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.insert(std::make_pair(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 // Propagate alignment, visibility and section info.
355 DestGV->setAlignment(std::max(DestGV->getAlignment(), SrcGV->getAlignment()));
356 DestGV->setSection(SrcGV->getSection());
357 DestGV->setVisibility(SrcGV->getVisibility());
358 if (const Function *SrcF = dyn_cast<Function>(SrcGV)) {
359 Function *DestF = cast<Function>(DestGV);
360 DestF->setCallingConv(SrcF->getCallingConv());
361 DestF->setParamAttrs(SrcF->getParamAttrs());
362 if (SrcF->hasCollector())
363 DestF->setCollector(SrcF->getCollector());
364 } else if (const GlobalVariable *SrcVar = dyn_cast<GlobalVariable>(SrcGV)) {
365 GlobalVariable *DestVar = cast<GlobalVariable>(DestGV);
366 DestVar->setThreadLocal(SrcVar->isThreadLocal());
370 /// GetLinkageResult - This analyzes the two global values and determines what
371 /// the result will look like in the destination module. In particular, it
372 /// computes the resultant linkage type, computes whether the global in the
373 /// source should be copied over to the destination (replacing the existing
374 /// one), and computes whether this linkage is an error or not. It also performs
375 /// visibility checks: we cannot link together two symbols with different
377 static bool GetLinkageResult(GlobalValue *Dest, GlobalValue *Src,
378 GlobalValue::LinkageTypes <, bool &LinkFromSrc,
380 assert((!Dest || !Src->hasInternalLinkage()) &&
381 "If Src has internal linkage, Dest shouldn't be set!");
383 // Linking something to nothing.
385 LT = Src->getLinkage();
386 } else if (Src->isDeclaration()) {
387 // If Src is external or if both Src & Drc are external.. Just link the
388 // external globals, we aren't adding anything.
389 if (Src->hasDLLImportLinkage()) {
390 // If one of GVs has DLLImport linkage, result should be dllimport'ed.
391 if (Dest->isDeclaration()) {
393 LT = Src->getLinkage();
395 } else if (Dest->hasExternalWeakLinkage()) {
396 //If the Dest is weak, use the source linkage
398 LT = Src->getLinkage();
401 LT = Dest->getLinkage();
403 } else if (Dest->isDeclaration() && !Dest->hasDLLImportLinkage()) {
404 // If Dest is external but Src is not:
406 LT = Src->getLinkage();
407 } else if (Src->hasAppendingLinkage() || Dest->hasAppendingLinkage()) {
408 if (Src->getLinkage() != Dest->getLinkage())
409 return Error(Err, "Linking globals named '" + Src->getName() +
410 "': can only link appending global with another appending global!");
411 LinkFromSrc = true; // Special cased.
412 LT = Src->getLinkage();
413 } else if (Src->hasWeakLinkage() || Src->hasLinkOnceLinkage()) {
414 // At this point we know that Dest has LinkOnce, External*, Weak, or
416 if ((Dest->hasLinkOnceLinkage() && Src->hasWeakLinkage()) ||
417 Dest->hasExternalWeakLinkage()) {
419 LT = Src->getLinkage();
422 LT = Dest->getLinkage();
424 } else if (Dest->hasWeakLinkage() || Dest->hasLinkOnceLinkage()) {
425 // At this point we know that Src has External* or DLL* linkage.
426 if (Src->hasExternalWeakLinkage()) {
428 LT = Dest->getLinkage();
431 LT = GlobalValue::ExternalLinkage;
434 assert((Dest->hasExternalLinkage() ||
435 Dest->hasDLLImportLinkage() ||
436 Dest->hasDLLExportLinkage() ||
437 Dest->hasExternalWeakLinkage()) &&
438 (Src->hasExternalLinkage() ||
439 Src->hasDLLImportLinkage() ||
440 Src->hasDLLExportLinkage() ||
441 Src->hasExternalWeakLinkage()) &&
442 "Unexpected linkage type!");
443 return Error(Err, "Linking globals named '" + Src->getName() +
444 "': symbol multiply defined!");
448 if (Dest && Src->getVisibility() != Dest->getVisibility())
449 if (!Src->isDeclaration() && !Dest->isDeclaration())
450 return Error(Err, "Linking globals named '" + Src->getName() +
451 "': symbols have different visibilities!");
455 // LinkGlobals - Loop through the global variables in the src module and merge
456 // them into the dest module.
