Code generation for RISC and CISC architectures(MCQs)

Basics of RISC and CISC Architectures What is a characteristic of RISC architecture? A) Small and simple instruction set B) Complex and variable-length instructions C) Support for multiple addressing modes D) Emphasis on microcode Answer: A) Small and simple instruction set Which architecture typically has more complex instructions, RISC or CISC? A) CISC B) RISC C) Both are equally complex D) Neither Answer: A) CISC In RISC architecture, what is typically the size of instructions? A) Fixed size B) Variable size C) Dynamic size D) None of the above Answer: A) Fixed size Which architecture often uses multiple clock cycles to execute a single instruction? A) CISC B) RISC C) Both RISC and CISC D) Neither Answer: A) CISC RISC architectures often focus on which aspect to improve performance? A) Pipelining and instruction-level parallelism B) Complex instructions C) Microcode interpretation D) Extensive addressing modes Answer: A) Pipelining and instruction-level parallelism Instruction Set and Complexity Which of the following is true about CISC instructions? A) They can perform multiple operations in a single instruction. B) They are typically simple and uniform. C) They are always fixed in length. D) They focus on single-cycle execution. Answer: A) They can perform multiple operations in a single instruction. What is a typical feature of RISC instructions? A) Simple operations and a uniform instruction format B) Complex addressing modes C) Support for microcode D) Multi-cycle execution for each instruction Answer: A) Simple operations and a uniform instruction format Which architecture uses a larger number of general-purpose registers to minimize memory access? A) RISC B) CISC C) Both D) Neither Answer: A) RISC CISC processors generally require more complex hardware to handle what aspect of instruction execution? A) Instruction decoding and execution B) Register allocation C) Pipelining D) Instruction fetch Answer: A) Instruction decoding and execution RISC architectures are designed to perform operations in how many clock cycles on average? A) One clock cycle B) Two to three clock cycles C) Multiple clock cycles D) Variable number of clock cycles Answer: A) One clock cycle Code Generation Principles Which of the following is a key consideration in code generation for RISC architectures? A) Instruction scheduling for pipelining B) Complex addressing modes C) Variable-length instructions D) Microcode optimization Answer: A) Instruction scheduling for pipelining In CISC architectures, code generation often involves what process? A) Complex instruction decoding B) Simple register allocation C) Uniform instruction format D) Minimal use of addressing modes Answer: A) Complex instruction decoding Which architecture often benefits from code generation techniques that focus on instruction reduction? A) CISC B) RISC C) Both D) Neither Answer: B) RISC In RISC architectures, how is instruction scheduling typically managed? A) By optimizing instruction pipelines B) By using variable-length instructions C) By decoding instructions into multiple micro-operations D) By managing complex addressing modes Answer: A) By optimizing instruction pipelines What is a common goal of code generation for CISC architectures? A) Efficient use of complex instructions B) Minimizing the number of instructions executed C) Reducing the number of registers D) Simplifying instruction formats Answer: A) Efficient use of complex instructions Register Allocation Which architecture typically emphasizes register allocation to minimize memory accesses? A) RISC B) CISC C) Both D) Neither Answer: A) RISC In CISC architectures, how is register allocation often handled? A) By leveraging the complex instructions that use memory directly B) By minimizing the number of registers available C) By using a fixed set of registers D) By focusing on a small number of registers Answer: A) By leveraging the complex instructions that use memory directly RISC architectures often utilize what kind of register model? A) A large number of general-purpose registers B) A small number of special-purpose registers C) A fixed register model with few general-purpose registers D) A register model with no registers Answer: A) A large number of general-purpose registers In CISC code generation, what is a typical approach to handling operations involving memory? A) Using complex instructions that access memory directly B) Performing all operations in registers C) Avoiding memory operations entirely D) Using only immediate values Answer: A) Using complex instructions that access memory directly Which approach to register allocation is more common in RISC architectures? A) Register-to-register operations B) Memory-to-register operations C) Immediate value operations D) Direct memory access Answer: A) Register-to-register operations Addressing Modes What is a common feature of addressing modes in CISC architectures? A) Support for a wide range of addressing modes B) Simple and uniform addressing modes C) Fixed addressing mode D) Limited addressing modes Answer: A) Support for a wide range of addressing modes Which addressing mode is typically emphasized in RISC architectures? A) Register addressing B) Memory indirect addressing C) Immediate addressing D) Complex addressing modes Answer: A) Register addressing In which architecture is the use of complex addressing modes more common? A) CISC B) RISC C) Both D) Neither Answer: A) CISC RISC architectures often rely on which type of addressing mode for most operations? A) Register addressing B) Indexed addressing C) Base-register addressing D) Immediate addressing Answer: A) Register addressing Which addressing mode is used by CISC processors to directly access operands from memory? A) Direct addressing B) Register addressing C) Indirect addressing D) Indexed addressing Answer: A) Direct addressing Instruction Scheduling Which technique is commonly used in RISC architectures to enhance performance through instruction scheduling? A) Out-of-order execution B) Microcode interpretation C) Complex instruction decoding D) Multiple clock cycles for each instruction Answer: A) Out-of-order execution CISC processors often use which technique to handle complex instructions? A) Microcode B) Instruction pipelining C) Register renaming D) Out-of-order execution Answer: A) Microcode What is the primary goal of instruction scheduling in RISC architectures? A) To optimize the execution of instructions by the pipeline B) To decode complex instructions efficiently C) To handle variable-length instructions D) To manage multiple clock cycles Answer: A) To optimize the execution of instructions by the pipeline In CISC architectures, instruction scheduling may