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;
386 class LinkDiagnosticInfo : public DiagnosticInfo {
390 LinkDiagnosticInfo(DiagnosticSeverity Severity, const Twine &Msg);
391 void print(DiagnosticPrinter &DP) const override;
393 LinkDiagnosticInfo::LinkDiagnosticInfo(DiagnosticSeverity Severity,
395 : DiagnosticInfo(DK_Linker, Severity), Msg(Msg) {}
396 void LinkDiagnosticInfo::print(DiagnosticPrinter &DP) const { DP << Msg; }
398 /// This is an implementation class for the LinkModules function, which is the
399 /// entrypoint for this file.
404 ValueMaterializerTy ValMaterializer;
406 /// Mapping of values from what they used to be in Src, to what they are now
407 /// in DstM. ValueToValueMapTy is a ValueMap, which involves some overhead
408 /// due to the use of Value handles which the Linker doesn't actually need,
409 /// but this allows us to reuse the ValueMapper code.
410 ValueToValueMapTy ValueMap;
412 struct AppendingVarInfo {
413 GlobalVariable *NewGV; // New aggregate global in dest module.
414 const Constant *DstInit; // Old initializer from dest module.
415 const Constant *SrcInit; // Old initializer from src module.
418 std::vector<AppendingVarInfo> AppendingVars;
420 // Set of items not to link in from source.
421 SmallPtrSet<const Value*, 16> DoNotLinkFromSource;
423 // Vector of functions to lazily link in.
424 std::vector<Function*> LazilyLinkFunctions;
426 Linker::DiagnosticHandlerFunction DiagnosticHandler;
429 ModuleLinker(Module *dstM, TypeSet &Set, Module *srcM,
430 Linker::DiagnosticHandlerFunction DiagnosticHandler)
431 : DstM(dstM), SrcM(srcM), TypeMap(Set),
432 ValMaterializer(TypeMap, DstM, LazilyLinkFunctions),
433 DiagnosticHandler(DiagnosticHandler) {}
438 bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
439 const GlobalValue &Src);
441 /// Helper method for setting a message and returning an error code.
442 bool emitError(const Twine &Message) {
443 DiagnosticHandler(LinkDiagnosticInfo(DS_Error, Message));
447 void emitWarning(const Twine &Message) {
448 DiagnosticHandler(LinkDiagnosticInfo(DS_Warning, Message));
451 bool getComdatLeader(Module *M, StringRef ComdatName,
452 const GlobalVariable *&GVar);
453 bool computeResultingSelectionKind(StringRef ComdatName,
454 Comdat::SelectionKind Src,
455 Comdat::SelectionKind Dst,
456 Comdat::SelectionKind &Result,
458 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
460 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
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);
492 bool linkGlobalValueProto(GlobalValue *GV);
493 GlobalValue *linkGlobalVariableProto(const GlobalVariable *SGVar,
494 GlobalValue *DGV, bool LinkFromSrc);
495 GlobalValue *linkFunctionProto(const Function *SF, GlobalValue *DGV,
497 GlobalValue *linkGlobalAliasProto(const GlobalAlias *SGA, GlobalValue *DGV,
500 bool linkModuleFlagsMetadata();
502 void linkAppendingVarInit(const AppendingVarInfo &AVI);
503 void linkGlobalInits();
504 void linkFunctionBody(Function *Dst, Function *Src);
505 void linkAliasBodies();
506 void linkNamedMDNodes();
510 /// The LLVM SymbolTable class autorenames globals that conflict in the symbol
511 /// table. This is good for all clients except for us. Go through the trouble
512 /// to force this back.
513 static void forceRenaming(GlobalValue *GV, StringRef Name) {
514 // If the global doesn't force its name or if it already has the right name,
515 // there is nothing for us to do.
516 if (GV->hasLocalLinkage() || GV->getName() == Name)
519 Module *M = GV->getParent();
521 // If there is a conflict, rename the conflict.
522 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
523 GV->takeName(ConflictGV);
524 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
525 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
527 GV->setName(Name); // Force the name back
531 /// copy additional attributes (those not needed to construct a GlobalValue)
532 /// from the SrcGV to the DestGV.
533 static void copyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) {
534 // Use the maximum alignment, rather than just copying the alignment of SrcGV.
