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 /// Produce a body for an opaque type in the dest module from a type
67 /// 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 SpeculativeTypes.clear();
115 // Oops, they aren't isomorphic. Just discard this request by rolling out
116 // any speculative mappings we've established.
117 unsigned Removed = 0;
118 for (unsigned I = 0, E = SpeculativeTypes.size(); I != E; ++I) {
119 Type *SrcTy = SpeculativeTypes[I];
120 auto Iter = MappedTypes.find(SrcTy);
121 auto *DstTy = dyn_cast<StructType>(Iter->second);
122 if (DstTy && DstResolvedOpaqueTypes.erase(DstTy))
124 MappedTypes.erase(Iter);
126 SrcDefinitionsToResolve.resize(SrcDefinitionsToResolve.size() - Removed);
127 SpeculativeTypes.clear();
130 /// Recursively walk this pair of types, returning true if they are isomorphic,
131 /// false if they are not.
132 bool TypeMapTy::areTypesIsomorphic(Type *DstTy, Type *SrcTy) {
133 // Two types with differing kinds are clearly not isomorphic.
134 if (DstTy->getTypeID() != SrcTy->getTypeID()) return false;
136 // If we have an entry in the MappedTypes table, then we have our answer.
137 Type *&Entry = MappedTypes[SrcTy];
139 return Entry == DstTy;
141 // Two identical types are clearly isomorphic. Remember this
142 // non-speculatively.
143 if (DstTy == SrcTy) {
148 // Okay, we have two types with identical kinds that we haven't seen before.
150 // If this is an opaque struct type, special case it.
151 if (StructType *SSTy = dyn_cast<StructType>(SrcTy)) {
152 // Mapping an opaque type to any struct, just keep the dest struct.
153 if (SSTy->isOpaque()) {
155 SpeculativeTypes.push_back(SrcTy);
159 // Mapping a non-opaque source type to an opaque dest. If this is the first
160 // type that we're mapping onto this destination type then we succeed. Keep
161 // the dest, but fill it in later. If this is the second (different) type
162 // that we're trying to map onto the same opaque type then we fail.
163 if (cast<StructType>(DstTy)->isOpaque()) {
164 // We can only map one source type onto the opaque destination type.
165 if (!DstResolvedOpaqueTypes.insert(cast<StructType>(DstTy)).second)
167 SrcDefinitionsToResolve.push_back(SSTy);
168 SpeculativeTypes.push_back(SrcTy);
174 // If the number of subtypes disagree between the two types, then we fail.
175 if (SrcTy->getNumContainedTypes() != DstTy->getNumContainedTypes())
178 // Fail if any of the extra properties (e.g. array size) of the type disagree.
179 if (isa<IntegerType>(DstTy))
180 return false; // bitwidth disagrees.
181 if (PointerType *PT = dyn_cast<PointerType>(DstTy)) {
182 if (PT->getAddressSpace() != cast<PointerType>(SrcTy)->getAddressSpace())
185 } else if (FunctionType *FT = dyn_cast<FunctionType>(DstTy)) {
186 if (FT->isVarArg() != cast<FunctionType>(SrcTy)->isVarArg())
188 } else if (StructType *DSTy = dyn_cast<StructType>(DstTy)) {
189 StructType *SSTy = cast<StructType>(SrcTy);
190 if (DSTy->isLiteral() != SSTy->isLiteral() ||
191 DSTy->isPacked() != SSTy->isPacked())
193 } else if (ArrayType *DATy = dyn_cast<ArrayType>(DstTy)) {
194 if (DATy->getNumElements() != cast<ArrayType>(SrcTy)->getNumElements())
196 } else if (VectorType *DVTy = dyn_cast<VectorType>(DstTy)) {
197 if (DVTy->getNumElements() != cast<VectorType>(SrcTy)->getNumElements())
201 // Otherwise, we speculate that these two types will line up and recursively
202 // check the subelements.
204 SpeculativeTypes.push_back(SrcTy);
206 for (unsigned i = 0, e = SrcTy->getNumContainedTypes(); i != e; ++i)
207 if (!areTypesIsomorphic(DstTy->getContainedType(i),
208 SrcTy->getContainedType(i)))
211 // If everything seems to have lined up, then everything is great.
215 void TypeMapTy::linkDefinedTypeBodies() {
216 SmallVector<Type*, 16> Elements;
217 SmallString<16> TmpName;
219 // Note that processing entries in this loop (calling 'get') can add new
220 // entries to the SrcDefinitionsToResolve vector.
221 while (!SrcDefinitionsToResolve.empty()) {
222 StructType *SrcSTy = SrcDefinitionsToResolve.pop_back_val();
223 StructType *DstSTy = cast<StructType>(MappedTypes[SrcSTy]);
225 // TypeMap is a many-to-one mapping, if there were multiple types that
226 // provide a body for DstSTy then previous iterations of this loop may have
227 // already handled it. Just ignore this case.
228 if (!DstSTy->isOpaque()) continue;
229 assert(!SrcSTy->isOpaque() && "Not resolving a definition?");
231 // Map the body of the source type over to a new body for the dest type.
232 Elements.resize(SrcSTy->getNumElements());
233 for (unsigned i = 0, e = Elements.size(); i != e; ++i)
234 Elements[i] = getImpl(SrcSTy->getElementType(i));
236 DstSTy->setBody(Elements, SrcSTy->isPacked());
238 // If DstSTy has no name or has a longer name than STy, then viciously steal
240 if (!SrcSTy->hasName()) continue;
241 StringRef SrcName = SrcSTy->getName();
243 if (!DstSTy->hasName() || DstSTy->getName().size() > SrcName.size()) {
244 TmpName.insert(TmpName.end(), SrcName.begin(), SrcName.end());
246 DstSTy->setName(TmpName.str());
251 DstResolvedOpaqueTypes.clear();
254 Type *TypeMapTy::get(Type *Ty) {
255 Type *Result = getImpl(Ty);
257 // If this caused a reference to any struct type, resolve it before returning.
258 if (!SrcDefinitionsToResolve.empty())
259 linkDefinedTypeBodies();
263 /// This is the recursive version of get().
264 Type *TypeMapTy::getImpl(Type *Ty) {
265 // If we already have an entry for this type, return it.