be impacted by what factor? A) The complexity of instructions and their variable length B) Fixed instruction length C) Simple instruction formats D) Uniform instruction execution time Answer: A) The complexity of instructions and their variable length What role does instruction pipelining play in RISC architectures? A) It allows overlapping execution of multiple instructions to improve performance B) It simplifies instruction decoding C) It handles complex instructions with multiple micro-operations D) It reduces the number of general-purpose registers Answer: A) It allows overlapping execution of multiple instructions to improve performance Procedure Call Handling In RISC architectures, how is procedure call handling typically managed? A) Using a fixed-size stack frame and simple calling conventions B) Using complex stack frames and variable conventions C) By minimizing the use of procedures D) By using extensive microcode Answer: A) Using a fixed-size stack frame and simple calling conventions Which architecture often requires more complex handling for procedure calls and returns? A) CISC B) RISC C) Both D) Neither Answer: A) CISC What is the common approach for handling procedure calls in CISC architectures? A) Using a variety of calling conventions and complex stack management B) Using fixed-size stack frames and simple conventions C) Minimizing the use of procedures D) Avoiding procedure calls Answer: A) Using a variety of calling conventions and complex stack management What is a typical feature of procedure call handling in RISC architectures? A) Simplicity in stack management and calling conventions B) Complexity in instruction handling C) Use of microcode for calls D) Variable-size stack frames Answer: A) Simplicity in stack management and calling conventions CISC architectures often use what technique for efficient procedure calls? A) Using complex instructions that combine multiple operations B) Fixed-size stack frames C) Out-of-order execution D) Register renaming Answer: A) Using complex instructions that combine multiple operations Advanced Topics What is “loop unrolling” in the context of code generation for RISC architectures? A) Expanding loops to reduce the overhead of loop control and increase performance B) Repeating loops multiple times C) Reducing the number of instructions in a loop D) Simplifying loop instructions Answer: A) Expanding loops to reduce the overhead of loop control and increase performance In CISC architectures, what is a key challenge related to instruction encoding? A) Managing the variable length and complexity of instructions B) Ensuring fixed instruction length C) Simplifying instruction formats D) Minimizing the number of instructions Answer: A) Managing the variable length and complexity of instructions What is “instruction-level parallelism” in RISC architectures? A) The ability to execute multiple instructions simultaneously B) The use of complex instructions C) The handling of variable-length instructions D) The optimization of single instructions Answer: A) The ability to execute multiple instructions simultaneously In CISC architectures, what is a typical approach to optimize instruction execution? A) Using microcode to handle complex instructions B) Using fixed instruction formats C) Simplifying instruction execution D) Reducing the number of registers Answer: A) Using microcode to handle complex instructions Which approach is commonly used in RISC architectures to reduce instruction count and improve performance? A) Code optimization techniques like loop unrolling and instruction scheduling B) Complex addressing modes C) Variable-length instructions D) Extensive use of microcode Answer: A) Code optimization techniques like loop unrolling and instruction scheduling Code Generation Challenges What is a major challenge in code generation for CISC processors? A) Managing the complexity and variety of instructions B) Simplifying instruction execution C) Fixed instruction length D) Uniform instruction format Answer: A) Managing the complexity and variety of instructions In RISC code generation, what is typically minimized to improve performance? A) Memory access and instruction complexity B) Register usage C) Fixed instruction length D) Instruction set size Answer: A) Memory access and instruction complexity What is the role of “instruction scheduling” in optimizing code for RISC processors? A) To improve pipeline utilization and reduce stalls B) To manage complex instruction formats C) To handle variable-length instructions D) To simplify microcode execution Answer: A) To improve pipeline utilization and reduce stalls How does “code motion” optimization benefit CISC architectures? A) By moving code out of frequently executed paths to reduce overhead B) By simplifying instruction encoding C) By increasing instruction length D) By minimizing memory accesses Answer: A) By moving code out of frequently executed paths to reduce overhead What is “register renaming” used for in RISC architectures? A) To eliminate false data dependencies and increase parallelism B) To handle complex instructions C) To manage variable-length instructions D) To simplify instruction formats Answer: A) To eliminate false data dependencies and increase parallelism Miscellaneous Topics Which of the following techniques is often used in RISC architectures to optimize code execution? A) Branch prediction and speculative execution B) Microcode expansion C) Complex instruction formats D) Extensive use of memory operations Answer: A) Branch prediction and speculative execution What is a key advantage of using a fixed instruction length in RISC architectures? A) Simplified instruction decoding and pipelining B) Increased instruction complexity C) Variable-length instruction formats D) Complex addressing modes Answer: A) Simplified instruction decoding and pipelining Which architecture often employs “micro-operations” to break down complex instructions? A) CISC B) RISC C) Both D) Neither Answer: A) CISC What is the typical impact of “instruction fetch” on CISC architectures? A) It can be affected by the complexity and variable length of instructions B) It is simplified due to fixed instruction length C) It does not impact performance D) It reduces the need for pipelining Answer: A) It can be affected by the complexity and variable length of instructions How does “out-of-order execution” benefit RISC processors? A) By allowing instructions to be executed as soon as their operands are ready, increasing overall performance B) By simplifying instruction formats C) By using complex instruction formats D) By minimizing the number of registers Answer: A) By allowing instructions to be executed as soon as their operands are ready, increasing overall performance