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

[Fabrice Bellard]

Zoltán Lörincz wrote:
> 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?

The solution was implicit in my previous mail: you must include in the 
opcode the register numbers. That why I spoke about 9 opcodes per 
operation if 3 registers are used.

Fabrice.