//===- Linker.cpp - Module Linker Implementation --------------------------===// // // This file implements the LLVM module linker. // // Specifically, this: // * Merges global variables between the two modules // * Uninit + Uninit = Init, Init + Uninit = Init, Init + Init = Error if != // * Merges functions between two modules // //===----------------------------------------------------------------------===// #include "llvm/Transforms/Utils/Linker.h" #include "llvm/Module.h" #include "llvm/Function.h" #include "llvm/BasicBlock.h" #include "llvm/GlobalVariable.h" #include "llvm/SymbolTable.h" #include "llvm/DerivedTypes.h" #include "llvm/iOther.h" #include "llvm/Constants.h" #include "llvm/Argument.h" #include using std::cerr; using std::string; using std::map; // Error - Simple wrapper function to conditionally assign to E and return true. // This just makes error return conditions a little bit simpler... // static inline bool Error(string *E, string Message) { if (E) *E = Message; return true; } // LinkTypes - Go through the symbol table of the Src module and see if any // types are named in the src module that are not named in the Dst module. // Make sure there are no type name conflicts. // static bool LinkTypes(Module *Dest, const Module *Src, string *Err = 0) { // No symbol table? Can't have named types. if (!Src->hasSymbolTable()) return false; SymbolTable *DestST = Dest->getSymbolTableSure(); const SymbolTable *SrcST = Src->getSymbolTable(); // Look for a type plane for Type's... SymbolTable::const_iterator PI = SrcST->find(Type::TypeTy); if (PI == SrcST->end()) return false; // No named types, do nothing. const SymbolTable::VarMap &VM = PI->second; for (SymbolTable::type_const_iterator I = VM.begin(), E = VM.end(); I != E; ++I) { const string &Name = I->first; const Type *RHS = cast(I->second); // Check to see if this type name is already in the dest module... const Type *Entry = cast_or_null(DestST->lookup(Type::TypeTy, Name)); if (Entry) { // Yup, the value already exists... if (Entry != RHS) // If it's the same, noop. Otherwise, error. return Error(Err, "Type named '" + Name + "' of different shape in modules.\n Src='" + Entry->getDescription() + "'.\n Dst='" + RHS->getDescription() + "'"); } else { // Type not in dest module. Add it now. // TODO: FIXME WHEN TYPES AREN'T CONST DestST->insert(Name, const_cast(RHS)); } } return false; } static void PrintMap(const map &M) { for (map::const_iterator I = M.begin(), E = M.end(); I != E; ++I) { cerr << " Fr: " << (void*)I->first << " "; I->first->dump(); cerr << " To: " << (void*)I->second << " "; I->second->dump(); cerr << "\n"; } } // RemapOperand - Use LocalMap and GlobalMap to convert references from one // module to another. This is somewhat sophisticated in that it can // automatically handle constant references correctly as well... // static Value *RemapOperand(const Value *In, map &LocalMap, const map *GlobalMap = 0) { map::const_iterator I = LocalMap.find(In); if (I != LocalMap.end()) return I->second; if (GlobalMap) { I = GlobalMap->find(In); if (I != GlobalMap->end()) return I->second; } // Check to see if it's a constant that we are interesting in transforming... if (const Constant *CPV = dyn_cast(In)) { if (!isa(CPV->getType())) return const_cast(CPV); // Simple constants stay identical... Constant *Result = 0; if (const ConstantArray *CPA = dyn_cast(CPV)) { const std::vector &Ops = CPA->getValues(); std::vector Operands(Ops.size()); for (unsigned i = 0; i < Ops.size(); ++i) Operands[i] = cast(RemapOperand(Ops[i], LocalMap, GlobalMap)); Result = ConstantArray::get(cast(CPA->getType()), Operands); } else if (const ConstantStruct *CPS = dyn_cast(CPV)) { const std::vector &Ops = CPS->getValues(); std::vector Operands(Ops.size()); for (unsigned i = 0; i < Ops.size(); ++i) Operands[i] = cast(RemapOperand(Ops[i], LocalMap, GlobalMap)); Result = ConstantStruct::get(cast(CPS->getType()), Operands); } else if (isa(CPV)) { Result = const_cast(CPV); } else if (const ConstantPointerRef *CPR = dyn_cast(CPV)) { Value *V = RemapOperand(CPR->getValue(), LocalMap, GlobalMap); Result = ConstantPointerRef::get(cast(V)); } else { assert(0 && "Unknown type of derived type constant value!"); } // Cache the mapping in our local map structure... LocalMap.insert(std::make_pair(In, const_cast(CPV))); return Result; } cerr << "XXX LocalMap: \n"; PrintMap(LocalMap); if (GlobalMap) { cerr << "XXX GlobalMap: \n"; PrintMap(*GlobalMap); } cerr << "Couldn't remap value: " << (void*)In << " "; In->dump(); cerr << "\n"; assert(0 && "Couldn't remap value!"); return 0; } // LinkGlobals - Loop through the global variables in the src module and merge // them into the dest module... // static bool LinkGlobals(Module *Dest, const Module *Src, map &ValueMap, string *Err = 0) { // We will need a module level symbol table if the src module has a module // level symbol table... SymbolTable *ST = Src->getSymbolTable() ? Dest->getSymbolTableSure() : 0; // Loop over all of the globals in the src module, mapping them over as we go // for (Module::const_giterator I = Src->gbegin(), E = Src->gend(); I != E; ++I){ const GlobalVariable *SGV = I; Value *V; // If the global variable has a name, and that name is already in use in the // Dest module, make sure that the name is a compatible global variable... // if (SGV->hasExternalLinkage() && SGV->hasName() && (V = ST->lookup(SGV->getType(), SGV->getName())) && cast(V)->hasExternalLinkage()) { // The same named thing is a global variable, because the only two things // that may be in a module level symbol table are Global Vars and // Functions, and they both have distinct, nonoverlapping, possible types. // GlobalVariable *DGV = cast(V); // Check to see if the two GV's have the same Const'ness... if (SGV->isConstant() != DGV->isConstant()) return Error(Err, "Global Variable Collision on '" + SGV->getType()->getDescription() + "':%" + SGV->getName() + " - Global variables differ in const'ness"); // Okay, everything is cool, remember the mapping... ValueMap.insert(std::make_pair(SGV, DGV)); } else { // No linking to be performed, simply create an identical version of the // symbol over in the dest module... the initializer will be filled in // later by LinkGlobalInits... // GlobalVariable *DGV = new GlobalVariable(SGV->getType()->getElementType(), SGV->isConstant(), SGV->hasInternalLinkage(), 0, SGV->getName()); // Add the new global to the dest module Dest->getGlobalList().push_back(DGV); // Make sure to remember this mapping... ValueMap.insert(std::make_pair(SGV, DGV)); } } return false; } // LinkGlobalInits - Update the initializers in the Dest module now that all // globals that may be referenced are in Dest. // static bool LinkGlobalInits(Module *Dest, const Module *Src, map &ValueMap, string *Err = 0) { // Loop over all of the globals in the src module, mapping them over as we go // for (Module::const_giterator I = Src->gbegin(), E = Src->gend(); I != E; ++I){ const GlobalVariable *SGV = I; if (SGV->hasInitializer()) { // Only process initialized GV's // Figure out what the initializer looks like in the dest module... Constant *DInit = cast(RemapOperand(SGV->getInitializer(), ValueMap)); GlobalVariable *DGV = cast(ValueMap[SGV]); if (DGV->hasInitializer() && SGV->hasExternalLinkage() && DGV->hasExternalLinkage()) { if (DGV->getInitializer() != DInit) return Error(Err, "Global Variable Collision on '" + SGV->getType()->getDescription() + "':%" +SGV->getName()+ " - Global variables have different initializers"); } else { // Copy the initializer over now... DGV->setInitializer(DInit); } } } return false; } // LinkFunctionProtos - Link the functions together between the two modules, // without doing function bodies... this just adds external function prototypes // to the Dest function... // static bool LinkFunctionProtos(Module *Dest, const Module *Src, map &ValueMap, string *Err = 0) { // We will need a module level symbol table if the src module has a module // level symbol table... SymbolTable *ST = Src->getSymbolTable() ? Dest->getSymbolTableSure() : 0; // Loop over all of the functions in the src module, mapping them over as we // go // for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) { const Function *SF = I; // SrcFunction Value *V; // If the function has a name, and that name is already in use in the Dest // module, make sure that the name is a compatible function... // if (SF->hasExternalLinkage() && SF->hasName() && (V = ST->lookup(SF->getType(), SF->getName())) && cast(V)->hasExternalLinkage()) { // The same named thing is a Function, because the only two things // that may be in a module level symbol table are Global Vars and // Functions, and they both have distinct, nonoverlapping, possible types. // Function *DF = cast(V); // DestFunction // Check to make sure the function is not defined in both modules... if (!SF->isExternal() && !DF->isExternal()) return Error(Err, "Function '" + SF->getFunctionType()->getDescription() + "':\"" + SF->getName() + "\" - Function is already defined!"); // Otherwise, just remember this mapping... ValueMap.insert(std::make_pair(SF, DF)); } else { // Function does not already exist, simply insert an external function // signature identical to SF into the dest module... Function *DF = new Function(SF->getFunctionType(), SF->hasInternalLinkage(), SF->getName()); // Add the function signature to the dest module... Dest->getFunctionList().push_back(DF); // ... and remember this mapping... ValueMap.insert(std::make_pair(SF, DF)); } } return false; } // LinkFunctionBody - Copy