Fix tanh missing underflows (bug 16520).

Similar to various other bugs in this area, some tanh 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.

Tested for x86_64, x86, mips64 and powerpc.

	[BZ #16520]
	* sysdeps/ieee754/dbl-64/s_tanh.c: Include <float.h>.
	(__tanh): Force underflow exception for arguments with small
	absolute value.
	* sysdeps/ieee754/flt-32/s_tanhf.c: Include <float.h>.
	(__tanhf): Force underflow exception for arguments with small
	absolute value.
	* sysdeps/ieee754/ldbl-128/s_tanhl.c: Include <float.h>.
	(__tanhl): Force underflow exception for arguments with small
	absolute value.
	* sysdeps/ieee754/ldbl-128ibm/s_tanhl.c: Include <float.h>.
	(__tanhl): Force underflow exception for arguments with small
	absolute value.
	* sysdeps/ieee754/ldbl-96/s_tanhl.c: Include <float.h>.
	(__tanhl): Force underflow exception for arguments with small
	absolute value.
	* math/auto-libm-test-in: Add more tests of tanh.
	* math/auto-libm-test-out: Regenerated.
	* sysdeps/i386/fpu/libm-test-ulps: Update.

10 files changed, 390 insertions, 4 deletions

diff --git a/ChangeLog b/ChangeLog
index 3f55c55a1d..dbb7b467f6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,25 @@
+2015-08-13  Joseph Myers  <joseph@codesourcery.com>
+
+	[BZ #16520]
+	* sysdeps/ieee754/dbl-64/s_tanh.c: Include <float.h>.
+	(__tanh): Force underflow exception for arguments with small
+	absolute value.
+	* sysdeps/ieee754/flt-32/s_tanhf.c: Include <float.h>.
+	(__tanhf): Force underflow exception for arguments with small
+	absolute value.
+	* sysdeps/ieee754/ldbl-128/s_tanhl.c: Include <float.h>.
+	(__tanhl): Force underflow exception for arguments with small
+	absolute value.
+	* sysdeps/ieee754/ldbl-128ibm/s_tanhl.c: Include <float.h>.
+	(__tanhl): Force underflow exception for arguments with small
+	absolute value.
+	* sysdeps/ieee754/ldbl-96/s_tanhl.c: Include <float.h>.
+	(__tanhl): Force underflow exception for arguments with small
+	absolute value.
+	* math/auto-libm-test-in: Add more tests of tanh.
+	* math/auto-libm-test-out: Regenerated.
+	* sysdeps/i386/fpu/libm-test-ulps: Update.
+
 2015-08-13  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* sysdeps/x86/cpu-features.c (init_cpu_features): Call
diff --git a/NEWS b/NEWS
index ea8bb6d7ca..5ca3de8353 100644
--- a/NEWS
+++ b/NEWS
@@ -9,8 +9,8 @@ Version 2.23
 
 * The following bugs are resolved with this release:
 
-  16517, 16519, 16734, 17905, 18086, 18265, 18480, 18525, 18618, 18647,
-  18661, 18674, 18778, 18781, 18787, 18789, 18790, 18820.
+  16517, 16519, 16520, 16734, 17905, 18086, 18265, 18480, 18525, 18618,
+  18647, 18661, 18674, 18778, 18781, 18787, 18789, 18790, 18820.
 
 
 Version 2.22
diff --git a/math/auto-libm-test-in b/math/auto-libm-test-in
index c32e436905..b14146e2b6 100644
--- a/math/auto-libm-test-in
+++ b/math/auto-libm-test-in
@@ -2779,6 +2779,10 @@ tanh -0x2.6082fp-4
 tanh 0xe.05031p-16
 tanh 0x3.c80eaa7adaa3p-4
 tanh 0x2.00f9857616524p-4
+tanh min
+tanh -min
+tanh min_subnorm
+tanh -min_subnorm
 
