Re: [sdcc-devel] Adding TMS9900 back end

[Mark B. <ma...@bu...>]

On 08/02/2025 10:25, Philipp Klaus Krause wrote:
> There is a bit of information about adding a port at
> https://sourceforge.net/p/sdcc/wiki/Adding%20a%20port/
Thanks - I've taken a look - very interesting.
> My main worry here is the large number (16) of large (16 bit) registers
> in the TMS9900. A Chaitin-style graph coloring register allocator, as
> used by GCC, is most likely better for that than the register allocators
> we currently have in SDCC.
>
> Also, I have no idea how much work it would be to get your existing GCC
> 4.4 backend updated for current GCC, so it is hard for me to compare
> with the effort of creating a new SDCC port.
I've taken a look at the backends for stm8 and z80.  There are a few 
similarities to the GCC insns but it is overall very different and looks 
like it would be a very significant porting exercise.  Given your 
comment about the register allocator it sounds like it would be better 
to stick with the plan to upgrade the latest GCC instead.
> I haven't looked into the byte orderings yet. But "a few quirks", or a
> few more, is something you'll find in all SDCC targets.
Very true!

Thanks,

Mark