1 //===- Linker.cpp - Module Linker Implementation --------------------------===//
3 // This file implements the LLVM module linker.
6 // * Merges global variables between the two modules
7 // * Uninit + Uninit = Init, Init + Uninit = Init, Init + Init = Error if !=
8 // * Merges functions between two modules
10 //===----------------------------------------------------------------------===//
12 #include "llvm/Transforms/Utils/Linker.h"
13 #include "llvm/Module.h"
14 #include "llvm/SymbolTable.h"
15 #include "llvm/DerivedTypes.h"
16 #include "llvm/iOther.h"
17 #include "llvm/Constants.h"
19 // Error - Simple wrapper function to conditionally assign to E and return true.
20 // This just makes error return conditions a little bit simpler...
22 static inline bool Error(std::string *E, std::string Message) {
27 // LinkTypes - Go through the symbol table of the Src module and see if any
28 // types are named in the src module that are not named in the Dst module.
29 // Make sure there are no type name conflicts.
31 static bool LinkTypes(Module *Dest, const Module *Src, std::string *Err) {
32 SymbolTable *DestST = &Dest->getSymbolTable();
33 const SymbolTable *SrcST = &Src->getSymbolTable();
35 // Look for a type plane for Type's...
36 SymbolTable::const_iterator PI = SrcST->find(Type::TypeTy);
37 if (PI == SrcST->end()) return false; // No named types, do nothing.
39 const SymbolTable::VarMap &VM = PI->second;
40 for (SymbolTable::type_const_iterator I = VM.begin(), E = VM.end();
42 const std::string &Name = I->first;
43 const Type *RHS = cast<Type>(I->second);
45 // Check to see if this type name is already in the dest module...
46 const Type *Entry = cast_or_null<Type>(DestST->lookup(Type::TypeTy, Name));
47 if (Entry && !isa<OpaqueType>(Entry)) { // Yup, the value already exists...
49 if (OpaqueType *OT = dyn_cast<OpaqueType>(const_cast<Type*>(RHS))) {
50 OT->refineAbstractTypeTo(Entry);
52 // If it's the same, noop. Otherwise, error.
53 return Error(Err, "Type named '" + Name +
54 "' of different shape in modules.\n Src='" +
55 Entry->getDescription() + "'.\n Dst='" +
56 RHS->getDescription() + "'");
59 } else { // Type not in dest module. Add it now.
61 OpaqueType *OT = cast<OpaqueType>(const_cast<Type*>(Entry));
62 OT->refineAbstractTypeTo(RHS);
65 // TODO: FIXME WHEN TYPES AREN'T CONST
66 DestST->insert(Name, const_cast<Type*>(RHS));
72 static void PrintMap(const std::map<const Value*, Value*> &M) {
73 for (std::map<const Value*, Value*>::const_iterator I = M.begin(), E =M.end();
75 std::cerr << " Fr: " << (void*)I->first << " ";
77 std::cerr << " To: " << (void*)I->second << " ";
84 // RemapOperand - Use LocalMap and GlobalMap to convert references from one
85 // module to another. This is somewhat sophisticated in that it can
86 // automatically handle constant references correctly as well...
88 static Value *RemapOperand(const Value *In,
89 std::map<const Value*, Value*> &LocalMap,
90 std::map<const Value*, Value*> *GlobalMap) {
91 std::map<const Value*,Value*>::const_iterator I = LocalMap.find(In);
92 if (I != LocalMap.end()) return I->second;
95 I = GlobalMap->find(In);
96 if (I != GlobalMap->end()) return I->second;
99 // Check to see if it's a constant that we are interesting in transforming...
100 if (const Constant *CPV = dyn_cast<Constant>(In)) {
101 if (!isa<DerivedType>(CPV->getType()) && !isa<ConstantExpr>(CPV))
102 return const_cast<Constant*>(CPV); // Simple constants stay identical...
