[Bug math/16562] New: spurious overflow exception from yn

[Bug math/16562] New: spurious overflow exception from yn

[zimmerma+gcc at loria dot fr]

https://sourceware.org/bugzilla/show_bug.cgi?id=16562

            Bug ID: 16562
           Summary: spurious overflow exception from yn
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: math
          Assignee: unassigned at sourceware dot org
          Reporter: zimmerma+gcc at loria dot fr

on x86_64 I get (double precision, y42 is yn for n=42):

Testing function y42 for exponent 3 [seed=14309].
 rounding mode MPFR_RNDZ:
      wrong overflow flag for x=4.0000000000000@-269
      library gives -f.ffffffffffff0@255
      mpfr    gives -f.ffffffffffff8@255
      overflow: mpfr 2, library 8

Note the glibc result is *not* -DBL_MAX, thus no overflow exception should be
raised.

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[Bug math/16562] spurious overflow exception from yn

[zimmerma+gcc at loria dot fr]

https://sourceware.org/bugzilla/show_bug.cgi?id=16562

--- Comment #1 from Paul Zimmermann <zimmerma+gcc at loria dot fr> ---
idem in extended precision:

Testing function y42 for exponent 3 [seed=16203].
 rounding mode MPFR_RNDZ:
      wrong overflow flag for x=8.0000000000000000@-4112
      library gives -f.ffffffffffffffe0@4095
      mpfr    gives -f.fffffffffffffff0@4095
      overflow: mpfr 2, library 8

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[Bug math/16562] spurious overflow exception from yn

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16562

Florian Weimer <fweimer at redhat dot com> changed:

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

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[Bug math/16562] spurious overflow exception from yn

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16562

--- 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
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The branch, master has been updated
       via  be25493251c014a696b62834b0e63b155d8fe353 (commit)
      from  b351d85aa284f81271bc93e11301e1c2466b7c82 (commit)

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- Log -----------------------------------------------------------------
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=be25493251c014a696b62834b0e63b155d8fe353

commit be25493251c014a696b62834b0e63b155d8fe353
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Fri Jun 27 14:52:13 2014 +0000

    Fix yn overflow handling in non-default rounding modes (bug 16561, bug
16562).

    This patch fixes bugs 16561 and 16562, bad results of yn in overflow
    cases in non-default rounding modes, both because an intermediate
    overflow in the recurrence does not get detected if the result is not
    an infinity and because an overflowing result may occur in the wrong
    sign.  The fix is to set FE_TONEAREST mode internally for the parts of
    the function where such overflows can occur (which includes the call
    to y1 - where yn is used to compute a Bessel function of order -1,
    negating the result of y1 isn't correct for overflowing results in
    directed rounding modes) and then compute an overflowing value in the
    original rounding mode if the to-nearest result was an infinity.

    Tested x86_64 and x86 and ulps updated accordingly.  Also tested for
    mips64 and powerpc32 to test the ldbl-128 and ldbl-128ibm changes.

    (The tests for these bugs were added in my previous y1 patch, so the
    only thing this patch has to do with the testsuite is enable yn
    testing in all rounding modes.)

        [BZ #16561]
        [BZ #16562]
        * sysdeps/ieee754/dbl-64/e_jn.c: Include <float.h>.
        (__ieee754_yn): Set FE_TONEAREST mode internally and then
        recompute overflowing results in original rounding mode.
        * sysdeps/ieee754/flt-32/e_jnf.c: Include <float.h>.
        (__ieee754_ynf): Set FE_TONEAREST mode internally and then
        recompute overflowing results in original rounding mode.
        * sysdeps/ieee754/ldbl-128/e_jnl.c: Include <float.h>.
        (__ieee754_ynl): Set FE_TONEAREST mode internally and then
        recompute overflowing results in original rounding mode.
        * sysdeps/ieee754/ldbl-128ibm/e_jnl.c: Include <float.h>.
        (__ieee754_ynl): Set FE_TONEAREST mode internally and then
        recompute overflowing results in original rounding mode.
        * sysdeps/ieee754/ldbl-96/e_jnl.c: Include <float.h>.
        (__ieee754_ynl): Set FE_TONEAREST mode internally and then
        recompute overflowing results in original rounding mode.
        * sysdeps/i386/fpu/fenv_private.h [!__SSE2_MATH__]
        (libc_feholdsetround_ctx): New macro.
        * math/libm-test.inc (yn_test): Use ALL_RM_TEST.
        * sysdeps/i386/fpu/libm-test-ulps: Update.
        * sysdeps/x86_64/fpu/libm-test-ulps : Likewise.

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

Summary of changes:
 ChangeLog                           |   25 ++++++
 NEWS                                |   20 +++---
 math/libm-test.inc                  |    4 +-
 sysdeps/i386/fpu/fenv_private.h     |    1 +
 sysdeps/i386/fpu/libm-test-ulps     |   24 ++++++
 sysdeps/ieee754/dbl-64/e_jn.c       |  117 ++++++++++++++++-------------
 sysdeps/ieee754/flt-32/e_jnf.c      |   16 ++++-
 sysdeps/ieee754/ldbl-128/e_jnl.c    |  139 ++++++++++++++++++----------------
 sysdeps/ieee754/ldbl-128ibm/e_jnl.c |  143 +++++++++++++++++++----------------
 sysdeps/ieee754/ldbl-96/e_jnl.c     |  137 ++++++++++++++++++---------------
 sysdeps/x86_64/fpu/libm-test-ulps   |   24 ++++++
 11 files changed, 389 insertions(+), 261 deletions(-)

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[Bug math/16562] spurious overflow exception from yn

[jsm28 at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16562

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

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

--- Comment #3 from Joseph Myers <jsm28 at gcc dot gnu.org> ---
Fixed for 2.20.

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