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/Module.h"
23 #include "llvm/TypeSymbolTable.h"
24 #include "llvm/ValueSymbolTable.h"
25 #include "llvm/Instructions.h"
26 #include "llvm/Assembly/Writer.h"
27 #include "llvm/Support/Streams.h"
28 #include "llvm/System/Path.h"
32 // Error - Simple wrapper function to conditionally assign to E and return true.
33 // This just makes error return conditions a little bit simpler...
34 static inline bool Error(std::string *E, const std::string &Message) {
39 // ToStr - Simple wrapper function to convert a type to a string.
40 static std::string ToStr(const Type *Ty, const Module *M) {
41 std::ostringstream OS;
42 WriteTypeSymbolic(OS, Ty, M);
47 // Function: ResolveTypes()
50 // Attempt to link the two specified types together.
53 // DestTy - The type to which we wish to resolve.
54 // SrcTy - The original type which we want to resolve.
55 // Name - The name of the type.
58 // DestST - The symbol table in which the new type should be placed.
61 // true - There is an error and the types cannot yet be linked.
64 static bool ResolveTypes(const Type *DestTy, const Type *SrcTy,
65 TypeSymbolTable *DestST, const std::string &Name) {
66 if (DestTy == SrcTy) return false; // If already equal, noop
68 // Does the type already exist in the module?
69 if (DestTy && !isa<OpaqueType>(DestTy)) { // Yup, the type already exists...
70 if (const OpaqueType *OT = dyn_cast<OpaqueType>(SrcTy)) {
71 const_cast<OpaqueType*>(OT)->refineAbstractTypeTo(DestTy);
73 return true; // Cannot link types... neither is opaque and not-equal
75 } else { // Type not in dest module. Add it now.
76 if (DestTy) // Type _is_ in module, just opaque...
77 const_cast<OpaqueType*>(cast<OpaqueType>(DestTy))
78 ->refineAbstractTypeTo(SrcTy);
79 else if (!Name.empty())
80 DestST->insert(Name, const_cast<Type*>(SrcTy));
85 static const FunctionType *getFT(const PATypeHolder &TH) {
86 return cast<FunctionType>(TH.get());
88 static const StructType *getST(const PATypeHolder &TH) {
89 return cast<StructType>(TH.get());
92 // RecursiveResolveTypes - This is just like ResolveTypes, except that it
93 // recurses down into derived types, merging the used types if the parent types
95 static bool RecursiveResolveTypesI(const PATypeHolder &DestTy,
96 const PATypeHolder &SrcTy,
97 TypeSymbolTable *DestST,
98 const std::string &Name,
99 std::vector<std::pair<PATypeHolder, PATypeHolder> > &Pointers) {
100 const Type *SrcTyT = SrcTy.get();
101 const Type *DestTyT = DestTy.get();
102 if (DestTyT == SrcTyT) return false; // If already equal, noop
104 // If we found our opaque type, resolve it now!
105 if (isa<OpaqueType>(DestTyT) || isa<OpaqueType>(SrcTyT))
106 return ResolveTypes(DestTyT, SrcTyT, DestST, Name);
108 // Two types cannot be resolved together if they are of different primitive
109 // type. For example, we cannot resolve an int to a float.
110 if (DestTyT->getTypeID() != SrcTyT->getTypeID()) return true;
112 // Otherwise, resolve the used type used by this derived type...
113 switch (DestTyT->getTypeID()) {
114 case Type::IntegerTyID: {
115 if (cast<IntegerType>(DestTyT)->getBitWidth() !=
116 cast<IntegerType>(SrcTyT)->getBitWidth())
120 case Type::FunctionTyID: {
121 if (cast<FunctionType>(DestTyT)->isVarArg() !=
122 cast<FunctionType>(SrcTyT)->isVarArg() ||
123 cast<FunctionType>(DestTyT)->getNumContainedTypes() !=
124 cast<FunctionType>(SrcTyT)->getNumContainedTypes())
126 for (unsigned i = 0, e = getFT(DestTy)->getNumContainedTypes(); i != e; ++i)
127 if (RecursiveResolveTypesI(getFT(DestTy)->getContainedType(i),
128 getFT(SrcTy)->getContainedType(i), DestST, "",
133 case Type::StructTyID: {
134 if (getST(DestTy)->getNumContainedTypes() !=
135 getST(SrcTy)->getNumContainedTypes()) return 1;
136 for (unsigned i = 0, e = getST(DestTy)->getNumContainedTypes(); i != e; ++i)
137 if (RecursiveResolveTypesI(getST(DestTy)->getContainedType(i),
138 getST(SrcTy)->getContainedType(i), DestST, "",
143 case Type::ArrayTyID: {
144 const ArrayType *DAT = cast<ArrayType>(DestTy.get());
145 const ArrayType *SAT = cast<ArrayType>(SrcTy.get());
146 if (DAT->getNumElements() != SAT->getNumElements()) return true;
147 return RecursiveResolveTypesI(DAT->getElementType(), SAT->getElementType(),
148 DestST, "", Pointers);
150 case Type::PointerTyID: {
151 // If this is a pointer type, check to see if we have already seen it. If
152 // so, we are in a recursive branch. Cut off the search now. We cannot use
153 // an associative container for this search, because the type pointers (keys
154 // in the container) change whenever types get resolved...
155 for (unsigned i = 0, e = Pointers.size(); i != e; ++i)
156 if (Pointers[i].first == DestTy)
157 return Pointers[i].second != SrcTy;
159 // Otherwise, add the current pointers to the vector to stop recursion on
161 Pointers.push_back(std::make_pair(DestTyT, SrcTyT));
163 RecursiveResolveTypesI(cast<PointerType>(DestTy.get())->getElementType(),
164 cast<PointerType>(SrcTy.get())->getElementType(),
165 DestST, "", Pointers);
169 default: assert(0 && "Unexpected type!"); return true;
173 static bool RecursiveResolveTypes(const PATypeHolder &DestTy,
174 const PATypeHolder &SrcTy,
175 TypeSymbolTable *DestST,
176 const std::string &Name){
177 std::vector<std::pair<PATypeHolder, PATypeHolder> > PointerTypes;
178 return RecursiveResolveTypesI(DestTy, SrcTy, DestST, Name, PointerTypes);
182 // LinkTypes - Go through the symbol table of the Src module and see if any
183 // types are named in the src module that are not named in the Dst module.
