Re: RFA: Fix calculation of size of builtin setjmp buffer

[Jakub Jelinek <jakub@redhat.com>]

On Tue, May 06, 2014 at 03:34:37PM +0100, Nicholas Clifton wrote:
> --- gcc/except.c	(revision 210096)
> +++ gcc/except.c	(working copy)
> @@ -286,8 +286,8 @@
>        tmp = size_int (FIRST_PSEUDO_REGISTER + 2 - 1);
>  #endif
>  #else
> -      /* builtin_setjmp takes a pointer to 5 words.  */
> -      tmp = size_int (5 * BITS_PER_WORD / POINTER_SIZE - 1);
> +      /* builtin_setjmp uses a buffer big enough to hold 5 pointers.  */
> +      tmp = size_int (5 * POINTER_SIZE / BITS_PER_WORD - 1);

But what will this do on targets where POINTER_SIZE is smaller than
BITS_PER_WORD?  E.g. I think some options on s390 or ppc.
If you want it to be always 5 pointers, then you want
  tmp = size_int (4);
and not something else, otherwise it really depends on how exactly it is
used, perhaps it can be 5 * MAX (BITS_PER_WORD / POINTER_SIZE, 1) - 1
or whatever else, but 5 * POINTER_SIZE / BITS_PER_WORD is definitely wrong.

>  #endif
>        tmp = build_index_type (tmp);
>        tmp = build_array_type (ptr_type_node, tmp);

	Jakub