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[Bug math/22665] alpha: ceil and floor raise inexact exceptions


https://sourceware.org/bugzilla/show_bug.cgi?id=22665

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- Log -----------------------------------------------------------------
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=b0a4eca2fcfe2a6bc3cbb3951241c4facc887670

commit b0a4eca2fcfe2a6bc3cbb3951241c4facc887670
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Wed Jan 3 17:03:48 2018 -0200

    alpha: Remove s_trunc{f} implementation (BZ#22666)

    As discussed in libc-alpha [1], alpha trunc{f} implementation uses
    addt/suc and subt/suc and although the Alpha Architecture
    Handbook version 3 states that that ADDx SUBx OUTPUT Exceptions
    (B.3 Mapping to IEEE Standard) should not generate Inexact if INE
    bit is set, the Alpha 21264 [2] chip manual (A.8 IEEE Floating-Point
    Conformance) states that ADDx SUBx OUTPUT does generate inexact
    exception for inexact result regardless.

    As Joseph noted [3] to correctly fix it on alpha we need to either
    avoid the instruction or avoid any inexact bit from it being set
    on return from the function (while preserving the inexact bit that
    might be set on the entry to the function).  The later will result
    mf_fpcr followed by a mt_fpcr to get and set the fpcr which will
    defeat the optimization itself.

    So the patch just remove the alpha optimized and rely on generic
    implementation.  It fixes the math/test-*-{trunc} on alpha.

            [BZ #15479]
            [BZ #22666]
            * sysdeps/alpha/fpu/s_trunc.c: Remove file.
            * sysdeps/alpha/fpu/s_truncf.c: Likewise.

    [1] https://sourceware.org/ml/libc-alpha/2018-01/msg00114.html
    [2] https://www.star.bnl.gov/public/daq/HARDWARE/21264_data_sheet.pdf
    [3] https://sourceware.org/ml/libc-alpha/2018-01/msg00086.html

    Signed-off-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=4854ddd874d4aafb1ac21f551abda58ac4f9144d

commit 4854ddd874d4aafb1ac21f551abda58ac4f9144d
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Wed Jan 3 15:36:53 2018 -0200

    alpha: Remove s_ceil{f} and s_floor{f} implementation (BZ#22665)

    As discussed in libc-alpha [1], alpha ceil{f} and floor{f}
    implementation uses cvttq/svm and although the Alpha Architecture
    Handbook version 3 states that that CVTfi OUTPUT Exceptions
    (B.3 Mapping to IEEE Standard) should not generate Inexact if INE
    bit is set on fpcr, the Alpha 21264 [1] chip manual (A.8 IEEE
    Floating-Point Conformance) states that CVTfi and CVTif OUTPUT
    does generate inexact exception for inexact result regardless.

    As Joseph noted [2] to correctly fix it on alpha we need to either
    avoid the instruction or avoid any inexact bit from it being set
    on return from the function (while preserving the inexact bit that
    might be set on the entry to the function).  The later will result
    mf_fpcr followed by a mt_fpcr to get and set the fpcr which will
    defeat the optimization itself.

    So the patch just remove the alpha optimized and rely on generic
    implementation.  It fixes the math/test-*-{ceil,floor} on alpha.

        [BZ #15479]
        [BZ #22665]
        * sysdeps/alpha/fpu/s_ceil.c: Remove file.
        * sysdeps/alpha/fpu/s_ceilf.c: Likewise.
        * sysdeps/alpha/fpu/s_floor.c: Likewise.
        * sysdeps/alpha/fpu/s_floorf.c: Likewise.

    [1] https://www.star.bnl.gov/public/daq/HARDWARE/21264_data_sheet.pdf
    [2] https://sourceware.org/ml/libc-alpha/2018-01/msg00086.html

    Signed-off-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>

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

Summary of changes:
 ChangeLog                    |   14 ++++++++++
 sysdeps/alpha/fpu/s_ceil.c   |   50 --------------------------------------
 sysdeps/alpha/fpu/s_ceilf.c  |   54 -----------------------------------------
 sysdeps/alpha/fpu/s_floor.c  |   51 --------------------------------------
 sysdeps/alpha/fpu/s_floorf.c |   55 ------------------------------------------
 sysdeps/alpha/fpu/s_trunc.c  |   45 ----------------------------------
 sysdeps/alpha/fpu/s_truncf.c |   44 ---------------------------------
 7 files changed, 14 insertions(+), 299 deletions(-)
 delete mode 100644 sysdeps/alpha/fpu/s_ceil.c
 delete mode 100644 sysdeps/alpha/fpu/s_ceilf.c
 delete mode 100644 sysdeps/alpha/fpu/s_floor.c
 delete mode 100644 sysdeps/alpha/fpu/s_floorf.c
 delete mode 100644 sysdeps/alpha/fpu/s_trunc.c
 delete mode 100644 sysdeps/alpha/fpu/s_truncf.c

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