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Subject: Re: [PATCH v3] sh: Use generic GCC library routines
From:   "D. Jeff Dionne" <djeffdionne@gmail.com>
In-Reply-To: <434fe02c2c774ae4d1694ff222884bc5d5fc25e6.camel@physik.fu-berlin.de>
Date:   Fri, 21 Apr 2023 20:16:06 +0900
Cc:     Geert Uytterhoeven <geert+renesas@glider.be>,
        Yoshinori Sato <ysato@users.sourceforge.jp>,
        Rich Felker <dalias@libc.org>,
        Palmer Dabbelt <palmer@rivosinc.com>,
        Linux-sh list <linux-sh@vger.kernel.org>,
        linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org
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Message-Id: <E21A1070-ABD7-4D33-90BF-AB44E584AE7F@gmail.com>
References: <74dbe68dc8e2ffb6180092f73723fe21ab692c7a.1679566500.git.geert+renesas@glider.be>
 <434fe02c2c774ae4d1694ff222884bc5d5fc25e6.camel@physik.fu-berlin.de>
To:     John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Precedence: bulk


> On Apr 21, 2023, at 20:03, John Paul Adrian Glaubitz =
<glaubitz@physik.fu-berlin.de> wrote:
>=20
> Hi Geert!
>=20
> On Thu, 2023-03-23 at 11:18 +0100, Geert Uytterhoeven wrote:
>> The C implementations of __ashldi3(), __ashrdi3__(), and __lshrdi3() =
in
>> arch/sh/lib/ are identical to the generic C implementations in lib/.
>> Reduce duplication by switching SH to the generic versions.
...
>=20
> Why are the single-precision (denoted as "si") variants not being =
replaced?
>=20
> Don't we have generic versions for these?

The SH arch versions of si variants are optimized assembler, which is =
pretty important=E2=80=A6 these are things like bit shifts.

Actually, it would be better to have the di variants be hand coded asm =
also=E2=80=A6 I=E2=80=99m not sure how much use the kernel makes of =
those, and I=E2=80=99ve not looked if there is a good source of =
optimized SH versions those with the right license.

J.

>=20
> Adrian
>=20
> --=20
> .''`.  John Paul Adrian Glaubitz
> : :' :  Debian Developer
> `. `'   Physicist
>  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913