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 methods between two modules
10 //===----------------------------------------------------------------------===//
12 #include "llvm/Transforms/Linker.h"
13 #include "llvm/Module.h"
14 #include "llvm/Function.h"
15 #include "llvm/BasicBlock.h"
16 #include "llvm/GlobalVariable.h"
17 #include "llvm/SymbolTable.h"
18 #include "llvm/DerivedTypes.h"
19 #include "llvm/iOther.h"
20 #include "llvm/Constants.h"
21 #include "llvm/Argument.h"
27 // Error - Simple wrapper function to conditionally assign to E and return true.
28 // This just makes error return conditions a little bit simpler...
30 static inline bool Error(string *E, string Message) {
35 // LinkTypes - Go through the symbol table of the Src module and see if any
36 // types are named in the src module that are not named in the Dst module.
37 // Make sure there are no type name conflicts.
39 static bool LinkTypes(Module *Dest, const Module *Src, string *Err = 0) {
40 // No symbol table? Can't have named types.
41 if (!Src->hasSymbolTable()) return false;
43 SymbolTable *DestST = Dest->getSymbolTableSure();
44 const SymbolTable *SrcST = Src->getSymbolTable();
46 // Look for a type plane for Type's...
47 SymbolTable::const_iterator PI = SrcST->find(Type::TypeTy);
48 if (PI == SrcST->end()) return false; // No named types, do nothing.
50 const SymbolTable::VarMap &VM = PI->second;
51 for (SymbolTable::type_const_iterator I = VM.begin(), E = VM.end();
53 const string &Name = I->first;
54 const Type *RHS = cast<Type>(I->second);
56 // Check to see if this type name is already in the dest module...
57 const Type *Entry = cast_or_null<Type>(DestST->lookup(Type::TypeTy, Name));
58 if (Entry) { // Yup, the value already exists...
59 if (Entry != RHS) // If it's the same, noop. Otherwise, error.
60 return Error(Err, "Type named '" + Name +
61 "' of different shape in modules.\n Src='" +
62 Entry->getDescription() + "'.\n Dst='" +
63 RHS->getDescription() + "'");
64 } else { // Type not in dest module. Add it now.
65 // TODO: FIXME WHEN TYPES AREN'T CONST
66 DestST->insert(Name, const_cast<Type*>(RHS));
72 static void PrintMap(const map<const Value*, Value*> &M) {
73 for (map<const Value*, Value*>::const_iterator I = M.begin(), E = M.end();
75 cerr << " Fr: " << (void*)I->first << " ";
77 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, map<const Value*, Value*> &LocalMap,
89 const map<const Value*, Value*> *GlobalMap = 0) {
90 map<const Value*,Value*>::const_iterator I = LocalMap.find(In);
91 if (I != LocalMap.end()) return I->second;
94 I = GlobalMap->find(In);
95 if (I != GlobalMap->end()) return I->second;
98 // Check to see if it's a constant that we are interesting in transforming...
99 if (Constant *CPV = dyn_cast<Constant>(In)) {
100 if (!isa<DerivedType>(CPV->getType()))
101 return CPV; // Simple constants stay identical...
103 Constant *Result = 0;
105 if (ConstantArray *CPA = dyn_cast<ConstantArray>(CPV)) {
106 const std::vector<Use> &Ops = CPA->getValues();
107 std::vector<Constant*> Operands(Ops.size());
108 for (unsigned i = 0; i < Ops.size(); ++i)
110 cast<Constant>(RemapOperand(Ops[i], LocalMap, GlobalMap));
111 Result = ConstantArray::get(cast<ArrayType>(CPA->getType()), Operands);
112 } else if (ConstantStruct *CPS = dyn_cast<ConstantStruct>(CPV)) {
113 const std::vector<Use> &Ops = CPS->getValues();
114 std::vector<Constant*> Operands(Ops.size());
115 for (unsigned i = 0; i < Ops.size(); ++i)
117 cast<Constant>(RemapOperand(Ops[i], LocalMap, GlobalMap));
118 Result = ConstantStruct::get(cast<StructType>(CPS->getType()), Operands);
119 } else if (isa<ConstantPointerNull>(CPV)) {
121 } else if (ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(CPV)) {
122 Value *V = RemapOperand(CPR->getValue(), LocalMap, GlobalMap);
123 Result = ConstantPointerRef::get(cast<GlobalValue>(V));
125 assert(0 && "Unknown type of derived type constant value!");
128 // Cache the mapping in our local map structure...
129 LocalMap.insert(std::make_pair(In, CPV));
133 cerr << "XXX LocalMap: \n";
137 cerr << "XXX GlobalMap: \n";
138 PrintMap(*GlobalMap);
141 cerr << "Couldn't remap value: " << (void*)In << " ";
144 assert(0 && "Couldn't remap value!");
149 // LinkGlobals - Loop through the global variables in the src module and merge
150 // them into the dest module...
152 static bool LinkGlobals(Module *Dest, const Module *Src,
153 map<const Value*, Value*> &ValueMap, string *Err = 0) {
154 // We will need a module level symbol table if the src module has a module
155 // level symbol table...
