1 //===- lib/Linker/LinkModules.cpp - Module Linker Implementation ----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the LLVM module linker.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Linker/Linker.h"
15 #include "llvm-c/Linker.h"
16 #include "llvm/ADT/Optional.h"
17 #include "llvm/ADT/SetVector.h"
18 #include "llvm/ADT/SmallString.h"
19 #include "llvm/IR/Constants.h"
20 #include "llvm/IR/DiagnosticInfo.h"
21 #include "llvm/IR/DiagnosticPrinter.h"
22 #include "llvm/IR/LLVMContext.h"
23 #include "llvm/IR/Module.h"
24 #include "llvm/IR/TypeFinder.h"
25 #include "llvm/Support/CommandLine.h"
26 #include "llvm/Support/Debug.h"
27 #include "llvm/Support/raw_ostream.h"
28 #include "llvm/Transforms/Utils/Cloning.h"
34 //===----------------------------------------------------------------------===//
35 // TypeMap implementation.
36 //===----------------------------------------------------------------------===//
39 typedef SmallPtrSet<StructType *, 32> TypeSet;
41 class TypeMapTy : public ValueMapTypeRemapper {
42 /// This is a mapping from a source type to a destination type to use.
43 DenseMap<Type*, Type*> MappedTypes;
45 /// When checking to see if two subgraphs are isomorphic, we speculatively
46 /// add types to MappedTypes, but keep track of them here in case we need to
48 SmallVector<Type*, 16> SpeculativeTypes;
50 /// This is a list of non-opaque structs in the source module that are mapped
51 /// to an opaque struct in the destination module.
52 SmallVector<StructType*, 16> SrcDefinitionsToResolve;
54 /// This is the set of opaque types in the destination modules who are
55 /// getting a body from the source module.
56 SmallPtrSet<StructType*, 16> DstResolvedOpaqueTypes;
59 TypeMapTy(TypeSet &Set) : DstStructTypesSet(Set) {}
61 TypeSet &DstStructTypesSet;
62 /// Indicate that the specified type in the destination module is conceptually
63 /// equivalent to the specified type in the source module.
64 void addTypeMapping(Type *DstTy, Type *SrcTy);
66 /// linkDefinedTypeBodies - Produce a body for an opaque type in the dest
67 /// module from a type definition in the source module.
68 void linkDefinedTypeBodies();
70 /// Return the mapped type to use for the specified input type from the
72 Type *get(Type *SrcTy);
74 FunctionType *get(FunctionType *T) {return cast<FunctionType>(get((Type*)T));}
76 /// Dump out the type map for debugging purposes.
78 for (DenseMap<Type*, Type*>::const_iterator
79 I = MappedTypes.begin(), E = MappedTypes.end(); I != E; ++I) {
80 dbgs() << "TypeMap: ";
81 I->first->print(dbgs());
83 I->second->print(dbgs());
89 Type *getImpl(Type *T);
90 /// Implement the ValueMapTypeRemapper interface.
91 Type *remapType(Type *SrcTy) override {
95 bool areTypesIsomorphic(Type *DstTy, Type *SrcTy);
99 void TypeMapTy::addTypeMapping(Type *DstTy, Type *SrcTy) {
100 Type *&Entry = MappedTypes[SrcTy];
103 if (DstTy == SrcTy) {
108 // Check to see if these types are recursively isomorphic and establish a
109 // mapping between them if so.
110 if (!areTypesIsomorphic(DstTy, SrcTy)) {
111 // Oops, they aren't isomorphic. Just discard this request by rolling out
112 // any speculative mappings we've established.
113 for (unsigned i = 0, e = SpeculativeTypes.size(); i != e; ++i)
114 MappedTypes.erase(SpeculativeTypes[i]);
116 SpeculativeTypes.clear();
119 /// Recursively walk this pair of types, returning true if they are isomorphic,
120 /// false if they are not.
121 bool TypeMapTy::areTypesIsomorphic(Type *DstTy, Type *SrcTy) {
122 // Two types with differing kinds are clearly not isomorphic.
123 if (DstTy->getTypeID() != SrcTy->getTypeID()) return false;
125 // If we have an entry in the MappedTypes table, then we have our answer.
126 Type *&Entry = MappedTypes[SrcTy];
128 return Entry == DstTy;
130 // Two identical types are clearly isomorphic. Remember this
131 // non-speculatively.
132 if (DstTy == SrcTy) {
137 // Okay, we have two types with identical kinds that we haven't seen before.
139 // If this is an opaque struct type, special case it.
140 if (StructType *SSTy = dyn_cast<StructType>(SrcTy)) {
141 // Mapping an opaque type to any struct, just keep the dest struct.
142 if (SSTy->isOpaque()) {
144 SpeculativeTypes.push_back(SrcTy);
148 // Mapping a non-opaque source type to an opaque dest. If this is the first
149 // type that we're mapping onto this destination type then we succeed. Keep
150 // the dest, but fill it in later. This doesn't need to be speculative. If
151 // this is the second (different) type that we're trying to map onto the
152 // same opaque type then we fail.
153 if (cast<StructType>(DstTy)->isOpaque()) {
154 // We can only map one source type onto the opaque destination type.
155 if (!DstResolvedOpaqueTypes.insert(cast<StructType>(DstTy)))
157 SrcDefinitionsToResolve.push_back(SSTy);
163 // If the number of subtypes disagree between the two types, then we fail.
164 if (SrcTy->getNumContainedTypes() != DstTy->getNumContainedTypes())
167 // Fail if any of the extra properties (e.g. array size) of the type disagree.
168 if (isa<IntegerType>(DstTy))
169 return false; // bitwidth disagrees.
170 if (PointerType *PT = dyn_cast<PointerType>(DstTy)) {
171 if (PT->getAddressSpace() != cast<PointerType>(SrcTy)->getAddressSpace())
174 } else if (FunctionType *FT = dyn_cast<FunctionType>(DstTy)) {
175 if (FT->isVarArg() != cast<FunctionType>(SrcTy)->isVarArg())
177 } else if (StructType *DSTy = dyn_cast<StructType>(DstTy)) {
178 StructType *SSTy = cast<StructType>(SrcTy);
179 if (DSTy->isLiteral() != SSTy->isLiteral() ||
180 DSTy->isPacked() != SSTy->isPacked())
182 } else if (ArrayType *DATy = dyn_cast<ArrayType>(DstTy)) {
183 if (DATy->getNumElements() != cast<ArrayType>(SrcTy)->getNumElements())
185 } else if (VectorType *DVTy = dyn_cast<VectorType>(DstTy)) {
186 if (DVTy->getNumElements() != cast<VectorType>(SrcTy)->getNumElements())
190 // Otherwise, we speculate that these two types will line up and recursively
191 // check the subelements.
193 SpeculativeTypes.push_back(SrcTy);
195 for (unsigned i = 0, e = SrcTy->getNumContainedTypes(); i != e; ++i)
196 if (!areTypesIsomorphic(DstTy->getContainedType(i),
197 SrcTy->getContainedType(i)))
200 // If everything seems to have lined up, then everything is great.
204 /// Produce a body for an opaque type in the dest module from a type definition
205 /// in the source module.
