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 unsigned Mode; // Mode to treat source module.
415 // Set of items not to link in from source.
416 SmallPtrSet<const Value*, 16> DoNotLinkFromSource;
418 // Vector of functions to lazily link in.
419 std::vector<Function*> LazilyLinkFunctions;
421 Linker::DiagnosticHandlerFunction DiagnosticHandler;
424 ModuleLinker(Module *dstM, TypeSet &Set, Module *srcM, unsigned mode,
425 Linker::DiagnosticHandlerFunction DiagnosticHandler)
426 : DstM(dstM), SrcM(srcM), TypeMap(Set),
427 ValMaterializer(TypeMap, DstM, LazilyLinkFunctions), Mode(mode),
428 DiagnosticHandler(DiagnosticHandler) {}
433 bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
434 const GlobalValue &Src);
436 /// Helper method for setting a message and returning an error code.
437 bool emitError(const Twine &Message) {
438 DiagnosticHandler(LinkDiagnosticInfo(DS_Error, Message));
442 void emitWarning(const Twine &Message) {
443 DiagnosticHandler(LinkDiagnosticInfo(DS_Warning, Message));
446 bool getComdatLeader(Module *M, StringRef ComdatName,
447 const GlobalVariable *&GVar);
448 bool computeResultingSelectionKind(StringRef ComdatName,
449 Comdat::SelectionKind Src,
450 Comdat::SelectionKind Dst,
451 Comdat::SelectionKind &Result,
453 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
455 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
458 /// This analyzes the two global values and determines what the result will
459 /// look like in the destination module.
460 bool getLinkageResult(GlobalValue *Dest, const GlobalValue *Src,
461 GlobalValue::LinkageTypes <,
462 GlobalValue::VisibilityTypes &Vis,
465 /// Given a global in the source module, return the global in the
466 /// destination module that is being linked to, if any.
467 GlobalValue *getLinkedToGlobal(GlobalValue *SrcGV) {
468 // If the source has no name it can't link. If it has local linkage,
469 // there is no name match-up going on.
470 if (!SrcGV->hasName() || SrcGV->hasLocalLinkage())
473 // Otherwise see if we have a match in the destination module's symtab.
474 GlobalValue *DGV = DstM->getNamedValue(SrcGV->getName());
475 if (!DGV) return nullptr;
477 // If we found a global with the same name in the dest module, but it has
478 // internal linkage, we are really not doing any linkage here.
479 if (DGV->hasLocalLinkage())
482 // Otherwise, we do in fact link to the destination global.
486 void computeTypeMapping();
488 void upgradeMismatchedGlobalArray(StringRef Name);
489 void upgradeMismatchedGlobals();
491 bool linkAppendingVarProto(GlobalVariable *DstGV, GlobalVariable *SrcGV);
492 bool linkGlobalProto(GlobalVariable *SrcGV);
493 bool linkFunctionProto(Function *SrcF);
494 bool linkAliasProto(GlobalAlias *SrcA);
495 bool linkModuleFlagsMetadata();
497 void linkAppendingVarInit(const AppendingVarInfo &AVI);
498 void linkGlobalInits();
499 void linkFunctionBody(Function *Dst, Function *Src);
500 void linkAliasBodies();
501 void linkNamedMDNodes();
505 /// The LLVM SymbolTable class autorenames globals that conflict in the symbol
506 /// table. This is good for all clients except for us. Go through the trouble
507 /// to force this back.
508 static void forceRenaming(GlobalValue *GV, StringRef Name) {
509 // If the global doesn't force its name or if it already has the right name,
510 // there is nothing for us to do.
511 if (GV->hasLocalLinkage() || GV->getName() == Name)
514 Module *M = GV->getParent();
516 // If there is a conflict, rename the conflict.
517 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
518 GV->takeName(ConflictGV);
519 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
520 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
522 GV->setName(Name); // Force the name back
526 /// copy additional attributes (those not needed to construct a GlobalValue)
527 /// from the SrcGV to the DestGV.
528 static void copyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) {
529 // Use the maximum alignment, rather than just copying the alignment of SrcGV.
530 auto *DestGO = dyn_cast<GlobalObject>(DestGV);
533 Alignment = std::max(DestGO->getAlignment(), SrcGV->getAlignment());
535 DestGV->copyAttributesFrom(SrcGV);
538 DestGO->setAlignment(Alignment);
540 forceRenaming(DestGV, SrcGV->getName());
543 static bool isLessConstraining(GlobalValue::VisibilityTypes a,
544 GlobalValue::VisibilityTypes b) {
545 if (a == GlobalValue::HiddenVisibility)
547 if (b == GlobalValue::HiddenVisibility)
549 if (a == GlobalValue::ProtectedVisibility)
551 if (b == GlobalValue::ProtectedVisibility)
556 Value *ValueMaterializerTy::materializeValueFor(Value *V) {
557 Function *SF = dyn_cast<Function>(V);
561 Function *DF = Function::Create(TypeMap.get(SF->getFunctionType()),
562 SF->getLinkage(), SF->getName(), DstM);
563 copyGVAttributes(DF, SF);
565 if (Comdat *SC = SF->getComdat()) {
566 Comdat *DC = DstM->getOrInsertComdat(SC->getName());
570 LazilyLinkFunctions.push_back(SF);
574 bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName,
575 const GlobalVariable *&GVar) {
576 const GlobalValue *GVal = M->getNamedValue(ComdatName);
577 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
578 GVal = GA->getBaseObject();
580 // We cannot resolve the size of the aliasee yet.