535 auto *DestGO = dyn_cast<GlobalObject>(DestGV);
538 Alignment = std::max(DestGO->getAlignment(), SrcGV->getAlignment());
540 DestGV->copyAttributesFrom(SrcGV);
543 DestGO->setAlignment(Alignment);
545 forceRenaming(DestGV, SrcGV->getName());
548 static bool isLessConstraining(GlobalValue::VisibilityTypes a,
549 GlobalValue::VisibilityTypes b) {
550 if (a == GlobalValue::HiddenVisibility)
552 if (b == GlobalValue::HiddenVisibility)
554 if (a == GlobalValue::ProtectedVisibility)
556 if (b == GlobalValue::ProtectedVisibility)
561 Value *ValueMaterializerTy::materializeValueFor(Value *V) {
562 Function *SF = dyn_cast<Function>(V);
566 Function *DF = Function::Create(TypeMap.get(SF->getFunctionType()),
567 SF->getLinkage(), SF->getName(), DstM);
568 copyGVAttributes(DF, SF);
570 if (Comdat *SC = SF->getComdat()) {
571 Comdat *DC = DstM->getOrInsertComdat(SC->getName());
575 LazilyLinkFunctions.push_back(SF);
579 bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName,
580 const GlobalVariable *&GVar) {
581 const GlobalValue *GVal = M->getNamedValue(ComdatName);
582 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
583 GVal = GA->getBaseObject();
585 // We cannot resolve the size of the aliasee yet.
586 return emitError("Linking COMDATs named '" + ComdatName +
587 "': COMDAT key involves incomputable alias size.");
590 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
593 "Linking COMDATs named '" + ComdatName +
594 "': GlobalVariable required for data dependent selection!");
599 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
600 Comdat::SelectionKind Src,
601 Comdat::SelectionKind Dst,
602 Comdat::SelectionKind &Result,
604 // The ability to mix Comdat::SelectionKind::Any with
605 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
606 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
607 Dst == Comdat::SelectionKind::Largest;
608 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
609 Src == Comdat::SelectionKind::Largest;
610 if (DstAnyOrLargest && SrcAnyOrLargest) {
611 if (Dst == Comdat::SelectionKind::Largest ||
612 Src == Comdat::SelectionKind::Largest)
613 Result = Comdat::SelectionKind::Largest;
615 Result = Comdat::SelectionKind::Any;
616 } else if (Src == Dst) {
619 return emitError("Linking COMDATs named '" + ComdatName +
620 "': invalid selection kinds!");
624 case Comdat::SelectionKind::Any:
628 case Comdat::SelectionKind::NoDuplicates:
629 return emitError("Linking COMDATs named '" + ComdatName +
630 "': noduplicates has been violated!");
631 case Comdat::SelectionKind::ExactMatch:
632 case Comdat::SelectionKind::Largest:
633 case Comdat::SelectionKind::SameSize: {
634 const GlobalVariable *DstGV;
635 const GlobalVariable *SrcGV;
636 if (getComdatLeader(DstM, ComdatName, DstGV) ||
637 getComdatLeader(SrcM, ComdatName, SrcGV))
640 const DataLayout *DstDL = DstM->getDataLayout();
641 const DataLayout *SrcDL = SrcM->getDataLayout();
642 if (!DstDL || !SrcDL) {
644 "Linking COMDATs named '" + ComdatName +
645 "': can't do size dependent selection without DataLayout!");
648 DstDL->getTypeAllocSize(DstGV->getType()->getPointerElementType());
650 SrcDL->getTypeAllocSize(SrcGV->getType()->getPointerElementType());
651 if (Result == Comdat::SelectionKind::ExactMatch) {
652 if (SrcGV->getInitializer() != DstGV->getInitializer())
653 return emitError("Linking COMDATs named '" + ComdatName +
654 "': ExactMatch violated!");
656 } else if (Result == Comdat::SelectionKind::Largest) {
657 LinkFromSrc = SrcSize > DstSize;
658 } else if (Result == Comdat::SelectionKind::SameSize) {
659 if (SrcSize != DstSize)
660 return emitError("Linking COMDATs named '" + ComdatName +
661 "': SameSize violated!");
664 llvm_unreachable("unknown selection kind");
673 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
674 Comdat::SelectionKind &Result,
676 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
677 StringRef ComdatName = SrcC->getName();
678 Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable();
679 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
681 if (DstCI == ComdatSymTab.end()) {
682 // Use the comdat if it is only available in one of the modules.
688 const Comdat *DstC = &DstCI->second;
689 Comdat::SelectionKind DSK = DstC->getSelectionKind();
690 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
694 bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
695 const GlobalValue &Dest,
696 const GlobalValue &Src) {
697 // We always have to add Src if it has appending linkage.
698 if (Src.hasAppendingLinkage()) {
703 bool SrcIsDeclaration = Src.isDeclarationForLinker();
704 bool DestIsDeclaration = Dest.isDeclarationForLinker();
706 if (SrcIsDeclaration) {
707 // If Src is external or if both Src & Dest are external.. Just link the
708 // external globals, we aren't adding anything.
709 if (Src.hasDLLImportStorageClass()) {
710 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
711 LinkFromSrc = DestIsDeclaration;
714 // If the Dest is weak, use the source linkage.
715 LinkFromSrc = Dest.hasExternalWeakLinkage();
719 if (DestIsDeclaration) {
720 // If Dest is external but Src is not:
725 if (Src.hasCommonLinkage()) {
726 if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
731 if (!Dest.hasCommonLinkage()) {
736 // FIXME: Make datalayout mandatory and just use getDataLayout().
