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());
230 SrcDefinitionsToResolve.clear();
231 DstResolvedOpaqueTypes.clear();
234 void TypeMapTy::finishType(StructType *DTy, StructType *STy,
235 ArrayRef<Type *> ETypes) {
236 DTy->setBody(ETypes, STy->isPacked());
239 if (STy->hasName()) {
240 SmallString<16> TmpName = STy->getName();
242 DTy->setName(TmpName);
245 DstStructTypesSet.addNonOpaque(DTy);
248 Type *TypeMapTy::get(Type *Ty) {
249 SmallPtrSet<StructType *, 8> Visited;
250 return get(Ty, Visited);
253 Type *TypeMapTy::get(Type *Ty, SmallPtrSet<StructType *, 8> &Visited) {
254 // If we already have an entry for this type, return it.
255 Type **Entry = &MappedTypes[Ty];
259 // These are types that LLVM itself will unique.
260 bool IsUniqued = !isa<StructType>(Ty) || cast<StructType>(Ty)->isLiteral();
264 for (auto &Pair : MappedTypes) {
265 assert(!(Pair.first != Ty && Pair.second == Ty) &&
266 "mapping to a source type");
271 if (!IsUniqued && !Visited.insert(cast<StructType>(Ty)).second) {
272 StructType *DTy = StructType::create(Ty->getContext());
276 // If this is not a recursive type, then just map all of the elements and
277 // then rebuild the type from inside out.
278 SmallVector<Type *, 4> ElementTypes;
280 // If there are no element types to map, then the type is itself. This is
281 // true for the anonymous {} struct, things like 'float', integers, etc.
282 if (Ty->getNumContainedTypes() == 0 && IsUniqued)
285 // Remap all of the elements, keeping track of whether any of them change.
286 bool AnyChange = false;
287 ElementTypes.resize(Ty->getNumContainedTypes());
288 for (unsigned I = 0, E = Ty->getNumContainedTypes(); I != E; ++I) {
289 ElementTypes[I] = get(Ty->getContainedType(I), Visited);
290 AnyChange |= ElementTypes[I] != Ty->getContainedType(I);
293 // If we found our type while recursively processing stuff, just use it.
294 Entry = &MappedTypes[Ty];
296 if (auto *DTy = dyn_cast<StructType>(*Entry)) {
297 if (DTy->isOpaque()) {
298 auto *STy = cast<StructType>(Ty);
299 finishType(DTy, STy, ElementTypes);
305 // If all of the element types mapped directly over and the type is not
306 // a nomed struct, then the type is usable as-is.
307 if (!AnyChange && IsUniqued)
310 // Otherwise, rebuild a modified type.
311 switch (Ty->getTypeID()) {
313 llvm_unreachable("unknown derived type to remap");
314 case Type::ArrayTyID:
315 return *Entry = ArrayType::get(ElementTypes[0],
316 cast<ArrayType>(Ty)->getNumElements());
317 case Type::VectorTyID:
318 return *Entry = VectorType::get(ElementTypes[0],
319 cast<VectorType>(Ty)->getNumElements());
320 case Type::PointerTyID:
321 return *Entry = PointerType::get(ElementTypes[0],
322 cast<PointerType>(Ty)->getAddressSpace());
323 case Type::FunctionTyID:
324 return *Entry = FunctionType::get(ElementTypes[0],
325 makeArrayRef(ElementTypes).slice(1),
326 cast<FunctionType>(Ty)->isVarArg());
327 case Type::StructTyID: {
328 auto *STy = cast<StructType>(Ty);
329 bool IsPacked = STy->isPacked();
331 return *Entry = StructType::get(Ty->getContext(), ElementTypes, IsPacked);
333 // If the type is opaque, we can just use it directly.
334 if (STy->isOpaque()) {
335 DstStructTypesSet.addOpaque(STy);
339 if (StructType *OldT =
340 DstStructTypesSet.findNonOpaque(ElementTypes, IsPacked)) {
342 return *Entry = OldT;
346 DstStructTypesSet.addNonOpaque(STy);
350 StructType *DTy = StructType::create(Ty->getContext());
351 finishType(DTy, STy, ElementTypes);
357 //===----------------------------------------------------------------------===//
358 // ModuleLinker implementation.
359 //===----------------------------------------------------------------------===//
364 /// Creates prototypes for functions that are lazily linked on the fly. This
365 /// speeds up linking for modules with many/ lazily linked functions of which
367 class ValueMaterializerTy : public ValueMaterializer {
370 std::vector<GlobalValue *> &LazilyLinkGlobalValues;
373 ValueMaterializerTy(TypeMapTy &TypeMap, Module *DstM,
374 std::vector<GlobalValue *> &LazilyLinkGlobalValues)
375 : ValueMaterializer(), TypeMap(TypeMap), DstM(DstM),
376 LazilyLinkGlobalValues(LazilyLinkGlobalValues) {}
378 Value *materializeValueFor(Value *V) override;
381 class LinkDiagnosticInfo : public DiagnosticInfo {
385 LinkDiagnosticInfo(DiagnosticSeverity Severity, const Twine &Msg);
386 void print(DiagnosticPrinter &DP) const override;
388 LinkDiagnosticInfo::LinkDiagnosticInfo(DiagnosticSeverity Severity,
390 : DiagnosticInfo(DK_Linker, Severity), Msg(Msg) {}
391 void LinkDiagnosticInfo::print(DiagnosticPrinter &DP) const { DP << Msg; }
393 /// This is an implementation class for the LinkModules function, which is the
394 /// entrypoint for this file.
399 ValueMaterializerTy ValMaterializer;
401 /// Mapping of values from what they used to be in Src, to what they are now
402 /// in DstM. ValueToValueMapTy is a ValueMap, which involves some overhead
403 /// due to the use of Value handles which the Linker doesn't actually need,
404 /// but this allows us to reuse the ValueMapper code.
405 ValueToValueMapTy ValueMap;
407 struct AppendingVarInfo {
408 GlobalVariable *NewGV; // New aggregate global in dest module.
409 const Constant *DstInit; // Old initializer from dest module.
410 const Constant *SrcInit; // Old initializer from src module.
413 std::vector<AppendingVarInfo> AppendingVars;
415 // Set of items not to link in from source.
416 SmallPtrSet<const Value *, 16> DoNotLinkFromSource;
418 // Vector of GlobalValues to lazily link in.