581 return emitError("Linking COMDATs named '" + ComdatName +
582 "': COMDAT key involves incomputable alias size.");
585 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
588 "Linking COMDATs named '" + ComdatName +
589 "': GlobalVariable required for data dependent selection!");
594 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
595 Comdat::SelectionKind Src,
596 Comdat::SelectionKind Dst,
597 Comdat::SelectionKind &Result,
599 // The ability to mix Comdat::SelectionKind::Any with
600 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
601 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
602 Dst == Comdat::SelectionKind::Largest;
603 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
604 Src == Comdat::SelectionKind::Largest;
605 if (DstAnyOrLargest && SrcAnyOrLargest) {
606 if (Dst == Comdat::SelectionKind::Largest ||
607 Src == Comdat::SelectionKind::Largest)
608 Result = Comdat::SelectionKind::Largest;
610 Result = Comdat::SelectionKind::Any;
611 } else if (Src == Dst) {
614 return emitError("Linking COMDATs named '" + ComdatName +
615 "': invalid selection kinds!");
619 case Comdat::SelectionKind::Any:
623 case Comdat::SelectionKind::NoDuplicates:
624 return emitError("Linking COMDATs named '" + ComdatName +
625 "': noduplicates has been violated!");
626 case Comdat::SelectionKind::ExactMatch:
627 case Comdat::SelectionKind::Largest:
628 case Comdat::SelectionKind::SameSize: {
629 const GlobalVariable *DstGV;
630 const GlobalVariable *SrcGV;
631 if (getComdatLeader(DstM, ComdatName, DstGV) ||
632 getComdatLeader(SrcM, ComdatName, SrcGV))
635 const DataLayout *DstDL = DstM->getDataLayout();
636 const DataLayout *SrcDL = SrcM->getDataLayout();
637 if (!DstDL || !SrcDL) {
639 "Linking COMDATs named '" + ComdatName +
640 "': can't do size dependent selection without DataLayout!");
643 DstDL->getTypeAllocSize(DstGV->getType()->getPointerElementType());
645 SrcDL->getTypeAllocSize(SrcGV->getType()->getPointerElementType());
646 if (Result == Comdat::SelectionKind::ExactMatch) {
647 if (SrcGV->getInitializer() != DstGV->getInitializer())
648 return emitError("Linking COMDATs named '" + ComdatName +
649 "': ExactMatch violated!");
651 } else if (Result == Comdat::SelectionKind::Largest) {
652 LinkFromSrc = SrcSize > DstSize;
653 } else if (Result == Comdat::SelectionKind::SameSize) {
654 if (SrcSize != DstSize)
655 return emitError("Linking COMDATs named '" + ComdatName +
656 "': SameSize violated!");
659 llvm_unreachable("unknown selection kind");
668 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
669 Comdat::SelectionKind &Result,
671 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
672 StringRef ComdatName = SrcC->getName();
673 Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable();
674 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
676 if (DstCI == ComdatSymTab.end()) {
677 // Use the comdat if it is only available in one of the modules.
683 const Comdat *DstC = &DstCI->second;
684 Comdat::SelectionKind DSK = DstC->getSelectionKind();
685 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
689 bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
690 const GlobalValue &Dest,
691 const GlobalValue &Src) {
692 bool SrcIsDeclaration = Src.isDeclarationForLinker();
693 bool DestIsDeclaration = Dest.isDeclarationForLinker();
695 // FIXME: Make datalayout mandatory and just use getDataLayout().
696 DataLayout DL(Dest.getParent());
698 if (SrcIsDeclaration) {
699 // If Src is external or if both Src & Dest are external.. Just link the
700 // external globals, we aren't adding anything.
701 if (Src.hasDLLImportStorageClass()) {
702 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
703 LinkFromSrc = DestIsDeclaration;
706 // If the Dest is weak, use the source linkage.
707 LinkFromSrc = Dest.hasExternalWeakLinkage();
711 if (DestIsDeclaration) {
712 // If Dest is external but Src is not:
717 if (Src.hasCommonLinkage()) {
718 if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
723 if (!Dest.hasCommonLinkage()) {
728 uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
729 uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
730 LinkFromSrc = SrcSize > DestSize;
734 if (Src.isWeakForLinker()) {
735 assert(!Dest.hasExternalWeakLinkage());
736 assert(!Dest.hasAvailableExternallyLinkage());
738 if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
747 if (Dest.isWeakForLinker()) {
748 assert(Src.hasExternalLinkage());
753 assert(!Src.hasExternalWeakLinkage());
754 assert(!Dest.hasExternalWeakLinkage());
755 assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
756 "Unexpected linkage type!");
757 return emitError("Linking globals named '" + Src.getName() +
758 "': symbol multiply defined!");
761 /// This analyzes the two global values and determines what the result will look
762 /// like in the destination module. In particular, it computes the resultant
763 /// linkage type and visibility, computes whether the global in the source
764 /// should be copied over to the destination (replacing the existing one), and
765 /// computes whether this linkage is an error or not.
