Re: [Tinycc-devel] Questions about backend writing

[Thomas Preud'homme]

Le samedi 2 novembre 2013 03:21:10 yazgoo a écrit :
> Hi,
> 
> I'd like to try and write a backend for TCC.
> Is there more documentation than:
> http://bellard.org/tcc/tcc-doc.html#SEC34 ?

Unfortunetaly only the code (and the few comments) can help you at this stage. 
It would be really nice if someone improve tcc-doc with some more examples to 
explain and more details. I'd really enjoy if tcc could become a code that 
people (esp. students) use to learn compilation.

> More precisely, I'd be interested in knowing:
> 
> 1. how load and store functions work, especially why in my tests I always
> have a store call after a load call;

No clue sorry. Could you be more precise as to what tests you did?

> 2. if it is possible to use a custom assembler and how to do so;

you mean like gas? Well, tcc doesn't output assembler but directly output 
instruction. So no, you can't use a custom assembler, unless you plan to write 
an asm backend first.

> 3. how to use labels to call functions (if it is the good way);

I'm not sure what you mean by labels here.

> 4. what the following warning means:
> "../main.c:16: warning: internal compiler error: vstack leak? (4)"

You pushed to many things on the value stack. Since this stack is implemented 
with a fixed-size buffer, reaching it's end generate this error. It's 
considered 
that the size is big enough and only a vstack leak (push without pop) can lead 
to such a situation.

> 
> Regards

Best regards and good luck in your project.

Thomas