Instruction selection and scheduling(MCQs)

Instruction Selection What is the primary goal of instruction selection in a compiler? A) To choose the most efficient machine instructions for a given intermediate representation B) To generate assembly code C) To optimize memory allocation D) To handle function calls Answer: A) To choose the most efficient machine instructions for a given intermediate representation In the context of instruction selection, what is an “instruction pattern”? A) A template used to match intermediate representations with target machine instructions B) A method for generating intermediate code C) A strategy for memory management D) A technique for optimizing loops Answer: A) A template used to match intermediate representations with target machine instructions Which of the following techniques is used to improve the effectiveness of instruction selection? A) Instruction pattern matching B) Register allocation C) Data flow analysis D) Control flow analysis Answer: A) Instruction pattern matching What is a “cost model” in instruction selection? A) A method to estimate the performance impact of different instruction sequences B) A technique to generate intermediate code C) A strategy to manage memory allocation D) A tool for debugging Answer: A) A method to estimate the performance impact of different instruction sequences What does “target-independent code generation” mean in instruction selection? A) Generating code that can be adapted to different target architectures B) Generating code specific to a single target architecture C) Optimizing memory usage D) Handling function calls Answer: A) Generating code that can be adapted to different target architectures Instruction Scheduling What is the primary purpose of instruction scheduling? A) To arrange instructions in an optimal order to improve performance and minimize delays B) To generate intermediate code C) To handle function calls D) To manage memory allocation Answer: A) To arrange instructions in an optimal order to improve performance and minimize delays What is “static instruction scheduling”? A) Scheduling instructions based on compile-time information without considering runtime behavior B) Scheduling instructions at runtime based on actual execution C) Managing memory allocation D) Handling function calls Answer: A) Scheduling instructions based on compile-time information without considering runtime behavior Which of the following is a common technique used in static instruction scheduling? A) List scheduling B) Register allocation C) Data flow analysis D) Code generation Answer: A) List scheduling What is “dynamic instruction scheduling”? A) Scheduling instructions at runtime based on actual execution and runtime data B) Scheduling instructions based on compile-time information C) Managing memory allocation D) Generating intermediate code Answer: A) Scheduling instructions at runtime based on actual execution and runtime data Which scheduling technique involves reordering instructions to avoid pipeline stalls? A) Instruction-level parallelism B) Loop unrolling C) Dependency scheduling D) Instruction fusion Answer: C) Dependency scheduling Techniques and Algorithms What is “list scheduling” in the context of instruction scheduling? A) A technique where instructions are scheduled based on a list of their dependencies and priorities B) A method for generating intermediate code C) A technique for memory management D) A strategy for function calls Answer: A) A technique where instructions are scheduled based on a list of their dependencies and priorities What is the purpose of “software pipelining” in instruction scheduling? A) To overlap the execution of loop iterations to improve performance B) To manage memory allocation C) To optimize function calls D) To generate intermediate code Answer: A) To overlap the execution of loop iterations to improve performance In instruction scheduling, what does “loop unrolling” refer to? A) A technique to increase instruction-level parallelism by expanding the loop body B) A method for managing memory allocation C) A technique to handle function calls D) A strategy for code generation Answer: A) A technique to increase instruction-level parallelism by expanding the loop body What is “VLIW” in instruction scheduling? A) Very Long Instruction Word, a type of architecture that allows multiple instructions to be executed simultaneously B) Variable Length Instruction Word C) Virtual Long Instruction Word D) Vector Length Instruction Word Answer: A) Very Long Instruction Word, a type of architecture that allows multiple instructions to be executed simultaneously What is “out-of-order execution” in the context of instruction scheduling? A) Executing instructions based on their availability rather than their original program order to improve performance B) Executing instructions strictly in their original order C) Managing memory allocation D) Handling function calls Answer: A) Executing instructions based on their availability rather than their original program order to improve performance Performance Considerations What is “instruction-level parallelism”? A) The degree to which multiple instructions can be executed simultaneously B) The degree to which functions can be executed simultaneously C) The degree to which memory can be accessed simultaneously D) The degree to which variables can be accessed simultaneously Answer: A) The degree to which multiple instructions can be executed simultaneously What is the main benefit of “speculative execution” in instruction scheduling? A) To improve performance by executing instructions before it is certain that they are needed B) To manage memory allocation more efficiently C) To handle function calls D) To generate intermediate code Answer: A) To improve performance by executing instructions before it is certain that they are needed How does “register renaming” contribute to instruction scheduling? A) By