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/Hashing.h"
17 #include "llvm/ADT/Optional.h"
18 #include "llvm/ADT/SetVector.h"
19 #include "llvm/ADT/SmallString.h"
20 #include "llvm/ADT/Statistic.h"
21 #include "llvm/ADT/Triple.h"
22 #include "llvm/IR/Constants.h"
23 #include "llvm/IR/DebugInfo.h"
24 #include "llvm/IR/DiagnosticInfo.h"
25 #include "llvm/IR/DiagnosticPrinter.h"
26 #include "llvm/IR/LLVMContext.h"
27 #include "llvm/IR/Module.h"
28 #include "llvm/IR/TypeFinder.h"
29 #include "llvm/Support/CommandLine.h"
30 #include "llvm/Support/Debug.h"
31 #include "llvm/Support/raw_ostream.h"
32 #include "llvm/Transforms/Utils/Cloning.h"
38 //===----------------------------------------------------------------------===//
39 // TypeMap implementation.
40 //===----------------------------------------------------------------------===//
43 class TypeMapTy : public ValueMapTypeRemapper {
44 /// This is a mapping from a source type to a destination type to use.
45 DenseMap<Type*, Type*> MappedTypes;
47 /// When checking to see if two subgraphs are isomorphic, we speculatively
48 /// add types to MappedTypes, but keep track of them here in case we need to
50 SmallVector<Type*, 16> SpeculativeTypes;
52 SmallVector<StructType*, 16> SpeculativeDstOpaqueTypes;
54 /// This is a list of non-opaque structs in the source module that are mapped
55 /// to an opaque struct in the destination module.
56 SmallVector<StructType*, 16> SrcDefinitionsToResolve;
58 /// This is the set of opaque types in the destination modules who are
59 /// getting a body from the source module.
60 SmallPtrSet<StructType*, 16> DstResolvedOpaqueTypes;
63 TypeMapTy(Linker::IdentifiedStructTypeSet &DstStructTypesSet)
64 : DstStructTypesSet(DstStructTypesSet) {}
66 Linker::IdentifiedStructTypeSet &DstStructTypesSet;
67 /// Indicate that the specified type in the destination module is conceptually
68 /// equivalent to the specified type in the source module.
69 void addTypeMapping(Type *DstTy, Type *SrcTy);
71 /// Produce a body for an opaque type in the dest module from a type
72 /// definition in the source module.
73 void linkDefinedTypeBodies();
75 /// Return the mapped type to use for the specified input type from the
77 Type *get(Type *SrcTy);
78 Type *get(Type *SrcTy, SmallPtrSet<StructType *, 8> &Visited);
80 void finishType(StructType *DTy, StructType *STy, ArrayRef<Type *> ETypes);
82 FunctionType *get(FunctionType *T) {
83 return cast<FunctionType>(get((Type *)T));
86 /// Dump out the type map for debugging purposes.
88 for (auto &Pair : MappedTypes) {
89 dbgs() << "TypeMap: ";
90 Pair.first->print(dbgs());
92 Pair.second->print(dbgs());
98 Type *remapType(Type *SrcTy) override { return get(SrcTy); }
100 bool areTypesIsomorphic(Type *DstTy, Type *SrcTy);
104 void TypeMapTy::addTypeMapping(Type *DstTy, Type *SrcTy) {
105 assert(SpeculativeTypes.empty());
106 assert(SpeculativeDstOpaqueTypes.empty());
108 // Check to see if these types are recursively isomorphic and establish a
109 // mapping between them if so.
110 if (!areTypesIsomorphic(DstTy, SrcTy)) {
111 // Oops, they aren't isomorphic. Just discard this request by rolling out
112 // any speculative mappings we've established.
113 for (Type *Ty : SpeculativeTypes)
114 MappedTypes.erase(Ty);
116 SrcDefinitionsToResolve.resize(SrcDefinitionsToResolve.size() -
117 SpeculativeDstOpaqueTypes.size());
118 for (StructType *Ty : SpeculativeDstOpaqueTypes)
119 DstResolvedOpaqueTypes.erase(Ty);
121 for (Type *Ty : SpeculativeTypes)
122 if (auto *STy = dyn_cast<StructType>(Ty))
126 SpeculativeTypes.clear();
127 SpeculativeDstOpaqueTypes.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())
137 // If we have an entry in the MappedTypes table, then we have our answer.
138 Type *&Entry = MappedTypes[SrcTy];
140 return Entry == DstTy;
142 // Two identical types are clearly isomorphic. Remember this
143 // non-speculatively.
144 if (DstTy == SrcTy) {
149 // Okay, we have two types with identical kinds that we haven't seen before.
151 // If this is an opaque struct type, special case it.
152 if (StructType *SSTy = dyn_cast<StructType>(SrcTy)) {
153 // Mapping an opaque type to any struct, just keep the dest struct.
154 if (SSTy->isOpaque()) {
156 SpeculativeTypes.push_back(SrcTy);
160 // Mapping a non-opaque source type to an opaque dest. If this is the first
161 // type that we're mapping onto this destination type then we succeed. Keep
162 // the dest, but fill it in later. If this is the second (different) type
163 // that we're trying to map onto the same opaque type then we fail.
164 if (cast<StructType>(DstTy)->isOpaque()) {
165 // We can only map one source type onto the opaque destination type.
166 if (!DstResolvedOpaqueTypes.insert(cast<StructType>(DstTy)).second)
168 SrcDefinitionsToResolve.push_back(SSTy);
169 SpeculativeTypes.push_back(SrcTy);
170 SpeculativeDstOpaqueTypes.push_back(cast<StructType>(DstTy));
176 // If the number of subtypes disagree between the two types, then we fail.
177 if (SrcTy->getNumContainedTypes() != DstTy->getNumContainedTypes())
180 // Fail if any of the extra properties (e.g. array size) of the type disagree.
181 if (isa<IntegerType>(DstTy))
182 return false; // bitwidth disagrees.
183 if (PointerType *PT = dyn_cast<PointerType>(DstTy)) {
184 if (PT->getAddressSpace() != cast<PointerType>(SrcTy)->getAddressSpace())
187 } else if (FunctionType *FT = dyn_cast<FunctionType>(DstTy)) {
188 if (FT->isVarArg() != cast<FunctionType>(SrcTy)->isVarArg())
190 } else if (StructType *DSTy = dyn_cast<StructType>(DstTy)) {
191 StructType *SSTy = cast<StructType>(SrcTy);
192 if (DSTy->isLiteral() != SSTy->isLiteral() ||
193 DSTy->isPacked() != SSTy->isPacked())
195 } else if (ArrayType *DATy = dyn_cast<ArrayType>(DstTy)) {
196 if (DATy->getNumElements() != cast<ArrayType>(SrcTy)->getNumElements())
198 } else if (VectorType *DVTy = dyn_cast<VectorType>(DstTy)) {
199 if (DVTy->getNumElements() != cast<VectorType>(SrcTy)->getNumElements())
203 // Otherwise, we speculate that these two types will line up and recursively
204 // check the subelements.
206 SpeculativeTypes.push_back(SrcTy);
208 for (unsigned I = 0, E = SrcTy->getNumContainedTypes(); I != E; ++I)
209 if (!areTypesIsomorphic(DstTy->getContainedType(I),
210 SrcTy->getContainedType(I)))
213 // If everything seems to have lined up, then everything is great.