737 DataLayout DL(Dest.getParent());
739 uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
740 uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
741 LinkFromSrc = SrcSize > DestSize;
745 if (Src.isWeakForLinker()) {
746 assert(!Dest.hasExternalWeakLinkage());
747 assert(!Dest.hasAvailableExternallyLinkage());
749 if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
758 if (Dest.isWeakForLinker()) {
759 assert(Src.hasExternalLinkage());
764 assert(!Src.hasExternalWeakLinkage());
765 assert(!Dest.hasExternalWeakLinkage());
766 assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
767 "Unexpected linkage type!");
768 return emitError("Linking globals named '" + Src.getName() +
769 "': symbol multiply defined!");
772 /// Loop over all of the linked values to compute type mappings. For example,
773 /// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct
774 /// types 'Foo' but one got renamed when the module was loaded into the same
776 void ModuleLinker::computeTypeMapping() {
777 for (GlobalValue &SGV : SrcM->globals()) {
778 GlobalValue *DGV = getLinkedToGlobal(&SGV);
782 if (!DGV->hasAppendingLinkage() || !SGV.hasAppendingLinkage()) {
783 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
787 // Unify the element type of appending arrays.
788 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
789 ArrayType *SAT = cast<ArrayType>(SGV.getType()->getElementType());
790 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
793 for (GlobalValue &SGV : *SrcM) {
794 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
795 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
798 for (GlobalValue &SGV : SrcM->aliases()) {
799 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
800 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
803 // Incorporate types by name, scanning all the types in the source module.
804 // At this point, the destination module may have a type "%foo = { i32 }" for
805 // example. When the source module got loaded into the same LLVMContext, if
806 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
807 TypeFinder SrcStructTypes;
808 SrcStructTypes.run(*SrcM, true);
809 SmallPtrSet<StructType*, 32> SrcStructTypesSet(SrcStructTypes.begin(),
810 SrcStructTypes.end());
812 for (unsigned i = 0, e = SrcStructTypes.size(); i != e; ++i) {
813 StructType *ST = SrcStructTypes[i];
814 if (!ST->hasName()) continue;
816 // Check to see if there is a dot in the name followed by a digit.
817 size_t DotPos = ST->getName().rfind('.');
818 if (DotPos == 0 || DotPos == StringRef::npos ||
819 ST->getName().back() == '.' ||
820 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos+1])))
823 // Check to see if the destination module has a struct with the prefix name.
824 if (StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos)))
825 // Don't use it if this actually came from the source module. They're in
826 // the same LLVMContext after all. Also don't use it unless the type is
827 // actually used in the destination module. This can happen in situations
832 // %Z = type { %A } %B = type { %C.1 }
833 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
834 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
835 // %C = type { i8* } %B.3 = type { %C.1 }
837 // When we link Module B with Module A, the '%B' in Module B is
838 // used. However, that would then use '%C.1'. But when we process '%C.1',
839 // we prefer to take the '%C' version. So we are then left with both
840 // '%C.1' and '%C' being used for the same types. This leads to some
841 // variables using one type and some using the other.
842 if (!SrcStructTypesSet.count(DST) && TypeMap.DstStructTypesSet.count(DST))
843 TypeMap.addTypeMapping(DST, ST);
846 // Now that we have discovered all of the type equivalences, get a body for
847 // any 'opaque' types in the dest module that are now resolved.
848 TypeMap.linkDefinedTypeBodies();
851 static void upgradeGlobalArray(GlobalVariable *GV) {
852 ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
853 StructType *OldTy = cast<StructType>(ATy->getElementType());
854 assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
856 // Get the upgraded 3 element type.
857 PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
858 Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
860 StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
862 // Build new constants with a null third field filled in.
863 Constant *OldInitC = GV->getInitializer();
864 ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
865 if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
866 // Invalid initializer; give up.
868 std::vector<Constant *> Initializers;
869 if (OldInit && OldInit->getNumOperands()) {
870 Value *Null = Constant::getNullValue(VoidPtrTy);
871 for (Use &U : OldInit->operands()) {
872 ConstantStruct *Init = cast<ConstantStruct>(U.get());
873 Initializers.push_back(ConstantStruct::get(
874 NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
877 assert(Initializers.size() == ATy->getNumElements() &&
878 "Failed to copy all array elements");
880 // Replace the old GV with a new one.
881 ATy = ArrayType::get(NewTy, Initializers.size());
882 Constant *NewInit = ConstantArray::get(ATy, Initializers);
883 GlobalVariable *NewGV = new GlobalVariable(
884 *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
885 GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
886 GV->isExternallyInitialized());
887 NewGV->copyAttributesFrom(GV);
889 assert(GV->use_empty() && "program cannot use initializer list");
890 GV->eraseFromParent();
893 void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
894 // Look for the global arrays.
