Help with following RTL

[kernel coder]

hi,
Following is a c code .

int a;
main()
{
a=a+1;
}

This RTL generated for this programe for mips processor is

/*******************************************************/
; Function main

(note 2 0 3 NOTE_INSN_DELETED)

(note 3 2 4 NOTE_INSN_FUNCTION_BEG)

(note 4 3 5 NOTE_INSN_DELETED)

(note 5 4 6 NOTE_INSN_DELETED)

(note 6 5 8 NOTE_INSN_DELETED)

(insn 8 6 9 (nil) (set (reg:SI 182)
      (mem/f:SI (symbol_ref:SI ("a")) [0 a+0 S4 A32])) -1 (nil)
  (nil))

(insn 9 8 10 (nil) (set (reg:SI 183)
      (plus:SI (reg:SI 182)
          (const_int 1 [0x1]))) -1 (nil)
  (nil))

(insn 10 9 11 (nil) (set (mem/f:SI (symbol_ref:SI ("a")) [0 a+0 S4 A32])
      (reg:SI 183)) -1 (nil)
  (nil))

(note 11 10 15 NOTE_INSN_FUNCTION_END)

(insn 15 11 16 (nil) (clobber (reg/i:SI 2 v0)) -1 (nil)
  (nil))

(insn 16 15 13 (nil) (clobber (reg:SI 181)) -1 (nil)
  (nil))

(code_label 13 16 14 1 "" [0 uses])

(insn 14 13 17 (nil) (set (reg/i:SI 2 v0)
      (reg:SI 181)) -1 (nil)
         (nil))

(insn 17 14 0 (nil) (use (reg/i:SI 2 v0)) -1 (nil)
  (nil))

/*****************************************************/

I'm a newbie in RTL,so please explain what is happening in lines after
(note 11 10 15 NOTE_INSN_FUNCTION_END)


/******************************************************/
(insn 15 11 16 (nil) (clobber (reg/i:SI 2 v0)) -1 (nil)
  (nil))

(insn 16 15 13 (nil) (clobber (reg:SI 181)) -1 (nil)
  (nil))

(code_label 13 16 14 1 "" [0 uses])

(insn 14 13 17 (nil) (set (reg/i:SI 2 v0)
      (reg:SI 181)) -1 (nil)
         (nil))

(insn 17 14 0 (nil) (use (reg/i:SI 2 v0)) -1 (nil)
  (nil))
/***********************************/


thanks,
shahzad