Re: [PATCH v5 2/3] target/riscv: Reuse tb->flags.FS

[Alistair Francis]

On Fri, May 19, 2023 at 3:51 AM Mayuresh Chitale
<mchitale@ventanamicro.com> wrote:
>
> When misa.F is 0 tb->flags.FS field is unused and can be used to save
> the current state of smstateen0.FCSR check which is needed by the
> floating point translation routines.
>
> Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> Reviewed-by: Weiwei Li <liweiwei@iscas.ac.cn>

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

Alistair

> ---
>  target/riscv/cpu_helper.c               | 6 ++++++
>  target/riscv/insn_trans/trans_rvf.c.inc | 7 ++++---
>  2 files changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
> index b68dcfe7b6..695c189f96 100644
> --- a/target/riscv/cpu_helper.c
> +++ b/target/riscv/cpu_helper.c
> @@ -119,6 +119,12 @@ void cpu_get_tb_cpu_state(CPURISCVState *env, 
> target_ulong *pc,
>          vs = MIN(vs, get_field(env->mstatus_hs, MSTATUS_VS));
>      }
>
> +    /* With Zfinx, floating point is enabled/disabled by Smstateen. */
> +    if (!riscv_has_ext(env, RVF)) {
> +        fs = (smstateen_acc_ok(env, 0, SMSTATEEN0_FCSR) == RISCV_EXCP_NONE)
> +             ? EXT_STATUS_DIRTY : EXT_STATUS_DISABLED;
> +    }
> +
>      if (cpu->cfg.debug && !icount_enabled()) {
>          flags = FIELD_DP32(flags, TB_FLAGS, ITRIGGER, env->itrigger_enabled);
>      }
> diff --git a/target/riscv/insn_trans/trans_rvf.c.inc 
> b/target/riscv/insn_trans/trans_rvf.c.inc
> index b2de4fcf3f..509a6acffe 100644
> --- a/target/riscv/insn_trans/trans_rvf.c.inc
> +++ b/target/riscv/insn_trans/trans_rvf.c.inc
> @@ -19,9 +19,10 @@
>   */
>
>  #define REQUIRE_FPU do {\
> -    if (ctx->mstatus_fs == EXT_STATUS_DISABLED) \
> -        if (!ctx->cfg_ptr->ext_zfinx) \
> -            return false; \
> +    if (ctx->mstatus_fs == EXT_STATUS_DISABLED) {                           \
> +        ctx->virt_inst_excp = ctx->virt_enabled && ctx->cfg_ptr->ext_zfinx; \
> +        return false;                                                       \
> +    }                                                                       \
>  } while (0)
>
>  #define REQUIRE_ZFINX_OR_F(ctx) do {\
> --
> 2.34.1
>