1 //===- Linker.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/Transforms/Utils/Linker.h"
20 #include "llvm/Module.h"
21 #include "llvm/SymbolTable.h"
22 #include "llvm/DerivedTypes.h"
23 #include "llvm/iOther.h"
24 #include "llvm/Constants.h"
28 // Error - Simple wrapper function to conditionally assign to E and return true.
29 // This just makes error return conditions a little bit simpler...
31 static inline bool Error(std::string *E, const std::string &Message) {
37 // Function: ResolveTypes()
40 // Attempt to link the two specified types together.
43 // DestTy - The type to which we wish to resolve.
44 // SrcTy - The original type which we want to resolve.
45 // Name - The name of the type.
48 // DestST - The symbol table in which the new type should be placed.
51 // true - There is an error and the types cannot yet be linked.
54 static bool ResolveTypes(const Type *DestTy, const Type *SrcTy,
55 SymbolTable *DestST, const std::string &Name) {
56 if (DestTy == SrcTy) return false; // If already equal, noop
58 // Does the type already exist in the module?
59 if (DestTy && !isa<OpaqueType>(DestTy)) { // Yup, the type already exists...
60 if (const OpaqueType *OT = dyn_cast<OpaqueType>(SrcTy)) {
61 const_cast<OpaqueType*>(OT)->refineAbstractTypeTo(DestTy);
63 return true; // Cannot link types... neither is opaque and not-equal
65 } else { // Type not in dest module. Add it now.
66 if (DestTy) // Type _is_ in module, just opaque...
67 const_cast<OpaqueType*>(cast<OpaqueType>(DestTy))
68 ->refineAbstractTypeTo(SrcTy);
69 else if (!Name.empty())
70 DestST->insert(Name, const_cast<Type*>(SrcTy));
75 static const FunctionType *getFT(const PATypeHolder &TH) {
76 return cast<FunctionType>(TH.get());
78 static const StructType *getST(const PATypeHolder &TH) {
79 return cast<StructType>(TH.get());
82 // RecursiveResolveTypes - This is just like ResolveTypes, except that it
83 // recurses down into derived types, merging the used types if the parent types
86 static bool RecursiveResolveTypesI(const PATypeHolder &DestTy,
87 const PATypeHolder &SrcTy,
88 SymbolTable *DestST, const std::string &Name,
89 std::vector<std::pair<PATypeHolder, PATypeHolder> > &Pointers) {
90 const Type *SrcTyT = SrcTy.get();
91 const Type *DestTyT = DestTy.get();
92 if (DestTyT == SrcTyT) return false; // If already equal, noop
94 // If we found our opaque type, resolve it now!
95 if (isa<OpaqueType>(DestTyT) || isa<OpaqueType>(SrcTyT))
96 return ResolveTypes(DestTyT, SrcTyT, DestST, Name);
98 // Two types cannot be resolved together if they are of different primitive
99 // type. For example, we cannot resolve an int to a float.
100 if (DestTyT->getPrimitiveID() != SrcTyT->getPrimitiveID()) return true;
102 // Otherwise, resolve the used type used by this derived type...
103 switch (DestTyT->getPrimitiveID()) {
104 case Type::FunctionTyID: {
105 if (cast<FunctionType>(DestTyT)->isVarArg() !=
106 cast<FunctionType>(SrcTyT)->isVarArg() ||
107 cast<FunctionType>(DestTyT)->getNumContainedTypes() !=
108 cast<FunctionType>(SrcTyT)->getNumContainedTypes())
110 for (unsigned i = 0, e = getFT(DestTy)->getNumContainedTypes(); i != e; ++i)
111 if (RecursiveResolveTypesI(getFT(DestTy)->getContainedType(i),
112 getFT(SrcTy)->getContainedType(i), DestST, "",
117 case Type::StructTyID: {
118 if (getST(DestTy)->getNumContainedTypes() !=
119 getST(SrcTy)->getNumContainedTypes()) return 1;
120 for (unsigned i = 0, e = getST(DestTy)->getNumContainedTypes(); i != e; ++i)
121 if (RecursiveResolveTypesI(getST(DestTy)->getContainedType(i),
122 getST(SrcTy)->getContainedType(i), DestST, "",
127 case Type::ArrayTyID: {
128 const ArrayType *DAT = cast<ArrayType>(DestTy.get());
129 const ArrayType *SAT = cast<ArrayType>(SrcTy.get());
130 if (DAT->getNumElements() != SAT->getNumElements()) return true;
131 return RecursiveResolveTypesI(DAT->getElementType(), SAT->getElementType(),
132 DestST, "", Pointers);
134 case Type::PointerTyID: {
135 // If this is a pointer type, check to see if we have already seen it. If
136 // so, we are in a recursive branch. Cut off the search now. We cannot use
137 // an associative container for this search, because the type pointers (keys
138 // in the container) change whenever types get resolved...
