Re: [Qemu-devel] [PATCH v1 1/1] target-arm: A64: Fix decoding of iss_sf in disas_ld_lit

["Edgar E. Iglesias" <edgar.iglesias@gmail.com>]

On Fri, Sep 30, 2016 at 12:42:27PM +0200, Thomas Huth wrote:
> On 30.09.2016 12:19, Edgar E. Iglesias wrote:
> > From: "Edgar E. Iglesias" <edgar.iglesias@xilinx.com>
> > 
> > Fix the decoding of iss_sf in disas_ld_lit.
> > The SF (Sixty-Four) field in the ISS (Instruction Specific Syndrome)
> > is a bit that specifies the width of the register that the
> > instruction loads to.
> > 
> > If cleared it specifies 32 bits.
> > If set it specifies 64 bits.
> > 
> > Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
> > ---
> >  target-arm/translate-a64.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c
> > index ddf52f5..eae25c3 100644
> > --- a/target-arm/translate-a64.c
> > +++ b/target-arm/translate-a64.c
> > @@ -2025,7 +2025,7 @@ static void disas_ld_lit(DisasContext *s, uint32_t insn)
> >          do_fp_ld(s, rt, tcg_addr, size);
> >      } else {
> >          /* Only unsigned 32bit loads target 32bit registers.  */
> > -        bool iss_sf = opc == 0 ? 32 : 64;
> > +        bool iss_sf = opc == 0 ? false : true;
> 
> You could simplify that to:
> 
> 	bool iss_sf = !(opc == 0);

I don't really see how that is simpler/clearer.

I considered:
bool iss_sf = opc != 0;

but felt the expanded one was clearer in particular as a patch for review.

In any case, I have no strong opinion on the syntax.

Cheers,
Edgar