Fix wrong ussage of sincos for subnormal arguments

[thirdparty/glibc.git] / math / s_ctanhl.c

diff --git a/math/s_ctanhl.c b/math/s_ctanhl.c
index dbf1612707208500233e821280f60b43bc99ce3b..c4fc1d3d04829abe16d4068eb54b99dbb818f7ca 100644 (file)
--- a/math/s_ctanhl.c
+++ b/math/s_ctanhl.c
@@ -53,11 +53,20 @@ __ctanhl (__complex__ long double x)
       long double sinix, cosix;
       long double den;
       const int t = (int) ((LDBL_MAX_EXP - 1) * M_LN2l / 2);
+      int icls = fpclassify (__imag__ x);
 
       /* tanh(x+iy) = (sinh(2x) + i*sin(2y))/(cosh(2x) + cos(2y))
         = (sinh(x)*cosh(x) + i*sin(y)*cos(y))/(sinh(x)^2 + cos(y)^2).  */
 
-      __sincosl (__imag__ x, &sinix, &cosix);
+      if (__builtin_expect (icls != FP_SUBNORMAL, 1))
+       {
+         __sincosl (__imag__ x, &sinix, &cosix);
+       }
+      else
+       {
+         sinix = __imag__ x;
+         cosix = 1.0;
+       }
 
       if (fabsl (__real__ x) > t)
        {