217 void TypeMapTy::linkDefinedTypeBodies() {
218 SmallVector<Type*, 16> Elements;
219 for (StructType *SrcSTy : SrcDefinitionsToResolve) {
220 StructType *DstSTy = cast<StructType>(MappedTypes[SrcSTy]);
221 assert(DstSTy->isOpaque());
223 // Map the body of the source type over to a new body for the dest type.
224 Elements.resize(SrcSTy->getNumElements());
225 for (unsigned I = 0, E = Elements.size(); I != E; ++I)
226 Elements[I] = get(SrcSTy->getElementType(I));
228 DstSTy->setBody(Elements, SrcSTy->isPacked());
229 DstStructTypesSet.switchToNonOpaque(DstSTy);
231 SrcDefinitionsToResolve.clear();
232 DstResolvedOpaqueTypes.clear();
235 void TypeMapTy::finishType(StructType *DTy, StructType *STy,
236 ArrayRef<Type *> ETypes) {
237 DTy->setBody(ETypes, STy->isPacked());
240 if (STy->hasName()) {
241 SmallString<16> TmpName = STy->getName();
243 DTy->setName(TmpName);
246 DstStructTypesSet.addNonOpaque(DTy);
249 Type *TypeMapTy::get(Type *Ty) {
250 SmallPtrSet<StructType *, 8> Visited;
251 return get(Ty, Visited);
254 Type *TypeMapTy::get(Type *Ty, SmallPtrSet<StructType *, 8> &Visited) {
255 // If we already have an entry for this type, return it.
256 Type **Entry = &MappedTypes[Ty];
260 // These are types that LLVM itself will unique.
261 bool IsUniqued = !isa<StructType>(Ty) || cast<StructType>(Ty)->isLiteral();
265 for (auto &Pair : MappedTypes) {
266 assert(!(Pair.first != Ty && Pair.second == Ty) &&
267 "mapping to a source type");
272 if (!IsUniqued && !Visited.insert(cast<StructType>(Ty)).second) {
273 StructType *DTy = StructType::create(Ty->getContext());
277 // If this is not a recursive type, then just map all of the elements and
278 // then rebuild the type from inside out.
279 SmallVector<Type *, 4> ElementTypes;
281 // If there are no element types to map, then the type is itself. This is
282 // true for the anonymous {} struct, things like 'float', integers, etc.
283 if (Ty->getNumContainedTypes() == 0 && IsUniqued)
286 // Remap all of the elements, keeping track of whether any of them change.
287 bool AnyChange = false;
288 ElementTypes.resize(Ty->getNumContainedTypes());
289 for (unsigned I = 0, E = Ty->getNumContainedTypes(); I != E; ++I) {
290 ElementTypes[I] = get(Ty->getContainedType(I), Visited);
291 AnyChange |= ElementTypes[I] != Ty->getContainedType(I);
294 // If we found our type while recursively processing stuff, just use it.
295 Entry = &MappedTypes[Ty];
297 if (auto *DTy = dyn_cast<StructType>(*Entry)) {
298 if (DTy->isOpaque()) {
299 auto *STy = cast<StructType>(Ty);
300 finishType(DTy, STy, ElementTypes);
306 // If all of the element types mapped directly over and the type is not
307 // a nomed struct, then the type is usable as-is.
308 if (!AnyChange && IsUniqued)
311 // Otherwise, rebuild a modified type.
312 switch (Ty->getTypeID()) {
314 llvm_unreachable("unknown derived type to remap");
315 case Type::ArrayTyID:
316 return *Entry = ArrayType::get(ElementTypes[0],
317 cast<ArrayType>(Ty)->getNumElements());
318 case Type::VectorTyID:
319 return *Entry = VectorType::get(ElementTypes[0],
320 cast<VectorType>(Ty)->getNumElements());
321 case Type::PointerTyID:
322 return *Entry = PointerType::get(ElementTypes[0],
323 cast<PointerType>(Ty)->getAddressSpace());
324 case Type::FunctionTyID:
325 return *Entry = FunctionType::get(ElementTypes[0],
326 makeArrayRef(ElementTypes).slice(1),
327 cast<FunctionType>(Ty)->isVarArg());
328 case Type::StructTyID: {
329 auto *STy = cast<StructType>(Ty);
330 bool IsPacked = STy->isPacked();
332 return *Entry = StructType::get(Ty->getContext(), ElementTypes, IsPacked);
334 // If the type is opaque, we can just use it directly.
335 if (STy->isOpaque()) {
336 DstStructTypesSet.addOpaque(STy);
340 if (StructType *OldT =
341 DstStructTypesSet.findNonOpaque(ElementTypes, IsPacked)) {
343 return *Entry = OldT;
347 DstStructTypesSet.addNonOpaque(STy);
351 StructType *DTy = StructType::create(Ty->getContext());
352 finishType(DTy, STy, ElementTypes);
358 //===----------------------------------------------------------------------===//
359 // ModuleLinker implementation.
360 //===----------------------------------------------------------------------===//
365 /// Creates prototypes for functions that are lazily linked on the fly. This
366 /// speeds up linking for modules with many/ lazily linked functions of which
368 class ValueMaterializerTy : public ValueMaterializer {
371 std::vector<GlobalValue *> &LazilyLinkGlobalValues;
374 ValueMaterializerTy(TypeMapTy &TypeMap, Module *DstM,
375 std::vector<GlobalValue *> &LazilyLinkGlobalValues)
376 : ValueMaterializer(), TypeMap(TypeMap), DstM(DstM),
377 LazilyLinkGlobalValues(LazilyLinkGlobalValues) {}
379 Value *materializeValueFor(Value *V) override;
382 class LinkDiagnosticInfo : public DiagnosticInfo {
386 LinkDiagnosticInfo(DiagnosticSeverity Severity, const Twine &Msg);
387 void print(DiagnosticPrinter &DP) const override;
389 LinkDiagnosticInfo::LinkDiagnosticInfo(DiagnosticSeverity Severity,
391 : DiagnosticInfo(DK_Linker, Severity), Msg(Msg) {}
392 void LinkDiagnosticInfo::print(DiagnosticPrinter &DP) const { DP << Msg; }
394 /// This is an implementation class for the LinkModules function, which is the
395 /// entrypoint for this file.
400 ValueMaterializerTy ValMaterializer;
402 /// Mapping of values from what they used to be in Src, to what they are now
403 /// in DstM. ValueToValueMapTy is a ValueMap, which involves some overhead
404 /// due to the use of Value handles which the Linker doesn't actually need,
405 /// but this allows us to reuse the ValueMapper code.
406 ValueToValueMapTy ValueMap;
408 struct AppendingVarInfo {
409 GlobalVariable *NewGV; // New aggregate global in dest module.
410 const Constant *DstInit; // Old initializer from dest module.
411 const Constant *SrcInit; // Old initializer from src module.
414 std::vector<AppendingVarInfo> AppendingVars;
416 // Set of items not to link in from source.
417 SmallPtrSet<const Value *, 16> DoNotLinkFromSource;
419 // Vector of GlobalValues to lazily link in.
420 std::vector<GlobalValue *> LazilyLinkGlobalValues;
422 /// Functions that have replaced other functions.
423 SmallPtrSet<const Function *, 16> OverridingFunctions;
425 DiagnosticHandlerFunction DiagnosticHandler;
427 /// For symbol clashes, prefer those from Src.