184 // Make sure there are no type name conflicts.
185 static bool LinkTypes(Module *Dest, const Module *Src, std::string *Err) {
186 TypeSymbolTable *DestST = &Dest->getTypeSymbolTable();
187 const TypeSymbolTable *SrcST = &Src->getTypeSymbolTable();
189 // Look for a type plane for Type's...
190 TypeSymbolTable::const_iterator TI = SrcST->begin();
191 TypeSymbolTable::const_iterator TE = SrcST->end();
192 if (TI == TE) return false; // No named types, do nothing.
194 // Some types cannot be resolved immediately because they depend on other
195 // types being resolved to each other first. This contains a list of types we
196 // are waiting to recheck.
197 std::vector<std::string> DelayedTypesToResolve;
199 for ( ; TI != TE; ++TI ) {
200 const std::string &Name = TI->first;
201 const Type *RHS = TI->second;
203 // Check to see if this type name is already in the dest module...
204 Type *Entry = DestST->lookup(Name);
206 if (ResolveTypes(Entry, RHS, DestST, Name)) {
207 // They look different, save the types 'till later to resolve.
208 DelayedTypesToResolve.push_back(Name);
212 // Iteratively resolve types while we can...
213 while (!DelayedTypesToResolve.empty()) {
214 // Loop over all of the types, attempting to resolve them if possible...
215 unsigned OldSize = DelayedTypesToResolve.size();
217 // Try direct resolution by name...
218 for (unsigned i = 0; i != DelayedTypesToResolve.size(); ++i) {
219 const std::string &Name = DelayedTypesToResolve[i];
220 Type *T1 = SrcST->lookup(Name);
221 Type *T2 = DestST->lookup(Name);
222 if (!ResolveTypes(T2, T1, DestST, Name)) {
223 // We are making progress!
224 DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i);
229 // Did we not eliminate any types?
230 if (DelayedTypesToResolve.size() == OldSize) {
231 // Attempt to resolve subelements of types. This allows us to merge these
232 // two types: { int* } and { opaque* }
233 for (unsigned i = 0, e = DelayedTypesToResolve.size(); i != e; ++i) {
234 const std::string &Name = DelayedTypesToResolve[i];
235 PATypeHolder T1(SrcST->lookup(Name));
236 PATypeHolder T2(DestST->lookup(Name));
238 if (!RecursiveResolveTypes(T2, T1, DestST, Name)) {
239 // We are making progress!
240 DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i);
242 // Go back to the main loop, perhaps we can resolve directly by name
248 // If we STILL cannot resolve the types, then there is something wrong.
249 if (DelayedTypesToResolve.size() == OldSize) {
250 // Remove the symbol name from the destination.
251 DelayedTypesToResolve.pop_back();
260 static void PrintMap(const std::map<const Value*, Value*> &M) {
261 for (std::map<const Value*, Value*>::const_iterator I = M.begin(), E =M.end();
263 cerr << " Fr: " << (void*)I->first << " ";
265 cerr << " To: " << (void*)I->second << " ";
272 // RemapOperand - Use ValueMap to convert constants from one module to another.
273 static Value *RemapOperand(const Value *In,
274 std::map<const Value*, Value*> &ValueMap) {
275 std::map<const Value*,Value*>::const_iterator I = ValueMap.find(In);
276 if (I != ValueMap.end())
279 // Check to see if it's a constant that we are interested in transforming.
281 if (const Constant *CPV = dyn_cast<Constant>(In)) {
282 if ((!isa<DerivedType>(CPV->getType()) && !isa<ConstantExpr>(CPV)) ||
283 isa<ConstantInt>(CPV) || isa<ConstantAggregateZero>(CPV))
284 return const_cast<Constant*>(CPV); // Simple constants stay identical.
286 if (const ConstantArray *CPA = dyn_cast<ConstantArray>(CPV)) {
287 std::vector<Constant*> Operands(CPA->getNumOperands());
288 for (unsigned i = 0, e = CPA->getNumOperands(); i != e; ++i)
289 Operands[i] =cast<Constant>(RemapOperand(CPA->getOperand(i), ValueMap));
290 Result = ConstantArray::get(cast<ArrayType>(CPA->getType()), Operands);
291 } else if (const ConstantStruct *CPS = dyn_cast<ConstantStruct>(CPV)) {
292 std::vector<Constant*> Operands(CPS->getNumOperands());
293 for (unsigned i = 0, e = CPS->getNumOperands(); i != e; ++i)
294 Operands[i] =cast<Constant>(RemapOperand(CPS->getOperand(i), ValueMap));
295 Result = ConstantStruct::get(cast<StructType>(CPS->getType()), Operands);
296 } else if (isa<ConstantPointerNull>(CPV) || isa<UndefValue>(CPV)) {
297 Result = const_cast<Constant*>(CPV);
298 } else if (const ConstantVector *CP = dyn_cast<ConstantVector>(CPV)) {
299 std::vector<Constant*> Operands(CP->getNumOperands());
300 for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i)
301 Operands[i] = cast<Constant>(RemapOperand(CP->getOperand(i), ValueMap));
302 Result = ConstantVector::get(Operands);
303 } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CPV)) {
304 std::vector<Constant*> Ops;
305 for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i)
306 Ops.push_back(cast<Constant>(RemapOperand(CE->getOperand(i),ValueMap)));
307 Result = CE->getWithOperands(Ops);
308 } else if (isa<GlobalValue>(CPV)) {
309 assert(0 && "Unmapped global?");
311 assert(0 && "Unknown type of derived type constant value!");
313 } else if (isa<InlineAsm>(In)) {
314 Result = const_cast<Value*>(In);
317 // Cache the mapping in our local map structure
319 ValueMap[In] = Result;
324 cerr << "LinkModules ValueMap: \n";
327 cerr << "Couldn't remap value: " << (void*)In << " " << *In << "\n";
328 assert(0 && "Couldn't remap value!");
332 /// ForceRenaming - The LLVM SymbolTable class autorenames globals that conflict
333 /// in the symbol table. This is good for all clients except for us. Go
334 /// through the trouble to force this back.
335 static void ForceRenaming(GlobalValue *GV, const std::string &Name) {
336 assert(GV->getName() != Name && "Can't force rename to self");
337 ValueSymbolTable &ST = GV->getParent()->getValueSymbolTable();
339 // If there is a conflict, rename the conflict.
340 if (GlobalValue *ConflictGV = cast_or_null<GlobalValue>(ST.lookup(Name))) {
341 assert(ConflictGV->hasInternalLinkage() &&
342 "Not conflicting with a static global, should link instead!");
343 GV->takeName(ConflictGV);
344 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
345 assert(ConflictGV->getName() != Name && "ForceRenaming didn't work");
347 GV->setName(Name); // Force the name back
351 /// CopyGVAttributes - copy additional attributes (those not needed to construct
352 /// a GlobalValue) from the SrcGV to the DestGV.
353 static void CopyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) {
354 // Use the maximum alignment, rather than just copying the alignment of SrcGV.
355 unsigned Alignment = std::max(DestGV->getAlignment(), SrcGV->getAlignment());
356 DestGV->copyAttributesFrom(SrcGV);
357 DestGV->setAlignment(Alignment);
360 /// GetLinkageResult - This analyzes the two global values and determines what
361 /// the result will look like in the destination module. In particular, it
362 /// computes the resultant linkage type, computes whether the global in the
363 /// source should be copied over to the destination (replacing the existing
364 /// one), and computes whether this linkage is an error or not. It also performs
365 /// visibility checks: we cannot link together two symbols with different
367 static bool GetLinkageResult(GlobalValue *Dest, const GlobalValue *Src,
368 GlobalValue::LinkageTypes <, bool &LinkFromSrc,
370 assert((!Dest || !Src->hasInternalLinkage()) &&
371 "If Src has internal linkage, Dest shouldn't be set!");
373 // Linking something to nothing.
375 LT = Src->getLinkage();
376 } else if (Src->isDeclaration()) {
377 // If Src is external or if both Src & Dest are external.. Just link the
378 // external globals, we aren't adding anything.
379 if (Src->hasDLLImportLinkage()) {
380 // If one of GVs has DLLImport linkage, result should be dllimport'ed.
381 if (Dest->isDeclaration()) {
383 LT = Src->getLinkage();
385 } else if (Dest->hasExternalWeakLinkage()) {
386 //If the Dest is weak, use the source linkage
388 LT = Src->getLinkage();
391 LT = Dest->getLinkage();
393 } else if (Dest->isDeclaration() && !Dest->hasDLLImportLinkage()) {
394 // If Dest is external but Src is not:
396 LT = Src->getLinkage();
397 } else if (Src->hasAppendingLinkage() || Dest->hasAppendingLinkage()) {
398 if (Src->getLinkage() != Dest->getLinkage())
399 return Error(Err, "Linking globals named '" + Src->getName() +
400 "': can only link appending global with another appending global!");
401 LinkFromSrc = true; // Special cased.
402 LT = Src->getLinkage();
403 } else if (Src->hasWeakLinkage() || Src->hasLinkOnceLinkage() ||
404 Src->hasCommonLinkage()) {
405 // At this point we know that Dest has LinkOnce, External*, Weak, Common,
407 if ((Dest->hasLinkOnceLinkage() &&
408 (Src->hasWeakLinkage() || Src->hasCommonLinkage())) ||
409 Dest->hasExternalWeakLinkage()) {
411 LT = Src->getLinkage();
414 LT = Dest->getLinkage();
416 } else if (Dest->hasWeakLinkage() || Dest->hasLinkOnceLinkage() ||
417 Dest->hasCommonLinkage()) {
418 // At this point we know that Src has External* or DLL* linkage.
419 if (Src->hasExternalWeakLinkage()) {
421 LT = Dest->getLinkage();
424 LT = GlobalValue::ExternalLinkage;
427 assert((Dest->hasExternalLinkage() ||
428 Dest->hasDLLImportLinkage() ||
429 Dest->hasDLLExportLinkage() ||
430 Dest->hasExternalWeakLinkage()) &&
431 (Src->hasExternalLinkage() ||
432 Src->hasDLLImportLinkage() ||
433 Src->hasDLLExportLinkage() ||
434 Src->hasExternalWeakLinkage()) &&
435 "Unexpected linkage type!");
436 return Error(Err, "Linking globals named '" + Src->getName() +
437 "': symbol multiply defined!");
441 if (Dest && Src->getVisibility() != Dest->getVisibility())
442 if (!Src->isDeclaration() && !Dest->isDeclaration())
443 return Error(Err, "Linking globals named '" + Src->getName() +
444 "': symbols have different visibilities!");
448 // LinkGlobals - Loop through the global variables in the src module and merge
449 // them into the dest module.
450 static bool LinkGlobals(Module *Dest, const Module *Src,
451 std::map<const Value*, Value*> &ValueMap,
452 std::multimap<std::string, GlobalVariable *> &AppendingVars,
454 // Loop over all of the globals in the src module, mapping them over as we go
455 for (Module::const_global_iterator I = Src->global_begin(), E = Src->global_end();
457 const GlobalVariable *SGV = I;
458 GlobalValue *DGV = 0;
460 // Check to see if may have to link the global with the global
461 if (SGV->hasName() && !SGV->hasInternalLinkage()) {
462 DGV = Dest->getGlobalVariable(SGV->getName());
463 if (DGV && DGV->getType() != SGV->getType())
464 // If types don't agree due to opaque types, try to resolve them.
465 RecursiveResolveTypes(SGV->getType(), DGV->getType(),
466 &Dest->getTypeSymbolTable(), "");
469 // Check to see if may have to link the global with the alias
470 if (!DGV && SGV->hasName() && !SGV->hasInternalLinkage()) {
471 DGV = Dest->getNamedAlias(SGV->getName());
472 if (DGV && DGV->getType() != SGV->getType())
473 // If types don't agree due to opaque types, try to resolve them.
