msvcrt: Import tanhf implementation from musl.

dlls/msvcrt/math.c

@@ -1512,9 +1512,43 @@ float CDECL tanf( float x )
  */
 float CDECL tanhf( float x )
 {
-  float ret = unix_funcs->tanhf(x);
-  if (!isfinite(x)) return math_error(_DOMAIN, "tanhf", x, 0, ret);
-  return ret;
+    UINT32 ui = *(UINT32*)&x;
+    int sign;
+    float t;
+
+    /* x = |x| */
+    sign = ui >> 31;
+    ui &= 0x7fffffff;
+    x = *(float*)&ui;
+
+    if (ui > 0x3f0c9f54) {
+        /* |x| > log(3)/2 ~= 0.5493 or nan */
+        if (ui > 0x41200000) {
+#if _MSVCR_VER < 140
+            if (isnan(x))
+                return math_error(_DOMAIN, "tanhf", x, 0, x);
+#endif
+            /* |x| > 10 */
+            fp_barrierf(x + 0x1p120f);
+            t = 1 + 0 / x;
+        } else {
+            t = __expm1f(2 * x);
+            t = 1 - 2 / (t + 2);
+        }
+    } else if (ui > 0x3e82c578) {
+        /* |x| > log(5/3)/2 ~= 0.2554 */
+        t = __expm1f(2 * x);
+        t = t / (t + 2);
+    } else if (ui >= 0x00800000) {
+        /* |x| >= 0x1p-126 */
+        t = __expm1f(-2 * x);
+        t = -t / (t + 2);
+    } else {
+        /* |x| is subnormal */
+        fp_barrierf(x * x);
+        t = x;
+    }
+    return sign ? -t : t;
 }
 
 /*********************************************************************

dlls/msvcrt/unixlib.c

@@ -269,14 +269,6 @@ static float CDECL unix_powf( float x, float y )
 }
 
 /*********************************************************************
- *      tanhf
- */
-static float CDECL unix_tanhf( float x )
-{
-    return tanhf( x );
-}
-
-/*********************************************************************
  *      tgamma
  */
 static double CDECL unix_tgamma(double x)
@@ -327,7 +319,6 @@ static const struct unix_funcs funcs =
     unix_log2f,
     unix_pow,
     unix_powf,
-    unix_tanhf,
     unix_tgamma,
     unix_tgammaf,
 };

dlls/msvcrt/unixlib.h

@@ -46,7 +46,6 @@ struct unix_funcs
     float           (CDECL *log2f)(float x);
     double          (CDECL *pow)(double x, double y);
     float           (CDECL *powf)(float x, float y);
-    float           (CDECL *tanhf)(float x);
     double          (CDECL *tgamma)(double x);
     float           (CDECL *tgammaf)(float x);
 };