On Thu, Jan 26, 2012 at 10:03 PM, Jakub Jelinek <ja...@redhat.com> wrote:
> Hi!
>
> When a VALUE contains already some constant location, it will be always
> preferable to expressing it by some other expression - const (or some
> similar reverse operation), so we just should point at adding the
> reverse_op.
>
> This fixes the testcase from the PR on mips64-linux, bootstrapped/regtested
> on x86_64-linux and i686-linux, ok for trunk?
Ok.
Thanks,
Richard.
> 2012-01-26 Jakub Jelinek <ja...@redhat.com>
>
> PR debug/52001
> * var-tracking.c (reverse_op): Don't add any reverse operation
> if V already has any constant locations.
>
> --- gcc/var-tracking.c.jj 2012-01-23 18:23:45.000000000 +0100
> +++ gcc/var-tracking.c 2012-01-26 16:37:20.110049563 +0100
> @@ -5298,6 +5298,7 @@ reverse_op (rtx val, const_rtx expr, rtx
> {
> rtx src, arg, ret;
> cselib_val *v;
> + struct elt_loc_list *l;
> enum rtx_code code;
>
> if (GET_CODE (expr) != SET)
> @@ -5333,6 +5334,14 @@ reverse_op (rtx val, const_rtx expr, rtx
> if (!v || !cselib_preserved_value_p (v))
> return;
>
> + /* Adding a reverse op isn't useful if V already has an always valid
> + location. Ignore ENTRY_VALUE, while it is always constant, we should
> + prefer non-ENTRY_VALUE locations whenever possible. */
> + for (l = v->locs; l; l = l->next)
> + if (CONSTANT_P (l->loc)
> + && (GET_CODE (l->loc) != CONST || !references_value_p (l->loc, 0)))
> + return;
> +
> switch (GET_CODE (src))
> {
> case NOT:
>
> Jakub
