Conversation with Merlin [email protected] · Sat Nov 25 2023

Show/Draw the stack with all activation record instances, including the dynamic chain, when execution reaches the position ("Draw at this point") indicated in the following skeletal program.

void fun1() { float a; . . . } void fun2() { int b, c; . . . } void fun3() { float d; . . . Draw at this point } void main() { char e, f, g; . . . }

The calling sequence for this program for execution to reach fun3 is main calls fun2 fun2 calls fun1 fun1 calls fun1 fun1 calls fun3

To draw the stack with all activation record instances at the indicated position, we can trace the calling sequence and track the activation records for each function. We'll start with the main function and follow the calling sequence until we reach the position indicated in fun3.

  1. main function:

    • Activation Record for main:
      • Variables: e, f, g

  2. main calls fun2:

    • Activation Record for fun2:
      • Variables: b, c

  3. fun2 calls fun1:

    • Activation Record for fun1:
      • Variables: a

  4. fun1 calls fun1 (this recursion is to be a mistake, if it should be calling fun3, please let me know):

    • Activation Record for additional fun1 call:
      • Variables: a

  5. fun1 calls fun3 (at the indicated position):

    • Activation Record for fun3:
      • Variables: d

The dynamic chain tracks the order of function calls. It shows the sequence of activation records that leads from the current execution point to the activation record of the original call to the current function.

Assuming that the function call sequence is correct and without errors, the stack with all activation record instances, including the dynamic chain at the indicated point would be:

Stack:
-------
| fun3 |  <-- current activation record
-------
| fun1 |  <-- previous activation record
-------
| fun2 |  <-- previous activation record
-------
| main |  <-- bottom of the stack
-------
Dynamic Chain: main -> fun2 -> fun1 -> fun3