Based on the other answers, the proper answer is: they do whatever the instructions bits tell them too. Since apparently they aren't validated, they always do something, even if that something is nothing.

Same as trying to turn on a lamp on an illuminated room- you won't notice it is there and it is on.

Based on the other answers, the proper answer is: they do whatever the instructions bits tell them too. Since apparently they aren't validated, they always do something, even if that something is nothing.

Same as trying to turn on a lamp on an illuminated room- you won't notice it is there and it is on.

EDIT: I had a question in the answer which I removed, which was "Another question you may ask is: if an instruction does not exist, how does the processor knows it length?", which was replied in the comments below.

Based on the other answers, the proper answer is: they do whatever the instructions bits tell them too. Since apparently they aren't validated, they always do something, even if that something is nothing.

Same as trying to turn on a lamp on an illuminated room- you won't notice it is there and it is on.

Another question you may ask is: if an instruction does not exist, how does the processor knows it length? (since unlike MIPS, x86 is variable-sized instructions) I would like to know the answer to this question too :)

Based on the other answers, the proper answer is: they do whatever the instructions bits tell them too. Since apparently they aren't validated, they always do something, even if that something is nothing.

Same as trying to turn on a lamp on an illuminated room- you won't notice it is there and it is on.