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 46DF3383F84D; Tue, 12 May 2020 11:34:33 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 46DF3383F84D
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
 s=default; t=1589283273;
 bh=V7/LYBlxDqT1KHbWT9e0VqHV7epsfk0Sh+GSwVsA2JE=;
 h=From:To:Subject:Date:In-Reply-To:References:From;
 b=vGpgGtwNPZS/Z0sOkYJSctaJJB3U7Tg4BaGRJSx0YfijIyaV+b8UsBeqOIO5EQKA0
 6aqJtDxPyoZ9u63MJ/MroKVYFCqCWJBL6SvFKtkUtRjUf0m2xZ9l8/KhYSUEHpJNBN
 YzlglIU5h33zHAb9WtRsvZ8+aiE1U22UkN3S/zkY=
From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/95078] Missing fwprop for SIB address
Date: Tue, 12 May 2020 11:34:33 +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: rguenth at gcc dot gnu.org
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-95078-4-PUrN5JeSYj@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-95078-4@http.gcc.gnu.org/bugzilla/>
References: <bug-95078-4@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: <http://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: <http://gcc.gnu.org/mailman/listinfo/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Tue, 12 May 2020 11:34:33 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95078

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
TER should go away, not be extended.  So you are suggesting that we replace

        leaq    44(%rdi,%rdx,4), %rdx  --- redundant could be fwprop
        movl    (%rdx), %eax
        movl    $3, (%rsi)
        addl    (%rdx), %eax

with

        movl   44(%rdi,%rdx,4), %eax
        movl    $3, (%rsi)
        addl   44(%rdi,%rdx,4), %eax

?  The variant that looks bigger is actually one byte smaller.  Note as
soon as there are three uses it will be larger again...

So this is really something for RTL and yeah, fwprop only makes "local"
decisions.  Note that I think that your proposed variant will consume
more resources since the complex addressing modes are likely split into
a separate uop.  Yes, overall I'd expect less latency for your sequence.=