8373987: [lworld] exploded-image/test broken since disable patching (JDK-8373806)

[david-beaumont]

Preview mode support for exploded build.

This is an alternate approach from #1845 which I think is actually cleaner and more robust.

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Issue

• JDK-8373987: [lworld] exploded-image/test broken since disable patching (JDK-8373806) (Bug - P3)

Reviewers

• Lois Foltan (@lfoltan - Committer)

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8373987: [lworld] exploded-image/test broken since disable patching (JDK-8373806)

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At the time when this comment was updated there had been 112 new commits pushed to the lworld branch:

• 6886e81: 8374117: [lworld] Disable Valhalla specific VM flags when --enable-preview is not set
• 4b318c8: Merge
• 4f283f1: 8373820: C2: Robust Node::uncast_helper infinite loop check
• ... and 109 more: https://git.openjdk.org/valhalla/compare/69399cedf6fe208832a66c134d370af860154bc2...lworld

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[lfoltan]

LGTM.

One nit at line #735 in classLoader.cpp, the convention within the file is to specify the variable that you are checking nullptr against first, if (preview_entry != nullptr)...

Thanks,
Lois

[RogerRiggs]

Previously, the preview related names were associated with jimage mode, expanding that to the exploded image raises a question about the name and the name set_preview_mode ; there may be some ambiguity in this is_preview_enabled() and the vm wide method(s) indicating --enable-preview across all HotSpot functions.
It would be good if this name could reflect the mode of loading classes.
Maybe...
is_class_loading_mode_preview() based on class_loading_mode.