Re: [PATCH] tcg: Reset free_temps before tcg_optimize

[Philippe Mathieu-Daudé]

On 7/12/24 22:47, Richard Henderson wrote:
> When allocating new temps during tcg_optmize, do not re-use
> any EBB temps that were used within the TB.  We do not have
> any idea what span of the TB in which the temp was live.
>
> Cc: qemu-stable@nongnu.org
> Fixes: fb04ab7ddd8 ("tcg/optimize: Lower TCG_COND_TST{EQ,NE} if unsupported")

Hmm, the problem is due to arg_new_temp()?

> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2711
> Reported-by: wannacu <wannacu2049@gmail.com>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>
> Unless there's some other reason to spin an -rc4, this can wait
> to be the first patch for 10.0.1.
>
> r~
>
> ---
>   tcg/tcg.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/tcg/tcg.c b/tcg/tcg.c
> index 0babae1b88..eece825e2e 100644
> --- a/tcg/tcg.c
> +++ b/tcg/tcg.c
> @@ -6120,6 +6120,9 @@ int tcg_gen_code(TCGContext *s, TranslationBlock *tb, 
> uint64_t pc_start)
>       }
>   #endif
>   
> +    /* Do not reuse any EBB that may be allocated within the TB. */
> +    memset(s->free_temps, 0, sizeof(s->free_temps));

Maybe add as tcg_temp_[ebb]_[reset|flush]() helper so we can reuse,
like in tcg_func_start() and plugin_gen_inject()?

>       tcg_optimize(s);
>   
>       reachable_code_pass(s);