floating point verification using is?

[Steven Schveighoffer]

On Fri, 18 Dec 2009 21:47:22 -0500, bearophile <bearophileHUGS at lycos.com>  
wrote:

> Unfortunately the asm produced by ldc shows the call to the array  
> equality function still. Fifth try:
>
>
> bool isInitNaN(T)(T x) if (isFloatingPoint!T) {
>     union FPData {
>         T f;
>
>         static if (T.sizeof == uint.sizeof) {
>             uint data;
>         } else static if (T.sizeof == ulong.sizeof) {
>             ulong data;
>         } else static if (T.sizeof == 10) {
>             ulong data1;
>             ushort data2;
>         } else static if (T.sizeof == 12) {
>             ulong data1;
>             uint data2;
>         } else static if (T.sizeof == 16) {
>             ulong data1;
>             ulong data2;
>         } else {
>             ubyte[T.sizeof] data;
>         }
>     }
>
>     static FPData fnan, fpd;
>     fpd.f = x;
>
>     static if (T.sizeof == 10 || T.sizeof == 12 || T.sizeof == 16)
>         return fnan.data1 == fpd.data1 && fnan.data2 == fpd.data2;
>     else
>         return fnan.data == fpd.data;
> }
>
> Bye,
> bearophile

Are you still working on this?  :)  I think this proves my point.  The  
compiler does not provide an easy way to compare floats bitwise, so this  
means convoluted hard-to-write code.  When we have two operators that do  
equality -- and one of those means bitwise compare in all other contexts  
-- I think this is a no-brainer.

-Steve