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

[Borja F. <bor...@gm...>]

Hello John,
I havent created yet a SF account, but i could create one right now. I'm
currently developing for version 2.7, v2.8 is going to be released in a few
days so i will need to update my code for then because there has been some
changes in the interfaces. What i thought is to wait for the release, update
my code to make it compatible and then merge it into here.
Yes there are places that are a bit farther ahead, but others not. For
example, i've seen you've already added some code thinking on memory
addresses for IO and that stuff but i havent touched that at all yet.

As a side note, if it's possible to know, how many devs are involved in the
project and what is the time availability of them. Im asking this because i
noticed last commit was from march and you're the only one that is really
commiting code, so i want to know what is the status of the project and if
there are any plans.

Thanks.

2010/9/24 John Myers <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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>