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Message-ID: <3ae43538e724dcbcd2a8cad2ac8248b73e17f7c7.camel@t-online.de>
Subject: Re: AW: optimizer discards sign information
From: Oleg Endo <oleg.endo@t-online.de>
To: Stefan Franke <stefan@franke.ms>, gcc-help@gcc.gnu.org
Date: Thu, 11 Apr 2024 09:32:22 +0900
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On Wed, 2024-04-10 at 16:25 +0200, Stefan Franke wrote:
>=20
> Thank you for the detailed explanation.
> It still doesn't fit together, since if the compiler knows that it's unsi=
gned, why does it emit code for sign extension on the m68k target?
>=20
> Well. Since there are enough explanations and my expectations are simply =
wrong consider this as closed.
>=20
>=20

By the way, on targets that can do widening multiplication the sign
extensions are omitted.  E.g. on SH -- https://godbolt.org/z/7hr4njEx8

_foo:
        mulu.w  r4,r5
        sts     macl,r1
        sts     macl,r0
        shll    r1
        rts    =20
        subc    r1,r1


Best regards,
Oleg Endo