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 // Specifically, this:
13 // * Merges global variables between the two modules
14 // * Uninit + Uninit = Init, Init + Uninit = Init, Init + Init = Error if !=
15 // * Merges functions between two modules
17 //===----------------------------------------------------------------------===//
19 #include "llvm/Linker.h"
20 #include "llvm/Constants.h"
21 #include "llvm/DerivedTypes.h"
22 #include "llvm/LLVMContext.h"
23 #include "llvm/Module.h"
24 #include "llvm/TypeSymbolTable.h"
25 #include "llvm/ValueSymbolTable.h"
26 #include "llvm/Instructions.h"
27 #include "llvm/Assembly/Writer.h"
28 #include "llvm/Support/Streams.h"
29 #include "llvm/System/Path.h"
30 #include "llvm/ADT/DenseMap.h"
34 // Error - Simple wrapper function to conditionally assign to E and return true.
35 // This just makes error return conditions a little bit simpler...
36 static inline bool Error(std::string *E, const std::string &Message) {
41 // Function: ResolveTypes()
44 // Attempt to link the two specified types together.
47 // DestTy - The type to which we wish to resolve.
48 // SrcTy - The original type which we want to resolve.
51 // DestST - The symbol table in which the new type should be placed.
54 // true - There is an error and the types cannot yet be linked.
57 static bool ResolveTypes(const Type *DestTy, const Type *SrcTy) {
58 if (DestTy == SrcTy) return false; // If already equal, noop
59 assert(DestTy && SrcTy && "Can't handle null types");
61 if (const OpaqueType *OT = dyn_cast<OpaqueType>(DestTy)) {
62 // Type _is_ in module, just opaque...
63 const_cast<OpaqueType*>(OT)->refineAbstractTypeTo(SrcTy);
64 } else if (const OpaqueType *OT = dyn_cast<OpaqueType>(SrcTy)) {
65 const_cast<OpaqueType*>(OT)->refineAbstractTypeTo(DestTy);
67 return true; // Cannot link types... not-equal and neither is opaque.
72 /// LinkerTypeMap - This implements a map of types that is stable
73 /// even if types are resolved/refined to other types. This is not a general
74 /// purpose map, it is specific to the linker's use.
76 class LinkerTypeMap : public AbstractTypeUser {
77 typedef DenseMap<const Type*, PATypeHolder> TheMapTy;
80 LinkerTypeMap(const LinkerTypeMap&); // DO NOT IMPLEMENT
81 void operator=(const LinkerTypeMap&); // DO NOT IMPLEMENT
85 for (DenseMap<const Type*, PATypeHolder>::iterator I = TheMap.begin(),
86 E = TheMap.end(); I != E; ++I)
87 I->first->removeAbstractTypeUser(this);
90 /// lookup - Return the value for the specified type or null if it doesn't
92 const Type *lookup(const Type *Ty) const {
93 TheMapTy::const_iterator I = TheMap.find(Ty);
94 if (I != TheMap.end()) return I->second;
98 /// erase - Remove the specified type, returning true if it was in the set.
99 bool erase(const Type *Ty) {
100 if (!TheMap.erase(Ty))
102 if (Ty->isAbstract())
103 Ty->removeAbstractTypeUser(this);
107 /// insert - This returns true if the pointer was new to the set, false if it
108 /// was already in the set.
109 bool insert(const Type *Src, const Type *Dst) {
110 if (!TheMap.insert(std::make_pair(Src, PATypeHolder(Dst))).second)
111 return false; // Already in map.
112 if (Src->isAbstract())
113 Src->addAbstractTypeUser(this);
118 /// refineAbstractType - The callback method invoked when an abstract type is
119 /// resolved to another type. An object must override this method to update
120 /// its internal state to reference NewType instead of OldType.
122 virtual void refineAbstractType(const DerivedType *OldTy,
124 TheMapTy::iterator I = TheMap.find(OldTy);
125 const Type *DstTy = I->second;
128 if (OldTy->isAbstract())
129 OldTy->removeAbstractTypeUser(this);
131 // Don't reinsert into the map if the key is concrete now.
132 if (NewTy->isAbstract())
133 insert(NewTy, DstTy);
136 /// The other case which AbstractTypeUsers must be aware of is when a type
137 /// makes the transition from being abstract (where it has clients on it's
138 /// AbstractTypeUsers list) to concrete (where it does not). This method
139 /// notifies ATU's when this occurs for a type.
140 virtual void typeBecameConcrete(const DerivedType *AbsTy) {
142 AbsTy->removeAbstractTypeUser(this);
146 virtual void dump() const {
147 cerr << "AbstractTypeSet!\n";
153 // RecursiveResolveTypes - This is just like ResolveTypes, except that it
154 // recurses down into derived types, merging the used types if the parent types
156 static bool RecursiveResolveTypesI(const Type *DstTy, const Type *SrcTy,
157 LinkerTypeMap &Pointers) {
158 if (DstTy == SrcTy) return false; // If already equal, noop
160 // If we found our opaque type, resolve it now!
161 if (isa<OpaqueType>(DstTy) || isa<OpaqueType>(SrcTy))
162 return ResolveTypes(DstTy, SrcTy);
164 // Two types cannot be resolved together if they are of different primitive
165 // type. For example, we cannot resolve an int to a float.
166 if (DstTy->getTypeID() != SrcTy->getTypeID()) return true;
168 // If neither type is abstract, then they really are just different types.
169 if (!DstTy->isAbstract() && !SrcTy->isAbstract())
172 // Otherwise, resolve the used type used by this derived type...
173 switch (DstTy->getTypeID()) {
176 case Type::FunctionTyID: {
177 const FunctionType *DstFT = cast<FunctionType>(DstTy);
178 const FunctionType *SrcFT = cast<FunctionType>(SrcTy);
179 if (DstFT->isVarArg() != SrcFT->isVarArg() ||
180 DstFT->getNumContainedTypes() != SrcFT->getNumContainedTypes())
183 // Use TypeHolder's so recursive resolution won't break us.
