Re: new demangler

[Ian Lance Taylor <ian@wasabisystems.com>]

Jim Blandy <jimb@redhat.com> writes:

> Daniel Jacobowitz <drow@mvista.com> writes:
> > When I can figure out a few more points of C++ grammar - it's taken me
> > a *(!&#@ month so far and it's barely functional... - I'll have an
> > efficient solution for breaking down names into the demangler's trees. 
> > This will let us get the information we want much more reliably.
> 
> When working on big C++ programs, I think I remember seeing that the
> mangled and demangled names take up a *lot* of memory.
> 
> If that recollection is correct, it might be cool to have GDB store
> the trees instead of the names, and throw a bcache at the nodes in
> these demangled name trees, working from the leaves upward, to get
> maximum sharing.  I bet that would bring the memory requirements down
> to something more closely resembling the actual number of classes,
> methods, etc. in the program.
> 
> I think the trees would be a lot easier to do certain kinds of
> matching on, too.  "Is this a user-defined cast operator?"

Tangentially, note that the trees that I wrote for the demangler are
based pretty directly on the mangling ABI.  They just follow the
grammar productions used there.

To use them for anything other than demangling, it might be useful to
try to work out a good tree representation for C++ names.  Then I or
somebody can modify the demangler to use that tree representation
instead.  It would probably be pretty close to the trees I use, but I
doubt it would be identical.

Ian