266 Type **Entry = &MappedTypes[Ty];
267 if (*Entry) return *Entry;
269 // If this is not a named struct type, then just map all of the elements and
270 // then rebuild the type from inside out.
271 if (!isa<StructType>(Ty) || cast<StructType>(Ty)->isLiteral()) {
272 // If there are no element types to map, then the type is itself. This is
273 // true for the anonymous {} struct, things like 'float', integers, etc.
274 if (Ty->getNumContainedTypes() == 0)
277 // Remap all of the elements, keeping track of whether any of them change.
278 bool AnyChange = false;
279 SmallVector<Type*, 4> ElementTypes;
280 ElementTypes.resize(Ty->getNumContainedTypes());
281 for (unsigned i = 0, e = Ty->getNumContainedTypes(); i != e; ++i) {
282 ElementTypes[i] = getImpl(Ty->getContainedType(i));
283 AnyChange |= ElementTypes[i] != Ty->getContainedType(i);
286 // If we found our type while recursively processing stuff, just use it.
287 Entry = &MappedTypes[Ty];
288 if (*Entry) return *Entry;
290 // If all of the element types mapped directly over, then the type is usable
295 // Otherwise, rebuild a modified type.
296 switch (Ty->getTypeID()) {
297 default: llvm_unreachable("unknown derived type to remap");
298 case Type::ArrayTyID:
299 return *Entry = ArrayType::get(ElementTypes[0],
300 cast<ArrayType>(Ty)->getNumElements());
301 case Type::VectorTyID:
302 return *Entry = VectorType::get(ElementTypes[0],
303 cast<VectorType>(Ty)->getNumElements());
304 case Type::PointerTyID:
305 return *Entry = PointerType::get(ElementTypes[0],
306 cast<PointerType>(Ty)->getAddressSpace());
307 case Type::FunctionTyID:
308 return *Entry = FunctionType::get(ElementTypes[0],
309 makeArrayRef(ElementTypes).slice(1),
310 cast<FunctionType>(Ty)->isVarArg());
311 case Type::StructTyID:
312 // Note that this is only reached for anonymous structs.
313 return *Entry = StructType::get(Ty->getContext(), ElementTypes,
314 cast<StructType>(Ty)->isPacked());
318 // Otherwise, this is an unmapped named struct. If the struct can be directly
319 // mapped over, just use it as-is. This happens in a case when the linked-in
320 // module has something like:
321 // %T = type {%T*, i32}
322 // @GV = global %T* null
323 // where T does not exist at all in the destination module.
325 // The other case we watch for is when the type is not in the destination
326 // module, but that it has to be rebuilt because it refers to something that
327 // is already mapped. For example, if the destination module has:
329 // and the source module has something like
330 // %A' = type { i32 }
331 // %B = type { %A'* }
332 // @GV = global %B* null
333 // then we want to create a new type: "%B = type { %A*}" and have it take the
334 // pristine "%B" name from the source module.
336 // To determine which case this is, we have to recursively walk the type graph
337 // speculating that we'll be able to reuse it unmodified. Only if this is
338 // safe would we map the entire thing over. Because this is an optimization,
339 // and is not required for the prettiness of the linked module, we just skip
340 // it and always rebuild a type here.
341 StructType *STy = cast<StructType>(Ty);
343 // If the type is opaque, we can just use it directly.
344 if (STy->isOpaque()) {
345 // A named structure type from src module is used. Add it to the Set of
346 // identified structs in the destination module.
347 DstStructTypesSet.insert(STy);
351 // Otherwise we create a new type and resolve its body later. This will be
352 // resolved by the top level of get().
353 SrcDefinitionsToResolve.push_back(STy);
354 StructType *DTy = StructType::create(STy->getContext());
355 // A new identified structure type was created. Add it to the set of
356 // identified structs in the destination module.
357 DstStructTypesSet.insert(DTy);
358 DstResolvedOpaqueTypes.insert(DTy);
362 //===----------------------------------------------------------------------===//
363 // ModuleLinker implementation.
364 //===----------------------------------------------------------------------===//
369 /// Creates prototypes for functions that are lazily linked on the fly. This
370 /// speeds up linking for modules with many/ lazily linked functions of which
372 class ValueMaterializerTy : public ValueMaterializer {
375 std::vector<Function*> &LazilyLinkFunctions;
377 ValueMaterializerTy(TypeMapTy &TypeMap, Module *DstM,
378 std::vector<Function*> &LazilyLinkFunctions) :
379 ValueMaterializer(), TypeMap(TypeMap), DstM(DstM),
380 LazilyLinkFunctions(LazilyLinkFunctions) {
383 Value *materializeValueFor(Value *V) override;
387 class LinkDiagnosticInfo : public DiagnosticInfo {
391 LinkDiagnosticInfo(DiagnosticSeverity Severity, const Twine &Msg);
392 void print(DiagnosticPrinter &DP) const override;
394 LinkDiagnosticInfo::LinkDiagnosticInfo(DiagnosticSeverity Severity,
396 : DiagnosticInfo(DK_Linker, Severity), Msg(Msg) {}
397 void LinkDiagnosticInfo::print(DiagnosticPrinter &DP) const { DP << Msg; }
400 /// This is an implementation class for the LinkModules function, which is the
401 /// entrypoint for this file.
406 ValueMaterializerTy ValMaterializer;
408 /// Mapping of values from what they used to be in Src, to what they are now
409 /// in DstM. ValueToValueMapTy is a ValueMap, which involves some overhead
410 /// due to the use of Value handles which the Linker doesn't actually need,
411 /// but this allows us to reuse the ValueMapper code.
412 ValueToValueMapTy ValueMap;
414 struct AppendingVarInfo {
415 GlobalVariable *NewGV; // New aggregate global in dest module.
416 const Constant *DstInit; // Old initializer from dest module.
417 const Constant *SrcInit; // Old initializer from src module.
420 std::vector<AppendingVarInfo> AppendingVars;
422 // Set of items not to link in from source.
423 SmallPtrSet<const Value*, 16> DoNotLinkFromSource;
425 // Vector of functions to lazily link in.
426 std::vector<Function*> LazilyLinkFunctions;
428 Linker::DiagnosticHandlerFunction DiagnosticHandler;
431 ModuleLinker(Module *dstM, TypeSet &Set, Module *srcM,
432 Linker::DiagnosticHandlerFunction DiagnosticHandler)
433 : DstM(dstM), SrcM(srcM), TypeMap(Set),
434 ValMaterializer(TypeMap, DstM, LazilyLinkFunctions),
435 DiagnosticHandler(DiagnosticHandler) {}
440 bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
441 const GlobalValue &Src);
443 /// Helper method for setting a message and returning an error code.
444 bool emitError(const Twine &Message) {
445 DiagnosticHandler(LinkDiagnosticInfo(DS_Error, Message));
449 void emitWarning(const Twine &Message) {
450 DiagnosticHandler(LinkDiagnosticInfo(DS_Warning, Message));
453 bool getComdatLeader(Module *M, StringRef ComdatName,
454 const GlobalVariable *&GVar);
455 bool computeResultingSelectionKind(StringRef ComdatName,
456 Comdat::SelectionKind Src,
457 Comdat::SelectionKind Dst,
458 Comdat::SelectionKind &Result,
460 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
462 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
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(const 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,
492 const GlobalVariable *SrcGV);
494 bool linkGlobalValueProto(GlobalValue *GV);
495 GlobalValue *linkGlobalVariableProto(const GlobalVariable *SGVar,
496 GlobalValue *DGV, bool LinkFromSrc);
497 GlobalValue *linkFunctionProto(const Function *SF, GlobalValue *DGV,
499 GlobalValue *linkGlobalAliasProto(const GlobalAlias *SGA, GlobalValue *DGV,
502 bool linkModuleFlagsMetadata();
504 void linkAppendingVarInit(const AppendingVarInfo &AVI);
505 void linkGlobalInits();
506 void linkFunctionBody(Function *Dst, Function *Src);
507 void linkAliasBodies();
508 void linkNamedMDNodes();
512 /// The LLVM SymbolTable class autorenames globals that conflict in the symbol
513 /// table. This is good for all clients except for us. Go through the trouble
514 /// to force this back.
515 static void forceRenaming(GlobalValue *GV, StringRef Name) {
516 // If the global doesn't force its name or if it already has the right name,
517 // there is nothing for us to do.
518 if (GV->hasLocalLinkage() || GV->getName() == Name)
521 Module *M = GV->getParent();
523 // If there is a conflict, rename the conflict.
524 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
525 GV->takeName(ConflictGV);
526 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
527 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
529 GV->setName(Name); // Force the name back
533 /// copy additional attributes (those not needed to construct a GlobalValue)
534 /// from the SrcGV to the DestGV.
535 static void copyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) {
536 // Use the maximum alignment, rather than just copying the alignment of SrcGV.
537 auto *DestGO = dyn_cast<GlobalObject>(DestGV);
540 Alignment = std::max(DestGO->getAlignment(), SrcGV->getAlignment());
542 DestGV->copyAttributesFrom(SrcGV);
545 DestGO->setAlignment(Alignment);
547 forceRenaming(DestGV, SrcGV->getName());
550 static bool isLessConstraining(GlobalValue::VisibilityTypes a,
551 GlobalValue::VisibilityTypes b) {
552 if (a == GlobalValue::HiddenVisibility)
554 if (b == GlobalValue::HiddenVisibility)
556 if (a == GlobalValue::ProtectedVisibility)
558 if (b == GlobalValue::ProtectedVisibility)
563 Value *ValueMaterializerTy::materializeValueFor(Value *V) {
564 Function *SF = dyn_cast<Function>(V);
568 Function *DF = Function::Create(TypeMap.get(SF->getFunctionType()),
569 SF->getLinkage(), SF->getName(), DstM);
570 copyGVAttributes(DF, SF);
572 if (Comdat *SC = SF->getComdat()) {
573 Comdat *DC = DstM->getOrInsertComdat(SC->getName());
577 LazilyLinkFunctions.push_back(SF);
581 bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName,
582 const GlobalVariable *&GVar) {
583 const GlobalValue *GVal = M->getNamedValue(ComdatName);
584 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
585 GVal = GA->getBaseObject();
587 // We cannot resolve the size of the aliasee yet.
588 return emitError("Linking COMDATs named '" + ComdatName +
589 "': COMDAT key involves incomputable alias size.");
592 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
595 "Linking COMDATs named '" + ComdatName +
596 "': GlobalVariable required for data dependent selection!");
601 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
602 Comdat::SelectionKind Src,
603 Comdat::SelectionKind Dst,
604 Comdat::SelectionKind &Result,
606 // The ability to mix Comdat::SelectionKind::Any with
607 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
608 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
609 Dst == Comdat::SelectionKind::Largest;
610 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
611 Src == Comdat::SelectionKind::Largest;
612 if (DstAnyOrLargest && SrcAnyOrLargest) {
613 if (Dst == Comdat::SelectionKind::Largest ||
614 Src == Comdat::SelectionKind::Largest)
615 Result = Comdat::SelectionKind::Largest;
617 Result = Comdat::SelectionKind::Any;
618 } else if (Src == Dst) {
621 return emitError("Linking COMDATs named '" + ComdatName +
622 "': invalid selection kinds!");
626 case Comdat::SelectionKind::Any:
630 case Comdat::SelectionKind::NoDuplicates:
631 return emitError("Linking COMDATs named '" + ComdatName +
632 "': noduplicates has been violated!");
633 case Comdat::SelectionKind::ExactMatch:
634 case Comdat::SelectionKind::Largest:
635 case Comdat::SelectionKind::SameSize: {
636 const GlobalVariable *DstGV;
637 const GlobalVariable *SrcGV;
638 if (getComdatLeader(DstM, ComdatName, DstGV) ||
639 getComdatLeader(SrcM, ComdatName, SrcGV))
642 const DataLayout *DstDL = DstM->getDataLayout();
643 const DataLayout *SrcDL = SrcM->getDataLayout();
644 if (!DstDL || !SrcDL) {
646 "Linking COMDATs named '" + ComdatName +
647 "': can't do size dependent selection without DataLayout!");
650 DstDL->getTypeAllocSize(DstGV->getType()->getPointerElementType());
652 SrcDL->getTypeAllocSize(SrcGV->getType()->getPointerElementType());
653 if (Result == Comdat::SelectionKind::ExactMatch) {
654 if (SrcGV->getInitializer() != DstGV->getInitializer())
655 return emitError("Linking COMDATs named '" + ComdatName +
656 "': ExactMatch violated!");
658 } else if (Result == Comdat::SelectionKind::Largest) {
659 LinkFromSrc = SrcSize > DstSize;
660 } else if (Result == Comdat::SelectionKind::SameSize) {
661 if (SrcSize != DstSize)
662 return emitError("Linking COMDATs named '" + ComdatName +
663 "': SameSize violated!");
666 llvm_unreachable("unknown selection kind");
675 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
676 Comdat::SelectionKind &Result,
678 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
679 StringRef ComdatName = SrcC->getName();
680 Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable();
681 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
683 if (DstCI == ComdatSymTab.end()) {
684 // Use the comdat if it is only available in one of the modules.
