1 //===- FunctionResolution.cpp - Resolve declarations to implementations ---===//
3 // Loop over the functions that are in the module and look for functions that
4 // have the same name. More often than not, there will be things like:
6 // declare void %foo(...)
7 // void %foo(int, int) { ... }
9 // because of the way things are declared in C. If this is the case, patch
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Transforms/IPO.h"
15 #include "llvm/Module.h"
16 #include "llvm/SymbolTable.h"
17 #include "llvm/DerivedTypes.h"
18 #include "llvm/Pass.h"
19 #include "llvm/iOther.h"
20 #include "llvm/Constant.h"
21 #include "Support/StatisticReporter.h"
30 Statistic<>NumResolved("funcresolve\t- Number of varargs functions resolved");
32 struct FunctionResolvingPass : public Pass {
35 RegisterPass<FunctionResolvingPass> X("funcresolve", "Resolve Functions");
38 Pass *createFunctionResolvingPass() {
39 return new FunctionResolvingPass();
42 // ConvertCallTo - Convert a call to a varargs function with no arg types
43 // specified to a concrete nonvarargs function.
45 static void ConvertCallTo(CallInst *CI, Function *Dest) {
46 const FunctionType::ParamTypes &ParamTys =
47 Dest->getFunctionType()->getParamTypes();
48 BasicBlock *BB = CI->getParent();
50 // Keep an iterator to where we want to insert cast instructions if the
51 // argument types don't agree.
53 BasicBlock::iterator BBI = CI;
54 assert(CI->getNumOperands()-1 == ParamTys.size() &&
55 "Function calls resolved funny somehow, incompatible number of args");
57 vector<Value*> Params;
59 // Convert all of the call arguments over... inserting cast instructions if
60 // the types are not compatible.
61 for (unsigned i = 1; i < CI->getNumOperands(); ++i) {
62 Value *V = CI->getOperand(i);
64 if (V->getType() != ParamTys[i-1]) { // Must insert a cast...
65 Instruction *Cast = new CastInst(V, ParamTys[i-1]);
66 BBI = ++BB->getInstList().insert(BBI, Cast);
73 Instruction *NewCall = new CallInst(Dest, Params);
75 // Replace the old call instruction with a new call instruction that calls
78 BBI = ++BB->getInstList().insert(BBI, NewCall);
80 // Remove the old call instruction from the program...
81 BB->getInstList().remove(BBI);
83 // Replace uses of the old instruction with the appropriate values...
85 if (NewCall->getType() == CI->getType()) {
86 CI->replaceAllUsesWith(NewCall);
87 NewCall->setName(CI->getName());
89 } else if (NewCall->getType() == Type::VoidTy) {
90 // Resolved function does not return a value but the prototype does. This
91 // often occurs because undefined functions default to returning integers.
92 // Just replace uses of the call (which are broken anyway) with dummy
94 CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
95 } else if (CI->getType() == Type::VoidTy) {
96 // If we are gaining a new return value, we don't have to do anything
99 assert(0 && "This should have been checked before!");
103 // The old instruction is no longer needed, destroy it!
108 bool FunctionResolvingPass::run(Module &M) {
109 SymbolTable *ST = M.getSymbolTable();
110 if (!ST) return false;
112 std::map<string, vector<Function*> > Functions;
114 // Loop over the entries in the symbol table. If an entry is a func pointer,
115 // then add it to the Functions map. We do a two pass algorithm here to avoid
116 // problems with iterators getting invalidated if we did a one pass scheme.
118 for (SymbolTable::iterator I = ST->begin(), E = ST->end(); I != E; ++I)
119 if (const PointerType *PT = dyn_cast<PointerType>(I->first))
120 if (isa<FunctionType>(PT->getElementType())) {
121 SymbolTable::VarMap &Plane = I->second;
122 for (SymbolTable::type_iterator PI = Plane.begin(), PE = Plane.end();
124 Function *F = cast<Function>(PI->second);
125 assert(PI->first == F->getName() &&
126 "Function name and symbol table do not agree!");
127 if (F->hasExternalLinkage()) // Only resolve decls to external fns
128 Functions[PI->first].push_back(F);
132 bool Changed = false;
134 // Now we have a list of all functions with a particular name. If there is
135 // more than one entry in a list, merge the functions together.
