[Bug debug/78685] -Og generates too many "<optimized out>"s

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78685

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to rguenther@suse.de from comment #3)
> Sth orthogonal to -Og, -fkeep-vars-live=N with some level, default
> to N > 0 for -Og maybe.
> 
> Of course it will likely pessimize code as I don't see how we can
> easily compute whether var-tracking might reverse compute a vars
> value from sth else.

Yes, trying to guess whether var-tracking will be able to figure something out
is pretty much impossible, perhaps except for easiest cases e.g. where one var
is some other user var + const or something similar.  And sure, it would
pessimize code a lot.