428 bool OverrideFromSrc;
431 ModuleLinker(Module *dstM, Linker::IdentifiedStructTypeSet &Set, Module *srcM,
432 DiagnosticHandlerFunction DiagnosticHandler,
433 bool OverrideFromSrc)
434 : DstM(dstM), SrcM(srcM), TypeMap(Set),
435 ValMaterializer(TypeMap, DstM, LazilyLinkGlobalValues),
436 DiagnosticHandler(DiagnosticHandler), OverrideFromSrc(OverrideFromSrc) {
442 bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
443 const GlobalValue &Src);
445 /// Helper method for setting a message and returning an error code.
446 bool emitError(const Twine &Message) {
447 DiagnosticHandler(LinkDiagnosticInfo(DS_Error, Message));
451 void emitWarning(const Twine &Message) {
452 DiagnosticHandler(LinkDiagnosticInfo(DS_Warning, Message));
455 bool getComdatLeader(Module *M, StringRef ComdatName,
456 const GlobalVariable *&GVar);
457 bool computeResultingSelectionKind(StringRef ComdatName,
458 Comdat::SelectionKind Src,
459 Comdat::SelectionKind Dst,
460 Comdat::SelectionKind &Result,
462 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
464 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
467 /// Given a global in the source module, return the global in the
468 /// destination module that is being linked to, if any.
469 GlobalValue *getLinkedToGlobal(const GlobalValue *SrcGV) {
470 // If the source has no name it can't link. If it has local linkage,
471 // there is no name match-up going on.
472 if (!SrcGV->hasName() || SrcGV->hasLocalLinkage())
475 // Otherwise see if we have a match in the destination module's symtab.
476 GlobalValue *DGV = DstM->getNamedValue(SrcGV->getName());
480 // If we found a global with the same name in the dest module, but it has
481 // internal linkage, we are really not doing any linkage here.
482 if (DGV->hasLocalLinkage())
485 // Otherwise, we do in fact link to the destination global.
489 void computeTypeMapping();
491 void upgradeMismatchedGlobalArray(StringRef Name);
492 void upgradeMismatchedGlobals();
494 bool linkAppendingVarProto(GlobalVariable *DstGV,
495 const GlobalVariable *SrcGV);
497 bool linkGlobalValueProto(GlobalValue *GV);
498 bool linkModuleFlagsMetadata();
500 void linkAppendingVarInit(const AppendingVarInfo &AVI);
502 void linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src);
503 bool linkFunctionBody(Function &Dst, Function &Src);
504 void linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src);
505 bool linkGlobalValueBody(GlobalValue &Src);
507 void linkNamedMDNodes();
508 void stripReplacedSubprograms();
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 DestGV->copyAttributesFrom(SrcGV);
537 forceRenaming(DestGV, SrcGV->getName());
540 static bool isLessConstraining(GlobalValue::VisibilityTypes a,
541 GlobalValue::VisibilityTypes b) {
542 if (a == GlobalValue::HiddenVisibility)
544 if (b == GlobalValue::HiddenVisibility)
546 if (a == GlobalValue::ProtectedVisibility)
548 if (b == GlobalValue::ProtectedVisibility)
553 /// Loop through the global variables in the src module and merge them into the
555 static GlobalVariable *copyGlobalVariableProto(TypeMapTy &TypeMap, Module &DstM,
556 const GlobalVariable *SGVar) {
557 // No linking to be performed or linking from the source: simply create an
558 // identical version of the symbol over in the dest module... the
559 // initializer will be filled in later by LinkGlobalInits.
560 GlobalVariable *NewDGV = new GlobalVariable(
561 DstM, TypeMap.get(SGVar->getType()->getElementType()),
562 SGVar->isConstant(), SGVar->getLinkage(), /*init*/ nullptr,
563 SGVar->getName(), /*insertbefore*/ nullptr, SGVar->getThreadLocalMode(),
564 SGVar->getType()->getAddressSpace());
569 /// Link the function in the source module into the destination module if
570 /// needed, setting up mapping information.
571 static Function *copyFunctionProto(TypeMapTy &TypeMap, Module &DstM,
572 const Function *SF) {
573 // If there is no linkage to be performed or we are linking from the source,
575 return Function::Create(TypeMap.get(SF->getFunctionType()), SF->getLinkage(),
576 SF->getName(), &DstM);
579 /// Set up prototypes for any aliases that come over from the source module.
580 static GlobalAlias *copyGlobalAliasProto(TypeMapTy &TypeMap, Module &DstM,
581 const GlobalAlias *SGA) {
582 // If there is no linkage to be performed or we're linking from the source,
584 auto *PTy = cast<PointerType>(TypeMap.get(SGA->getType()));
585 return GlobalAlias::create(PTy, SGA->getLinkage(), SGA->getName(), &DstM);
588 static GlobalValue *copyGlobalValueProto(TypeMapTy &TypeMap, Module &DstM,
589 const GlobalValue *SGV) {
591 if (auto *SGVar = dyn_cast<GlobalVariable>(SGV))
592 NewGV = copyGlobalVariableProto(TypeMap, DstM, SGVar);
593 else if (auto *SF = dyn_cast<Function>(SGV))
594 NewGV = copyFunctionProto(TypeMap, DstM, SF);
596 NewGV = copyGlobalAliasProto(TypeMap, DstM, cast<GlobalAlias>(SGV));
597 copyGVAttributes(NewGV, SGV);
601 Value *ValueMaterializerTy::materializeValueFor(Value *V) {
602 auto *SGV = dyn_cast<GlobalValue>(V);
606 GlobalValue *DGV = copyGlobalValueProto(TypeMap, *DstM, SGV);
608 if (Comdat *SC = SGV->getComdat()) {
609 if (auto *DGO = dyn_cast<GlobalObject>(DGV)) {
610 Comdat *DC = DstM->getOrInsertComdat(SC->getName());
615 LazilyLinkGlobalValues.push_back(SGV);
619 bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName,
620 const GlobalVariable *&GVar) {
621 const GlobalValue *GVal = M->getNamedValue(ComdatName);
622 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
623 GVal = GA->getBaseObject();
625 // We cannot resolve the size of the aliasee yet.
