Re: [Qemu-devel] [PATCH 20/38] target-arm: Implement adc_cc inline

[Peter Crosthwaite]

Hi All,

This patch breaks ARM TCG. Fix comming shortly.

On Wed, Feb 20, 2013 at 5:52 PM, Richard Henderson <address@hidden> wrote:
> Use add2 if available, otherwise use 64-bit arithmetic.
>
> Cc: Peter Maydell <address@hidden>
> Signed-off-by: Richard Henderson <address@hidden>
> ---
>  target-arm/helper.h    |  1 -
>  target-arm/op_helper.c | 15 ---------------
>  target-arm/translate.c | 39 ++++++++++++++++++++++++++++++++++-----
>  3 files changed, 34 insertions(+), 21 deletions(-)
>
> diff --git a/target-arm/helper.h b/target-arm/helper.h
> index bca5a5b..507bb9c 100644
> --- a/target-arm/helper.h
> +++ b/target-arm/helper.h
> @@ -140,7 +140,6 @@ DEF_HELPER_2(recpe_u32, i32, i32, env)
>  DEF_HELPER_2(rsqrte_u32, i32, i32, env)
>  DEF_HELPER_5(neon_tbl, i32, env, i32, i32, i32, i32)
>
> -DEF_HELPER_3(adc_cc, i32, env, i32, i32)
>  DEF_HELPER_3(sbc_cc, i32, env, i32, i32)
>
>  DEF_HELPER_3(shl_cc, i32, env, i32, i32)
> diff --git a/target-arm/op_helper.c b/target-arm/op_helper.c
> index 99610d7..49fc036 100644
> --- a/target-arm/op_helper.c
> +++ b/target-arm/op_helper.c
> @@ -315,21 +315,6 @@ uint64_t HELPER(get_cp_reg64)(CPUARMState *env, void 
> *rip)
>     The only way to do that in TCG is a conditional branch, which clobbers
>     all our temporaries.  For now implement these as helper functions.  */
>
> -uint32_t HELPER(adc_cc)(CPUARMState *env, uint32_t a, uint32_t b)
> -{
> -    uint32_t result;
> -    if (!env->CF) {
> -        result = a + b;
> -        env->CF = result < a;
> -    } else {
> -        result = a + b + 1;
> -        env->CF = result <= a;
> -    }
> -    env->VF = (a ^ b ^ -1) & (a ^ result);
> -    env->NF = env->ZF = result;
> -    return result;
> -}
> -
>  uint32_t HELPER(sbc_cc)(CPUARMState *env, uint32_t a, uint32_t b)
>  {
>      uint32_t result;
> diff --git a/target-arm/translate.c b/target-arm/translate.c
> index ca6f0af..493448a 100644
> --- a/target-arm/translate.c
> +++ b/target-arm/translate.c
> @@ -421,6 +421,34 @@ static void gen_add_CC(TCGv dest, TCGv t0, TCGv t1)
>      tcg_gen_mov_i32(dest, cpu_NF);
>  }
>
> +/* dest = T0 + T1 + CF.  Compute C, N, V and Z flags */
> +static void gen_adc_CC(TCGv dest, TCGv t0, TCGv t1)
> +{
> +    TCGv tmp = tcg_temp_new_i32();
> +    if (TCG_TARGET_HAS_add2_i32) {
> +        tcg_gen_movi_i32(tmp, 0);
> +        tcg_gen_add2_i32(cpu_NF, cpu_CF, t0, tmp, cpu_CF, tmp);

You discard the intermediary add result stored in NF here and add A to
B. You have effectively discarded incoming carry here.

Regards,
Peter

> +        tcg_gen_add2_i32(cpu_NF, cpu_CF, t0, cpu_CF, t1, tmp);
> +    } else {
> +        TCGv_i64 q0 = tcg_temp_new_i64();
> +        TCGv_i64 q1 = tcg_temp_new_i64();
> +        tcg_gen_extu_i32_i64(q0, t0);
> +        tcg_gen_extu_i32_i64(q1, t1);
> +        tcg_gen_add_i64(q0, q0, q1);
> +        tcg_gen_extu_i32_i64(q1, cpu_CF);
> +        tcg_gen_add_i64(q0, q0, q1);
> +        tcg_gen_extr_i64_i32(cpu_NF, cpu_CF, q0);
> +        tcg_temp_free_i64(q0);
> +        tcg_temp_free_i64(q1);
> +    }
> +    tcg_gen_mov_i32(cpu_ZF, cpu_NF);
> +    tcg_gen_xor_i32(cpu_VF, cpu_NF, t0);
> +    tcg_gen_xor_i32(tmp, t0, t1);
> +    tcg_gen_andc_i32(cpu_VF, cpu_VF, tmp);
> +    tcg_temp_free_i32(tmp);
> +    tcg_gen_mov_i32(dest, cpu_NF);
> +}
> +
>  /* dest = T0 - T1. Compute C, N, V and Z flags */
>  static void gen_sub_CC(TCGv dest, TCGv t0, TCGv t1)
>  {
> @@ -7073,7 +7101,7 @@ static void disas_arm_insn(CPUARMState * env, 
> DisasContext *s)
>              break;
>          case 0x05:
>              if (set_cc) {
> -                gen_helper_adc_cc(tmp, cpu_env, tmp, tmp2);
> +                gen_adc_CC(tmp, tmp, tmp2);
>              } else {
>                  gen_add_carry(tmp, tmp, tmp2);
>              }
> @@ -7914,7 +7942,7 @@ gen_thumb2_data_op(DisasContext *s, int op, int conds, 
> uint32_t shifter_out, TCG
>          break;
>      case 10: /* adc */
>          if (conds)
> -            gen_helper_adc_cc(t0, cpu_env, t0, t1);
> +            gen_adc_CC(t0, t0, t1);
>          else
>              gen_adc(t0, t1);
>          break;
> @@ -9232,10 +9260,11 @@ static void disas_thumb_insn(CPUARMState *env, 
> DisasContext *s)
>              }
>              break;
>          case 0x5: /* adc */
> -            if (s->condexec_mask)
> +            if (s->condexec_mask) {
>                  gen_adc(tmp, tmp2);
> -            else
> -                gen_helper_adc_cc(tmp, cpu_env, tmp, tmp2);
> +            } else {
> +                gen_adc_CC(tmp, tmp, tmp2);
> +            }
>              break;
>          case 0x6: /* sbc */
>              if (s->condexec_mask)
> --
> 1.8.1.2
>
>