Re: [Qemu-devel] [PATCH 2/2] ppc: Convert op_andi to TCG

[Andreas Färber]

Am 14.09.2008 um 13:53 schrieb Blue Swirl:

> On 9/14/08, Andreas Färber <address@hidden> wrote:
> > Am 14.09.2008 um 13:35 schrieb Blue Swirl:
> >
> >
> >
> > > On 9/14/08, Andreas Färber <address@hidden> wrote:
> > >
> > > > Replace op_andi_... with tcg_gen_andi_tl.
> > >
> > >
> > > > GEN_HANDLER2(andi_, "andi.", 0x1C, 0xFF, 0xFF, 0x00000000,  
> > > > PPC_INTEGER)
> > > > {
> > > >   tcg_gen_mov_tl(cpu_T[0], cpu_gpr[rS(ctx->opcode)]);
> > > > -    gen_op_andi_T0(UIMM(ctx->opcode));
> > > > +    tcg_gen_andi_tl(cpu_T[0], cpu_T[0], UIMM(ctx->opcode));
> > > >   tcg_gen_mov_tl(cpu_gpr[rA(ctx->opcode)], cpu_T[0]);
> > > >   gen_set_Rc0(ctx);
> > > > }
> > >
> > > Small comment: this would be more optimally:
> > >  tcg_gen_andi_tl(cpu_gpr[rA(ctx->opcode)],
> > > cpu_gpr[rS(ctx->opcode)], UIMM(ctx->opcode));
> > >
> > > The same applies to andis.
> >
> > Careful there, iirc this cannot be done before gen_set_Rc0 is  
> > converted!
>
> I didn't mean to remove gen_set_Rc0, the comment only applied to the
> mov+andi+mov sequence.

Right, but this optimization would require to move from gpr to T0  
after the suggested mov+andi+mov optimization and before this  
gen_set_Rc0 thing. That would still save one line, so feel free to  
modify my patch or apply another one on top.

Andreas