11 files changed, 101 insertions, 8 deletions
diff --git a/ChangeLog b/ChangeLog
index a7a9185e85..c035c9f882 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,20 @@
+2014-05-23  Joseph Myers  <joseph@codesourcery.com>
+
+	[BZ #16977]
+	* sysdeps/i386/fpu/e_log10.S (__ieee754_log10): Take absolute
+	value when x - 1 is zero.
+	* sysdeps/i386/fpu/e_log10f.S (__ieee754_log10f): Likewise.
+	* sysdeps/i386/fpu/e_log10l.S (__ieee754_log10l): Likewise.
+	* sysdeps/ieee754/ldbl-128/e_log10l.c (__ieee754_log10l): Return
+	0.0L for an argument of 1.0L.
+	* sysdeps/ieee754/ldbl-128ibm/e_log10l.c (__ieee754_log10l):
+	Likewise.
+	* sysdeps/x86_64/fpu/e_log10l.S (__ieee754_log10l): Take absolute
+	value when x - 1 is zero.
+	* math/libm-test.inc (log10_test): Use ALL_RM_TEST.
+	* sysdeps/i386/fpu/libm-test-ulps: Update.
+	* sysdeps/x86_64/fpu/libm-test-ulps: Likewise.
+
 2014-05-23  Rasmus Villemoes  <rv@rasmusvillemoes.dk>
 
 	* manual/filesys.texi (Scanning Directory Content): Fix prototype of
diff --git a/NEWS b/NEWS
index 8aaf2f4cb5..1c44fd6e2d 100644
--- a/NEWS
+++ b/NEWS
@@ -18,7 +18,7 @@ Version 2.20
   16760, 16770, 16786, 16789, 16791, 16799, 16800, 16815, 16823, 16824,
   16831, 16838, 16849, 16854, 16876, 16877, 16885, 16888, 16890, 16912,
   16915, 16916, 16917, 16922, 16927, 16928, 16932, 16943, 16958, 16966,
-  16967, 16965.
+  16967, 16965, 16977.
 
 * The minimum Linux kernel version that this version of the GNU C Library
   can be used with is 2.6.32.
diff --git a/math/libm-test.inc b/math/libm-test.inc
index de7bc8ad94..0d467a2195 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -7798,9 +7798,7 @@ static const struct test_f_f_data log10_test_data[] =
 static void
 log10_test (void)
 {
-  START (log10, 0);
-  RUN_TEST_LOOP_f_f (log10, log10_test_data, );
-  END;
+  ALL_RM_TEST (log10, 0, log10_test_data, RUN_TEST_LOOP_f_f, END);
 }
 
 
diff --git a/sysdeps/i386/fpu/e_log10.S b/sysdeps/i386/fpu/e_log10.S
index ce6a81abb6..17277084ca 100644
--- a/sysdeps/i386/fpu/e_log10.S
+++ b/sysdeps/i386/fpu/e_log10.S
@@ -46,7 +46,13 @@ ENTRY(__ieee754_log10)
 	fnstsw			// x-1 : x : log10(2)
 	andb	$0x45, %ah
 	jz	2f
-	fstp	%st(1)		// x-1 : log10(2)
+	fxam
+	fnstsw
+	andb	$0x45, %ah
+	cmpb	$0x40, %ah
+	jne	5f
+	fabs			// log10(1) is +0 in all rounding modes.
+5:	fstp	%st(1)		// x-1 : log10(2)
 	fyl2xp1			// log10(x)
 	ret
 
diff --git a/sysdeps/i386/fpu/e_log10f.S b/sysdeps/i386/fpu/e_log10f.S
index 8c20723555..72a3b88251 100644
--- a/sysdeps/i386/fpu/e_log10f.S
+++ b/sysdeps/i386/fpu/e_log10f.S
@@ -47,7 +47,13 @@ ENTRY(__ieee754_log10f)
 	fnstsw			// x-1 : x : log10(2)
 	andb	$0x45, %ah
 	jz	2f
-	fstp	%st(1)		// x-1 : log10(2)
+	fxam
+	fnstsw
+	andb	$0x45, %ah
+	cmpb	$0x40, %ah
+	jne	5f
+	fabs			// log10(1) is +0 in all rounding modes.
+5:	fstp	%st(1)		// x-1 : log10(2)
 	fyl2xp1			// log10(x)
 	ret
 
