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 DF6B5385803F; Tue,  6 Sep 2022 22:04:43 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org DF6B5385803F
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1662501883;
	bh=5Ywrd2lQaoKT8C0FHcdUgLHVEEu38j5pKyDTLQGsOC8=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=l/V5uPL3QHPc98pPk/+tEQs37VLQLjTmqfKybYtXQQx+wl8J/dqahz7jMKBCH2sSF
	 mWiOLD0xAGz+1XuufeRU8jaU7trmS2jLuJvKqCMBiwWt+qzz/lLqsQbGMiwaVS7TVz
	 fw1E02136PnUie3J6HIfXA/5dn0FmRXA5RxXKlaI=
From: "pobrn at protonmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/104151] [10/11/12/13 Regression] x86: excessive code
 generated for 128-bit byteswap
Date: Tue, 06 Sep 2022 22:04:42 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: middle-end
X-Bugzilla-Version: 12.0
X-Bugzilla-Keywords: missed-optimization
X-Bugzilla-Severity: normal
X-Bugzilla-Who: pobrn at protonmail dot com
X-Bugzilla-Status: NEW
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P2
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 12.3
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: cc
Message-ID: <bug-104151-4-uUYjslMAer@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-104151-4@http.gcc.gnu.org/bugzilla/>
References: <bug-104151-4@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
List-Id: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104151

Barnab=C3=A1s P=C5=91cze <pobrn at protonmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pobrn at protonmail dot com

--- Comment #15 from Barnab=C3=A1s P=C5=91cze <pobrn at protonmail dot com>=
 ---
Sorry, I haven't found a better issue. But I think the example below exhibi=
ts
the same or a very similar issue.

I would expect the following code

void f(unsigned char *p, std::uint32_t x, std::uint32_t y)
{
    p[0] =3D x >> 24;
    p[1] =3D x >> 16;
    p[2] =3D x >>  8;
    p[3] =3D x >>  0;

    p[4] =3D y >> 24;
    p[5] =3D y >> 16;
    p[6] =3D y >>  8;
    p[7] =3D y >>  0;
}

to be compiled to something along the lines of

f(unsigned char*, unsigned int, unsigned int):
        bswap   esi
        bswap   edx
        mov     DWORD PTR [rdi], esi
        mov     DWORD PTR [rdi+4], edx
        ret

however, I get scores of bitwise operations instead if `-fno-tree-vectorize=
` is
not specified.

https://gcc.godbolt.org/z/z51K6qorv=