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. 


> On Feb 2, 2018, at 5:03 AM, Remi Forax <> 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" <>
>> À: "Da Vinci Machine Project" <>
>> 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 <> 
>>> 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 mailing list
> _______________________________________________
> mlvm-dev mailing list

mlvm-dev mailing list

Reply via email to