Question about pass_fix_loops or other loop fixing classes

[xerofoify]

Greetings,
I was wondering why the execute function in the file tree-ssa-loop.c
does not for all the pass fixing
classes run it on a separate thread. Seems a good idea to call execute
for these classes on another
thread and then join up with the main thread into order to avoid
shared state or waiting on complex
loops to be optimized.

Maybe I'm missing something so if anyone has a good reason why not let me know,

Nick