At some point in the future it may be possible, with the constant folding work, to express the declaration of a MH locally but it gets stuffed in the constant pool (see amber constant-folding) if what the MH is derived from is constant. e.g. think of a language compiler intrinsic for ldc. That may be improve some use-cases but if any input is not constant we are back to the slower path.
Paul. > On Feb 2, 2018, at 5:03 AM, Remi Forax <fo...@univ-mlv.fr> wrote: > > Hi Charles, > usually, it's because a non constant method handle is not inlined into the > callsite, > so it's as fast as a function call or a method call when you ask to not > inline. > > A way to improve the perf is to profile the method handles that can be seen > when doing an invokeExact, > and inline them if they are few of them, making invokeExact acts as a > n-morphic inlining cache (with an identity check instanceof a class check). > > Obviously, it's also easy to emulate think kind of cache with an > invokedynamic, i think Golo has such cache (Golo lambdas are plain method > handle), > and if you want to go fully circular, you can simulate invokedynamic with an > invokeExact on a constant method handle :) > > see you tomorrow, > Rémi > > ----- Mail original ----- >> De: "John Rose" <john.r.r...@oracle.com> >> À: "Da Vinci Machine Project" <mlvm-dev@openjdk.java.net> >> Envoyé: Vendredi 2 Février 2018 13:33:49 >> Objet: Re: Performance of non-static method handles > >> Vladimir Ivanov did some work a few years ago on MH customization for hot MH >> instances. It’s in the system. That should get better results than what you >> show. I wonder why it isn’t kicking in. You are using invokeExact right? >> >>> On Feb 2, 2018, at 1:26 PM, Charles Oliver Nutter <head...@headius.com> >>> wrote: >>> >>> Hey folks! >>> >>> I'm running some simple benchmarks for my FOSDEM handles talk and wanted to >>> reopen discussion about the performance of non-static-final method handles. >>> >>> In my test, I just try to call a method that adds given argument to a static >>> long. The numbers for reflection and static final handle are what I'd >>> expect, >>> with the latter basically being equivalent to a direct call: >>> >>> Direct: 0.05ns/call >>> Reflected: 3ns/call >>> static final Handle: 0.05ns/call >>> >>> If the handle is coming from an instance field or local variable, however, >>> performance is only slightly faster than reflection. I assume the only real >>> improvement in this case is that it doesn't box the long value I pass in. >>> >>> local var Handle: 2.7ns/call >>> >>> What can we do to improve the performance of non-static method handle >>> invocation? >>> >>> - Charlie >>> _______________________________________________ >>> mlvm-dev mailing list >>> mlvm-dev@openjdk.java.net >>> http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev >> >> _______________________________________________ >> mlvm-dev mailing list >> mlvm-dev@openjdk.java.net >> http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev > _______________________________________________ > mlvm-dev mailing list > mlvm-dev@openjdk.java.net > http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev _______________________________________________ mlvm-dev mailing list mlvm-dev@openjdk.java.net http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev
