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/Debug.h"
29 #include "llvm/Support/ErrorHandling.h"
30 #include "llvm/Support/raw_ostream.h"
31 #include "llvm/System/Path.h"
32 #include "llvm/ADT/DenseMap.h"
35 // Error - Simple wrapper function to conditionally assign to E and return true.
36 // This just makes error return conditions a little bit simpler...
37 static inline bool Error(std::string *E, const Twine &Message) {
38 if (E) *E = Message.str();
42 // Function: ResolveTypes()
45 // Attempt to link the two specified types together.
48 // DestTy - The type to which we wish to resolve.
49 // SrcTy - The original type which we want to resolve.
52 // DestST - The symbol table in which the new type should be placed.
55 // true - There is an error and the types cannot yet be linked.
58 static bool ResolveTypes(const Type *DestTy, const Type *SrcTy) {
59 if (DestTy == SrcTy) return false; // If already equal, noop
60 assert(DestTy && SrcTy && "Can't handle null types");
62 if (const OpaqueType *OT = dyn_cast<OpaqueType>(DestTy)) {
63 // Type _is_ in module, just opaque...
64 const_cast<OpaqueType*>(OT)->refineAbstractTypeTo(SrcTy);
65 } else if (const OpaqueType *OT = dyn_cast<OpaqueType>(SrcTy)) {
66 const_cast<OpaqueType*>(OT)->refineAbstractTypeTo(DestTy);
68 return true; // Cannot link types... not-equal and neither is opaque.
73 /// LinkerTypeMap - This implements a map of types that is stable
74 /// even if types are resolved/refined to other types. This is not a general
75 /// purpose map, it is specific to the linker's use.
77 class LinkerTypeMap : public AbstractTypeUser {
78 typedef DenseMap<const Type*, PATypeHolder> TheMapTy;
81 LinkerTypeMap(const LinkerTypeMap&); // DO NOT IMPLEMENT
82 void operator=(const LinkerTypeMap&); // DO NOT IMPLEMENT
86 for (DenseMap<const Type*, PATypeHolder>::iterator I = TheMap.begin(),
87 E = TheMap.end(); I != E; ++I)
88 I->first->removeAbstractTypeUser(this);
91 /// lookup - Return the value for the specified type or null if it doesn't
93 const Type *lookup(const Type *Ty) const {
94 TheMapTy::const_iterator I = TheMap.find(Ty);
95 if (I != TheMap.end()) return I->second;
99 /// erase - Remove the specified type, returning true if it was in the set.
100 bool erase(const Type *Ty) {
101 if (!TheMap.erase(Ty))
103 if (Ty->isAbstract())
104 Ty->removeAbstractTypeUser(this);
108 /// insert - This returns true if the pointer was new to the set, false if it
109 /// was already in the set.
110 bool insert(const Type *Src, const Type *Dst) {
111 if (!TheMap.insert(std::make_pair(Src, PATypeHolder(Dst))).second)
112 return false; // Already in map.
113 if (Src->isAbstract())
114 Src->addAbstractTypeUser(this);
119 /// refineAbstractType - The callback method invoked when an abstract type is
120 /// resolved to another type. An object must override this method to update
121 /// its internal state to reference NewType instead of OldType.
123 virtual void refineAbstractType(const DerivedType *OldTy,
125 TheMapTy::iterator I = TheMap.find(OldTy);
126 const Type *DstTy = I->second;
129 if (OldTy->isAbstract())
130 OldTy->removeAbstractTypeUser(this);
132 // Don't reinsert into the map if the key is concrete now.
133 if (NewTy->isAbstract())
134 insert(NewTy, DstTy);
137 /// The other case which AbstractTypeUsers must be aware of is when a type
138 /// makes the transition from being abstract (where it has clients on it's
139 /// AbstractTypeUsers list) to concrete (where it does not). This method
140 /// notifies ATU's when this occurs for a type.
141 virtual void typeBecameConcrete(const DerivedType *AbsTy) {
143 AbsTy->removeAbstractTypeUser(this);
147 virtual void dump() const {
148 dbgs() << "AbstractTypeSet!\n";
154 // RecursiveResolveTypes - This is just like ResolveTypes, except that it
155 // recurses down into derived types, merging the used types if the parent types
157 static bool RecursiveResolveTypesI(const Type *DstTy, const Type *SrcTy,
158 LinkerTypeMap &Pointers) {
159 if (DstTy == SrcTy) return false; // If already equal, noop
161 // If we found our opaque type, resolve it now!
162 if (DstTy->isOpaqueTy() || SrcTy->isOpaqueTy())
163 return ResolveTypes(DstTy, SrcTy);
165 // Two types cannot be resolved together if they are of different primitive
166 // type. For example, we cannot resolve an int to a float.
167 if (DstTy->getTypeID() != SrcTy->getTypeID()) return true;
169 // If neither type is abstract, then they really are just different types.
170 if (!DstTy->isAbstract() && !SrcTy->isAbstract())
173 // Otherwise, resolve the used type used by this derived type...
174 switch (DstTy->getTypeID()) {
177 case Type::FunctionTyID: {
178 const FunctionType *DstFT = cast<FunctionType>(DstTy);
179 const FunctionType *SrcFT = cast<FunctionType>(SrcTy);
180 if (DstFT->isVarArg() != SrcFT->isVarArg() ||
181 DstFT->getNumContainedTypes() != SrcFT->getNumContainedTypes())
184 // Use TypeHolder's so recursive resolution won't break us.
185 PATypeHolder ST(SrcFT), DT(DstFT);
186 for (unsigned i = 0, e = DstFT->getNumContainedTypes(); i != e; ++i) {
187 const Type *SE = ST->getContainedType(i), *DE = DT->getContainedType(i);
188 if (SE != DE && RecursiveResolveTypesI(DE, SE, Pointers))
193 case Type::StructTyID: {
194 const StructType *DstST = cast<StructType>(DstTy);
195 const StructType *SrcST = cast<StructType>(SrcTy);
196 if (DstST->getNumContainedTypes() != SrcST->getNumContainedTypes())
199 PATypeHolder ST(SrcST), DT(DstST);
200 for (unsigned i = 0, e = DstST->getNumContainedTypes(); i != e; ++i) {
201 const Type *SE = ST->getContainedType(i), *DE = DT->getContainedType(i);
202 if (SE != DE && RecursiveResolveTypesI(DE, SE, Pointers))
207 case Type::ArrayTyID: {
208 const ArrayType *DAT = cast<ArrayType>(DstTy);
209 const ArrayType *SAT = cast<ArrayType>(SrcTy);
210 if (DAT->getNumElements() != SAT->getNumElements()) return true;
211 return RecursiveResolveTypesI(DAT->getElementType(), SAT->getElementType(),
214 case Type::VectorTyID: {
215 const VectorType *DVT = cast<VectorType>(DstTy);
216 const VectorType *SVT = cast<VectorType>(SrcTy);
217 if (DVT->getNumElements() != SVT->getNumElements()) return true;
218 return RecursiveResolveTypesI(DVT->getElementType(), SVT->getElementType(),
221 case Type::PointerTyID: {
222 const PointerType *DstPT = cast<PointerType>(DstTy);
223 const PointerType *SrcPT = cast<PointerType>(SrcTy);
225 if (DstPT->getAddressSpace() != SrcPT->getAddressSpace())
228 // If this is a pointer type, check to see if we have already seen it. If
229 // so, we are in a recursive branch. Cut off the search now. We cannot use
230 // an associative container for this search, because the type pointers (keys
231 // in the container) change whenever types get resolved.
