LinkModules.cpp revision c18545dc9e5c8d98ea9089af8702a6cf563a8dfd
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 20// Error - Simple wrapper function to conditionally assign to E and return true. 21// This just makes error return conditions a little bit simpler... 22// 23static inline bool Error(string *E, string Message) { 24 if (E) *E = Message; 25 return true; 26} 27 28#include "llvm/Assembly/Writer.h" // TODO: REMOVE 29 30// RemapOperand - Use LocalMap and GlobalMap to convert references from one 31// module to another. This is somewhat sophisticated in that it can 32// automatically handle constant references correctly as well... 33// 34static Value *RemapOperand(const Value *In, map<const Value*, Value*> &LocalMap, 35 const map<const Value*, Value*> *GlobalMap = 0) { 36 map<const Value*,Value*>::const_iterator I = LocalMap.find(In); 37 if (I != LocalMap.end()) return I->second; 38 39 if (GlobalMap) { 40 I = GlobalMap->find(In); 41 if (I != GlobalMap->end()) return I->second; 42 } 43 44 // Check to see if it's a constant that we are interesting in transforming... 45 if (ConstPoolVal *CPV = dyn_cast<ConstPoolVal>(In)) { 46 if (!isa<DerivedType>(CPV->getType())) 47 return CPV; // Simple constants stay identical... 48 49 ConstPoolVal *Result = 0; 50 51 if (ConstPoolArray *CPA = dyn_cast<ConstPoolArray>(CPV)) { 52 const vector<Use> &Ops = CPA->getValues(); 53 vector<ConstPoolVal*> Operands(Ops.size()); 54 for (unsigned i = 0; i < Ops.size(); ++i) 55 Operands[i] = 56 cast<ConstPoolVal>(RemapOperand(Ops[i], LocalMap, GlobalMap)); 57 Result = ConstPoolArray::get(cast<ArrayType>(CPA->getType()), Operands); 58 } else if (ConstPoolStruct *CPS = dyn_cast<ConstPoolStruct>(CPV)) { 59 const vector<Use> &Ops = CPS->getValues(); 60 vector<ConstPoolVal*> Operands(Ops.size()); 61 for (unsigned i = 0; i < Ops.size(); ++i) 62 Operands[i] = 63 cast<ConstPoolVal>(RemapOperand(Ops[i], LocalMap, GlobalMap)); 64 Result = ConstPoolStruct::get(cast<StructType>(CPS->getType()), Operands); 65 } else if (isa<ConstPoolPointerNull>(CPV)) { 66 Result = CPV; 67 } else if (ConstPoolPointerRef *CPR = dyn_cast<ConstPoolPointerRef>(CPV)) { 68 Value *V = RemapOperand(CPR->getValue(), LocalMap, GlobalMap); 69 Result = ConstPoolPointerRef::get(cast<GlobalValue>(V)); 70 } else { 71 assert(0 && "Unknown type of derived type constant value!"); 72 } 73 74 // Cache the mapping in our local map structure... 75 LocalMap.insert(make_pair(In, CPV)); 76 return Result; 77 } 78 79 cerr << "Couldn't remap value: " << In << endl; 80 assert(0 && "Couldn't remap value!"); 81 return 0; 82} 83 84 85// LinkGlobals - Loop through the global variables in the src module and merge 86// them into the dest module... 87// 88static bool LinkGlobals(Module *Dest, const Module *Src, 89 map<const Value*, Value*> &ValueMap, string *Err = 0) { 90 // We will need a module level symbol table if the src module has a module 91 // level symbol table... 92 SymbolTable *ST = Src->getSymbolTable() ? Dest->getSymbolTableSure() : 0; 93 94 // Loop over all of the globals in the src module, mapping them over as we go 95 // 96 for (Module::const_giterator I = Src->gbegin(), E = Src->gend(); I != E; ++I){ 97 const GlobalVariable *SGV = *I; 98 Value *V; 99 100 // If the global variable has a name, and that name is already in use in the 101 // Dest module, make sure that the name is a compatible global variable... 102 // 103 if (SGV->hasName() && (V = ST->lookup(SGV->getType(), SGV->getName()))) { 104 // The same named thing is a global variable, because the only two things 105 // that may be in a module level symbol table are Global Vars and Methods, 106 // and they both have distinct, nonoverlapping, possible types. 107 // 108 GlobalVariable *DGV = cast<GlobalVariable>(V); 109 110 // Check to see if the two GV's have the same Const'ness... 111 if (SGV->isConstant() != DGV->isConstant()) 112 return Error(Err, "Global Variable Collision on '" + 113 SGV->getType()->getDescription() + "':%" + SGV->getName() + 114 " - Global variables differ in const'ness"); 115 116 // Okay, everything is cool, remember the mapping... 117 ValueMap.insert(make_pair(SGV, DGV)); 118 } else { 119 // No linking to be performed, simply create an identical version of the 120 // symbol over in the dest module... the initializer will be filled in 121 // later by LinkGlobalInits... 