419 std::vector<GlobalValue *> LazilyLinkGlobalValues;
421 /// Functions that have replaced other functions.
422 SmallPtrSet<const Function *, 16> OverridingFunctions;
424 DiagnosticHandlerFunction DiagnosticHandler;
427 ModuleLinker(Module *dstM, Linker::IdentifiedStructTypeSet &Set, Module *srcM,
428 DiagnosticHandlerFunction DiagnosticHandler)
429 : DstM(dstM), SrcM(srcM), TypeMap(Set),
430 ValMaterializer(TypeMap, DstM, LazilyLinkGlobalValues),
431 DiagnosticHandler(DiagnosticHandler) {}
436 bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
437 const GlobalValue &Src);
439 /// Helper method for setting a message and returning an error code.
440 bool emitError(const Twine &Message) {
441 DiagnosticHandler(LinkDiagnosticInfo(DS_Error, Message));
445 void emitWarning(const Twine &Message) {
446 DiagnosticHandler(LinkDiagnosticInfo(DS_Warning, Message));
449 bool getComdatLeader(Module *M, StringRef ComdatName,
450 const GlobalVariable *&GVar);
451 bool computeResultingSelectionKind(StringRef ComdatName,
452 Comdat::SelectionKind Src,
453 Comdat::SelectionKind Dst,
454 Comdat::SelectionKind &Result,
456 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
458 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
461 /// Given a global in the source module, return the global in the
462 /// destination module that is being linked to, if any.
463 GlobalValue *getLinkedToGlobal(const GlobalValue *SrcGV) {
464 // If the source has no name it can't link. If it has local linkage,
465 // there is no name match-up going on.
466 if (!SrcGV->hasName() || SrcGV->hasLocalLinkage())
469 // Otherwise see if we have a match in the destination module's symtab.
470 GlobalValue *DGV = DstM->getNamedValue(SrcGV->getName());
474 // If we found a global with the same name in the dest module, but it has
475 // internal linkage, we are really not doing any linkage here.
476 if (DGV->hasLocalLinkage())
479 // Otherwise, we do in fact link to the destination global.
483 void computeTypeMapping();
485 void upgradeMismatchedGlobalArray(StringRef Name);
486 void upgradeMismatchedGlobals();
488 bool linkAppendingVarProto(GlobalVariable *DstGV,
489 const GlobalVariable *SrcGV);
491 bool linkGlobalValueProto(GlobalValue *GV);
492 bool linkModuleFlagsMetadata();
494 void linkAppendingVarInit(const AppendingVarInfo &AVI);
496 void linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src);
497 bool linkFunctionBody(Function &Dst, Function &Src);
498 void linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src);
499 bool linkGlobalValueBody(GlobalValue &Src);
501 void linkNamedMDNodes();
502 void stripReplacedSubprograms();
506 /// The LLVM SymbolTable class autorenames globals that conflict in the symbol
507 /// table. This is good for all clients except for us. Go through the trouble
508 /// to force this back.
509 static void forceRenaming(GlobalValue *GV, StringRef Name) {
510 // If the global doesn't force its name or if it already has the right name,
511 // there is nothing for us to do.
512 if (GV->hasLocalLinkage() || GV->getName() == Name)
515 Module *M = GV->getParent();
517 // If there is a conflict, rename the conflict.
518 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
519 GV->takeName(ConflictGV);
520 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
521 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
523 GV->setName(Name); // Force the name back
527 /// copy additional attributes (those not needed to construct a GlobalValue)
528 /// from the SrcGV to the DestGV.
529 static void copyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) {
530 DestGV->copyAttributesFrom(SrcGV);
531 forceRenaming(DestGV, SrcGV->getName());
534 static bool isLessConstraining(GlobalValue::VisibilityTypes a,
535 GlobalValue::VisibilityTypes b) {
536 if (a == GlobalValue::HiddenVisibility)
538 if (b == GlobalValue::HiddenVisibility)
540 if (a == GlobalValue::ProtectedVisibility)
542 if (b == GlobalValue::ProtectedVisibility)
547 /// Loop through the global variables in the src module and merge them into the
549 static GlobalVariable *copyGlobalVariableProto(TypeMapTy &TypeMap, Module &DstM,
550 const GlobalVariable *SGVar) {
551 // No linking to be performed or linking from the source: simply create an
552 // identical version of the symbol over in the dest module... the
553 // initializer will be filled in later by LinkGlobalInits.
554 GlobalVariable *NewDGV = new GlobalVariable(
555 DstM, TypeMap.get(SGVar->getType()->getElementType()),
556 SGVar->isConstant(), SGVar->getLinkage(), /*init*/ nullptr,
557 SGVar->getName(), /*insertbefore*/ nullptr, SGVar->getThreadLocalMode(),
558 SGVar->getType()->getAddressSpace());
563 /// Link the function in the source module into the destination module if
564 /// needed, setting up mapping information.
565 static Function *copyFunctionProto(TypeMapTy &TypeMap, Module &DstM,
566 const Function *SF) {
567 // If there is no linkage to be performed or we are linking from the source,
569 return Function::Create(TypeMap.get(SF->getFunctionType()), SF->getLinkage(),
570 SF->getName(), &DstM);
573 /// Set up prototypes for any aliases that come over from the source module.
574 static GlobalAlias *copyGlobalAliasProto(TypeMapTy &TypeMap, Module &DstM,
575 const GlobalAlias *SGA) {
576 // If there is no linkage to be performed or we're linking from the source,
578 auto *PTy = cast<PointerType>(TypeMap.get(SGA->getType()));
579 return GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(),
580 SGA->getLinkage(), SGA->getName(), &DstM);
583 static GlobalValue *copyGlobalValueProto(TypeMapTy &TypeMap, Module &DstM,
584 const GlobalValue *SGV) {
586 if (auto *SGVar = dyn_cast<GlobalVariable>(SGV))
587 NewGV = copyGlobalVariableProto(TypeMap, DstM, SGVar);
588 else if (auto *SF = dyn_cast<Function>(SGV))
589 NewGV = copyFunctionProto(TypeMap, DstM, SF);
591 NewGV = copyGlobalAliasProto(TypeMap, DstM, cast<GlobalAlias>(SGV));
592 copyGVAttributes(NewGV, SGV);
596 Value *ValueMaterializerTy::materializeValueFor(Value *V) {
597 auto *SGV = dyn_cast<GlobalValue>(V);
601 GlobalValue *DGV = copyGlobalValueProto(TypeMap, *DstM, SGV);
603 if (Comdat *SC = SGV->getComdat()) {
604 if (auto *DGO = dyn_cast<GlobalObject>(DGV)) {
605 Comdat *DC = DstM->getOrInsertComdat(SC->getName());
610 LazilyLinkGlobalValues.push_back(SGV);
614 bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName,
615 const GlobalVariable *&GVar) {
616 const GlobalValue *GVal = M->getNamedValue(ComdatName);
617 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
618 GVal = GA->getBaseObject();
620 // We cannot resolve the size of the aliasee yet.
