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 final : 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.
431 ModuleLinker(Module *dstM, Linker::IdentifiedStructTypeSet &Set, Module *srcM,
432 DiagnosticHandlerFunction DiagnosticHandler, unsigned Flags)
433 : DstM(dstM), SrcM(srcM), TypeMap(Set),
434 ValMaterializer(TypeMap, DstM, LazilyLinkGlobalValues),
435 DiagnosticHandler(DiagnosticHandler), Flags(Flags) {}
439 bool shouldOverrideFromSrc() { return Flags & Linker::OverrideFromSrc; }
440 bool shouldLinkOnlyNeeded() { return Flags & Linker::LinkOnlyNeeded; }
441 bool shouldInternalizeLinkedSymbols() {
442 return Flags & Linker::InternalizeLinkedSymbols;
446 bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
447 const GlobalValue &Src);
449 /// Helper method for setting a message and returning an error code.
450 bool emitError(const Twine &Message) {
451 DiagnosticHandler(LinkDiagnosticInfo(DS_Error, Message));
455 void emitWarning(const Twine &Message) {
456 DiagnosticHandler(LinkDiagnosticInfo(DS_Warning, Message));
459 bool getComdatLeader(Module *M, StringRef ComdatName,
460 const GlobalVariable *&GVar);
461 bool computeResultingSelectionKind(StringRef ComdatName,
462 Comdat::SelectionKind Src,
463 Comdat::SelectionKind Dst,
464 Comdat::SelectionKind &Result,
466 std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
468 bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
471 /// Given a global in the source module, return the global in the
472 /// destination module that is being linked to, if any.
473 GlobalValue *getLinkedToGlobal(const GlobalValue *SrcGV) {
474 // If the source has no name it can't link. If it has local linkage,
475 // there is no name match-up going on.
476 if (!SrcGV->hasName() || SrcGV->hasLocalLinkage())
479 // Otherwise see if we have a match in the destination module's symtab.
480 GlobalValue *DGV = DstM->getNamedValue(SrcGV->getName());
484 // If we found a global with the same name in the dest module, but it has
485 // internal linkage, we are really not doing any linkage here.
486 if (DGV->hasLocalLinkage())
489 // Otherwise, we do in fact link to the destination global.
493 void computeTypeMapping();
495 void upgradeMismatchedGlobalArray(StringRef Name);
496 void upgradeMismatchedGlobals();
498 bool linkAppendingVarProto(GlobalVariable *DstGV,
499 const GlobalVariable *SrcGV);
501 bool linkGlobalValueProto(GlobalValue *GV);
502 bool linkModuleFlagsMetadata();
504 void linkAppendingVarInit(const AppendingVarInfo &AVI);
506 void linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src);
507 bool linkFunctionBody(Function &Dst, Function &Src);
508 void linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src);
509 bool linkGlobalValueBody(GlobalValue &Src);
511 void linkNamedMDNodes();
512 void stripReplacedSubprograms();
516 /// The LLVM SymbolTable class autorenames globals that conflict in the symbol
517 /// table. This is good for all clients except for us. Go through the trouble
518 /// to force this back.
519 static void forceRenaming(GlobalValue *GV, StringRef Name) {
520 // If the global doesn't force its name or if it already has the right name,
521 // there is nothing for us to do.
522 if (GV->hasLocalLinkage() || GV->getName() == Name)
525 Module *M = GV->getParent();
527 // If there is a conflict, rename the conflict.
528 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
529 GV->takeName(ConflictGV);
530 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
531 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
533 GV->setName(Name); // Force the name back
537 /// copy additional attributes (those not needed to construct a GlobalValue)
538 /// from the SrcGV to the DestGV.
539 static void copyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) {
540 DestGV->copyAttributesFrom(SrcGV);
541 forceRenaming(DestGV, SrcGV->getName());
544 static bool isLessConstraining(GlobalValue::VisibilityTypes a,
545 GlobalValue::VisibilityTypes b) {
546 if (a == GlobalValue::HiddenVisibility)
548 if (b == GlobalValue::HiddenVisibility)
550 if (a == GlobalValue::ProtectedVisibility)
552 if (b == GlobalValue::ProtectedVisibility)
557 /// Loop through the global variables in the src module and merge them into the
559 static GlobalVariable *copyGlobalVariableProto(TypeMapTy &TypeMap, Module &DstM,
560 const GlobalVariable *SGVar) {
561 // No linking to be performed or linking from the source: simply create an
562 // identical version of the symbol over in the dest module... the
563 // initializer will be filled in later by LinkGlobalInits.
564 GlobalVariable *NewDGV = new GlobalVariable(
565 DstM, TypeMap.get(SGVar->getType()->getElementType()),
566 SGVar->isConstant(), SGVar->getLinkage(), /*init*/ nullptr,
567 SGVar->getName(), /*insertbefore*/ nullptr, SGVar->getThreadLocalMode(),
568 SGVar->getType()->getAddressSpace());
573 /// Link the function in the source module into the destination module if
574 /// needed, setting up mapping information.
575 static Function *copyFunctionProto(TypeMapTy &TypeMap, Module &DstM,
576 const Function *SF) {
577 // If there is no linkage to be performed or we are linking from the source,
579 return Function::Create(TypeMap.get(SF->getFunctionType()), SF->getLinkage(),
580 SF->getName(), &DstM);
583 /// Set up prototypes for any aliases that come over from the source module.
