On 6/30/14, 3:50 PM, Christian Thalinger wrote:
private Class(ClassLoader loader) {
// Initialize final field for classLoader. The initialization value
of non-null
// prevents future JIT optimizations from assuming this final field
is null.
classLoader = loader;
+ componentType = null;
}
Are we worried about the same optimization?
I don't know if I was justified in worrying about the optimization in
the first place. Since getComponentType() is conditional, I wasn't
worried.
But it should be consistent. Maybe I should revert the classLoader
constructor change, now that I fixed all the tests not to care. What do
people think?
+ compute_optional_offset(_component_mirror_offset,
+ klass_oop, vmSymbols::componentType_name(),
+ vmSymbols::class_signature());
Is there a followup cleanup to make it non-optional? Or, are you
waiting for JPRT to be able to push hotspot and jdk changes together?
Yes, please look at the _full webrev. That has the non-optional changes
in it and the follow on changes to remove getComponentType as an
intrinsic in C2 (will file new RFE). I really would like a compiler
person to comment on it.
Thanks so much,
Coleen
On Jun 30, 2014, at 5:42 AM, Coleen Phillimore
<coleen.phillim...@oracle.com <mailto:coleen.phillim...@oracle.com>>
wrote:
On 6/30/14, 1:55 AM, David Holmes wrote:
Hi Coleen,
Your webrev links are to internal locations.
Sorry, I cut/pasted the wrong links. They are:
http://cr.openjdk.java.net/~coleenp/8047737_jdk/
<http://cr.openjdk.java.net/%7Ecoleenp/8047737_jdk/>
http://cr.openjdk.java.net/~coleenp/8047737_hotspot/
and the full version
http://cr.openjdk.java.net/~coleenp/8047737_hotspot/
Thank you for pointing this out David.
Coleen
David
On 28/06/2014 5:24 AM, Coleen Phillimore wrote:
Summary: Add field in java.lang.Class for componentType to simplify oop
processing and intrinsics in JVM
This is part of ongoing work to clean up oop pointers in the metadata
and simplify the interface between the JDK j.l.C and the JVM. There's a
performance benefit at the end of all of this if we can remove all oop
pointers from metadata. mirror in Klass is the only one left after
this full change.
See bug https://bugs.openjdk.java.net/browse/JDK-8047737
There are a couple steps to this change because Hotspot testing is done
with promoted JDKs. The first step is this webrev:
http://oklahoma.us.oracle.com/~cphillim/webrev/8047737_jdk/
http://oklahoma.us.oracle.com/~cphillim/webrev/8047737_hotspot/
When the JDK is promoted, the code to remove
ArrayKlass::_component_mirror will be changed under a new bug id.
http://oklahoma.us.oracle.com/~cphillim/webrev/8047737_hotspot_full
Finally, a compatibility request and licensee notification will
occur to
remove the function JVM_GetComponentType.
Performance testing was done that shows no difference in performance.
The isArray() call is a compiler intrinsic which is now called instead
of getComponentType, which was recognized as a compiler intrinsic.
JDK jtreg testing, hotspot jtreg testing, hotspot NSK testing and jck8
tests were performed on both the change requested (1st one) and the
full
change.
hotspot NSK tests were run on the hotspot-only change with a
promoted JDK.
Please send your comments.
Thanks,
Coleen