474 RecursiveResolveTypes(SGV->getType(), DGV->getType(),
475 &Dest->getTypeSymbolTable(), "");
478 if (DGV && DGV->hasInternalLinkage())
481 assert((SGV->hasInitializer() || SGV->hasExternalWeakLinkage() ||
482 SGV->hasExternalLinkage() || SGV->hasDLLImportLinkage()) &&
483 "Global must either be external or have an initializer!");
485 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
486 bool LinkFromSrc = false;
487 if (GetLinkageResult(DGV, SGV, NewLinkage, LinkFromSrc, Err))
491 // No linking to be performed, simply create an identical version of the
492 // symbol over in the dest module... the initializer will be filled in
493 // later by LinkGlobalInits...
494 GlobalVariable *NewDGV =
495 new GlobalVariable(SGV->getType()->getElementType(),
496 SGV->isConstant(), SGV->getLinkage(), /*init*/0,
497 SGV->getName(), Dest);
498 // Propagate alignment, visibility and section info.
499 CopyGVAttributes(NewDGV, SGV);
501 // If the LLVM runtime renamed the global, but it is an externally visible
502 // symbol, DGV must be an existing global with internal linkage. Rename
504 if (NewDGV->getName() != SGV->getName() && !NewDGV->hasInternalLinkage())
505 ForceRenaming(NewDGV, SGV->getName());
507 // Make sure to remember this mapping...
508 ValueMap[SGV] = NewDGV;
510 if (SGV->hasAppendingLinkage())
511 // Keep track that this is an appending variable...
512 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV));
513 } else if (DGV->hasAppendingLinkage()) {
514 // No linking is performed yet. Just insert a new copy of the global, and
515 // keep track of the fact that it is an appending variable in the
516 // AppendingVars map. The name is cleared out so that no linkage is
518 GlobalVariable *NewDGV =
519 new GlobalVariable(SGV->getType()->getElementType(),
520 SGV->isConstant(), SGV->getLinkage(), /*init*/0,
523 // Set alignment allowing CopyGVAttributes merge it with alignment of SGV.
524 NewDGV->setAlignment(DGV->getAlignment());
525 // Propagate alignment, section and visibility info.
526 CopyGVAttributes(NewDGV, SGV);
528 // Make sure to remember this mapping...
529 ValueMap[SGV] = NewDGV;
531 // Keep track that this is an appending variable...
532 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV));
533 } else if (GlobalAlias *DGA = dyn_cast<GlobalAlias>(DGV)) {
534 // SGV is global, but DGV is alias. The only valid mapping is when SGV is
535 // external declaration, which is effectively a no-op. Also make sure
536 // linkage calculation was correct.
537 if (SGV->isDeclaration() && !LinkFromSrc) {
538 // Make sure to remember this mapping...
541 return Error(Err, "Global-Alias Collision on '" + SGV->getName() +
542 "': symbol multiple defined");
543 } else if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) {
544 // Otherwise, perform the global-global mapping as instructed by
547 // Propagate alignment, section, and visibility info.
548 CopyGVAttributes(DGVar, SGV);
550 // If the types don't match, and if we are to link from the source, nuke
551 // DGV and create a new one of the appropriate type.
552 if (SGV->getType() != DGVar->getType()) {
553 GlobalVariable *NewDGV =
554 new GlobalVariable(SGV->getType()->getElementType(),
555 DGVar->isConstant(), DGVar->getLinkage(),
556 /*init*/0, DGVar->getName(), Dest);
557 CopyGVAttributes(NewDGV, DGVar);
558 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV,
560 // DGVar will conflict with NewDGV because they both had the same
561 // name. We must erase this now so ForceRenaming doesn't assert
562 // because DGV might not have internal linkage.
563 DGVar->eraseFromParent();
565 // If the symbol table renamed the global, but it is an externally
566 // visible symbol, DGV must be an existing global with internal
567 // linkage. Rename it.
568 if (NewDGV->getName() != SGV->getName() &&
569 !NewDGV->hasInternalLinkage())
570 ForceRenaming(NewDGV, SGV->getName());
575 // Inherit const as appropriate
576 DGVar->setConstant(SGV->isConstant());
578 // Set initializer to zero, so we can link the stuff later
579 DGVar->setInitializer(0);
581 // Special case for const propagation
582 if (DGVar->isDeclaration() && SGV->isConstant() && !DGVar->isConstant())
583 DGVar->setConstant(true);
586 // Set calculated linkage
587 DGVar->setLinkage(NewLinkage);
589 // Make sure to remember this mapping...
590 ValueMap[SGV] = ConstantExpr::getBitCast(DGVar, SGV->getType());
596 static GlobalValue::LinkageTypes
597 CalculateAliasLinkage(const GlobalValue *SGV, const GlobalValue *DGV) {
598 if (SGV->hasExternalLinkage() || DGV->hasExternalLinkage())
599 return GlobalValue::ExternalLinkage;
600 else if (SGV->hasWeakLinkage() || DGV->hasWeakLinkage())
601 return GlobalValue::WeakLinkage;
603 assert(SGV->hasInternalLinkage() && DGV->hasInternalLinkage() &&
604 "Unexpected linkage type");
605 return GlobalValue::InternalLinkage;
609 // LinkAlias - Loop through the alias in the src module and link them into the
610 // dest module. We're assuming, that all functions/global variables were already
612 static bool LinkAlias(Module *Dest, const Module *Src,
613 std::map<const Value*, Value*> &ValueMap,
615 // Loop over all alias in the src module
616 for (Module::const_alias_iterator I = Src->alias_begin(),
617 E = Src->alias_end(); I != E; ++I) {
618 const GlobalAlias *SGA = I;
619 const GlobalValue *SAliasee = SGA->getAliasedGlobal();
620 GlobalAlias *NewGA = NULL;
622 // Globals were already linked, thus we can just query ValueMap for variant
623 // of SAliasee in Dest.
624 std::map<const Value*,Value*>::const_iterator VMI = ValueMap.find(SAliasee);
625 assert(VMI != ValueMap.end() && "Aliasee not linked");
626 GlobalValue* DAliasee = cast<GlobalValue>(VMI->second);
627 GlobalValue* DGV = NULL;
629 // Try to find something 'similar' to SGA in destination module.
630 if (!DGV && !SGA->hasInternalLinkage()) {
631 DGV = Dest->getNamedAlias(SGA->getName());
633 // If types don't agree due to opaque types, try to resolve them.
