Using YMM registers causes an undefined label error

[Rumbu]

On Saturday, 6 March 2021 at 12:15:43 UTC, Mike Parker wrote:
> On Saturday, 6 March 2021 at 11:57:13 UTC, Imperatorn wrote:
>
>> What... Is this really how it's supposed to be? Makes no sense 
>> to not use any of the existing conventions.
>
> extern(C) and extern(D) are both documented to be the same as 
> the platform's C calling convention everywhere except x86 
> windows:
>
> https://dlang.org/spec/abi.html#function_calling_conventions
>
> There have been times when differences were noted (I recall a 
> particularly bad one related to passing structs by value on 
> 64-bit linux) and there may be more. When they are, they should 
> be reported in Bugzilla.

Where exactly is documented the extern(D) x86-64 calling 
convention? Because currently seems like a mess according to the 
dissasembly. First X parameters on stack from left to right, last 
4 in registers. But wait, if you have less than 4 parameters, 
they are passed in register. Again, WTF?