140 for (unsigned i = 0, e = Pointers.size(); i != e; ++i)
141 if (Pointers[i].first == DestTy)
142 return Pointers[i].second != SrcTy;
144 // Otherwise, add the current pointers to the vector to stop recursion on
146 Pointers.push_back(std::make_pair(DestTyT, SrcTyT));
148 RecursiveResolveTypesI(cast<PointerType>(DestTy.get())->getElementType(),
149 cast<PointerType>(SrcTy.get())->getElementType(),
150 DestST, "", Pointers);
154 default: assert(0 && "Unexpected type!"); return true;
158 static bool RecursiveResolveTypes(const PATypeHolder &DestTy,
159 const PATypeHolder &SrcTy,
160 SymbolTable *DestST, const std::string &Name){
161 std::vector<std::pair<PATypeHolder, PATypeHolder> > PointerTypes;
162 return RecursiveResolveTypesI(DestTy, SrcTy, DestST, Name, PointerTypes);
166 // LinkTypes - Go through the symbol table of the Src module and see if any
167 // types are named in the src module that are not named in the Dst module.
168 // Make sure there are no type name conflicts.
170 static bool LinkTypes(Module *Dest, const Module *Src, std::string *Err) {
171 SymbolTable *DestST = &Dest->getSymbolTable();
172 const SymbolTable *SrcST = &Src->getSymbolTable();
174 // Look for a type plane for Type's...
175 SymbolTable::const_iterator PI = SrcST->find(Type::TypeTy);
176 if (PI == SrcST->end()) return false; // No named types, do nothing.
178 // Some types cannot be resolved immediately because they depend on other
179 // types being resolved to each other first. This contains a list of types we
180 // are waiting to recheck.
181 std::vector<std::string> DelayedTypesToResolve;
183 const SymbolTable::VarMap &VM = PI->second;
184 for (SymbolTable::type_const_iterator I = VM.begin(), E = VM.end();
186 const std::string &Name = I->first;
187 Type *RHS = cast<Type>(I->second);
189 // Check to see if this type name is already in the dest module...
190 Type *Entry = cast_or_null<Type>(DestST->lookup(Type::TypeTy, Name));
192 if (ResolveTypes(Entry, RHS, DestST, Name)) {
193 // They look different, save the types 'till later to resolve.
194 DelayedTypesToResolve.push_back(Name);
198 // Iteratively resolve types while we can...
199 while (!DelayedTypesToResolve.empty()) {
200 // Loop over all of the types, attempting to resolve them if possible...
201 unsigned OldSize = DelayedTypesToResolve.size();
203 // Try direct resolution by name...
204 for (unsigned i = 0; i != DelayedTypesToResolve.size(); ++i) {
205 const std::string &Name = DelayedTypesToResolve[i];
206 Type *T1 = cast<Type>(VM.find(Name)->second);
207 Type *T2 = cast<Type>(DestST->lookup(Type::TypeTy, Name));
208 if (!ResolveTypes(T2, T1, DestST, Name)) {
209 // We are making progress!
210 DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i);
215 // Did we not eliminate any types?
216 if (DelayedTypesToResolve.size() == OldSize) {
217 // Attempt to resolve subelements of types. This allows us to merge these
218 // two types: { int* } and { opaque* }
219 for (unsigned i = 0, e = DelayedTypesToResolve.size(); i != e; ++i) {
220 const std::string &Name = DelayedTypesToResolve[i];
221 PATypeHolder T1(cast<Type>(VM.find(Name)->second));
222 PATypeHolder T2(cast<Type>(DestST->lookup(Type::TypeTy, Name)));
224 if (!RecursiveResolveTypes(T2, T1, DestST, Name)) {
225 // We are making progress!
226 DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i);
228 // Go back to the main loop, perhaps we can resolve directly by name
234 // If we STILL cannot resolve the types, then there is something wrong.
235 // Report the warning and delete one of the names.
