LinkModules.cpp revision 7a1767520611d9ff6face702068de858e1cadf2c
1//===- Linker.cpp - Module Linker Implementation --------------------------===// 2// 3// This file implements the LLVM module linker. 4// 5// Specifically, this: 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 9// 10//===----------------------------------------------------------------------===// 11 12#include "llvm/Transforms/Linker.h" 13#include "llvm/Module.h" 14#include "llvm/Method.h" 15#include "llvm/GlobalVariable.h" 16#include "llvm/SymbolTable.h" 17#include "llvm/DerivedTypes.h" 18#include "llvm/iOther.h" 19#include "llvm/ConstantVals.h" 20 21// Error - Simple wrapper function to conditionally assign to E and return true. 22// This just makes error return conditions a little bit simpler... 23// 24static inline bool Error(string *E, string Message) { 25 if (E) *E = Message; 26 return true; 27} 28 29#include "llvm/Assembly/Writer.h" // TODO: REMOVE 30 31 32// LinkTypes - Go through the symbol table of the Src module and see if any 33// types are named in the src module that are not named in the Dst module. 34// Make sure there are no type name conflicts. 35// 36static bool LinkTypes(Module *Dest, const Module *Src, string *Err = 0) { 37 // No symbol table? Can't have named types. 38 if (!Src->hasSymbolTable()) return false; 39 40 SymbolTable *DestST = Dest->getSymbolTableSure(); 41 const SymbolTable *SrcST = Src->getSymbolTable(); 42 43 // Look for a type plane for Type's... 44 SymbolTable::const_iterator PI = SrcST->find(Type::TypeTy); 45 if (PI == SrcST->end()) return false; // No named types, do nothing. 46 47 const SymbolTable::VarMap &VM = PI->second; 48 for (SymbolTable::type_const_iterator I = VM.begin(), E = VM.end(); 49 I != E; ++I) { 50 const string &Name = I->first; 51 const Type *RHS = cast<Type>(I->second); 52 53 // Check to see if this type name is already in the dest module... 54 const Type *Entry = cast_or_null<Type>(DestST->lookup(Type::TypeTy, Name)); 55 if (Entry) { // Yup, the value already exists... 56 if (Entry != RHS) // If it's the same, noop. Otherwise, error. 57 return Error(Err, "Type named '" + Name + 58 "' of different shape in modules.\n Src='" + 59 Entry->getDescription() + "'. Dest='" + 60 RHS->getDescription() + "'"); 61 } else { // Type not in dest module. Add it now. 62 // TODO: FIXME WHEN TYPES AREN'T CONST 63 DestST->insert(Name, const_cast<Type*>(RHS)); 64 } 65 } 66 return false; 67} 68 69static void PrintMap(const map<const Value*, Value*> &M) { 70 for (map<const Value*, Value*>::const_iterator I = M.begin(), E = M.end(); 71 I != E; ++I) { 72 cerr << " Fr: " << (void*)I->first << " " << I->first 73 << " To: " << (void*)I->second << " " << I->second << endl; 74 } 75} 76 77 78// RemapOperand - Use LocalMap and GlobalMap to convert references from one 79// module to another. This is somewhat sophisticated in that it can 80// automatically handle constant references correctly as well... 81// 82static Value *RemapOperand(const Value *In, map<const Value*, Value*> &LocalMap, 83 const map<const Value*, Value*> *GlobalMap = 0) { 84 map<const Value*,Value*>::const_iterator I = LocalMap.find(In); 85 if (I != LocalMap.end()) return I->second; 86 87 if (GlobalMap) { 88 I = GlobalMap->find(In); 89 if (I != GlobalMap->end()) return I->second; 90 } 91 92 // Check to see if it's a constant that we are interesting in transforming... 93 if (Constant *CPV = dyn_cast<Constant>(In)) { 94 if (!isa<DerivedType>(CPV->getType())) 95 return CPV; // Simple constants stay identical... 