VisibilityTypes NV;
1090 if (getLinkageResult(DGV, SF, NewLinkage, NV, LinkFromSrc))
1093 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1096 // Set calculated linkage
1097 DGV->setLinkage(NewLinkage);
1098 DGV->setVisibility(*NewVisibility);
1099 DGV->setUnnamedAddr(HasUnnamedAddr);
1104 // Make sure to remember this mapping.
1105 ValueMap[SF] = ConstantExpr::getBitCast(DGV, TypeMap.get(SF->getType()));
1107 // Track the function from the source module so we don't attempt to remap
1109 DoNotLinkFromSource.insert(SF);
1115 // If the function is to be lazily linked, don't create it just yet.
1116 // The ValueMaterializerTy will deal with creating it if it's used.
1117 if (!DGV && (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() ||
1118 SF->hasAvailableExternallyLinkage())) {
1119 DoNotLinkFromSource.insert(SF);
1123 // If the Comdat this function was inside of wasn't selected, skip it.
1124 if (DC && !DGV && !LinkFromSrc) {
1125 DoNotLinkFromSource.insert(SF);
1129 // If there is no linkage to be performed or we are linking from the source,
1131 Function *NewDF = Function::Create(TypeMap.get(SF->getFunctionType()),
1132 SF->getLinkage(), SF->getName(), DstM);
1133 copyGVAttributes(NewDF, SF);
1135 NewDF->setVisibility(*NewVisibility);
1136 NewDF->setUnnamedAddr(HasUnnamedAddr);
1139 NewDF->setComdat(DC);
1142 // Any uses of DF need to change to NewDF, with cast.
1143 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, DGV->getType()));
1144 DGV->eraseFromParent();
1147 ValueMap[SF] = NewDF;
1151 /// LinkAliasProto - Set up prototypes for any aliases that come over from the
1153 bool ModuleLinker::linkAliasProto(GlobalAlias *SGA) {
1154 GlobalValue *DGV = getLinkedToGlobal(SGA);
1155 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
1156 bool HasUnnamedAddr = SGA->hasUnnamedAddr();
1158 bool LinkFromSrc = false;
1159 Comdat *DC = nullptr;
1160 if (const Comdat *SC = SGA->getComdat()) {
1161 Comdat::SelectionKind SK;
1162 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1163 DC = DstM->getOrInsertComdat(SC->getName());
1164 DC->setSelectionKind(SK);
1169 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
1170 GlobalValue::VisibilityTypes NV;
1171 if (getLinkageResult(DGV, SGA, NewLinkage, NV, LinkFromSrc))
1174 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1177 // Set calculated linkage.
1178 DGV->setLinkage(NewLinkage);
1179 DGV->setVisibility(*NewVisibility);
1180 DGV->setUnnamedAddr(HasUnnamedAddr);
1185 // Make sure to remember this mapping.
1186 ValueMap[SGA] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGA->getType()));
1188 // Track the alias from the source module so we don't attempt to remap it.
1189 DoNotLinkFromSource.insert(SGA);
1195 // If the Comdat this alias was inside of wasn't selected, skip it.
1196 if (DC && !DGV && !LinkFromSrc) {
1197 DoNotLinkFromSource.insert(SGA);
1201 // If there is no linkage to be performed or we're linking from the source,
1203 auto *PTy = cast<PointerType>(TypeMap.get(SGA->getType()));
1205 GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(),
1206 SGA->getLinkage(), SGA->getName(), DstM);
1207 copyGVAttributes(NewDA, SGA);
1209 NewDA->setVisibility(*NewVisibility);
1210 NewDA->setUnnamedAddr(HasUnnamedAddr);
1213 // Any uses of DGV need to change to NewDA, with cast.
1214 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDA, DGV->getType()));
1215 DGV->eraseFromParent();
1218 ValueMap[SGA] = NewDA;
1222 static void getArrayElements(Constant *C, SmallVectorImpl<Constant*> &Dest) {
1223 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1225 for (unsigned i = 0; i != NumElements; ++i)
1226 Dest.push_back(C->getAggregateElement(i));
1229 void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) {
1230 // Merge the initializer.
