Activation records and call stack in Compiler Design - Mini Project: Build & Apply

Understanding Activation Records and Call Stack

📖 Scenario: Imagine you are learning how a computer keeps track of function calls when running a program. Each time a function is called, the computer creates a special box to store information about that call. This box is called an activation record. All these boxes are stacked on top of each other in a structure called the call stack.In this project, you will build a simple representation of activation records and the call stack to understand how function calls are managed.

🎯 Goal: You will create a simple model of activation records as dictionaries and manage them in a list to simulate the call stack. This will help you see how information about function calls is stored and removed as functions start and finish.

📋 What You'll Learn

Create an activation record as a dictionary with specific keys and values.

Create a call stack as a list to hold activation records.

Add activation records to the call stack to simulate function calls.

Remove activation records from the call stack to simulate function returns.

💡 Why This Matters

🌍 Real World

Understanding activation records and the call stack helps in debugging programs and understanding how programming languages manage function calls internally.

💼 Career

This knowledge is important for software developers, compiler engineers, and anyone working with low-level programming or debugging complex software.

1

Create the first activation record

Create a dictionary called activation_record_main with these exact entries: 'function_name': 'main', 'return_address': 0, and 'local_variables': {'x': 10, 'y': 20}.

Compiler Design

# Create the activation_record_main dictionary with specified keys and values
# Your code here

Need a hint?

Use curly braces {} to create a dictionary. Include the keys exactly as shown with their values.

2

Create the call stack list

Create a list called call_stack and add the activation_record_main dictionary as its first element.

Compiler Design

activation_record_main = {
    'function_name': 'main',
    'return_address': 0,
    'local_variables': {'x': 10, 'y': 20}
}
# Create the call_stack list and add activation_record_main
# Your code here

Need a hint?

Create a list using square brackets [] and put activation_record_main inside it.

3

Add a new activation record for a function call

Create a dictionary called activation_record_func with these entries: 'function_name': 'compute', 'return_address': 5, and 'local_variables': {'a': 3, 'b': 4}. Then add activation_record_func to the end of the call_stack list.

Compiler Design

activation_record_main = {
    'function_name': 'main',
    'return_address': 0,
    'local_variables': {'x': 10, 'y': 20}
}

call_stack = [activation_record_main]
# Create activation_record_func dictionary and add it to call_stack
# Your code here

Need a hint?

Create the dictionary like in step 1, then use the append() method to add it to the list.

4

Simulate function return by removing the top activation record

Remove the last activation record from the call_stack list to simulate returning from the compute function.

Compiler Design

activation_record_main = {
    'function_name': 'main',
    'return_address': 0,
    'local_variables': {'x': 10, 'y': 20}
}

call_stack = [activation_record_main]

activation_record_func = {
    'function_name': 'compute',
    'return_address': 5,
    'local_variables': {'a': 3, 'b': 4}
}

call_stack.append(activation_record_func)
# Remove the last activation record from call_stack
# Your code here

Need a hint?

Use the pop() method on the list to remove the last item.