457 static bool LinkGlobals(Module *Dest, Module *Src,
458 std::map<const Value*, Value*> &ValueMap,
459 std::multimap<std::string, GlobalVariable *> &AppendingVars,
461 // Loop over all of the globals in the src module, mapping them over as we go
462 for (Module::global_iterator I = Src->global_begin(), E = Src->global_end();
464 GlobalVariable *SGV = I;
465 GlobalVariable *DGV = 0;
466 // Check to see if may have to link the global.
467 if (SGV->hasName() && !SGV->hasInternalLinkage()) {
468 DGV = Dest->getGlobalVariable(SGV->getName());
469 if (DGV && DGV->getType() != SGV->getType())
470 // If types don't agree due to opaque types, try to resolve them.
471 RecursiveResolveTypes(SGV->getType(), DGV->getType(),
472 &Dest->getTypeSymbolTable(), "");
475 if (DGV && DGV->hasInternalLinkage())
478 assert((SGV->hasInitializer() || SGV->hasExternalWeakLinkage() ||
479 SGV->hasExternalLinkage() || SGV->hasDLLImportLinkage()) &&
480 "Global must either be external or have an initializer!");
482 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
483 bool LinkFromSrc = false;
484 if (GetLinkageResult(DGV, SGV, NewLinkage, LinkFromSrc, Err))
488 // No linking to be performed, simply create an identical version of the
489 // symbol over in the dest module... the initializer will be filled in
490 // later by LinkGlobalInits...
491 GlobalVariable *NewDGV =
492 new GlobalVariable(SGV->getType()->getElementType(),
493 SGV->isConstant(), SGV->getLinkage(), /*init*/0,
494 SGV->getName(), Dest);
495 // Propagate alignment, visibility and section info.
496 CopyGVAttributes(NewDGV, SGV);
498 // If the LLVM runtime renamed the global, but it is an externally visible
499 // symbol, DGV must be an existing global with internal linkage. Rename
501 if (NewDGV->getName() != SGV->getName() && !NewDGV->hasInternalLinkage())
502 ForceRenaming(NewDGV, SGV->getName());
504 // Make sure to remember this mapping...
505 ValueMap.insert(std::make_pair(SGV, NewDGV));
506 if (SGV->hasAppendingLinkage())
507 // Keep track that this is an appending variable...
508 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV));
509 } else if (DGV->hasAppendingLinkage()) {
510 // No linking is performed yet. Just insert a new copy of the global, and
511 // keep track of the fact that it is an appending variable in the
512 // AppendingVars map. The name is cleared out so that no linkage is
514 GlobalVariable *NewDGV =
515 new GlobalVariable(SGV->getType()->getElementType(),
516 SGV->isConstant(), SGV->getLinkage(), /*init*/0,
519 // Propagate alignment, section and visibility info.
520 NewDGV->setAlignment(DGV->getAlignment());
521 CopyGVAttributes(NewDGV, SGV);
523 // Make sure to remember this mapping...
524 ValueMap.insert(std::make_pair(SGV, NewDGV));
526 // Keep track that this is an appending variable...
527 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV));
529 // Otherwise, perform the mapping as instructed by GetLinkageResult.
531 // Propagate alignment, section, and visibility info.
532 CopyGVAttributes(DGV, SGV);
534 // If the types don't match, and if we are to link from the source, nuke
535 // DGV and create a new one of the appropriate type.