621 return emitError("Linking COMDATs named '" + ComdatName +
622 "': COMDAT key involves incomputable alias size.");
625 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
628 "Linking COMDATs named '" + ComdatName +
629 "': GlobalVariable required for data dependent selection!");
634 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
635 Comdat::SelectionKind Src,
636 Comdat::SelectionKind Dst,
637 Comdat::SelectionKind &Result,
639 // The ability to mix Comdat::SelectionKind::Any with
640 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
641 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
642 Dst == Comdat::SelectionKind::Largest;
643 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
644 Src == Comdat::SelectionKind::Largest;
645 if (DstAnyOrLargest && SrcAnyOrLargest) {
646 if (Dst == Comdat::SelectionKind::Largest ||
647 Src == Comdat::SelectionKind::Largest)
648 Result = Comdat::SelectionKind::Largest;
650 Result = Comdat::SelectionKind::Any;
651 } else if (Src == Dst) {
654 return emitError("Linking COMDATs named '" + ComdatName +
655 "': invalid selection kinds!");
659 case Comdat::SelectionKind::Any:
663 case Comdat::SelectionKind::NoDuplicates:
664 return emitError("Linking COMDATs named '" + ComdatName +
665 "': noduplicates has been violated!");
666 case Comdat::SelectionKind::ExactMatch:
667 case Comdat::SelectionKind::Largest:
668 case Comdat::SelectionKind::SameSize: {
669 const GlobalVariable *DstGV;
670 const GlobalVariable *SrcGV;
671 if (getComdatLeader(DstM, ComdatName, DstGV) ||
672 getComdatLeader(SrcM, ComdatName, SrcGV))
675 const DataLayout &DstDL = DstM->getDataLayout();
676 const DataLayout &SrcDL = SrcM->getDataLayout();
678 DstDL.getTypeAllocSize(DstGV->getType()->getPointerElementType());
680 SrcDL.getTypeAllocSize(SrcGV->getType()->getPointerElementType());
681 if (Result == Comdat::SelectionKind::ExactMatch) {
682 if (SrcGV->getInitializer() != DstGV->getInitializer())
683 return emitError("Linking COMDATs named '" + ComdatName +
684 "': ExactMatch violated!");
686 } else if (Result == Comdat::SelectionKind::Largest) {
687 LinkFromSrc = SrcSize > DstSize;
688 } else if (Result == Comdat::SelectionKind::SameSize) {
689 if (SrcSize != DstSize)
690 return emitError("Linking COMDATs named '" + ComdatName +
691 "': SameSize violated!");
694 llvm_unreachable("unknown selection kind");
703 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
704 Comdat::SelectionKind &Result,
706 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
707 StringRef ComdatName = SrcC->getName();
708 Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable();
709 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
711 if (DstCI == ComdatSymTab.end()) {
712 // Use the comdat if it is only available in one of the modules.
718 const Comdat *DstC = &DstCI->second;
719 Comdat::SelectionKind DSK = DstC->getSelectionKind();
720 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
724 bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
725 const GlobalValue &Dest,
726 const GlobalValue &Src) {
727 // We always have to add Src if it has appending linkage.
728 if (Src.hasAppendingLinkage()) {
733 bool SrcIsDeclaration = Src.isDeclarationForLinker();
734 bool DestIsDeclaration = Dest.isDeclarationForLinker();
736 if (SrcIsDeclaration) {
737 // If Src is external or if both Src & Dest are external.. Just link the
738 // external globals, we aren't adding anything.
739 if (Src.hasDLLImportStorageClass()) {
740 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
741 LinkFromSrc = DestIsDeclaration;
744 // If the Dest is weak, use the source linkage.
745 LinkFromSrc = Dest.hasExternalWeakLinkage();
749 if (DestIsDeclaration) {
750 // If Dest is external but Src is not:
755 if (Src.hasCommonLinkage()) {
756 if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
761 if (!Dest.hasCommonLinkage()) {
766 // FIXME: Make datalayout mandatory and just use getDataLayout().
767 DataLayout DL(Dest.getParent());
769 uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
770 uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
771 LinkFromSrc = SrcSize > DestSize;
775 if (Src.isWeakForLinker()) {
776 assert(!Dest.hasExternalWeakLinkage());
777 assert(!Dest.hasAvailableExternallyLinkage());
779 if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
788 if (Dest.isWeakForLinker()) {
789 assert(Src.hasExternalLinkage());
794 assert(!Src.hasExternalWeakLinkage());
795 assert(!Dest.hasExternalWeakLinkage());
796 assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
797 "Unexpected linkage type!");
798 return emitError("Linking globals named '" + Src.getName() +
799 "': symbol multiply defined!");
802 /// Loop over all of the linked values to compute type mappings. For example,
803 /// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct
804 /// types 'Foo' but one got renamed when the module was loaded into the same
806 void ModuleLinker::computeTypeMapping() {
807 for (GlobalValue &SGV : SrcM->globals()) {
808 GlobalValue *DGV = getLinkedToGlobal(&SGV);
812 if (!DGV->hasAppendingLinkage() || !SGV.hasAppendingLinkage()) {
813 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
817 // Unify the element type of appending arrays.
818 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
819 ArrayType *SAT = cast<ArrayType>(SGV.getType()->getElementType());
820 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
823 for (GlobalValue &SGV : *SrcM) {
824 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
825 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
828 for (GlobalValue &SGV : SrcM->aliases()) {
829 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
830 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
833 // Incorporate types by name, scanning all the types in the source module.