96 97 Constant *Result = 0; 98 99 if (ConstantArray *CPA = dyn_cast<ConstantArray>(CPV)) { 100 const vector<Use> &Ops = CPA->getValues(); 101 vector<Constant*> Operands(Ops.size()); 102 for (unsigned i = 0; i < Ops.size(); ++i) 103 Operands[i] = 104 cast<Constant>(RemapOperand(Ops[i], LocalMap, GlobalMap)); 105 Result = ConstantArray::get(cast<ArrayType>(CPA->getType()), Operands); 106 } else if (ConstantStruct *CPS = dyn_cast<ConstantStruct>(CPV)) { 107 const vector<Use> &Ops = CPS->getValues(); 108 vector<Constant*> Operands(Ops.size()); 109 for (unsigned i = 0; i < Ops.size(); ++i) 110 Operands[i] = 111 cast<Constant>(RemapOperand(Ops[i], LocalMap, GlobalMap)); 112 Result = ConstantStruct::get(cast<StructType>(CPS->getType()), Operands); 113 } else if (isa<ConstantPointerNull>(CPV)) { 114 Result = CPV; 115 } else if (ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(CPV)) { 116 Value *V = RemapOperand(CPR->getValue(), LocalMap, GlobalMap); 117 Result = ConstantPointerRef::get(cast<GlobalValue>(V)); 118 } else { 119 assert(0 && "Unknown type of derived type constant value!"); 120 } 121 122 // Cache the mapping in our local map structure... 123 LocalMap.insert(make_pair(In, CPV)); 124 return Result; 125 } 126 127 cerr << "XXX LocalMap: \n"; 128 PrintMap(LocalMap); 129 130 if (GlobalMap) { 131 cerr << "XXX GlobalMap: \n"; 132 PrintMap(*GlobalMap); 133 } 134 135 cerr << "Couldn't remap value: " << (void*)In << " " << In << endl; 136 assert(0 && "Couldn't remap value!"); 137 return 0; 138} 139 140 141// LinkGlobals - Loop through the global variables in the src module and merge 142// them into the dest module... 143// 144static bool LinkGlobals(Module *Dest, const Module *Src, 145 map<const Value*, Value*> &ValueMap, string *Err = 0) { 146 // We will need a module level symbol table if the src module has a module 147 // level symbol table... 148 SymbolTable *ST = Src->getSymbolTable() ? Dest->getSymbolTableSure() : 0; 149 150 // Loop over all of the globals in the src module, mapping them over as we go 151 // 152 for (Module::const_giterator I = Src->gbegin(), E = Src->gend(); I != E; ++I){ 153 const GlobalVariable *SGV = *I; 154 Value *V; 155 156 // If the global variable has a name, and that name is already in use in the 157 // Dest module, make sure that the name is a compatible global variable... 158 // 159 if (SGV->hasExternalLinkage() && SGV->hasName() && 160 (V = ST->lookup(SGV->getType(), SGV->getName())) && 161 cast<GlobalVariable>(V)->hasExternalLinkage()) { 162 // The same named thing is a global variable, because the only two things 163 // that may be in a module level symbol table are Global Vars and Methods, 164 // and they both have distinct, nonoverlapping, possible types. 165 // 166 GlobalVariable *DGV = cast<GlobalVariable>(V); 167 168 // Check to see if the two GV's have the same Const'ness... 169 if (SGV->isConstant() != DGV->isConstant()) 170 return Error(Err, "Global Variable Collision on '" + 171 SGV->getType()->getDescription() + "':%" + SGV->getName() + 172 " - Global variables differ in const'ness"); 173 174 // Okay, everything is cool, remember the mapping... 175 ValueMap.insert(make_pair(SGV, DGV)); 176 } else { 177 // No linking to be performed, simply create an identical version of the 178 // symbol over in the dest module... the initializer will be filled in 179 // later by LinkGlobalInits... 180 // 181 GlobalVariable *DGV = 182 new GlobalVariable(SGV->getType()->getElementType(), SGV->isConstant(), 183 SGV->hasInternalLinkage(), 0, SGV->getName()); 184 185 // Add the new global to the dest module 186 Dest->getGlobalList().push_back(DGV); 187 188 // Make sure to remember this mapping... 189 ValueMap.insert(make_pair(SGV, DGV)); 190 } 191 } 192 return false; 193} 194 195 196// LinkGlobalInits - Update the initializers in the Dest module now that all 197// globals that may be referenced are in Dest. 198// 199static bool LinkGlobalInits(Module *Dest, const Module *Src, 200 map<const Value*, Value*> &ValueMap, 201 string *Err = 0) { 202 203 // Loop over all of the globals in the src module, mapping them over as we go 204 // 205 for (Module::const_giterator I = Src->gbegin(), E = Src->gend(); I != E; ++I){ 206 const GlobalVariable *SGV = *I; 207 208 if (SGV->hasInitializer()) { // Only process initialized GV's 209 // Figure out what the initializer looks like in the dest module... 