536 if (SGV->getType() != DGV->getType() && LinkFromSrc) {
537 GlobalVariable *NewDGV =
538 new GlobalVariable(SGV->getType()->getElementType(),
539 DGV->isConstant(), DGV->getLinkage());
540 CopyGVAttributes(NewDGV, DGV);
541 Dest->getGlobalList().insert(DGV, NewDGV);
542 DGV->replaceAllUsesWith(
543 ConstantExpr::getBitCast(NewDGV, DGV->getType()));
544 DGV->eraseFromParent();
545 NewDGV->setName(SGV->getName());
549 DGV->setLinkage(NewLinkage);
552 // Inherit const as appropriate
553 DGV->setConstant(SGV->isConstant());
554 DGV->setInitializer(0);
556 if (SGV->isConstant() && !DGV->isConstant()) {
557 if (DGV->isDeclaration())
558 DGV->setConstant(true);
560 SGV->setLinkage(GlobalValue::ExternalLinkage);
561 SGV->setInitializer(0);
565 std::make_pair(SGV, ConstantExpr::getBitCast(DGV, SGV->getType())));
571 static GlobalValue::LinkageTypes
572 CalculateAliasLinkage(const GlobalValue *SGV, const GlobalValue *DGV) {
573 if (SGV->hasExternalLinkage() || DGV->hasExternalLinkage())
574 return GlobalValue::ExternalLinkage;
575 else if (SGV->hasWeakLinkage() || DGV->hasWeakLinkage())
576 return GlobalValue::WeakLinkage;
578 assert(SGV->hasInternalLinkage() && DGV->hasInternalLinkage() &&
579 "Unexpected linkage type");
580 return GlobalValue::InternalLinkage;
584 // LinkAlias - Loop through the alias in the src module and link them into the
585 // dest module. We're assuming, that all functions/global variables were already
587 static bool LinkAlias(Module *Dest, const Module *Src,
588 std::map<const Value*, Value*> &ValueMap,
590 // Loop over all alias in the src module
591 for (Module::const_alias_iterator I = Src->alias_begin(),
592 E = Src->alias_end(); I != E; ++I) {
593 const GlobalAlias *SGA = I;
594 const GlobalValue *SAliasee = SGA->getAliasedGlobal();
595 GlobalAlias *NewGA = NULL;
597 // Globals were already linked, thus we can just query ValueMap for variant
598 // of SAliasee in Dest
599 std::map<const Value*,Value*>::const_iterator I = ValueMap.find(SAliasee);
600 assert(I != ValueMap.end() && "Aliasee not linked");
601 GlobalValue* DAliasee = cast<GlobalValue>(I->second);
603 // Try to find something 'similar' to SGA in destination module.
604 if (GlobalAlias *DGA = Dest->getNamedAlias(SGA->getName())) {
605 // If types don't agree due to opaque types, try to resolve them.
606 if (RecursiveResolveTypes(SGA->getType(), DGA->getType(),
607 &Dest->getTypeSymbolTable(), ""))
608 return Error(Err, "Alias Collision on '" +
609 ToStr(SGA->getType(), Src) +"':%"+SGA->getName()+
610 " - aliases have different types");
612 // Now types are known to be the same, check whether aliasees equal. As
613 // globals are already linked we just need query ValueMap to find the
615 if (DAliasee == DGA->getAliasedGlobal()) {
616 // This is just two copies of the same alias. Propagate linkage, if
618 DGA->setLinkage(CalculateAliasLinkage(SGA, DGA));
621 // Proceed to 'common' steps
623 return Error(Err, "Alias Collision on '" +
624 ToStr(SGA->getType(), Src) +"':%"+SGA->getName()+
625 " - aliases have different aliasees");
626 } else if (GlobalVariable *DGV = Dest->getGlobalVariable(SGA->getName())) {
627 RecursiveResolveTypes(SGA->getType(), DGV->getType(),
628 &Dest->getTypeSymbolTable(), "");
630 // The only allowed way is to link alias with external declaration.
631 if (DGV->isDeclaration()) {
632 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(),
633 SGA->getName(), DAliasee, Dest);
634 CopyGVAttributes(NewGA, SGA);
636 // Any uses of DGV need to change to NewGA, with cast, if needed.
637 if (SGA->getType() != DGV->getType())
638 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewGA,
641 DGV->replaceAllUsesWith(NewGA);
643 // DGV will conflict with NewGA because they both had the same
644 // name. We must erase this now so ForceRenaming doesn't assert
645 // because DGV might not have internal linkage.
646 DGV->eraseFromParent();
648 // Proceed to 'common' steps
650 return Error(Err, "Alias Collision on '" +
651 ToStr(SGA->getType(), Src) +"':%"+SGA->getName()+
652 " - symbol multiple defined");
653 } else if (Function *DF = Dest->getFunction(SGA->getName())) {
654 RecursiveResolveTypes(SGA->getType(), DF->getType(),
655 &Dest->getTypeSymbolTable(), "");
657 // The only allowed way is to link alias with external declaration.
