Re: [avr-llvm-devel] New backend implementation

[John M. <ato...@gm...>]

Hi,

I also think merging the projects would be good. Do you have a SourceForge
account? I can add you as a developer.
Are you developing off the trunk or a release? Our code is stale now, since
we haven't been keeping up with the trunk.
It sounds like your code is farther ahead in producing code.

--John


On Fri, Sep 24, 2010 at 6:06 AM, Borja Ferrer <bor...@gm...> wrote:

> Hello everybody, I've been working lately in the AVR backend for LLVM by
> myself until i've found this project. I'm not completely happy with the code
> GCC produces so i decided to take on with this challenge. I think it would
> be a good idea to join our efforts in this project, instead of duplicating
> the work if we do it by separate.
>
> My current code has the following status:
>
> - It can build and emit AVR asm code for very basic C code.
> - Produce code for all arithmetic and binary operators and for different
> sizes wider than char (except division for larger types which will end being
> a lib call).
> - Basic support for shifts, currently only by a constant number. (We needed
> here customized shifts because AVR only supports shifts by 1).
> - Support for the multiplication instruction.
> - Support for input function arguments and return values of any size.
> - Code pass to fold two move instructions into a movw. (I dont like this as
> a final solution since i prefer patching the DAG before codegen but it works
> atm).
> - Very basic support for function calls (I'm currently working into this).
>
> My code looks very similar to the one in this project with some exceptions,
> for example the instruction formats and instruction description. I've taken
> a different approach on encoding instructions trying to pack instructions by
> format like Reg,Reg or Reg, K, etc so we end up encoding them in a compact
> form.
>
> I've been running some tests and the code produced looks very promising,
> LLVM produces more compact code than gcc without having written any single
> optimization yet in my code. Of course there are cases that need tuning, but
> I think optimizations should be left for a later stage in development until
> things work decently. Although i couldnt resist on this last point, i've
> reported some missed optimizations in the LLVM dev list, and filled them as
> a bug report. One great thing about LLVM is that you get pretty fast support
> and things get fixed much faster than for GCC where a bug report can be open
> for 8 years.
>
> Well let me know what you think and if we can merge our code.
>
> Thanks
>
>
>
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