On 24/07/2015 18:30, Aurelien Jarno wrote:
> The tcg_temp_info structure uses 24 bytes per temp. Now that we emulate
> vector registers on most guests, it's not uncommon to have more than 100
> used temps. This means we have initialize more than 2kB at least twice
> per TB, often more when there is a few goto_tb.
>
> Instead used a TCGTempSet bit array to track which temps are in used in
> the current basic block. This means there are only around 16 bytes to
> initialize.
>
> This improves the boot time of a MIPS guest on an x86-64 host by around
> 7% and moves out tcg_optimize from the the top of the profiler list.
>
> Cc: Richard Henderson <r...@twiddle.net>
> Signed-off-by: Aurelien Jarno <aurel...@aurel32.net>
> ---
> tcg/optimize.c | 32 ++++++++++++++++++++++----------
> 1 file changed, 22 insertions(+), 10 deletions(-)
>
> diff --git a/tcg/optimize.c b/tcg/optimize.c
> index cd0e793..20e24b3 100644
> --- a/tcg/optimize.c
> +++ b/tcg/optimize.c
> @@ -50,6 +50,7 @@ struct tcg_temp_info {
> };
>
> static struct tcg_temp_info temps[TCG_MAX_TEMPS];
> +static TCGTempSet temps_used;
>
> /* Reset TEMP's state to TCG_TEMP_UNDEF. If TEMP only had one copy, remove
> the copy flag from the left temp. */
> @@ -67,6 +68,22 @@ static void reset_temp(TCGArg temp)
> temps[temp].mask = -1;
> }
>
> +/* Reset all temporaries, given that there are NB_TEMPS of them. */
> +static void reset_all_temps(int nb_temps)
> +{
> + memset(&temps_used.l, 0, sizeof(long) * BITS_TO_LONGS(nb_temps));
You can use bitmap_zero here.
Paolo
> +}
> +
> +/* Initialize and activate a temporary. */
> +static void init_temp_info(TCGArg temp)
> +{
> + if (!test_bit(temp, temps_used.l)) {
> + temps[temp].state = TCG_TEMP_UNDEF;
> + temps[temp].mask = -1;
> + set_bit(temp, temps_used.l);
> + }
> +}
> +
> static TCGOp *insert_op_before(TCGContext *s, TCGOp *old_op,
> TCGOpcode opc, int nargs)
> {
> @@ -98,16 +115,6 @@ static TCGOp *insert_op_before(TCGContext *s, TCGOp
> *old_op,
> return new_op;
> }
>
> -/* Reset all temporaries, given that there are NB_TEMPS of them. */
> -static void reset_all_temps(int nb_temps)
> -{
> - int i;
> - for (i = 0; i < nb_temps; i++) {
> - temps[i].state = TCG_TEMP_UNDEF;
> - temps[i].mask = -1;
> - }
> -}
> -
> static int op_bits(TCGOpcode op)
> {
> const TCGOpDef *def = &tcg_op_defs[op];
> @@ -606,6 +613,11 @@ void tcg_optimize(TCGContext *s)
> nb_iargs = def->nb_iargs;
> }
>
> + /* Initialize the temps that are going to be used */
> + for (i = 0; i < nb_oargs + nb_iargs; i++) {
> + init_temp_info(args[i]);
> + }
> +
> /* Do copy propagation */
> for (i = nb_oargs; i < nb_oargs + nb_iargs; i++) {
> if (temps[args[i]].state == TCG_TEMP_COPY) {
>
