RFR 6642881: Improve performance of Class.getClassLoader()

[Vladimir Ivanov]

Looks good.

Best regards,
Vladimir Ivanov

On 6/16/14 7:42 PM, Coleen Phillimore wrote:
> Summary: Add classLoader to java/lang/Class instance for fast access
>
> In order to improve performance of Class.getClassLoader() in a way to
> allow the compilers to automatically optimize this call, I added the
> classLoader to the instance of java/lang/Class.  For microbenchmarks,
> this results in a 98% improvement, which was expected.  For Oracle
> internal applications, this results in a 10-12% improvement on
> solaris/sparc.   The increase in size of java/lang/Class can be offset
> by other changes (removing constant pool lock, or removing signers).
>
> See bug link https://bugs.openjdk.java.net/browse/JDK-6642881 and
> associated linked bugs for more details.
>
> open webrev at http://cr.openjdk.java.net/~coleenp/6642881_hotspot/
> open webrev at http://cr.openjdk.java.net/~coleenp/6642881_jdk/
>
> There is both hotspot and jdk changes for this change.  The hotspot
> changes can work without the jdk changes (check for optional field), but
> not vice-versa.  I'll file another bug (and compatibility request) to
> remove JVM_GetClassLoader from hotspot.
>
> Tested with jck lang, vm, api/java_lang tests with/without jdk change,
> nsk vm.quick.testlist and hotspot jtreg tests, and jprt.
>
> Thanks,
> Coleen
>
>