8293887: AArch64 build failure with GCC 12 due to maybe-uninitialized warning in libfdlibm k_rem_pio2.c #10386

shqking · 2022-09-22T07:02:16Z

This warning seems to be a false positive, because 1) array "fq" with elements from index 0 to "jz" has already been initialized as "fw" at line 290 [1], and 2) variable "jz" should be non-negative from the comment at line 99 [2].

Note-1: GCC warning option -Wmaybe-uninitialized is not a new one. Note-2: x86-64 build with GCC 12 on Ubuntu 22.04 passed in my local test.

This warning is raised only on GCC 12 + AArch64. I suspect it might be some GCC 12 bug, so I reported it to GCC community [3].

Since it involves third party code, I think it's better to suppress the warning by simply disabling this warning option in the makefile.

Testing: Release builds with GCC 9, GCC 11 and GCC 12 passed on Ubuntu 22.04/AArch64 system.

[1] https://github.com/openjdk/jdk/blob/master/src/java.base/share/native/libfdlibm/k_rem_pio2.c#L290
[2] https://github.com/openjdk/jdk/blob/master/src/java.base/share/native/libfdlibm/k_rem_pio2.c#L99
[3] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106992

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Issue

JDK-8293887: AArch64 build failure with GCC 12 due to maybe-uninitialized warning in libfdlibm k_rem_pio2.c

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Erik Joelsson (@erikj79 - Reviewer)
Aleksey Shipilev (@shipilev - Reviewer)
Magnus Ihse Bursie (@magicus - Reviewer)

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Update a local copy of the PR:
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… warning in libfdlibm k_rem_pio2.c This warning seems to be a false positive, because 1) array "fq" with elements from index 0 to "jz" has already been initialized as "fw" at line 290 [1], and 2) variable "jz" should be non-negative from the comment at line 99 [2]. Note-1: GCC warning option -Wmaybe-uninitialized is not a new one. Note-2: x86-64 build with GCC 12 on Ubuntu 22.04 passed in my local test. This warning is raised only on GCC 12 + AArch64. I suspect it might be some GCC 12 bug, so I reported it to GCC community [3]. Since it involves third party code, I think it's better to suppress the warning by simply disabling this warning option in the makefile. Testing: Release builds with GCC 9, GCC 11 and GCC 12 passed on Ubuntu 22.04/AArch64 system. [1] https://github.com/openjdk/jdk/blob/master/src/java.base/share/native/libfdlibm/k_rem_pio2.c#L290 [2] https://github.com/openjdk/jdk/blob/master/src/java.base/share/native/libfdlibm/k_rem_pio2.c#L99 [3] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106992

bridgekeeper · 2022-09-22T07:03:16Z

👋 Welcome back haosun! 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 · 2022-09-22T07:05:35Z

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

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mlbridge · 2022-09-22T07:08:11Z

Webrevs

01: Full - Incremental (22355e68)
00: Full (f745d060)

theRealAph · 2022-09-22T09:35:47Z

make/modules/java.base/lib/CoreLibraries.gmk

@@ -48,7 +48,8 @@ $(eval $(call SetupNativeCompilation, BUILD_LIBFDLIBM, \
    CFLAGS := $(CFLAGS_JDKLIB) $(LIBFDLIBM_CFLAGS), \
    CFLAGS_windows_debug := -DLOGGING, \
    CFLAGS_aix := -qfloat=nomaf, \
-    DISABLED_WARNINGS_gcc := sign-compare misleading-indentation array-bounds, \
+    DISABLED_WARNINGS_gcc := sign-compare misleading-indentation \
+        array-bounds maybe-uninitialized, \


Something like this would be better:

#pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Wmaybe-uninitialized" write(foo, bar, baz); #pragma GCC diagnostic pop

Thanks for your review.

Your mentioned solution should work and we can also enable the pragma only for aarch64 + gcc>=12 condition.
I considered such a solution when preparing this patch.

But I personally prefer to suppress the waring in the makefile, mainly because fdlibm is 3rd party library and we'd better not changing the source code. I think it is a long-standing policy.

Yes, we should not modify 3rd party code.

What you would need is JDK-8294281. If you can hold back this patch for a little while, you'll be able to utilize it instead.

Thanks for your info @magicus.

