second draft: add Bitfields to D

[user1234]

On Friday, 3 May 2024 at 15:50:42 UTC, user1234 wrote:
> On Friday, 3 May 2024 at 12:52:09 UTC, Patrick Schluter wrote:
>> Not true. x86 provides BMI1 instructions which are present in 
>> x86 CPUs at least since 2013.
>> ARM also provides bit field instructions and quite a number of 
>> legacy CPU's also had bitfield instructions (m68k, NEC V30, 
>> Itanium, PowerPC, etc.).
>> Doesn't change the issues with language bitfields
>
> About BMI/BMI2 it would interesting to see if optimizing 
> compilers actually generate instructions of these extensions 
> for c++ bitfields. I've tried for styx enum-sets, sure that's a 
> bit a special case of bitfields, but so far the only difference 
> visible is a BMI2 `shlxl` emitted. But once again very special 
> case.

![](https://i.imgur.com/Uw6qZ1g.png)