Any chance of 128-bit alignment of static arrays?

[Don Clugston]

Jarrett Billingsley wrote:
> "Dan" <murpsoft at hotmail.com> wrote in message 
> news:fg61am$2p80$1 at digitalmars.com...
> 
>> Heh, actually Walter, I've been studying alot on osdev.org, and I've 
>> completely given up with D because it only allows me to program for an 
>> obsolete platform.
>>
>> I really do like the notation, but it's the final code that counts, and 
>> only YASM assembler is letting me do what I need to.
>>
>> If I may be so brash; D needs ucent, 16-byte alignment, XMM8-15, R*X 
>> 64-bit GPR's, the amd64 instruction set, version(Windows64), 
>> version(linux64), and version(DInline_Asm*) with that featureset.
> 
> You must not have heard of GDC.  My friends and I are using it and its 
> extended inline ASM to write a kernel for x86-64 in D.  Keep in mind that 
> the inline ASM provided by the DMDFE isn't supposed to be the _only_ inline 
> ASM that compilers can support.

It would be horrible if that situation persists long-term, though. It's 
fantastic to be able to write asm code that will work on Linux and Windows.

   TBH I kind of like the route GDC has taken
> in this regard, as it means traditional ASM syntaxes can be preserved, 
> instead of having to map them, possibly unfavorably, to fit in with the 
> syntactic boundaries of the D grammar.
> 
>> If ucent is done properly, I understand it'll take alot of work.  You'd 
>> want to bind it to the XMM registers and they use completely different 
>> instructions than ulong's and uints.
> 
> I don't really see how ucent at all maps to XMM registers.. [u]cent is an 
> integer type, which would probably be represented as a RDX:RAX pair, much as 
> [u]long is EDX:EAX in x86.  The multimedia registers are completely 
> different semantically, and mapping them to an integer type makes no sense.

Agreed. I haven't found any XMM instructions which use 128-bit integers. Only 
pairs of QWORDS.

> 
> If D did include i.e. float4, meaning 4 32-bit IEEE 754 floats to be put 
> into a SIMD register, it would be a first for any programming language. 

I wonder if there is any advantage to float4 over float[4] ? (with float[4] 
being optimised specially by the compiler to be SIMD). It would allow you to use 
  SIMD registers for parameter passing in extern functions, I guess.