834 // At this point, the destination module may have a type "%foo = { i32 }" for
835 // example. When the source module got loaded into the same LLVMContext, if
836 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
837 std::vector<StructType *> Types = SrcM->getIdentifiedStructTypes();
838 for (StructType *ST : Types) {
842 // Check to see if there is a dot in the name followed by a digit.
843 size_t DotPos = ST->getName().rfind('.');
844 if (DotPos == 0 || DotPos == StringRef::npos ||
845 ST->getName().back() == '.' ||
846 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos + 1])))
849 // Check to see if the destination module has a struct with the prefix name.
850 StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos));
854 // Don't use it if this actually came from the source module. They're in
855 // the same LLVMContext after all. Also don't use it unless the type is
856 // actually used in the destination module. This can happen in situations
861 // %Z = type { %A } %B = type { %C.1 }
862 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
863 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
864 // %C = type { i8* } %B.3 = type { %C.1 }
866 // When we link Module B with Module A, the '%B' in Module B is
867 // used. However, that would then use '%C.1'. But when we process '%C.1',
868 // we prefer to take the '%C' version. So we are then left with both
869 // '%C.1' and '%C' being used for the same types. This leads to some
870 // variables using one type and some using the other.
871 if (TypeMap.DstStructTypesSet.hasType(DST))
872 TypeMap.addTypeMapping(DST, ST);
875 // Now that we have discovered all of the type equivalences, get a body for
876 // any 'opaque' types in the dest module that are now resolved.
877 TypeMap.linkDefinedTypeBodies();
880 static void upgradeGlobalArray(GlobalVariable *GV) {
881 ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
882 StructType *OldTy = cast<StructType>(ATy->getElementType());
883 assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
885 // Get the upgraded 3 element type.
886 PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
887 Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
889 StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
891 // Build new constants with a null third field filled in.
892 Constant *OldInitC = GV->getInitializer();
893 ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
894 if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
895 // Invalid initializer; give up.
897 std::vector<Constant *> Initializers;
898 if (OldInit && OldInit->getNumOperands()) {
899 Value *Null = Constant::getNullValue(VoidPtrTy);
900 for (Use &U : OldInit->operands()) {
901 ConstantStruct *Init = cast<ConstantStruct>(U.get());
902 Initializers.push_back(ConstantStruct::get(
903 NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
906 assert(Initializers.size() == ATy->getNumElements() &&
907 "Failed to copy all array elements");
909 // Replace the old GV with a new one.
910 ATy = ArrayType::get(NewTy, Initializers.size());
911 Constant *NewInit = ConstantArray::get(ATy, Initializers);
912 GlobalVariable *NewGV = new GlobalVariable(
913 *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
914 GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
915 GV->isExternallyInitialized());
916 NewGV->copyAttributesFrom(GV);
918 assert(GV->use_empty() && "program cannot use initializer list");
919 GV->eraseFromParent();
922 void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
923 // Look for the global arrays.
924 auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM->getNamedValue(Name));
927 auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM->getNamedValue(Name));
931 // Check if the types already match.
932 auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
934 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
938 // Grab the element types. We can only upgrade an array of a two-field
939 // struct. Only bother if the other one has three-fields.
940 auto *DstEltTy = cast<StructType>(DstTy->getElementType());
941 auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
942 if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
943 upgradeGlobalArray(DstGV);
946 if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
947 upgradeGlobalArray(SrcGV);
949 // We can't upgrade any other differences.
952 void ModuleLinker::upgradeMismatchedGlobals() {
953 upgradeMismatchedGlobalArray("llvm.global_ctors");
954 upgradeMismatchedGlobalArray("llvm.global_dtors");
957 /// If there were any appending global variables, link them together now.
958 /// Return true on error.
959 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
960 const GlobalVariable *SrcGV) {
962 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
963 return emitError("Linking globals named '" + SrcGV->getName() +
964 "': can only link appending global with another appending global!");
966 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
968 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
969 Type *EltTy = DstTy->getElementType();
971 // Check to see that they two arrays agree on type.
972 if (EltTy != SrcTy->getElementType())
973 return emitError("Appending variables with different element types!");
974 if (DstGV->isConstant() != SrcGV->isConstant())
975 return emitError("Appending variables linked with different const'ness!");
977 if (DstGV->getAlignment() != SrcGV->getAlignment())
979 "Appending variables with different alignment need to be linked!");
981 if (DstGV->getVisibility() != SrcGV->getVisibility())
983 "Appending variables with different visibility need to be linked!");
985 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
987 "Appending variables with different unnamed_addr need to be linked!");
989 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
991 "Appending variables with different section name need to be linked!");
993 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements();
994 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
996 // Create the new global variable.
998 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(),
999 DstGV->getLinkage(), /*init*/nullptr, /*name*/"", DstGV,
1000 DstGV->getThreadLocalMode(),
1001 DstGV->getType()->getAddressSpace());
1003 // Propagate alignment, visibility and section info.
1004 copyGVAttributes(NG, DstGV);
1006 AppendingVarInfo AVI;
1008 AVI.DstInit = DstGV->getInitializer();
1009 AVI.SrcInit = SrcGV->getInitializer();
1010 AppendingVars.push_back(AVI);
1012 // Replace any uses of the two global variables with uses of the new
1014 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
1016 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
1017 DstGV->eraseFromParent();
1019 // Track the source variable so we don't try to link it.
1020 DoNotLinkFromSource.insert(SrcGV);
1025 bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) {
1026 GlobalValue *DGV = getLinkedToGlobal(SGV);
1028 // Handle the ultra special appending linkage case first.
1029 if (DGV && DGV->hasAppendingLinkage())
1030 return linkAppendingVarProto(cast<GlobalVariable>(DGV),
1031 cast<GlobalVariable>(SGV));
1033 bool LinkFromSrc = true;
1034 Comdat *C = nullptr;
1035 GlobalValue::VisibilityTypes Visibility = SGV->getVisibility();
1036 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
1038 if (const Comdat *SC = SGV->getComdat()) {
1039 Comdat::SelectionKind SK;
1040 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1041 C = DstM->getOrInsertComdat(SC->getName());
1042 C->setSelectionKind(SK);
1044 if (shouldLinkFromSource(LinkFromSrc, *DGV, *SGV))
1049 // Track the source global so that we don't attempt to copy it over when
1050 // processing global initializers.
1051 DoNotLinkFromSource.insert(SGV);
1054 // Make sure to remember this mapping.