690 const Comdat *DstC = &DstCI->second;
691 Comdat::SelectionKind DSK = DstC->getSelectionKind();
692 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
696 bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
697 const GlobalValue &Dest,
698 const GlobalValue &Src) {
699 // We always have to add Src if it has appending linkage.
700 if (Src.hasAppendingLinkage()) {
705 bool SrcIsDeclaration = Src.isDeclarationForLinker();
706 bool DestIsDeclaration = Dest.isDeclarationForLinker();
708 if (SrcIsDeclaration) {
709 // If Src is external or if both Src & Dest are external.. Just link the
710 // external globals, we aren't adding anything.
711 if (Src.hasDLLImportStorageClass()) {
712 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
713 LinkFromSrc = DestIsDeclaration;
716 // If the Dest is weak, use the source linkage.
717 LinkFromSrc = Dest.hasExternalWeakLinkage();
721 if (DestIsDeclaration) {
722 // If Dest is external but Src is not:
727 if (Src.hasCommonLinkage()) {
728 if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
733 if (!Dest.hasCommonLinkage()) {
738 // FIXME: Make datalayout mandatory and just use getDataLayout().
739 DataLayout DL(Dest.getParent());
741 uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
742 uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
743 LinkFromSrc = SrcSize > DestSize;
747 if (Src.isWeakForLinker()) {
748 assert(!Dest.hasExternalWeakLinkage());
749 assert(!Dest.hasAvailableExternallyLinkage());
751 if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
760 if (Dest.isWeakForLinker()) {
761 assert(Src.hasExternalLinkage());
766 assert(!Src.hasExternalWeakLinkage());
767 assert(!Dest.hasExternalWeakLinkage());
768 assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
769 "Unexpected linkage type!");
770 return emitError("Linking globals named '" + Src.getName() +
771 "': symbol multiply defined!");
774 /// Loop over all of the linked values to compute type mappings. For example,
775 /// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct
776 /// types 'Foo' but one got renamed when the module was loaded into the same
778 void ModuleLinker::computeTypeMapping() {
779 for (GlobalValue &SGV : SrcM->globals()) {
780 GlobalValue *DGV = getLinkedToGlobal(&SGV);
784 if (!DGV->hasAppendingLinkage() || !SGV.hasAppendingLinkage()) {
785 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
789 // Unify the element type of appending arrays.
790 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
791 ArrayType *SAT = cast<ArrayType>(SGV.getType()->getElementType());
792 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
795 for (GlobalValue &SGV : *SrcM) {
796 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
797 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
800 for (GlobalValue &SGV : SrcM->aliases()) {
801 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
802 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
805 // Incorporate types by name, scanning all the types in the source module.
806 // At this point, the destination module may have a type "%foo = { i32 }" for
807 // example. When the source module got loaded into the same LLVMContext, if
808 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
809 TypeFinder SrcStructTypes;
810 SrcStructTypes.run(*SrcM, true);
811 SmallPtrSet<StructType*, 32> SrcStructTypesSet(SrcStructTypes.begin(),
812 SrcStructTypes.end());
814 for (unsigned i = 0, e = SrcStructTypes.size(); i != e; ++i) {
815 StructType *ST = SrcStructTypes[i];
816 if (!ST->hasName()) continue;
818 // Check to see if there is a dot in the name followed by a digit.
819 size_t DotPos = ST->getName().rfind('.');
820 if (DotPos == 0 || DotPos == StringRef::npos ||
821 ST->getName().back() == '.' ||
822 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos+1])))
825 // Check to see if the destination module has a struct with the prefix name.
826 if (StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos)))
827 // Don't use it if this actually came from the source module. They're in
828 // the same LLVMContext after all. Also don't use it unless the type is
829 // actually used in the destination module. This can happen in situations
834 // %Z = type { %A } %B = type { %C.1 }
835 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
836 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
837 // %C = type { i8* } %B.3 = type { %C.1 }
839 // When we link Module B with Module A, the '%B' in Module B is
840 // used. However, that would then use '%C.1'. But when we process '%C.1',
841 // we prefer to take the '%C' version. So we are then left with both
842 // '%C.1' and '%C' being used for the same types. This leads to some
843 // variables using one type and some using the other.
844 if (!SrcStructTypesSet.count(DST) && TypeMap.DstStructTypesSet.count(DST))
845 TypeMap.addTypeMapping(DST, ST);
848 // Now that we have discovered all of the type equivalences, get a body for
849 // any 'opaque' types in the dest module that are now resolved.
850 TypeMap.linkDefinedTypeBodies();
853 static void upgradeGlobalArray(GlobalVariable *GV) {
854 ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
855 StructType *OldTy = cast<StructType>(ATy->getElementType());
856 assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
858 // Get the upgraded 3 element type.
859 PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
860 Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
862 StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
864 // Build new constants with a null third field filled in.
865 Constant *OldInitC = GV->getInitializer();
866 ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
867 if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
868 // Invalid initializer; give up.
870 std::vector<Constant *> Initializers;
871 if (OldInit && OldInit->getNumOperands()) {
872 Value *Null = Constant::getNullValue(VoidPtrTy);
873 for (Use &U : OldInit->operands()) {
874 ConstantStruct *Init = cast<ConstantStruct>(U.get());
875 Initializers.push_back(ConstantStruct::get(
876 NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
879 assert(Initializers.size() == ATy->getNumElements() &&
880 "Failed to copy all array elements");
882 // Replace the old GV with a new one.
