1 //===- lib/Linker/LinkModules.cpp - Module Linker Implementation ----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the LLVM module linker.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Linker/Linker.h"
15 #include "llvm-c/Linker.h"
16 #include "llvm/ADT/Optional.h"
17 #include "llvm/ADT/SetVector.h"
18 #include "llvm/ADT/SmallString.h"
19 #include "llvm/IR/Constants.h"
20 #include "llvm/IR/Module.h"
21 #include "llvm/IR/TypeFinder.h"
22 #include "llvm/Support/CommandLine.h"
23 #include "llvm/Support/Debug.h"
24 #include "llvm/Support/raw_ostream.h"
25 #include "llvm/Transforms/Utils/Cloning.h"
30 //===----------------------------------------------------------------------===//
31 // TypeMap implementation.
32 //===----------------------------------------------------------------------===//
35 typedef SmallPtrSet<StructType*, 32> TypeSet;
37 class TypeMapTy : public ValueMapTypeRemapper {
38 /// MappedTypes - This is a mapping from a source type to a destination type
40 DenseMap<Type*, Type*> MappedTypes;
42 /// SpeculativeTypes - When checking to see if two subgraphs are isomorphic,
43 /// we speculatively add types to MappedTypes, but keep track of them here in
44 /// case we need to roll back.
45 SmallVector<Type*, 16> SpeculativeTypes;
47 /// SrcDefinitionsToResolve - This is a list of non-opaque structs in the
48 /// source module that are mapped to an opaque struct in the destination
50 SmallVector<StructType*, 16> SrcDefinitionsToResolve;
52 /// DstResolvedOpaqueTypes - This is the set of opaque types in the
53 /// destination modules who are getting a body from the source module.
54 SmallPtrSet<StructType*, 16> DstResolvedOpaqueTypes;
57 TypeMapTy(TypeSet &Set) : DstStructTypesSet(Set) {}
59 TypeSet &DstStructTypesSet;
60 /// addTypeMapping - Indicate that the specified type in the destination
61 /// module is conceptually equivalent to the specified type in the source
63 void addTypeMapping(Type *DstTy, Type *SrcTy);
65 /// linkDefinedTypeBodies - Produce a body for an opaque type in the dest
66 /// module from a type definition in the source module.
67 void linkDefinedTypeBodies();
69 /// get - Return the mapped type to use for the specified input type from the
71 Type *get(Type *SrcTy);
73 FunctionType *get(FunctionType *T) {return cast<FunctionType>(get((Type*)T));}
75 /// dump - Dump out the type map for debugging purposes.
77 for (DenseMap<Type*, Type*>::const_iterator
78 I = MappedTypes.begin(), E = MappedTypes.end(); I != E; ++I) {
79 dbgs() << "TypeMap: ";
88 Type *getImpl(Type *T);
89 /// remapType - Implement the ValueMapTypeRemapper interface.
90 Type *remapType(Type *SrcTy) override {
94 bool areTypesIsomorphic(Type *DstTy, Type *SrcTy);
98 void TypeMapTy::addTypeMapping(Type *DstTy, Type *SrcTy) {
99 Type *&Entry = MappedTypes[SrcTy];
102 if (DstTy == SrcTy) {
107 // Check to see if these types are recursively isomorphic and establish a
108 // mapping between them if so.
109 if (!areTypesIsomorphic(DstTy, SrcTy)) {
110 // Oops, they aren't isomorphic. Just discard this request by rolling out
111 // any speculative mappings we've established.
112 for (unsigned i = 0, e = SpeculativeTypes.size(); i != e; ++i)
113 MappedTypes.erase(SpeculativeTypes[i]);
115 SpeculativeTypes.clear();
118 /// areTypesIsomorphic - Recursively walk this pair of types, returning true
119 /// if they are isomorphic, false if they are not.
120 bool TypeMapTy::areTypesIsomorphic(Type *DstTy, Type *SrcTy) {
121 // Two types with differing kinds are clearly not isomorphic.
122 if (DstTy->getTypeID() != SrcTy->getTypeID()) return false;
124 // If we have an entry in the MappedTypes table, then we have our answer.
125 Type *&Entry = MappedTypes[SrcTy];
127 return Entry == DstTy;
129 // Two identical types are clearly isomorphic. Remember this
130 // non-speculatively.
131 if (DstTy == SrcTy) {
136 // Okay, we have two types with identical kinds that we haven't seen before.
138 // If this is an opaque struct type, special case it.
139 if (StructType *SSTy = dyn_cast<StructType>(SrcTy)) {
140 // Mapping an opaque type to any struct, just keep the dest struct.
141 if (SSTy->isOpaque()) {
143 SpeculativeTypes.push_back(SrcTy);
147 // Mapping a non-opaque source type to an opaque dest. If this is the first
148 // type that we're mapping onto this destination type then we succeed. Keep
149 // the dest, but fill it in later. This doesn't need to be speculative. If
150 // this is the second (different) type that we're trying to map onto the
151 // same opaque type then we fail.
152 if (cast<StructType>(DstTy)->isOpaque()) {
153 // We can only map one source type onto the opaque destination type.
154 if (!DstResolvedOpaqueTypes.insert(cast<StructType>(DstTy)))
156 SrcDefinitionsToResolve.push_back(SSTy);
162 // If the number of subtypes disagree between the two types, then we fail.
163 if (SrcTy->getNumContainedTypes() != DstTy->getNumContainedTypes())
166 // Fail if any of the extra properties (e.g. array size) of the type disagree.
167 if (isa<IntegerType>(DstTy))
168 return false; // bitwidth disagrees.
169 if (PointerType *PT = dyn_cast<PointerType>(DstTy)) {
170 if (PT->getAddressSpace() != cast<PointerType>(SrcTy)->getAddressSpace())
173 } else if (FunctionType *FT = dyn_cast<FunctionType>(DstTy)) {
174 if (FT->isVarArg() != cast<FunctionType>(SrcTy)->isVarArg())
176 } else if (StructType *DSTy = dyn_cast<StructType>(DstTy)) {
177 StructType *SSTy = cast<StructType>(SrcTy);
178 if (DSTy->isLiteral() != SSTy->isLiteral() ||
179 DSTy->isPacked() != SSTy->isPacked())
181 } else if (ArrayType *DATy = dyn_cast<ArrayType>(DstTy)) {
182 if (DATy->getNumElements() != cast<ArrayType>(SrcTy)->getNumElements())
184 } else if (VectorType *DVTy = dyn_cast<VectorType>(DstTy)) {
185 if (DVTy->getNumElements() != cast<VectorType>(SrcTy)->getNumElements())
189 // Otherwise, we speculate that these two types will line up and recursively
190 // check the subelements.
