1 //===- lib/Linker/LinkModules.cpp - Module Linker Implementation ----------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source 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());
364 /// GetLinkageResult - This analyzes the two global values and determines what
365 /// the result will look like in the destination module. In particular, it
366 /// computes the resultant linkage type, computes whether the global in the
367 /// source should be copied over to the destination (replacing the existing
368 /// one), and computes whether this linkage is an error or not. It also performs
369 /// visibility checks: we cannot link together two symbols with different
371 static bool GetLinkageResult(GlobalValue *Dest, GlobalValue *Src,
372 GlobalValue::LinkageTypes <, bool &LinkFromSrc,
374 assert((!Dest || !Src->hasInternalLinkage()) &&
375 "If Src has internal linkage, Dest shouldn't be set!");
377 // Linking something to nothing.
379 LT = Src->getLinkage();
380 } else if (Src->isDeclaration()) {
381 // If Src is external or if both Src & Drc are external.. Just link the
382 // external globals, we aren't adding anything.
383 if (Src->hasDLLImportLinkage()) {
384 // If one of GVs has DLLImport linkage, result should be dllimport'ed.
385 if (Dest->isDeclaration()) {
387 LT = Src->getLinkage();
389 } else if (Dest->hasExternalWeakLinkage()) {
390 //If the Dest is weak, use the source linkage
392 LT = Src->getLinkage();
395 LT = Dest->getLinkage();
397 } else if (Dest->isDeclaration() && !Dest->hasDLLImportLinkage()) {
398 // If Dest is external but Src is not:
400 LT = Src->getLinkage();
401 } else if (Src->hasAppendingLinkage() || Dest->hasAppendingLinkage()) {
402 if (Src->getLinkage() != Dest->getLinkage())
403 return Error(Err, "Linking globals named '" + Src->getName() +
404 "': can only link appending global with another appending global!");
405 LinkFromSrc = true; // Special cased.
406 LT = Src->getLinkage();
407 } else if (Src->hasWeakLinkage() || Src->hasLinkOnceLinkage()) {
408 // At this point we know that Dest has LinkOnce, External*, Weak, or
410 if ((Dest->hasLinkOnceLinkage() && Src->hasWeakLinkage()) ||
411 Dest->hasExternalWeakLinkage()) {
413 LT = Src->getLinkage();
416 LT = Dest->getLinkage();
418 } else if (Dest->hasWeakLinkage() || Dest->hasLinkOnceLinkage()) {
419 // At this point we know that Src has External* or DLL* linkage.
420 if (Src->hasExternalWeakLinkage()) {
422 LT = Dest->getLinkage();
425 LT = GlobalValue::ExternalLinkage;
428 assert((Dest->hasExternalLinkage() ||
429 Dest->hasDLLImportLinkage() ||
430 Dest->hasDLLExportLinkage() ||
431 Dest->hasExternalWeakLinkage()) &&
432 (Src->hasExternalLinkage() ||
433 Src->hasDLLImportLinkage() ||
434 Src->hasDLLExportLinkage() ||
435 Src->hasExternalWeakLinkage()) &&
436 "Unexpected linkage type!");
437 return Error(Err, "Linking globals named '" + Src->getName() +
438 "': symbol multiply defined!");
442 if (Dest && Src->getVisibility() != Dest->getVisibility())
443 if (!Src->isDeclaration() && !Dest->isDeclaration())
444 return Error(Err, "Linking globals named '" + Src->getName() +
445 "': symbols have different visibilities!");
449 // LinkGlobals - Loop through the global variables in the src module and merge
450 // them into the dest module.
451 static bool LinkGlobals(Module *Dest, Module *Src,
452 std::map<const Value*, Value*> &ValueMap,
453 std::multimap<std::string, GlobalVariable *> &AppendingVars,
455 // Loop over all of the globals in the src module, mapping them over as we go
456 for (Module::global_iterator I = Src->global_begin(), E = Src->global_end();
458 GlobalVariable *SGV = I;
459 GlobalVariable *DGV = 0;
460 // Check to see if may have to link the global.
