8326109: GCC 13 reports maybe-uninitialized warnings for jni.cpp with dtrace enabled

[gnu-andrew]

This is a simple fix that allows newer versions of gcc to build OpenJDK without --disable-warnings-as-errors (i.e. the default)

When dtrace is enabled, the compilation of jni.cpp throws up a number of maybe-uninitialized warnings due to the expansion of the DTRACE_PROBE macros from sdt.hpp e.g.

In file included from /localhome/andrew/projects/openjdk/upstream/jdk11u-dev/src/hotspot/share/prims/jni.cpp:88:
In destructor 'DTraceReturnProbeMark_NewStringUTF::~DTraceReturnProbeMark_NewStringUTF()',
    inlined from '_jstring* jni_NewStringUTF(JNIEnv*, const char*)' at /localhome/andrew/projects/openjdk/upstream/jdk11u-dev/src/hotspot/share/prims/jni.cpp:2524:1:
/home/andrew/builder/11u-dev/hotspot/variant-server/gensrc/dtracefiles/hotspot_jni.h:4179:1: error: 'ret' may be used uninitialized [-Werror=maybe-uninitialized]
 4179 | DTRACE_PROBE1 (hotspot_jni, NewStringUTF__return, arg1)
      | ^~~~~~~~~~~~~
/localhome/andrew/projects/openjdk/upstream/jdk11u-dev/src/hotspot/share/utilities/dtrace.hpp:33:24: note: in definition of macro 'DTRACE_ONLY'
   33 | #define DTRACE_ONLY(x) x
      | ^
/localhome/andrew/projects/openjdk/upstream/jdk11u-dev/src/hotspot/share/prims/jni.cpp:2512:1: note: in expansion of macro 'DT_RETURN_MARK_DECL'
 2512 | DT_RETURN_MARK_DECL(NewStringUTF, jstring
      | ^~~~~~~~~~~~~~~~~~~
/localhome/andrew/projects/openjdk/upstream/jdk11u-dev/src/hotspot/share/prims/jni.cpp:2513:23: note: in expansion of macro 'HOTSPOT_JNI_NEWSTRINGUTF_RETURN'
 2513 | , HOTSPOT_JNI_NEWSTRINGUTF_RETURN(_ret_ref));
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 

I don't see the same on 17u as -Wno-maybe-uninitialized is one of a number of warnings disabled in CompileJvm.gmk. This 11u only patch does the more specific fix of disabling the warning on jni.cpp only and only when dtrace is enabled.

---

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Issue

• JDK-8326109: GCC 13 reports maybe-uninitialized warnings for jni.cpp with dtrace enabled (Bug - P4 - Approved)

Reviewers

• Paul Hohensee (@phohensee - Reviewer)

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[openjdk]

⚠️ @gnu-andrew This change is now ready for you to apply for maintainer approval. This can be done directly in each associated issue or by using the /approval command.

[gnu-andrew]

Thanks Paul.
/approval request Disables a warning which prevents the build from completing in the default configuration (i.e. without --disable-warnings-as-errors). The warning is triggered by SystemTap headers, not JDK code, when DTrace is enabled.

[openjdk]

@gnu-andrew
8326109: The approval request has been created successfully.

[openjdk]

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

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

8326109: GCC 13 reports maybe-uninitialized warnings for jni.cpp with dtrace enabled

Reviewed-by: phh

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 9 new commits pushed to the master branch:

• de3ae6f: 8318468: compiler/tiered/LevelTransitionTest.java fails with -XX:CompileThreshold=100 -XX:TieredStopAtLevel=1
• 38a60d7: 8318983: Fix comment typo in PKCS12Passwd.java
• cc88c3c: 8317307: test/jdk/com/sun/jndi/ldap/LdapPoolTimeoutTest.java fails with ConnectException: Connection timed out: no further information
• ccd4c98: 8319668: Fixup of jar filename typo in BadFactoryTest.sh
• a5e6577: 8315680: java/lang/ref/ReachabilityFenceTest.java should run with -Xbatch
• 92cb5eb: 8319456: jdk/jfr/event/gc/collection/TestGCCauseWith[Serial|Parallel].java : GC cause 'GCLocker Initiated GC' not in the valid causes
• ddc3e41: 8318736: com/sun/jdi/JdwpOnThrowTest.java failed with "transport error 202: bind failed: Address already in use"
• 6ecf198: 8316001: GC: Make TestArrayAllocatorMallocLimit use createTestJvm
• f7cd14c: 8307123: Fix deprecation warnings in DPrinter

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.

[gnu-andrew]

/integrate

[openjdk]

Going to push as commit 382942d.
Since your change was applied there have been 9 commits pushed to the master branch:

• de3ae6f: 8318468: compiler/tiered/LevelTransitionTest.java fails with -XX:CompileThreshold=100 -XX:TieredStopAtLevel=1
• 38a60d7: 8318983: Fix comment typo in PKCS12Passwd.java
• cc88c3c: 8317307: test/jdk/com/sun/jndi/ldap/LdapPoolTimeoutTest.java fails with ConnectException: Connection timed out: no further information
• ccd4c98: 8319668: Fixup of jar filename typo in BadFactoryTest.sh
• a5e6577: 8315680: java/lang/ref/ReachabilityFenceTest.java should run with -Xbatch
• 92cb5eb: 8319456: jdk/jfr/event/gc/collection/TestGCCauseWith[Serial|Parallel].java : GC cause 'GCLocker Initiated GC' not in the valid causes
• ddc3e41: 8318736: com/sun/jdi/JdwpOnThrowTest.java failed with "transport error 202: bind failed: Address already in use"
• 6ecf198: 8316001: GC: Make TestArrayAllocatorMallocLimit use createTestJvm
• f7cd14c: 8307123: Fix deprecation warnings in DPrinter

Your commit was automatically rebased without conflicts.

[openjdk]

@gnu-andrew Pushed as commit 382942d.

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