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From: Andy Wingo <wingo@pobox.com>
To: Mark H Weaver <mhw@netris.org>
Cc: guile-devel <guile-devel@gnu.org>
Subject: Re: rtl metadata musings
Date: Sun, 12 May 2013 23:20:33 +0200	[thread overview]
Message-ID: <87obcfopy6.fsf@pobox.com> (raw)
In-Reply-To: <87wqr63yvt.fsf@tines.lan> (Mark H. Weaver's message of "Sat, 11 May 2013 00:48:38 -0400")

On Sat 11 May 2013 06:48, Mark H Weaver <mhw@netris.org> writes:

> I have only one comment for now, which regards arity information.  The
> required/optional/rest representation is not sufficiently general.  Not
> only is it unable to handle empty case-lambdas, but it's also unable to
> properly represent a case-lambda that can accept 1 or 3 arguments, but
> not 2.

I did think about this and I think I just didn't express myself well.  I
said:

      struct guile_arity {
        Elf_Addr pc;
        Elf_Off size;
        nreq; // encodings for these not determined yet
        nopt;
        flags; // has-keyword-args, has-rest, is-case-lambda
        Elf_Offset offset;
      }

    An entry describes how many required, optional, keyword, and rest
    arguments a function has.  The .guile.arities section is prefixed by a
    length indicating how many entries there are, then all the arity
    structures, sorted by pc.  Note that one arity may contain another!  In
    particular for case-lambda clauses you can have one arity for the whole
    function, then a number of other ones for the cases.

The case-lambda as a whole would get the is-case-lambda flag.  The
arities of the clauses would follow and have their [pc*, pc*+size*]
within the [pc, pc+size] of the case-lambda entry.

I don't know whether to use the nreq/nopt/flags of the "outer" arity for
any purpose or not.

Cheers,

Andy
-- 
http://wingolog.org/



  reply	other threads:[~2013-05-12 21:20 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-05-10  5:07 rtl metadata musings Andy Wingo
2013-05-11  4:48 ` Mark H Weaver
2013-05-12 21:20   ` Andy Wingo [this message]
2013-05-16 21:42 ` Andy Wingo
2013-05-19 21:52 ` Ludovic Courtès
2013-05-20 14:23   ` Andy Wingo
2013-05-20 16:37     ` Ludovic Courtès
2013-05-20 16:48       ` Mike Gran
2013-05-20 18:29       ` Andy Wingo
2013-05-20 19:28         ` Ludovic Courtès
2013-05-20 20:24           ` Andy Wingo

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