third draft: add bitfields to D

[IchorDev]

On Monday, 22 July 2024 at 21:23:04 UTC, claptrap wrote:
> x86 CPUs favour type alignment not pointer size alignment, 
> bytes 1 align, shorts 2 align and so on.
>
> It's mostly to avoid buggering up the store to load forwarding 
> IIRC. Which is basically a way of making recent writes faster 
> to retrieve when they are loaded again.

Pointer size was me simplifying for the sake of brevity, but I 
was taught that i386-based processors are generally fastest with 
4-byte memory alignment, and AMD64-based processors are generally 
fastest with 8-byte memory alignment.