658 if (DF->isDeclaration()) {
659 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(),
660 SGA->getName(), DAliasee, Dest);
661 CopyGVAttributes(NewGA, SGA);
663 // Any uses of DF need to change to NewGA, with cast, if needed.
664 if (SGA->getType() != DF->getType())
665 DF->replaceAllUsesWith(ConstantExpr::getBitCast(NewGA,
668 DF->replaceAllUsesWith(NewGA);
670 // DF will conflict with NewGA because they both had the same
671 // name. We must erase this now so ForceRenaming doesn't assert
672 // because DF might not have internal linkage.
673 DF->eraseFromParent();
675 // Proceed to 'common' steps
677 return Error(Err, "Alias Collision on '" +
678 ToStr(SGA->getType(), Src) +"':%"+SGA->getName()+
679 " - symbol multiple defined");
681 // Nothing similar found, just copy alias into destination module.
683 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(),
684 SGA->getName(), DAliasee, Dest);
685 CopyGVAttributes(NewGA, SGA);
687 // Proceed to 'common' steps
690 assert(NewGA && "No alias was created in destination module!");
692 // If the symbol table renamed the function, but it is an externally
693 // visible symbol, DGV must be an existing function with internal
694 // linkage. Rename it.
695 if (NewGA->getName() != SGA->getName() &&
696 !NewGA->hasInternalLinkage())
697 ForceRenaming(NewGA, SGA->getName());
699 // Remember this mapping so uses in the source module get remapped
700 // later by RemapOperand.
701 ValueMap.insert(std::make_pair(SGA, NewGA));
708 // LinkGlobalInits - Update the initializers in the Dest module now that all
709 // globals that may be referenced are in Dest.
710 static bool LinkGlobalInits(Module *Dest, const Module *Src,
711 std::map<const Value*, Value*> &ValueMap,
714 // Loop over all of the globals in the src module, mapping them over as we go
715 for (Module::const_global_iterator I = Src->global_begin(),
716 E = Src->global_end(); I != E; ++I) {
717 const GlobalVariable *SGV = I;
719 if (SGV->hasInitializer()) { // Only process initialized GV's
720 // Figure out what the initializer looks like in the dest module...
722 cast<Constant>(RemapOperand(SGV->getInitializer(), ValueMap));
724 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[SGV]);
725 if (DGV->hasInitializer()) {
726 if (SGV->hasExternalLinkage()) {
727 if (DGV->getInitializer() != SInit)
728 return Error(Err, "Global Variable Collision on '" +
729 ToStr(SGV->getType(), Src) +"':%"+SGV->getName()+
730 " - Global variables have different initializers");
731 } else if (DGV->hasLinkOnceLinkage() || DGV->hasWeakLinkage()) {
732 // Nothing is required, mapped values will take the new global
734 } else if (SGV->hasLinkOnceLinkage() || SGV->hasWeakLinkage()) {
735 // Nothing is required, mapped values will take the new global
737 } else if (DGV->hasAppendingLinkage()) {
738 assert(0 && "Appending linkage unimplemented!");
740 assert(0 && "Unknown linkage!");
743 // Copy the initializer over now...
744 DGV->setInitializer(SInit);
751 // LinkFunctionProtos - Link the functions together between the two modules,
752 // without doing function bodies... this just adds external function prototypes
753 // to the Dest function...
755 static bool LinkFunctionProtos(Module *Dest, const Module *Src,
756 std::map<const Value*, Value*> &ValueMap,
758 // Loop over all of the functions in the src module, mapping them over
759 for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) {
760 const Function *SF = I; // SrcFunction
762 if (SF->hasName() && !SF->hasInternalLinkage()) {
763 // Check to see if may have to link the function.
764 DF = Dest->getFunction(SF->getName());
765 if (DF && SF->getType() != DF->getType())
766 // If types don't agree because of opaque, try to resolve them
767 RecursiveResolveTypes(SF->getType(), DF->getType(),
768 &Dest->getTypeSymbolTable(), "");
772 if (DF && !DF->hasInternalLinkage() &&
773 SF->getVisibility() != DF->getVisibility()) {
774 // If one is a prototype, ignore its visibility. Prototypes are always
775 // overridden by the definition.
