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/Constants.h"
21 #include "llvm/Assembly/Writer.h" // FIXME: remove when varargs implemented
22 #include "Support/Statistic.h"
26 Statistic<>NumResolved("funcresolve", "Number of varargs functions resolved");
27 Statistic<> NumGlobals("funcresolve", "Number of global variables resolved");
29 struct FunctionResolvingPass : public Pass {
32 RegisterOpt<FunctionResolvingPass> X("funcresolve", "Resolve Functions");
35 Pass *createFunctionResolvingPass() {
36 return new FunctionResolvingPass();
39 // ConvertCallTo - Convert a call to a varargs function with no arg types
40 // specified to a concrete nonvarargs function.
42 static void ConvertCallTo(CallInst *CI, Function *Dest) {
43 const FunctionType::ParamTypes &ParamTys =
44 Dest->getFunctionType()->getParamTypes();
45 BasicBlock *BB = CI->getParent();
47 // Keep an iterator to where we want to insert cast instructions if the
48 // argument types don't agree.
50 unsigned NumArgsToCopy = CI->getNumOperands()-1;
51 if (NumArgsToCopy != ParamTys.size() &&
52 !(NumArgsToCopy > ParamTys.size() &&
53 Dest->getFunctionType()->isVarArg())) {
54 std::cerr << "WARNING: Call arguments do not match expected number of"
56 std::cerr << "WARNING: In function '"
57 << CI->getParent()->getParent()->getName() << "': call: " << *CI;
58 std::cerr << "Function resolved to: ";
59 WriteAsOperand(std::cerr, Dest);
61 if (NumArgsToCopy > ParamTys.size())
62 NumArgsToCopy = ParamTys.size();
65 std::vector<Value*> Params;
67 // Convert all of the call arguments over... inserting cast instructions if
68 // the types are not compatible.
69 for (unsigned i = 1; i <= NumArgsToCopy; ++i) {
70 Value *V = CI->getOperand(i);
72 if (i-1 < ParamTys.size() && V->getType() != ParamTys[i-1]) {
73 // Must insert a cast...
74 V = new CastInst(V, ParamTys[i-1], "argcast", CI);
80 // If the function takes extra parameters that are not being passed in, pass
81 // null values in now...
82 for (unsigned i = NumArgsToCopy; i < ParamTys.size(); ++i)
83 Params.push_back(Constant::getNullValue(ParamTys[i]));
85 // Replace the old call instruction with a new call instruction that calls
88 Instruction *NewCall = new CallInst(Dest, Params, "", CI);
89 std::string Name = CI->getName(); CI->setName("");
91 // Transfer the name over...
92 if (NewCall->getType() != Type::VoidTy)
93 NewCall->setName(Name);
95 // Replace uses of the old instruction with the appropriate values...
97 if (NewCall->getType() == CI->getType()) {
98 CI->replaceAllUsesWith(NewCall);
99 NewCall->setName(Name);
101 } else if (NewCall->getType() == Type::VoidTy) {
102 // Resolved function does not return a value but the prototype does. This
103 // often occurs because undefined functions default to returning integers.
104 // Just replace uses of the call (which are broken anyway) with dummy
106 CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
107 } else if (CI->getType() == Type::VoidTy) {
108 // If we are gaining a new return value, we don't have to do anything
109 // special here, because it will automatically be ignored.
111 // Insert a cast instruction to convert the return value of the function
112 // into it's new type. Of course we only need to do this if the return
113 // value of the function is actually USED.
115 if (!CI->use_empty()) {
116 // Insert the new cast instruction...
117 CastInst *NewCast = new CastInst(NewCall, CI->getType(), Name, CI);
118 CI->replaceAllUsesWith(NewCast);
122 // The old instruction is no longer needed, destroy it!