 tgamma 0.5
 tgamma -0.5
diff --git a/math/auto-libm-test-out b/math/auto-libm-test-out
index b4114be3d8..4d8bcf2f08 100644
--- a/math/auto-libm-test-out
+++ b/math/auto-libm-test-out
@@ -205177,6 +205177,322 @@ tanh 0x2.00f9857616524p-4
 = tanh tonearest ldbl-128ibm 0x2.00f9857616524p-4L : 0x1.fe4f3a8e0515344ff794387d93p-4L : inexact-ok
 = tanh towardzero ldbl-128ibm 0x2.00f9857616524p-4L : 0x1.fe4f3a8e0515344ff794387d928p-4L : inexact-ok
 = tanh upward ldbl-128ibm 0x2.00f9857616524p-4L : 0x1.fe4f3a8e0515344ff794387d93p-4L : inexact-ok
+tanh min
+= tanh downward flt-32 0x4p-128f : 0x3.fffff8p-128f : inexact-ok underflow-ok errno-erange-ok
+= tanh tonearest flt-32 0x4p-128f : 0x4p-128f : inexact-ok underflow-ok errno-erange-ok
+= tanh towardzero flt-32 0x4p-128f : 0x3.fffff8p-128f : inexact-ok underflow-ok errno-erange-ok
+= tanh upward flt-32 0x4p-128f : 0x4p-128f : inexact-ok underflow-ok errno-erange-ok
+= tanh downward dbl-64 0x4p-128 : 0x3.ffffffffffffep-128 : inexact-ok
+= tanh tonearest dbl-64 0x4p-128 : 0x4p-128 : inexact-ok
+= tanh towardzero dbl-64 0x4p-128 : 0x3.ffffffffffffep-128 : inexact-ok
+= tanh upward dbl-64 0x4p-128 : 0x4p-128 : inexact-ok
+= tanh downward ldbl-96-intel 0x4p-128L : 0x3.fffffffffffffffcp-128L : inexact-ok
+= tanh tonearest ldbl-96-intel 0x4p-128L : 0x4p-128L : inexact-ok
+= tanh towardzero ldbl-96-intel 0x4p-128L : 0x3.fffffffffffffffcp-128L : inexact-ok
+= tanh upward ldbl-96-intel 0x4p-128L : 0x4p-128L : inexact-ok
+= tanh downward ldbl-96-m68k 0x4p-128L : 0x3.fffffffffffffffcp-128L : inexact-ok
+= tanh tonearest ldbl-96-m68k 0x4p-128L : 0x4p-128L : inexact-ok
+= tanh towardzero ldbl-96-m68k 0x4p-128L : 0x3.fffffffffffffffcp-128L : inexact-ok
+= tanh upward ldbl-96-m68k 0x4p-128L : 0x4p-128L : inexact-ok
+= tanh downward ldbl-128 0x4p-128L : 0x3.fffffffffffffffffffffffffffep-128L : inexact-ok
+= tanh tonearest ldbl-128 0x4p-128L : 0x4p-128L : inexact-ok
+= tanh towardzero ldbl-128 0x4p-128L : 0x3.fffffffffffffffffffffffffffep-128L : inexact-ok
+= tanh upward ldbl-128 0x4p-128L : 0x4p-128L : inexact-ok
+= tanh downward ldbl-128ibm 0x4p-128L : 0x3.ffffffffffffffffffffffffffp-128L : inexact-ok
+= tanh tonearest ldbl-128ibm 0x4p-128L : 0x4p-128L : inexact-ok
+= tanh towardzero ldbl-128ibm 0x4p-128L : 0x3.ffffffffffffffffffffffffffp-128L : inexact-ok
+= tanh upward ldbl-128ibm 0x4p-128L : 0x4p-128L : inexact-ok
+= tanh downward dbl-64 0x4p-1024 : 0x3.ffffffffffffcp-1024 : inexact-ok underflow-ok errno-erange-ok
+= tanh tonearest dbl-64 0x4p-1024 : 0x4p-1024 : inexact-ok underflow-ok errno-erange-ok
+= tanh towardzero dbl-64 0x4p-1024 : 0x3.ffffffffffffcp-1024 : inexact-ok underflow-ok errno-erange-ok
+= tanh upward dbl-64 0x4p-1024 : 0x4p-1024 : inexact-ok underflow-ok errno-erange-ok
+= tanh downward ldbl-96-intel 0x4p-1024L : 0x3.fffffffffffffffcp-1024L : inexact-ok
+= tanh tonearest ldbl-96-intel 0x4p-1024L : 0x4p-1024L : inexact-ok
+= tanh towardzero ldbl-96-intel 0x4p-1024L : 0x3.fffffffffffffffcp-1024L : inexact-ok
+= tanh upward ldbl-96-intel 0x4p-1024L : 0x4p-1024L : inexact-ok
+= tanh downward ldbl-96-m68k 0x4p-1024L : 0x3.fffffffffffffffcp-1024L : inexact-ok
+= tanh tonearest ldbl-96-m68k 0x4p-1024L : 0x4p-1024L : inexact-ok
+= tanh towardzero ldbl-96-m68k 0x4p-1024L : 0x3.fffffffffffffffcp-1024L : inexact-ok
+= tanh upward ldbl-96-m68k 0x4p-1024L : 0x4p-1024L : inexact-ok
+= tanh downward ldbl-128 0x4p-1024L : 0x3.fffffffffffffffffffffffffffep-1024L : inexact-ok
+= tanh tonearest ldbl-128 0x4p-1024L : 0x4p-1024L : inexact-ok
+= tanh towardzero ldbl-128 0x4p-1024L : 0x3.fffffffffffffffffffffffffffep-1024L : inexact-ok
+= tanh upward ldbl-128 0x4p-1024L : 0x4p-1024L : inexact-ok
+= tanh downward ldbl-128ibm 0x4p-1024L : 0x3.ffffffffffffcp-1024L : inexact-ok underflow errno-erange-ok
+= tanh tonearest ldbl-128ibm 0x4p-1024L : 0x4p-1024L : inexact-ok underflow errno-erange-ok
+= tanh towardzero ldbl-128ibm 0x4p-1024L : 0x3.ffffffffffffcp-1024L : inexact-ok underflow errno-erange-ok
+= tanh upward ldbl-128ibm 0x4p-1024L : 0x4p-1024L : inexact-ok underflow errno-erange-ok
+= tanh downward ldbl-96-intel 0x4p-16384L : 0x3.fffffffffffffff8p-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh tonearest ldbl-96-intel 0x4p-16384L : 0x4p-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh towardzero ldbl-96-intel 0x4p-16384L : 0x3.fffffffffffffff8p-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh upward ldbl-96-intel 0x4p-16384L : 0x4p-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh downward ldbl-96-m68k 0x4p-16384L : 0x3.fffffffffffffffcp-16384L : inexact-ok
+= tanh tonearest ldbl-96-m68k 0x4p-16384L : 0x4p-16384L : inexact-ok