776 if (!SF->isDeclaration() && !DF->isDeclaration())
777 return Error(Err, "Linking functions named '" + SF->getName() +
778 "': symbols have different visibilities!");
781 if (DF && DF->hasInternalLinkage())
784 if (DF && DF->getType() != SF->getType()) {
785 if (DF->isDeclaration() && !SF->isDeclaration()) {
786 // We have a definition of the same name but different type in the
787 // source module. Copy the prototype to the destination and replace
788 // uses of the destination's prototype with the new prototype.
789 Function *NewDF = new Function(SF->getFunctionType(), SF->getLinkage(),
790 SF->getName(), Dest);
791 CopyGVAttributes(NewDF, SF);
793 // Any uses of DF need to change to NewDF, with cast
794 DF->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, DF->getType()));
796 // DF will conflict with NewDF because they both had the same. We must
797 // erase this now so ForceRenaming doesn't assert because DF might
798 // not have internal linkage.
799 DF->eraseFromParent();
801 // If the symbol table renamed the function, but it is an externally
802 // visible symbol, DF must be an existing function with internal
803 // linkage. Rename it.
804 if (NewDF->getName() != SF->getName() && !NewDF->hasInternalLinkage())
805 ForceRenaming(NewDF, SF->getName());
807 // Remember this mapping so uses in the source module get remapped
808 // later by RemapOperand.
809 ValueMap[SF] = NewDF;
810 } else if (SF->isDeclaration()) {
811 // We have two functions of the same name but different type and the
812 // source is a declaration while the destination is not. Any use of
813 // the source must be mapped to the destination, with a cast.
814 ValueMap[SF] = ConstantExpr::getBitCast(DF, SF->getType());
816 // We have two functions of the same name but different types and they
817 // are both definitions. This is an error.
818 return Error(Err, "Function '" + DF->getName() + "' defined as both '" +
819 ToStr(SF->getFunctionType(), Src) + "' and '" +
820 ToStr(DF->getFunctionType(), Dest) + "'");
822 } else if (!DF || SF->hasInternalLinkage() || DF->hasInternalLinkage()) {
823 // Function does not already exist, simply insert an function signature
824 // identical to SF into the dest module.
825 Function *NewDF = new Function(SF->getFunctionType(), SF->getLinkage(),
826 SF->getName(), Dest);
827 CopyGVAttributes(NewDF, SF);
829 // If the LLVM runtime renamed the function, but it is an externally
830 // visible symbol, DF must be an existing function with internal linkage.
832 if (NewDF->getName() != SF->getName() && !NewDF->hasInternalLinkage())
833 ForceRenaming(NewDF, SF->getName());
835 // ... and remember this mapping...
836 ValueMap.insert(std::make_pair(SF, NewDF));
837 } else if (SF->isDeclaration()) {
838 // If SF is a declaration or if both SF & DF are declarations, just link
839 // the declarations, we aren't adding anything.
840 if (SF->hasDLLImportLinkage()) {
841 if (DF->isDeclaration()) {
842 ValueMap.insert(std::make_pair(SF, DF));
843 DF->setLinkage(SF->getLinkage());
846 ValueMap.insert(std::make_pair(SF, DF));
848 } else if (DF->isDeclaration() && !DF->hasDLLImportLinkage()) {
849 // If DF is external but SF is not...
850 // Link the external functions, update linkage qualifiers
851 ValueMap.insert(std::make_pair(SF, DF));
852 DF->setLinkage(SF->getLinkage());
853 // Visibility of prototype is overridden by vis of definition.
854 DF->setVisibility(SF->getVisibility());
855 } else if (SF->hasWeakLinkage() || SF->hasLinkOnceLinkage()) {
856 // At this point we know that DF has LinkOnce, Weak, or External* linkage.
857 ValueMap.insert(std::make_pair(SF, DF));
859 // Linkonce+Weak = Weak
860 // *+External Weak = *
861 if ((DF->hasLinkOnceLinkage() && SF->hasWeakLinkage()) ||
862 DF->hasExternalWeakLinkage())
863 DF->setLinkage(SF->getLinkage());
864 } else if (DF->hasWeakLinkage() || DF->hasLinkOnceLinkage()) {
865 // At this point we know that SF has LinkOnce or External* linkage.