461 if (SGV->hasName() && !SGV->hasInternalLinkage()) {
462 DGV = Dest->getGlobalVariable(SGV->getName());
463 if (DGV && DGV->getType() != SGV->getType())
464 // If types don't agree due to opaque types, try to resolve them.
465 RecursiveResolveTypes(SGV->getType(), DGV->getType(),
466 &Dest->getTypeSymbolTable(), "");
469 if (DGV && DGV->hasInternalLinkage())
472 assert(SGV->hasInitializer() || SGV->hasExternalWeakLinkage() ||
473 SGV->hasExternalLinkage() || SGV->hasDLLImportLinkage() &&
474 "Global must either be external or have an initializer!");
476 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
477 bool LinkFromSrc = false;
478 if (GetLinkageResult(DGV, SGV, NewLinkage, LinkFromSrc, Err))
482 // No linking to be performed, simply create an identical version of the
483 // symbol over in the dest module... the initializer will be filled in
484 // later by LinkGlobalInits...
485 GlobalVariable *NewDGV =
486 new GlobalVariable(SGV->getType()->getElementType(),
487 SGV->isConstant(), SGV->getLinkage(), /*init*/0,
488 SGV->getName(), Dest, SGV->isThreadLocal());
489 // Propagate alignment, visibility and section info.
490 CopyGVAttributes(NewDGV, SGV);
492 // If the LLVM runtime renamed the global, but it is an externally visible
493 // symbol, DGV must be an existing global with internal linkage. Rename
495 if (NewDGV->getName() != SGV->getName() && !NewDGV->hasInternalLinkage())
496 ForceRenaming(NewDGV, SGV->getName());
498 // Make sure to remember this mapping...
499 ValueMap.insert(std::make_pair(SGV, NewDGV));
500 if (SGV->hasAppendingLinkage())
501 // Keep track that this is an appending variable...
502 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV));
503 } else if (DGV->hasAppendingLinkage()) {
504 // No linking is performed yet. Just insert a new copy of the global, and
505 // keep track of the fact that it is an appending variable in the
506 // AppendingVars map. The name is cleared out so that no linkage is
508 GlobalVariable *NewDGV =
509 new GlobalVariable(SGV->getType()->getElementType(),
510 SGV->isConstant(), SGV->getLinkage(), /*init*/0,
511 "", Dest, SGV->isThreadLocal());
513 // Propagate alignment, section and visibility info.
514 NewDGV->setAlignment(DGV->getAlignment());
515 CopyGVAttributes(NewDGV, SGV);
517 // Make sure to remember this mapping...
518 ValueMap.insert(std::make_pair(SGV, NewDGV));
520 // Keep track that this is an appending variable...
521 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV));
523 // Propagate alignment, section, and visibility info.
524 CopyGVAttributes(DGV, SGV);
526 // Otherwise, perform the mapping as instructed by GetLinkageResult. If
527 // the types don't match, and if we are to link from the source, nuke DGV
528 // and create a new one of the appropriate type.
529 if (SGV->getType() != DGV->getType() && LinkFromSrc) {
530 GlobalVariable *NewDGV =
531 new GlobalVariable(SGV->getType()->getElementType(),
532 DGV->isConstant(), DGV->getLinkage());
533 NewDGV->setThreadLocal(DGV->isThreadLocal());
534 CopyGVAttributes(NewDGV, DGV);
535 Dest->getGlobalList().insert(DGV, NewDGV);
536 DGV->replaceAllUsesWith(
537 ConstantExpr::getBitCast(NewDGV, DGV->getType()));
538 DGV->eraseFromParent();
539 NewDGV->setName(SGV->getName());
543 DGV->setLinkage(NewLinkage);
546 // Inherit const as appropriate
547 DGV->setConstant(SGV->isConstant());
548 DGV->setInitializer(0);
550 if (SGV->isConstant() && !DGV->isConstant()) {
551 if (DGV->isDeclaration())
552 DGV->setConstant(true);
554 SGV->setLinkage(GlobalValue::ExternalLinkage);
555 SGV->setInitializer(0);
559 std::make_pair(SGV, ConstantExpr::getBitCast(DGV, SGV->getType())));
565 // LinkAlias - Loop through the alias in the src module and link them into the
567 static bool LinkAlias(Module *Dest, const Module *Src, std::string *Err) {
568 // Loop over all alias in the src module
569 for (Module::const_alias_iterator I = Src->alias_begin(),
570 E = Src->alias_end(); I != E; ++I) {
571 const GlobalAlias *GA = I;
573 GlobalValue *NewAliased = NULL;
574 const GlobalValue *Aliased = GA->getAliasedGlobal();
575 if (isa<GlobalVariable>(*Aliased))
576 NewAliased = Dest->getGlobalVariable(Aliased->getName());
577 else if (isa<Function>(*Aliased))
578 NewAliased = Dest->getFunction(Aliased->getName());
579 // FIXME: we should handle the bitcast alias.
