Fix atanhl missing underflows (bug 16352).

Similar to various other bugs in this area, some atanh implementations
do not raise the underflow exception for subnormal arguments, when the
result is tiny and inexact.  This patch forces the exception in a
similar way to previous fixes.  (No change in this regard is needed
for the i386 implementation; special handling to force underflows in
these cases will only be needed there when the spurious underflows,
bug 18049, get fixed.)

Tested for x86_64, x86, powerpc and mips64.

	[BZ #16352]
	* sysdeps/i386/fpu/e_atanh.S (dbl_min): New object.
	(__ieee754_atanh): Force underflow exception for results with
	small absolute value.
	* sysdeps/i386/fpu/e_atanhf.S (flt_min): New object.
	(__ieee754_atanhf): Force underflow exception for results with
	small absolute value.
	* sysdeps/ieee754/dbl-64/e_atanh.c: Include <float.h>.
	(__ieee754_atanh): Force underflow exception for results with
	small absolute value.
	* sysdeps/ieee754/flt-32/e_atanhf.c: Include <float.h>.
	(__ieee754_atanhf): Force underflow exception for results with
	small absolute value.
	* sysdeps/ieee754/ldbl-128/e_atanhl.c: Include <float.h>.
	(__ieee754_atanhl): Force underflow exception for results with
	small absolute value.
	* sysdeps/ieee754/ldbl-128ibm/e_atanhl.c: Include <float.h>.
	(__ieee754_atanhl): Force underflow exception for results with
	small absolute value.
	* sysdeps/ieee754/ldbl-96/e_atanhl.c: Include <float.h>.
	(__ieee754_atanhl): Force underflow exception for results with
	small absolute value.
	* math/auto-libm-test-in: Do not allow missing underflow
	exceptions from atanh.
	* math/auto-libm-test-out: Regenerated.

7 files changed, 76 insertions, 4 deletions

diff --git a/sysdeps/i386/fpu/e_atanh.S b/sysdeps/i386/fpu/e_atanh.S
index 16e149b..90d19bc 100644
--- a/sysdeps/i386/fpu/e_atanh.S
+++ b/sysdeps/i386/fpu/e_atanh.S
@@ -35,6 +35,13 @@ limit:	.double 0.29
 ln2_2:	.tfloat 0.3465735902799726547086160
 	ASM_SIZE_DIRECTIVE(ln2_2)
 
+	.section .rodata.cst8,"aM",@progbits,8
+
+	.p2align 3
+	.type dbl_min,@object
+dbl_min:	.byte 0, 0, 0, 0, 0, 0, 0x10, 0
+	ASM_SIZE_DIRECTIVE(dbl_min)
+
 #ifdef PIC
 #define MO(op) op##@GOTOFF(%edx)
 #else
@@ -81,7 +88,18 @@ ENTRY(__ieee754_atanh)
 	sahf
 	jae	4f
 	fyl2xp1			// 0.5*ln2*ld(1+2*|x|+(2*|x|^2)/(1-|x|))
-	jecxz	3f
+	fcoml	MO(dbl_min)
+	fnstsw
+	sahf
+	jae	8f
+	subl	$8, %esp
+	cfi_adjust_cfa_offset (8)
+	fld	%st(0)
+	fmul	%st(0)
+	fstpl	(%esp)
+	addl	$8, %esp
+	cfi_adjust_cfa_offset (-8)
+8:	jecxz	3f
 	fchs			// 0.5*ln2*ld(1+2*x+(2*x^2)/(1-x))
 3:	ret
 
diff --git a/sysdeps/i386/fpu/e_atanhf.S b/sysdeps/i386/fpu/e_atanhf.S
index 0021d9c..1c8969e 100644
--- a/sysdeps/i386/fpu/e_atanhf.S
+++ b/sysdeps/i386/fpu/e_atanhf.S
@@ -36,6 +36,13 @@ limit:	.double 0.29
 ln2_2:	.tfloat 0.3465735902799726547086160
 	ASM_SIZE_DIRECTIVE(ln2_2)
 
+	.section .rodata.cst4,"aM",@progbits,4
+
+	.p2align 2
+	.type flt_min,@object
+flt_min:	.byte 0, 0, 0x80, 0
+	ASM_SIZE_DIRECTIVE(flt_min)
+
 #ifdef PIC
 #define MO(op) op##@GOTOFF(%edx)
 #else
@@ -77,7 +84,18 @@ ENTRY(__ieee754_atanhf)
 	sahf
 	jae	4f
 	fyl2xp1			// 0.5*ln2*ld(1+2*|x|+(2*|x|^2)/(1-|x|))
-	jecxz	3f
+	fcoms	MO(flt_min)
+	fnstsw
+	sahf
+	jae	6f
+	subl	$4, %esp
+	cfi_adjust_cfa_offset (4)
+	fld	%st(0)
+	fmul	%st(0)
+	fstps	(%esp)
+	addl	$4, %esp
+	cfi_adjust_cfa_offset (-4)
+6:	jecxz	3f
 	fchs			// 0.5*ln2*ld(1+2*x+(2*x^2)/(1-x))
 3:	ret
 
diff --git a/sysdeps/ieee754/dbl-64/e_atanh.c b/sysdeps/ieee754/dbl-64/e_atanh.c
index b95399d..6b00b80 100644
--- a/sysdeps/ieee754/dbl-64/e_atanh.c
+++ b/sysdeps/ieee754/dbl-64/e_atanh.c
@@ -35,6 +35,7 @@
 