766 bool ModuleLinker::getLinkageResult(GlobalValue *Dest, const GlobalValue *Src,
767 GlobalValue::LinkageTypes <,
768 GlobalValue::VisibilityTypes &Vis,
770 assert(Dest && "Must have two globals being queried");
771 assert(!Src->hasLocalLinkage() &&
772 "If Src has internal linkage, Dest shouldn't be set!");
774 if (shouldLinkFromSource(LinkFromSrc, *Dest, *Src))
778 LT = Src->getLinkage();
780 LT = Dest->getLinkage();
782 // Compute the visibility. We follow the rules in the System V Application
784 assert(!GlobalValue::isLocalLinkage(LT) &&
785 "Symbols with local linkage should not be merged");
786 Vis = isLessConstraining(Src->getVisibility(), Dest->getVisibility()) ?
787 Dest->getVisibility() : Src->getVisibility();
791 /// Loop over all of the linked values to compute type mappings. For example,
792 /// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct
793 /// types 'Foo' but one got renamed when the module was loaded into the same
795 void ModuleLinker::computeTypeMapping() {
796 // Incorporate globals.
797 for (Module::global_iterator I = SrcM->global_begin(),
798 E = SrcM->global_end(); I != E; ++I) {
799 GlobalValue *DGV = getLinkedToGlobal(I);
802 if (!DGV->hasAppendingLinkage() || !I->hasAppendingLinkage()) {
803 TypeMap.addTypeMapping(DGV->getType(), I->getType());
807 // Unify the element type of appending arrays.
808 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
809 ArrayType *SAT = cast<ArrayType>(I->getType()->getElementType());
810 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
813 // Incorporate functions.
814 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I) {
815 if (GlobalValue *DGV = getLinkedToGlobal(I))
816 TypeMap.addTypeMapping(DGV->getType(), I->getType());
819 // Incorporate types by name, scanning all the types in the source module.
820 // At this point, the destination module may have a type "%foo = { i32 }" for
821 // example. When the source module got loaded into the same LLVMContext, if
822 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
823 TypeFinder SrcStructTypes;
824 SrcStructTypes.run(*SrcM, true);
825 SmallPtrSet<StructType*, 32> SrcStructTypesSet(SrcStructTypes.begin(),
826 SrcStructTypes.end());
828 for (unsigned i = 0, e = SrcStructTypes.size(); i != e; ++i) {
829 StructType *ST = SrcStructTypes[i];
830 if (!ST->hasName()) continue;
832 // Check to see if there is a dot in the name followed by a digit.
833 size_t DotPos = ST->getName().rfind('.');
834 if (DotPos == 0 || DotPos == StringRef::npos ||
835 ST->getName().back() == '.' ||
836 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos+1])))
839 // Check to see if the destination module has a struct with the prefix name.
840 if (StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos)))
841 // Don't use it if this actually came from the source module. They're in
842 // the same LLVMContext after all. Also don't use it unless the type is
843 // actually used in the destination module. This can happen in situations
848 // %Z = type { %A } %B = type { %C.1 }
849 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
850 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
851 // %C = type { i8* } %B.3 = type { %C.1 }
853 // When we link Module B with Module A, the '%B' in Module B is
854 // used. However, that would then use '%C.1'. But when we process '%C.1',
855 // we prefer to take the '%C' version. So we are then left with both
856 // '%C.1' and '%C' being used for the same types. This leads to some
857 // variables using one type and some using the other.
858 if (!SrcStructTypesSet.count(DST) && TypeMap.DstStructTypesSet.count(DST))
859 TypeMap.addTypeMapping(DST, ST);
862 // Don't bother incorporating aliases, they aren't generally typed well.
864 // Now that we have discovered all of the type equivalences, get a body for
865 // any 'opaque' types in the dest module that are now resolved.
866 TypeMap.linkDefinedTypeBodies();
869 static void upgradeGlobalArray(GlobalVariable *GV) {
870 ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
871 StructType *OldTy = cast<StructType>(ATy->getElementType());
872 assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
874 // Get the upgraded 3 element type.
875 PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
876 Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
878 StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
880 // Build new constants with a null third field filled in.
881 Constant *OldInitC = GV->getInitializer();
882 ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
883 if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
884 // Invalid initializer; give up.
886 std::vector<Constant *> Initializers;
887 if (OldInit && OldInit->getNumOperands()) {
888 Value *Null = Constant::getNullValue(VoidPtrTy);
889 for (Use &U : OldInit->operands()) {
890 ConstantStruct *Init = cast<ConstantStruct>(U.get());
891 Initializers.push_back(ConstantStruct::get(
892 NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
895 assert(Initializers.size() == ATy->getNumElements() &&
896 "Failed to copy all array elements");
898 // Replace the old GV with a new one.
899 ATy = ArrayType::get(NewTy, Initializers.size());
900 Constant *NewInit = ConstantArray::get(ATy, Initializers);
901 GlobalVariable *NewGV = new GlobalVariable(
902 *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
903 GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
904 GV->isExternallyInitialized());
905 NewGV->copyAttributesFrom(GV);
907 assert(GV->use_empty() && "program cannot use initializer list");
908 GV->eraseFromParent();
911 void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
912 // Look for the global arrays.
913 auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM->getNamedValue(Name));
916 auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM->getNamedValue(Name));
920 // Check if the types already match.
921 auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
923 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
927 // Grab the element types. We can only upgrade an array of a two-field
928 // struct. Only bother if the other one has three-fields.
929 auto *DstEltTy = cast<StructType>(DstTy->getElementType());
930 auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
931 if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
932 upgradeGlobalArray(DstGV);
935 if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
936 upgradeGlobalArray(SrcGV);
938 // We can't upgrade any other differences.
