--- Quote Start ---
That's why I think the compile is made following the value as follows your explanation (josyb) and
so the value defines the way of compile. Is correct?
--- Quote End ---
I think
yes because of optimisations.
In Quartus messages windows, you can see (a part of) those optimisations. In the report too.
I am not an expert, neither a Quartus software designer and I haven't try other compilers.
You are focusing on the compiler algorithm, I would advice you to focus more on helping the compiler. Many design tips.
@Josyb : thanks for your experience.
Nota Bene : On my example above (process(clk_43)) : the last else statement is not needed.