Re: [Qemu-devel] [PATCH v14 24/33] target-tilegx: Handle shift instructions

[Peter Maydell]

On 24 August 2015 at 17:17, Richard Henderson <address@hidden> wrote:
> Signed-off-by: Richard Henderson <address@hidden>
> ---
>  target-tilegx/translate.c | 57 
> +++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 55 insertions(+), 2 deletions(-)
>
> diff --git a/target-tilegx/translate.c b/target-tilegx/translate.c
> index 6be751b..4e6d577 100644
> --- a/target-tilegx/translate.c
> +++ b/target-tilegx/translate.c
> @@ -474,6 +474,7 @@ static TileExcp gen_rrr_opcode(DisasContext *dc, unsigned 
> opext,
>      TCGv tdest = dest_gr(dc, dest);
>      TCGv tsrca = load_gr(dc, srca);
>      TCGv tsrcb = load_gr(dc, srcb);
> +    TCGv t0;

Personally I would restrict the scope of this to just the
case block where it's used.

>      case OE_RRR(SHRUX, 0, X0):
>      case OE_RRR(SHRUX, 0, X1):
> +        t0 = tcg_temp_new();
> +        tcg_gen_andi_tl(t0, tsrcb, 31);
> +        tcg_gen_ext32u_tl(tdest, tsrca);
> +        tcg_gen_shl_tl(tdest, tdest, t0);
> +        tcg_gen_ext32s_tl(tdest, tdest);
> +        tcg_temp_free(t0);
> +        mnemonic = "shrux";
> +        break;

Using shl for a shift right doesn't look right...

>      case OE_SH(SHRUI, X0):
>      case OE_SH(SHRUI, X1):
>      case OE_SH(SHRUI, Y0):
>      case OE_SH(SHRUI, Y1):
> +        tcg_gen_shri_tl(tdest, tsrca, imm);
> +        mnemonic = "shrui";
> +        break;
>      case OE_SH(SHRUXI, X0):
>      case OE_SH(SHRUXI, X1):
> +        if ((imm & 31) == 0) {
> +            tcg_gen_ext32s_tl(tdest, tsrca);
> +        } else {
> +            tcg_gen_ext32u_tl(tdest, tsrca);
> +            tcg_gen_shli_tl(tdest, tdest, imm & 31);

Shift left used when shift right intended ?

> +        }
> +        mnemonic = "shlxi";
> +        break;
>      case OE_SH(V1SHLI, X0):
>      case OE_SH(V1SHLI, X1):
>      case OE_SH(V1SHRSI, X0):
> @@ -1096,6 +1148,7 @@ static TileExcp gen_rri_opcode(DisasContext *dc, 
> unsigned opext,
>      case OE_SH(V2SHRSI, X1):
>      case OE_SH(V2SHRUI, X0):
>      case OE_SH(V2SHRUI, X1):
> +        return TILEGX_EXCP_OPCODE_UNIMPLEMENTED;

Why does this change appear in this patch?

>
>      case OE(ADDLI_OPCODE_X0, 0, X0):
>      case OE(ADDLI_OPCODE_X1, 0, X1):
> --
> 2.4.3
>

thanks
-- PMM