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/Statistic.h"
29 Statistic<>NumResolved("funcresolve", "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 V = new CastInst(V, ParamTys[i-1], "argcast", BBI);
69 // Replace the old call instruction with a new call instruction that calls
72 Instruction *NewCall = new CallInst(Dest, Params, "", BBI);
74 // Remove the old call instruction from the program...
75 BB->getInstList().remove(BBI);
77 // Transfer the name over...
78 if (NewCall->getType() != Type::VoidTy)
79 NewCall->setName(CI->getName());
81 // Replace uses of the old instruction with the appropriate values...
83 if (NewCall->getType() == CI->getType()) {
84 CI->replaceAllUsesWith(NewCall);
85 NewCall->setName(CI->getName());
87 } else if (NewCall->getType() == Type::VoidTy) {
88 // Resolved function does not return a value but the prototype does. This
89 // often occurs because undefined functions default to returning integers.
90 // Just replace uses of the call (which are broken anyway) with dummy
92 CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
93 } else if (CI->getType() == Type::VoidTy) {
94 // If we are gaining a new return value, we don't have to do anything
95 // special here, because it will automatically be ignored.
97 // Insert a cast instruction to convert the return value of the function
98 // into it's new type. Of course we only need to do this if the return
99 // value of the function is actually USED.
101 if (!CI->use_empty()) {
102 // Insert the new cast instruction...
103 CastInst *NewCast = new CastInst(NewCall, CI->getType(),
104 NewCall->getName(), BBI);
105 CI->replaceAllUsesWith(NewCast);
109 // The old instruction is no longer needed, destroy it!
114 bool FunctionResolvingPass::run(Module &M) {
115 SymbolTable *ST = M.getSymbolTable();
116 if (!ST) return false;
118 std::map<string, vector<Function*> > Functions;
120 // Loop over the entries in the symbol table. If an entry is a func pointer,
121 // then add it to the Functions map. We do a two pass algorithm here to avoid
122 // problems with iterators getting invalidated if we did a one pass scheme.
124 for (SymbolTable::iterator I = ST->begin(), E = ST->end(); I != E; ++I)
125 if (const PointerType *PT = dyn_cast<PointerType>(I->first))
126 if (isa<FunctionType>(PT->getElementType())) {
127 SymbolTable::VarMap &Plane = I->second;
128 for (SymbolTable::type_iterator PI = Plane.begin(), PE = Plane.end();
130 Function *F = cast<Function>(PI->second);
131 assert(PI->first == F->getName() &&
132 "Function name and symbol table do not agree!");
133 if (F->hasExternalLinkage()) // Only resolve decls to external fns
134 Functions[PI->first].push_back(F);
138 bool Changed = false;
140 // Now we have a list of all functions with a particular name. If there is
141 // more than one entry in a list, merge the functions together.
143 for (std::map<string, vector<Function*> >::iterator I = Functions.begin(),
144 E = Functions.end(); I != E; ++I) {
145 vector<Function*> &Functions = I->second;
146 Function *Implementation = 0; // Find the implementation
147 Function *Concrete = 0;
148 for (unsigned i = 0; i < Functions.size(); ) {
149 if (!Functions[i]->isExternal()) { // Found an implementation
150 if (Implementation != 0)
151 assert(Implementation == 0 && "Multiple definitions of the same"
152 " function. Case not handled yet!");
153 Implementation = Functions[i];
155 // Ignore functions that are never used so they don't cause spurious
156 // warnings... here we will actually DCE the function so that it isn't
159 if (Functions[i]->use_empty()) {
160 M.getFunctionList().erase(Functions[i]);
161 Functions.erase(Functions.begin()+i);
168 if (Functions[i] && (!Functions[i]->getFunctionType()->isVarArg())) {
169 if (Concrete) { // Found two different functions types. Can't choose
173 Concrete = Functions[i];
178 if (Functions.size() > 1) { // Found a multiply defined function...
179 // We should find exactly one non-vararg function definition, which is
180 // probably the implementation. Change all of the function definitions
181 // and uses to use it instead.
184 cerr << "Warning: Found functions types that are not compatible:\n";
185 for (unsigned i = 0; i < Functions.size(); ++i) {
186 cerr << "\t" << Functions[i]->getType()->getDescription() << " %"
187 << Functions[i]->getName() << "\n";
189 cerr << " No linkage of functions named '" << Functions[0]->getName()
192 for (unsigned i = 0; i < Functions.size(); ++i)
193 if (Functions[i] != Concrete) {
194 Function *Old = Functions[i];
195 const FunctionType *OldMT = Old->getFunctionType();
196 const FunctionType *ConcreteMT = Concrete->getFunctionType();
199 assert(OldMT->getParamTypes().size() <=
200 ConcreteMT->getParamTypes().size() &&
201 "Concrete type must have more specified parameters!");
203 // Check to make sure that if there are specified types, that they
206 for (unsigned i = 0; i < OldMT->getParamTypes().size(); ++i)
207 if (OldMT->getParamTypes()[i] != ConcreteMT->getParamTypes()[i]) {
208 cerr << "Parameter types conflict for" << OldMT
209 << " and " << ConcreteMT;
212 if (Broken) break; // Can't process this one!
215 // Attempt to convert all of the uses of the old function to the
216 // concrete form of the function. If there is a use of the fn that
217 // we don't understand here we punt to avoid making a bad
220 // At this point, we know that the return values are the same for
221 // our two functions and that the Old function has no varargs fns
222 // specified. In otherwords it's just <retty> (...)
224 for (unsigned i = 0; i < Old->use_size(); ) {
225 User *U = *(Old->use_begin()+i);
226 if (CastInst *CI = dyn_cast<CastInst>(U)) {
227 // Convert casts directly
228 assert(CI->getOperand(0) == Old);
229 CI->setOperand(0, Concrete);
232 } else if (CallInst *CI = dyn_cast<CallInst>(U)) {
233 // Can only fix up calls TO the argument, not args passed in.
234 if (CI->getCalledValue() == Old) {
235 ConvertCallTo(CI, Concrete);
239 cerr << "Couldn't cleanup this function call, must be an"
240 << " argument or something!" << CI;
244 cerr << "Cannot convert use of function: " << U << "\n";