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 const Constant *DstInit; // Old initializer from dest module.
408 const Constant *SrcInit; // Old initializer from src module.
411 std::vector<AppendingVarInfo> AppendingVars;
413 // Set of items not to link in from source.
414 SmallPtrSet<const Value*, 16> DoNotLinkFromSource;
416 // Vector of functions to lazily link in.
417 std::vector<Function*> LazilyLinkFunctions;
419 Linker::DiagnosticHandlerFunction DiagnosticHandler;
422 ModuleLinker(Module *dstM, TypeSet &Set, Module *srcM,
423 Linker::DiagnosticHandlerFunction DiagnosticHandler)
424 : DstM(dstM), SrcM(srcM), TypeMap(Set),
425 ValMaterializer(TypeMap, DstM, LazilyLinkFunctions),
426 DiagnosticHandler(DiagnosticHandler) {}
431 bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
432 const GlobalValue &Src);
434 /// Helper method for setting a message and returning an error code.
435 bool emitError(const Twine &Message) {
436 DiagnosticHandler(LinkDiagnosticInfo(DS_Error, Message));
440 void emitWarning(const Twine &Message) {
441 DiagnosticHandler(LinkDiagnosticInfo(DS_Warning, Message));
444 bool getComdatLeader(Module *M, StringRef ComdatName,
445 const GlobalVariable *&GVar);
446 bool computeResultingSelectionKind(StringRef ComdatName,
447 Comdat::SelectionKind Src,
448 Comdat::SelectionKind Dst,
449 Comdat::SelectionKind &Result,
451 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
453 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
456 /// 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(const 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,
490 const GlobalVariable *SrcGV);
491 bool linkGlobalProto(const GlobalVariable *SrcGV);
492 bool linkFunctionProto(Function *SrcF);
493 bool linkAliasProto(GlobalAlias *SrcA);
494 bool linkModuleFlagsMetadata();
496 void linkAppendingVarInit(const AppendingVarInfo &AVI);
497 void linkGlobalInits();
498 void linkFunctionBody(Function *Dst, Function *Src);
499 void linkAliasBodies();
500 void linkNamedMDNodes();
504 /// The LLVM SymbolTable class autorenames globals that conflict in the symbol
505 /// table. This is good for all clients except for us. Go through the trouble
506 /// to force this back.
507 static void forceRenaming(GlobalValue *GV, StringRef Name) {
508 // If the global doesn't force its name or if it already has the right name,
509 // there is nothing for us to do.
510 if (GV->hasLocalLinkage() || GV->getName() == Name)
513 Module *M = GV->getParent();
515 // If there is a conflict, rename the conflict.
516 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
517 GV->takeName(ConflictGV);
518 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
519 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
521 GV->setName(Name); // Force the name back
525 /// copy additional attributes (those not needed to construct a GlobalValue)
526 /// from the SrcGV to the DestGV.
527 static void copyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) {
528 // Use the maximum alignment, rather than just copying the alignment of SrcGV.
529 auto *DestGO = dyn_cast<GlobalObject>(DestGV);
532 Alignment = std::max(DestGO->getAlignment(), SrcGV->getAlignment());
534 DestGV->copyAttributesFrom(SrcGV);
537 DestGO->setAlignment(Alignment);
539 forceRenaming(DestGV, SrcGV->getName());
542 static bool isLessConstraining(GlobalValue::VisibilityTypes a,
543 GlobalValue::VisibilityTypes b) {
544 if (a == GlobalValue::HiddenVisibility)
546 if (b == GlobalValue::HiddenVisibility)
548 if (a == GlobalValue::ProtectedVisibility)
550 if (b == GlobalValue::ProtectedVisibility)
555 Value *ValueMaterializerTy::materializeValueFor(Value *V) {
556 Function *SF = dyn_cast<Function>(V);
560 Function *DF = Function::Create(TypeMap.get(SF->getFunctionType()),
561 SF->getLinkage(), SF->getName(), DstM);
562 copyGVAttributes(DF, SF);
564 if (Comdat *SC = SF->getComdat()) {
565 Comdat *DC = DstM->getOrInsertComdat(SC->getName());
569 LazilyLinkFunctions.push_back(SF);
573 bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName,
574 const GlobalVariable *&GVar) {
575 const GlobalValue *GVal = M->getNamedValue(ComdatName);
576 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
577 GVal = GA->getBaseObject();
579 // We cannot resolve the size of the aliasee yet.