626 return emitError("Linking COMDATs named '" + ComdatName +
627 "': COMDAT key involves incomputable alias size.");
630 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
633 "Linking COMDATs named '" + ComdatName +
634 "': GlobalVariable required for data dependent selection!");
639 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
640 Comdat::SelectionKind Src,
641 Comdat::SelectionKind Dst,
642 Comdat::SelectionKind &Result,
644 // The ability to mix Comdat::SelectionKind::Any with
645 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
646 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
647 Dst == Comdat::SelectionKind::Largest;
648 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
649 Src == Comdat::SelectionKind::Largest;
650 if (DstAnyOrLargest && SrcAnyOrLargest) {
651 if (Dst == Comdat::SelectionKind::Largest ||
652 Src == Comdat::SelectionKind::Largest)
653 Result = Comdat::SelectionKind::Largest;
655 Result = Comdat::SelectionKind::Any;
656 } else if (Src == Dst) {
659 return emitError("Linking COMDATs named '" + ComdatName +
660 "': invalid selection kinds!");
664 case Comdat::SelectionKind::Any:
668 case Comdat::SelectionKind::NoDuplicates:
669 return emitError("Linking COMDATs named '" + ComdatName +
670 "': noduplicates has been violated!");
671 case Comdat::SelectionKind::ExactMatch:
672 case Comdat::SelectionKind::Largest:
673 case Comdat::SelectionKind::SameSize: {
674 const GlobalVariable *DstGV;
675 const GlobalVariable *SrcGV;
676 if (getComdatLeader(DstM, ComdatName, DstGV) ||
677 getComdatLeader(SrcM, ComdatName, SrcGV))
680 const DataLayout &DstDL = DstM->getDataLayout();
681 const DataLayout &SrcDL = SrcM->getDataLayout();
683 DstDL.getTypeAllocSize(DstGV->getType()->getPointerElementType());
685 SrcDL.getTypeAllocSize(SrcGV->getType()->getPointerElementType());
686 if (Result == Comdat::SelectionKind::ExactMatch) {
687 if (SrcGV->getInitializer() != DstGV->getInitializer())
688 return emitError("Linking COMDATs named '" + ComdatName +
689 "': ExactMatch violated!");
691 } else if (Result == Comdat::SelectionKind::Largest) {
692 LinkFromSrc = SrcSize > DstSize;
693 } else if (Result == Comdat::SelectionKind::SameSize) {
694 if (SrcSize != DstSize)
695 return emitError("Linking COMDATs named '" + ComdatName +
696 "': SameSize violated!");
699 llvm_unreachable("unknown selection kind");
708 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
709 Comdat::SelectionKind &Result,
711 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
712 StringRef ComdatName = SrcC->getName();
713 Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable();
714 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
716 if (DstCI == ComdatSymTab.end()) {
717 // Use the comdat if it is only available in one of the modules.
723 const Comdat *DstC = &DstCI->second;
724 Comdat::SelectionKind DSK = DstC->getSelectionKind();
725 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
729 bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
730 const GlobalValue &Dest,
731 const GlobalValue &Src) {
732 // Should we unconditionally use the Src?
733 if (OverrideFromSrc) {
738 // We always have to add Src if it has appending linkage.
739 if (Src.hasAppendingLinkage()) {
744 bool SrcIsDeclaration = Src.isDeclarationForLinker();
745 bool DestIsDeclaration = Dest.isDeclarationForLinker();
747 if (SrcIsDeclaration) {
748 // If Src is external or if both Src & Dest are external.. Just link the
749 // external globals, we aren't adding anything.
750 if (Src.hasDLLImportStorageClass()) {
751 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
752 LinkFromSrc = DestIsDeclaration;
755 // If the Dest is weak, use the source linkage.
756 LinkFromSrc = Dest.hasExternalWeakLinkage();
760 if (DestIsDeclaration) {
761 // If Dest is external but Src is not:
766 if (Src.hasCommonLinkage()) {
767 if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
772 if (!Dest.hasCommonLinkage()) {
777 const DataLayout &DL = Dest.getParent()->getDataLayout();
778 uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
779 uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
780 LinkFromSrc = SrcSize > DestSize;
784 if (Src.isWeakForLinker()) {
785 assert(!Dest.hasExternalWeakLinkage());
786 assert(!Dest.hasAvailableExternallyLinkage());
788 if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
797 if (Dest.isWeakForLinker()) {
798 assert(Src.hasExternalLinkage());
803 assert(!Src.hasExternalWeakLinkage());
804 assert(!Dest.hasExternalWeakLinkage());
805 assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
806 "Unexpected linkage type!");
807 return emitError("Linking globals named '" + Src.getName() +
808 "': symbol multiply defined!");
811 /// Loop over all of the linked values to compute type mappings. For example,
812 /// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct
813 /// types 'Foo' but one got renamed when the module was loaded into the same
815 void ModuleLinker::computeTypeMapping() {
816 for (GlobalValue &SGV : SrcM->globals()) {
817 GlobalValue *DGV = getLinkedToGlobal(&SGV);
821 if (!DGV->hasAppendingLinkage() || !SGV.hasAppendingLinkage()) {
822 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
826 // Unify the element type of appending arrays.
827 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
828 ArrayType *SAT = cast<ArrayType>(SGV.getType()->getElementType());
829 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
832 for (GlobalValue &SGV : *SrcM) {
833 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
834 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
837 for (GlobalValue &SGV : SrcM->aliases()) {
838 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
839 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
842 // Incorporate types by name, scanning all the types in the source module.
843 // At this point, the destination module may have a type "%foo = { i32 }" for
844 // example. When the source module got loaded into the same LLVMContext, if
845 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
846 std::vector<StructType *> Types = SrcM->getIdentifiedStructTypes();
847 for (StructType *ST : Types) {
851 // Check to see if there is a dot in the name followed by a digit.
852 size_t DotPos = ST->getName().rfind('.');
853 if (DotPos == 0 || DotPos == StringRef::npos ||
854 ST->getName().back() == '.' ||
855 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos + 1])))
858 // Check to see if the destination module has a struct with the prefix name.
859 StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos));
863 // Don't use it if this actually came from the source module. They're in
864 // the same LLVMContext after all. Also don't use it unless the type is
865 // actually used in the destination module. This can happen in situations
870 // %Z = type { %A } %B = type { %C.1 }
871 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
872 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
873 // %C = type { i8* } %B.3 = type { %C.1 }
875 // When we link Module B with Module A, the '%B' in Module B is
876 // used. However, that would then use '%C.1'. But when we process '%C.1',
877 // we prefer to take the '%C' version. So we are then left with both
878 // '%C.1' and '%C' being used for the same types. This leads to some
879 // variables using one type and some using the other.
880 if (TypeMap.DstStructTypesSet.hasType(DST))
881 TypeMap.addTypeMapping(DST, ST);
884 // Now that we have discovered all of the type equivalences, get a body for
885 // any 'opaque' types in the dest module that are now resolved.
886 TypeMap.linkDefinedTypeBodies();
889 static void upgradeGlobalArray(GlobalVariable *GV) {
890 ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
891 StructType *OldTy = cast<StructType>(ATy->getElementType());
892 assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
894 // Get the upgraded 3 element type.
895 PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
896 Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
898 StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
900 // Build new constants with a null third field filled in.
901 Constant *OldInitC = GV->getInitializer();
902 ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
903 if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
904 // Invalid initializer; give up.
906 std::vector<Constant *> Initializers;
907 if (OldInit && OldInit->getNumOperands()) {
908 Value *Null = Constant::getNullValue(VoidPtrTy);
909 for (Use &U : OldInit->operands()) {
910 ConstantStruct *Init = cast<ConstantStruct>(U.get());
911 Initializers.push_back(ConstantStruct::get(
912 NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
915 assert(Initializers.size() == ATy->getNumElements() &&
916 "Failed to copy all array elements");
918 // Replace the old GV with a new one.
919 ATy = ArrayType::get(NewTy, Initializers.size());
920 Constant *NewInit = ConstantArray::get(ATy, Initializers);
921 GlobalVariable *NewGV = new GlobalVariable(
922 *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
923 GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
924 GV->isExternallyInitialized());
925 NewGV->copyAttributesFrom(GV);
927 assert(GV->use_empty() && "program cannot use initializer list");
928 GV->eraseFromParent();
931 void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
932 // Look for the global arrays.
933 auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM->getNamedValue(Name));
936 auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM->getNamedValue(Name));
940 // Check if the types already match.
