Re: [RFC] Contributing tree-ssa to mainline

[Robert Dewar <dewar at gnat dot com>]

law@redhat.com wrote:
> In message <10401170230.AA15232@vlsi1.ultra.nyu.edu>, Richard Kenner writes:

> Given the lack of movement on that front, how can we realistically expect
> any movement on something like tree-ssa?  Particularly when tree-ssa
> depends on function at a time mode?
>
> Given the lack of movement from the Ada maintainers on that front, can we
> realistically consider the Ada front-end even maintained, except perhaps
> in a bugfix mode?

Well in practice there is a huge amount of development on the Ada front
end, probably as much or more than any other gcc front end. It is really
a question of priorities. We don't have any Ada users for whom function
at a time is an important issue, where as there are a heap of other
important and urgent enhancements. So that tends to make function at a 
time non-urgent, even if of course important in the long run. Even in
the area of performance, for Ada users concerned with code quality, the
important issues are not in general optimization of the back end, but
rather Ada specific issues (e.g. efficient handling of multi-dimensional
packed arrays).

I agree with Richard, it is not that serious a problem if there is a lag
and Ada is unavailable for a while. That unavailability would in fact 
obviously create an increased urgency for getting function at a time to
work for Ada. After all, for years, GNAT users were successfully using
GCC 2.8 and it took quite a long time to get GNAT working with GCC 3.
We are now over that bump, and no doubt function at a time will be
achieved relatively soon. We can't commit a definite schedule (since
projects urgently needed by (and funded by) our customers will take
priority and can preempt non-funded projects, but that does not mean
that the non-funded projects don't eventually get done.

If the arguments for including tree-ssa are strong enough, my viewpoint 
would be that there is no need to let Ada be a blocking issue.