forked from OSchip/llvm-project
253 lines
9.2 KiB
C++
253 lines
9.2 KiB
C++
//===- FunctionResolution.cpp - Resolve declarations to implementations ---===//
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//
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// Loop over the functions that are in the module and look for functions that
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// have the same name. More often than not, there will be things like:
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//
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// declare void %foo(...)
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// void %foo(int, int) { ... }
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//
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// because of the way things are declared in C. If this is the case, patch
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// things up.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/IPO.h"
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#include "llvm/Module.h"
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#include "llvm/SymbolTable.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/Pass.h"
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#include "llvm/iOther.h"
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#include "llvm/Constant.h"
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#include "Support/StatisticReporter.h"
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#include <iostream>
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#include <algorithm>
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using std::vector;
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using std::string;
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using std::cerr;
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namespace {
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Statistic<>NumResolved("funcresolve\t- Number of varargs functions resolved");
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struct FunctionResolvingPass : public Pass {
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bool run(Module &M);
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};
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RegisterPass<FunctionResolvingPass> X("funcresolve", "Resolve Functions");
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}
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Pass *createFunctionResolvingPass() {
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return new FunctionResolvingPass();
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}
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// ConvertCallTo - Convert a call to a varargs function with no arg types
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// specified to a concrete nonvarargs function.
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//
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static void ConvertCallTo(CallInst *CI, Function *Dest) {
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const FunctionType::ParamTypes &ParamTys =
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Dest->getFunctionType()->getParamTypes();
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BasicBlock *BB = CI->getParent();
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// Keep an iterator to where we want to insert cast instructions if the
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// argument types don't agree.
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//
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BasicBlock::iterator BBI = CI;
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assert(CI->getNumOperands()-1 == ParamTys.size() &&
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"Function calls resolved funny somehow, incompatible number of args");
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vector<Value*> Params;
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// Convert all of the call arguments over... inserting cast instructions if
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// the types are not compatible.
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for (unsigned i = 1; i < CI->getNumOperands(); ++i) {
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Value *V = CI->getOperand(i);
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if (V->getType() != ParamTys[i-1]) { // Must insert a cast...
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Instruction *Cast = new CastInst(V, ParamTys[i-1]);
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BBI = ++BB->getInstList().insert(BBI, Cast);
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V = Cast;
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}
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Params.push_back(V);
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}
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Instruction *NewCall = new CallInst(Dest, Params);
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// Replace the old call instruction with a new call instruction that calls
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// the real function.
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//
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BBI = ++BB->getInstList().insert(BBI, NewCall);
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// Remove the old call instruction from the program...
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BB->getInstList().remove(BBI);
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// Replace uses of the old instruction with the appropriate values...
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//
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if (NewCall->getType() == CI->getType()) {
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CI->replaceAllUsesWith(NewCall);
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NewCall->setName(CI->getName());
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} else if (NewCall->getType() == Type::VoidTy) {
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// Resolved function does not return a value but the prototype does. This
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// often occurs because undefined functions default to returning integers.
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// Just replace uses of the call (which are broken anyway) with dummy
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// values.
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CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
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} else if (CI->getType() == Type::VoidTy) {
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// If we are gaining a new return value, we don't have to do anything
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// special.
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} else {
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assert(0 && "This should have been checked before!");
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abort();
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}
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// The old instruction is no longer needed, destroy it!
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delete CI;
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}
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bool FunctionResolvingPass::run(Module &M) {
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SymbolTable *ST = M.getSymbolTable();
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if (!ST) return false;
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std::map<string, vector<Function*> > Functions;
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// Loop over the entries in the symbol table. If an entry is a func pointer,
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// then add it to the Functions map. We do a two pass algorithm here to avoid
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// problems with iterators getting invalidated if we did a one pass scheme.
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//
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for (SymbolTable::iterator I = ST->begin(), E = ST->end(); I != E; ++I)
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if (const PointerType *PT = dyn_cast<PointerType>(I->first))
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if (isa<FunctionType>(PT->getElementType())) {
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SymbolTable::VarMap &Plane = I->second;
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for (SymbolTable::type_iterator PI = Plane.begin(), PE = Plane.end();
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PI != PE; ++PI) {
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Function *F = cast<Function>(PI->second);
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assert(PI->first == F->getName() &&
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"Function name and symbol table do not agree!");
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if (F->hasExternalLinkage()) // Only resolve decls to external fns
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Functions[PI->first].push_back(F);
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}
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}
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bool Changed = false;
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// Now we have a list of all functions with a particular name. If there is
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// more than one entry in a list, merge the functions together.
