From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id C9A7F3858D28; Wed, 6 Jul 2022 23:34:19 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org C9A7F3858D28 From: "already5chosen at yahoo dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug target/106220] x86-64 optimizer forgets about shrd peephole optimization pattern when faced with more than one in close proximity Date: Wed, 06 Jul 2022 23:34:19 +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: 12.1.0 X-Bugzilla-Keywords: missed-optimization X-Bugzilla-Severity: normal X-Bugzilla-Who: already5chosen at yahoo dot 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: 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, 06 Jul 2022 23:34:19 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106220 --- Comment #3 from Michael_S --- -march-haswell is not very important. I added it only because in absence of BMI extension an issue is somewhat obscured by need to keep shift count in CL register. -O2 is also not important. -O3 is the same. And -O1, due to absence of if-conversion, demonstrates the same issue in different form. In practice, I'd guess -O1 code would perform quite well, unlike -O2 and -O= 3, but it does not make it less ugly looking.=