895 auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM->getNamedValue(Name));
898 auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM->getNamedValue(Name));
902 // Check if the types already match.
903 auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
905 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
909 // Grab the element types. We can only upgrade an array of a two-field
910 // struct. Only bother if the other one has three-fields.
911 auto *DstEltTy = cast<StructType>(DstTy->getElementType());
912 auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
913 if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
914 upgradeGlobalArray(DstGV);
917 if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
918 upgradeGlobalArray(SrcGV);
920 // We can't upgrade any other differences.
923 void ModuleLinker::upgradeMismatchedGlobals() {
924 upgradeMismatchedGlobalArray("llvm.global_ctors");
925 upgradeMismatchedGlobalArray("llvm.global_dtors");
928 /// If there were any appending global variables, link them together now.
929 /// Return true on error.
930 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
931 const GlobalVariable *SrcGV) {
933 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
934 return emitError("Linking globals named '" + SrcGV->getName() +
935 "': can only link appending global with another appending global!");
937 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
939 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
940 Type *EltTy = DstTy->getElementType();
942 // Check to see that they two arrays agree on type.
943 if (EltTy != SrcTy->getElementType())
944 return emitError("Appending variables with different element types!");
945 if (DstGV->isConstant() != SrcGV->isConstant())
946 return emitError("Appending variables linked with different const'ness!");
948 if (DstGV->getAlignment() != SrcGV->getAlignment())
950 "Appending variables with different alignment need to be linked!");
952 if (DstGV->getVisibility() != SrcGV->getVisibility())
954 "Appending variables with different visibility need to be linked!");
956 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
958 "Appending variables with different unnamed_addr need to be linked!");
960 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
962 "Appending variables with different section name need to be linked!");
964 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements();
965 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
967 // Create the new global variable.
969 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(),
970 DstGV->getLinkage(), /*init*/nullptr, /*name*/"", DstGV,
971 DstGV->getThreadLocalMode(),
972 DstGV->getType()->getAddressSpace());
974 // Propagate alignment, visibility and section info.
975 copyGVAttributes(NG, DstGV);
977 AppendingVarInfo AVI;
979 AVI.DstInit = DstGV->getInitializer();
980 AVI.SrcInit = SrcGV->getInitializer();
981 AppendingVars.push_back(AVI);
983 // Replace any uses of the two global variables with uses of the new
985 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
987 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
988 DstGV->eraseFromParent();
990 // Track the source variable so we don't try to link it.
991 DoNotLinkFromSource.insert(SrcGV);
996 bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) {
997 GlobalValue *DGV = getLinkedToGlobal(SGV);
999 // Handle the ultra special appending linkage case first.
1000 if (DGV && DGV->hasAppendingLinkage())
1001 return linkAppendingVarProto(cast<GlobalVariable>(DGV),
1002 cast<GlobalVariable>(SGV));
1004 bool LinkFromSrc = true;
1005 Comdat *C = nullptr;
1006 GlobalValue::VisibilityTypes Visibility = SGV->getVisibility();
1007 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
1009 if (const Comdat *SC = SGV->getComdat()) {
1010 Comdat::SelectionKind SK;
1011 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1012 C = DstM->getOrInsertComdat(SC->getName());
1013 C->setSelectionKind(SK);
1015 if (shouldLinkFromSource(LinkFromSrc, *DGV, *SGV))
1020 // Track the source global so that we don't attempt to copy it over when
1021 // processing global initializers.
1022 DoNotLinkFromSource.insert(SGV);
1025 // Make sure to remember this mapping.
1027 ConstantExpr::getBitCast(DGV, TypeMap.get(SGV->getType()));
1031 Visibility = isLessConstraining(Visibility, DGV->getVisibility())
1032 ? DGV->getVisibility()
1034 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1037 if (!LinkFromSrc && !DGV)
1041 if (auto *SGVar = dyn_cast<GlobalVariable>(SGV)) {
1042 NewGV = linkGlobalVariableProto(SGVar, DGV, LinkFromSrc);
1045 } else if (auto *SF = dyn_cast<Function>(SGV)) {
1046 NewGV = linkFunctionProto(SF, DGV, LinkFromSrc);
1048 NewGV = linkGlobalAliasProto(cast<GlobalAlias>(SGV), DGV, LinkFromSrc);
1053 copyGVAttributes(NewGV, SGV);
1055 NewGV->setUnnamedAddr(HasUnnamedAddr);
1056 NewGV->setVisibility(Visibility);
1058 if (auto *NewGO = dyn_cast<GlobalObject>(NewGV)) {
1060 NewGO->setComdat(C);
1063 // Make sure to remember this mapping.
