Re: [Qemu-devel] [PATCH] tcg, tci: Add TCG and interpreter for bytecode (virtual machine)

[Blue Swirl <blauwirbel@gmail.com>]

On Mon, Sep 28, 2009 at 7:50 PM, Stefan Weil <weil@mail.berlios.de> wrote:
> This is an initial and highly experimental version of
> a new code generator which does not create native code
> (so it will not depend on the host running qemu when it
> is finished). It creates bytecode which is interpreted.
>
> The current version can run the bios code, a simple
> hello world and the linux-user testcode for the
> i386 and x86_64 targets on x86_64 hosts.
>
> Some additional information is in tcg/bytecode/README
> which is part of the patch.
>
> Please send patches / enhancements based on my latest
> version from git://repo.or.cz/qemu/ar7.git.

Nice. When the interpreter works, it should be unconditional for
targets that are not supported by TCG.

> +QEMU can create native code for some hosts (arm, hppa, i386, ppc, ppc64,
> +sparc, x86_64). For others, inoffical host support was written (s390).

unofficial

> +static const int tcg_target_call_oarg_regs[2] = {
> +    // TODO: ppc64 only uses one register. Why do others use two?

To pass a 64 bit return value in two 32 bit registers?

> +static const char * const tcg_target_reg_names[TCG_TARGET_NB_REGS] = {

> +#if TCG_TARGET_NB_REGS == 16 || TCG_TARGET_NB_REGS == 32

> +    "r16",

Table overflow.