8336489: Track scoped accesses in JVMCI compiled code

[c-refice]

This PR adds JVMCI support to scoped access tracking introduced in #20158.

In this PR:

• The Method::is_scoped flag is now exposed in JVMCI as HotSpotResolvedJavaMethod.isScoped(), and serialized to / deserialized from the JVMCI compiled code stream as a boolean flag.
• To determine whether a compiled method has a scoped access, we simply check HotSpotResolvedJavaMethod.isScoped() returns true for the root method or any of the methods that were inlined in the compilation.
• The above check is implemented as the method HotSpotCompiledNMethod.hasScopedAccess(), instead of as an explicit flag set in a the constructor of HotSpotCompiledNMethod. This keeps the change isolated to JVMCI, without requiring coordinated changes to the Graal compiler. No other changes in the compiler are necessary to benefit from the optimization.

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8336489: Track scoped accesses in JVMCI compiled code (Enhancement - P3)

Reviewers

• Tom Rodriguez (@tkrodriguez - Reviewer) 🔄 Re-review required (review applies to 9620670b)
• Doug Simon (@dougxc - Reviewer)

Reviewing

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$ git checkout pull/20256

Update a local copy of the PR:
$ git checkout pull/20256
$ git pull https://git.openjdk.org/jdk.git pull/20256/head

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$ git pr checkout 20256

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https://git.openjdk.org/jdk/pull/20256.diff

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[openjdk]

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

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

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

8336489: Track scoped accesses in JVMCI compiled code

Reviewed-by: dnsimon, never

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 78 new commits pushed to the master branch:

• 2e093b0: 8337779: test/jdk/jdk/jfr/jvm/TestHiddenWait.java is a bit fragile
• d3e7b0c: 8336462: ConcurrentSkipListSet Javadoc incorrectly warns about size method complexity
• be34730: 8335257: Refactor code to create Initialized Assertion Predicates into separate class
• fbe8a81: 8333144: docker tests do not work when ubsan is configured
• dabdae6: 8334599: Improve code from JDK-8302671
• 8bd3cd5: 8337716: ByteBuffer hashCode implementations are inconsistent
• 367e0a6: 8334755: Asymptotically faster implementation of square root algorithm
• 34edc73: 8337396: Cleanup usage of ExternalAddess
• 7deee74: 8335122: Reorganize internal low-level support for HTML in jdk.javadoc
• f2e1205: 8337676: JFR: Change the label of the throttle setting
• ... and 68 more: https://git.openjdk.org/jdk/compare/374fca0fcbc049f937fa49bb4825edcbbf961f2b...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

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[openjdk]

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[c-refice]

/covered

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Webrevs

• 05: Full - Incremental (8b61ab79)
• 04: Full (8fabb8bb)
• 03: Full - Incremental (59c4fa79)
• 02: Full - Incremental (9620670b)
• 01: Full - Incremental (1f60dae3)
• 00: Full (5f961087)

[tkrodriguez]

Looks good to me

[openjdk]

@c-refice Please do not rebase or force-push to an active PR as it invalidates existing review comments. Note for future reference, the bots always squash all changes into a single commit automatically as part of the integration. See OpenJDK Developers’ Guide for more information.

[tkrodriguez]

New version looks good.

[c-refice]

I figured out what went wrong with the is_scoped flag in JVMCI. The implementation of HotSpotResolvedJavaMethodImpl#getConstMethodFlags was as follows:

    private int getConstMethodFlags() {
        return UNSAFE.getChar(getConstMethod() + config().constMethodFlagsOffset);
    }
    
    public boolean isScoped() {
        // constMethodFlagsIsScoped == 1 << 16
        return (getConstMethodFlags() & config().constMethodFlagsIsScoped) != 0;
    }

However, ConstMethod::_flags is a u4, not a u1. This caused only the least significant byte of the flags (or most, depending on endianness) to be read in JVMCI code. A similar problem also occurred with Method::_flags, though for that one two bytes were read.

I suppose we didn't really care about flags with bit indexes past 8 before now, hence why the tests never failed before. Nevertheless, I fixed both and isScoped() now behaves as expected (and tested)

[openjdk]

@c-refice Please do not rebase or force-push to an active PR as it invalidates existing review comments. Note for future reference, the bots always squash all changes into a single commit automatically as part of the integration. See OpenJDK Developers’ Guide for more information.

[c-refice]

Apologies for the second force push, I involuntarily rebased my branch on top of origin/master again

[dougxc]

Still looks good to me.

[c-refice]

/integrate

[openjdk]

@c-refice
Your change (at version 8b61ab7) is now ready to be sponsored by a Committer.

[dougxc]

/sponsor

[openjdk]

Going to push as commit c095c0e.
Since your change was applied there have been 79 commits pushed to the master branch:

• 7e925d7: 8337283: configure.log is truncated when build dir is on different filesystem
• 2e093b0: 8337779: test/jdk/jdk/jfr/jvm/TestHiddenWait.java is a bit fragile
• d3e7b0c: 8336462: ConcurrentSkipListSet Javadoc incorrectly warns about size method complexity
• be34730: 8335257: Refactor code to create Initialized Assertion Predicates into separate class
• fbe8a81: 8333144: docker tests do not work when ubsan is configured
• dabdae6: 8334599: Improve code from JDK-8302671
• 8bd3cd5: 8337716: ByteBuffer hashCode implementations are inconsistent
• 367e0a6: 8334755: Asymptotically faster implementation of square root algorithm
• 34edc73: 8337396: Cleanup usage of ExternalAddess
• 7deee74: 8335122: Reorganize internal low-level support for HTML in jdk.javadoc
• ... and 69 more: https://git.openjdk.org/jdk/compare/374fca0fcbc049f937fa49bb4825edcbbf961f2b...master

Your commit was automatically rebased without conflicts.

[openjdk]

@dougxc @c-refice Pushed as commit c095c0e.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.