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 9BA583858D39; Sun,  5 Sep 2021 04:52:28 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 9BA583858D39
From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/52082] Memory loads not rematerialized
Date: Sun, 05 Sep 2021 04:52:28 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: rtl-optimization
X-Bugzilla-Version: 4.7.0
X-Bugzilla-Keywords: missed-optimization, ra
X-Bugzilla-Severity: enhancement
X-Bugzilla-Who: pinskia at gcc dot gnu.org
X-Bugzilla-Status: NEW
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: bug_severity
Message-ID: <bug-52082-4-6ieDKkRX30@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-52082-4@http.gcc.gnu.org/bugzilla/>
References: <bug-52082-4@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: Sun, 05 Sep 2021 04:52:28 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D52082

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
One thing I noticed that LLVM does to reduce the register pressure is:
(z ? v4 [k] : v3 [k])

Gets pulled out of the loop such that it is:
tmpaddr =3D z ? v4 : v3;

and then inside the loop it does:
(tempaddr)[k]

GCC still has (I changed the bb order just so it is easier to see what is g=
oing
on):
  if (z_39(D) !=3D 0)
    goto <bb 9>; [50.00%]
  else
    goto <bb 11>; [50.00%]

  <bb 11> [local count: 5427362]:
  _21 =3D v3.3_18 + _157;
  iftmp.1_40 =3D *_21;
  goto <bb 10>; [100.00%]

  <bb 9> [local count: 5427362]:
  _17 =3D v4.2_14 + _157;
  iftmp.1_41 =3D *_17;

  <bb 10> [local count: 10854724]:
  # m_8 =3D PHI <iftmp.1_40(11), iftmp.1_41(9)>
  if (m_8 !=3D 0B)
    goto <bb 12>; [94.50%]
  else
    goto <bb 19>; [5.50%]

we should able to do the similar it seems and need two less registers; one =
to
hold z and one to hold either v3 or v4.  This won't be enough for this test=
case
but it will be something.=