184 PATypeHolder ST(SrcFT), DT(DstFT);
185 for (unsigned i = 0, e = DstFT->getNumContainedTypes(); i != e; ++i) {
186 const Type *SE = ST->getContainedType(i), *DE = DT->getContainedType(i);
187 if (SE != DE && RecursiveResolveTypesI(DE, SE, Pointers))
192 case Type::StructTyID: {
193 const StructType *DstST = cast<StructType>(DstTy);
194 const StructType *SrcST = cast<StructType>(SrcTy);
195 if (DstST->getNumContainedTypes() != SrcST->getNumContainedTypes())
198 PATypeHolder ST(SrcST), DT(DstST);
199 for (unsigned i = 0, e = DstST->getNumContainedTypes(); i != e; ++i) {
200 const Type *SE = ST->getContainedType(i), *DE = DT->getContainedType(i);
201 if (SE != DE && RecursiveResolveTypesI(DE, SE, Pointers))
206 case Type::ArrayTyID: {
207 const ArrayType *DAT = cast<ArrayType>(DstTy);
208 const ArrayType *SAT = cast<ArrayType>(SrcTy);
209 if (DAT->getNumElements() != SAT->getNumElements()) return true;
210 return RecursiveResolveTypesI(DAT->getElementType(), SAT->getElementType(),
213 case Type::VectorTyID: {
214 const VectorType *DVT = cast<VectorType>(DstTy);
215 const VectorType *SVT = cast<VectorType>(SrcTy);
216 if (DVT->getNumElements() != SVT->getNumElements()) return true;
217 return RecursiveResolveTypesI(DVT->getElementType(), SVT->getElementType(),
220 case Type::PointerTyID: {
221 const PointerType *DstPT = cast<PointerType>(DstTy);
222 const PointerType *SrcPT = cast<PointerType>(SrcTy);
224 if (DstPT->getAddressSpace() != SrcPT->getAddressSpace())
227 // If this is a pointer type, check to see if we have already seen it. If
228 // so, we are in a recursive branch. Cut off the search now. We cannot use
229 // an associative container for this search, because the type pointers (keys
230 // in the container) change whenever types get resolved.
231 if (SrcPT->isAbstract())
232 if (const Type *ExistingDestTy = Pointers.lookup(SrcPT))
233 return ExistingDestTy != DstPT;
235 if (DstPT->isAbstract())
236 if (const Type *ExistingSrcTy = Pointers.lookup(DstPT))
237 return ExistingSrcTy != SrcPT;
238 // Otherwise, add the current pointers to the vector to stop recursion on
240 if (DstPT->isAbstract())
241 Pointers.insert(DstPT, SrcPT);
242 if (SrcPT->isAbstract())
243 Pointers.insert(SrcPT, DstPT);
245 return RecursiveResolveTypesI(DstPT->getElementType(),
246 SrcPT->getElementType(), Pointers);
251 static bool RecursiveResolveTypes(const Type *DestTy, const Type *SrcTy) {
252 LinkerTypeMap PointerTypes;
253 return RecursiveResolveTypesI(DestTy, SrcTy, PointerTypes);
257 // LinkTypes - Go through the symbol table of the Src module and see if any
258 // types are named in the src module that are not named in the Dst module.
259 // Make sure there are no type name conflicts.
260 static bool LinkTypes(Module *Dest, const Module *Src, std::string *Err) {
261 TypeSymbolTable *DestST = &Dest->getTypeSymbolTable();
262 const TypeSymbolTable *SrcST = &Src->getTypeSymbolTable();
264 // Look for a type plane for Type's...
265 TypeSymbolTable::const_iterator TI = SrcST->begin();
266 TypeSymbolTable::const_iterator TE = SrcST->end();
267 if (TI == TE) return false; // No named types, do nothing.
269 // Some types cannot be resolved immediately because they depend on other
270 // types being resolved to each other first. This contains a list of types we
271 // are waiting to recheck.
272 std::vector<std::string> DelayedTypesToResolve;
274 for ( ; TI != TE; ++TI ) {
275 const std::string &Name = TI->first;
276 const Type *RHS = TI->second;
278 // Check to see if this type name is already in the dest module.
279 Type *Entry = DestST->lookup(Name);
281 // If the name is just in the source module, bring it over to the dest.
284 DestST->insert(Name, const_cast<Type*>(RHS));
285 } else if (ResolveTypes(Entry, RHS)) {
286 // They look different, save the types 'till later to resolve.
287 DelayedTypesToResolve.push_back(Name);
291 // Iteratively resolve types while we can...
292 while (!DelayedTypesToResolve.empty()) {
293 // Loop over all of the types, attempting to resolve them if possible...
294 unsigned OldSize = DelayedTypesToResolve.size();
296 // Try direct resolution by name...
297 for (unsigned i = 0; i != DelayedTypesToResolve.size(); ++i) {
298 const std::string &Name = DelayedTypesToResolve[i];
299 Type *T1 = SrcST->lookup(Name);
300 Type *T2 = DestST->lookup(Name);
301 if (!ResolveTypes(T2, T1)) {
302 // We are making progress!
303 DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i);
308 // Did we not eliminate any types?
309 if (DelayedTypesToResolve.size() == OldSize) {
310 // Attempt to resolve subelements of types. This allows us to merge these
311 // two types: { int* } and { opaque* }
312 for (unsigned i = 0, e = DelayedTypesToResolve.size(); i != e; ++i) {
313 const std::string &Name = DelayedTypesToResolve[i];
314 if (!RecursiveResolveTypes(SrcST->lookup(Name), DestST->lookup(Name))) {
315 // We are making progress!
316 DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i);
318 // Go back to the main loop, perhaps we can resolve directly by name
324 // If we STILL cannot resolve the types, then there is something wrong.
325 if (DelayedTypesToResolve.size() == OldSize) {
326 // Remove the symbol name from the destination.
327 DelayedTypesToResolve.pop_back();
337 static void PrintMap(const std::map<const Value*, Value*> &M) {
338 for (std::map<const Value*, Value*>::const_iterator I = M.begin(), E =M.end();
340 cerr << " Fr: " << (void*)I->first << " ";
342 cerr << " To: " << (void*)I->second << " ";
350 // RemapOperand - Use ValueMap to convert constants from one module to another.
351 static Value *RemapOperand(const Value *In,
352 std::map<const Value*, Value*> &ValueMap,
353 LLVMContext &Context) {
354 std::map<const Value*,Value*>::const_iterator I = ValueMap.find(In);
355 if (I != ValueMap.end())
358 // Check to see if it's a constant that we are interested in transforming.
360 if (const Constant *CPV = dyn_cast<Constant>(In)) {
361 if ((!isa<DerivedType>(CPV->getType()) && !isa<ConstantExpr>(CPV)) ||
362 isa<ConstantInt>(CPV) || isa<ConstantAggregateZero>(CPV))
363 return const_cast<Constant*>(CPV); // Simple constants stay identical.