+= tanh towardzero ldbl-96-m68k 0x4p-16384L : 0x3.fffffffffffffffcp-16384L : inexact-ok
+= tanh upward ldbl-96-m68k 0x4p-16384L : 0x4p-16384L : inexact-ok
+= tanh downward ldbl-128 0x4p-16384L : 0x3.fffffffffffffffffffffffffffcp-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh tonearest ldbl-128 0x4p-16384L : 0x4p-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh towardzero ldbl-128 0x4p-16384L : 0x3.fffffffffffffffffffffffffffcp-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh upward ldbl-128 0x4p-16384L : 0x4p-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh downward ldbl-96-intel 0x2p-16384L : 0x1.fffffffffffffff8p-16384L : inexact-ok underflow errno-erange-ok
+= tanh tonearest ldbl-96-intel 0x2p-16384L : 0x2p-16384L : inexact-ok underflow errno-erange-ok
+= tanh towardzero ldbl-96-intel 0x2p-16384L : 0x1.fffffffffffffff8p-16384L : inexact-ok underflow errno-erange-ok
+= tanh upward ldbl-96-intel 0x2p-16384L : 0x2p-16384L : inexact-ok underflow errno-erange-ok
+= tanh downward ldbl-96-m68k 0x2p-16384L : 0x1.fffffffffffffffcp-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh tonearest ldbl-96-m68k 0x2p-16384L : 0x2p-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh towardzero ldbl-96-m68k 0x2p-16384L : 0x1.fffffffffffffffcp-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh upward ldbl-96-m68k 0x2p-16384L : 0x2p-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh downward ldbl-128 0x2p-16384L : 0x1.fffffffffffffffffffffffffffcp-16384L : inexact-ok underflow errno-erange-ok
+= tanh tonearest ldbl-128 0x2p-16384L : 0x2p-16384L : inexact-ok underflow errno-erange-ok
+= tanh towardzero ldbl-128 0x2p-16384L : 0x1.fffffffffffffffffffffffffffcp-16384L : inexact-ok underflow errno-erange-ok
+= tanh upward ldbl-128 0x2p-16384L : 0x2p-16384L : inexact-ok underflow errno-erange-ok
+= tanh downward dbl-64 0x8p-972 : 0x7.ffffffffffffcp-972 : inexact-ok
+= tanh tonearest dbl-64 0x8p-972 : 0x8p-972 : inexact-ok
+= tanh towardzero dbl-64 0x8p-972 : 0x7.ffffffffffffcp-972 : inexact-ok
+= tanh upward dbl-64 0x8p-972 : 0x8p-972 : inexact-ok
+= tanh downward ldbl-96-intel 0x8p-972L : 0x7.fffffffffffffff8p-972L : inexact-ok
+= tanh tonearest ldbl-96-intel 0x8p-972L : 0x8p-972L : inexact-ok
+= tanh towardzero ldbl-96-intel 0x8p-972L : 0x7.fffffffffffffff8p-972L : inexact-ok
+= tanh upward ldbl-96-intel 0x8p-972L : 0x8p-972L : inexact-ok
+= tanh downward ldbl-96-m68k 0x8p-972L : 0x7.fffffffffffffff8p-972L : inexact-ok
+= tanh tonearest ldbl-96-m68k 0x8p-972L : 0x8p-972L : inexact-ok
+= tanh towardzero ldbl-96-m68k 0x8p-972L : 0x7.fffffffffffffff8p-972L : inexact-ok
+= tanh upward ldbl-96-m68k 0x8p-972L : 0x8p-972L : inexact-ok
+= tanh downward ldbl-128 0x8p-972L : 0x7.fffffffffffffffffffffffffffcp-972L : inexact-ok
+= tanh tonearest ldbl-128 0x8p-972L : 0x8p-972L : inexact-ok
+= tanh towardzero ldbl-128 0x8p-972L : 0x7.fffffffffffffffffffffffffffcp-972L : inexact-ok
+= tanh upward ldbl-128 0x8p-972L : 0x8p-972L : inexact-ok
+= tanh downward ldbl-128ibm 0x8p-972L : 0x7.fffffffffffffffffffffffffcp-972L : inexact-ok underflow-ok errno-erange-ok
+= tanh tonearest ldbl-128ibm 0x8p-972L : 0x8p-972L : inexact-ok underflow-ok errno-erange-ok
+= tanh towardzero ldbl-128ibm 0x8p-972L : 0x7.fffffffffffffffffffffffffcp-972L : inexact-ok underflow-ok errno-erange-ok
+= tanh upward ldbl-128ibm 0x8p-972L : 0x8p-972L : inexact-ok underflow-ok errno-erange-ok
+tanh -min
+= tanh downward flt-32 -0x4p-128f : -0x4p-128f : inexact-ok underflow-ok errno-erange-ok
+= tanh tonearest flt-32 -0x4p-128f : -0x4p-128f : inexact-ok underflow-ok errno-erange-ok
+= tanh towardzero flt-32 -0x4p-128f : -0x3.fffff8p-128f : inexact-ok underflow-ok errno-erange-ok
+= tanh upward flt-32 -0x4p-128f : -0x3.fffff8p-128f : inexact-ok underflow-ok errno-erange-ok
+= tanh downward dbl-64 -0x4p-128 : -0x4p-128 : inexact-ok
+= tanh tonearest dbl-64 -0x4p-128 : -0x4p-128 : inexact-ok
+= tanh towardzero dbl-64 -0x4p-128 : -0x3.ffffffffffffep-128 : inexact-ok
+= tanh upward dbl-64 -0x4p-128 : -0x3.ffffffffffffep-128 : inexact-ok
+= tanh downward ldbl-96-intel -0x4p-128L : -0x4p-128L : inexact-ok
+= tanh tonearest ldbl-96-intel -0x4p-128L : -0x4p-128L : inexact-ok
+= tanh towardzero ldbl-96-intel -0x4p-128L : -0x3.fffffffffffffffcp-128L : inexact-ok
+= tanh upward ldbl-96-intel -0x4p-128L : -0x3.fffffffffffffffcp-128L : inexact-ok
+= tanh downward ldbl-96-m68k -0x4p-128L : -0x4p-128L : inexact-ok
+= tanh tonearest ldbl-96-m68k -0x4p-128L : -0x4p-128L : inexact-ok
+= tanh towardzero ldbl-96-m68k -0x4p-128L : -0x3.fffffffffffffffcp-128L : inexact-ok
