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

[Weddington, E. <Eri...@at...>]

Hi Borja!

Sorry to respond late to this email...

This is really exciting!

You said you need help in getting a basic toolchain working. Help me understand in detail, what you have, and where you want to be.

We need avr-gcc to run the assembler and linker. From avr-llvm, we have a compiler that will compile C to assembler. I would think that we would need to modify the avr-gcc specs to call the correct (new) executable for the compilation step.

If you can give me a few more details on your setup, then let's see where we can go with it. :-)

Eric

> -----Original Message-----
> From: Borja Ferrer [mailto:bor...@gm...]
> Sent: Tuesday, August 28, 2012 4:24 PM
> To: avr...@li...
> Subject: [avr-llvm-devel] Toolchain support needed!
> 
> 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!