From: Dmitry Antipov <dmantipov@yandex.ru>
To: Paul Eggert <eggert@cs.ucla.edu>
Cc: Stefan Monnier <monnier@IRO.UMontreal.CA>,
Emacs development discussions <emacs-devel@gnu.org>
Subject: Re: Benchmarking temporary Lisp objects [Was: Re: [RFC] temporary Lisp_Strings]
Date: Fri, 05 Sep 2014 13:16:21 +0400 [thread overview]
Message-ID: <54097F65.5030906@yandex.ru> (raw)
In-Reply-To: <5409630B.6030201@cs.ucla.edu>
On 09/05/2014 11:15 AM, Paul Eggert wrote:
> I like the idea of simpler and cleaner, but your patch's implementations of
> build_local_vector and build_local_string use alloca expressions as function
> arguments
I don't do that - I'm using 1st arg (result) as a temporary variable,
assuming that Lisp_Object is always wide enough to hold an address:
#define build_local_vector(obj, size, init) \
(MAX_ALLOCA < (size) * word_size + header_size \
? obj = Fmake_vector (make_number (size), (init)) \
: (obj = XIL ((uintptr_t) alloca \ here
((size) * word_size + header_size)), \
obj = local_vector_init ((uintptr_t) XLI (obj), (size), (init))))
IIUC the compiler should know about alloca limitations and so should not
try to (mis)optimize the code above to:
#define build_local_vector(obj, size, init) \
(MAX_ALLOCA < (size) * word_size + header_size \
? obj = Fmake_vector (make_number (size), (init)) \
obj = local_vector_init \
((uintptr_t) alloca ((size) * word_size + header_size), \
(size), (init)))
Dmitry
next prev parent reply other threads:[~2014-09-05 9:16 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
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 [this message]
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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