156 SymbolTable *ST = Src->getSymbolTable() ? Dest->getSymbolTableSure() : 0;
158 // Loop over all of the globals in the src module, mapping them over as we go
160 for (Module::const_giterator I = Src->gbegin(), E = Src->gend(); I != E; ++I){
161 const GlobalVariable *SGV = *I;
164 // If the global variable has a name, and that name is already in use in the
165 // Dest module, make sure that the name is a compatible global variable...
167 if (SGV->hasExternalLinkage() && SGV->hasName() &&
168 (V = ST->lookup(SGV->getType(), SGV->getName())) &&
169 cast<GlobalVariable>(V)->hasExternalLinkage()) {
170 // The same named thing is a global variable, because the only two things
171 // that may be in a module level symbol table are Global Vars and
172 // Functions, and they both have distinct, nonoverlapping, possible types.
174 GlobalVariable *DGV = cast<GlobalVariable>(V);
176 // Check to see if the two GV's have the same Const'ness...
177 if (SGV->isConstant() != DGV->isConstant())
178 return Error(Err, "Global Variable Collision on '" +
179 SGV->getType()->getDescription() + "':%" + SGV->getName() +
180 " - Global variables differ in const'ness");
182 // Okay, everything is cool, remember the mapping...
183 ValueMap.insert(std::make_pair(SGV, DGV));
185 // No linking to be performed, simply create an identical version of the
186 // symbol over in the dest module... the initializer will be filled in
187 // later by LinkGlobalInits...
189 GlobalVariable *DGV =
190 new GlobalVariable(SGV->getType()->getElementType(), SGV->isConstant(),
191 SGV->hasInternalLinkage(), 0, SGV->getName());
193 // Add the new global to the dest module
194 Dest->getGlobalList().push_back(DGV);
196 // Make sure to remember this mapping...
197 ValueMap.insert(std::make_pair(SGV, DGV));
204 // LinkGlobalInits - Update the initializers in the Dest module now that all
205 // globals that may be referenced are in Dest.
207 static bool LinkGlobalInits(Module *Dest, const Module *Src,
208 map<const Value*, Value*> &ValueMap,
211 // Loop over all of the globals in the src module, mapping them over as we go
213 for (Module::const_giterator I = Src->gbegin(), E = Src->gend(); I != E; ++I){
214 const GlobalVariable *SGV = *I;
216 if (SGV->hasInitializer()) { // Only process initialized GV's
217 // Figure out what the initializer looks like in the dest module...
219 cast<Constant>(RemapOperand(SGV->getInitializer(), ValueMap));
221 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[SGV]);
222 if (DGV->hasInitializer() && SGV->hasExternalLinkage() &&
223 DGV->hasExternalLinkage()) {
224 if (DGV->getInitializer() != DInit)
225 return Error(Err, "Global Variable Collision on '" +
226 SGV->getType()->getDescription() + "':%" +SGV->getName()+
227 " - Global variables have different initializers");
229 // Copy the initializer over now...
230 DGV->setInitializer(DInit);
237 // LinkFunctionProtos - Link the functions together between the two modules,
238 // without doing method bodies... this just adds external method prototypes to
239 // the Dest function...
241 static bool LinkFunctionProtos(Module *Dest, const Module *Src,
242 map<const Value*, Value*> &ValueMap,
244 // We will need a module level symbol table if the src module has a module
245 // level symbol table...
246 SymbolTable *ST = Src->getSymbolTable() ? Dest->getSymbolTableSure() : 0;
248 // Loop over all of the methods in the src module, mapping them over as we go
250 for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) {
251 const Function *SM = *I; // SrcFunction
254 // If the method has a name, and that name is already in use in the
255 // Dest module, make sure that the name is a compatible method...
257 if (SM->hasExternalLinkage() && SM->hasName() &&
258 (V = ST->lookup(SM->getType(), SM->getName())) &&
259 cast<Function>(V)->hasExternalLinkage()) {
260 // The same named thing is a Function, because the only two things
261 // that may be in a module level symbol table are Global Vars and
262 // Functions, and they both have distinct, nonoverlapping, possible types.
264 Function *DM = cast<Function>(V); // DestFunction
266 // Check to make sure the method is not defined in both modules...
267 if (!SM->isExternal() && !DM->isExternal())
268 return Error(Err, "Function '" +
269 SM->getFunctionType()->getDescription() + "':\"" +
270 SM->getName() + "\" - Function is already defined!");
272 // Otherwise, just remember this mapping...
273 ValueMap.insert(std::make_pair(SM, DM));
275 // Function does not already exist, simply insert an external method
276 // signature identical to SM into the dest module...
277 Function *DM = new Function(SM->getFunctionType(),
278 SM->hasInternalLinkage(),
281 // Add the method signature to the dest module...
282 Dest->getFunctionList().push_back(DM);
284 // ... and remember this mapping...
