[Bug math/18803] hypot missing underflows

["cvs-commit at gcc dot gnu.org" <sourceware-bugzilla at sourceware dot org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=18803

--- Comment #2 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
This is an automated email from the git hooks/post-receive script. It was
generated because a ref change was pushed to the repository containing
the project "GNU C Library master sources".

The branch, master has been updated
       via  f6987f5aa4c2ef7270bcb0a828808bd3db53520b (commit)
      from  2fd9177c92328e5c861c60ec9d0c4588cf0d9376 (commit)

Those revisions listed above that are new to this repository have
not appeared on any other notification email; so we list those
revisions in full, below.

- Log -----------------------------------------------------------------
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=f6987f5aa4c2ef7270bcb0a828808bd3db53520b

commit f6987f5aa4c2ef7270bcb0a828808bd3db53520b
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Thu Sep 24 23:43:57 2015 +0000

    Fix hypot missing underflows (bug 18803).

    Similar to various other bugs in this area, hypot functions can fail
    to raise the underflow exception when the result is tiny and inexact
    but one or more low bits of the intermediate result that is scaled
    down (or, in the i386 case, converted from a wider evaluation format)
    are zero.  This patch forces the exception in a similar way to
    previous fixes.

    Note that this issue cannot arise for implementations of hypotf using
    double (or wider) for intermediate evaluation (if hypotf should
    underflow, that means the double square root is being computed of some
    number of the form N*2^-298, for 0 < N < 2^46, which is exactly
    represented as a double, and whatever the rounding mode such a square
    root cannot have a mantissa with all zeroes after the initial 23
    bits).  Thus no changes are made to hypotf implementations in this
    patch, only to hypot and hypotl.

    Tested for x86_64, x86, mips64 and powerpc.

        [BZ #18803]
        * sysdeps/i386/fpu/e_hypot.S: Use DEFINE_DBL_MIN.
        (MO): New macro.
        (__ieee754_hypot) [PIC]: Load PIC register.
        (__ieee754_hypot): Use DBL_NARROW_EVAL_UFLOW_NONNEG instead of
        DBL_NARROW_EVAL.
        * sysdeps/ieee754/dbl-64/e_hypot.c (__ieee754_hypot): Use
        math_check_force_underflow_nonneg in case where result might be
        tiny.
        * sysdeps/ieee754/ldbl-128/e_hypotl.c (__ieee754_hypotl):
        Likewise.
        * sysdeps/ieee754/ldbl-128ibm/e_hypotl.c (__ieee754_hypotl):
        Likewise.
        * sysdeps/ieee754/ldbl-96/e_hypotl.c (__ieee754_hypotl): Likewise.
        * sysdeps/powerpc/fpu/e_hypot.c (__ieee754_hypot): Likewise.
        * math/auto-libm-test-in: Add more tests of hypot.
        * math/auto-libm-test-out: Regenerated.

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog                              |   20 +
 NEWS                                   |    6 +-
 math/auto-libm-test-in                 |    7 +
 math/auto-libm-test-out                | 1342 ++++++++++++++++++++++++++++++++
 sysdeps/i386/fpu/e_hypot.S             |   13 +-
 sysdeps/ieee754/dbl-64/e_hypot.c       |    4 +-
 sysdeps/ieee754/ldbl-128/e_hypotl.c    |    4 +-
 sysdeps/ieee754/ldbl-128ibm/e_hypotl.c |    6 +-
 sysdeps/ieee754/ldbl-96/e_hypotl.c     |    4 +-
 sysdeps/powerpc/fpu/e_hypot.c          |    4 +-
 10 files changed, 1401 insertions(+), 9 deletions(-)

-- 
You are receiving this mail because:
You are on the CC list for the bug.