941 void ModuleLinker::upgradeMismatchedGlobals() {
942 upgradeMismatchedGlobalArray("llvm.global_ctors");
943 upgradeMismatchedGlobalArray("llvm.global_dtors");
946 /// If there were any appending global variables, link them together now.
947 /// Return true on error.
948 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
949 GlobalVariable *SrcGV) {
951 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
952 return emitError("Linking globals named '" + SrcGV->getName() +
953 "': can only link appending global with another appending global!");
955 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
957 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
958 Type *EltTy = DstTy->getElementType();
960 // Check to see that they two arrays agree on type.
961 if (EltTy != SrcTy->getElementType())
962 return emitError("Appending variables with different element types!");
963 if (DstGV->isConstant() != SrcGV->isConstant())
964 return emitError("Appending variables linked with different const'ness!");
966 if (DstGV->getAlignment() != SrcGV->getAlignment())
968 "Appending variables with different alignment need to be linked!");
970 if (DstGV->getVisibility() != SrcGV->getVisibility())
972 "Appending variables with different visibility need to be linked!");
974 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
976 "Appending variables with different unnamed_addr need to be linked!");
978 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
980 "Appending variables with different section name need to be linked!");
982 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements();
983 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
985 // Create the new global variable.
987 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(),
988 DstGV->getLinkage(), /*init*/nullptr, /*name*/"", DstGV,
989 DstGV->getThreadLocalMode(),
990 DstGV->getType()->getAddressSpace());
992 // Propagate alignment, visibility and section info.
993 copyGVAttributes(NG, DstGV);
995 AppendingVarInfo AVI;
997 AVI.DstInit = DstGV->getInitializer();
998 AVI.SrcInit = SrcGV->getInitializer();
999 AppendingVars.push_back(AVI);
1001 // Replace any uses of the two global variables with uses of the new
1003 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
1005 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
1006 DstGV->eraseFromParent();
1008 // Track the source variable so we don't try to link it.
1009 DoNotLinkFromSource.insert(SrcGV);
1014 /// Loop through the global variables in the src module and merge them into the
1016 bool ModuleLinker::linkGlobalProto(GlobalVariable *SGV) {
1017 GlobalValue *DGV = getLinkedToGlobal(SGV);
1018 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
1019 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
1020 unsigned Alignment = SGV->getAlignment();
1022 bool LinkFromSrc = false;
1023 Comdat *DC = nullptr;
1024 if (const Comdat *SC = SGV->getComdat()) {
1025 Comdat::SelectionKind SK;
1026 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1027 DC = DstM->getOrInsertComdat(SC->getName());
1028 DC->setSelectionKind(SK);
1033 // Concatenation of appending linkage variables is magic and handled later.
1034 if (DGV->hasAppendingLinkage() || SGV->hasAppendingLinkage())
1035 return linkAppendingVarProto(cast<GlobalVariable>(DGV), SGV);
1037 // Determine whether linkage of these two globals follows the source
1038 // module's definition or the destination module's definition.
1039 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
1040 GlobalValue::VisibilityTypes NV;
1041 if (getLinkageResult(DGV, SGV, NewLinkage, NV, LinkFromSrc))
1044 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1045 if (DGV->hasCommonLinkage() && SGV->hasCommonLinkage())
1046 Alignment = std::max(Alignment, DGV->getAlignment());
1047 else if (!LinkFromSrc)
1048 Alignment = DGV->getAlignment();
1050 // If we're not linking from the source, then keep the definition that we
1053 // Special case for const propagation.
1054 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) {
1055 DGVar->setAlignment(Alignment);
1057 if (DGVar->isDeclaration() && SGV->isConstant() &&
1058 !DGVar->isConstant())
1059 DGVar->setConstant(true);
1062 // Set calculated linkage, visibility and unnamed_addr.
1063 DGV->setLinkage(NewLinkage);
1064 DGV->setVisibility(*NewVisibility);
1065 DGV->setUnnamedAddr(HasUnnamedAddr);
1070 // Make sure to remember this mapping.
1071 ValueMap[SGV] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGV->getType()));
1073 // Track the source global so that we don't attempt to copy it over when
1074 // processing global initializers.
1075 DoNotLinkFromSource.insert(SGV);
1081 // If the Comdat this variable was inside of wasn't selected, skip it.
1082 if (DC && !DGV && !LinkFromSrc) {
1083 DoNotLinkFromSource.insert(SGV);
1087 // No linking to be performed or linking from the source: simply create an
1088 // identical version of the symbol over in the dest module... the
1089 // initializer will be filled in later by LinkGlobalInits.
1090 GlobalVariable *NewDGV =
1091 new GlobalVariable(*DstM, TypeMap.get(SGV->getType()->getElementType()),
1092 SGV->isConstant(), SGV->getLinkage(), /*init*/nullptr,
1093 SGV->getName(), /*insertbefore*/nullptr,
1094 SGV->getThreadLocalMode(),
1095 SGV->getType()->getAddressSpace());
1096 // Propagate alignment, visibility and section info.
1097 copyGVAttributes(NewDGV, SGV);
1098 NewDGV->setAlignment(Alignment);
1100 NewDGV->setVisibility(*NewVisibility);
1101 NewDGV->setUnnamedAddr(HasUnnamedAddr);
1104 NewDGV->setComdat(DC);
1107 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV, DGV->getType()));
1108 DGV->eraseFromParent();
1111 // Make sure to remember this mapping.
1112 ValueMap[SGV] = NewDGV;
1116 /// Link the function in the source module into the destination module if
1117 /// needed, setting up mapping information.
