From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id E6FC43857BBA; Fri, 8 Jul 2022 17:31:26 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org E6FC43857BBA From: "rearnsha at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug target/106187] armhf: Miscompilation at O2 level (O0 / O1 are working) Date: Fri, 08 Jul 2022 17:31:26 +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: 10.4.0 X-Bugzilla-Keywords: wrong-code X-Bugzilla-Severity: normal X-Bugzilla-Who: rearnsha at gcc dot gnu.org X-Bugzilla-Status: WAITING 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: Fri, 08 Jul 2022 17:31:27 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106187 --- Comment #22 from Richard Earnshaw --- I notice that the sources seem to do floating-point negation by casting val= ues to integers, xor-ing the sign bit and then casting the result back to a flo= at.=20 This is exactly the sort of operation that is likely to violate the aliasing rules (though I don't know if this is the precise source of the problem in = this case).=