1066 DGV->replaceAllUsesWith(
1067 ConstantExpr::getBitCast(NewGV, DGV->getType()));
1068 DGV->eraseFromParent();
1070 ValueMap[SGV] = NewGV;
1077 /// Loop through the global variables in the src module and merge them into the
1079 GlobalValue *ModuleLinker::linkGlobalVariableProto(const GlobalVariable *SGVar,
1082 unsigned Alignment = 0;
1083 bool ClearConstant = false;
1086 if (DGV->hasCommonLinkage() && SGVar->hasCommonLinkage())
1087 Alignment = std::max(SGVar->getAlignment(), DGV->getAlignment());
1089 auto *DGVar = dyn_cast<GlobalVariable>(DGV);
1090 if (!SGVar->isConstant() || (DGVar && !DGVar->isConstant()))
1091 ClearConstant = true;
1095 if (auto *NewGVar = dyn_cast<GlobalVariable>(DGV)) {
1097 NewGVar->setAlignment(Alignment);
1098 if (NewGVar->isDeclaration() && ClearConstant)
1099 NewGVar->setConstant(false);
1104 // No linking to be performed or linking from the source: simply create an
1105 // identical version of the symbol over in the dest module... the
1106 // initializer will be filled in later by LinkGlobalInits.
1107 GlobalVariable *NewDGV = new GlobalVariable(
1108 *DstM, TypeMap.get(SGVar->getType()->getElementType()),
1109 SGVar->isConstant(), SGVar->getLinkage(), /*init*/ nullptr,
1110 SGVar->getName(), /*insertbefore*/ nullptr, SGVar->getThreadLocalMode(),
1111 SGVar->getType()->getAddressSpace());
1114 NewDGV->setAlignment(Alignment);
1119 /// Link the function in the source module into the destination module if
1120 /// needed, setting up mapping information.
1121 GlobalValue *ModuleLinker::linkFunctionProto(const Function *SF,
1127 // If the function is to be lazily linked, don't create it just yet.
1128 // The ValueMaterializerTy will deal with creating it if it's used.
1129 if (!DGV && (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() ||
1130 SF->hasAvailableExternallyLinkage())) {
1131 DoNotLinkFromSource.insert(SF);
1135 // If there is no linkage to be performed or we are linking from the source,
1137 return Function::Create(TypeMap.get(SF->getFunctionType()), SF->getLinkage(),
1138 SF->getName(), DstM);
1141 /// Set up prototypes for any aliases that come over from the source module.
1142 GlobalValue *ModuleLinker::linkGlobalAliasProto(const GlobalAlias *SGA,
1148 // If there is no linkage to be performed or we're linking from the source,
1150 auto *PTy = cast<PointerType>(TypeMap.get(SGA->getType()));
1151 return GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(),
1152 SGA->getLinkage(), SGA->getName(), DstM);
1155 static void getArrayElements(const Constant *C,
1156 SmallVectorImpl<Constant *> &Dest) {
1157 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1159 for (unsigned i = 0; i != NumElements; ++i)
1160 Dest.push_back(C->getAggregateElement(i));
1163 void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) {
1164 // Merge the initializer.
1165 SmallVector<Constant *, 16> DstElements;
1166 getArrayElements(AVI.DstInit, DstElements);
1168 SmallVector<Constant *, 16> SrcElements;
1169 getArrayElements(AVI.SrcInit, SrcElements);
1171 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
1173 StringRef Name = AVI.NewGV->getName();
1174 bool IsNewStructor =
1175 (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
1176 cast<StructType>(NewType->getElementType())->getNumElements() == 3;
1178 for (auto *V : SrcElements) {
1179 if (IsNewStructor) {
1180 Constant *Key = V->getAggregateElement(2);
1181 if (DoNotLinkFromSource.count(Key))
1184 DstElements.push_back(
1185 MapValue(V, ValueMap, RF_None, &TypeMap, &ValMaterializer));
1187 if (IsNewStructor) {
1188 NewType = ArrayType::get(NewType->getElementType(), DstElements.size());
1189 AVI.NewGV->mutateType(PointerType::get(NewType, 0));
1192 AVI.NewGV->setInitializer(ConstantArray::get(NewType, DstElements));
1195 /// Update the initializers in the Dest module now that all globals that may be
1196 /// referenced are in Dest.
1197 void ModuleLinker::linkGlobalInits() {
1198 // Loop over all of the globals in the src module, mapping them over as we go
1199 for (Module::const_global_iterator I = SrcM->global_begin(),
1200 E = SrcM->global_end(); I != E; ++I) {
1202 // Only process initialized GV's or ones not already in dest.
1203 if (!I->hasInitializer() || DoNotLinkFromSource.count(I)) continue;
1205 // Grab destination global variable.
1206 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[I]);
1207 // Figure out what the initializer looks like in the dest module.
1208 DGV->setInitializer(MapValue(I->getInitializer(), ValueMap,
1209 RF_None, &TypeMap, &ValMaterializer));
1213 /// Copy the source function over into the dest function and fix up references
1214 /// to values. At this point we know that Dest is an external function, and
1215 /// that Src is not.