584 static GlobalAlias *copyGlobalAliasProto(TypeMapTy &TypeMap, Module &DstM,
585 const GlobalAlias *SGA) {
586 // If there is no linkage to be performed or we're linking from the source,
588 auto *Ty = TypeMap.get(SGA->getValueType());
589 return GlobalAlias::create(Ty, SGA->getType()->getPointerAddressSpace(),
590 SGA->getLinkage(), SGA->getName(), &DstM);
593 static GlobalValue *copyGlobalValueProto(TypeMapTy &TypeMap, Module &DstM,
594 const GlobalValue *SGV) {
596 if (auto *SGVar = dyn_cast<GlobalVariable>(SGV))
597 NewGV = copyGlobalVariableProto(TypeMap, DstM, SGVar);
598 else if (auto *SF = dyn_cast<Function>(SGV))
599 NewGV = copyFunctionProto(TypeMap, DstM, SF);
601 NewGV = copyGlobalAliasProto(TypeMap, DstM, cast<GlobalAlias>(SGV));
602 copyGVAttributes(NewGV, SGV);
606 Value *ValueMaterializerTy::materializeValueFor(Value *V) {
607 auto *SGV = dyn_cast<GlobalValue>(V);
611 GlobalValue *DGV = copyGlobalValueProto(TypeMap, *DstM, SGV);
613 if (Comdat *SC = SGV->getComdat()) {
614 if (auto *DGO = dyn_cast<GlobalObject>(DGV)) {
615 Comdat *DC = DstM->getOrInsertComdat(SC->getName());
620 LazilyLinkGlobalValues.push_back(SGV);
624 bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName,
625 const GlobalVariable *&GVar) {
626 const GlobalValue *GVal = M->getNamedValue(ComdatName);
627 if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
628 GVal = GA->getBaseObject();
630 // We cannot resolve the size of the aliasee yet.
631 return emitError("Linking COMDATs named '" + ComdatName +
632 "': COMDAT key involves incomputable alias size.");
635 GVar = dyn_cast_or_null<GlobalVariable>(GVal);
638 "Linking COMDATs named '" + ComdatName +
639 "': GlobalVariable required for data dependent selection!");
644 bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
645 Comdat::SelectionKind Src,
646 Comdat::SelectionKind Dst,
647 Comdat::SelectionKind &Result,
649 // The ability to mix Comdat::SelectionKind::Any with
650 // Comdat::SelectionKind::Largest is a behavior that comes from COFF.
651 bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
652 Dst == Comdat::SelectionKind::Largest;
653 bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
654 Src == Comdat::SelectionKind::Largest;
655 if (DstAnyOrLargest && SrcAnyOrLargest) {
656 if (Dst == Comdat::SelectionKind::Largest ||
657 Src == Comdat::SelectionKind::Largest)
658 Result = Comdat::SelectionKind::Largest;
660 Result = Comdat::SelectionKind::Any;
661 } else if (Src == Dst) {
664 return emitError("Linking COMDATs named '" + ComdatName +
665 "': invalid selection kinds!");
669 case Comdat::SelectionKind::Any:
673 case Comdat::SelectionKind::NoDuplicates:
674 return emitError("Linking COMDATs named '" + ComdatName +
675 "': noduplicates has been violated!");
676 case Comdat::SelectionKind::ExactMatch:
677 case Comdat::SelectionKind::Largest:
678 case Comdat::SelectionKind::SameSize: {
679 const GlobalVariable *DstGV;
680 const GlobalVariable *SrcGV;
681 if (getComdatLeader(DstM, ComdatName, DstGV) ||
682 getComdatLeader(SrcM, ComdatName, SrcGV))
685 const DataLayout &DstDL = DstM->getDataLayout();
686 const DataLayout &SrcDL = SrcM->getDataLayout();
688 DstDL.getTypeAllocSize(DstGV->getType()->getPointerElementType());
690 SrcDL.getTypeAllocSize(SrcGV->getType()->getPointerElementType());
691 if (Result == Comdat::SelectionKind::ExactMatch) {
692 if (SrcGV->getInitializer() != DstGV->getInitializer())
693 return emitError("Linking COMDATs named '" + ComdatName +
694 "': ExactMatch violated!");
696 } else if (Result == Comdat::SelectionKind::Largest) {
697 LinkFromSrc = SrcSize > DstSize;
698 } else if (Result == Comdat::SelectionKind::SameSize) {
699 if (SrcSize != DstSize)
700 return emitError("Linking COMDATs named '" + ComdatName +
701 "': SameSize violated!");
704 llvm_unreachable("unknown selection kind");
713 bool ModuleLinker::getComdatResult(const Comdat *SrcC,
714 Comdat::SelectionKind &Result,
716 Comdat::SelectionKind SSK = SrcC->getSelectionKind();
717 StringRef ComdatName = SrcC->getName();
718 Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable();
719 Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
721 if (DstCI == ComdatSymTab.end()) {
722 // Use the comdat if it is only available in one of the modules.
728 const Comdat *DstC = &DstCI->second;
729 Comdat::SelectionKind DSK = DstC->getSelectionKind();
730 return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
734 bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
735 const GlobalValue &Dest,
736 const GlobalValue &Src) {
737 // Should we unconditionally use the Src?
738 if (shouldOverrideFromSrc()) {
743 // We always have to add Src if it has appending linkage.
744 if (Src.hasAppendingLinkage()) {
749 bool SrcIsDeclaration = Src.isDeclarationForLinker();
750 bool DestIsDeclaration = Dest.isDeclarationForLinker();
752 if (SrcIsDeclaration) {
753 // If Src is external or if both Src & Dest are external.. Just link the
754 // external globals, we aren't adding anything.
755 if (Src.hasDLLImportStorageClass()) {
756 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
757 LinkFromSrc = DestIsDeclaration;
760 // If the Dest is weak, use the source linkage.
