Re: [Qemu-devel] [5100] SH4: Convert register moves to TCG

[Thiemo Seufer]

Aurelien Jarno wrote:
> On Thu, Aug 28, 2008 at 11:13:42PM +0100, Paul Brook wrote:
> > On Thursday 28 August 2008, Aurelien Jarno wrote:
> > > +static always_inline void gen_movl_T_rN (TCGv t, int reg)
> > > +{
> > > +    tcg_gen_st_tl(t, cpu_env, offsetof(CPUState, gregs[reg]));
> > 
> > The preferred way of doing this is to have TCG variables for common 
> > (possibly 
> > all?) registers. See e.g. m68k or sparc.
> > 
> 
> Until now I have used MIPS as an example, it copies CPU registers to TCG
> variables. As you pointed, m68k and sparc use direct access to CPU
> registers through TCG variables.

For MIPS I tried to keep thing similiar to dyngen when both TCG and
dyngen were used. Then I converted a few places to use TCG variables
but had no time to finish the job.

> I wonder in which way what your propose is better? It seems easier to write,
> but what about the runtime speed?

TCG variables are (potentially) better.


Thiemo