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 044AC3851C26; Fri, 19 Jun 2020 17:43:15 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 044AC3851C26
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
 s=default; t=1592588596;
 bh=d6PmvwUyY+pRwxKnoVpCAbzKVZYMP0iQmA94DU9u5+k=;
 h=From:To:Subject:Date:In-Reply-To:References:From;
 b=EjHLER1TxEVCp8iDAdy7tjlUnE0LN5Y2hQ5ghukVVSXESME/MRjOTfT7CkbPa/pFn
 8P0rYG8EGDO0V5GdGNyCbjHI8lVN0CqREqx9eWRKi3n+XGRR5A2HU2EeovoMPUSvgc
 M4bPGTbETePFbCKcJK8K+Jsaxdydab/GX5HnADdY=
From: "jens.seifert at de dot ibm.com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/95737] PPC: Unnecessary extsw after negative less than
Date: Fri, 19 Jun 2020 17:43:15 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: target
X-Bugzilla-Version: 8.3.0
X-Bugzilla-Keywords: missed-optimization
X-Bugzilla-Severity: normal
X-Bugzilla-Who: jens.seifert at de dot ibm.com
X-Bugzilla-Status: UNCONFIRMED
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_status resolution
Message-ID: <bug-95737-4-dmnOMiUmVr@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-95737-4@http.gcc.gnu.org/bugzilla/>
References: <bug-95737-4@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: <http://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: <http://gcc.gnu.org/mailman/listinfo/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Fri, 19 Jun 2020 17:43:16 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95737

Jens Seifert <jens.seifert at de dot ibm.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |UNCONFIRMED
         Resolution|DUPLICATE                   |---

--- Comment #3 from Jens Seifert <jens.seifert at de dot ibm.com> ---
This is different as the extsw also happens if the result gets used e.g.
followed by a andc, which is my case. I obviously oversimplified the sample=
. It
has nothing to do with function result and ABI requirements. gcc assume that
the result of -(a < b) implemented by subfc, subfe is signed 32-bit. But the
result is already 64-bit.

unsigned long long branchlesconditional(unsigned long long a, unsigned long
long b, unsigned long long c)
{
   unsigned long long mask =3D -(a < b);
   return c &~ mask;
}

results in

_Z20branchlesconditionalyyy:
.LFB1:
        .cfi_startproc
        subfc 4,4,3
        subfe 3,3,3
        not 3,3
        extsw 3,3
        and 3,3,5
        blr

expected
subfc
subfe
andc=