236 if (DelayedTypesToResolve.size() == OldSize) {
237 const std::string &Name = DelayedTypesToResolve.back();
239 const Type *T1 = cast<Type>(VM.find(Name)->second);
240 const Type *T2 = cast<Type>(DestST->lookup(Type::TypeTy, Name));
241 std::cerr << "WARNING: Type conflict between types named '" << Name
242 << "'.\n Src='" << *T1 << "'.\n Dest='" << *T2 << "'\n";
244 // Remove the symbol name from the destination.
245 DelayedTypesToResolve.pop_back();
254 static void PrintMap(const std::map<const Value*, Value*> &M) {
255 for (std::map<const Value*, Value*>::const_iterator I = M.begin(), E =M.end();
257 std::cerr << " Fr: " << (void*)I->first << " ";
259 std::cerr << " To: " << (void*)I->second << " ";
266 // RemapOperand - Use LocalMap and GlobalMap to convert references from one
267 // module to another. This is somewhat sophisticated in that it can
268 // automatically handle constant references correctly as well...
270 static Value *RemapOperand(const Value *In,
271 std::map<const Value*, Value*> &LocalMap,
272 std::map<const Value*, Value*> *GlobalMap) {
273 std::map<const Value*,Value*>::const_iterator I = LocalMap.find(In);
274 if (I != LocalMap.end()) return I->second;
277 I = GlobalMap->find(In);
278 if (I != GlobalMap->end()) return I->second;
281 // Check to see if it's a constant that we are interesting in transforming...
282 if (const Constant *CPV = dyn_cast<Constant>(In)) {
283 if (!isa<DerivedType>(CPV->getType()) && !isa<ConstantExpr>(CPV))
284 return const_cast<Constant*>(CPV); // Simple constants stay identical...
286 Constant *Result = 0;
288 if (const ConstantArray *CPA = dyn_cast<ConstantArray>(CPV)) {
289 const std::vector<Use> &Ops = CPA->getValues();
290 std::vector<Constant*> Operands(Ops.size());
291 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
293 cast<Constant>(RemapOperand(Ops[i], LocalMap, GlobalMap));
294 Result = ConstantArray::get(cast<ArrayType>(CPA->getType()), Operands);
295 } else if (const ConstantStruct *CPS = dyn_cast<ConstantStruct>(CPV)) {
296 const std::vector<Use> &Ops = CPS->getValues();
297 std::vector<Constant*> Operands(Ops.size());
298 for (unsigned i = 0; i < Ops.size(); ++i)
300 cast<Constant>(RemapOperand(Ops[i], LocalMap, GlobalMap));
301 Result = ConstantStruct::get(cast<StructType>(CPS->getType()), Operands);
302 } else if (isa<ConstantPointerNull>(CPV)) {
303 Result = const_cast<Constant*>(CPV);
304 } else if (const ConstantPointerRef *CPR =
305 dyn_cast<ConstantPointerRef>(CPV)) {
306 Value *V = RemapOperand(CPR->getValue(), LocalMap, GlobalMap);
307 Result = ConstantPointerRef::get(cast<GlobalValue>(V));
308 } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CPV)) {
309 if (CE->getOpcode() == Instruction::GetElementPtr) {
310 Value *Ptr = RemapOperand(CE->getOperand(0), LocalMap, GlobalMap);
311 std::vector<Constant*> Indices;
312 Indices.reserve(CE->getNumOperands()-1);
313 for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
314 Indices.push_back(cast<Constant>(RemapOperand(CE->getOperand(i),
315 LocalMap, GlobalMap)));
317 Result = ConstantExpr::getGetElementPtr(cast<Constant>(Ptr), Indices);
318 } else if (CE->getNumOperands() == 1) {
320 assert(CE->getOpcode() == Instruction::Cast);
321 Value *V = RemapOperand(CE->getOperand(0), LocalMap, GlobalMap);
322 Result = ConstantExpr::getCast(cast<Constant>(V), CE->getType());
323 } else if (CE->getOpcode() == Instruction::Shl ||
324 CE->getOpcode() == Instruction::Shr) { // Shift
325 Value *V1 = RemapOperand(CE->getOperand(0), LocalMap, GlobalMap);
326 Value *V2 = RemapOperand(CE->getOperand(1), LocalMap, GlobalMap);
327 Result = ConstantExpr::getShift(CE->getOpcode(), cast<Constant>(V1),
329 } else if (CE->getNumOperands() == 2) {
330 // Binary operator...
331 Value *V1 = RemapOperand(CE->getOperand(0), LocalMap, GlobalMap);
332 Value *V2 = RemapOperand(CE->getOperand(1), LocalMap, GlobalMap);
334 Result = ConstantExpr::get(CE->getOpcode(), cast<Constant>(V1),
337 assert(0 && "Unknown constant expr type!");
341 assert(0 && "Unknown type of derived type constant value!");
344 // Cache the mapping in our local map structure...
