DMD Backend: Deciding instructions to use/avoid?

[Don]

Nick Sabalausky wrote:
> So my main question: Does DMD do anything like, say, detecting the CPU at 
> compile time and then enabling instructions only available on that CPU and 
> up? Or does it do anything like always assuming the target CPU has SSE2? 
> Anything like that that could cause differences between our CPUs to result 
> in object code that will work on one of the CPUs, but not the other? FWIW, 
> the CPU on my linux box is i686, so it's not like I'm on some 
> super-ultra-old i586, or anything like that. 

DMD itself doesn't, but the array operations do. The DMD backend is 
ancient, and generates code for original Pentiums (+ 64 bit equivalents 
of the same instructions).