[Bug math/18593] New: csin, csinh bad overflow results in directed rounding modes

[Bug math/18593] New: csin, csinh bad overflow results in directed rounding modes

[jsm28 at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=18593

            Bug ID: 18593
           Summary: csin, csinh bad overflow results in directed rounding
                    modes
           Product: glibc
           Version: 2.21
            Status: NEW
          Severity: normal
          Priority: P2
         Component: math
          Assignee: unassigned at sourceware dot org
          Reporter: jsm28 at gcc dot gnu.org
  Target Milestone: ---

csin and csinh can produce bad results when overflowing in directed rounding
modes.  E.g., for float on x86_64:

Failure: Test: Real part of: csin_downward (-0xcp-4 - 0x2.c5d4p+12 i)
Result:
 is:         -3.40282346638528859812e+38  -0x1.fffffe00000000000000p+127
 should be:  -inf  -inf

Failure: Test: Real part of: csinh_downward (-0x2.c5d4p+12 - 0xcp-4 i)
Result:
 is:         -3.40282346638528859812e+38  -0x1.fffffe00000000000000p+127
 should be:  -inf  -inf

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[Bug math/18593] csin, csinh bad overflow results in directed rounding modes

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=18593

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       via  ac831b362ad6ecd49643625481ec700a9812e52f (commit)
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- Log -----------------------------------------------------------------
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=ac831b362ad6ecd49643625481ec700a9812e52f

commit ac831b362ad6ecd49643625481ec700a9812e52f
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Wed Jun 24 16:20:48 2015 +0000

    Fix csin, csinh overflow in directed rounding modes (bug 18593).

    csin and csinh can produce bad results when overflowing in directed
    rounding modes, because a multiplication that can overflow is followed
    by a possible negation.  This patch fixes this by negating one of the
    arguments of the multiplication before the multiplication instead of
    negating the result.

    The new tests for this issue are added to auto-libm-test-in, starting
    use of that file for csin and csinh.  The issue was found in the
    course of moving existing tests for csin and csinh (existing tests, by
    being enabled in more cases than previously, showed the issue for
    float and double but not for long double); that move will now be done
    separately.

    Tested for x86_64 and x86 and ulps updated accordingly.

        [BZ #18593]
        * math/s_csin.c (__csin): Negate before rather than after possibly
        overflowing multiplication.
        * math/s_csinf.c (__csinf): Likewise.
        * math/s_csinh.c (__csinh): Likewise.
        * math/s_csinhf.c (__csinhf): Likewise.
        * math/s_csinhl.c (__csinhl): Likewise.
        * math/s_csinl.c (__csinl): Likewise.
        * math/auto-libm-test-in: Add some tests of csin and csinh.
        * math/auto-libm-test-out: Regenerated.
        * math/libm-test.inc (csin_test_data): Use AUTO_TESTS_c_c.
        (csinh_test_data): Likewise.
        * sysdeps/x86_64/fpu/libm-test-ulps: Update.

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

Summary of changes:
 ChangeLog                         |   14 +++
 NEWS                              |    2 +-
 math/auto-libm-test-in            |   10 ++
 math/auto-libm-test-out           |  200 +++++++++++++++++++++++++++++++++++++
 math/libm-test.inc                |    4 +
 math/s_csin.c                     |    6 +-
 math/s_csinf.c                    |    6 +-
 math/s_csinh.c                    |    6 +-
 math/s_csinhf.c                   |    6 +-
 math/s_csinhl.c                   |    6 +-
 math/s_csinl.c                    |    6 +-
 sysdeps/x86_64/fpu/libm-test-ulps |    8 +-
 12 files changed, 251 insertions(+), 23 deletions(-)

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[Bug math/18593] csin, csinh bad overflow results in directed rounding modes

[jsm28 at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=18593

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> ---
Fixed for 2.22.

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