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 3f55c55..dbb7b46 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 ea8bb6d..5ca3de8 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 c32e436..b14146e 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 b4114be..4d8bcf2 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 3603765..de53451 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 23cfcde..4f9fcfd 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 dc96da9..5b48fb2 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 129735b..8b1706f 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 fe396e9..5342a8b 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 7ec6247..035037c 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);