346 GlobalMap->insert(std::make_pair(In, Result));
348 LocalMap.insert(std::make_pair(In, Result));
352 std::cerr << "XXX LocalMap: \n";
356 std::cerr << "XXX GlobalMap: \n";
357 PrintMap(*GlobalMap);
360 std::cerr << "Couldn't remap value: " << (void*)In << " " << *In << "\n";
361 assert(0 && "Couldn't remap value!");
365 /// FindGlobalNamed - Look in the specified symbol table for a global with the
366 /// specified name and type. If an exactly matching global does not exist, see
367 /// if there is a global which is "type compatible" with the specified
368 /// name/type. This allows us to resolve things like '%x = global int*' with
369 /// '%x = global opaque*'.
371 static GlobalValue *FindGlobalNamed(const std::string &Name, const Type *Ty,
373 // See if an exact match exists in the symbol table...
374 if (Value *V = ST->lookup(Ty, Name)) return cast<GlobalValue>(V);
376 // It doesn't exist exactly, scan through all of the type planes in the symbol
377 // table, checking each of them for a type-compatible version.
379 for (SymbolTable::iterator I = ST->begin(), E = ST->end(); I != E; ++I)
380 if (I->first != Type::TypeTy) {
381 SymbolTable::VarMap &VM = I->second;
383 // Does this type plane contain an entry with the specified name?
384 SymbolTable::type_iterator TI = VM.find(Name);
385 if (TI != VM.end()) {
387 // Ensure that this type if placed correctly into the symbol table.
389 assert(TI->second->getType() == I->first && "Type conflict!");
392 // Save a reference to the new type. Resolving the type can modify the
393 // symbol table, invalidating the TI variable.
395 Value *ValPtr = TI->second;
398 // Determine whether we can fold the two types together, resolving them.
399 // If so, we can use this value.
401 if (!RecursiveResolveTypes(Ty, I->first, ST, ""))
402 return cast<GlobalValue>(ValPtr);
405 return 0; // Otherwise, nothing could be found.
409 // LinkGlobals - Loop through the global variables in the src module and merge
410 // them into the dest module.
412 static bool LinkGlobals(Module *Dest, const Module *Src,
413 std::map<const Value*, Value*> &ValueMap,
414 std::multimap<std::string, GlobalVariable *> &AppendingVars,
416 // We will need a module level symbol table if the src module has a module
417 // level symbol table...
418 SymbolTable *ST = (SymbolTable*)&Dest->getSymbolTable();
420 // Loop over all of the globals in the src module, mapping them over as we go
422 for (Module::const_giterator I = Src->gbegin(), E = Src->gend(); I != E; ++I){
423 const GlobalVariable *SGV = I;
424 GlobalVariable *DGV = 0;
425 if (SGV->hasName()) {
426 // A same named thing is a global variable, because the only two things
427 // that may be in a module level symbol table are Global Vars and
428 // Functions, and they both have distinct, nonoverlapping, possible types.
430 DGV = cast_or_null<GlobalVariable>(FindGlobalNamed(SGV->getName(),
431 SGV->getType(), ST));
434 assert(SGV->hasInitializer() || SGV->hasExternalLinkage() &&
435 "Global must either be external or have an initializer!");
437 bool SGExtern = SGV->isExternal();
438 bool DGExtern = DGV ? DGV->isExternal() : false;
440 if (!DGV || DGV->hasInternalLinkage() || SGV->hasInternalLinkage()) {
441 // No linking to be performed, simply create an identical version of the
442 // symbol over in the dest module... the initializer will be filled in
443 // later by LinkGlobalInits...
445 GlobalVariable *NewDGV =
446 new GlobalVariable(SGV->getType()->getElementType(),
447 SGV->isConstant(), SGV->getLinkage(), /*init*/0,
448 SGV->getName(), Dest);
450 // If the LLVM runtime renamed the global, but it is an externally visible
451 // symbol, DGV must be an existing global with internal linkage. Rename
453 if (NewDGV->getName() != SGV->getName() && !NewDGV->hasInternalLinkage()){
454 assert(DGV && DGV->getName() == SGV->getName() &&
455 DGV->hasInternalLinkage());
457 NewDGV->setName(SGV->getName()); // Force the name back
458 DGV->setName(SGV->getName()); // This will cause a renaming
459 assert(NewDGV->getName() == SGV->getName() &&
460 DGV->getName() != SGV->getName());
463 // Make sure to remember this mapping...
