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8266168: -Wmaybe-uninitialized happens in check_code.c #3787

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@YaSuenag YaSuenag commented Apr 29, 2021

We can see following compiler warning in check_code.c on GCC 11.

/home/ysuenaga/github-forked/jdk/src/java.base/share/native/libverify/check_code.c: In function 'signature_to_fieldtype':
/home/ysuenaga/github-forked/jdk/src/java.base/share/native/libverify/check_code.c:3825:21: warning: 'buffer' may be used uninitialized [-Wmaybe-uninitialized]
 3825 |                     check_and_push(context, buffer, VM_MALLOC_BLK);
      |                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/ysuenaga/github-forked/jdk/src/java.base/share/native/libverify/check_code.c:4144:13: note: by argument 2 of type 'const void *' to 'check_and_push' declared here
 4144 | static void check_and_push(context_type *context, const void *ptr, int kind)
      |             ^~~~~~~~~~~~~~

It is caused by the change in GCC 11. -Wmaybe-uninitialized diagnoses passing pointers or references to uninitialized memory to functions taking const-qualified arguments.

https://gcc.gnu.org/gcc-11/changes.html

check_and_push() has const in its argument, and related functions ( free_block() ) does not modify the argument. We can avoid this issue to use calloc(), and it would not be any side-effect at here.


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  • JDK-8266168: -Wmaybe-uninitialized happens in check_code.c

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👋 Welcome back ysuenaga! 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.

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

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@openjdk openjdk bot added the core-libs core-libs-dev@openjdk.org label Apr 29, 2021
@YaSuenag YaSuenag marked this pull request as ready for review April 29, 2021 13:05
@openjdk openjdk bot added the rfr Pull request is ready for review label Apr 29, 2021
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Webrevs

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YaSuenag commented May 6, 2021

Ping: Could you review this PR? We still see this warning with GCC 11.1.

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LGTM.

I am not aware of any platform where sizeof(char) is not 1, but good to be prepared :)

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openjdk bot commented May 6, 2021

@YaSuenag 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:

8266168: -Wmaybe-uninitialized happens in check_code.c

Reviewed-by: stuefe

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 101 new commits pushed to the master branch:

  • 7835cdb: 8265915: adjust state_unloading_cycle compuation order in nmethod::is_unloading
  • 20ad428: 8180568: Refactor javax/crypto shell tests to plain java tests
  • 138d573: 8262392: Update Mesa 3-D Headers to version 21.0.3
  • 9de62a4: 8266505: Cleanup LibraryCallKit::make_unsafe_address()
  • 1885c83: 8266504: Remove leftovers from BarrierSetAssemblerC1
  • 6018336: 8259316: [REDO] C1/C2 compiler support for blackholes
  • f07bb2f: 8250766: javadoc adds redundant spaces when @see program element is wrapped
  • 61bb6ec: 8266453: Shenandoah: Disable write protections before patching nmethod in nmethod_barrier on MacOSX/AArch64
  • a05e8e2: 8266497: Remove unnecessary EMCP liveness indication
  • 6ba911d: 8266498: Make debug ps() call print_stack
  • ... and 91 more: https://git.openjdk.java.net/jdk/compare/56cde70da271ef5437d5544b3bd9ba26e4148af1...master

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YaSuenag commented May 6, 2021

/integrate

@openjdk openjdk bot closed this May 6, 2021
@openjdk openjdk bot added integrated Pull request has been integrated and removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels May 6, 2021
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openjdk bot commented May 6, 2021

@YaSuenag Since your change was applied there have been 104 commits pushed to the master branch:

Your commit was automatically rebased without conflicts.

Pushed as commit 0f9852c.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

@YaSuenag YaSuenag deleted the JDK-8266168 branch May 6, 2021 14:57
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