Your branch target buffer (and branch history buffer) each have 8 slots. Your CPU executes the...

 

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Your branch target buffer (and branch history buffer) each have 8 slots. Your CPU executes the following code fragment. Assume that prediction takes place in the Fetch cycle, and that the result of a branch is actually known after the execute cycle. Assume full forwarding (MX, WX, WM). addi x12, x0, 5 add x11, x0, xo // x11 = 0 add x19, x0, x0 // x19 = 0 L1: L2: L3: Exit: addi x20, x0, 150 bge x11, x12, Exit slli x13, x11, 3 add x14, x16, x13 ld x15, 0(x14) blt x15, x20, L2 sd x0, 0(x14) add x19, x15, x19 beq x0, x0. L3 addi x15, x15, 1 sd x15, 0(x14) addi x11, x11, 1 jal x0, L1 // i8 //x16 address of array[0] // i++ (a) Draw a pipeline diagram for the execution of the program, assuming a static predict-not-taken policy (yes, this means that the BTB and BHT aren't used... yet). Circle the stages in which the outcome of a branch is known. Make sure to include stalls due to branch misprediction. How many cycles are lost due to stalls? (b) Assume that you are using a 1-bit branch predictor, and redraw the pipeline diagram. How many cycles are lost due to stalls? Make sure that you incorporate the cycle in which the outcome of a branch is known, if necessary. (c) Show the values read and written from the BTB and BHT (from 2b, and the cycles in which the read/write occurs. You need not show reads due to fetches of non-branch instructions. (d) Assume that you are using a 2-bit branch predictor, and redraw the pipeline diagram. How many cycles are lost due to stalls? Make sure that you incorporate the cycle in which the outcome of a branch is known, if necessary. (e) Show the values read and written from the BTB and BHT (from 2d, and the cycles in which the read/write occurs. You need not show reads due to fetches of non-branch instructions. Your branch target buffer (and branch history buffer) each have 8 slots. Your CPU executes the following code fragment. Assume that prediction takes place in the Fetch cycle, and that the result of a branch is actually known after the execute cycle. Assume full forwarding (MX, WX, WM). addi x12, x0, 5 add x11, x0, xo // x11 = 0 add x19, x0, x0 // x19 = 0 L1: L2: L3: Exit: addi x20, x0, 150 bge x11, x12, Exit slli x13, x11, 3 add x14, x16, x13 ld x15, 0(x14) blt x15, x20, L2 sd x0, 0(x14) add x19, x15, x19 beq x0, x0. L3 addi x15, x15, 1 sd x15, 0(x14) addi x11, x11, 1 jal x0, L1 // i8 //x16 address of array[0] // i++ (a) Draw a pipeline diagram for the execution of the program, assuming a static predict-not-taken policy (yes, this means that the BTB and BHT aren't used... yet). Circle the stages in which the outcome of a branch is known. Make sure to include stalls due to branch misprediction. How many cycles are lost due to stalls? (b) Assume that you are using a 1-bit branch predictor, and redraw the pipeline diagram. How many cycles are lost due to stalls? Make sure that you incorporate the cycle in which the outcome of a branch is known, if necessary. (c) Show the values read and written from the BTB and BHT (from 2b, and the cycles in which the read/write occurs. You need not show reads due to fetches of non-branch instructions. (d) Assume that you are using a 2-bit branch predictor, and redraw the pipeline diagram. How many cycles are lost due to stalls? Make sure that you incorporate the cycle in which the outcome of a branch is known, if necessary. (e) Show the values read and written from the BTB and BHT (from 2d, and the cycles in which the read/write occurs. You need not show reads due to fetches of non-branch instructions.

Answer rating: 100% (QA)

a Pipeline diagram with static predictnottaken policy Fetch Decode Execute Memory Writeback addi 1 a... View the full answer