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 879643861800; Sat, 26 Jun 2021 16:14:57 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 879643861800
From: "maxsamukha at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug d/101226] New: Suboptimal codegen for >>/>>>
Date: Sat, 26 Jun 2021 16:14:57 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: d
X-Bugzilla-Version: 11.1.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: maxsamukha at gmail dot com
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: ibuclaw at gdcproject dot org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: bug_id short_desc product version bug_status
 bug_severity priority component assigned_to reporter target_milestone
 cf_gcctarget
Message-ID: <bug-101226-4@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: Sat, 26 Jun 2021 16:14:57 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D101226

            Bug ID: 101226
           Summary: Suboptimal codegen for >>/>>>
           Product: gcc
           Version: 11.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: d
          Assignee: ibuclaw at gdcproject dot org
          Reporter: maxsamukha at gmail dot com
  Target Milestone: ---
            Target: AVR

example.d:

void f1()
{
    __gshared ubyte value;
    value >>>=3D 5;
}

void f2()
{
    __gshared ubyte value;
    value =3D value >>> 5;
}

----
avr-gcc -fno-druntime -O3 example.d:

example.f1():
        lds r24,example.f1().value
        swap r24
        lsr r24
        andi r24,lo8(7)
        sts example.f1().value,r24
        ret
example.f2():
        lds r24,example.f2().value
        ldi r25,0
        ldi r27,0
        ldi r26,0
        ldi r18,5
        1:
        lsr r27
        ror r26
        ror r25
        ror r24
        dec r18
        brne 1b
        sts example.f2().value,r24
        ret

The compiler apparently fails to optimize out the integer promotion for >>>=
 in
f2 and produces inefficient machine code.=