Compiler Optimizations for Parallelism MCQs

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1. What is the main goal of compiler optimizations for parallelism?
(A) Reduce source code size
(B) Improve execution speed by exploiting multiple processors
(C) Simplify debugging
(D) Increase memory usage

2. Which type of parallelism involves executing independent instructions simultaneously?
(A) Instruction-level parallelism (ILP)
(B) Data-level parallelism (DLP)
(C) Thread-level parallelism (TLP)
(D) Process-level parallelism (PLP)

3. Loop unrolling is an optimization that:
(A) Removes all loops
(B) Converts loops into recursive calls
(C) Reduces loop iterations for better instruction scheduling
(D) Increases memory allocation

4. What is vectorization in parallelism optimization?
(A) Using recursion instead of loops
(B) Serializing code execution
(C) Allocating memory in a vector structure
(D) Transforming scalar operations into vector operations for SIMD execution

5. Which of the following is an example of data-level parallelism?
(A) Running a single instruction on multiple processors
(B) Executing multiple threads processing different elements of an array simultaneously
(C) Scheduling independent instructions
(D) Using a single-core processor

6. Dependency analysis in compiler optimization is used to:
(A) Detect and resolve memory leaks
(B) Identify data dependencies to safely parallelize loops and instructions
(C) Reduce compilation time
(D) Simplify syntax checking

7. What is a critical section in parallel programming?
(A) A loop that cannot be executed
(B) A part of code that must be executed by only one thread at a time to prevent conflicts
(C) A function that is always optimized
(D) A dead code block

8. Which compiler optimization technique improves parallel execution by reordering instructions?
(A) Dead code elimination
(B) Loop fusion
(C) Instruction scheduling
(D) Constant propagation

9. Loop splitting (loop fission) is used to:
(A) Divide a loop into smaller loops to enable parallel execution
(B) Merge multiple loops into one
(C) Convert loops into conditional statements
(D) Eliminate unnecessary loops

10. What is thread-level parallelism (TLP)?
(A) Running multiple instructions of a single thread simultaneously
(B) Parallelizing instructions within a loop
(C) Using a single thread for vector operations
(D) Executing multiple threads concurrently on different processors or cores

11. Loop fusion is an optimization technique that:
(A) Combines adjacent loops with the same bounds to reduce overhead
(B) Splits a loop into smaller chunks
(C) Converts loops into recursive functions
(D) Eliminates loops entirely

12. Which of the following is a potential challenge of parallelism optimizations?
(A) Increased instruction-level parallelism
(B) Reduced compilation time
(C) Faster execution
(D) Data hazards and race conditions

13. What is SIMD in parallel computing?
(A) Single Instruction, Multiple Devices
(B) Single Instruction, Multiple Data
(C) Serial Instruction, Multiple Data
(D) Sequential Instruction, Multiple Data

14. What is a reduction operation in parallel loops?
(A) A loop that decreases its iteration count automatically
(B) Combining results from multiple threads, such as sum or max
(C) Removing loops with minimal execution time
(D) A function that optimizes memory

15. Automatic parallelization by a compiler refers to:
(A) Manually adding threads in source code
(B) Compiler identifying opportunities to execute code in parallel without programmer intervention
(C) Ignoring data dependencies
(D) Running code sequentially for safety

16. What is loop interchange in parallel compiler optimization?
(A) Removing loops entirely
(B) Converting a loop into a function
(C) Swapping the order of nested loops to improve cache utilization and parallelism
(D) Merging two unrelated loops

17. What is false sharing in parallel programs?
(A) Threads accessing different memory locations
(B) Multiple threads accessing different variables in the same cache line, causing performance degradation
(C) Threads sharing only read-only data
(D) Threads executing independently without conflict

18. Task parallelism involves:
(A) Sequential task execution
(B) Parallel execution of instructions in a single thread
(C) Parallel execution of independent tasks or functions
(D) Using SIMD instructions for vectors

19. What is a dependency chain?
(A) Sequence of instructions where each depends on the result of the previous
(B) Sequence of instructions that can be executed independently
(C) Memory block used for caching
(D) Parallel thread pool

20. Which compiler optimization improves parallelism by minimizing idle CPU time?
(A) Speculative execution
(B) Loop unrolling
(C) Dead code elimination
(D) Constant folding

21. What is task scheduling in parallel computing?
(A) Allocating tasks to threads or processors to balance load and improve performance
(B) Assigning instructions to CPU pipelines
(C) Determining loop bounds
(D) Eliminating dead code

22. OpenMP is primarily used for:
(A) Instruction-level parallelism
(B) Simplifying parallel programming with compiler directives in C/C++/Fortran
(C) GPU programming only
(D) Single-threaded optimizations

23. What is the main advantage of loop tiling (blocking) in parallelism?
(A) Improves cache locality and performance in nested loops
(B) Reduces loop iteration counts
(C) Eliminates the need for threading
(D) Converts loops into functions

24. Software pipelining in parallelism is used to:
(A) Pipeline instructions of a loop to execute multiple iterations concurrently
(B) Merge multiple loops
(C) Unroll loops completely
(D) Avoid multi-threading

25. What is speculative parallelization?
(A) Only unrolling loops
(B) Executing loops sequentially
(C) Avoiding any parallel execution
(D) Executing code in parallel assuming dependencies do not exist, rolling back if assumptions fail

26. Which of the following is a benefit of compiler-guided parallelization?
(A) Reduced memory footprint
(B) Avoiding synchronization issues
(C) Automatic identification of parallelizable code
(D) Increased sequential execution

27. What is the role of a dependency graph in parallel compiler optimization?
(A) Illustrates memory usage
(B) Detects syntax errors
(C) Shows CPU utilization
(D) Represents data dependencies between instructions to determine safe parallel execution

28. What does load balancing mean in parallel computing?
(A) Assigning all work to a single processor
(B) Avoiding memory allocation
(C) Distributing tasks evenly across processors to maximize performance
(D) Reducing compiler complexity

29. Privatization in parallel loops refers to:
(A) Sharing all variables across threads
(B) Combining loops into one
(C) Ignoring data dependencies
(D) Creating private copies of variables for each thread to avoid conflicts

30. Which is a major challenge in automatic parallelization by compilers?
(A) Identifying independent computations
(B) Minimizing communication overhead
(C) All of the above
(D) Handling complex data dependencies

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