464 ValueMap.insert(std::make_pair(SGV, NewDGV));
465 if (SGV->hasAppendingLinkage())
466 // Keep track that this is an appending variable...
467 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV));
469 } else if (SGV->isExternal()) {
470 // If SGV is external or if both SGV & DGV are external.. Just link the
471 // external globals, we aren't adding anything.
472 ValueMap.insert(std::make_pair(SGV, DGV));
474 } else if (DGV->isExternal()) { // If DGV is external but SGV is not...
475 ValueMap.insert(std::make_pair(SGV, DGV));
476 DGV->setLinkage(SGV->getLinkage()); // Inherit linkage!
477 } else if (SGV->hasWeakLinkage() || SGV->hasLinkOnceLinkage()) {
478 // At this point we know that DGV has LinkOnce, Appending, Weak, or
479 // External linkage. If DGV is Appending, this is an error.
480 if (DGV->hasAppendingLinkage())
481 return Error(Err, "Linking globals named '" + SGV->getName() +
482 " ' with 'weak' and 'appending' linkage is not allowed!");
484 if (SGV->isConstant() != DGV->isConstant())
485 return Error(Err, "Global Variable Collision on '" +
486 SGV->getType()->getDescription() + " %" + SGV->getName() +
487 "' - Global variables differ in const'ness");
489 // Otherwise, just perform the link.
490 ValueMap.insert(std::make_pair(SGV, DGV));
492 // Linkonce+Weak = Weak
493 if (DGV->hasLinkOnceLinkage() && SGV->hasWeakLinkage())
494 DGV->setLinkage(SGV->getLinkage());
496 } else if (DGV->hasWeakLinkage() || DGV->hasLinkOnceLinkage()) {
497 // At this point we know that SGV has LinkOnce, Appending, or External
498 // linkage. If SGV is Appending, this is an error.
499 if (SGV->hasAppendingLinkage())
500 return Error(Err, "Linking globals named '" + SGV->getName() +
501 " ' with 'weak' and 'appending' linkage is not allowed!");
503 if (SGV->isConstant() != DGV->isConstant())
504 return Error(Err, "Global Variable Collision on '" +
505 SGV->getType()->getDescription() + " %" + SGV->getName() +
506 "' - Global variables differ in const'ness");
508 if (!SGV->hasLinkOnceLinkage())
509 DGV->setLinkage(SGV->getLinkage()); // Inherit linkage!
510 ValueMap.insert(std::make_pair(SGV, DGV));
512 } else if (SGV->getLinkage() != DGV->getLinkage()) {
513 return Error(Err, "Global variables named '" + SGV->getName() +
514 "' have different linkage specifiers!");
515 } else if (SGV->hasExternalLinkage()) {
516 // Allow linking two exactly identical external global variables...
517 if (SGV->isConstant() != DGV->isConstant())
518 return Error(Err, "Global Variable Collision on '" +
519 SGV->getType()->getDescription() + " %" + SGV->getName() +
520 "' - Global variables differ in const'ness");
522 if (SGV->getInitializer() != DGV->getInitializer())
523 return Error(Err, "Global Variable Collision on '" +
524 SGV->getType()->getDescription() + " %" + SGV->getName() +
525 "' - External linkage globals have different initializers");
527 ValueMap.insert(std::make_pair(SGV, DGV));
528 } else if (SGV->hasAppendingLinkage()) {
529 // No linking is performed yet. Just insert a new copy of the global, and
530 // keep track of the fact that it is an appending variable in the
531 // AppendingVars map. The name is cleared out so that no linkage is
533 GlobalVariable *NewDGV =
534 new GlobalVariable(SGV->getType()->getElementType(),
535 SGV->isConstant(), SGV->getLinkage(), /*init*/0,
538 // Make sure to remember this mapping...
539 ValueMap.insert(std::make_pair(SGV, NewDGV));
541 // Keep track that this is an appending variable...
542 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV));
544 assert(0 && "Unknown linkage!");
551 // LinkGlobalInits - Update the initializers in the Dest module now that all
552 // globals that may be referenced are in Dest.
554 static bool LinkGlobalInits(Module *Dest, const Module *Src,
555 std::map<const Value*, Value*> &ValueMap,
558 // Loop over all of the globals in the src module, mapping them over as we go
560 for (Module::const_giterator I = Src->gbegin(), E = Src->gend(); I != E; ++I){
561 const GlobalVariable *SGV = I;
563 if (SGV->hasInitializer()) { // Only process initialized GV's
564 // Figure out what the initializer looks like in the dest module...