1216 void ModuleLinker::linkFunctionBody(Function *Dst, Function *Src) {
1217 assert(Src && Dst && Dst->isDeclaration() && !Src->isDeclaration());
1219 // Go through and convert function arguments over, remembering the mapping.
1220 Function::arg_iterator DI = Dst->arg_begin();
1221 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1222 I != E; ++I, ++DI) {
1223 DI->setName(I->getName()); // Copy the name over.
1225 // Add a mapping to our mapping.
1229 // Splice the body of the source function into the dest function.
1230 Dst->getBasicBlockList().splice(Dst->end(), Src->getBasicBlockList());
1232 // At this point, all of the instructions and values of the function are now
1233 // copied over. The only problem is that they are still referencing values in
1234 // the Source function as operands. Loop through all of the operands of the
1235 // functions and patch them up to point to the local versions.
1236 for (Function::iterator BB = Dst->begin(), BE = Dst->end(); BB != BE; ++BB)
1237 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
1238 RemapInstruction(I, ValueMap, RF_IgnoreMissingEntries, &TypeMap,
1241 // There is no need to map the arguments anymore.
1242 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1248 /// Insert all of the aliases in Src into the Dest module.
1249 void ModuleLinker::linkAliasBodies() {
1250 for (Module::alias_iterator I = SrcM->alias_begin(), E = SrcM->alias_end();
1252 if (DoNotLinkFromSource.count(I))
1254 if (Constant *Aliasee = I->getAliasee()) {
1255 GlobalAlias *DA = cast<GlobalAlias>(ValueMap[I]);
1257 MapValue(Aliasee, ValueMap, RF_None, &TypeMap, &ValMaterializer);
1258 DA->setAliasee(Val);
1263 /// Insert all of the named MDNodes in Src into the Dest module.
1264 void ModuleLinker::linkNamedMDNodes() {
1265 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1266 for (Module::const_named_metadata_iterator I = SrcM->named_metadata_begin(),
1267 E = SrcM->named_metadata_end(); I != E; ++I) {
1268 // Don't link module flags here. Do them separately.
1269 if (&*I == SrcModFlags) continue;
1270 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(I->getName());
1271 // Add Src elements into Dest node.
1272 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
1273 DestNMD->addOperand(MapValue(I->getOperand(i), ValueMap,
1274 RF_None, &TypeMap, &ValMaterializer));
1278 /// Merge the linker flags in Src into the Dest module.
1279 bool ModuleLinker::linkModuleFlagsMetadata() {
1280 // If the source module has no module flags, we are done.
1281 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1282 if (!SrcModFlags) return false;
1284 // If the destination module doesn't have module flags yet, then just copy
1285 // over the source module's flags.
1286 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
1287 if (DstModFlags->getNumOperands() == 0) {
1288 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1289 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1294 // First build a map of the existing module flags and requirements.
1295 DenseMap<MDString*, MDNode*> Flags;
1296 SmallSetVector<MDNode*, 16> Requirements;
1297 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1298 MDNode *Op = DstModFlags->getOperand(I);
1299 ConstantInt *Behavior = cast<ConstantInt>(Op->getOperand(0));
1300 MDString *ID = cast<MDString>(Op->getOperand(1));
1302 if (Behavior->getZExtValue() == Module::Require) {
1303 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1309 // Merge in the flags from the source module, and also collect its set of
1311 bool HasErr = false;
1312 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1313 MDNode *SrcOp = SrcModFlags->getOperand(I);
1314 ConstantInt *SrcBehavior = cast<ConstantInt>(SrcOp->getOperand(0));
1315 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1316 MDNode *DstOp = Flags.lookup(ID);
1317 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1319 // If this is a requirement, add it and continue.
1320 if (SrcBehaviorValue == Module::Require) {
1321 // If the destination module does not already have this requirement, add
1323 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1324 DstModFlags->addOperand(SrcOp);
1329 // If there is no existing flag with this ID, just add it.
1332 DstModFlags->addOperand(SrcOp);
1336 // Otherwise, perform a merge.
1337 ConstantInt *DstBehavior = cast<ConstantInt>(DstOp->getOperand(0));
1338 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1340 // If either flag has override behavior, handle it first.
1341 if (DstBehaviorValue == Module::Override) {
1342 // Diagnose inconsistent flags which both have override behavior.
1343 if (SrcBehaviorValue == Module::Override &&
1344 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1345 HasErr |= emitError("linking module flags '" + ID->getString() +
1346 "': IDs have conflicting override values");
1349 } else if (SrcBehaviorValue == Module::Override) {
1350 // Update the destination flag to that of the source.
1351 DstOp->replaceOperandWith(0, SrcBehavior);
1352 DstOp->replaceOperandWith(2, SrcOp->getOperand(2));
1356 // Diagnose inconsistent merge behavior types.
