Re: [PATCH v2 2/5] RISC-V: Cache management instructions

["Christoph Müllner" <cmuellner@gcc.gnu.org>]

On Tue, Jan 11, 2022 at 11:26 AM Tsukasa OI via Binutils <
binutils@sourceware.org> wrote:

> This commit adds 'Zicbom' / 'Zicboz' instructions.
>
> bfd/ChangeLog:
>
>         * elfxx-riscv.c (riscv_multi_subset_supports): Add handling for
>         new instruction classes.
>
> include/ChangeLog:
>
>         * opcode/riscv-opc.h (MATCH_CBO_CLEAN, MASK_CBO_CLEAN,
>         MATCH_CBO_FLUSH, MASK_CBO_FLUSH, MATCH_CBO_INVAL,
>         MASK_CBO_INVAL, MATCH_CBO_ZERO, MASK_CBO_ZERO): New macros.
>         * opcode/riscv.h (enum riscv_insn_class): Add new instruction
>         classes INSN_CLASS_ZICBOM and INSN_CLASS_ZICBOZ.
>
> opcodes/ChangeLog:
>
>         * riscv-opc.c (riscv_opcodes): Add cache-block management
>         instructions.
> ---
>  bfd/elfxx-riscv.c          | 4 ++++
>  include/opcode/riscv-opc.h | 9 +++++++++
>  include/opcode/riscv.h     | 2 ++
>  opcodes/riscv-opc.c        | 6 ++++++
>  4 files changed, 21 insertions(+)
>
> diff --git a/bfd/elfxx-riscv.c b/bfd/elfxx-riscv.c
> index 3761811d4fd..a7cd9320655 100644
> --- a/bfd/elfxx-riscv.c
> +++ b/bfd/elfxx-riscv.c
> @@ -2334,6 +2334,10 @@ riscv_multi_subset_supports (riscv_parse_subset_t
> *rps,
>      {
>      case INSN_CLASS_I:
>        return riscv_subset_supports (rps, "i");
> +    case INSN_CLASS_ZICBOM:
> +      return riscv_subset_supports (rps, "zicbom");
> +    case INSN_CLASS_ZICBOZ:
> +      return riscv_subset_supports (rps, "zicboz");
>      case INSN_CLASS_ZICSR:
>        return riscv_subset_supports (rps, "zicsr");
>      case INSN_CLASS_ZIFENCEI:
> diff --git a/include/opcode/riscv-opc.h b/include/opcode/riscv-opc.h
> index 0b8cc6c7ddb..b24e8a47c87 100644
> --- a/include/opcode/riscv-opc.h
> +++ b/include/opcode/riscv-opc.h
> @@ -2029,6 +2029,15 @@
>  #define MASK_HSV_W 0xfe007fff
>  #define MATCH_HSV_D 0x6e004073
>  #define MASK_HSV_D 0xfe007fff
> +/* Zicbom/Zicboz instructions. */
> +#define MATCH_CBO_CLEAN 0x10200f
> +#define MASK_CBO_CLEAN 0xfff07fff
> +#define MATCH_CBO_FLUSH 0x20200f
> +#define MASK_CBO_FLUSH 0xfff07fff
> +#define MATCH_CBO_INVAL 0x200f
> +#define MASK_CBO_INVAL 0xfff07fff
> +#define MATCH_CBO_ZERO 0x40200f
> +#define MASK_CBO_ZERO 0xfff07fff
>  /* Privileged CSR addresses.  */
>  #define CSR_USTATUS 0x0
>  #define CSR_UIE 0x4
> diff --git a/include/opcode/riscv.h b/include/opcode/riscv.h
> index 048ab0a5d68..1d74f0e521a 100644
> --- a/include/opcode/riscv.h
> +++ b/include/opcode/riscv.h
> @@ -388,6 +388,8 @@ enum riscv_insn_class
>    INSN_CLASS_V,
>    INSN_CLASS_ZVEF,
>    INSN_CLASS_SVINVAL,
> +  INSN_CLASS_ZICBOM,
> +  INSN_CLASS_ZICBOZ,
>  };
>
>  /* This structure holds information for a particular instruction.  */
> diff --git a/opcodes/riscv-opc.c b/opcodes/riscv-opc.c
> index 2da0f7cf0a4..07835ddd071 100644
> --- a/opcodes/riscv-opc.c
> +++ b/opcodes/riscv-opc.c
> @@ -849,6 +849,12 @@ const struct riscv_opcode riscv_opcodes[] =
>  {"sfence.vma", 0, INSN_CLASS_I,    "s,t",      MATCH_SFENCE_VMA,
> MASK_SFENCE_VMA, match_opcode, 0 },
>  {"wfi",        0, INSN_CLASS_I,    "",         MATCH_WFI, MASK_WFI,
> match_opcode, 0 },
>
> +/* Zicbom and Zicboz instructions.  */
> +{"cbo.clean",  0, INSN_CLASS_ZICBOM, "s", MATCH_CBO_CLEAN,
> MASK_CBO_CLEAN, match_opcode, 0 },
> +{"cbo.flush",  0, INSN_CLASS_ZICBOM, "s", MATCH_CBO_FLUSH,
> MASK_CBO_FLUSH, match_opcode, 0 },
> +{"cbo.inval",  0, INSN_CLASS_ZICBOM, "s", MATCH_CBO_INVAL,
> MASK_CBO_INVAL, match_opcode, 0 },
> +{"cbo.zero",   0, INSN_CLASS_ZICBOZ, "s", MATCH_CBO_ZERO, MASK_CBO_ZERO,
> match_opcode, 0 },
> +
>

Hi Tsukasa,

There has been a discussion ([1]) about using "0(a0)"/"(a0)" vs "a0" as
operand format for these instructions.
Following that discussion, I'd suggest using the AMO (zero-)displacement
format ("0(s)") here (and adjusting the tests accordingly).

BR
Christoph

[1] https://github.com/riscv/riscv-CMOs/issues/47



>  /* Zbb or zbkb instructions.  */
>  {"clz",        0, INSN_CLASS_ZBB,  "d,s",   MATCH_CLZ, MASK_CLZ,
> match_opcode, 0 },
>  {"ctz",        0, INSN_CLASS_ZBB,  "d,s",   MATCH_CTZ, MASK_CTZ,
> match_opcode, 0 },
> --
> 2.32.0
>