1118 bool ModuleLinker::linkFunctionProto(Function *SF) {
1119 GlobalValue *DGV = getLinkedToGlobal(SF);
1120 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
1121 bool HasUnnamedAddr = SF->hasUnnamedAddr();
1123 bool LinkFromSrc = false;
1124 Comdat *DC = nullptr;
1125 if (const Comdat *SC = SF->getComdat()) {
1126 Comdat::SelectionKind SK;
1127 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1128 DC = DstM->getOrInsertComdat(SC->getName());
1129 DC->setSelectionKind(SK);
1134 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
1135 GlobalValue::VisibilityTypes NV;
1136 if (getLinkageResult(DGV, SF, NewLinkage, NV, LinkFromSrc))
1139 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1142 // Set calculated linkage
1143 DGV->setLinkage(NewLinkage);
1144 DGV->setVisibility(*NewVisibility);
1145 DGV->setUnnamedAddr(HasUnnamedAddr);
1150 // Make sure to remember this mapping.
1151 ValueMap[SF] = ConstantExpr::getBitCast(DGV, TypeMap.get(SF->getType()));
1153 // Track the function from the source module so we don't attempt to remap
1155 DoNotLinkFromSource.insert(SF);
1161 // If the function is to be lazily linked, don't create it just yet.
1162 // The ValueMaterializerTy will deal with creating it if it's used.
1163 if (!DGV && (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() ||
1164 SF->hasAvailableExternallyLinkage())) {
1165 DoNotLinkFromSource.insert(SF);
1169 // If the Comdat this function was inside of wasn't selected, skip it.
1170 if (DC && !DGV && !LinkFromSrc) {
1171 DoNotLinkFromSource.insert(SF);
1175 // If there is no linkage to be performed or we are linking from the source,
1177 Function *NewDF = Function::Create(TypeMap.get(SF->getFunctionType()),
1178 SF->getLinkage(), SF->getName(), DstM);
1179 copyGVAttributes(NewDF, SF);
1181 NewDF->setVisibility(*NewVisibility);
1182 NewDF->setUnnamedAddr(HasUnnamedAddr);
1185 NewDF->setComdat(DC);
1188 // Any uses of DF need to change to NewDF, with cast.
1189 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, DGV->getType()));
1190 DGV->eraseFromParent();
1193 ValueMap[SF] = NewDF;
1197 /// Set up prototypes for any aliases that come over from the source module.
1198 bool ModuleLinker::linkAliasProto(GlobalAlias *SGA) {
1199 GlobalValue *DGV = getLinkedToGlobal(SGA);
1200 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
1201 bool HasUnnamedAddr = SGA->hasUnnamedAddr();
1203 bool LinkFromSrc = false;
1204 Comdat *DC = nullptr;
1205 if (const Comdat *SC = SGA->getComdat()) {
1206 Comdat::SelectionKind SK;
1207 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1208 DC = DstM->getOrInsertComdat(SC->getName());
1209 DC->setSelectionKind(SK);
1214 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
1215 GlobalValue::VisibilityTypes NV;
1216 if (getLinkageResult(DGV, SGA, NewLinkage, NV, LinkFromSrc))
1219 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1222 // Set calculated linkage.
1223 DGV->setLinkage(NewLinkage);
1224 DGV->setVisibility(*NewVisibility);
1225 DGV->setUnnamedAddr(HasUnnamedAddr);
1230 // Make sure to remember this mapping.
1231 ValueMap[SGA] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGA->getType()));
1233 // Track the alias from the source module so we don't attempt to remap it.
1234 DoNotLinkFromSource.insert(SGA);
1240 // If the Comdat this alias was inside of wasn't selected, skip it.
1241 if (DC && !DGV && !LinkFromSrc) {
1242 DoNotLinkFromSource.insert(SGA);
1246 // If there is no linkage to be performed or we're linking from the source,
1248 auto *PTy = cast<PointerType>(TypeMap.get(SGA->getType()));
1250 GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(),
1251 SGA->getLinkage(), SGA->getName(), DstM);
1252 copyGVAttributes(NewDA, SGA);
1254 NewDA->setVisibility(*NewVisibility);
1255 NewDA->setUnnamedAddr(HasUnnamedAddr);
1258 // Any uses of DGV need to change to NewDA, with cast.
1259 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDA, DGV->getType()));
1260 DGV->eraseFromParent();
1263 ValueMap[SGA] = NewDA;
1267 static void getArrayElements(Constant *C, SmallVectorImpl<Constant*> &Dest) {
1268 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1270 for (unsigned i = 0; i != NumElements; ++i)
1271 Dest.push_back(C->getAggregateElement(i));
1274 void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) {
1275 // Merge the initializer.
1276 SmallVector<Constant *, 16> DstElements;
1277 getArrayElements(AVI.DstInit, DstElements);
1279 SmallVector<Constant *, 16> SrcElements;
1280 getArrayElements(AVI.SrcInit, SrcElements);
1282 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
1284 StringRef Name = AVI.NewGV->getName();
1285 bool IsNewStructor =
1286 (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
1287 cast<StructType>(NewType->getElementType())->getNumElements() == 3;
1289 for (auto *V : SrcElements) {
1290 if (IsNewStructor) {
1291 Constant *Key = V->getAggregateElement(2);
1292 if (DoNotLinkFromSource.count(Key))
1295 DstElements.push_back(
1296 MapValue(V, ValueMap, RF_None, &TypeMap, &ValMaterializer));
1298 if (IsNewStructor) {
1299 NewType = ArrayType::get(NewType->getElementType(), DstElements.size());
1300 AVI.NewGV->mutateType(PointerType::get(NewType, 0));
1303 AVI.NewGV->setInitializer(ConstantArray::get(NewType, DstElements));
1306 /// Update the initializers in the Dest module now that all globals that may be
1307 /// referenced are in Dest.
