Re: [PATCH v2 05/10] accel/tcg: Handle -singlestep in curr_cflags

["Alex Bennée" <alex.bennee@linaro.org>]

Richard Henderson <richard.henderson@linaro.org> writes:

> Exchange the test in translator_use_goto_tb for CF_NO_GOTO_TB,
> and the test in tb_gen_code for setting CF_COUNT_MASK to 1.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  accel/tcg/cpu-exec.c      | 8 +++++++-
>  accel/tcg/translate-all.c | 2 +-
>  accel/tcg/translator.c    | 2 +-
>  3 files changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c
> index 70ea3c7d68..2206c463f5 100644
> --- a/accel/tcg/cpu-exec.c
> +++ b/accel/tcg/cpu-exec.c
> @@ -149,7 +149,13 @@ uint32_t curr_cflags(CPUState *cpu)
>  {
>      uint32_t cflags = cpu->tcg_cflags;
>  
> -    if (qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) {
> +    /*
> +     * For singlestep and -d nochain, suppress goto_tb so that
> +     * we can log -d cpu,exec after every TB.
> +     */
> +    if (singlestep) {

Hmm we are testing a magic global here and looking at
cpu->singlestep_enabled lower down. We have a transient singlestep which
is turned on an off via cpu->singlestep_enabled and a global as a debug
option. Can we rationalise it further?

> +        cflags |= CF_NO_GOTO_TB | 1;
> +    } else if (qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) {
>          cflags |= CF_NO_GOTO_TB;
>      }
>  
> diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
> index 997e44c73b..491c1a56b2 100644
> --- a/accel/tcg/translate-all.c
> +++ b/accel/tcg/translate-all.c
> @@ -1432,7 +1432,7 @@ TranslationBlock *tb_gen_code(CPUState *cpu,
>      }
>      QEMU_BUILD_BUG_ON(CF_COUNT_MASK + 1 != TCG_MAX_INSNS);
>  
> -    if (cpu->singlestep_enabled || singlestep) {
> +    if (cpu->singlestep_enabled) {
>          max_insns = 1;
>      }
>  
> diff --git a/accel/tcg/translator.c b/accel/tcg/translator.c
> index 2ea5a74f30..a59eb7c11b 100644
> --- a/accel/tcg/translator.c
> +++ b/accel/tcg/translator.c
> @@ -39,7 +39,7 @@ bool translator_use_goto_tb(DisasContextBase *db, target_ulong dest)
>      }
>  
>      /* Suppress goto_tb in the case of single-steping.  */
> -    if (db->singlestep_enabled || singlestep) {
> +    if (db->singlestep_enabled) {
>          return false;
>      }


-- 
Alex Bennée