Re: [Qemu-devel] [PATCH 5/8] tcg: Add interpreter for bytecode

[Stefan Weil]

Am 18.09.2011 06:03, schrieb Andi Kleen:
> Stefan Weil <address@hidden> writes:
> > +
> > + switch (opc) {
> > + case INDEX_op_end:
> > + case INDEX_op_nop:
> > + break;
>
> You could probably get some more speed out of this by using a threaded
> interpreter with gcc's computed goto extension. That's typically
> significantly faster than a plain switch in a loop.
>
> static void *ops[] = {
> &&op1,
> &&op2,
> ...
> };
>
> #define NEXT() goto *ops[*tb_ptr++];
>
> op1:
> ...
> NEXT();
>
> -Andi

Is there really any difference in the generated code?
gcc already uses a jump table internally to handle the
switch cases.

- Stefan