Re: [PATCH v2 07/15] RISC-V: Adding T-Head multiply-accumulate instructions

[Alistair Francis]

On Sat, Dec 24, 2022 at 4:04 AM Christoph Muellner
<christoph.muellner@vrull.eu> wrote:
>
> From: Christoph Müllner <christoph.muellner@vrull.eu>
>
> This patch adds support for the T-Head MAC instructions.
> The patch uses the T-Head specific decoder and translation.
>
> Changes in v2:
> - Add ISA_EXT_DATA_ENTRY()
> - Use single decoder for XThead extensions
>
> Co-developed-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
> Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu>

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

Alistair

> ---
>  target/riscv/cpu.c                         |  2 +
>  target/riscv/cpu.h                         |  1 +
>  target/riscv/insn_trans/trans_xthead.c.inc | 83 ++++++++++++++++++++++
>  target/riscv/translate.c                   |  3 +-
>  target/riscv/xthead.decode                 |  8 +++
>  5 files changed, 96 insertions(+), 1 deletion(-)
>
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index 36a53784dd..88ad2138db 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -113,6 +113,7 @@ static const struct isa_ext_data isa_edata_arr[] = {
>      ISA_EXT_DATA_ENTRY(xtheadbs, true, PRIV_VERSION_1_11_0, ext_xtheadbs),
>      ISA_EXT_DATA_ENTRY(xtheadcmo, true, PRIV_VERSION_1_11_0, ext_xtheadcmo),
>      ISA_EXT_DATA_ENTRY(xtheadcondmov, true, PRIV_VERSION_1_11_0, 
> ext_xtheadcondmov),
> +    ISA_EXT_DATA_ENTRY(xtheadmac, true, PRIV_VERSION_1_11_0, ext_xtheadmac),
>      ISA_EXT_DATA_ENTRY(xtheadsync, true, PRIV_VERSION_1_11_0, 
> ext_xtheadsync),
>      ISA_EXT_DATA_ENTRY(xventanacondops, true, PRIV_VERSION_1_12_0, 
> ext_XVentanaCondOps),
>  };
> @@ -1071,6 +1072,7 @@ static Property riscv_cpu_extensions[] = {
>      DEFINE_PROP_BOOL("xtheadbs", RISCVCPU, cfg.ext_xtheadbs, false),
>      DEFINE_PROP_BOOL("xtheadcmo", RISCVCPU, cfg.ext_xtheadcmo, false),
>      DEFINE_PROP_BOOL("xtheadcondmov", RISCVCPU, cfg.ext_xtheadcondmov, 
> false),
> +    DEFINE_PROP_BOOL("xtheadmac", RISCVCPU, cfg.ext_xtheadmac, false),
>      DEFINE_PROP_BOOL("xtheadsync", RISCVCPU, cfg.ext_xtheadsync, false),
>      DEFINE_PROP_BOOL("xventanacondops", RISCVCPU, cfg.ext_XVentanaCondOps, 
> false),
>
> diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
> index 01f035d8e9..92198be9d8 100644
> --- a/target/riscv/cpu.h
> +++ b/target/riscv/cpu.h
> @@ -470,6 +470,7 @@ struct RISCVCPUConfig {
>      bool ext_xtheadbs;
>      bool ext_xtheadcmo;
>      bool ext_xtheadcondmov;
> +    bool ext_xtheadmac;
>      bool ext_xtheadsync;
>      bool ext_XVentanaCondOps;
>
> diff --git a/target/riscv/insn_trans/trans_xthead.c.inc 
> b/target/riscv/insn_trans/trans_xthead.c.inc
> index bf549bbd74..109be58c9b 100644
> --- a/target/riscv/insn_trans/trans_xthead.c.inc
> +++ b/target/riscv/insn_trans/trans_xthead.c.inc
> @@ -46,6 +46,12 @@
>      }                                            \
>  } while (0)
>
> +#define REQUIRE_XTHEADMAC(ctx) do {              \
> +    if (!ctx->cfg_ptr->ext_xtheadmac) {          \
> +        return false;                            \
> +    }                                            \
> +} while (0)
> +
>  #define REQUIRE_XTHEADSYNC(ctx) do {             \
>      if (!ctx->cfg_ptr->ext_xtheadsync) {         \
>          return false;                            \
> @@ -307,6 +313,83 @@ static bool trans_th_mvnez(DisasContext *ctx, 
> arg_th_mveqz *a)
>      return gen_th_condmove(ctx, a, TCG_COND_NE);
>  }
>
> +/* XTheadMac */
> +
> +static bool gen_th_mac(DisasContext *ctx, arg_r *a,
> +                       void (*accumulate_func)(TCGv, TCGv, TCGv),
> +                       void (*extend_operand_func)(TCGv, TCGv))
> +{
> +    TCGv dest = dest_gpr(ctx, a->rd);
> +    TCGv src0 = get_gpr(ctx, a->rd, EXT_NONE);
