Re: [Tinycc-devel] TCC code generation for a stack based VM

[Zoltán Lörincz]

Hello Mirar,

thank you again for your answer.

I also thought that it would be easier to generate byte code for a
register based VM.

But then the interpreter, would be slower and more comlicated.

For example for an  i386 style asm code: "mov ax, bx" in the byte code
i should generate
- the opcode for move 
- then bitfields where i specify that the move is between ax and bx
(in our case)

Decoding this in the interpreter would take more processing time than
in a stack based machine.
 There I don't need to decode anything in this way, only to make a
switch by the opcodes and do the corresponding operations.

Do you have an idea how i could encode/decode the registers/immediate
values, without too much processing time?


Best regards,
Zoltan.





On Tue, 02 Nov 2004 19:48:57 +0100, Mirar <address@hidden> wrote:
> > Unfortunately it is not in my hands to change the requirements.
> 
> It was just an idea :)
> 
> > On the other hand, if we would use TCC for JIT compiling then for
> > every new processor we would need to write a code generator wich we
> > would like to avoid.
> 
> Nah, you would require TCC to work for every new processor. The code
> would stay the same (since it would be in C)? I didn't know you
> switched processors that often.
> 
> TCC is rather small though (a few 100k), quite comparable to an
> interpreter.
> 
> Why not make a registered based byte code interpreter, it might be
> easier then rewriting tcc? (I haven't seen any answer whether tcc can
> do that yet, but...)
> 
> /Mirar
>