Register allocation and assignment in Compiler Design - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Purpose of Register Allocation

What is the main purpose of register allocation in a compiler?

A To assign variables to a limited number of CPU registers to optimize execution speed

B To convert high-level code into machine code instructions

C To manage memory allocation for dynamic data structures

D To optimize disk storage usage for compiled programs

💡 Hint

Think about how using CPU registers affects program speed.

Register allocation assigns variables to CPU registers, which are faster than memory, improving execution speed.

📋 Factual

intermediate

Register Assignment Strategies

Which of the following is a common strategy used in register assignment?

A Bubble sort

B Binary search

C Depth-first search

D Graph coloring

💡 Hint

It involves coloring nodes to avoid conflicts.

Graph coloring is used to assign registers by modeling conflicts as edges and coloring nodes to avoid register overlap.

🔍 Analysis

advanced

Impact of Register Spilling

What is the impact of register spilling on program performance?

A It causes syntax errors during compilation

B It improves performance by freeing up registers

C It decreases performance because spilled variables are stored in slower memory

D It has no effect on performance

💡 Hint

Consider the speed difference between registers and memory.

Register spilling stores variables in memory when registers are full, slowing down access and reducing performance.

❓ Comparison

advanced

Static vs Dynamic Register Allocation

Which statement correctly compares static and dynamic register allocation?

A Static allocation assigns registers at runtime; dynamic allocation assigns at compile time

B Static allocation assigns registers at compile time; dynamic allocation assigns at runtime

C Both assign registers only at runtime

D Both assign registers only at compile time

💡 Hint

Think about when the decisions are made.

Static allocation fixes register assignments during compilation, while dynamic allocation decides during program execution.

❓ Reasoning

expert

Register Allocation Graph Coloring Challenge

Given a register interference graph with nodes A, B, C, D where edges are: A-B, A-C, B-C, C-D, what is the minimum number of registers needed to allocate without conflicts?

A 3

B 2

C 4

D 1

💡 Hint

Consider the largest clique in the graph.

The largest clique is A-B-C, which requires 3 different colors (registers) to avoid conflicts.