8333177: Invalid value used for enum Cell in ciTypeFlow::get_start_state

[TobiHartmann]

Ubsan detected undefined behavior in ciTypeFlow::get_start_state because an invalid value of 4294967295 is assigned to enum Cell:

jdk/src/hotspot/share/ci/ciTypeFlow.hpp

Lines 150 to 152 in ac7119f

	enum Cell {
	Cell_0, Cell_max = INT_MAX
	};

The problem is that if the C++ compiler decides to encode Cell with an unsigned int, casting a negative integer value will lead to an underflow and therefore a value > Cell_max = INT_MAX. Here, state->tos() returns a value < 0:

jdk/src/hotspot/share/ci/ciTypeFlow.cpp

Line 407 in ac7119f

Cell cell = state->next_cell(state->tos());

which is casted to a Cell:

jdk/src/hotspot/share/ci/ciTypeFlow.hpp

Line 211 in ac7119f

static Cell next_cell(Cell c) { return (Cell)(((int)c) + 1); }

I simply re-wrote the code to not require a negative Cell value to iterate over the locals and setting them to bottom type.

Thanks,
Tobias

---

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Issue

• JDK-8333177: Invalid value used for enum Cell in ciTypeFlow::get_start_state (Bug - P4)

Reviewers

• Vladimir Kozlov (@vnkozlov - Reviewer) ⚠️ Review applies to ead0e611
• Christian Hagedorn (@chhagedorn - Reviewer)

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[bridgekeeper]

👋 Welcome back thartmann! 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]

@TobiHartmann 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:

8333177: Invalid value used for enum Cell in ciTypeFlow::get_start_state

Reviewed-by: kvn, chagedorn

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 16 new commits pushed to the master branch:

• 64bbae7: 8333394: C2: assert(bol->is_Opaque4() || bol->is_OpaqueInitializedAssertionPredicate()) failed: Opaque node of non-null-check or of Initialized Assertion Predicate
• c7495fb: 8333444: Parallel: Inline PSParallelCompact::mark_obj
• 454660d: 8332900: RISC-V: refactor nativeInst_riscv.cpp and macroAssembler_riscv.cpp
• 67d6f3c: 8332905: C2 SuperWord: bad AD file, with RotateRightV and first operand not a pack
• ca30726: 8332866: Crash in ImageIO JPEG decoding when MEM_STATS in enabled
• 29e10e4: 8332547: Unloaded signature classes in DirectMethodHandles
• c7d2a5c: 8314070: javax.print: Support IPP output-bin attribute extension
• d230b30: 8333398: Uncomment the commented test in test/jdk/java/util/jar/JarFile/mrjar/MultiReleaseJarAPI.java
• 1512011: 8332123: [nmt] Move mallocLimit code to the nmt subdir
• 6dac8d6: 8332424: Update IANA Language Subtag Registry to Version 2024-05-16
• ... and 6 more: https://git.openjdk.org/jdk/compare/f0bffbce35bb06e724857e8651dd429c4f9df284...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.

[openjdk]

@TobiHartmann The following label will be automatically applied to this pull request:

• hotspot-compiler

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[mlbridge]

Webrevs

• 01: Full - Incremental (c4d45ca4)
• 00: Full (ead0e611)

[vnkozlov]

This looks correct.

[TobiHartmann]

Thanks for the review, Vladimir!

[TobiHartmann]

Thanks for the review Christian. Your suggestion makes sense!

[chhagedorn]

Looks good, thanks for the update!

[TobiHartmann]

Thanks for the review!

[TobiHartmann]

/integrate

[openjdk]

Going to push as commit 6f690a5.
Since your change was applied there have been 61 commits pushed to the master branch:

• b351b5f: 8331736: C2: Live Node limit exceeded limit after JDK-8316991
• b3f540d: 8332921: Ctrl+C does not call shutdown hooks after JLine upgrade
• 3089412: 8326716: JVMTI spec: clarify what nullptr means for C/C++ developers
• ca93907: 8256828: ostream::print_cr() truncates buffer in copy-through case
• 60ea17e: 8311177: Switching to interpreter only mode in carrier thread can lead to crashes
• 7564949: 8291643: Consider omitting type annotations from type error diagnostics
• 4c09d9f: 8332119: Incorrect IllegalArgumentException for C2 compiled permute kernel
• f7dbb98: 8333086: Using Console.println is unnecessarily slow due to JLine initalization
• 9b3694c: 8319822: Use a linear-time algorithm for assert_different_registers()
• f73922b: 8333235: vmTestbase/nsk/jdb/kill/kill001/kill001.java fails with C1
• ... and 51 more: https://git.openjdk.org/jdk/compare/f0bffbce35bb06e724857e8651dd429c4f9df284...master

Your commit was automatically rebased without conflicts.

[openjdk]

@TobiHartmann Pushed as commit 6f690a5.

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