There are different levels of "what". 1. I'm moving value from this address to that address through %rax register. 2. I'm copying this value from that place t

There are different levels of "what". 1. I'm moving value from this address to that address through %rax register. 2. I'm copying this value from that place to that. 3. I'm making sure that this values are equal. 4. An invariant was broken and I need to restore it. If you look at it, each next like is an answer to "why" question applied to a previous line. Answers to "why" questions becomes new "what" and then "why" applied to them again. The point I want to make is it is easier to move back (in descending order) through this than forward. When you know (4) you can easily figure out what is needed to be done. But if you have (1) you need to infer next points one by one. One who just wrote the patch is probably unaware of differences, because he knows all the answers and can easily move from one to another. He/she do not feel difficulties. But the person who reads patch starts with (1) and needs to climb the ladder in opposite direction than the person who wrote the patch.