[PATCH v4 07/21] math: Remove the SVID error handling from remainder

[Wilco Dijkstra]

Hi Adhemerval,

@@ -36,7 +38,7 @@ __ieee754_remainder (double x, double y)
     {
       /* |x| not finite, |y| equal 0 is handled by fmod.  */
       if (__glibc_unlikely (hx >= EXPONENT_MASK))
-	return (x * y) / (x * y);
+	return __math_invalid (x);

Since we are unconditionally calling fmod (which has the same
error conditions and sets errno after patch 1/21), wouldn't it be
simpler to now let it handle all error conditions?

       x = fabs (__ieee754_fmod (x, y + y));

Changing to __fmod would be clearer I think.

       if (x + x > y)
@@ -53,8 +55,13 @@ __ieee754_remainder (double x, double y)
   else
     {
       /* |x| not finite or |y| is NaN or 0 */

Remove "or 0" - y == 0 is not possible here.

-      if ((hx >= EXPONENT_MASK || (hy - 1) >= EXPONENT_MASK))
-	return (x * y) / (x * y);
+      if (__glibc_unlikely ((hx >= EXPONENT_MASK
+			     || (hy - 1) >= EXPONENT_MASK)))

Should be: hy > EXPONENT_MASK since we don't need to handle
zero here.

At this point we have (hx is Inf) or (hx is NaN) or (hy is NaN).

+	{
+	  if (is_inf (hy))
+	    return __math_invalid (x);
+	  return (x * y) / (x * y);
+	}

Ie. is_inf (hy) is always false and we never set errno if x is infinite.
This should be:

return __math_invalid (x * y);

If either is NaN this will return NaN and not set errno, otherwise if
x is infinite, it will set errno.

Cheers,
Wilco