580 assert(NewAliased && "Can't find the aliased GV.");
582 GlobalAlias *NewGA = new GlobalAlias(GA->getType(), GA->getLinkage(),
583 GA->getName(), NewAliased, Dest);
584 CopyGVAttributes(NewGA, GA);
590 // LinkGlobalInits - Update the initializers in the Dest module now that all
591 // globals that may be referenced are in Dest.
592 static bool LinkGlobalInits(Module *Dest, const Module *Src,
593 std::map<const Value*, Value*> &ValueMap,
596 // Loop over all of the globals in the src module, mapping them over as we go
597 for (Module::const_global_iterator I = Src->global_begin(),
598 E = Src->global_end(); I != E; ++I) {
599 const GlobalVariable *SGV = I;
601 if (SGV->hasInitializer()) { // Only process initialized GV's
602 // Figure out what the initializer looks like in the dest module...
604 cast<Constant>(RemapOperand(SGV->getInitializer(), ValueMap));
606 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[SGV]);
607 if (DGV->hasInitializer()) {
608 if (SGV->hasExternalLinkage()) {
609 if (DGV->getInitializer() != SInit)
610 return Error(Err, "Global Variable Collision on '" +
611 ToStr(SGV->getType(), Src) +"':%"+SGV->getName()+
612 " - Global variables have different initializers");
613 } else if (DGV->hasLinkOnceLinkage() || DGV->hasWeakLinkage()) {
614 // Nothing is required, mapped values will take the new global
616 } else if (SGV->hasLinkOnceLinkage() || SGV->hasWeakLinkage()) {
617 // Nothing is required, mapped values will take the new global
619 } else if (DGV->hasAppendingLinkage()) {
620 assert(0 && "Appending linkage unimplemented!");
622 assert(0 && "Unknown linkage!");
625 // Copy the initializer over now...
626 DGV->setInitializer(SInit);
633 // LinkFunctionProtos - Link the functions together between the two modules,
634 // without doing function bodies... this just adds external function prototypes
635 // to the Dest function...
637 static bool LinkFunctionProtos(Module *Dest, const Module *Src,
638 std::map<const Value*, Value*> &ValueMap,
640 // Loop over all of the functions in the src module, mapping them over
641 for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) {
642 const Function *SF = I; // SrcFunction
644 if (SF->hasName() && !SF->hasInternalLinkage()) {
645 // Check to see if may have to link the function.
646 DF = Dest->getFunction(SF->getName());
647 if (DF && SF->getType() != DF->getType())
648 // If types don't agree because of opaque, try to resolve them
649 RecursiveResolveTypes(SF->getType(), DF->getType(),
650 &Dest->getTypeSymbolTable(), "");
654 if (DF && !DF->hasInternalLinkage() &&
655 SF->getVisibility() != DF->getVisibility()) {
656 // If one is a prototype, ignore its visibility. Prototypes are always
657 // overridden by the definition.