1308 void ModuleLinker::linkGlobalInits() {
1309 // Loop over all of the globals in the src module, mapping them over as we go
1310 for (Module::const_global_iterator I = SrcM->global_begin(),
1311 E = SrcM->global_end(); I != E; ++I) {
1313 // Only process initialized GV's or ones not already in dest.
1314 if (!I->hasInitializer() || DoNotLinkFromSource.count(I)) continue;
1316 // Grab destination global variable.
1317 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[I]);
1318 // Figure out what the initializer looks like in the dest module.
1319 DGV->setInitializer(MapValue(I->getInitializer(), ValueMap,
1320 RF_None, &TypeMap, &ValMaterializer));
1324 /// Copy the source function over into the dest function and fix up references
1325 /// to values. At this point we know that Dest is an external function, and
1326 /// that Src is not.
1327 void ModuleLinker::linkFunctionBody(Function *Dst, Function *Src) {
1328 assert(Src && Dst && Dst->isDeclaration() && !Src->isDeclaration());
1330 // Go through and convert function arguments over, remembering the mapping.
1331 Function::arg_iterator DI = Dst->arg_begin();
1332 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1333 I != E; ++I, ++DI) {
1334 DI->setName(I->getName()); // Copy the name over.
1336 // Add a mapping to our mapping.
1340 if (Mode == Linker::DestroySource) {
1341 // Splice the body of the source function into the dest function.
1342 Dst->getBasicBlockList().splice(Dst->end(), Src->getBasicBlockList());
1344 // At this point, all of the instructions and values of the function are now
1345 // copied over. The only problem is that they are still referencing values in
1346 // the Source function as operands. Loop through all of the operands of the
1347 // functions and patch them up to point to the local versions.
1348 for (Function::iterator BB = Dst->begin(), BE = Dst->end(); BB != BE; ++BB)
1349 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
1350 RemapInstruction(I, ValueMap, RF_IgnoreMissingEntries,
1351 &TypeMap, &ValMaterializer);
1354 // Clone the body of the function into the dest function.
1355 SmallVector<ReturnInst*, 8> Returns; // Ignore returns.
1356 CloneFunctionInto(Dst, Src, ValueMap, false, Returns, "", nullptr,
1357 &TypeMap, &ValMaterializer);
1360 // There is no need to map the arguments anymore.
1361 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1367 /// Insert all of the aliases in Src into the Dest module.
1368 void ModuleLinker::linkAliasBodies() {
1369 for (Module::alias_iterator I = SrcM->alias_begin(), E = SrcM->alias_end();
1371 if (DoNotLinkFromSource.count(I))
1373 if (Constant *Aliasee = I->getAliasee()) {
1374 GlobalAlias *DA = cast<GlobalAlias>(ValueMap[I]);
1376 MapValue(Aliasee, ValueMap, RF_None, &TypeMap, &ValMaterializer);
1377 DA->setAliasee(Val);
1382 /// Insert all of the named MDNodes in Src into the Dest module.
1383 void ModuleLinker::linkNamedMDNodes() {
1384 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1385 for (Module::const_named_metadata_iterator I = SrcM->named_metadata_begin(),
1386 E = SrcM->named_metadata_end(); I != E; ++I) {
1387 // Don't link module flags here. Do them separately.
1388 if (&*I == SrcModFlags) continue;
1389 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(I->getName());
1390 // Add Src elements into Dest node.
1391 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
1392 DestNMD->addOperand(MapValue(I->getOperand(i), ValueMap,
1393 RF_None, &TypeMap, &ValMaterializer));
1397 /// Merge the linker flags in Src into the Dest module.
1398 bool ModuleLinker::linkModuleFlagsMetadata() {
1399 // If the source module has no module flags, we are done.
1400 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1401 if (!SrcModFlags) return false;
1403 // If the destination module doesn't have module flags yet, then just copy
1404 // over the source module's flags.
1405 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
1406 if (DstModFlags->getNumOperands() == 0) {
1407 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1408 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1413 // First build a map of the existing module flags and requirements.
1414 DenseMap<MDString*, MDNode*> Flags;
1415 SmallSetVector<MDNode*, 16> Requirements;
1416 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1417 MDNode *Op = DstModFlags->getOperand(I);
1418 ConstantInt *Behavior = cast<ConstantInt>(Op->getOperand(0));
1419 MDString *ID = cast<MDString>(Op->getOperand(1));
1421 if (Behavior->getZExtValue() == Module::Require) {
1422 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1428 // Merge in the flags from the source module, and also collect its set of
1430 bool HasErr = false;
1431 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1432 MDNode *SrcOp = SrcModFlags->getOperand(I);
1433 ConstantInt *SrcBehavior = cast<ConstantInt>(SrcOp->getOperand(0));
1434 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1435 MDNode *DstOp = Flags.lookup(ID);
1436 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1438 // If this is a requirement, add it and continue.
1439 if (SrcBehaviorValue == Module::Require) {
1440 // If the destination module does not already have this requirement, add
1442 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1443 DstModFlags->addOperand(SrcOp);
1448 // If there is no existing flag with this ID, just add it.