580 return emitError("Linking COMDATs named '" + ComdatName +
581 "': COMDAT key involves incomputable alias size.");
584 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
587 "Linking COMDATs named '" + ComdatName +
588 "': GlobalVariable required for data dependent selection!");
593 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
594 Comdat::SelectionKind Src,
595 Comdat::SelectionKind Dst,
596 Comdat::SelectionKind &Result,
598 // The ability to mix Comdat::SelectionKind::Any with
599 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
600 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
601 Dst == Comdat::SelectionKind::Largest;
602 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
603 Src == Comdat::SelectionKind::Largest;
604 if (DstAnyOrLargest && SrcAnyOrLargest) {
605 if (Dst == Comdat::SelectionKind::Largest ||
606 Src == Comdat::SelectionKind::Largest)
607 Result = Comdat::SelectionKind::Largest;
609 Result = Comdat::SelectionKind::Any;
610 } else if (Src == Dst) {
613 return emitError("Linking COMDATs named '" + ComdatName +
614 "': invalid selection kinds!");
618 case Comdat::SelectionKind::Any:
622 case Comdat::SelectionKind::NoDuplicates:
623 return emitError("Linking COMDATs named '" + ComdatName +
624 "': noduplicates has been violated!");
625 case Comdat::SelectionKind::ExactMatch:
626 case Comdat::SelectionKind::Largest:
627 case Comdat::SelectionKind::SameSize: {
628 const GlobalVariable *DstGV;
629 const GlobalVariable *SrcGV;
630 if (getComdatLeader(DstM, ComdatName, DstGV) ||
631 getComdatLeader(SrcM, ComdatName, SrcGV))
634 const DataLayout *DstDL = DstM->getDataLayout();
635 const DataLayout *SrcDL = SrcM->getDataLayout();
636 if (!DstDL || !SrcDL) {
638 "Linking COMDATs named '" + ComdatName +
639 "': can't do size dependent selection without DataLayout!");
642 DstDL->getTypeAllocSize(DstGV->getType()->getPointerElementType());
644 SrcDL->getTypeAllocSize(SrcGV->getType()->getPointerElementType());
645 if (Result == Comdat::SelectionKind::ExactMatch) {
646 if (SrcGV->getInitializer() != DstGV->getInitializer())
647 return emitError("Linking COMDATs named '" + ComdatName +
648 "': ExactMatch violated!");
650 } else if (Result == Comdat::SelectionKind::Largest) {
651 LinkFromSrc = SrcSize > DstSize;
652 } else if (Result == Comdat::SelectionKind::SameSize) {
653 if (SrcSize != DstSize)
654 return emitError("Linking COMDATs named '" + ComdatName +
655 "': SameSize violated!");
658 llvm_unreachable("unknown selection kind");
667 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
668 Comdat::SelectionKind &Result,
670 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
671 StringRef ComdatName = SrcC->getName();
672 Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable();
673 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
675 if (DstCI == ComdatSymTab.end()) {
676 // Use the comdat if it is only available in one of the modules.
682 const Comdat *DstC = &DstCI->second;
683 Comdat::SelectionKind DSK = DstC->getSelectionKind();
684 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
688 bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
689 const GlobalValue &Dest,
690 const GlobalValue &Src) {
691 bool SrcIsDeclaration = Src.isDeclarationForLinker();
692 bool DestIsDeclaration = Dest.isDeclarationForLinker();
694 if (SrcIsDeclaration) {
695 // If Src is external or if both Src & Dest are external.. Just link the
696 // external globals, we aren't adding anything.
697 if (Src.hasDLLImportStorageClass()) {
698 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
699 LinkFromSrc = DestIsDeclaration;
702 // If the Dest is weak, use the source linkage.
703 LinkFromSrc = Dest.hasExternalWeakLinkage();
707 if (DestIsDeclaration) {
708 // If Dest is external but Src is not:
713 if (Src.hasCommonLinkage()) {
714 if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
719 if (!Dest.hasCommonLinkage()) {
724 // FIXME: Make datalayout mandatory and just use getDataLayout().
725 DataLayout DL(Dest.getParent());
727 uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
728 uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
729 LinkFromSrc = SrcSize > DestSize;
733 if (Src.isWeakForLinker()) {
734 assert(!Dest.hasExternalWeakLinkage());
735 assert(!Dest.hasAvailableExternallyLinkage());
737 if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
746 if (Dest.isWeakForLinker()) {
747 assert(Src.hasExternalLinkage());
752 assert(!Src.hasExternalWeakLinkage());
753 assert(!Dest.hasExternalWeakLinkage());
754 assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
755 "Unexpected linkage type!");
756 return emitError("Linking globals named '" + Src.getName() +
757 "': symbol multiply defined!");
760 /// This analyzes the two global values and determines what the result will look
761 /// like in the destination module. In particular, it computes the resultant
762 /// linkage type and visibility, computes whether the global in the source
763 /// should be copied over to the destination (replacing the existing one), and
764 /// computes whether this linkage is an error or not.
765 bool ModuleLinker::getLinkageResult(GlobalValue *Dest, const GlobalValue *Src,
766 GlobalValue::LinkageTypes <,
767 GlobalValue::VisibilityTypes &Vis,
769 assert(Dest && "Must have two globals being queried");
770 assert(!Src->hasLocalLinkage() &&
771 "If Src has internal linkage, Dest shouldn't be set!");
773 if (shouldLinkFromSource(LinkFromSrc, *Dest, *Src))
777 LT = Src->getLinkage();
779 LT = Dest->getLinkage();
781 // Compute the visibility. We follow the rules in the System V Application
783 assert(!GlobalValue::isLocalLinkage(LT) &&
784 "Symbols with local linkage should not be merged");
785 Vis = isLessConstraining(Src->getVisibility(), Dest->getVisibility()) ?
786 Dest->getVisibility() : Src->getVisibility();
790 /// Loop over all of the linked values to compute type mappings. For example,
791 /// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct
792 /// types 'Foo' but one got renamed when the module was loaded into the same
794 void ModuleLinker::computeTypeMapping() {
795 // Incorporate globals.
