From: "Jₑₙₛ Gustedt" <jens.gustedt@inria.fr>
To: Alexander Monakov <amonakov@ispras.ru>
Cc: musl@lists.openwall.com
Subject: Re: [musl] [C23 128 bit 4/4] C23: implement proper support for int128_t and uint128_t
Date: Thu, 1 Jun 2023 09:24:13 +0200 [thread overview]
Message-ID: <20230601092413.6679c6a6@inria.fr> (raw)
In-Reply-To: <45274206-ca94-2c12-c8e9-7e5d5991fa20@ispras.ru>
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Alexander,
on Wed, 31 May 2023 20:09:29 +0300 (MSK) you (Alexander Monakov
<amonakov@ispras.ru>) wrote:
> On Wed, 31 May 2023, Jens Gustedt wrote:
>
> > So what? On the arch where it exist, it is used and useful. (And I
> > also think that implementations improved over the state from 20
> > years ago that you describe.)
>
> Sorry, I'm not sure what you meant in the parenthetical statement.
> Improved in what sense?
In the sense that depending on your -march=xxx settings they use all
low level operations that are available. IIRC, bit operation support
is e.g already quite good on most current x86_64, there is
specialization for multiplying or dividing a 128 bit integer with/by a
64 bit integer, and when I did these patches I have seen that division
by a small constant is quite good.
The composition of 64 bit operations is still used as a fallback where
no such native processor support is available, though.
Jₑₙₛ
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next prev parent reply other threads:[~2023-06-01 7:24 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-31 14:15 [musl] [C23 128 bit 0/4] implement the library part of 128 bit support Jens Gustedt
2023-05-31 14:15 ` [musl] [C23 128 bit 1/4] add an emulation for 128 bit arithmetic as needed for C library support Jens Gustedt
2023-05-31 14:15 ` [musl] [C23 128 bit 2/4] C23: implement w128 and wf128 support for printf Jens Gustedt
2023-05-31 14:15 ` [musl] [C23 128 bit 3/4] C23: implement w128 and wf128 for scanf and similar Jens Gustedt
2023-05-31 14:15 ` [musl] [C23 128 bit 4/4] C23: implement proper support for int128_t and uint128_t Jens Gustedt
2023-05-31 14:27 ` Rich Felker
2023-05-31 14:29 ` Rich Felker
2023-05-31 14:36 ` Jₑₙₛ Gustedt
2023-05-31 14:41 ` Rich Felker
2023-05-31 14:55 ` Jₑₙₛ Gustedt
2023-05-31 14:57 ` Rich Felker
2023-05-31 15:07 ` Jₑₙₛ Gustedt
2023-05-31 15:14 ` Rich Felker
2023-05-31 15:37 ` Jₑₙₛ Gustedt
2023-05-31 15:40 ` Rich Felker
2023-05-31 15:56 ` Jₑₙₛ Gustedt
2023-05-31 16:30 ` Alexander Monakov
2023-05-31 16:58 ` Jens Gustedt
2023-05-31 17:03 ` Rich Felker
2023-05-31 17:09 ` Alexander Monakov
2023-06-01 7:24 ` Jₑₙₛ Gustedt [this message]
2023-05-31 14:42 ` Jₑₙₛ Gustedt
2023-05-31 14:47 ` Rich Felker
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