206 void TypeMapTy::linkDefinedTypeBodies() {
207 SmallVector<Type*, 16> Elements;
208 SmallString<16> TmpName;
210 // Note that processing entries in this loop (calling 'get') can add new
211 // entries to the SrcDefinitionsToResolve vector.
212 while (!SrcDefinitionsToResolve.empty()) {
213 StructType *SrcSTy = SrcDefinitionsToResolve.pop_back_val();
214 StructType *DstSTy = cast<StructType>(MappedTypes[SrcSTy]);
216 // TypeMap is a many-to-one mapping, if there were multiple types that
217 // provide a body for DstSTy then previous iterations of this loop may have
218 // already handled it. Just ignore this case.
219 if (!DstSTy->isOpaque()) continue;
220 assert(!SrcSTy->isOpaque() && "Not resolving a definition?");
222 // Map the body of the source type over to a new body for the dest type.
223 Elements.resize(SrcSTy->getNumElements());
224 for (unsigned i = 0, e = Elements.size(); i != e; ++i)
225 Elements[i] = getImpl(SrcSTy->getElementType(i));
227 DstSTy->setBody(Elements, SrcSTy->isPacked());
229 // If DstSTy has no name or has a longer name than STy, then viciously steal
231 if (!SrcSTy->hasName()) continue;
232 StringRef SrcName = SrcSTy->getName();
234 if (!DstSTy->hasName() || DstSTy->getName().size() > SrcName.size()) {
235 TmpName.insert(TmpName.end(), SrcName.begin(), SrcName.end());
237 DstSTy->setName(TmpName.str());
242 DstResolvedOpaqueTypes.clear();
245 Type *TypeMapTy::get(Type *Ty) {
246 Type *Result = getImpl(Ty);
248 // If this caused a reference to any struct type, resolve it before returning.
249 if (!SrcDefinitionsToResolve.empty())
250 linkDefinedTypeBodies();
254 /// This is the recursive version of get().
255 Type *TypeMapTy::getImpl(Type *Ty) {
256 // If we already have an entry for this type, return it.
257 Type **Entry = &MappedTypes[Ty];
258 if (*Entry) return *Entry;
260 // If this is not a named struct type, then just map all of the elements and
261 // then rebuild the type from inside out.
262 if (!isa<StructType>(Ty) || cast<StructType>(Ty)->isLiteral()) {
263 // If there are no element types to map, then the type is itself. This is
264 // true for the anonymous {} struct, things like 'float', integers, etc.
265 if (Ty->getNumContainedTypes() == 0)
268 // Remap all of the elements, keeping track of whether any of them change.
269 bool AnyChange = false;
270 SmallVector<Type*, 4> ElementTypes;
271 ElementTypes.resize(Ty->getNumContainedTypes());
272 for (unsigned i = 0, e = Ty->getNumContainedTypes(); i != e; ++i) {
273 ElementTypes[i] = getImpl(Ty->getContainedType(i));
274 AnyChange |= ElementTypes[i] != Ty->getContainedType(i);
277 // If we found our type while recursively processing stuff, just use it.
278 Entry = &MappedTypes[Ty];
279 if (*Entry) return *Entry;
281 // If all of the element types mapped directly over, then the type is usable
286 // Otherwise, rebuild a modified type.
287 switch (Ty->getTypeID()) {
288 default: llvm_unreachable("unknown derived type to remap");
289 case Type::ArrayTyID:
290 return *Entry = ArrayType::get(ElementTypes[0],
291 cast<ArrayType>(Ty)->getNumElements());
292 case Type::VectorTyID:
293 return *Entry = VectorType::get(ElementTypes[0],
294 cast<VectorType>(Ty)->getNumElements());
295 case Type::PointerTyID:
296 return *Entry = PointerType::get(ElementTypes[0],
297 cast<PointerType>(Ty)->getAddressSpace());
298 case Type::FunctionTyID:
299 return *Entry = FunctionType::get(ElementTypes[0],
300 makeArrayRef(ElementTypes).slice(1),
301 cast<FunctionType>(Ty)->isVarArg());
302 case Type::StructTyID:
303 // Note that this is only reached for anonymous structs.
304 return *Entry = StructType::get(Ty->getContext(), ElementTypes,
305 cast<StructType>(Ty)->isPacked());
309 // Otherwise, this is an unmapped named struct. If the struct can be directly
310 // mapped over, just use it as-is. This happens in a case when the linked-in
311 // module has something like:
312 // %T = type {%T*, i32}
313 // @GV = global %T* null
314 // where T does not exist at all in the destination module.
316 // The other case we watch for is when the type is not in the destination
317 // module, but that it has to be rebuilt because it refers to something that
318 // is already mapped. For example, if the destination module has:
320 // and the source module has something like
321 // %A' = type { i32 }
322 // %B = type { %A'* }
323 // @GV = global %B* null
324 // then we want to create a new type: "%B = type { %A*}" and have it take the
325 // pristine "%B" name from the source module.
327 // To determine which case this is, we have to recursively walk the type graph
328 // speculating that we'll be able to reuse it unmodified. Only if this is
329 // safe would we map the entire thing over. Because this is an optimization,
330 // and is not required for the prettiness of the linked module, we just skip
331 // it and always rebuild a type here.
332 StructType *STy = cast<StructType>(Ty);
334 // If the type is opaque, we can just use it directly.
335 if (STy->isOpaque()) {
336 // A named structure type from src module is used. Add it to the Set of
337 // identified structs in the destination module.
338 DstStructTypesSet.insert(STy);
342 // Otherwise we create a new type and resolve its body later. This will be
343 // resolved by the top level of get().
344 SrcDefinitionsToResolve.push_back(STy);
345 StructType *DTy = StructType::create(STy->getContext());
346 // A new identified structure type was created. Add it to the set of
347 // identified structs in the destination module.
348 DstStructTypesSet.insert(DTy);
349 DstResolvedOpaqueTypes.insert(DTy);
353 //===----------------------------------------------------------------------===//
354 // ModuleLinker implementation.
355 //===----------------------------------------------------------------------===//
360 /// Creates prototypes for functions that are lazily linked on the fly. This
361 /// speeds up linking for modules with many/ lazily linked functions of which
363 class ValueMaterializerTy : public ValueMaterializer {
366 std::vector<Function*> &LazilyLinkFunctions;
368 ValueMaterializerTy(TypeMapTy &TypeMap, Module *DstM,
369 std::vector<Function*> &LazilyLinkFunctions) :
370 ValueMaterializer(), TypeMap(TypeMap), DstM(DstM),
371 LazilyLinkFunctions(LazilyLinkFunctions) {
374 Value *materializeValueFor(Value *V) override;
378 class LinkDiagnosticInfo : public DiagnosticInfo {
382 LinkDiagnosticInfo(DiagnosticSeverity Severity, const Twine &Msg);
383 void print(DiagnosticPrinter &DP) const override;
385 LinkDiagnosticInfo::LinkDiagnosticInfo(DiagnosticSeverity Severity,
387 : DiagnosticInfo(DK_Linker, Severity), Msg(Msg) {}
388 void LinkDiagnosticInfo::print(DiagnosticPrinter &DP) const { DP << Msg; }
391 /// This is an implementation class for the LinkModules function, which is the
392 /// entrypoint for this file.