796 for (Module::global_iterator I = SrcM->global_begin(),
797 E = SrcM->global_end(); I != E; ++I) {
798 GlobalValue *DGV = getLinkedToGlobal(I);
801 if (!DGV->hasAppendingLinkage() || !I->hasAppendingLinkage()) {
802 TypeMap.addTypeMapping(DGV->getType(), I->getType());
806 // Unify the element type of appending arrays.
807 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
808 ArrayType *SAT = cast<ArrayType>(I->getType()->getElementType());
809 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
812 // Incorporate functions.
813 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I) {
814 if (GlobalValue *DGV = getLinkedToGlobal(I))
815 TypeMap.addTypeMapping(DGV->getType(), I->getType());
818 // Incorporate types by name, scanning all the types in the source module.
819 // At this point, the destination module may have a type "%foo = { i32 }" for
820 // example. When the source module got loaded into the same LLVMContext, if
821 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
822 TypeFinder SrcStructTypes;
823 SrcStructTypes.run(*SrcM, true);
824 SmallPtrSet<StructType*, 32> SrcStructTypesSet(SrcStructTypes.begin(),
825 SrcStructTypes.end());
827 for (unsigned i = 0, e = SrcStructTypes.size(); i != e; ++i) {
828 StructType *ST = SrcStructTypes[i];
829 if (!ST->hasName()) continue;
831 // Check to see if there is a dot in the name followed by a digit.
832 size_t DotPos = ST->getName().rfind('.');
833 if (DotPos == 0 || DotPos == StringRef::npos ||
834 ST->getName().back() == '.' ||
835 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos+1])))
838 // Check to see if the destination module has a struct with the prefix name.
839 if (StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos)))
840 // Don't use it if this actually came from the source module. They're in
841 // the same LLVMContext after all. Also don't use it unless the type is
842 // actually used in the destination module. This can happen in situations
847 // %Z = type { %A } %B = type { %C.1 }
848 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
849 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
850 // %C = type { i8* } %B.3 = type { %C.1 }
852 // When we link Module B with Module A, the '%B' in Module B is
853 // used. However, that would then use '%C.1'. But when we process '%C.1',
854 // we prefer to take the '%C' version. So we are then left with both
855 // '%C.1' and '%C' being used for the same types. This leads to some
856 // variables using one type and some using the other.
857 if (!SrcStructTypesSet.count(DST) && TypeMap.DstStructTypesSet.count(DST))
858 TypeMap.addTypeMapping(DST, ST);
861 // Don't bother incorporating aliases, they aren't generally typed well.
863 // Now that we have discovered all of the type equivalences, get a body for
864 // any 'opaque' types in the dest module that are now resolved.
865 TypeMap.linkDefinedTypeBodies();
868 static void upgradeGlobalArray(GlobalVariable *GV) {
869 ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
870 StructType *OldTy = cast<StructType>(ATy->getElementType());
871 assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
873 // Get the upgraded 3 element type.
874 PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
875 Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
877 StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
879 // Build new constants with a null third field filled in.
880 Constant *OldInitC = GV->getInitializer();
881 ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
882 if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
883 // Invalid initializer; give up.
885 std::vector<Constant *> Initializers;
886 if (OldInit && OldInit->getNumOperands()) {
887 Value *Null = Constant::getNullValue(VoidPtrTy);
888 for (Use &U : OldInit->operands()) {
889 ConstantStruct *Init = cast<ConstantStruct>(U.get());
890 Initializers.push_back(ConstantStruct::get(
891 NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
894 assert(Initializers.size() == ATy->getNumElements() &&
895 "Failed to copy all array elements");
897 // Replace the old GV with a new one.
898 ATy = ArrayType::get(NewTy, Initializers.size());
899 Constant *NewInit = ConstantArray::get(ATy, Initializers);
900 GlobalVariable *NewGV = new GlobalVariable(
901 *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
902 GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
903 GV->isExternallyInitialized());
904 NewGV->copyAttributesFrom(GV);
906 assert(GV->use_empty() && "program cannot use initializer list");
907 GV->eraseFromParent();
910 void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
911 // Look for the global arrays.
912 auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM->getNamedValue(Name));
915 auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM->getNamedValue(Name));
919 // Check if the types already match.
920 auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
922 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
926 // Grab the element types. We can only upgrade an array of a two-field
927 // struct. Only bother if the other one has three-fields.
928 auto *DstEltTy = cast<StructType>(DstTy->getElementType());
929 auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
930 if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
931 upgradeGlobalArray(DstGV);
934 if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
935 upgradeGlobalArray(SrcGV);
937 // We can't upgrade any other differences.
940 void ModuleLinker::upgradeMismatchedGlobals() {
941 upgradeMismatchedGlobalArray("llvm.global_ctors");
942 upgradeMismatchedGlobalArray("llvm.global_dtors");
945 /// If there were any appending global variables, link them together now.
