[Bug math/19079] New: dbl-64/wordsize-64 lround based on llround incorrect for ILP32

[Bug math/19079] New: dbl-64/wordsize-64 lround based on llround incorrect for ILP32

[jsm28 at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=19079

            Bug ID: 19079
           Summary: dbl-64/wordsize-64 lround based on llround incorrect
                    for ILP32
           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: ---

The implementation of lround in dbl-64/wordsize-64 as an alias or wrapper for
llround is always incorrect when long is not 64-bit, because it misses required
exceptions in overflow cases.  E.g., for MIPS n32 modified to use this code:

Failure: lround (0x1p31): Exception "Invalid operation" not set
Failure: lround (0x1p32): Exception "Invalid operation" not set
Failure: lround (0x1p33): Exception "Invalid operation" not set
Failure: lround (-0x1p32): Exception "Invalid operation" not set
Failure: lround (-0x1p33): Exception "Invalid operation" not set
Failure: lround (-0x1p63): Exception "Invalid operation" not set
Failure: lround_downward (0x1p31): Exception "Invalid operation" not set
Failure: lround_downward (0x1p32): Exception "Invalid operation" not set
Failure: lround_downward (0x1p33): Exception "Invalid operation" not set
Failure: lround_downward (-0x1p32): Exception "Invalid operation" not set
Failure: lround_downward (-0x1p33): Exception "Invalid operation" not set
Failure: lround_downward (-0x1p63): Exception "Invalid operation" not set
Failure: lround_towardzero (0x1p31): Exception "Invalid operation" not set
Failure: lround_towardzero (0x1p32): Exception "Invalid operation" not set
Failure: lround_towardzero (0x1p33): Exception "Invalid operation" not set
Failure: lround_towardzero (-0x1p32): Exception "Invalid operation" not set
Failure: lround_towardzero (-0x1p33): Exception "Invalid operation" not set
Failure: lround_towardzero (-0x1p63): Exception "Invalid operation" not set
Failure: lround_upward (0x1p31): Exception "Invalid operation" not set
Failure: lround_upward (0x1p32): Exception "Invalid operation" not set
Failure: lround_upward (0x1p33): Exception "Invalid operation" not set
Failure: lround_upward (-0x1p32): Exception "Invalid operation" not set
Failure: lround_upward (-0x1p33): Exception "Invalid operation" not set
Failure: lround_upward (-0x1p63): Exception "Invalid operation" not set

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[Bug math/19079] dbl-64/wordsize-64 lround based on llround incorrect for ILP32

[jsm28 at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=19079

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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[Bug math/19079] dbl-64/wordsize-64 lround based on llround incorrect for ILP32

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=19079

--- Comment #1 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
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       via  b75bc69cdfe5247b2156ce249518f1c1df4d797d (commit)
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https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=b75bc69cdfe5247b2156ce249518f1c1df4d797d

commit b75bc69cdfe5247b2156ce249518f1c1df4d797d
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Wed Oct 7 00:40:12 2015 +0000

    Don't use dbl-64/wordsize-64 lround based on llround for ILP32 (bug 19079).

    The implementation of lround in dbl-64/wordsize-64 as an alias or
    wrapper for llround is always incorrect when long is not 64-bit,
    because it misses required exceptions in overflow cases, as shown by
    my recently added tests.  This patch removes that alias / wrapper in
    the non-LP64 case, together with the REGISTER_CAST_INT32_TO_INT64
    macro, restoring the previous version of lround for dbl-64/wordsize-64
    (newly conditioned on !_LP64).

    Tested for x86_64, and for mips64 with use of dbl-64/wordsize-64
    enabled.

        [BZ #19079]
        * sysdeps/ieee754/dbl-64/wordsize-64/s_lround.c: Restore previous
        file, conditioned on [!_LP64].
        * sysdeps/ieee754/dbl-64/wordsize-64/s_llround.c
        [!_LP64] (__lround): Do not define as function or alias.
        [!_LP64] (lround): Likewise.
        [!_LP64] (__lroundl): Likewise.
        [!_LP64] (lroundl): Likewise.
        * sysdeps/tile/sysdep.h (REGISTER_CAST_INT32_TO_INT64): Remove
        macro.
        * sysdeps/x86_64/x32/sysdep.h (REGISTER_CAST_INT32_TO_INT64):
        Likewise.

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

Summary of changes:
 ChangeLog                                      |   15 +++++
 NEWS                                           |    2 +-
 sysdeps/ieee754/dbl-64/wordsize-64/s_llround.c |   17 +-----
 sysdeps/ieee754/dbl-64/wordsize-64/s_lround.c  |   70 +++++++++++++++++++++++-
 sysdeps/tile/sysdep.h                          |    4 --
 sysdeps/x86_64/x32/sysdep.h                    |    4 --
 6 files changed, 87 insertions(+), 25 deletions(-)

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