Re: [PATCH 03/17] target/riscv: Use gpr_{src, dst} in shift operations

[Alistair Francis]

On Fri, Jul 9, 2021 at 2:43 PM Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> These operations are slightly more complicated since
> we need to crop the shift operand.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  target/riscv/translate.c | 68 +++++++++++++++-------------------------
>  1 file changed, 26 insertions(+), 42 deletions(-)
>
> diff --git a/target/riscv/translate.c b/target/riscv/translate.c
> index 2cfcb849b8..a60b198623 100644
> --- a/target/riscv/translate.c
> +++ b/target/riscv/translate.c
> @@ -778,18 +778,14 @@ static bool gen_arith(DisasContext *ctx, arg_r *a,
>  static bool gen_shift(DisasContext *ctx, arg_r *a,
>                          void(*func)(TCGv, TCGv, TCGv))
>  {
> -    TCGv source1 = tcg_temp_new();
> -    TCGv source2 = tcg_temp_new();
> +    TCGv dest = gpr_dst(ctx, a->rd);
> +    TCGv src1 = gpr_src(ctx, a->rs1);
> +    TCGv src2 = gpr_src(ctx, a->rs2);
> +    TCGv ext2 = tcg_temp_new();
>
> -    gen_get_gpr(source1, a->rs1);
> -    gen_get_gpr(source2, a->rs2);
> -
> -    tcg_gen_andi_tl(source2, source2, TARGET_LONG_BITS - 1);
> -    (*func)(source1, source1, source2);
> -
> -    gen_set_gpr(a->rd, source1);
> -    tcg_temp_free(source1);
> -    tcg_temp_free(source2);
> +    tcg_gen_andi_tl(ext2, src2, TARGET_LONG_BITS - 1);
> +    (*func)(dest, src1, ext2);
> +    tcg_temp_free(ext2);
>      return true;
>  }
>
> @@ -805,58 +801,46 @@ static uint32_t opcode_at(DisasContextBase *dcbase, 
> target_ulong pc)
>  static bool gen_shifti(DisasContext *ctx, arg_shift *a,
>                         void(*func)(TCGv, TCGv, TCGv))
>  {
> +    TCGv dest, src1, src2;
> +
>      if (a->shamt >= TARGET_LONG_BITS) {
>          return false;
>      }
>
> -    TCGv source1 = tcg_temp_new();
> -    TCGv source2 = tcg_temp_new();
> +    dest = gpr_dst(ctx, a->rd);
> +    src1 = gpr_src(ctx, a->rs1);
> +    src2 = tcg_constant_tl(a->shamt);
>
> -    gen_get_gpr(source1, a->rs1);
> -
> -    tcg_gen_movi_tl(source2, a->shamt);
> -    (*func)(source1, source1, source2);
> -
> -    gen_set_gpr(a->rd, source1);
> -    tcg_temp_free(source1);
> -    tcg_temp_free(source2);
> +    (*func)(dest, src1, src2);
>      return true;
>  }
>
>  static bool gen_shiftw(DisasContext *ctx, arg_r *a,
>                         void(*func)(TCGv, TCGv, TCGv))
>  {
> -    TCGv source1 = tcg_temp_new();
> -    TCGv source2 = tcg_temp_new();
> +    TCGv dest = gpr_dst(ctx, a->rd);
> +    TCGv src1 = gpr_src(ctx, a->rs1);
> +    TCGv src2 = gpr_src(ctx, a->rs2);
> +    TCGv ext2 = tcg_temp_new();
>
> -    gen_get_gpr(source1, a->rs1);
> -    gen_get_gpr(source2, a->rs2);
> +    tcg_gen_andi_tl(ext2, src2, 31);
> +    (*func)(dest, src1, ext2);
> +    tcg_gen_ext32s_tl(dest, dest);
>
> -    tcg_gen_andi_tl(source2, source2, 31);
> -    (*func)(source1, source1, source2);
> -    tcg_gen_ext32s_tl(source1, source1);
> -
> -    gen_set_gpr(a->rd, source1);
> -    tcg_temp_free(source1);
> -    tcg_temp_free(source2);
> +    tcg_temp_free(ext2);
>      return true;
>  }
>
>  static bool gen_shiftiw(DisasContext *ctx, arg_shift *a,
>                          void(*func)(TCGv, TCGv, TCGv))
>  {
> -    TCGv source1 = tcg_temp_new();
> -    TCGv source2 = tcg_temp_new();
> +    TCGv dest = gpr_dst(ctx, a->rd);
> +    TCGv src1 = gpr_src(ctx, a->rs1);
> +    TCGv src2 = tcg_constant_tl(a->shamt);
>
> -    gen_get_gpr(source1, a->rs1);
> -    tcg_gen_movi_tl(source2, a->shamt);
> +    (*func)(dest, src1, src2);
> +    tcg_gen_ext32s_tl(dest, dest);
>
> -    (*func)(source1, source1, source2);
> -    tcg_gen_ext32s_tl(source1, source1);
> -
> -    gen_set_gpr(a->rd, source1);
> -    tcg_temp_free(source1);
> -    tcg_temp_free(source2);
>      return true;
>  }
>
> --
> 2.25.1
>
>