the source function over into the dest function and // fix up references to values. At this point we know that Dest is an external // function, and that Src is not. // static bool LinkFunctionBody(Function *Dest, const Function *Src, const map &GlobalMap, string *Err = 0) { assert(Src && Dest && Dest->isExternal() && !Src->isExternal()); map LocalMap; // Map for function local values // Go through and convert function arguments over... for (Function::const_aiterator I = Src->abegin(), E = Src->aend(); I != E; ++I) { // Create the new function argument and add to the dest function... Argument *DFA = new Argument(I->getType(), I->getName()); Dest->getArgumentList().push_back(DFA); // Add a mapping to our local map LocalMap.insert(std::make_pair(I, DFA)); } // Loop over all of the basic blocks, copying the instructions over... // for (Function::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) { // Create new basic block and add to mapping and the Dest function... BasicBlock *DBB = new BasicBlock(I->getName(), Dest); LocalMap.insert(std::make_pair(I, DBB)); // Loop over all of the instructions in the src basic block, copying them // over. Note that this is broken in a strict sense because the cloned // instructions will still be referencing values in the Src module, not // the remapped values. In our case, however, we will not get caught and // so we can delay patching the values up until later... // for (BasicBlock::const_iterator II = I->begin(), IE = I->end(); II != IE; ++II) { Instruction *DI = II->clone(); DI->setName(II->getName()); DBB->getInstList().push_back(DI); LocalMap.insert(std::make_pair(II, DI)); } } // At this point, all of the instructions and values of the function are now // copied over. The only problem is that they are still referencing values in // the Source function as operands. Loop through all of the operands of the // functions and patch them up to point to the local versions... // for (Function::iterator BB = Dest->begin(), BE = Dest->end(); BB != BE; ++BB) for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end(); OI != OE; ++OI) *OI = RemapOperand(*OI, LocalMap, &GlobalMap); return false; } // LinkFunctionBodies - Link in the function bodies that are defined in the // source module into the DestModule. This consists basically of copying the // function over and fixing up references to values. // static bool LinkFunctionBodies(Module *Dest, const Module *Src, map &ValueMap, string *Err = 0) { // Loop over all of the functions in the src module, mapping them over as we // go // for (Module::const_iterator SF = Src->begin(), E = Src->end(); SF != E; ++SF){ if (!SF->isExternal()) { // No body if function is external Function *DF = cast(ValueMap[SF]); // Destination function // DF not external SF external? if (!DF->isExternal()) { if (Err) *Err = "Function '" + (SF->hasName() ? SF->getName() : string("")) + "' body multiply defined!"; return true; } if (LinkFunctionBody(DF, SF, ValueMap, Err)) return true; } } return false; } // LinkModules - This function links two modules together, with the resulting // left module modified to be the composite of the two input modules. If an // error occurs, true is returned and ErrorMsg (if not null) is set to indicate // the problem. Upon failure, the Dest module could be in a modified state, and // shouldn't be relied on to be consistent. // bool LinkModules(Module *Dest, const Module *Src, string *ErrorMsg = 0) { // LinkTypes - Go through the symbol table of the Src module and see if any // types are named in the src module that are not named in the Dst module. // Make sure there are no type name conflicts. // if (LinkTypes(Dest, Src, ErrorMsg)) return true; // ValueMap - Mapping of values from what they used to be in Src, to what they // are now in Dest. // map ValueMap; // Insert all of the globals in src into the Dest module... without // initializers if (LinkGlobals(Dest, Src, ValueMap, ErrorMsg)) return true; // Update the initializers in the Dest module now that all globals that may // be referenced are in Dest. // if (LinkGlobalInits(Dest, Src, ValueMap, ErrorMsg)) return true; // Link the functions together between the two modules, without doing function // bodies... this just adds external function prototypes to the Dest // function... We do this so that when we begin processing function bodies, // all of the global values that may be referenced are available in our // ValueMap. // if (LinkFunctionProtos(Dest, Src, ValueMap, ErrorMsg)) return true; // Link in the function bodies that are defined in the source module into the // DestModule. This consists basically of copying the function over and // fixing up references to values. // if (LinkFunctionBodies(Dest, Src, ValueMap, ErrorMsg)) return true; return false; }