diff --git a/sysdeps/i386/fpu/e_log10l.S b/sysdeps/i386/fpu/e_log10l.S
index cde987b137..45b9c6d21d 100644
--- a/sysdeps/i386/fpu/e_log10l.S
+++ b/sysdeps/i386/fpu/e_log10l.S
@@ -48,7 +48,13 @@ ENTRY(__ieee754_log10l)
 	fnstsw			// x-1 : x : log10(2)
 	andb	$0x45, %ah
 	jz	2f
-	fstp	%st(1)		// x-1 : log10(2)
+	fxam
+	fnstsw
+	andb	$0x45, %ah
+	cmpb	$0x40, %ah
+	jne	5f
+	fabs			// log10(1) is +0 in all rounding modes.
+5:	fstp	%st(1)		// x-1 : log10(2)
 	fyl2xp1			// log10(x)
 	ret
 
diff --git a/sysdeps/i386/fpu/libm-test-ulps b/sysdeps/i386/fpu/libm-test-ulps
index 946cad489b..1e89284455 100644
--- a/sysdeps/i386/fpu/libm-test-ulps
+++ b/sysdeps/i386/fpu/libm-test-ulps
@@ -1536,6 +1536,30 @@ Function: "log10":
 ildouble: 1
 ldouble: 1
 
+Function: "log10_downward":
+double: 1
+float: 1
+idouble: 1
+ifloat: 1
+ildouble: 1
+ldouble: 1
+
+Function: "log10_towardzero":
+double: 1
+float: 1
+idouble: 1
+ifloat: 1
+ildouble: 1
+ldouble: 1
+
+Function: "log10_upward":
+double: 1
+float: 1
+idouble: 1
+ifloat: 1
+ildouble: 1
+ldouble: 1
+
 Function: "log1p":
 ildouble: 1
 ldouble: 1
diff --git a/sysdeps/ieee754/ldbl-128/e_log10l.c b/sysdeps/ieee754/ldbl-128/e_log10l.c
index b403f815fb..618255f2fa 100644
--- a/sysdeps/ieee754/ldbl-128/e_log10l.c
+++ b/sysdeps/ieee754/ldbl-128/e_log10l.c
@@ -193,6 +193,9 @@ __ieee754_log10l (long double x)
   if (hx >= 0x7fff000000000000LL)
     return (x + x);
 
+  if (x == 1.0L)
+    return 0.0L;
+
 /* separate mantissa from exponent */
 
 /* Note, frexp is used so that denormal numbers
diff --git a/sysdeps/ieee754/ldbl-128ibm/e_log10l.c b/sysdeps/ieee754/ldbl-128ibm/e_log10l.c
index 1a6a4a0fa3..7477791b77 100644
--- a/sysdeps/ieee754/ldbl-128ibm/e_log10l.c
+++ b/sysdeps/ieee754/ldbl-128ibm/e_log10l.c
@@ -195,6 +195,9 @@ __ieee754_log10l (long double x)
   if (hx >= 0x7ff0000000000000LL)
     return (x + x);
 
+  if (x == 1.0L)
+    return 0.0L;
+
 /* separate mantissa from exponent */
 
 /* Note, frexp is used so that denormal numbers
diff --git a/sysdeps/x86_64/fpu/e_log10l.S b/sysdeps/x86_64/fpu/e_log10l.S
index 6c07024c19..2607ad199b 100644
--- a/sysdeps/x86_64/fpu/e_log10l.S
+++ b/sysdeps/x86_64/fpu/e_log10l.S
@@ -46,7 +46,13 @@ ENTRY(__ieee754_log10l)
 	fnstsw			// x-1 : x : log10(2)
 	andb	$0x45, %ah
 	jz	2f
-	fstp	%st(1)		// x-1 : log10(2)
+	fxam
+	fnstsw
+	andb	$0x45, %ah
+	cmpb	$0x40, %ah
+	jne	5f
+	fabs			// log10(1) is +0 in all rounding modes.
+5:	fstp	%st(1)		// x-1 : log10(2)
 	fyl2xp1			// log10(x)
 	ret
 
diff --git a/sysdeps/x86_64/fpu/libm-test-ulps b/sysdeps/x86_64/fpu/libm-test-ulps
index d47287696c..bb549d2b0d 100644
--- a/sysdeps/x86_64/fpu/libm-test-ulps
+++ b/sysdeps/x86_64/fpu/libm-test-ulps
@@ -1611,6 +1611,30 @@ ifloat: 2
 ildouble: 1
 ldouble: 1
 
+Function: "log10_downward":
+double: 1
+float: 1
+idouble: 1
+ifloat: 1
+ildouble: 1
+ldouble: 1
+
+Function: "log10_towardzero":
+double: 1
+float: 1
+idouble: 1
+ifloat: 1
+ildouble: 1
+ldouble: 1
+
+Function: "log10_upward":
+double: 1
+float: 1
+idouble: 1
+ifloat: 1
+ildouble: 1
+ldouble: 1
+
 Function: "log1p":
 float: 1
 ifloat: 1