reducing false dependencies and enabling more parallelism in instruction execution B) By increasing memory access times C) By simplifying code generation D) By managing function calls Answer: A) By reducing false dependencies and enabling more parallelism in instruction execution What is the impact of “cache coherence” on instruction scheduling? A) Ensuring that changes to data in caches are consistent across different processors or cores, which affects instruction scheduling and performance B) Reducing the number of instructions executed C) Simplifying memory allocation D) Managing function calls Answer: A) Ensuring that changes to data in caches are consistent across different processors or cores, which affects instruction scheduling and performance What is “branch prediction” used for in instruction scheduling? A) To predict the outcome of conditional branches and reduce pipeline stalls B) To manage memory allocation C) To handle function calls D) To generate intermediate code Answer: A) To predict the outcome of conditional branches and reduce pipeline stalls Optimization Techniques What is “trace scheduling”? A) A technique to schedule instructions along frequently executed paths (traces) to improve performance B) A method for managing memory allocation C) A technique for generating intermediate code D) A strategy for handling function calls Answer: A) A technique to schedule instructions along frequently executed paths (traces) to improve performance What does “dynamic scheduling” involve? A) Scheduling instructions at runtime based on real-time execution information B) Scheduling instructions at compile time C) Managing memory allocation D) Generating intermediate code Answer: A) Scheduling instructions at runtime based on real-time execution information What is “loop fusion” in instruction scheduling? A) Combining multiple loops into a single loop to improve performance by reducing loop overhead B) Separating loops to increase parallelism C) Reducing the number of instructions executed D) Handling function calls Answer: A) Combining multiple loops into a single loop to improve performance by reducing loop overhead What is “loop splitting” used for? A) To break a loop into smaller loops to improve instruction scheduling and reduce register pressure B) To combine multiple loops C) To manage memory allocation D) To handle function calls Answer: A) To break a loop into smaller loops to improve instruction scheduling and reduce register pressure What is “instruction fusion”? A) Combining multiple instructions into a single instruction to reduce the number of instructions and improve performance B) Splitting instructions into smaller units C) Managing memory allocation more efficiently D) Handling function calls Answer: A) Combining multiple instructions into a single instruction to reduce the number of instructions and improve performance Compiler Techniques What is “instruction scheduling with register constraints”? A) Scheduling instructions while considering constraints imposed by the availability of registers B) Scheduling instructions without considering registers C) Generating intermediate code D) Managing memory allocation Answer: A) Scheduling instructions while considering constraints imposed by the availability of registers How does “peephole optimization” relate to instruction scheduling? A) It involves making small local improvements to instruction sequences to enhance performance B) It manages memory allocation C) It handles function calls D) It generates intermediate code Answer: A) It involves making small local improvements to instruction sequences to enhance performance What is the role of “post-pass optimization” in instruction scheduling? A) To perform optimizations after the initial instruction scheduling to further enhance performance B) To handle memory allocation C) To generate intermediate code D) To manage function calls Answer: A) To perform optimizations after the initial instruction scheduling to further enhance performance What is “function-level scheduling”? A) Scheduling instructions at the level of entire functions to improve performance B) Scheduling instructions within a single loop C) Generating intermediate code D) Managing memory allocation Answer: A) Scheduling instructions at the level of entire functions to improve performance What is “software pipelining” used for in the context of loops? A) To overlap the execution of loop iterations to improve performance B) To unroll loops C) To manage memory allocation D) To handle function calls Answer: A) To overlap the execution of loop iterations to improve performance Advanced Concepts What is “superscalar architecture”? A) An architecture that allows multiple instructions to be executed simultaneously in a single clock cycle B) An architecture that executes instructions sequentially C) An architecture focused on managing memory allocation D) An architecture for handling function calls Answer: A) An architecture that allows multiple instructions to be executed simultaneously in a single clock cycle What is “out-of-order execution”? A) A technique that allows instructions to be executed as resources are available, rather than strictly in the order they appear B) Executing instructions in their original order C) Managing memory allocation D) Handling function calls Answer: A) A technique that allows instructions to be executed as resources are available, rather than strictly in the order they appear What is “branch prediction” used for in instruction scheduling? A) To guess the direction of a branch to reduce pipeline stalls B) To handle memory allocation C) To manage function calls D) To generate intermediate code Answer: A) To guess the direction of a branch to reduce pipeline stalls What does “loop unrolling” do? A) It increases instruction-level parallelism by expanding the loop body B) It reduces the number of instructions executed C) It handles function calls D) It