NPTEL Advanced Computer Architecture Week 5 Assignment Answers 2025
1. The act of dynamically nullifying or cancelling an instruction in the pipeline is known as instruction _____________.
- Squashing
- Dropping
- Retiring
- Broadcasting
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2. Which of the following statements are correct regarding the non-selective replay mechanism?
S1: The mechanism decrements the timer associated with an operand only if it is accessed.
S2: If the timers of all operands of an instruction become zero, then we can conclude that this instruction will not be squashed.
- S1 is true, S2 is false
- S1 is false, S2 is true
- Both S1 and S2 are true
- Both S1 and S2 are false
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3. The ____________ replay mechanism uses the _____________ to rescue orphan instructions.
- Non-selective, Kill wire
- Delayed selective, Poison bit
- Non-selective, Poison bit
- Delayed selective, Completion bus
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4. Consider the statements and select the most appropriate option.
S1: The poison bit propagates when we read a value either from the register file or the bypass network.
S2: The poison bit is propagated while broadcasting tags or waking up instructions.
- S1 is true, S2 is false
- S1 is false, S2 is true
- Both S1 and S2 are true
- Both S1 and S2 are false
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5. In the__________ based design we read the register values after issuing the instruction. In the_____________ based design values may reside in multiple locations.
- physical register file, physical register file
- architectural register file, architectural register file
- physical register file, architectural register file
- architectural register file, physical register file
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6. Which of the following statements are true regarding the physical register file-based design?
- It is fast and efficient.
- The state recovery is complex.
- The physical register management is onerous
- All the options.
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7. Consider the following code snippet:
int a = 10 + 6;
int b = a * a;
Which of the following compiler optimizations are possible here?
- Common subexpression elimination
- Strength reduction
- Constant folding
- None of the options.
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8. Consider the following code snippet:
int c = (a+b) * 8;
int d = (a+b) * (a+b);
Which of the following is the optimized version of the code?
- int t1 = a+b;
int c = t1 * 8;
int d = t1 * t1; - int t1 = a+b;
int c = t1 << 3;
int d = t1 * t1; - int c = (a+b) << 3;
int t1 = a + b;
int d = t1 * t1; - None of the options.
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9. A variable or property that does not change across the iterations of a loop is known as a _________.
- loop invariant
- loop constant
- loop point
- loop variable
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10. Which of the following statements are correct regarding the compiler-based optimizations?
- It reduces the code size.
- It increases the ILP.
- It reduces the complexity of instructions.
- All the options.
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