Re: [RFC] trailing_wide_ints with runtime variable lengths

[Jakub Jelinek <jakub@redhat.com>]

On Fri, Jul 01, 2022 at 06:47:48PM +0200, Aldy Hernandez wrote:
> > So, you are looking for something like trailing_wide_ints<N> but where that
> > N is actually a runtime value?  Then e.g. the
> >   struct {unsigned char len;} m_len[N];
> > member can't work properly either, because it isn't constant size.
> 
> What my patch does is store the run-time length in the aforementioned
> byte, while defaulting to N/MAX.  There is no size difference (or code
> changes) for existing users.  With my change, set_precision() and
> extra_size() now take a runtime parameter, but it defaults to N and is
> inlined, so there is no penalty for existing users.  I benchmarked to
> make sure :).

So, you still use N = 3 but can sometimes store say 255 wide_ints in there?
In that case, m_len[N] provides lengths just for the first 3, no?

Anyway, you really want feedback from Richard Sandiford IMHO...

	Jakub