192 SpeculativeTypes.push_back(SrcTy);
194 for (unsigned i = 0, e = SrcTy->getNumContainedTypes(); i != e; ++i)
195 if (!areTypesIsomorphic(DstTy->getContainedType(i),
196 SrcTy->getContainedType(i)))
199 // If everything seems to have lined up, then everything is great.
203 /// linkDefinedTypeBodies - Produce a body for an opaque type in the dest
204 /// module from a type definition in the source module.
205 void TypeMapTy::linkDefinedTypeBodies() {
206 SmallVector<Type*, 16> Elements;
207 SmallString<16> TmpName;
209 // Note that processing entries in this loop (calling 'get') can add new
210 // entries to the SrcDefinitionsToResolve vector.
211 while (!SrcDefinitionsToResolve.empty()) {
212 StructType *SrcSTy = SrcDefinitionsToResolve.pop_back_val();
213 StructType *DstSTy = cast<StructType>(MappedTypes[SrcSTy]);
215 // TypeMap is a many-to-one mapping, if there were multiple types that
216 // provide a body for DstSTy then previous iterations of this loop may have
217 // already handled it. Just ignore this case.
218 if (!DstSTy->isOpaque()) continue;
219 assert(!SrcSTy->isOpaque() && "Not resolving a definition?");
221 // Map the body of the source type over to a new body for the dest type.
222 Elements.resize(SrcSTy->getNumElements());
223 for (unsigned i = 0, e = Elements.size(); i != e; ++i)
224 Elements[i] = getImpl(SrcSTy->getElementType(i));
226 DstSTy->setBody(Elements, SrcSTy->isPacked());
228 // If DstSTy has no name or has a longer name than STy, then viciously steal
230 if (!SrcSTy->hasName()) continue;
231 StringRef SrcName = SrcSTy->getName();
233 if (!DstSTy->hasName() || DstSTy->getName().size() > SrcName.size()) {
234 TmpName.insert(TmpName.end(), SrcName.begin(), SrcName.end());
236 DstSTy->setName(TmpName.str());
241 DstResolvedOpaqueTypes.clear();
244 /// get - Return the mapped type to use for the specified input type from the
246 Type *TypeMapTy::get(Type *Ty) {
247 Type *Result = getImpl(Ty);
249 // If this caused a reference to any struct type, resolve it before returning.
250 if (!SrcDefinitionsToResolve.empty())
251 linkDefinedTypeBodies();
255 /// getImpl - This is the recursive version of get().
256 Type *TypeMapTy::getImpl(Type *Ty) {
257 // If we already have an entry for this type, return it.
258 Type **Entry = &MappedTypes[Ty];
259 if (*Entry) return *Entry;
261 // If this is not a named struct type, then just map all of the elements and
262 // then rebuild the type from inside out.
263 if (!isa<StructType>(Ty) || cast<StructType>(Ty)->isLiteral()) {
264 // If there are no element types to map, then the type is itself. This is
265 // true for the anonymous {} struct, things like 'float', integers, etc.
266 if (Ty->getNumContainedTypes() == 0)
269 // Remap all of the elements, keeping track of whether any of them change.
270 bool AnyChange = false;
271 SmallVector<Type*, 4> ElementTypes;
272 ElementTypes.resize(Ty->getNumContainedTypes());
273 for (unsigned i = 0, e = Ty->getNumContainedTypes(); i != e; ++i) {
274 ElementTypes[i] = getImpl(Ty->getContainedType(i));
275 AnyChange |= ElementTypes[i] != Ty->getContainedType(i);
278 // If we found our type while recursively processing stuff, just use it.
279 Entry = &MappedTypes[Ty];
280 if (*Entry) return *Entry;
282 // If all of the element types mapped directly over, then the type is usable
287 // Otherwise, rebuild a modified type.
288 switch (Ty->getTypeID()) {
289 default: llvm_unreachable("unknown derived type to remap");
290 case Type::ArrayTyID:
291 return *Entry = ArrayType::get(ElementTypes[0],
292 cast<ArrayType>(Ty)->getNumElements());
293 case Type::VectorTyID:
294 return *Entry = VectorType::get(ElementTypes[0],
295 cast<VectorType>(Ty)->getNumElements());
296 case Type::PointerTyID:
297 return *Entry = PointerType::get(ElementTypes[0],
298 cast<PointerType>(Ty)->getAddressSpace());
299 case Type::FunctionTyID:
300 return *Entry = FunctionType::get(ElementTypes[0],
301 makeArrayRef(ElementTypes).slice(1),
302 cast<FunctionType>(Ty)->isVarArg());
303 case Type::StructTyID:
304 // Note that this is only reached for anonymous structs.
305 return *Entry = StructType::get(Ty->getContext(), ElementTypes,
306 cast<StructType>(Ty)->isPacked());
310 // Otherwise, this is an unmapped named struct. If the struct can be directly
311 // mapped over, just use it as-is. This happens in a case when the linked-in
312 // module has something like:
313 // %T = type {%T*, i32}
314 // @GV = global %T* null
315 // where T does not exist at all in the destination module.
317 // The other case we watch for is when the type is not in the destination
318 // module, but that it has to be rebuilt because it refers to something that
319 // is already mapped. For example, if the destination module has:
321 // and the source module has something like
322 // %A' = type { i32 }
323 // %B = type { %A'* }
324 // @GV = global %B* null
325 // then we want to create a new type: "%B = type { %A*}" and have it take the
326 // pristine "%B" name from the source module.
328 // To determine which case this is, we have to recursively walk the type graph
329 // speculating that we'll be able to reuse it unmodified. Only if this is
330 // safe would we map the entire thing over. Because this is an optimization,
331 // and is not required for the prettiness of the linked module, we just skip
332 // it and always rebuild a type here.
333 StructType *STy = cast<StructType>(Ty);
335 // If the type is opaque, we can just use it directly.
336 if (STy->isOpaque()) {
337 // A named structure type from src module is used. Add it to the Set of
338 // identified structs in the destination module.
339 DstStructTypesSet.insert(STy);
343 // Otherwise we create a new type and resolve its body later. This will be
344 // resolved by the top level of get().
345 SrcDefinitionsToResolve.push_back(STy);
346 StructType *DTy = StructType::create(STy->getContext());
347 // A new identified structure type was created. Add it to the set of
348 // identified structs in the destination module.
349 DstStructTypesSet.insert(DTy);
350 DstResolvedOpaqueTypes.insert(DTy);
354 //===----------------------------------------------------------------------===//
355 // ModuleLinker implementation.
356 //===----------------------------------------------------------------------===//
361 /// ValueMaterializerTy - Creates prototypes for functions that are lazily
362 /// linked on the fly. This speeds up linking for modules with many
363 /// lazily linked functions of which few get used.
364 class ValueMaterializerTy : public ValueMaterializer {
367 std::vector<Function*> &LazilyLinkFunctions;
369 ValueMaterializerTy(TypeMapTy &TypeMap, Module *DstM,
370 std::vector<Function*> &LazilyLinkFunctions) :
371 ValueMaterializer(), TypeMap(TypeMap), DstM(DstM),
372 LazilyLinkFunctions(LazilyLinkFunctions) {
375 Value *materializeValueFor(Value *V) override;
378 /// ModuleLinker - This is an implementation class for the LinkModules
379 /// function, which is the entrypoint for this file.
384 ValueMaterializerTy ValMaterializer;
386 /// ValueMap - Mapping of values from what they used to be in Src, to what
387 /// they are now in DstM. ValueToValueMapTy is a ValueMap, which involves
388 /// some overhead due to the use of Value handles which the Linker doesn't
389 /// actually need, but this allows us to reuse the ValueMapper code.
390 ValueToValueMapTy ValueMap;
392 std::vector<std::pair<GlobalValue *, GlobalAlias *>> ReplaceWithAlias;
394 struct AppendingVarInfo {
395 GlobalVariable *NewGV; // New aggregate global in dest module.
396 Constant *DstInit; // Old initializer from dest module.
397 Constant *SrcInit; // Old initializer from src module.
400 std::vector<AppendingVarInfo> AppendingVars;
402 unsigned Mode; // Mode to treat source module.
404 // Set of items not to link in from source.
405 SmallPtrSet<const Value*, 16> DoNotLinkFromSource;
407 // Vector of functions to lazily link in.
408 std::vector<Function*> LazilyLinkFunctions;
410 bool SuppressWarnings;
413 std::string ErrorMsg;
415 ModuleLinker(Module *dstM, TypeSet &Set, Module *srcM, unsigned mode,
416 bool SuppressWarnings=false)
417 : DstM(dstM), SrcM(srcM), TypeMap(Set),
418 ValMaterializer(TypeMap, DstM, LazilyLinkFunctions), Mode(mode),
419 SuppressWarnings(SuppressWarnings) {}
424 /// emitError - Helper method for setting a message and returning an error
426 bool emitError(const Twine &Message) {
427 ErrorMsg = Message.str();
431 /// getLinkageResult - This analyzes the two global values and determines
432 /// what the result will look like in the destination module.
433 bool getLinkageResult(GlobalValue *Dest, const GlobalValue *Src,
434 GlobalValue::LinkageTypes <,
435 GlobalValue::VisibilityTypes &Vis,
438 /// getLinkedToGlobal - Given a global in the source module, return the
439 /// global in the destination module that is being linked to, if any.
440 GlobalValue *getLinkedToGlobal(GlobalValue *SrcGV) {
441 // If the source has no name it can't link. If it has local linkage,
442 // there is no name match-up going on.
443 if (!SrcGV->hasName() || SrcGV->hasLocalLinkage())
446 // Otherwise see if we have a match in the destination module's symtab.
447 GlobalValue *DGV = DstM->getNamedValue(SrcGV->getName());
448 if (!DGV) return nullptr;
450 // If we found a global with the same name in the dest module, but it has
451 // internal linkage, we are really not doing any linkage here.
452 if (DGV->hasLocalLinkage())
455 // Otherwise, we do in fact link to the destination global.
459 void computeTypeMapping();
461 bool linkAppendingVarProto(GlobalVariable *DstGV, GlobalVariable *SrcGV);
462 bool linkGlobalProto(GlobalVariable *SrcGV);
463 bool linkFunctionProto(Function *SrcF);
464 bool linkAliasProto(GlobalAlias *SrcA);
465 bool linkModuleFlagsMetadata();
467 void linkAppendingVarInit(const AppendingVarInfo &AVI);
468 void linkGlobalInits();
469 void linkFunctionBody(Function *Dst, Function *Src);
470 void linkAliasBodies();
471 void linkNamedMDNodes();
475 /// forceRenaming - The LLVM SymbolTable class autorenames globals that conflict
476 /// in the symbol table. This is good for all clients except for us. Go
477 /// through the trouble to force this back.
478 static void forceRenaming(GlobalValue *GV, StringRef Name) {
479 // If the global doesn't force its name or if it already has the right name,
480 // there is nothing for us to do.
481 if (GV->hasLocalLinkage() || GV->getName() == Name)
484 Module *M = GV->getParent();
486 // If there is a conflict, rename the conflict.
487 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
488 GV->takeName(ConflictGV);
489 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
490 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
492 GV->setName(Name); // Force the name back
496 /// copyGVAttributes - copy additional attributes (those not needed to construct
497 /// a GlobalValue) from the SrcGV to the DestGV.
498 static void copyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) {
499 // Use the maximum alignment, rather than just copying the alignment of SrcGV.
