Re: [PATCH 26/33] target/mips: Convert MSA ELM instruction format to decodetree

[Richard Henderson]

On 10/23/21 2:47 PM, Philippe Mathieu-Daudé wrote:
> +static bool trans_msa_elm_df(DisasContext *ctx, arg_msa_elm *a,
> +                             void (*gen_msa_elm_df)(TCGv_ptr, TCGv_i32,
> +                                                    TCGv_i32, TCGv_i32,
> +                                                    TCGv_i32))
> +{
> +    TCGv_i32 twd;
> +    TCGv_i32 tws;
> +    TCGv_i32 tdf;
> +    TCGv_i32 tn;
> +    uint32_t df, n;
> +
> +    if (!df_extract(df_elm, a->df, &df, &n)) {
> +        gen_reserved_instruction(ctx);
> +        return true;
> +    }

Again, I think this should happen before the access check.

You could even return false from these extractions, because they represent an invalid 
encoding for this instruction.  In a different context, there could be another grouped 
insn that matches.


> +    twd = tcg_const_i32(a->wd);
> +    tws = tcg_const_i32(a->ws);

tcg_constant_i32.

r~