1231 SmallVector<Constant *, 16> DstElements;
1232 getArrayElements(AVI.DstInit, DstElements);
1234 SmallVector<Constant *, 16> SrcElements;
1235 getArrayElements(AVI.SrcInit, SrcElements);
1237 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
1239 StringRef Name = AVI.NewGV->getName();
1240 bool IsNewStructor =
1241 (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
1242 cast<StructType>(NewType->getElementType())->getNumElements() == 3;
1244 for (auto *V : SrcElements) {
1245 if (IsNewStructor) {
1246 Constant *Key = V->getAggregateElement(2);
1247 if (DoNotLinkFromSource.count(Key))
1250 DstElements.push_back(
1251 MapValue(V, ValueMap, RF_None, &TypeMap, &ValMaterializer));
1253 if (IsNewStructor) {
1254 NewType = ArrayType::get(NewType->getElementType(), DstElements.size());
1255 AVI.NewGV->mutateType(PointerType::get(NewType, 0));
1258 AVI.NewGV->setInitializer(ConstantArray::get(NewType, DstElements));
1261 /// linkGlobalInits - Update the initializers in the Dest module now that all
1262 /// globals that may be referenced are in Dest.
1263 void ModuleLinker::linkGlobalInits() {
1264 // Loop over all of the globals in the src module, mapping them over as we go
1265 for (Module::const_global_iterator I = SrcM->global_begin(),
1266 E = SrcM->global_end(); I != E; ++I) {
1268 // Only process initialized GV's or ones not already in dest.
1269 if (!I->hasInitializer() || DoNotLinkFromSource.count(I)) continue;
1271 // Grab destination global variable.
1272 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[I]);
1273 // Figure out what the initializer looks like in the dest module.
1274 DGV->setInitializer(MapValue(I->getInitializer(), ValueMap,
1275 RF_None, &TypeMap, &ValMaterializer));
1279 /// linkFunctionBody - Copy the source function over into the dest function and
1280 /// fix up references to values. At this point we know that Dest is an external
1281 /// function, and that Src is not.
1282 void ModuleLinker::linkFunctionBody(Function *Dst, Function *Src) {
1283 assert(Src && Dst && Dst->isDeclaration() && !Src->isDeclaration());
1285 // Go through and convert function arguments over, remembering the mapping.
1286 Function::arg_iterator DI = Dst->arg_begin();
1287 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1288 I != E; ++I, ++DI) {
1289 DI->setName(I->getName()); // Copy the name over.
1291 // Add a mapping to our mapping.
1295 if (Mode == Linker::DestroySource) {
1296 // Splice the body of the source function into the dest function.
1297 Dst->getBasicBlockList().splice(Dst->end(), Src->getBasicBlockList());
1299 // At this point, all of the instructions and values of the function are now
1300 // copied over. The only problem is that they are still referencing values in
1301 // the Source function as operands. Loop through all of the operands of the
1302 // functions and patch them up to point to the local versions.
1303 for (Function::iterator BB = Dst->begin(), BE = Dst->end(); BB != BE; ++BB)
1304 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
1305 RemapInstruction(I, ValueMap, RF_IgnoreMissingEntries,
1306 &TypeMap, &ValMaterializer);
1309 // Clone the body of the function into the dest function.
1310 SmallVector<ReturnInst*, 8> Returns; // Ignore returns.
1311 CloneFunctionInto(Dst, Src, ValueMap, false, Returns, "", nullptr,
1312 &TypeMap, &ValMaterializer);
1315 // There is no need to map the arguments anymore.
1316 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1322 /// linkAliasBodies - Insert all of the aliases in Src into the Dest module.
1323 void ModuleLinker::linkAliasBodies() {
1324 for (Module::alias_iterator I = SrcM->alias_begin(), E = SrcM->alias_end();
1326 if (DoNotLinkFromSource.count(I))
1328 if (Constant *Aliasee = I->getAliasee()) {
1329 GlobalAlias *DA = cast<GlobalAlias>(ValueMap[I]);
1331 MapValue(Aliasee, ValueMap, RF_None, &TypeMap, &ValMaterializer);
1332 DA->setAliasee(Val);
1337 /// linkNamedMDNodes - Insert all of the named MDNodes in Src into the Dest
1339 void ModuleLinker::linkNamedMDNodes() {
1340 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1341 for (Module::const_named_metadata_iterator I = SrcM->named_metadata_begin(),
1342 E = SrcM->named_metadata_end(); I != E; ++I) {
1343 // Don't link module flags here. Do them separately.
