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From: "Ludovic Courtès" <ludo@gnu.org>
To: Maxime Devos <maximedevos@telenet.be>
Cc: guile-user@gnu.org,  guile-devel@gnu.org
Subject: Re: mmap for guile
Date: Thu, 21 Jul 2022 11:14:44 +0200	[thread overview]
Message-ID: <87ilnqn7y3.fsf@gnu.org> (raw)
In-Reply-To: <4c07ec35d773ecb8d4d7ea6687a4c11cd2a221b0.camel@telenet.be> (Maxime Devos's message of "Tue, 19 Jul 2022 15:20:56 +0200")

Hi,

Maxime Devos <maximedevos@telenet.be> skribis:

> Ludovic Courtès schreef op ma 04-07-2022 om 12:09 [+0200]:
>> I don’t think the optimizer makes any such assumption, except for
>> literal bytevectors.
>
> It _does_ assume that bytevector lengths don't change:

[...]

> As can be seen in the above output, it first determines
> the length of the bytevector and then compares it again the index
> (for the index check) and then actually reads th byte
> so it assumes that the length doesn't change in-between -- it's not an
> atomic operation!

Oh right.

> Even if it didn't, being able to assume bytevector lengths don't change
> is important for optimising code like (begin (bytevector-ref bv 9000) (bytevector-ref 8999) ...)),
> to optimise out many range checks, though I don't know if Guile currently
> does that.

Indeed.

Ludo’.



  reply	other threads:[~2022-07-21  9:14 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-26 15:37 mmap for guile Matt Wette
2022-06-26 16:21 ` Matt Wette
2022-06-26 17:06 ` Olivier Dion via Developers list for Guile, the GNU extensibility library
2022-06-26 18:11 ` Maxime Devos
2022-07-04 10:09   ` Ludovic Courtès
2022-07-04 13:14     ` Greg Troxel
2022-07-04 20:03       ` Ludovic Courtès
2022-07-05 12:49         ` Greg Troxel
2022-07-19 13:20     ` Maxime Devos
2022-07-21  9:14       ` Ludovic Courtès [this message]
2022-07-19 13:30     ` Maxime Devos
2022-07-19 13:34     ` Maxime Devos
2022-06-26 18:21 ` Maxime Devos

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