866 ValueMap.insert(std::make_pair(SF, DF));
867 if (!SF->hasLinkOnceLinkage() && !SF->hasExternalWeakLinkage())
868 // Don't inherit linkonce & external weak linkage
869 DF->setLinkage(SF->getLinkage());
870 } else if (SF->getLinkage() != DF->getLinkage()) {
871 return Error(Err, "Functions named '" + SF->getName() +
872 "' have different linkage specifiers!");
873 } else if (SF->hasExternalLinkage()) {
874 // The function is defined identically in both modules!!
875 return Error(Err, "Function '" +
876 ToStr(SF->getFunctionType(), Src) + "':\"" +
877 SF->getName() + "\" - Function is already defined!");
879 assert(0 && "Unknown linkage configuration found!");
885 // LinkFunctionBody - Copy the source function over into the dest function and
886 // fix up references to values. At this point we know that Dest is an external
887 // function, and that Src is not.
888 static bool LinkFunctionBody(Function *Dest, Function *Src,
889 std::map<const Value*, Value*> &ValueMap,
891 assert(Src && Dest && Dest->isDeclaration() && !Src->isDeclaration());
893 // Go through and convert function arguments over, remembering the mapping.
894 Function::arg_iterator DI = Dest->arg_begin();
895 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
897 DI->setName(I->getName()); // Copy the name information over...
899 // Add a mapping to our local map
900 ValueMap.insert(std::make_pair(I, DI));
903 // Splice the body of the source function into the dest function.
904 Dest->getBasicBlockList().splice(Dest->end(), Src->getBasicBlockList());
906 // At this point, all of the instructions and values of the function are now
907 // copied over. The only problem is that they are still referencing values in
908 // the Source function as operands. Loop through all of the operands of the
909 // functions and patch them up to point to the local versions...
911 for (Function::iterator BB = Dest->begin(), BE = Dest->end(); BB != BE; ++BB)
912 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
913 for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end();
915 if (!isa<Instruction>(*OI) && !isa<BasicBlock>(*OI))
916 *OI = RemapOperand(*OI, ValueMap);
918 // There is no need to map the arguments anymore.
919 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
927 // LinkFunctionBodies - Link in the function bodies that are defined in the
928 // source module into the DestModule. This consists basically of copying the
929 // function over and fixing up references to values.
930 static bool LinkFunctionBodies(Module *Dest, Module *Src,
931 std::map<const Value*, Value*> &ValueMap,
934 // Loop over all of the functions in the src module, mapping them over as we
936 for (Module::iterator SF = Src->begin(), E = Src->end(); SF != E; ++SF) {
937 if (!SF->isDeclaration()) { // No body if function is external
938 Function *DF = cast<Function>(ValueMap[SF]); // Destination function
940 // DF not external SF external?
941 if (DF->isDeclaration())
942 // Only provide the function body if there isn't one already.
943 if (LinkFunctionBody(DF, SF, ValueMap, Err))
950 // LinkAppendingVars - If there were any appending global variables, link them
951 // together now. Return true on error.
952 static bool LinkAppendingVars(Module *M,
953 std::multimap<std::string, GlobalVariable *> &AppendingVars,
954 std::string *ErrorMsg) {
955 if (AppendingVars.empty()) return false; // Nothing to do.
957 // Loop over the multimap of appending vars, processing any variables with the
958 // same name, forming a new appending global variable with both of the
959 // initializers merged together, then rewrite references to the old variables
961 std::vector<Constant*> Inits;
962 while (AppendingVars.size() > 1) {
963 // Get the first two elements in the map...
964 std::multimap<std::string,
965 GlobalVariable*>::iterator Second = AppendingVars.begin(), First=Second++;
967 // If the first two elements are for different names, there is no pair...
968 // Otherwise there is a pair, so link them together...
969 if (First->first == Second->first) {
970 GlobalVariable *G1 = First->second, *G2 = Second->second;
971 const ArrayType *T1 = cast<ArrayType>(G1->getType()->getElementType());
972 const ArrayType *T2 = cast<ArrayType>(G2->getType()->getElementType());
974 // Check to see that they two arrays agree on type...
