Re: Ada subtypes and base types

[Jeffrey A Law <law at redhat dot com>]

On Tue, 2006-03-21 at 18:13 +0100, Duncan Sands wrote:

> Is memory use a problem here?  VR_VARYING has the advantage of using
> a bit less memory.  On the other hand, I guess you could introduce the
> convention that VR_RANGE with null min/mae means to use TYPE_MIN/
> TYPE_MAX, or something along those lines.
Well, more than anything, I just don't think we really thought
about the issue of what the best representation would be in this
kind of case.

If I was to lean any particular direction I would tend to lean
towards exposing the range and removing VR_VARYING.  The net
result would be good consistency in the transformations within
VRP.  ie, we would not need to special case stuff like

VR_VARYING | ~[0, 0]  -> ~[0, 0]

SImilarly for typecasts and a variety of other stuff.

jeff


> 
> Ciao,
> 
> D.