122 // 123 GlobalVariable *DGV = 124 new GlobalVariable(SGV->getType()->getValueType(), SGV->isConstant(), 125 0, SGV->getName()); 126 127 // Add the new global to the dest module 128 Dest->getGlobalList().push_back(DGV); 129 130 // Make sure to remember this mapping... 131 ValueMap.insert(make_pair(SGV, DGV)); 132 } 133 } 134 return false; 135} 136 137 138// LinkGlobalInits - Update the initializers in the Dest module now that all 139// globals that may be referenced are in Dest. 140// 141static bool LinkGlobalInits(Module *Dest, const Module *Src, 142 map<const Value*, Value*> &ValueMap, 143 string *Err = 0) { 144 145 // Loop over all of the globals in the src module, mapping them over as we go 146 // 147 for (Module::const_giterator I = Src->gbegin(), E = Src->gend(); I != E; ++I){ 148 const GlobalVariable *SGV = *I; 149 150 if (SGV->hasInitializer()) { // Only process initialized GV's 151 // Figure out what the initializer looks like in the dest module... 152 ConstPoolVal *DInit = 153 cast<ConstPoolVal>(RemapOperand(SGV->getInitializer(), ValueMap)); 154 155 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[SGV]); 156 if (DGV->hasInitializer()) { 157 if (DGV->getInitializer() != DInit) 158 return Error(Err, "Global Variable Collision on '" + 159 SGV->getType()->getDescription() + "':%" +SGV->getName()+ 160 " - Global variables have different initializers"); 161 } else { 162 // Copy the initializer over now... 163 DGV->setInitializer(DInit); 164 } 165 } 166 } 167 return false; 168} 169 170// LinkMethodProtos - Link the methods together between the two modules, without 171// doing method bodies... this just adds external method prototypes to the Dest 172// method... 173// 174static bool LinkMethodProtos(Module *Dest, const Module *Src, 175 map<const Value*, Value*> &ValueMap, 176 string *Err = 0) { 177 // We will need a module level symbol table if the src module has a module 178 // level symbol table... 179 SymbolTable *ST = Src->getSymbolTable() ? Dest->getSymbolTableSure() : 0; 180 181 // Loop over all of the methods in the src module, mapping them over as we go 182 // 183 for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) { 184 const Method *SM = *I; // SrcMethod 185 Value *V; 186 187 // If the method has a name, and that name is already in use in the 188 // Dest module, make sure that the name is a compatible method... 189 // 190 if (SM->hasName() && (V = ST->lookup(SM->getType(), SM->getName()))) { 191 // The same named thing is a Method, because the only two things 192 // that may be in a module level symbol table are Global Vars and Methods, 193 // and they both have distinct, nonoverlapping, possible types. 194 // 195 Method *DM = cast<Method>(V); // DestMethod 196 197 // Check to make sure the method is not defined in both modules... 198 if (!SM->isExternal() && !DM->isExternal()) 199 return Error(Err, "Method '" + 200 SM->getMethodType()->getDescription() + "':\"" + 201 SM->getName() + "\" - Method is already defined!"); 202 203 // Otherwise, just remember this mapping... 204 ValueMap.insert(make_pair(SM, DM)); 205 } else { 206 // Method does not already exist, simply insert an external method 207 // signature identical to SM into the dest module... 208 Method *DM = new Method(SM->getMethodType(), SM->getName()); 209 210 // Add the method signature to the dest module... 211 Dest->getMethodList().push_back(DM); 212 213 // ... and remember this mapping... 214 ValueMap.insert(make_pair(SM, DM)); 215 } 216 } 217 return false; 218} 219 220// LinkMethodBody - Copy the source method over into the dest method and fix up 221// references to values. At this point we know that Dest is an external method, 222// and that Src is not. 223// 224static bool LinkMethodBody(Method *Dest, const Method *Src, 225 const map<const Value*, Value*> &GlobalMap, 226 string *Err = 0) { 227 assert(Src && Dest && Dest->isExternal() && !Src->isExternal()); 228 map<const Value*, Value*> LocalMap; // Map for method local values 229 230 // Go through and convert method arguments over... 231 for (Method::ArgumentListType::const_iterator 232 I = Src->getArgumentList().begin(), 233 E = Src->getArgumentList().end(); I != E; ++I) { 234 const MethodArgument *SMA = *I; 235 236 // Create the new method argument and add to the dest method... 