Re: [Qemu-devel] [PATCH v14 14/33] target-tilegx: Handle simple logical operations

[Richard Henderson]

On 08/29/2015 07:58 AM, Peter Maydell wrote:
> On 24 August 2015 at 17:17, Richard Henderson <address@hidden> wrote:
> > Signed-off-by: Richard Henderson <address@hidden>
> > ---
> >   target-tilegx/translate.c | 99 +++++++++++++++++++++++++++++++++++++++++++++--
> >   1 file changed, 96 insertions(+), 3 deletions(-)
> >
> > diff --git a/target-tilegx/translate.c b/target-tilegx/translate.c
> > index a2d597d..066d351 100644
> > --- a/target-tilegx/translate.c
> > +++ b/target-tilegx/translate.c
> > @@ -106,9 +106,64 @@ static void gen_exception(DisasContext *dc, TileExcp num)
> >       dc->exit_tb = true;
> >   }
> >
> > +static bool check_gr(DisasContext *dc, uint8_t reg)
> > +{
> > +    if (likely(reg < TILEGX_R_COUNT)) {
> > +        return true;
> > +    }
> > +
> > +    switch (reg) {
> > +    case TILEGX_R_SN:
> > +    case TILEGX_R_ZERO:
> > +        break;
> > +    case TILEGX_R_IDN0:
> > +    case TILEGX_R_IDN1:
> > +        gen_exception(dc, TILEGX_EXCP_REG_IDN_ACCESS);
> > +        break;
> > +    case TILEGX_R_UDN0:
> > +    case TILEGX_R_UDN1:
> > +    case TILEGX_R_UDN2:
> > +    case TILEGX_R_UDN3:
> > +        gen_exception(dc, TILEGX_EXCP_REG_UDN_ACCESS);
>
> Why does this function generate an exception immediately
> rather than returning a TILEGX_EXCP_* code the way the
> decode framework seems to be set up to work?

So that we can simply return a TCGv from the load_gr and dest_gr functions, and 
their users don't have to check for an error code.

r~