8357782: JVM JIT Causes Static Initialization Order Issue

[mhaessig]

Issue Summary

When C1 compiles a method that allocates a new instance of a class that is not fully initialized at compile time, it does not take into account that the <clinit> might run a static initializer that might have side effects. Consider the following example:

class A {
    static class B {
        static String field;
        static void test() {
            String tmp = field;
            new C(field);
        }
    }

    static class C {
        static {
            B.field = "Hello";
        }

        C(String val) {
            if (val == null) {
                throw new RuntimeException("Should not reach here");
            }
        }
    }
}

Here, B.field gets assigned in C's static initializer. Since C1 believes that the newinstance does not have memory side effects, local value numbering eliminates the field access for the argument in C.<init> because it believes that B.field is still the same as tmp. Hence, the assignment in C.<clinit> gets effectively ignored and the code triggers the runtime exception. Because this only happens if C is not fully initialized when it is compiled, we need -Xcomp to reproduce this issue.

Changes

To fix the illustrated issue, this PR ensures that newinstance kills the memory state in C1's LVN if the class might not be fully initialized. Since we can not reliably detect if a class has a static initializer, we kill memory whenever a class is not yet loaded or, if it has already been loaded, when it has not been fully initialized, which is conservative and might kill memory when it is not necessary for correctness and have an impact on performance in the form of some additional field accesses.

Benchmark Results

Since this might have an effect on startup, I ran some benchmarks. The results mostly did not show effects outside the run-to-run variance.

Testing

• Github Actions
• tier1 through tier3 plus Oracle internal testing on Oracle supported platforms and OSes

Acknowledgements

Shout out to @TobiHartmann who wrote the reproducer that became the regression test and helped me find my way around C1 and narrow down the problem.

---

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-8357782: JVM JIT Causes Static Initialization Order Issue (Bug - P3)

Reviewers

• Damon Fenacci (@dafedafe - Committer) Review applies to ccdbdbdc
• Tobias Hartmann (@TobiHartmann - Reviewer)
• Dean Long (@dean-long - Reviewer)

Contributors

• Tobias Hartmann <[email protected]>

Reviewing

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$ git checkout pull/25725

Update a local copy of the PR:
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$ git pull https://git.openjdk.org/jdk.git pull/25725/head

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Checkout this PR locally:
$ git pr checkout 25725

View PR using the GUI difftool:
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https://git.openjdk.org/jdk/pull/25725.diff

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[bridgekeeper]

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

[openjdk]

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

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

8357782: JVM JIT Causes Static Initialization Order Issue

Co-authored-by: Tobias Hartmann <[email protected]>
Reviewed-by: thartmann, dlong, dfenacci

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At the time when this comment was updated there had been 95 new commits pushed to the master branch:

• e7f63ba: 8359327: Incorrect AVX3Threshold results into code buffer overflows on APX targets
• a0fb35c: 8359272: Several vmTestbase/compact tests timed out on large memory machine
• 032ead1: 8358483: G1: Remove G1HeapRegionManager::num_available_regions
• ... and 92 more: https://git.openjdk.org/jdk/compare/bd08932d5b9d1a363d8229ea72df4c6dbfd4571d...master

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[openjdk]

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[mhaessig]

/contributor add @TobiHartmann

[openjdk]

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

[mlbridge]

Webrevs

• 02: Full - Incremental (71b04b50)
• 01: Full - Incremental (f6a4a290)
• 00: Full (ccdbdbdc)

[dafedafe]

Thanks for fixing this @mhaessig!
Looks good to me!

[TobiHartmann]

Looks good to me.

[mhaessig]

Thank you for your reviews!

/integrate

[openjdk]

@mhaessig
Your change (at version 71b04b5) is now ready to be sponsored by a Committer.

[TobiHartmann]

/sponsor

[openjdk]

Going to push as commit e8ef93a.
Since your change was applied there have been 98 commits pushed to the master branch:

• 25b22c9: 8358602: JFR: Annotations in jdk.jfr package should not use "not null" in specification
• ead4529: 8340182: Java HttpClient does not follow default retry limit of 3 retries
• 3a18872: 8359225: Remove unused test/jdk/javax/script/MyContext.java
• ... and 95 more: https://git.openjdk.org/jdk/compare/bd08932d5b9d1a363d8229ea72df4c6dbfd4571d...master

Your commit was automatically rebased without conflicts.

[openjdk]

@TobiHartmann @mhaessig Pushed as commit e8ef93a.

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