[PATCH] RISC-V: Add SpacemiT vendor extensions xsmtvdot

[Jan Beulich]

On 09.04.2026 13:37, Mark Zhuang wrote:
> --- a/gas/NEWS
> +++ b/gas/NEWS
> @@ -17,6 +17,9 @@ Changes in 2.46:
>  * Add support for RISC-V standard extensions:
>    sdtrig v1.0, ssstrict v1.0.
>  
> +* Add support for RISC-V vendor extensions:
> +  SpacemiT: xsmtvdot v1.0.
> +
>  * The assembler now supports generating SFrame Version 3 format.  This version
>    supports .text > 2 GiB, support for marking outermost frames, support for
>    marking signal trampolines, and support for "flexible" frames which have

This clearly is in need of adjustment. 2.46 has already gone out.

> --- a/gas/config/tc-riscv.c
> +++ b/gas/config/tc-riscv.c
> @@ -1771,6 +1771,29 @@ validate_riscv_insn (const struct riscv_opcode *opc, int length)
>  		    goto unknown_validate_operand;
>  		}
>  		break;
> +	    case 'p': /* Vendor-specific (SpacemiT) operands.  */
> +		switch (*++oparg)
> +		{
> +		  case 'V':
> +		    switch (*++oparg)
> +			  {
> +			  case 'd': USE_BITS (OP_MASK_SPACEMIT_IME_VD, OP_SH_SPACEMIT_IME_VD); break;
> +			  case 's': USE_BITS (OP_MASK_SPACEMIT_IME_VS1, OP_SH_SPACEMIT_IME_VS1); break;
> +			  default:
> +			    goto unknown_validate_operand;
> +			  }
> +			  break;
> +		  case 'w': /* Xpw&S ... bits in S indicates whether corresponding item is permitted.  */
> +		    if (*++oparg != '&')
> +		      goto unknown_validate_operand;
> +		    strtol (oparg + 1, (char **)&oparg, 16);
> +		    oparg--;
> +		    USE_BITS (OP_MASK_SPACEMIT_IME_WI, OP_SH_SPACEMIT_IME_WI);
> +		    break;
> +		  default:
> +		    goto unknown_validate_operand;
> +		}
> +		break;
>  	    default:
>  	      goto unknown_validate_operand;
>  	    }

There look to be issues with indentation and line length throughout here. And
more further down, including in disassembler code.

> --- a/opcodes/riscv-opc.c
> +++ b/opcodes/riscv-opc.c
> @@ -122,6 +122,12 @@ const char * const riscv_th_vediv[4] =
>      "d1", "d2", "d4", "d8"
>  };
>  
> +/* XSmtVdot, List of int type width constants.  */
> +const char * const riscv_smt_wi[4] =
> +{
> +    "i2", "i16", "i4", "i8"
> +};

Do you really need to use arg_lookup() for these, and hence do you really need
this table (requiring more space for the pointers than for the actual strings
pointed to)?

> @@ -3579,6 +3585,45 @@ const struct riscv_opcode riscv_opcodes[] =
>  {"mips.sdp", 0, INSN_CLASS_XMIPSLSP, "t,r,Xm^(s)", MATCH_MIPS_SDP, MASK_MIPS_SDP, match_opcode, 0 },
>  {"mips.swp", 0, INSN_CLASS_XMIPSLSP, "t,r,Xm&(s)", MATCH_MIPS_SWP, MASK_MIPS_SWP, match_opcode, 0 },
>  
> +/* SpacemiT custom instructions. */
> +/* Int Matrix Multi-Accumulation */
> +{"smt.vmadot",   0, INSN_CLASS_XSMTVDOT, "XpVd,Vs,Vt",       MATCH_SMT_VMADOT_I8,   MASK_SMT_VMADOT_I8,   match_opcode, INSN_ALIAS },
> +{"smt.vmadot",   0, INSN_CLASS_XSMTVDOT, "XpVd,Vs,Vt,Xpw&8", MATCH_SMT_VMADOT,      MASK_SMT_VMADOT,      match_opcode, 0 },

Rather than having two entries each, can't you handle to Xpw&8 operand as an
optional one, like is done for Vm (and I'm soon to submit a patch to do the
same for floating point rounding mode operands)? We shouldn't grow this ever
growing table more than necessary, imo.

Jan