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 functions between two modules
10 //===----------------------------------------------------------------------===//
12 #include "llvm/Transforms/Utils/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 (const Constant *CPV = dyn_cast<Constant>(In)) {
100 if (!isa<DerivedType>(CPV->getType()) && !isa<ConstantExpr>(CPV))
101 return const_cast<Constant*>(CPV); // Simple constants stay identical...
103 Constant *Result = 0;
105 if (const 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 (const 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)) {
120 Result = const_cast<Constant*>(CPV);
121 } else if (const ConstantPointerRef *CPR =
122 dyn_cast<ConstantPointerRef>(CPV)) {
123 Value *V = RemapOperand(CPR->getValue(), LocalMap, GlobalMap);
124 Result = ConstantPointerRef::get(cast<GlobalValue>(V));
125 } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CPV)) {
126 if (CE->getNumOperands() == 1) {
127 // Cast instruction, unary operator
128 Value *V = RemapOperand(CE->getOperand(0), LocalMap, GlobalMap);
129 Result = ConstantExpr::get(CE->getOpcode(), cast<Constant>(V),
131 } else if (CE->getNumOperands() == 2) {
132 // Binary operator...
133 Value *V1 = RemapOperand(CE->getOperand(0), LocalMap, GlobalMap);
134 Value *V2 = RemapOperand(CE->getOperand(1), LocalMap, GlobalMap);
136 Result = ConstantExpr::get(CE->getOpcode(), cast<Constant>(V1),
137 cast<Constant>(V2), CE->getType());
139 // GetElementPtr Expression
140 assert(CE->getOpcode() == Instruction::GetElementPtr);
141 Value *Ptr = RemapOperand(CE->getOperand(0), LocalMap, GlobalMap);
142 std::vector<Constant*> Indices;
143 Indices.reserve(CE->getNumOperands()-1);
144 for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
145 Indices.push_back(cast<Constant>(RemapOperand(CE->getOperand(i),
146 LocalMap, GlobalMap)));
148 Result = ConstantExpr::get(CE->getOpcode(), cast<Constant>(Ptr),
149 Indices, CE->getType());
153 assert(0 && "Unknown type of derived type constant value!");
156 // Cache the mapping in our local map structure...
157 LocalMap.insert(std::make_pair(In, const_cast<Constant*>(CPV)));
161 cerr << "XXX LocalMap: \n";
165 cerr << "XXX GlobalMap: \n";
166 PrintMap(*GlobalMap);
169 cerr << "Couldn't remap value: " << (void*)In << " " << *In << "\n";
170 assert(0 && "Couldn't remap value!");
175 // LinkGlobals - Loop through the global variables in the src module and merge
176 // them into the dest module...
178 static bool LinkGlobals(Module *Dest, const Module *Src,
179 map<const Value*, Value*> &ValueMap, string *Err = 0) {
180 // We will need a module level symbol table if the src module has a module
181 // level symbol table...
182 SymbolTable *ST = Src->getSymbolTable() ? Dest->getSymbolTableSure() : 0;
184 // Loop over all of the globals in the src module, mapping them over as we go
186 for (Module::const_giterator I = Src->gbegin(), E = Src->gend(); I != E; ++I){
187 const GlobalVariable *SGV = I;
190 // If the global variable has a name, and that name is already in use in the
191 // Dest module, make sure that the name is a compatible global variable...
193 if (SGV->hasExternalLinkage() && SGV->hasName() &&
194 (V = ST->lookup(SGV->getType(), SGV->getName())) &&
195 cast<GlobalVariable>(V)->hasExternalLinkage()) {
196 // The same named thing is a global variable, because the only two things
197 // that may be in a module level symbol table are Global Vars and
198 // Functions, and they both have distinct, nonoverlapping, possible types.
200 GlobalVariable *DGV = cast<GlobalVariable>(V);
202 // Check to see if the two GV's have the same Const'ness...
203 if (SGV->isConstant() != DGV->isConstant())
204 return Error(Err, "Global Variable Collision on '" +
205 SGV->getType()->getDescription() + "':%" + SGV->getName() +
206 " - Global variables differ in const'ness");
208 // Okay, everything is cool, remember the mapping...
