8368475: [lworld] Add preview classes to jimage at make time

[david-beaumont]

Copies valuetype classes for each module into corresponding "/META-INF/preview/..." sub-directories to be pulled into jimage files and processed by the new preview mode handling code.

There might be a better way to do this in terms of Makefile semantics, but this seems to work well enough and doesn't prevent the value-class JAR files being generated for patching (which is still how everyone will get value classes until the rest of the work is plumbed in).

To enable the new preview mode work, set the "DISABLE_PREVIEW_PATCHING" system property to "true".

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Issue

• JDK-8368475: [lworld] Add preview classes to jimage at make time (Sub-task - P3)

Reviewers

• Roger Riggs (@RogerRiggs - Committer)

Reviewing

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[bridgekeeper]

👋 Welcome back david-beaumont! A progress list of the required criteria for merging this PR into lworld will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

@david-beaumont 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.

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8368475: [lworld] Add preview classes to jimage at make time

Reviewed-by: rriggs

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At the time when this comment was updated there had been 4 new commits pushed to the lworld branch:

• fe178a8: 8364447: [lworld] Save isIdentity in a field of Class
• 63a6221: 8371897: [lworld] CLONE - VerifyJimage test incorrectly skips all tests when comparing directory structure
• b1d14c6: 8371382: [lworld] Javac accepts field initializer that refers to a superclass field
• ... and 1 more: https://git.openjdk.org/valhalla/compare/409f56a757145bf59ba17c9975c0dab2c01eef5b...lworld

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[mlbridge]

Webrevs

• 01: Full - Incremental (09327056)
• 00: Full (e38847af)

[RogerRiggs]

How is this change tested?
What tests verify the configuration with "DISABLE_PREVIEW_PATCHING=true"

[RogerRiggs]

Please merge with lworld so all the related commits are in place.

[RogerRiggs]

There should be a log message indicating that jimage is using preview classes.
Perhaps per-class logging, as is done for CDS archive or JAR file or..., indicating where the class is loaded from. That would give good visibility into class loading problems, if any.

There is an existing message in arguments.cpp for patched value classes that could be revised for enabling preview classes from jimage.

    log_info(class)("--enable-preview appending value classes for module %s: %s", module_name, entry->d_name);

[RogerRiggs]

This does the job, but its hard to confirm the results.