232 if (SrcPT->isAbstract())
233 if (const Type *ExistingDestTy = Pointers.lookup(SrcPT))
234 return ExistingDestTy != DstPT;
236 if (DstPT->isAbstract())
237 if (const Type *ExistingSrcTy = Pointers.lookup(DstPT))
238 return ExistingSrcTy != SrcPT;
239 // Otherwise, add the current pointers to the vector to stop recursion on
241 if (DstPT->isAbstract())
242 Pointers.insert(DstPT, SrcPT);
243 if (SrcPT->isAbstract())
244 Pointers.insert(SrcPT, DstPT);
246 return RecursiveResolveTypesI(DstPT->getElementType(),
247 SrcPT->getElementType(), Pointers);
252 static bool RecursiveResolveTypes(const Type *DestTy, const Type *SrcTy) {
253 LinkerTypeMap PointerTypes;
254 return RecursiveResolveTypesI(DestTy, SrcTy, PointerTypes);
258 // LinkTypes - Go through the symbol table of the Src module and see if any
259 // types are named in the src module that are not named in the Dst module.
260 // Make sure there are no type name conflicts.
261 static bool LinkTypes(Module *Dest, const Module *Src, std::string *Err) {
262 TypeSymbolTable *DestST = &Dest->getTypeSymbolTable();
263 const TypeSymbolTable *SrcST = &Src->getTypeSymbolTable();
265 // Look for a type plane for Type's...
266 TypeSymbolTable::const_iterator TI = SrcST->begin();
267 TypeSymbolTable::const_iterator TE = SrcST->end();
268 if (TI == TE) return false; // No named types, do nothing.
270 // Some types cannot be resolved immediately because they depend on other
271 // types being resolved to each other first. This contains a list of types we
272 // are waiting to recheck.
273 std::vector<std::string> DelayedTypesToResolve;
275 for ( ; TI != TE; ++TI ) {
276 const std::string &Name = TI->first;
277 const Type *RHS = TI->second;
279 // Check to see if this type name is already in the dest module.
280 Type *Entry = DestST->lookup(Name);
282 // If the name is just in the source module, bring it over to the dest.
285 DestST->insert(Name, const_cast<Type*>(RHS));
286 } else if (ResolveTypes(Entry, RHS)) {
287 // They look different, save the types 'till later to resolve.
288 DelayedTypesToResolve.push_back(Name);
292 // Iteratively resolve types while we can...
293 while (!DelayedTypesToResolve.empty()) {
294 // Loop over all of the types, attempting to resolve them if possible...
295 unsigned OldSize = DelayedTypesToResolve.size();
297 // Try direct resolution by name...
298 for (unsigned i = 0; i != DelayedTypesToResolve.size(); ++i) {
299 const std::string &Name = DelayedTypesToResolve[i];
300 Type *T1 = SrcST->lookup(Name);
301 Type *T2 = DestST->lookup(Name);
302 if (!ResolveTypes(T2, T1)) {
303 // We are making progress!
304 DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i);
309 // Did we not eliminate any types?
310 if (DelayedTypesToResolve.size() == OldSize) {
311 // Attempt to resolve subelements of types. This allows us to merge these
312 // two types: { int* } and { opaque* }
313 for (unsigned i = 0, e = DelayedTypesToResolve.size(); i != e; ++i) {
314 const std::string &Name = DelayedTypesToResolve[i];
315 if (!RecursiveResolveTypes(SrcST->lookup(Name), DestST->lookup(Name))) {
316 // We are making progress!
317 DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i);
319 // Go back to the main loop, perhaps we can resolve directly by name
325 // If we STILL cannot resolve the types, then there is something wrong.
326 if (DelayedTypesToResolve.size() == OldSize) {
327 // Remove the symbol name from the destination.
328 DelayedTypesToResolve.pop_back();
338 static void PrintMap(const std::map<const Value*, Value*> &M) {
339 for (std::map<const Value*, Value*>::const_iterator I = M.begin(), E =M.end();
341 dbgs() << " Fr: " << (void*)I->first << " ";
343 dbgs() << " To: " << (void*)I->second << " ";
351 // RemapOperand - Use ValueMap to convert constants from one module to another.