975 if (T1->getElementType() != T2->getElementType())
976 return Error(ErrorMsg,
977 "Appending variables with different element types need to be linked!");
978 if (G1->isConstant() != G2->isConstant())
979 return Error(ErrorMsg,
980 "Appending variables linked with different const'ness!");
982 if (G1->getAlignment() != G2->getAlignment())
983 return Error(ErrorMsg,
984 "Appending variables with different alignment need to be linked!");
986 if (G1->getVisibility() != G2->getVisibility())
987 return Error(ErrorMsg,
988 "Appending variables with different visibility need to be linked!");
990 if (G1->getSection() != G2->getSection())
991 return Error(ErrorMsg,
992 "Appending variables with different section name need to be linked!");
994 unsigned NewSize = T1->getNumElements() + T2->getNumElements();
995 ArrayType *NewType = ArrayType::get(T1->getElementType(), NewSize);
997 G1->setName(""); // Clear G1's name in case of a conflict!
999 // Create the new global variable...
1000 GlobalVariable *NG =
1001 new GlobalVariable(NewType, G1->isConstant(), G1->getLinkage(),
1002 /*init*/0, First->first, M, G1->isThreadLocal());
1004 // Propagate alignment, visibility and section info.
1005 CopyGVAttributes(NG, G1);
1007 // Merge the initializer...
1008 Inits.reserve(NewSize);
1009 if (ConstantArray *I = dyn_cast<ConstantArray>(G1->getInitializer())) {
1010 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i)
1011 Inits.push_back(I->getOperand(i));
1013 assert(isa<ConstantAggregateZero>(G1->getInitializer()));
1014 Constant *CV = Constant::getNullValue(T1->getElementType());
1015 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i)
1016 Inits.push_back(CV);
1018 if (ConstantArray *I = dyn_cast<ConstantArray>(G2->getInitializer())) {
1019 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i)
1020 Inits.push_back(I->getOperand(i));
1022 assert(isa<ConstantAggregateZero>(G2->getInitializer()));
1023 Constant *CV = Constant::getNullValue(T2->getElementType());
1024 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i)
1025 Inits.push_back(CV);
1027 NG->setInitializer(ConstantArray::get(NewType, Inits));
1030 // Replace any uses of the two global variables with uses of the new
1033 // FIXME: This should rewrite simple/straight-forward uses such as
1034 // getelementptr instructions to not use the Cast!
1035 G1->replaceAllUsesWith(ConstantExpr::getBitCast(NG, G1->getType()));
1036 G2->replaceAllUsesWith(ConstantExpr::getBitCast(NG, G2->getType()));
1038 // Remove the two globals from the module now...
1039 M->getGlobalList().erase(G1);
1040 M->getGlobalList().erase(G2);
1042 // Put the new global into the AppendingVars map so that we can handle
1043 // linking of more than two vars...
1044 Second->second = NG;
1046 AppendingVars.erase(First);
1052 static bool ResolveAliases(Module *Dest) {
1053 for (Module::alias_iterator I = Dest->alias_begin(), E = Dest->alias_end();
1055 GlobalValue* GV = const_cast<GlobalValue*>(I->getAliasedGlobal());
1056 if (!GV->isDeclaration())
1057 I->replaceAllUsesWith(GV);
1063 // LinkModules - This function links two modules together, with the resulting
1064 // left module modified to be the composite of the two input modules. If an
1065 // error occurs, true is returned and ErrorMsg (if not null) is set to indicate
1066 // the problem. Upon failure, the Dest module could be in a modified state, and
1067 // shouldn't be relied on to be consistent.
1069 Linker::LinkModules(Module *Dest, Module *Src, std::string *ErrorMsg) {
1070 assert(Dest != 0 && "Invalid Destination module");
1071 assert(Src != 0 && "Invalid Source Module");
1073 if (Dest->getDataLayout().empty()) {
1074 if (!Src->getDataLayout().empty()) {
1075 Dest->setDataLayout(Src->getDataLayout());
1077 std::string DataLayout;
1079 if (Dest->getEndianness() == Module::AnyEndianness) {
1080 if (Src->getEndianness() == Module::BigEndian)
1081 DataLayout.append("E");
1082 else if (Src->getEndianness() == Module::LittleEndian)
1083 DataLayout.append("e");
1086 if (Dest->getPointerSize() == Module::AnyPointerSize) {
1087 if (Src->getPointerSize() == Module::Pointer64)
1088 DataLayout.append(DataLayout.length() == 0 ? "p:64:64" : "-p:64:64");
1089 else if (Src->getPointerSize() == Module::Pointer32)
1090 DataLayout.append(DataLayout.length() == 0 ? "p:32:32" : "-p:32:32");
1092 Dest->setDataLayout(DataLayout);
1096 // Copy the target triple from the source to dest if the dest's is empty.