634 if (DGV && DGV->getType() != SGA->getType())
635 if (RecursiveResolveTypes(SGA->getType(), DGV->getType(),
636 &Dest->getTypeSymbolTable(), ""))
637 return Error(Err, "Alias Collision on '" + SGA->getName()+
638 "': aliases have different types");
641 if (!DGV && !SGA->hasInternalLinkage()) {
642 DGV = Dest->getGlobalVariable(SGA->getName());
644 // If types don't agree due to opaque types, try to resolve them.
645 if (DGV && DGV->getType() != SGA->getType())
646 if (RecursiveResolveTypes(SGA->getType(), DGV->getType(),
647 &Dest->getTypeSymbolTable(), ""))
648 return Error(Err, "Alias Collision on '" + SGA->getName()+
649 "': aliases have different types");
652 if (!DGV && !SGA->hasInternalLinkage()) {
653 DGV = Dest->getFunction(SGA->getName());
655 // If types don't agree due to opaque types, try to resolve them.
656 if (DGV && DGV->getType() != SGA->getType())
657 if (RecursiveResolveTypes(SGA->getType(), DGV->getType(),
658 &Dest->getTypeSymbolTable(), ""))
659 return Error(Err, "Alias Collision on '" + SGA->getName()+
660 "': aliases have different types");
663 // No linking to be performed on internal stuff.
664 if (DGV && DGV->hasInternalLinkage())
667 if (GlobalAlias *DGA = dyn_cast_or_null<GlobalAlias>(DGV)) {
668 // Types are known to be the same, check whether aliasees equal. As
669 // globals are already linked we just need query ValueMap to find the
671 if (DAliasee == DGA->getAliasedGlobal()) {
672 // This is just two copies of the same alias. Propagate linkage, if
674 DGA->setLinkage(CalculateAliasLinkage(SGA, DGA));
677 // Proceed to 'common' steps
679 return Error(Err, "Alias Collision on '" + SGA->getName()+
680 "': aliases have different aliasees");
681 } else if (GlobalVariable *DGVar = dyn_cast_or_null<GlobalVariable>(DGV)) {
682 // The only allowed way is to link alias with external declaration.
683 if (DGVar->isDeclaration()) {
684 // But only if aliasee is global too...
685 if (!isa<GlobalVariable>(DAliasee))
686 return Error(Err, "Global-Alias Collision on '" + SGA->getName() +
687 "': aliasee is not global variable");
689 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(),
690 SGA->getName(), DAliasee, Dest);
691 CopyGVAttributes(NewGA, SGA);
693 // Any uses of DGV need to change to NewGA, with cast, if needed.
694 if (SGA->getType() != DGVar->getType())
695 DGVar->replaceAllUsesWith(ConstantExpr::getBitCast(NewGA,
698 DGVar->replaceAllUsesWith(NewGA);
700 // DGVar will conflict with NewGA because they both had the same
701 // name. We must erase this now so ForceRenaming doesn't assert
702 // because DGV might not have internal linkage.
703 DGVar->eraseFromParent();
705 // Proceed to 'common' steps
707 return Error(Err, "Global-Alias Collision on '" + SGA->getName() +
708 "': symbol multiple defined");
709 } else if (Function *DF = dyn_cast_or_null<Function>(DGV)) {
710 // The only allowed way is to link alias with external declaration.
711 if (DF->isDeclaration()) {
712 // But only if aliasee is function too...
713 if (!isa<Function>(DAliasee))
714 return Error(Err, "Function-Alias Collision on '" + SGA->getName() +
715 "': aliasee is not function");
717 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(),
718 SGA->getName(), DAliasee, Dest);
719 CopyGVAttributes(NewGA, SGA);
721 // Any uses of DF need to change to NewGA, with cast, if needed.
722 if (SGA->getType() != DF->getType())
723 DF->replaceAllUsesWith(ConstantExpr::getBitCast(NewGA,
726 DF->replaceAllUsesWith(NewGA);
728 // DF will conflict with NewGA because they both had the same
729 // name. We must erase this now so ForceRenaming doesn't assert
730 // because DF might not have internal linkage.
731 DF->eraseFromParent();
733 // Proceed to 'common' steps
735 return Error(Err, "Function-Alias Collision on '" + SGA->getName() +
736 "': symbol multiple defined");
738 // No linking to be performed, simply create an identical version of the
739 // alias over in the dest module...
741 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(),
742 SGA->getName(), DAliasee, Dest);
743 CopyGVAttributes(NewGA, SGA);
745 // Proceed to 'common' steps
748 assert(NewGA && "No alias was created in destination module!");
750 // If the symbol table renamed the alias, but it is an externally visible
751 // symbol, DGA must be an global value with internal linkage. Rename it.
752 if (NewGA->getName() != SGA->getName() &&
753 !NewGA->hasInternalLinkage())
754 ForceRenaming(NewGA, SGA->getName());
756 // Remember this mapping so uses in the source module get remapped
757 // later by RemapOperand.
758 ValueMap[SGA] = NewGA;
765 // LinkGlobalInits - Update the initializers in the Dest module now that all
766 // globals that may be referenced are in Dest.
767 static bool LinkGlobalInits(Module *Dest, const Module *Src,
768 std::map<const Value*, Value*> &ValueMap,
771 // Loop over all of the globals in the src module, mapping them over as we go
772 for (Module::const_global_iterator I = Src->global_begin(),
773 E = Src->global_end(); I != E; ++I) {
774 const GlobalVariable *SGV = I;
776 if (SGV->hasInitializer()) { // Only process initialized GV's
777 // Figure out what the initializer looks like in the dest module...
779 cast<Constant>(RemapOperand(SGV->getInitializer(), ValueMap));
781 GlobalVariable *DGV =
782 cast<GlobalVariable>(ValueMap[SGV]->stripPointerCasts());
783 if (DGV->hasInitializer()) {
784 if (SGV->hasExternalLinkage()) {
785 if (DGV->getInitializer() != SInit)
786 return Error(Err, "Global Variable Collision on '" + SGV->getName() +
787 "': global variables have different initializers");
788 } else if (DGV->hasLinkOnceLinkage() || DGV->hasWeakLinkage() ||
789 DGV->hasCommonLinkage()) {
790 // Nothing is required, mapped values will take the new global
792 } else if (SGV->hasLinkOnceLinkage() || SGV->hasWeakLinkage() ||
793 SGV->hasCommonLinkage()) {
794 // Nothing is required, mapped values will take the new global
796 } else if (DGV->hasAppendingLinkage()) {
797 assert(0 && "Appending linkage unimplemented!");
799 assert(0 && "Unknown linkage!");
802 // Copy the initializer over now...