352 static Value *RemapOperand(const Value *In,
353 std::map<const Value*, Value*> &ValueMap) {
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));
369 Result = ConstantArray::get(cast<ArrayType>(CPA->getType()), Operands);
370 } else if (const ConstantStruct *CPS = dyn_cast<ConstantStruct>(CPV)) {
371 std::vector<Constant*> Operands(CPS->getNumOperands());
372 for (unsigned i = 0, e = CPS->getNumOperands(); i != e; ++i)
373 Operands[i] =cast<Constant>(RemapOperand(CPS->getOperand(i), ValueMap));
374 Result = ConstantStruct::get(cast<StructType>(CPS->getType()), Operands);
375 } else if (isa<ConstantPointerNull>(CPV) || isa<UndefValue>(CPV)) {
376 Result = const_cast<Constant*>(CPV);
377 } else if (const ConstantVector *CP = dyn_cast<ConstantVector>(CPV)) {
378 std::vector<Constant*> Operands(CP->getNumOperands());
379 for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i)
380 Operands[i] = cast<Constant>(RemapOperand(CP->getOperand(i), ValueMap));
381 Result = ConstantVector::get(Operands);
382 } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CPV)) {
383 std::vector<Constant*> Ops;
384 for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i)
385 Ops.push_back(cast<Constant>(RemapOperand(CE->getOperand(i),ValueMap)));
386 Result = CE->getWithOperands(Ops);
387 } else if (const BlockAddress *CE = dyn_cast<BlockAddress>(CPV)) {
388 Result = BlockAddress::get(
389 cast<Function>(RemapOperand(CE->getFunction(), ValueMap)),
390 CE->getBasicBlock());
392 assert(!isa<GlobalValue>(CPV) && "Unmapped global?");
393 llvm_unreachable("Unknown type of derived type constant value!");
395 } else if (const MDNode *MD = dyn_cast<MDNode>(In)) {
396 if (MD->isFunctionLocal()) {
397 SmallVector<Value*, 4> Elts;
398 for (unsigned i = 0, e = MD->getNumOperands(); i != e; ++i) {
399 if (MD->getOperand(i))
400 Elts.push_back(RemapOperand(MD->getOperand(i), ValueMap));
402 Elts.push_back(NULL);
404 Result = MDNode::get(In->getContext(), Elts.data(), MD->getNumOperands());
406 Result = const_cast<Value*>(In);
408 } else if (isa<MDString>(In) || isa<InlineAsm>(In) || isa<Instruction>(In)) {
409 Result = const_cast<Value*>(In);
412 // Cache the mapping in our local map structure
414 ValueMap[In] = Result;
419 dbgs() << "LinkModules ValueMap: \n";
422 dbgs() << "Couldn't remap value: " << (void*)In << " " << *In << "\n";
423 llvm_unreachable("Couldn't remap value!");
428 /// ForceRenaming - The LLVM SymbolTable class autorenames globals that conflict
429 /// in the symbol table. This is good for all clients except for us. Go
430 /// through the trouble to force this back.
431 static void ForceRenaming(GlobalValue *GV, const std::string &Name) {
432 assert(GV->getName() != Name && "Can't force rename to self");
433 ValueSymbolTable &ST = GV->getParent()->getValueSymbolTable();
435 // If there is a conflict, rename the conflict.
436 if (GlobalValue *ConflictGV = cast_or_null<GlobalValue>(ST.lookup(Name))) {
437 assert(ConflictGV->hasLocalLinkage() &&
438 "Not conflicting with a static global, should link instead!");
439 GV->takeName(ConflictGV);
440 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
441 assert(ConflictGV->getName() != Name && "ForceRenaming didn't work");
443 GV->setName(Name); // Force the name back
447 /// CopyGVAttributes - copy additional attributes (those not needed to construct
448 /// a GlobalValue) from the SrcGV to the DestGV.
449 static void CopyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) {
450 // Use the maximum alignment, rather than just copying the alignment of SrcGV.
451 unsigned Alignment = std::max(DestGV->getAlignment(), SrcGV->getAlignment());
452 DestGV->copyAttributesFrom(SrcGV);
453 DestGV->setAlignment(Alignment);
456 /// GetLinkageResult - This analyzes the two global values and determines what
457 /// the result will look like in the destination module. In particular, it
458 /// computes the resultant linkage type, computes whether the global in the
459 /// source should be copied over to the destination (replacing the existing
460 /// one), and computes whether this linkage is an error or not. It also performs
461 /// visibility checks: we cannot link together two symbols with different
463 static bool GetLinkageResult(GlobalValue *Dest, const GlobalValue *Src,
464 GlobalValue::LinkageTypes <, bool &LinkFromSrc,
466 assert((!Dest || !Src->hasLocalLinkage()) &&
467 "If Src has internal linkage, Dest shouldn't be set!");
469 // Linking something to nothing.
471 LT = Src->getLinkage();
472 } else if (Src->isDeclaration()) {
473 // If Src is external or if both Src & Dest are external.. Just link the
474 // external globals, we aren't adding anything.
475 if (Src->hasDLLImportLinkage()) {
476 // If one of GVs has DLLImport linkage, result should be dllimport'ed.
477 if (Dest->isDeclaration()) {
479 LT = Src->getLinkage();
481 } else if (Dest->hasExternalWeakLinkage()) {
482 // If the Dest is weak, use the source linkage.
484 LT = Src->getLinkage();
487 LT = Dest->getLinkage();
489 } else if (Dest->isDeclaration() && !Dest->hasDLLImportLinkage()) {
490 // If Dest is external but Src is not:
492 LT = Src->getLinkage();
493 } else if (Src->hasAppendingLinkage() || Dest->hasAppendingLinkage()) {
494 if (Src->getLinkage() != Dest->getLinkage())
495 return Error(Err, "Linking globals named '" + Src->getName() +
496 "': can only link appending global with another appending global!");
497 LinkFromSrc = true; // Special cased.
498 LT = Src->getLinkage();
499 } else if (Src->isWeakForLinker()) {
500 // At this point we know that Dest has LinkOnce, External*, Weak, Common,
502 if (Dest->hasExternalWeakLinkage() ||
503 Dest->hasAvailableExternallyLinkage() ||
504 (Dest->hasLinkOnceLinkage() &&
505 (Src->hasWeakLinkage() || Src->hasCommonLinkage()))) {
507 LT = Src->getLinkage();
510 LT = Dest->getLinkage();
512 } else if (Dest->isWeakForLinker()) {
513 // At this point we know that Src has External* or DLL* linkage.
514 if (Src->hasExternalWeakLinkage()) {
516 LT = Dest->getLinkage();
519 LT = GlobalValue::ExternalLinkage;
522 assert((Dest->hasExternalLinkage() ||
523 Dest->hasDLLImportLinkage() ||
524 Dest->hasDLLExportLinkage() ||
525 Dest->hasExternalWeakLinkage()) &&
526 (Src->hasExternalLinkage() ||
527 Src->hasDLLImportLinkage() ||
528 Src->hasDLLExportLinkage() ||
529 Src->hasExternalWeakLinkage()) &&
530 "Unexpected linkage type!");
531 return Error(Err, "Linking globals named '" + Src->getName() +
532 "': symbol multiply defined!");
536 if (Dest && Src->getVisibility() != Dest->getVisibility())
537 if (!Src->isDeclaration() && !Dest->isDeclaration())
538 return Error(Err, "Linking globals named '" + Src->getName() +
539 "': symbols have different visibilities!");
543 // Insert all of the named mdnoes in Src into the Dest module.
544 static void LinkNamedMDNodes(Module *Dest, Module *Src) {
545 for (Module::const_named_metadata_iterator I = Src->named_metadata_begin(),
546 E = Src->named_metadata_end(); I != E; ++I) {
547 const NamedMDNode *SrcNMD = I;
548 NamedMDNode *DestNMD = Dest->getNamedMetadata(SrcNMD->getName());
550 NamedMDNode::Create(SrcNMD, Dest);
552 // Add Src elements into Dest node.
