From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id EBA4E3858C3A; Wed, 13 Oct 2021 12:50:12 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org EBA4E3858C3A From: "ubizjak at gmail dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug target/93934] Unnecessary fld of uninitialized float stack variable results in ub of valid C++ code Date: Wed, 13 Oct 2021 12:50:12 +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: 7.4.0 X-Bugzilla-Keywords: wrong-code X-Bugzilla-Severity: normal X-Bugzilla-Who: ubizjak at gmail dot com 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, 13 Oct 2021 12:50:13 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D93934 --- Comment #11 from Uro=C5=A1 Bizjak --- (In reply to Zoltan Vajda from comment #9) > As I understand it, it is acknowledged, that this is a bug. However, the > issue is in state NEW for a quite long time. The issue is still present in > GCC 11.2. Do you see any chances for some progress in this case? The Comment #5 summarises all the troubles with trapping FLDL/FLDS. I'm afr= aid that trapping FLDL/FLDS renders -fsignaling-nans on x87 practically impossi= ble to implement. Even the documentation advises against usage of -fsignaling-nans: This option is experimental and does not currently guarantee to disable all GCC optimizations that affect signaling NaN behavior. You should really use -mfpmath=3Dsse here.=