500 auto *DestGO = dyn_cast<GlobalObject>(DestGV);
503 Alignment = std::max(DestGO->getAlignment(), SrcGV->getAlignment());
505 DestGV->copyAttributesFrom(SrcGV);
508 DestGO->setAlignment(Alignment);
510 forceRenaming(DestGV, SrcGV->getName());
513 static bool isLessConstraining(GlobalValue::VisibilityTypes a,
514 GlobalValue::VisibilityTypes b) {
515 if (a == GlobalValue::HiddenVisibility)
517 if (b == GlobalValue::HiddenVisibility)
519 if (a == GlobalValue::ProtectedVisibility)
521 if (b == GlobalValue::ProtectedVisibility)
526 Value *ValueMaterializerTy::materializeValueFor(Value *V) {
527 Function *SF = dyn_cast<Function>(V);
531 Function *DF = Function::Create(TypeMap.get(SF->getFunctionType()),
532 SF->getLinkage(), SF->getName(), DstM);
533 copyGVAttributes(DF, SF);
535 LazilyLinkFunctions.push_back(SF);
540 /// getLinkageResult - This analyzes the two global values and determines what
541 /// the result will look like in the destination module. In particular, it
542 /// computes the resultant linkage type and visibility, computes whether the
543 /// global in the source should be copied over to the destination (replacing
544 /// the existing one), and computes whether this linkage is an error or not.
545 bool ModuleLinker::getLinkageResult(GlobalValue *Dest, const GlobalValue *Src,
546 GlobalValue::LinkageTypes <,
547 GlobalValue::VisibilityTypes &Vis,
549 assert(Dest && "Must have two globals being queried");
550 assert(!Src->hasLocalLinkage() &&
551 "If Src has internal linkage, Dest shouldn't be set!");
553 bool SrcIsDeclaration = Src->isDeclaration() && !Src->isMaterializable();
554 bool DestIsDeclaration = Dest->isDeclaration();
556 if (SrcIsDeclaration) {
557 // If Src is external or if both Src & Dest are external.. Just link the
558 // external globals, we aren't adding anything.
559 if (Src->hasDLLImportStorageClass()) {
560 // If one of GVs is marked as DLLImport, result should be dllimport'ed.
561 if (DestIsDeclaration) {
563 LT = Src->getLinkage();
565 } else if (Dest->hasExternalWeakLinkage()) {
566 // If the Dest is weak, use the source linkage.
568 LT = Src->getLinkage();
571 LT = Dest->getLinkage();
573 } else if (DestIsDeclaration && !Dest->hasDLLImportStorageClass()) {
574 // If Dest is external but Src is not:
576 LT = Src->getLinkage();
577 } else if (Src->isWeakForLinker()) {
578 // At this point we know that Dest has LinkOnce, External*, Weak, Common,
580 if (Dest->hasExternalWeakLinkage() ||
581 Dest->hasAvailableExternallyLinkage() ||
582 (Dest->hasLinkOnceLinkage() &&
583 (Src->hasWeakLinkage() || Src->hasCommonLinkage()))) {
585 LT = Src->getLinkage();
588 LT = Dest->getLinkage();
590 } else if (Dest->isWeakForLinker()) {
591 // At this point we know that Src has External* or DLL* linkage.
592 if (Src->hasExternalWeakLinkage()) {
594 LT = Dest->getLinkage();
597 LT = GlobalValue::ExternalLinkage;
600 assert((Dest->hasExternalLinkage() || Dest->hasExternalWeakLinkage()) &&
601 (Src->hasExternalLinkage() || Src->hasExternalWeakLinkage()) &&
602 "Unexpected linkage type!");
603 return emitError("Linking globals named '" + Src->getName() +
604 "': symbol multiply defined!");
607 // Compute the visibility. We follow the rules in the System V Application
609 assert(!GlobalValue::isLocalLinkage(LT) &&
610 "Symbols with local linkage should not be merged");
611 Vis = isLessConstraining(Src->getVisibility(), Dest->getVisibility()) ?
612 Dest->getVisibility() : Src->getVisibility();
616 /// computeTypeMapping - Loop over all of the linked values to compute type
617 /// mappings. For example, if we link "extern Foo *x" and "Foo *x = NULL", then
618 /// we have two struct types 'Foo' but one got renamed when the module was
619 /// loaded into the same LLVMContext.
620 void ModuleLinker::computeTypeMapping() {
621 // Incorporate globals.
622 for (Module::global_iterator I = SrcM->global_begin(),
623 E = SrcM->global_end(); I != E; ++I) {
624 GlobalValue *DGV = getLinkedToGlobal(I);
627 if (!DGV->hasAppendingLinkage() || !I->hasAppendingLinkage()) {
628 TypeMap.addTypeMapping(DGV->getType(), I->getType());
632 // Unify the element type of appending arrays.
633 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
634 ArrayType *SAT = cast<ArrayType>(I->getType()->getElementType());
635 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
638 // Incorporate functions.
639 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I) {
640 if (GlobalValue *DGV = getLinkedToGlobal(I))
641 TypeMap.addTypeMapping(DGV->getType(), I->getType());
644 // Incorporate types by name, scanning all the types in the source module.
645 // At this point, the destination module may have a type "%foo = { i32 }" for
646 // example. When the source module got loaded into the same LLVMContext, if
647 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
648 TypeFinder SrcStructTypes;
649 SrcStructTypes.run(*SrcM, true);
650 SmallPtrSet<StructType*, 32> SrcStructTypesSet(SrcStructTypes.begin(),
651 SrcStructTypes.end());
653 for (unsigned i = 0, e = SrcStructTypes.size(); i != e; ++i) {
654 StructType *ST = SrcStructTypes[i];
655 if (!ST->hasName()) continue;
657 // Check to see if there is a dot in the name followed by a digit.
658 size_t DotPos = ST->getName().rfind('.');
659 if (DotPos == 0 || DotPos == StringRef::npos ||
660 ST->getName().back() == '.' ||
661 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos+1])))
664 // Check to see if the destination module has a struct with the prefix name.
665 if (StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos)))
666 // Don't use it if this actually came from the source module. They're in
667 // the same LLVMContext after all. Also don't use it unless the type is
668 // actually used in the destination module. This can happen in situations
673 // %Z = type { %A } %B = type { %C.1 }
674 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
675 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
676 // %C = type { i8* } %B.3 = type { %C.1 }
678 // When we link Module B with Module A, the '%B' in Module B is
679 // used. However, that would then use '%C.1'. But when we process '%C.1',
680 // we prefer to take the '%C' version. So we are then left with both
681 // '%C.1' and '%C' being used for the same types. This leads to some
682 // variables using one type and some using the other.
