std.math performance (SSE vs. real)

[Sean Kelly via Digitalmars-d]

On Thursday, 3 July 2014 at 21:01:43 UTC, Jonathan M Davis via
Digitalmars-d wrote:
>
> I'm fine with real varying from platform to platform depending 
> on what makes sense for that platform, but I think that it 
> should be clear what real is generally supposed to be (e.g. the 
> largest floating point type that the hardware supports), but 
> unless it's _guaranteed_ that real be the same as long double, 
> I would strongly argue in favor of having an alias for long 
> double rather than using real directly (much as it will likely 
> be an alias to real in most cases). We already do that with 
> c_long.

I'm inclined to agree.  From what's been said, I suspect that on
SPARC, 'real' would be an alias of 'double', and c_long_double
would be an alias of some intrinsic type provided by the
compiler, since there is no D equivalent for the IEEE 754
binary128 type.  The alternative, making c_long_double a struct
used for marshaling data into and out of the C format, doesn't
seem terribly appealing.