397 ValueMaterializerTy ValMaterializer;
399 /// Mapping of values from what they used to be in Src, to what they are now
400 /// in DstM. ValueToValueMapTy is a ValueMap, which involves some overhead
401 /// due to the use of Value handles which the Linker doesn't actually need,
402 /// but this allows us to reuse the ValueMapper code.
403 ValueToValueMapTy ValueMap;
405 struct AppendingVarInfo {
406 GlobalVariable *NewGV; // New aggregate global in dest module.
407 Constant *DstInit; // Old initializer from dest module.
408 Constant *SrcInit; // Old initializer from src module.
411 std::vector<AppendingVarInfo> AppendingVars;
413 // Set of items not to link in from source.
414 SmallPtrSet<const Value*, 16> DoNotLinkFromSource;
416 // Vector of functions to lazily link in.
417 std::vector<Function*> LazilyLinkFunctions;
419 Linker::DiagnosticHandlerFunction DiagnosticHandler;
422 ModuleLinker(Module *dstM, TypeSet &Set, Module *srcM,
423 Linker::DiagnosticHandlerFunction DiagnosticHandler)
424 : DstM(dstM), SrcM(srcM), TypeMap(Set),
425 ValMaterializer(TypeMap, DstM, LazilyLinkFunctions),
426 DiagnosticHandler(DiagnosticHandler) {}
431 bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
432 const GlobalValue &Src);
434 /// Helper method for setting a message and returning an error code.
435 bool emitError(const Twine &Message) {
436 DiagnosticHandler(LinkDiagnosticInfo(DS_Error, Message));
440 void emitWarning(const Twine &Message) {
441 DiagnosticHandler(LinkDiagnosticInfo(DS_Warning, Message));
444 bool getComdatLeader(Module *M, StringRef ComdatName,
445 const GlobalVariable *&GVar);
446 bool computeResultingSelectionKind(StringRef ComdatName,
447 Comdat::SelectionKind Src,
448 Comdat::SelectionKind Dst,
449 Comdat::SelectionKind &Result,
451 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
453 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
456 /// This analyzes the two global values and determines what the result will
457 /// look like in the destination module.
458 bool getLinkageResult(GlobalValue *Dest, const GlobalValue *Src,
459 GlobalValue::LinkageTypes <,
460 GlobalValue::VisibilityTypes &Vis,
463 /// Given a global in the source module, return the global in the
464 /// destination module that is being linked to, if any.
465 GlobalValue *getLinkedToGlobal(GlobalValue *SrcGV) {
466 // If the source has no name it can't link. If it has local linkage,
467 // there is no name match-up going on.
468 if (!SrcGV->hasName() || SrcGV->hasLocalLinkage())
471 // Otherwise see if we have a match in the destination module's symtab.
472 GlobalValue *DGV = DstM->getNamedValue(SrcGV->getName());
473 if (!DGV) return nullptr;
475 // If we found a global with the same name in the dest module, but it has
476 // internal linkage, we are really not doing any linkage here.
477 if (DGV->hasLocalLinkage())
480 // Otherwise, we do in fact link to the destination global.
484 void computeTypeMapping();
486 void upgradeMismatchedGlobalArray(StringRef Name);
487 void upgradeMismatchedGlobals();
489 bool linkAppendingVarProto(GlobalVariable *DstGV, GlobalVariable *SrcGV);
490 bool linkGlobalProto(GlobalVariable *SrcGV);
491 bool linkFunctionProto(Function *SrcF);
492 bool linkAliasProto(GlobalAlias *SrcA);
493 bool linkModuleFlagsMetadata();
495 void linkAppendingVarInit(const AppendingVarInfo &AVI);
496 void linkGlobalInits();
497 void linkFunctionBody(Function *Dst, Function *Src);
498 void linkAliasBodies();
499 void linkNamedMDNodes();
503 /// The LLVM SymbolTable class autorenames globals that conflict in the symbol
504 /// table. This is good for all clients except for us. Go through the trouble
505 /// to force this back.
506 static void forceRenaming(GlobalValue *GV, StringRef Name) {
507 // If the global doesn't force its name or if it already has the right name,
508 // there is nothing for us to do.
509 if (GV->hasLocalLinkage() || GV->getName() == Name)
512 Module *M = GV->getParent();
514 // If there is a conflict, rename the conflict.
515 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
516 GV->takeName(ConflictGV);
517 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
518 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
520 GV->setName(Name); // Force the name back
524 /// copy additional attributes (those not needed to construct a GlobalValue)
525 /// from the SrcGV to the DestGV.
526 static void copyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) {
527 // Use the maximum alignment, rather than just copying the alignment of SrcGV.
528 auto *DestGO = dyn_cast<GlobalObject>(DestGV);
531 Alignment = std::max(DestGO->getAlignment(), SrcGV->getAlignment());
533 DestGV->copyAttributesFrom(SrcGV);
536 DestGO->setAlignment(Alignment);
538 forceRenaming(DestGV, SrcGV->getName());
541 static bool isLessConstraining(GlobalValue::VisibilityTypes a,
542 GlobalValue::VisibilityTypes b) {
543 if (a == GlobalValue::HiddenVisibility)
545 if (b == GlobalValue::HiddenVisibility)
547 if (a == GlobalValue::ProtectedVisibility)
549 if (b == GlobalValue::ProtectedVisibility)
554 Value *ValueMaterializerTy::materializeValueFor(Value *V) {
555 Function *SF = dyn_cast<Function>(V);
559 Function *DF = Function::Create(TypeMap.get(SF->getFunctionType()),
560 SF->getLinkage(), SF->getName(), DstM);
561 copyGVAttributes(DF, SF);
563 if (Comdat *SC = SF->getComdat()) {
564 Comdat *DC = DstM->getOrInsertComdat(SC->getName());
568 LazilyLinkFunctions.push_back(SF);
572 bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName,
573 const GlobalVariable *&GVar) {
574 const GlobalValue *GVal = M->getNamedValue(ComdatName);
575 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
576 GVal = GA->getBaseObject();
578 // We cannot resolve the size of the aliasee yet.