1357 if (SrcBehaviorValue != DstBehaviorValue) {
1358 HasErr |= emitError("linking module flags '" + ID->getString() +
1359 "': IDs have conflicting behaviors");
1363 // Perform the merge for standard behavior types.
1364 switch (SrcBehaviorValue) {
1365 case Module::Require:
1366 case Module::Override: llvm_unreachable("not possible");
1367 case Module::Error: {
1368 // Emit an error if the values differ.
1369 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1370 HasErr |= emitError("linking module flags '" + ID->getString() +
1371 "': IDs have conflicting values");
1375 case Module::Warning: {
1376 // Emit a warning if the values differ.
1377 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1378 emitWarning("linking module flags '" + ID->getString() +
1379 "': IDs have conflicting values");
1383 case Module::Append: {
1384 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1385 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1386 unsigned NumOps = DstValue->getNumOperands() + SrcValue->getNumOperands();
1387 Value **VP, **Values = VP = new Value*[NumOps];
1388 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i, ++VP)
1389 *VP = DstValue->getOperand(i);
1390 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i, ++VP)
1391 *VP = SrcValue->getOperand(i);
1392 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1393 ArrayRef<Value*>(Values,
1398 case Module::AppendUnique: {
1399 SmallSetVector<Value*, 16> Elts;
1400 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1401 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1402 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i)
1403 Elts.insert(DstValue->getOperand(i));
1404 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i)
1405 Elts.insert(SrcValue->getOperand(i));
1406 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1407 ArrayRef<Value*>(Elts.begin(),
1414 // Check all of the requirements.
1415 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1416 MDNode *Requirement = Requirements[I];
1417 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1418 Value *ReqValue = Requirement->getOperand(1);
1420 MDNode *Op = Flags[Flag];
1421 if (!Op || Op->getOperand(2) != ReqValue) {
1422 HasErr |= emitError("linking module flags '" + Flag->getString() +
1423 "': does not have the required value");
1431 bool ModuleLinker::run() {
1432 assert(DstM && "Null destination module");
1433 assert(SrcM && "Null source module");
1435 // Inherit the target data from the source module if the destination module
1436 // doesn't have one already.
1437 if (!DstM->getDataLayout() && SrcM->getDataLayout())
1438 DstM->setDataLayout(SrcM->getDataLayout());
1440 // Copy the target triple from the source to dest if the dest's is empty.
1441 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
1442 DstM->setTargetTriple(SrcM->getTargetTriple());
1444 if (SrcM->getDataLayout() && DstM->getDataLayout() &&
1445 *SrcM->getDataLayout() != *DstM->getDataLayout()) {
1446 emitWarning("Linking two modules of different data layouts: '" +
1447 SrcM->getModuleIdentifier() + "' is '" +
1448 SrcM->getDataLayoutStr() + "' whereas '" +
1449 DstM->getModuleIdentifier() + "' is '" +
1450 DstM->getDataLayoutStr() + "'\n");
1452 if (!SrcM->getTargetTriple().empty() &&
1453 DstM->getTargetTriple() != SrcM->getTargetTriple()) {
1454 emitWarning("Linking two modules of different target triples: " +
1455 SrcM->getModuleIdentifier() + "' is '" +
1456 SrcM->getTargetTriple() + "' whereas '" +
1457 DstM->getModuleIdentifier() + "' is '" +
1458 DstM->getTargetTriple() + "'\n");
1461 // Append the module inline asm string.
1462 if (!SrcM->getModuleInlineAsm().empty()) {
1463 if (DstM->getModuleInlineAsm().empty())
1464 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
1466 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
1467 SrcM->getModuleInlineAsm());
1470 // Loop over all of the linked values to compute type mappings.
1471 computeTypeMapping();
1473 ComdatsChosen.clear();
1474 for (const auto &SMEC : SrcM->getComdatSymbolTable()) {
1475 const Comdat &C = SMEC.getValue();
1476 if (ComdatsChosen.count(&C))
1478 Comdat::SelectionKind SK;
1480 if (getComdatResult(&C, SK, LinkFromSrc))
1482 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1485 // Upgrade mismatched global arrays.
1486 upgradeMismatchedGlobals();
1488 // Insert all of the globals in src into the DstM module... without linking
1489 // initializers (which could refer to functions not yet mapped over).
1490 for (Module::global_iterator I = SrcM->global_begin(),
1491 E = SrcM->global_end(); I != E; ++I)
1492 if (linkGlobalValueProto(I))
1495 // Link the functions together between the two modules, without doing function
1496 // bodies... this just adds external function prototypes to the DstM
1497 // function... We do this so that when we begin processing function bodies,
1498 // all of the global values that may be referenced are available in our
1500 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I)
1501 if (linkGlobalValueProto(I))
1504 // If there were any aliases, link them now.
