Translate the following statements into a quadruple sequence:

while (a<b and c>d) do

   if (e<f) then

           x := y + z;

else

          x := y - z;

Given the following program: 

  #include <stdio.h>

  Int i=0;

  Void swap(int x, int y)

  { x= x+y;

   y=x-y;

   x=x-y；

  }

  main()

  { int a[3]= {2, 0, 1};

   swap(i, a[i]);

   printf(“%d %d %d %d \n”,i ,a[0], a[1], a[2]);

   return 0;

  }

Please show the output of the above program using four parameter passing methods (pass by value, pass by reference, pass by value-result, pass by name) respectively.

The IR code generation can be performed during a parse.  Please complete the C program of the action1、action2、action3、action4、action5、action6  in the YACC file of the following grammar.  

Grammar: 

stmt → while-stmt | break | other

while-stmt → while ( exp )  stmt

exp → true | false

the IR codes as following :                      the three-address codes as following: 

 label L1                                                      read x             (rd,x _,_ )

<code to evaluate exp to t1>                    if_false,t1,L1   ( if_f, t1,L1,_)

if_false t1 goto L2                                      label L1           (lab,L1,_,_)

<code for stmt>                                        goto L1            (go,L1,_,_)

goto L1                                                       x=t3                (asn,t3, x ,_ )

label L2 

YACC:

  while-stmt :  { action1 }  while  ( exp )  { action2 }  stmt

              {action3 } 

exp :  true   { action4 } 

| false  { action5 }

  stmt:  while-stmt 

| break  {  action6  } 

| other

Consider the CFG of number with a one-character suffix o (for octal) or d (for decimal).

based-num → num basechar 

basechar → o | d

num → num digit | digit

digit → 0|1|2|3|4|5|6|7|8|9

In this case, we need two attributes, base (for indicating octal or decimal) and val (for value of the number).

(1) Rewrite the grammar so that the computation of the attribute base does not depend on parent nodes.

(2) Given the number “789o”, show the dependency of attribute computation on its parsing tree of the above modified CFG.

Given a program as follow: 

  int x=3;

  void g(int);

  void f(int n)

  {  

      static int x =1;

      g(n);

      x--;

  }

  void g(int m)

  { 

     int y = m-1;

     If (y > 0)

     { f(y);

       x--;

       g(y);

      }

  }

  main()

  { 

      g(x);

      return 0;

  }

Please draw the runtime environment of the above program at the point just before the second call to g.