579 return emitError("Linking COMDATs named '" + ComdatName +
580 "': COMDAT key involves incomputable alias size.");
583 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
586 "Linking COMDATs named '" + ComdatName +
587 "': GlobalVariable required for data dependent selection!");
592 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
593 Comdat::SelectionKind Src,
594 Comdat::SelectionKind Dst,
595 Comdat::SelectionKind &Result,
597 // The ability to mix Comdat::SelectionKind::Any with
598 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
599 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
600 Dst == Comdat::SelectionKind::Largest;
601 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
602 Src == Comdat::SelectionKind::Largest;
603 if (DstAnyOrLargest && SrcAnyOrLargest) {
604 if (Dst == Comdat::SelectionKind::Largest ||
605 Src == Comdat::SelectionKind::Largest)
606 Result = Comdat::SelectionKind::Largest;
608 Result = Comdat::SelectionKind::Any;
609 } else if (Src == Dst) {
612 return emitError("Linking COMDATs named '" + ComdatName +
613 "': invalid selection kinds!");
617 case Comdat::SelectionKind::Any:
621 case Comdat::SelectionKind::NoDuplicates:
622 return emitError("Linking COMDATs named '" + ComdatName +
623 "': noduplicates has been violated!");
624 case Comdat::SelectionKind::ExactMatch:
625 case Comdat::SelectionKind::Largest:
626 case Comdat::SelectionKind::SameSize: {
627 const GlobalVariable *DstGV;
628 const GlobalVariable *SrcGV;
629 if (getComdatLeader(DstM, ComdatName, DstGV) ||
630 getComdatLeader(SrcM, ComdatName, SrcGV))
633 const DataLayout *DstDL = DstM->getDataLayout();
634 const DataLayout *SrcDL = SrcM->getDataLayout();
635 if (!DstDL || !SrcDL) {
637 "Linking COMDATs named '" + ComdatName +
638 "': can't do size dependent selection without DataLayout!");
641 DstDL->getTypeAllocSize(DstGV->getType()->getPointerElementType());
643 SrcDL->getTypeAllocSize(SrcGV->getType()->getPointerElementType());
644 if (Result == Comdat::SelectionKind::ExactMatch) {
645 if (SrcGV->getInitializer() != DstGV->getInitializer())
646 return emitError("Linking COMDATs named '" + ComdatName +
647 "': ExactMatch violated!");
649 } else if (Result == Comdat::SelectionKind::Largest) {
650 LinkFromSrc = SrcSize > DstSize;
651 } else if (Result == Comdat::SelectionKind::SameSize) {
652 if (SrcSize != DstSize)
653 return emitError("Linking COMDATs named '" + ComdatName +
654 "': SameSize violated!");
657 llvm_unreachable("unknown selection kind");
666 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
667 Comdat::SelectionKind &Result,
669 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
670 StringRef ComdatName = SrcC->getName();
671 Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable();
672 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
674 if (DstCI == ComdatSymTab.end()) {
675 // Use the comdat if it is only available in one of the modules.
681 const Comdat *DstC = &DstCI->second;
682 Comdat::SelectionKind DSK = DstC->getSelectionKind();
683 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
687 bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
688 const GlobalValue &Dest,
689 const GlobalValue &Src) {
690 bool SrcIsDeclaration = Src.isDeclarationForLinker();
691 bool DestIsDeclaration = Dest.isDeclarationForLinker();
693 // FIXME: Make datalayout mandatory and just use getDataLayout().
694 DataLayout DL(Dest.getParent());
696 if (SrcIsDeclaration) {
697 // If Src is external or if both Src & Dest are external.. Just link the
698 // external globals, we aren't adding anything.
699 if (Src.hasDLLImportStorageClass()) {
700 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
701 LinkFromSrc = DestIsDeclaration;
704 // If the Dest is weak, use the source linkage.
705 LinkFromSrc = Dest.hasExternalWeakLinkage();
709 if (DestIsDeclaration) {
710 // If Dest is external but Src is not:
715 if (Src.hasCommonLinkage()) {
716 if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
721 if (!Dest.hasCommonLinkage()) {
726 uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
727 uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
728 LinkFromSrc = SrcSize > DestSize;
732 if (Src.isWeakForLinker()) {
733 assert(!Dest.hasExternalWeakLinkage());
734 assert(!Dest.hasAvailableExternallyLinkage());
736 if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
745 if (Dest.isWeakForLinker()) {
746 assert(Src.hasExternalLinkage());
751 assert(!Src.hasExternalWeakLinkage());
752 assert(!Dest.hasExternalWeakLinkage());
753 assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
754 "Unexpected linkage type!");
755 return emitError("Linking globals named '" + Src.getName() +
756 "': symbol multiply defined!");
759 /// This analyzes the two global values and determines what the result will look
760 /// like in the destination module. In particular, it computes the resultant
761 /// linkage type and visibility, computes whether the global in the source
762 /// should be copied over to the destination (replacing the existing one), and
763 /// computes whether this linkage is an error or not.
764 bool ModuleLinker::getLinkageResult(GlobalValue *Dest, const GlobalValue *Src,
765 GlobalValue::LinkageTypes <,
766 GlobalValue::VisibilityTypes &Vis,
768 assert(Dest && "Must have two globals being queried");
769 assert(!Src->hasLocalLinkage() &&
770 "If Src has internal linkage, Dest shouldn't be set!");
772 if (shouldLinkFromSource(LinkFromSrc, *Dest, *Src))
776 LT = Src->getLinkage();
778 LT = Dest->getLinkage();
780 // Compute the visibility. We follow the rules in the System V Application
782 assert(!GlobalValue::isLocalLinkage(LT) &&
783 "Symbols with local linkage should not be merged");
784 Vis = isLessConstraining(Src->getVisibility(), Dest->getVisibility()) ?
785 Dest->getVisibility() : Src->getVisibility();
789 /// Loop over all of the linked values to compute type mappings. For example,
790 /// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct
791 /// types 'Foo' but one got renamed when the module was loaded into the same
793 void ModuleLinker::computeTypeMapping() {
794 // Incorporate globals.
795 for (Module::global_iterator I = SrcM->global_begin(),
796 E = SrcM->global_end(); I != E; ++I) {
797 GlobalValue *DGV = getLinkedToGlobal(I);
800 if (!DGV->hasAppendingLinkage() || !I->hasAppendingLinkage()) {
801 TypeMap.addTypeMapping(DGV->getType(), I->getType());
805 // Unify the element type of appending arrays.
806 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
807 ArrayType *SAT = cast<ArrayType>(I->getType()->getElementType());
808 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
811 // Incorporate functions.
812 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I) {
813 if (GlobalValue *DGV = getLinkedToGlobal(I))
814 TypeMap.addTypeMapping(DGV->getType(), I->getType());
817 // Incorporate types by name, scanning all the types in the source module.
818 // At this point, the destination module may have a type "%foo = { i32 }" for
819 // example. When the source module got loaded into the same LLVMContext, if
820 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
821 TypeFinder SrcStructTypes;
822 SrcStructTypes.run(*SrcM, true);
823 SmallPtrSet<StructType*, 32> SrcStructTypesSet(SrcStructTypes.begin(),
824 SrcStructTypes.end());
826 for (unsigned i = 0, e = SrcStructTypes.size(); i != e; ++i) {
827 StructType *ST = SrcStructTypes[i];
828 if (!ST->hasName()) continue;
830 // Check to see if there is a dot in the name followed by a digit.
831 size_t DotPos = ST->getName().rfind('.');
832 if (DotPos == 0 || DotPos == StringRef::npos ||
833 ST->getName().back() == '.' ||
834 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos+1])))
837 // Check to see if the destination module has a struct with the prefix name.
838 if (StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos)))
839 // Don't use it if this actually came from the source module. They're in
840 // the same LLVMContext after all. Also don't use it unless the type is
841 // actually used in the destination module. This can happen in situations
846 // %Z = type { %A } %B = type { %C.1 }
847 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
848 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
849 // %C = type { i8* } %B.3 = type { %C.1 }
851 // When we link Module B with Module A, the '%B' in Module B is
852 // used. However, that would then use '%C.1'. But when we process '%C.1',
853 // we prefer to take the '%C' version. So we are then left with both
854 // '%C.1' and '%C' being used for the same types. This leads to some
855 // variables using one type and some using the other.
