spesh comments for bindattr/getattr specialization of P6opaque

gistfile1.txt

After:
Spesh of 'pull-one' (cuid: 1346, file: SETTING::src/core/Rakudo/Iterator.pm6:1721)
Callsite 0x7f44ec8e0b20 (1 args, 1 pos)
Positional flags: obj

  BB 0 (0x7f44e43a9bb0):
    line: 1721 (pc 0)
    Instructions:
      no_op           
    Successors: 1
    Predecessors: 
    Dominance children: 1

  BB 1 (0x7f44e43a9c38):
    line: 1721 (pc 0)
    Instructions:
      [Annotation: INS Deopt One (idx 0 -> pc 30; line 1721)]
      sp_getarg_o       r0(2), liti16(0)
      [Annotation: Line Number: SETTING::src/core/Rakudo/Iterator.pm6:1721]
      takedispatcher    r3(2)
      [Annotation: FH Start (1)]
      sp_p6oget_i       r7(2),   r0(2), liti16(8)  # getattr_i of '$!i' in <anon|19>
      const_i64_16      r8(1), liti16(1)
      add_i             r8(2),   r7(2),   r8(1)
      sp_p6obind_i      r0(2), liti16(8),   r8(2)  # bindattr_i of '$!i' in <anon|19>
      sp_p6oget_i       r7(3),   r0(2), liti16(16)  # getattr_i of '$!last' in <anon|19>
      le_i              r7(4),   r8(2),   r7(3)
      unless_i          r7(4),   BB(3)
    Successors: 3, 2
    Predecessors: 0
    Dominance children: 2

  BB 2 (0x7f44e43a9e78):
    line: 1721 (pc 166)
    Instructions:
      sp_p6oget_i       r8(3),   r0(2), liti16(8)  # getattr_i of '$!i' in <anon|19>
      sp_fastbox_bi_ic   r6(3), liti16(40), sslot(5), liti16(32),   r8(3), liti16(1)
      goto              BB(4)
    Successors: 4
    Predecessors: 6
    Dominance children: 

  BB 3 (0x7f44e43a9ed8):
    line: 1721 (pc 212)
    Instructions:
      sp_getspeshslot   r6(4), sslot(3)
    Successors: 4
    Predecessors: 6
    Dominance children: 

  BB 4 (0x7f44e43a9f38):
    line: 1721 (pc 226)
    Instructions:
      PHI               r6(5),   r6(3),   r6(4)
      set               r4(5),   r6(5)
      [Annotation: INS Deopt One (idx 1 -> pc 232; line 1721)]
      /* sp_guard r4(8) r4(5); flags 0xc */
      /* sp_guard r4(8) r4(5); flags 0xc */
      sp_guard         r11(1),   r4(5), sslot(1), litui32(232)
      [Annotation: FH End (0)]
      [Annotation: INS Deopt One (idx 2 -> pc 250; line 1721)]
      [Annotation: Logged (bytecode offset 242)]
      [Annotation: INS Deopt One (idx 3 -> pc 250; line 1721)]
      sp_getspeshslot   r6(6), sslot(4)
    Successors: 5, 8
    Predecessors: 2, 3
    Dominance children: 5, 8, 9

  BB 5 (0x7f44e43a9f98):
    line: 1721 (pc 250)
    Instructions:
    Successors: 6, 8
    Predecessors: 4
    Dominance children: 6

  BB 6 (0x7f44e41d7970):
    Inlined
    line: 1721 (pc 0)
    Instructions:
    Successors: 7
    Predecessors: 5
    Dominance children: 7

  BB 7 (0x7f44e43a9ff8):
    line: 1721 (pc 266)
    Instructions:
      [Annotation: FH Start (0)]
      [Annotation: Inline Start (0)]
      [Annotation: Inline End (0)]
      [Annotation: FH Goto (0)]
      [Annotation: INS Deopt One (idx 4 -> pc 266; line 1721)]
      set               r6(7),  r11(1)  # sp_guardconc r6(7) r6(11); flags 0x0
      goto              BB(9)
    Successors: 9
    Predecessors: 6
    Dominance children: 

  BB 8 (0x7f44e43aa058):
    line: 1721 (pc 272)
    Instructions:
      [Annotation: FH Goto (1)]
      [Annotation: FH End (1)]
      lastexpayload     r6(9)
    Successors: 9
    Predecessors: 4, 5
    Dominance children: 

  BB 9 (0x7f44e43aa0b8):
    line: 1721 (pc 282)
    Instructions:
      PHI              r6(10),   r6(7),   r6(9)
      return_o         r6(10)
    Successors: 
    Predecessors: 7, 8
    Dominance children: