[LLVMdev] New 8bit micro controller back-end

[Guillaume Deroire]

Thanks for this feedback, I think our chip architecture is between a PIC16
and a 8051.

You have written 18 months, but with how many developpers ?

I will take a look at the PIC16 LLVM port to have a better view of the work
done and todo.

Regards

Guillaume

2009/11/23 <Alireza.Moshtaghi at microchip.com>

>  Our 8-bit port for PIC16 has taken roughly about 18 months to get to
> where we are now. Our instruction set is not orthogonal, data memory is
> banked, program memory is paged, there is only one accumulator and two
> pointer registers, and the use of indirect memory access is really
> expensive. So we had to implement some non conventional approaches to get
> the model working.
>
> For the most part, LLVM generic optimizations (except for mem2reg kind of
> optimizations) reduce the code size pretty good and typical applications
> that we use for PIC16 fit in the memory without problem.
>
> We use clang and LLVM just to generate assembly output. We have our own
> assembler, linker and debugger. In fact we have to implement some of our
> tricks in the linker and assembler in order to allow mix of C and assembly
> projects. If your users only want to use C, then you can probably use a lot
> more of the analysis capabilities of LLVM than what we use.
>
> Our ABI and model of code generation is probably far from what you need,
> but you may find some tricks in our port that can be useful to you as well.
>
>
>
> Regards
>
> Ali
>
>
>  ------------------------------
>
> *From:* llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] *On
> Behalf Of *Guillaume Deroire
> *Sent:* Monday, November 23, 2009 6:46 AM
> *To:* LLVM Developers Mailing List
> *Subject:* [LLVMdev] New 8bit micro controller back-end
>
>
>
> Hi all,
>
> I'm new to LLVM dev mailling list and I'm starting to discover some aspects
> of LLVM.
>
> Actually I'm looking for a solution to create a tool chain for my own chip
> (a 8bit micro controller processor) that include a compiler/linker/assembler
> toolset and a simulator/debugger.
>
> >From what I've read, LLVM is a good tool to implement a compiler for this
> proprietary platform, but I have the following questions:
> - Is there estimation (from your experiences) of the work required to
> implement a backend for a simple 8bits micro controller architecture (1
> men-month, 10 or 100 ?)
> - Is it possible to create a debugger/simulator (at C and assembler level)
> with LLVM ?
>
> Thanks for your help and advices
>
> Regards
>
> Guillaume
>
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