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| author | Joseph Myers <joseph@codesourcery.com> | 2015-02-26 15:13:22 +0000 |
|---|---|---|
| committer | Joseph Myers <joseph@codesourcery.com> | 2015-02-26 15:14:58 +0000 |
| commit | 380bd0fd2418f8988217de950f8b8ff18af0cb2b (patch) | |
| tree | abb55a322fc5e1b829761d91a23510ecfc6bf1ee /math | |
| parent | 4a28f4d55a6cc33474c0792fe93b5942d81bf185 (diff) | |
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Fix ldbl-128ibm logbl near powers of 2 (bug 18030).
The ldbl-128ibm implementation of logbl produces incorrect results
when the high part of the argument is a power of 2 and the low part a
nonzero number with the opposite sign (and so the returned exponent
should be 1 less than that of the high part). For example, logbl
(0x1.ffffffffffffffp1L) returns 2 but should return 1. (This is
similar to (fixed) bug 16740 for frexpl, and (fixed) bug 18029 for
ilogbl.) This patch adds checks for that case.
Tested for powerpc.
[BZ #18030]
* sysdeps/ieee754/ldbl-128ibm/s_logbl.c (__logbl): Adjust exponent
of power of 2 down when low part has opposite sign.
* math/libm-test.inc (logb_test_data): Add more tests.
Diffstat (limited to 'math')
| -rw-r--r-- | math/libm-test.inc | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/math/libm-test.inc b/math/libm-test.inc index 6045764fd3..7acd29bc13 100644 --- a/math/libm-test.inc +++ b/math/libm-test.inc @@ -7868,6 +7868,11 @@ static const struct test_f_f_data logb_test_data[] = TEST_f_f (logb, 0x1p-16400L, -16400, NO_INEXACT_EXCEPTION), TEST_f_f (logb, 0x.00000000001p-16382L, -16426, NO_INEXACT_EXCEPTION), #endif + +#if defined TEST_LDOUBLE && LDBL_MANT_DIG >= 57 + TEST_f_f (logb, 0x1.ffffffffffffffp1L, 1, NO_INEXACT_EXCEPTION), + TEST_f_f (logb, -0x1.ffffffffffffffp1L, 1, NO_INEXACT_EXCEPTION), +#endif }; static void |