566 cast<Constant>(RemapOperand(SGV->getInitializer(), ValueMap, 0));
568 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[SGV]);
569 if (DGV->hasInitializer()) {
570 assert(SGV->getLinkage() == DGV->getLinkage());
571 if (SGV->hasExternalLinkage()) {
572 if (DGV->getInitializer() != SInit)
573 return Error(Err, "Global Variable Collision on '" +
574 SGV->getType()->getDescription() +"':%"+SGV->getName()+
575 " - Global variables have different initializers");
576 } else if (DGV->hasLinkOnceLinkage() || DGV->hasWeakLinkage()) {
577 // Nothing is required, mapped values will take the new global
579 } else if (DGV->hasAppendingLinkage()) {
580 assert(0 && "Appending linkage unimplemented!");
582 assert(0 && "Unknown linkage!");
585 // Copy the initializer over now...
586 DGV->setInitializer(SInit);
593 // LinkFunctionProtos - Link the functions together between the two modules,
594 // without doing function bodies... this just adds external function prototypes
595 // to the Dest function...
597 static bool LinkFunctionProtos(Module *Dest, const Module *Src,
598 std::map<const Value*, Value*> &ValueMap,
600 SymbolTable *ST = (SymbolTable*)&Dest->getSymbolTable();
602 // Loop over all of the functions in the src module, mapping them over as we
605 for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) {
606 const Function *SF = I; // SrcFunction
609 // The same named thing is a Function, because the only two things
610 // that may be in a module level symbol table are Global Vars and
611 // Functions, and they both have distinct, nonoverlapping, possible types.
613 DF = cast_or_null<Function>(FindGlobalNamed(SF->getName(), SF->getType(),
616 if (!DF || SF->hasInternalLinkage() || DF->hasInternalLinkage()) {
617 // Function does not already exist, simply insert an function signature
618 // identical to SF into the dest module...
619 Function *NewDF = new Function(SF->getFunctionType(), SF->getLinkage(),
620 SF->getName(), Dest);
622 // If the LLVM runtime renamed the function, but it is an externally
623 // visible symbol, DF must be an existing function with internal linkage.
625 if (NewDF->getName() != SF->getName() && !NewDF->hasInternalLinkage()) {
626 assert(DF && DF->getName() == SF->getName() &&DF->hasInternalLinkage());
628 NewDF->setName(SF->getName()); // Force the name back
629 DF->setName(SF->getName()); // This will cause a renaming
630 assert(NewDF->getName() == SF->getName() &&
631 DF->getName() != SF->getName());
634 // ... and remember this mapping...
635 ValueMap.insert(std::make_pair(SF, NewDF));
636 } else if (SF->isExternal()) {
637 // If SF is external or if both SF & DF are external.. Just link the
638 // external functions, we aren't adding anything.
639 ValueMap.insert(std::make_pair(SF, DF));
640 } else if (DF->isExternal()) { // If DF is external but SF is not...
641 // Link the external functions, update linkage qualifiers
642 ValueMap.insert(std::make_pair(SF, DF));
643 DF->setLinkage(SF->getLinkage());
645 } else if (SF->hasWeakLinkage() || SF->hasLinkOnceLinkage()) {
646 // At this point we know that DF has LinkOnce, Weak, or External linkage.
647 ValueMap.insert(std::make_pair(SF, DF));
649 // Linkonce+Weak = Weak
650 if (DF->hasLinkOnceLinkage() && SF->hasWeakLinkage())
651 DF->setLinkage(SF->getLinkage());
653 } else if (DF->hasWeakLinkage() || DF->hasLinkOnceLinkage()) {
654 // At this point we know that SF has LinkOnce or External linkage.
655 ValueMap.insert(std::make_pair(SF, DF));
656 if (!SF->hasLinkOnceLinkage()) // Don't inherit linkonce linkage
657 DF->setLinkage(SF->getLinkage());
659 } else if (SF->getLinkage() != DF->getLinkage()) {
660 return Error(Err, "Functions named '" + SF->getName() +
661 "' have different linkage specifiers!");
662 } else if (SF->hasExternalLinkage()) {
663 // The function is defined in both modules!!
