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authorJoseph Myers <joseph@codesourcery.com>2015-02-26 12:57:21 +0000
committerJoseph Myers <joseph@codesourcery.com>2015-02-26 12:57:21 +0000
commit524ae9ea2e3ae9f5bf5d655595fda827e9dc50a1 (patch)
tree363ab7a9bab473dc18c22b1179d8b549d8497f80 /math
parent23d43090e0b275e47e09e859823e965a1eb323dc (diff)
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Fix ldbl-128ibm ilogbl near powers of 2 (bug 18029).
The ldbl-128ibm implementation of ilogbl 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, ilogbl (0x1.ffffffffffffffp1L) returns 2 but should return 1. (This is similar to (fixed) bug 16740 for frexpl, and bug 18030 for logbl.) This patch adds checks for that case. Tested for powerpc. [BZ #18029] * sysdeps/ieee754/ldbl-128ibm/e_ilogbl.c (__ieee754_ilogbl): Adjust exponent of power of 2 down when low part has opposite sign. * math/libm-test.inc (ilogb_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 b3396b6a79..6045764fd3 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -7219,6 +7219,11 @@ static const struct test_f_i_data ilogb_test_data[] =
TEST_f_i (ilogb, 1024, 10, NO_INEXACT_EXCEPTION),
TEST_f_i (ilogb, -2000, 10, NO_INEXACT_EXCEPTION),
+#if defined TEST_LDOUBLE && LDBL_MANT_DIG >= 57
+ TEST_f_i (ilogb, 0x1.ffffffffffffffp1L, 1, NO_INEXACT_EXCEPTION),
+ TEST_f_i (ilogb, -0x1.ffffffffffffffp1L, 1, NO_INEXACT_EXCEPTION),
+#endif
+
/* ilogb (0.0) == FP_ILOGB0 plus invalid exception */
TEST_f_i (ilogb, 0.0, FP_ILOGB0, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
/* ilogb (qNaN) == FP_ILOGBNAN plus invalid exception */