Basic blocks and flow graphs in Compiler Design - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to identify the start of a basic block in a flow graph.

Compiler Design

if instruction.is_leader():
    start_block = [1]

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

Ainstruction

BFalse

CNone

DTrue

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning a boolean value instead of the instruction.

Using None which does not represent a block start.

The start of a basic block is marked by a leader instruction, so we assign the current instruction as the start.

2fill in blank

medium

Complete the code to create edges between basic blocks in a flow graph.

Compiler Design

for block in basic_blocks:
    for successor in block.[1]:
        graph.add_edge(block, successor)

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

Apredecessors

Bleaders

Csuccessors

Dinstructions

Attempts:

3 left

💡 Hint

Common Mistakes

Using predecessors which point backward.

Using leaders or instructions which are not related to edges.

Edges in a flow graph connect a block to its successors, representing possible next blocks in execution.

3fill in blank

hard

Fix the error in the code that checks if a block ends with a jump instruction.

Compiler Design

if block.instructions[-1].[1] == 'jump':
    handle_jump(block)

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

Aopcode

Boperand

Clabel

Daddress

Attempts:

3 left

💡 Hint

Common Mistakes

Checking operand or label which are not operation types.

Using address which is unrelated here.

The opcode field of an instruction tells what operation it performs, such as 'jump'.

4fill in blank

hard

Fill both blanks to build a dictionary mapping block leaders to their successors.

Compiler Design

block_map = {leader: block[1] for leader, block in blocks.items() if block[2]

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

A.successors

B.predecessors

Cis not None

Dis None

Attempts:

3 left

💡 Hint

Common Mistakes

Using predecessors instead of successors.

Checking if block is None instead of not None.

We map each leader to its block's successors only if the block exists (is not None).

5fill in blank

hard

Fill all three blanks to create a flow graph with nodes and edges from basic blocks.

Compiler Design

flow_graph = FlowGraph()
for block in [1]:
    flow_graph.add_node(block.[2])
    for succ in block.[3]:
        flow_graph.add_edge(block.[2], succ.[2])

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

Abasic_blocks

Bleader

Csuccessors

Dinstructions

Attempts:

3 left

💡 Hint

Common Mistakes

Using instructions instead of basic blocks.

Using instructions or predecessors instead of successors.

Using block instead of leader for node identity.

We iterate over basic_blocks, add nodes using each block's leader, and add edges to their successors.