941 auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
943 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
947 // Grab the element types. We can only upgrade an array of a two-field
948 // struct. Only bother if the other one has three-fields.
949 auto *DstEltTy = cast<StructType>(DstTy->getElementType());
950 auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
951 if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
952 upgradeGlobalArray(DstGV);
955 if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
956 upgradeGlobalArray(SrcGV);
958 // We can't upgrade any other differences.
961 void ModuleLinker::upgradeMismatchedGlobals() {
962 upgradeMismatchedGlobalArray("llvm.global_ctors");
963 upgradeMismatchedGlobalArray("llvm.global_dtors");
966 /// If there were any appending global variables, link them together now.
967 /// Return true on error.
968 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
969 const GlobalVariable *SrcGV) {
971 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
972 return emitError("Linking globals named '" + SrcGV->getName() +
973 "': can only link appending global with another appending global!");
975 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
977 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
978 Type *EltTy = DstTy->getElementType();
980 // Check to see that they two arrays agree on type.
981 if (EltTy != SrcTy->getElementType())
982 return emitError("Appending variables with different element types!");
983 if (DstGV->isConstant() != SrcGV->isConstant())
984 return emitError("Appending variables linked with different const'ness!");
986 if (DstGV->getAlignment() != SrcGV->getAlignment())
988 "Appending variables with different alignment need to be linked!");
990 if (DstGV->getVisibility() != SrcGV->getVisibility())
992 "Appending variables with different visibility need to be linked!");
994 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
996 "Appending variables with different unnamed_addr need to be linked!");
998 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
1000 "Appending variables with different section name need to be linked!");
1002 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements();
1003 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
1005 // Create the new global variable.
1006 GlobalVariable *NG =
1007 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(),
1008 DstGV->getLinkage(), /*init*/nullptr, /*name*/"", DstGV,
1009 DstGV->getThreadLocalMode(),
1010 DstGV->getType()->getAddressSpace());
1012 // Propagate alignment, visibility and section info.
1013 copyGVAttributes(NG, DstGV);
1015 AppendingVarInfo AVI;
1017 AVI.DstInit = DstGV->getInitializer();
1018 AVI.SrcInit = SrcGV->getInitializer();
1019 AppendingVars.push_back(AVI);
1021 // Replace any uses of the two global variables with uses of the new
1023 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
1025 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
1026 DstGV->eraseFromParent();
1028 // Track the source variable so we don't try to link it.
1029 DoNotLinkFromSource.insert(SrcGV);
1034 bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) {
1035 GlobalValue *DGV = getLinkedToGlobal(SGV);
1037 // Handle the ultra special appending linkage case first.
1038 if (DGV && DGV->hasAppendingLinkage())
1039 return linkAppendingVarProto(cast<GlobalVariable>(DGV),
1040 cast<GlobalVariable>(SGV));
1042 bool LinkFromSrc = true;
1043 Comdat *C = nullptr;
1044 GlobalValue::VisibilityTypes Visibility = SGV->getVisibility();
1045 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
1047 if (const Comdat *SC = SGV->getComdat()) {
1048 Comdat::SelectionKind SK;
1049 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1050 C = DstM->getOrInsertComdat(SC->getName());
1051 C->setSelectionKind(SK);
1053 if (shouldLinkFromSource(LinkFromSrc, *DGV, *SGV))
1058 // Track the source global so that we don't attempt to copy it over when
1059 // processing global initializers.
1060 DoNotLinkFromSource.insert(SGV);
1063 // Make sure to remember this mapping.
1065 ConstantExpr::getBitCast(DGV, TypeMap.get(SGV->getType()));
1069 Visibility = isLessConstraining(Visibility, DGV->getVisibility())
1070 ? DGV->getVisibility()
1072 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1075 if (!LinkFromSrc && !DGV)
1082 // If the GV is to be lazily linked, don't create it just yet.
1083 // The ValueMaterializerTy will deal with creating it if it's used.
1084 if (!DGV && !OverrideFromSrc &&
1085 (SGV->hasLocalLinkage() || SGV->hasLinkOnceLinkage() ||
1086 SGV->hasAvailableExternallyLinkage())) {
1087 DoNotLinkFromSource.insert(SGV);
1091 NewGV = copyGlobalValueProto(TypeMap, *DstM, SGV);
1093 if (DGV && isa<Function>(DGV))
1094 if (auto *NewF = dyn_cast<Function>(NewGV))
1095 OverridingFunctions.insert(NewF);
1098 NewGV->setUnnamedAddr(HasUnnamedAddr);
1099 NewGV->setVisibility(Visibility);
1101 if (auto *NewGO = dyn_cast<GlobalObject>(NewGV)) {
1103 NewGO->setComdat(C);
1105 if (DGV && DGV->hasCommonLinkage() && SGV->hasCommonLinkage())
1106 NewGO->setAlignment(std::max(DGV->getAlignment(), SGV->getAlignment()));
1109 if (auto *NewGVar = dyn_cast<GlobalVariable>(NewGV)) {
1110 auto *DGVar = dyn_cast_or_null<GlobalVariable>(DGV);
1111 auto *SGVar = dyn_cast<GlobalVariable>(SGV);
1112 if (DGVar && SGVar && DGVar->isDeclaration() && SGVar->isDeclaration() &&
1113 (!DGVar->isConstant() || !SGVar->isConstant()))
1114 NewGVar->setConstant(false);
1117 // Make sure to remember this mapping.
1120 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewGV, DGV->getType()));
1121 DGV->eraseFromParent();
1123 ValueMap[SGV] = NewGV;
1129 static void getArrayElements(const Constant *C,
1130 SmallVectorImpl<Constant *> &Dest) {
1131 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1133 for (unsigned i = 0; i != NumElements; ++i)
1134 Dest.push_back(C->getAggregateElement(i));
1137 void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) {
1138 // Merge the initializer.
1139 SmallVector<Constant *, 16> DstElements;
1140 getArrayElements(AVI.DstInit, DstElements);
1142 SmallVector<Constant *, 16> SrcElements;
1143 getArrayElements(AVI.SrcInit, SrcElements);
1145 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
1147 StringRef Name = AVI.NewGV->getName();
1148 bool IsNewStructor =
1149 (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
1150 cast<StructType>(NewType->getElementType())->getNumElements() == 3;
1152 for (auto *V : SrcElements) {
1153 if (IsNewStructor) {
1154 Constant *Key = V->getAggregateElement(2);
1155 if (DoNotLinkFromSource.count(Key))
1158 DstElements.push_back(
1159 MapValue(V, ValueMap, RF_None, &TypeMap, &ValMaterializer));
1161 if (IsNewStructor) {
1162 NewType = ArrayType::get(NewType->getElementType(), DstElements.size());
1163 AVI.NewGV->mutateType(PointerType::get(NewType, 0));
1166 AVI.NewGV->setInitializer(ConstantArray::get(NewType, DstElements));
1169 /// Update the initializers in the Dest module now that all globals that may be
1170 /// referenced are in Dest.
1171 void ModuleLinker::linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src) {
1172 // Figure out what the initializer looks like in the dest module.
1173 Dst.setInitializer(MapValue(Src.getInitializer(), ValueMap, RF_None, &TypeMap,
1177 /// Copy the source function over into the dest function and fix up references
1178 /// to values. At this point we know that Dest is an external function, and
1179 /// that Src is not.