365 if (const ConstantArray *CPA = dyn_cast<ConstantArray>(CPV)) {
366 std::vector<Constant*> Operands(CPA->getNumOperands());
367 for (unsigned i = 0, e = CPA->getNumOperands(); i != e; ++i)
368 Operands[i] =cast<Constant>(RemapOperand(CPA->getOperand(i), ValueMap,
371 Context.getConstantArray(cast<ArrayType>(CPA->getType()), Operands);
372 } else if (const ConstantStruct *CPS = dyn_cast<ConstantStruct>(CPV)) {
373 std::vector<Constant*> Operands(CPS->getNumOperands());
374 for (unsigned i = 0, e = CPS->getNumOperands(); i != e; ++i)
375 Operands[i] =cast<Constant>(RemapOperand(CPS->getOperand(i), ValueMap,
378 Context.getConstantStruct(cast<StructType>(CPS->getType()), Operands);
379 } else if (isa<ConstantPointerNull>(CPV) || isa<UndefValue>(CPV)) {
380 Result = const_cast<Constant*>(CPV);
381 } else if (const ConstantVector *CP = dyn_cast<ConstantVector>(CPV)) {
382 std::vector<Constant*> Operands(CP->getNumOperands());
383 for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i)
384 Operands[i] = cast<Constant>(RemapOperand(CP->getOperand(i), ValueMap,
386 Result = Context.getConstantVector(Operands);
387 } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CPV)) {
388 std::vector<Constant*> Ops;
389 for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i)
390 Ops.push_back(cast<Constant>(RemapOperand(CE->getOperand(i),ValueMap,
392 Result = CE->getWithOperands(Ops);
394 assert(!isa<GlobalValue>(CPV) && "Unmapped global?");
395 assert(0 && "Unknown type of derived type constant value!");
397 } else if (isa<InlineAsm>(In)) {
398 Result = const_cast<Value*>(In);
401 // Cache the mapping in our local map structure
403 ValueMap[In] = Result;
408 cerr << "LinkModules ValueMap: \n";
411 cerr << "Couldn't remap value: " << (void*)In << " " << *In << "\n";
412 assert(0 && "Couldn't remap value!");
417 /// ForceRenaming - The LLVM SymbolTable class autorenames globals that conflict
418 /// in the symbol table. This is good for all clients except for us. Go
419 /// through the trouble to force this back.
420 static void ForceRenaming(GlobalValue *GV, const std::string &Name) {
421 assert(GV->getName() != Name && "Can't force rename to self");
422 ValueSymbolTable &ST = GV->getParent()->getValueSymbolTable();
424 // If there is a conflict, rename the conflict.
425 if (GlobalValue *ConflictGV = cast_or_null<GlobalValue>(ST.lookup(Name))) {
426 assert(ConflictGV->hasLocalLinkage() &&
427 "Not conflicting with a static global, should link instead!");
428 GV->takeName(ConflictGV);
429 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
430 assert(ConflictGV->getName() != Name && "ForceRenaming didn't work");
432 GV->setName(Name); // Force the name back
436 /// CopyGVAttributes - copy additional attributes (those not needed to construct
437 /// a GlobalValue) from the SrcGV to the DestGV.
438 static void CopyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) {
439 // Use the maximum alignment, rather than just copying the alignment of SrcGV.
440 unsigned Alignment = std::max(DestGV->getAlignment(), SrcGV->getAlignment());
441 DestGV->copyAttributesFrom(SrcGV);
442 DestGV->setAlignment(Alignment);
445 /// GetLinkageResult - This analyzes the two global values and determines what
446 /// the result will look like in the destination module. In particular, it
447 /// computes the resultant linkage type, computes whether the global in the
448 /// source should be copied over to the destination (replacing the existing
449 /// one), and computes whether this linkage is an error or not. It also performs
450 /// visibility checks: we cannot link together two symbols with different
452 static bool GetLinkageResult(GlobalValue *Dest, const GlobalValue *Src,
453 GlobalValue::LinkageTypes <, bool &LinkFromSrc,
455 assert((!Dest || !Src->hasLocalLinkage()) &&
456 "If Src has internal linkage, Dest shouldn't be set!");
458 // Linking something to nothing.
460 LT = Src->getLinkage();
461 } else if (Src->isDeclaration()) {
462 // If Src is external or if both Src & Dest are external.. Just link the
463 // external globals, we aren't adding anything.
464 if (Src->hasDLLImportLinkage()) {
465 // If one of GVs has DLLImport linkage, result should be dllimport'ed.
466 if (Dest->isDeclaration()) {
468 LT = Src->getLinkage();
470 } else if (Dest->hasExternalWeakLinkage()) {
471 // If the Dest is weak, use the source linkage.
473 LT = Src->getLinkage();
476 LT = Dest->getLinkage();
478 } else if (Dest->isDeclaration() && !Dest->hasDLLImportLinkage()) {
479 // If Dest is external but Src is not:
481 LT = Src->getLinkage();
482 } else if (Src->hasAppendingLinkage() || Dest->hasAppendingLinkage()) {
483 if (Src->getLinkage() != Dest->getLinkage())
484 return Error(Err, "Linking globals named '" + Src->getName() +
485 "': can only link appending global with another appending global!");
486 LinkFromSrc = true; // Special cased.
487 LT = Src->getLinkage();
488 } else if (Src->isWeakForLinker()) {
489 // At this point we know that Dest has LinkOnce, External*, Weak, Common,
491 if (Dest->hasExternalWeakLinkage() ||
492 Dest->hasAvailableExternallyLinkage() ||
493 (Dest->hasLinkOnceLinkage() &&
494 (Src->hasWeakLinkage() || Src->hasCommonLinkage()))) {
496 LT = Src->getLinkage();
499 LT = Dest->getLinkage();
501 } else if (Dest->isWeakForLinker()) {
502 // At this point we know that Src has External* or DLL* linkage.
