From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
 id 146303894C18; Thu, 11 Mar 2021 23:35:53 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 146303894C18
From: "unlvsur at live dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/99548] Help me! Lost the fight against the compiler.
Date: Thu, 11 Mar 2021 23:35:52 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: target
X-Bugzilla-Version: 11.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: unlvsur at live dot com
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-99548-4-MrIIs992iR@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-99548-4@http.gcc.gnu.org/bugzilla/>
References: <bug-99548-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-BeenThere: gcc-bugs@gcc.gnu.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Gcc-bugs mailing list <gcc-bugs.gcc.gnu.org>
List-Unsubscribe: <https://gcc.gnu.org/mailman/options/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=unsubscribe>
List-Archive: <https://gcc.gnu.org/pipermail/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-request@gcc.gnu.org?subject=help>
List-Subscribe: <https://gcc.gnu.org/mailman/listinfo/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Thu, 11 Mar 2021 23:35:53 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99548

--- Comment #2 from cqwrteur <unlvsur at live dot com> ---
(In reply to Andrew Pinski from comment #1)
> For aarch64 we get:
>         ldp     x4, x3, [x1]
>         mov     x7, 38
>         ldp     x6, x5, [x2]
>         ldr     x8, [x1, 16]
>         add     x6, x4, x6
>         cmp     x4, x6
>         adc     x5, x3, x5
>         cmp     x3, x5
>         ldr     x3, [x1, 24]
>         ldp     x4, x1, [x2, 16]
>         adc     x4, x8, x4
>         cmp     x8, x4
>         adc     x1, x3, x1
>         cmp     x3, x1
>         csetm   x2, cs
>         and     x2, x2, x7
>         add     x2, x2, x6
>         cmp     x2, x6
>         cinc    x6, x5, ls
>         cmp     x6, x5
>         cinc    x5, x4, ls
>         cmp     x5, x4
>         cinc    x3, x1, ls
>         cmp     x3, x1
>         csetm   x1, ls
>         and     x1, x1, x7
>         add     x1, x1, x2
>         str     x1, [x0]
>         cmp     x1, x2
>         cinc    x1, x6, ls
>         str     x1, [x0, 8]
>         cmp     x1, x6
>         cinc    x1, x5, ls
>         cmp     x1, x5
>         cinc    x3, x3, ls
>         stp     x1, x3, [x0, 16]
>         ret
> There is only one missing optimization there really:
>         csetm   x1, ls
>         and     x1, x1, x7
> Should be turned into:
> csel x1, x7, xzw, ls
> Which is repeated a few times.
>=20
> It looks like x86_64 has other issues.

my add carry implementation for none-x86_64 platforms is wrong on godbolt.=