1451 DstModFlags->addOperand(SrcOp);
1455 // Otherwise, perform a merge.
1456 ConstantInt *DstBehavior = cast<ConstantInt>(DstOp->getOperand(0));
1457 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1459 // If either flag has override behavior, handle it first.
1460 if (DstBehaviorValue == Module::Override) {
1461 // Diagnose inconsistent flags which both have override behavior.
1462 if (SrcBehaviorValue == Module::Override &&
1463 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1464 HasErr |= emitError("linking module flags '" + ID->getString() +
1465 "': IDs have conflicting override values");
1468 } else if (SrcBehaviorValue == Module::Override) {
1469 // Update the destination flag to that of the source.
1470 DstOp->replaceOperandWith(0, SrcBehavior);
1471 DstOp->replaceOperandWith(2, SrcOp->getOperand(2));
1475 // Diagnose inconsistent merge behavior types.
1476 if (SrcBehaviorValue != DstBehaviorValue) {
1477 HasErr |= emitError("linking module flags '" + ID->getString() +
1478 "': IDs have conflicting behaviors");
1482 // Perform the merge for standard behavior types.
1483 switch (SrcBehaviorValue) {
1484 case Module::Require:
1485 case Module::Override: llvm_unreachable("not possible");
1486 case Module::Error: {
1487 // Emit an error if the values differ.
1488 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1489 HasErr |= emitError("linking module flags '" + ID->getString() +
1490 "': IDs have conflicting values");
1494 case Module::Warning: {
1495 // Emit a warning if the values differ.
1496 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1497 emitWarning("linking module flags '" + ID->getString() +
1498 "': IDs have conflicting values");
1502 case Module::Append: {
1503 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1504 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1505 unsigned NumOps = DstValue->getNumOperands() + SrcValue->getNumOperands();
1506 Value **VP, **Values = VP = new Value*[NumOps];
1507 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i, ++VP)
1508 *VP = DstValue->getOperand(i);
1509 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i, ++VP)
1510 *VP = SrcValue->getOperand(i);
1511 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1512 ArrayRef<Value*>(Values,
1517 case Module::AppendUnique: {
1518 SmallSetVector<Value*, 16> Elts;
1519 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1520 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1521 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i)
1522 Elts.insert(DstValue->getOperand(i));
1523 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i)
1524 Elts.insert(SrcValue->getOperand(i));
1525 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1526 ArrayRef<Value*>(Elts.begin(),
1533 // Check all of the requirements.
1534 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1535 MDNode *Requirement = Requirements[I];
1536 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1537 Value *ReqValue = Requirement->getOperand(1);
1539 MDNode *Op = Flags[Flag];
1540 if (!Op || Op->getOperand(2) != ReqValue) {
1541 HasErr |= emitError("linking module flags '" + Flag->getString() +
1542 "': does not have the required value");
1550 bool ModuleLinker::run() {
1551 assert(DstM && "Null destination module");
1552 assert(SrcM && "Null source module");
1554 // Inherit the target data from the source module if the destination module
1555 // doesn't have one already.
1556 if (!DstM->getDataLayout() && SrcM->getDataLayout())
1557 DstM->setDataLayout(SrcM->getDataLayout());
1559 // Copy the target triple from the source to dest if the dest's is empty.
1560 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
1561 DstM->setTargetTriple(SrcM->getTargetTriple());
1563 if (SrcM->getDataLayout() && DstM->getDataLayout() &&
1564 *SrcM->getDataLayout() != *DstM->getDataLayout()) {
1565 emitWarning("Linking two modules of different data layouts: '" +
1566 SrcM->getModuleIdentifier() + "' is '" +
1567 SrcM->getDataLayoutStr() + "' whereas '" +
1568 DstM->getModuleIdentifier() + "' is '" +
1569 DstM->getDataLayoutStr() + "'\n");
1571 if (!SrcM->getTargetTriple().empty() &&
1572 DstM->getTargetTriple() != SrcM->getTargetTriple()) {
1573 emitWarning("Linking two modules of different target triples: " +
1574 SrcM->getModuleIdentifier() + "' is '" +
1575 SrcM->getTargetTriple() + "' whereas '" +
1576 DstM->getModuleIdentifier() + "' is '" +
1577 DstM->getTargetTriple() + "'\n");
1580 // Append the module inline asm string.
1581 if (!SrcM->getModuleInlineAsm().empty()) {
1582 if (DstM->getModuleInlineAsm().empty())
1583 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
1585 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
1586 SrcM->getModuleInlineAsm());
1589 // Loop over all of the linked values to compute type mappings.
1590 computeTypeMapping();
1592 ComdatsChosen.clear();
1593 for (const StringMapEntry<llvm::Comdat> &SMEC : SrcM->getComdatSymbolTable()) {
1594 const Comdat &C = SMEC.getValue();
1595 if (ComdatsChosen.count(&C))
1597 Comdat::SelectionKind SK;
1599 if (getComdatResult(&C, SK, LinkFromSrc))
1601 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1604 // Upgrade mismatched global arrays.
1605 upgradeMismatchedGlobals();
1607 // Insert all of the globals in src into the DstM module... without linking
1608 // initializers (which could refer to functions not yet mapped over).