803 DGV->setInitializer(SInit);
810 // LinkFunctionProtos - Link the functions together between the two modules,
811 // without doing function bodies... this just adds external function prototypes
812 // to the Dest function...
814 static bool LinkFunctionProtos(Module *Dest, const Module *Src,
815 std::map<const Value*, Value*> &ValueMap,
817 // Loop over all of the functions in the src module, mapping them over
818 for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) {
819 const Function *SF = I; // SrcFunction
823 // If this function is internal or has no name, it doesn't participate in
825 if (SF->hasName() && !SF->hasInternalLinkage()) {
826 // Check to see if may have to link the function.
827 DF = Dest->getFunction(SF->getName());
828 if (DF && DF->hasInternalLinkage())
832 // If there is no linkage to be performed, just bring over SF without
835 // Function does not already exist, simply insert an function signature
836 // identical to SF into the dest module.
837 Function *NewDF = Function::Create(SF->getFunctionType(),
839 SF->getName(), Dest);
840 CopyGVAttributes(NewDF, SF);
842 // If the LLVM runtime renamed the function, but it is an externally
843 // visible symbol, DF must be an existing function with internal linkage.
845 if (!NewDF->hasInternalLinkage() && NewDF->getName() != SF->getName())
846 ForceRenaming(NewDF, SF->getName());
848 // ... and remember this mapping...
849 ValueMap[SF] = NewDF;
854 // If types don't agree because of opaque, try to resolve them.
855 if (SF->getType() != DF->getType())
856 RecursiveResolveTypes(SF->getType(), DF->getType(),
857 &Dest->getTypeSymbolTable(), "");
859 // Check visibility, merging if a definition overrides a prototype.
860 if (SF->getVisibility() != DF->getVisibility()) {
861 // If one is a prototype, ignore its visibility. Prototypes are always
862 // overridden by the definition.
863 if (!SF->isDeclaration() && !DF->isDeclaration())
864 return Error(Err, "Linking functions named '" + SF->getName() +
865 "': symbols have different visibilities!");
867 // Otherwise, replace the visibility of DF if DF is a prototype.
868 if (DF->isDeclaration())
869 DF->setVisibility(SF->getVisibility());
872 if (DF->getType() != SF->getType()) {
873 if (DF->isDeclaration() && !SF->isDeclaration()) {
874 // We have a definition of the same name but different type in the
875 // source module. Copy the prototype to the destination and replace
876 // uses of the destination's prototype with the new prototype.
877 Function *NewDF = Function::Create(SF->getFunctionType(),
879 SF->getName(), Dest);
880 CopyGVAttributes(NewDF, SF);
882 // Any uses of DF need to change to NewDF, with cast
883 DF->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, DF->getType()));
885 // DF will conflict with NewDF because they both had the same. We must
886 // erase this now so ForceRenaming doesn't assert because DF might
887 // not have internal linkage.
888 DF->eraseFromParent();
890 // If the symbol table renamed the function, but it is an externally
891 // visible symbol, DF must be an existing function with internal
892 // linkage. Rename it.
893 if (NewDF->getName() != SF->getName() && !NewDF->hasInternalLinkage())
894 ForceRenaming(NewDF, SF->getName());
896 // Remember this mapping so uses in the source module get remapped
897 // later by RemapOperand.
898 ValueMap[SF] = NewDF;
899 } else if (SF->isDeclaration()) {
900 // We have two functions of the same name but different type and the
901 // source is a declaration while the destination is not. Any use of
902 // the source must be mapped to the destination, with a cast.
903 ValueMap[SF] = ConstantExpr::getBitCast(DF, SF->getType());
905 // We have two functions of the same name but different types and they
906 // are both definitions. This is an error.
907 return Error(Err, "Function '" + DF->getName() + "' defined as both '" +
908 ToStr(SF->getFunctionType(), Src) + "' and '" +
909 ToStr(DF->getFunctionType(), Dest) + "'");
914 if (SF->isDeclaration()) {
915 // If SF is a declaration or if both SF & DF are declarations, just link
916 // the declarations, we aren't adding anything.
917 if (SF->hasDLLImportLinkage()) {
918 if (DF->isDeclaration()) {
919 ValueMap.insert(std::make_pair(SF, DF));
920 DF->setLinkage(SF->getLinkage());
925 } else if (DF->isDeclaration() && !DF->hasDLLImportLinkage()) {
926 // If DF is external but SF is not...
927 // Link the external functions, update linkage qualifiers
928 ValueMap.insert(std::make_pair(SF, DF));
929 DF->setLinkage(SF->getLinkage());
930 } else if (SF->hasWeakLinkage() || SF->hasLinkOnceLinkage() ||
931 SF->hasCommonLinkage()) {
932 // At this point we know that DF has LinkOnce, Weak, or External* linkage.
935 // Linkonce+Weak = Weak
936 // *+External Weak = *
937 if ((DF->hasLinkOnceLinkage() &&
938 (SF->hasWeakLinkage() || SF->hasCommonLinkage())) ||
939 DF->hasExternalWeakLinkage())
940 DF->setLinkage(SF->getLinkage());
941 } else if (DF->hasWeakLinkage() || DF->hasLinkOnceLinkage() ||
942 DF->hasCommonLinkage()) {
943 // At this point we know that SF has LinkOnce or External* linkage.
945 if (!SF->hasLinkOnceLinkage() && !SF->hasExternalWeakLinkage())
946 // Don't inherit linkonce & external weak linkage
947 DF->setLinkage(SF->getLinkage());
948 } else if (SF->getLinkage() != DF->getLinkage()) {
949 return Error(Err, "Functions named '" + SF->getName() +
950 "' have different linkage specifiers!");
951 } else if (SF->hasExternalLinkage()) {
952 // The function is defined identically in both modules!!