553 for (unsigned i = 0, e = SrcNMD->getNumOperands(); i != e; ++i)
554 DestNMD->addOperand(SrcNMD->getOperand(i));
559 // LinkGlobals - Loop through the global variables in the src module and merge
560 // them into the dest module.
561 static bool LinkGlobals(Module *Dest, const Module *Src,
562 std::map<const Value*, Value*> &ValueMap,
563 std::multimap<std::string, GlobalVariable *> &AppendingVars,
565 ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable();
567 // Loop over all of the globals in the src module, mapping them over as we go
568 for (Module::const_global_iterator I = Src->global_begin(),
569 E = Src->global_end(); I != E; ++I) {
570 const GlobalVariable *SGV = I;
571 GlobalValue *DGV = 0;
573 // Check to see if may have to link the global with the global, alias or
575 if (SGV->hasName() && !SGV->hasLocalLinkage())
576 DGV = cast_or_null<GlobalValue>(DestSymTab.lookup(SGV->getName()));
578 // If we found a global with the same name in the dest module, but it has
579 // internal linkage, we are really not doing any linkage here.
580 if (DGV && DGV->hasLocalLinkage())
583 // If types don't agree due to opaque types, try to resolve them.
584 if (DGV && DGV->getType() != SGV->getType())
585 RecursiveResolveTypes(SGV->getType(), DGV->getType());
587 assert((SGV->hasInitializer() || SGV->hasExternalWeakLinkage() ||
588 SGV->hasExternalLinkage() || SGV->hasDLLImportLinkage()) &&
589 "Global must either be external or have an initializer!");
591 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
592 bool LinkFromSrc = false;
593 if (GetLinkageResult(DGV, SGV, NewLinkage, LinkFromSrc, Err))
597 // No linking to be performed, simply create an identical version of the
598 // symbol over in the dest module... the initializer will be filled in
599 // later by LinkGlobalInits.
600 GlobalVariable *NewDGV =
601 new GlobalVariable(*Dest, SGV->getType()->getElementType(),
602 SGV->isConstant(), SGV->getLinkage(), /*init*/0,
603 SGV->getName(), 0, false,
604 SGV->getType()->getAddressSpace());
605 // Propagate alignment, visibility and section info.
606 CopyGVAttributes(NewDGV, SGV);
608 // If the LLVM runtime renamed the global, but it is an externally visible
609 // symbol, DGV must be an existing global with internal linkage. Rename
611 if (!NewDGV->hasLocalLinkage() && NewDGV->getName() != SGV->getName())
612 ForceRenaming(NewDGV, SGV->getName());
614 // Make sure to remember this mapping.
615 ValueMap[SGV] = NewDGV;
617 // Keep track that this is an appending variable.
618 if (SGV->hasAppendingLinkage())
619 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV));
623 // If the visibilities of the symbols disagree and the destination is a
624 // prototype, take the visibility of its input.
625 if (DGV->isDeclaration())
626 DGV->setVisibility(SGV->getVisibility());
628 if (DGV->hasAppendingLinkage()) {
629 // No linking is performed yet. Just insert a new copy of the global, and
630 // keep track of the fact that it is an appending variable in the
631 // AppendingVars map. The name is cleared out so that no linkage is
633 GlobalVariable *NewDGV =
634 new GlobalVariable(*Dest, SGV->getType()->getElementType(),
635 SGV->isConstant(), SGV->getLinkage(), /*init*/0,
637 SGV->getType()->getAddressSpace());
639 // Set alignment allowing CopyGVAttributes merge it with alignment of SGV.
640 NewDGV->setAlignment(DGV->getAlignment());
641 // Propagate alignment, section and visibility info.
642 CopyGVAttributes(NewDGV, SGV);
644 // Make sure to remember this mapping...
645 ValueMap[SGV] = NewDGV;
647 // Keep track that this is an appending variable...
648 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV));
653 if (isa<GlobalAlias>(DGV))
654 return Error(Err, "Global-Alias Collision on '" + SGV->getName() +
655 "': symbol multiple defined");
657 // If the types don't match, and if we are to link from the source, nuke
658 // DGV and create a new one of the appropriate type. Note that the thing
659 // we are replacing may be a function (if a prototype, weak, etc) or a
661 GlobalVariable *NewDGV =
662 new GlobalVariable(*Dest, SGV->getType()->getElementType(),
663 SGV->isConstant(), NewLinkage, /*init*/0,
664 DGV->getName(), 0, false,
665 SGV->getType()->getAddressSpace());
667 // Propagate alignment, section, and visibility info.
668 CopyGVAttributes(NewDGV, SGV);
669 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV,
672 // DGV will conflict with NewDGV because they both had the same
673 // name. We must erase this now so ForceRenaming doesn't assert
674 // because DGV might not have internal linkage.
675 if (GlobalVariable *Var = dyn_cast<GlobalVariable>(DGV))
676 Var->eraseFromParent();
678 cast<Function>(DGV)->eraseFromParent();
680 // If the symbol table renamed the global, but it is an externally visible
681 // symbol, DGV must be an existing global with internal linkage. Rename.
682 if (NewDGV->getName() != SGV->getName() && !NewDGV->hasLocalLinkage())
683 ForceRenaming(NewDGV, SGV->getName());
685 // Inherit const as appropriate.
686 NewDGV->setConstant(SGV->isConstant());
688 // Make sure to remember this mapping.
689 ValueMap[SGV] = NewDGV;
693 // Not "link from source", keep the one in the DestModule and remap the
696 // Special case for const propagation.
697 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV))
698 if (DGVar->isDeclaration() && SGV->isConstant() && !DGVar->isConstant())
699 DGVar->setConstant(true);
701 // SGV is global, but DGV is alias.
702 if (isa<GlobalAlias>(DGV)) {
703 // The only valid mappings are:
704 // - SGV is external declaration, which is effectively a no-op.
705 // - SGV is weak, when we just need to throw SGV out.
706 if (!SGV->isDeclaration() && !SGV->isWeakForLinker())
707 return Error(Err, "Global-Alias Collision on '" + SGV->getName() +
708 "': symbol multiple defined");
711 // Set calculated linkage
712 DGV->setLinkage(NewLinkage);
714 // Make sure to remember this mapping...
