Re: Add VIEW_CONVERT_EXPR to operand_equal_p

[Richard Biener <richard.guenther@gmail.com>]

On Wed, Oct 14, 2015 at 6:29 PM, Jan Hubicka <hubicka@ucw.cz> wrote:
> Hi,
> this patch adds VIEW_CONVERT_EXPR which is another code omitted in
> operand_equal_p.  During bootstrap there are about 1000 matches.
>
> Bootstrapped/regtested x86_64-linux, OK?

Eric, does that look ok WRT TYPE_ALIGN_OK?  (that is, did we decide
TYPE_ALIGN_OK is no longer needed?)

> Honza
>
>         * fold-const.c (operand_equal_p): Handle VIEW_CONVERT_EXPR.
> Index: fold-const.c
> ===================================================================
> --- fold-const.c        (revision 228735)
> +++ fold-const.c        (working copy)
> @@ -2962,6 +2968,12 @@ operand_equal_p (const_tree arg0, const_
>         case IMAGPART_EXPR:
>           return OP_SAME (0);
>
> +       case VIEW_CONVERT_EXPR:
> +         if (!(flags & (OEP_ADDRESS_OF | OEP_CONSTANT_ADDRESS_OF))
> +             && !types_compatible_p (TREE_TYPE (arg0), TREE_TYPE (arg1)))

Note that mixing the GIMPLE types_compatible_p into operand_equal_p which
is supposed to handle GENERIC as well looks dangerous.  You short-cutted
the type checks for OEP_ADDRESS_OF earlier so why do you need to
preserve them here?

The test looks bogus anyway, but maybe it's just too early in the morning ;)
Shouldn't it be && types_compatible_p (...) (instead of && !types_com...)?
Otherwise it looks really weird.

Richard.

> +           return false;
> +         return OP_SAME (0);
> +
>         case TARGET_MEM_REF:
>         case MEM_REF:
>           if (!(flags & (OEP_ADDRESS_OF | OEP_CONSTANT_ADDRESS_OF)))