658 if (!SF->isDeclaration() && !DF->isDeclaration())
659 return Error(Err, "Linking functions named '" + SF->getName() +
660 "': symbols have different visibilities!");
663 if (DF && DF->getType() != SF->getType()) {
664 if (DF->isDeclaration() && !SF->isDeclaration()) {
665 // We have a definition of the same name but different type in the
666 // source module. Copy the prototype to the destination and replace
667 // uses of the destination's prototype with the new prototype.
668 Function *NewDF = new Function(SF->getFunctionType(), SF->getLinkage(),
669 SF->getName(), Dest);
670 CopyGVAttributes(NewDF, SF);
672 // Any uses of DF need to change to NewDF, with cast
673 DF->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, DF->getType()));
675 // DF will conflict with NewDF because they both had the same. We must
676 // erase this now so ForceRenaming doesn't assert because DF might
677 // not have internal linkage.
678 DF->eraseFromParent();
680 // If the symbol table renamed the function, but it is an externally
681 // visible symbol, DF must be an existing function with internal
682 // linkage. Rename it.
683 if (NewDF->getName() != SF->getName() && !NewDF->hasInternalLinkage())
684 ForceRenaming(NewDF, SF->getName());
686 // Remember this mapping so uses in the source module get remapped
687 // later by RemapOperand.
688 ValueMap[SF] = NewDF;
689 } else if (SF->isDeclaration()) {
690 // We have two functions of the same name but different type and the
691 // source is a declaration while the destination is not. Any use of
692 // the source must be mapped to the destination, with a cast.
693 ValueMap[SF] = ConstantExpr::getBitCast(DF, SF->getType());
695 // We have two functions of the same name but different types and they
696 // are both definitions. This is an error.
697 return Error(Err, "Function '" + DF->getName() + "' defined as both '" +
698 ToStr(SF->getFunctionType(), Src) + "' and '" +
699 ToStr(DF->getFunctionType(), Dest) + "'");
701 } else if (!DF || SF->hasInternalLinkage() || DF->hasInternalLinkage()) {
702 // Function does not already exist, simply insert an function signature
703 // identical to SF into the dest module.
704 Function *NewDF = new Function(SF->getFunctionType(), SF->getLinkage(),
705 SF->getName(), Dest);
706 CopyGVAttributes(NewDF, SF);
708 // If the LLVM runtime renamed the function, but it is an externally
709 // visible symbol, DF must be an existing function with internal linkage.
711 if (NewDF->getName() != SF->getName() && !NewDF->hasInternalLinkage())
712 ForceRenaming(NewDF, SF->getName());
714 // ... and remember this mapping...
715 ValueMap.insert(std::make_pair(SF, NewDF));
716 } else if (SF->isDeclaration()) {
717 // If SF is a declaration or if both SF & DF are declarations, just link
718 // the declarations, we aren't adding anything.
719 if (SF->hasDLLImportLinkage()) {
720 if (DF->isDeclaration()) {
721 ValueMap.insert(std::make_pair(SF, DF));
722 DF->setLinkage(SF->getLinkage());
725 ValueMap.insert(std::make_pair(SF, DF));
727 } else if (DF->isDeclaration() && !DF->hasDLLImportLinkage()) {
728 // If DF is external but SF is not...
729 // Link the external functions, update linkage qualifiers
730 ValueMap.insert(std::make_pair(SF, DF));
731 DF->setLinkage(SF->getLinkage());
732 // Visibility of prototype is overridden by vis of definition.
733 DF->setVisibility(SF->getVisibility());
734 } else if (SF->hasWeakLinkage() || SF->hasLinkOnceLinkage()) {
735 // At this point we know that DF has LinkOnce, Weak, or External* linkage.
736 ValueMap.insert(std::make_pair(SF, DF));
738 // Linkonce+Weak = Weak
739 // *+External Weak = *
740 if ((DF->hasLinkOnceLinkage() && SF->hasWeakLinkage()) ||
741 DF->hasExternalWeakLinkage())
742 DF->setLinkage(SF->getLinkage());
743 } else if (DF->hasWeakLinkage() || DF->hasLinkOnceLinkage()) {
744 // At this point we know that SF has LinkOnce or External* linkage.
