| //===- FunctionResolution.cpp - Resolve declarations to implementations ---===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file was developed by the LLVM research group and is distributed under |
| // the University of Illinois Open Source License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // Loop over the functions that are in the module and look for functions that |
| // have the same name. More often than not, there will be things like: |
| // |
| // declare void %foo(...) |
| // void %foo(int, int) { ... } |
| // |
| // because of the way things are declared in C. If this is the case, patch |
| // things up. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/Transforms/IPO.h" |
| #include "llvm/Module.h" |
| #include "llvm/DerivedTypes.h" |
| #include "llvm/Pass.h" |
| #include "llvm/Instructions.h" |
| #include "llvm/Constants.h" |
| #include "llvm/Support/CallSite.h" |
| #include "llvm/Target/TargetData.h" |
| #include "llvm/Assembly/Writer.h" |
| #include "llvm/ADT/Statistic.h" |
| #include <algorithm> |
| using namespace llvm; |
| |
| namespace { |
| Statistic<>NumResolved("funcresolve", "Number of varargs functions resolved"); |
| Statistic<> NumGlobals("funcresolve", "Number of global variables resolved"); |
| |
| struct FunctionResolvingPass : public ModulePass { |
| virtual void getAnalysisUsage(AnalysisUsage &AU) const { |
| AU.addRequired<TargetData>(); |
| } |
| |
| bool runOnModule(Module &M); |
| }; |
| RegisterOpt<FunctionResolvingPass> X("funcresolve", "Resolve Functions"); |
| } |
| |
| ModulePass *llvm::createFunctionResolvingPass() { |
| return new FunctionResolvingPass(); |
| } |
| |
| static bool ResolveFunctions(Module &M, std::vector<GlobalValue*> &Globals, |
| Function *Concrete) { |
| bool Changed = false; |
| for (unsigned i = 0; i != Globals.size(); ++i) |
| if (Globals[i] != Concrete) { |
| Function *Old = cast<Function>(Globals[i]); |
| const FunctionType *OldMT = Old->getFunctionType(); |
| const FunctionType *ConcreteMT = Concrete->getFunctionType(); |
| |
| if (OldMT->getNumParams() > ConcreteMT->getNumParams() && |
| !ConcreteMT->isVarArg()) |
| if (!Old->use_empty()) { |
| std::cerr << "WARNING: Linking function '" << Old->getName() |
| << "' is causing arguments to be dropped.\n"; |
| std::cerr << "WARNING: Prototype: "; |
| WriteAsOperand(std::cerr, Old); |
| std::cerr << " resolved to "; |
| WriteAsOperand(std::cerr, Concrete); |
| std::cerr << "\n"; |
| } |
| |
| // Check to make sure that if there are specified types, that they |
| // match... |
| // |
| unsigned NumArguments = std::min(OldMT->getNumParams(), |
| ConcreteMT->getNumParams()); |
| |
| if (!Old->use_empty() && !Concrete->use_empty()) |
| for (unsigned i = 0; i < NumArguments; ++i) |
| if (OldMT->getParamType(i) != ConcreteMT->getParamType(i)) |
| if (OldMT->getParamType(i)->getTypeID() != |
| ConcreteMT->getParamType(i)->getTypeID()) { |
| std::cerr << "WARNING: Function [" << Old->getName() |
| << "]: Parameter types conflict for: '"; |
| WriteTypeSymbolic(std::cerr, OldMT, &M); |
| std::cerr << "' and '"; |
| WriteTypeSymbolic(std::cerr, ConcreteMT, &M); |
| std::cerr << "'\n"; |
| return Changed; |
| } |
| |
| // Attempt to convert all of the uses of the old function to the concrete |
| // form of the function. If there is a use of the fn that we don't |
| // understand here we punt to avoid making a bad transformation. |
| // |
| // At this point, we know that the return values are the same for our two |
| // functions and that the Old function has no varargs fns specified. In |
| // otherwords it's just <retty> (...) |
| // |
| if (!Old->use_empty()) { |
| Value *Replacement = Concrete; |
| if (Concrete->getType() != Old->getType()) |
| Replacement = ConstantExpr::getCast(Concrete, Old->getType()); |
| NumResolved += Old->getNumUses(); |
| Old->replaceAllUsesWith(Replacement); |
| } |
| |
| // Since there are no uses of Old anymore, remove it from the module. |
| M.getFunctionList().erase(Old); |
| } |
| return Changed; |
| } |
| |
| |
| static bool ResolveGlobalVariables(Module &M, |
| std::vector<GlobalValue*> &Globals, |
| GlobalVariable *Concrete) { |
| bool Changed = false; |
| |
| for (unsigned i = 0; i != Globals.size(); ++i) |
| if (Globals[i] != Concrete) { |