1056 ConstantExpr::getBitCast(DGV, TypeMap.get(SGV->getType()));
1060 Visibility = isLessConstraining(Visibility, DGV->getVisibility())
1061 ? DGV->getVisibility()
1063 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1066 if (!LinkFromSrc && !DGV)
1073 // If the GV is to be lazily linked, don't create it just yet.
1074 // The ValueMaterializerTy will deal with creating it if it's used.
1075 if (!DGV && (SGV->hasLocalLinkage() || SGV->hasLinkOnceLinkage() ||
1076 SGV->hasAvailableExternallyLinkage())) {
1077 DoNotLinkFromSource.insert(SGV);
1081 NewGV = copyGlobalValueProto(TypeMap, *DstM, SGV);
1083 if (DGV && isa<Function>(DGV))
1084 if (auto *NewF = dyn_cast<Function>(NewGV))
1085 OverridingFunctions.insert(NewF);
1088 NewGV->setUnnamedAddr(HasUnnamedAddr);
1089 NewGV->setVisibility(Visibility);
1091 if (auto *NewGO = dyn_cast<GlobalObject>(NewGV)) {
1093 NewGO->setComdat(C);
1095 if (DGV && DGV->hasCommonLinkage() && SGV->hasCommonLinkage())
1096 NewGO->setAlignment(std::max(DGV->getAlignment(), SGV->getAlignment()));
1099 if (auto *NewGVar = dyn_cast<GlobalVariable>(NewGV)) {
1100 auto *DGVar = dyn_cast_or_null<GlobalVariable>(DGV);
1101 auto *SGVar = dyn_cast<GlobalVariable>(SGV);
1102 if (DGVar && SGVar && DGVar->isDeclaration() && SGVar->isDeclaration() &&
1103 (!DGVar->isConstant() || !SGVar->isConstant()))
1104 NewGVar->setConstant(false);
1107 // Make sure to remember this mapping.
1110 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewGV, DGV->getType()));
1111 DGV->eraseFromParent();
1113 ValueMap[SGV] = NewGV;
1119 static void getArrayElements(const Constant *C,
1120 SmallVectorImpl<Constant *> &Dest) {
1121 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1123 for (unsigned i = 0; i != NumElements; ++i)
1124 Dest.push_back(C->getAggregateElement(i));
1127 void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) {
1128 // Merge the initializer.
1129 SmallVector<Constant *, 16> DstElements;
1130 getArrayElements(AVI.DstInit, DstElements);
1132 SmallVector<Constant *, 16> SrcElements;
1133 getArrayElements(AVI.SrcInit, SrcElements);
1135 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
1137 StringRef Name = AVI.NewGV->getName();
1138 bool IsNewStructor =
1139 (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
1140 cast<StructType>(NewType->getElementType())->getNumElements() == 3;
1142 for (auto *V : SrcElements) {
1143 if (IsNewStructor) {
1144 Constant *Key = V->getAggregateElement(2);
1145 if (DoNotLinkFromSource.count(Key))
1148 DstElements.push_back(
1149 MapValue(V, ValueMap, RF_None, &TypeMap, &ValMaterializer));
1151 if (IsNewStructor) {
1152 NewType = ArrayType::get(NewType->getElementType(), DstElements.size());
1153 AVI.NewGV->mutateType(PointerType::get(NewType, 0));
1156 AVI.NewGV->setInitializer(ConstantArray::get(NewType, DstElements));
1159 /// Update the initializers in the Dest module now that all globals that may be
1160 /// referenced are in Dest.
1161 void ModuleLinker::linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src) {
1162 // Figure out what the initializer looks like in the dest module.
1163 Dst.setInitializer(MapValue(Src.getInitializer(), ValueMap, RF_None, &TypeMap,
1167 /// Copy the source function over into the dest function and fix up references
1168 /// to values. At this point we know that Dest is an external function, and
1169 /// that Src is not.
1170 bool ModuleLinker::linkFunctionBody(Function &Dst, Function &Src) {
1171 assert(Dst.isDeclaration() && !Src.isDeclaration());
1173 // Materialize if needed.
1174 if (std::error_code EC = Src.materialize())
1175 return emitError(EC.message());
1177 // Link in the prefix data.
1178 if (Src.hasPrefixData())
1179 Dst.setPrefixData(MapValue(Src.getPrefixData(), ValueMap, RF_None, &TypeMap,
1182 // Link in the prologue data.
1183 if (Src.hasPrologueData())
1184 Dst.setPrologueData(MapValue(Src.getPrologueData(), ValueMap, RF_None,
1185 &TypeMap, &ValMaterializer));
1187 // Go through and convert function arguments over, remembering the mapping.
1188 Function::arg_iterator DI = Dst.arg_begin();
1189 for (Argument &Arg : Src.args()) {
1190 DI->setName(Arg.getName()); // Copy the name over.
1192 // Add a mapping to our mapping.
1193 ValueMap[&Arg] = DI;
1197 // Splice the body of the source function into the dest function.
1198 Dst.getBasicBlockList().splice(Dst.end(), Src.getBasicBlockList());
1200 // At this point, all of the instructions and values of the function are now
1201 // copied over. The only problem is that they are still referencing values in
1202 // the Source function as operands. Loop through all of the operands of the
1203 // functions and patch them up to point to the local versions.
1204 for (BasicBlock &BB : Dst)
1205 for (Instruction &I : BB)
1206 RemapInstruction(&I, ValueMap, RF_IgnoreMissingEntries, &TypeMap,
1209 // There is no need to map the arguments anymore.
1210 for (Argument &Arg : Src.args())
1211 ValueMap.erase(&Arg);
1213 Src.Dematerialize();
1217 void ModuleLinker::linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src) {
1218 Constant *Aliasee = Src.getAliasee();
1220 MapValue(Aliasee, ValueMap, RF_None, &TypeMap, &ValMaterializer);
1221 Dst.setAliasee(Val);
1224 bool ModuleLinker::linkGlobalValueBody(GlobalValue &Src) {
1225 Value *Dst = ValueMap[&Src];
1227 if (auto *F = dyn_cast<Function>(&Src))
1228 return linkFunctionBody(cast<Function>(*Dst), *F);
1229 if (auto *GVar = dyn_cast<GlobalVariable>(&Src)) {
1230 linkGlobalInit(cast<GlobalVariable>(*Dst), *GVar);
1233 linkAliasBody(cast<GlobalAlias>(*Dst), cast<GlobalAlias>(Src));
1237 /// Insert all of the named MDNodes in Src into the Dest module.
