[Bug math/16347] New: ldbl-128/e_lgammal_r.c may not be suitable for ldbl-128ibm

[Bug math/16347] New: ldbl-128/e_lgammal_r.c may not be suitable for ldbl-128ibm

[schwab@linux-m68k.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=16347

            Bug ID: 16347
           Summary: ldbl-128/e_lgammal_r.c may not be suitable for
                    ldbl-128ibm
           Product: glibc
           Version: 2.19
            Status: NEW
          Severity: normal
          Priority: P2
         Component: math
          Assignee: unassigned at sourceware dot org
          Reporter: schwab@linux-m68k.org
            Target: powerpc*-*-*

In file included from ../sysdeps/ieee754/ldbl-128ibm/e_lgammal_r.c:2:0:
../sysdeps/ieee754/ldbl-128/e_lgammal_r.c:75:1: warning: floating constant
exceeds range of 'long double' [-Woverflow]
static const long double MAXLGM =
1.0485738685148938358098967157129705071571E4928L;
^
../sysdeps/ieee754/ldbl-128/e_lgammal_r.c:78:1: warning: floating constant
exceeds range of 'long double' [-Woverflow]
static const long double huge = 1.0e4000L;
^

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[Bug math/16347] ldbl-128/e_lgammal_r.c may not be suitable for ldbl-128ibm

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16347

Florian Weimer <fweimer at redhat dot com> changed:

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

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[Bug math/16347] [ldbl-128ibm] ldbl-128/e_lgammal_r.c may not be suitable.

[carlos at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16347

Carlos O'Donell <carlos at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |carlos at redhat dot com
            Summary|ldbl-128/e_lgammal_r.c may  |[ldbl-128ibm]
                   |not be suitable for         |ldbl-128/e_lgammal_r.c may
                   |ldbl-128ibm                 |not be suitable.

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[Bug math/16347] [ldbl-128ibm] ldbl-128/e_lgammal_r.c may not be suitable.

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16347

--- 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  4b84e2471b5f0c9197073395eb77843c6f23e790 (commit)
      from  e27fcd027cbdc2f13bf440177c0434eb9ec3dd28 (commit)

Those revisions listed above that are new to this repository have
not appeared on any other notification email; so we list those
revisions in full, below.

- Log -----------------------------------------------------------------
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=4b84e2471b5f0c9197073395eb77843c6f23e790

commit 4b84e2471b5f0c9197073395eb77843c6f23e790
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Thu Oct 1 17:15:54 2015 +0000

    Fix ldbl-128 / ldbl-128ibm lgamma overflow handling (bug 16347, bug 19046).

    The ldbl-128 / ldbl-128ibm implementation of lgamma has problems with
    its handling of large arguments.  It has an overflow threshold that is
    correct only for ldbl-128, despite being used for both types - with
    diagnostic control macros as a temporary measure to disable warnings
    about that constant overflowing for ldbl-128ibm - and it has a
    calculation that's roughly x * log(x) - x, resulting in overflows for
    arguments that are roughly at most a factor 1/log(threshold) below the
    overflow threshold.

    This patch fixes both issues, using an overflow threshold appropriate
    for the type in question and adding another case for large arguments
    that avoids the possible intermediate overflow.

    Tested for x86_64, x86, mips64 and powerpc.

        [BZ #16347]
        [BZ #19046]
        * sysdeps/ieee754/ldbl-128/e_lgammal_r.c: Do not include
        <libc-internal.h>.
        (MAXLGM): Do not use diagnostic control macros.
        [LDBL_MANT_DIG == 106] (MAXLGM): Change value to overflow
        threshold for ldbl-128ibm.
        (__ieee754_lgammal_r): For large arguments, multiply by log - 1
        instead of multiplying by log then subtracting.
        * math/auto-libm-test-in: Add more tests of lgamma.
        * math/auto-libm-test-out: Regenerated.

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

Summary of changes:
 ChangeLog                              |   12 +
 NEWS                                   |   16 +-
 math/auto-libm-test-in                 |   18 +
 math/auto-libm-test-out                |  642 ++++++++++++++++++++++++++++++++
 sysdeps/ieee754/ldbl-128/e_lgammal_r.c |   13 +-
 5 files changed, 686 insertions(+), 15 deletions(-)

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[Bug math/16347] [ldbl-128ibm] ldbl-128/e_lgammal_r.c may not be suitable.

[jsm28 at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16347

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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