503 if (Src->hasExternalWeakLinkage()) {
505 LT = Dest->getLinkage();
508 LT = GlobalValue::ExternalLinkage;
511 assert((Dest->hasExternalLinkage() ||
512 Dest->hasDLLImportLinkage() ||
513 Dest->hasDLLExportLinkage() ||
514 Dest->hasExternalWeakLinkage()) &&
515 (Src->hasExternalLinkage() ||
516 Src->hasDLLImportLinkage() ||
517 Src->hasDLLExportLinkage() ||
518 Src->hasExternalWeakLinkage()) &&
519 "Unexpected linkage type!");
520 return Error(Err, "Linking globals named '" + Src->getName() +
521 "': symbol multiply defined!");
525 if (Dest && Src->getVisibility() != Dest->getVisibility())
526 if (!Src->isDeclaration() && !Dest->isDeclaration())
527 return Error(Err, "Linking globals named '" + Src->getName() +
528 "': symbols have different visibilities!");
532 // LinkGlobals - Loop through the global variables in the src module and merge
533 // them into the dest module.
534 static bool LinkGlobals(Module *Dest, const Module *Src,
535 std::map<const Value*, Value*> &ValueMap,
536 std::multimap<std::string, GlobalVariable *> &AppendingVars,
538 ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable();
539 LLVMContext &Context = Dest->getContext();
541 // Loop over all of the globals in the src module, mapping them over as we go
542 for (Module::const_global_iterator I = Src->global_begin(),
543 E = Src->global_end(); I != E; ++I) {
544 const GlobalVariable *SGV = I;
545 GlobalValue *DGV = 0;
547 // Check to see if may have to link the global with the global, alias or
549 if (SGV->hasName() && !SGV->hasLocalLinkage())
550 DGV = cast_or_null<GlobalValue>(DestSymTab.lookup(SGV->getNameStart(),
553 // If we found a global with the same name in the dest module, but it has
554 // internal linkage, we are really not doing any linkage here.
555 if (DGV && DGV->hasLocalLinkage())
558 // If types don't agree due to opaque types, try to resolve them.
559 if (DGV && DGV->getType() != SGV->getType())
560 RecursiveResolveTypes(SGV->getType(), DGV->getType());
562 assert((SGV->hasInitializer() || SGV->hasExternalWeakLinkage() ||
563 SGV->hasExternalLinkage() || SGV->hasDLLImportLinkage()) &&
564 "Global must either be external or have an initializer!");
566 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
567 bool LinkFromSrc = false;
568 if (GetLinkageResult(DGV, SGV, NewLinkage, LinkFromSrc, Err))
572 // No linking to be performed, simply create an identical version of the
573 // symbol over in the dest module... the initializer will be filled in
574 // later by LinkGlobalInits.
575 GlobalVariable *NewDGV =
576 new GlobalVariable(*Dest, SGV->getType()->getElementType(),
577 SGV->isConstant(), SGV->getLinkage(), /*init*/0,
578 SGV->getName(), 0, false,
579 SGV->getType()->getAddressSpace());
580 // Propagate alignment, visibility and section info.
581 CopyGVAttributes(NewDGV, SGV);
583 // If the LLVM runtime renamed the global, but it is an externally visible
584 // symbol, DGV must be an existing global with internal linkage. Rename
586 if (!NewDGV->hasLocalLinkage() && NewDGV->getName() != SGV->getName())
587 ForceRenaming(NewDGV, SGV->getName());
589 // Make sure to remember this mapping.
590 ValueMap[SGV] = NewDGV;
592 // Keep track that this is an appending variable.
593 if (SGV->hasAppendingLinkage())
594 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV));
598 // If the visibilities of the symbols disagree and the destination is a
599 // prototype, take the visibility of its input.
600 if (DGV->isDeclaration())
601 DGV->setVisibility(SGV->getVisibility());
603 if (DGV->hasAppendingLinkage()) {
604 // No linking is performed yet. Just insert a new copy of the global, and
605 // keep track of the fact that it is an appending variable in the
606 // AppendingVars map. The name is cleared out so that no linkage is
608 GlobalVariable *NewDGV =
609 new GlobalVariable(*Dest, SGV->getType()->getElementType(),
610 SGV->isConstant(), SGV->getLinkage(), /*init*/0,
612 SGV->getType()->getAddressSpace());
614 // Set alignment allowing CopyGVAttributes merge it with alignment of SGV.
615 NewDGV->setAlignment(DGV->getAlignment());
616 // Propagate alignment, section and visibility info.
617 CopyGVAttributes(NewDGV, SGV);
619 // Make sure to remember this mapping...
620 ValueMap[SGV] = NewDGV;
622 // Keep track that this is an appending variable...
623 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV));
628 if (isa<GlobalAlias>(DGV))
629 return Error(Err, "Global-Alias Collision on '" + SGV->getName() +
630 "': symbol multiple defined");
632 // If the types don't match, and if we are to link from the source, nuke
633 // DGV and create a new one of the appropriate type. Note that the thing
634 // we are replacing may be a function (if a prototype, weak, etc) or a
636 GlobalVariable *NewDGV =
637 new GlobalVariable(*Dest, SGV->getType()->getElementType(),
638 SGV->isConstant(), NewLinkage, /*init*/0,
639 DGV->getName(), 0, false,
640 SGV->getType()->getAddressSpace());
642 // Propagate alignment, section, and visibility info.
643 CopyGVAttributes(NewDGV, SGV);
644 DGV->replaceAllUsesWith(Context.getConstantExprBitCast(NewDGV,
647 // DGV will conflict with NewDGV because they both had the same
648 // name. We must erase this now so ForceRenaming doesn't assert
649 // because DGV might not have internal linkage.
650 if (GlobalVariable *Var = dyn_cast<GlobalVariable>(DGV))
651 Var->eraseFromParent();
653 cast<Function>(DGV)->eraseFromParent();
656 // If the symbol table renamed the global, but it is an externally visible
657 // symbol, DGV must be an existing global with internal linkage. Rename.
658 if (NewDGV->getName() != SGV->getName() && !NewDGV->hasLocalLinkage())
659 ForceRenaming(NewDGV, SGV->getName());
661 // Inherit const as appropriate.
662 NewDGV->setConstant(SGV->isConstant());
664 // Make sure to remember this mapping.
665 ValueMap[SGV] = NewDGV;
669 // Not "link from source", keep the one in the DestModule and remap the
672 // Special case for const propagation.
673 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV))
674 if (DGVar->isDeclaration() && SGV->isConstant() && !DGVar->isConstant())
675 DGVar->setConstant(true);
677 // SGV is global, but DGV is alias.
678 if (isa<GlobalAlias>(DGV)) {
679 // The only valid mappings are:
680 // - SGV is external declaration, which is effectively a no-op.
681 // - SGV is weak, when we just need to throw SGV out.