209 ValueMap.insert(std::make_pair(SGV, DGV));
211 // No linking to be performed, simply create an identical version of the
212 // symbol over in the dest module... the initializer will be filled in
213 // later by LinkGlobalInits...
215 GlobalVariable *DGV =
216 new GlobalVariable(SGV->getType()->getElementType(), SGV->isConstant(),
217 SGV->hasInternalLinkage(), 0, SGV->getName());
219 // Add the new global to the dest module
220 Dest->getGlobalList().push_back(DGV);
222 // Make sure to remember this mapping...
223 ValueMap.insert(std::make_pair(SGV, DGV));
230 // LinkGlobalInits - Update the initializers in the Dest module now that all
231 // globals that may be referenced are in Dest.
233 static bool LinkGlobalInits(Module *Dest, const Module *Src,
234 map<const Value*, Value*> &ValueMap,
237 // Loop over all of the globals in the src module, mapping them over as we go
239 for (Module::const_giterator I = Src->gbegin(), E = Src->gend(); I != E; ++I){
240 const GlobalVariable *SGV = I;
242 if (SGV->hasInitializer()) { // Only process initialized GV's
243 // Figure out what the initializer looks like in the dest module...
245 cast<Constant>(RemapOperand(SGV->getInitializer(), ValueMap));
247 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[SGV]);
248 if (DGV->hasInitializer() && SGV->hasExternalLinkage() &&
249 DGV->hasExternalLinkage()) {
250 if (DGV->getInitializer() != DInit)
251 return Error(Err, "Global Variable Collision on '" +
252 SGV->getType()->getDescription() + "':%" +SGV->getName()+
253 " - Global variables have different initializers");
255 // Copy the initializer over now...
256 DGV->setInitializer(DInit);
263 // LinkFunctionProtos - Link the functions together between the two modules,
264 // without doing function bodies... this just adds external function prototypes
265 // to the Dest function...
267 static bool LinkFunctionProtos(Module *Dest, const Module *Src,
268 map<const Value*, Value*> &ValueMap,
270 // We will need a module level symbol table if the src module has a module
271 // level symbol table...
272 SymbolTable *ST = Src->getSymbolTable() ? Dest->getSymbolTableSure() : 0;
274 // Loop over all of the functions in the src module, mapping them over as we
277 for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) {
278 const Function *SF = I; // SrcFunction
281 // If the function has a name, and that name is already in use in the Dest
282 // module, make sure that the name is a compatible function...
284 if (SF->hasExternalLinkage() && SF->hasName() &&
285 (V = ST->lookup(SF->getType(), SF->getName())) &&
286 cast<Function>(V)->hasExternalLinkage()) {
287 // The same named thing is a Function, because the only two things
288 // that may be in a module level symbol table are Global Vars and
289 // Functions, and they both have distinct, nonoverlapping, possible types.
291 Function *DF = cast<Function>(V); // DestFunction
293 // Check to make sure the function is not defined in both modules...
294 if (!SF->isExternal() && !DF->isExternal())
295 return Error(Err, "Function '" +
296 SF->getFunctionType()->getDescription() + "':\"" +
297 SF->getName() + "\" - Function is already defined!");
299 // Otherwise, just remember this mapping...
300 ValueMap.insert(std::make_pair(SF, DF));
302 // Function does not already exist, simply insert an external function
303 // signature identical to SF into the dest module...
304 Function *DF = new Function(SF->getFunctionType(),
305 SF->hasInternalLinkage(),
308 // Add the function signature to the dest module...
309 Dest->getFunctionList().push_back(DF);
311 // ... and remember this mapping...
312 ValueMap.insert(std::make_pair(SF, DF));
318 // LinkFunctionBody - Copy the source function over into the dest function and
319 // fix up references to values. At this point we know that Dest is an external
320 // function, and that Src is not.
322 static bool LinkFunctionBody(Function *Dest, const Function *Src,
323 const map<const Value*, Value*> &GlobalMap,
325 assert(Src && Dest && Dest->isExternal() && !Src->isExternal());
326 map<const Value*, Value*> LocalMap; // Map for function local values
328 // Go through and convert function arguments over...
329 for (Function::const_aiterator I = Src->abegin(), E = Src->aend();
331 // Create the new function argument and add to the dest function...
