Thanks! Pushed.
/Claes
On 2018-02-20 17:06, Brian Goetz wrote:
That’s great. Anyone maintaining this file should see it.
On Feb 20, 2018, at 7:46 AM, Claes Redestad <claes.redes...@oracle.com> wrote:
Would injecting this before the LMF::metafactory do? Or should this be an
@implNote?
diff -r d8e1eab41853
src/java.base/share/classes/java/lang/invoke/LambdaMetafactory.java
--- a/src/java.base/share/classes/java/lang/invoke/LambdaMetafactory.java Tue
Feb 20 14:40:53 2018 +0100
+++ b/src/java.base/share/classes/java/lang/invoke/LambdaMetafactory.java Tue
Feb 20 16:50:27 2018 +0100
@@ -242,6 +242,12 @@
private static final Class<?>[] EMPTY_CLASS_ARRAY = new Class<?>[0];
private static final MethodType[] EMPTY_MT_ARRAY = new MethodType[0];
+ // LambdaMetafactory bootstrap methods are startup sensitive, and may be
+ // special cased in java.lang.invokeBootstrapMethodInvoker to ensure
+ // methods are invoked with exact type information to avoid generating
+ // code for runtime checks. Take care any changes or additions here are
+ // reflected there as appropriate.
+
/**
* Facilitates the creation of simple "function objects" that implement
one
* or more interfaces by delegation to a provided {@link MethodHandle},
/Claes
On 2018-02-20 16:05, Brian Goetz wrote:
Add a comment to LMF to remember to update the hack if additional sigs are
added.
Sent from my iPad
On Feb 20, 2018, at 4:27 AM, Claes Redestad <claes.redes...@oracle.com> wrote:
You also pointed out that if the params or return types doesn't match, we'd get
a CCE sooner or later, making the return and argument checks superfluous. This
all simplifies into this, then:
http://cr.openjdk.java.net/~redestad/8198418/jdk.02/
Thanks!
/Claes
On 2018-02-20 13:20, Vladimir Ivanov wrote:
No need in MT.equals. Pointer comparison should work as well: MethodType
instances are interned and all exact type checks on MethodHandles are
implemented using == on their MTs.
Best regards,
Vladimir Ivanov
On 2/20/18 3:07 PM, Claes Redestad wrote:
Hi Rémi,
sure, MethodType.equals will do a fast == check, but then checks the param
types. It sure looks cleaner, though:
http://cr.openjdk.java.net/~redestad/8198418/jdk.01/
Thanks!
/Claes
On 2018-02-20 12:38, Remi Forax wrote:
Hi Claes,
instead of checking each parameter of the bsmType(), why not allocating the
corresponding MethodType and storing it in a static final, so you can check if
the MethodType are equals using equals (as far as i remember MethodType.equals
is a == in the OpenJDK implementation).
in term of name why not isLambdaMetafactoryIndyBootstrapMethod and
isLambdaMetafactoryCondyBoostrapMethod instead of isLambdaMetafactoryCallSite
and isLambdaMetafactoryFunction ?
and you can remove <T> in the signature of isLambdaMetafactoryCallSite() and replace
Class<T> by Class<?>.
cheers,
Rémi
----- Mail original -----
De: "Claes Redestad" <claes.redes...@oracle.com>
À: "core-libs-dev" <core-libs-dev@openjdk.java.net>
Envoyé: Mardi 20 Février 2018 11:51:15
Objet: [11] RFR: 8198418: Invoke LambdaMetafactory::metafactory exactly from
the BootstrapMethodInvoker
Hi,
a small regression to lambda bootstrapping came in with the recent
condy merge, and it took me a while to figure out why.
Before condy, the first three parameters of calls from the BSM invoker
to the six parameter LambdaMetafactory::metafactory were statically
known, so only the fourth through sixth param were dynamically bound
to enforce runtime type checks (MH.invoke -> MH.checkGenericInvoker
-> MH.asType(MT) -> MHI.makePairwiseConvertByEditor -> generates a
slew of filterArguments, rebinds, casting MHs etc).
With condy, the third parameter is now an Object (in reality either a
Class or a MethodType), thus not statically known. This means the
MethodType sent to checkGenericInvoker will have to add a cast for
this param too, thus in makePairwiseConvertByEditor we see an
additional rebind, some additional time spent spinning classes etc.
Effectively increasing the cost of first lambda initialization by a small
amount (a couple of ms).
Here came the realization that much of the static overhead of the
lambda bootstrapping could be avoided altogether since we can
determine and cast arguments statically for the special-but-common
case of LambdaMetafactory::metafactory. By using exact type
information, and even bootstrapMethod.invokeExact, no dynamic
runtime checking is needed, so the time spent in
makePairwiseConvertByEditor is avoided entirely.
This might be a hack, but a hack that removes a large chunk of the
code executed (~75% less bytecode) for the initial lambda bootstrap.
Startup tests exercising lambdas show a 10-15ms improvement - the
static overhead of using lambdas is now just a few milliseconds in total.
Webrev: http://cr.openjdk.java.net/~redestad/8198418/jdk.00/
RFE: https://bugs.openjdk.java.net/browse/JDK-8198418
The patch includes a test for an experimental new metafactory method
that exists only in the amber condy-folding branch. I can easily break it
out and push that directly to amber once this patch syncs up there, but
have tested that keeping it in here does no harm.
Thanks!
/Claes