856 if (!SrcStructTypesSet.count(DST) && TypeMap.DstStructTypesSet.count(DST))
857 TypeMap.addTypeMapping(DST, ST);
860 // Don't bother incorporating aliases, they aren't generally typed well.
862 // Now that we have discovered all of the type equivalences, get a body for
863 // any 'opaque' types in the dest module that are now resolved.
864 TypeMap.linkDefinedTypeBodies();
867 static void upgradeGlobalArray(GlobalVariable *GV) {
868 ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
869 StructType *OldTy = cast<StructType>(ATy->getElementType());
870 assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
872 // Get the upgraded 3 element type.
873 PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
874 Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
876 StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
878 // Build new constants with a null third field filled in.
879 Constant *OldInitC = GV->getInitializer();
880 ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
881 if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
882 // Invalid initializer; give up.
884 std::vector<Constant *> Initializers;
885 if (OldInit && OldInit->getNumOperands()) {
886 Value *Null = Constant::getNullValue(VoidPtrTy);
887 for (Use &U : OldInit->operands()) {
888 ConstantStruct *Init = cast<ConstantStruct>(U.get());
889 Initializers.push_back(ConstantStruct::get(
890 NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
893 assert(Initializers.size() == ATy->getNumElements() &&
894 "Failed to copy all array elements");
896 // Replace the old GV with a new one.
897 ATy = ArrayType::get(NewTy, Initializers.size());
898 Constant *NewInit = ConstantArray::get(ATy, Initializers);
899 GlobalVariable *NewGV = new GlobalVariable(
900 *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
901 GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
902 GV->isExternallyInitialized());
903 NewGV->copyAttributesFrom(GV);
905 assert(GV->use_empty() && "program cannot use initializer list");
906 GV->eraseFromParent();
909 void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
910 // Look for the global arrays.
911 auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM->getNamedValue(Name));
914 auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM->getNamedValue(Name));
918 // Check if the types already match.
919 auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
921 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
925 // Grab the element types. We can only upgrade an array of a two-field
926 // struct. Only bother if the other one has three-fields.
927 auto *DstEltTy = cast<StructType>(DstTy->getElementType());
928 auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
929 if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
930 upgradeGlobalArray(DstGV);
933 if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
934 upgradeGlobalArray(SrcGV);
936 // We can't upgrade any other differences.
939 void ModuleLinker::upgradeMismatchedGlobals() {
940 upgradeMismatchedGlobalArray("llvm.global_ctors");
941 upgradeMismatchedGlobalArray("llvm.global_dtors");
944 /// If there were any appending global variables, link them together now.
945 /// Return true on error.
946 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
947 GlobalVariable *SrcGV) {
949 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
950 return emitError("Linking globals named '" + SrcGV->getName() +
951 "': can only link appending global with another appending global!");
953 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
955 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
956 Type *EltTy = DstTy->getElementType();
958 // Check to see that they two arrays agree on type.
959 if (EltTy != SrcTy->getElementType())
960 return emitError("Appending variables with different element types!");
961 if (DstGV->isConstant() != SrcGV->isConstant())
962 return emitError("Appending variables linked with different const'ness!");
964 if (DstGV->getAlignment() != SrcGV->getAlignment())
966 "Appending variables with different alignment need to be linked!");
968 if (DstGV->getVisibility() != SrcGV->getVisibility())
970 "Appending variables with different visibility need to be linked!");
972 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
974 "Appending variables with different unnamed_addr need to be linked!");
976 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
978 "Appending variables with different section name need to be linked!");
980 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements();
981 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
983 // Create the new global variable.
985 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(),
986 DstGV->getLinkage(), /*init*/nullptr, /*name*/"", DstGV,
987 DstGV->getThreadLocalMode(),
988 DstGV->getType()->getAddressSpace());
990 // Propagate alignment, visibility and section info.
991 copyGVAttributes(NG, DstGV);
993 AppendingVarInfo AVI;
995 AVI.DstInit = DstGV->getInitializer();
996 AVI.SrcInit = SrcGV->getInitializer();
997 AppendingVars.push_back(AVI);
999 // Replace any uses of the two global variables with uses of the new
1001 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
1003 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
1004 DstGV->eraseFromParent();
1006 // Track the source variable so we don't try to link it.
1007 DoNotLinkFromSource.insert(SrcGV);
1012 /// Loop through the global variables in the src module and merge them into the
1014 bool ModuleLinker::linkGlobalProto(GlobalVariable *SGV) {
1015 GlobalValue *DGV = getLinkedToGlobal(SGV);
1016 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
1017 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
1018 unsigned Alignment = SGV->getAlignment();
1020 bool LinkFromSrc = false;
1021 Comdat *DC = nullptr;
1022 if (const Comdat *SC = SGV->getComdat()) {
1023 Comdat::SelectionKind SK;
1024 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1025 DC = DstM->getOrInsertComdat(SC->getName());
1026 DC->setSelectionKind(SK);
1031 // Concatenation of appending linkage variables is magic and handled later.
1032 if (DGV->hasAppendingLinkage() || SGV->hasAppendingLinkage())
1033 return linkAppendingVarProto(cast<GlobalVariable>(DGV), SGV);
1035 // Determine whether linkage of these two globals follows the source
1036 // module's definition or the destination module's definition.
1037 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
1038 GlobalValue::VisibilityTypes NV;
1039 if (getLinkageResult(DGV, SGV, NewLinkage, NV, LinkFromSrc))
1042 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1043 if (DGV->hasCommonLinkage() && SGV->hasCommonLinkage())
1044 Alignment = std::max(Alignment, DGV->getAlignment());
1045 else if (!LinkFromSrc)
1046 Alignment = DGV->getAlignment();
1048 // If we're not linking from the source, then keep the definition that we
1051 // Special case for const propagation.
1052 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) {
1053 DGVar->setAlignment(Alignment);
1055 if (DGVar->isDeclaration() && !SGV->isConstant())
1056 DGVar->setConstant(false);
1059 // Set calculated linkage, visibility and unnamed_addr.
1060 DGV->setLinkage(NewLinkage);
1061 DGV->setVisibility(*NewVisibility);
1062 DGV->setUnnamedAddr(HasUnnamedAddr);
1067 // Make sure to remember this mapping.
1068 ValueMap[SGV] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGV->getType()));
1070 // Track the source global so that we don't attempt to copy it over when
1071 // processing global initializers.
1072 DoNotLinkFromSource.insert(SGV);
1078 // If the Comdat this variable was inside of wasn't selected, skip it.
1079 if (DC && !DGV && !LinkFromSrc) {
1080 DoNotLinkFromSource.insert(SGV);
1084 // No linking to be performed or linking from the source: simply create an
1085 // identical version of the symbol over in the dest module... the
1086 // initializer will be filled in later by LinkGlobalInits.
1087 GlobalVariable *NewDGV =
1088 new GlobalVariable(*DstM, TypeMap.get(SGV->getType()->getElementType()),
1089 SGV->isConstant(), SGV->getLinkage(), /*init*/nullptr,
1090 SGV->getName(), /*insertbefore*/nullptr,
1091 SGV->getThreadLocalMode(),
1092 SGV->getType()->getAddressSpace());
1093 // Propagate alignment, visibility and section info.
