Final Exam, Fall 2006
=====================

Q.3:  this
      a
      ra
      x
      temporaries
      saved callee-save registers


Q.4   y=0
      | y
      >
      a=1
      | y,a
      >
      if y<0 then   <-------
      |a    |y             |y,a
      |     >              |
      |    a=y             |
      |     |a             |
      >     >              |
      i=a+2                |
      |a,i                 |
      >                    |
      y=i+1                |
      |y,a,i               |
      >                    |
      if i<100 then -------|
      |i
      >
      return

Q.5   For the liveness analysis in the book to make sense,
      we must recognize that the statement (2nd to last)
      b=d+e is dead.  When that statement is dead, also
      e=a+c is dead.  The resulting program has an 
      interference graph which can be colored with 3 colors.

Q.6   Linear scan with 3 registers does not spill;
      linear scan with 2 register spills one variable (d).