Re: [PATCH 1/4] tests/libqtest: Introduce qtest_get_arch_bits()

[Thomas Huth <thuth@redhat.com>]

On 10/10/2023 09.49, Philippe Mathieu-Daudé wrote:
> Add a method to return the architecture bits (currently 8/32/64).
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> ---
>   tests/qtest/libqtest.h |  8 ++++++++
>   tests/qtest/libqtest.c | 21 +++++++++++++++++++++
>   2 files changed, 29 insertions(+)
> 
> diff --git a/tests/qtest/libqtest.h b/tests/qtest/libqtest.h
> index e53e350e3a..1e1b42241d 100644
> --- a/tests/qtest/libqtest.h
> +++ b/tests/qtest/libqtest.h
> @@ -654,6 +654,14 @@ bool qtest_big_endian(QTestState *s);
>    */
>   const char *qtest_get_arch(void);
>   
> +/**
> + * qtest_get_arch_bits:
> + *
> + * Returns: The architecture bits (a.k.a. word size) for the QEMU executable
> + * under test.
> + */
> +unsigned qtest_get_arch_bits(void);
> +
>   /**
>    * qtest_has_accel:
>    * @accel_name: Accelerator name to check for.
> diff --git a/tests/qtest/libqtest.c b/tests/qtest/libqtest.c
> index b1eba71ffe..a643a6309c 100644
> --- a/tests/qtest/libqtest.c
> +++ b/tests/qtest/libqtest.c
> @@ -925,6 +925,27 @@ const char *qtest_get_arch(void)
>       return end + 1;
>   }
>   
> +unsigned qtest_get_arch_bits(void)
> +{
> +    static const char *const arch64[] = {
> +        "aarch64", "hppa", "x86_64", "loongarch64", "mips64",
> +        "mips64el", "ppc64", "riscv64", "s390x", "sparc64",
> +    };
> +    const char *arch = qtest_get_arch();
> +
> +    if (!strcmp(arch, "avr")) {

Just a matter of taste, but I prefer g_str_equal(), that's easier to read.

> +        return 8;
> +    }
> +
> +    for (unsigned i = 0; i < ARRAY_SIZE(arch64); i++) {
> +        if (!strcmp(arch, arch64[i])) {
> +            return 64;
> +        }
> +    }
> +
> +    return 32;
> +}

Since this function might get called multiple times, would it make sense to 
cache the value? I.e.:

   static const unsigned bits;

   if (!bits) {
       ... do all the magic to find out the right bits ...
   }

   return bits;

?

  Thomas