8327636: [lworld] Make primitive wrappers be value class if preview feature is enabled

[mlchung]

As specified in JEP 401, when preview features are enabled, the following standard library classes are considered to be value classes:

    java.lang.Byte
    java.lang.Short
    java.lang.Integer
    java.lang.Long
    java.lang.Float
    java.lang.Double
    java.lang.Boolean
    java.lang.Character
    java.util.Optional
    java.lang.Number
    java.lang.Record

These value classes are loaded only if --enable-preview is set. All valhalla tests should have preview enabled to ensure testing with the proper set of library classes.

Testing: Run jdk_valhalla and hotspot_valhalla_runtime with -Xint with and without --enable-preview. The result is pretty good. JDK-8327637 and JDK-8327639 need further investigation.

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Progress

• Change must not contain extraneous whitespace

Issue

• JDK-8327636: [lworld] Make primitive wrappers be value class if preview feature is enabled (Bug - P3)

Reviewers

• Roger Riggs (@RogerRiggs - Committer) ⚠️ Review applies to ff15f65e

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[openjdk]

@mlchung This change now passes all automated pre-integration checks.

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After integration, the commit message for the final commit will be:

8327636: [lworld] Make primitive wrappers be value class if preview feature is enabled

Reviewed-by: rriggs

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At the time when this comment was updated there had been 2 new commits pushed to the lworld branch:

• 9c21d4c: 8326990: [lworld] make value classes a preview feature
• 676fe48: 8327498: [lworld] Remove Q-descriptor change from ASM and other clean up

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[mlbridge]

Webrevs

• 02: Full - Incremental (c04cf1ba)
• 01: Full - Incremental (ff15f65e)
• 00: Full (8f981c2f)

[liach]

https://bugs.openjdk.org/browse/JDK-8327481 can be closed as a duplicate of this.

[liach]

Record is already included in the end of the list.

[mlchung]

Good catch. Fixed.

[liach]

Should we merge this and the lookupModule == null early startup cases, and assert lookupModule == refModule && refModule == Object.class.getModule() can become assert lookupModule == refModule && (refModule == null || refModule == Object.class.getModule())?

[mlchung]

It can be simpler:

            // early VM startup case, java.base not defined or module system not initialized
            if (lookupModule == null || !jdk.internal.misc.VM.isModuleSystemInited()) {
                assert lookupModule == refModule;
                return true;
            }

[liach]

Can Class::getModule ever return null after module system is initialized? If not we can omit the lookupModule == null check.

[mlchung]

Can Class::getModule ever return null after module system is initialized?

No.

lookupModule == null when module system is being initialized before java.base is defined. So the null check needs to be there.

[RogerRiggs]

LGTM

[mlchung]

/integrate

[openjdk]

Going to push as commit 3ee4244.
Since your change was applied there have been 2 commits pushed to the lworld branch:

• 9c21d4c: 8326990: [lworld] make value classes a preview feature
• 676fe48: 8327498: [lworld] Remove Q-descriptor change from ASM and other clean up

Your commit was automatically rebased without conflicts.

[openjdk]

@mlchung Pushed as commit 3ee4244.

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