[Bug math/18583] New: fmodl, remainderl spurious inexact for NaN results

[Bug math/18583] New: fmodl, remainderl spurious inexact for NaN results

[jsm28 at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=18583

            Bug ID: 18583
           Summary: fmodl, remainderl spurious inexact for NaN results
           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: ---

Similar to bug 18245 for sqrtl, and with the same underlying cause, fmodl
(-1.1L, 0.0L) and similar cases with (Inf, y) and with remainderl, produce
spurious "inexact" exceptions with NaN results (these being fully determined
functions, they should not do so, whereas for most functions such exceptions
are OK).

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[Bug math/18583] fmodl, remainderl spurious inexact for NaN results

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=18583

--- Comment #1 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
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The branch, master has been updated
       via  8b1bab5ffa235bc494c33fdbe4c9994202936cfc (commit)
      from  c47ca9647f9b72692e62f94fe468cd5568f49129 (commit)

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- Log -----------------------------------------------------------------
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=8b1bab5ffa235bc494c33fdbe4c9994202936cfc

commit 8b1bab5ffa235bc494c33fdbe4c9994202936cfc
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Tue Jun 23 17:26:46 2015 +0000

    Fix spurious "inexact" exceptions from __kernel_standard_l (bug 18245, bug
18583).

    __kernel_standard_l converts long double arguments to double for use
    in SVID "struct exception".  This has special-case handling for when
    that conversion would overflow or underflow but the original long
    double function wouldn't.  However, it turns out that "inexact"
    exceptions can be spurious here as well, when the function is exactly
    determined and __kernel_standard_l is being called for a domain error.
    This patch fixes this by using feholdexcept / fesetenv to avoid
    exceptions from the conversion, replacing the previous special-case
    logic for overflow and underflow (this covers all functions using
    __kernel_standard_l, not just those that actually need a change, since
    there doesn't seem to be much point in restricting things just to the
    functions that mustn't get "inexact" here).

    Tested for x86_64 and x86.

        [BZ #18245]
        [BZ #18583]
        * sysdeps/ieee754/k_standardl.c: Include <fenv.h>.
        (__kernel_standard_l): Use feholdexcept and fesetenv around
        conversion to double instead of special-casing overflow and
        underflow.
        * math/libm-test.inc (fmod_test_data): Add more tests.
        (remainder_test_data): Likewise.
        (sqrt_test_data): Likewise.

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

Summary of changes:
 ChangeLog                     |   12 ++++++++++++
 NEWS                          |   12 ++++++------
 math/libm-test.inc            |    9 +++++++++
 sysdeps/ieee754/k_standardl.c |   34 +++++++++-------------------------
 4 files changed, 36 insertions(+), 31 deletions(-)

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[Bug math/18583] fmodl, remainderl spurious inexact for NaN results

[jsm28 at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=18583

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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