Re: [PATCH 3/3] target/arm: Use clear_vec_high more effectively

["Alex Bennée" <alex.bennee@linaro.org>]

Richard Henderson <richard.henderson@linaro.org> writes:

> Do not explicitly store zero to the NEON high part
> when we can pass !is_q to clear_vec_high.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

> ---
>  target/arm/translate-a64.c | 59 +++++++++++++++++++++++---------------
>  1 file changed, 36 insertions(+), 23 deletions(-)
>
> diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
> index d57aa54d6a..bf82a2e115 100644
> --- a/target/arm/translate-a64.c
> +++ b/target/arm/translate-a64.c
> @@ -948,11 +948,10 @@ static void do_fp_ld(DisasContext *s, int destidx, TCGv_i64 tcg_addr, int size)
>  {
>      /* This always zero-extends and writes to a full 128 bit wide vector */
>      TCGv_i64 tmplo = tcg_temp_new_i64();
> -    TCGv_i64 tmphi;
> +    TCGv_i64 tmphi = NULL;
>  
>      if (size < 4) {
>          MemOp memop = s->be_data + size;
> -        tmphi = tcg_const_i64(0);
>          tcg_gen_qemu_ld_i64(tmplo, tcg_addr, get_mem_index(s), memop);
>      } else {
>          bool be = s->be_data == MO_BE;
> @@ -970,12 +969,13 @@ static void do_fp_ld(DisasContext *s, int destidx, TCGv_i64 tcg_addr, int size)
>      }
>  
>      tcg_gen_st_i64(tmplo, cpu_env, fp_reg_offset(s, destidx, MO_64));
> -    tcg_gen_st_i64(tmphi, cpu_env, fp_reg_hi_offset(s, destidx));
> -
>      tcg_temp_free_i64(tmplo);
> -    tcg_temp_free_i64(tmphi);
>  
> -    clear_vec_high(s, true, destidx);
> +    if (tmphi) {
> +        tcg_gen_st_i64(tmphi, cpu_env, fp_reg_hi_offset(s, destidx));
> +        tcg_temp_free_i64(tmphi);
> +    }
> +    clear_vec_high(s, tmphi != NULL, destidx);
>  }
>  
>  /*
> @@ -6969,8 +6969,8 @@ static void disas_simd_ext(DisasContext *s, uint32_t insn)
>          return;
>      }
>  
> -    tcg_resh = tcg_temp_new_i64();
>      tcg_resl = tcg_temp_new_i64();
> +    tcg_resh = NULL;
>  
>      /* Vd gets bits starting at pos bits into Vm:Vn. This is
>       * either extracting 128 bits from a 128:128 concatenation, or
> @@ -6982,7 +6982,6 @@ static void disas_simd_ext(DisasContext *s, uint32_t insn)
>              read_vec_element(s, tcg_resh, rm, 0, MO_64);
>              do_ext64(s, tcg_resh, tcg_resl, pos);
>          }
> -        tcg_gen_movi_i64(tcg_resh, 0);
>      } else {
>          TCGv_i64 tcg_hh;
>          typedef struct {
> @@ -6997,6 +6996,7 @@ static void disas_simd_ext(DisasContext *s, uint32_t insn)
>              pos -= 64;
>          }
>  
> +        tcg_resh = tcg_temp_new_i64();
>          read_vec_element(s, tcg_resl, elt->reg, elt->elt, MO_64);
>          elt++;
>          read_vec_element(s, tcg_resh, elt->reg, elt->elt, MO_64);
> @@ -7012,9 +7012,12 @@ static void disas_simd_ext(DisasContext *s, uint32_t insn)
>  
>      write_vec_element(s, tcg_resl, rd, 0, MO_64);
>      tcg_temp_free_i64(tcg_resl);
> -    write_vec_element(s, tcg_resh, rd, 1, MO_64);
> -    tcg_temp_free_i64(tcg_resh);
> -    clear_vec_high(s, true, rd);
> +
> +    if (is_q) {
> +        write_vec_element(s, tcg_resh, rd, 1, MO_64);
> +        tcg_temp_free_i64(tcg_resh);
> +    }
> +    clear_vec_high(s, is_q, rd);
>  }
>  
>  /* TBL/TBX
> @@ -7051,17 +7054,21 @@ static void disas_simd_tb(DisasContext *s, uint32_t insn)
>       * the input.
>       */
>      tcg_resl = tcg_temp_new_i64();
> -    tcg_resh = tcg_temp_new_i64();
> +    tcg_resh = NULL;
>  
>      if (is_tblx) {
>          read_vec_element(s, tcg_resl, rd, 0, MO_64);
>      } else {
>          tcg_gen_movi_i64(tcg_resl, 0);
>      }
> -    if (is_tblx && is_q) {
> -        read_vec_element(s, tcg_resh, rd, 1, MO_64);
> -    } else {
> -        tcg_gen_movi_i64(tcg_resh, 0);
> +
> +    if (is_q) {
> +        tcg_resh = tcg_temp_new_i64();
> +        if (is_tblx) {
> +            read_vec_element(s, tcg_resh, rd, 1, MO_64);
> +        } else {
> +            tcg_gen_movi_i64(tcg_resh, 0);
> +        }
>      }
>  
>      tcg_idx = tcg_temp_new_i64();
> @@ -7081,9 +7088,12 @@ static void disas_simd_tb(DisasContext *s, uint32_t insn)
>  
>      write_vec_element(s, tcg_resl, rd, 0, MO_64);
>      tcg_temp_free_i64(tcg_resl);
> -    write_vec_element(s, tcg_resh, rd, 1, MO_64);
> -    tcg_temp_free_i64(tcg_resh);
> -    clear_vec_high(s, true, rd);
> +
> +    if (is_q) {
> +        write_vec_element(s, tcg_resh, rd, 1, MO_64);
> +        tcg_temp_free_i64(tcg_resh);
> +    }
> +    clear_vec_high(s, is_q, rd);
>  }
>  
>  /* ZIP/UZP/TRN
> @@ -7120,7 +7130,7 @@ static void disas_simd_zip_trn(DisasContext *s, uint32_t insn)
>      }
>  
>      tcg_resl = tcg_const_i64(0);
> -    tcg_resh = tcg_const_i64(0);
> +    tcg_resh = is_q ? tcg_const_i64(0) : NULL;
>      tcg_res = tcg_temp_new_i64();
>  
>      for (i = 0; i < elements; i++) {
> @@ -7171,9 +7181,12 @@ static void disas_simd_zip_trn(DisasContext *s, uint32_t insn)
>  
>      write_vec_element(s, tcg_resl, rd, 0, MO_64);
>      tcg_temp_free_i64(tcg_resl);
> -    write_vec_element(s, tcg_resh, rd, 1, MO_64);
> -    tcg_temp_free_i64(tcg_resh);
> -    clear_vec_high(s, true, rd);
> +
> +    if (is_q) {
> +        write_vec_element(s, tcg_resh, rd, 1, MO_64);
> +        tcg_temp_free_i64(tcg_resh);
> +    }
> +    clear_vec_high(s, is_q, rd);
>  }
>  
>  /*


-- 
Alex Bennée