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Re: [PATCH] [BZ #17031][PowerPC64] Fix nearbyintl failure for few inputs
- From: Adhemerval Zanella <azanella at linux dot vnet dot ibm dot com>
- To: libc-alpha at sourceware dot org
- Date: Tue, 17 Jun 2014 10:45:47 -0300
- Subject: Re: [PATCH] [BZ #17031][PowerPC64] Fix nearbyintl failure for few inputs
- Authentication-results: sourceware.org; auth=none
- References: <1402390928-37048-1-git-send-email-raji at linux dot vnet dot ibm dot com> <1402485135-72573-1-git-send-email-raji at linux dot vnet dot ibm dot com>
Thanks Vidya, this patch looks ok. Joseph, do you have any more regards about this
change?
On 11-06-2014 08:12, Rajalakshmi Srinivasaraghavan wrote:
> This patch fixes few failures in nearbyintl() where the fraction part is close
> to 0.5.The new tests added report few extra failures in nearbyint_downward and
> nearbyint_towardzero which is a known issue.
>
> [BZ #17031]
> * sysdeps/ieee754/ldbl-128ibm/s_nearbyintl.c: Consider the low
> double, adjusted for any remainder from the high double.
> * math/libm-test.inc (nearbyint): Add tests.
> (rint): Likewise.
>
> Signed-off-by: Rajalakshmi Srinivasaraghavan <raji@linux.vnet.ibm.com>
> ---
> NEWS | 2 +-
> math/libm-test.inc | 8 ++++++++
> sysdeps/ieee754/ldbl-128ibm/s_nearbyintl.c | 5 +++++
> 3 files changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/NEWS b/NEWS
> index ca3ef63..066a2c8 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -19,7 +19,7 @@ Version 2.20
> 16791, 16796, 16799, 16800, 16815, 16823, 16824, 16831, 16838, 16849,
> 16854, 16876, 16877, 16878, 16882, 16885, 16888, 16890, 16912, 16915,
> 16916, 16917, 16922, 16927, 16928, 16932, 16943, 16958, 16965, 16966,
> - 16967, 16977, 16978, 16984, 16990, 17009, 17042.
> + 16967, 16977, 16978, 16984, 16990, 17009, 17031, 17042.
>
> * The minimum Linux kernel version that this version of the GNU C Library
> can be used with is 2.6.32.
> diff --git a/math/libm-test.inc b/math/libm-test.inc
> index fa8e238..d98d85c 100644
> --- a/math/libm-test.inc
> +++ b/math/libm-test.inc
> @@ -8188,6 +8188,10 @@ static const struct test_f_f_data nearbyint_test_data[] =
> TEST_f_f (nearbyint, 4503599627370496.75L, 4503599627370496.0L, NO_INEXACT_EXCEPTION, 4503599627370497.0L, NO_INEXACT_EXCEPTION, 4503599627370496.0L, NO_INEXACT_EXCEPTION, 4503599627370497.0L, NO_INEXACT_EXCEPTION),
> TEST_f_f (nearbyint, 4503599627370497.5L, 4503599627370497.0L, NO_INEXACT_EXCEPTION, 4503599627370498.0L, NO_INEXACT_EXCEPTION, 4503599627370497.0L, NO_INEXACT_EXCEPTION, 4503599627370498.0L, NO_INEXACT_EXCEPTION),
> # if LDBL_MANT_DIG > 100
> + TEST_f_f (nearbyint, 1024.5000000000001L, 1024.0L, NO_INEXACT_EXCEPTION, 1025.0L, NO_INEXACT_EXCEPTION, 1024.0L, NO_INEXACT_EXCEPTION, 1025.0L, NO_INEXACT_EXCEPTION),
> + TEST_f_f (nearbyint, 1025.5000000000001L, 1025.0L, NO_INEXACT_EXCEPTION, 1026.0L, NO_INEXACT_EXCEPTION, 1025.0L, NO_INEXACT_EXCEPTION, 1026.0L, NO_INEXACT_EXCEPTION),
> + TEST_f_f (nearbyint, -1024.5000000000001L, -1025.0L, NO_INEXACT_EXCEPTION, -1025.0L, NO_INEXACT_EXCEPTION, -1024.0L, NO_INEXACT_EXCEPTION, -1024.0L, NO_INEXACT_EXCEPTION),
> + TEST_f_f (nearbyint, -1025.5000000000001L, -1026.0L, NO_INEXACT_EXCEPTION, -1026.0L, NO_INEXACT_EXCEPTION, -1025.0L, NO_INEXACT_EXCEPTION, -1025.0L, NO_INEXACT_EXCEPTION),