715 ValueMap[SGV] = ConstantExpr::getBitCast(DGV, SGV->getType());
720 static GlobalValue::LinkageTypes
721 CalculateAliasLinkage(const GlobalValue *SGV, const GlobalValue *DGV) {
722 GlobalValue::LinkageTypes SL = SGV->getLinkage();
723 GlobalValue::LinkageTypes DL = DGV->getLinkage();
724 if (SL == GlobalValue::ExternalLinkage || DL == GlobalValue::ExternalLinkage)
725 return GlobalValue::ExternalLinkage;
726 else if (SL == GlobalValue::WeakAnyLinkage ||
727 DL == GlobalValue::WeakAnyLinkage)
728 return GlobalValue::WeakAnyLinkage;
729 else if (SL == GlobalValue::WeakODRLinkage ||
730 DL == GlobalValue::WeakODRLinkage)
731 return GlobalValue::WeakODRLinkage;
732 else if (SL == GlobalValue::InternalLinkage &&
733 DL == GlobalValue::InternalLinkage)
734 return GlobalValue::InternalLinkage;
735 else if (SL == GlobalValue::LinkerPrivateLinkage &&
736 DL == GlobalValue::LinkerPrivateLinkage)
737 return GlobalValue::LinkerPrivateLinkage;
739 assert (SL == GlobalValue::PrivateLinkage &&
740 DL == GlobalValue::PrivateLinkage && "Unexpected linkage type");
741 return GlobalValue::PrivateLinkage;
745 // LinkAlias - Loop through the alias in the src module and link them into the
746 // dest module. We're assuming, that all functions/global variables were already
748 static bool LinkAlias(Module *Dest, const Module *Src,
749 std::map<const Value*, Value*> &ValueMap,
751 // Loop over all alias in the src module
752 for (Module::const_alias_iterator I = Src->alias_begin(),
753 E = Src->alias_end(); I != E; ++I) {
754 const GlobalAlias *SGA = I;
755 const GlobalValue *SAliasee = SGA->getAliasedGlobal();
756 GlobalAlias *NewGA = NULL;
758 // Globals were already linked, thus we can just query ValueMap for variant
759 // of SAliasee in Dest.
760 std::map<const Value*,Value*>::const_iterator VMI = ValueMap.find(SAliasee);
761 assert(VMI != ValueMap.end() && "Aliasee not linked");
762 GlobalValue* DAliasee = cast<GlobalValue>(VMI->second);
763 GlobalValue* DGV = NULL;
765 // Try to find something 'similar' to SGA in destination module.
766 if (!DGV && !SGA->hasLocalLinkage()) {
767 DGV = Dest->getNamedAlias(SGA->getName());
769 // If types don't agree due to opaque types, try to resolve them.
770 if (DGV && DGV->getType() != SGA->getType())
771 RecursiveResolveTypes(SGA->getType(), DGV->getType());
774 if (!DGV && !SGA->hasLocalLinkage()) {
775 DGV = Dest->getGlobalVariable(SGA->getName());
777 // If types don't agree due to opaque types, try to resolve them.
778 if (DGV && DGV->getType() != SGA->getType())
779 RecursiveResolveTypes(SGA->getType(), DGV->getType());
782 if (!DGV && !SGA->hasLocalLinkage()) {
783 DGV = Dest->getFunction(SGA->getName());
785 // If types don't agree due to opaque types, try to resolve them.
786 if (DGV && DGV->getType() != SGA->getType())
787 RecursiveResolveTypes(SGA->getType(), DGV->getType());
790 // No linking to be performed on internal stuff.
791 if (DGV && DGV->hasLocalLinkage())
794 if (GlobalAlias *DGA = dyn_cast_or_null<GlobalAlias>(DGV)) {
795 // Types are known to be the same, check whether aliasees equal. As
796 // globals are already linked we just need query ValueMap to find the
798 if (DAliasee == DGA->getAliasedGlobal()) {
799 // This is just two copies of the same alias. Propagate linkage, if
801 DGA->setLinkage(CalculateAliasLinkage(SGA, DGA));
804 // Proceed to 'common' steps
806 return Error(Err, "Alias Collision on '" + SGA->getName()+
807 "': aliases have different aliasees");
808 } else if (GlobalVariable *DGVar = dyn_cast_or_null<GlobalVariable>(DGV)) {
809 // The only allowed way is to link alias with external declaration or weak
811 if (DGVar->isDeclaration() || DGVar->isWeakForLinker()) {
812 // But only if aliasee is global too...
813 if (!isa<GlobalVariable>(DAliasee))
814 return Error(Err, "Global-Alias Collision on '" + SGA->getName() +
815 "': aliasee is not global variable");
817 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(),
818 SGA->getName(), DAliasee, Dest);
819 CopyGVAttributes(NewGA, SGA);
821 // Any uses of DGV need to change to NewGA, with cast, if needed.
822 if (SGA->getType() != DGVar->getType())
823 DGVar->replaceAllUsesWith(ConstantExpr::getBitCast(NewGA,
826 DGVar->replaceAllUsesWith(NewGA);
828 // DGVar will conflict with NewGA because they both had the same
829 // name. We must erase this now so ForceRenaming doesn't assert
830 // because DGV might not have internal linkage.
831 DGVar->eraseFromParent();
833 // Proceed to 'common' steps
835 return Error(Err, "Global-Alias Collision on '" + SGA->getName() +
836 "': symbol multiple defined");
837 } else if (Function *DF = dyn_cast_or_null<Function>(DGV)) {
838 // The only allowed way is to link alias with external declaration or weak
840 if (DF->isDeclaration() || DF->isWeakForLinker()) {
841 // But only if aliasee is function too...
842 if (!isa<Function>(DAliasee))
843 return Error(Err, "Function-Alias Collision on '" + SGA->getName() +
844 "': aliasee is not function");
846 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(),
847 SGA->getName(), DAliasee, Dest);
848 CopyGVAttributes(NewGA, SGA);
850 // Any uses of DF need to change to NewGA, with cast, if needed.
851 if (SGA->getType() != DF->getType())
852 DF->replaceAllUsesWith(ConstantExpr::getBitCast(NewGA,
855 DF->replaceAllUsesWith(NewGA);
857 // DF will conflict with NewGA because they both had the same
858 // name. We must erase this now so ForceRenaming doesn't assert
859 // because DF might not have internal linkage.
860 DF->eraseFromParent();
862 // Proceed to 'common' steps
864 return Error(Err, "Function-Alias Collision on '" + SGA->getName() +
865 "': symbol multiple defined");
867 // No linking to be performed, simply create an identical version of the
868 // alias over in the dest module...
