[PATCH][RFC] Optimize type-punning union accesses to VIEW_CONVERT_EXPRs

[Richard Guenther]

On Thu, 28 Feb 2008, Andrew Pinski wrote:

> On Thu, Feb 28, 2008 at 8:40 AM, Richard Guenther <rguenther@suse.de> wrote:
> 
> >  +       /* For integral conversions with the same precision or pointer
> >  +        conversions use a NOP_EXPR instead.  */
> >  +       if ((INTEGRAL_TYPE_P (type) && INTEGRAL_TYPE_P (TREE_TYPE (op0))
> >  +          && TYPE_PRECISION (type) == TYPE_PRECISION (TREE_TYPE (op0)))
> >  +         || (POINTER_TYPE_P (type) && POINTER_TYPE_P (TREE_TYPE (op0))))
> >  +       return fold_convert (type, op0);
> 
> You need to check to make sure the MIN and MAX are the similar.  Ada
> uses VIEW_CONVERT_EXPR to convert between the limited range and the
> normal range variables so it does not confuse VRP.

At least at the moment we don't seem to make use of those ranges in
VRP, but you are right;  I'll add such check.

Richard.

-- 
Richard Guenther <rguenther@suse.de>
Novell / SUSE Labs
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