dmd codegen improvements

[Walter Bright via Digitalmars-d]

On 8/18/2015 6:01 AM, ponce wrote:
> One thing that was striking to me is that it by and large it doesn't use PUSH,
> POP, and SETcc. Actually I don't remember such an instruction being emitted by it.
>
> And indeed using PUSH/POP/SETcc in assembly were often slower than the
> alternative. Which is _way_ different that the old x86 where each of these
> things would gain speed.

The 32 bit code generator does a lot of push/pop, but the 64 bit one does far 
less because function parameters are passed in registers most of the time.