+= tanh upward ldbl-96-m68k -0x4p-128L : -0x3.fffffffffffffffcp-128L : inexact-ok
+= tanh downward ldbl-128 -0x4p-128L : -0x4p-128L : inexact-ok
+= tanh tonearest ldbl-128 -0x4p-128L : -0x4p-128L : inexact-ok
+= tanh towardzero ldbl-128 -0x4p-128L : -0x3.fffffffffffffffffffffffffffep-128L : inexact-ok
+= tanh upward ldbl-128 -0x4p-128L : -0x3.fffffffffffffffffffffffffffep-128L : inexact-ok
+= tanh downward ldbl-128ibm -0x4p-128L : -0x4p-128L : inexact-ok
+= tanh tonearest ldbl-128ibm -0x4p-128L : -0x4p-128L : inexact-ok
+= tanh towardzero ldbl-128ibm -0x4p-128L : -0x3.ffffffffffffffffffffffffffp-128L : inexact-ok
+= tanh upward ldbl-128ibm -0x4p-128L : -0x3.ffffffffffffffffffffffffffp-128L : inexact-ok
+= tanh downward dbl-64 -0x4p-1024 : -0x4p-1024 : inexact-ok underflow-ok errno-erange-ok
+= tanh tonearest dbl-64 -0x4p-1024 : -0x4p-1024 : inexact-ok underflow-ok errno-erange-ok
+= tanh towardzero dbl-64 -0x4p-1024 : -0x3.ffffffffffffcp-1024 : inexact-ok underflow-ok errno-erange-ok
+= tanh upward dbl-64 -0x4p-1024 : -0x3.ffffffffffffcp-1024 : inexact-ok underflow-ok errno-erange-ok
+= tanh downward ldbl-96-intel -0x4p-1024L : -0x4p-1024L : inexact-ok
+= tanh tonearest ldbl-96-intel -0x4p-1024L : -0x4p-1024L : inexact-ok
+= tanh towardzero ldbl-96-intel -0x4p-1024L : -0x3.fffffffffffffffcp-1024L : inexact-ok
+= tanh upward ldbl-96-intel -0x4p-1024L : -0x3.fffffffffffffffcp-1024L : inexact-ok
+= tanh downward ldbl-96-m68k -0x4p-1024L : -0x4p-1024L : inexact-ok
+= tanh tonearest ldbl-96-m68k -0x4p-1024L : -0x4p-1024L : inexact-ok
+= tanh towardzero ldbl-96-m68k -0x4p-1024L : -0x3.fffffffffffffffcp-1024L : inexact-ok
+= tanh upward ldbl-96-m68k -0x4p-1024L : -0x3.fffffffffffffffcp-1024L : inexact-ok
+= tanh downward ldbl-128 -0x4p-1024L : -0x4p-1024L : inexact-ok
+= tanh tonearest ldbl-128 -0x4p-1024L : -0x4p-1024L : inexact-ok
+= tanh towardzero ldbl-128 -0x4p-1024L : -0x3.fffffffffffffffffffffffffffep-1024L : inexact-ok
+= tanh upward ldbl-128 -0x4p-1024L : -0x3.fffffffffffffffffffffffffffep-1024L : inexact-ok
+= tanh downward ldbl-128ibm -0x4p-1024L : -0x4p-1024L : inexact-ok underflow errno-erange-ok
+= tanh tonearest ldbl-128ibm -0x4p-1024L : -0x4p-1024L : inexact-ok underflow errno-erange-ok
+= tanh towardzero ldbl-128ibm -0x4p-1024L : -0x3.ffffffffffffcp-1024L : inexact-ok underflow errno-erange-ok
+= tanh upward ldbl-128ibm -0x4p-1024L : -0x3.ffffffffffffcp-1024L : inexact-ok underflow errno-erange-ok
+= tanh downward ldbl-96-intel -0x4p-16384L : -0x4p-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh tonearest ldbl-96-intel -0x4p-16384L : -0x4p-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh towardzero ldbl-96-intel -0x4p-16384L : -0x3.fffffffffffffff8p-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh upward ldbl-96-intel -0x4p-16384L : -0x3.fffffffffffffff8p-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh downward ldbl-96-m68k -0x4p-16384L : -0x4p-16384L : inexact-ok
+= tanh tonearest ldbl-96-m68k -0x4p-16384L : -0x4p-16384L : inexact-ok
+= tanh towardzero ldbl-96-m68k -0x4p-16384L : -0x3.fffffffffffffffcp-16384L : inexact-ok
+= tanh upward ldbl-96-m68k -0x4p-16384L : -0x3.fffffffffffffffcp-16384L : inexact-ok
+= tanh downward ldbl-128 -0x4p-16384L : -0x4p-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh tonearest ldbl-128 -0x4p-16384L : -0x4p-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh towardzero ldbl-128 -0x4p-16384L : -0x3.fffffffffffffffffffffffffffcp-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh upward ldbl-128 -0x4p-16384L : -0x3.fffffffffffffffffffffffffffcp-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh downward ldbl-96-intel -0x2p-16384L : -0x2p-16384L : inexact-ok underflow errno-erange-ok
+= tanh tonearest ldbl-96-intel -0x2p-16384L : -0x2p-16384L : inexact-ok underflow errno-erange-ok
+= tanh towardzero ldbl-96-intel -0x2p-16384L : -0x1.fffffffffffffff8p-16384L : inexact-ok underflow errno-erange-ok
+= tanh upward ldbl-96-intel -0x2p-16384L : -0x1.fffffffffffffff8p-16384L : inexact-ok underflow errno-erange-ok
+= tanh downward ldbl-96-m68k -0x2p-16384L : -0x2p-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh tonearest ldbl-96-m68k -0x2p-16384L : -0x2p-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh towardzero ldbl-96-m68k -0x2p-16384L : -0x1.fffffffffffffffcp-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh upward ldbl-96-m68k -0x2p-16384L : -0x1.fffffffffffffffcp-16384L : inexact-ok underflow-ok errno-erange-ok
+= tanh downward ldbl-128 -0x2p-16384L : -0x2p-16384L : inexact-ok underflow errno-erange-ok
+= tanh tonearest ldbl-128 -0x2p-16384L : -0x2p-16384L : inexact-ok underflow errno-erange-ok
