Re: [RFC] Proposed changes in symbol-handling for Ada

Daniel Jacobowitz
2004-01-21T15:19:20Z

On Wed, Jan 21, 2004 at 05:55:10AM -0500, Paul Hilfinger wrote:
>
> > Rather than demangling at startup, we ask each mangled name for a base
> > identifier. This can be done reasonably efficiently - I hope - I
> > haven't performed measurements yet. Then, when we search for a symbol,
> > we wildcard for the basename. We demangle everything with that
> > basename. If you do a search that doesn't know the basename you
> > have to un-lazy all symbols, of course, but I don't think that's much
> > of a change.
>
> Daniel,
>
> At first blush, this sounds like a great idea (at least until someone
> introduces a mangling scheme in which the basename is not a
> substring). The basename situation for Ada is essentially the same as you
> describe for C++.
>
> As you may know, the current Ada lookup machinery is separate from (and
> partially duplicative of) the usual lookup machinery. There are two
> reasons for this:
>
> 1. We actually WANT to be able to match on base name alone if the user
> supplies just a base name.
>
> 2. We don't include parameter types in mangled names: instead, our
> basic lookup routine returns a list of all matches, from which we select
> by parameter type or, if that doesn't work, by giving the user a choice.
>
> 3. Three; there are three reasons: we don't store demangled names.
>
> So, your proposal takes care of 3. If we could persuade you to
>
> A. Provide a mode in which you search for the base name (i.e, return
> the results of your preliminary sift for base names, skipping the
> comparison against full demangled name), and
>
> B. Provide a mode in which you return ALL matches for a name.
>
> ... why we could clean up all that nasty duplication in the ada-* files and
> join the civilized world.

OK. (B) has always been on my todo list; C++ would benefit from it
also. (A) will require increasing the size of the symbol (because
I had been planning to overlap the basename information with the
demangled name information using a union, and store the two sets
separately), but I think it's worthwhile.

No promises on timeline, since I'm working on several other projects
right now, but I'll try to pull this together.

--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer