From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 59F6A3858CDB; Thu, 9 Mar 2023 11:50:29 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 59F6A3858CDB DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1678362629; bh=qpQI00tTIWyt6E2eDAf/ts8xe+SojseLxGPtWZoQPJg=; h=From:To:Subject:Date:In-Reply-To:References:From; b=uN/KW0F5VuZRym3vn8TWFfd9hO2fsp6WbcSdx7p/m35RKQj3Luo8PsK9DcuAdyZPA VcZm+KlsvTxaHInhZEz/qfCFWiot+H7DMe4XR8cglXDuIDu9Hg1XaEw5Lg6bLIlm1v IccZdYPEk/+MwpXzfTMGk1vKSasIrQALDLLFs7J4= From: "jakub at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/109008] [13 Regression] Wrong code in scipy package since r13-3926-gd4c2f1d376da6f Date: Thu, 09 Mar 2023 11:50:28 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: tree-optimization X-Bugzilla-Version: 13.0 X-Bugzilla-Keywords: wrong-code X-Bugzilla-Severity: normal X-Bugzilla-Who: jakub at gcc dot gnu.org X-Bugzilla-Status: RESOLVED X-Bugzilla-Resolution: FIXED X-Bugzilla-Priority: P1 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: 13.0 X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: attachments.created 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=3D109008 --- Comment #43 from Jakub Jelinek --- Created attachment 54622 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D54622&action=3Dedit gcc13-pr109008-2.patch Above mentioned incremental patch. It does actually 2 things. One is not widening to -inf or +inf, but to nextafter value in a hypothetical wider floating point type with equal mantissa precision but wider exponent range. And the other is, as the new test in that patch shows, that regardless whet= her we do the above optimization or not, with -ffinite-math-only it would still be miscompiled, as we limit the range to the maximum representable value an= d so on the resulting range in this case we get with vanilla trunk [frange] double [-1.9958403095347198116563727130368385660674512604354575415e+292 (-0x0.8p+9= 72), 0.0 (0x0.0p+0)] range. That is incorrect, __DBL_MAX__ + 0x0.fffffffffffff8p+970 when rounding to nearest is still finite (__DBL_MAX= __), and so valid for -ffinite-math-only. There is another issue. For !MODE_HAS_INFINITIES (TYPE_MODE (type)) types I'm afraid this is still broken and significantly more so. Because the min= imum or maximum representable values in those cases (probably, haven't played wi= th such machines) act as saturation boundaries (like infinities normally), WHATEVER_MAX + anything_positive is still WHATEVER_MAX etc. So, wonder if we e.g. shouldn't just punt in float_binary_op_range_finish for such modes if lhs range has at least one of the boundaries the maximum representable one. Though, maybe it isn't limited to the reverse ops, who knows...=