From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 6399F3951C4F; Wed, 10 Mar 2021 16:13:00 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 6399F3951C4F From: "jakub at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/99520] Failure to detect bswap pattern Date: Wed, 10 Mar 2021 16:13:00 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: middle-end X-Bugzilla-Version: unknown X-Bugzilla-Keywords: missed-optimization X-Bugzilla-Severity: normal X-Bugzilla-Who: jakub at gcc dot gnu.org 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: 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, 10 Mar 2021 16:13:00 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99520 --- Comment #2 from Jakub Jelinek --- Bet handling PLUS_EXPR next to BIT_IOR_EXPR in find_bswap_or_nop_1 and pass_optimize_bswap::execute could do the trick. Though, I guess for PLUS_EXPR one needs stronger tests in perform_symbolic_merge. Because for BIT_IOR_EXPR, it is perfectly fine if the same bytes are ored in multiple times, but for PLUS_EXPR it obviously is not. So masked1 =3D n1->n & mask; masked2 =3D n2->n & mask; if (masked1 && masked2 && masked1 !=3D masked2) return NULL; is good enough for BIT_IOR_EXPR, but PLUS_EXPR would need a if (masked1 && masked2) return NULL; test.=