[Bug middle-end/27181] Does not fold access to base with cast to different derived type

[rguenth at gcc dot gnu dot org]

------- Comment #3 from rguenth at gcc dot gnu dot org  2006-04-28 20:22 -------
Ok, this one does it, just for the curious:

template <int Dim>
struct Loc;

struct LocStorage
{ 
  int x;
};

template <>
struct Loc<1> : public LocStorage
{
  Loc() {}
  Loc(int i) { this->x = i; }
  Loc<1>& operator[](int) { return *this; }
  int get() { return this->x; }
};

template <int Dim>
struct WrapLoc1 : public Loc<1>
{
  WrapLoc1() {}
  WrapLoc1(int i) : Loc<1>(i) {}
};

template <int Dim>
struct WrapLocN : public Loc<Dim-1>
{
  WrapLocN() {}
  WrapLocN(int i) : Loc<Dim-1>(i) {}
};

template <int Dim>
struct Loc : public WrapLocN<Dim>, public WrapLoc1<Dim>
{
  Loc() {}
  Loc(int i) : WrapLocN<Dim>(i), WrapLoc1<Dim>(i) {}
  Loc<1>& operator[](int i)
  {
    if (i == Dim-1)
      {
        WrapLoc1<Dim> *w = this;
        return *w;
      }
    else
      {
        WrapLocN<Dim> *sl = this;
        return sl->operator[](i-1);
      }
  }
};

int foo(void)
{
  Loc<4> l(1);
  return l[0].get() + l[1].get() + l[2].get() + l[3].get();
}

now, we can optimize foo() to return 4, starting with gcc 4.0.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27181