1505 for (Module::alias_iterator I = SrcM->alias_begin(),
1506 E = SrcM->alias_end(); I != E; ++I)
1507 if (linkGlobalValueProto(I))
1510 for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i)
1511 linkAppendingVarInit(AppendingVars[i]);
1513 // Link in the function bodies that are defined in the source module into
1515 for (Module::iterator SF = SrcM->begin(), E = SrcM->end(); SF != E; ++SF) {
1516 // Skip if not linking from source.
1517 if (DoNotLinkFromSource.count(SF)) continue;
1519 Function *DF = cast<Function>(ValueMap[SF]);
1520 if (SF->hasPrefixData()) {
1521 // Link in the prefix data.
1522 DF->setPrefixData(MapValue(
1523 SF->getPrefixData(), ValueMap, RF_None, &TypeMap, &ValMaterializer));
1526 // Materialize if needed.
1527 if (std::error_code EC = SF->materialize())
1528 return emitError(EC.message());
1530 // Skip if no body (function is external).
1531 if (SF->isDeclaration())
1534 linkFunctionBody(DF, SF);
1535 SF->Dematerialize();
1538 // Resolve all uses of aliases with aliasees.
1541 // Remap all of the named MDNodes in Src into the DstM module. We do this
1542 // after linking GlobalValues so that MDNodes that reference GlobalValues
1543 // are properly remapped.
1546 // Merge the module flags into the DstM module.
1547 if (linkModuleFlagsMetadata())
1550 // Update the initializers in the DstM module now that all globals that may
1551 // be referenced are in DstM.
1554 // Process vector of lazily linked in functions.
1555 bool LinkedInAnyFunctions;
1557 LinkedInAnyFunctions = false;
1559 for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(),
1560 E = LazilyLinkFunctions.end(); I != E; ++I) {
1565 Function *DF = cast<Function>(ValueMap[SF]);
1566 if (SF->hasPrefixData()) {
1567 // Link in the prefix data.
1568 DF->setPrefixData(MapValue(SF->getPrefixData(),
1575 // Materialize if needed.
1576 if (std::error_code EC = SF->materialize())
1577 return emitError(EC.message());
1579 // Skip if no body (function is external).
1580 if (SF->isDeclaration())
1583 // Erase from vector *before* the function body is linked - linkFunctionBody could
1585 LazilyLinkFunctions.erase(I);
1587 // Link in function body.
1588 linkFunctionBody(DF, SF);
1589 SF->Dematerialize();
1591 // Set flag to indicate we may have more functions to lazily link in
1592 // since we linked in a function.
1593 LinkedInAnyFunctions = true;
1596 } while (LinkedInAnyFunctions);
1598 // Now that all of the types from the source are used, resolve any structs
1599 // copied over to the dest that didn't exist there.
1600 TypeMap.linkDefinedTypeBodies();
1605 void Linker::init(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
1606 this->Composite = M;
1607 this->DiagnosticHandler = DiagnosticHandler;
1609 TypeFinder StructTypes;
1610 StructTypes.run(*M, true);
1611 IdentifiedStructTypes.insert(StructTypes.begin(), StructTypes.end());
1614 Linker::Linker(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
1615 init(M, DiagnosticHandler);
1618 Linker::Linker(Module *M) {
1619 init(M, [this](const DiagnosticInfo &DI) {
1620 Composite->getContext().diagnose(DI);
1627 void Linker::deleteModule() {
1629 Composite = nullptr;
1632 bool Linker::linkInModule(Module *Src) {
1633 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,
1635 return TheLinker.run();
1638 //===----------------------------------------------------------------------===//
1639 // LinkModules entrypoint.
1640 //===----------------------------------------------------------------------===//
1642 /// This function links two modules together, with the resulting Dest module
1643 /// modified to be the composite of the two input modules. If an error occurs,
1644 /// true is returned and ErrorMsg (if not null) is set to indicate the problem.
1645 /// Upon failure, the Dest module could be in a modified state, and shouldn't be
1646 /// relied on to be consistent.
1647 bool Linker::LinkModules(Module *Dest, Module *Src,
1648 DiagnosticHandlerFunction DiagnosticHandler) {
1649 Linker L(Dest, DiagnosticHandler);
1650 return L.linkInModule(Src);
1653 bool Linker::LinkModules(Module *Dest, Module *Src) {
1655 return L.linkInModule(Src);
1658 //===----------------------------------------------------------------------===//
1660 //===----------------------------------------------------------------------===//
1662 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
1663 LLVMLinkerMode Mode, char **OutMessages) {
1664 Module *D = unwrap(Dest);
1665 std::string Message;
1666 raw_string_ostream Stream(Message);
1667 DiagnosticPrinterRawOStream DP(Stream);
1669 LLVMBool Result = Linker::LinkModules(
1670 D, unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); });
1672 if (OutMessages && Result)
1673 *OutMessages = strdup(Message.c_str());