+= tanh towardzero ldbl-128 -0x2p-16384L : -0x1.fffffffffffffffffffffffffffcp-16384L : inexact-ok underflow errno-erange-ok
+= tanh upward ldbl-128 -0x2p-16384L : -0x1.fffffffffffffffffffffffffffcp-16384L : inexact-ok underflow errno-erange-ok
+= tanh downward dbl-64 -0x8p-972 : -0x8p-972 : inexact-ok
+= tanh tonearest dbl-64 -0x8p-972 : -0x8p-972 : inexact-ok
+= tanh towardzero dbl-64 -0x8p-972 : -0x7.ffffffffffffcp-972 : inexact-ok
+= tanh upward dbl-64 -0x8p-972 : -0x7.ffffffffffffcp-972 : inexact-ok
+= tanh downward ldbl-96-intel -0x8p-972L : -0x8p-972L : inexact-ok
+= tanh tonearest ldbl-96-intel -0x8p-972L : -0x8p-972L : inexact-ok
+= tanh towardzero ldbl-96-intel -0x8p-972L : -0x7.fffffffffffffff8p-972L : inexact-ok
+= tanh upward ldbl-96-intel -0x8p-972L : -0x7.fffffffffffffff8p-972L : inexact-ok
+= tanh downward ldbl-96-m68k -0x8p-972L : -0x8p-972L : inexact-ok
+= tanh tonearest ldbl-96-m68k -0x8p-972L : -0x8p-972L : inexact-ok
+= tanh towardzero ldbl-96-m68k -0x8p-972L : -0x7.fffffffffffffff8p-972L : inexact-ok
+= tanh upward ldbl-96-m68k -0x8p-972L : -0x7.fffffffffffffff8p-972L : inexact-ok
+= tanh downward ldbl-128 -0x8p-972L : -0x8p-972L : inexact-ok
+= tanh tonearest ldbl-128 -0x8p-972L : -0x8p-972L : inexact-ok
+= tanh towardzero ldbl-128 -0x8p-972L : -0x7.fffffffffffffffffffffffffffcp-972L : inexact-ok
+= tanh upward ldbl-128 -0x8p-972L : -0x7.fffffffffffffffffffffffffffcp-972L : inexact-ok
+= tanh downward ldbl-128ibm -0x8p-972L : -0x8p-972L : inexact-ok underflow-ok errno-erange-ok
+= tanh tonearest ldbl-128ibm -0x8p-972L : -0x8p-972L : inexact-ok underflow-ok errno-erange-ok
+= tanh towardzero ldbl-128ibm -0x8p-972L : -0x7.fffffffffffffffffffffffffcp-972L : inexact-ok underflow-ok errno-erange-ok
+= tanh upward ldbl-128ibm -0x8p-972L : -0x7.fffffffffffffffffffffffffcp-972L : inexact-ok underflow-ok errno-erange-ok
+tanh min_subnorm
+= tanh downward flt-32 0x8p-152f : 0x0p+0f : inexact-ok underflow errno-erange-ok
+= tanh tonearest flt-32 0x8p-152f : 0x8p-152f : inexact-ok underflow errno-erange-ok
+= tanh towardzero flt-32 0x8p-152f : 0x0p+0f : inexact-ok underflow errno-erange-ok
+= tanh upward flt-32 0x8p-152f : 0x8p-152f : inexact-ok underflow errno-erange-ok
+= tanh downward dbl-64 0x8p-152 : 0x7.ffffffffffffcp-152 : inexact-ok
+= tanh tonearest dbl-64 0x8p-152 : 0x8p-152 : inexact-ok
+= tanh towardzero dbl-64 0x8p-152 : 0x7.ffffffffffffcp-152 : inexact-ok
+= tanh upward dbl-64 0x8p-152 : 0x8p-152 : inexact-ok
+= tanh downward ldbl-96-intel 0x8p-152L : 0x7.fffffffffffffff8p-152L : inexact-ok
+= tanh tonearest ldbl-96-intel 0x8p-152L : 0x8p-152L : inexact-ok
+= tanh towardzero ldbl-96-intel 0x8p-152L : 0x7.fffffffffffffff8p-152L : inexact-ok
+= tanh upward ldbl-96-intel 0x8p-152L : 0x8p-152L : inexact-ok
+= tanh downward ldbl-96-m68k 0x8p-152L : 0x7.fffffffffffffff8p-152L : inexact-ok
+= tanh tonearest ldbl-96-m68k 0x8p-152L : 0x8p-152L : inexact-ok
+= tanh towardzero ldbl-96-m68k 0x8p-152L : 0x7.fffffffffffffff8p-152L : inexact-ok
+= tanh upward ldbl-96-m68k 0x8p-152L : 0x8p-152L : inexact-ok
+= tanh downward ldbl-128 0x8p-152L : 0x7.fffffffffffffffffffffffffffcp-152L : inexact-ok
+= tanh tonearest ldbl-128 0x8p-152L : 0x8p-152L : inexact-ok
+= tanh towardzero ldbl-128 0x8p-152L : 0x7.fffffffffffffffffffffffffffcp-152L : inexact-ok
+= tanh upward ldbl-128 0x8p-152L : 0x8p-152L : inexact-ok
+= tanh downward ldbl-128ibm 0x8p-152L : 0x7.fffffffffffffffffffffffffep-152L : inexact-ok
+= tanh tonearest ldbl-128ibm 0x8p-152L : 0x8p-152L : inexact-ok
+= tanh towardzero ldbl-128ibm 0x8p-152L : 0x7.fffffffffffffffffffffffffep-152L : inexact-ok
+= tanh upward ldbl-128ibm 0x8p-152L : 0x8p-152L : inexact-ok
+= tanh downward dbl-64 0x4p-1076 : 0x0p+0 : inexact-ok underflow errno-erange-ok
+= tanh tonearest dbl-64 0x4p-1076 : 0x4p-1076 : inexact-ok underflow errno-erange-ok
+= tanh towardzero dbl-64 0x4p-1076 : 0x0p+0 : inexact-ok underflow errno-erange-ok
+= tanh upward dbl-64 0x4p-1076 : 0x4p-1076 : inexact-ok underflow errno-erange-ok
+= tanh downward ldbl-96-intel 0x4p-1076L : 0x3.fffffffffffffffcp-1076L : inexact-ok
+= tanh tonearest ldbl-96-intel 0x4p-1076L : 0x4p-1076L : inexact-ok
+= tanh towardzero ldbl-96-intel 0x4p-1076L : 0x3.fffffffffffffffcp-1076L : inexact-ok
+= tanh upward ldbl-96-intel 0x4p-1076L : 0x4p-1076L : inexact-ok
+= tanh downward ldbl-96-m68k 0x4p-1076L : 0x3.fffffffffffffffcp-1076L : inexact-ok
+= tanh tonearest ldbl-96-m68k 0x4p-1076L : 0x4p-1076L : inexact-ok
+= tanh towardzero ldbl-96-m68k 0x4p-1076L : 0x3.fffffffffffffffcp-1076L : inexact-ok
+= tanh upward ldbl-96-m68k 0x4p-1076L : 0x4p-1076L : inexact-ok