869 Constant *Aliasee = DAliasee;
870 // Fixup aliases to bitcasts. Note that aliases to GEPs are still broken
871 // by this, but aliases to GEPs are broken to a lot of other things, so
872 // it's less important.
873 if (SGA->getType() != DAliasee->getType())
874 Aliasee = ConstantExpr::getBitCast(DAliasee, SGA->getType());
875 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(),
876 SGA->getName(), Aliasee, Dest);
877 CopyGVAttributes(NewGA, SGA);
879 // Proceed to 'common' steps
882 assert(NewGA && "No alias was created in destination module!");
884 // If the symbol table renamed the alias, but it is an externally visible
885 // symbol, DGA must be an global value with internal linkage. Rename it.
886 if (NewGA->getName() != SGA->getName() &&
887 !NewGA->hasLocalLinkage())
888 ForceRenaming(NewGA, SGA->getName());
890 // Remember this mapping so uses in the source module get remapped
891 // later by RemapOperand.
892 ValueMap[SGA] = NewGA;
899 // LinkGlobalInits - Update the initializers in the Dest module now that all
900 // globals that may be referenced are in Dest.
901 static bool LinkGlobalInits(Module *Dest, const Module *Src,
902 std::map<const Value*, Value*> &ValueMap,
904 // Loop over all of the globals in the src module, mapping them over as we go
905 for (Module::const_global_iterator I = Src->global_begin(),
906 E = Src->global_end(); I != E; ++I) {
907 const GlobalVariable *SGV = I;
909 if (SGV->hasInitializer()) { // Only process initialized GV's
910 // Figure out what the initializer looks like in the dest module...
912 cast<Constant>(RemapOperand(SGV->getInitializer(), ValueMap));
913 // Grab destination global variable or alias.
914 GlobalValue *DGV = cast<GlobalValue>(ValueMap[SGV]->stripPointerCasts());
916 // If dest if global variable, check that initializers match.
917 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) {
918 if (DGVar->hasInitializer()) {
919 if (SGV->hasExternalLinkage()) {
920 if (DGVar->getInitializer() != SInit)
921 return Error(Err, "Global Variable Collision on '" +
923 "': global variables have different initializers");
924 } else if (DGVar->isWeakForLinker()) {
925 // Nothing is required, mapped values will take the new global
927 } else if (SGV->isWeakForLinker()) {
928 // Nothing is required, mapped values will take the new global
930 } else if (DGVar->hasAppendingLinkage()) {
931 llvm_unreachable("Appending linkage unimplemented!");
933 llvm_unreachable("Unknown linkage!");
936 // Copy the initializer over now...
937 DGVar->setInitializer(SInit);
940 // Destination is alias, the only valid situation is when source is
941 // weak. Also, note, that we already checked linkage in LinkGlobals(),
942 // thus we assert here.
943 // FIXME: Should we weaken this assumption, 'dereference' alias and
944 // check for initializer of aliasee?
945 assert(SGV->isWeakForLinker());
952 // LinkFunctionProtos - Link the functions together between the two modules,
953 // without doing function bodies... this just adds external function prototypes
954 // to the Dest function...
956 static bool LinkFunctionProtos(Module *Dest, const Module *Src,
957 std::map<const Value*, Value*> &ValueMap,
959 ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable();
961 // Loop over all of the functions in the src module, mapping them over
962 for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) {
963 const Function *SF = I; // SrcFunction
964 GlobalValue *DGV = 0;
966 // Check to see if may have to link the function with the global, alias or
968 if (SF->hasName() && !SF->hasLocalLinkage())
969 DGV = cast_or_null<GlobalValue>(DestSymTab.lookup(SF->getName()));
971 // If we found a global with the same name in the dest module, but it has
972 // internal linkage, we are really not doing any linkage here.
973 if (DGV && DGV->hasLocalLinkage())
976 // If types don't agree due to opaque types, try to resolve them.
977 if (DGV && DGV->getType() != SF->getType())
978 RecursiveResolveTypes(SF->getType(), DGV->getType());
980 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
981 bool LinkFromSrc = false;
982 if (GetLinkageResult(DGV, SF, NewLinkage, LinkFromSrc, Err))
985 // If there is no linkage to be performed, just bring over SF without
988 // Function does not already exist, simply insert an function signature
989 // identical to SF into the dest module.
990 Function *NewDF = Function::Create(SF->getFunctionType(),
992 SF->getName(), Dest);
993 CopyGVAttributes(NewDF, SF);
995 // If the LLVM runtime renamed the function, but it is an externally
996 // visible symbol, DF must be an existing function with internal linkage.
998 if (!NewDF->hasLocalLinkage() && NewDF->getName() != SF->getName())
999 ForceRenaming(NewDF, SF->getName());
1001 // ... and remember this mapping...
1002 ValueMap[SF] = NewDF;
1006 // If the visibilities of the symbols disagree and the destination is a
1007 // prototype, take the visibility of its input.
1008 if (DGV->isDeclaration())
1009 DGV->setVisibility(SF->getVisibility());
1012 if (isa<GlobalAlias>(DGV))
1013 return Error(Err, "Function-Alias Collision on '" + SF->getName() +
1014 "': symbol multiple defined");
1016 // We have a definition of the same name but different type in the
1017 // source module. Copy the prototype to the destination and replace
1018 // uses of the destination's prototype with the new prototype.
1019 Function *NewDF = Function::Create(SF->getFunctionType(), NewLinkage,
1020 SF->getName(), Dest);
1021 CopyGVAttributes(NewDF, SF);
1023 // Any uses of DF need to change to NewDF, with cast
1024 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF,
1027 // DF will conflict with NewDF because they both had the same. We must
1028 // erase this now so ForceRenaming doesn't assert because DF might
1029 // not have internal linkage.
1030 if (GlobalVariable *Var = dyn_cast<GlobalVariable>(DGV))
1031 Var->eraseFromParent();
1033 cast<Function>(DGV)->eraseFromParent();
1035 // If the symbol table renamed the function, but it is an externally
1036 // visible symbol, DF must be an existing function with internal
1037 // linkage. Rename it.
1038 if (NewDF->getName() != SF->getName() && !NewDF->hasLocalLinkage())
1039 ForceRenaming(NewDF, SF->getName());
1041 // Remember this mapping so uses in the source module get remapped
1042 // later by RemapOperand.
1043 ValueMap[SF] = NewDF;
1047 // Not "link from source", keep the one in the DestModule and remap the
1050 if (isa<GlobalAlias>(DGV)) {
1051 // The only valid mappings are:
1052 // - SF is external declaration, which is effectively a no-op.
1053 // - SF is weak, when we just need to throw SF out.
