From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id E28AD3858C5F; Wed, 28 Feb 2024 08:12:14 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org E28AD3858C5F DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1709107934; bh=HSeuBHYJc4PMkp9soY1l73tLXinFUKRMkBpnxi3mZJg=; h=From:To:Subject:Date:In-Reply-To:References:From; b=WFYHo9uiorzwyJpv+vbbeZWk2A9eOycx/wwn3RwU7ImvmBqMS4GhxWe8b7OB4MbBw TPoBWjKhihZYIG4o/DkuwsuK4+woTOBlRKf1mMtAZ3B1eH1QOGM9UsuOkTouYps5kS 72MqTLyiHy8G6Gh6kFdSQHJG4OLfALRyTYjmb5qM= From: "rguenth at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug libquadmath/114140] different results for std::fmin/std::fmax and quadmath fminq/fmaxq if one argument=signaling_NaN Date: Wed, 28 Feb 2024 08:12:13 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: libquadmath X-Bugzilla-Version: unknown X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: rguenth 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 List-Id: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114140 --- Comment #15 from Richard Biener --- It's the old argument on whether isnan(NaN) should return true or false with -ffinite-math-only. With what we currently do "constant folding" sNaN into= NaN would be correct with -fno-signalling-nans, likewise constant folding Inf i= nto 42.0 is "correct" for -ffinite-math-only. You are basically invoking undefined beavior when introducing sNaN into a program without using -fsignalling-nans.=