Re: [PATCH 05/33] target/mips: Have check_msa_access() return a boolean

[Richard Henderson]

On 10/23/21 2:47 PM, Philippe Mathieu-Daudé wrote:
> Have check_msa_access() return a boolean value so we can
> return early if MSA is not enabled.
>
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> ---
>   target/mips/tcg/msa_translate.c | 20 +++++++++++++-------
>   1 file changed, 13 insertions(+), 7 deletions(-)
>
> diff --git a/target/mips/tcg/msa_translate.c b/target/mips/tcg/msa_translate.c
> index 3ef912da6b8..9e0a08fe335 100644
> --- a/target/mips/tcg/msa_translate.c
> +++ b/target/mips/tcg/msa_translate.c
> @@ -293,19 +293,19 @@ void msa_translate_init(void)
>       }
>   }
>   
> -static inline int check_msa_access(DisasContext *ctx)
> +static inline bool check_msa_access(DisasContext *ctx)
>   {
>       if (unlikely((ctx->hflags & MIPS_HFLAG_FPU) &&
>                    !(ctx->hflags & MIPS_HFLAG_F64))) {
>           gen_reserved_instruction(ctx);
> -        return 0;
> +        return false;
>       }
>   
>       if (unlikely(!(ctx->hflags & MIPS_HFLAG_MSA))) {
>           generate_exception_end(ctx, EXCP_MSADIS);
> -        return 0;
> +        return false;
>       }

When we return false, we have raised an exception.

> @@ -354,7 +354,9 @@ static bool gen_msa_BxZ_V(DisasContext *ctx, int wt, int 
> s16, TCGCond cond)
>   {
>       TCGv_i64 t0;
>   
> -    check_msa_access(ctx);
> +    if (!check_msa_access(ctx)) {
> +        return false;
> +    }

... which means that here we should return true, meaning that we have recognized the 
instruction and emitted some code for it.  In this case: we have recognized that the 
instruction is valid but not enabled.

Otherwise, we will return to decode_opc and (eventually) emit another 
gen_reserved_instruction.


r~