Re: [PATCH] Enhanced nested functions lowering pass

[Andrew Pinski <pinskia at physics dot uc dot edu>]

On Mar 19, 2006, at 2:20 AM, Eric Botcazou wrote:

> > Actually this testcase is really the same as PR 24169 :).
>
> No, it isn't, the *whole* nonlocal frame structure always escapes.

The problem is the same.

Just change that testcase instead to:
struct g
{
  char i, j;
};
static void f(struct g *a)
{
  a->j = 1;
}
void h(void)
{
  struct g k = {2, 2};
  f(&k);
  if (k.i != 2)
    link_error ();
}
-----
Now there is no difference between the nested version and this non 
nested
version but the problem is the same.  In fact this is just an example 
of IPA
aliasing combined and IPA call clobbering can help.

if we change your (nested) example to:
int foo(void)
{
  int a = 0;
  int b = 0;
  int c;

  void bar1 (void)
  {
    a = 1;
  }

  void bar2 (void)
  {
    b = 1;
  }

  a = a + 1;
  bar2 ();
  c = a + b;
  bar1 ();
  return c + b;
}

Your enhancement of nest lowering does nothing to improve
this case which I would not doubt is more common in general in both
Ada and Fortran (and maybe even Pascal) than you unused nested function
example.

-- Pinski