From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <glibc-bugs-return-18582-listarch-glibc-bugs=sources.redhat.com@sourceware.org>
Received: (qmail 9483 invoked by alias); 7 May 2013 19:17:26 -0000
Mailing-List: contact glibc-bugs-help@sourceware.org; run by ezmlm
Precedence: bulk
List-Id: <glibc-bugs.sourceware.org>
List-Subscribe: <mailto:glibc-bugs-subscribe@sourceware.org>
List-Post: <mailto:glibc-bugs@sourceware.org>
List-Help: <mailto:glibc-bugs-help@sourceware.org>, <http://sourceware.org/lists.html#faqs>
Sender: glibc-bugs-owner@sourceware.org
Received: (qmail 9446 invoked by uid 48); 7 May 2013 19:17:23 -0000
From: "macro@linux-mips.org" <sourceware-bugzilla@sourceware.org>
To: glibc-bugs@sourceware.org
Subject: [Bug math/15442] New: MIPS NewABI sqrtl (soft-fp) test-ldouble sqrt (qNaN) failure
Date: Tue, 07 May 2013 19:17:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: glibc
X-Bugzilla-Component: math
X-Bugzilla-Keywords:
X-Bugzilla-Severity: normal
X-Bugzilla-Who: macro@linux-mips.org
X-Bugzilla-Status: NEW
X-Bugzilla-Priority: P2
X-Bugzilla-Assigned-To: macro@linux-mips.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Changed-Fields:
Message-ID: <bug-15442-131@http.sourceware.org/bugzilla/>
X-Bugzilla-URL: http://sourceware.org/bugzilla/
Auto-Submitted: auto-generated
Content-Type: text/plain; charset="UTF-8"
MIME-Version: 1.0
X-SW-Source: 2013-05/txt/msg00029.txt.bz2

http://sourceware.org/bugzilla/show_bug.cgi?id=15442

             Bug #: 15442
           Summary: MIPS NewABI sqrtl (soft-fp) test-ldouble sqrt (qNaN)
                    failure
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: math
        AssignedTo: macro@linux-mips.org
        ReportedBy: macro@linux-mips.org
                CC: tschwinge@sourceware.org
    Classification: Unclassified
            Target: mips-linux-gnu


This problem:

Failure: sqrt (qNaN) == qNaN: Exception "Invalid operation" set
Failure: Test: sqrt (qNaN) == qNaN
Result:
 is:         sNaN
 should be:  qNaN

is reported for sqrtl by test-ldouble for the MIPS/Linux target and the
n64 and n64 ABIs.  This is because soft-fp does not respect the MIPS NaN
encoding convention, where the quiet bit being zero denotes a qNaN.
This is the only soft-fp function used by the MIPS port.

There are other failures too, for negative numeric inputs, e.g. -1, but
in those cases the result is passed through __kernel_standard that
returns a double value rather than a long double value.  Therefore the
result is converted with __extenddftf2, that is a part of GCC's fp-bit
soft-float support.  That support suffers from a related bug being
discussed here:

http://gcc.gnu.org/ml/gcc-patches/2013-04/msg00278.html

and therefore the remaining failures cannot be removed by simply
correcting our soft-fp support.

A proposed fix has been posted here:

http://sourceware.org/ml/libc-alpha/2013-04/msg00646.html

-- that removes the test-ldouble failure referred to above.

-- 
Configure bugmail: http://sourceware.org/bugzilla/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are on the CC list for the bug.