1094 copyGVAttributes(NewDGV, SGV);
1095 NewDGV->setAlignment(Alignment);
1097 NewDGV->setVisibility(*NewVisibility);
1098 NewDGV->setUnnamedAddr(HasUnnamedAddr);
1101 NewDGV->setComdat(DC);
1104 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV, DGV->getType()));
1105 DGV->eraseFromParent();
1108 // Make sure to remember this mapping.
1109 ValueMap[SGV] = NewDGV;
1113 /// Link the function in the source module into the destination module if
1114 /// needed, setting up mapping information.
1115 bool ModuleLinker::linkFunctionProto(Function *SF) {
1116 GlobalValue *DGV = getLinkedToGlobal(SF);
1117 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
1118 bool HasUnnamedAddr = SF->hasUnnamedAddr();
1120 bool LinkFromSrc = false;
1121 Comdat *DC = nullptr;
1122 if (const Comdat *SC = SF->getComdat()) {
1123 Comdat::SelectionKind SK;
1124 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1125 DC = DstM->getOrInsertComdat(SC->getName());
1126 DC->setSelectionKind(SK);
1131 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
1132 GlobalValue::VisibilityTypes NV;
1133 if (getLinkageResult(DGV, SF, NewLinkage, NV, LinkFromSrc))
1136 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1139 // Set calculated linkage
1140 DGV->setLinkage(NewLinkage);
1141 DGV->setVisibility(*NewVisibility);
1142 DGV->setUnnamedAddr(HasUnnamedAddr);
1147 // Make sure to remember this mapping.
1148 ValueMap[SF] = ConstantExpr::getBitCast(DGV, TypeMap.get(SF->getType()));
1150 // Track the function from the source module so we don't attempt to remap
1152 DoNotLinkFromSource.insert(SF);
1158 // If the function is to be lazily linked, don't create it just yet.
1159 // The ValueMaterializerTy will deal with creating it if it's used.
1160 if (!DGV && (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() ||
1161 SF->hasAvailableExternallyLinkage())) {
1162 DoNotLinkFromSource.insert(SF);
1166 // If the Comdat this function was inside of wasn't selected, skip it.
1167 if (DC && !DGV && !LinkFromSrc) {
1168 DoNotLinkFromSource.insert(SF);
1172 // If there is no linkage to be performed or we are linking from the source,
1174 Function *NewDF = Function::Create(TypeMap.get(SF->getFunctionType()),
1175 SF->getLinkage(), SF->getName(), DstM);
1176 copyGVAttributes(NewDF, SF);
1178 NewDF->setVisibility(*NewVisibility);
1179 NewDF->setUnnamedAddr(HasUnnamedAddr);
1182 NewDF->setComdat(DC);
1185 // Any uses of DF need to change to NewDF, with cast.
1186 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, DGV->getType()));
1187 DGV->eraseFromParent();
1190 ValueMap[SF] = NewDF;
1194 /// Set up prototypes for any aliases that come over from the source module.
1195 bool ModuleLinker::linkAliasProto(GlobalAlias *SGA) {
1196 GlobalValue *DGV = getLinkedToGlobal(SGA);
1197 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
1198 bool HasUnnamedAddr = SGA->hasUnnamedAddr();
1200 bool LinkFromSrc = false;
1201 Comdat *DC = nullptr;
1202 if (const Comdat *SC = SGA->getComdat()) {
1203 Comdat::SelectionKind SK;
1204 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1205 DC = DstM->getOrInsertComdat(SC->getName());
1206 DC->setSelectionKind(SK);
1211 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
1212 GlobalValue::VisibilityTypes NV;
1213 if (getLinkageResult(DGV, SGA, NewLinkage, NV, LinkFromSrc))
1216 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1219 // Set calculated linkage.
1220 DGV->setLinkage(NewLinkage);
1221 DGV->setVisibility(*NewVisibility);
1222 DGV->setUnnamedAddr(HasUnnamedAddr);
1227 // Make sure to remember this mapping.
1228 ValueMap[SGA] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGA->getType()));
1230 // Track the alias from the source module so we don't attempt to remap it.
1231 DoNotLinkFromSource.insert(SGA);
1237 // If the Comdat this alias was inside of wasn't selected, skip it.
1238 if (DC && !DGV && !LinkFromSrc) {
1239 DoNotLinkFromSource.insert(SGA);
1243 // If there is no linkage to be performed or we're linking from the source,
1245 auto *PTy = cast<PointerType>(TypeMap.get(SGA->getType()));
1247 GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(),
1248 SGA->getLinkage(), SGA->getName(), DstM);
1249 copyGVAttributes(NewDA, SGA);
1251 NewDA->setVisibility(*NewVisibility);
1252 NewDA->setUnnamedAddr(HasUnnamedAddr);
1255 // Any uses of DGV need to change to NewDA, with cast.
1256 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDA, DGV->getType()));
1257 DGV->eraseFromParent();
1260 ValueMap[SGA] = NewDA;
1264 static void getArrayElements(Constant *C, SmallVectorImpl<Constant*> &Dest) {
1265 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1267 for (unsigned i = 0; i != NumElements; ++i)
1268 Dest.push_back(C->getAggregateElement(i));
1271 void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) {
1272 // Merge the initializer.
1273 SmallVector<Constant *, 16> DstElements;
1274 getArrayElements(AVI.DstInit, DstElements);
1276 SmallVector<Constant *, 16> SrcElements;
1277 getArrayElements(AVI.SrcInit, SrcElements);
1279 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
1281 StringRef Name = AVI.NewGV->getName();
1282 bool IsNewStructor =
1283 (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
1284 cast<StructType>(NewType->getElementType())->getNumElements() == 3;
1286 for (auto *V : SrcElements) {
1287 if (IsNewStructor) {
1288 Constant *Key = V->getAggregateElement(2);
1289 if (DoNotLinkFromSource.count(Key))
1292 DstElements.push_back(
1293 MapValue(V, ValueMap, RF_None, &TypeMap, &ValMaterializer));
1295 if (IsNewStructor) {
1296 NewType = ArrayType::get(NewType->getElementType(), DstElements.size());
1297 AVI.NewGV->mutateType(PointerType::get(NewType, 0));
1300 AVI.NewGV->setInitializer(ConstantArray::get(NewType, DstElements));
1303 /// Update the initializers in the Dest module now that all globals that may be
1304 /// referenced are in Dest.
1305 void ModuleLinker::linkGlobalInits() {
1306 // Loop over all of the globals in the src module, mapping them over as we go
1307 for (Module::const_global_iterator I = SrcM->global_begin(),
1308 E = SrcM->global_end(); I != E; ++I) {
1310 // Only process initialized GV's or ones not already in dest.
1311 if (!I->hasInitializer() || DoNotLinkFromSource.count(I)) continue;
1313 // Grab destination global variable.
1314 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[I]);
1315 // Figure out what the initializer looks like in the dest module.
1316 DGV->setInitializer(MapValue(I->getInitializer(), ValueMap,
1317 RF_None, &TypeMap, &ValMaterializer));
1321 /// Copy the source function over into the dest function and fix up references
1322 /// to values. At this point we know that Dest is an external function, and
1323 /// that Src is not.