946 /// Return true on error.
947 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
948 const GlobalVariable *SrcGV) {
950 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
951 return emitError("Linking globals named '" + SrcGV->getName() +
952 "': can only link appending global with another appending global!");
954 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
956 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
957 Type *EltTy = DstTy->getElementType();
959 // Check to see that they two arrays agree on type.
960 if (EltTy != SrcTy->getElementType())
961 return emitError("Appending variables with different element types!");
962 if (DstGV->isConstant() != SrcGV->isConstant())
963 return emitError("Appending variables linked with different const'ness!");
965 if (DstGV->getAlignment() != SrcGV->getAlignment())
967 "Appending variables with different alignment need to be linked!");
969 if (DstGV->getVisibility() != SrcGV->getVisibility())
971 "Appending variables with different visibility need to be linked!");
973 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
975 "Appending variables with different unnamed_addr need to be linked!");
977 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
979 "Appending variables with different section name need to be linked!");
981 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements();
982 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
984 // Create the new global variable.
986 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(),
987 DstGV->getLinkage(), /*init*/nullptr, /*name*/"", DstGV,
988 DstGV->getThreadLocalMode(),
989 DstGV->getType()->getAddressSpace());
991 // Propagate alignment, visibility and section info.
992 copyGVAttributes(NG, DstGV);
994 AppendingVarInfo AVI;
996 AVI.DstInit = DstGV->getInitializer();
997 AVI.SrcInit = SrcGV->getInitializer();
998 AppendingVars.push_back(AVI);
1000 // Replace any uses of the two global variables with uses of the new
1002 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
1004 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
1005 DstGV->eraseFromParent();
1007 // Track the source variable so we don't try to link it.
1008 DoNotLinkFromSource.insert(SrcGV);
1013 /// Loop through the global variables in the src module and merge them into the
1015 bool ModuleLinker::linkGlobalProto(const GlobalVariable *SGV) {
1016 GlobalValue *DGV = getLinkedToGlobal(SGV);
1017 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
1018 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
1019 unsigned Alignment = SGV->getAlignment();
1021 bool LinkFromSrc = false;
1022 Comdat *DC = nullptr;
1023 if (const Comdat *SC = SGV->getComdat()) {
1024 Comdat::SelectionKind SK;
1025 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1026 DC = DstM->getOrInsertComdat(SC->getName());
1027 DC->setSelectionKind(SK);
1032 // Concatenation of appending linkage variables is magic and handled later.
1033 if (DGV->hasAppendingLinkage() || SGV->hasAppendingLinkage())
1034 return linkAppendingVarProto(cast<GlobalVariable>(DGV), SGV);
1036 // Determine whether linkage of these two globals follows the source
1037 // module's definition or the destination module's definition.
1038 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
1039 GlobalValue::VisibilityTypes NV;
1040 if (getLinkageResult(DGV, SGV, NewLinkage, NV, LinkFromSrc))
1043 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1044 if (DGV->hasCommonLinkage() && SGV->hasCommonLinkage())
1045 Alignment = std::max(Alignment, DGV->getAlignment());
1046 else if (!LinkFromSrc)
1047 Alignment = DGV->getAlignment();
1049 // If we're not linking from the source, then keep the definition that we
1052 // Special case for const propagation.
1053 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) {
1054 DGVar->setAlignment(Alignment);
1056 if (DGVar->isDeclaration() && !SGV->isConstant())
1057 DGVar->setConstant(false);
1060 // Set calculated linkage, visibility and unnamed_addr.
1061 DGV->setLinkage(NewLinkage);
1062 DGV->setVisibility(*NewVisibility);
1063 DGV->setUnnamedAddr(HasUnnamedAddr);
1068 // Make sure to remember this mapping.
1069 ValueMap[SGV] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGV->getType()));
1071 // Track the source global so that we don't attempt to copy it over when
1072 // processing global initializers.
1073 DoNotLinkFromSource.insert(SGV);
1079 // If the Comdat this variable was inside of wasn't selected, skip it.
1080 if (DC && !DGV && !LinkFromSrc) {
1081 DoNotLinkFromSource.insert(SGV);
1085 // No linking to be performed or linking from the source: simply create an
1086 // identical version of the symbol over in the dest module... the
1087 // initializer will be filled in later by LinkGlobalInits.
1088 GlobalVariable *NewDGV =
1089 new GlobalVariable(*DstM, TypeMap.get(SGV->getType()->getElementType()),
1090 SGV->isConstant(), SGV->getLinkage(), /*init*/nullptr,
1091 SGV->getName(), /*insertbefore*/nullptr,
1092 SGV->getThreadLocalMode(),
1093 SGV->getType()->getAddressSpace());
1094 // Propagate alignment, visibility and section info.
1095 copyGVAttributes(NewDGV, SGV);
1096 NewDGV->setAlignment(Alignment);
1098 NewDGV->setVisibility(*NewVisibility);
1099 NewDGV->setUnnamedAddr(HasUnnamedAddr);
1102 NewDGV->setComdat(DC);
1105 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV, DGV->getType()));
1106 DGV->eraseFromParent();
1109 // Make sure to remember this mapping.