664 return Error(Err, "Function '" +
665 SF->getFunctionType()->getDescription() + "':\"" +
666 SF->getName() + "\" - Function is already defined!");
668 assert(0 && "Unknown linkage configuration found!");
674 // LinkFunctionBody - Copy the source function over into the dest function and
675 // fix up references to values. At this point we know that Dest is an external
676 // function, and that Src is not.
678 static bool LinkFunctionBody(Function *Dest, const Function *Src,
679 std::map<const Value*, Value*> &GlobalMap,
681 assert(Src && Dest && Dest->isExternal() && !Src->isExternal());
682 std::map<const Value*, Value*> LocalMap; // Map for function local values
684 // Go through and convert function arguments over...
685 Function::aiterator DI = Dest->abegin();
686 for (Function::const_aiterator I = Src->abegin(), E = Src->aend();
688 DI->setName(I->getName()); // Copy the name information over...
690 // Add a mapping to our local map
691 LocalMap.insert(std::make_pair(I, DI));
694 // Loop over all of the basic blocks, copying the instructions over...
696 for (Function::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) {
697 // Create new basic block and add to mapping and the Dest function...
698 BasicBlock *DBB = new BasicBlock(I->getName(), Dest);
699 LocalMap.insert(std::make_pair(I, DBB));
701 // Loop over all of the instructions in the src basic block, copying them
702 // over. Note that this is broken in a strict sense because the cloned
703 // instructions will still be referencing values in the Src module, not
704 // the remapped values. In our case, however, we will not get caught and
705 // so we can delay patching the values up until later...
707 for (BasicBlock::const_iterator II = I->begin(), IE = I->end();
709 Instruction *DI = II->clone();
710 DI->setName(II->getName());
711 DBB->getInstList().push_back(DI);
712 LocalMap.insert(std::make_pair(II, DI));
716 // At this point, all of the instructions and values of the function are now
717 // copied over. The only problem is that they are still referencing values in
718 // the Source function as operands. Loop through all of the operands of the
719 // functions and patch them up to point to the local versions...
721 for (Function::iterator BB = Dest->begin(), BE = Dest->end(); BB != BE; ++BB)
722 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
723 for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end();
725 *OI = RemapOperand(*OI, LocalMap, &GlobalMap);
731 // LinkFunctionBodies - Link in the function bodies that are defined in the
732 // source module into the DestModule. This consists basically of copying the
733 // function over and fixing up references to values.
735 static bool LinkFunctionBodies(Module *Dest, const Module *Src,
736 std::map<const Value*, Value*> &ValueMap,
739 // Loop over all of the functions in the src module, mapping them over as we
742 for (Module::const_iterator SF = Src->begin(), E = Src->end(); SF != E; ++SF){
743 if (!SF->isExternal()) { // No body if function is external
744 Function *DF = cast<Function>(ValueMap[SF]); // Destination function
746 // DF not external SF external?
747 if (DF->isExternal()) {
748 // Only provide the function body if there isn't one already.
749 if (LinkFunctionBody(DF, SF, ValueMap, Err))
757 // LinkAppendingVars - If there were any appending global variables, link them
758 // together now. Return true on error.
760 static bool LinkAppendingVars(Module *M,
761 std::multimap<std::string, GlobalVariable *> &AppendingVars,
762 std::string *ErrorMsg) {
763 if (AppendingVars.empty()) return false; // Nothing to do.
765 // Loop over the multimap of appending vars, processing any variables with the
766 // same name, forming a new appending global variable with both of the
767 // initializers merged together, then rewrite references to the old variables
770 std::vector<Constant*> Inits;
771 while (AppendingVars.size() > 1) {
772 // Get the first two elements in the map...
773 std::multimap<std::string,
774 GlobalVariable*>::iterator Second = AppendingVars.begin(), First=Second++;
776 // If the first two elements are for different names, there is no pair...
777 // Otherwise there is a pair, so link them together...
778 if (First->first == Second->first) {
779 GlobalVariable *G1 = First->second, *G2 = Second->second;
780 const ArrayType *T1 = cast<ArrayType>(G1->getType()->getElementType());
781 const ArrayType *T2 = cast<ArrayType>(G2->getType()->getElementType());
783 // Check to see that they two arrays agree on type...
784 if (T1->getElementType() != T2->getElementType())
785 return Error(ErrorMsg,
786 "Appending variables with different element types need to be linked!");
787 if (G1->isConstant() != G2->isConstant())
788 return Error(ErrorMsg,
789 "Appending variables linked with different const'ness!");
791 unsigned NewSize = T1->getNumElements() + T2->getNumElements();
792 ArrayType *NewType = ArrayType::get(T1->getElementType(), NewSize);
794 // Create the new global variable...