manages memory allocation Answer: A) It increases instruction-level parallelism by expanding the loop body What is “loop interchange” in instruction scheduling? A) Changing the order of nested loops to improve performance by improving cache utilization and parallelism B) Combining multiple loops C) Reducing the number of instructions executed D) Handling function calls Answer: A) Changing the order of nested loops to improve performance by improving cache utilization and parallelism Miscellaneous What is the main advantage of “instruction-level parallelism”? A) It allows multiple instructions to be executed simultaneously, improving performance B) It increases memory usage C) It reduces the number of function calls D) It simplifies code generation Answer: A) It allows multiple instructions to be executed simultaneously, improving performance What is “data dependence analysis” used for in instruction scheduling? A) To determine dependencies between instructions to ensure correct execution order B) To manage memory allocation C) To handle function calls D) To generate intermediate code Answer: A) To determine dependencies between instructions to ensure correct execution order How does “loop fusion” affect instruction scheduling? A) It can improve performance by reducing loop overhead and increasing parallelism B) It reduces the number of instructions executed C) It manages memory allocation D) It handles function calls Answer: A) It can improve performance by reducing loop overhead and increasing parallelism What is “register renaming” used to address in instruction scheduling? A) It addresses false dependencies between instructions to improve parallelism B) It simplifies memory management C) It handles function calls D) It generates intermediate code Answer: A) It addresses false dependencies between instructions to improve parallelism What is the goal of “out-of-order execution”? A) To improve performance by executing instructions as soon as their operands are available, regardless of their original order B) To ensure instructions are executed in their original order C) To manage memory allocation D) To handle function calls Answer: A) To improve performance by executing instructions as soon as their operands are available, regardless of their original order Advanced Scheduling Techniques What is “trace scheduling”? A) Scheduling frequently executed paths (traces) in the code to improve performance B) Managing memory allocation C) Generating intermediate code D) Handling function calls Answer: A) Scheduling frequently executed paths (traces) in the code to improve performance What does “loop blocking” aim to achieve? A) It aims to improve cache performance by dividing loops into smaller blocks B) It reduces the number of instructions executed C) It simplifies function calls D) It manages memory allocation Answer: A) It aims to improve cache performance by dividing loops into smaller blocks What is the purpose of “software pipelining”? A) To overlap the execution of loop iterations to increase performance B) To manage memory allocation more efficiently C) To simplify function calls D) To generate intermediate code Answer: A) To overlap the execution of loop iterations to increase performance What does “register allocation” involve in the context of instruction scheduling? A) Allocating a limited number of registers to hold variables and intermediate results to minimize memory access B) Scheduling instructions to improve performance C) Managing function calls D) Generating intermediate code Answer: A) Allocating a limited number of registers to hold variables and intermediate results to minimize memory access What is “instruction fusion”? A) Combining multiple instructions into a single instruction to reduce the number of instructions and improve performance B) Splitting instructions into smaller units C) Managing memory allocation D) Handling function calls Answer: A) Combining multiple instructions into a single instruction to reduce the number of instructions and improve performance Performance and Optimization What is “pipeline stall”? A) A delay that occurs in a pipeline when the next instruction cannot be executed due to dependencies or resource constraints B) A technique to optimize function calls C) A method for managing memory allocation D) A strategy for generating intermediate code Answer: A) A delay that occurs in a pipeline when the next instruction cannot be executed due to dependencies or resource constraints What is “speculative execution”? A) Executing instructions before it is certain they are needed to improve performance B) Managing memory allocation C) Handling function calls D) Generating intermediate code Answer: A) Executing instructions before it is certain they are needed to improve performance What does “loop invariant code motion” aim to achieve? A) Moving computations that do not change across loop iterations outside of the loop to improve performance B) Reducing the number of function calls C) Simplifying memory management D) Handling function calls Answer: A) Moving computations that do not change across loop iterations outside of the loop to improve performance How does “data dependence” affect instruction scheduling? A) It determines the order in which instructions must be executed to ensure correct results B) It simplifies memory management C) It reduces the number of instructions executed D) It handles function calls Answer: A) It determines the order in which instructions must be executed to ensure correct results What is “instruction selection” in the context of code generation? A) The process of choosing the most efficient machine instructions for a given intermediate representation B) The process of generating intermediate code C) The process of managing memory allocation D) The process of handling function calls Answer: A) The process of choosing the most efficient machine instructions for a given intermediate representation