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"
29 Statistic<>NumResolved("funcresolve\t- Number of varargs functions resolved");
31 struct FunctionResolvingPass : public Pass {
34 RegisterOpt<FunctionResolvingPass> X("funcresolve", "Resolve Functions");
37 Pass *createFunctionResolvingPass() {
38 return new FunctionResolvingPass();
41 // ConvertCallTo - Convert a call to a varargs function with no arg types
42 // specified to a concrete nonvarargs function.
44 static void ConvertCallTo(CallInst *CI, Function *Dest) {
45 const FunctionType::ParamTypes &ParamTys =
46 Dest->getFunctionType()->getParamTypes();
47 BasicBlock *BB = CI->getParent();
49 // Keep an iterator to where we want to insert cast instructions if the
50 // argument types don't agree.
52 BasicBlock::iterator BBI = CI;
53 assert(CI->getNumOperands()-1 == ParamTys.size() &&
54 "Function calls resolved funny somehow, incompatible number of args");
56 vector<Value*> Params;
58 // Convert all of the call arguments over... inserting cast instructions if
59 // the types are not compatible.
60 for (unsigned i = 1; i < CI->getNumOperands(); ++i) {
61 Value *V = CI->getOperand(i);
63 if (V->getType() != ParamTys[i-1]) { // Must insert a cast...
64 Instruction *Cast = new CastInst(V, ParamTys[i-1]);
65 BBI = ++BB->getInstList().insert(BBI, Cast);
72 Instruction *NewCall = new CallInst(Dest, Params);
74 // Replace the old call instruction with a new call instruction that calls
77 BBI = ++BB->getInstList().insert(BBI, NewCall);
79 // Remove the old call instruction from the program...
80 BB->getInstList().remove(BBI);
82 // Transfer the name over...
83 if (NewCall->getType() != Type::VoidTy)
84 NewCall->setName(CI->getName());
86 // Replace uses of the old instruction with the appropriate values...
88 if (NewCall->getType() == CI->getType()) {
89 CI->replaceAllUsesWith(NewCall);
90 NewCall->setName(CI->getName());
92 } else if (NewCall->getType() == Type::VoidTy) {
93 // Resolved function does not return a value but the prototype does. This
94 // often occurs because undefined functions default to returning integers.
95 // Just replace uses of the call (which are broken anyway) with dummy
97 CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
98 } else if (CI->getType() == Type::VoidTy) {
99 // If we are gaining a new return value, we don't have to do anything
100 // special here, because it will automatically be ignored.
102 // Insert a cast instruction to convert the return value of the function
103 // into it's new type. Of course we only need to do this if the return
104 // value of the function is actually USED.
106 if (!CI->use_empty()) {
107 CastInst *NewCast = new CastInst(NewCall, CI->getType(),
109 CI->replaceAllUsesWith(NewCast);
110 // Insert the new cast instruction...
111 BB->getInstList().insert(BBI, NewCast);
115 // The old instruction is no longer needed, destroy it!
120 bool FunctionResolvingPass::run(Module &M) {
121 SymbolTable *ST = M.getSymbolTable();
122 if (!ST) return false;
124 std::map<string, vector<Function*> > Functions;
126 // Loop over the entries in the symbol table. If an entry is a func pointer,
127 // then add it to the Functions map. We do a two pass algorithm here to avoid
128 // problems with iterators getting invalidated if we did a one pass scheme.
130 for (SymbolTable::iterator I = ST->begin(), E = ST->end(); I != E; ++I)
131 if (const PointerType *PT = dyn_cast<PointerType>(I->first))
132 if (isa<FunctionType>(PT->getElementType())) {
133 SymbolTable::VarMap &Plane = I->second;
134 for (SymbolTable::type_iterator PI = Plane.begin(), PE = Plane.end();
136 Function *F = cast<Function>(PI->second);
137 assert(PI->first == F->getName() &&
138 "Function name and symbol table do not agree!");
139 if (F->hasExternalLinkage()) // Only resolve decls to external fns
140 Functions[PI->first].push_back(F);
144 bool Changed = false;
146 // Now we have a list of all functions with a particular name. If there is
147 // more than one entry in a list, merge the functions together.
149 for (std::map<string, vector<Function*> >::iterator I = Functions.begin(),
150 E = Functions.end(); I != E; ++I) {
151 vector<Function*> &Functions = I->second;
152 Function *Implementation = 0; // Find the implementation
153 Function *Concrete = 0;
154 for (unsigned i = 0; i < Functions.size(); ) {
155 if (!Functions[i]->isExternal()) { // Found an implementation
156 if (Implementation != 0)
157 assert(Implementation == 0 && "Multiple definitions of the same"
158 " function. Case not handled yet!");
159 Implementation = Functions[i];
161 // Ignore functions that are never used so they don't cause spurious
162 // warnings... here we will actually DCE the function so that it isn't
165 if (Functions[i]->use_empty()) {
166 M.getFunctionList().erase(Functions[i]);
167 Functions.erase(Functions.begin()+i);
174 if (Functions[i] && (!Functions[i]->getFunctionType()->isVarArg())) {
175 if (Concrete) { // Found two different functions types. Can't choose
179 Concrete = Functions[i];
184 if (Functions.size() > 1) { // Found a multiply defined function...
185 // We should find exactly one non-vararg function definition, which is
186 // probably the implementation. Change all of the function definitions
187 // and uses to use it instead.
190 cerr << "Warning: Found functions types that are not compatible:\n";
191 for (unsigned i = 0; i < Functions.size(); ++i) {
192 cerr << "\t" << Functions[i]->getType()->getDescription() << " %"
193 << Functions[i]->getName() << "\n";
195 cerr << " No linkage of functions named '" << Functions[0]->getName()
198 for (unsigned i = 0; i < Functions.size(); ++i)
199 if (Functions[i] != Concrete) {
200 Function *Old = Functions[i];
201 const FunctionType *OldMT = Old->getFunctionType();
202 const FunctionType *ConcreteMT = Concrete->getFunctionType();
205 assert(OldMT->getParamTypes().size() <=
206 ConcreteMT->getParamTypes().size() &&
207 "Concrete type must have more specified parameters!");
209 // Check to make sure that if there are specified types, that they
212 for (unsigned i = 0; i < OldMT->getParamTypes().size(); ++i)
213 if (OldMT->getParamTypes()[i] != ConcreteMT->getParamTypes()[i]) {
214 cerr << "Parameter types conflict for" << OldMT
215 << " and " << ConcreteMT;
218 if (Broken) break; // Can't process this one!
221 // Attempt to convert all of the uses of the old function to the
222 // concrete form of the function. If there is a use of the fn that
223 // we don't understand here we punt to avoid making a bad
226 // At this point, we know that the return values are the same for
227 // our two functions and that the Old function has no varargs fns
228 // specified. In otherwords it's just <retty> (...)
230 for (unsigned i = 0; i < Old->use_size(); ) {
231 User *U = *(Old->use_begin()+i);
232 if (CastInst *CI = dyn_cast<CastInst>(U)) {
233 // Convert casts directly
234 assert(CI->getOperand(0) == Old);
235 CI->setOperand(0, Concrete);
238 } else if (CallInst *CI = dyn_cast<CallInst>(U)) {
239 // Can only fix up calls TO the argument, not args passed in.
240 if (CI->getCalledValue() == Old) {
241 ConvertCallTo(CI, Concrete);
245 cerr << "Couldn't cleanup this function call, must be an"
246 << " argument or something!" << CI;
250 cerr << "Cannot convert use of function: " << U << "\n";