1180 bool ModuleLinker::linkFunctionBody(Function &Dst, Function &Src) {
1181 assert(Dst.isDeclaration() && !Src.isDeclaration());
1183 // Materialize if needed.
1184 if (std::error_code EC = Src.materialize())
1185 return emitError(EC.message());
1187 // Link in the prefix data.
1188 if (Src.hasPrefixData())
1189 Dst.setPrefixData(MapValue(Src.getPrefixData(), ValueMap, RF_None, &TypeMap,
1192 // Link in the prologue data.
1193 if (Src.hasPrologueData())
1194 Dst.setPrologueData(MapValue(Src.getPrologueData(), ValueMap, RF_None,
1195 &TypeMap, &ValMaterializer));
1197 // Link in the personality function.
1198 if (Src.hasPersonalityFn())
1199 Dst.setPersonalityFn(MapValue(Src.getPersonalityFn(), ValueMap, RF_None,
1200 &TypeMap, &ValMaterializer));
1202 // Go through and convert function arguments over, remembering the mapping.
1203 Function::arg_iterator DI = Dst.arg_begin();
1204 for (Argument &Arg : Src.args()) {
1205 DI->setName(Arg.getName()); // Copy the name over.
1207 // Add a mapping to our mapping.
1208 ValueMap[&Arg] = DI;
1212 // Copy over the metadata attachments.
1213 SmallVector<std::pair<unsigned, MDNode *>, 8> MDs;
1214 Src.getAllMetadata(MDs);
1215 for (const auto &I : MDs)
1216 Dst.setMetadata(I.first, MapMetadata(I.second, ValueMap, RF_None, &TypeMap,
1219 // Splice the body of the source function into the dest function.
1220 Dst.getBasicBlockList().splice(Dst.end(), Src.getBasicBlockList());
1222 // At this point, all of the instructions and values of the function are now
1223 // copied over. The only problem is that they are still referencing values in
1224 // the Source function as operands. Loop through all of the operands of the
1225 // functions and patch them up to point to the local versions.
1226 for (BasicBlock &BB : Dst)
1227 for (Instruction &I : BB)
1228 RemapInstruction(&I, ValueMap, RF_IgnoreMissingEntries, &TypeMap,
1231 // There is no need to map the arguments anymore.
1232 for (Argument &Arg : Src.args())
1233 ValueMap.erase(&Arg);
1235 Src.dematerialize();
1239 void ModuleLinker::linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src) {
1240 Constant *Aliasee = Src.getAliasee();
1242 MapValue(Aliasee, ValueMap, RF_None, &TypeMap, &ValMaterializer);
1243 Dst.setAliasee(Val);
1246 bool ModuleLinker::linkGlobalValueBody(GlobalValue &Src) {
1247 Value *Dst = ValueMap[&Src];
1249 if (auto *F = dyn_cast<Function>(&Src))
1250 return linkFunctionBody(cast<Function>(*Dst), *F);
1251 if (auto *GVar = dyn_cast<GlobalVariable>(&Src)) {
1252 linkGlobalInit(cast<GlobalVariable>(*Dst), *GVar);
1255 linkAliasBody(cast<GlobalAlias>(*Dst), cast<GlobalAlias>(Src));
1259 /// Insert all of the named MDNodes in Src into the Dest module.
1260 void ModuleLinker::linkNamedMDNodes() {
1261 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1262 for (const NamedMDNode &NMD : SrcM->named_metadata()) {
1263 // Don't link module flags here. Do them separately.
1264 if (&NMD == SrcModFlags)
1266 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(NMD.getName());
1267 // Add Src elements into Dest node.
1268 for (const MDNode *op : NMD.operands())
1269 DestNMD->addOperand(
1270 MapMetadata(op, ValueMap, RF_None, &TypeMap, &ValMaterializer));
1274 /// Drop DISubprograms that have been superseded.
1276 /// FIXME: this creates an asymmetric result: we strip functions from losing
1277 /// subprograms in DstM, but leave losing subprograms in SrcM.
1278 /// TODO: Remove this logic once the backend can correctly determine canonical
1280 void ModuleLinker::stripReplacedSubprograms() {
1281 // Avoid quadratic runtime by returning early when there's nothing to do.
1282 if (OverridingFunctions.empty())
1285 // Move the functions now, so the set gets cleared even on early returns.
1286 auto Functions = std::move(OverridingFunctions);
1287 OverridingFunctions.clear();
1289 // Drop functions from subprograms if they've been overridden by the new
1291 NamedMDNode *CompileUnits = DstM->getNamedMetadata("llvm.dbg.cu");
1294 for (unsigned I = 0, E = CompileUnits->getNumOperands(); I != E; ++I) {
1295 auto *CU = cast<DICompileUnit>(CompileUnits->getOperand(I));
1296 assert(CU && "Expected valid compile unit");
1298 for (DISubprogram *SP : CU->getSubprograms()) {
1299 if (!SP || !SP->getFunction() || !Functions.count(SP->getFunction()))
1302 // Prevent DebugInfoFinder from tagging this as the canonical subprogram,
1303 // since the canonical one is in the incoming module.
1304 SP->replaceFunction(nullptr);
1309 /// Merge the linker flags in Src into the Dest module.
1310 bool ModuleLinker::linkModuleFlagsMetadata() {
1311 // If the source module has no module flags, we are done.
1312 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1313 if (!SrcModFlags) return false;
1315 // If the destination module doesn't have module flags yet, then just copy
1316 // over the source module's flags.
1317 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
1318 if (DstModFlags->getNumOperands() == 0) {
1319 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1320 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1325 // First build a map of the existing module flags and requirements.
1326 DenseMap<MDString *, std::pair<MDNode *, unsigned>> Flags;
1327 SmallSetVector<MDNode*, 16> Requirements;
1328 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1329 MDNode *Op = DstModFlags->getOperand(I);
1330 ConstantInt *Behavior = mdconst::extract<ConstantInt>(Op->getOperand(0));
1331 MDString *ID = cast<MDString>(Op->getOperand(1));
1333 if (Behavior->getZExtValue() == Module::Require) {
1334 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1336 Flags[ID] = std::make_pair(Op, I);
1340 // Merge in the flags from the source module, and also collect its set of
1342 bool HasErr = false;
1343 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1344 MDNode *SrcOp = SrcModFlags->getOperand(I);
1345 ConstantInt *SrcBehavior =
1346 mdconst::extract<ConstantInt>(SrcOp->getOperand(0));
1347 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1350 std::tie(DstOp, DstIndex) = Flags.lookup(ID);
1351 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1353 // If this is a requirement, add it and continue.
1354 if (SrcBehaviorValue == Module::Require) {
1355 // If the destination module does not already have this requirement, add
1357 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1358 DstModFlags->addOperand(SrcOp);
1363 // If there is no existing flag with this ID, just add it.
1365 Flags[ID] = std::make_pair(SrcOp, DstModFlags->getNumOperands());
1366 DstModFlags->addOperand(SrcOp);
1370 // Otherwise, perform a merge.
1371 ConstantInt *DstBehavior =
1372 mdconst::extract<ConstantInt>(DstOp->getOperand(0));
1373 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1375 // If either flag has override behavior, handle it first.
1376 if (DstBehaviorValue == Module::Override) {
1377 // Diagnose inconsistent flags which both have override behavior.
