A new calling convention in VS2013

[bearophile]

Benjamin Thaut:

> http://d.puremagic.com/issues/show_bug.cgi?id=10226

I see there are codegen inefficiencies.


> Until dmd uses the XMM registers correctly it doesn't make much 
> sense to add a special calling convetion for this purpose.

I don't agree, because:
- Even if DMD codegen is far from not perfect, it's a good idea 
to improve all things in parallel. Generally improving things (or 
fixing bugs) gives a better result if you adopt a pipelined 
development approach.
- A vector calling convention is meant to be usable on other 
compilers too, like LDC2, that have better codegen. (The asm I 
have shown in this thread comes from LDC2 because dmd doesn't 
even use SIMD registers on Windows 32 bit).

Bye,
bearophile