From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-413639-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 14477 invoked by alias); 30 Jan 2013 15:18:29 -0000
Received: (qmail 14441 invoked by uid 48); 30 Jan 2013 15:18:13 -0000
From: "ysrumyan at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/56151] New: Performance degradation after r194054 on x86 Atom.
Date: Wed, 30 Jan 2013 15:18:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Keywords:
X-Bugzilla-Severity: normal
X-Bugzilla-Who: ysrumyan at gmail dot com
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Changed-Fields:
Message-ID: <bug-56151-4@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: 2013-01/txt/msg02758.txt.bz2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56151

             Bug #: 56151
           Summary: Performance degradation after r194054 on x86 Atom.
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: ysrumyan@gmail.com


For simple test-case extracted from one important benchmark we see number
instrctions increasing after fix r194054. If we compile test-case with compiler
built before this revision we have only 6 instructions for store stmt:

    movl    %edx, %ebx
    movl    %edx, %ebp
    sarl    $5, %ebx
    andl    $31, %ebp
    movl    setmask(,%ebp,4), %ebp
    orl    %ebp, (%edi,%ebx,4)

but after this fix we got 9 instrctions for it:

    movl    %edx, %ebx
    movl    56(%esp), %esi
    sarl    $5, %ebx
    movl    %edx, %ebp
    andl    $31, %ebp
    leal    (%esi,%ebx,4), %esi
    movl    (%esi), %ebx
    orl    setmask(,%ebp,4), %ebx
    movl    %ebx, (%esi)

To reproduce it is sufficient to compile with the following options:

-O2 -ffast-math -msse2 -mfpmath=sse -m32 -march=atom -mtune=atom