Iterative data flow frameworks in Compiler Design - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the data flow analysis iteration.

Compiler Design

worklist = [1]

Drag options to blanks, or click blank then click option'

Aempty set

Bsingle start node

Call program nodes

Drandom nodes

Attempts:

3 left

💡 Hint

Common Mistakes

Initializing with an empty set causes no analysis to run.

Starting with random nodes may miss some nodes.

In iterative data flow frameworks, the worklist is usually initialized with all program nodes to ensure all nodes are analyzed.

2fill in blank

medium

Complete the code to update the data flow information for a node.

Compiler Design

new_info = meet([1])

Drag options to blanks, or click blank then click option'

Aall successors' data

Ball predecessors' data

Conly current node data

Drandom node data

Attempts:

3 left

💡 Hint

Common Mistakes

Using successors' data instead of predecessors' data.

Ignoring the meet operation and using only current node data.

The meet operation combines data flow information from all predecessors of a node to update its state.

3fill in blank

hard

Fix the error in the iteration condition to continue until no changes occur.

Compiler Design

while [1]:

Drag options to blanks, or click blank then click option'

Achanges detected

Bworklist is not empty

Citeration count < max

Dnodes remain unvisited

Attempts:

3 left

💡 Hint

Common Mistakes

Using worklist emptiness alone may stop too early.

Relying on iteration count can miss convergence.

The iteration continues while changes are detected in data flow information, ensuring convergence.

4fill in blank

hard

Fill both blanks to correctly update the worklist after processing a node.

Compiler Design

if data_changed:
    worklist.[1](successors)
else:
    worklist.[2](node)

Drag options to blanks, or click blank then click option'

Aextend

Bremove

Cappend

Dpop

Attempts:

3 left

💡 Hint

Common Mistakes

Using append instead of extend adds successors as a single element.

Using pop removes the wrong element.

If data changes, successors are added to the worklist using extend. Otherwise, the current node is removed using remove.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps nodes to their data if data is valid.

Compiler Design

result = [1]: [2] for [3] in nodes if is_valid([2])

Drag options to blanks, or click blank then click option'

Anode

Bdata[node]

Ddata

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'data' as the key instead of the node.

Using 'node' as the value instead of data[node].

The comprehension maps each node to its data[node] if the data is valid. The variable iterating over nodes is node.