1110 ValueMap[SGV] = NewDGV;
1114 /// Link the function in the source module into the destination module if
1115 /// needed, setting up mapping information.
1116 bool ModuleLinker::linkFunctionProto(Function *SF) {
1117 GlobalValue *DGV = getLinkedToGlobal(SF);
1118 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
1119 bool HasUnnamedAddr = SF->hasUnnamedAddr();
1121 bool LinkFromSrc = false;
1122 Comdat *DC = nullptr;
1123 if (const Comdat *SC = SF->getComdat()) {
1124 Comdat::SelectionKind SK;
1125 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1126 DC = DstM->getOrInsertComdat(SC->getName());
1127 DC->setSelectionKind(SK);
1132 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
1133 GlobalValue::VisibilityTypes NV;
1134 if (getLinkageResult(DGV, SF, NewLinkage, NV, LinkFromSrc))
1137 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1140 // Set calculated linkage
1141 DGV->setLinkage(NewLinkage);
1142 DGV->setVisibility(*NewVisibility);
1143 DGV->setUnnamedAddr(HasUnnamedAddr);
1148 // Make sure to remember this mapping.
1149 ValueMap[SF] = ConstantExpr::getBitCast(DGV, TypeMap.get(SF->getType()));
1151 // Track the function from the source module so we don't attempt to remap
1153 DoNotLinkFromSource.insert(SF);
1159 // If the function is to be lazily linked, don't create it just yet.
1160 // The ValueMaterializerTy will deal with creating it if it's used.
1161 if (!DGV && (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() ||
1162 SF->hasAvailableExternallyLinkage())) {
1163 DoNotLinkFromSource.insert(SF);
1167 // If the Comdat this function was inside of wasn't selected, skip it.
1168 if (DC && !DGV && !LinkFromSrc) {
1169 DoNotLinkFromSource.insert(SF);
1173 // If there is no linkage to be performed or we are linking from the source,
1175 Function *NewDF = Function::Create(TypeMap.get(SF->getFunctionType()),
1176 SF->getLinkage(), SF->getName(), DstM);
1177 copyGVAttributes(NewDF, SF);
1179 NewDF->setVisibility(*NewVisibility);
1180 NewDF->setUnnamedAddr(HasUnnamedAddr);
1183 NewDF->setComdat(DC);
1186 // Any uses of DF need to change to NewDF, with cast.
1187 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, DGV->getType()));
1188 DGV->eraseFromParent();
1191 ValueMap[SF] = NewDF;
1195 /// Set up prototypes for any aliases that come over from the source module.
1196 bool ModuleLinker::linkAliasProto(GlobalAlias *SGA) {
1197 GlobalValue *DGV = getLinkedToGlobal(SGA);
1198 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
1199 bool HasUnnamedAddr = SGA->hasUnnamedAddr();
1201 bool LinkFromSrc = false;
1202 Comdat *DC = nullptr;
1203 if (const Comdat *SC = SGA->getComdat()) {
1204 Comdat::SelectionKind SK;
1205 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1206 DC = DstM->getOrInsertComdat(SC->getName());
1207 DC->setSelectionKind(SK);
1212 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
1213 GlobalValue::VisibilityTypes NV;
1214 if (getLinkageResult(DGV, SGA, NewLinkage, NV, LinkFromSrc))
1217 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1220 // Set calculated linkage.
1221 DGV->setLinkage(NewLinkage);
1222 DGV->setVisibility(*NewVisibility);
1223 DGV->setUnnamedAddr(HasUnnamedAddr);
1228 // Make sure to remember this mapping.
1229 ValueMap[SGA] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGA->getType()));
1231 // Track the alias from the source module so we don't attempt to remap it.
1232 DoNotLinkFromSource.insert(SGA);
1238 // If the Comdat this alias was inside of wasn't selected, skip it.
1239 if (DC && !DGV && !LinkFromSrc) {
1240 DoNotLinkFromSource.insert(SGA);
1244 // If there is no linkage to be performed or we're linking from the source,
1246 auto *PTy = cast<PointerType>(TypeMap.get(SGA->getType()));
1248 GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(),
1249 SGA->getLinkage(), SGA->getName(), DstM);
1250 copyGVAttributes(NewDA, SGA);
1252 NewDA->setVisibility(*NewVisibility);
1253 NewDA->setUnnamedAddr(HasUnnamedAddr);
1256 // Any uses of DGV need to change to NewDA, with cast.
1257 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDA, DGV->getType()));
1258 DGV->eraseFromParent();
1261 ValueMap[SGA] = NewDA;
1265 static void getArrayElements(const Constant *C,
1266 SmallVectorImpl<Constant *> &Dest) {
1267 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1269 for (unsigned i = 0; i != NumElements; ++i)
1270 Dest.push_back(C->getAggregateElement(i));
1273 void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) {
1274 // Merge the initializer.