745 ValueMap.insert(std::make_pair(SF, DF));
746 if (!SF->hasLinkOnceLinkage() && !SF->hasExternalWeakLinkage())
747 // Don't inherit linkonce & external weak linkage
748 DF->setLinkage(SF->getLinkage());
749 } else if (SF->getLinkage() != DF->getLinkage()) {
750 return Error(Err, "Functions named '" + SF->getName() +
751 "' have different linkage specifiers!");
752 } else if (SF->hasExternalLinkage()) {
753 // The function is defined identically in both modules!!
754 return Error(Err, "Function '" +
755 ToStr(SF->getFunctionType(), Src) + "':\"" +
756 SF->getName() + "\" - Function is already defined!");
758 assert(0 && "Unknown linkage configuration found!");
764 // LinkFunctionBody - Copy the source function over into the dest function and
765 // fix up references to values. At this point we know that Dest is an external
766 // function, and that Src is not.
767 static bool LinkFunctionBody(Function *Dest, Function *Src,
768 std::map<const Value*, Value*> &ValueMap,
770 assert(Src && Dest && Dest->isDeclaration() && !Src->isDeclaration());
772 // Go through and convert function arguments over, remembering the mapping.
773 Function::arg_iterator DI = Dest->arg_begin();
774 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
776 DI->setName(I->getName()); // Copy the name information over...
778 // Add a mapping to our local map
779 ValueMap.insert(std::make_pair(I, DI));
782 // Splice the body of the source function into the dest function.
783 Dest->getBasicBlockList().splice(Dest->end(), Src->getBasicBlockList());
785 // At this point, all of the instructions and values of the function are now
786 // copied over. The only problem is that they are still referencing values in
787 // the Source function as operands. Loop through all of the operands of the
788 // functions and patch them up to point to the local versions...
790 for (Function::iterator BB = Dest->begin(), BE = Dest->end(); BB != BE; ++BB)
791 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
792 for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end();
794 if (!isa<Instruction>(*OI) && !isa<BasicBlock>(*OI))
795 *OI = RemapOperand(*OI, ValueMap);
797 // There is no need to map the arguments anymore.
798 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
806 // LinkFunctionBodies - Link in the function bodies that are defined in the
807 // source module into the DestModule. This consists basically of copying the
808 // function over and fixing up references to values.
809 static bool LinkFunctionBodies(Module *Dest, Module *Src,
810 std::map<const Value*, Value*> &ValueMap,
813 // Loop over all of the functions in the src module, mapping them over as we
815 for (Module::iterator SF = Src->begin(), E = Src->end(); SF != E; ++SF) {
816 if (!SF->isDeclaration()) { // No body if function is external
817 Function *DF = cast<Function>(ValueMap[SF]); // Destination function
819 // DF not external SF external?
820 if (DF->isDeclaration())
821 // Only provide the function body if there isn't one already.
822 if (LinkFunctionBody(DF, SF, ValueMap, Err))
829 // LinkAppendingVars - If there were any appending global variables, link them
830 // together now. Return true on error.
831 static bool LinkAppendingVars(Module *M,
832 std::multimap<std::string, GlobalVariable *> &AppendingVars,
833 std::string *ErrorMsg) {
834 if (AppendingVars.empty()) return false; // Nothing to do.
836 // Loop over the multimap of appending vars, processing any variables with the
837 // same name, forming a new appending global variable with both of the
838 // initializers merged together, then rewrite references to the old variables
840 std::vector<Constant*> Inits;
841 while (AppendingVars.size() > 1) {
842 // Get the first two elements in the map...
843 std::multimap<std::string,
844 GlobalVariable*>::iterator Second = AppendingVars.begin(), First=Second++;
846 // If the first two elements are for different names, there is no pair...
847 // Otherwise there is a pair, so link them together...
848 if (First->first == Second->first) {
849 GlobalVariable *G1 = First->second, *G2 = Second->second;
850 const ArrayType *T1 = cast<ArrayType>(G1->getType()->getElementType());
851 const ArrayType *T2 = cast<ArrayType>(G2->getType()->getElementType());
853 // Check to see that they two arrays agree on type...
