[Bug math/18951] New: tgamma missing underflows

[Bug math/18951] New: tgamma missing underflows

[jsm28 at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=18951

            Bug ID: 18951
           Summary: tgamma missing underflows
           Product: glibc
           Version: 2.22
            Status: NEW
          Severity: normal
          Priority: P2
         Component: math
          Assignee: unassigned at sourceware dot org
          Reporter: jsm28 at gcc dot gnu.org
  Target Milestone: ---

tgamma functions can sometimes miss underflow exceptions.  E.g., for float on
x86_64:

Failure: tgamma (-0x2.3fe04p+4): Exception "Underflow" not set

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[Bug math/18951] tgamma missing underflows

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=18951

--- 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
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the project "GNU C Library master sources".

The branch, master has been updated
       via  46f74e1deee549b41160d353ce0c8f7db555d36c (commit)
      from  e67dc1b57f1fc8407cb45bdb38ae1eaa0a5c6f78 (commit)

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- Log -----------------------------------------------------------------
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=46f74e1deee549b41160d353ce0c8f7db555d36c

commit 46f74e1deee549b41160d353ce0c8f7db555d36c
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Thu Sep 17 15:51:54 2015 +0000

    Fix tgamma missing underflows (bug 18951).

    Similar to various other bugs in this area, tgamma 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 are zero.  This patch forces the exception in a similar way to
    previous fixes.

    Tested for x86_64, x86, mips64 and powerpc.

        [BZ #18951]
        * sysdeps/ieee754/dbl-64/e_gamma_r.c (__ieee754_gamma_r): Force
        underflow exception for small results.
        * sysdeps/ieee754/flt-32/e_gammaf_r.c (__ieee754_gammaf_r):
        Likewise.
        * sysdeps/ieee754/ldbl-128/e_gammal_r.c (__ieee754_gammal_r):
        Likewise.
        * sysdeps/ieee754/ldbl-128ibm/e_gammal_r.c (__ieee754_gammal_r):
        Likewise.
        * sysdeps/ieee754/ldbl-96/e_gammal_r.c (__ieee754_gammal_r):
        Likewise.
        * math/auto-libm-test-in: Add more tests of tgamma.
        * math/auto-libm-test-out: Regenerated.

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

Summary of changes:
 ChangeLog                                |   16 +
 NEWS                                     |    4 +-
 math/auto-libm-test-in                   |   41 ++
 math/auto-libm-test-out                  | 1000 ++++++++++++++++++++++++++++++
 sysdeps/ieee754/dbl-64/e_gamma_r.c       |    5 +
 sysdeps/ieee754/flt-32/e_gammaf_r.c      |    5 +
 sysdeps/ieee754/ldbl-128/e_gammal_r.c    |    5 +
 sysdeps/ieee754/ldbl-128ibm/e_gammal_r.c |    5 +
 sysdeps/ieee754/ldbl-96/e_gammal_r.c     |    5 +
 9 files changed, 1084 insertions(+), 2 deletions(-)

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[Bug math/18951] tgamma missing underflows

[jsm28 at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=18951

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED
   Target Milestone|---                         |2.23

--- Comment #2 from Joseph Myers <jsm28 at gcc dot gnu.org> ---
Fixed for 2.23.

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