target-arm/translate: Fix RRX operands

Instructions that both use the RRX second operand and update CS were
incorrect, as the Carry flag was updated too early. An example of such an
instruction would be:

ands r12,r13,RRX

Ands, because of the "s" flag will update the carry flag. But the RRX second
operand rotates through the C flag which should happen before the update.
Fixed the ordering of the two, the old carry is read by "r13,RRX" before being
updated.

Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Reported-by: Vinesh Peringat <vineshp@xilinx.com>
---
 target-arm/translate.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

On 16 October 2012 10:15, Peter Crosthwaite
<peter.crosthwaite@petalogix.com> wrote:
> Instructions that both use the RRX second operand and update CS were
> incorrect, as the Carry flag was updated too early. An example of such an
> instruction would be:
>
> ands r12,r13,RRX
>
> Ands, because of the "s" flag will update the carry flag. But the RRX second
> operand rotates through the C flag which should happen before the update.
> Fixed the ordering of the two, the old carry is read by "r13,RRX" before being
> updated.
>
> Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
> Reported-by: Vinesh Peringat <vineshp@xilinx.com>
> ---
>  target-arm/translate.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/target-arm/translate.c b/target-arm/translate.c
> index c6840b7..daccb15 100644
> --- a/target-arm/translate.c
> +++ b/target-arm/translate.c
> @@ -516,10 +516,10 @@ static inline void gen_arm_shift_im(TCGv var, int shiftop, int shift, int flags)
>              tcg_gen_rotri_i32(var, var, shift); break;
>          } else {
>              TCGv tmp = tcg_temp_new_i32();
> +            tcg_gen_shli_i32(tmp, cpu_CF, 31);
>              if (flags)
>                  shifter_out_im(var, 0);
>              tcg_gen_shri_i32(var, var, 1);
> -            tcg_gen_shli_i32(tmp, cpu_CF, 31);
>              tcg_gen_or_i32(var, var, tmp);
>              tcg_temp_free_i32(tmp);
>          }

Looks like this was broken by Aurelien's commit 66c374de8; previously
we loaded CF into a tmp before doing the shifter_out_im() [which updates CF],
and then used the tmp after the call, rather than directly using CF.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

-- PMM

On Wed, Oct 17, 2012 at 05:43:55PM +0100, Peter Maydell wrote:
> On 16 October 2012 10:15, Peter Crosthwaite
> <peter.crosthwaite@petalogix.com> wrote:
> > Instructions that both use the RRX second operand and update CS were
> > incorrect, as the Carry flag was updated too early. An example of such an
> > instruction would be:
> >
> > ands r12,r13,RRX
> >
> > Ands, because of the "s" flag will update the carry flag. But the RRX second
> > operand rotates through the C flag which should happen before the update.
> > Fixed the ordering of the two, the old carry is read by "r13,RRX" before being
> > updated.
> >
> > Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
> > Reported-by: Vinesh Peringat <vineshp@xilinx.com>
> > ---
> >  target-arm/translate.c |    2 +-
> >  1 files changed, 1 insertions(+), 1 deletions(-)
> >
> > diff --git a/target-arm/translate.c b/target-arm/translate.c
> > index c6840b7..daccb15 100644
> > --- a/target-arm/translate.c
> > +++ b/target-arm/translate.c
> > @@ -516,10 +516,10 @@ static inline void gen_arm_shift_im(TCGv var, int shiftop, int shift, int flags)
> >              tcg_gen_rotri_i32(var, var, shift); break;
> >          } else {
> >              TCGv tmp = tcg_temp_new_i32();
> > +            tcg_gen_shli_i32(tmp, cpu_CF, 31);
> >              if (flags)
> >                  shifter_out_im(var, 0);
> >              tcg_gen_shri_i32(var, var, 1);
> > -            tcg_gen_shli_i32(tmp, cpu_CF, 31);
> >              tcg_gen_or_i32(var, var, tmp);
> >              tcg_temp_free_i32(tmp);
> >          }
> 
> Looks like this was broken by Aurelien's commit 66c374de8; previously
> we loaded CF into a tmp before doing the shifter_out_im() [which updates CF],
> and then used the tmp after the call, rather than directly using CF.

Yes, I am the culprit here, sorry about that.

> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
> 

And applied.