On Wed, 2012-06-20 at 11:52 -0700, Richard Henderson wrote:
> On 06/20/2012 04:11 AM, Richard Guenther wrote:
> > I notice (with all of these functions)
> >
> > +unsigned
> > +negate_cost (enum machine_mode mode, bool speed)
> > +{
> > + static unsigned costs[NUM_MACHINE_MODES];
> > + rtx seq;
> > + unsigned cost;
> > +
> > + if (costs[mode])
> > + return costs[mode];
> > +
> > + start_sequence ();
> > + force_operand (gen_rtx_fmt_e (NEG, mode,
> > + gen_raw_REG (mode, LAST_VIRTUAL_REGISTER + 1)),
> > + NULL_RTX);
>
> I don't suppose there's any way to share data with what init_expmed computes?
>
> Not, strictly speaking, the cleanest thing to include expmed.h here, but
> surely
> a tad better than re-computing identical data (and without the clever rtl
> garbage avoidance tricks).
Interesting. I was building on what ivopts already has; not sure of the
history there. It looks like there is some overlap in function, but
expmed doesn't have everything ivopts uses today (particularly the hash
table of costs for multiplies by various constants). The stuff I need
for type promotion/demotion is also not present (which I'm computing on
demand for whatever mode pairs are encountered). Not sure how great it
would be to precompute that for all pairs, and obviously precomputing
costs of multiplying by all constants isn't going to work. So if the
two functionalities were to be combined, it would seem to require some
modification to how expmed works.
Thanks,
Bill
>
>
> r~
>
