From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 1E31B3849ADC; Fri, 19 Apr 2024 16:50:45 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 1E31B3849ADC DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1713545445; bh=LxLkSNumGUAJ3JaKvHk1o7yaVk0UmZ4QEwuUokKnR/E=; h=From:To:Subject:Date:In-Reply-To:References:From; b=m8BR/ml+r7kX0ClWDJ5FahV4uI1PcYS7O5KJeo5h9XozVuiNGMaUSU8ceaDjvSvXK P7NHGiWJfDkBhsP4ybndetZRbOlUleo3cxJzeeZfwM3vSOWmiJ1GN20RNMnhMu8Y71 LARCvoZyISUcsSCQ0fyrYaV7Zslqm16DNDIztVf8= From: "jsm28 at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug c/114746] With FLT_EVAL_METHOD = 2, -fexcess-precision=fast reduces the precision of floating-point constants and floating-point constant expressions Date: Fri, 19 Apr 2024 16:50:44 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: c X-Bugzilla-Version: 14.0 X-Bugzilla-Keywords: wrong-code X-Bugzilla-Severity: normal X-Bugzilla-Who: jsm28 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=3D114746 --- Comment #3 from Joseph S. Myers --- The actual effect of -fexcess-precision=3Dfast is more like "outside the ba= ck end, pretend excess precision doesn't exist, but the back end might use it anyway" (complicated a bit by having genuine excess precision logic for _Float16 still in operation when otherwise pretending excess precision does= n't exist). Pretending excess precision doesn't exist includes not having its effects on constants. Maybe that's confusing, but the effects of excess precision on constants also confuse people, as do all forms of excess preci= sion for operations, so it's not clear that an alternative would be any better.=