1238 void ModuleLinker::linkNamedMDNodes() {
1239 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1240 for (Module::const_named_metadata_iterator I = SrcM->named_metadata_begin(),
1241 E = SrcM->named_metadata_end(); I != E; ++I) {
1242 // Don't link module flags here. Do them separately.
1243 if (&*I == SrcModFlags) continue;
1244 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(I->getName());
1245 // Add Src elements into Dest node.
1246 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
1247 DestNMD->addOperand(MapMetadata(I->getOperand(i), ValueMap, RF_None,
1248 &TypeMap, &ValMaterializer));
1252 /// Drop DISubprograms that have been superseded.
1254 /// FIXME: this creates an asymmetric result: we strip losing subprograms from
1255 /// DstM, but leave losing subprograms in SrcM. Instead we should also strip
1256 /// losers from SrcM, but this requires extra plumbing in MapMetadata.
1257 void ModuleLinker::stripReplacedSubprograms() {
1258 // Avoid quadratic runtime by returning early when there's nothing to do.
1259 if (OverridingFunctions.empty())
1262 // Move the functions now, so the set gets cleared even on early returns.
1263 auto Functions = std::move(OverridingFunctions);
1264 OverridingFunctions.clear();
1266 // Drop subprograms whose functions have been overridden by the new compile
1268 NamedMDNode *CompileUnits = DstM->getNamedMetadata("llvm.dbg.cu");
1271 for (unsigned I = 0, E = CompileUnits->getNumOperands(); I != E; ++I) {
1272 DICompileUnit CU(CompileUnits->getOperand(I));
1273 assert(CU && "Expected valid compile unit");
1275 DITypedArray<DISubprogram> SPs(CU.getSubprograms());
1276 assert(SPs && "Expected valid subprogram array");
1278 SmallVector<Metadata *, 16> NewSPs;
1279 NewSPs.reserve(SPs.getNumElements());
1280 for (unsigned S = 0, SE = SPs.getNumElements(); S != SE; ++S) {
1281 DISubprogram SP = SPs.getElement(S);
1282 if (SP && SP.getFunction() && Functions.count(SP.getFunction()))
1285 NewSPs.push_back(SP);
1288 // Redirect operand to the overriding subprogram.
1289 if (NewSPs.size() != SPs.getNumElements())
1290 CU.replaceSubprograms(DIArray(MDNode::get(DstM->getContext(), NewSPs)));
1294 /// Merge the linker flags in Src into the Dest module.
1295 bool ModuleLinker::linkModuleFlagsMetadata() {
1296 // If the source module has no module flags, we are done.
1297 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1298 if (!SrcModFlags) return false;
1300 // If the destination module doesn't have module flags yet, then just copy
1301 // over the source module's flags.
1302 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
1303 if (DstModFlags->getNumOperands() == 0) {
1304 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1305 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1310 // First build a map of the existing module flags and requirements.
1311 DenseMap<MDString *, std::pair<MDNode *, unsigned>> Flags;
1312 SmallSetVector<MDNode*, 16> Requirements;
1313 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1314 MDNode *Op = DstModFlags->getOperand(I);
1315 ConstantInt *Behavior = mdconst::extract<ConstantInt>(Op->getOperand(0));
1316 MDString *ID = cast<MDString>(Op->getOperand(1));
1318 if (Behavior->getZExtValue() == Module::Require) {
1319 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1321 Flags[ID] = std::make_pair(Op, I);
1325 // Merge in the flags from the source module, and also collect its set of
1327 bool HasErr = false;
1328 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1329 MDNode *SrcOp = SrcModFlags->getOperand(I);
1330 ConstantInt *SrcBehavior =
1331 mdconst::extract<ConstantInt>(SrcOp->getOperand(0));
1332 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1335 std::tie(DstOp, DstIndex) = Flags.lookup(ID);
1336 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1338 // If this is a requirement, add it and continue.
1339 if (SrcBehaviorValue == Module::Require) {
1340 // If the destination module does not already have this requirement, add
1342 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1343 DstModFlags->addOperand(SrcOp);
1348 // If there is no existing flag with this ID, just add it.
1350 Flags[ID] = std::make_pair(SrcOp, DstModFlags->getNumOperands());
1351 DstModFlags->addOperand(SrcOp);
1355 // Otherwise, perform a merge.
1356 ConstantInt *DstBehavior =
1357 mdconst::extract<ConstantInt>(DstOp->getOperand(0));
1358 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1360 // If either flag has override behavior, handle it first.
1361 if (DstBehaviorValue == Module::Override) {
1362 // Diagnose inconsistent flags which both have override behavior.
1363 if (SrcBehaviorValue == Module::Override &&
1364 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1365 HasErr |= emitError("linking module flags '" + ID->getString() +
1366 "': IDs have conflicting override values");
1369 } else if (SrcBehaviorValue == Module::Override) {
1370 // Update the destination flag to that of the source.
1371 DstModFlags->setOperand(DstIndex, SrcOp);
1372 Flags[ID].first = SrcOp;
1376 // Diagnose inconsistent merge behavior types.
1377 if (SrcBehaviorValue != DstBehaviorValue) {
1378 HasErr |= emitError("linking module flags '" + ID->getString() +
1379 "': IDs have conflicting behaviors");
1383 auto replaceDstValue = [&](MDNode *New) {
1384 Metadata *FlagOps[] = {DstOp->getOperand(0), ID, New};
1385 MDNode *Flag = MDNode::get(DstM->getContext(), FlagOps);
1386 DstModFlags->setOperand(DstIndex, Flag);
1387 Flags[ID].first = Flag;
1390 // Perform the merge for standard behavior types.
1391 switch (SrcBehaviorValue) {
1392 case Module::Require:
1393 case Module::Override: llvm_unreachable("not possible");
1394 case Module::Error: {
1395 // Emit an error if the values differ.
1396 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1397 HasErr |= emitError("linking module flags '" + ID->getString() +
1398 "': IDs have conflicting values");
1402 case Module::Warning: {
1403 // Emit a warning if the values differ.
