Re: [Qemu-devel] [PATCH v2 08/10] target-arm: optimize thumb push/pop ops

[Laurent Desnogues <laurent.desnogues@gmail.com>]

On Sat, Oct 24, 2009 at 2:19 PM,  <juha.riihimaki@nokia.com> wrote:
> From: Juha Riihimäki <juha.riihimaki@nokia.com>
>
> Thumb push/pop instructions can be slightly optimized by loading the
> register offset constant into a variable outside the register loop and
> using the preloaded variable inside the loop instead of reloading the
> offset value to a temporary variable on each loop iteration. This
> causes less TCG ops to be generated for a Thumb push/pop instruction
> if there are more than one register accessed, otherwise the amount of
> generated TCG ops is the same.
>
> Signed-off-by: Juha Riihimäki <juha.riihimaki@nokia.com>

Acked-by: Laurent Desnogues <laurent.desnogues@gmail.com>


Laurent

> ---
>  target-arm/translate.c |    6 ++++--
>  1 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/target-arm/translate.c b/target-arm/translate.c
> index 353f638..f262758 100644
> --- a/target-arm/translate.c
> +++ b/target-arm/translate.c
> @@ -8596,6 +8596,7 @@ static void disas_thumb_insn(CPUState *env, DisasContext *s)
>             if ((insn & (1 << 11)) == 0) {
>                 tcg_gen_addi_i32(addr, addr, -offset);
>             }
> +            tmp2 = tcg_const_i32(4);
>             for (i = 0; i < 8; i++) {
>                 if (insn & (1 << i)) {
>                     if (insn & (1 << 11)) {
> @@ -8608,7 +8609,7 @@ static void disas_thumb_insn(CPUState *env, DisasContext *s)
>                         gen_st32(tmp, addr, IS_USER(s));
>                     }
>                     /* advance to the next address.  */
> -                    tcg_gen_addi_i32(addr, addr, 4);
> +                    tcg_gen_add_i32(addr, addr, tmp2);
>                 }
>             }
>             TCGV_UNUSED(tmp);
> @@ -8623,8 +8624,9 @@ static void disas_thumb_insn(CPUState *env, DisasContext *s)
>                     tmp = load_reg(s, 14);
>                     gen_st32(tmp, addr, IS_USER(s));
>                 }
> -                tcg_gen_addi_i32(addr, addr, 4);
> +                tcg_gen_add_i32(addr, addr, tmp2);
>             }
> +            tcg_temp_free_i32(tmp2);
>             if ((insn & (1 << 11)) == 0) {
>                 tcg_gen_addi_i32(addr, addr, -offset);
>             }
> --
> 1.6.5
>
>
>
>