682 if (!SGV->isDeclaration() && !SGV->isWeakForLinker())
683 return Error(Err, "Global-Alias Collision on '" + SGV->getName() +
684 "': symbol multiple defined");
687 // Set calculated linkage
688 DGV->setLinkage(NewLinkage);
690 // Make sure to remember this mapping...
691 ValueMap[SGV] = Context.getConstantExprBitCast(DGV, SGV->getType());
696 static GlobalValue::LinkageTypes
697 CalculateAliasLinkage(const GlobalValue *SGV, const GlobalValue *DGV) {
698 GlobalValue::LinkageTypes SL = SGV->getLinkage();
699 GlobalValue::LinkageTypes DL = DGV->getLinkage();
700 if (SL == GlobalValue::ExternalLinkage || DL == GlobalValue::ExternalLinkage)
701 return GlobalValue::ExternalLinkage;
702 else if (SL == GlobalValue::WeakAnyLinkage ||
703 DL == GlobalValue::WeakAnyLinkage)
704 return GlobalValue::WeakAnyLinkage;
705 else if (SL == GlobalValue::WeakODRLinkage ||
706 DL == GlobalValue::WeakODRLinkage)
707 return GlobalValue::WeakODRLinkage;
708 else if (SL == GlobalValue::InternalLinkage &&
709 DL == GlobalValue::InternalLinkage)
710 return GlobalValue::InternalLinkage;
712 assert (SL == GlobalValue::PrivateLinkage &&
713 DL == GlobalValue::PrivateLinkage && "Unexpected linkage type");
714 return GlobalValue::PrivateLinkage;
718 // LinkAlias - Loop through the alias in the src module and link them into the
719 // dest module. We're assuming, that all functions/global variables were already
721 static bool LinkAlias(Module *Dest, const Module *Src,
722 std::map<const Value*, Value*> &ValueMap,
724 LLVMContext &Context = Dest->getContext();
726 // Loop over all alias in the src module
727 for (Module::const_alias_iterator I = Src->alias_begin(),
728 E = Src->alias_end(); I != E; ++I) {
729 const GlobalAlias *SGA = I;
730 const GlobalValue *SAliasee = SGA->getAliasedGlobal();
731 GlobalAlias *NewGA = NULL;
733 // Globals were already linked, thus we can just query ValueMap for variant
734 // of SAliasee in Dest.
735 std::map<const Value*,Value*>::const_iterator VMI = ValueMap.find(SAliasee);
736 assert(VMI != ValueMap.end() && "Aliasee not linked");
737 GlobalValue* DAliasee = cast<GlobalValue>(VMI->second);
738 GlobalValue* DGV = NULL;
740 // Try to find something 'similar' to SGA in destination module.
741 if (!DGV && !SGA->hasLocalLinkage()) {
742 DGV = Dest->getNamedAlias(SGA->getName());
744 // If types don't agree due to opaque types, try to resolve them.
745 if (DGV && DGV->getType() != SGA->getType())
746 RecursiveResolveTypes(SGA->getType(), DGV->getType());
749 if (!DGV && !SGA->hasLocalLinkage()) {
750 DGV = Dest->getGlobalVariable(SGA->getName());
752 // If types don't agree due to opaque types, try to resolve them.
753 if (DGV && DGV->getType() != SGA->getType())
754 RecursiveResolveTypes(SGA->getType(), DGV->getType());
757 if (!DGV && !SGA->hasLocalLinkage()) {
758 DGV = Dest->getFunction(SGA->getName());
760 // If types don't agree due to opaque types, try to resolve them.
761 if (DGV && DGV->getType() != SGA->getType())
762 RecursiveResolveTypes(SGA->getType(), DGV->getType());
765 // No linking to be performed on internal stuff.
766 if (DGV && DGV->hasLocalLinkage())
769 if (GlobalAlias *DGA = dyn_cast_or_null<GlobalAlias>(DGV)) {
770 // Types are known to be the same, check whether aliasees equal. As
771 // globals are already linked we just need query ValueMap to find the
773 if (DAliasee == DGA->getAliasedGlobal()) {
774 // This is just two copies of the same alias. Propagate linkage, if
776 DGA->setLinkage(CalculateAliasLinkage(SGA, DGA));
779 // Proceed to 'common' steps
781 return Error(Err, "Alias Collision on '" + SGA->getName()+
782 "': aliases have different aliasees");
783 } else if (GlobalVariable *DGVar = dyn_cast_or_null<GlobalVariable>(DGV)) {
784 // The only allowed way is to link alias with external declaration or weak
786 if (DGVar->isDeclaration() || DGVar->isWeakForLinker()) {
787 // But only if aliasee is global too...
788 if (!isa<GlobalVariable>(DAliasee))
789 return Error(Err, "Global-Alias Collision on '" + SGA->getName() +
790 "': aliasee is not global variable");
792 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(),
793 SGA->getName(), DAliasee, Dest);
794 CopyGVAttributes(NewGA, SGA);
796 // Any uses of DGV need to change to NewGA, with cast, if needed.
797 if (SGA->getType() != DGVar->getType())
798 DGVar->replaceAllUsesWith(Context.getConstantExprBitCast(NewGA,
801 DGVar->replaceAllUsesWith(NewGA);
803 // DGVar will conflict with NewGA because they both had the same
804 // name. We must erase this now so ForceRenaming doesn't assert
805 // because DGV might not have internal linkage.
806 DGVar->eraseFromParent();
808 // Proceed to 'common' steps
810 return Error(Err, "Global-Alias Collision on '" + SGA->getName() +
811 "': symbol multiple defined");
812 } else if (Function *DF = dyn_cast_or_null<Function>(DGV)) {
813 // The only allowed way is to link alias with external declaration or weak
815 if (DF->isDeclaration() || DF->isWeakForLinker()) {
816 // But only if aliasee is function too...
817 if (!isa<Function>(DAliasee))
818 return Error(Err, "Function-Alias Collision on '" + SGA->getName() +
819 "': aliasee is not function");
821 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(),
822 SGA->getName(), DAliasee, Dest);
823 CopyGVAttributes(NewGA, SGA);
825 // Any uses of DF need to change to NewGA, with cast, if needed.
826 if (SGA->getType() != DF->getType())
827 DF->replaceAllUsesWith(Context.getConstantExprBitCast(NewGA,
830 DF->replaceAllUsesWith(NewGA);
832 // DF will conflict with NewGA because they both had the same
833 // name. We must erase this now so ForceRenaming doesn't assert
834 // because DF might not have internal linkage.