104 Constant *Result = 0;
106 if (const ConstantArray *CPA = dyn_cast<ConstantArray>(CPV)) {
107 const std::vector<Use> &Ops = CPA->getValues();
108 std::vector<Constant*> Operands(Ops.size());
109 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
111 cast<Constant>(RemapOperand(Ops[i], LocalMap, GlobalMap));
112 Result = ConstantArray::get(cast<ArrayType>(CPA->getType()), Operands);
113 } else if (const ConstantStruct *CPS = dyn_cast<ConstantStruct>(CPV)) {
114 const std::vector<Use> &Ops = CPS->getValues();
115 std::vector<Constant*> Operands(Ops.size());
116 for (unsigned i = 0; i < Ops.size(); ++i)
118 cast<Constant>(RemapOperand(Ops[i], LocalMap, GlobalMap));
119 Result = ConstantStruct::get(cast<StructType>(CPS->getType()), Operands);
120 } else if (isa<ConstantPointerNull>(CPV)) {
121 Result = const_cast<Constant*>(CPV);
122 } else if (const ConstantPointerRef *CPR =
123 dyn_cast<ConstantPointerRef>(CPV)) {
124 Value *V = RemapOperand(CPR->getValue(), LocalMap, GlobalMap);
125 Result = ConstantPointerRef::get(cast<GlobalValue>(V));
126 } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CPV)) {
127 if (CE->getOpcode() == Instruction::GetElementPtr) {
128 Value *Ptr = RemapOperand(CE->getOperand(0), LocalMap, GlobalMap);
129 std::vector<Constant*> Indices;
130 Indices.reserve(CE->getNumOperands()-1);
131 for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
132 Indices.push_back(cast<Constant>(RemapOperand(CE->getOperand(i),
133 LocalMap, GlobalMap)));
135 Result = ConstantExpr::getGetElementPtr(cast<Constant>(Ptr), Indices);
136 } else if (CE->getNumOperands() == 1) {
138 assert(CE->getOpcode() == Instruction::Cast);
139 Value *V = RemapOperand(CE->getOperand(0), LocalMap, GlobalMap);
140 Result = ConstantExpr::getCast(cast<Constant>(V), CE->getType());
141 } else if (CE->getNumOperands() == 2) {
142 // Binary operator...
143 Value *V1 = RemapOperand(CE->getOperand(0), LocalMap, GlobalMap);
144 Value *V2 = RemapOperand(CE->getOperand(1), LocalMap, GlobalMap);
146 Result = ConstantExpr::get(CE->getOpcode(), cast<Constant>(V1),
149 assert(0 && "Unknown constant expr type!");
153 assert(0 && "Unknown type of derived type constant value!");
156 // Cache the mapping in our local map structure...
158 GlobalMap->insert(std::make_pair(In, Result));
160 LocalMap.insert(std::make_pair(In, Result));
164 std::cerr << "XXX LocalMap: \n";
168 std::cerr << "XXX GlobalMap: \n";
169 PrintMap(*GlobalMap);
172 std::cerr << "Couldn't remap value: " << (void*)In << " " << *In << "\n";
173 assert(0 && "Couldn't remap value!");
178 // LinkGlobals - Loop through the global variables in the src module and merge
179 // them into the dest module...
181 static bool LinkGlobals(Module *Dest, const Module *Src,
182 std::map<const Value*, Value*> &ValueMap,
184 // We will need a module level symbol table if the src module has a module
185 // level symbol table...
186 SymbolTable *ST = (SymbolTable*)&Dest->getSymbolTable();
188 // Loop over all of the globals in the src module, mapping them over as we go
190 for (Module::const_giterator I = Src->gbegin(), E = Src->gend(); I != E; ++I){
191 const GlobalVariable *SGV = I;
192 GlobalVariable *DGV = 0;
193 if (SGV->hasName()) {
194 // A same named thing is a global variable, because the only two things
195 // that may be in a module level symbol table are Global Vars and
196 // Functions, and they both have distinct, nonoverlapping, possible types.
198 DGV = cast_or_null<GlobalVariable>(ST->lookup(SGV->getType(),
202 assert(SGV->hasInitializer() || SGV->hasExternalLinkage() &&
203 "Global must either be external or have an initializer!");
205 if (!DGV || DGV->hasInternalLinkage() || SGV->hasInternalLinkage()) {
206 // No linking to be performed, simply create an identical version of the
207 // symbol over in the dest module... the initializer will be filled in
208 // later by LinkGlobalInits...
210 DGV = new GlobalVariable(SGV->getType()->getElementType(),
211 SGV->isConstant(), SGV->getLinkage(), /*init*/0,
212 SGV->getName(), Dest);
214 // Make sure to remember this mapping...
215 ValueMap.insert(std::make_pair(SGV, DGV));
216 } else if (SGV->getLinkage() != DGV->getLinkage()) {
217 return Error(Err, "Global variables named '" + SGV->getName() +
218 "' have different linkage specifiers!");
219 } else if (SGV->hasExternalLinkage() || SGV->hasLinkOnceLinkage() ||
220 SGV->hasAppendingLinkage()) {
221 // If the global variable has a name, and that name is already in use in
222 // the Dest module, make sure that the name is a compatible global
225 // Check to see if the two GV's have the same Const'ness...