883 ATy = ArrayType::get(NewTy, Initializers.size());
884 Constant *NewInit = ConstantArray::get(ATy, Initializers);
885 GlobalVariable *NewGV = new GlobalVariable(
886 *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
887 GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
888 GV->isExternallyInitialized());
889 NewGV->copyAttributesFrom(GV);
891 assert(GV->use_empty() && "program cannot use initializer list");
892 GV->eraseFromParent();
895 void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
896 // Look for the global arrays.
897 auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM->getNamedValue(Name));
900 auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM->getNamedValue(Name));
904 // Check if the types already match.
905 auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
907 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
911 // Grab the element types. We can only upgrade an array of a two-field
912 // struct. Only bother if the other one has three-fields.
913 auto *DstEltTy = cast<StructType>(DstTy->getElementType());
914 auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
915 if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
916 upgradeGlobalArray(DstGV);
919 if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
920 upgradeGlobalArray(SrcGV);
922 // We can't upgrade any other differences.
925 void ModuleLinker::upgradeMismatchedGlobals() {
926 upgradeMismatchedGlobalArray("llvm.global_ctors");
927 upgradeMismatchedGlobalArray("llvm.global_dtors");
930 /// If there were any appending global variables, link them together now.
931 /// Return true on error.
932 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
933 const GlobalVariable *SrcGV) {
935 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
936 return emitError("Linking globals named '" + SrcGV->getName() +
937 "': can only link appending global with another appending global!");
939 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
941 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
942 Type *EltTy = DstTy->getElementType();
944 // Check to see that they two arrays agree on type.
945 if (EltTy != SrcTy->getElementType())
946 return emitError("Appending variables with different element types!");
947 if (DstGV->isConstant() != SrcGV->isConstant())
948 return emitError("Appending variables linked with different const'ness!");
950 if (DstGV->getAlignment() != SrcGV->getAlignment())
952 "Appending variables with different alignment need to be linked!");
954 if (DstGV->getVisibility() != SrcGV->getVisibility())
956 "Appending variables with different visibility need to be linked!");
958 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
960 "Appending variables with different unnamed_addr need to be linked!");
962 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
964 "Appending variables with different section name need to be linked!");
966 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements();
967 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
969 // Create the new global variable.
971 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(),
972 DstGV->getLinkage(), /*init*/nullptr, /*name*/"", DstGV,
973 DstGV->getThreadLocalMode(),
974 DstGV->getType()->getAddressSpace());
976 // Propagate alignment, visibility and section info.
977 copyGVAttributes(NG, DstGV);
979 AppendingVarInfo AVI;
981 AVI.DstInit = DstGV->getInitializer();
982 AVI.SrcInit = SrcGV->getInitializer();
983 AppendingVars.push_back(AVI);
985 // Replace any uses of the two global variables with uses of the new
987 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
989 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
990 DstGV->eraseFromParent();
992 // Track the source variable so we don't try to link it.
993 DoNotLinkFromSource.insert(SrcGV);
998 bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) {
999 GlobalValue *DGV = getLinkedToGlobal(SGV);
1001 // Handle the ultra special appending linkage case first.
1002 if (DGV && DGV->hasAppendingLinkage())
1003 return linkAppendingVarProto(cast<GlobalVariable>(DGV),
1004 cast<GlobalVariable>(SGV));
1006 bool LinkFromSrc = true;
1007 Comdat *C = nullptr;
1008 GlobalValue::VisibilityTypes Visibility = SGV->getVisibility();
1009 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
1011 if (const Comdat *SC = SGV->getComdat()) {
1012 Comdat::SelectionKind SK;
1013 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1014 C = DstM->getOrInsertComdat(SC->getName());
1015 C->setSelectionKind(SK);
1017 if (shouldLinkFromSource(LinkFromSrc, *DGV, *SGV))
1022 // Track the source global so that we don't attempt to copy it over when
1023 // processing global initializers.
1024 DoNotLinkFromSource.insert(SGV);
1027 // Make sure to remember this mapping.
1029 ConstantExpr::getBitCast(DGV, TypeMap.get(SGV->getType()));
1033 Visibility = isLessConstraining(Visibility, DGV->getVisibility())
1034 ? DGV->getVisibility()
1036 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1039 if (!LinkFromSrc && !DGV)
1043 if (auto *SGVar = dyn_cast<GlobalVariable>(SGV)) {
1044 NewGV = linkGlobalVariableProto(SGVar, DGV, LinkFromSrc);
1047 } else if (auto *SF = dyn_cast<Function>(SGV)) {
1048 NewGV = linkFunctionProto(SF, DGV, LinkFromSrc);
1050 NewGV = linkGlobalAliasProto(cast<GlobalAlias>(SGV), DGV, LinkFromSrc);
1055 copyGVAttributes(NewGV, SGV);
1057 NewGV->setUnnamedAddr(HasUnnamedAddr);
1058 NewGV->setVisibility(Visibility);
1060 if (auto *NewGO = dyn_cast<GlobalObject>(NewGV)) {
1062 NewGO->setComdat(C);
1065 // Make sure to remember this mapping.
1068 DGV->replaceAllUsesWith(
1069 ConstantExpr::getBitCast(NewGV, DGV->getType()));
1070 DGV->eraseFromParent();
1072 ValueMap[SGV] = NewGV;
1079 /// Loop through the global variables in the src module and merge them into the
1081 GlobalValue *ModuleLinker::linkGlobalVariableProto(const GlobalVariable *SGVar,
1084 unsigned Alignment = 0;
1085 bool ClearConstant = false;
1088 if (DGV->hasCommonLinkage() && SGVar->hasCommonLinkage())
1089 Alignment = std::max(SGVar->getAlignment(), DGV->getAlignment());
1091 auto *DGVar = dyn_cast<GlobalVariable>(DGV);
1092 if (!SGVar->isConstant() || (DGVar && !DGVar->isConstant()))
1093 ClearConstant = true;
1097 if (auto *NewGVar = dyn_cast<GlobalVariable>(DGV)) {
1099 NewGVar->setAlignment(Alignment);
1100 if (NewGVar->isDeclaration() && ClearConstant)
1101 NewGVar->setConstant(false);
1106 // No linking to be performed or linking from the source: simply create an
1107 // identical version of the symbol over in the dest module... the
1108 // initializer will be filled in later by LinkGlobalInits.
