And WEEKS of lost time, mopping the cr*p afteer each such gain have lost me half of lifetime already. And it is adding up infinitely faster.
Doing it for testing is fine, but using this in kernel for 1% gain on some irellevant test for 99.999% of the planet while risking for the thing to ge berserk and make fruit salad out of one's disk/s/ is IMHO moronic.
Nobody said LTO is going to be FORCED in the kernel. It would probably be quite the opposite.