[Bug optimization/15262] [tree-ssa] Alias analyzer cannot handle addressable fields

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-05-03 15:32 -------
Here is another example which does not use char pointers at all:
struct A
{
  int t;
  int i;
};

void
bar (float *p)
{
  *p = 5.2;
}

int
foo(struct A *locp, int i, int str)
{
  float f, g, *p;
  int T355;
  int *T356;
  /* Currently, the alias analyzer has limited support for handling
     aliases of structure fields when no other variables are aliased.
     Introduce additional aliases to confuse it.  */
  p =  i ? &g : &f;
  bar (p);
  if (*p > 0.0)
    str = 1;

  T355 = locp->i;
  T356 = &locp->i;  // the problem is that the front-end changes this to ((int *)((char*)locp +4))
  *T356 = str;
  T355 = locp->i;

  return T355;
}

main ()
{
  struct A loc;
  int str;

  loc.i = 2;
  str = foo (&loc, 10, 3);
  if (str!=1)
    abort ();
  return 0;
}

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15262