Re: [PATCH v2] target/hppa: Speed up hppa_is_pa20()

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 28/12/24 22:08, Helge Deller wrote:
> Although the hppa_is_pa20() helper is costly due to string comparisms in

"comparisms" -> "comparison"?

> object_dynamic_cast(), it is called quite often during memory lookups
> and at each start of a block of instruction translations.
> Speed hppa_is_pa20() up by calling object_dynamic_cast() only once at
> CPU creation and store the result in the is_pa20 of struct CPUArchState.
> 
> Signed-off-by: Helge Deller <deller@gmx.de>
> 
> v2:
> - moved init to hppa_cpu_initfn() and is_pa20 to end of CPUArchState struct
>    (feedback by Richard)
> 
> diff --git a/target/hppa/cpu.c b/target/hppa/cpu.c
> index b908cf65c6..05de952a87 100644
> --- a/target/hppa/cpu.c
> +++ b/target/hppa/cpu.c
> @@ -199,6 +199,7 @@ static void hppa_cpu_initfn(Object *obj)
>       CPUHPPAState *env = &cpu->env;
>   
>       cs->exception_index = -1;
> +    env->is_pa20 = object_dynamic_cast(obj, TYPE_HPPA64_CPU);

Personally I find explicit casts to boolean clearer:

        env->is_pa20 = !!object_dynamic_cast(obj, TYPE_HPPA64_CPU);

>       cpu_hppa_loaded_fr0(env);
>       cpu_hppa_put_psw(env, PSW_W);
>   }

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>