761 LinkFromSrc = Dest.hasExternalWeakLinkage();
765 if (DestIsDeclaration) {
766 // If Dest is external but Src is not:
771 if (Src.hasCommonLinkage()) {
772 if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) {
777 if (!Dest.hasCommonLinkage()) {
782 const DataLayout &DL = Dest.getParent()->getDataLayout();
783 uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
784 uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
785 LinkFromSrc = SrcSize > DestSize;
789 if (Src.isWeakForLinker()) {
790 assert(!Dest.hasExternalWeakLinkage());
791 assert(!Dest.hasAvailableExternallyLinkage());
793 if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) {
802 if (Dest.isWeakForLinker()) {
803 assert(Src.hasExternalLinkage());
808 assert(!Src.hasExternalWeakLinkage());
809 assert(!Dest.hasExternalWeakLinkage());
810 assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
811 "Unexpected linkage type!");
812 return emitError("Linking globals named '" + Src.getName() +
813 "': symbol multiply defined!");
816 /// Loop over all of the linked values to compute type mappings. For example,
817 /// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct
818 /// types 'Foo' but one got renamed when the module was loaded into the same
820 void ModuleLinker::computeTypeMapping() {
821 for (GlobalValue &SGV : SrcM->globals()) {
822 GlobalValue *DGV = getLinkedToGlobal(&SGV);
826 if (!DGV->hasAppendingLinkage() || !SGV.hasAppendingLinkage()) {
827 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
831 // Unify the element type of appending arrays.
832 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
833 ArrayType *SAT = cast<ArrayType>(SGV.getType()->getElementType());
834 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
837 for (GlobalValue &SGV : *SrcM) {
838 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
839 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
842 for (GlobalValue &SGV : SrcM->aliases()) {
843 if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
844 TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
847 // Incorporate types by name, scanning all the types in the source module.
848 // At this point, the destination module may have a type "%foo = { i32 }" for
849 // example. When the source module got loaded into the same LLVMContext, if
850 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
851 std::vector<StructType *> Types = SrcM->getIdentifiedStructTypes();
852 for (StructType *ST : Types) {
856 // Check to see if there is a dot in the name followed by a digit.
857 size_t DotPos = ST->getName().rfind('.');
858 if (DotPos == 0 || DotPos == StringRef::npos ||
859 ST->getName().back() == '.' ||
860 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos + 1])))
863 // Check to see if the destination module has a struct with the prefix name.
864 StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos));
868 // Don't use it if this actually came from the source module. They're in
869 // the same LLVMContext after all. Also don't use it unless the type is
870 // actually used in the destination module. This can happen in situations
875 // %Z = type { %A } %B = type { %C.1 }
876 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
877 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
878 // %C = type { i8* } %B.3 = type { %C.1 }
880 // When we link Module B with Module A, the '%B' in Module B is
881 // used. However, that would then use '%C.1'. But when we process '%C.1',
882 // we prefer to take the '%C' version. So we are then left with both
883 // '%C.1' and '%C' being used for the same types. This leads to some
884 // variables using one type and some using the other.
885 if (TypeMap.DstStructTypesSet.hasType(DST))
886 TypeMap.addTypeMapping(DST, ST);
889 // Now that we have discovered all of the type equivalences, get a body for
890 // any 'opaque' types in the dest module that are now resolved.
891 TypeMap.linkDefinedTypeBodies();
894 static void upgradeGlobalArray(GlobalVariable *GV) {
895 ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
896 StructType *OldTy = cast<StructType>(ATy->getElementType());
897 assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
899 // Get the upgraded 3 element type.
900 PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
901 Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
903 StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
905 // Build new constants with a null third field filled in.
906 Constant *OldInitC = GV->getInitializer();
907 ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
908 if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
909 // Invalid initializer; give up.
911 std::vector<Constant *> Initializers;
912 if (OldInit && OldInit->getNumOperands()) {
913 Value *Null = Constant::getNullValue(VoidPtrTy);
914 for (Use &U : OldInit->operands()) {
915 ConstantStruct *Init = cast<ConstantStruct>(U.get());
916 Initializers.push_back(ConstantStruct::get(
917 NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
920 assert(Initializers.size() == ATy->getNumElements() &&
921 "Failed to copy all array elements");
923 // Replace the old GV with a new one.
924 ATy = ArrayType::get(NewTy, Initializers.size());
925 Constant *NewInit = ConstantArray::get(ATy, Initializers);
926 GlobalVariable *NewGV = new GlobalVariable(
927 *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
928 GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
929 GV->isExternallyInitialized());
930 NewGV->copyAttributesFrom(GV);
932 assert(GV->use_empty() && "program cannot use initializer list");
933 GV->eraseFromParent();
936 void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
937 // Look for the global arrays.
938 auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM->getNamedValue(Name));
941 auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM->getNamedValue(Name));
945 // Check if the types already match.
946 auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
948 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
952 // Grab the element types. We can only upgrade an array of a two-field
953 // struct. Only bother if the other one has three-fields.
954 auto *DstEltTy = cast<StructType>(DstTy->getElementType());
955 auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
956 if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
957 upgradeGlobalArray(DstGV);
960 if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
961 upgradeGlobalArray(SrcGV);
963 // We can't upgrade any other differences.
966 void ModuleLinker::upgradeMismatchedGlobals() {
967 upgradeMismatchedGlobalArray("llvm.global_ctors");
968 upgradeMismatchedGlobalArray("llvm.global_dtors");
971 /// If there were any appending global variables, link them together now.
972 /// Return true on error.
973 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
974 const GlobalVariable *SrcGV) {
976 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
977 return emitError("Linking globals named '" + SrcGV->getName() +
978 "': can only link appending global with another appending global!");
980 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
982 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
983 Type *EltTy = DstTy->getElementType();
985 // Check to see that they two arrays agree on type.