1109 GlobalVariable *NewDGV = new GlobalVariable(
1110 *DstM, TypeMap.get(SGVar->getType()->getElementType()),
1111 SGVar->isConstant(), SGVar->getLinkage(), /*init*/ nullptr,
1112 SGVar->getName(), /*insertbefore*/ nullptr, SGVar->getThreadLocalMode(),
1113 SGVar->getType()->getAddressSpace());
1116 NewDGV->setAlignment(Alignment);
1121 /// Link the function in the source module into the destination module if
1122 /// needed, setting up mapping information.
1123 GlobalValue *ModuleLinker::linkFunctionProto(const Function *SF,
1129 // If the function is to be lazily linked, don't create it just yet.
1130 // The ValueMaterializerTy will deal with creating it if it's used.
1131 if (!DGV && (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() ||
1132 SF->hasAvailableExternallyLinkage())) {
1133 DoNotLinkFromSource.insert(SF);
1137 // If there is no linkage to be performed or we are linking from the source,
1139 return Function::Create(TypeMap.get(SF->getFunctionType()), SF->getLinkage(),
1140 SF->getName(), DstM);
1143 /// Set up prototypes for any aliases that come over from the source module.
1144 GlobalValue *ModuleLinker::linkGlobalAliasProto(const GlobalAlias *SGA,
1150 // If there is no linkage to be performed or we're linking from the source,
1152 auto *PTy = cast<PointerType>(TypeMap.get(SGA->getType()));
1153 return GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(),
1154 SGA->getLinkage(), SGA->getName(), DstM);
1157 static void getArrayElements(const Constant *C,
1158 SmallVectorImpl<Constant *> &Dest) {
1159 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1161 for (unsigned i = 0; i != NumElements; ++i)
1162 Dest.push_back(C->getAggregateElement(i));
1165 void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) {
1166 // Merge the initializer.
1167 SmallVector<Constant *, 16> DstElements;
1168 getArrayElements(AVI.DstInit, DstElements);
1170 SmallVector<Constant *, 16> SrcElements;
1171 getArrayElements(AVI.SrcInit, SrcElements);
1173 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
1175 StringRef Name = AVI.NewGV->getName();
1176 bool IsNewStructor =
1177 (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
1178 cast<StructType>(NewType->getElementType())->getNumElements() == 3;
1180 for (auto *V : SrcElements) {
1181 if (IsNewStructor) {
1182 Constant *Key = V->getAggregateElement(2);
1183 if (DoNotLinkFromSource.count(Key))
1186 DstElements.push_back(
1187 MapValue(V, ValueMap, RF_None, &TypeMap, &ValMaterializer));
1189 if (IsNewStructor) {
1190 NewType = ArrayType::get(NewType->getElementType(), DstElements.size());
1191 AVI.NewGV->mutateType(PointerType::get(NewType, 0));
1194 AVI.NewGV->setInitializer(ConstantArray::get(NewType, DstElements));
1197 /// Update the initializers in the Dest module now that all globals that may be
1198 /// referenced are in Dest.
1199 void ModuleLinker::linkGlobalInits() {
1200 // Loop over all of the globals in the src module, mapping them over as we go
1201 for (Module::const_global_iterator I = SrcM->global_begin(),
1202 E = SrcM->global_end(); I != E; ++I) {
1204 // Only process initialized GV's or ones not already in dest.
1205 if (!I->hasInitializer() || DoNotLinkFromSource.count(I)) continue;
1207 // Grab destination global variable.
1208 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[I]);
1209 // Figure out what the initializer looks like in the dest module.
1210 DGV->setInitializer(MapValue(I->getInitializer(), ValueMap,
1211 RF_None, &TypeMap, &ValMaterializer));
1215 /// Copy the source function over into the dest function and fix up references
1216 /// to values. At this point we know that Dest is an external function, and
1217 /// that Src is not.
1218 void ModuleLinker::linkFunctionBody(Function *Dst, Function *Src) {
1219 assert(Src && Dst && Dst->isDeclaration() && !Src->isDeclaration());
1221 // Go through and convert function arguments over, remembering the mapping.
1222 Function::arg_iterator DI = Dst->arg_begin();
1223 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1224 I != E; ++I, ++DI) {
1225 DI->setName(I->getName()); // Copy the name over.
1227 // Add a mapping to our mapping.
1231 // Splice the body of the source function into the dest function.
1232 Dst->getBasicBlockList().splice(Dst->end(), Src->getBasicBlockList());
1234 // At this point, all of the instructions and values of the function are now
1235 // copied over. The only problem is that they are still referencing values in
1236 // the Source function as operands. Loop through all of the operands of the
1237 // functions and patch them up to point to the local versions.
1238 for (Function::iterator BB = Dst->begin(), BE = Dst->end(); BB != BE; ++BB)
1239 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
1240 RemapInstruction(I, ValueMap, RF_IgnoreMissingEntries, &TypeMap,
1243 // There is no need to map the arguments anymore.
1244 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1250 /// Insert all of the aliases in Src into the Dest module.
1251 void ModuleLinker::linkAliasBodies() {
1252 for (Module::alias_iterator I = SrcM->alias_begin(), E = SrcM->alias_end();
1254 if (DoNotLinkFromSource.count(I))
1256 if (Constant *Aliasee = I->getAliasee()) {
1257 GlobalAlias *DA = cast<GlobalAlias>(ValueMap[I]);
1259 MapValue(Aliasee, ValueMap, RF_None, &TypeMap, &ValMaterializer);
1260 DA->setAliasee(Val);
1265 /// Insert all of the named MDNodes in Src into the Dest module.
1266 void ModuleLinker::linkNamedMDNodes() {
1267 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1268 for (Module::const_named_metadata_iterator I = SrcM->named_metadata_begin(),
1269 E = SrcM->named_metadata_end(); I != E; ++I) {
1270 // Don't link module flags here. Do them separately.
