llvm-project/llvm/lib/VMCore/Module.cpp

//===-- Module.cpp - Implement the Module class ------------------*- C++ -*--=//
//
// This file implements the Module class for the VMCore library.
//
//===----------------------------------------------------------------------===//

#include "llvm/Module.h"
#include "llvm/InstrTypes.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "Support/STLExtras.h"
#include "Support/LeakDetector.h"
#include "SymbolTableListTraitsImpl.h"
#include <algorithm>
#include <map>

Function *ilist_traits<Function>::createNode() {
  FunctionType *FTy =
    FunctionType::get(Type::VoidTy, std::vector<const Type*>(), false);
  Function *Ret = new Function(FTy, GlobalValue::ExternalLinkage);
  // This should not be garbage monitored.
  LeakDetector::removeGarbageObject(Ret);
  return Ret;
}
GlobalVariable *ilist_traits<GlobalVariable>::createNode() {
  GlobalVariable *Ret = new GlobalVariable(Type::IntTy, false,
                                           GlobalValue::ExternalLinkage);
  // This should not be garbage monitored.
  LeakDetector::removeGarbageObject(Ret);
  return Ret;
}

iplist<Function> &ilist_traits<Function>::getList(Module *M) {
  return M->getFunctionList();
}
iplist<GlobalVariable> &ilist_traits<GlobalVariable>::getList(Module *M) {
  return M->getGlobalList();
}

// Explicit instantiations of SymbolTableListTraits since some of the methods
// are not in the public header file...
template SymbolTableListTraits<GlobalVariable, Module, Module>;
template SymbolTableListTraits<Function, Module, Module>;

// Define the GlobalValueRefMap as a struct that wraps a map so that we don't
// have Module.h depend on <map>
//
struct GlobalValueRefMap {
  typedef std::map<GlobalValue*, ConstantPointerRef*> MapTy;
  typedef MapTy::iterator iterator;
  std::map<GlobalValue*, ConstantPointerRef*> Map;
};


Module::Module(const std::string &MID)
  : ModuleID(MID), Endian(BigEndian), PtrSize(Pointer64) {
  FunctionList.setItemParent(this);
  FunctionList.setParent(this);
  GlobalList.setItemParent(this);
  GlobalList.setParent(this);
  GVRefMap = 0;
  SymTab = new SymbolTable();
}

Module::~Module() {
  dropAllReferences();
  GlobalList.clear();
  GlobalList.setParent(0);
  FunctionList.clear();
  FunctionList.setParent(0);
  delete SymTab;
}

// Module::dump() - Allow printing from debugger
void Module::dump() const {
  print(std::cerr);
}

// getOrInsertFunction - Look up the specified function in the module symbol
// table.  If it does not exist, add a prototype for the function and return
// it.  This is nice because it allows most passes to get away with not handling
// the symbol table directly for this common task.
//
Function *Module::getOrInsertFunction(const std::string &Name,
                                      const FunctionType *Ty) {
  SymbolTable &SymTab = getSymbolTable();

  // See if we have a definitions for the specified function already...
  if (Value *V = SymTab.lookup(PointerType::get(Ty), Name)) {
    return cast<Function>(V);      // Yup, got it
  } else {                         // Nope, add one
    Function *New = new Function(Ty, GlobalVariable::ExternalLinkage, Name);
    FunctionList.push_back(New);
    return New;                    // Return the new prototype...
  }
}

// getFunction - Look up the specified function in the module symbol table.
// If it does not exist, return null.
//
Function *Module::getFunction(const std::string &Name, const FunctionType *Ty) {
  SymbolTable &SymTab = getSymbolTable();
  return cast_or_null<Function>(SymTab.lookup(PointerType::get(Ty), Name));
}

// addTypeName - Insert an entry in the symbol table mapping Str to Type.  If
// there is already an entry for this name, true is returned and the symbol
// table is not modified.
//
bool Module::addTypeName(const std::string &Name, const Type *Ty) {
  SymbolTable &ST = getSymbolTable();

  if (ST.lookup(Type::TypeTy, Name)) return true;  // Already in symtab...
  
  // Not in symbol table?  Set the name with the Symtab as an argument so the
  // type knows what to update...
  ((Value*)Ty)->setName(Name, &ST);

  return false;
}

/// getMainFunction - This function looks up main efficiently.  This is such a
/// common case, that it is a method in Module.  If main cannot be found, a
/// null pointer is returned.
///
Function *Module::getMainFunction() {
  std::vector<const Type*> Params;

  // int main(void)...
  if (Function *F = getFunction("main", FunctionType::get(Type::IntTy,
                                                          Params, false)))
    return F;

  // void main(void)...
  if (Function *F = getFunction("main", FunctionType::get(Type::VoidTy,
                                                          Params, false)))
    return F;

  Params.push_back(Type::IntTy);

  // int main(int argc)...
  if (Function *F = getFunction("main", FunctionType::get(Type::IntTy,
                                                          Params, false)))
    return F;