1378 if (SrcBehaviorValue == Module::Override &&
1379 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1380 HasErr |= emitError("linking module flags '" + ID->getString() +
1381 "': IDs have conflicting override values");
1384 } else if (SrcBehaviorValue == Module::Override) {
1385 // Update the destination flag to that of the source.
1386 DstModFlags->setOperand(DstIndex, SrcOp);
1387 Flags[ID].first = SrcOp;
1391 // Diagnose inconsistent merge behavior types.
1392 if (SrcBehaviorValue != DstBehaviorValue) {
1393 HasErr |= emitError("linking module flags '" + ID->getString() +
1394 "': IDs have conflicting behaviors");
1398 auto replaceDstValue = [&](MDNode *New) {
1399 Metadata *FlagOps[] = {DstOp->getOperand(0), ID, New};
1400 MDNode *Flag = MDNode::get(DstM->getContext(), FlagOps);
1401 DstModFlags->setOperand(DstIndex, Flag);
1402 Flags[ID].first = Flag;
1405 // Perform the merge for standard behavior types.
1406 switch (SrcBehaviorValue) {
1407 case Module::Require:
1408 case Module::Override: llvm_unreachable("not possible");
1409 case Module::Error: {
1410 // Emit an error if the values differ.
1411 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1412 HasErr |= emitError("linking module flags '" + ID->getString() +
1413 "': IDs have conflicting values");
1417 case Module::Warning: {
1418 // Emit a warning if the values differ.
1419 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1420 emitWarning("linking module flags '" + ID->getString() +
1421 "': IDs have conflicting values");
1425 case Module::Append: {
1426 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1427 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1428 SmallVector<Metadata *, 8> MDs;
1429 MDs.reserve(DstValue->getNumOperands() + SrcValue->getNumOperands());
1430 MDs.append(DstValue->op_begin(), DstValue->op_end());
1431 MDs.append(SrcValue->op_begin(), SrcValue->op_end());
1433 replaceDstValue(MDNode::get(DstM->getContext(), MDs));
1436 case Module::AppendUnique: {
1437 SmallSetVector<Metadata *, 16> Elts;
1438 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1439 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1440 Elts.insert(DstValue->op_begin(), DstValue->op_end());
1441 Elts.insert(SrcValue->op_begin(), SrcValue->op_end());
1443 replaceDstValue(MDNode::get(DstM->getContext(),
1444 makeArrayRef(Elts.begin(), Elts.end())));
1450 // Check all of the requirements.
1451 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1452 MDNode *Requirement = Requirements[I];
1453 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1454 Metadata *ReqValue = Requirement->getOperand(1);
1456 MDNode *Op = Flags[Flag].first;
1457 if (!Op || Op->getOperand(2) != ReqValue) {
1458 HasErr |= emitError("linking module flags '" + Flag->getString() +
1459 "': does not have the required value");
1467 // This function returns true if the triples match.
1468 static bool triplesMatch(const Triple &T0, const Triple &T1) {
1469 // If vendor is apple, ignore the version number.
1470 if (T0.getVendor() == Triple::Apple)
1471 return T0.getArch() == T1.getArch() &&
1472 T0.getSubArch() == T1.getSubArch() &&
1473 T0.getVendor() == T1.getVendor() &&
1474 T0.getOS() == T1.getOS();
1479 // This function returns the merged triple.
1480 static std::string mergeTriples(const Triple &SrcTriple, const Triple &DstTriple) {
1481 // If vendor is apple, pick the triple with the larger version number.
1482 if (SrcTriple.getVendor() == Triple::Apple)
1483 if (DstTriple.isOSVersionLT(SrcTriple))
1484 return SrcTriple.str();
1486 return DstTriple.str();
1489 bool ModuleLinker::run() {
1490 assert(DstM && "Null destination module");
1491 assert(SrcM && "Null source module");
1493 // Inherit the target data from the source module if the destination module
1494 // doesn't have one already.
1495 if (DstM->getDataLayout().isDefault())
1496 DstM->setDataLayout(SrcM->getDataLayout());
1498 if (SrcM->getDataLayout() != DstM->getDataLayout()) {
1499 emitWarning("Linking two modules of different data layouts: '" +
1500 SrcM->getModuleIdentifier() + "' is '" +
1501 SrcM->getDataLayoutStr() + "' whereas '" +
1502 DstM->getModuleIdentifier() + "' is '" +
1503 DstM->getDataLayoutStr() + "'\n");
1506 // Copy the target triple from the source to dest if the dest's is empty.
1507 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
1508 DstM->setTargetTriple(SrcM->getTargetTriple());
1510 Triple SrcTriple(SrcM->getTargetTriple()), DstTriple(DstM->getTargetTriple());
1512 if (!SrcM->getTargetTriple().empty() && !triplesMatch(SrcTriple, DstTriple))
1513 emitWarning("Linking two modules of different target triples: " +
1514 SrcM->getModuleIdentifier() + "' is '" +
1515 SrcM->getTargetTriple() + "' whereas '" +
1516 DstM->getModuleIdentifier() + "' is '" +
1517 DstM->getTargetTriple() + "'\n");
1519 DstM->setTargetTriple(mergeTriples(SrcTriple, DstTriple));
1521 // Append the module inline asm string.
1522 if (!SrcM->getModuleInlineAsm().empty()) {
1523 if (DstM->getModuleInlineAsm().empty())
1524 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
1526 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
1527 SrcM->getModuleInlineAsm());
1530 // Loop over all of the linked values to compute type mappings.
1531 computeTypeMapping();
1533 ComdatsChosen.clear();
1534 for (const auto &SMEC : SrcM->getComdatSymbolTable()) {
1535 const Comdat &C = SMEC.getValue();
1536 if (ComdatsChosen.count(&C))
1538 Comdat::SelectionKind SK;
1540 if (getComdatResult(&C, SK, LinkFromSrc))
1542 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1545 // Upgrade mismatched global arrays.
1546 upgradeMismatchedGlobals();
1548 // Insert all of the globals in src into the DstM module... without linking
1549 // initializers (which could refer to functions not yet mapped over).
1550 for (GlobalVariable &GV : SrcM->globals())
1551 if (linkGlobalValueProto(&GV))
1554 // Link the functions together between the two modules, without doing function
1555 // bodies... this just adds external function prototypes to the DstM
1556 // function... We do this so that when we begin processing function bodies,
1557 // all of the global values that may be referenced are available in our
1559 for (Function &F :*SrcM)
1560 if (linkGlobalValueProto(&F))
1563 // If there were any aliases, link them now.
1564 for (GlobalAlias &GA : SrcM->aliases())
1565 if (linkGlobalValueProto(&GA))
1568 for (const AppendingVarInfo &AppendingVar : AppendingVars)
1569 linkAppendingVarInit(AppendingVar);
1571 for (const auto &Entry : DstM->getComdatSymbolTable()) {
1572 const Comdat &C = Entry.getValue();
1573 if (C.getSelectionKind() == Comdat::Any)
1575 const GlobalValue *GV = SrcM->getNamedValue(C.getName());
1577 MapValue(GV, ValueMap, RF_None, &TypeMap, &ValMaterializer);
1580 // Strip replaced subprograms before mapping any metadata -- so that we're
1581 // not changing metadata from the source module (note that
1582 // linkGlobalValueBody() eventually calls RemapInstruction() and therefore
1583 // MapMetadata()) -- but after linking global value protocols -- so that
1584 // OverridingFunctions has been built.