> +    TCGv src1 = get_gpr(ctx, a->rs1, EXT_NONE);
> +    TCGv src2 = get_gpr(ctx, a->rs2, EXT_NONE);
> +    TCGv tmp = tcg_temp_new();
> +
> +    if (extend_operand_func) {
> +        TCGv tmp2 = tcg_temp_new();
> +        extend_operand_func(tmp, src1);
> +        extend_operand_func(tmp2, src2);
> +        tcg_gen_mul_tl(tmp, tmp, tmp2);
> +        tcg_temp_free(tmp2);
> +    } else {
> +        tcg_gen_mul_tl(tmp, src1, src2);
> +    }
> +
> +    accumulate_func(dest, src0, tmp);
> +    gen_set_gpr(ctx, a->rd, dest);
> +    tcg_temp_free(tmp);
> +
> +    return true;
> +}
> +
> +/* th.mula: "rd = rd + rs1 * rs2" */
> +static bool trans_th_mula(DisasContext *ctx, arg_th_mula *a)
> +{
> +    REQUIRE_XTHEADMAC(ctx);
> +    return gen_th_mac(ctx, a, tcg_gen_add_tl, NULL);
> +}
> +
> +/* th.mulah: "rd = sext.w(rd + sext.w(rs1[15:0]) * sext.w(rs2[15:0]))" */
> +static bool trans_th_mulah(DisasContext *ctx, arg_th_mulah *a)
> +{
> +    REQUIRE_XTHEADMAC(ctx);
> +    ctx->ol = MXL_RV32;
> +    return gen_th_mac(ctx, a, tcg_gen_add_tl, tcg_gen_ext16s_tl);
> +}
> +
> +/* th.mulaw: "rd = sext.w(rd + rs1 * rs2)" */
> +static bool trans_th_mulaw(DisasContext *ctx, arg_th_mulaw *a)
> +{
> +    REQUIRE_XTHEADMAC(ctx);
> +    REQUIRE_64BIT(ctx);
> +    ctx->ol = MXL_RV32;
> +    return gen_th_mac(ctx, a, tcg_gen_add_tl, NULL);
> +}
> +
> +/* th.muls: "rd = rd - rs1 * rs2" */
> +static bool trans_th_muls(DisasContext *ctx, arg_th_muls *a)
> +{
> +    REQUIRE_XTHEADMAC(ctx);
> +    return gen_th_mac(ctx, a, tcg_gen_sub_tl, NULL);
> +}
> +
> +/* th.mulsh: "rd = sext.w(rd - sext.w(rs1[15:0]) * sext.w(rs2[15:0]))" */
> +static bool trans_th_mulsh(DisasContext *ctx, arg_th_mulsh *a)
> +{
> +    REQUIRE_XTHEADMAC(ctx);
> +    ctx->ol = MXL_RV32;
> +    return gen_th_mac(ctx, a, tcg_gen_sub_tl, tcg_gen_ext16s_tl);
> +}
> +
> +/* th.mulsw: "rd = sext.w(rd - rs1 * rs2)" */
> +static bool trans_th_mulsw(DisasContext *ctx, arg_th_mulsw *a)
> +{
> +    REQUIRE_XTHEADMAC(ctx);
> +    REQUIRE_64BIT(ctx);
> +    ctx->ol = MXL_RV32;
> +    return gen_th_mac(ctx, a, tcg_gen_sub_tl, NULL);
> +}
> +
>  /* XTheadSync */
>
>  static bool trans_th_sfence_vmas(DisasContext *ctx, arg_th_sfence_vmas *a)
> diff --git a/target/riscv/translate.c b/target/riscv/translate.c
> index f15883b16b..36f512baa8 100644
> --- a/target/riscv/translate.c
> +++ b/target/riscv/translate.c
> @@ -129,7 +129,8 @@ static bool has_xthead_p(DisasContext *ctx  
> __attribute__((__unused__)))
>  {
>      return ctx->cfg_ptr->ext_xtheadba || ctx->cfg_ptr->ext_xtheadbb ||
>             ctx->cfg_ptr->ext_xtheadbs || ctx->cfg_ptr->ext_xtheadcmo ||
> -           ctx->cfg_ptr->ext_xtheadcondmov || ctx->cfg_ptr->ext_xtheadsync;
> +           ctx->cfg_ptr->ext_xtheadcondmov || ctx->cfg_ptr->ext_xtheadmac ||
> +           ctx->cfg_ptr->ext_xtheadsync;
>  }
>
>  #define MATERIALISE_EXT_PREDICATE(ext)  \
> diff --git a/target/riscv/xthead.decode b/target/riscv/xthead.decode
> index a8ebd8a18b..696de6cecf 100644
> --- a/target/riscv/xthead.decode
> +++ b/target/riscv/xthead.decode
> @@ -88,6 +88,14 @@ th_l2cache_iall  0000000 10110 00000 000 00000 0001011
>  th_mveqz         0100000 ..... .....  001 ..... 0001011 @r
>  th_mvnez         0100001 ..... .....  001 ..... 0001011 @r
>
> +# XTheadMac
> +th_mula          00100 00 ..... ..... 001 ..... 0001011 @r
> +th_mulah         00101 00 ..... ..... 001 ..... 0001011 @r
> +th_mulaw         00100 10 ..... ..... 001 ..... 0001011 @r
> +th_muls          00100 01 ..... ..... 001 ..... 0001011 @r
> +th_mulsh         00101 01 ..... ..... 001 ..... 0001011 @r
> +th_mulsw         00100 11 ..... ..... 001 ..... 0001011 @r
> +
>  # XTheadSync
>  th_sfence_vmas   0000010 ..... ..... 000 00000 0001011 @rs2_s
>  th_sync          0000000 11000 00000 000 00000 0001011
> --
> 2.38.1
>
>