From: Dmitry Antipov <antipov@mvista.com>
To: emacs-devel@gnu.org
Cc: Paul Eggert <eggert@cs.ucla.edu>,
Stefan Monnier <monnier@IRO.UMontreal.CA>
Subject: Re: immediate strings #2
Date: Wed, 30 Nov 2011 09:37:01 +0400 [thread overview]
Message-ID: <4ED5C0FD.8030301@yandex.ru> (raw)
In-Reply-To: <4ED49CC9.6080808@cs.ucla.edu>
On 11/29/2011 12:50 PM, Paul Eggert wrote:
> There is a bit available in size (since it's always nonnegative)
> but not in size_byte (since it ranges from -1 .. PTRDIFF_MAX
> and is a ptrdiff_t, assuming a 32-bit host configured --with-wide-int
> and assuming the memory-saving patch of Bug#9874).
>
> This is in contrast with our current uses of mark bits (e.g.,
> ARRAY_MARK_FLAG), which use bits that are otherwise unused, even if
> a vector has its maximal size.
>
> We can fairly easily get that bit back from size_byte by restricting
> its range to (say) 0 .. PTRDIFF_MAX.
>
> So this is a fairly minor glitch that can be fixed but is not yet
> fixed in the current proposal.
It looks like I miss the point. For an immediate strings, we need
two extra bits - 1 for GC, 1 for string subtype, so the question is
simple: where to get them if both size and size_byte are ptrdiff_t?
Dmitry
next prev parent reply other threads:[~2011-11-30 5:37 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-28 9:11 immediate strings #2 Dmitry Antipov
2011-11-28 17:33 ` Stefan Monnier
2011-11-28 19:48 ` Ken Raeburn
2011-11-28 20:10 ` Andreas Schwab
2011-11-28 21:54 ` Stefan Monnier
2011-11-28 22:25 ` Andreas Schwab
2011-11-29 0:57 ` Ken Raeburn
2011-11-29 8:44 ` Andreas Schwab
2011-11-29 15:48 ` Ken Raeburn
2011-11-29 16:08 ` Andreas Schwab
2011-11-30 16:43 ` Ken Raeburn
2011-11-28 22:18 ` Paul Eggert
2011-11-29 2:07 ` Stefan Monnier
2011-11-29 3:37 ` Dmitry Antipov
2011-11-29 8:50 ` Paul Eggert
2011-11-30 5:37 ` Dmitry Antipov [this message]
2011-11-30 9:35 ` Paul Eggert
2011-11-30 16:43 ` Ken Raeburn
2011-11-30 21:44 ` Paul Eggert
2011-11-29 3:17 ` Dmitry Antipov
2011-11-29 5:29 ` Dmitry Antipov
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