Re: [patch] lno branch merge -- vectorizer patch #1

[Steven Bosscher <stevenb at suse dot de>]

On Thursday 22 July 2004 18:26, Dorit Naishlos wrote:
> +   /* An insn writing through a restricted pointer is "independent" of any
> +      insn reading or writing through a different pointer, in the same
> +      block/scope.
> +    */
> +   if ((TREE_CODE (ta) == POINTER_TYPE && TYPE_RESTRICT (ta)
> +        && !DR_IS_READ(a))
> +       || (TREE_CODE (tb) == POINTER_TYPE && TYPE_RESTRICT (tb)
> + 	  && !DR_IS_READ(b)))
> +     {
> +       *differ_p = true;
> +       return true;
> +     }

This is not the semantics of 'restrict' the way I remember it (but of
course I may be wrong ;-) In tree.h the comment for TYPE_RESTRICT states:

    /* If nonzero, this type is `restrict'-qualified, in the C sense of
       the term.  */

And the "C sense" (C semantics) is that two restrict-qualified pointers 
cannot be aliases of the same object.  But a restricted pointer and a 
non-restricted pointer can still be aliases.  So iiuc the above check
should set differ_p to false unless ta and tb are both restrict qualified
(and they are nor the same object, but that's checked earlier).

Gr.
Steven