854 if (T1->getElementType() != T2->getElementType())
855 return Error(ErrorMsg,
856 "Appending variables with different element types need to be linked!");
857 if (G1->isConstant() != G2->isConstant())
858 return Error(ErrorMsg,
859 "Appending variables linked with different const'ness!");
861 if (G1->getAlignment() != G2->getAlignment())
862 return Error(ErrorMsg,
863 "Appending variables with different alignment need to be linked!");
865 if (G1->getVisibility() != G2->getVisibility())
866 return Error(ErrorMsg,
867 "Appending variables with different visibility need to be linked!");
869 if (G1->getSection() != G2->getSection())
870 return Error(ErrorMsg,
871 "Appending variables with different section name need to be linked!");
873 unsigned NewSize = T1->getNumElements() + T2->getNumElements();
874 ArrayType *NewType = ArrayType::get(T1->getElementType(), NewSize);
876 G1->setName(""); // Clear G1's name in case of a conflict!
878 // Create the new global variable...
880 new GlobalVariable(NewType, G1->isConstant(), G1->getLinkage(),
881 /*init*/0, First->first, M, G1->isThreadLocal());
883 // Propagate alignment, visibility and section info.
884 CopyGVAttributes(NG, G1);
886 // Merge the initializer...
887 Inits.reserve(NewSize);
888 if (ConstantArray *I = dyn_cast<ConstantArray>(G1->getInitializer())) {
889 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i)
890 Inits.push_back(I->getOperand(i));
892 assert(isa<ConstantAggregateZero>(G1->getInitializer()));
893 Constant *CV = Constant::getNullValue(T1->getElementType());
894 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i)
897 if (ConstantArray *I = dyn_cast<ConstantArray>(G2->getInitializer())) {
898 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i)
899 Inits.push_back(I->getOperand(i));
901 assert(isa<ConstantAggregateZero>(G2->getInitializer()));
902 Constant *CV = Constant::getNullValue(T2->getElementType());
903 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i)
906 NG->setInitializer(ConstantArray::get(NewType, Inits));
909 // Replace any uses of the two global variables with uses of the new
912 // FIXME: This should rewrite simple/straight-forward uses such as
913 // getelementptr instructions to not use the Cast!
914 G1->replaceAllUsesWith(ConstantExpr::getBitCast(NG, G1->getType()));
915 G2->replaceAllUsesWith(ConstantExpr::getBitCast(NG, G2->getType()));
917 // Remove the two globals from the module now...
918 M->getGlobalList().erase(G1);
919 M->getGlobalList().erase(G2);
921 // Put the new global into the AppendingVars map so that we can handle
922 // linking of more than two vars...
925 AppendingVars.erase(First);
932 // LinkModules - This function links two modules together, with the resulting
933 // left module modified to be the composite of the two input modules. If an
934 // error occurs, true is returned and ErrorMsg (if not null) is set to indicate
935 // the problem. Upon failure, the Dest module could be in a modified state, and
936 // shouldn't be relied on to be consistent.