796 new GlobalVariable(NewType, G1->isConstant(), G1->getLinkage(),
797 /*init*/0, First->first, M);
799 // Merge the initializer...
800 Inits.reserve(NewSize);
801 ConstantArray *I = cast<ConstantArray>(G1->getInitializer());
802 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i)
803 Inits.push_back(cast<Constant>(I->getValues()[i]));
804 I = cast<ConstantArray>(G2->getInitializer());
805 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i)
806 Inits.push_back(cast<Constant>(I->getValues()[i]));
807 NG->setInitializer(ConstantArray::get(NewType, Inits));
810 // Replace any uses of the two global variables with uses of the new
813 // FIXME: This should rewrite simple/straight-forward uses such as
814 // getelementptr instructions to not use the Cast!
815 ConstantPointerRef *NGCP = ConstantPointerRef::get(NG);
816 G1->replaceAllUsesWith(ConstantExpr::getCast(NGCP, G1->getType()));
817 G2->replaceAllUsesWith(ConstantExpr::getCast(NGCP, G2->getType()));
819 // Remove the two globals from the module now...
820 M->getGlobalList().erase(G1);
821 M->getGlobalList().erase(G2);
823 // Put the new global into the AppendingVars map so that we can handle
824 // linking of more than two vars...
827 AppendingVars.erase(First);
834 // LinkModules - This function links two modules together, with the resulting
835 // left module modified to be the composite of the two input modules. If an
836 // error occurs, true is returned and ErrorMsg (if not null) is set to indicate
837 // the problem. Upon failure, the Dest module could be in a modified state, and
838 // shouldn't be relied on to be consistent.
840 bool LinkModules(Module *Dest, const Module *Src, std::string *ErrorMsg) {
841 if (Dest->getEndianness() == Module::AnyEndianness)
842 Dest->setEndianness(Src->getEndianness());
843 if (Dest->getPointerSize() == Module::AnyPointerSize)
844 Dest->setPointerSize(Src->getPointerSize());
846 if (Src->getEndianness() != Module::AnyEndianness &&
847 Dest->getEndianness() != Src->getEndianness())
848 std::cerr << "WARNING: Linking two modules of different endianness!\n";
849 if (Src->getPointerSize() != Module::AnyPointerSize &&
850 Dest->getPointerSize() != Src->getPointerSize())
851 std::cerr << "WARNING: Linking two modules of different pointer size!\n";
853 // LinkTypes - Go through the symbol table of the Src module and see if any
854 // types are named in the src module that are not named in the Dst module.
855 // Make sure there are no type name conflicts.
857 if (LinkTypes(Dest, Src, ErrorMsg)) return true;
859 // ValueMap - Mapping of values from what they used to be in Src, to what they
862 std::map<const Value*, Value*> ValueMap;
864 // AppendingVars - Keep track of global variables in the destination module
865 // with appending linkage. After the module is linked together, they are
866 // appended and the module is rewritten.
868 std::multimap<std::string, GlobalVariable *> AppendingVars;
870 // Add all of the appending globals already in the Dest module to
872 for (Module::giterator I = Dest->gbegin(), E = Dest->gend(); I != E; ++I)
873 if (I->hasAppendingLinkage())
874 AppendingVars.insert(std::make_pair(I->getName(), I));
876 // Insert all of the globals in src into the Dest module... without linking
877 // initializers (which could refer to functions not yet mapped over).
879 if (LinkGlobals(Dest, Src, ValueMap, AppendingVars, ErrorMsg)) return true;
881 // Link the functions together between the two modules, without doing function
882 // bodies... this just adds external function prototypes to the Dest
883 // function... We do this so that when we begin processing function bodies,
884 // all of the global values that may be referenced are available in our
887 if (LinkFunctionProtos(Dest, Src, ValueMap, ErrorMsg)) return true;
889 // Update the initializers in the Dest module now that all globals that may
890 // be referenced are in Dest.
892 if (LinkGlobalInits(Dest, Src, ValueMap, ErrorMsg)) return true;
894 // Link in the function bodies that are defined in the source module into the
895 // DestModule. This consists basically of copying the function over and
896 // fixing up references to values.
898 if (LinkFunctionBodies(Dest, Src, ValueMap, ErrorMsg)) return true;
900 // If there were any appending global variables, link them together now.
902 if (LinkAppendingVars(Dest, AppendingVars, ErrorMsg)) return true;
907 } // End llvm namespace