Suppose that a RISC machine uses 5 register windows. a) How deep can the procedu

Question

Suppose that a RISC machine uses 5 register windows.

a) How deep can the procedure calls go before registers must be saved in memory?

b) Suppose 2 more calls are made ater the maximum value from part a) is reached. How many register windows must be saved to memory as a result?

c) Now suppose that the most recently called procedure retrns. Explain what occurs.

d) Now suppose one more procedure is called. How many register windows need to be stored in memory?

If answered in under 1 hour, I will add 100 points to best answer.

Explanation / Answer

a. Due to the circular nature of the windows, the output registers of the last window are shared as the input registers of the first window. Therefore, only four procedures could be active without saving registers in memory.

b. The input registers from the first window, on the first call (due to wrap around), and the input, local, and output registers on the second call.

c. The previously saved registers are restored.

d. Again, the input, local, and output values would need to be saved.

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