Updated the code using JDK-8294281 in the latest commit.
Would you mind taking another look? Thanks! @theRealAph @magicus

After JDK-8294281, we can disable the warning options per file. Testing: Release builds with GCC 9, GCC 11 and GCC 12 passed on Ubuntu 22.04/AArch64 system.

openjdk · 2022-09-26T13:00:22Z

@shqking 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:

8293887: AArch64 build failure with GCC 12 due to maybe-uninitialized warning in libfdlibm k_rem_pio2.c

Reviewed-by: erikj, shade, ihse

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 10 new commits pushed to the master branch:

b88ee1e: 6251738: Want a top-level summary page that itemizes all spec documents referenced from javadocs (OEM spec)
aca4276: 8294379: Missing comma after copyright year
1f521a1: 8225012: sanity/client/SwingSet/src/ToolTipDemoTest.java fails on Windows
5ae6bc2: 8234262: Unmask SIGQUIT in a child process
968af74: 8293567: AbstractSplittableWithBrineGenerator: salt has digits that duplicate the marker
36b61c5: 8293872: Make runtime/Thread/ThreadCountLimit.java more robust
2be3158: 4797982: Setting negative size of JSplitPane divider leads to unexpected results.
050eebf: 8294245: Make Compile::print_inlining_stream stack allocated
91a23d7: 8294142: make test should report only on executed tests
169a5d4: 8294193: Files.createDirectories throws FileAlreadyExistsException for a symbolic link whose target is an existing directory

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.

As you do not have Committer status in this project an existing Committer must agree to sponsor your change. Possible candidates are the reviewers of this PR (@erikj79, @shipilev, @magicus) but any other Committer may sponsor as well.

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shipilev

Looks fine to me.

magicus

LGTM

shqking · 2022-09-26T22:18:18Z

Thanks for your review!
/integrate

openjdk · 2022-09-26T22:20:20Z

@shqking
Your change (at version 22355e6) is now ready to be sponsored by a Committer.

nsjian · 2022-09-27T03:07:29Z

/sponsor

openjdk · 2022-09-27T03:09:26Z

Going to push as commit 02ea338.
Since your change was applied there have been 15 commits pushed to the master branch:

49a7347: 8294408: Problemlist runtime/handshake/HandshakeSuspendExitTest.java
aa48705: 8289422: Fix and re-enable vector conditional move
1ddc92f: 8294404: [BACKOUT] JDK-8294142: make test should report only executed tests
1e222bc: 8293462: [macos] app image signature invalid when creating DMG or PKG from post processed signed image
43eff2b: 8272687: Replace StringBuffer with StringBuilder in RuleBasedCollator
b88ee1e: 6251738: Want a top-level summary page that itemizes all spec documents referenced from javadocs (OEM spec)
aca4276: 8294379: Missing comma after copyright year
1f521a1: 8225012: sanity/client/SwingSet/src/ToolTipDemoTest.java fails on Windows
5ae6bc2: 8234262: Unmask SIGQUIT in a child process
968af74: 8293567: AbstractSplittableWithBrineGenerator: salt has digits that duplicate the marker
... and 5 more: https://git.openjdk.org/jdk/compare/3675f4c2afd10b5042948fc79e62caee5f3874ce...master

Your commit was automatically rebased without conflicts.

openjdk · 2022-09-27T03:09:48Z

@nsjian @shqking Pushed as commit 02ea338.

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

openjdk bot added the rfr Pull request is ready for review label Sep 22, 2022

openjdk bot added build build-dev@openjdk.org core-libs core-libs-dev@openjdk.org labels Sep 22, 2022

theRealAph reviewed Sep 22, 2022

View reviewed changes

shqking added 2 commits September 26, 2022 01:25

Merge branch 'master' into 8293887-gcc12-fdlibm

85cb850

Disable the warning option per file

22355e6

After JDK-8294281, we can disable the warning options per file. Testing: Release builds with GCC 9, GCC 11 and GCC 12 passed on Ubuntu 22.04/AArch64 system.

erikj79 approved these changes Sep 26, 2022

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openjdk bot added the ready Pull request is ready to be integrated label Sep 26, 2022

shipilev approved these changes Sep 26, 2022

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magicus approved these changes Sep 26, 2022

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openjdk bot added the sponsor Pull request is ready to be sponsored label Sep 26, 2022

openjdk bot added the integrated Pull request has been integrated label Sep 27, 2022

openjdk bot closed this Sep 27, 2022

openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review sponsor Pull request is ready to be sponsored labels Sep 27, 2022

shqking deleted the 8293887-gcc12-fdlibm branch September 27, 2022 03:18

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8293887: AArch64 build failure with GCC 12 due to maybe-uninitialized warning in libfdlibm k_rem_pio2.c #10386

8293887: AArch64 build failure with GCC 12 due to maybe-uninitialized warning in libfdlibm k_rem_pio2.c #10386

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8293887: AArch64 build failure with GCC 12 due to maybe-uninitialized warning in libfdlibm k_rem_pio2.c #10386

8293887: AArch64 build failure with GCC 12 due to maybe-uninitialized warning in libfdlibm k_rem_pio2.c #10386

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