237 MethodArgument *DMA = new MethodArgument(SMA->getType(), SMA->getName()); 238 Dest->getArgumentList().push_back(DMA); 239 240 // Add a mapping to our local map 241 LocalMap.insert(make_pair(SMA, DMA)); 242 } 243 244 // Loop over all of the basic blocks, copying the instructions over... 245 // 246 for (Method::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) { 247 const BasicBlock *SBB = *I; 248 249 // Create new basic block and add to mapping and the Dest method... 250 BasicBlock *DBB = new BasicBlock(SBB->getName(), Dest); 251 LocalMap.insert(make_pair(SBB, DBB)); 252 253 // Loop over all of the instructions in the src basic block, copying them 254 // over. Note that this is broken in a strict sense because the cloned 255 // instructions will still be referencing values in the Src module, not 256 // the remapped values. In our case, however, we will not get caught and 257 // so we can delay patching the values up until later... 258 // 259 for (BasicBlock::const_iterator II = SBB->begin(), IE = SBB->end(); 260 II != IE; ++II) { 261 const Instruction *SI = *II; 262 Instruction *DI = SI->clone(); 263 DBB->getInstList().push_back(DI); 264 LocalMap.insert(make_pair(SI, DI)); 265 } 266 } 267 268 // At this point, all of the instructions and values of the method are now 269 // copied over. The only problem is that they are still referencing values 270 // in the Source method as operands. Loop through all of the operands of the 271 // methods and patch them up to point to the local versions... 272 // 273 for (Method::inst_iterator I = Dest->inst_begin(), E = Dest->inst_end(); 274 I != E; ++I) { 275 Instruction *Inst = *I; 276 277 for (Instruction::op_iterator OI = Inst->op_begin(), OE = Inst->op_end(); 278 OI != OE; ++OI) 279 *OI = RemapOperand(*OI, LocalMap, &GlobalMap); 280 } 281 282 return false; 283} 284 285 286// LinkMethodBodies - Link in the method bodies that are defined in the source 287// module into the DestModule. This consists basically of copying the method 288// over and fixing up references to values. 289// 290static bool LinkMethodBodies(Module *Dest, const Module *Src, 291 map<const Value*, Value*> &ValueMap, 292 string *Err = 0) { 293 294 // Loop over all of the methods in the src module, mapping them over as we go 295 // 296 for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) { 297 const Method *SM = *I; // Source Method 298 Method *DM = cast<Method>(ValueMap[SM]); // Destination method 299 300 assert(DM && DM->isExternal() && "LinkMethodProtos failed!"); 301 if (!SM->isExternal()) // External methods are already done 302 if (LinkMethodBody(DM, SM, ValueMap, Err)) return true; 303 } 304 return false; 305} 306 307 308 309// LinkModules - This function links two modules together, with the resulting 310// left module modified to be the composite of the two input modules. If an 311// error occurs, true is returned and ErrorMsg (if not null) is set to indicate 312// the problem. Upon failure, the Dest module could be in a modified state, and 313// shouldn't be relied on to be consistent. 314// 315bool LinkModules(Module *Dest, const Module *Src, string *ErrorMsg = 0) { 316 // ValueMap - Mapping of values from what they used to be in Src, to what they 317 // are now in Dest. 318 // 319 map<const Value*, Value*> ValueMap; 320 321 // Insert all of the globals in src into the Dest module... without 322 // initializers 323 if (LinkGlobals(Dest, Src, ValueMap, ErrorMsg)) return true; 324 325 // Update the initializers in the Dest module now that all globals that may 326 // be referenced are in Dest. 327 // 328 if (LinkGlobalInits(Dest, Src, ValueMap, ErrorMsg)) return true; 329 330 // Link the methods together between the two modules, without doing method 331 // bodies... this just adds external method prototypes to the Dest method... 332 // We do this so that when we begin processing method bodies, all of the 333 // global values that may be referenced are available in our ValueMap. 334 // 335 if (LinkMethodProtos(Dest, Src, ValueMap, ErrorMsg)) return true; 336 337 // Link in the method bodies that are defined in the source module into the 338 // DestModule. This consists basically of copying the method over and fixing 339 // up references to values. 340 // 341 if (LinkMethodBodies(Dest, Src, ValueMap, ErrorMsg)) return true; 342 343 return false; 344} 345