953 return Error(Err, "Function '" +
954 ToStr(SF->getFunctionType(), Src) + "':\"" +
955 SF->getName() + "\" - Function is already defined!");
957 assert(0 && "Unknown linkage configuration found!");
963 // LinkFunctionBody - Copy the source function over into the dest function and
964 // fix up references to values. At this point we know that Dest is an external
965 // function, and that Src is not.
966 static bool LinkFunctionBody(Function *Dest, Function *Src,
967 std::map<const Value*, Value*> &ValueMap,
969 assert(Src && Dest && Dest->isDeclaration() && !Src->isDeclaration());
971 // Go through and convert function arguments over, remembering the mapping.
972 Function::arg_iterator DI = Dest->arg_begin();
973 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
975 DI->setName(I->getName()); // Copy the name information over...
977 // Add a mapping to our local map
981 // Splice the body of the source function into the dest function.
982 Dest->getBasicBlockList().splice(Dest->end(), Src->getBasicBlockList());
984 // At this point, all of the instructions and values of the function are now
985 // copied over. The only problem is that they are still referencing values in
986 // the Source function as operands. Loop through all of the operands of the
987 // functions and patch them up to point to the local versions...
989 for (Function::iterator BB = Dest->begin(), BE = Dest->end(); BB != BE; ++BB)
990 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
991 for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end();
993 if (!isa<Instruction>(*OI) && !isa<BasicBlock>(*OI))
994 *OI = RemapOperand(*OI, ValueMap);
996 // There is no need to map the arguments anymore.
997 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1005 // LinkFunctionBodies - Link in the function bodies that are defined in the
1006 // source module into the DestModule. This consists basically of copying the
1007 // function over and fixing up references to values.
1008 static bool LinkFunctionBodies(Module *Dest, Module *Src,
1009 std::map<const Value*, Value*> &ValueMap,
1012 // Loop over all of the functions in the src module, mapping them over as we
1014 for (Module::iterator SF = Src->begin(), E = Src->end(); SF != E; ++SF) {
1015 if (!SF->isDeclaration()) { // No body if function is external
1016 Function *DF = cast<Function>(ValueMap[SF]); // Destination function
1018 // DF not external SF external?
1019 if (DF->isDeclaration())
1020 // Only provide the function body if there isn't one already.
1021 if (LinkFunctionBody(DF, SF, ValueMap, Err))
1028 // LinkAppendingVars - If there were any appending global variables, link them
1029 // together now. Return true on error.
1030 static bool LinkAppendingVars(Module *M,
1031 std::multimap<std::string, GlobalVariable *> &AppendingVars,
1032 std::string *ErrorMsg) {
1033 if (AppendingVars.empty()) return false; // Nothing to do.
1035 // Loop over the multimap of appending vars, processing any variables with the
1036 // same name, forming a new appending global variable with both of the
1037 // initializers merged together, then rewrite references to the old variables
1039 std::vector<Constant*> Inits;
1040 while (AppendingVars.size() > 1) {
1041 // Get the first two elements in the map...
1042 std::multimap<std::string,
1043 GlobalVariable*>::iterator Second = AppendingVars.begin(), First=Second++;
1045 // If the first two elements are for different names, there is no pair...
1046 // Otherwise there is a pair, so link them together...
1047 if (First->first == Second->first) {
1048 GlobalVariable *G1 = First->second, *G2 = Second->second;
1049 const ArrayType *T1 = cast<ArrayType>(G1->getType()->getElementType());
1050 const ArrayType *T2 = cast<ArrayType>(G2->getType()->getElementType());
1052 // Check to see that they two arrays agree on type...
1053 if (T1->getElementType() != T2->getElementType())
1054 return Error(ErrorMsg,
1055 "Appending variables with different element types need to be linked!");
1056 if (G1->isConstant() != G2->isConstant())
1057 return Error(ErrorMsg,
1058 "Appending variables linked with different const'ness!");
1060 if (G1->getAlignment() != G2->getAlignment())
1061 return Error(ErrorMsg,
1062 "Appending variables with different alignment need to be linked!");
1064 if (G1->getVisibility() != G2->getVisibility())
1065 return Error(ErrorMsg,
1066 "Appending variables with different visibility need to be linked!");
1068 if (G1->getSection() != G2->getSection())
1069 return Error(ErrorMsg,
1070 "Appending variables with different section name need to be linked!");
1072 unsigned NewSize = T1->getNumElements() + T2->getNumElements();
1073 ArrayType *NewType = ArrayType::get(T1->getElementType(), NewSize);
1075 G1->setName(""); // Clear G1's name in case of a conflict!
1077 // Create the new global variable...
1078 GlobalVariable *NG =
1079 new GlobalVariable(NewType, G1->isConstant(), G1->getLinkage(),
1080 /*init*/0, First->first, M, G1->isThreadLocal());
1082 // Propagate alignment, visibility and section info.
1083 CopyGVAttributes(NG, G1);
1085 // Merge the initializer...
1086 Inits.reserve(NewSize);
1087 if (ConstantArray *I = dyn_cast<ConstantArray>(G1->getInitializer())) {
1088 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i)
1089 Inits.push_back(I->getOperand(i));
1091 assert(isa<ConstantAggregateZero>(G1->getInitializer()));
1092 Constant *CV = Constant::getNullValue(T1->getElementType());
1093 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i)
1094 Inits.push_back(CV);
1096 if (ConstantArray *I = dyn_cast<ConstantArray>(G2->getInitializer())) {
1097 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i)
1098 Inits.push_back(I->getOperand(i));
1100 assert(isa<ConstantAggregateZero>(G2->getInitializer()));
1101 Constant *CV = Constant::getNullValue(T2->getElementType());
1102 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i)
1103 Inits.push_back(CV);
1105 NG->setInitializer(ConstantArray::get(NewType, Inits));
1108 // Replace any uses of the two global variables with uses of the new
1111 // FIXME: This should rewrite simple/straight-forward uses such as
1112 // getelementptr instructions to not use the Cast!
1113 G1->replaceAllUsesWith(ConstantExpr::getBitCast(NG, G1->getType()));
1114 G2->replaceAllUsesWith(ConstantExpr::getBitCast(NG, G2->getType()));
1116 // Remove the two globals from the module now...