986 if (EltTy != SrcTy->getElementType())
987 return emitError("Appending variables with different element types!");
988 if (DstGV->isConstant() != SrcGV->isConstant())
989 return emitError("Appending variables linked with different const'ness!");
991 if (DstGV->getAlignment() != SrcGV->getAlignment())
993 "Appending variables with different alignment need to be linked!");
995 if (DstGV->getVisibility() != SrcGV->getVisibility())
997 "Appending variables with different visibility need to be linked!");
999 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
1001 "Appending variables with different unnamed_addr need to be linked!");
1003 if (StringRef(DstGV->getSection()) != SrcGV->getSection())
1005 "Appending variables with different section name need to be linked!");
1007 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements();
1008 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
1010 // Create the new global variable.
1011 GlobalVariable *NG =
1012 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(),
1013 DstGV->getLinkage(), /*init*/nullptr, /*name*/"", DstGV,
1014 DstGV->getThreadLocalMode(),
1015 DstGV->getType()->getAddressSpace());
1017 // Propagate alignment, visibility and section info.
1018 copyGVAttributes(NG, DstGV);
1020 AppendingVarInfo AVI;
1022 AVI.DstInit = DstGV->getInitializer();
1023 AVI.SrcInit = SrcGV->getInitializer();
1024 AppendingVars.push_back(AVI);
1026 // Replace any uses of the two global variables with uses of the new
1028 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
1030 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
1031 DstGV->eraseFromParent();
1033 // Track the source variable so we don't try to link it.
1034 DoNotLinkFromSource.insert(SrcGV);
1039 bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) {
1040 GlobalValue *DGV = getLinkedToGlobal(SGV);
1042 // Handle the ultra special appending linkage case first.
1043 if (DGV && DGV->hasAppendingLinkage())
1044 return linkAppendingVarProto(cast<GlobalVariable>(DGV),
1045 cast<GlobalVariable>(SGV));
1047 bool LinkFromSrc = true;
1048 Comdat *C = nullptr;
1049 GlobalValue::VisibilityTypes Visibility = SGV->getVisibility();
1050 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
1052 if (const Comdat *SC = SGV->getComdat()) {
1053 Comdat::SelectionKind SK;
1054 std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
1055 C = DstM->getOrInsertComdat(SC->getName());
1056 C->setSelectionKind(SK);
1058 if (shouldLinkFromSource(LinkFromSrc, *DGV, *SGV))
1063 // Track the source global so that we don't attempt to copy it over when
1064 // processing global initializers.
1065 DoNotLinkFromSource.insert(SGV);
1068 // Make sure to remember this mapping.
1070 ConstantExpr::getBitCast(DGV, TypeMap.get(SGV->getType()));
1074 Visibility = isLessConstraining(Visibility, DGV->getVisibility())
1075 ? DGV->getVisibility()
1077 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
1080 if (!LinkFromSrc && !DGV)
1087 // If the GV is to be lazily linked, don't create it just yet.
1088 // The ValueMaterializerTy will deal with creating it if it's used.
1089 if (!DGV && !shouldOverrideFromSrc() &&
1090 (SGV->hasLocalLinkage() || SGV->hasLinkOnceLinkage() ||
1091 SGV->hasAvailableExternallyLinkage())) {
1092 DoNotLinkFromSource.insert(SGV);
1096 // When we only want to link in unresolved dependencies, blacklist
1097 // the symbol unless unless DestM has a matching declaration (DGV).
1098 if (shouldLinkOnlyNeeded() && !(DGV && DGV->isDeclaration())) {
1099 DoNotLinkFromSource.insert(SGV);
1103 NewGV = copyGlobalValueProto(TypeMap, *DstM, SGV);
1105 if (DGV && isa<Function>(DGV))
1106 if (auto *NewF = dyn_cast<Function>(NewGV))
1107 OverridingFunctions.insert(NewF);
1110 NewGV->setUnnamedAddr(HasUnnamedAddr);
1111 NewGV->setVisibility(Visibility);
1113 if (auto *NewGO = dyn_cast<GlobalObject>(NewGV)) {
1115 NewGO->setComdat(C);
1117 if (DGV && DGV->hasCommonLinkage() && SGV->hasCommonLinkage())
1118 NewGO->setAlignment(std::max(DGV->getAlignment(), SGV->getAlignment()));
1121 if (auto *NewGVar = dyn_cast<GlobalVariable>(NewGV)) {
1122 auto *DGVar = dyn_cast_or_null<GlobalVariable>(DGV);
1123 auto *SGVar = dyn_cast<GlobalVariable>(SGV);
1124 if (DGVar && SGVar && DGVar->isDeclaration() && SGVar->isDeclaration() &&
1125 (!DGVar->isConstant() || !SGVar->isConstant()))
1126 NewGVar->setConstant(false);
1129 // Make sure to remember this mapping.
1132 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewGV, DGV->getType()));
1133 DGV->eraseFromParent();
1135 ValueMap[SGV] = NewGV;
1141 static void getArrayElements(const Constant *C,
1142 SmallVectorImpl<Constant *> &Dest) {
1143 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
1145 for (unsigned i = 0; i != NumElements; ++i)
1146 Dest.push_back(C->getAggregateElement(i));
1149 void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) {
1150 // Merge the initializer.
1151 SmallVector<Constant *, 16> DstElements;
1152 getArrayElements(AVI.DstInit, DstElements);
1154 SmallVector<Constant *, 16> SrcElements;
1155 getArrayElements(AVI.SrcInit, SrcElements);
1157 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
1159 StringRef Name = AVI.NewGV->getName();
1160 bool IsNewStructor =
1161 (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
1162 cast<StructType>(NewType->getElementType())->getNumElements() == 3;
1164 for (auto *V : SrcElements) {
1165 if (IsNewStructor) {
1166 Constant *Key = V->getAggregateElement(2);
1167 if (DoNotLinkFromSource.count(Key))
1170 DstElements.push_back(
1171 MapValue(V, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1173 if (IsNewStructor) {
1174 NewType = ArrayType::get(NewType->getElementType(), DstElements.size());
1175 AVI.NewGV->mutateType(PointerType::get(NewType, 0));
1178 AVI.NewGV->setInitializer(ConstantArray::get(NewType, DstElements));
1181 /// Update the initializers in the Dest module now that all globals that may be
1182 /// referenced are in Dest.
