Re: [rfc] struct dictionary

Andrew Cagney
2003-04-29T20:06:05Z

> On Tue, 29 Apr 2003 11:10:05 -0400, Andrew Cagney <ac131313@redhat.com> said:
>
>
>>> On Fri, 25 Apr 2003 11:31:35 -0400, Andrew Cagney <ac131313@redhat.com> said:
>>>
>
>
>>>> Ok, humor me ...
>>>> http://sources.redhat.com/ml/gdb/2003-04/msg00017.html why even
>>>> build these data structures during symbol reading? It takes time
>>>> and space, yet is probably never used. Why not on-demand build this
>>>> dictionary specialized for the block?
>
>>> That sounds great to me if we can get it to work. It's certainly
>
>
>>> another reason to try to get the symbol lookup stuff abstracted behind
>>> an opaque interface: it makes lazy loading of data a lot easier.
>
>
>> But which interface?
>
>
>> A block has a language, and [I think] it's the language that, in the
>> end decides that block's name->symbol lookup strategy. The language
>> can, on demand, build a dictionary for its block.
>
>
> Currently, all uses of symbols in blocks either iterate over all
> symbols or else are looking for symbols with a given natural name. As
> you say, because of the features of certain languages, sometimes you
> need to refine the search further beyond that, but that's a good first
> cut. So having iterators dict_iterator_{first,next} and
> dict_iter_name_{first,next} is a good first step: it unifies all the
> existing mechanisms for symbol lookup, but doesn't commit to any sort
> of implementation mechanism. It certainly would allow for
> constructing the actual data structures on demand: for example, we
> could add an implementation that doesn't actually build the data
> structures storing the symbols until the first time that an iterator
> is called.
>
> I'm certainly willing to believe that the interface might change in
> the future; but separating the interface from the implementation is a
> good first step no matter what.
>
> I kind of get the impression that I'm missing your point somehow and
> that we're talking past each other. I'll post a concrete patch soon
> (Wednesday, maybe? It's done on my laptop, but I don't have my laptop
> with me), and hopefully that will clarify matters.

Sounds like it. I'm think I'm looking a step beyond your changes.

Is the block's symbol search algorithm determined by the language? I
believe it is, and hence it should be language specific code that
constructs the blocks dictionary? Of course it could also be
implemented on-demand.

I think that would allow much C++ junk to be kicked out of the current
symbol table readers. Instead they just read in simple lists of symbols
in blocks.

Andrew