+= tanh downward ldbl-128 0x4p-1076L : 0x3.fffffffffffffffffffffffffffep-1076L : inexact-ok
+= tanh tonearest ldbl-128 0x4p-1076L : 0x4p-1076L : inexact-ok
+= tanh towardzero ldbl-128 0x4p-1076L : 0x3.fffffffffffffffffffffffffffep-1076L : inexact-ok
+= tanh upward ldbl-128 0x4p-1076L : 0x4p-1076L : inexact-ok
+= tanh downward ldbl-128ibm 0x4p-1076L : 0x0p+0L : inexact-ok underflow errno-erange-ok
+= tanh tonearest ldbl-128ibm 0x4p-1076L : 0x4p-1076L : inexact-ok underflow errno-erange-ok
+= tanh towardzero ldbl-128ibm 0x4p-1076L : 0x0p+0L : inexact-ok underflow errno-erange-ok
+= tanh upward ldbl-128ibm 0x4p-1076L : 0x4p-1076L : inexact-ok underflow errno-erange-ok
+= tanh downward ldbl-96-intel 0x8p-16448L : 0x0p+0L : inexact-ok underflow errno-erange-ok
+= tanh tonearest ldbl-96-intel 0x8p-16448L : 0x8p-16448L : inexact-ok underflow errno-erange-ok
+= tanh towardzero ldbl-96-intel 0x8p-16448L : 0x0p+0L : inexact-ok underflow errno-erange-ok
+= tanh upward ldbl-96-intel 0x8p-16448L : 0x8p-16448L : inexact-ok underflow errno-erange-ok
+= tanh downward ldbl-96-m68k 0x8p-16448L : 0x4p-16448L : inexact-ok underflow errno-erange-ok
+= tanh tonearest ldbl-96-m68k 0x8p-16448L : 0x8p-16448L : inexact-ok underflow errno-erange-ok
+= tanh towardzero ldbl-96-m68k 0x8p-16448L : 0x4p-16448L : inexact-ok underflow errno-erange-ok
+= tanh upward ldbl-96-m68k 0x8p-16448L : 0x8p-16448L : inexact-ok underflow errno-erange-ok
+= tanh downward ldbl-128 0x8p-16448L : 0x7.fffffffffffcp-16448L : inexact-ok underflow errno-erange-ok
+= tanh tonearest ldbl-128 0x8p-16448L : 0x8p-16448L : inexact-ok underflow errno-erange-ok
+= tanh towardzero ldbl-128 0x8p-16448L : 0x7.fffffffffffcp-16448L : inexact-ok underflow errno-erange-ok
+= tanh upward ldbl-128 0x8p-16448L : 0x8p-16448L : inexact-ok underflow errno-erange-ok
+= tanh downward ldbl-96-m68k 0x4p-16448L : 0x0p+0L : inexact-ok underflow errno-erange-ok
+= tanh tonearest ldbl-96-m68k 0x4p-16448L : 0x4p-16448L : inexact-ok underflow errno-erange-ok
+= tanh towardzero ldbl-96-m68k 0x4p-16448L : 0x0p+0L : inexact-ok underflow errno-erange-ok
+= tanh upward ldbl-96-m68k 0x4p-16448L : 0x4p-16448L : inexact-ok underflow errno-erange-ok
+= tanh downward ldbl-128 0x4p-16448L : 0x3.fffffffffffcp-16448L : inexact-ok underflow errno-erange-ok
+= tanh tonearest ldbl-128 0x4p-16448L : 0x4p-16448L : inexact-ok underflow errno-erange-ok
+= tanh towardzero ldbl-128 0x4p-16448L : 0x3.fffffffffffcp-16448L : inexact-ok underflow errno-erange-ok
+= tanh upward ldbl-128 0x4p-16448L : 0x4p-16448L : inexact-ok underflow errno-erange-ok
+= tanh downward ldbl-128 0x4p-16496L : 0x0p+0L : inexact-ok underflow errno-erange-ok
+= tanh tonearest ldbl-128 0x4p-16496L : 0x4p-16496L : inexact-ok underflow errno-erange-ok
+= tanh towardzero ldbl-128 0x4p-16496L : 0x0p+0L : inexact-ok underflow errno-erange-ok
+= tanh upward ldbl-128 0x4p-16496L : 0x4p-16496L : inexact-ok underflow errno-erange-ok
+tanh -min_subnorm
+= tanh downward flt-32 -0x8p-152f : -0x8p-152f : inexact-ok underflow errno-erange-ok
+= tanh tonearest flt-32 -0x8p-152f : -0x8p-152f : inexact-ok underflow errno-erange-ok
+= tanh towardzero flt-32 -0x8p-152f : -0x0p+0f : inexact-ok underflow errno-erange-ok
+= tanh upward flt-32 -0x8p-152f : -0x0p+0f : inexact-ok underflow errno-erange-ok
+= tanh downward dbl-64 -0x8p-152 : -0x8p-152 : inexact-ok
+= tanh tonearest dbl-64 -0x8p-152 : -0x8p-152 : inexact-ok
+= tanh towardzero dbl-64 -0x8p-152 : -0x7.ffffffffffffcp-152 : inexact-ok
+= tanh upward dbl-64 -0x8p-152 : -0x7.ffffffffffffcp-152 : inexact-ok
+= tanh downward ldbl-96-intel -0x8p-152L : -0x8p-152L : inexact-ok
+= tanh tonearest ldbl-96-intel -0x8p-152L : -0x8p-152L : inexact-ok
+= tanh towardzero ldbl-96-intel -0x8p-152L : -0x7.fffffffffffffff8p-152L : inexact-ok
+= tanh upward ldbl-96-intel -0x8p-152L : -0x7.fffffffffffffff8p-152L : inexact-ok
+= tanh downward ldbl-96-m68k -0x8p-152L : -0x8p-152L : inexact-ok
+= tanh tonearest ldbl-96-m68k -0x8p-152L : -0x8p-152L : inexact-ok
+= tanh towardzero ldbl-96-m68k -0x8p-152L : -0x7.fffffffffffffff8p-152L : inexact-ok
+= tanh upward ldbl-96-m68k -0x8p-152L : -0x7.fffffffffffffff8p-152L : inexact-ok
+= tanh downward ldbl-128 -0x8p-152L : -0x8p-152L : inexact-ok
+= tanh tonearest ldbl-128 -0x8p-152L : -0x8p-152L : inexact-ok
+= tanh towardzero ldbl-128 -0x8p-152L : -0x7.fffffffffffffffffffffffffffcp-152L : inexact-ok
+= tanh upward ldbl-128 -0x8p-152L : -0x7.fffffffffffffffffffffffffffcp-152L : inexact-ok
+= tanh downward ldbl-128ibm -0x8p-152L : -0x8p-152L : inexact-ok
+= tanh tonearest ldbl-128ibm -0x8p-152L : -0x8p-152L : inexact-ok
