[FFmpeg-devel] [PATCH] checkasm: Test whether direct cycle counter access works

[Rémi Denis-Courmont]

Le torstaina 11. tammikuuta 2024, 14.53.05 EET Martin Storsjö a écrit :
> This should print a nicer error message than crashing due to
> an illegal instruction, if direct cycle counter access isn't
> allowed.
> 
> This matches the dav1d checkasm commit
> 95a192549a448b70d9542e840c4e34b60d09b093.
> ---
>  tests/checkasm/checkasm.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/tests/checkasm/checkasm.c b/tests/checkasm/checkasm.c
> index 994d64e96b..9c5abb53dc 100644
> --- a/tests/checkasm/checkasm.c
> +++ b/tests/checkasm/checkasm.c
> @@ -754,6 +754,14 @@ static int bench_init_kperf(void)
>  static int bench_init_ffmpeg(void)
>  {
>  #ifdef AV_READ_TIME
> +    if (!checkasm_save_context()) {
> +        checkasm_set_signal_handler_state(1);
> +        AV_READ_TIME();
> +        checkasm_set_signal_handler_state(0);
> +    } else {
> +        fprintf(stderr, "checkasm: unable to access cycle counter\n");

AV_READ_TIME() reads time, not cycles. If we want cycle count, then we should 
add a separate macro, as the two are different performance counters at least on 
RISC-V. As things stand, this code won't do anything on RISC-V, sinec 
AV_READ_TIME() actually reads, well, time, not cycles.

> +        return -1;
> +    }
>      printf("benchmarking with native FFmpeg timers\n");
>      return 0;
>  #else
> @@ -927,7 +935,9 @@ int checkasm_bench_func(void)
>  /* Indicate that the current test has failed */
>  void checkasm_fail_func(const char *msg, ...)
>  {
> -    if (state.current_func_ver->cpu && state.current_func_ver->ok) {
> +    if (state.current_func_ver && state.current_func_ver->cpu &&
> +        state.current_func_ver->ok)
> +    {
>          va_list arg;
> 
>          print_cpu_name();


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