1344 if (&*I == SrcModFlags) continue;
1345 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(I->getName());
1346 // Add Src elements into Dest node.
1347 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
1348 DestNMD->addOperand(MapValue(I->getOperand(i), ValueMap,
1349 RF_None, &TypeMap, &ValMaterializer));
1353 /// linkModuleFlagsMetadata - Merge the linker flags in Src into the Dest
1355 bool ModuleLinker::linkModuleFlagsMetadata() {
1356 // If the source module has no module flags, we are done.
1357 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1358 if (!SrcModFlags) return false;
1360 // If the destination module doesn't have module flags yet, then just copy
1361 // over the source module's flags.
1362 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
1363 if (DstModFlags->getNumOperands() == 0) {
1364 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1365 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1370 // First build a map of the existing module flags and requirements.
1371 DenseMap<MDString*, MDNode*> Flags;
1372 SmallSetVector<MDNode*, 16> Requirements;
1373 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1374 MDNode *Op = DstModFlags->getOperand(I);
1375 ConstantInt *Behavior = cast<ConstantInt>(Op->getOperand(0));
1376 MDString *ID = cast<MDString>(Op->getOperand(1));
1378 if (Behavior->getZExtValue() == Module::Require) {
1379 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1385 // Merge in the flags from the source module, and also collect its set of
1387 bool HasErr = false;
1388 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1389 MDNode *SrcOp = SrcModFlags->getOperand(I);
1390 ConstantInt *SrcBehavior = cast<ConstantInt>(SrcOp->getOperand(0));
1391 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1392 MDNode *DstOp = Flags.lookup(ID);
1393 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1395 // If this is a requirement, add it and continue.
1396 if (SrcBehaviorValue == Module::Require) {
1397 // If the destination module does not already have this requirement, add
1399 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1400 DstModFlags->addOperand(SrcOp);
1405 // If there is no existing flag with this ID, just add it.
1408 DstModFlags->addOperand(SrcOp);
1412 // Otherwise, perform a merge.
1413 ConstantInt *DstBehavior = cast<ConstantInt>(DstOp->getOperand(0));
1414 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1416 // If either flag has override behavior, handle it first.
1417 if (DstBehaviorValue == Module::Override) {
1418 // Diagnose inconsistent flags which both have override behavior.
1419 if (SrcBehaviorValue == Module::Override &&
1420 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1421 HasErr |= emitError("linking module flags '" + ID->getString() +
1422 "': IDs have conflicting override values");
1425 } else if (SrcBehaviorValue == Module::Override) {
1426 // Update the destination flag to that of the source.
1427 DstOp->replaceOperandWith(0, SrcBehavior);
1428 DstOp->replaceOperandWith(2, SrcOp->getOperand(2));
1432 // Diagnose inconsistent merge behavior types.
1433 if (SrcBehaviorValue != DstBehaviorValue) {
1434 HasErr |= emitError("linking module flags '" + ID->getString() +
1435 "': IDs have conflicting behaviors");
1439 // Perform the merge for standard behavior types.
1440 switch (SrcBehaviorValue) {
1441 case Module::Require:
1442 case Module::Override: llvm_unreachable("not possible");
1443 case Module::Error: {
1444 // Emit an error if the values differ.
1445 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1446 HasErr |= emitError("linking module flags '" + ID->getString() +
1447 "': IDs have conflicting values");
1451 case Module::Warning: {
1452 // Emit a warning if the values differ.
1453 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1454 if (!SuppressWarnings) {
1455 errs() << "WARNING: linking module flags '" << ID->getString()
1456 << "': IDs have conflicting values";
1461 case Module::Append: {
1462 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1463 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1464 unsigned NumOps = DstValue->getNumOperands() + SrcValue->getNumOperands();
1465 Value **VP, **Values = VP = new Value*[NumOps];
1466 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i, ++VP)
1467 *VP = DstValue->getOperand(i);
1468 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i, ++VP)
1469 *VP = SrcValue->getOperand(i);
1470 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1471 ArrayRef<Value*>(Values,
1476 case Module::AppendUnique: {
1477 SmallSetVector<Value*, 16> Elts;
1478 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1479 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1480 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i)
1481 Elts.insert(DstValue->getOperand(i));
1482 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i)
1483 Elts.insert(SrcValue->getOperand(i));
1484 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1485 ArrayRef<Value*>(Elts.begin(),
1492 // Check all of the requirements.