1117 M->getGlobalList().erase(G1);
1118 M->getGlobalList().erase(G2);
1120 // Put the new global into the AppendingVars map so that we can handle
1121 // linking of more than two vars...
1122 Second->second = NG;
1124 AppendingVars.erase(First);
1130 static bool ResolveAliases(Module *Dest) {
1131 for (Module::alias_iterator I = Dest->alias_begin(), E = Dest->alias_end();
1133 if (const GlobalValue *GV = I->resolveAliasedGlobal())
1134 if (!GV->isDeclaration())
1135 I->replaceAllUsesWith(const_cast<GlobalValue*>(GV));
1140 // LinkModules - This function links two modules together, with the resulting
1141 // left module modified to be the composite of the two input modules. If an
1142 // error occurs, true is returned and ErrorMsg (if not null) is set to indicate
1143 // the problem. Upon failure, the Dest module could be in a modified state, and
1144 // shouldn't be relied on to be consistent.
1146 Linker::LinkModules(Module *Dest, Module *Src, std::string *ErrorMsg) {
1147 assert(Dest != 0 && "Invalid Destination module");
1148 assert(Src != 0 && "Invalid Source Module");
1150 if (Dest->getDataLayout().empty()) {
1151 if (!Src->getDataLayout().empty()) {
1152 Dest->setDataLayout(Src->getDataLayout());
1154 std::string DataLayout;
1156 if (Dest->getEndianness() == Module::AnyEndianness) {
1157 if (Src->getEndianness() == Module::BigEndian)
1158 DataLayout.append("E");
1159 else if (Src->getEndianness() == Module::LittleEndian)
1160 DataLayout.append("e");
1163 if (Dest->getPointerSize() == Module::AnyPointerSize) {
1164 if (Src->getPointerSize() == Module::Pointer64)
1165 DataLayout.append(DataLayout.length() == 0 ? "p:64:64" : "-p:64:64");
1166 else if (Src->getPointerSize() == Module::Pointer32)
1167 DataLayout.append(DataLayout.length() == 0 ? "p:32:32" : "-p:32:32");
1169 Dest->setDataLayout(DataLayout);
1173 // Copy the target triple from the source to dest if the dest's is empty.
1174 if (Dest->getTargetTriple().empty() && !Src->getTargetTriple().empty())
1175 Dest->setTargetTriple(Src->getTargetTriple());
1177 if (!Src->getDataLayout().empty() && !Dest->getDataLayout().empty() &&
1178 Src->getDataLayout() != Dest->getDataLayout())
1179 cerr << "WARNING: Linking two modules of different data layouts!\n";
1180 if (!Src->getTargetTriple().empty() &&
1181 Dest->getTargetTriple() != Src->getTargetTriple())
1182 cerr << "WARNING: Linking two modules of different target triples!\n";
1184 // Append the module inline asm string.
1185 if (!Src->getModuleInlineAsm().empty()) {
1186 if (Dest->getModuleInlineAsm().empty())
1187 Dest->setModuleInlineAsm(Src->getModuleInlineAsm());
1189 Dest->setModuleInlineAsm(Dest->getModuleInlineAsm()+"\n"+
1190 Src->getModuleInlineAsm());
1193 // Update the destination module's dependent libraries list with the libraries
1194 // from the source module. There's no opportunity for duplicates here as the
1195 // Module ensures that duplicate insertions are discarded.
1196 for (Module::lib_iterator SI = Src->lib_begin(), SE = Src->lib_end();
1198 Dest->addLibrary(*SI);
1200 // LinkTypes - Go through the symbol table of the Src module and see if any
1201 // types are named in the src module that are not named in the Dst module.
1202 // Make sure there are no type name conflicts.
1203 if (LinkTypes(Dest, Src, ErrorMsg))
1206 // ValueMap - Mapping of values from what they used to be in Src, to what they
1208 std::map<const Value*, Value*> ValueMap;
1210 // AppendingVars - Keep track of global variables in the destination module
1211 // with appending linkage. After the module is linked together, they are
1212 // appended and the module is rewritten.
1213 std::multimap<std::string, GlobalVariable *> AppendingVars;
1214 for (Module::global_iterator I = Dest->global_begin(), E = Dest->global_end();
1216 // Add all of the appending globals already in the Dest module to
1218 if (I->hasAppendingLinkage())
1219 AppendingVars.insert(std::make_pair(I->getName(), I));
1222 // Insert all of the globals in src into the Dest module... without linking
1223 // initializers (which could refer to functions not yet mapped over).
1224 if (LinkGlobals(Dest, Src, ValueMap, AppendingVars, ErrorMsg))
1227 // Link the functions together between the two modules, without doing function
1228 // bodies... this just adds external function prototypes to the Dest
1229 // function... We do this so that when we begin processing function bodies,
1230 // all of the global values that may be referenced are available in our
1232 if (LinkFunctionProtos(Dest, Src, ValueMap, ErrorMsg))
1235 // If there were any alias, link them now. We really need to do this now,
1236 // because all of the aliases that may be referenced need to be available in
1238 if (LinkAlias(Dest, Src, ValueMap, ErrorMsg)) return true;
1240 // Update the initializers in the Dest module now that all globals that may
1241 // be referenced are in Dest.
1242 if (LinkGlobalInits(Dest, Src, ValueMap, ErrorMsg)) return true;
1244 // Link in the function bodies that are defined in the source module into the
1245 // DestModule. This consists basically of copying the function over and
1246 // fixing up references to values.
1247 if (LinkFunctionBodies(Dest, Src, ValueMap, ErrorMsg)) return true;
1249 // If there were any appending global variables, link them together now.
1250 if (LinkAppendingVars(Dest, AppendingVars, ErrorMsg)) return true;
1252 // Resolve all uses of aliases with aliasees
1253 if (ResolveAliases(Dest)) return true;
1255 // If the source library's module id is in the dependent library list of the
1256 // destination library, remove it since that module is now linked in.
1258 modId.set(Src->getModuleIdentifier());
1259 if (!modId.isEmpty())
1260 Dest->removeLibrary(modId.getBasename());