8323657: Compilation of snippet results in VerifyError at runtime with --release 9 (and above)

[lahodaj]

Consider code like:

public class Test {
    public static void main(String... args) {
        System.err.println((test() ? null : null) + "");
    }
    private static boolean test() {
        System.err.println("test called!");
        return true;
    }
}

This should print:

test called!
null

but it prints:

$ java /tmp/Test.java
null

The correct semantics can be achieved by using --source 8:

$ java --source 8 /tmp/Test.java
test called!
null

Or -XDstringConcat=inline when compiling.

The reason is that when StringConcat.IndyConstants converts String concatenation parameters, it will short-circuit any expressions whose type is BOT (i.e. basically the null type). But, in this case, the expression that has the BOT type is a complex expression with a side-effect, so short-circuiting it leads to a broken semantics.

My proposal is to "short-circuit" only null literals, and generate other expressions normally. There may be some corner cases where we'd generate the expression unnecessarily (if it does not have any side-effect), but looking for side-effects seems unnecessarily complex and fragile given I'd expect non-trivial expressions with the BOT type are very rare. (The only case which comes to mind is exactly the above one - a conditional expressions, whose both result values are null.)

Please note that when the expression is incorrectly short-circuited, it may lead to various other effects - the original bug report shows a case where the resulting code does not pass the verification.

---

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Issue

• JDK-8323657: Compilation of snippet results in VerifyError at runtime with --release 9 (and above) (Bug - P3)

Reviewers

• Vicente Romero (@vicente-romero-oracle - Reviewer)

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[vicente-romero-oracle]

lgtm

[openjdk]

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

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

8323657: Compilation of snippet results in VerifyError at runtime with --release 9 (and above)

Reviewed-by: vromero

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At the time when this comment was updated there had been 28 new commits pushed to the master branch:

• 9049402: 8323675: Race in jdk.javadoc-gendata
• f1b7335: 8320113: [macos14] : ShapeNotSetSometimes.java fails intermittently on macOS 14
• 8700de6: 8322744: VirtualThread.notifyJvmtiDisableSuspend should be static
• 6c0bebc: 8159927: Add a test to verify JMOD files created in the images do not have debug symbols
• 437342b: 8323556: CDS archive space addresses should be randomized with ArchiveRelocationMode=1
• 39005e2: 8324041: ModuleOption.java failed with update release versioning scheme
• 2865afe: 8323685: PrintSystemDictionaryAtExit has mutex rank assert
• 6997bfc: 8323154: C2: assert(cmp != nullptr && cmp->Opcode() == Op_Cmp(bt)) failed: no exit test
• 16be388: 8322383: G1: Only preserve marks on objects that are actually moved
• 0081d8c: 8324147: Serial: Remove generation::compute_new_size
• ... and 18 more: https://git.openjdk.org/jdk/compare/ff8cc268fdaaf85299c94088a226b73e7eaf6bdb...master

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[lahodaj]

/integrate

[openjdk]

Going to push as commit c9cacfb.
Since your change was applied there have been 40 commits pushed to the master branch:

• bde650f: 8322282: Incorrect LoaderConstraintTable::add_entry after JDK-8298468
• be943a9: 8321984: IGV: Upgrade to Netbeans Platform 20
• d3b2ac1: 8314186: runtime/8176717/TestInheritFD.java failed with "Log file was leaked"
• 72f1990: 8323057: Recoverable errors may be reported before unrecoverable errors when annotation processing is skipped
• c84af49: 8324129: C2: Remove some ttyLocker usages in preparation for JDK-8306767
• fd37262: 8323748: RISC-V: Add Zfh probe code
• 76afa02: 8322572: AllocationMergesTests.java fails with "IRViolationException: There were one or multiple IR rule failures."
• 2003610: 8323108: BufferedImage.setData(Raster) should not cast float and double values to integers
• a474b37: 8324240: Remove unused GrowableArrayView::EMPTY
• 68b5aab: 8324229: JFR: Temporarily disable assertion for missing object reference
• ... and 30 more: https://git.openjdk.org/jdk/compare/ff8cc268fdaaf85299c94088a226b73e7eaf6bdb...master

Your commit was automatically rebased without conflicts.

[openjdk]

@lahodaj Pushed as commit c9cacfb.

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

[lahodaj]

/backport jdk22u

[openjdk]

@lahodaj the backport was successfully created on the branch backport-lahodaj-c9cacfb2 in my personal fork of openjdk/jdk22u. To create a pull request with this backport targeting openjdk/jdk22u:master, just click the following link:

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Hi all,

This pull request contains a backport of commit c9cacfb2 from the openjdk/jdk repository.

The commit being backported was authored by Jan Lahoda on 22 Jan 2024 and was reviewed by Vicente Romero.

Thanks!

If you need to update the source branch of the pull then run the following commands in a local clone of your personal fork of openjdk/jdk22u:

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$ git checkout backport-lahodaj-c9cacfb2
# make changes
$ git add paths/to/changed/files
$ git commit --message 'Describe additional changes made'
$ git push https://github.com/openjdk-bots/jdk22u.git backport-lahodaj-c9cacfb2

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