1183 void ModuleLinker::linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src) {
1184 // Figure out what the initializer looks like in the dest module.
1185 Dst.setInitializer(MapValue(Src.getInitializer(), ValueMap,
1186 RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1189 /// Copy the source function over into the dest function and fix up references
1190 /// to values. At this point we know that Dest is an external function, and
1191 /// that Src is not.
1192 bool ModuleLinker::linkFunctionBody(Function &Dst, Function &Src) {
1193 assert(Dst.isDeclaration() && !Src.isDeclaration());
1195 // Materialize if needed.
1196 if (std::error_code EC = Src.materialize())
1197 return emitError(EC.message());
1199 // Link in the prefix data.
1200 if (Src.hasPrefixData())
1201 Dst.setPrefixData(MapValue(Src.getPrefixData(), ValueMap,
1202 RF_MoveDistinctMDs, &TypeMap, &ValMaterializer));
1204 // Link in the prologue data.
1205 if (Src.hasPrologueData())
1206 Dst.setPrologueData(MapValue(Src.getPrologueData(), ValueMap,
1207 RF_MoveDistinctMDs, &TypeMap,
1210 // Link in the personality function.
1211 if (Src.hasPersonalityFn())
1212 Dst.setPersonalityFn(MapValue(Src.getPersonalityFn(), ValueMap,
1213 RF_MoveDistinctMDs, &TypeMap,
1216 // Go through and convert function arguments over, remembering the mapping.
1217 Function::arg_iterator DI = Dst.arg_begin();
1218 for (Argument &Arg : Src.args()) {
1219 DI->setName(Arg.getName()); // Copy the name over.
1221 // Add a mapping to our mapping.
1222 ValueMap[&Arg] = DI;
1226 // Copy over the metadata attachments.
1227 SmallVector<std::pair<unsigned, MDNode *>, 8> MDs;
1228 Src.getAllMetadata(MDs);
1229 for (const auto &I : MDs)
1230 Dst.setMetadata(I.first, MapMetadata(I.second, ValueMap, RF_MoveDistinctMDs,
1231 &TypeMap, &ValMaterializer));
1233 // Splice the body of the source function into the dest function.
1234 Dst.getBasicBlockList().splice(Dst.end(), Src.getBasicBlockList());
1236 // At this point, all of the instructions and values of the function are now
1237 // copied over. The only problem is that they are still referencing values in
1238 // the Source function as operands. Loop through all of the operands of the
1239 // functions and patch them up to point to the local versions.
1240 for (BasicBlock &BB : Dst)
1241 for (Instruction &I : BB)
1242 RemapInstruction(&I, ValueMap,
1243 RF_IgnoreMissingEntries | RF_MoveDistinctMDs, &TypeMap,
1246 // There is no need to map the arguments anymore.
1247 for (Argument &Arg : Src.args())
1248 ValueMap.erase(&Arg);
1250 Src.dematerialize();
1254 void ModuleLinker::linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src) {
1255 Constant *Aliasee = Src.getAliasee();
1256 Constant *Val = MapValue(Aliasee, ValueMap, RF_MoveDistinctMDs, &TypeMap,
1258 Dst.setAliasee(Val);
1261 bool ModuleLinker::linkGlobalValueBody(GlobalValue &Src) {
1262 Value *Dst = ValueMap[&Src];
1264 if (shouldInternalizeLinkedSymbols())
1265 if (auto *DGV = dyn_cast<GlobalValue>(Dst))
1266 DGV->setLinkage(GlobalValue::InternalLinkage);
1267 if (auto *F = dyn_cast<Function>(&Src))
1268 return linkFunctionBody(cast<Function>(*Dst), *F);
1269 if (auto *GVar = dyn_cast<GlobalVariable>(&Src)) {
1270 linkGlobalInit(cast<GlobalVariable>(*Dst), *GVar);
1273 linkAliasBody(cast<GlobalAlias>(*Dst), cast<GlobalAlias>(Src));
1277 /// Insert all of the named MDNodes in Src into the Dest module.
1278 void ModuleLinker::linkNamedMDNodes() {
1279 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1280 for (const NamedMDNode &NMD : SrcM->named_metadata()) {
1281 // Don't link module flags here. Do them separately.
1282 if (&NMD == SrcModFlags)
1284 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(NMD.getName());
1285 // Add Src elements into Dest node.
1286 for (const MDNode *op : NMD.operands())
1287 DestNMD->addOperand(MapMetadata(op, ValueMap, RF_MoveDistinctMDs,
1288 &TypeMap, &ValMaterializer));
1292 /// Drop DISubprograms that have been superseded.
1294 /// FIXME: this creates an asymmetric result: we strip functions from losing
1295 /// subprograms in DstM, but leave losing subprograms in SrcM.
1296 /// TODO: Remove this logic once the backend can correctly determine canonical
1298 void ModuleLinker::stripReplacedSubprograms() {
1299 // Avoid quadratic runtime by returning early when there's nothing to do.
1300 if (OverridingFunctions.empty())
1303 // Move the functions now, so the set gets cleared even on early returns.
1304 auto Functions = std::move(OverridingFunctions);
1305 OverridingFunctions.clear();
1307 // Drop functions from subprograms if they've been overridden by the new
1309 NamedMDNode *CompileUnits = DstM->getNamedMetadata("llvm.dbg.cu");
1312 for (unsigned I = 0, E = CompileUnits->getNumOperands(); I != E; ++I) {
1313 auto *CU = cast<DICompileUnit>(CompileUnits->getOperand(I));
1314 assert(CU && "Expected valid compile unit");
1316 for (DISubprogram *SP : CU->getSubprograms()) {
1317 if (!SP || !SP->getFunction() || !Functions.count(SP->getFunction()))
1320 // Prevent DebugInfoFinder from tagging this as the canonical subprogram,
1321 // since the canonical one is in the incoming module.