1275 SmallVector<Constant *, 16> DstElements;
1276 getArrayElements(AVI.DstInit, DstElements);
1278 SmallVector<Constant *, 16> SrcElements;
1279 getArrayElements(AVI.SrcInit, SrcElements);
1281 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
1283 StringRef Name = AVI.NewGV->getName();
1284 bool IsNewStructor =
1285 (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
1286 cast<StructType>(NewType->getElementType())->getNumElements() == 3;
1288 for (auto *V : SrcElements) {
1289 if (IsNewStructor) {
1290 Constant *Key = V->getAggregateElement(2);
1291 if (DoNotLinkFromSource.count(Key))
1294 DstElements.push_back(
1295 MapValue(V, ValueMap, RF_None, &TypeMap, &ValMaterializer));
1297 if (IsNewStructor) {
1298 NewType = ArrayType::get(NewType->getElementType(), DstElements.size());
1299 AVI.NewGV->mutateType(PointerType::get(NewType, 0));
1302 AVI.NewGV->setInitializer(ConstantArray::get(NewType, DstElements));
1305 /// Update the initializers in the Dest module now that all globals that may be
1306 /// referenced are in Dest.
1307 void ModuleLinker::linkGlobalInits() {
1308 // Loop over all of the globals in the src module, mapping them over as we go
1309 for (Module::const_global_iterator I = SrcM->global_begin(),
1310 E = SrcM->global_end(); I != E; ++I) {
1312 // Only process initialized GV's or ones not already in dest.
1313 if (!I->hasInitializer() || DoNotLinkFromSource.count(I)) continue;
1315 // Grab destination global variable.
1316 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[I]);
1317 // Figure out what the initializer looks like in the dest module.
1318 DGV->setInitializer(MapValue(I->getInitializer(), ValueMap,
1319 RF_None, &TypeMap, &ValMaterializer));
1323 /// Copy the source function over into the dest function and fix up references
1324 /// to values. At this point we know that Dest is an external function, and
1325 /// that Src is not.
1326 void ModuleLinker::linkFunctionBody(Function *Dst, Function *Src) {
1327 assert(Src && Dst && Dst->isDeclaration() && !Src->isDeclaration());
1329 // Go through and convert function arguments over, remembering the mapping.
1330 Function::arg_iterator DI = Dst->arg_begin();
1331 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1332 I != E; ++I, ++DI) {
1333 DI->setName(I->getName()); // Copy the name over.
1335 // Add a mapping to our mapping.
1339 // Splice the body of the source function into the dest function.
1340 Dst->getBasicBlockList().splice(Dst->end(), Src->getBasicBlockList());
1342 // At this point, all of the instructions and values of the function are now
1343 // copied over. The only problem is that they are still referencing values in
1344 // the Source function as operands. Loop through all of the operands of the
1345 // functions and patch them up to point to the local versions.
1346 for (Function::iterator BB = Dst->begin(), BE = Dst->end(); BB != BE; ++BB)
1347 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
1348 RemapInstruction(I, ValueMap, RF_IgnoreMissingEntries, &TypeMap,
1351 // There is no need to map the arguments anymore.
1352 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1358 /// Insert all of the aliases in Src into the Dest module.
1359 void ModuleLinker::linkAliasBodies() {
1360 for (Module::alias_iterator I = SrcM->alias_begin(), E = SrcM->alias_end();
1362 if (DoNotLinkFromSource.count(I))
1364 if (Constant *Aliasee = I->getAliasee()) {
1365 GlobalAlias *DA = cast<GlobalAlias>(ValueMap[I]);
1367 MapValue(Aliasee, ValueMap, RF_None, &TypeMap, &ValMaterializer);
1368 DA->setAliasee(Val);
1373 /// Insert all of the named MDNodes in Src into the Dest module.
1374 void ModuleLinker::linkNamedMDNodes() {
1375 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1376 for (Module::const_named_metadata_iterator I = SrcM->named_metadata_begin(),
1377 E = SrcM->named_metadata_end(); I != E; ++I) {
1378 // Don't link module flags here. Do them separately.
1379 if (&*I == SrcModFlags) continue;
1380 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(I->getName());
1381 // Add Src elements into Dest node.
1382 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
1383 DestNMD->addOperand(MapValue(I->getOperand(i), ValueMap,
1384 RF_None, &TypeMap, &ValMaterializer));
1388 /// Merge the linker flags in Src into the Dest module.
1389 bool ModuleLinker::linkModuleFlagsMetadata() {
1390 // If the source module has no module flags, we are done.
1391 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1392 if (!SrcModFlags) return false;
1394 // If the destination module doesn't have module flags yet, then just copy
1395 // over the source module's flags.
1396 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
1397 if (DstModFlags->getNumOperands() == 0) {
1398 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1399 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1404 // First build a map of the existing module flags and requirements.