123 BB->getInstList().erase(CI);
127 static bool ResolveFunctions(Module &M, std::vector<GlobalValue*> &Globals,
128 Function *Concrete) {
129 bool Changed = false;
130 for (unsigned i = 0; i != Globals.size(); ++i)
131 if (Globals[i] != Concrete) {
132 Function *Old = cast<Function>(Globals[i]);
133 const FunctionType *OldMT = Old->getFunctionType();
134 const FunctionType *ConcreteMT = Concrete->getFunctionType();
136 if (OldMT->getParamTypes().size() > ConcreteMT->getParamTypes().size() &&
137 !ConcreteMT->isVarArg())
138 if (!Old->use_empty()) {
139 std::cerr << "WARNING: Linking function '" << Old->getName()
140 << "' is causing arguments to be dropped.\n";
141 std::cerr << "WARNING: Prototype: ";
142 WriteAsOperand(std::cerr, Old);
143 std::cerr << " resolved to ";
144 WriteAsOperand(std::cerr, Concrete);
148 // Check to make sure that if there are specified types, that they
151 unsigned NumArguments = std::min(OldMT->getParamTypes().size(),
152 ConcreteMT->getParamTypes().size());
154 if (!Old->use_empty() && !Concrete->use_empty())
155 for (unsigned i = 0; i < NumArguments; ++i)
156 if (OldMT->getParamTypes()[i] != ConcreteMT->getParamTypes()[i]) {
157 std::cerr << "WARNING: Function [" << Old->getName()
158 << "]: Parameter types conflict for: '" << OldMT
159 << "' and '" << ConcreteMT << "'\n";
163 // Attempt to convert all of the uses of the old function to the concrete
164 // form of the function. If there is a use of the fn that we don't
165 // understand here we punt to avoid making a bad transformation.
167 // At this point, we know that the return values are the same for our two
168 // functions and that the Old function has no varargs fns specified. In
169 // otherwords it's just <retty> (...)
171 for (unsigned i = 0; i < Old->use_size(); ) {
172 User *U = *(Old->use_begin()+i);
173 if (CastInst *CI = dyn_cast<CastInst>(U)) {
174 // Convert casts directly
175 assert(CI->getOperand(0) == Old);
176 CI->setOperand(0, Concrete);
179 } else if (CallInst *CI = dyn_cast<CallInst>(U)) {
180 // Can only fix up calls TO the argument, not args passed in.
181 if (CI->getCalledValue() == Old) {
182 ConvertCallTo(CI, Concrete);
193 // If there are any more uses that we could not resolve, force them to use
194 // a casted pointer now.
195 if (!Old->use_empty()) {
196 NumResolved += Old->use_size();
197 Constant *NewCPR = ConstantPointerRef::get(Concrete);
198 Old->replaceAllUsesWith(ConstantExpr::getCast(NewCPR, Old->getType()));
202 // Since there are no uses of Old anymore, remove it from the module.
203 M.getFunctionList().erase(Old);
209 static bool ResolveGlobalVariables(Module &M,
210 std::vector<GlobalValue*> &Globals,
211 GlobalVariable *Concrete) {
212 bool Changed = false;
213 assert(isa<ArrayType>(Concrete->getType()->getElementType()) &&
214 "Concrete version should be an array type!");
216 // Get the type of the things that may be resolved to us...
217 const ArrayType *CATy =cast<ArrayType>(Concrete->getType()->getElementType());
218 const Type *AETy = CATy->getElementType();
220 Constant *CCPR = ConstantPointerRef::get(Concrete);
222 for (unsigned i = 0; i != Globals.size(); ++i)
223 if (Globals[i] != Concrete) {
224 GlobalVariable *Old = cast<GlobalVariable>(Globals[i]);
225 const ArrayType *OATy = cast<ArrayType>(Old->getType()->getElementType());
226 if (OATy->getElementType() != AETy || OATy->getNumElements() != 0) {
227 std::cerr << "WARNING: Two global variables exist with the same name "
228 << "that cannot be resolved!\n";
232 Old->replaceAllUsesWith(ConstantExpr::getCast(CCPR, Old->getType()));
234 // Since there are no uses of Old anymore, remove it from the module.
235 M.getGlobalList().erase(Old);
243 static bool ProcessGlobalsWithSameName(Module &M,
244 std::vector<GlobalValue*> &Globals) {
245 assert(!Globals.empty() && "Globals list shouldn't be empty here!");
247 bool isFunction = isa<Function>(Globals[0]); // Is this group all functions?
248 GlobalValue *Concrete = 0; // The most concrete implementation to resolve to
250 assert((isFunction ^ isa<GlobalVariable>(Globals[0])) &&
251 "Should either be function or gvar!");
253 for (unsigned i = 0; i != Globals.size(); ) {
254 if (isa<Function>(Globals[i]) != isFunction) {
255 std::cerr << "WARNING: Found function and global variable with the "
256 << "same name: '" << Globals[i]->getName() << "'.\n";
257 return false; // Don't know how to handle this, bail out!
261 // For functions, we look to merge functions definitions of "int (...)"
262 // to 'int (int)' or 'int ()' or whatever else is not completely generic.
264 Function *F = cast<Function>(Globals[i]);
265 if (!F->isExternal()) {
266 if (Concrete && !Concrete->isExternal())
267 return false; // Found two different functions types. Can't choose!