938 Linker::LinkModules(Module *Dest, Module *Src, std::string *ErrorMsg) {
939 assert(Dest != 0 && "Invalid Destination module");
940 assert(Src != 0 && "Invalid Source Module");
942 if (Dest->getDataLayout().empty()) {
943 if (!Src->getDataLayout().empty()) {
944 Dest->setDataLayout(Src->getDataLayout());
946 std::string DataLayout;
948 if (Dest->getEndianness() == Module::AnyEndianness)
949 if (Src->getEndianness() == Module::BigEndian)
950 DataLayout.append("E");
951 else if (Src->getEndianness() == Module::LittleEndian)
952 DataLayout.append("e");
953 if (Dest->getPointerSize() == Module::AnyPointerSize)
954 if (Src->getPointerSize() == Module::Pointer64)
955 DataLayout.append(DataLayout.length() == 0 ? "p:64:64" : "-p:64:64");
956 else if (Src->getPointerSize() == Module::Pointer32)
957 DataLayout.append(DataLayout.length() == 0 ? "p:32:32" : "-p:32:32");
958 Dest->setDataLayout(DataLayout);
962 // COpy the target triple from the source to dest if the dest's is empty
963 if (Dest->getTargetTriple().empty() && !Src->getTargetTriple().empty())
964 Dest->setTargetTriple(Src->getTargetTriple());
966 if (!Src->getDataLayout().empty() && !Dest->getDataLayout().empty() &&
967 Src->getDataLayout() != Dest->getDataLayout())
968 cerr << "WARNING: Linking two modules of different data layouts!\n";
969 if (!Src->getTargetTriple().empty() &&
970 Dest->getTargetTriple() != Src->getTargetTriple())
971 cerr << "WARNING: Linking two modules of different target triples!\n";
973 // Append the module inline asm string
974 if (!Src->getModuleInlineAsm().empty()) {
975 if (Dest->getModuleInlineAsm().empty())
976 Dest->setModuleInlineAsm(Src->getModuleInlineAsm());
978 Dest->setModuleInlineAsm(Dest->getModuleInlineAsm()+"\n"+
979 Src->getModuleInlineAsm());
982 // Update the destination module's dependent libraries list with the libraries
983 // from the source module. There's no opportunity for duplicates here as the
984 // Module ensures that duplicate insertions are discarded.
985 Module::lib_iterator SI = Src->lib_begin();
986 Module::lib_iterator SE = Src->lib_end();
988 Dest->addLibrary(*SI);
992 // LinkTypes - Go through the symbol table of the Src module and see if any
993 // types are named in the src module that are not named in the Dst module.
994 // Make sure there are no type name conflicts.
995 if (LinkTypes(Dest, Src, ErrorMsg))
998 // ValueMap - Mapping of values from what they used to be in Src, to what they
1000 std::map<const Value*, Value*> ValueMap;
1002 // AppendingVars - Keep track of global variables in the destination module
1003 // with appending linkage. After the module is linked together, they are
1004 // appended and the module is rewritten.
1005 std::multimap<std::string, GlobalVariable *> AppendingVars;
1006 for (Module::global_iterator I = Dest->global_begin(), E = Dest->global_end();
1008 // Add all of the appending globals already in the Dest module to
1010 if (I->hasAppendingLinkage())
1011 AppendingVars.insert(std::make_pair(I->getName(), I));
1014 // Insert all of the globals in src into the Dest module... without linking
1015 // initializers (which could refer to functions not yet mapped over).
1016 if (LinkGlobals(Dest, Src, ValueMap, AppendingVars, ErrorMsg))
1019 // Link the functions together between the two modules, without doing function
1020 // bodies... this just adds external function prototypes to the Dest
1021 // function... We do this so that when we begin processing function bodies,
1022 // all of the global values that may be referenced are available in our
1024 if (LinkFunctionProtos(Dest, Src, ValueMap, ErrorMsg))
1027 // Update the initializers in the Dest module now that all globals that may
1028 // be referenced are in Dest.
1029 if (LinkGlobalInits(Dest, Src, ValueMap, ErrorMsg)) return true;
1031 // Link in the function bodies that are defined in the source module into the
1032 // DestModule. This consists basically of copying the function over and
1033 // fixing up references to values.
1034 if (LinkFunctionBodies(Dest, Src, ValueMap, ErrorMsg)) return true;
1036 // If there were any appending global variables, link them together now.
1037 if (LinkAppendingVars(Dest, AppendingVars, ErrorMsg)) return true;
1039 // If there were any alias, link them now.
1040 if (LinkAlias(Dest, Src, ErrorMsg)) return true;
1042 // If the source library's module id is in the dependent library list of the
1043 // destination library, remove it since that module is now linked in.
1045 modId.set(Src->getModuleIdentifier());
1046 if (!modId.isEmpty())
1047 Dest->removeLibrary(modId.getBasename());