| Constant *Cast = ConstantExpr::getCast(Concrete, Globals[i]->getType()); |
| Globals[i]->replaceAllUsesWith(Cast); |
| |
| // Since there are no uses of Old anymore, remove it from the module. |
| M.getGlobalList().erase(cast<GlobalVariable>(Globals[i])); |
| |
| ++NumGlobals; |
| Changed = true; |
| } |
| return Changed; |
| } |
| |
| // Check to see if all of the callers of F ignore the return value. |
| static bool CallersAllIgnoreReturnValue(Function &F) { |
| if (F.getReturnType() == Type::VoidTy) return true; |
| for (Value::use_iterator I = F.use_begin(), E = F.use_end(); I != E; ++I) { |
| if (GlobalValue *GV = dyn_cast<GlobalValue>(*I)) { |
| for (Value::use_iterator I = GV->use_begin(), E = GV->use_end(); |
| I != E; ++I) { |
| CallSite CS = CallSite::get(*I); |
| if (!CS.getInstruction() || !CS.getInstruction()->use_empty()) |
| return false; |
| } |
| } else { |
| CallSite CS = CallSite::get(*I); |
| if (!CS.getInstruction() || !CS.getInstruction()->use_empty()) |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| static bool ProcessGlobalsWithSameName(Module &M, TargetData &TD, |
| std::vector<GlobalValue*> &Globals) { |
| assert(!Globals.empty() && "Globals list shouldn't be empty here!"); |
| |
| bool isFunction = isa<Function>(Globals[0]); // Is this group all functions? |
| GlobalValue *Concrete = 0; // The most concrete implementation to resolve to |
| |
| for (unsigned i = 0; i != Globals.size(); ) { |
| if (isa<Function>(Globals[i]) != isFunction) { |
| std::cerr << "WARNING: Found function and global variable with the " |
| << "same name: '" << Globals[i]->getName() << "'.\n"; |
| return false; // Don't know how to handle this, bail out! |
| } |
| |
| if (isFunction) { |
| // For functions, we look to merge functions definitions of "int (...)" |
| // to 'int (int)' or 'int ()' or whatever else is not completely generic. |
| // |
| Function *F = cast<Function>(Globals[i]); |
| if (!F->isExternal()) { |
| if (Concrete && !Concrete->isExternal()) |
| return false; // Found two different functions types. Can't choose! |
| |
| Concrete = Globals[i]; |
| } else if (Concrete) { |
| if (Concrete->isExternal()) // If we have multiple external symbols... |
| if (F->getFunctionType()->getNumParams() > |
| cast<Function>(Concrete)->getFunctionType()->getNumParams()) |
| Concrete = F; // We are more concrete than "Concrete"! |
| |
| } else { |
| Concrete = F; |
| } |
| } else { |
| GlobalVariable *GV = cast<GlobalVariable>(Globals[i]); |
| if (!GV->isExternal()) { |
| if (Concrete) { |
| std::cerr << "WARNING: Two global variables with external linkage" |
| << " exist with the same name: '" << GV->getName() |
| << "'!\n"; |
| return false; |
| } |
| Concrete = GV; |
| } |
| } |
| ++i; |
| } |
| |
| if (Globals.size() > 1) { // Found a multiply defined global... |
| // If there are no external declarations, and there is at most one |
| // externally visible instance of the global, then there is nothing to do. |
| // |
| bool HasExternal = false; |
| unsigned NumInstancesWithExternalLinkage = 0; |
| |
| for (unsigned i = 0, e = Globals.size(); i != e; ++i) { |
| if (Globals[i]->isExternal()) |
| HasExternal = true; |
| else if (!Globals[i]->hasInternalLinkage()) |
| NumInstancesWithExternalLinkage++; |
| } |
| |
| if (!HasExternal && NumInstancesWithExternalLinkage <= 1) |
| return false; // Nothing to do? Must have multiple internal definitions. |
| |
| // There are a couple of special cases we don't want to print the warning |
| // for, check them now. |
| bool DontPrintWarning = false; |
| if (Concrete && Globals.size() == 2) { |
| GlobalValue *Other = Globals[Globals[0] == Concrete]; |
| // If the non-concrete global is a function which takes (...) arguments, |
| // and the return values match (or was never used), do not warn. |
| if (Function *ConcreteF = dyn_cast<Function>(Concrete)) |
| if (Function *OtherF = dyn_cast<Function>(Other)) |
| if ((ConcreteF->getReturnType() == OtherF->getReturnType() || |
| CallersAllIgnoreReturnValue(*OtherF)) && |
| OtherF->getFunctionType()->isVarArg() && |
| OtherF->getFunctionType()->getNumParams() == 0) |
| DontPrintWarning = true; |
| |
| // Otherwise, if the non-concrete global is a global array variable with a |
| // size of 0, and the concrete global is an array with a real size, don't |
