Re: [Qemu-devel] [PATCH] TCG: fix copy propagation

[Stefan Weil <weil@mail.berlios.de>]

Am 06.08.2011 23:26, schrieb Blue Swirl:
> Copy propagation introduced in 22613af4a6d9602001e6d0e7b6d98aa40aa018dc
> considered only global registers. However, register temps and stack
> allocated locals must be handled differently because register temps
> don't survive across brcond.
>
> Fix by propagating only within same class of temps.
>
> Signed-off-by: Blue Swirl<blauwirbel@gmail.com>
> ---
>   tcg/optimize.c |   15 +++++++++------
>   tcg/tcg.h      |    5 +++++
>   2 files changed, 14 insertions(+), 6 deletions(-)
>
> diff --git a/tcg/optimize.c b/tcg/optimize.c
> index a3bfa5e..7eb5eb1 100644
> --- a/tcg/optimize.c
> +++ b/tcg/optimize.c
> @@ -185,12 +185,15 @@ static int op_to_movi(int op)
>       }
>   }
>
> -static void tcg_opt_gen_mov(TCGArg *gen_args, TCGArg dst, TCGArg src,
> -                            int nb_temps, int nb_globals)
> +static void tcg_opt_gen_mov(TCGContext *s, TCGArg *gen_args, TCGArg dst,
> +                            TCGArg src, int nb_temps, int nb_globals)
>   {
>           reset_temp(dst, nb_temps, nb_globals);
>           assert(temps[src].state != TCG_TEMP_COPY);
> -        if (src>= nb_globals) {
> +        /* Don't try to copy if one of temps is a global or either one
> +           is local and another is register */
> +        if (src>= nb_globals&&  dst>= nb_globals&&
> +            tcg_arg_is_local(s, src) == tcg_arg_is_local(s, dst)) {
>               assert(temps[src].state != TCG_TEMP_CONST);
>               if (temps[src].state != TCG_TEMP_HAS_COPY) {
>                   temps[src].state = TCG_TEMP_HAS_COPY;
> @@ -474,7 +477,7 @@ static TCGArg *tcg_constant_folding(TCGContext *s,
> uint16_t *tcg_opc_ptr,
>                       gen_opc_buf[op_index] = INDEX_op_nop;
>                   } else {
>                       gen_opc_buf[op_index] = op_to_mov(op);
> -                    tcg_opt_gen_mov(gen_args, args[0], args[1],
> +                    tcg_opt_gen_mov(s, gen_args, args[0], args[1],
>                                       nb_temps, nb_globals);
>                       gen_args += 2;
>                       args += 3;
> @@ -500,7 +503,7 @@ static TCGArg *tcg_constant_folding(TCGContext *s,
> uint16_t *tcg_opc_ptr,
>                       gen_opc_buf[op_index] = INDEX_op_nop;
>                   } else {
>                       gen_opc_buf[op_index] = op_to_mov(op);
> -                    tcg_opt_gen_mov(gen_args, args[0], args[1], nb_temps,
> +                    tcg_opt_gen_mov(s, gen_args, args[0], args[1], nb_temps,
>                                       nb_globals);
>                       gen_args += 2;
>                       args += 3;
> @@ -523,7 +526,7 @@ static TCGArg *tcg_constant_folding(TCGContext *s,
> uint16_t *tcg_opc_ptr,
>                   break;
>               }
>               if (temps[args[1]].state != TCG_TEMP_CONST) {
> -                tcg_opt_gen_mov(gen_args, args[0], args[1],
> +                tcg_opt_gen_mov(s, gen_args, args[0], args[1],
>                                   nb_temps, nb_globals);
>                   gen_args += 2;
>                   args += 2;
> diff --git a/tcg/tcg.h b/tcg/tcg.h
> index e76f9af..e2a7095 100644
> --- a/tcg/tcg.h
> +++ b/tcg/tcg.h
> @@ -410,6 +410,11 @@ static inline TCGv_i64 tcg_temp_local_new_i64(void)
>   void tcg_temp_free_i64(TCGv_i64 arg);
>   char *tcg_get_arg_str_i64(TCGContext *s, char *buf, int buf_size,
> TCGv_i64 arg);
>
> +static inline bool tcg_arg_is_local(TCGContext *s, TCGArg arg)
> +{
> +    return s->temps[arg].temp_local;
> +}
> +
>   #if defined(CONFIG_DEBUG_TCG)
>   /* If you call tcg_clear_temp_count() at the start of a section of
>    * code which is not supposed to leak any TCG temporaries, then

This fixes qemu-system-x86_64 and qemu-system-mips64(el) on 32 bit hosts.

Tested-by: Stefan Weil <weil@mail.berlios.de>