1054 if (!SF->isDeclaration() && !SF->isWeakForLinker())
1055 return Error(Err, "Function-Alias Collision on '" + SF->getName() +
1056 "': symbol multiple defined");
1059 // Set calculated linkage
1060 DGV->setLinkage(NewLinkage);
1062 // Make sure to remember this mapping.
1063 ValueMap[SF] = ConstantExpr::getBitCast(DGV, SF->getType());
1068 // LinkFunctionBody - Copy the source function over into the dest function and
1069 // fix up references to values. At this point we know that Dest is an external
1070 // function, and that Src is not.
1071 static bool LinkFunctionBody(Function *Dest, Function *Src,
1072 std::map<const Value*, Value*> &ValueMap,
1074 assert(Src && Dest && Dest->isDeclaration() && !Src->isDeclaration());
1076 // Go through and convert function arguments over, remembering the mapping.
1077 Function::arg_iterator DI = Dest->arg_begin();
1078 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1079 I != E; ++I, ++DI) {
1080 DI->setName(I->getName()); // Copy the name information over...
1082 // Add a mapping to our local map
1086 // Splice the body of the source function into the dest function.
1087 Dest->getBasicBlockList().splice(Dest->end(), Src->getBasicBlockList());
1089 // At this point, all of the instructions and values of the function are now
1090 // copied over. The only problem is that they are still referencing values in
1091 // the Source function as operands. Loop through all of the operands of the
1092 // functions and patch them up to point to the local versions...
1094 for (Function::iterator BB = Dest->begin(), BE = Dest->end(); BB != BE; ++BB)
1095 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
1096 for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end();
1098 if (!isa<Instruction>(*OI) && !isa<BasicBlock>(*OI))
1099 *OI = RemapOperand(*OI, ValueMap);
1101 // There is no need to map the arguments anymore.
1102 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
1110 // LinkFunctionBodies - Link in the function bodies that are defined in the
1111 // source module into the DestModule. This consists basically of copying the
1112 // function over and fixing up references to values.
1113 static bool LinkFunctionBodies(Module *Dest, Module *Src,
1114 std::map<const Value*, Value*> &ValueMap,
1117 // Loop over all of the functions in the src module, mapping them over as we
1119 for (Module::iterator SF = Src->begin(), E = Src->end(); SF != E; ++SF) {
1120 if (!SF->isDeclaration()) { // No body if function is external
1121 Function *DF = dyn_cast<Function>(ValueMap[SF]); // Destination function
1123 // DF not external SF external?
1124 if (DF && DF->isDeclaration())
1125 // Only provide the function body if there isn't one already.
1126 if (LinkFunctionBody(DF, SF, ValueMap, Err))
1133 // LinkAppendingVars - If there were any appending global variables, link them
1134 // together now. Return true on error.
1135 static bool LinkAppendingVars(Module *M,
1136 std::multimap<std::string, GlobalVariable *> &AppendingVars,
1137 std::string *ErrorMsg) {
1138 if (AppendingVars.empty()) return false; // Nothing to do.
1140 // Loop over the multimap of appending vars, processing any variables with the
1141 // same name, forming a new appending global variable with both of the
1142 // initializers merged together, then rewrite references to the old variables
1144 std::vector<Constant*> Inits;
1145 while (AppendingVars.size() > 1) {
1146 // Get the first two elements in the map...
1147 std::multimap<std::string,
1148 GlobalVariable*>::iterator Second = AppendingVars.begin(), First=Second++;
1150 // If the first two elements are for different names, there is no pair...
1151 // Otherwise there is a pair, so link them together...
1152 if (First->first == Second->first) {
1153 GlobalVariable *G1 = First->second, *G2 = Second->second;
1154 const ArrayType *T1 = cast<ArrayType>(G1->getType()->getElementType());
1155 const ArrayType *T2 = cast<ArrayType>(G2->getType()->getElementType());
1157 // Check to see that they two arrays agree on type...
1158 if (T1->getElementType() != T2->getElementType())
1159 return Error(ErrorMsg,
1160 "Appending variables with different element types need to be linked!");
1161 if (G1->isConstant() != G2->isConstant())
1162 return Error(ErrorMsg,
1163 "Appending variables linked with different const'ness!");
1165 if (G1->getAlignment() != G2->getAlignment())
1166 return Error(ErrorMsg,
1167 "Appending variables with different alignment need to be linked!");
1169 if (G1->getVisibility() != G2->getVisibility())
1170 return Error(ErrorMsg,
1171 "Appending variables with different visibility need to be linked!");
1173 if (G1->getSection() != G2->getSection())
1174 return Error(ErrorMsg,
1175 "Appending variables with different section name need to be linked!");
1177 unsigned NewSize = T1->getNumElements() + T2->getNumElements();
1178 ArrayType *NewType = ArrayType::get(T1->getElementType(),
1181 G1->setName(""); // Clear G1's name in case of a conflict!
1183 // Create the new global variable...
1184 GlobalVariable *NG =
1185 new GlobalVariable(*M, NewType, G1->isConstant(), G1->getLinkage(),
1186 /*init*/0, First->first, 0, G1->isThreadLocal(),
1187 G1->getType()->getAddressSpace());
1189 // Propagate alignment, visibility and section info.
1190 CopyGVAttributes(NG, G1);
1192 // Merge the initializer...
1193 Inits.reserve(NewSize);
1194 if (ConstantArray *I = dyn_cast<ConstantArray>(G1->getInitializer())) {
1195 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i)
1196 Inits.push_back(I->getOperand(i));
1198 assert(isa<ConstantAggregateZero>(G1->getInitializer()));
1199 Constant *CV = Constant::getNullValue(T1->getElementType());
1200 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i)
1201 Inits.push_back(CV);
1203 if (ConstantArray *I = dyn_cast<ConstantArray>(G2->getInitializer())) {
1204 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i)
1205 Inits.push_back(I->getOperand(i));
1207 assert(isa<ConstantAggregateZero>(G2->getInitializer()));
1208 Constant *CV = Constant::getNullValue(T2->getElementType());
1209 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i)
1210 Inits.push_back(CV);
1212 NG->setInitializer(ConstantArray::get(NewType, Inits));
1215 // Replace any uses of the two global variables with uses of the new
1218 // FIXME: This should rewrite simple/straight-forward uses such as
1219 // getelementptr instructions to not use the Cast!
1220 G1->replaceAllUsesWith(ConstantExpr::getBitCast(NG,
1222 G2->replaceAllUsesWith(ConstantExpr::getBitCast(NG,
1225 // Remove the two globals from the module now...