269 Concrete = Globals[i];
270 } else if (Concrete) {
271 if (Concrete->isExternal()) // If we have multiple external symbols...x
272 if (F->getFunctionType()->getNumParams() >
273 cast<Function>(Concrete)->getFunctionType()->getNumParams())
274 Concrete = F; // We are more concrete than "Concrete"!
280 // For global variables, we have to merge C definitions int A[][4] with
281 // int[6][4]. A[][4] is represented as A[0][4] by the CFE.
282 GlobalVariable *GV = cast<GlobalVariable>(Globals[i]);
283 if (!isa<ArrayType>(GV->getType()->getElementType())) {
285 break; // Non array's cannot be compatible with other types.
286 } else if (Concrete == 0) {
289 // Must have different types... allow merging A[0][4] w/ A[6][4] if
290 // A[0][4] is external.
291 const ArrayType *NAT = cast<ArrayType>(GV->getType()->getElementType());
292 const ArrayType *CAT =
293 cast<ArrayType>(Concrete->getType()->getElementType());
295 if (NAT->getElementType() != CAT->getElementType()) {
296 Concrete = 0; // Non-compatible types
298 } else if (NAT->getNumElements() == 0 && GV->isExternal()) {
299 // Concrete remains the same
300 } else if (CAT->getNumElements() == 0 && Concrete->isExternal()) {
301 Concrete = GV; // Concrete becomes GV
303 Concrete = 0; // Cannot merge these types...
311 if (Globals.size() > 1) { // Found a multiply defined global...
312 // If there are no external declarations, and there is at most one
313 // externally visible instance of the global, then there is nothing to do.
315 bool HasExternal = false;
316 unsigned NumInstancesWithExternalLinkage = 0;
318 for (unsigned i = 0, e = Globals.size(); i != e; ++i) {
319 if (Globals[i]->isExternal())
321 else if (!Globals[i]->hasInternalLinkage())
322 NumInstancesWithExternalLinkage++;
325 if (!HasExternal && NumInstancesWithExternalLinkage <= 1)
326 return false; // Nothing to do? Must have multiple internal definitions.
329 // We should find exactly one concrete function definition, which is
330 // probably the implementation. Change all of the function definitions and
331 // uses to use it instead.
334 std::cerr << "WARNING: Found global types that are not compatible:\n";
335 for (unsigned i = 0; i < Globals.size(); ++i) {
336 std::cerr << "\t" << Globals[i]->getType()->getDescription() << " %"
337 << Globals[i]->getName() << "\n";
339 std::cerr << " No linkage of globals named '" << Globals[0]->getName()
345 return ResolveFunctions(M, Globals, cast<Function>(Concrete));
347 return ResolveGlobalVariables(M, Globals,
348 cast<GlobalVariable>(Concrete));
353 bool FunctionResolvingPass::run(Module &M) {
354 SymbolTable &ST = M.getSymbolTable();
356 std::map<std::string, std::vector<GlobalValue*> > Globals;
358 // Loop over the entries in the symbol table. If an entry is a func pointer,
359 // then add it to the Functions map. We do a two pass algorithm here to avoid
360 // problems with iterators getting invalidated if we did a one pass scheme.
362 for (SymbolTable::iterator I = ST.begin(), E = ST.end(); I != E; ++I)
363 if (const PointerType *PT = dyn_cast<PointerType>(I->first)) {
364 SymbolTable::VarMap &Plane = I->second;
365 for (SymbolTable::type_iterator PI = Plane.begin(), PE = Plane.end();
367 GlobalValue *GV = cast<GlobalValue>(PI->second);
368 assert(PI->first == GV->getName() &&
369 "Global name and symbol table do not agree!");
370 Globals[PI->first].push_back(GV);
374 bool Changed = false;
376 // Now we have a list of all functions with a particular name. If there is
377 // more than one entry in a list, merge the functions together.
379 for (std::map<std::string, std::vector<GlobalValue*> >::iterator
380 I = Globals.begin(), E = Globals.end(); I != E; ++I)
381 Changed |= ProcessGlobalsWithSameName(M, I->second);
383 // Now loop over all of the globals, checking to see if any are trivially
384 // dead. If so, remove them now.
386 for (Module::iterator I = M.begin(), E = M.end(); I != E; )
387 if (I->isExternal() && I->use_empty()) {
390 M.getFunctionList().erase(F);
397 for (Module::giterator I = M.gbegin(), E = M.gend(); I != E; )
398 if (I->isExternal() && I->use_empty()) {
399 GlobalVariable *GV = I;
401 M.getGlobalList().erase(GV);