Re: [Qemu-devel] [PATCH v2 36/45] tcg: dynamically allocate optimizer globals + fold into TCGContext

[Richard Henderson]

On 07/16/2017 10:04 AM, Emilio G. Cota wrote:
> Groundwork for supporting multiple TCG contexts.
>
> Signed-off-by: Emilio G. Cota <address@hidden>
> ---
>   tcg/tcg.h      | 12 ++++++++++++
>   tcg/optimize.c | 40 +++++++++++++++++++++++-----------------
>   2 files changed, 35 insertions(+), 17 deletions(-)
>
> diff --git a/tcg/tcg.h b/tcg/tcg.h
> index 569f823..175d4de 100644
> --- a/tcg/tcg.h
> +++ b/tcg/tcg.h
> @@ -641,6 +641,14 @@ QEMU_BUILD_BUG_ON(OPPARAM_BUF_SIZE > (1 << 14));
>   /* Make sure that we don't overflow 64 bits without noticing.  */
>   QEMU_BUILD_BUG_ON(sizeof(TCGOp) > 8);
>   
> +struct tcg_temp_info {
> +    bool is_const;
> +    uint16_t prev_copy;
> +    uint16_t next_copy;
> +    tcg_target_ulong val;
> +    tcg_target_ulong mask;
> +};
> +
>   struct TCGContext {
>       uint8_t *pool_cur, *pool_end;
>       TCGPool *pool_first, *pool_current, *pool_first_large;
> @@ -717,6 +725,10 @@ struct TCGContext {
>       TCGTempSet free_temps[TCG_TYPE_COUNT * 2];
>       TCGTemp temps[TCG_MAX_TEMPS]; /* globals first, temps after */
>   
> +    /* optimizer */
> +    struct tcg_temp_info *opt_temps;
> +    TCGTempSet opt_temps_used;

I would prefer either

  (1) Dynamic allocation.  I know we eschew that most places during,
      but surely this is the exact situation for which it's handy.

  (2) Make opt_temps an array of TCG_MAX_TEMPS and drop the pointer.

I think the TCGTempSet should be a local within tcg_optimize.


r~