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//
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for (std::map<string, vector<Function*> >::iterator I = Functions.begin(),
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E = Functions.end(); I != E; ++I) {
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vector<Function*> &Functions = I->second;
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Function *Implementation = 0; // Find the implementation
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Function *Concrete = 0;
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for (unsigned i = 0; i < Functions.size(); ) {
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if (!Functions[i]->isExternal()) { // Found an implementation
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if (Implementation != 0)
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assert(Implementation == 0 && "Multiple definitions of the same"
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" function. Case not handled yet!");
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Implementation = Functions[i];
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} else {
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// Ignore functions that are never used so they don't cause spurious
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// warnings... here we will actually DCE the function so that it isn't
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// used later.
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//
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if (Functions[i]->use_empty()) {
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M.getFunctionList().erase(Functions[i]);
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Functions.erase(Functions.begin()+i);
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Changed = true;
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++NumResolved;
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continue;
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}
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}
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if (Functions[i] && (!Functions[i]->getFunctionType()->isVarArg())) {
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if (Concrete) { // Found two different functions types. Can't choose
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Concrete = 0;
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break;
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}
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Concrete = Functions[i];
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}
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++i;
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}
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if (Functions.size() > 1) { // Found a multiply defined function...
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// We should find exactly one non-vararg function definition, which is
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// probably the implementation. Change all of the function definitions
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// and uses to use it instead.
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//
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if (!Concrete) {
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cerr << "Warning: Found functions types that are not compatible:\n";
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for (unsigned i = 0; i < Functions.size(); ++i) {
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cerr << "\t" << Functions[i]->getType()->getDescription() << " %"
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<< Functions[i]->getName() << "\n";
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}
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cerr << " No linkage of functions named '" << Functions[0]->getName()
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<< "' performed!\n";
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} else {
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for (unsigned i = 0; i < Functions.size(); ++i)
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if (Functions[i] != Concrete) {
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Function *Old = Functions[i];
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const FunctionType *OldMT = Old->getFunctionType();
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const FunctionType *ConcreteMT = Concrete->getFunctionType();
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bool Broken = false;
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assert((Old->getReturnType() == Concrete->getReturnType() ||
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Concrete->getReturnType() == Type::VoidTy ||
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Old->getReturnType() == Type::VoidTy) &&
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"Differing return types not handled yet!");
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assert(OldMT->getParamTypes().size() <=
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ConcreteMT->getParamTypes().size() &&
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"Concrete type must have more specified parameters!");
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// Check to make sure that if there are specified types, that they
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// match...
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//
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for (unsigned i = 0; i < OldMT->getParamTypes().size(); ++i)
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if (OldMT->getParamTypes()[i] != ConcreteMT->getParamTypes()[i]) {
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cerr << "Parameter types conflict for" << OldMT
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<< " and " << ConcreteMT;
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Broken = true;
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}
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if (Broken) break; // Can't process this one!
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// Attempt to convert all of the uses of the old function to the
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// concrete form of the function. If there is a use of the fn that
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// we don't understand here we punt to avoid making a bad
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// transformation.
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//
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// At this point, we know that the return values are the same for
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// our two functions and that the Old function has no varargs fns
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// specified. In otherwords it's just <retty> (...)
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//
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for (unsigned i = 0; i < Old->use_size(); ) {
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User *U = *(Old->use_begin()+i);
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if (CastInst *CI = dyn_cast<CastInst>(U)) {
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// Convert casts directly
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assert(CI->getOperand(0) == Old);
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CI->setOperand(0, Concrete);
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Changed = true;
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++NumResolved;
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} else if (CallInst *CI = dyn_cast<CallInst>(U)) {
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// Can only fix up calls TO the argument, not args passed in.
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if (CI->getCalledValue() == Old) {
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ConvertCallTo(CI, Concrete);
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Changed = true;
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++NumResolved;
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} else {
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cerr << "Couldn't cleanup this function call, must be an"
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<< " argument or something!" << CI;
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++i;
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}
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} else {
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cerr << "Cannot convert use of function: " << U << "\n";
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++i;
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}
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}
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}
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}
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}
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}
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return Changed;
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}
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