-fstrict-aliasing fixes 5/6: make type system independent of flag_strict_aliasing

[Richard Biener]

On Wed, 9 Dec 2015, Jan Hubicka wrote:

> Hi
> this patch implements the trik for punting if we get too many nested pointers.
> This fixes the ada tstcases. Curiously enough I would like to replace safe_push
> by quick_push but doing so I get weird error about freeing non-heap object
> in the auto_vec desructor...

That's odd but a sign of you doing sth wrong ;)  Like somehow
clobbering m_using_auto_storage of the vec.

But of course if you use a maximum length of 8 there
is no need to use a vec<>, just use a fixed bool[8] array
(or an integer mask).

> Bootstraping/regtesting x86_64-linux. Ok if it passes?

Ok.

Thanks,
Richard.

> Honza
> 
> 	* alias.c (get_alias_set): Punt after getting 8 nested pointers.
> 
> Index: alias.c
> ===================================================================
> --- alias.c	(revision 231439)
> +++ alias.c	(working copy)
> @@ -990,6 +990,14 @@ get_alias_set (tree t)
>  	   || TREE_CODE (p) == VECTOR_TYPE;
>  	   p = TREE_TYPE (p))
>  	{
> +	  /* Ada supports recusive pointers.  Instead of doing recrusion check
> +	     just give up once the preallocated space of 8 elements is up.
> +	     In this case just punt to void * alias set.  */
> +	  if (reference.length () == 8)
> +	    {
> +	      p = ptr_type_node;
> +	      break;
> +	    }
>  	  if (TREE_CODE (p) == REFERENCE_TYPE)
>  	    /* In LTO we want languages that use references to be compatible
>   	       with languages that use pointers.  */