From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id CBF26385E449; Thu, 8 Apr 2021 22:46:55 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org CBF26385E449 From: "segher at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/99930] Failure to optimize floating point -abs(x) in nontrivial code at -O2/3 Date: Thu, 08 Apr 2021 22:46:55 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: rtl-optimization X-Bugzilla-Version: 11.0 X-Bugzilla-Keywords: missed-optimization X-Bugzilla-Severity: normal 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: Thu, 08 Apr 2021 22:46:55 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99930 --- Comment #10 from Segher Boessenkool --- That is a USE of a constant, which is a no-op always. Here we have a USE of a register, which is not. We actually have *two* uses of pseudos, and combine cannot know what that means for the target (all PARALLELs are split up in combine).=