1322 SP->replaceFunction(nullptr);
1327 /// Merge the linker flags in Src into the Dest module.
1328 bool ModuleLinker::linkModuleFlagsMetadata() {
1329 // If the source module has no module flags, we are done.
1330 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1331 if (!SrcModFlags) return false;
1333 // If the destination module doesn't have module flags yet, then just copy
1334 // over the source module's flags.
1335 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
1336 if (DstModFlags->getNumOperands() == 0) {
1337 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1338 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1343 // First build a map of the existing module flags and requirements.
1344 DenseMap<MDString *, std::pair<MDNode *, unsigned>> Flags;
1345 SmallSetVector<MDNode*, 16> Requirements;
1346 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1347 MDNode *Op = DstModFlags->getOperand(I);
1348 ConstantInt *Behavior = mdconst::extract<ConstantInt>(Op->getOperand(0));
1349 MDString *ID = cast<MDString>(Op->getOperand(1));
1351 if (Behavior->getZExtValue() == Module::Require) {
1352 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1354 Flags[ID] = std::make_pair(Op, I);
1358 // Merge in the flags from the source module, and also collect its set of
1360 bool HasErr = false;
1361 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1362 MDNode *SrcOp = SrcModFlags->getOperand(I);
1363 ConstantInt *SrcBehavior =
1364 mdconst::extract<ConstantInt>(SrcOp->getOperand(0));
1365 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1368 std::tie(DstOp, DstIndex) = Flags.lookup(ID);
1369 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1371 // If this is a requirement, add it and continue.
1372 if (SrcBehaviorValue == Module::Require) {
1373 // If the destination module does not already have this requirement, add
1375 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1376 DstModFlags->addOperand(SrcOp);
1381 // If there is no existing flag with this ID, just add it.
1383 Flags[ID] = std::make_pair(SrcOp, DstModFlags->getNumOperands());
1384 DstModFlags->addOperand(SrcOp);
1388 // Otherwise, perform a merge.
1389 ConstantInt *DstBehavior =
1390 mdconst::extract<ConstantInt>(DstOp->getOperand(0));
1391 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1393 // If either flag has override behavior, handle it first.
1394 if (DstBehaviorValue == Module::Override) {
1395 // Diagnose inconsistent flags which both have override behavior.
1396 if (SrcBehaviorValue == Module::Override &&
1397 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1398 HasErr |= emitError("linking module flags '" + ID->getString() +
1399 "': IDs have conflicting override values");
1402 } else if (SrcBehaviorValue == Module::Override) {
1403 // Update the destination flag to that of the source.
1404 DstModFlags->setOperand(DstIndex, SrcOp);
1405 Flags[ID].first = SrcOp;
1409 // Diagnose inconsistent merge behavior types.
1410 if (SrcBehaviorValue != DstBehaviorValue) {
1411 HasErr |= emitError("linking module flags '" + ID->getString() +
1412 "': IDs have conflicting behaviors");
1416 auto replaceDstValue = [&](MDNode *New) {
1417 Metadata *FlagOps[] = {DstOp->getOperand(0), ID, New};
1418 MDNode *Flag = MDNode::get(DstM->getContext(), FlagOps);
1419 DstModFlags->setOperand(DstIndex, Flag);
1420 Flags[ID].first = Flag;
1423 // Perform the merge for standard behavior types.
1424 switch (SrcBehaviorValue) {
1425 case Module::Require:
1426 case Module::Override: llvm_unreachable("not possible");
1427 case Module::Error: {
1428 // Emit an error if the values differ.
1429 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1430 HasErr |= emitError("linking module flags '" + ID->getString() +
1431 "': IDs have conflicting values");
1435 case Module::Warning: {
1436 // Emit a warning if the values differ.
1437 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1438 emitWarning("linking module flags '" + ID->getString() +
1439 "': IDs have conflicting values");
1443 case Module::Append: {
1444 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1445 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1446 SmallVector<Metadata *, 8> MDs;
1447 MDs.reserve(DstValue->getNumOperands() + SrcValue->getNumOperands());
1448 MDs.append(DstValue->op_begin(), DstValue->op_end());
1449 MDs.append(SrcValue->op_begin(), SrcValue->op_end());
1451 replaceDstValue(MDNode::get(DstM->getContext(), MDs));
1454 case Module::AppendUnique: {
1455 SmallSetVector<Metadata *, 16> Elts;
1456 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1457 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1458 Elts.insert(DstValue->op_begin(), DstValue->op_end());
1459 Elts.insert(SrcValue->op_begin(), SrcValue->op_end());
1461 replaceDstValue(MDNode::get(DstM->getContext(),
1462 makeArrayRef(Elts.begin(), Elts.end())));
1468 // Check all of the requirements.
1469 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1470 MDNode *Requirement = Requirements[I];
1471 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1472 Metadata *ReqValue = Requirement->getOperand(1);
1474 MDNode *Op = Flags[Flag].first;
1475 if (!Op || Op->getOperand(2) != ReqValue) {
1476 HasErr |= emitError("linking module flags '" + Flag->getString() +
1477 "': does not have the required value");
1485 // This function returns true if the triples match.
1486 static bool triplesMatch(const Triple &T0, const Triple &T1) {
1487 // If vendor is apple, ignore the version number.
1488 if (T0.getVendor() == Triple::Apple)
1489 return T0.getArch() == T1.getArch() &&
1490 T0.getSubArch() == T1.getSubArch() &&
1491 T0.getVendor() == T1.getVendor() &&
1492 T0.getOS() == T1.getOS();
1497 // This function returns the merged triple.