683 if (!SrcStructTypesSet.count(DST) && TypeMap.DstStructTypesSet.count(DST))
684 TypeMap.addTypeMapping(DST, ST);
687 // Don't bother incorporating aliases, they aren't generally typed well.
689 // Now that we have discovered all of the type equivalences, get a body for
690 // any 'opaque' types in the dest module that are now resolved.
691 TypeMap.linkDefinedTypeBodies();
694 /// linkAppendingVarProto - If there were any appending global variables, link
695 /// them together now. Return true on error.
696 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
697 GlobalVariable *SrcGV) {
699 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
700 return emitError("Linking globals named '" + SrcGV->getName() +
701 "': can only link appending global with another appending global!");
703 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
705 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
706 Type *EltTy = DstTy->getElementType();
708 // Check to see that they two arrays agree on type.
709 if (EltTy != SrcTy->getElementType())
710 return emitError("Appending variables with different element types!");
711 if (DstGV->isConstant() != SrcGV->isConstant())
712 return emitError("Appending variables linked with different const'ness!");
714 if (DstGV->getAlignment() != SrcGV->getAlignment())
716 "Appending variables with different alignment need to be linked!");
718 if (DstGV->getVisibility() != SrcGV->getVisibility())
720 "Appending variables with different visibility need to be linked!");
722 if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
724 "Appending variables with different unnamed_addr need to be linked!");
726 if (DstGV->getSection() != SrcGV->getSection())
728 "Appending variables with different section name need to be linked!");
730 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements();
731 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
733 // Create the new global variable.
735 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(),
736 DstGV->getLinkage(), /*init*/nullptr, /*name*/"", DstGV,
737 DstGV->getThreadLocalMode(),
738 DstGV->getType()->getAddressSpace());
740 // Propagate alignment, visibility and section info.
741 copyGVAttributes(NG, DstGV);
743 AppendingVarInfo AVI;
745 AVI.DstInit = DstGV->getInitializer();
746 AVI.SrcInit = SrcGV->getInitializer();
747 AppendingVars.push_back(AVI);
749 // Replace any uses of the two global variables with uses of the new
751 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
753 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
754 DstGV->eraseFromParent();
756 // Track the source variable so we don't try to link it.
757 DoNotLinkFromSource.insert(SrcGV);
762 /// linkGlobalProto - Loop through the global variables in the src module and
763 /// merge them into the dest module.
764 bool ModuleLinker::linkGlobalProto(GlobalVariable *SGV) {
765 GlobalValue *DGV = getLinkedToGlobal(SGV);
766 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
767 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
770 // Concatenation of appending linkage variables is magic and handled later.
771 if (DGV->hasAppendingLinkage() || SGV->hasAppendingLinkage())
772 return linkAppendingVarProto(cast<GlobalVariable>(DGV), SGV);
774 // Determine whether linkage of these two globals follows the source
775 // module's definition or the destination module's definition.
776 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
777 GlobalValue::VisibilityTypes NV;
778 bool LinkFromSrc = false;
779 if (getLinkageResult(DGV, SGV, NewLinkage, NV, LinkFromSrc))
782 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
784 // If we're not linking from the source, then keep the definition that we
787 // Special case for const propagation.
788 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV))
789 if (DGVar->isDeclaration() && SGV->isConstant() && !DGVar->isConstant())
790 DGVar->setConstant(true);
792 // Set calculated linkage, visibility and unnamed_addr.
793 DGV->setLinkage(NewLinkage);
794 DGV->setVisibility(*NewVisibility);
795 DGV->setUnnamedAddr(HasUnnamedAddr);
797 // Make sure to remember this mapping.
798 ValueMap[SGV] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGV->getType()));
800 // Track the source global so that we don't attempt to copy it over when
801 // processing global initializers.
802 DoNotLinkFromSource.insert(SGV);
808 // No linking to be performed or linking from the source: simply create an
809 // identical version of the symbol over in the dest module... the
810 // initializer will be filled in later by LinkGlobalInits.
811 GlobalVariable *NewDGV =
812 new GlobalVariable(*DstM, TypeMap.get(SGV->getType()->getElementType()),
813 SGV->isConstant(), SGV->getLinkage(), /*init*/nullptr,
814 SGV->getName(), /*insertbefore*/nullptr,
815 SGV->getThreadLocalMode(),
816 SGV->getType()->getAddressSpace());
817 // Propagate alignment, visibility and section info.
818 copyGVAttributes(NewDGV, SGV);
820 NewDGV->setVisibility(*NewVisibility);
821 NewDGV->setUnnamedAddr(HasUnnamedAddr);
824 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV, DGV->getType()));
825 DGV->eraseFromParent();
828 // Make sure to remember this mapping.
829 ValueMap[SGV] = NewDGV;
833 /// linkFunctionProto - Link the function in the source module into the
834 /// destination module if needed, setting up mapping information.
835 bool ModuleLinker::linkFunctionProto(Function *SF) {
836 GlobalValue *DGV = getLinkedToGlobal(SF);
837 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
838 bool HasUnnamedAddr = SF->hasUnnamedAddr();
841 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
842 bool LinkFromSrc = false;
843 GlobalValue::VisibilityTypes NV;
844 if (getLinkageResult(DGV, SF, NewLinkage, NV, LinkFromSrc))
847 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
850 // Set calculated linkage
851 DGV->setLinkage(NewLinkage);
852 DGV->setVisibility(*NewVisibility);
853 DGV->setUnnamedAddr(HasUnnamedAddr);
855 // Make sure to remember this mapping.
856 ValueMap[SF] = ConstantExpr::getBitCast(DGV, TypeMap.get(SF->getType()));
858 // Track the function from the source module so we don't attempt to remap
860 DoNotLinkFromSource.insert(SF);
866 // If the function is to be lazily linked, don't create it just yet.
867 // The ValueMaterializerTy will deal with creating it if it's used.
