Re: [PATCH v8 63/78] target/riscv: add "set round to odd" rounding mode helper function

[Alistair Francis]

On Fri, Oct 15, 2021 at 6:39 PM <frank.chang@sifive.com> wrote:
>
> From: Frank Chang <frank.chang@sifive.com>
>
> helper_set_rounding_mode() is responsible for SIGILL, and "round to odd"
> should be an interface private to translation, so add a new independent
> helper_set_rod_rounding_mode().
>
> Signed-off-by: Frank Chang <frank.chang@sifive.com>

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

Alistair

> ---
>  target/riscv/fpu_helper.c | 5 +++++
>  target/riscv/helper.h     | 1 +
>  target/riscv/internals.h  | 1 +
>  target/riscv/translate.c  | 7 +++++++
>  4 files changed, 14 insertions(+)
>
> diff --git a/target/riscv/fpu_helper.c b/target/riscv/fpu_helper.c
> index 43ce6148313..cf21097b5fb 100644
> --- a/target/riscv/fpu_helper.c
> +++ b/target/riscv/fpu_helper.c
> @@ -81,6 +81,11 @@ void helper_set_rounding_mode(CPURISCVState *env, uint32_t 
> rm)
>      set_float_rounding_mode(softrm, &env->fp_status);
>  }
>
> +void helper_set_rod_rounding_mode(CPURISCVState *env)
> +{
> +    set_float_rounding_mode(float_round_to_odd, &env->fp_status);
> +}
> +
>  static uint64_t do_fmadd_h(CPURISCVState *env, uint64_t rs1, uint64_t rs2,
>                             uint64_t rs3, int flags)
>  {
> diff --git a/target/riscv/helper.h b/target/riscv/helper.h
> index 53cf88cd402..606bf72d5cb 100644
> --- a/target/riscv/helper.h
> +++ b/target/riscv/helper.h
> @@ -3,6 +3,7 @@ DEF_HELPER_2(raise_exception, noreturn, env, i32)
>
>  /* Floating Point - rounding mode */
>  DEF_HELPER_FLAGS_2(set_rounding_mode, TCG_CALL_NO_WG, void, env, i32)
> +DEF_HELPER_FLAGS_1(set_rod_rounding_mode, TCG_CALL_NO_WG, void, env)
>
>  /* Floating Point - fused */
>  DEF_HELPER_FLAGS_4(fmadd_s, TCG_CALL_NO_RWG, i64, env, i64, i64, i64)
> diff --git a/target/riscv/internals.h b/target/riscv/internals.h
> index db105d4d640..065e8162a2f 100644
> --- a/target/riscv/internals.h
> +++ b/target/riscv/internals.h
> @@ -43,6 +43,7 @@ enum {
>      RISCV_FRM_RUP = 3,  /* Round Up */
>      RISCV_FRM_RMM = 4,  /* Round to Nearest, ties to Max Magnitude */
>      RISCV_FRM_DYN = 7,  /* Dynamic rounding mode */
> +    RISCV_FRM_ROD = 8,  /* Round to Odd */
>  };
>
>  static inline uint64_t nanbox_s(float32 f)
> diff --git a/target/riscv/translate.c b/target/riscv/translate.c
> index 6a3f105d431..6fa7e016e22 100644
> --- a/target/riscv/translate.c
> +++ b/target/riscv/translate.c
> @@ -30,6 +30,7 @@
>  #include "exec/log.h"
>
>  #include "instmap.h"
> +#include "internals.h"
>
>  /* global register indices */
>  static TCGv cpu_gpr[32], cpu_pc, cpu_vl;
> @@ -382,6 +383,12 @@ static void gen_set_rm(DisasContext *ctx, int rm)
>          return;
>      }
>      ctx->frm = rm;
> +
> +    if (rm == RISCV_FRM_ROD) {
> +        gen_helper_set_rod_rounding_mode(cpu_env);
> +        return;
> +    }
> +
>      gen_helper_set_rounding_mode(cpu_env, tcg_constant_i32(rm));
>  }
>
> --
> 2.25.1
>
>