CS 132 Fall 2005, Final Exam, Proposed Solutions
------------------------------------------------

Q.1.  P ---> fields: 
                next:Q
             methods:
                expand: () -> void
                        locals:
                           temp: Q
                           v: P
      Q ---> fields:
                pred: P
                succ: P
             methods:
                insert: (x:P, y:P) -> void

Q.2.  --->[next]
   
      // I will show code that relies on that there are no extends clauses
      // and that does not build virtual tables.
      // I am writing "TEMP n" as "TEMP_n", for readability.

      // this -> TEMP_0
      // temp -> TEMP_1
      //    v -> TEMP_2

      HLOAD TEMP_1 TEMP_0 0   // temp = next;

      HALLOCATE TEMP_2 4      // v = new P();
      HSTORE TEMP_2 0 0

      HALLOCATE TEMP_10 8     // next = new Q();
      HSTORE TEMP_10 0 0
      HSTORE TEMP_10 4 0
      HSTORE TEMP_0 0 TEMP_10

      HSTORE TEMP_2 0 TEMP_1  // v.next = temp;

      HSTORE TEMP_1 0 TEMP_2  // temp.pred = v;

      move TEMP_20 CALL Q_insert(TEMP_0 TEMP_2)  // next.insert(this, v)

Q.3.  this  (incoming parameter)
      ------ 
      old fp 
      ra
      ------
      temp
      v
      ------
      compiler-generated temporaries
      ------
      callee-save registers
      ------
      this (outgoing parameters)
      v

Q.4.        
             |
           a |
             v
            i = 10
             |
         a,i |
             v
       L1:  if i < 80 then goto L2
             |                |   ^
         a,i |                |   |
             v                |   |
            a = a + 1         |   |
             |                |   |
         a,i |                |   |
             v                |   |
            b = a             |   |
             |                |   |
         b,i |            a,i |   | a,i
             v                |   |
            a = i             |   |
             |                |   |
         a,b |                |   |
             v                |   |
            i = b             |   |
             |                |   |
         a,i |                |   |
             v                |   |
            i = i + 2         |   |
             |                |   |
         a,i |                |   |
             v                |   |
            goto L2           |   |
             |                |   |
         a,i |     a = a + i  |   |
             v                v   |
       L2:  if i < 9 then goto L1 
             |
           i |
             v
            return i

Q.5.       1
            b
            |
            |
    1       |4      1
     f ---- a ---- e
     |\    /|    
     | \  / |    
     |  \/  |    
     |  /\  |   
     | /  \ |   
     |/    \|   
     d ---- c
    2        3

      r4 = 1
      r1 = 10
      r3 = 8 + r1
      r2 = r4 + r3
      r1 = r4 + r2
      r1 = r3 + r1
      r2 = r4 + r1
      r3 = r2 + r1
      r1 = r4 + r3
      return r3 + r1

Q.6.  

      available: r1,r2,r3

      a  b  c  d  e  f
      |1
      |  |2
      |     |2->spill
      |     |  |3
      |     |  |  |2
      |     |  |     |2
      |     |  |     |
      |     |        |
            |        |

      r1 = 1
      r2 = 10
      c = 8 + r2
      r3 = r1 + c
      r2 = r1 + r3
      r2 = c + r2
      r3 = r1 + r2
      c = r3 + r2
      r2 = r1 + c
      return c + r2


      available: s1,s2

      a  b  c  d  e  f
      |1->spill
      |  |2
      |     |2->spill
      |     |  |2
      |     |  |  |1
      |     |  |     |1
      |     |  |     |
      |     |        |
            |        |

      a = 1
      s2 = 10
      c = 8 + s2
      s2 = a + c
      s1 = a + s2
      s1 = c + s1
      s2 = a + s1
      c = s2 + s1
      s1 = a + c
      return c + s1