Re: [Nasm-devel] Feature request: fine-grain control over instruction encoding forms

[H. P. A. <hp...@zy...>]

On 11/20/2012 07:37 AM, Marat Dukhan wrote:
>
> Example for rex keyword:
>
>     MOV ecx, [rsi] ; encoded without REX
>     rex MOV ecx, [rsi] ; encoded with REX
>
>
> Example for vex3 keyword:
>
>     VPADDD xmm0, xmm0, xmm0 ; encoded with 2-byte VEX prefix
>     vex3 VPADDD xmm0, xmm0, xmm0 ; encoded with 3-byte VEX prefix
>
> Is there any chance to get these features in NASM?
>

Well, there are a few problems:

First, NASM is largely a volunteer project, so getting the resources to 
do it is always a problem.

Second, and this may be the bigger issue, is that it causes namespace 
issues; someone may be using e.g. "rex" as a variable.  However, the 
Xeon Phi assembler syntax already are addressing this by adding new 
keywords recognized only if they are inside curly braces, so perhaps we 
could just make that a general keyword space and make the syntax {rex} 
and so on.

Third, covering all the cases and making them work with the matching 
engine could take a fair bit of time.

If you are interested in this as a project, it is certainly something 
that would be welcome.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.