[Bug math/16599] New: [i386] Spurious underflow from asin

[Bug math/16599] New: [i386] Spurious underflow from asin

[jsm28 at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16599

            Bug ID: 16599
           Summary: [i386] Spurious underflow from asin
           Product: glibc
           Version: 2.19
            Status: NEW
          Severity: normal
          Priority: P2
         Component: math
          Assignee: unassigned at sourceware dot org
          Reporter: jsm28 at gcc dot gnu.org
              Host: i?86-*-*

On 32-bit x86 (possibly depending on the processor), asin (-DBL_MIN), in
FE_UPWARD mode, produces a result in the underflowing range.  The mathematical
result is slightly outside that range.

testing double (without inline functions)
Failure: asin_upward (-0x4p-1024): Exception "Underflow" set

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[Bug math/16599] [i386] Spurious underflow from asin

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16599

--- Comment #1 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  046651c1688ff0eaa385d555dc4f24fd51a64460 (commit)
      from  003e49ed5d2034d73bfcf5324c461785687b7e88 (commit)

Those revisions listed above that are new to this repository have
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- Log -----------------------------------------------------------------
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=046651c1688ff0eaa385d555dc4f24fd51a64460

commit 046651c1688ff0eaa385d555dc4f24fd51a64460
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Tue Mar 25 12:26:06 2014 +0000

    Relax gen-auto-libm-tests may-underflow rules, test log1p in all rounding
modes.

    gen-auto-libm-tests presently allows but does not require underflow
    exceptions for results with magnitude in the range (greatest
    subnormal, least normal].

    In some cases, the magnitude of the exact result is very slightly
    above the least normal, but rounding in the implementation results in
    it effectively computing an infinite-precision result that is slightly
    below the least normal, so raising an underflow exception.  This is in
    accordance with the documented accuracy goals, but results in
    testsuite failures.

    This patch changes the logic to allow underflows when the mathematical
    result is up to 0.5ulp above the least normal (so in any case where
    the round-to-nearest result is the least normal).  Ideally underflows
    in all these cases would be accepted only when an underflow with the
    actual result is consistent with the rounding mode (in FE_TOWARDZERO
    mode, a return value of the least normal implies that the
    infinite-precision result did not underflow so there should be no
    underflow exception, for example), so as to match the documented goals
    more precisely - whereas at present the tests for exceptions are
    completely independent of the tests of the returned values.  (The same
    applies to overflow exceptions as well - they too should be checked
    for consistency with the result, as in FE_TOWARDZERO mode a result
    1ulp below the largest finite value should be inconsistent with an
    overflow exception and cause a failure with overflow rather than
    simply being considered a 1ulp error when overflow is expected.)  But
    the present patch at least deals with the cases causing spurious
    failures so that (a) certain existing tests no longer need to be
    marked as having spurious exceptions (such markings in
    auto-libm-test-in end up applying to more cases than just those they
    are needed for) and (b) log1p can be tested in all rounding modes
    without introducing more such failures.  This patch duly moves tests
    of log1p to ALL_RM_TEST.

    Tested x86_64 and x86 and ulps updated accordingly.

        [BZ #16357]
        [BZ #16599]
        * math/gen-auto-libm-tests.c (fp_format_desc): Add field
        min_plus_half.
        (fp_formats): Update initializers.
        (init_fp_formats): Initialize new field.
        (output_for_one_input_case): Allow underflow for results up to
        min_plus_half.
        * math/libm-test.inc (log1p_test): Use ALL_RM_TEST.
        * math/auto-libm-test-in: Don't mark some underflows from asin and
        atanh as spurious.
        * math/auto-libm-test-out: Regenerated.
        * sysdeps/i386/fpu/libm-test-ulps: Update.
        * sysdeps/x86_64/fpu/libm-test-ulps: Likewise.

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

Summary of changes:
 ChangeLog                         |   17 ++
 NEWS                              |    8 +-
 math/auto-libm-test-in            |    8 +-
 math/auto-libm-test-out           |  558 ++++++++++++++++++------------------
 math/gen-auto-libm-tests.c        |   23 +-
 math/libm-test.inc                |    4 +-
 sysdeps/i386/fpu/libm-test-ulps   |   24 ++
 sysdeps/x86_64/fpu/libm-test-ulps |   24 ++
 8 files changed, 367 insertions(+), 299 deletions(-)

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[Bug math/16599] [i386] Spurious underflow from asin

[jsm28 at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16599

Joseph Myers <jsm28 at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #2 from Joseph Myers <jsm28 at gcc dot gnu.org> ---
The testsuite logic counting this as spurious has been fixed for 2.20 to be
closer to the documented accuracy goals.

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[Bug math/16599] [i386] Spurious underflow from asin

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16599

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
              Flags|                            |security-

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