From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 636653858D35; Wed, 22 Dec 2021 20:29:15 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 636653858D35 From: "hubicka at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/103797] Clang vectorized LightPixel while GCC does not Date: Wed, 22 Dec 2021 20:29:15 +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: unknown X-Bugzilla-Keywords: missed-optimization X-Bugzilla-Severity: enhancement X-Bugzilla-Who: hubicka 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: Wed, 22 Dec 2021 20:29:15 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103797 --- Comment #11 from Jan Hubicka --- Aha, I did not noticed that we need special patterns (I extecpted this is problem to solve in machine independent code). So I guess we have 1) SLP should vectorize the 3 accesses with -ffast-math to only one vector operation (as opposed to one vector+one scalar it does now) 2) we could adddivv2sf3 pattern which initializes the elt 4 of the operand= 2 to 1.0f to avoid funny results 3) we need to figure out why SLP vectorization is not even considered in t= he original testcase (which I do not seem to be able to dig out with reasonable effort in a way that it preserves original properties - to be vectorized by clang and not vectorized by gcc)=