RFD: hookizing BITS_PER_UNIT in tree optimizers / frontends

[Richard Guenther]

On Wed, Nov 24, 2010 at 3:33 PM, Diego Novillo <dnovillo@google.com> wrote:
> On Wed, Nov 24, 2010 at 09:17, Richard Guenther
> <richard.guenther@gmail.com> wrote:
>
>> And we don't want to pay the overhead of hookization every target
>> dependent constant just for the odd guys who want multi-target
>> compilers that have those constants differing.
>
> I would like to know how much this overhead really amounts to.  Long
> term, I would like to see back ends become shared objects that can be
> selected with a -fbackend=... flag or some such.  Removing
> configure/compile-time macros and other hardwired data is instrumental
> to that.

Well.  Long term.  Hookizing constants is easy - before proceeding
with those (seemingly expensive) ones I'd like to see all the _hard_
target macros converted into hooks.  If there are only things like
BITS_PER_UNIT left we can talk again.

Richard.

>
> Diego.
>