//===- 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 methods between two modules // //===----------------------------------------------------------------------===// #include "llvm/Transforms/Linker.h" #include "llvm/Module.h" #include "llvm/Method.h" #include "llvm/GlobalVariable.h" #include "llvm/SymbolTable.h" #include "llvm/DerivedTypes.h" #include "llvm/iOther.h" // 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; } #include "llvm/Assembly/Writer.h" // TODO: REMOVE // 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 (ConstPoolVal *CPV = dyn_cast(In)) { if (!isa(CPV->getType())) return CPV; // Simple constants stay identical... ConstPoolVal *Result = 0; if (ConstPoolArray *CPA = dyn_cast(CPV)) { const vector &Ops = CPA->getValues(); vector Operands(Ops.size()); for (unsigned i = 0; i < Ops.size(); ++i) Operands[i] = cast(RemapOperand(Ops[i], LocalMap, GlobalMap)); Result = ConstPoolArray::get(cast(CPA->getType()), Operands); } else if (ConstPoolStruct *CPS = dyn_cast(CPV)) { const vector &Ops = CPS->getValues(); vector Operands(Ops.size()); for (unsigned i = 0; i < Ops.size(); ++i) Operands[i] = cast(RemapOperand(Ops[i], LocalMap, GlobalMap)); Result = ConstPoolStruct::get(cast(CPS->getType()), Operands); } else if (isa(CPV)) { Result = CPV; } else if (ConstPoolPointerRef *CPR = dyn_cast(CPV)) { Value *V = RemapOperand(CPR->getValue(), LocalMap, GlobalMap); Result = ConstPoolPointerRef::get(cast(V)); } else { assert(0 && "Unknown type of derived type constant value!"); } // Cache the mapping in our local map structure... LocalMap.insert(make_pair(In, CPV)); return Result; } cerr << "Couldn't remap value: " << In << endl; 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->hasName() && (V = ST->lookup(SGV->getType(), SGV->getName()))) { // 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 Methods, // 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(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()->getValueType(), SGV->isConstant(), 0, SGV->getName()); // Add the new global to the dest module Dest->getGlobalList().push_back(DGV); // Make sure to remember this mapping... ValueMap.insert(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... ConstPoolVal *DInit = cast(RemapOperand(SGV->getInitializer(), ValueMap)); GlobalVariable *DGV = cast(ValueMap[SGV]); if (DGV->hasInitializer()) { 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; } // LinkMethodProtos - Link the methods together between the two modules, without // doing method bodies... this just adds external method prototypes to the Dest // method... // static bool LinkMethodProtos(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 methods in the src module, mapping them over as we go // for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) { const Method *SM = *I; // SrcMethod Value *V; // If the method has a name, and that name is already in use in the // Dest module, make sure that the name is a compatible method... // if (SM->hasName() && (V = ST->lookup(SM->getType(), SM->getName()))) { // The same named thing is a Method, because the only two things // that may be in a module level symbol table are Global Vars and Methods, // and they both have distinct, nonoverlapping, possible types. // Method *DM = cast(V); // DestMethod // Check to make sure the method is not defined in both modules... if (!SM->isExternal() && !DM->isExternal()) return Error(Err, "Method '" + SM->getMethodType()->getDescription() + "':\"" + SM->getName() + "\" - Method is already defined!"); // Otherwise, just remember this mapping... ValueMap.insert(make_pair(SM, DM)); } else { // Method does not already exist, simply insert an external method // signature identical to SM into the dest module... Method *DM = new Method(SM->getMethodType(), SM->getName()); // Add the method signature to the dest module... Dest->getMethodList().push_back(DM); // ... and remember this mapping... ValueMap.insert(make_pair(SM, DM)); } } return false; } // LinkMethodBody - Copy the source method over into the dest method and fix up // references to values. At this point we know that Dest is an external method, // and that Src is not. // static bool LinkMethodBody(Method *Dest, const Method *Src, const map &GlobalMap, string *Err = 0) { assert(Src && Dest && Dest->isExternal() && !Src->isExternal()); map LocalMap; // Map for method local values // Go through and convert method arguments over... for (Method::ArgumentListType::const_iterator I = Src->getArgumentList().begin(), E = Src->getArgumentList().end(); I != E; ++I) { const MethodArgument *SMA = *I; // Create the new method argument and add to the dest method... MethodArgument *DMA = new MethodArgument(SMA->getType(), SMA->getName()); Dest->getArgumentList().push_back(DMA); // Add a mapping to our local map LocalMap.insert(make_pair(SMA, DMA)); } // Loop over all of the basic blocks, copying the instructions over... // for (Method::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) { const BasicBlock *SBB = *I; // Create new basic block and add to mapping and the Dest method... BasicBlock *DBB = new BasicBlock(SBB->getName(), Dest); LocalMap.insert(make_pair(SBB, 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 = SBB->begin(), IE = SBB->end(); II != IE; ++II) { const Instruction *SI = *II; Instruction *DI = SI->clone(); DBB->getInstList().push_back(DI); LocalMap.insert(make_pair(SI, DI)); } } // At this point, all of the instructions and values of the method are now // copied over. The only problem is that they are still referencing values // in the Source method as operands. Loop through all of the operands of the // methods and patch them up to point to the local versions... // for (Method::inst_iterator I = Dest->inst_begin(), E = Dest->inst_end(); I != E; ++I) { Instruction *Inst = *I; for (Instruction::op_iterator OI = Inst->op_begin(), OE = Inst->op_end(); OI != OE; ++OI) *OI = RemapOperand(*OI, LocalMap, &GlobalMap); } return false; } // LinkMethodBodies - Link in the method bodies that are defined in the source // module into the DestModule. This consists basically of copying the method // over and fixing up references to values. // static bool LinkMethodBodies(Module *Dest, const Module *Src, map &ValueMap, string *Err = 0) { // Loop over all of the methods in the src module, mapping them over as we go // for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) { const Method *SM = *I; // Source Method if (!SM->isExternal()) { // No body if method is external Method *DM = cast(ValueMap[SM]); // Destination method // DM not external SM external? if (!DM->isExternal()) { if (Err) *Err = "Method '" + (SM->hasName() ? SM->getName() : string("")) + "' body multiply defined!"; return true; } if (LinkMethodBody(DM, SM, 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) { // 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 methods together between the two modules, without doing method // bodies... this just adds external method prototypes to the Dest method... // We do this so that when we begin processing method bodies, all of the // global values that may be referenced are available in our ValueMap. // if (LinkMethodProtos(Dest, Src, ValueMap, ErrorMsg)) return true; // Link in the method bodies that are defined in the source module into the // DestModule. This consists basically of copying the method over and fixing // up references to values. // if (LinkMethodBodies(Dest, Src, ValueMap, ErrorMsg)) return true; return false; }