Re: [Qemu-devel] [PATCH v3 2/5] target-ppc: improve lxvw4x implementation

[David Gibson]

On Fri, Sep 16, 2016 at 04:21:48PM +0530, Nikunj A Dadhania wrote:
> Load 8byte at a time and manipulate.
> 
> Signed-off-by: Nikunj A Dadhania <address@hidden>
> ---
>  target-ppc/helper.h                 |  1 +
>  target-ppc/mem_helper.c             |  5 +++++
>  target-ppc/translate/vsx-impl.inc.c | 19 +++++--------------
>  3 files changed, 11 insertions(+), 14 deletions(-)
> 
> diff --git a/target-ppc/helper.h b/target-ppc/helper.h
> index 966f2ce..9f6705d 100644
> --- a/target-ppc/helper.h
> +++ b/target-ppc/helper.h
> @@ -297,6 +297,7 @@ DEF_HELPER_2(mtvscr, void, env, avr)
>  DEF_HELPER_3(lvebx, void, env, avr, tl)
>  DEF_HELPER_3(lvehx, void, env, avr, tl)
>  DEF_HELPER_3(lvewx, void, env, avr, tl)
> +DEF_HELPER_1(deposit32x2, i64, i64)
>  DEF_HELPER_3(stvebx, void, env, avr, tl)
>  DEF_HELPER_3(stvehx, void, env, avr, tl)
>  DEF_HELPER_3(stvewx, void, env, avr, tl)
> diff --git a/target-ppc/mem_helper.c b/target-ppc/mem_helper.c
> index 6548715..86e493e 100644
> --- a/target-ppc/mem_helper.c
> +++ b/target-ppc/mem_helper.c
> @@ -285,6 +285,11 @@ STVE(stvewx, cpu_stl_data_ra, bswap32, u32)
>  #undef I
>  #undef LVE
>  
> +uint64_t helper_deposit32x2(uint64_t x)
> +{
> +    return deposit64((x >> 32), 32, 32, (x));
> +}

It seems a shame to drop out to a helper for something this simple.
How hard would it be to implement this.. wordswap, I guess you'd call
it.. in tcg ops?

I'm also not particularly fond of the deposit32x2 name, though a
better one doesn't quickly come to mind.

> +
>  #undef HI_IDX
>  #undef LO_IDX
>  
> diff --git a/target-ppc/translate/vsx-impl.inc.c 
> b/target-ppc/translate/vsx-impl.inc.c
> index eee6052..df278df 100644
> --- a/target-ppc/translate/vsx-impl.inc.c
> +++ b/target-ppc/translate/vsx-impl.inc.c
> @@ -75,7 +75,6 @@ static void gen_lxvdsx(DisasContext *ctx)
>  static void gen_lxvw4x(DisasContext *ctx)
>  {
>      TCGv EA;
> -    TCGv_i64 tmp;
>      TCGv_i64 xth = cpu_vsrh(xT(ctx->opcode));
>      TCGv_i64 xtl = cpu_vsrl(xT(ctx->opcode));
>      if (unlikely(!ctx->vsx_enabled)) {
> @@ -84,22 +83,14 @@ static void gen_lxvw4x(DisasContext *ctx)
>      }
>      gen_set_access_type(ctx, ACCESS_INT);
>      EA = tcg_temp_new();
> -    tmp = tcg_temp_new_i64();
>  
>      gen_addr_reg_index(ctx, EA);
> -    gen_qemu_ld32u_i64(ctx, tmp, EA);
> -    tcg_gen_addi_tl(EA, EA, 4);
> -    gen_qemu_ld32u_i64(ctx, xth, EA);
> -    tcg_gen_deposit_i64(xth, xth, tmp, 32, 32);
> -
> -    tcg_gen_addi_tl(EA, EA, 4);
> -    gen_qemu_ld32u_i64(ctx, tmp, EA);
> -    tcg_gen_addi_tl(EA, EA, 4);
> -    gen_qemu_ld32u_i64(ctx, xtl, EA);
> -    tcg_gen_deposit_i64(xtl, xtl, tmp, 32, 32);
> -
> +    tcg_gen_qemu_ld_i64(xth, EA, ctx->mem_idx, MO_LEQ);
> +    gen_helper_deposit32x2(xth, xth);
> +    tcg_gen_addi_tl(EA, EA, 8);
> +    tcg_gen_qemu_ld_i64(xtl, EA, ctx->mem_idx, MO_LEQ);
> +    gen_helper_deposit32x2(xtl, xtl);
>      tcg_temp_free(EA);
> -    tcg_temp_free_i64(tmp);
>  }
>  
>  #define VSX_STORE_SCALAR(name, operation)                     \

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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