332 Argument *DFA = new Argument(I->getType(), I->getName());
333 Dest->getArgumentList().push_back(DFA);
335 // Add a mapping to our local map
336 LocalMap.insert(std::make_pair(I, DFA));
339 // Loop over all of the basic blocks, copying the instructions over...
341 for (Function::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) {
342 // Create new basic block and add to mapping and the Dest function...
343 BasicBlock *DBB = new BasicBlock(I->getName(), Dest);
344 LocalMap.insert(std::make_pair(I, DBB));
346 // Loop over all of the instructions in the src basic block, copying them
347 // over. Note that this is broken in a strict sense because the cloned
348 // instructions will still be referencing values in the Src module, not
349 // the remapped values. In our case, however, we will not get caught and
350 // so we can delay patching the values up until later...
352 for (BasicBlock::const_iterator II = I->begin(), IE = I->end();
354 Instruction *DI = II->clone();
355 DI->setName(II->getName());
356 DBB->getInstList().push_back(DI);
357 LocalMap.insert(std::make_pair(II, DI));
361 // At this point, all of the instructions and values of the function are now
362 // copied over. The only problem is that they are still referencing values in
363 // the Source function as operands. Loop through all of the operands of the
364 // functions and patch them up to point to the local versions...
366 for (Function::iterator BB = Dest->begin(), BE = Dest->end(); BB != BE; ++BB)
367 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
368 for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end();
370 *OI = RemapOperand(*OI, LocalMap, &GlobalMap);
376 // LinkFunctionBodies - Link in the function bodies that are defined in the
377 // source module into the DestModule. This consists basically of copying the
378 // function over and fixing up references to values.
380 static bool LinkFunctionBodies(Module *Dest, const Module *Src,
381 map<const Value*, Value*> &ValueMap,
384 // Loop over all of the functions in the src module, mapping them over as we
387 for (Module::const_iterator SF = Src->begin(), E = Src->end(); SF != E; ++SF){
388 if (!SF->isExternal()) { // No body if function is external
389 Function *DF = cast<Function>(ValueMap[SF]); // Destination function
391 // DF not external SF external?
392 if (!DF->isExternal()) {
394 *Err = "Function '" + (SF->hasName() ? SF->getName() : string("")) +
395 "' body multiply defined!";
399 if (LinkFunctionBody(DF, SF, ValueMap, Err)) return true;
407 // LinkModules - This function links two modules together, with the resulting
408 // left module modified to be the composite of the two input modules. If an
409 // error occurs, true is returned and ErrorMsg (if not null) is set to indicate
410 // the problem. Upon failure, the Dest module could be in a modified state, and
411 // shouldn't be relied on to be consistent.
413 bool LinkModules(Module *Dest, const Module *Src, string *ErrorMsg = 0) {
415 // LinkTypes - Go through the symbol table of the Src module and see if any
416 // types are named in the src module that are not named in the Dst module.
417 // Make sure there are no type name conflicts.
419 if (LinkTypes(Dest, Src, ErrorMsg)) return true;
421 // ValueMap - Mapping of values from what they used to be in Src, to what they
424 map<const Value*, Value*> ValueMap;
427 // FIXME: This should be a two step process:
428 // FIXME: 1. LinkGlobals & LinkFunctionProtos
429 // FIXME: 2. LinkGlobalContents
431 // FIXME: Global variables and functions are the same!
435 // Insert all of the globals in src into the Dest module... without
437 if (LinkGlobals(Dest, Src, ValueMap, ErrorMsg)) return true;
439 // Link the functions together between the two modules, without doing function
440 // bodies... this just adds external function prototypes to the Dest
441 // function... We do this so that when we begin processing function bodies,
442 // all of the global values that may be referenced are available in our
445 if (LinkFunctionProtos(Dest, Src, ValueMap, ErrorMsg)) return true;
447 // Update the initializers in the Dest module now that all globals that may
448 // be referenced are in Dest.
450 if (LinkGlobalInits(Dest, Src, ValueMap, ErrorMsg)) return true;
452 // Link in the function bodies that are defined in the source module into the
453 // DestModule. This consists basically of copying the function over and
454 // fixing up references to values.
456 if (LinkFunctionBodies(Dest, Src, ValueMap, ErrorMsg)) return true;