vfmerge.vfm

{
  let rm_3b         = fcsr.FRM();
  let start_element = get_start_element();
  let end_element   = get_end_element();
  let SEW           = get_sew();
  let LMUL_pow      = get_lmul_pow();
  let num_elem      = get_num_elem(LMUL_pow, SEW); /* max(VLMAX,VLEN/SEW)) */
  let real_num_elem = if LMUL_pow >= 0 then num_elem else num_elem / (0 - LMUL_pow); /* VLMAX */

  if illegal_fp_vd_masked(vd, SEW, rm_3b) then { handle_illegal(); return RETIRE_FAIL };
  assert(SEW != 8);

  let 'n = num_elem;
  let 'm = SEW;

  let vm_val  : vector('n, dec, bool)     = read_vmask(num_elem, 0b0, 0b00000);
  let rs1_val : bits('m)                  = get_scalar_fp(rs1, 'm);
  let vs2_val : vector('n, dec, bits('m)) = read_vreg(num_elem, SEW, LMUL_pow, vs2);
  let vd_val  : vector('n, dec, bits('m)) = read_vreg(num_elem, SEW, LMUL_pow, vd);
  result      : vector('n, dec, bits('m)) = undefined;

  let tail_ag : agtype = get_vtype_vta();
  foreach (i from 0 to (num_elem - 1)) {
    if i < start_element then {
      result[i] = vd_val[i]
    } else if i > end_element | i >= real_num_elem then {
      result[i] = match tail_ag {
        UNDISTURBED => vd_val[i],
        AGNOSTIC    => vd_val[i] /* TODO: configuration support */
      }
    } else {
      /* the merge operates on all body elements */
      result[i] = if vm_val[i] then rs1_val else vs2_val[i]
    }
  };

  write_vreg(num_elem, SEW, LMUL_pow, vd, result);
  vstart = zeros();
  RETIRE_SUCCESS
}