From: Paul Eggert <eggert@cs.ucla.edu>
To: Dmitry Antipov <dmantipov@yandex.ru>
Cc: Emacs development discussions <emacs-devel@gnu.org>
Subject: Re: Benchmarking temporary Lisp objects [Was: Re: [RFC] temporary Lisp_Strings]
Date: Wed, 03 Sep 2014 23:45:18 -0700 [thread overview]
Message-ID: <54080A7E.8080008@cs.ucla.edu> (raw)
In-Reply-To: <5407FDF4.7020504@yandex.ru>
Dmitry Antipov wrote:
> I'm talking about the case when we can't us __attribute__ ((aligned (X))).
How about something like this?
typedef unsigned long uintptr_t;
typedef uintptr_t Lisp_Object;
struct Lisp_Cons
{
Lisp_Object car;
Lisp_Object cdr;
};
static Lisp_Object
cons_init (void *result, Lisp_Object a, Lisp_Object b)
{
struct Lisp_Cons *p = (struct Lisp_Cons *) (((uintptr_t) result + 7)
& -8);
p->car = a;
p->cdr = b;
return (Lisp_Object) p + 3;
}
#define BCONS(a, b) cons_init ((char[sizeof (struct Lisp_Cons) + 7]){},
a, b)
#define untag(x) ((struct Lisp_Cons *) (uintptr_t) ((x) - 3))
int
foo (void)
{
Lisp_Object a = BCONS (0, 0);
Lisp_Object b = BCONS (0, a);
return untag (untag(b) -> cdr) -> car;
}
next prev parent reply other threads:[~2014-09-04 6:45 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-02 12:55 [RFC] temporary Lisp_Strings Dmitry Antipov
2014-09-02 13:21 ` Andreas Schwab
2014-09-02 13:47 ` Dmitry Antipov
2014-09-02 14:14 ` Andreas Schwab
2014-09-02 15:00 ` Eli Zaretskii
2014-09-02 14:00 ` Stefan Monnier
2014-09-02 15:13 ` Dmitry Antipov
2014-09-02 17:32 ` Stefan Monnier
2014-09-03 10:23 ` Benchmarking temporary Lisp objects [Was: Re: [RFC] temporary Lisp_Strings] Dmitry Antipov
2014-09-03 13:14 ` Stefan Monnier
2014-09-03 14:39 ` Paul Eggert
2014-09-03 15:39 ` Dmitry Antipov
2014-09-03 16:42 ` Paul Eggert
2014-09-03 17:47 ` Stefan Monnier
2014-09-03 18:00 ` Paul Eggert
2014-09-04 4:59 ` Dmitry Antipov
2014-09-04 5:13 ` Paul Eggert
2014-09-04 5:51 ` Dmitry Antipov
2014-09-04 6:45 ` Paul Eggert [this message]
2014-09-04 13:11 ` Stefan Monnier
2014-09-04 13:37 ` Dmitry Antipov
2014-09-04 14:46 ` Dmitry Antipov
2014-09-04 16:03 ` Paul Eggert
2014-09-05 4:00 ` Dmitry Antipov
2014-09-05 4:24 ` Stefan Monnier
2014-09-05 9:28 ` Dmitry Antipov
2014-09-05 7:15 ` Paul Eggert
2014-09-05 9:16 ` Dmitry Antipov
2014-09-05 14:35 ` Paul Eggert
2014-09-05 15:35 ` Stefan Monnier
2014-09-08 10:33 ` Dmitry Antipov
2014-09-08 12:01 ` Dmitry Antipov
2014-09-08 13:30 ` Stefan Monnier
2014-09-08 12:44 ` Stefan Monnier
2014-09-08 13:30 ` Stefan Monnier
2014-09-02 14:37 ` [RFC] temporary Lisp_Strings Paul Eggert
2014-09-02 15:24 ` Dmitry Antipov
2014-09-02 15:28 ` Dmitry Antipov
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