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JDK16 changes for Hidden Classes #11321

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tajila opened this issue Dec 1, 2020 · 6 comments
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JDK16 changes for Hidden Classes #11321

tajila opened this issue Dec 1, 2020 · 6 comments
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@hangshao0
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comp:vm project:MH Used to track Method Handles related work
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Release 0.25 (Jav...

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@tajila
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tajila commented Dec 1, 2020

See https://bugs.openjdk.java.net/browse/JDK-8256214

Some changes to Lookup
@tajila tajila mentioned this issue Dec 1, 2020
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@tajila
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tajila commented Dec 1, 2020

@hangshao0

@tajila tajila added this to the Release 0.25 (Java 16) milestone Dec 1, 2020
@hangshao0
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I will look at this.

@babsingh
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babsingh commented Dec 1, 2020 •
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In https://bugs.openjdk.java.net/browse/JDK-8256214, the new specification introduces the following new methods and updates few old methods:

    In java.lang.invoke.MethodHandles.Lookup class:
        New Lookup::defineHiddenClassWithClassData method
        New Lookup::ORIGINAL mode and the following methods are updated to reflect this new mode
            Lookup::lookupModes
            Lookup::in
            Lookup::dropLookupIn
    java.lang.invoke.MethodHandles class
        New MethodHandles::classData(Lookup lookup, String name, Class<?> type) static method
        New MethodHandles::classDataAt(Lookup lookup, String name, Class<?> type, int index) static method
        MethodHandles::lookup and MethodHandles::privateLookupIn are updated to reflect the new ORIGINAL mode

Since we plan to move to OpenJDK MH (#7352) in JDK16, the above Java changes to J9 classes can be avoided. We can do minimal changes to get JDK16 builds re-enabled in the short term.

@hangshao0
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Since we plan to move to OpenJDK MH (#7352) in JDK16, the above Java changes to J9 classes can be avoided.

I agree. I was planning to just add the missing bit ORIGINAL and the public API to resolve the compilation issue. But from #11312 (comment) I see you are already doing that.

babsingh added a commit to babsingh/openj9 that referenced this issue Dec 2, 2020
@babsingh
Add Lookup.ORIGINAL and update defineHiddenClassWithClassData for JDK16
3f978f4 
The new Lookup.ORIGINAL field (= 0x40) conflicts with
Lookup.INTERNAL_PRIVILEGED. Since INTERNAL_PRIVILEGED is J9 specific, it
is given a different value (= 0x80).

In JDK16, defineHiddenClassWithClassData has changed to a public method;
and the initOption is supplied by the caller instead of it always being
true.

Related:
eclipse-openj9#11312
eclipse-openj9#11321

Signed-off-by: Babneet Singh <sbabneet@ca.ibm.com>
@hangshao0
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Since #11322 is merged, I think this can be closed. All the new changes here are in OpenJDK MH, which will be consumed by OpenJ9 in Java 16.

@babsingh
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babsingh commented Dec 3, 2020 •
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Updated refs:

  1. https://bugs.openjdk.java.net/browse/JDK-8256214
  2. https://bugs.openjdk.java.net/browse/JDK-8230501

Related commit: ibmruntimes/openj9-openjdk-jdk@1e8bd60

All is Java code. No native dependencies found.
+1 to close this issue.
But, we should relate it to project:MH to verify functionality once OpenJDK MH is enabled in OpenJ9.

@tajila tajila added the project:MH Used to track Method Handles related work label Dec 3, 2020
@tajila tajila removed the blocker label Dec 3, 2020
@tajila tajila closed this as completed Dec 3, 2020
@babsingh babsingh mentioned this issue Dec 4, 2020
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