835 DF->eraseFromParent();
837 // Proceed to 'common' steps
839 return Error(Err, "Function-Alias Collision on '" + SGA->getName() +
840 "': symbol multiple defined");
842 // No linking to be performed, simply create an identical version of the
843 // alias over in the dest module...
845 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(),
846 SGA->getName(), DAliasee, Dest);
847 CopyGVAttributes(NewGA, SGA);
849 // Proceed to 'common' steps
852 assert(NewGA && "No alias was created in destination module!");
854 // If the symbol table renamed the alias, but it is an externally visible
855 // symbol, DGA must be an global value with internal linkage. Rename it.
856 if (NewGA->getName() != SGA->getName() &&
857 !NewGA->hasLocalLinkage())
858 ForceRenaming(NewGA, SGA->getName());
860 // Remember this mapping so uses in the source module get remapped
861 // later by RemapOperand.
862 ValueMap[SGA] = NewGA;
869 // LinkGlobalInits - Update the initializers in the Dest module now that all
870 // globals that may be referenced are in Dest.
871 static bool LinkGlobalInits(Module *Dest, const Module *Src,
872 std::map<const Value*, Value*> &ValueMap,
874 // Loop over all of the globals in the src module, mapping them over as we go
875 for (Module::const_global_iterator I = Src->global_begin(),
876 E = Src->global_end(); I != E; ++I) {
877 const GlobalVariable *SGV = I;
879 if (SGV->hasInitializer()) { // Only process initialized GV's
880 // Figure out what the initializer looks like in the dest module...
882 cast<Constant>(RemapOperand(SGV->getInitializer(), ValueMap,
883 Dest->getContext()));
884 // Grab destination global variable or alias.
885 GlobalValue *DGV = cast<GlobalValue>(ValueMap[SGV]->stripPointerCasts());
887 // If dest if global variable, check that initializers match.
888 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) {
889 if (DGVar->hasInitializer()) {
890 if (SGV->hasExternalLinkage()) {
891 if (DGVar->getInitializer() != SInit)
892 return Error(Err, "Global Variable Collision on '" +
894 "': global variables have different initializers");
895 } else if (DGVar->isWeakForLinker()) {
896 // Nothing is required, mapped values will take the new global
898 } else if (SGV->isWeakForLinker()) {
899 // Nothing is required, mapped values will take the new global
901 } else if (DGVar->hasAppendingLinkage()) {
902 assert(0 && "Appending linkage unimplemented!");
904 assert(0 && "Unknown linkage!");
907 // Copy the initializer over now...
908 DGVar->setInitializer(SInit);
911 // Destination is alias, the only valid situation is when source is
912 // weak. Also, note, that we already checked linkage in LinkGlobals(),
913 // thus we assert here.
914 // FIXME: Should we weaken this assumption, 'dereference' alias and
915 // check for initializer of aliasee?
916 assert(SGV->isWeakForLinker());
923 // LinkFunctionProtos - Link the functions together between the two modules,
924 // without doing function bodies... this just adds external function prototypes
925 // to the Dest function...
927 static bool LinkFunctionProtos(Module *Dest, const Module *Src,
928 std::map<const Value*, Value*> &ValueMap,
930 ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable();
931 LLVMContext &Context = Dest->getContext();
933 // Loop over all of the functions in the src module, mapping them over
934 for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) {
935 const Function *SF = I; // SrcFunction
936 GlobalValue *DGV = 0;
938 // Check to see if may have to link the function with the global, alias or
940 if (SF->hasName() && !SF->hasLocalLinkage())
941 DGV = cast_or_null<GlobalValue>(DestSymTab.lookup(SF->getNameStart(),
944 // If we found a global with the same name in the dest module, but it has
945 // internal linkage, we are really not doing any linkage here.
946 if (DGV && DGV->hasLocalLinkage())
949 // If types don't agree due to opaque types, try to resolve them.
950 if (DGV && DGV->getType() != SF->getType())
951 RecursiveResolveTypes(SF->getType(), DGV->getType());
953 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
954 bool LinkFromSrc = false;
955 if (GetLinkageResult(DGV, SF, NewLinkage, LinkFromSrc, Err))
958 // If there is no linkage to be performed, just bring over SF without
961 // Function does not already exist, simply insert an function signature
962 // identical to SF into the dest module.
963 Function *NewDF = Function::Create(SF->getFunctionType(),
965 SF->getName(), Dest);
966 CopyGVAttributes(NewDF, SF);
968 // If the LLVM runtime renamed the function, but it is an externally
969 // visible symbol, DF must be an existing function with internal linkage.
971 if (!NewDF->hasLocalLinkage() && NewDF->getName() != SF->getName())
972 ForceRenaming(NewDF, SF->getName());
974 // ... and remember this mapping...
975 ValueMap[SF] = NewDF;
979 // If the visibilities of the symbols disagree and the destination is a
980 // prototype, take the visibility of its input.
981 if (DGV->isDeclaration())
982 DGV->setVisibility(SF->getVisibility());
985 if (isa<GlobalAlias>(DGV))
986 return Error(Err, "Function-Alias Collision on '" + SF->getName() +
987 "': symbol multiple defined");
989 // We have a definition of the same name but different type in the
990 // source module. Copy the prototype to the destination and replace
991 // uses of the destination's prototype with the new prototype.
992 Function *NewDF = Function::Create(SF->getFunctionType(), NewLinkage,
993 SF->getName(), Dest);
994 CopyGVAttributes(NewDF, SF);
996 // Any uses of DF need to change to NewDF, with cast
997 DGV->replaceAllUsesWith(Context.getConstantExprBitCast(NewDF,
1000 // DF will conflict with NewDF because they both had the same. We must
1001 // erase this now so ForceRenaming doesn't assert because DF might
1002 // not have internal linkage.
1003 if (GlobalVariable *Var = dyn_cast<GlobalVariable>(DGV))
1004 Var->eraseFromParent();
1006 cast<Function>(DGV)->eraseFromParent();
1008 // If the symbol table renamed the function, but it is an externally
1009 // visible symbol, DF must be an existing function with internal
1010 // linkage. Rename it.
1011 if (NewDF->getName() != SF->getName() && !NewDF->hasLocalLinkage())
1012 ForceRenaming(NewDF, SF->getName());
1014 // Remember this mapping so uses in the source module get remapped
1015 // later by RemapOperand.
1016 ValueMap[SF] = NewDF;
1020 // Not "link from source", keep the one in the DestModule and remap the
1023 if (isa<GlobalAlias>(DGV)) {
1024 // The only valid mappings are:
1025 // - SF is external declaration, which is effectively a no-op.
