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"
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 static bool ResolveFunctions(Module &M, std::vector<GlobalValue*> &Globals,
42 for (unsigned i = 0; i != Globals.size(); ++i)
43 if (Globals[i] != Concrete) {
44 Function *Old = cast<Function>(Globals[i]);
45 const FunctionType *OldMT = Old->getFunctionType();
46 const FunctionType *ConcreteMT = Concrete->getFunctionType();
48 if (OldMT->getParamTypes().size() > ConcreteMT->getParamTypes().size() &&
49 !ConcreteMT->isVarArg())
50 if (!Old->use_empty()) {
51 std::cerr << "WARNING: Linking function '" << Old->getName()
52 << "' is causing arguments to be dropped.\n";
53 std::cerr << "WARNING: Prototype: ";
54 WriteAsOperand(std::cerr, Old);
55 std::cerr << " resolved to ";
56 WriteAsOperand(std::cerr, Concrete);
60 // Check to make sure that if there are specified types, that they
63 unsigned NumArguments = std::min(OldMT->getParamTypes().size(),
64 ConcreteMT->getParamTypes().size());
66 if (!Old->use_empty() && !Concrete->use_empty())
67 for (unsigned i = 0; i < NumArguments; ++i)
68 if (OldMT->getParamTypes()[i] != ConcreteMT->getParamTypes()[i])
69 if (OldMT->getParamTypes()[i]->getPrimitiveID() !=
70 ConcreteMT->getParamTypes()[i]->getPrimitiveID()) {
71 std::cerr << "WARNING: Function [" << Old->getName()
72 << "]: Parameter types conflict for: '" << OldMT
73 << "' and '" << ConcreteMT << "'\n";
77 // Attempt to convert all of the uses of the old function to the concrete
78 // form of the function. If there is a use of the fn that we don't
79 // understand here we punt to avoid making a bad transformation.
81 // At this point, we know that the return values are the same for our two
82 // functions and that the Old function has no varargs fns specified. In
83 // otherwords it's just <retty> (...)
85 if (!Old->use_empty()) { // Avoid making the CPR unless we really need it
86 Value *Replacement = Concrete;
87 if (Concrete->getType() != Old->getType())
88 Replacement = ConstantExpr::getCast(ConstantPointerRef::get(Concrete),
90 NumResolved += Old->use_size();
91 Old->replaceAllUsesWith(Replacement);
94 // Since there are no uses of Old anymore, remove it from the module.
95 M.getFunctionList().erase(Old);
101 static bool ResolveGlobalVariables(Module &M,
102 std::vector<GlobalValue*> &Globals,
103 GlobalVariable *Concrete) {
104 bool Changed = false;
105 assert(isa<ArrayType>(Concrete->getType()->getElementType()) &&
106 "Concrete version should be an array type!");
108 // Get the type of the things that may be resolved to us...
109 const ArrayType *CATy =cast<ArrayType>(Concrete->getType()->getElementType());
110 const Type *AETy = CATy->getElementType();
112 Constant *CCPR = ConstantPointerRef::get(Concrete);
114 for (unsigned i = 0; i != Globals.size(); ++i)
115 if (Globals[i] != Concrete) {
116 GlobalVariable *Old = cast<GlobalVariable>(Globals[i]);
117 const ArrayType *OATy = cast<ArrayType>(Old->getType()->getElementType());
118 if (OATy->getElementType() != AETy || OATy->getNumElements() != 0) {
119 std::cerr << "WARNING: Two global variables exist with the same name "
120 << "that cannot be resolved!\n";
124 Old->replaceAllUsesWith(ConstantExpr::getCast(CCPR, Old->getType()));
126 // Since there are no uses of Old anymore, remove it from the module.
127 M.getGlobalList().erase(Old);
135 static bool ProcessGlobalsWithSameName(Module &M,
136 std::vector<GlobalValue*> &Globals) {
137 assert(!Globals.empty() && "Globals list shouldn't be empty here!");
139 bool isFunction = isa<Function>(Globals[0]); // Is this group all functions?
140 GlobalValue *Concrete = 0; // The most concrete implementation to resolve to
142 assert((isFunction ^ isa<GlobalVariable>(Globals[0])) &&
143 "Should either be function or gvar!");
145 for (unsigned i = 0; i != Globals.size(); ) {
146 if (isa<Function>(Globals[i]) != isFunction) {
147 std::cerr << "WARNING: Found function and global variable with the "
148 << "same name: '" << Globals[i]->getName() << "'.\n";
149 return false; // Don't know how to handle this, bail out!
153 // For functions, we look to merge functions definitions of "int (...)"
154 // to 'int (int)' or 'int ()' or whatever else is not completely generic.
