From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-405284-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 30591 invoked by alias); 31 Oct 2012 13:47:46 -0000
Received: (qmail 30124 invoked by uid 48); 31 Oct 2012 13:47:11 -0000
From: "olegendo at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/49263] SH Target: underutilized "TST #imm, R0" instruction
Date: Wed, 31 Oct 2012 13:47:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: target
X-Bugzilla-Keywords:
X-Bugzilla-Severity: enhancement
X-Bugzilla-Who: olegendo at gcc dot gnu.org
X-Bugzilla-Status: REOPENED
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: olegendo at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Changed-Fields:
Message-ID: <bug-49263-4-nHtXHuatDa@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-49263-4@http.gcc.gnu.org/bugzilla/>
References: <bug-49263-4@http.gcc.gnu.org/bugzilla/>
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
Content-Type: text/plain; charset="UTF-8"
MIME-Version: 1.0
Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-bugs.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-help@gcc.gnu.org>
Sender: gcc-bugs-owner@gcc.gnu.org
X-SW-Source: 2012-10/txt/msg02960.txt.bz2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49263

--- Comment #20 from Oleg Endo <olegendo at gcc dot gnu.org> 2012-10-31 13:47:07 UTC ---
(In reply to comment #19)
> Another thing I've noticed...
> Cases such as:
> 
>         mov.l   r0,@r2        ! LS
>         mov     r13,r0        ! MT
>         and     #7,r0         ! EX
>         tst     r0,r0         ! MT
>         bt/s    .L8           ! BR
>         mov.l   r0,@(16,r1)
> 
> where the result of the and op is re-used would be slightly better as:
> 
>         mov.l   r0,@r2       ! LS
>         mov     r13,r0       ! MT
>         tst     #7,r0        ! MT
>         and     #7,r0        ! EX
>         bt/s    .L8          ! BR
>         mov.l   r0,@(16,r1)
> 
> because it reduces dependency on the result of the and op and thus has a higher
> chance to be executed in parallel.

Other similar cases where hoisting the tst insn would make sense:
        mov.b   @(13,r2),r0
        extu.b  r0,r0
        tst     #1,r0
        bt      .L53

        mov.b   @(13,r1),r0
        extu.b  r0,r0
        tst     r0,r0
        bt/s    .L37