  // void main(int argc)...
  if (Function *F = getFunction("main", FunctionType::get(Type::VoidTy,
                                                          Params, false)))
    return F;

  for (unsigned i = 0; i != 2; ++i) {  // Check argv and envp
    Params.push_back(PointerType::get(PointerType::get(Type::SByteTy)));

    // int main(int argc, char **argv)...
    if (Function *F = getFunction("main", FunctionType::get(Type::IntTy,
                                                            Params, false)))
      return F;
    
    // void main(int argc, char **argv)...
    if (Function *F = getFunction("main", FunctionType::get(Type::VoidTy,
                                                            Params, false)))
      return F;
  }

  // Ok, try to find main the hard way...
  return getNamedFunction("main");
}

/// getNamedFunction - Return the first function in the module with the
/// specified name, of arbitrary type.  This method returns null if a function
/// with the specified name is not found.
///
Function *Module::getNamedFunction(const std::string &Name) {
  // Loop over all of the functions, looking for the function desired
  Function *Found = 0;
  for (iterator I = begin(), E = end(); I != E; ++I)
    if (I->getName() == Name)
      if (I->isExternal())
        Found = I;
      else
        return I;
  return Found; // Non-external function not found...
}



// getTypeName - If there is at least one entry in the symbol table for the
// specified type, return it.
//
std::string Module::getTypeName(const Type *Ty) {
  const SymbolTable &ST = getSymbolTable();
  if (ST.find(Type::TypeTy) == ST.end())
    return ""; // No names for types...

  SymbolTable::type_const_iterator TI = ST.type_begin(Type::TypeTy);
  SymbolTable::type_const_iterator TE = ST.type_end(Type::TypeTy);

  while (TI != TE && TI->second != (const Value*)Ty)
    ++TI;

  if (TI != TE)  // Must have found an entry!
    return TI->first;
  return "";     // Must not have found anything...
}


// dropAllReferences() - This function causes all the subelementss to "let go"
// of all references that they are maintaining.  This allows one to 'delete' a
// whole module at a time, even though there may be circular references... first
// all references are dropped, and all use counts go to zero.  Then everything
// is delete'd for real.  Note that no operations are valid on an object that
// has "dropped all references", except operator delete.
//
void Module::dropAllReferences() {
  for(Module::iterator I = begin(), E = end(); I != E; ++I)
    I->dropAllReferences();

  for(Module::giterator I = gbegin(), E = gend(); I != E; ++I)
    I->dropAllReferences();

  // If there are any GlobalVariable references still out there, nuke them now.
  // Since all references are hereby dropped, nothing could possibly reference
  // them still.  Note that destroying all of the constant pointer refs will
  // eventually cause the GVRefMap field to be set to null (by
  // destroyConstantPointerRef, below).
  //
  while (GVRefMap)
    // Delete the ConstantPointerRef node...  
    GVRefMap->Map.begin()->second->destroyConstant();
}

// Accessor for the underlying GlobalValRefMap...
ConstantPointerRef *Module::getConstantPointerRef(GlobalValue *V){
  // Create ref map lazily on demand...
  if (GVRefMap == 0) GVRefMap = new GlobalValueRefMap();

  GlobalValueRefMap::iterator I = GVRefMap->Map.find(V);
  if (I != GVRefMap->Map.end()) return I->second;

  ConstantPointerRef *Ref = new ConstantPointerRef(V);
  GVRefMap->Map[V] = Ref;
  return Ref;
}

void Module::destroyConstantPointerRef(ConstantPointerRef *CPR) {
  assert(GVRefMap && "No map allocated, but we have a CPR?");
  if (!GVRefMap->Map.erase(CPR->getValue()))  // Remove it from the map...
    assert(0 && "ConstantPointerRef not found in module CPR map!");
  
  if (GVRefMap->Map.empty()) {   // If the map is empty, delete it.
    delete GVRefMap;
    GVRefMap = 0;
  }
}

void Module::mutateConstantPointerRef(GlobalValue *OldGV, GlobalValue *NewGV) {
  assert(OldGV != NewGV && "Cannot mutate to the same global!");
  GlobalValueRefMap::iterator I = GVRefMap->Map.find(OldGV);
  assert(I != GVRefMap->Map.end() && 
	 "mutateConstantPointerRef; OldGV not in table!");
  ConstantPointerRef *Ref = I->second;

  // Remove the old entry...
  GVRefMap->Map.erase(I);

  // Check to see if a CPR already exists for NewGV
  I = GVRefMap->Map.lower_bound(NewGV);

  if (I == GVRefMap->Map.end() || I->first != NewGV) {
    // Insert the new entry...
    GVRefMap->Map.insert(I, std::make_pair(NewGV, Ref));
  } else {
    // Otherwise, an entry already exists for the current global value.
    // Completely replace the old CPR with the existing one...
    Ref->replaceAllUsesWith(I->second);
    delete Ref;
  }
}