| // warn. This occurs due to declaring 'extern int A[];'. |
| if (GlobalVariable *ConcreteGV = dyn_cast<GlobalVariable>(Concrete)) |
| if (GlobalVariable *OtherGV = dyn_cast<GlobalVariable>(Other)) { |
| const Type *CTy = ConcreteGV->getType(); |
| const Type *OTy = OtherGV->getType(); |
| |
| if (CTy->isSized()) |
| if (!OTy->isSized() || !TD.getTypeSize(OTy) || |
| TD.getTypeSize(OTy) == TD.getTypeSize(CTy)) |
| DontPrintWarning = true; |
| } |
| } |
| |
| if (0 && !DontPrintWarning) { |
| std::cerr << "WARNING: Found global types that are not compatible:\n"; |
| for (unsigned i = 0; i < Globals.size(); ++i) { |
| std::cerr << "\t"; |
| WriteTypeSymbolic(std::cerr, Globals[i]->getType(), &M); |
| std::cerr << " %" << Globals[i]->getName() << "\n"; |
| } |
| } |
| |
| if (!Concrete) |
| Concrete = Globals[0]; |
| else if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Concrete)) { |
| // Handle special case hack to change globals if it will make their types |
| // happier in the long run. The situation we do this is intentionally |
| // extremely limited. |
| if (GV->use_empty() && GV->hasInitializer() && |
| GV->getInitializer()->isNullValue()) { |
| // Check to see if there is another (external) global with the same size |
| // and a non-empty use-list. If so, we will make IT be the real |
| // implementation. |
| unsigned TS = TD.getTypeSize(Concrete->getType()->getElementType()); |
| for (unsigned i = 0, e = Globals.size(); i != e; ++i) |
| if (Globals[i] != Concrete && !Globals[i]->use_empty() && |
| isa<GlobalVariable>(Globals[i]) && |
| TD.getTypeSize(Globals[i]->getType()->getElementType()) == TS) { |
| // At this point we want to replace Concrete with Globals[i]. Make |
| // concrete external, and Globals[i] have an initializer. |
| GlobalVariable *NGV = cast<GlobalVariable>(Globals[i]); |
| const Type *ElTy = NGV->getType()->getElementType(); |
| NGV->setInitializer(Constant::getNullValue(ElTy)); |
| cast<GlobalVariable>(Concrete)->setInitializer(0); |
| Concrete = NGV; |
| break; |
| } |
| } |
| } |
| |
| if (isFunction) |
| return ResolveFunctions(M, Globals, cast<Function>(Concrete)); |
| else |
| return ResolveGlobalVariables(M, Globals, |
| cast<GlobalVariable>(Concrete)); |
| } |
| return false; |
| } |
| |
| bool FunctionResolvingPass::runOnModule(Module &M) { |
| std::map<std::string, std::vector<GlobalValue*> > Globals; |
| |
| // Loop over the globals, adding them to the Globals map. We use a two pass |
| // algorithm here to avoid problems with iterators getting invalidated if we |
| // did a one pass scheme. |
| // |
| bool Changed = false; |
| for (Module::iterator I = M.begin(), E = M.end(); I != E; ) { |
| Function *F = I++; |
| if (F->use_empty() && F->isExternal()) { |
| M.getFunctionList().erase(F); |
| Changed = true; |
| } else if (!F->hasInternalLinkage() && !F->getName().empty() && |
| !F->getIntrinsicID()) |
| Globals[F->getName()].push_back(F); |
| } |
| |
| for (Module::global_iterator I = M.global_begin(), E = M.global_end(); I != E; ) { |
| GlobalVariable *GV = I++; |
| if (GV->use_empty() && GV->isExternal()) { |
| M.getGlobalList().erase(GV); |
| Changed = true; |
| } else if (!GV->hasInternalLinkage() && !GV->getName().empty()) |
| Globals[GV->getName()].push_back(GV); |
| } |
| |
| TargetData &TD = getAnalysis<TargetData>(); |
| |
| // Now we have a list of all functions with a particular name. If there is |
| // more than one entry in a list, merge the functions together. |
| // |
| for (std::map<std::string, std::vector<GlobalValue*> >::iterator |
| I = Globals.begin(), E = Globals.end(); I != E; ++I) |
| Changed |= ProcessGlobalsWithSameName(M, TD, I->second); |
| |
| // Now loop over all of the globals, checking to see if any are trivially |
| // dead. If so, remove them now. |
| |
| for (Module::iterator I = M.begin(), E = M.end(); I != E; ) |
| if (I->isExternal() && I->use_empty()) { |
| Function *F = I; |
| ++I; |
| M.getFunctionList().erase(F); |
| ++NumResolved; |
| Changed = true; |
| } else { |
| ++I; |
| } |
| |
| for (Module::global_iterator I = M.global_begin(), E = M.global_end(); I != E; ) |
| if (I->isExternal() && I->use_empty()) { |
| GlobalVariable *GV = I; |
| ++I; |
| M.getGlobalList().erase(GV); |
| ++NumGlobals; |
| Changed = true; |
| } else { |
| ++I; |
| } |
| |
| return Changed; |
| } |