  */
 
+#include <float.h>
 #include <inttypes.h>
 #include <math.h>
 #include <math_private.h>
@@ -51,6 +52,11 @@ __ieee754_atanh (double x)
       if (__glibc_unlikely (xa < 0x1.0p-28))
 	{
 	  math_force_eval (huge + x);
+	  if (fabs (x) < DBL_MIN)
+	    {
+	      double force_underflow = x * x;
+	      math_force_eval (force_underflow);
+	    }
 	  return x;
 	}
 
diff --git a/sysdeps/ieee754/flt-32/e_atanhf.c b/sysdeps/ieee754/flt-32/e_atanhf.c
index a6d8bd1..bc74960 100644
--- a/sysdeps/ieee754/flt-32/e_atanhf.c
+++ b/sysdeps/ieee754/flt-32/e_atanhf.c
@@ -35,6 +35,7 @@
 
  */
 
+#include <float.h>
 #include <inttypes.h>
 #include <math.h>
 #include <math_private.h>
@@ -51,6 +52,11 @@ __ieee754_atanhf (float x)
       if (__glibc_unlikely (xa < 0x1.0p-28f))
 	{
 	  math_force_eval (huge + x);
+	  if (fabsf (x) < FLT_MIN)
+	    {
+	      float force_underflow = x * x;
+	      math_force_eval (force_underflow);
+	    }
 	  return x;
 	}
 
diff --git a/sysdeps/ieee754/ldbl-128/e_atanhl.c b/sysdeps/ieee754/ldbl-128/e_atanhl.c
index c5cceb5..a5a7ee0 100644
--- a/sysdeps/ieee754/ldbl-128/e_atanhl.c
+++ b/sysdeps/ieee754/ldbl-128/e_atanhl.c
@@ -32,6 +32,7 @@
  *
  */
 
+#include <float.h>
 #include <math.h>
 #include <math_private.h>
 
@@ -57,7 +58,15 @@ __ieee754_atanhl(long double x)
 	    else
 	      return (x-x)/(x-x);
 	  }
-	if(ix<0x3fc60000 && (huge+x)>zero) return x;	/* x < 2^-57 */
+	if(ix<0x3fc60000 && (huge+x)>zero)	/* x < 2^-57 */
+	  {
+	    if (fabsl (x) < LDBL_MIN)
+	      {
+		long double force_underflow = x * x;
+		math_force_eval (force_underflow);
+	      }
+	    return x;
+	  }
 
 	if(ix<0x3ffe0000) {		/* x < 0.5 */
 	    t = u.value+u.value;
diff --git a/sysdeps/ieee754/ldbl-128ibm/e_atanhl.c b/sysdeps/ieee754/ldbl-128ibm/e_atanhl.c
index 5a98999..bcd1fce 100644
--- a/sysdeps/ieee754/ldbl-128ibm/e_atanhl.c
+++ b/sysdeps/ieee754/ldbl-128ibm/e_atanhl.c
@@ -28,6 +28,7 @@
  *
  */
 
+#include <float.h>
 #include <math.h>
 #include <math_private.h>
 
@@ -54,7 +55,15 @@ __ieee754_atanhl(long double x)
 	    if (t == one)
 		return x/zero;
 	}
-	if(ix<0x3c70000000000000LL&&(huge+x)>zero) return x;	/* x<2**-56 */
+	if(ix<0x3c70000000000000LL&&(huge+x)>zero)	/* x<2**-56 */
+	  {
+	    if (fabsl (x) < LDBL_MIN)
+	      {
+		long double force_underflow = x * x;
+		math_force_eval (force_underflow);
+	      }
+	    return x;
+	  }
 	x = fabsl (x);
 	if(ix<0x3fe0000000000000LL) {		/* x < 0.5 */
 	    t = x+x;
diff --git a/sysdeps/ieee754/ldbl-96/e_atanhl.c b/sysdeps/ieee754/ldbl-96/e_atanhl.c
index 305d50e..9a957c9 100644
--- a/sysdeps/ieee754/ldbl-96/e_atanhl.c
+++ b/sysdeps/ieee754/ldbl-96/e_atanhl.c
@@ -32,6 +32,7 @@
  *
  */
 
+#include <float.h>
 #include <math.h>
 #include <math_private.h>
 
@@ -54,6 +55,11 @@ __ieee754_atanhl(long double x)
 	    return x/zero;
 	if(ix<0x3fdf) {
 	    math_force_eval(huge+x);
+	    if (fabsl (x) < LDBL_MIN)
+	      {
+		long double force_underflow = x * x;
+		math_force_eval (force_underflow);
+	      }
 	    return x;	/* x<2**-32 */
 	}
 	SET_LDOUBLE_EXP(x,ix);