868 if (!DGV && (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() ||
869 SF->hasAvailableExternallyLinkage())) {
870 DoNotLinkFromSource.insert(SF);
874 // If there is no linkage to be performed or we are linking from the source,
876 Function *NewDF = Function::Create(TypeMap.get(SF->getFunctionType()),
877 SF->getLinkage(), SF->getName(), DstM);
878 copyGVAttributes(NewDF, SF);
880 NewDF->setVisibility(*NewVisibility);
881 NewDF->setUnnamedAddr(HasUnnamedAddr);
884 // Any uses of DF need to change to NewDF, with cast.
885 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, DGV->getType()));
886 DGV->eraseFromParent();
889 ValueMap[SF] = NewDF;
893 /// LinkAliasProto - Set up prototypes for any aliases that come over from the
895 bool ModuleLinker::linkAliasProto(GlobalAlias *SGA) {
896 GlobalValue *DGV = getLinkedToGlobal(SGA);
897 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
900 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
901 GlobalValue::VisibilityTypes NV;
902 bool LinkFromSrc = false;
903 if (getLinkageResult(DGV, SGA, NewLinkage, NV, LinkFromSrc))
908 // Set calculated linkage.
909 DGV->setLinkage(NewLinkage);
910 DGV->setVisibility(*NewVisibility);
912 // Make sure to remember this mapping.
913 ValueMap[SGA] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGA->getType()));
915 // Track the alias from the source module so we don't attempt to remap it.
916 DoNotLinkFromSource.insert(SGA);
922 // If there is no linkage to be performed or we're linking from the source,
924 auto *PTy = cast<PointerType>(TypeMap.get(SGA->getType()));
926 GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(),
927 SGA->getLinkage(), SGA->getName(), DstM);
928 copyGVAttributes(NewDA, SGA);
930 NewDA->setVisibility(*NewVisibility);
933 ReplaceWithAlias.push_back(std::make_pair(DGV, NewDA));
935 ValueMap[SGA] = NewDA;
939 static void getArrayElements(Constant *C, SmallVectorImpl<Constant*> &Dest) {
940 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
942 for (unsigned i = 0; i != NumElements; ++i)
943 Dest.push_back(C->getAggregateElement(i));
946 void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) {
947 // Merge the initializer.
948 SmallVector<Constant*, 16> Elements;
949 getArrayElements(AVI.DstInit, Elements);
951 Constant *SrcInit = MapValue(AVI.SrcInit, ValueMap, RF_None, &TypeMap, &ValMaterializer);
952 getArrayElements(SrcInit, Elements);
954 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
955 AVI.NewGV->setInitializer(ConstantArray::get(NewType, Elements));
958 /// linkGlobalInits - Update the initializers in the Dest module now that all
959 /// globals that may be referenced are in Dest.
960 void ModuleLinker::linkGlobalInits() {
961 // Loop over all of the globals in the src module, mapping them over as we go
962 for (Module::const_global_iterator I = SrcM->global_begin(),
963 E = SrcM->global_end(); I != E; ++I) {
965 // Only process initialized GV's or ones not already in dest.
966 if (!I->hasInitializer() || DoNotLinkFromSource.count(I)) continue;
968 // Grab destination global variable.
969 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[I]);
970 // Figure out what the initializer looks like in the dest module.
971 DGV->setInitializer(MapValue(I->getInitializer(), ValueMap,
972 RF_None, &TypeMap, &ValMaterializer));
976 /// linkFunctionBody - Copy the source function over into the dest function and
977 /// fix up references to values. At this point we know that Dest is an external
978 /// function, and that Src is not.
979 void ModuleLinker::linkFunctionBody(Function *Dst, Function *Src) {
980 assert(Src && Dst && Dst->isDeclaration() && !Src->isDeclaration());
982 // Go through and convert function arguments over, remembering the mapping.
983 Function::arg_iterator DI = Dst->arg_begin();
984 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
986 DI->setName(I->getName()); // Copy the name over.
988 // Add a mapping to our mapping.
992 if (Mode == Linker::DestroySource) {
993 // Splice the body of the source function into the dest function.
994 Dst->getBasicBlockList().splice(Dst->end(), Src->getBasicBlockList());
996 // At this point, all of the instructions and values of the function are now
997 // copied over. The only problem is that they are still referencing values in
998 // the Source function as operands. Loop through all of the operands of the
999 // functions and patch them up to point to the local versions.
1000 for (Function::iterator BB = Dst->begin(), BE = Dst->end(); BB != BE; ++BB)
1001 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
1002 RemapInstruction(I, ValueMap, RF_IgnoreMissingEntries,
1003 &TypeMap, &ValMaterializer);
1006 // Clone the body of the function into the dest function.
1007 SmallVector<ReturnInst*, 8> Returns; // Ignore returns.
1008 CloneFunctionInto(Dst, Src, ValueMap, false, Returns, "", nullptr,
1009 &TypeMap, &ValMaterializer);
1012 // There is no need to map the arguments anymore.
1013 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1019 static GlobalObject &getGlobalObjectInExpr(Constant &C) {
1020 auto *GO = dyn_cast<GlobalObject>(&C);
1023 auto *GA = dyn_cast<GlobalAlias>(&C);
1025 return *GA->getAliasee();
1026 auto &CE = cast<ConstantExpr>(C);
1027 assert(CE.getOpcode() == Instruction::BitCast ||
1028 CE.getOpcode() == Instruction::AddrSpaceCast);
1029 return getGlobalObjectInExpr(*CE.getOperand(0));
1032 /// linkAliasBodies - Insert all of the aliases in Src into the Dest module.
1033 void ModuleLinker::linkAliasBodies() {
1034 for (Module::alias_iterator I = SrcM->alias_begin(), E = SrcM->alias_end();
1036 if (DoNotLinkFromSource.count(I))
1038 if (Constant *Aliasee = I->getAliasee()) {
1039 GlobalAlias *DA = cast<GlobalAlias>(ValueMap[I]);
1041 MapValue(Aliasee, ValueMap, RF_None, &TypeMap, &ValMaterializer);
1042 DA->setAliasee(&getGlobalObjectInExpr(*Val));
1046 // Any uses of DGV need to change to NewDA, with cast.