1026 // - SF is weak, when we just need to throw SF out.
1027 if (!SF->isDeclaration() && !SF->isWeakForLinker())
1028 return Error(Err, "Function-Alias Collision on '" + SF->getName() +
1029 "': symbol multiple defined");
1032 // Set calculated linkage
1033 DGV->setLinkage(NewLinkage);
1035 // Make sure to remember this mapping.
1036 ValueMap[SF] = Context.getConstantExprBitCast(DGV, SF->getType());
1041 // LinkFunctionBody - Copy the source function over into the dest function and
1042 // fix up references to values. At this point we know that Dest is an external
1043 // function, and that Src is not.
1044 static bool LinkFunctionBody(Function *Dest, Function *Src,
1045 std::map<const Value*, Value*> &ValueMap,
1047 assert(Src && Dest && Dest->isDeclaration() && !Src->isDeclaration());
1049 // Go through and convert function arguments over, remembering the mapping.
1050 Function::arg_iterator DI = Dest->arg_begin();
1051 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1052 I != E; ++I, ++DI) {
1053 DI->setName(I->getName()); // Copy the name information over...
1055 // Add a mapping to our local map
1059 // Splice the body of the source function into the dest function.
1060 Dest->getBasicBlockList().splice(Dest->end(), Src->getBasicBlockList());
1062 // At this point, all of the instructions and values of the function are now
1063 // copied over. The only problem is that they are still referencing values in
1064 // the Source function as operands. Loop through all of the operands of the
1065 // functions and patch them up to point to the local versions...
1067 for (Function::iterator BB = Dest->begin(), BE = Dest->end(); BB != BE; ++BB)
1068 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
1069 for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end();
1071 if (!isa<Instruction>(*OI) && !isa<BasicBlock>(*OI))
1072 *OI = RemapOperand(*OI, ValueMap, *Dest->getContext());
1074 // There is no need to map the arguments anymore.
1075 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1083 // LinkFunctionBodies - Link in the function bodies that are defined in the
1084 // source module into the DestModule. This consists basically of copying the
1085 // function over and fixing up references to values.
1086 static bool LinkFunctionBodies(Module *Dest, Module *Src,
1087 std::map<const Value*, Value*> &ValueMap,
1090 // Loop over all of the functions in the src module, mapping them over as we
1092 for (Module::iterator SF = Src->begin(), E = Src->end(); SF != E; ++SF) {
1093 if (!SF->isDeclaration()) { // No body if function is external
1094 Function *DF = dyn_cast<Function>(ValueMap[SF]); // Destination function
1096 // DF not external SF external?
1097 if (DF && DF->isDeclaration())
1098 // Only provide the function body if there isn't one already.
1099 if (LinkFunctionBody(DF, SF, ValueMap, Err))
1106 // LinkAppendingVars - If there were any appending global variables, link them
1107 // together now. Return true on error.
1108 static bool LinkAppendingVars(Module *M,
1109 std::multimap<std::string, GlobalVariable *> &AppendingVars,
1110 std::string *ErrorMsg) {
1111 if (AppendingVars.empty()) return false; // Nothing to do.
1113 LLVMContext &Context = M->getContext();
1115 // Loop over the multimap of appending vars, processing any variables with the
1116 // same name, forming a new appending global variable with both of the
1117 // initializers merged together, then rewrite references to the old variables
1119 std::vector<Constant*> Inits;
1120 while (AppendingVars.size() > 1) {
1121 // Get the first two elements in the map...
1122 std::multimap<std::string,
1123 GlobalVariable*>::iterator Second = AppendingVars.begin(), First=Second++;
1125 // If the first two elements are for different names, there is no pair...
1126 // Otherwise there is a pair, so link them together...
1127 if (First->first == Second->first) {
1128 GlobalVariable *G1 = First->second, *G2 = Second->second;
1129 const ArrayType *T1 = cast<ArrayType>(G1->getType()->getElementType());
1130 const ArrayType *T2 = cast<ArrayType>(G2->getType()->getElementType());
1132 // Check to see that they two arrays agree on type...
1133 if (T1->getElementType() != T2->getElementType())
1134 return Error(ErrorMsg,
1135 "Appending variables with different element types need to be linked!");
1136 if (G1->isConstant() != G2->isConstant())
1137 return Error(ErrorMsg,
1138 "Appending variables linked with different const'ness!");
1140 if (G1->getAlignment() != G2->getAlignment())
1141 return Error(ErrorMsg,
1142 "Appending variables with different alignment need to be linked!");
1144 if (G1->getVisibility() != G2->getVisibility())
1145 return Error(ErrorMsg,
1146 "Appending variables with different visibility need to be linked!");
1148 if (G1->getSection() != G2->getSection())
1149 return Error(ErrorMsg,
1150 "Appending variables with different section name need to be linked!");
1152 unsigned NewSize = T1->getNumElements() + T2->getNumElements();
1153 ArrayType *NewType = Context.getArrayType(T1->getElementType(),
1156 G1->setName(""); // Clear G1's name in case of a conflict!
1158 // Create the new global variable...
1159 GlobalVariable *NG =
1160 new GlobalVariable(*M, NewType, G1->isConstant(), G1->getLinkage(),
1161 /*init*/0, First->first, 0, G1->isThreadLocal(),
1162 G1->getType()->getAddressSpace());
1164 // Propagate alignment, visibility and section info.
1165 CopyGVAttributes(NG, G1);
1167 // Merge the initializer...
1168 Inits.reserve(NewSize);
1169 if (ConstantArray *I = dyn_cast<ConstantArray>(G1->getInitializer())) {
1170 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i)
1171 Inits.push_back(I->getOperand(i));
1173 assert(isa<ConstantAggregateZero>(G1->getInitializer()));
1174 Constant *CV = Context.getNullValue(T1->getElementType());
1175 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i)
1176 Inits.push_back(CV);
1178 if (ConstantArray *I = dyn_cast<ConstantArray>(G2->getInitializer())) {
1179 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i)
1180 Inits.push_back(I->getOperand(i));
1182 assert(isa<ConstantAggregateZero>(G2->getInitializer()));
1183 Constant *CV = Context.getNullValue(T2->getElementType());
1184 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i)
1185 Inits.push_back(CV);
1187 NG->setInitializer(Context.getConstantArray(NewType, Inits));
1190 // Replace any uses of the two global variables with uses of the new
1193 // FIXME: This should rewrite simple/straight-forward uses such as
1194 // getelementptr instructions to not use the Cast!