> TEST_f_f (nearbyint, 4503599627370494.5000000000001L, 4503599627370494.0L, NO_INEXACT_EXCEPTION, 4503599627370495.0L, NO_INEXACT_EXCEPTION, 4503599627370494.0L, NO_INEXACT_EXCEPTION, 4503599627370495.0L, NO_INEXACT_EXCEPTION),
> TEST_f_f (nearbyint, 4503599627370495.5000000000001L, 4503599627370495.0L, NO_INEXACT_EXCEPTION, 4503599627370496.0L, NO_INEXACT_EXCEPTION, 4503599627370495.0L, NO_INEXACT_EXCEPTION, 4503599627370496.0L, NO_INEXACT_EXCEPTION),
> TEST_f_f (nearbyint, 4503599627370496.5000000000001L, 4503599627370496.0L, NO_INEXACT_EXCEPTION, 4503599627370497.0L, NO_INEXACT_EXCEPTION, 4503599627370496.0L, NO_INEXACT_EXCEPTION, 4503599627370497.0L, NO_INEXACT_EXCEPTION),
> @@ -8890,6 +8894,10 @@ static const struct test_f_f_data rint_test_data[] =
> TEST_f_f (rint, 4503599627370496.75L, 4503599627370496.0L, INEXACT_EXCEPTION, 4503599627370497.0L, INEXACT_EXCEPTION, 4503599627370496.0L, INEXACT_EXCEPTION, 4503599627370497.0L, INEXACT_EXCEPTION),
> TEST_f_f (rint, 4503599627370497.5L, 4503599627370497.0L, INEXACT_EXCEPTION, 4503599627370498.0L, INEXACT_EXCEPTION, 4503599627370497.0L, INEXACT_EXCEPTION, 4503599627370498.0L, INEXACT_EXCEPTION),
> # if LDBL_MANT_DIG > 100
> + TEST_f_f (rint, 1024.5000000000001L, 1024.0L, INEXACT_EXCEPTION, 1025.0L, INEXACT_EXCEPTION, 1024.0L, INEXACT_EXCEPTION, 1025.0L, INEXACT_EXCEPTION),
> + TEST_f_f (rint, 1025.5000000000001L, 1025.0L, INEXACT_EXCEPTION, 1026.0L, INEXACT_EXCEPTION, 1025.0L, INEXACT_EXCEPTION, 1026.0L, INEXACT_EXCEPTION),
> + TEST_f_f (rint, -1024.5000000000001L, -1025.0L, INEXACT_EXCEPTION, -1025.0L, INEXACT_EXCEPTION, -1024.0L, INEXACT_EXCEPTION, -1024.0L, INEXACT_EXCEPTION),
> + TEST_f_f (rint, -1025.5000000000001L, -1026.0L, INEXACT_EXCEPTION, -1026.0L, INEXACT_EXCEPTION, -1025.0L, INEXACT_EXCEPTION, -1025.0L, INEXACT_EXCEPTION),
> TEST_f_f (rint, 4503599627370494.5000000000001L, 4503599627370494.0L, INEXACT_EXCEPTION, 4503599627370495.0L, INEXACT_EXCEPTION, 4503599627370494.0L, INEXACT_EXCEPTION, 4503599627370495.0L, INEXACT_EXCEPTION),
> TEST_f_f (rint, 4503599627370495.5000000000001L, 4503599627370495.0L, INEXACT_EXCEPTION, 4503599627370496.0L, INEXACT_EXCEPTION, 4503599627370495.0L, INEXACT_EXCEPTION, 4503599627370496.0L, INEXACT_EXCEPTION),
> TEST_f_f (rint, 4503599627370496.5000000000001L, 4503599627370496.0L, INEXACT_EXCEPTION, 4503599627370497.0L, INEXACT_EXCEPTION, 4503599627370496.0L, INEXACT_EXCEPTION, 4503599627370497.0L, INEXACT_EXCEPTION),
> diff --git a/sysdeps/ieee754/ldbl-128ibm/s_nearbyintl.c b/sysdeps/ieee754/ldbl-128ibm/s_nearbyintl.c
> index 4e997a6..8f34604 100644
> --- a/sysdeps/ieee754/ldbl-128ibm/s_nearbyintl.c
> +++ b/sysdeps/ieee754/ldbl-128ibm/s_nearbyintl.c
> @@ -38,6 +38,7 @@ __nearbyintl (long double x)
>
> if (fabs (u.d[0].d) < TWO52)
> {
> + double xh = u.d[0].d;
> double high = u.d[0].d;
> feholdexcept (&env);
> if (high > 0.0)
> @@ -52,6 +53,10 @@ __nearbyintl (long double x)
> high += TWO52;
> if (high == 0.0) high = -0.0;
> }
> + if (u.d[1].d > 0.0 && (xh - high == 0.5))
> + high += 1.0;
> + else if (u.d[1].d < 0.0 && (-(xh - high) == 0.5))
> + high -= 1.0;
> u.d[0].d = high;
> u.d[1].d = 0.0;
> math_force_eval (u.d[0]);