1271 if (&*I == SrcModFlags) continue;
1272 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(I->getName());
1273 // Add Src elements into Dest node.
1274 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
1275 DestNMD->addOperand(MapValue(I->getOperand(i), ValueMap,
1276 RF_None, &TypeMap, &ValMaterializer));
1280 /// Merge the linker flags in Src into the Dest module.
1281 bool ModuleLinker::linkModuleFlagsMetadata() {
1282 // If the source module has no module flags, we are done.
1283 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1284 if (!SrcModFlags) return false;
1286 // If the destination module doesn't have module flags yet, then just copy
1287 // over the source module's flags.
1288 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
1289 if (DstModFlags->getNumOperands() == 0) {
1290 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1291 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1296 // First build a map of the existing module flags and requirements.
1297 DenseMap<MDString*, MDNode*> Flags;
1298 SmallSetVector<MDNode*, 16> Requirements;
1299 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1300 MDNode *Op = DstModFlags->getOperand(I);
1301 ConstantInt *Behavior = cast<ConstantInt>(Op->getOperand(0));
1302 MDString *ID = cast<MDString>(Op->getOperand(1));
1304 if (Behavior->getZExtValue() == Module::Require) {
1305 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1311 // Merge in the flags from the source module, and also collect its set of
1313 bool HasErr = false;
1314 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1315 MDNode *SrcOp = SrcModFlags->getOperand(I);
1316 ConstantInt *SrcBehavior = cast<ConstantInt>(SrcOp->getOperand(0));
1317 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1318 MDNode *DstOp = Flags.lookup(ID);
1319 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1321 // If this is a requirement, add it and continue.
1322 if (SrcBehaviorValue == Module::Require) {
1323 // If the destination module does not already have this requirement, add
1325 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1326 DstModFlags->addOperand(SrcOp);
1331 // If there is no existing flag with this ID, just add it.
1334 DstModFlags->addOperand(SrcOp);
1338 // Otherwise, perform a merge.
1339 ConstantInt *DstBehavior = cast<ConstantInt>(DstOp->getOperand(0));
1340 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1342 // If either flag has override behavior, handle it first.
1343 if (DstBehaviorValue == Module::Override) {
1344 // Diagnose inconsistent flags which both have override behavior.
1345 if (SrcBehaviorValue == Module::Override &&
1346 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1347 HasErr |= emitError("linking module flags '" + ID->getString() +
1348 "': IDs have conflicting override values");
1351 } else if (SrcBehaviorValue == Module::Override) {
1352 // Update the destination flag to that of the source.
1353 DstOp->replaceOperandWith(0, SrcBehavior);
1354 DstOp->replaceOperandWith(2, SrcOp->getOperand(2));
1358 // Diagnose inconsistent merge behavior types.
1359 if (SrcBehaviorValue != DstBehaviorValue) {
1360 HasErr |= emitError("linking module flags '" + ID->getString() +
1361 "': IDs have conflicting behaviors");
1365 // Perform the merge for standard behavior types.
1366 switch (SrcBehaviorValue) {
1367 case Module::Require:
1368 case Module::Override: llvm_unreachable("not possible");
1369 case Module::Error: {
1370 // Emit an error if the values differ.
1371 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1372 HasErr |= emitError("linking module flags '" + ID->getString() +
1373 "': IDs have conflicting values");
1377 case Module::Warning: {
1378 // Emit a warning if the values differ.
1379 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1380 emitWarning("linking module flags '" + ID->getString() +
1381 "': IDs have conflicting values");
1385 case Module::Append: {
1386 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1387 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1388 unsigned NumOps = DstValue->getNumOperands() + SrcValue->getNumOperands();
1389 Value **VP, **Values = VP = new Value*[NumOps];
1390 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i, ++VP)
1391 *VP = DstValue->getOperand(i);
1392 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i, ++VP)
1393 *VP = SrcValue->getOperand(i);
1394 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1395 ArrayRef<Value*>(Values,
1400 case Module::AppendUnique: {
1401 SmallSetVector<Value*, 16> Elts;
1402 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1403 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1404 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i)
1405 Elts.insert(DstValue->getOperand(i));
1406 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i)
1407 Elts.insert(SrcValue->getOperand(i));
1408 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1409 ArrayRef<Value*>(Elts.begin(),
1416 // Check all of the requirements.
1417 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1418 MDNode *Requirement = Requirements[I];
1419 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1420 Value *ReqValue = Requirement->getOperand(1);
1422 MDNode *Op = Flags[Flag];
1423 if (!Op || Op->getOperand(2) != ReqValue) {
1424 HasErr |= emitError("linking module flags '" + Flag->getString() +
1425 "': does not have the required value");
1433 bool ModuleLinker::run() {
1434 assert(DstM && "Null destination module");
1435 assert(SrcM && "Null source module");
1437 // Inherit the target data from the source module if the destination module
1438 // doesn't have one already.
1439 if (!DstM->getDataLayout() && SrcM->getDataLayout())
1440 DstM->setDataLayout(SrcM->getDataLayout());
1442 // Copy the target triple from the source to dest if the dest's is empty.
1443 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
1444 DstM->setTargetTriple(SrcM->getTargetTriple());
1446 if (SrcM->getDataLayout() && DstM->getDataLayout() &&
1447 *SrcM->getDataLayout() != *DstM->getDataLayout()) {
1448 emitWarning("Linking two modules of different data layouts: '" +
1449 SrcM->getModuleIdentifier() + "' is '" +
1450 SrcM->getDataLayoutStr() + "' whereas '" +
1451 DstM->getModuleIdentifier() + "' is '" +
1452 DstM->getDataLayoutStr() + "'\n");
1454 if (!SrcM->getTargetTriple().empty() &&
1455 DstM->getTargetTriple() != SrcM->getTargetTriple()) {
1456 emitWarning("Linking two modules of different target triples: " +
1457 SrcM->getModuleIdentifier() + "' is '" +
1458 SrcM->getTargetTriple() + "' whereas '" +
1459 DstM->getModuleIdentifier() + "' is '" +
1460 DstM->getTargetTriple() + "'\n");
1463 // Append the module inline asm string.