1404 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1405 emitWarning("linking module flags '" + ID->getString() +
1406 "': IDs have conflicting values");
1410 case Module::Append: {
1411 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1412 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1413 SmallVector<Metadata *, 8> MDs;
1414 MDs.reserve(DstValue->getNumOperands() + SrcValue->getNumOperands());
1415 MDs.append(DstValue->op_begin(), DstValue->op_end());
1416 MDs.append(SrcValue->op_begin(), SrcValue->op_end());
1418 replaceDstValue(MDNode::get(DstM->getContext(), MDs));
1421 case Module::AppendUnique: {
1422 SmallSetVector<Metadata *, 16> Elts;
1423 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1424 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1425 Elts.insert(DstValue->op_begin(), DstValue->op_end());
1426 Elts.insert(SrcValue->op_begin(), SrcValue->op_end());
1428 replaceDstValue(MDNode::get(DstM->getContext(),
1429 makeArrayRef(Elts.begin(), Elts.end())));
1435 // Check all of the requirements.
1436 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1437 MDNode *Requirement = Requirements[I];
1438 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1439 Metadata *ReqValue = Requirement->getOperand(1);
1441 MDNode *Op = Flags[Flag].first;
1442 if (!Op || Op->getOperand(2) != ReqValue) {
1443 HasErr |= emitError("linking module flags '" + Flag->getString() +
1444 "': does not have the required value");
1452 // This function returns true if the triples match.
1453 static bool triplesMatch(const Triple &T0, const Triple &T1) {
1454 // If vendor is apple, ignore the version number.
1455 if (T0.getVendor() == Triple::Apple)
1456 return T0.getArch() == T1.getArch() &&
1457 T0.getSubArch() == T1.getSubArch() &&
1458 T0.getVendor() == T1.getVendor() &&
1459 T0.getOS() == T1.getOS();
1464 // This function returns the merged triple.
1465 static std::string mergeTriples(const Triple &SrcTriple, const Triple &DstTriple) {
1466 // If vendor is apple, pick the triple with the larger version number.
1467 if (SrcTriple.getVendor() == Triple::Apple)
1468 if (DstTriple.isOSVersionLT(SrcTriple))
1469 return SrcTriple.str();
1471 return DstTriple.str();
1474 bool ModuleLinker::run() {
1475 assert(DstM && "Null destination module");
1476 assert(SrcM && "Null source module");
1478 // Inherit the target data from the source module if the destination module
1479 // doesn't have one already.
1480 if (DstM->getDataLayout().isDefault())
1481 DstM->setDataLayout(SrcM->getDataLayout());
1483 if (SrcM->getDataLayout() != DstM->getDataLayout()) {
1484 emitWarning("Linking two modules of different data layouts: '" +
1485 SrcM->getModuleIdentifier() + "' is '" +
1486 SrcM->getDataLayoutStr() + "' whereas '" +
1487 DstM->getModuleIdentifier() + "' is '" +
1488 DstM->getDataLayoutStr() + "'\n");
1491 // Copy the target triple from the source to dest if the dest's is empty.
1492 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
1493 DstM->setTargetTriple(SrcM->getTargetTriple());
1495 Triple SrcTriple(SrcM->getTargetTriple()), DstTriple(DstM->getTargetTriple());
1497 if (!SrcM->getTargetTriple().empty() && !triplesMatch(SrcTriple, DstTriple))
1498 emitWarning("Linking two modules of different target triples: " +
1499 SrcM->getModuleIdentifier() + "' is '" +
1500 SrcM->getTargetTriple() + "' whereas '" +
1501 DstM->getModuleIdentifier() + "' is '" +
1502 DstM->getTargetTriple() + "'\n");
1504 DstM->setTargetTriple(mergeTriples(SrcTriple, DstTriple));
1506 // Append the module inline asm string.
1507 if (!SrcM->getModuleInlineAsm().empty()) {
1508 if (DstM->getModuleInlineAsm().empty())
1509 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
1511 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
1512 SrcM->getModuleInlineAsm());
1515 // Loop over all of the linked values to compute type mappings.
1516 computeTypeMapping();
1518 ComdatsChosen.clear();
1519 for (const auto &SMEC : SrcM->getComdatSymbolTable()) {
1520 const Comdat &C = SMEC.getValue();
1521 if (ComdatsChosen.count(&C))
1523 Comdat::SelectionKind SK;
1525 if (getComdatResult(&C, SK, LinkFromSrc))
1527 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1530 // Upgrade mismatched global arrays.
1531 upgradeMismatchedGlobals();
1533 // Insert all of the globals in src into the DstM module... without linking
1534 // initializers (which could refer to functions not yet mapped over).
1535 for (Module::global_iterator I = SrcM->global_begin(),
1536 E = SrcM->global_end(); I != E; ++I)
1537 if (linkGlobalValueProto(I))
1540 // Link the functions together between the two modules, without doing function
1541 // bodies... this just adds external function prototypes to the DstM
1542 // function... We do this so that when we begin processing function bodies,
1543 // all of the global values that may be referenced are available in our
1545 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I)
1546 if (linkGlobalValueProto(I))
1549 // If there were any aliases, link them now.
1550 for (Module::alias_iterator I = SrcM->alias_begin(),
1551 E = SrcM->alias_end(); I != E; ++I)
1552 if (linkGlobalValueProto(I))
1555 for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i)
1556 linkAppendingVarInit(AppendingVars[i]);
1558 for (const auto &Entry : DstM->getComdatSymbolTable()) {
1559 const Comdat &C = Entry.getValue();
1560 if (C.getSelectionKind() == Comdat::Any)
1562 const GlobalValue *GV = SrcM->getNamedValue(C.getName());
1564 MapValue(GV, ValueMap, RF_None, &TypeMap, &ValMaterializer);
1567 // Link in the function bodies that are defined in the source module into
1569 for (Function &SF : *SrcM) {
1570 // Skip if no body (function is external).
1571 if (SF.isDeclaration())
1574 // Skip if not linking from source.
1575 if (DoNotLinkFromSource.count(&SF))
1578 if (linkGlobalValueBody(SF))
1582 // Resolve all uses of aliases with aliasees.
1583 for (GlobalAlias &Src : SrcM->aliases()) {
1584 if (DoNotLinkFromSource.count(&Src))
1586 linkGlobalValueBody(Src);
1589 // Strip replaced subprograms before linking together compile units.