285 ValueMap.insert(std::make_pair(SM, DM));
291 // LinkFunctionBody - Copy the source method over into the dest method
292 // and fix up references to values. At this point we know that Dest
293 // is an external method, and that Src is not.
295 static bool LinkFunctionBody(Function *Dest, const Function *Src,
296 const map<const Value*, Value*> &GlobalMap,
298 assert(Src && Dest && Dest->isExternal() && !Src->isExternal());
299 map<const Value*, Value*> LocalMap; // Map for method local values
301 // Go through and convert method arguments over...
302 for (Function::ArgumentListType::const_iterator
303 I = Src->getArgumentList().begin(),
304 E = Src->getArgumentList().end(); I != E; ++I) {
305 const Argument *SMA = *I;
307 // Create the new method argument and add to the dest method...
308 Argument *DMA = new Argument(SMA->getType(), SMA->getName());
309 Dest->getArgumentList().push_back(DMA);
311 // Add a mapping to our local map
312 LocalMap.insert(std::make_pair(SMA, DMA));
315 // Loop over all of the basic blocks, copying the instructions over...
317 for (Function::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) {
318 const BasicBlock *SBB = *I;
320 // Create new basic block and add to mapping and the Dest method...
321 BasicBlock *DBB = new BasicBlock(SBB->getName(), Dest);
322 LocalMap.insert(std::make_pair(SBB, DBB));
324 // Loop over all of the instructions in the src basic block, copying them
325 // over. Note that this is broken in a strict sense because the cloned
326 // instructions will still be referencing values in the Src module, not
327 // the remapped values. In our case, however, we will not get caught and
328 // so we can delay patching the values up until later...
330 for (BasicBlock::const_iterator II = SBB->begin(), IE = SBB->end();
332 const Instruction *SI = *II;
333 Instruction *DI = SI->clone();
334 DI->setName(SI->getName());
335 DBB->getInstList().push_back(DI);
336 LocalMap.insert(std::make_pair(SI, DI));
340 // At this point, all of the instructions and values of the method are now
341 // copied over. The only problem is that they are still referencing values
342 // in the Source method as operands. Loop through all of the operands of the
343 // methods and patch them up to point to the local versions...
345 for (Function::iterator BI = Dest->begin(), BE = Dest->end();
347 BasicBlock *BB = *BI;
348 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
349 Instruction *Inst = *I;
351 for (Instruction::op_iterator OI = Inst->op_begin(), OE = Inst->op_end();
353 *OI = RemapOperand(*OI, LocalMap, &GlobalMap);
361 // LinkFunctionBodies - Link in the method bodies that are defined in the source
362 // module into the DestModule. This consists basically of copying the method
363 // over and fixing up references to values.
365 static bool LinkFunctionBodies(Module *Dest, const Module *Src,
366 map<const Value*, Value*> &ValueMap,
369 // Loop over all of the methods in the src module, mapping them over as we go
371 for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) {
372 const Function *SM = *I; // Source Function
373 if (!SM->isExternal()) { // No body if method is external
374 Function *DM = cast<Function>(ValueMap[SM]); // Destination method
376 // DM not external SM external?
377 if (!DM->isExternal()) {
379 *Err = "Function '" + (SM->hasName() ? SM->getName() : string("")) +
380 "' body multiply defined!";
384 if (LinkFunctionBody(DM, SM, ValueMap, Err)) return true;
392 // LinkModules - This function links two modules together, with the resulting
393 // left module modified to be the composite of the two input modules. If an
394 // error occurs, true is returned and ErrorMsg (if not null) is set to indicate
395 // the problem. Upon failure, the Dest module could be in a modified state, and
396 // shouldn't be relied on to be consistent.
398 bool LinkModules(Module *Dest, const Module *Src, string *ErrorMsg = 0) {
400 // LinkTypes - Go through the symbol table of the Src module and see if any
401 // types are named in the src module that are not named in the Dst module.
402 // Make sure there are no type name conflicts.
404 if (LinkTypes(Dest, Src, ErrorMsg)) return true;
406 // ValueMap - Mapping of values from what they used to be in Src, to what they
409 map<const Value*, Value*> ValueMap;
411 // Insert all of the globals in src into the Dest module... without
413 if (LinkGlobals(Dest, Src, ValueMap, ErrorMsg)) return true;
415 // Update the initializers in the Dest module now that all globals that may
416 // be referenced are in Dest.
418 if (LinkGlobalInits(Dest, Src, ValueMap, ErrorMsg)) return true;
420 // Link the methods together between the two modules, without doing method
421 // bodies... this just adds external method prototypes to the Dest method...
422 // We do this so that when we begin processing method bodies, all of the
423 // global values that may be referenced are available in our ValueMap.
425 if (LinkFunctionProtos(Dest, Src, ValueMap, ErrorMsg)) return true;
427 // Link in the method bodies that are defined in the source module into the
428 // DestModule. This consists basically of copying the method over and fixing
429 // up references to values.
431 if (LinkFunctionBodies(Dest, Src, ValueMap, ErrorMsg)) return true;