8291633: Build failures with GCC 11, Alpine 3 due to incompatible casts from nullptr

[shipilev]

Looks like GCC and musl that ship in new Alpine 3.15 highlight that some casts from NULL and nullptr are risky/illegal.

They fall into three categories:

• explicitly casting NULL to integral type; we can and should use NULL_WORD in these cases, like the rest of Hotspot does;
• using NULL in ternary expression when another side is integral type, thus implicitly casting it;
• reinterpret_cast-ing NULL to pointer type -- this is dangerous and rightfully breaks; we can use static_cast instead.

Additional testing:

• Linux x86_64 {release, fastdebug, slowdebug} build with Alpine 3.15, GCC 11.2.1
• Linux x86_64 fastdebug tier1 with GCC 9.3.0

---

Progress

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Issue

• JDK-8291633: Build failures with GCC 11, Alpine 3 due to incompatible casts from nullptr

Reviewers

• Thomas Stuefe (@tstuefe - Reviewer) ⚠️ Review applies to 59f92b41
• Matthias Baesken (@MBaesken - Reviewer) ⚠️ Review applies to 59f92b41
• Jie Fu (@DamonFool - Reviewer)

Reviewing

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[openjdk]

@shipilev The following labels will be automatically applied to this pull request:

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[mlbridge]

Webrevs

• 01: Full - Incremental (3d3dbc3c)
• 00: Full (59f92b41)

[tstuefe]

LGTM

[openjdk]

@shipilev 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:

8291633: Build failures with GCC 11, Alpine 3 due to incompatible casts from nullptr

Reviewed-by: stuefe, mbaesken, jiefu

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 8 new commits pushed to the master branch:

• 0971d34: Merge
• 54c093a: 8291524: jdk/jfr/event/runtime/TestClassLoaderStatsEvent.java Value not equal to 2, field='hiddenClassCount', value='0'
• 1d16c91: 8291512: Snippetize modules API examples
• 0ae8341: 8290908: misc tests fail: assert(!thread->owns_locks()) failed: must release all locks when leaving VM
• 5acf2d7: 8291578: Remove JMX related tests from ProblemList-svc-vthreads.txt
• a6564d4: 8291650: Add delay to ClassUnloadEventTest before exiting to give time for JVM to send all events before VMDeath
• af76c0c: 8291654: AArch64: assert from JDK-8287393 causes crashes
• a9db5bb: 8291626: Remove Mutex::contains as it is unused

Please see this link for an up-to-date comparison between the source branch of this pull request and the master branch.
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.

[MBaesken]

Looks good to me, thanks for looking into it.

[shipilev]

Thank you! If there are no other reviews, I'll be integrating this soon.

[DamonFool]

Thank you! If there are no other reviews, I'll be integrating this soon.

Maybe, we'd better update the copyright year of src/hotspot/cpu/x86/interpreterRT_x86_64.cpp before integration.
Thanks.

[shipilev]

Maybe, we'd better update the copyright year of src/hotspot/cpu/x86/interpreterRT_x86_64.cpp before integration. Thanks.

Did so in new commit.

[DamonFool]

Thanks for the update.
LGTM

[shipilev]

/integrate

[openjdk]

Going to push as commit c89556f.
Since your change was applied there have been 12 commits pushed to the master branch:

• 4d6e6f6: 8291822: ARM32: Build errors with GCC 11 in frame::saved_oop_result
• e52a340: 8290488: IBM864 character encoding implementation bug
• af529be: 8285836: sun/net/www/http/KeepAliveCache/KeepAliveProperty.java failed with "RuntimeException: Failed in server"
• b7d2bde: 8291733: Remove JFR events that expose hashtable
• 0971d34: Merge
• 54c093a: 8291524: jdk/jfr/event/runtime/TestClassLoaderStatsEvent.java Value not equal to 2, field='hiddenClassCount', value='0'
• 1d16c91: 8291512: Snippetize modules API examples
• 0ae8341: 8290908: misc tests fail: assert(!thread->owns_locks()) failed: must release all locks when leaving VM
• 5acf2d7: 8291578: Remove JMX related tests from ProblemList-svc-vthreads.txt
• a6564d4: 8291650: Add delay to ClassUnloadEventTest before exiting to give time for JVM to send all events before VMDeath
• ... and 2 more: https://git.openjdk.org/jdk/compare/a2cff2634cdaa0fa7ba2a1acd951d6f521f59f6d...master

Your commit was automatically rebased without conflicts.

[openjdk]

@shipilev Pushed as commit c89556f.

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