8348606: [lworld] Substitutability test may perform heap allocations

[liach]

Update substitutability test to use MethodHandles that access independent primitive/pointer instead heap reallocated copies of inlined values with an object header. Need long-term solution for user MethodHandle that accesses nested values in the future; hope the intrinsics can help in the future.

Testing: test/jdk/valhalla and test/hotspot/jtreg/*/valhalla, tier 1-3 tests running.

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Progress

• [x] Change must not contain extraneous whitespace

Issue

• JDK-8348606: [lworld] Substitutability test may perform heap allocations (Bug - P3)

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:wave: Welcome back liach! 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[bot]]

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

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

8348606: [lworld] Substitutability test may perform heap allocations

Co-authored-by: Tobias Hartmann <[email protected]>

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Webrevs

• 04: Full - Incremental (921a8d59)
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[merykitty]

The reason you are seeing the failures is that you are using Unsafe incorrectly. Note this paragraph:

 * The results are undefined unless one of the following cases is true:
 * <ul>
 * <li>The offset was obtained from {@link #objectFieldOffset} on
 * the {@link java.lang.reflect.Field} of some Java field and the object
 * referred to by {@code o} is of a class compatible with that
 * field's class.
 *
 * <li>The offset and object reference {@code o} (either null or
 * non-null) were both obtained via {@link #staticFieldOffset}
 * and {@link #staticFieldBase} (respectively) from the
 * reflective {@link Field} representation of some Java field.
 *
 * <li>The object referred to by {@code o} is an array, and the offset
 * is an integer of the form {@code B+N*S}, where {@code N} is
 * a valid index into the array, and {@code B} and {@code S} are
 * the values obtained by {@link #arrayBaseOffset} and {@link
 * #arrayIndexScale} (respectively) from the array's class.  The value
 * referred to is the {@code N}<em>th</em> element of the array.
 *
 * </ul>

The wording here is albeit bad, it is not only the result that is undefined, the behaviour itself is undefined.

[liach]

Hmm, @fparain recommends this access pattern for me...

[liach]

Marking this ready - @TobiHartmann recommends me to integrate and C2 to subsequently fix up. This can fix JDK-8354122.

[liach]

/contributor add @TobiHartmann

[openjdk[bot]]

@liach Contributor Tobias Hartmann <[email protected]> successfully added.

[liach]

compiler/valhalla/inlinetypes/TestNullableInlineTypes.java seems to have some problem with aarch64 with -ea -esa -XX:CompileThreshold=100 -XX:+UnlockExperimentalVMOptions -server -XX:-TieredCompilation flags on mac and linux, but I don't know what exactly causes it. No other failure. Guess I am integrating for now.

/integrate

[openjdk[bot]]

@liach Your change (at version 921a8d59961f46b0e29f5bd08644556d0eff3360) is now ready to be sponsored by a Committer.

[TobiHartmann]

Right, the TestNullableInlineTypes.java failure is a known issue.

[TobiHartmann]

/sponsor

[openjdk[bot]]

Going to push as commit 15a064c787fe5ef7972ad7d3de8f0c42b7a0a288.

[openjdk[bot]]

@TobiHartmann @liach Pushed as commit 15a064c787fe5ef7972ad7d3de8f0c42b7a0a288.

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