[Bug middle-end/81445] Dynamic stack allocation not optimized into static allocation

["wilco at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81445

--- Comment #5 from Wilco <wilco at gcc dot gnu.org> ---
(In reply to Marc Glisse from comment #4)
> (In reply to Wilco from comment #2)
> > I don't see it happen for the simplest case in current trunk:
> 
> 400 bytes is too large, try again with something smaller. (I'm with you if
> you want to increase the threshold)

I see, it appears 256 bytes is the maximum, that's a bit low indeed. Note it
will statically allocate 100 arrays of 256 bytes but not 1 array of 25600
bytes...

Also it doesn't support these simple cases:

void vla2(int x)
{
  if (x == 10)
  {
    int arr[x];
    t (arr);
  }
}

void vla3(int x)
{
  if (x >= 0 && x <= 10)
  {
    int arr[x];
    t (arr);
  }
}