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Re: Fix nearbyintf rounding (bugs 2547, 11365)
On Monday, February 20, 2012 01:05:45 Joseph S. Myers wrote:
> The nearbyintf implementation is substantially the same as rintf (the
> only difference being that nearbyintf does not raise the "inexact"
> exception, so there are feholdexcept/fesetenv pairs). So it has the
> same bugs, and much the same fix as in
> <http://sourceware.org/ml/libc-alpha/2012-02/msg00397.html> applies.
> This fix adds both the tests added for rint and the specific testcases
> from the bug reports for nearbyint.
The testsuite is definitely fine ;)
The rest looks ok - as with rint: I wonder why the double and long double
functions use the similar code you remove,
Andreas
> 2012-02-19 Joseph Myers <joseph@codesourcery.com>
>
> [BZ #2547]
> [BZ #11365]
> * sysdeps/ieee754/flt-32/s_nearbyintf.c (__nearbyintf): Do not
> manipulate bits before adding and subtracting TWO23[sx].
> * math/libm-test.inc (nearbyint_test): Add more tests.
>
> diff --git a/math/libm-test.inc b/math/libm-test.inc
> index 6243e1e..d904543 100644
> --- a/math/libm-test.inc
> +++ b/math/libm-test.inc
> @@ -4632,6 +4632,29 @@ nearbyint_test (void)
> TEST_f_f (nearbyint, 524286.75, 524287.0);
> TEST_f_f (nearbyint, 524288.75, 524289.0);
>
> + TEST_f_f (nearbyint, 1048576.75, 1048577.0);
> + TEST_f_f (nearbyint, 2097152.75, 2097153.0);
> + TEST_f_f (nearbyint, 2492472.75, 2492473.0);
> + TEST_f_f (nearbyint, 2886220.75, 2886221.0);
> + TEST_f_f (nearbyint, 3058792.75, 3058793.0);
> + TEST_f_f (nearbyint, -1048576.75, -1048577.0);
> + TEST_f_f (nearbyint, -2097152.75, -2097153.0);
> + TEST_f_f (nearbyint, -2492472.75, -2492473.0);
> + TEST_f_f (nearbyint, -2886220.75, -2886221.0);
> + TEST_f_f (nearbyint, -3058792.75, -3058793.0);
> +#ifndef TEST_FLOAT
> + TEST_f_f (nearbyint, 70368744177664.75, 70368744177665.0);
> + TEST_f_f (nearbyint, 140737488355328.75, 140737488355329.0);
> + TEST_f_f (nearbyint, 281474976710656.75, 281474976710657.0);
> + TEST_f_f (nearbyint, 562949953421312.75, 562949953421313.0);
> + TEST_f_f (nearbyint, 1125899906842624.75, 1125899906842625.0);
> + TEST_f_f (nearbyint, -70368744177664.75, -70368744177665.0);
> + TEST_f_f (nearbyint, -140737488355328.75, -140737488355329.0);
> + TEST_f_f (nearbyint, -281474976710656.75, -281474976710657.0);
> + TEST_f_f (nearbyint, -562949953421312.75, -562949953421313.0);
> + TEST_f_f (nearbyint, -1125899906842624.75, -1125899906842625.0);
> +#endif
> +
> END (nearbyint);
> }
>
> diff --git a/sysdeps/ieee754/flt-32/s_nearbyintf.c
> b/sysdeps/ieee754/flt-32/s_nearbyintf.c index 04ef9ab..a6d602b 100644
> --- a/sysdeps/ieee754/flt-32/s_nearbyintf.c
> +++ b/sysdeps/ieee754/flt-32/s_nearbyintf.c
> @@ -30,18 +30,12 @@ __nearbyintf(float x)
> {
> fenv_t env;
> int32_t i0,j0,sx;
> - u_int32_t i,i1;
> float w,t;
> GET_FLOAT_WORD(i0,x);
> sx = (i0>>31)&1;
> j0 = ((i0>>23)&0xff)-0x7f;
> if(j0<23) {
> if(j0<0) {
> - if((i0&0x7fffffff)==0) return x;
> - i1 = (i0&0x07fffff);
> - i0 &= 0xfff00000;
> - i0 |= ((i1|-i1)>>9)&0x400000;
> - SET_FLOAT_WORD(x,i0);
> libc_feholdexceptf (&env);
> w = TWO23[sx]+x;
> t = w-TWO23[sx];
> @@ -49,17 +43,11 @@ __nearbyintf(float x)
> GET_FLOAT_WORD(i0,t);
> SET_FLOAT_WORD(t,(i0&0x7fffffff)|(sx<<31));
> return t;
> - } else {
> - i = (0x007fffff)>>j0;
> - if((i0&i)==0) return x; /* x is integral */
> - i>>=1;
> - if((i0&i)!=0) i0 = (i0&(~i))|((0x100000)>>j0);
> }
> } else {
> if(__builtin_expect(j0==0x80, 0)) return x+x; /* inf or NaN */
> else return x; /* x is integral */
> }
> - SET_FLOAT_WORD(x,i0);
> libc_feholdexceptf (&env);
> w = TWO23[sx]+x;
> t = w-TWO23[sx];
--
Andreas Jaeger aj@{suse.com,opensuse.org} Twitter/Identica: jaegerandi
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