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Can two commands be executed in one cycle if the same register is used as input and output, respectively?

For example, can these two commands start execution in one cycle, or do they interfere with each other?

MOV  %RAX, (ADDR)      # AT&T syntax: store rax
POP  %RAX
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1 answer

Yes, they can be executed in a single cycle on a modern processor out of order, because they use the Tomasulo algorithm to rename registers. It completely avoids all the dangers of writing after reading, such as this, as well as writing after writing , so execution is not in order limited by valid Read-after-Write dependencies.

After renaming the register, it popwill write the new value of the architectural register RAX to a different physical register than the one that contains the old value of RAX (which is used as an input for the storage).

, pop RAX. ( - .) pop ( , / RAX), , , , .

. Agar Fog microarch pdf x86 wiki.

update: , , , % AX, , 16- Intel -. .

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Intel Sandybridge , , . ( Agner Fog pdf / . , ).

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Source: https://habr.com/ru/post/1652283/

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