1498 static std::string mergeTriples(const Triple &SrcTriple, const Triple &DstTriple) {
1499 // If vendor is apple, pick the triple with the larger version number.
1500 if (SrcTriple.getVendor() == Triple::Apple)
1501 if (DstTriple.isOSVersionLT(SrcTriple))
1502 return SrcTriple.str();
1504 return DstTriple.str();
1507 bool ModuleLinker::run() {
1508 assert(DstM && "Null destination module");
1509 assert(SrcM && "Null source module");
1511 // Inherit the target data from the source module if the destination module
1512 // doesn't have one already.
1513 if (DstM->getDataLayout().isDefault())
1514 DstM->setDataLayout(SrcM->getDataLayout());
1516 if (SrcM->getDataLayout() != DstM->getDataLayout()) {
1517 emitWarning("Linking two modules of different data layouts: '" +
1518 SrcM->getModuleIdentifier() + "' is '" +
1519 SrcM->getDataLayoutStr() + "' whereas '" +
1520 DstM->getModuleIdentifier() + "' is '" +
1521 DstM->getDataLayoutStr() + "'\n");
1524 // Copy the target triple from the source to dest if the dest's is empty.
1525 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
1526 DstM->setTargetTriple(SrcM->getTargetTriple());
1528 Triple SrcTriple(SrcM->getTargetTriple()), DstTriple(DstM->getTargetTriple());
1530 if (!SrcM->getTargetTriple().empty() && !triplesMatch(SrcTriple, DstTriple))
1531 emitWarning("Linking two modules of different target triples: " +
1532 SrcM->getModuleIdentifier() + "' is '" +
1533 SrcM->getTargetTriple() + "' whereas '" +
1534 DstM->getModuleIdentifier() + "' is '" +
1535 DstM->getTargetTriple() + "'\n");
1537 DstM->setTargetTriple(mergeTriples(SrcTriple, DstTriple));
1539 // Append the module inline asm string.
1540 if (!SrcM->getModuleInlineAsm().empty()) {
1541 if (DstM->getModuleInlineAsm().empty())
1542 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
1544 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
1545 SrcM->getModuleInlineAsm());
1548 // Loop over all of the linked values to compute type mappings.
1549 computeTypeMapping();
1551 ComdatsChosen.clear();
1552 for (const auto &SMEC : SrcM->getComdatSymbolTable()) {
1553 const Comdat &C = SMEC.getValue();
1554 if (ComdatsChosen.count(&C))
1556 Comdat::SelectionKind SK;
1558 if (getComdatResult(&C, SK, LinkFromSrc))
1560 ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
1563 // Upgrade mismatched global arrays.
1564 upgradeMismatchedGlobals();
1566 // Insert all of the globals in src into the DstM module... without linking
1567 // initializers (which could refer to functions not yet mapped over).
1568 for (GlobalVariable &GV : SrcM->globals())
1569 if (linkGlobalValueProto(&GV))
1572 // Link the functions together between the two modules, without doing function
1573 // bodies... this just adds external function prototypes to the DstM
1574 // function... We do this so that when we begin processing function bodies,
1575 // all of the global values that may be referenced are available in our
1577 for (Function &F :*SrcM)
1578 if (linkGlobalValueProto(&F))
1581 // If there were any aliases, link them now.
1582 for (GlobalAlias &GA : SrcM->aliases())
1583 if (linkGlobalValueProto(&GA))
1586 for (const AppendingVarInfo &AppendingVar : AppendingVars)
1587 linkAppendingVarInit(AppendingVar);
1589 for (const auto &Entry : DstM->getComdatSymbolTable()) {
1590 const Comdat &C = Entry.getValue();
1591 if (C.getSelectionKind() == Comdat::Any)
1593 const GlobalValue *GV = SrcM->getNamedValue(C.getName());
1595 MapValue(GV, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer);
1598 // Strip replaced subprograms before mapping any metadata -- so that we're
1599 // not changing metadata from the source module (note that
1600 // linkGlobalValueBody() eventually calls RemapInstruction() and therefore
1601 // MapMetadata()) -- but after linking global value protocols -- so that
1602 // OverridingFunctions has been built.
1603 stripReplacedSubprograms();
1605 // Link in the function bodies that are defined in the source module into
1607 for (Function &SF : *SrcM) {
1608 // Skip if no body (function is external).
1609 if (SF.isDeclaration())
1612 // Skip if not linking from source.
1613 if (DoNotLinkFromSource.count(&SF))
1616 if (linkGlobalValueBody(SF))
1620 // Resolve all uses of aliases with aliasees.
1621 for (GlobalAlias &Src : SrcM->aliases()) {
1622 if (DoNotLinkFromSource.count(&Src))
1624 linkGlobalValueBody(Src);
1627 // Remap all of the named MDNodes in Src into the DstM module. We do this
1628 // after linking GlobalValues so that MDNodes that reference GlobalValues
1629 // are properly remapped.
1632 // Merge the module flags into the DstM module.
1633 if (linkModuleFlagsMetadata())
1636 // Update the initializers in the DstM module now that all globals that may
1637 // be referenced are in DstM.
1638 for (GlobalVariable &Src : SrcM->globals()) {
1639 // Only process initialized GV's or ones not already in dest.
1640 if (!Src.hasInitializer() || DoNotLinkFromSource.count(&Src))
1642 linkGlobalValueBody(Src);
1645 // Process vector of lazily linked in functions.
1646 while (!LazilyLinkGlobalValues.empty()) {
1647 GlobalValue *SGV = LazilyLinkGlobalValues.back();
1648 LazilyLinkGlobalValues.pop_back();
1650 // Skip declarations that ValueMaterializer may have created in
1651 // case we link in only some of SrcM.