1226 M->getGlobalList().erase(G1);
1227 M->getGlobalList().erase(G2);
1229 // Put the new global into the AppendingVars map so that we can handle
1230 // linking of more than two vars...
1231 Second->second = NG;
1233 AppendingVars.erase(First);
1239 static bool ResolveAliases(Module *Dest) {
1240 for (Module::alias_iterator I = Dest->alias_begin(), E = Dest->alias_end();
1242 // We can't sue resolveGlobalAlias here because we need to preserve
1243 // bitcasts and GEPs.
1244 if (const Constant *C = I->getAliasee()) {
1245 while (dyn_cast<GlobalAlias>(C))
1246 C = cast<GlobalAlias>(C)->getAliasee();
1247 const GlobalValue *GV = dyn_cast<GlobalValue>(C);
1248 if (C != I && !(GV && GV->isDeclaration()))
1249 I->replaceAllUsesWith(const_cast<Constant*>(C));
1255 // LinkModules - This function links two modules together, with the resulting
1256 // left module modified to be the composite of the two input modules. If an
1257 // error occurs, true is returned and ErrorMsg (if not null) is set to indicate
1258 // the problem. Upon failure, the Dest module could be in a modified state, and
1259 // shouldn't be relied on to be consistent.
1261 Linker::LinkModules(Module *Dest, Module *Src, std::string *ErrorMsg) {
1262 assert(Dest != 0 && "Invalid Destination module");
1263 assert(Src != 0 && "Invalid Source Module");
1265 if (Dest->getDataLayout().empty()) {
1266 if (!Src->getDataLayout().empty()) {
1267 Dest->setDataLayout(Src->getDataLayout());
1269 std::string DataLayout;
1271 if (Dest->getEndianness() == Module::AnyEndianness) {
1272 if (Src->getEndianness() == Module::BigEndian)
1273 DataLayout.append("E");
1274 else if (Src->getEndianness() == Module::LittleEndian)
1275 DataLayout.append("e");
1278 if (Dest->getPointerSize() == Module::AnyPointerSize) {
1279 if (Src->getPointerSize() == Module::Pointer64)
1280 DataLayout.append(DataLayout.length() == 0 ? "p:64:64" : "-p:64:64");
1281 else if (Src->getPointerSize() == Module::Pointer32)
1282 DataLayout.append(DataLayout.length() == 0 ? "p:32:32" : "-p:32:32");
1284 Dest->setDataLayout(DataLayout);
1288 // Copy the target triple from the source to dest if the dest's is empty.
1289 if (Dest->getTargetTriple().empty() && !Src->getTargetTriple().empty())
1290 Dest->setTargetTriple(Src->getTargetTriple());
1292 if (!Src->getDataLayout().empty() && !Dest->getDataLayout().empty() &&
1293 Src->getDataLayout() != Dest->getDataLayout())
1294 errs() << "WARNING: Linking two modules of different data layouts!\n";
1295 if (!Src->getTargetTriple().empty() &&
1296 Dest->getTargetTriple() != Src->getTargetTriple())
1297 errs() << "WARNING: Linking two modules of different target triples!\n";
1299 // Append the module inline asm string.
1300 if (!Src->getModuleInlineAsm().empty()) {
1301 if (Dest->getModuleInlineAsm().empty())
1302 Dest->setModuleInlineAsm(Src->getModuleInlineAsm());
1304 Dest->setModuleInlineAsm(Dest->getModuleInlineAsm()+"\n"+
1305 Src->getModuleInlineAsm());
1308 // Update the destination module's dependent libraries list with the libraries
1309 // from the source module. There's no opportunity for duplicates here as the
1310 // Module ensures that duplicate insertions are discarded.
1311 for (Module::lib_iterator SI = Src->lib_begin(), SE = Src->lib_end();
1313 Dest->addLibrary(*SI);
1315 // LinkTypes - Go through the symbol table of the Src module and see if any
1316 // types are named in the src module that are not named in the Dst module.
1317 // Make sure there are no type name conflicts.
1318 if (LinkTypes(Dest, Src, ErrorMsg))
1321 // ValueMap - Mapping of values from what they used to be in Src, to what they
1323 std::map<const Value*, Value*> ValueMap;
1325 // AppendingVars - Keep track of global variables in the destination module
1326 // with appending linkage. After the module is linked together, they are
1327 // appended and the module is rewritten.
1328 std::multimap<std::string, GlobalVariable *> AppendingVars;
1329 for (Module::global_iterator I = Dest->global_begin(), E = Dest->global_end();
1331 // Add all of the appending globals already in the Dest module to
1333 if (I->hasAppendingLinkage())
1334 AppendingVars.insert(std::make_pair(I->getName(), I));
1337 // Insert all of the named mdnoes in Src into the Dest module.
1338 LinkNamedMDNodes(Dest, Src);
1340 // Insert all of the globals in src into the Dest module... without linking
1341 // initializers (which could refer to functions not yet mapped over).
1342 if (LinkGlobals(Dest, Src, ValueMap, AppendingVars, ErrorMsg))
1345 // Link the functions together between the two modules, without doing function
1346 // bodies... this just adds external function prototypes to the Dest
1347 // function... We do this so that when we begin processing function bodies,
1348 // all of the global values that may be referenced are available in our
1350 if (LinkFunctionProtos(Dest, Src, ValueMap, ErrorMsg))
1353 // If there were any alias, link them now. We really need to do this now,
1354 // because all of the aliases that may be referenced need to be available in
1356 if (LinkAlias(Dest, Src, ValueMap, ErrorMsg)) return true;
1358 // Update the initializers in the Dest module now that all globals that may
1359 // be referenced are in Dest.
1360 if (LinkGlobalInits(Dest, Src, ValueMap, ErrorMsg)) return true;
1362 // Link in the function bodies that are defined in the source module into the
1363 // DestModule. This consists basically of copying the function over and
1364 // fixing up references to values.
1365 if (LinkFunctionBodies(Dest, Src, ValueMap, ErrorMsg)) return true;
1367 // If there were any appending global variables, link them together now.
1368 if (LinkAppendingVars(Dest, AppendingVars, ErrorMsg)) return true;
1370 // Resolve all uses of aliases with aliasees
1371 if (ResolveAliases(Dest)) return true;
1373 // If the source library's module id is in the dependent library list of the
1374 // destination library, remove it since that module is now linked in.
1376 modId.set(Src->getModuleIdentifier());
1377 if (!modId.isEmpty())
1378 Dest->removeLibrary(modId.getBasename());