1324 void ModuleLinker::linkFunctionBody(Function *Dst, Function *Src) {
1325 assert(Src && Dst && Dst->isDeclaration() && !Src->isDeclaration());
1327 // Go through and convert function arguments over, remembering the mapping.
1328 Function::arg_iterator DI = Dst->arg_begin();
1329 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1330 I != E; ++I, ++DI) {
1331 DI->setName(I->getName()); // Copy the name over.
1333 // Add a mapping to our mapping.
1337 // Splice the body of the source function into the dest function.
1338 Dst->getBasicBlockList().splice(Dst->end(), Src->getBasicBlockList());
1340 // At this point, all of the instructions and values of the function are now
1341 // copied over. The only problem is that they are still referencing values in
1342 // the Source function as operands. Loop through all of the operands of the
1343 // functions and patch them up to point to the local versions.
1344 for (Function::iterator BB = Dst->begin(), BE = Dst->end(); BB != BE; ++BB)
1345 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
1346 RemapInstruction(I, ValueMap, RF_IgnoreMissingEntries, &TypeMap,
1349 // There is no need to map the arguments anymore.
1350 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1356 /// Insert all of the aliases in Src into the Dest module.
1357 void ModuleLinker::linkAliasBodies() {
1358 for (Module::alias_iterator I = SrcM->alias_begin(), E = SrcM->alias_end();
1360 if (DoNotLinkFromSource.count(I))
1362 if (Constant *Aliasee = I->getAliasee()) {
1363 GlobalAlias *DA = cast<GlobalAlias>(ValueMap[I]);
1365 MapValue(Aliasee, ValueMap, RF_None, &TypeMap, &ValMaterializer);
1366 DA->setAliasee(Val);
1371 /// Insert all of the named MDNodes in Src into the Dest module.
1372 void ModuleLinker::linkNamedMDNodes() {
1373 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1374 for (Module::const_named_metadata_iterator I = SrcM->named_metadata_begin(),
1375 E = SrcM->named_metadata_end(); I != E; ++I) {
1376 // Don't link module flags here. Do them separately.
1377 if (&*I == SrcModFlags) continue;
1378 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(I->getName());
1379 // Add Src elements into Dest node.
1380 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
1381 DestNMD->addOperand(MapValue(I->getOperand(i), ValueMap,
1382 RF_None, &TypeMap, &ValMaterializer));
1386 /// Merge the linker flags in Src into the Dest module.
1387 bool ModuleLinker::linkModuleFlagsMetadata() {
1388 // If the source module has no module flags, we are done.
1389 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1390 if (!SrcModFlags) return false;
1392 // If the destination module doesn't have module flags yet, then just copy
1393 // over the source module's flags.
1394 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
1395 if (DstModFlags->getNumOperands() == 0) {
1396 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1397 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1402 // First build a map of the existing module flags and requirements.
1403 DenseMap<MDString*, MDNode*> Flags;
1404 SmallSetVector<MDNode*, 16> Requirements;
1405 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1406 MDNode *Op = DstModFlags->getOperand(I);
1407 ConstantInt *Behavior = cast<ConstantInt>(Op->getOperand(0));
1408 MDString *ID = cast<MDString>(Op->getOperand(1));
1410 if (Behavior->getZExtValue() == Module::Require) {
1411 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1417 // Merge in the flags from the source module, and also collect its set of
1419 bool HasErr = false;
1420 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1421 MDNode *SrcOp = SrcModFlags->getOperand(I);
1422 ConstantInt *SrcBehavior = cast<ConstantInt>(SrcOp->getOperand(0));
1423 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1424 MDNode *DstOp = Flags.lookup(ID);
1425 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1427 // If this is a requirement, add it and continue.
1428 if (SrcBehaviorValue == Module::Require) {
1429 // If the destination module does not already have this requirement, add
1431 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1432 DstModFlags->addOperand(SrcOp);
1437 // If there is no existing flag with this ID, just add it.
1440 DstModFlags->addOperand(SrcOp);
1444 // Otherwise, perform a merge.
1445 ConstantInt *DstBehavior = cast<ConstantInt>(DstOp->getOperand(0));
1446 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1448 // If either flag has override behavior, handle it first.
1449 if (DstBehaviorValue == Module::Override) {
1450 // Diagnose inconsistent flags which both have override behavior.
1451 if (SrcBehaviorValue == Module::Override &&
1452 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1453 HasErr |= emitError("linking module flags '" + ID->getString() +
1454 "': IDs have conflicting override values");
1457 } else if (SrcBehaviorValue == Module::Override) {
1458 // Update the destination flag to that of the source.
1459 DstOp->replaceOperandWith(0, SrcBehavior);
1460 DstOp->replaceOperandWith(2, SrcOp->getOperand(2));
1464 // Diagnose inconsistent merge behavior types.
1465 if (SrcBehaviorValue != DstBehaviorValue) {
1466 HasErr |= emitError("linking module flags '" + ID->getString() +
1467 "': IDs have conflicting behaviors");
1471 // Perform the merge for standard behavior types.
1472 switch (SrcBehaviorValue) {
1473 case Module::Require:
1474 case Module::Override: llvm_unreachable("not possible");
1475 case Module::Error: {
1476 // Emit an error if the values differ.
1477 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1478 HasErr |= emitError("linking module flags '" + ID->getString() +
1479 "': IDs have conflicting values");
1483 case Module::Warning: {
1484 // Emit a warning if the values differ.
1485 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1486 emitWarning("linking module flags '" + ID->getString() +
1487 "': IDs have conflicting values");
1491 case Module::Append: {
1492 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1493 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1494 unsigned NumOps = DstValue->getNumOperands() + SrcValue->getNumOperands();
1495 Value **VP, **Values = VP = new Value*[NumOps];
1496 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i, ++VP)
1497 *VP = DstValue->getOperand(i);
1498 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i, ++VP)
1499 *VP = SrcValue->getOperand(i);
1500 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1501 ArrayRef<Value*>(Values,
1506 case Module::AppendUnique: {
1507 SmallSetVector<Value*, 16> Elts;
1508 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1509 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1510 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i)
1511 Elts.insert(DstValue->getOperand(i));
1512 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i)
1513 Elts.insert(SrcValue->getOperand(i));
1514 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1515 ArrayRef<Value*>(Elts.begin(),
1522 // Check all of the requirements.
1523 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1524 MDNode *Requirement = Requirements[I];
1525 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1526 Value *ReqValue = Requirement->getOperand(1);
1528 MDNode *Op = Flags[Flag];
1529 if (!Op || Op->getOperand(2) != ReqValue) {
1530 HasErr |= emitError("linking module flags '" + Flag->getString() +
1531 "': does not have the required value");
1539 bool ModuleLinker::run() {
1540 assert(DstM && "Null destination module");
1541 assert(SrcM && "Null source module");
1543 // Inherit the target data from the source module if the destination module
1544 // doesn't have one already.
1545 if (!DstM->getDataLayout() && SrcM->getDataLayout())
1546 DstM->setDataLayout(SrcM->getDataLayout());
1548 // Copy the target triple from the source to dest if the dest's is empty.