156 Function *F = cast<Function>(Globals[i]);
157 if (!F->isExternal()) {
158 if (Concrete && !Concrete->isExternal())
159 return false; // Found two different functions types. Can't choose!
161 Concrete = Globals[i];
162 } else if (Concrete) {
163 if (Concrete->isExternal()) // If we have multiple external symbols...x
164 if (F->getFunctionType()->getNumParams() >
165 cast<Function>(Concrete)->getFunctionType()->getNumParams())
166 Concrete = F; // We are more concrete than "Concrete"!
172 // For global variables, we have to merge C definitions int A[][4] with
173 // int[6][4]. A[][4] is represented as A[0][4] by the CFE.
174 GlobalVariable *GV = cast<GlobalVariable>(Globals[i]);
175 if (!isa<ArrayType>(GV->getType()->getElementType())) {
177 break; // Non array's cannot be compatible with other types.
178 } else if (Concrete == 0) {
181 // Must have different types... allow merging A[0][4] w/ A[6][4] if
182 // A[0][4] is external.
183 const ArrayType *NAT = cast<ArrayType>(GV->getType()->getElementType());
184 const ArrayType *CAT =
185 cast<ArrayType>(Concrete->getType()->getElementType());
187 if (NAT->getElementType() != CAT->getElementType()) {
188 Concrete = 0; // Non-compatible types
190 } else if (NAT->getNumElements() == 0 && GV->isExternal()) {
191 // Concrete remains the same
192 } else if (CAT->getNumElements() == 0 && Concrete->isExternal()) {
193 Concrete = GV; // Concrete becomes GV
195 Concrete = 0; // Cannot merge these types...
203 if (Globals.size() > 1) { // Found a multiply defined global...
204 // If there are no external declarations, and there is at most one
205 // externally visible instance of the global, then there is nothing to do.
207 bool HasExternal = false;
208 unsigned NumInstancesWithExternalLinkage = 0;
210 for (unsigned i = 0, e = Globals.size(); i != e; ++i) {
211 if (Globals[i]->isExternal())
213 else if (!Globals[i]->hasInternalLinkage())
214 NumInstancesWithExternalLinkage++;
217 if (!HasExternal && NumInstancesWithExternalLinkage <= 1)
218 return false; // Nothing to do? Must have multiple internal definitions.
221 // We should find exactly one concrete function definition, which is
222 // probably the implementation. Change all of the function definitions and
223 // uses to use it instead.
226 std::cerr << "WARNING: Found global types that are not compatible:\n";
227 for (unsigned i = 0; i < Globals.size(); ++i) {
228 std::cerr << "\t" << Globals[i]->getType()->getDescription() << " %"
229 << Globals[i]->getName() << "\n";
231 std::cerr << " No linkage of globals named '" << Globals[0]->getName()
237 return ResolveFunctions(M, Globals, cast<Function>(Concrete));
239 return ResolveGlobalVariables(M, Globals,
240 cast<GlobalVariable>(Concrete));
245 bool FunctionResolvingPass::run(Module &M) {
246 SymbolTable &ST = M.getSymbolTable();
248 std::map<std::string, std::vector<GlobalValue*> > Globals;
250 // Loop over the entries in the symbol table. If an entry is a func pointer,
251 // then add it to the Functions map. We do a two pass algorithm here to avoid
252 // problems with iterators getting invalidated if we did a one pass scheme.
254 for (SymbolTable::iterator I = ST.begin(), E = ST.end(); I != E; ++I)
255 if (const PointerType *PT = dyn_cast<PointerType>(I->first)) {
256 SymbolTable::VarMap &Plane = I->second;
257 for (SymbolTable::type_iterator PI = Plane.begin(), PE = Plane.end();
259 GlobalValue *GV = cast<GlobalValue>(PI->second);
260 assert(PI->first == GV->getName() &&
261 "Global name and symbol table do not agree!");
262 Globals[PI->first].push_back(GV);
266 bool Changed = false;
268 // Now we have a list of all functions with a particular name. If there is
269 // more than one entry in a list, merge the functions together.
271 for (std::map<std::string, std::vector<GlobalValue*> >::iterator
272 I = Globals.begin(), E = Globals.end(); I != E; ++I)
273 Changed |= ProcessGlobalsWithSameName(M, I->second);
275 // Now loop over all of the globals, checking to see if any are trivially
276 // dead. If so, remove them now.
278 for (Module::iterator I = M.begin(), E = M.end(); I != E; )
279 if (I->isExternal() && I->use_empty()) {
282 M.getFunctionList().erase(F);
289 for (Module::giterator I = M.gbegin(), E = M.gend(); I != E; )
290 if (I->isExternal() && I->use_empty()) {
291 GlobalVariable *GV = I;
293 M.getGlobalList().erase(GV);