Hi Kewen,
On Wed, Jun 19, 2019 at 07:47:34PM +0800, Kewen.Lin wrote:
> +/* Return true if count register for branch is supported. */
> +
> +static bool
> +rs6000_have_count_reg_decr_p ()
> +{
> + return flag_branch_on_count_reg;
> +}
rs6000 unconditionally supports these instructions, not just when that
flag is set. If you need to look at the flag, the *caller* of this new
hook should, not every implementation of the hook. So just "return true"
here?
> DEFHOOK
> +(have_count_reg_decr_p,
> + "Return true if the target supports hardware count register for decrement\n\
> +and branch.\n\
> +The default version of this hook returns false.",
> + bool, (void),
> + hook_bool_void_false)
Is it important here that you cannot use that register as a GPR, that any
use of it is expensive because it has to be moved to/from a GPR? The doc
should say something like that; a little more context, what the hook is
meant to be used for.
> +/* For doloop use, if the algothrim selects some candidate which invalid for
> + later rewrite, fix it up with bind_cand. */
"algorithm", "which is invalid".
> +/* Find doloop comparison use and set its related bind_cand. We adjust the
> + doloop use group cost against various IV cands, it's possible to assign
> + some cost like zero rather than original inifite cost. The point is to
"infinite"
Looks good :-)
Segher