1549 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
1550 DstM->setTargetTriple(SrcM->getTargetTriple());
1552 if (SrcM->getDataLayout() && DstM->getDataLayout() &&
1553 *SrcM->getDataLayout() != *DstM->getDataLayout()) {
1554 emitWarning("Linking two modules of different data layouts: '" +
1555 SrcM->getModuleIdentifier() + "' is '" +
1556 SrcM->getDataLayoutStr() + "' whereas '" +
1557 DstM->getModuleIdentifier() + "' is '" +
1558 DstM->getDataLayoutStr() + "'\n");
1560 if (!SrcM->getTargetTriple().empty() &&
1561 DstM->getTargetTriple() != SrcM->getTargetTriple()) {
1562 emitWarning("Linking two modules of different target triples: " +
1563 SrcM->getModuleIdentifier() + "' is '" +
1564 SrcM->getTargetTriple() + "' whereas '" +
1565 DstM->getModuleIdentifier() + "' is '" +
1566 DstM->getTargetTriple() + "'\n");
1569 // Append the module inline asm string.
1570 if (!SrcM->getModuleInlineAsm().empty()) {
1571 if (DstM->getModuleInlineAsm().empty())
1572 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
1574 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
1575 SrcM->getModuleInlineAsm());
1578 // Loop over all of the linked values to compute type mappings.
1579 computeTypeMapping();
1581 ComdatsChosen.clear();
1582 for (const StringMapEntry<llvm::Comdat> &SMEC : SrcM->getComdatSymbolTable()) {
1583 const Comdat &C = SMEC.getValue();
1584 if (ComdatsChosen.count(&C))
1586 Comdat::SelectionKind SK;
1588 if (getComdatResult(&C, SK, LinkFromSrc))
1590 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1593 // Upgrade mismatched global arrays.
1594 upgradeMismatchedGlobals();
1596 // Insert all of the globals in src into the DstM module... without linking
1597 // initializers (which could refer to functions not yet mapped over).
1598 for (Module::global_iterator I = SrcM->global_begin(),
1599 E = SrcM->global_end(); I != E; ++I)
1600 if (linkGlobalProto(I))
1603 // Link the functions together between the two modules, without doing function
1604 // bodies... this just adds external function prototypes to the DstM
1605 // function... We do this so that when we begin processing function bodies,
1606 // all of the global values that may be referenced are available in our
1608 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I)
1609 if (linkFunctionProto(I))
1612 // If there were any aliases, link them now.
1613 for (Module::alias_iterator I = SrcM->alias_begin(),
1614 E = SrcM->alias_end(); I != E; ++I)
1615 if (linkAliasProto(I))
1618 for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i)
1619 linkAppendingVarInit(AppendingVars[i]);
1621 // Link in the function bodies that are defined in the source module into
1623 for (Module::iterator SF = SrcM->begin(), E = SrcM->end(); SF != E; ++SF) {
1624 // Skip if not linking from source.
1625 if (DoNotLinkFromSource.count(SF)) continue;
1627 Function *DF = cast<Function>(ValueMap[SF]);
1628 if (SF->hasPrefixData()) {
1629 // Link in the prefix data.
1630 DF->setPrefixData(MapValue(
1631 SF->getPrefixData(), ValueMap, RF_None, &TypeMap, &ValMaterializer));
1634 // Materialize if needed.
1635 if (SF->isMaterializable()) {
1636 if (std::error_code EC = SF->materialize())
1637 return emitError(EC.message());
1640 // Skip if no body (function is external).
1641 if (SF->isDeclaration())
1644 linkFunctionBody(DF, SF);
1645 SF->Dematerialize();
1648 // Resolve all uses of aliases with aliasees.
1651 // Remap all of the named MDNodes in Src into the DstM module. We do this
1652 // after linking GlobalValues so that MDNodes that reference GlobalValues
1653 // are properly remapped.
1656 // Merge the module flags into the DstM module.
1657 if (linkModuleFlagsMetadata())
1660 // Update the initializers in the DstM module now that all globals that may
1661 // be referenced are in DstM.
1664 // Process vector of lazily linked in functions.
1665 bool LinkedInAnyFunctions;
1667 LinkedInAnyFunctions = false;
1669 for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(),
1670 E = LazilyLinkFunctions.end(); I != E; ++I) {
1675 Function *DF = cast<Function>(ValueMap[SF]);
1676 if (SF->hasPrefixData()) {
1677 // Link in the prefix data.
1678 DF->setPrefixData(MapValue(SF->getPrefixData(),
1685 // Materialize if needed.
1686 if (SF->isMaterializable()) {
1687 if (std::error_code EC = SF->materialize())
1688 return emitError(EC.message());
1691 // Skip if no body (function is external).
1692 if (SF->isDeclaration())
1695 // Erase from vector *before* the function body is linked - linkFunctionBody could
1697 LazilyLinkFunctions.erase(I);
1699 // Link in function body.
1700 linkFunctionBody(DF, SF);
1701 SF->Dematerialize();
1703 // Set flag to indicate we may have more functions to lazily link in
1704 // since we linked in a function.
1705 LinkedInAnyFunctions = true;
1708 } while (LinkedInAnyFunctions);
1710 // Now that all of the types from the source are used, resolve any structs
1711 // copied over to the dest that didn't exist there.
1712 TypeMap.linkDefinedTypeBodies();
1717 Linker::Linker(Module *M, DiagnosticHandlerFunction DiagnosticHandler)
1718 : Composite(M), DiagnosticHandler(DiagnosticHandler) {}
1720 Linker::Linker(Module *M)
1721 : Composite(M), DiagnosticHandler([this](const DiagnosticInfo &DI) {
1722 Composite->getContext().diagnose(DI);
1724 TypeFinder StructTypes;
1725 StructTypes.run(*M, true);
1726 IdentifiedStructTypes.insert(StructTypes.begin(), StructTypes.end());
1732 void Linker::deleteModule() {
1734 Composite = nullptr;
1737 bool Linker::linkInModule(Module *Src) {
1738 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,
1740 return TheLinker.run();
1743 //===----------------------------------------------------------------------===//
1744 // LinkModules entrypoint.
1745 //===----------------------------------------------------------------------===//
1747 /// This function links two modules together, with the resulting Dest module
1748 /// modified to be the composite of the two input modules. If an error occurs,
1749 /// true is returned and ErrorMsg (if not null) is set to indicate the problem.
1750 /// Upon failure, the Dest module could be in a modified state, and shouldn't be
1751 /// relied on to be consistent.
1752 bool Linker::LinkModules(Module *Dest, Module *Src,
1753 DiagnosticHandlerFunction DiagnosticHandler) {
1754 Linker L(Dest, DiagnosticHandler);
1755 return L.linkInModule(Src);
1758 bool Linker::LinkModules(Module *Dest, Module *Src) {
1760 return L.linkInModule(Src);
1763 //===----------------------------------------------------------------------===//
1765 //===----------------------------------------------------------------------===//
1767 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
1768 LLVMLinkerMode Mode, char **OutMessages) {
1769 Module *D = unwrap(Dest);
1770 std::string Message;
1771 raw_string_ostream Stream(Message);
1772 DiagnosticPrinterRawOStream DP(Stream);
1774 LLVMBool Result = Linker::LinkModules(
1775 D, unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); });
1777 if (OutMessages && Result)
1778 *OutMessages = strdup(Message.c_str());