Brooks Moses wrote on 11/06/06 17:41:
Is there a need for any fine-grained control on this knob, though, or
would it be sufficient to add an -O4 option that's equivalent to -O3 but
with no optimization throttling?
We need to distinguish two orthogonal issues here: effort and enabled
transformations. Currently, -O3 means enabling transformations that (a)
may not result in an optimization improvement, and (b) may change the
semantics of the program. -O3 will also enable "maximum effort" out of
every transformation.
In terms of effort, we currently have individual knobs in the form of -f
and/or --params settings. It should not be hard to introduce a global
-Oeffort=xxx parameter. But, it will take some tweaking to coordinate
what -f/--params/-m switches should that enable.