+= tanh towardzero ldbl-128ibm -0x8p-152L : -0x7.fffffffffffffffffffffffffep-152L : inexact-ok
+= tanh upward ldbl-128ibm -0x8p-152L : -0x7.fffffffffffffffffffffffffep-152L : inexact-ok
+= tanh downward dbl-64 -0x4p-1076 : -0x4p-1076 : inexact-ok underflow errno-erange-ok
+= tanh tonearest dbl-64 -0x4p-1076 : -0x4p-1076 : inexact-ok underflow errno-erange-ok
+= tanh towardzero dbl-64 -0x4p-1076 : -0x0p+0 : inexact-ok underflow errno-erange-ok
+= tanh upward dbl-64 -0x4p-1076 : -0x0p+0 : inexact-ok underflow errno-erange-ok
+= tanh downward ldbl-96-intel -0x4p-1076L : -0x4p-1076L : inexact-ok
+= tanh tonearest ldbl-96-intel -0x4p-1076L : -0x4p-1076L : inexact-ok
+= tanh towardzero ldbl-96-intel -0x4p-1076L : -0x3.fffffffffffffffcp-1076L : inexact-ok
+= tanh upward ldbl-96-intel -0x4p-1076L : -0x3.fffffffffffffffcp-1076L : inexact-ok
+= tanh downward ldbl-96-m68k -0x4p-1076L : -0x4p-1076L : inexact-ok
+= tanh tonearest ldbl-96-m68k -0x4p-1076L : -0x4p-1076L : inexact-ok
+= tanh towardzero ldbl-96-m68k -0x4p-1076L : -0x3.fffffffffffffffcp-1076L : inexact-ok
+= tanh upward ldbl-96-m68k -0x4p-1076L : -0x3.fffffffffffffffcp-1076L : inexact-ok
+= tanh downward ldbl-128 -0x4p-1076L : -0x4p-1076L : inexact-ok
+= tanh tonearest ldbl-128 -0x4p-1076L : -0x4p-1076L : inexact-ok
+= tanh towardzero ldbl-128 -0x4p-1076L : -0x3.fffffffffffffffffffffffffffep-1076L : inexact-ok
+= tanh upward ldbl-128 -0x4p-1076L : -0x3.fffffffffffffffffffffffffffep-1076L : inexact-ok
+= tanh downward ldbl-128ibm -0x4p-1076L : -0x4p-1076L : inexact-ok underflow errno-erange-ok
+= tanh tonearest ldbl-128ibm -0x4p-1076L : -0x4p-1076L : inexact-ok underflow errno-erange-ok
+= tanh towardzero ldbl-128ibm -0x4p-1076L : -0x0p+0L : inexact-ok underflow errno-erange-ok
+= tanh upward ldbl-128ibm -0x4p-1076L : -0x0p+0L : inexact-ok underflow errno-erange-ok
+= tanh downward ldbl-96-intel -0x8p-16448L : -0x8p-16448L : inexact-ok underflow errno-erange-ok
+= tanh tonearest ldbl-96-intel -0x8p-16448L : -0x8p-16448L : inexact-ok underflow errno-erange-ok
+= tanh towardzero ldbl-96-intel -0x8p-16448L : -0x0p+0L : inexact-ok underflow errno-erange-ok
+= tanh upward ldbl-96-intel -0x8p-16448L : -0x0p+0L : inexact-ok underflow errno-erange-ok
+= tanh downward ldbl-96-m68k -0x8p-16448L : -0x8p-16448L : inexact-ok underflow errno-erange-ok
+= tanh tonearest ldbl-96-m68k -0x8p-16448L : -0x8p-16448L : inexact-ok underflow errno-erange-ok
+= tanh towardzero ldbl-96-m68k -0x8p-16448L : -0x4p-16448L : inexact-ok underflow errno-erange-ok
+= tanh upward ldbl-96-m68k -0x8p-16448L : -0x4p-16448L : inexact-ok underflow errno-erange-ok
+= tanh downward ldbl-128 -0x8p-16448L : -0x8p-16448L : inexact-ok underflow errno-erange-ok
+= tanh tonearest ldbl-128 -0x8p-16448L : -0x8p-16448L : inexact-ok underflow errno-erange-ok
+= tanh towardzero ldbl-128 -0x8p-16448L : -0x7.fffffffffffcp-16448L : inexact-ok underflow errno-erange-ok
+= tanh upward ldbl-128 -0x8p-16448L : -0x7.fffffffffffcp-16448L : inexact-ok underflow errno-erange-ok
+= tanh downward ldbl-96-m68k -0x4p-16448L : -0x4p-16448L : inexact-ok underflow errno-erange-ok
+= tanh tonearest ldbl-96-m68k -0x4p-16448L : -0x4p-16448L : inexact-ok underflow errno-erange-ok
+= tanh towardzero ldbl-96-m68k -0x4p-16448L : -0x0p+0L : inexact-ok underflow errno-erange-ok
+= tanh upward ldbl-96-m68k -0x4p-16448L : -0x0p+0L : inexact-ok underflow errno-erange-ok
+= tanh downward ldbl-128 -0x4p-16448L : -0x4p-16448L : inexact-ok underflow errno-erange-ok
+= tanh tonearest ldbl-128 -0x4p-16448L : -0x4p-16448L : inexact-ok underflow errno-erange-ok
+= tanh towardzero ldbl-128 -0x4p-16448L : -0x3.fffffffffffcp-16448L : inexact-ok underflow errno-erange-ok
+= tanh upward ldbl-128 -0x4p-16448L : -0x3.fffffffffffcp-16448L : inexact-ok underflow errno-erange-ok
+= tanh downward ldbl-128 -0x4p-16496L : -0x4p-16496L : inexact-ok underflow errno-erange-ok
+= tanh tonearest ldbl-128 -0x4p-16496L : -0x4p-16496L : inexact-ok underflow errno-erange-ok
+= tanh towardzero ldbl-128 -0x4p-16496L : -0x0p+0L : inexact-ok underflow errno-erange-ok
+= tanh upward ldbl-128 -0x4p-16496L : -0x0p+0L : inexact-ok underflow errno-erange-ok
 tgamma 0.5
 = tgamma downward flt-32 0x8p-4f : 0x1.c5bf88p+0f : inexact-ok
 = tgamma tonearest flt-32 0x8p-4f : 0x1.c5bf8ap+0f : inexact-ok
diff --git a/sysdeps/i386/fpu/libm-test-ulps b/sysdeps/i386/fpu/libm-test-ulps
index 36037655f2..de53451879 100644
--- a/sysdeps/i386/fpu/libm-test-ulps
+++ b/sysdeps/i386/fpu/libm-test-ulps
@@ -1988,12 +1988,16 @@ ldouble: 4
 Function: "tanh_towardzero":
 double: 1
 float: 1
+idouble: 1
+ifloat: 1
 ildouble: 3
 ldouble: 3
 
