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Fix catan, catanh, __ieee754_logf in round-downward mode (bug 16799, bug 16800).

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This patch fixes incorrect results from catan and catanh of certain
special inputs in round-downward mode (bug 16799), and incorrect
results of __ieee754_logf (+/-0) in round-downward mode (bug 16800)
that show up through catan/catanh when tested in all rounding modes,
but not directly in the testing for logf because the bug gets hidden
by the wrappers.

Both bugs involve a zero that should be +0 being -0 instead: one
computed as (1-x)*(1+x) in the catan/catanh case, and one as (x-x) in
the logf case.  The fixes ensure positive zero is used.  Testing of
catan and catanh in all rounding modes is duly enabled.

I expect there are various other bugs in special cases in __ieee754_*
functions that are normally hidden by the wrappers but would show up
for testing with -lieee (or in future with -fno-math-errno if we
replace -lieee and _LIB_VERSION with compile-time redirection to new
*_noerrno symbol names).

Tested x86_64 and x86 and ulps updated accordingly.

	[BZ #16799]
	[BZ #16800]
	* math/s_catan.c (__catan): Avoid passing -0 denominator to atan2
	with 0 numerator.
	* math/s_catanf.c (__catanf): Likewise.
	* math/s_catanh.c (__catanh): Likewise.
	* math/s_catanhf.c (__catanhf): Likewise.
	* math/s_catanhl.c (__catanhl): Likewise.
	* math/s_catanl.c (__catanl): Likewise.
	* sysdeps/ieee754/flt-32/e_logf.c (__ieee754_logf): Always divide
	by positive zero when computing -Inf result.
	* math/libm-test.inc (catan_test): Use ALL_RM_TEST.
	(catanh_test): Likewise.
	* sysdeps/i386/fpu/libm-test-ulps: Update.
	* sysdeps/x86_64/fpu/libm-test-ulps: Likewise.
This commit is contained in:
Joseph Myers
2014-04-02 17:41:02 +00:00
parent 6f05bafeba
commit a84e78c8b3
12 changed files with 242 additions and 14 deletions
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8
math/libm-test.inc
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@ -5239,9 +5239,7 @@ static const struct test_c_c_data catan_test_data[] =
static void
catan_test (void)
{
START (catan, 0);
RUN_TEST_LOOP_c_c (catan, catan_test_data, );
END_COMPLEX;
ALL_RM_TEST (catan, 0, catan_test_data, RUN_TEST_LOOP_c_c, END_COMPLEX);
}
static const struct test_c_c_data catanh_test_data[] =
@ -5746,9 +5744,7 @@ static const struct test_c_c_data catanh_test_data[] =
static void
catanh_test (void)
{
START (catanh, 0);
RUN_TEST_LOOP_c_c (catanh, catanh_test_data, );
END_COMPLEX;
ALL_RM_TEST (catanh, 0, catanh_test_data, RUN_TEST_LOOP_c_c, END_COMPLEX);
}
static const struct test_f_f_data cbrt_test_data[] =