1405 DenseMap<MDString*, MDNode*> Flags;
1406 SmallSetVector<MDNode*, 16> Requirements;
1407 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1408 MDNode *Op = DstModFlags->getOperand(I);
1409 ConstantInt *Behavior = cast<ConstantInt>(Op->getOperand(0));
1410 MDString *ID = cast<MDString>(Op->getOperand(1));
1412 if (Behavior->getZExtValue() == Module::Require) {
1413 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1419 // Merge in the flags from the source module, and also collect its set of
1421 bool HasErr = false;
1422 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1423 MDNode *SrcOp = SrcModFlags->getOperand(I);
1424 ConstantInt *SrcBehavior = cast<ConstantInt>(SrcOp->getOperand(0));
1425 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1426 MDNode *DstOp = Flags.lookup(ID);
1427 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1429 // If this is a requirement, add it and continue.
1430 if (SrcBehaviorValue == Module::Require) {
1431 // If the destination module does not already have this requirement, add
1433 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1434 DstModFlags->addOperand(SrcOp);
1439 // If there is no existing flag with this ID, just add it.
1442 DstModFlags->addOperand(SrcOp);
1446 // Otherwise, perform a merge.
1447 ConstantInt *DstBehavior = cast<ConstantInt>(DstOp->getOperand(0));
1448 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1450 // If either flag has override behavior, handle it first.
1451 if (DstBehaviorValue == Module::Override) {
1452 // Diagnose inconsistent flags which both have override behavior.
1453 if (SrcBehaviorValue == Module::Override &&
1454 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1455 HasErr |= emitError("linking module flags '" + ID->getString() +
1456 "': IDs have conflicting override values");
1459 } else if (SrcBehaviorValue == Module::Override) {
1460 // Update the destination flag to that of the source.
1461 DstOp->replaceOperandWith(0, SrcBehavior);
1462 DstOp->replaceOperandWith(2, SrcOp->getOperand(2));
1466 // Diagnose inconsistent merge behavior types.
1467 if (SrcBehaviorValue != DstBehaviorValue) {
1468 HasErr |= emitError("linking module flags '" + ID->getString() +
1469 "': IDs have conflicting behaviors");
1473 // Perform the merge for standard behavior types.
1474 switch (SrcBehaviorValue) {
1475 case Module::Require:
1476 case Module::Override: llvm_unreachable("not possible");
1477 case Module::Error: {
1478 // Emit an error if the values differ.
1479 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1480 HasErr |= emitError("linking module flags '" + ID->getString() +
1481 "': IDs have conflicting values");
1485 case Module::Warning: {
1486 // Emit a warning if the values differ.
1487 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1488 emitWarning("linking module flags '" + ID->getString() +
1489 "': IDs have conflicting values");
1493 case Module::Append: {
1494 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1495 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1496 unsigned NumOps = DstValue->getNumOperands() + SrcValue->getNumOperands();
1497 Value **VP, **Values = VP = new Value*[NumOps];
1498 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i, ++VP)
1499 *VP = DstValue->getOperand(i);
1500 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i, ++VP)
1501 *VP = SrcValue->getOperand(i);
1502 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1503 ArrayRef<Value*>(Values,
1508 case Module::AppendUnique: {
1509 SmallSetVector<Value*, 16> Elts;
1510 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1511 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1512 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i)
1513 Elts.insert(DstValue->getOperand(i));
1514 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i)
1515 Elts.insert(SrcValue->getOperand(i));
1516 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1517 ArrayRef<Value*>(Elts.begin(),
1524 // Check all of the requirements.
1525 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1526 MDNode *Requirement = Requirements[I];
1527 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1528 Value *ReqValue = Requirement->getOperand(1);
1530 MDNode *Op = Flags[Flag];
1531 if (!Op || Op->getOperand(2) != ReqValue) {
1532 HasErr |= emitError("linking module flags '" + Flag->getString() +
1533 "': does not have the required value");
1541 bool ModuleLinker::run() {
1542 assert(DstM && "Null destination module");
1543 assert(SrcM && "Null source module");
1545 // Inherit the target data from the source module if the destination module
1546 // doesn't have one already.
1547 if (!DstM->getDataLayout() && SrcM->getDataLayout())
1548 DstM->setDataLayout(SrcM->getDataLayout());
1550 // Copy the target triple from the source to dest if the dest's is empty.
1551 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
1552 DstM->setTargetTriple(SrcM->getTargetTriple());
1554 if (SrcM->getDataLayout() && DstM->getDataLayout() &&
1555 *SrcM->getDataLayout() != *DstM->getDataLayout()) {
1556 emitWarning("Linking two modules of different data layouts: '" +
1557 SrcM->getModuleIdentifier() + "' is '" +
1558 SrcM->getDataLayoutStr() + "' whereas '" +
1559 DstM->getModuleIdentifier() + "' is '" +
1560 DstM->getDataLayoutStr() + "'\n");
1562 if (!SrcM->getTargetTriple().empty() &&
1563 DstM->getTargetTriple() != SrcM->getTargetTriple()) {
1564 emitWarning("Linking two modules of different target triples: " +
1565 SrcM->getModuleIdentifier() + "' is '" +
1566 SrcM->getTargetTriple() + "' whereas '" +
1567 DstM->getModuleIdentifier() + "' is '" +
1568 DstM->getTargetTriple() + "'\n");
1571 // Append the module inline asm string.
