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 77F853858001; Fri, 18 Feb 2022 08:37:32 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 77F853858001
From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/104582] [11/12 Regression] Unoptimal code for
 __negdi2 (and others) from libgcc2 due to unwanted vectorization
Date: Fri, 18 Feb 2022 08:37:32 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 12.0
X-Bugzilla-Keywords: missed-optimization
X-Bugzilla-Severity: normal
X-Bugzilla-Who: jakub at gcc dot gnu.org
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: 11.3
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-104582-4-55lUmGJzcr@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-104582-4@http.gcc.gnu.org/bugzilla/>
References: <bug-104582-4@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: Fri, 18 Feb 2022 08:37:32 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104582

--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Just trying a dumb microbenchmark:
struct S { unsigned long a, b; } s;

__attribute__((noipa)) void
foo (unsigned long a, unsigned long b)
{
  s.a =3D a;
  s.b =3D b;
}

int
main ()
{
  int i;
  for (i =3D 0; i < 1000000000; i++)
    foo (42, 43);
  return 0;
}
the GCC 11 vs. GCC 12 code:
-       movq    %rdi, s(%rip)
-       movq    %rsi, s+8(%rip)
+       movq    %rdi, %xmm0
+       movq    %rsi, %xmm1
+       punpcklqdq      %xmm1, %xmm0
+       movaps  %xmm0, s(%rip)
seems to be exactly the same speed (on i9-7960X) and the GCC 11 code is 7 b=
ytes
smaller.=