Re: [PATCH 27/56] disas/riscv: Handle aliases of csrrw during decode

Alistair <[email protected]>
Newsgroups org.nongnu.qemu-riscv,org.nongnu.qemu-devel
Message-ID <[email protected]>
On Sun, 2026-08-09 at 15:35 -0700, Richard Henderson wrote:
> Signed-off-by: Richard Henderson <[email protected]>

Reviewed-by: Alistair Francis <[email protected]>

Alistair

> ---
>  disas/riscv.c | 22 +++++++++-------------
>  1 file changed, 9 insertions(+), 13 deletions(-)
> 
> diff --git a/disas/riscv.c b/disas/riscv.c
> index bde1cc6e62..e464b8b075 100644
> --- a/disas/riscv.c
> +++ b/disas/riscv.c
> @@ -1081,9 +1081,6 @@ static const rvc_constraint rvcc_frrm[] = {
> rvc_rs1_eq_x0, rvc_csr_eq_0x002,
>                                              rvc_end };
>  static const rvc_constraint rvcc_frflags[] = { rvc_rs1_eq_x0,
> rvc_csr_eq_0x001,
>                                                 rvc_end };
> -static const rvc_constraint rvcc_fscsr[] = { rvc_csr_eq_0x003,
> rvc_end };
> -static const rvc_constraint rvcc_fsrm[] = { rvc_csr_eq_0x002,
> rvc_end };
> -static const rvc_constraint rvcc_fsflags[] = { rvc_csr_eq_0x001,
> rvc_end };
>  static const rvc_constraint rvcc_fsrmi[] = { rvc_csr_eq_0x002,
> rvc_end };
>  static const rvc_constraint rvcc_fsflagsi[] = { rvc_csr_eq_0x001,
> rvc_end };
>  
> @@ -1166,14 +1163,6 @@ static const rv_comp_data rvcp_subw[] = {
>      { rv_op_illegal, NULL }
>  };
>  
> -static const rv_comp_data rvcp_csrrw[] = {
> -    { rv_op_fscsr, rvcc_fscsr },
> -    { rv_op_fsrm, rvcc_fsrm },
> -    { rv_op_fsflags, rvcc_fsflags },
> -    { rv_op_illegal, NULL }
> -};
> -
> -
>  static const rv_comp_data rvcp_csrrs[] = {
>      { rv_op_rdcycle, rvcc_rdcycle },
>      { rv_op_rdtime, rvcc_rdtime },
> @@ -1761,7 +1750,7 @@ static const rv_opcode_data rvi_opcode_data[] =
> {
>      { "sfence.vm", rv_codec_r, rv_fmt_rs1 },
>      { "sfence.vma", rv_codec_r, rv_fmt_rs1_rs2 },
>      { "wfi", rv_codec_none, rv_fmt_none },
> -    { "csrrw", rv_codec_i_csr, rv_fmt_rd_csr_rs1, rvcp_csrrw },
> +    { "csrrw", rv_codec_i_csr, rv_fmt_rd_csr_rs1 },
>      { "csrrs", rv_codec_i_csr, rv_fmt_rd_csr_rs1, rvcp_csrrs },
>      { "csrrc", rv_codec_i_csr, rv_fmt_rd_csr_rs1 },
>      { "csrrwi", rv_codec_i_csr, rv_fmt_rd_csr_zimm, rvcp_csrrwi },
> @@ -4443,7 +4432,14 @@ static void decode_inst_opcode(rv_decode *dec,
> rv_isa isa)
>                      break;
>                  }
>                  break;
> -            case 1: op = rv_op_csrrw; break;
> +            case 1:
> +                switch (operand_csr12(inst)) {
> +                case 1: op = rv_op_fsflags; break;
> +                case 2: op = rv_op_fsrm; break;
> +                case 3: op = rv_op_fscsr; break;
> +                default: op = rv_op_csrrw; break;
> +                }
> +                break;
>              case 2: op = rv_op_csrrs; break;
>              case 3: op = rv_op_csrrc; break;
>              case 4:
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