1047 for (auto &Pair : ReplaceWithAlias) {
1048 GlobalValue *DGV = Pair.first;
1049 GlobalAlias *NewDA = Pair.second;
1051 for (auto *User : DGV->users()) {
1052 if (auto *GA = dyn_cast<GlobalAlias>(User)) {
1054 report_fatal_error("Linking these modules creates an alias cycle.");
1058 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDA, DGV->getType()));
1059 DGV->eraseFromParent();
1063 /// linkNamedMDNodes - Insert all of the named MDNodes in Src into the Dest
1065 void ModuleLinker::linkNamedMDNodes() {
1066 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1067 for (Module::const_named_metadata_iterator I = SrcM->named_metadata_begin(),
1068 E = SrcM->named_metadata_end(); I != E; ++I) {
1069 // Don't link module flags here. Do them separately.
1070 if (&*I == SrcModFlags) continue;
1071 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(I->getName());
1072 // Add Src elements into Dest node.
1073 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
1074 DestNMD->addOperand(MapValue(I->getOperand(i), ValueMap,
1075 RF_None, &TypeMap, &ValMaterializer));
1079 /// linkModuleFlagsMetadata - Merge the linker flags in Src into the Dest
1081 bool ModuleLinker::linkModuleFlagsMetadata() {
1082 // If the source module has no module flags, we are done.
1083 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1084 if (!SrcModFlags) return false;
1086 // If the destination module doesn't have module flags yet, then just copy
1087 // over the source module's flags.
1088 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
1089 if (DstModFlags->getNumOperands() == 0) {
1090 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1091 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1096 // First build a map of the existing module flags and requirements.
1097 DenseMap<MDString*, MDNode*> Flags;
1098 SmallSetVector<MDNode*, 16> Requirements;
1099 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1100 MDNode *Op = DstModFlags->getOperand(I);
1101 ConstantInt *Behavior = cast<ConstantInt>(Op->getOperand(0));
1102 MDString *ID = cast<MDString>(Op->getOperand(1));
1104 if (Behavior->getZExtValue() == Module::Require) {
1105 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1111 // Merge in the flags from the source module, and also collect its set of
1113 bool HasErr = false;
1114 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1115 MDNode *SrcOp = SrcModFlags->getOperand(I);
1116 ConstantInt *SrcBehavior = cast<ConstantInt>(SrcOp->getOperand(0));
1117 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1118 MDNode *DstOp = Flags.lookup(ID);
1119 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1121 // If this is a requirement, add it and continue.
1122 if (SrcBehaviorValue == Module::Require) {
1123 // If the destination module does not already have this requirement, add
1125 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1126 DstModFlags->addOperand(SrcOp);
1131 // If there is no existing flag with this ID, just add it.
1134 DstModFlags->addOperand(SrcOp);
1138 // Otherwise, perform a merge.
1139 ConstantInt *DstBehavior = cast<ConstantInt>(DstOp->getOperand(0));
1140 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1142 // If either flag has override behavior, handle it first.
1143 if (DstBehaviorValue == Module::Override) {
1144 // Diagnose inconsistent flags which both have override behavior.
1145 if (SrcBehaviorValue == Module::Override &&
1146 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1147 HasErr |= emitError("linking module flags '" + ID->getString() +
1148 "': IDs have conflicting override values");
1151 } else if (SrcBehaviorValue == Module::Override) {
1152 // Update the destination flag to that of the source.
1153 DstOp->replaceOperandWith(0, SrcBehavior);
1154 DstOp->replaceOperandWith(2, SrcOp->getOperand(2));
1158 // Diagnose inconsistent merge behavior types.
1159 if (SrcBehaviorValue != DstBehaviorValue) {
1160 HasErr |= emitError("linking module flags '" + ID->getString() +
1161 "': IDs have conflicting behaviors");
1165 // Perform the merge for standard behavior types.
1166 switch (SrcBehaviorValue) {
1167 case Module::Require:
1168 case Module::Override: assert(0 && "not possible"); break;
1169 case Module::Error: {
1170 // Emit an error if the values differ.
1171 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1172 HasErr |= emitError("linking module flags '" + ID->getString() +
1173 "': IDs have conflicting values");
1177 case Module::Warning: {
1178 // Emit a warning if the values differ.
1179 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1180 if (!SuppressWarnings) {
1181 errs() << "WARNING: linking module flags '" << ID->getString()
1182 << "': IDs have conflicting values";
1187 case Module::Append: {
1188 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1189 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1190 unsigned NumOps = DstValue->getNumOperands() + SrcValue->getNumOperands();
1191 Value **VP, **Values = VP = new Value*[NumOps];
1192 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i, ++VP)
1193 *VP = DstValue->getOperand(i);
1194 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i, ++VP)
1195 *VP = SrcValue->getOperand(i);
1196 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1197 ArrayRef<Value*>(Values,
1202 case Module::AppendUnique: {
1203 SmallSetVector<Value*, 16> Elts;
1204 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1205 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1206 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i)
1207 Elts.insert(DstValue->getOperand(i));
1208 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i)
1209 Elts.insert(SrcValue->getOperand(i));
1210 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1211 ArrayRef<Value*>(Elts.begin(),
1218 // Check all of the requirements.
1219 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1220 MDNode *Requirement = Requirements[I];
1221 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1222 Value *ReqValue = Requirement->getOperand(1);
1224 MDNode *Op = Flags[Flag];
1225 if (!Op || Op->getOperand(2) != ReqValue) {
1226 HasErr |= emitError("linking module flags '" + Flag->getString() +
1227 "': does not have the required value");
1235 bool ModuleLinker::run() {
1236 assert(DstM && "Null destination module");
1237 assert(SrcM && "Null source module");
1239 // Inherit the target data from the source module if the destination module
1240 // doesn't have one already.
1241 if (!DstM->getDataLayout() && SrcM->getDataLayout())
1242 DstM->setDataLayout(SrcM->getDataLayout());
1244 // Copy the target triple from the source to dest if the dest's is empty.