210 Constant *DInit = 211 cast<Constant>(RemapOperand(SGV->getInitializer(), ValueMap)); 212 213 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[SGV]); 214 if (DGV->hasInitializer() && SGV->hasExternalLinkage() && 215 DGV->hasExternalLinkage()) { 216 if (DGV->getInitializer() != DInit) 217 return Error(Err, "Global Variable Collision on '" + 218 SGV->getType()->getDescription() + "':%" +SGV->getName()+ 219 " - Global variables have different initializers"); 220 } else { 221 // Copy the initializer over now... 222 DGV->setInitializer(DInit); 223 } 224 } 225 } 226 return false; 227} 228 229// LinkMethodProtos - Link the methods together between the two modules, without 230// doing method bodies... this just adds external method prototypes to the Dest 231// method... 232// 233static bool LinkMethodProtos(Module *Dest, const Module *Src, 234 map<const Value*, Value*> &ValueMap, 235 string *Err = 0) { 236 // We will need a module level symbol table if the src module has a module 237 // level symbol table... 238 SymbolTable *ST = Src->getSymbolTable() ? Dest->getSymbolTableSure() : 0; 239 240 // Loop over all of the methods in the src module, mapping them over as we go 241 // 242 for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) { 243 const Method *SM = *I; // SrcMethod 244 Value *V; 245 246 // If the method has a name, and that name is already in use in the 247 // Dest module, make sure that the name is a compatible method... 248 // 249 if (SM->hasExternalLinkage() && SM->hasName() && 250 (V = ST->lookup(SM->getType(), SM->getName())) && 251 cast<Method>(V)->hasExternalLinkage()) { 252 // The same named thing is a Method, because the only two things 253 // that may be in a module level symbol table are Global Vars and Methods, 254 // and they both have distinct, nonoverlapping, possible types. 255 // 256 Method *DM = cast<Method>(V); // DestMethod 257 258 // Check to make sure the method is not defined in both modules... 259 if (!SM->isExternal() && !DM->isExternal()) 260 return Error(Err, "Method '" + 261 SM->getMethodType()->getDescription() + "':\"" + 262 SM->getName() + "\" - Method is already defined!"); 263 264 // Otherwise, just remember this mapping... 265 ValueMap.insert(make_pair(SM, DM)); 266 } else { 267 // Method does not already exist, simply insert an external method 268 // signature identical to SM into the dest module... 269 Method *DM = new Method(SM->getMethodType(), SM->hasInternalLinkage(), 270 SM->getName()); 271 272 // Add the method signature to the dest module... 273 Dest->getMethodList().push_back(DM); 274 275 // ... and remember this mapping... 276 ValueMap.insert(make_pair(SM, DM)); 277 } 278 } 279 return false; 280} 281 282// LinkMethodBody - Copy the source method over into the dest method and fix up 283// references to values. At this point we know that Dest is an external method, 284// and that Src is not. 285// 286static bool LinkMethodBody(Method *Dest, const Method *Src, 287 const map<const Value*, Value*> &GlobalMap, 288 string *Err = 0) { 289 assert(Src && Dest && Dest->isExternal() && !Src->isExternal()); 290 map<const Value*, Value*> LocalMap; // Map for method local values 291 292 // Go through and convert method arguments over... 293 for (Method::ArgumentListType::const_iterator 294 I = Src->getArgumentList().begin(), 295 E = Src->getArgumentList().end(); I != E; ++I) { 296 const MethodArgument *SMA = *I; 297 298 // Create the new method argument and add to the dest method... 299 MethodArgument *DMA = new MethodArgument(SMA->getType(), SMA->getName()); 300 Dest->getArgumentList().push_back(DMA); 301 302 // Add a mapping to our local map 303 LocalMap.insert(make_pair(SMA, DMA)); 304 } 305 306 // Loop over all of the basic blocks, copying the instructions over... 307 // 308 for (Method::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) { 309 const BasicBlock *SBB = *I; 310 311 // Create new basic block and add to mapping and the Dest method... 312 BasicBlock *DBB = new BasicBlock(SBB->getName(), Dest); 313 LocalMap.insert(make_pair(SBB, DBB)); 314 315 // Loop over all of the instructions in the src basic block, copying them 316 // over. Note that this is broken in a strict sense because the cloned 317 // instructions will still be referencing values in the Src module, not 318 // the remapped values. In our case, however, we will not get caught and 319 // so we can delay patching the values up until later... 