226 if (SGV->isConstant() != DGV->isConstant())
227 return Error(Err, "Global Variable Collision on '" +
228 SGV->getType()->getDescription() + "':%" + SGV->getName() +
229 " - Global variables differ in const'ness");
230 // Okay, everything is cool, remember the mapping...
231 ValueMap.insert(std::make_pair(SGV, DGV));
233 assert(0 && "Unknown linkage!");
240 // LinkGlobalInits - Update the initializers in the Dest module now that all
241 // globals that may be referenced are in Dest.
243 static bool LinkGlobalInits(Module *Dest, const Module *Src,
244 std::map<const Value*, Value*> &ValueMap,
247 // Loop over all of the globals in the src module, mapping them over as we go
249 for (Module::const_giterator I = Src->gbegin(), E = Src->gend(); I != E; ++I){
250 const GlobalVariable *SGV = I;
252 if (SGV->hasInitializer()) { // Only process initialized GV's
253 // Figure out what the initializer looks like in the dest module...
255 cast<Constant>(RemapOperand(SGV->getInitializer(), ValueMap, 0));
257 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[SGV]);
258 if (DGV->hasInitializer()) {
259 assert(SGV->getLinkage() == DGV->getLinkage());
260 if (SGV->hasExternalLinkage()) {
261 if (DGV->getInitializer() != SInit)
262 return Error(Err, "Global Variable Collision on '" +
263 SGV->getType()->getDescription() +"':%"+SGV->getName()+
264 " - Global variables have different initializers");
265 } else if (DGV->hasLinkOnceLinkage()) {
266 // Nothing is required, mapped values will take the new global
268 } else if (DGV->hasAppendingLinkage()) {
269 assert(0 && "Appending linkage unimplemented!");
271 assert(0 && "Unknown linkage!");
274 // Copy the initializer over now...
275 DGV->setInitializer(SInit);
282 // LinkFunctionProtos - Link the functions together between the two modules,
283 // without doing function bodies... this just adds external function prototypes
284 // to the Dest function...
286 static bool LinkFunctionProtos(Module *Dest, const Module *Src,
287 std::map<const Value*, Value*> &ValueMap,
289 SymbolTable *ST = (SymbolTable*)&Dest->getSymbolTable();
291 // Loop over all of the functions in the src module, mapping them over as we
294 for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) {
295 const Function *SF = I; // SrcFunction
298 // The same named thing is a Function, because the only two things
299 // that may be in a module level symbol table are Global Vars and
300 // Functions, and they both have distinct, nonoverlapping, possible types.
302 DF = cast_or_null<Function>(ST->lookup(SF->getType(), SF->getName()));
304 if (!DF || SF->hasInternalLinkage() || DF->hasInternalLinkage()) {
305 // Function does not already exist, simply insert an external function
306 // signature identical to SF into the dest module...
307 Function *DF = new Function(SF->getFunctionType(), SF->getLinkage(),
308 SF->getName(), Dest);
310 // ... and remember this mapping...
311 ValueMap.insert(std::make_pair(SF, DF));
312 } else if (SF->getLinkage() != DF->getLinkage()) {
313 return Error(Err, "Functions named '" + SF->getName() +
314 "' have different linkage specifiers!");
315 } else if (SF->getLinkage() == GlobalValue::AppendingLinkage) {
316 return Error(Err, "Functions named '" + SF->getName() +
317 "' have appending linkage!");
318 } else if (SF->getLinkage() == GlobalValue::ExternalLinkage) {
319 // If the function has a name, and that name is already in use in the Dest
320 // module, make sure that the name is a compatible function...
322 // Check to make sure the function is not defined in both modules...
323 if (!SF->isExternal() && !DF->isExternal())
324 return Error(Err, "Function '" +
325 SF->getFunctionType()->getDescription() + "':\"" +
326 SF->getName() + "\" - Function is already defined!");
328 // Otherwise, just remember this mapping...
329 ValueMap.insert(std::make_pair(SF, DF));
330 } else if (SF->getLinkage() == GlobalValue::LinkOnceLinkage) {
331 // Completely ignore the source function.
332 ValueMap.insert(std::make_pair(SF, DF));
338 // LinkFunctionBody - Copy the source function over into the dest function and
339 // fix up references to values. At this point we know that Dest is an external
340 // function, and that Src is not.
