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authorJoseph Myers <joseph@codesourcery.com>2015-02-26 15:13:22 +0000
committerJoseph Myers <joseph@codesourcery.com>2015-02-26 15:14:58 +0000
commit380bd0fd2418f8988217de950f8b8ff18af0cb2b (patch)
treeabb55a322fc5e1b829761d91a23510ecfc6bf1ee /math
parent4a28f4d55a6cc33474c0792fe93b5942d81bf185 (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.inc5
1 files changed, 5 insertions, 0 deletions
diff --git a/math/libm-test.inc b/math/libm-test.inc
index 6045764..7acd29b 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