RFR 8047737 Move array component mirror to instance of java/lang/Class

[Coleen Phillimore]

Thank you!
Coleen

On 7/1/14, 12:51 AM, Christian Thalinger wrote:
> On Jun 30, 2014, at 5:50 PM, Coleen Phillimore <coleen.phillimore at oracle.com> wrote:
>
>> 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?
>> Hi,  I've decided to make them consistent and add another parameter to the Class constructor.
>>
>> http://cr.openjdk.java.net/~coleenp/8047737_jdk_2/
> Thanks.
>
>> Thanks,
>> Coleen
>>> +  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?
>>>
>>> On Jun 30, 2014, at 5:42 AM, Coleen Phillimore <coleen.phillimore at oracle.com <mailto:coleen.phillimore at 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