Make instr_dict.yaml more detailed

[Vinayakamk]

consider this instr_dict.yaml snippet of making extention rv*_c it has this c_sw: encoding: '----------------110-----------00' extension:

• rv_c mask: '0xe003' match: '0xc000' variable_fields:
• rs1_p
• rs2_p
• c_uimm7lo
• c_uimm7hi

i wish it would be more detailed and clear if the variable fields are bifurcated into immediate(or args ) and register fields like

args_field:

• c_uimm7lo

• c_uimm7hi register_field:

  • rs1_p
  • rs2_p

  this will be helpfull to analyse and know registers of the instructions of such type like "rv.zcmp": "cm.mva01s c_sreg1 c_sreg2 1..0=2 15..13=5 12..10=3 6..5=3", "cm.mvsa01 c_sreg1 c_sreg2 1..0=2 15..13=5 12..10=3 6..5=1", "cm.popret c_rlist c_spimm 1..0=2 15..13=5 12..8=0x1E", "cm.pop c_rlist c_spimm 1..0=2 15..13=5 12..8=0x1A", "cm.push c_rlist c_spimm 1..0=2 15..13=5 12..8=0x18", "cm.popretz c_rlist c_spimm 1..0=2 15..13=5 12..8=0x1C"

  since arg_lut.csv contains both register and imm fields,it is not clear to know what are registers and imm
  
  if there is the way to know it ,kindly let me know!
  thanks