1195 G1->replaceAllUsesWith(Context.getConstantExprBitCast(NG,
1197 G2->replaceAllUsesWith(Context.getConstantExprBitCast(NG,
1200 // Remove the two globals from the module now...
1201 M->getGlobalList().erase(G1);
1202 M->getGlobalList().erase(G2);
1204 // Put the new global into the AppendingVars map so that we can handle
1205 // linking of more than two vars...
1206 Second->second = NG;
1208 AppendingVars.erase(First);
1214 static bool ResolveAliases(Module *Dest) {
1215 for (Module::alias_iterator I = Dest->alias_begin(), E = Dest->alias_end();
1217 if (const GlobalValue *GV = I->resolveAliasedGlobal())
1218 if (GV != I && !GV->isDeclaration())
1219 I->replaceAllUsesWith(const_cast<GlobalValue*>(GV));
1224 // LinkModules - This function links two modules together, with the resulting
1225 // left module modified to be the composite of the two input modules. If an
1226 // error occurs, true is returned and ErrorMsg (if not null) is set to indicate
1227 // the problem. Upon failure, the Dest module could be in a modified state, and
1228 // shouldn't be relied on to be consistent.
1230 Linker::LinkModules(Module *Dest, Module *Src, std::string *ErrorMsg) {
1231 assert(Dest != 0 && "Invalid Destination module");
1232 assert(Src != 0 && "Invalid Source Module");
1234 if (Dest->getDataLayout().empty()) {
1235 if (!Src->getDataLayout().empty()) {
1236 Dest->setDataLayout(Src->getDataLayout());
1238 std::string DataLayout;
1240 if (Dest->getEndianness() == Module::AnyEndianness) {
1241 if (Src->getEndianness() == Module::BigEndian)
1242 DataLayout.append("E");
1243 else if (Src->getEndianness() == Module::LittleEndian)
1244 DataLayout.append("e");
1247 if (Dest->getPointerSize() == Module::AnyPointerSize) {
1248 if (Src->getPointerSize() == Module::Pointer64)
1249 DataLayout.append(DataLayout.length() == 0 ? "p:64:64" : "-p:64:64");
1250 else if (Src->getPointerSize() == Module::Pointer32)
1251 DataLayout.append(DataLayout.length() == 0 ? "p:32:32" : "-p:32:32");
1253 Dest->setDataLayout(DataLayout);
1257 // Copy the target triple from the source to dest if the dest's is empty.
1258 if (Dest->getTargetTriple().empty() && !Src->getTargetTriple().empty())
1259 Dest->setTargetTriple(Src->getTargetTriple());
1261 if (!Src->getDataLayout().empty() && !Dest->getDataLayout().empty() &&
1262 Src->getDataLayout() != Dest->getDataLayout())
1263 cerr << "WARNING: Linking two modules of different data layouts!\n";
1264 if (!Src->getTargetTriple().empty() &&
1265 Dest->getTargetTriple() != Src->getTargetTriple())
1266 cerr << "WARNING: Linking two modules of different target triples!\n";
1268 // Append the module inline asm string.
1269 if (!Src->getModuleInlineAsm().empty()) {
1270 if (Dest->getModuleInlineAsm().empty())
1271 Dest->setModuleInlineAsm(Src->getModuleInlineAsm());
1273 Dest->setModuleInlineAsm(Dest->getModuleInlineAsm()+"\n"+
1274 Src->getModuleInlineAsm());
1277 // Update the destination module's dependent libraries list with the libraries
1278 // from the source module. There's no opportunity for duplicates here as the
1279 // Module ensures that duplicate insertions are discarded.
1280 for (Module::lib_iterator SI = Src->lib_begin(), SE = Src->lib_end();
1282 Dest->addLibrary(*SI);
1284 // LinkTypes - Go through the symbol table of the Src module and see if any
1285 // types are named in the src module that are not named in the Dst module.
1286 // Make sure there are no type name conflicts.
1287 if (LinkTypes(Dest, Src, ErrorMsg))
1290 // ValueMap - Mapping of values from what they used to be in Src, to what they
1292 std::map<const Value*, Value*> ValueMap;
1294 // AppendingVars - Keep track of global variables in the destination module
1295 // with appending linkage. After the module is linked together, they are
1296 // appended and the module is rewritten.
1297 std::multimap<std::string, GlobalVariable *> AppendingVars;
1298 for (Module::global_iterator I = Dest->global_begin(), E = Dest->global_end();
1300 // Add all of the appending globals already in the Dest module to
1302 if (I->hasAppendingLinkage())
1303 AppendingVars.insert(std::make_pair(I->getName(), I));
1306 // Insert all of the globals in src into the Dest module... without linking
1307 // initializers (which could refer to functions not yet mapped over).
1308 if (LinkGlobals(Dest, Src, ValueMap, AppendingVars, ErrorMsg))
1311 // Link the functions together between the two modules, without doing function
1312 // bodies... this just adds external function prototypes to the Dest
1313 // function... We do this so that when we begin processing function bodies,
1314 // all of the global values that may be referenced are available in our
1316 if (LinkFunctionProtos(Dest, Src, ValueMap, ErrorMsg))
1319 // If there were any alias, link them now. We really need to do this now,
1320 // because all of the aliases that may be referenced need to be available in
1322 if (LinkAlias(Dest, Src, ValueMap, ErrorMsg)) return true;
1324 // Update the initializers in the Dest module now that all globals that may
1325 // be referenced are in Dest.
1326 if (LinkGlobalInits(Dest, Src, ValueMap, ErrorMsg)) return true;
1328 // Link in the function bodies that are defined in the source module into the
1329 // DestModule. This consists basically of copying the function over and
1330 // fixing up references to values.
1331 if (LinkFunctionBodies(Dest, Src, ValueMap, ErrorMsg)) return true;
1333 // If there were any appending global variables, link them together now.
1334 if (LinkAppendingVars(Dest, AppendingVars, ErrorMsg)) return true;
1336 // Resolve all uses of aliases with aliasees
1337 if (ResolveAliases(Dest)) return true;
1339 // If the source library's module id is in the dependent library list of the
1340 // destination library, remove it since that module is now linked in.
1342 modId.set(Src->getModuleIdentifier());
1343 if (!modId.isEmpty())
1344 Dest->removeLibrary(modId.getBasename());