1097 if (Dest->getTargetTriple().empty() && !Src->getTargetTriple().empty())
1098 Dest->setTargetTriple(Src->getTargetTriple());
1100 if (!Src->getDataLayout().empty() && !Dest->getDataLayout().empty() &&
1101 Src->getDataLayout() != Dest->getDataLayout())
1102 cerr << "WARNING: Linking two modules of different data layouts!\n";
1103 if (!Src->getTargetTriple().empty() &&
1104 Dest->getTargetTriple() != Src->getTargetTriple())
1105 cerr << "WARNING: Linking two modules of different target triples!\n";
1107 // Append the module inline asm string.
1108 if (!Src->getModuleInlineAsm().empty()) {
1109 if (Dest->getModuleInlineAsm().empty())
1110 Dest->setModuleInlineAsm(Src->getModuleInlineAsm());
1112 Dest->setModuleInlineAsm(Dest->getModuleInlineAsm()+"\n"+
1113 Src->getModuleInlineAsm());
1116 // Update the destination module's dependent libraries list with the libraries
1117 // from the source module. There's no opportunity for duplicates here as the
1118 // Module ensures that duplicate insertions are discarded.
1119 for (Module::lib_iterator SI = Src->lib_begin(), SE = Src->lib_end();
1121 Dest->addLibrary(*SI);
1123 // LinkTypes - Go through the symbol table of the Src module and see if any
1124 // types are named in the src module that are not named in the Dst module.
1125 // Make sure there are no type name conflicts.
1126 if (LinkTypes(Dest, Src, ErrorMsg))
1129 // ValueMap - Mapping of values from what they used to be in Src, to what they
1131 std::map<const Value*, Value*> ValueMap;
1133 // AppendingVars - Keep track of global variables in the destination module
1134 // with appending linkage. After the module is linked together, they are
1135 // appended and the module is rewritten.
1136 std::multimap<std::string, GlobalVariable *> AppendingVars;
1137 for (Module::global_iterator I = Dest->global_begin(), E = Dest->global_end();
1139 // Add all of the appending globals already in the Dest module to
1141 if (I->hasAppendingLinkage())
1142 AppendingVars.insert(std::make_pair(I->getName(), I));
1145 // Insert all of the globals in src into the Dest module... without linking
1146 // initializers (which could refer to functions not yet mapped over).
1147 if (LinkGlobals(Dest, Src, ValueMap, AppendingVars, ErrorMsg))
1150 // Link the functions together between the two modules, without doing function
1151 // bodies... this just adds external function prototypes to the Dest
1152 // function... We do this so that when we begin processing function bodies,
1153 // all of the global values that may be referenced are available in our
1155 if (LinkFunctionProtos(Dest, Src, ValueMap, ErrorMsg))
1158 // If there were any alias, link them now. We really need to do this now,
1159 // because all of the aliases that may be referenced need to be available in
1161 if (LinkAlias(Dest, Src, ValueMap, ErrorMsg)) return true;
1163 // Update the initializers in the Dest module now that all globals that may
1164 // be referenced are in Dest.
1165 if (LinkGlobalInits(Dest, Src, ValueMap, ErrorMsg)) return true;
1167 // Link in the function bodies that are defined in the source module into the
1168 // DestModule. This consists basically of copying the function over and
1169 // fixing up references to values.
1170 if (LinkFunctionBodies(Dest, Src, ValueMap, ErrorMsg)) return true;
1172 // If there were any appending global variables, link them together now.
1173 if (LinkAppendingVars(Dest, AppendingVars, ErrorMsg)) return true;
1175 // Resolve all uses of aliases with aliasees
1176 if (ResolveAliases(Dest)) return true;
1178 // If the source library's module id is in the dependent library list of the
1179 // destination library, remove it since that module is now linked in.
1181 modId.set(Src->getModuleIdentifier());
1182 if (!modId.isEmpty())
1183 Dest->removeLibrary(modId.getBasename());