From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 6B047387740C; Mon, 21 Jun 2021 19:27:17 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 6B047387740C From: "segher at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug target/100866] PPC: Inefficient code for vec_revb(vector unsigned short) < P9 Date: Mon, 21 Jun 2021 19:27:17 +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: 8.3.1 X-Bugzilla-Keywords: missed-optimization X-Bugzilla-Severity: enhancement X-Bugzilla-Who: segher 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: Message-ID: In-Reply-To: References: 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 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 21 Jun 2021 19:27:17 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D100866 --- Comment #12 from Segher Boessenkool --- (In reply to Bill Schmidt from comment #11) > Segher, does this fit naturally in combine? This is just constant folding, combine won't have much to do with it. It is always better (namely, lower latency) to use one vector permute than to have multiple dependent permutation-class instructions. Combine will automatically pick this up when it gets the chance. Does it here though, or are there still some unspecs here that make all this non-clear?=