1493 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1494 MDNode *Requirement = Requirements[I];
1495 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1496 Value *ReqValue = Requirement->getOperand(1);
1498 MDNode *Op = Flags[Flag];
1499 if (!Op || Op->getOperand(2) != ReqValue) {
1500 HasErr |= emitError("linking module flags '" + Flag->getString() +
1501 "': does not have the required value");
1509 bool ModuleLinker::run() {
1510 assert(DstM && "Null destination module");
1511 assert(SrcM && "Null source module");
1513 // Inherit the target data from the source module if the destination module
1514 // doesn't have one already.
1515 if (!DstM->getDataLayout() && SrcM->getDataLayout())
1516 DstM->setDataLayout(SrcM->getDataLayout());
1518 // Copy the target triple from the source to dest if the dest's is empty.
1519 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
1520 DstM->setTargetTriple(SrcM->getTargetTriple());
1522 if (SrcM->getDataLayout() && DstM->getDataLayout() &&
1523 *SrcM->getDataLayout() != *DstM->getDataLayout()) {
1524 if (!SuppressWarnings) {
1525 errs() << "WARNING: Linking two modules of different data layouts: '"
1526 << SrcM->getModuleIdentifier() << "' is '"
1527 << SrcM->getDataLayoutStr() << "' whereas '"
1528 << DstM->getModuleIdentifier() << "' is '"
1529 << DstM->getDataLayoutStr() << "'\n";
1532 if (!SrcM->getTargetTriple().empty() &&
1533 DstM->getTargetTriple() != SrcM->getTargetTriple()) {
1534 if (!SuppressWarnings) {
1535 errs() << "WARNING: Linking two modules of different target triples: "
1536 << SrcM->getModuleIdentifier() << "' is '"
1537 << SrcM->getTargetTriple() << "' whereas '"
1538 << DstM->getModuleIdentifier() << "' is '"
1539 << DstM->getTargetTriple() << "'\n";
1543 // Append the module inline asm string.
1544 if (!SrcM->getModuleInlineAsm().empty()) {
1545 if (DstM->getModuleInlineAsm().empty())
1546 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
1548 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
1549 SrcM->getModuleInlineAsm());
1552 // Loop over all of the linked values to compute type mappings.
1553 computeTypeMapping();
1555 ComdatsChosen.clear();
1556 for (const StringMapEntry<llvm::Comdat> &SMEC : SrcM->getComdatSymbolTable()) {
1557 const Comdat &C = SMEC.getValue();
1558 if (ComdatsChosen.count(&C))
1560 Comdat::SelectionKind SK;
1562 if (getComdatResult(&C, SK, LinkFromSrc))
1564 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1567 // Upgrade mismatched global arrays.
1568 upgradeMismatchedGlobals();
1570 // Insert all of the globals in src into the DstM module... without linking
1571 // initializers (which could refer to functions not yet mapped over).
1572 for (Module::global_iterator I = SrcM->global_begin(),
1573 E = SrcM->global_end(); I != E; ++I)
1574 if (linkGlobalProto(I))
1577 // Link the functions together between the two modules, without doing function
1578 // bodies... this just adds external function prototypes to the DstM
1579 // function... We do this so that when we begin processing function bodies,
1580 // all of the global values that may be referenced are available in our
1582 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I)
1583 if (linkFunctionProto(I))
1586 // If there were any aliases, link them now.
1587 for (Module::alias_iterator I = SrcM->alias_begin(),
1588 E = SrcM->alias_end(); I != E; ++I)
1589 if (linkAliasProto(I))
1592 for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i)
1593 linkAppendingVarInit(AppendingVars[i]);
1595 // Link in the function bodies that are defined in the source module into
1597 for (Module::iterator SF = SrcM->begin(), E = SrcM->end(); SF != E; ++SF) {
1598 // Skip if not linking from source.