1245 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
1246 DstM->setTargetTriple(SrcM->getTargetTriple());
1248 if (SrcM->getDataLayout() && DstM->getDataLayout() &&
1249 *SrcM->getDataLayout() != *DstM->getDataLayout()) {
1250 if (!SuppressWarnings) {
1251 errs() << "WARNING: Linking two modules of different data layouts: '"
1252 << SrcM->getModuleIdentifier() << "' is '"
1253 << SrcM->getDataLayoutStr() << "' whereas '"
1254 << DstM->getModuleIdentifier() << "' is '"
1255 << DstM->getDataLayoutStr() << "'\n";
1258 if (!SrcM->getTargetTriple().empty() &&
1259 DstM->getTargetTriple() != SrcM->getTargetTriple()) {
1260 if (!SuppressWarnings) {
1261 errs() << "WARNING: Linking two modules of different target triples: "
1262 << SrcM->getModuleIdentifier() << "' is '"
1263 << SrcM->getTargetTriple() << "' whereas '"
1264 << DstM->getModuleIdentifier() << "' is '"
1265 << DstM->getTargetTriple() << "'\n";
1269 // Append the module inline asm string.
1270 if (!SrcM->getModuleInlineAsm().empty()) {
1271 if (DstM->getModuleInlineAsm().empty())
1272 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
1274 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
1275 SrcM->getModuleInlineAsm());
1278 // Loop over all of the linked values to compute type mappings.
1279 computeTypeMapping();
1281 // Insert all of the globals in src into the DstM module... without linking
1282 // initializers (which could refer to functions not yet mapped over).
1283 for (Module::global_iterator I = SrcM->global_begin(),
1284 E = SrcM->global_end(); I != E; ++I)
1285 if (linkGlobalProto(I))
1288 // Link the functions together between the two modules, without doing function
1289 // bodies... this just adds external function prototypes to the DstM
1290 // function... We do this so that when we begin processing function bodies,
1291 // all of the global values that may be referenced are available in our
1293 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I)
1294 if (linkFunctionProto(I))
1297 // If there were any aliases, link them now.
1298 for (Module::alias_iterator I = SrcM->alias_begin(),
1299 E = SrcM->alias_end(); I != E; ++I)
1300 if (linkAliasProto(I))
1303 for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i)
1304 linkAppendingVarInit(AppendingVars[i]);
1306 // Link in the function bodies that are defined in the source module into
1308 for (Module::iterator SF = SrcM->begin(), E = SrcM->end(); SF != E; ++SF) {
1309 // Skip if not linking from source.
1310 if (DoNotLinkFromSource.count(SF)) continue;
1312 Function *DF = cast<Function>(ValueMap[SF]);
1313 if (SF->hasPrefixData()) {
1314 // Link in the prefix data.
1315 DF->setPrefixData(MapValue(
1316 SF->getPrefixData(), ValueMap, RF_None, &TypeMap, &ValMaterializer));
1319 // Skip if no body (function is external) or materialize.
1320 if (SF->isDeclaration()) {
1321 if (!SF->isMaterializable())
1323 if (SF->Materialize(&ErrorMsg))
1327 linkFunctionBody(DF, SF);
1328 SF->Dematerialize();
1331 // Resolve all uses of aliases with aliasees.
1334 // Remap all of the named MDNodes in Src into the DstM module. We do this
1335 // after linking GlobalValues so that MDNodes that reference GlobalValues
1336 // are properly remapped.
1339 // Merge the module flags into the DstM module.
1340 if (linkModuleFlagsMetadata())
1343 // Update the initializers in the DstM module now that all globals that may
1344 // be referenced are in DstM.
1347 // Process vector of lazily linked in functions.
1348 bool LinkedInAnyFunctions;
1350 LinkedInAnyFunctions = false;
1352 for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(),
1353 E = LazilyLinkFunctions.end(); I != E; ++I) {
1358 Function *DF = cast<Function>(ValueMap[SF]);
1359 if (SF->hasPrefixData()) {
1360 // Link in the prefix data.
1361 DF->setPrefixData(MapValue(SF->getPrefixData(),
1368 // Materialize if necessary.
1369 if (SF->isDeclaration()) {
1370 if (!SF->isMaterializable())
1372 if (SF->Materialize(&ErrorMsg))
1376 // Erase from vector *before* the function body is linked - linkFunctionBody could
1378 LazilyLinkFunctions.erase(I);
1380 // Link in function body.
1381 linkFunctionBody(DF, SF);
1382 SF->Dematerialize();
1384 // Set flag to indicate we may have more functions to lazily link in
1385 // since we linked in a function.
1386 LinkedInAnyFunctions = true;
1389 } while (LinkedInAnyFunctions);
1391 // Now that all of the types from the source are used, resolve any structs
1392 // copied over to the dest that didn't exist there.
1393 TypeMap.linkDefinedTypeBodies();
1398 Linker::Linker(Module *M, bool SuppressWarnings)
1399 : Composite(M), SuppressWarnings(SuppressWarnings) {
1400 TypeFinder StructTypes;
1401 StructTypes.run(*M, true);
1402 IdentifiedStructTypes.insert(StructTypes.begin(), StructTypes.end());
1408 void Linker::deleteModule() {
1410 Composite = nullptr;
1413 bool Linker::linkInModule(Module *Src, unsigned Mode, std::string *ErrorMsg) {
1414 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src, Mode,
1416 if (TheLinker.run()) {
1418 *ErrorMsg = TheLinker.ErrorMsg;
1424 //===----------------------------------------------------------------------===//
1425 // LinkModules entrypoint.
1426 //===----------------------------------------------------------------------===//
1428 /// LinkModules - This function links two modules together, with the resulting
1429 /// Dest module modified to be the composite of the two input modules. If an
1430 /// error occurs, true is returned and ErrorMsg (if not null) is set to indicate
1431 /// the problem. Upon failure, the Dest module could be in a modified state,
1432 /// and shouldn't be relied on to be consistent.
1433 bool Linker::LinkModules(Module *Dest, Module *Src, unsigned Mode,
1434 std::string *ErrorMsg) {
1436 return L.linkInModule(Src, Mode, ErrorMsg);
1439 //===----------------------------------------------------------------------===//
1441 //===----------------------------------------------------------------------===//
1443 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
1444 LLVMLinkerMode Mode, char **OutMessages) {
1445 std::string Messages;
1446 LLVMBool Result = Linker::LinkModules(unwrap(Dest), unwrap(Src),
1447 Mode, OutMessages? &Messages : nullptr);
1449 *OutMessages = strdup(Messages.c_str());