1585 stripReplacedSubprograms();
1587 // Link in the function bodies that are defined in the source module into
1589 for (Function &SF : *SrcM) {
1590 // Skip if no body (function is external).
1591 if (SF.isDeclaration())
1594 // Skip if not linking from source.
1595 if (DoNotLinkFromSource.count(&SF))
1598 if (linkGlobalValueBody(SF))
1602 // Resolve all uses of aliases with aliasees.
1603 for (GlobalAlias &Src : SrcM->aliases()) {
1604 if (DoNotLinkFromSource.count(&Src))
1606 linkGlobalValueBody(Src);
1609 // Remap all of the named MDNodes in Src into the DstM module. We do this
1610 // after linking GlobalValues so that MDNodes that reference GlobalValues
1611 // are properly remapped.
1614 // Merge the module flags into the DstM module.
1615 if (linkModuleFlagsMetadata())
1618 // Update the initializers in the DstM module now that all globals that may
1619 // be referenced are in DstM.
1620 for (GlobalVariable &Src : SrcM->globals()) {
1621 // Only process initialized GV's or ones not already in dest.
1622 if (!Src.hasInitializer() || DoNotLinkFromSource.count(&Src))
1624 linkGlobalValueBody(Src);
1627 // Process vector of lazily linked in functions.
1628 while (!LazilyLinkGlobalValues.empty()) {
1629 GlobalValue *SGV = LazilyLinkGlobalValues.back();
1630 LazilyLinkGlobalValues.pop_back();
1632 assert(!SGV->isDeclaration() && "users should not pass down decls");
1633 if (linkGlobalValueBody(*SGV))
1640 Linker::StructTypeKeyInfo::KeyTy::KeyTy(ArrayRef<Type *> E, bool P)
1641 : ETypes(E), IsPacked(P) {}
1643 Linker::StructTypeKeyInfo::KeyTy::KeyTy(const StructType *ST)
1644 : ETypes(ST->elements()), IsPacked(ST->isPacked()) {}
1646 bool Linker::StructTypeKeyInfo::KeyTy::operator==(const KeyTy &That) const {
1647 if (IsPacked != That.IsPacked)
1649 if (ETypes != That.ETypes)
1654 bool Linker::StructTypeKeyInfo::KeyTy::operator!=(const KeyTy &That) const {
1655 return !this->operator==(That);
1658 StructType *Linker::StructTypeKeyInfo::getEmptyKey() {
1659 return DenseMapInfo<StructType *>::getEmptyKey();
1662 StructType *Linker::StructTypeKeyInfo::getTombstoneKey() {
1663 return DenseMapInfo<StructType *>::getTombstoneKey();
1666 unsigned Linker::StructTypeKeyInfo::getHashValue(const KeyTy &Key) {
1667 return hash_combine(hash_combine_range(Key.ETypes.begin(), Key.ETypes.end()),
1671 unsigned Linker::StructTypeKeyInfo::getHashValue(const StructType *ST) {
1672 return getHashValue(KeyTy(ST));
1675 bool Linker::StructTypeKeyInfo::isEqual(const KeyTy &LHS,
1676 const StructType *RHS) {
1677 if (RHS == getEmptyKey() || RHS == getTombstoneKey())
1679 return LHS == KeyTy(RHS);
1682 bool Linker::StructTypeKeyInfo::isEqual(const StructType *LHS,
1683 const StructType *RHS) {
1684 if (RHS == getEmptyKey())
1685 return LHS == getEmptyKey();
1687 if (RHS == getTombstoneKey())
1688 return LHS == getTombstoneKey();
1690 return KeyTy(LHS) == KeyTy(RHS);
1693 void Linker::IdentifiedStructTypeSet::addNonOpaque(StructType *Ty) {
1694 assert(!Ty->isOpaque());
1695 NonOpaqueStructTypes.insert(Ty);
1698 void Linker::IdentifiedStructTypeSet::switchToNonOpaque(StructType *Ty) {
1699 assert(!Ty->isOpaque());
1700 NonOpaqueStructTypes.insert(Ty);
1701 bool Removed = OpaqueStructTypes.erase(Ty);
1706 void Linker::IdentifiedStructTypeSet::addOpaque(StructType *Ty) {
1707 assert(Ty->isOpaque());
1708 OpaqueStructTypes.insert(Ty);
1712 Linker::IdentifiedStructTypeSet::findNonOpaque(ArrayRef<Type *> ETypes,
1714 Linker::StructTypeKeyInfo::KeyTy Key(ETypes, IsPacked);
1715 auto I = NonOpaqueStructTypes.find_as(Key);
1716 if (I == NonOpaqueStructTypes.end())
1721 bool Linker::IdentifiedStructTypeSet::hasType(StructType *Ty) {
1723 return OpaqueStructTypes.count(Ty);
1724 auto I = NonOpaqueStructTypes.find(Ty);
1725 if (I == NonOpaqueStructTypes.end())
1730 void Linker::init(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
1731 this->Composite = M;
1732 this->DiagnosticHandler = DiagnosticHandler;
1734 TypeFinder StructTypes;
1735 StructTypes.run(*M, true);
1736 for (StructType *Ty : StructTypes) {
1738 IdentifiedStructTypes.addOpaque(Ty);
1740 IdentifiedStructTypes.addNonOpaque(Ty);
1744 Linker::Linker(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
1745 init(M, DiagnosticHandler);
1748 Linker::Linker(Module *M) {
1749 init(M, [this](const DiagnosticInfo &DI) {
1750 Composite->getContext().diagnose(DI);
1757 void Linker::deleteModule() {
1759 Composite = nullptr;
1762 bool Linker::linkInModule(Module *Src, bool OverrideSymbols) {
1763 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,
1764 DiagnosticHandler, OverrideSymbols);
1765 bool RetCode = TheLinker.run();
1766 Composite->dropTriviallyDeadConstantArrays();
1770 void Linker::setModule(Module *Dst) {
1771 init(Dst, DiagnosticHandler);
1774 //===----------------------------------------------------------------------===//
1775 // LinkModules entrypoint.
1776 //===----------------------------------------------------------------------===//
1778 /// This function links two modules together, with the resulting Dest module
1779 /// modified to be the composite of the two input modules. If an error occurs,
1780 /// true is returned and ErrorMsg (if not null) is set to indicate the problem.
1781 /// Upon failure, the Dest module could be in a modified state, and shouldn't be
1782 /// relied on to be consistent.
1783 bool Linker::LinkModules(Module *Dest, Module *Src,
1784 DiagnosticHandlerFunction DiagnosticHandler) {
1785 Linker L(Dest, DiagnosticHandler);
1786 return L.linkInModule(Src);
1789 bool Linker::LinkModules(Module *Dest, Module *Src) {
1791 return L.linkInModule(Src);
1794 //===----------------------------------------------------------------------===//
1796 //===----------------------------------------------------------------------===//
1798 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
1799 LLVMLinkerMode Unused, char **OutMessages) {
1800 Module *D = unwrap(Dest);
1801 std::string Message;
1802 raw_string_ostream Stream(Message);
1803 DiagnosticPrinterRawOStream DP(Stream);
1805 LLVMBool Result = Linker::LinkModules(
1806 D, unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); });
1808 if (OutMessages && Result) {
1810 *OutMessages = strdup(Message.c_str());