1652 if (shouldLinkOnlyNeeded() && SGV->isDeclaration())
1655 assert(!SGV->isDeclaration() && "users should not pass down decls");
1656 if (linkGlobalValueBody(*SGV))
1663 Linker::StructTypeKeyInfo::KeyTy::KeyTy(ArrayRef<Type *> E, bool P)
1664 : ETypes(E), IsPacked(P) {}
1666 Linker::StructTypeKeyInfo::KeyTy::KeyTy(const StructType *ST)
1667 : ETypes(ST->elements()), IsPacked(ST->isPacked()) {}
1669 bool Linker::StructTypeKeyInfo::KeyTy::operator==(const KeyTy &That) const {
1670 if (IsPacked != That.IsPacked)
1672 if (ETypes != That.ETypes)
1677 bool Linker::StructTypeKeyInfo::KeyTy::operator!=(const KeyTy &That) const {
1678 return !this->operator==(That);
1681 StructType *Linker::StructTypeKeyInfo::getEmptyKey() {
1682 return DenseMapInfo<StructType *>::getEmptyKey();
1685 StructType *Linker::StructTypeKeyInfo::getTombstoneKey() {
1686 return DenseMapInfo<StructType *>::getTombstoneKey();
1689 unsigned Linker::StructTypeKeyInfo::getHashValue(const KeyTy &Key) {
1690 return hash_combine(hash_combine_range(Key.ETypes.begin(), Key.ETypes.end()),
1694 unsigned Linker::StructTypeKeyInfo::getHashValue(const StructType *ST) {
1695 return getHashValue(KeyTy(ST));
1698 bool Linker::StructTypeKeyInfo::isEqual(const KeyTy &LHS,
1699 const StructType *RHS) {
1700 if (RHS == getEmptyKey() || RHS == getTombstoneKey())
1702 return LHS == KeyTy(RHS);
1705 bool Linker::StructTypeKeyInfo::isEqual(const StructType *LHS,
1706 const StructType *RHS) {
1707 if (RHS == getEmptyKey())
1708 return LHS == getEmptyKey();
1710 if (RHS == getTombstoneKey())
1711 return LHS == getTombstoneKey();
1713 return KeyTy(LHS) == KeyTy(RHS);
1716 void Linker::IdentifiedStructTypeSet::addNonOpaque(StructType *Ty) {
1717 assert(!Ty->isOpaque());
1718 NonOpaqueStructTypes.insert(Ty);
1721 void Linker::IdentifiedStructTypeSet::switchToNonOpaque(StructType *Ty) {
1722 assert(!Ty->isOpaque());
1723 NonOpaqueStructTypes.insert(Ty);
1724 bool Removed = OpaqueStructTypes.erase(Ty);
1729 void Linker::IdentifiedStructTypeSet::addOpaque(StructType *Ty) {
1730 assert(Ty->isOpaque());
1731 OpaqueStructTypes.insert(Ty);
1735 Linker::IdentifiedStructTypeSet::findNonOpaque(ArrayRef<Type *> ETypes,
1737 Linker::StructTypeKeyInfo::KeyTy Key(ETypes, IsPacked);
1738 auto I = NonOpaqueStructTypes.find_as(Key);
1739 if (I == NonOpaqueStructTypes.end())
1744 bool Linker::IdentifiedStructTypeSet::hasType(StructType *Ty) {
1746 return OpaqueStructTypes.count(Ty);
1747 auto I = NonOpaqueStructTypes.find(Ty);
1748 if (I == NonOpaqueStructTypes.end())
1753 void Linker::init(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
1754 this->Composite = M;
1755 this->DiagnosticHandler = DiagnosticHandler;
1757 TypeFinder StructTypes;
1758 StructTypes.run(*M, true);
1759 for (StructType *Ty : StructTypes) {
1761 IdentifiedStructTypes.addOpaque(Ty);
1763 IdentifiedStructTypes.addNonOpaque(Ty);
1767 Linker::Linker(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
1768 init(M, DiagnosticHandler);
1771 Linker::Linker(Module *M) {
1772 init(M, [this](const DiagnosticInfo &DI) {
1773 Composite->getContext().diagnose(DI);
1777 void Linker::deleteModule() {
1779 Composite = nullptr;
1782 bool Linker::linkInModule(Module *Src, unsigned Flags) {
1783 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,
1784 DiagnosticHandler, Flags);
1785 bool RetCode = TheLinker.run();
1786 Composite->dropTriviallyDeadConstantArrays();
1790 void Linker::setModule(Module *Dst) {
1791 init(Dst, DiagnosticHandler);
1794 //===----------------------------------------------------------------------===//
1795 // LinkModules entrypoint.
1796 //===----------------------------------------------------------------------===//
1798 /// This function links two modules together, with the resulting Dest module
1799 /// modified to be the composite of the two input modules. If an error occurs,
1800 /// true is returned and ErrorMsg (if not null) is set to indicate the problem.
1801 /// Upon failure, the Dest module could be in a modified state, and shouldn't be
1802 /// relied on to be consistent.
1803 bool Linker::LinkModules(Module *Dest, Module *Src,
1804 DiagnosticHandlerFunction DiagnosticHandler,
1806 Linker L(Dest, DiagnosticHandler);
1807 return L.linkInModule(Src, Flags);
1810 bool Linker::LinkModules(Module *Dest, Module *Src, unsigned Flags) {
1812 return L.linkInModule(Src, Flags);
1815 //===----------------------------------------------------------------------===//
1817 //===----------------------------------------------------------------------===//
1819 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
1820 LLVMLinkerMode Unused, char **OutMessages) {
1821 Module *D = unwrap(Dest);
1822 std::string Message;
1823 raw_string_ostream Stream(Message);
1824 DiagnosticPrinterRawOStream DP(Stream);
1826 LLVMBool Result = Linker::LinkModules(
1827 D, unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); });
1829 if (OutMessages && Result) {
1831 *OutMessages = strdup(Message.c_str());