8254286: Wrong inference in switch expression with "null" arm

[lahodaj]

Basically, for code like:

    var t1 = switch (s) {
        case 1 -> i1;
        case 2 -> null;
        default -> i2;
    };

Attr.condType is currently passing , BOT, to Types.lub. But Types.lub needs the list without BOT, so filtering BOT(s) out of the list.

---

Progress

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Testing

	Linux x64	Windows x64	macOS x64
Build	❌ (2/5 failed)	✔️ (2/2 passed)	✔️ (2/2 passed)
Test (tier1)		✔️ (9/9 passed)	✔️ (9/9 passed)

Failed test tasks

• Linux x64 (build hotspot minimal)
• Linux x64 (build hotspot zero)

Issue

• JDK-8254286: Wrong inference in switch expression with "null" arm

Reviewers

• Maurizio Cimadamore (@mcimadamore - Reviewer)
• Vicente Romero (@vicente-romero-oracle - Reviewer)

Download

$ git fetch https://git.openjdk.java.net/jdk pull/583/head:pull/583
$ git checkout pull/583

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[mlbridge]

Webrevs

• 00: Full (ffc96c6)

[mcimadamore]

The fix looks fine. Note that in method inference we also skip the erroneous case:

@Override
        public boolean accepts(Type t) {
            return !t.isErroneous() && !inferenceContext.free(t) &&
                    !t.hasTag(BOT);
        }

Not sure whether this applies here too - maybe erroneous types are already skipped earlier?

[openjdk]

@lahodaj 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.

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

8254286: Wrong inference in switch expression with "null" arm

Reviewed-by: mcimadamore, vromero

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 153 new commits pushed to the master branch:

• 294e070: 8254998: C2: assert(!n->as_Loop()->is_transformed_long_loop()) failure with -XX:StressLongCountedLoop=1
• 3ee0380: 8234393: [macos] printing ignores printer tray
• 3f9c8a3: 8254966: Remove unused code from Matcher
• 21e67e5: 8225790: Two NestedDialogs tests fail on Ubuntu
• 017d151: 8254842: [JVMCI] copy thread name when attaching libgraal thread to HotSpot
• 5d1397f: 8254282: Add Linux x86_32 builds to submit workflow
• 7ba6a6b: 8251158: Implementation of JEP 387: Elastic Metaspace
• 5fedfa7: 8251271: C2: Compile::_for_igvn list is corrupted after RenumberLiveNodes
• 98ec4a6: 8254805: compiler/debug/TestStressCM.java is still failing
• 355f44d: 8254994: [x86] C1 StubAssembler::call_RT, "call_offset might not be initialized"
• ... and 143 more: https://git.openjdk.java.net/jdk/compare/d4b5dfd1a2fe4cdb4256269fc76059ba6d0074c8...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

[lahodaj]

The fix looks fine. Note that in method inference we also skip the erroneous case:

@Override
        public boolean accepts(Type t) {
            return !t.isErroneous() && !inferenceContext.free(t) &&
                    !t.hasTag(BOT);
        }

Not sure whether this applies here too - maybe erroneous types are already skipped earlier?

Right - I believe errors are handled by the preceding conditions in condType.

[vicente-romero-oracle]

looks sensible

[lahodaj]

/integrate

[openjdk]

@lahodaj Since your change was applied there have been 242 commits pushed to the master branch:

• 63ce304: 8249675: x86: frequency extraction from cpu brand string is incomplete
• e52156d: 8255067: Restore Copyright line in file modified by 8253191
• c520469: 8255131: G1CollectedHeap::is_in() returns wrong result
• 107fb9c: 8255049: Remove support for the hsdis decode_instructions entry point in hotspot
• c1524c5: 8255208: CodeStrings passed to Disassembler::decode are ignored
• 8e5dff0: 8255213: Shenandoah build fails without JFR after JDK-8255036
• fe74f3c: 8255224: x86_32 tests fail with "bad AD file" after JDK-8223051
• 64dc4b1: 8255225: compiler/aot tests fail on Windows with NPE during artifact resolution
• a824781: 8255210: [Vector API] jdk/incubator/vector/Int256VectorTests.java crashes on AVX512 machines
• 2ca7a08: 8255268: 32-bit failures in runtime/Metaspace/elastic
• ... and 232 more: https://git.openjdk.java.net/jdk/compare/d4b5dfd1a2fe4cdb4256269fc76059ba6d0074c8...master

Your commit was automatically rebased without conflicts.

Pushed as commit 0e92053.

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