137 for (std::map<string, vector<Function*> >::iterator I = Functions.begin(),
138 E = Functions.end(); I != E; ++I) {
139 vector<Function*> &Functions = I->second;
140 Function *Implementation = 0; // Find the implementation
141 Function *Concrete = 0;
142 for (unsigned i = 0; i < Functions.size(); ) {
143 if (!Functions[i]->isExternal()) { // Found an implementation
144 if (Implementation != 0)
145 assert(Implementation == 0 && "Multiple definitions of the same"
146 " function. Case not handled yet!");
147 Implementation = Functions[i];
149 // Ignore functions that are never used so they don't cause spurious
150 // warnings... here we will actually DCE the function so that it isn't
153 if (Functions[i]->use_empty()) {
154 M.getFunctionList().erase(Functions[i]);
155 Functions.erase(Functions.begin()+i);
162 if (Functions[i] && (!Functions[i]->getFunctionType()->isVarArg())) {
163 if (Concrete) { // Found two different functions types. Can't choose
167 Concrete = Functions[i];
172 if (Functions.size() > 1) { // Found a multiply defined function...
173 // We should find exactly one non-vararg function definition, which is
174 // probably the implementation. Change all of the function definitions
175 // and uses to use it instead.
178 cerr << "Warning: Found functions types that are not compatible:\n";
179 for (unsigned i = 0; i < Functions.size(); ++i) {
180 cerr << "\t" << Functions[i]->getType()->getDescription() << " %"
181 << Functions[i]->getName() << "\n";
183 cerr << " No linkage of functions named '" << Functions[0]->getName()
186 for (unsigned i = 0; i < Functions.size(); ++i)
187 if (Functions[i] != Concrete) {
188 Function *Old = Functions[i];
189 const FunctionType *OldMT = Old->getFunctionType();
190 const FunctionType *ConcreteMT = Concrete->getFunctionType();
193 assert((Old->getReturnType() == Concrete->getReturnType() ||
194 Concrete->getReturnType() == Type::VoidTy ||
195 Old->getReturnType() == Type::VoidTy) &&
196 "Differing return types not handled yet!");
197 assert(OldMT->getParamTypes().size() <=
198 ConcreteMT->getParamTypes().size() &&
199 "Concrete type must have more specified parameters!");
201 // Check to make sure that if there are specified types, that they
204 for (unsigned i = 0; i < OldMT->getParamTypes().size(); ++i)
205 if (OldMT->getParamTypes()[i] != ConcreteMT->getParamTypes()[i]) {
206 cerr << "Parameter types conflict for" << OldMT
207 << " and " << ConcreteMT;
210 if (Broken) break; // Can't process this one!
213 // Attempt to convert all of the uses of the old function to the
214 // concrete form of the function. If there is a use of the fn that
215 // we don't understand here we punt to avoid making a bad
218 // At this point, we know that the return values are the same for
219 // our two functions and that the Old function has no varargs fns
220 // specified. In otherwords it's just <retty> (...)
222 for (unsigned i = 0; i < Old->use_size(); ) {
223 User *U = *(Old->use_begin()+i);
224 if (CastInst *CI = dyn_cast<CastInst>(U)) {
225 // Convert casts directly
226 assert(CI->getOperand(0) == Old);
227 CI->setOperand(0, Concrete);
230 } else if (CallInst *CI = dyn_cast<CallInst>(U)) {
231 // Can only fix up calls TO the argument, not args passed in.
232 if (CI->getCalledValue() == Old) {
233 ConvertCallTo(CI, Concrete);
237 cerr << "Couldn't cleanup this function call, must be an"
238 << " argument or something!" << CI;
242 cerr << "Cannot convert use of function: " << U << "\n";