On the 0x1AB day of Apache Harmony Mikhail Fursov wrote: > > Seems like the best choice is to start from a couple of easy heuristics: > > * if there is only one loaded class to implement the interface, choose it > > * if there are more, choose the one with it's method invoked earlier > > (compiled > > by some JIT, possibly, some other JIT), > > * if we have many candidate methods that are compiled, choose the most > > frequent > > one (need a method-entry profile, the feature is likely to stay > > untouched for > > a while, I guess) > > > > > > 1. Does anybody have some additional elegant ideas? > > > > > Egor, I'm interested in devirtualizer improvement too.
Great! > IMO the profile based devirtualization will probably have the best results > and is easy to implement and to check: infrastructure in Jitrino is ready to > do it right now with a help of entry-backedge profile collected for OPT by > JET. OK, if it is not so difficult to use the profile. BTW, if I have a backedge in my HIR, how do I identify it with JET's backedge? Or is this done automatically in some way I should not care about? > + more ideas I have: > 1) to use edge profiler as value based one if initial compilation > devirtualize all possible dispatches and count their edge frequencies. Oh, that's a real code bloater!:) IMHO, inlining of these 'possible dispatches' should be disabled. Needs to make a hint for inliner. Not a difficult task though. Just an extra flag in call instruction. > 2) implement a real value profiler - this is not an easy task, but may be > reused in other optimizations Yes, sure. This is a big item for ongoing development. > 3) Add special annotations to classlib code about the most probable > dispatch. E.g. if the variable type does not depend on user's environment > and developer can prove that 90% of time the variable is of specific class - > JIT can read this annotation from method during the compilation and to > devirtualize it. Okay, waiting for 1.5 support here. I like the idea of writing annotations for devirtualization, parallelization, and other. They can provide hints without changing program semantics. I think, they should be available not only in classlib, but for user code too. > I will read more about other devirtualization techniques we can use and will > reply in a several days with results. That would be great! Thanks for ideas! -- Egor Pasko, Intel Managed Runtime Division --------------------------------------------------------------------- Terms of use : http://incubator.apache.org/harmony/mailing.html To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