1599 if (DoNotLinkFromSource.count(SF)) continue;
1601 Function *DF = cast<Function>(ValueMap[SF]);
1602 if (SF->hasPrefixData()) {
1603 // Link in the prefix data.
1604 DF->setPrefixData(MapValue(
1605 SF->getPrefixData(), ValueMap, RF_None, &TypeMap, &ValMaterializer));
1608 // Skip if no body (function is external) or materialize.
1609 if (SF->isDeclaration()) {
1610 if (!SF->isMaterializable())
1612 if (SF->Materialize(&ErrorMsg))
1616 linkFunctionBody(DF, SF);
1617 SF->Dematerialize();
1620 // Resolve all uses of aliases with aliasees.
1623 // Remap all of the named MDNodes in Src into the DstM module. We do this
1624 // after linking GlobalValues so that MDNodes that reference GlobalValues
1625 // are properly remapped.
1628 // Merge the module flags into the DstM module.
1629 if (linkModuleFlagsMetadata())
1632 // Update the initializers in the DstM module now that all globals that may
1633 // be referenced are in DstM.
1636 // Process vector of lazily linked in functions.
1637 bool LinkedInAnyFunctions;
1639 LinkedInAnyFunctions = false;
1641 for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(),
1642 E = LazilyLinkFunctions.end(); I != E; ++I) {
1647 Function *DF = cast<Function>(ValueMap[SF]);
1648 if (SF->hasPrefixData()) {
1649 // Link in the prefix data.
1650 DF->setPrefixData(MapValue(SF->getPrefixData(),
1657 // Materialize if necessary.
1658 if (SF->isDeclaration()) {
1659 if (!SF->isMaterializable())
1661 if (SF->Materialize(&ErrorMsg))
1665 // Erase from vector *before* the function body is linked - linkFunctionBody could
1667 LazilyLinkFunctions.erase(I);
1669 // Link in function body.
1670 linkFunctionBody(DF, SF);
1671 SF->Dematerialize();
1673 // Set flag to indicate we may have more functions to lazily link in
1674 // since we linked in a function.
1675 LinkedInAnyFunctions = true;
1678 } while (LinkedInAnyFunctions);
1680 // Now that all of the types from the source are used, resolve any structs
1681 // copied over to the dest that didn't exist there.
1682 TypeMap.linkDefinedTypeBodies();
1687 Linker::Linker(Module *M, bool SuppressWarnings)
1688 : Composite(M), SuppressWarnings(SuppressWarnings) {
1689 TypeFinder StructTypes;
1690 StructTypes.run(*M, true);
1691 IdentifiedStructTypes.insert(StructTypes.begin(), StructTypes.end());
1697 void Linker::deleteModule() {
1699 Composite = nullptr;
1702 bool Linker::linkInModule(Module *Src, unsigned Mode, std::string *ErrorMsg) {
1703 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src, Mode,
1705 if (TheLinker.run()) {
1707 *ErrorMsg = TheLinker.ErrorMsg;
1713 //===----------------------------------------------------------------------===//
1714 // LinkModules entrypoint.
1715 //===----------------------------------------------------------------------===//
1717 /// LinkModules - This function links two modules together, with the resulting
1718 /// Dest module modified to be the composite of the two input modules. If an
1719 /// error occurs, true is returned and ErrorMsg (if not null) is set to indicate
1720 /// the problem. Upon failure, the Dest module could be in a modified state,
1721 /// and shouldn't be relied on to be consistent.
1722 bool Linker::LinkModules(Module *Dest, Module *Src, unsigned Mode,
1723 std::string *ErrorMsg) {
1725 return L.linkInModule(Src, Mode, ErrorMsg);
1728 //===----------------------------------------------------------------------===//
1730 //===----------------------------------------------------------------------===//
1732 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
1733 LLVMLinkerMode Mode, char **OutMessages) {
1734 std::string Messages;
1735 LLVMBool Result = Linker::LinkModules(unwrap(Dest), unwrap(Src),
1736 Mode, OutMessages? &Messages : nullptr);
1738 *OutMessages = strdup(Messages.c_str());