1572 if (!SrcM->getModuleInlineAsm().empty()) {
1573 if (DstM->getModuleInlineAsm().empty())
1574 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
1576 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
1577 SrcM->getModuleInlineAsm());
1580 // Loop over all of the linked values to compute type mappings.
1581 computeTypeMapping();
1583 ComdatsChosen.clear();
1584 for (const StringMapEntry<llvm::Comdat> &SMEC : SrcM->getComdatSymbolTable()) {
1585 const Comdat &C = SMEC.getValue();
1586 if (ComdatsChosen.count(&C))
1588 Comdat::SelectionKind SK;
1590 if (getComdatResult(&C, SK, LinkFromSrc))
1592 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1595 // Upgrade mismatched global arrays.
1596 upgradeMismatchedGlobals();
1598 // Insert all of the globals in src into the DstM module... without linking
1599 // initializers (which could refer to functions not yet mapped over).
1600 for (Module::global_iterator I = SrcM->global_begin(),
1601 E = SrcM->global_end(); I != E; ++I)
1602 if (linkGlobalProto(I))
1605 // Link the functions together between the two modules, without doing function
1606 // bodies... this just adds external function prototypes to the DstM
1607 // function... We do this so that when we begin processing function bodies,
1608 // all of the global values that may be referenced are available in our
1610 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I)
1611 if (linkFunctionProto(I))
1614 // If there were any aliases, link them now.
1615 for (Module::alias_iterator I = SrcM->alias_begin(),
1616 E = SrcM->alias_end(); I != E; ++I)
1617 if (linkAliasProto(I))
1620 for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i)
1621 linkAppendingVarInit(AppendingVars[i]);
1623 // Link in the function bodies that are defined in the source module into
1625 for (Module::iterator SF = SrcM->begin(), E = SrcM->end(); SF != E; ++SF) {
1626 // Skip if not linking from source.
1627 if (DoNotLinkFromSource.count(SF)) continue;
1629 Function *DF = cast<Function>(ValueMap[SF]);
1630 if (SF->hasPrefixData()) {
1631 // Link in the prefix data.
1632 DF->setPrefixData(MapValue(
1633 SF->getPrefixData(), ValueMap, RF_None, &TypeMap, &ValMaterializer));
1636 // Materialize if needed.
1637 if (std::error_code EC = SF->materialize())
1638 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 (std::error_code EC = SF->materialize())
1687 return emitError(EC.message());
1689 // Skip if no body (function is external).
1690 if (SF->isDeclaration())
1693 // Erase from vector *before* the function body is linked - linkFunctionBody could
1695 LazilyLinkFunctions.erase(I);
1697 // Link in function body.
1698 linkFunctionBody(DF, SF);
1699 SF->Dematerialize();
1701 // Set flag to indicate we may have more functions to lazily link in
1702 // since we linked in a function.
1703 LinkedInAnyFunctions = true;
1706 } while (LinkedInAnyFunctions);
1708 // Now that all of the types from the source are used, resolve any structs
1709 // copied over to the dest that didn't exist there.
1710 TypeMap.linkDefinedTypeBodies();
1715 Linker::Linker(Module *M, DiagnosticHandlerFunction DiagnosticHandler)
1716 : Composite(M), DiagnosticHandler(DiagnosticHandler) {}
1718 Linker::Linker(Module *M)
1719 : Composite(M), DiagnosticHandler([this](const DiagnosticInfo &DI) {
1720 Composite->getContext().diagnose(DI);
1722 TypeFinder StructTypes;
1723 StructTypes.run(*M, true);
1724 IdentifiedStructTypes.insert(StructTypes.begin(), StructTypes.end());
1730 void Linker::deleteModule() {
1732 Composite = nullptr;
1735 bool Linker::linkInModule(Module *Src) {
1736 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,
1738 return TheLinker.run();
1741 //===----------------------------------------------------------------------===//
1742 // LinkModules entrypoint.
1743 //===----------------------------------------------------------------------===//
1745 /// This function links two modules together, with the resulting Dest module
1746 /// modified to be the composite of the two input modules. If an error occurs,
1747 /// true is returned and ErrorMsg (if not null) is set to indicate the problem.
1748 /// Upon failure, the Dest module could be in a modified state, and shouldn't be
1749 /// relied on to be consistent.
1750 bool Linker::LinkModules(Module *Dest, Module *Src,
1751 DiagnosticHandlerFunction DiagnosticHandler) {
1752 Linker L(Dest, DiagnosticHandler);
1753 return L.linkInModule(Src);
1756 bool Linker::LinkModules(Module *Dest, Module *Src) {
1758 return L.linkInModule(Src);
1761 //===----------------------------------------------------------------------===//
1763 //===----------------------------------------------------------------------===//
1765 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
1766 LLVMLinkerMode Mode, char **OutMessages) {
1767 Module *D = unwrap(Dest);
1768 std::string Message;
1769 raw_string_ostream Stream(Message);
1770 DiagnosticPrinterRawOStream DP(Stream);
1772 LLVMBool Result = Linker::LinkModules(
1773 D, unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); });
1775 if (OutMessages && Result)
1776 *OutMessages = strdup(Message.c_str());