320 // 321 for (BasicBlock::const_iterator II = SBB->begin(), IE = SBB->end(); 322 II != IE; ++II) { 323 const Instruction *SI = *II; 324 Instruction *DI = SI->clone(); 325 DI->setName(SI->getName()); 326 DBB->getInstList().push_back(DI); 327 LocalMap.insert(make_pair(SI, DI)); 328 } 329 } 330 331 // At this point, all of the instructions and values of the method are now 332 // copied over. The only problem is that they are still referencing values 333 // in the Source method as operands. Loop through all of the operands of the 334 // methods and patch them up to point to the local versions... 335 // 336 for (Method::inst_iterator I = Dest->inst_begin(), E = Dest->inst_end(); 337 I != E; ++I) { 338 Instruction *Inst = *I; 339 340 for (Instruction::op_iterator OI = Inst->op_begin(), OE = Inst->op_end(); 341 OI != OE; ++OI) 342 *OI = RemapOperand(*OI, LocalMap, &GlobalMap); 343 } 344 345 return false; 346} 347 348 349// LinkMethodBodies - Link in the method bodies that are defined in the source 350// module into the DestModule. This consists basically of copying the method 351// over and fixing up references to values. 352// 353static bool LinkMethodBodies(Module *Dest, const Module *Src, 354 map<const Value*, Value*> &ValueMap, 355 string *Err = 0) { 356 357 // Loop over all of the methods in the src module, mapping them over as we go 358 // 359 for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) { 360 const Method *SM = *I; // Source Method 361 if (!SM->isExternal()) { // No body if method is external 362 Method *DM = cast<Method>(ValueMap[SM]); // Destination method 363 364 // DM not external SM external? 365 if (!DM->isExternal()) { 366 if (Err) 367 *Err = "Method '" + (SM->hasName() ? SM->getName() : string("")) + 368 "' body multiply defined!"; 369 return true; 370 } 371 372 if (LinkMethodBody(DM, SM, ValueMap, Err)) return true; 373 } 374 } 375 return false; 376} 377 378 379 380// LinkModules - This function links two modules together, with the resulting 381// left module modified to be the composite of the two input modules. If an 382// error occurs, true is returned and ErrorMsg (if not null) is set to indicate 383// the problem. Upon failure, the Dest module could be in a modified state, and 384// shouldn't be relied on to be consistent. 385// 386bool LinkModules(Module *Dest, const Module *Src, string *ErrorMsg = 0) { 387 388 // LinkTypes - Go through the symbol table of the Src module and see if any 389 // types are named in the src module that are not named in the Dst module. 390 // Make sure there are no type name conflicts. 391 // 392 if (LinkTypes(Dest, Src, ErrorMsg)) return true; 393 394 // ValueMap - Mapping of values from what they used to be in Src, to what they 395 // are now in Dest. 396 // 397 map<const Value*, Value*> ValueMap; 398 399 // Insert all of the globals in src into the Dest module... without 400 // initializers 401 if (LinkGlobals(Dest, Src, ValueMap, ErrorMsg)) return true; 402 403 // Update the initializers in the Dest module now that all globals that may 404 // be referenced are in Dest. 405 // 406 if (LinkGlobalInits(Dest, Src, ValueMap, ErrorMsg)) return true; 407 408 // Link the methods together between the two modules, without doing method 409 // bodies... this just adds external method prototypes to the Dest method... 410 // We do this so that when we begin processing method bodies, all of the 411 // global values that may be referenced are available in our ValueMap. 412 // 413 if (LinkMethodProtos(Dest, Src, ValueMap, ErrorMsg)) return true; 414 415 // Link in the method bodies that are defined in the source module into the 416 // DestModule. This consists basically of copying the method over and fixing 417 // up references to values. 418 // 419 if (LinkMethodBodies(Dest, Src, ValueMap, ErrorMsg)) return true; 420 421 return false; 422} 423 424