Re: [PATCH v3 06/28] tcg: Split out tcg_region_prologue_set

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

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

> This has only one user, but will make more sense after some
> code motion.
>
> Always leave the tcg_init_ctx initialized to the first region,
> in preparation for tcg_prologue_init().  This also requires
> that we don't re-allocate the region for the first cpu, lest
> we hit the assertion for total number of regions allocated .
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

> ---
>  tcg/tcg.c | 37 ++++++++++++++++++++++---------------
>  1 file changed, 22 insertions(+), 15 deletions(-)
>
> diff --git a/tcg/tcg.c b/tcg/tcg.c
> index df78c89673..ee3319e163 100644
> --- a/tcg/tcg.c
> +++ b/tcg/tcg.c
> @@ -885,10 +885,26 @@ void tcg_region_init(void)
>  
>      tcg_region_trees_init();
>  
> -    /* In user-mode we support only one ctx, so do the initial allocation now */
> -#ifdef CONFIG_USER_ONLY
> -    tcg_region_initial_alloc__locked(tcg_ctx);
> -#endif
> +    /*
> +     * Leave the initial context initialized to the first region.
> +     * This will be the context into which we generate the prologue.
> +     * It is also the only context for CONFIG_USER_ONLY.
> +     */
> +    tcg_region_initial_alloc__locked(&tcg_init_ctx);
> +}
> +
> +static void tcg_region_prologue_set(TCGContext *s)
> +{
> +    /* Deduct the prologue from the first region.  */
> +    g_assert(region.start == s->code_gen_buffer);
> +    region.start = s->code_ptr;
> +
> +    /* Recompute boundaries of the first region. */
> +    tcg_region_assign(s, 0);
> +
> +    /* Register the balance of the buffer with gdb. */
> +    tcg_register_jit(tcg_splitwx_to_rx(region.start),
> +                     region.end - region.start);
>  }
>  
>  #ifdef CONFIG_DEBUG_TCG
> @@ -968,10 +984,10 @@ void tcg_register_thread(void)
>  
>      if (n > 0) {
>          alloc_tcg_plugin_context(s);
> +        tcg_region_initial_alloc(s);
>      }
>  
>      tcg_ctx = s;
> -    tcg_region_initial_alloc(s);
>  }
>  #endif /* !CONFIG_USER_ONLY */
>  
> @@ -1211,8 +1227,6 @@ void tcg_prologue_init(TCGContext *s)
>  {
>      size_t prologue_size;
>  
> -    /* Put the prologue at the beginning of code_gen_buffer.  */
> -    tcg_region_assign(s, 0);
>      s->code_ptr = s->code_gen_ptr;
>      s->code_buf = s->code_gen_ptr;
>      s->data_gen_ptr = NULL;
> @@ -1244,14 +1258,7 @@ void tcg_prologue_init(TCGContext *s)
>                          (uintptr_t)s->code_buf, prologue_size);
>  #endif
>  
> -    /* Deduct the prologue from the first region.  */
> -    region.start = s->code_ptr;
> -
> -    /* Recompute boundaries of the first region. */
> -    tcg_region_assign(s, 0);
> -
> -    tcg_register_jit(tcg_splitwx_to_rx(region.start),
> -                     region.end - region.start);
> +    tcg_region_prologue_set(s);
>  
>  #ifdef DEBUG_DISAS
>      if (qemu_loglevel_mask(CPU_LOG_TB_OUT_ASM)) {


-- 
Alex Bennée