Re: [Qemu-devel] [PATCH 06/10] target-mips: add microMIPS ASE support

[Nathan Froyd]

On Fri, Jun 04, 2010 at 11:30:38AM -0700, Richard Henderson wrote:
> On 05/24/2010 09:19 AM, Nathan Froyd wrote:
> > +    int (*ldfun)(target_ulong);
> > +
> > +    switch (mem_idx)
> > +    {
> > +    case 0: ldfun = ldl_kernel; break;
> > +    case 1: ldfun = ldl_super; break;
> > +    default:
> > +    case 2: ldfun = ldl_user; break;
> > +    }
> 
> This *should* now be a compile error.  The return type should
> now be "uint32_t", not "int".

Will fix, thanks for pointing that out.

> > @@ -2535,26 +2555,29 @@ static void gen_compute_branch (DisasContext *ctx, 
> > uint32_t opc,
> >          case OPC_JALX:
> >              ctx->hflags |= MIPS_HFLAG_BX;
> >              /* Fallthrough */
> > +        case OPC_JALS:
> >          case OPC_JAL:
> >              blink = 31;
> >              ctx->hflags |= MIPS_HFLAG_B;
> > -            ctx->hflags |= (ctx->hflags & MIPS_HFLAG_M16
> > +            ctx->hflags |= (opc == OPC_JALS
> >                              ? MIPS_HFLAG_BDS16
> >                              : MIPS_HFLAG_BDS32);
> 
> Changed semantics here?  You're no longer testing M16 bit.
> Or is that later handled by switching mips16 to JALS too?

It ought to be handled by switching mips16 to use JALS.  I see that I
didn't do that.

> And if so, perhaps this patch should be broken into two, where
> you introduce the new opcodes and hflags changes and apply them
> as-needed to the mips16 code.  Thus one can verify that the
> semantics for mips16 are the same before and after.

I don't think there are any hflags changes, but the point is
well-taken.  I'll do that.

> > +    if (base == 0) {
> > +        tcg_gen_movi_tl(t0, 0);
> > +    } else {
> > +        gen_load_gpr(t0, base);
> > +    }
> 
> gen_load_gpr already takes care of R0.

Will fix.

> > +#if 0
> > +    case 0x01:
> > +        switch (minor) {
> > +        case MFHI_ACC:
> > +            gen_HILO(ctx, OPC_MFHI, rs);
> 
> New if 0 code?

Yup, will delete.

-Nathan