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

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.

7 files changed, 32 insertions, 12 deletions

diff --git a/math/libm-test.inc b/math/libm-test.inc
index c6279e75a9..5e6789f9fb 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -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[] =
diff --git a/math/s_catan.c b/math/s_catan.c
index d6552d8b7c..0cfa92434a 100644
--- a/math/s_catan.c
+++ b/math/s_catan.c
@@ -89,7 +89,11 @@ __catan (__complex__ double x)
 	    }
 
 	  if (absy < DBL_EPSILON / 2.0)
-	    den = (1.0 - absx) * (1.0 + absx);
+	    {
+	      den = (1.0 - absx) * (1.0 + absx);
+	      if (den == -0.0)
+		den = 0.0;
+	    }
 	  else if (absx >= 1.0)
 	    den = (1.0 - absx) * (1.0 + absx) - absy * absy;
 	  else if (absx >= 0.75 || absy >= 0.5)
diff --git a/math/s_catanf.c b/math/s_catanf.c
index 41e419d8b0..b478684652 100644
--- a/math/s_catanf.c
+++ b/math/s_catanf.c
@@ -90,7 +90,11 @@ __catanf (__complex__ float x)
 	    }
 
 	  if (absy < FLT_EPSILON / 2.0f)
-	    den = (1.0f - absx) * (1.0f + absx);
+	    {
+	      den = (1.0f - absx) * (1.0f + absx);
+	      if (den == -0.0f)
+		den = 0.0f;
+	    }
 	  else if (absx >= 1.0f)
 	    den = (1.0f - absx) * (1.0f + absx) - absy * absy;
 	  else if (absx >= 0.75f || absy >= 0.5f)
diff --git a/math/s_catanh.c b/math/s_catanh.c
index 2ba1298bb6..7ef9142b0d 100644
--- a/math/s_catanh.c
+++ b/math/s_catanh.c
@@ -110,7 +110,11 @@ __catanh (__complex__ double x)
 	    }
 
 	  if (absy < DBL_EPSILON / 2.0)
-	    den = (1.0 - absx) * (1.0 + absx);
+	    {
+	      den = (1.0 - absx) * (1.0 + absx);
+	      if (den == -0.0)
+		den = 0.0;
+	    }
 	  else if (absx >= 1.0)
 	    den = (1.0 - absx) * (1.0 + absx) - absy * absy;
 	  else if (absx >= 0.75 || absy >= 0.5)
diff --git a/math/s_catanhf.c b/math/s_catanhf.c
index 0ee69a5ba0..0e55aff16c 100644
--- a/math/s_catanhf.c
+++ b/math/s_catanhf.c
@@ -112,7 +112,11 @@ __catanhf (__complex__ float x)
 	    }
 
 	  if (absy < FLT_EPSILON / 2.0f)
-	    den = (1.0f - absx) * (1.0f + absx);
+	    {
+	      den = (1.0f - absx) * (1.0f + absx);
+	      if (den == -0.0f)
+		den = 0.0f;
+	    }
 	  else if (absx >= 1.0f)
 	    den = (1.0f - absx) * (1.0f + absx) - absy * absy;
 	  else if (absx >= 0.75f || absy >= 0.5f)
diff --git a/math/s_catanhl.c b/math/s_catanhl.c
index 537bb3e28d..6410afec31 100644
--- a/math/s_catanhl.c
+++ b/math/s_catanhl.c
@@ -118,7 +118,11 @@ __catanhl (__complex__ long double x)
 	    }
 
 	  if (absy < LDBL_EPSILON / 2.0L)
-	    den = (1.0L - absx) * (1.0L + absx);
+	    {
+	      den = (1.0L - absx) * (1.0L + absx);
+	      if (den == -0.0L)
+		den = 0.0L;
+	    }
 	  else if (absx >= 1.0L)
 	    den = (1.0L - absx) * (1.0L + absx) - absy * absy;
 	  else if (absx >= 0.75L || absy >= 0.5L)
diff --git a/math/s_catanl.c b/math/s_catanl.c
index cea9282a54..dd01d16dcd 100644
--- a/math/s_catanl.c
+++ b/math/s_catanl.c
@@ -97,7 +97,11 @@ __catanl (__complex__ long double x)
 	    }
 
 	  if (absy < LDBL_EPSILON / 2.0L)
-	    den = (1.0L - absx) * (1.0L + absx);
+	    {
+	      den = (1.0L - absx) * (1.0L + absx);
+	      if (den == -0.0L)
+		den = 0.0L;
+	    }
 	  else if (absx >= 1.0L)
 	    den = (1.0L - absx) * (1.0L + absx) - absy * absy;
 	  else if (absx >= 0.75L || absy >= 0.5L)