Question

Assume the following code is executed on the PIPE machine that does forwarding: 0x000: . pos 0x000: 30f65800000000000000 irmovq num1, *rsi 0x00a: 30f76000000000000000 | irmovq num2, *rdi 0x014: 50660000000000000000 mrmova (rsi), Ersi Oxole: 50770000000000000000 mrmova (rdi), %rdi 0x028: 6176 subq rdi, Xrsi #rsi - Srdi 0x02a: 724600000000000000 jl less 0x033: 30f00000000000000000 irmovq $0, frax 0x03d: 705000000000000000 jmp done Ox046: 30f00100000000000000 less: irmova si, rax 0x050: 00 | done: halt 0x058: .align 8 0x058: c00000000000000 | num1: quad 12 0x60: 8800000000000000 num2: quad 8 What instruction is fetched after the OxO2a: 724600000000000000 jl less Select one: O a. ex050: 00 | done: halt Ob. ex®3d: 705000000000000000 jmp done OC. 0x033: 30f00000000000000000 irmova $0, %rax d. 8x046: 30f00100000000000000 | less: irmova $1, krax

Answer 1

Answer: c irmovq $0, %rax

Explanation:

The values in %rsi and %rdi are 0c00.... and 0800.... Respectively

The result for subq %rsi, %rdi will be positive will not update the negative flag

Therefore jl less is not executed, in which PC points to next instruction

So the next instruction that is executed after jl less is

irmovq $0, %rax.