From: Joseph Myers <joseph@codesourcery.com>
Date: Wed, 2 Apr 2014 17:41:02 +0000 (+0000)
Subject: Fix catan, catanh, __ieee754_logf in round-downward mode (bug 16799, bug 16800).
X-Git-Tag: glibc-2.20~655
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a84e78c8b3c4de94b488fdc5321f71feeb99358f;p=thirdparty%2Fglibc.git

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.
---

diff --git a/ChangeLog b/ChangeLog
index 4a514563b29..7e530ef40d1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,21 @@
 2014-04-02  Joseph Myers  <joseph@codesourcery.com>
 
+	[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.
+
 	[BZ #16789]
 	* math/s_clog.c (__clog): Use math_force_eval to ensure underflow
 	instead of using underflowing value in computing result.
diff --git a/NEWS b/NEWS
index 63e9303df2f..c7114da7ab5 100644
--- a/NEWS
+++ b/NEWS
@@ -14,7 +14,7 @@ Version 2.20
   16611, 16613, 16623, 16632, 16634, 16639, 16642, 16648, 16649, 16670,
   16674, 16677, 16680, 16683, 16689, 16695, 16701, 16706, 16707, 16712,
   16713, 16714, 16731, 16739, 16743, 16758, 16759, 16760, 16770, 16786,
-  16789.
+  16789, 16799, 16800.
 
 * Running the testsuite no longer terminates as soon as a test fails.
   Instead, a file tests.sum (xtests.sum from "make xcheck") is generated,
diff --git a/math/libm-test.inc b/math/libm-test.inc
index c6279e75a96..5e6789f9fbe 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 d6552d8b7c3..0cfa92434af 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 41e419d8b0b..b478684652c 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 2ba1298bb6e..7ef9142b0db 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 0ee69a5ba07..0e55aff16cb 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 537bb3e28d5..6410afec310 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 cea9282a545..dd01d16dcda 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)
diff --git a/sysdeps/i386/fpu/libm-test-ulps b/sysdeps/i386/fpu/libm-test-ulps
index 0252d5bbafc..aea6c51b233 100644
--- a/sysdeps/i386/fpu/libm-test-ulps
+++ b/sysdeps/i386/fpu/libm-test-ulps
@@ -383,6 +383,54 @@ ifloat: 1
 ildouble: 1
 ldouble: 1
 
+Function: Real part of "catan_downward":
+double: 1
+float: 1
+idouble: 1
+ifloat: 1
+ildouble: 1
+ldouble: 1
+
+Function: Imaginary part of "catan_downward":
+double: 2
+float: 1
+idouble: 2
+ifloat: 1
+ildouble: 4
+ldouble: 4
+
+Function: Real part of "catan_towardzero":
+double: 1
+float: 1
+idouble: 1
+ifloat: 1
+ildouble: 1
+ldouble: 1
+
+Function: Imaginary part of "catan_towardzero":
+double: 2
+float: 1
+idouble: 2
+ifloat: 1
+ildouble: 4
+ldouble: 4
+
+Function: Real part of "catan_upward":
+double: 1
+float: 1
+idouble: 1
+ifloat: 1
+ildouble: 1
+ldouble: 1
+
+Function: Imaginary part of "catan_upward":
+double: 2
+float: 2
+idouble: 2
+ifloat: 2
+ildouble: 3
+ldouble: 3
+
 Function: Real part of "catanh":
 double: 1
 float: 1
@@ -391,6 +439,54 @@ ifloat: 1
 ildouble: 1
 ldouble: 1
 