 Function: "tanh_upward":
 double: 1
 float: 1
+idouble: 1
+ifloat: 1
 ildouble: 5
 ldouble: 4
 
diff --git a/sysdeps/ieee754/dbl-64/s_tanh.c b/sysdeps/ieee754/dbl-64/s_tanh.c
index 23cfcdead5..4f9fcfd2bd 100644
--- a/sysdeps/ieee754/dbl-64/s_tanh.c
+++ b/sysdeps/ieee754/dbl-64/s_tanh.c
@@ -38,6 +38,7 @@ static char rcsid[] = "$NetBSD: s_tanh.c,v 1.7 1995/05/10 20:48:22 jtc Exp $";
  *	only tanh(0)=0 is exact for finite argument.
  */
 
+#include <float.h>
 #include <math.h>
 #include <math_private.h>
 
@@ -68,7 +69,14 @@ __tanh (double x)
       if ((ix | lx) == 0)
 	return x;                       /* x == +-0 */
       if (ix < 0x3c800000)              /* |x|<2**-55 */
-	return x * (one + x);           /* tanh(small) = small */
+	{
+	  if (fabs (x) < DBL_MIN)
+	    {
+	      double force_underflow = x * x;
+	      math_force_eval (force_underflow);
+	    }
+	  return x * (one + x);           /* tanh(small) = small */
+	}
       if (ix >= 0x3ff00000)             /* |x|>=1  */
 	{
 	  t = __expm1 (two * fabs (x));
diff --git a/sysdeps/ieee754/flt-32/s_tanhf.c b/sysdeps/ieee754/flt-32/s_tanhf.c
index dc96da9a5b..5b48fb2e00 100644
--- a/sysdeps/ieee754/flt-32/s_tanhf.c
+++ b/sysdeps/ieee754/flt-32/s_tanhf.c
@@ -17,6 +17,7 @@
 static char rcsid[] = "$NetBSD: s_tanhf.c,v 1.4 1995/05/10 20:48:24 jtc Exp $";
 #endif
 
+#include <float.h>
 #include <math.h>
 #include <math_private.h>
 
@@ -41,7 +42,14 @@ float __tanhf(float x)
 	    if (ix == 0)
 		return x;		/* x == +-0 */
 	    if (ix<0x24000000) 		/* |x|<2**-55 */
+	      {
+		if (fabsf (x) < FLT_MIN)
+		  {
+		    float force_underflow = x * x;
+		    math_force_eval (force_underflow);
+		  }
 		return x*(one+x);    	/* tanh(small) = small */
+	      }
 	    if (ix>=0x3f800000) {	/* |x|>=1  */
 		t = __expm1f(two*fabsf(x));
 		z = one - two/(t+two);
diff --git a/sysdeps/ieee754/ldbl-128/s_tanhl.c b/sysdeps/ieee754/ldbl-128/s_tanhl.c
index 129735b1b5..8b1706fcdc 100644
--- a/sysdeps/ieee754/ldbl-128/s_tanhl.c
+++ b/sysdeps/ieee754/ldbl-128/s_tanhl.c
@@ -41,6 +41,7 @@
  *      only tanhl(0)=0 is exact for finite argument.
  */
 
+#include <float.h>
 #include <math.h>
 #include <math_private.h>
 
@@ -73,7 +74,14 @@ __tanhl (long double x)
       if (u.value == 0)
 	return x;		/* x == +- 0 */
       if (ix < 0x3fc60000)	/* |x| < 2^-57 */
-	return x * (one + tiny); /* tanh(small) = small */
+	{
+	  if (fabsl (x) < LDBL_MIN)
+	    {
+	      long double force_underflow = x * x;
+	      math_force_eval (force_underflow);
+	    }
+	  return x * (one + tiny); /* tanh(small) = small */
+	}
       u.parts32.w0 = ix;	/* Absolute value of x.  */
       if (ix >= 0x3fff0000)
 	{			/* |x| >= 1  */
diff --git a/sysdeps/ieee754/ldbl-128ibm/s_tanhl.c b/sysdeps/ieee754/ldbl-128ibm/s_tanhl.c
index fe396e9bd3..5342a8b19a 100644
--- a/sysdeps/ieee754/ldbl-128ibm/s_tanhl.c
+++ b/sysdeps/ieee754/ldbl-128ibm/s_tanhl.c
@@ -38,6 +38,7 @@ static char rcsid[] = "$NetBSD: s_tanh.c,v 1.7 1995/05/10 20:48:22 jtc Exp $";
  *	only tanh(0)=0 is exact for finite argument.
  */
 
+#include <float.h>
 #include <math.h>
 #include <math_private.h>
 #include <math_ldbl_opt.h>
@@ -66,7 +67,14 @@ long double __tanhl(long double x)
 	    if (ix == 0)
 		return x;		/* x == +-0 */
 	    if (ix<0x3c60000000000000LL) 	/* |x|<2**-57 */
+	      {
+		if (fabsl (x) < LDBL_MIN)
+		  {
+		    long double force_underflow = x * x;
+		    math_force_eval (force_underflow);
+		  }
 		return x*(one+x);    	/* tanh(small) = small */
+	      }
 	    if (ix>=0x3ff0000000000000LL) {	/* |x|>=1  */
 		t = __expm1l(two*fabsl(x));
 		z = one - two/(t+two);
diff --git a/sysdeps/ieee754/ldbl-96/s_tanhl.c b/sysdeps/ieee754/ldbl-96/s_tanhl.c
index 7ec6247315..035037c8c7 100644
--- a/sysdeps/ieee754/ldbl-96/s_tanhl.c
+++ b/sysdeps/ieee754/ldbl-96/s_tanhl.c
@@ -42,6 +42,7 @@ static char rcsid[] = "$NetBSD: $";
  *	only tanhl(0)=0 is exact for finite argument.
  */
 
+#include <float.h>
 #include <math.h>
 #include <math_private.h>
 
@@ -69,7 +70,14 @@ long double __tanhl(long double x)
 	    if ((ix|j0|j1) == 0)
 		return x;		/* x == +- 0 */
 	    if (ix<0x3fc8)		/* |x|<2**-55 */
+	      {
+		if (fabsl (x) < LDBL_MIN)
+		  {
+		    long double force_underflow = x * x;
+		    math_force_eval (force_underflow);
+		  }
 		return x*(one+tiny);	/* tanh(small) = small */
+	      }
 	    if (ix>=0x3fff) {	/* |x|>=1  */
 		t = __expm1l(two*fabsl(x));
 		z = one - two/(t+two);