Re: [Bug rtl-optimization/20367] alias analysis doesn't take into account that variables that haven't their address taken can't alias arbitrary MEMs

[Diego Novillo]

pinskia at gcc dot gnu dot org wrote:
void g();
int
f(int s, int *a)
{
  static int i;
  for (i = 0; i < 800; i++)
  {
    g();
    s += a[i];
  }
  return s;
}
But all of this needs to be on the tree level to be really effective.
This particular case is trivial to fix inside the tree optimizers. 
Variable 'i' is a local variable with static storage that is not upward 
exposed (i.e., it has no default definition).

Once you recognize that, you can safely flip the TREE_STATIC bit on the 
variable and expose it as a gimple register.

Diego.