1464 if (!SrcM->getModuleInlineAsm().empty()) {
1465 if (DstM->getModuleInlineAsm().empty())
1466 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
1468 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
1469 SrcM->getModuleInlineAsm());
1472 // Loop over all of the linked values to compute type mappings.
1473 computeTypeMapping();
1475 ComdatsChosen.clear();
1476 for (const auto &SMEC : SrcM->getComdatSymbolTable()) {
1477 const Comdat &C = SMEC.getValue();
1478 if (ComdatsChosen.count(&C))
1480 Comdat::SelectionKind SK;
1482 if (getComdatResult(&C, SK, LinkFromSrc))
1484 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1487 // Upgrade mismatched global arrays.
1488 upgradeMismatchedGlobals();
1490 // Insert all of the globals in src into the DstM module... without linking
1491 // initializers (which could refer to functions not yet mapped over).
1492 for (Module::global_iterator I = SrcM->global_begin(),
1493 E = SrcM->global_end(); I != E; ++I)
1494 if (linkGlobalValueProto(I))
1497 // Link the functions together between the two modules, without doing function
1498 // bodies... this just adds external function prototypes to the DstM
1499 // function... We do this so that when we begin processing function bodies,
1500 // all of the global values that may be referenced are available in our
1502 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I)
1503 if (linkGlobalValueProto(I))
1506 // If there were any aliases, link them now.
1507 for (Module::alias_iterator I = SrcM->alias_begin(),
1508 E = SrcM->alias_end(); I != E; ++I)
1509 if (linkGlobalValueProto(I))
1512 for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i)
1513 linkAppendingVarInit(AppendingVars[i]);
1515 // Link in the function bodies that are defined in the source module into
1517 for (Module::iterator SF = SrcM->begin(), E = SrcM->end(); SF != E; ++SF) {
1518 // Skip if not linking from source.
1519 if (DoNotLinkFromSource.count(SF)) continue;
1521 Function *DF = cast<Function>(ValueMap[SF]);
1522 if (SF->hasPrefixData()) {
1523 // Link in the prefix data.
1524 DF->setPrefixData(MapValue(
1525 SF->getPrefixData(), ValueMap, RF_None, &TypeMap, &ValMaterializer));
1528 // Materialize if needed.
1529 if (std::error_code EC = SF->materialize())
1530 return emitError(EC.message());
1532 // Skip if no body (function is external).
1533 if (SF->isDeclaration())
1536 linkFunctionBody(DF, SF);
1537 SF->Dematerialize();
1540 // Resolve all uses of aliases with aliasees.
1543 // Remap all of the named MDNodes in Src into the DstM module. We do this
1544 // after linking GlobalValues so that MDNodes that reference GlobalValues
1545 // are properly remapped.
1548 // Merge the module flags into the DstM module.
1549 if (linkModuleFlagsMetadata())
1552 // Update the initializers in the DstM module now that all globals that may
1553 // be referenced are in DstM.
1556 // Process vector of lazily linked in functions.
1557 bool LinkedInAnyFunctions;
1559 LinkedInAnyFunctions = false;
1561 for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(),
1562 E = LazilyLinkFunctions.end(); I != E; ++I) {
1567 Function *DF = cast<Function>(ValueMap[SF]);
1568 if (SF->hasPrefixData()) {
1569 // Link in the prefix data.
1570 DF->setPrefixData(MapValue(SF->getPrefixData(),
1577 // Materialize if needed.
1578 if (std::error_code EC = SF->materialize())
1579 return emitError(EC.message());
1581 // Skip if no body (function is external).
1582 if (SF->isDeclaration())
1585 // Erase from vector *before* the function body is linked - linkFunctionBody could
1587 LazilyLinkFunctions.erase(I);
1589 // Link in function body.
1590 linkFunctionBody(DF, SF);
1591 SF->Dematerialize();
1593 // Set flag to indicate we may have more functions to lazily link in
1594 // since we linked in a function.
1595 LinkedInAnyFunctions = true;
1598 } while (LinkedInAnyFunctions);
1600 // Now that all of the types from the source are used, resolve any structs
1601 // copied over to the dest that didn't exist there.
1602 TypeMap.linkDefinedTypeBodies();
1607 void Linker::init(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
1608 this->Composite = M;
1609 this->DiagnosticHandler = DiagnosticHandler;
1611 TypeFinder StructTypes;
1612 StructTypes.run(*M, true);
1613 IdentifiedStructTypes.insert(StructTypes.begin(), StructTypes.end());
1616 Linker::Linker(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
1617 init(M, DiagnosticHandler);
1620 Linker::Linker(Module *M) {
1621 init(M, [this](const DiagnosticInfo &DI) {
1622 Composite->getContext().diagnose(DI);
1629 void Linker::deleteModule() {
1631 Composite = nullptr;
1634 bool Linker::linkInModule(Module *Src) {
1635 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,
1637 return TheLinker.run();
1640 //===----------------------------------------------------------------------===//
1641 // LinkModules entrypoint.
1642 //===----------------------------------------------------------------------===//
1644 /// This function links two modules together, with the resulting Dest module
1645 /// modified to be the composite of the two input modules. If an error occurs,
1646 /// true is returned and ErrorMsg (if not null) is set to indicate the problem.
1647 /// Upon failure, the Dest module could be in a modified state, and shouldn't be
1648 /// relied on to be consistent.
1649 bool Linker::LinkModules(Module *Dest, Module *Src,
1650 DiagnosticHandlerFunction DiagnosticHandler) {
1651 Linker L(Dest, DiagnosticHandler);
1652 return L.linkInModule(Src);
1655 bool Linker::LinkModules(Module *Dest, Module *Src) {
1657 return L.linkInModule(Src);
1660 //===----------------------------------------------------------------------===//
1662 //===----------------------------------------------------------------------===//
1664 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
1665 LLVMLinkerMode Mode, char **OutMessages) {
1666 Module *D = unwrap(Dest);
1667 std::string Message;
1668 raw_string_ostream Stream(Message);
1669 DiagnosticPrinterRawOStream DP(Stream);
1671 LLVMBool Result = Linker::LinkModules(
1672 D, unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); });
1674 if (OutMessages && Result)
1675 *OutMessages = strdup(Message.c_str());