+Function: Real part of "catanh_downward":
+double: 2
+float: 1
+idouble: 2
+ifloat: 1
+ildouble: 4
+ldouble: 4
+
+Function: Imaginary part of "catanh_downward":
+double: 1
+float: 1
+idouble: 1
+ifloat: 1
+ildouble: 1
+ldouble: 1
+
+Function: Real part of "catanh_towardzero":
+double: 2
+float: 1
+idouble: 2
+ifloat: 1
+ildouble: 4
+ldouble: 4
+
+Function: Imaginary part of "catanh_towardzero":
+double: 1
+float: 1
+idouble: 1
+ifloat: 1
+ildouble: 1
+ldouble: 1
+
+Function: Real part of "catanh_upward":
+double: 2
+float: 2
+idouble: 2
+ifloat: 2
+ildouble: 4
+ldouble: 4
+
+Function: Imaginary part of "catanh_upward":
+double: 1
+float: 1
+idouble: 1
+ifloat: 1
+ildouble: 1
+ldouble: 1
+
 Function: "cbrt":
 double: 1
 idouble: 1
diff --git a/sysdeps/ieee754/flt-32/e_logf.c b/sysdeps/ieee754/flt-32/e_logf.c
index 7da64896c1e..cf75e11781e 100644
--- a/sysdeps/ieee754/flt-32/e_logf.c
+++ b/sysdeps/ieee754/flt-32/e_logf.c
@@ -41,7 +41,7 @@ __ieee754_logf(float x)
 	k=0;
 	if (ix < 0x00800000) {			/* x < 2**-126  */
 	    if (__builtin_expect((ix&0x7fffffff)==0, 0))
-		return -two25/(x-x);		/* log(+-0)=-inf */
+		return -two25/zero;		/* log(+-0)=-inf */
 	    if (__builtin_expect(ix<0, 0))
 		return (x-x)/(x-x);	/* log(-#) = NaN */
 	    k -= 25; x *= two25; /* subnormal number, scale up x */
diff --git a/sysdeps/x86_64/fpu/libm-test-ulps b/sysdeps/x86_64/fpu/libm-test-ulps
index 1b6ebe21ed7..4ba83a46fd4 100644
--- a/sysdeps/x86_64/fpu/libm-test-ulps
+++ b/sysdeps/x86_64/fpu/libm-test-ulps
@@ -410,6 +410,54 @@ ifloat: 1
 ildouble: 1
 ldouble: 1
 
+Function: Real part of "catan_downward":
+double: 1
+float: 1
+idouble: 1
+ifloat: 1
+ildouble: 1
+ldouble: 1
+
+Function: Imaginary part of "catan_downward":
+double: 2
+float: 2
+idouble: 2
+ifloat: 2
+ildouble: 4
+ldouble: 4
+
+Function: Real part of "catan_towardzero":
+double: 1
+float: 1
+idouble: 1
+ifloat: 1
+ildouble: 1
+ldouble: 1
+
+Function: Imaginary part of "catan_towardzero":
+double: 2
+float: 1
+idouble: 2
+ifloat: 1
+ildouble: 4
+ldouble: 4
+
+Function: Real part of "catan_upward":
+double: 1
+float: 1
+idouble: 1
+ifloat: 1
+ildouble: 1
+ldouble: 1
+
+Function: Imaginary part of "catan_upward":
+double: 3
+float: 3
+idouble: 3
+ifloat: 3
+ildouble: 3
+ldouble: 3
+
 Function: Real part of "catanh":
 double: 1
 float: 1
@@ -422,6 +470,54 @@ Function: Imaginary part of "catanh":
 float: 1
 ifloat: 1
 
+Function: Real part of "catanh_downward":
+double: 2
+float: 2
+idouble: 2
+ifloat: 2
+ildouble: 4
+ldouble: 4
+
+Function: Imaginary part of "catanh_downward":
+double: 1
+float: 2
+idouble: 1
+ifloat: 2
+ildouble: 1
+ldouble: 1
+
+Function: Real part of "catanh_towardzero":
+double: 2
+float: 1
+idouble: 2
+ifloat: 1
+ildouble: 4
+ldouble: 4
+
+Function: Imaginary part of "catanh_towardzero":
+double: 1
+float: 2
+idouble: 1
+ifloat: 2
+ildouble: 1
+ldouble: 1
+
+Function: Real part of "catanh_upward":
+double: 4
+float: 3
+idouble: 4
+ifloat: 3
+ildouble: 4
+ldouble: 4
+
+Function: Imaginary part of "catanh_upward":
+double: 1
+float: 1
+idouble: 1
+ifloat: 1
+ildouble: 1
+ldouble: 1
+
 Function: "cbrt":
 double: 1
 float: 1