[fpc-devel] APX instruction set

[J. Gareth Moreton]

FPC is always going to be a bit behind the curve because gcc, for 
example, has corporate sponsors.  Heck, when I interviewed for a role at 
ARM (which I didn't get), they made clear that they help develop GCC and 
LLVM directly.  Can't easily compete with the actual CPU manufacturers 
contributing code!  Still, we do our best.

One thing I'm trying to work on at the moment is auto-vectorisation.  
Currently it's just for x86_64, but keeping things as generic as 
possible for AArch64 support too, and of course, for future Intel 
instruction sets.

Kit

On 21/05/2025 18:43, Marģers . via fpc-devel wrote:
> Hi,
>
> I am looking forward to implement APX instructions set. APX extend 
> general purpose register count to 32. By reading official 
> documentation about instructions sets from Intel it come to my 
> attention that APX is in Intel's road map for upcoming Diamond Rapids 
> cpu. It will be in metal rather sooner than later (probable year of 
> launch 2026). In Gas (tested ver 2.44) APX support is already 
> implemented.
>
> There has been ignored problem with instruction implementation in fpc. 
> Assumption that there is one fixed number of operators for opcode. 
> This is not a case as of today. It is ignored or handled as special 
> cases somewhere in code.
>
> As new addition to legacy instructions from map 0 and map 1 is 3 
> operator version. So most common instructions will have 2 and 3 
> operator version.
>
> The question is how to handle this for days to came?
>
> For example in x86ins.data it could be
>
> [ADD,addX]
> (Ch_Mop2, Ch_Rop1, Ch_WOverflowFlag, Ch_WSignFlag, Ch_WZeroFlag, 
> Ch_WAuxiliaryFlag, Ch_WCarryFlag, Ch_WParityFlag)
> regmem,reg16|32|64    \320\1\x01\101                  8086,SM
> reg16|32|64,regmem    \320\1\x03\110                  8086,SM
> (Ch_Wop3, Ch_Rop2, Ch_Rop1, Ch_WOverflowFlag, Ch_WSignFlag, 
> Ch_WZeroFlag, Ch_WAuxiliaryFlag, Ch_WCarryFlag, Ch_WParityFlag)
> regmem,reg64,reg64    ...                   APX
> reg64,reg64,regmem    ...                   APX
>
> There are multiple options how to go on from here. I have few ideas.
>
> I am open to suggestions. As well, I would want to know what I have to 
> take into consideration?
>
> I have not started yet. This is good point in time to know if this 
> kind addition to fpc is welcome.
> Anyhow implementation will take couple of weeks or so.
>
> Margers
>
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