1609 for (Module::global_iterator I = SrcM->global_begin(),
1610 E = SrcM->global_end(); I != E; ++I)
1611 if (linkGlobalProto(I))
1614 // Link the functions together between the two modules, without doing function
1615 // bodies... this just adds external function prototypes to the DstM
1616 // function... We do this so that when we begin processing function bodies,
1617 // all of the global values that may be referenced are available in our
1619 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I)
1620 if (linkFunctionProto(I))
1623 // If there were any aliases, link them now.
1624 for (Module::alias_iterator I = SrcM->alias_begin(),
1625 E = SrcM->alias_end(); I != E; ++I)
1626 if (linkAliasProto(I))
1629 for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i)
1630 linkAppendingVarInit(AppendingVars[i]);
1632 // Link in the function bodies that are defined in the source module into
1634 for (Module::iterator SF = SrcM->begin(), E = SrcM->end(); SF != E; ++SF) {
1635 // Skip if not linking from source.
1636 if (DoNotLinkFromSource.count(SF)) continue;
1638 Function *DF = cast<Function>(ValueMap[SF]);
1639 if (SF->hasPrefixData()) {
1640 // Link in the prefix data.
1641 DF->setPrefixData(MapValue(
1642 SF->getPrefixData(), ValueMap, RF_None, &TypeMap, &ValMaterializer));
1645 // Materialize if needed.
1646 if (SF->isMaterializable()) {
1647 if (std::error_code EC = SF->materialize())
1648 return emitError(EC.message());
1651 // Skip if no body (function is external).
1652 if (SF->isDeclaration())
1655 linkFunctionBody(DF, SF);
1656 SF->Dematerialize();
1659 // Resolve all uses of aliases with aliasees.
1662 // Remap all of the named MDNodes in Src into the DstM module. We do this
1663 // after linking GlobalValues so that MDNodes that reference GlobalValues
1664 // are properly remapped.
1667 // Merge the module flags into the DstM module.
1668 if (linkModuleFlagsMetadata())
1671 // Update the initializers in the DstM module now that all globals that may
1672 // be referenced are in DstM.
1675 // Process vector of lazily linked in functions.
1676 bool LinkedInAnyFunctions;
1678 LinkedInAnyFunctions = false;
1680 for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(),
1681 E = LazilyLinkFunctions.end(); I != E; ++I) {
1686 Function *DF = cast<Function>(ValueMap[SF]);
1687 if (SF->hasPrefixData()) {
1688 // Link in the prefix data.
1689 DF->setPrefixData(MapValue(SF->getPrefixData(),
1696 // Materialize if needed.
1697 if (SF->isMaterializable()) {
1698 if (std::error_code EC = SF->materialize())
1699 return emitError(EC.message());
1702 // Skip if no body (function is external).
1703 if (SF->isDeclaration())
1706 // Erase from vector *before* the function body is linked - linkFunctionBody could
1708 LazilyLinkFunctions.erase(I);
1710 // Link in function body.
1711 linkFunctionBody(DF, SF);
1712 SF->Dematerialize();
1714 // Set flag to indicate we may have more functions to lazily link in
1715 // since we linked in a function.
1716 LinkedInAnyFunctions = true;
1719 } while (LinkedInAnyFunctions);
1721 // Now that all of the types from the source are used, resolve any structs
1722 // copied over to the dest that didn't exist there.
1723 TypeMap.linkDefinedTypeBodies();
1728 Linker::Linker(Module *M, DiagnosticHandlerFunction DiagnosticHandler)
1729 : Composite(M), DiagnosticHandler(DiagnosticHandler) {}
1731 Linker::Linker(Module *M)
1732 : Composite(M), DiagnosticHandler([this](const DiagnosticInfo &DI) {
1733 Composite->getContext().diagnose(DI);
1735 TypeFinder StructTypes;
1736 StructTypes.run(*M, true);
1737 IdentifiedStructTypes.insert(StructTypes.begin(), StructTypes.end());
1743 void Linker::deleteModule() {
1745 Composite = nullptr;
1748 bool Linker::linkInModule(Module *Src, unsigned Mode) {
1749 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src, Mode, DiagnosticHandler);
1750 return TheLinker.run();
1753 //===----------------------------------------------------------------------===//
1754 // LinkModules entrypoint.
1755 //===----------------------------------------------------------------------===//
1757 /// This function links two modules together, with the resulting Dest module
1758 /// modified to be the composite of the two input modules. If an error occurs,
1759 /// true is returned and ErrorMsg (if not null) is set to indicate the problem.
1760 /// Upon failure, the Dest module could be in a modified state, and shouldn't be
1761 /// relied on to be consistent.
1762 bool Linker::LinkModules(Module *Dest, Module *Src, unsigned Mode,
1763 DiagnosticHandlerFunction DiagnosticHandler) {
1764 Linker L(Dest, DiagnosticHandler);
1765 return L.linkInModule(Src, Mode);
1768 bool Linker::LinkModules(Module *Dest, Module *Src, unsigned Mode) {
1770 return L.linkInModule(Src, Mode);
1773 //===----------------------------------------------------------------------===//
1775 //===----------------------------------------------------------------------===//
1777 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
1778 LLVMLinkerMode Mode, char **OutMessages) {
1779 Module *D = unwrap(Dest);
1780 std::string Message;
1781 raw_string_ostream Stream(Message);
1782 DiagnosticPrinterRawOStream DP(Stream);
1784 LLVMBool Result = Linker::LinkModules(
1785 D, unwrap(Src), Mode, [&](const DiagnosticInfo &DI) { DI.print(DP); });
1787 if (OutMessages && Result)
1788 *OutMessages = strdup(Message.c_str());