Re: [avr-llvm-devel] Toolchain support needed!

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

HI Borja,

Have you gone any farther with trying to setup a toolchain? It looks like
clang can just be installed using the same PREFIX that avr-gcc was
installed with in order to keep them in the same folder.

The include path is hard coded in clang (except for Windows and Linux
targets). So a quick and dirty way would be to make a patch to change it.
Clang has Driver & Toolchain classes which I think needs to be modified to
support an AVR target.


On Tue, Aug 28, 2012 at 3:24 PM, Borja Ferrer <bor...@gm...> wrote:

> Hello,
>
> With the latest changes, the backend is reaching the point where it can
> compile nearly any sort of code. One thing that is missing is support for
> inline asm which is heavily used in avr-libc, but apart from that it should
> be able to compile the rest. With a few tweaks i've been able to compile a
> 2200 line C file that stresses floating point calculations that produces
> around 22k instructions (C file -> S file)
>
> Now I'm getting more interested on getting a very basic toolchain working,
> Eric we'll need your help here. I've been able to build from a C file to a
> hex file a very basic main() function. avr-gcc is needed to produce the elf
> files and to drive the linker, so we'll have to stick with it for a while.
> The setup I have is messy because avr-gcc is in one folder with avr-libc
> and clang and llvm in another, so in order to get the toolchain with a
> decent setup both things should be in the same folder. Also included files
> default to the system's not the avr specific ones. Maybe others have tried
> it before, so i want to know how you did it or how hard it was, but in my
> case my first try was yesterday.
>
> Also I'm going to change how register-pairs are represented because avr-as
> can't understand what r29:r28 is. The llvm asm writer needs a bit of
> tweaking because avr-as can't understand some asm directives it produces.
>
> This is the cmd line i'm using to generate an object file: clang -O3
> test.c -o test.o -ccc-host-triple avr-generic-generic -ccc-gcc-name avr-gcc
> -mmcu=avr5
> notice that avr-gcc is passed so that clang can drive it once the .S file
> is generated.
>
> So try compiling a trivial main function to get the hex file generated,
> you'll need avr-copy (provided by binutils) to convert the elf file to hex,
> but that is easily handled by makefiles. Also people using windows try
> doing it aswell since I dont have a setup for it and I'm looking forward
> for it.
>
> Once we get the basic toolchain working, adding support for avr-libc and
> linking programs with its libraries should be much easier. I look forward
> for any help here!
>
>
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