Re: [PATCH v6 09/14] target/riscv: Add orc.b instruction for Zbb, removing gorc/gorci

[Alistair Francis <alistair23@gmail.com>]

On Thu, Aug 26, 2021 at 3:18 AM Philipp Tomsich
<philipp.tomsich@vrull.eu> wrote:
>
> The 1.0.0 version of Zbb does not contain gorc/gorci.  Instead, a
> orc.b instruction (equivalent to the orc.b pseudo-instruction built on
> gorci from pre-0.93 draft-B) is available, mainly targeting
> string-processing workloads.
>
> This commit adds the new orc.b instruction and removed gorc/gorci.
>
> Signed-off-by: Philipp Tomsich <philipp.tomsich@vrull.eu>
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>
> Changes in v6:
> - Fixed orc.b (now passes SPEC w/ optimized string functions) by
>   adding the missing final negation.
>
> Changes in v4:
> - Change orc.b to implementation suggested by Richard Henderson
>
> Changes in v3:
> - Moved orc.b and gorc/gorci changes into separate commit.
> - Using the simpler orc.b implementation suggested by Richard Henderson
>
>  target/riscv/bitmanip_helper.c          | 26 -----------------
>  target/riscv/helper.h                   |  2 --
>  target/riscv/insn32.decode              |  6 +---
>  target/riscv/insn_trans/trans_rvb.c.inc | 38 ++++++++++++-------------
>  target/riscv/translate.c                |  6 ----
>  5 files changed, 19 insertions(+), 59 deletions(-)
>
> diff --git a/target/riscv/bitmanip_helper.c b/target/riscv/bitmanip_helper.c
> index 73be5a81c7..bb48388fcd 100644
> --- a/target/riscv/bitmanip_helper.c
> +++ b/target/riscv/bitmanip_helper.c
> @@ -64,32 +64,6 @@ target_ulong HELPER(grevw)(target_ulong rs1, target_ulong rs2)
>      return do_grev(rs1, rs2, 32);
>  }
>
> -static target_ulong do_gorc(target_ulong rs1,
> -                            target_ulong rs2,
> -                            int bits)
> -{
> -    target_ulong x = rs1;
> -    int i, shift;
> -
> -    for (i = 0, shift = 1; shift < bits; i++, shift <<= 1) {
> -        if (rs2 & shift) {
> -            x |= do_swap(x, adjacent_masks[i], shift);
> -        }
> -    }
> -
> -    return x;
> -}
> -
> -target_ulong HELPER(gorc)(target_ulong rs1, target_ulong rs2)
> -{
> -    return do_gorc(rs1, rs2, TARGET_LONG_BITS);
> -}
> -
> -target_ulong HELPER(gorcw)(target_ulong rs1, target_ulong rs2)
> -{
> -    return do_gorc(rs1, rs2, 32);
> -}
> -
>  target_ulong HELPER(clmul)(target_ulong rs1, target_ulong rs2)
>  {
>      target_ulong result = 0;
> diff --git a/target/riscv/helper.h b/target/riscv/helper.h
> index c559c860a7..80561e8866 100644
> --- a/target/riscv/helper.h
> +++ b/target/riscv/helper.h
> @@ -61,8 +61,6 @@ DEF_HELPER_FLAGS_1(fclass_d, TCG_CALL_NO_RWG_SE, tl, i64)
>  /* Bitmanip */
>  DEF_HELPER_FLAGS_2(grev, TCG_CALL_NO_RWG_SE, tl, tl, tl)
>  DEF_HELPER_FLAGS_2(grevw, TCG_CALL_NO_RWG_SE, tl, tl, tl)
> -DEF_HELPER_FLAGS_2(gorc, TCG_CALL_NO_RWG_SE, tl, tl, tl)
> -DEF_HELPER_FLAGS_2(gorcw, TCG_CALL_NO_RWG_SE, tl, tl, tl)
>  DEF_HELPER_FLAGS_2(clmul, TCG_CALL_NO_RWG_SE, tl, tl, tl)
>  DEF_HELPER_FLAGS_2(clmulr, TCG_CALL_NO_RWG_SE, tl, tl, tl)
>
> diff --git a/target/riscv/insn32.decode b/target/riscv/insn32.decode
> index faa56836d8..8bcb602455 100644
> --- a/target/riscv/insn32.decode
> +++ b/target/riscv/insn32.decode
> @@ -680,6 +680,7 @@ max        0000101 .......... 110 ..... 0110011 @r
>  maxu       0000101 .......... 111 ..... 0110011 @r
>  min        0000101 .......... 100 ..... 0110011 @r
>  minu       0000101 .......... 101 ..... 0110011 @r
> +orc_b      001010 000111 ..... 101 ..... 0010011 @r2
>  orn        0100000 .......... 110 ..... 0110011 @r
>  rol        0110000 .......... 001 ..... 0110011 @r
>  ror        0110000 .......... 101 ..... 0110011 @r
> @@ -701,19 +702,14 @@ pack       0000100 .......... 100 ..... 0110011 @r
>  packu      0100100 .......... 100 ..... 0110011 @r
>  packh      0000100 .......... 111 ..... 0110011 @r
>  grev       0110100 .......... 101 ..... 0110011 @r
> -gorc       0010100 .......... 101 ..... 0110011 @r
> -
>  grevi      01101. ........... 101 ..... 0010011 @sh
> -gorci      00101. ........... 101 ..... 0010011 @sh
>
>  # *** RV64B Standard Extension (in addition to RV32B) ***
>  packw      0000100 .......... 100 ..... 0111011 @r
>  packuw     0100100 .......... 100 ..... 0111011 @r
>  grevw      0110100 .......... 101 ..... 0111011 @r
> -gorcw      0010100 .......... 101 ..... 0111011 @r
>
>  greviw     0110100 .......... 101 ..... 0011011 @sh5
> -gorciw     0010100 .......... 101 ..... 0011011 @sh5
>
>  # *** RV32 Zbc Standard Extension ***
>  clmul      0000101 .......... 001 ..... 0110011 @r
> diff --git a/target/riscv/insn_trans/trans_rvb.c.inc b/target/riscv/insn_trans/trans_rvb.c.inc
> index 03b3724c96..f3b85ca189 100644
> --- a/target/riscv/insn_trans/trans_rvb.c.inc
> +++ b/target/riscv/insn_trans/trans_rvb.c.inc
> @@ -215,18 +215,30 @@ static bool trans_grevi(DisasContext *ctx, arg_grevi *a)
>      return gen_grevi(ctx, a);
>  }
>
> -static bool trans_gorc(DisasContext *ctx, arg_gorc *a)
> +static void gen_orc_b(TCGv ret, TCGv source1)
>  {
> -    REQUIRE_EXT(ctx, RVB);
> -    return gen_shift(ctx, a, gen_helper_gorc);
> +    TCGv  tmp = tcg_temp_new();

Doesn't this need to be freed?

Alistair