342 static bool LinkFunctionBody(Function *Dest, const Function *Src,
343 std::map<const Value*, Value*> &GlobalMap,
345 assert(Src && Dest && Dest->isExternal() && !Src->isExternal());
346 std::map<const Value*, Value*> LocalMap; // Map for function local values
348 // Go through and convert function arguments over...
349 Function::aiterator DI = Dest->abegin();
350 for (Function::const_aiterator I = Src->abegin(), E = Src->aend();
352 DI->setName(I->getName()); // Copy the name information over...
354 // Add a mapping to our local map
355 LocalMap.insert(std::make_pair(I, DI));
358 // Loop over all of the basic blocks, copying the instructions over...
360 for (Function::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) {
361 // Create new basic block and add to mapping and the Dest function...
362 BasicBlock *DBB = new BasicBlock(I->getName(), Dest);
363 LocalMap.insert(std::make_pair(I, DBB));
365 // Loop over all of the instructions in the src basic block, copying them
366 // over. Note that this is broken in a strict sense because the cloned
367 // instructions will still be referencing values in the Src module, not
368 // the remapped values. In our case, however, we will not get caught and
369 // so we can delay patching the values up until later...
371 for (BasicBlock::const_iterator II = I->begin(), IE = I->end();
373 Instruction *DI = II->clone();
374 DI->setName(II->getName());
375 DBB->getInstList().push_back(DI);
376 LocalMap.insert(std::make_pair(II, DI));
380 // At this point, all of the instructions and values of the function are now
381 // copied over. The only problem is that they are still referencing values in
382 // the Source function as operands. Loop through all of the operands of the
383 // functions and patch them up to point to the local versions...
385 for (Function::iterator BB = Dest->begin(), BE = Dest->end(); BB != BE; ++BB)
386 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
387 for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end();
389 *OI = RemapOperand(*OI, LocalMap, &GlobalMap);
395 // LinkFunctionBodies - Link in the function bodies that are defined in the
396 // source module into the DestModule. This consists basically of copying the
397 // function over and fixing up references to values.
399 static bool LinkFunctionBodies(Module *Dest, const Module *Src,
400 std::map<const Value*, Value*> &ValueMap,
403 // Loop over all of the functions in the src module, mapping them over as we
406 for (Module::const_iterator SF = Src->begin(), E = Src->end(); SF != E; ++SF){
407 if (!SF->isExternal()) { // No body if function is external
408 Function *DF = cast<Function>(ValueMap[SF]); // Destination function
410 // DF not external SF external?
411 if (!DF->isExternal()) {
412 if (DF->hasLinkOnceLinkage()) continue; // No relinkage for link-once!
414 *Err = "Function '" + (SF->hasName() ? SF->getName() :std::string(""))
415 + "' body multiply defined!";
419 if (LinkFunctionBody(DF, SF, ValueMap, Err)) return true;
427 // LinkModules - This function links two modules together, with the resulting
428 // left module modified to be the composite of the two input modules. If an
429 // error occurs, true is returned and ErrorMsg (if not null) is set to indicate
430 // the problem. Upon failure, the Dest module could be in a modified state, and
431 // shouldn't be relied on to be consistent.
433 bool LinkModules(Module *Dest, const Module *Src, std::string *ErrorMsg) {
435 // LinkTypes - Go through the symbol table of the Src module and see if any
436 // types are named in the src module that are not named in the Dst module.
437 // Make sure there are no type name conflicts.
439 if (LinkTypes(Dest, Src, ErrorMsg)) return true;
441 // ValueMap - Mapping of values from what they used to be in Src, to what they
444 std::map<const Value*, Value*> ValueMap;
446 // Insert all of the globals in src into the Dest module... without
448 if (LinkGlobals(Dest, Src, ValueMap, ErrorMsg)) return true;
450 // Link the functions together between the two modules, without doing function
451 // bodies... this just adds external function prototypes to the Dest
452 // function... We do this so that when we begin processing function bodies,
453 // all of the global values that may be referenced are available in our
456 if (LinkFunctionProtos(Dest, Src, ValueMap, ErrorMsg)) return true;
458 // Update the initializers in the Dest module now that all globals that may
459 // be referenced are in Dest.
461 if (LinkGlobalInits(Dest, Src, ValueMap, ErrorMsg)) return true;
463 // Link in the function bodies that are defined in the source module into the
464 // DestModule. This consists basically of copying the function over and
465 // fixing up references to values.
467 if (LinkFunctionBodies(Dest, Src, ValueMap, ErrorMsg)) return true;