1590 stripReplacedSubprograms();
1592 // Remap all of the named MDNodes in Src into the DstM module. We do this
1593 // after linking GlobalValues so that MDNodes that reference GlobalValues
1594 // are properly remapped.
1597 // Merge the module flags into the DstM module.
1598 if (linkModuleFlagsMetadata())
1601 // Update the initializers in the DstM module now that all globals that may
1602 // be referenced are in DstM.
1603 for (GlobalVariable &Src : SrcM->globals()) {
1604 // Only process initialized GV's or ones not already in dest.
1605 if (!Src.hasInitializer() || DoNotLinkFromSource.count(&Src))
1607 linkGlobalValueBody(Src);
1610 // Process vector of lazily linked in functions.
1611 while (!LazilyLinkGlobalValues.empty()) {
1612 GlobalValue *SGV = LazilyLinkGlobalValues.back();
1613 LazilyLinkGlobalValues.pop_back();
1615 assert(!SGV->isDeclaration() && "users should not pass down decls");
1616 if (linkGlobalValueBody(*SGV))
1623 Linker::StructTypeKeyInfo::KeyTy::KeyTy(ArrayRef<Type *> E, bool P)
1624 : ETypes(E), IsPacked(P) {}
1626 Linker::StructTypeKeyInfo::KeyTy::KeyTy(const StructType *ST)
1627 : ETypes(ST->elements()), IsPacked(ST->isPacked()) {}
1629 bool Linker::StructTypeKeyInfo::KeyTy::operator==(const KeyTy &That) const {
1630 if (IsPacked != That.IsPacked)
1632 if (ETypes != That.ETypes)
1637 bool Linker::StructTypeKeyInfo::KeyTy::operator!=(const KeyTy &That) const {
1638 return !this->operator==(That);
1641 StructType *Linker::StructTypeKeyInfo::getEmptyKey() {
1642 return DenseMapInfo<StructType *>::getEmptyKey();
1645 StructType *Linker::StructTypeKeyInfo::getTombstoneKey() {
1646 return DenseMapInfo<StructType *>::getTombstoneKey();
1649 unsigned Linker::StructTypeKeyInfo::getHashValue(const KeyTy &Key) {
1650 return hash_combine(hash_combine_range(Key.ETypes.begin(), Key.ETypes.end()),
1654 unsigned Linker::StructTypeKeyInfo::getHashValue(const StructType *ST) {
1655 return getHashValue(KeyTy(ST));
1658 bool Linker::StructTypeKeyInfo::isEqual(const KeyTy &LHS,
1659 const StructType *RHS) {
1660 if (RHS == getEmptyKey() || RHS == getTombstoneKey())
1662 return LHS == KeyTy(RHS);
1665 bool Linker::StructTypeKeyInfo::isEqual(const StructType *LHS,
1666 const StructType *RHS) {
1667 if (RHS == getEmptyKey())
1668 return LHS == getEmptyKey();
1670 if (RHS == getTombstoneKey())
1671 return LHS == getTombstoneKey();
1673 return KeyTy(LHS) == KeyTy(RHS);
1676 void Linker::IdentifiedStructTypeSet::addNonOpaque(StructType *Ty) {
1677 assert(!Ty->isOpaque());
1678 NonOpaqueStructTypes.insert(Ty);
1681 void Linker::IdentifiedStructTypeSet::addOpaque(StructType *Ty) {
1682 assert(Ty->isOpaque());
1683 OpaqueStructTypes.insert(Ty);
1687 Linker::IdentifiedStructTypeSet::findNonOpaque(ArrayRef<Type *> ETypes,
1689 Linker::StructTypeKeyInfo::KeyTy Key(ETypes, IsPacked);
1690 auto I = NonOpaqueStructTypes.find_as(Key);
1691 if (I == NonOpaqueStructTypes.end())
1696 bool Linker::IdentifiedStructTypeSet::hasType(StructType *Ty) {
1698 return OpaqueStructTypes.count(Ty);
1699 auto I = NonOpaqueStructTypes.find(Ty);
1700 if (I == NonOpaqueStructTypes.end())
1705 void Linker::init(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
1706 this->Composite = M;
1707 this->DiagnosticHandler = DiagnosticHandler;
1709 TypeFinder StructTypes;
1710 StructTypes.run(*M, true);
1711 for (StructType *Ty : StructTypes) {
1713 IdentifiedStructTypes.addOpaque(Ty);
1715 IdentifiedStructTypes.addNonOpaque(Ty);
1719 Linker::Linker(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
1720 init(M, DiagnosticHandler);
1723 Linker::Linker(Module *M) {
1724 init(M, [this](const DiagnosticInfo &DI) {
1725 Composite->getContext().diagnose(DI);
1732 void Linker::deleteModule() {
1734 Composite = nullptr;
1737 bool Linker::linkInModule(Module *Src) {
1738 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,
1740 bool RetCode = TheLinker.run();
1741 Composite->dropTriviallyDeadConstantArrays();
1745 void Linker::setModule(Module *Dst) {
1746 init(Dst, DiagnosticHandler);
1749 //===----------------------------------------------------------------------===//
1750 // LinkModules entrypoint.
1751 //===----------------------------------------------------------------------===//
1753 /// This function links two modules together, with the resulting Dest module
1754 /// modified to be the composite of the two input modules. If an error occurs,
1755 /// true is returned and ErrorMsg (if not null) is set to indicate the problem.
1756 /// Upon failure, the Dest module could be in a modified state, and shouldn't be
1757 /// relied on to be consistent.
1758 bool Linker::LinkModules(Module *Dest, Module *Src,
1759 DiagnosticHandlerFunction DiagnosticHandler) {
1760 Linker L(Dest, DiagnosticHandler);
1761 return L.linkInModule(Src);
1764 bool Linker::LinkModules(Module *Dest, Module *Src) {
1766 return L.linkInModule(Src);
1769 //===----------------------------------------------------------------------===//
1771 //===----------------------------------------------------------------------===//
1773 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
1774 LLVMLinkerMode Unused, char **OutMessages) {
1775 Module *D = unwrap(Dest);
1776 std::string Message;
1777 raw_string_ostream Stream(Message);
1778 DiagnosticPrinterRawOStream DP(Stream);
1780 LLVMBool Result = Linker::LinkModules(
1781 D, unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); });
1783 if (OutMessages && Result)
1784 *OutMessages = strdup(Message.c_str());