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Re: RFA: Ada variable-sized objects, bit_size_type == TImode, and divti3
- From: Ulrich Weigand <weigand at immd1 dot informatik dot uni-erlangen dot de>
- To: rth at redhat dot com (Richard Henderson)
- Cc: weigand at immd1 dot informatik dot uni-erlangen dot de (Ulrich Weigand), gcc at gcc dot gnu dot org, uweigand at de dot ibm dot com
- Date: Fri, 21 Mar 2003 02:15:36 +0100 (MET)
- Subject: Re: RFA: Ada variable-sized objects, bit_size_type == TImode, and divti3
Richard Henderson wrote:
> On Thu, Mar 20, 2003 at 11:11:50PM +0100, Ulrich Weigand wrote:
> > Well, I guess I can find out why divti3 doesn't get built. However,
> > the IMO really interesting question is why TImode division should be
> > needed -- calling __divti3 just to make sure that a variable is 8-byte
> > aligned on the stack strikes me as seriously suboptimal ...
>
> Huh? We've computed its size, in bits. We need 67-bit
> arithmetic for this, technically. Not that I actually
> believe that someone is going to create a 2EB dynamically
> sized object...
Well, but we don't need the size in bits when computing stack
alignment. It should be possible to compute the size in bytes
without requiring 67-bit arithmetic ... I just find it weird
to require full-blown 128-bit arithmetic which is not actually
accessible to the user, and needed only at this place (where
it should be actually avoidable).
In any case, if that's the way it is, then so be it. ;-)
I'll just fix the MIN_UNITS_PER_WORD define to get 128-bit
libgcc2 routines built.
Thanks,
Ulrich
--
Dr. Ulrich Weigand
weigand at informatik dot uni-erlangen dot de