8275405: Linking error for classes with lambda template parameters and virtual functions

[stefank]

We encountered the following linking error when trying to build Generational ZGC on Windows:

jvm.exp : error LNK2001: unresolved external symbol "const ZBasicOopIterateClosure<class <lambda_9767402e468f9fc654281195f9700e48> >::`vftable'" (??_7?$ZBasicOopIterateClosure@V<lambda_9767402e468f9fc654281195f9700e48>@@@@6B@)

I narrowed this down to a simple reproducer, which doesn't link when built through the HotSpot build system:

#include <functional>
std::function<void()> = [](){};

I found that we have a line in our make files that filters out symbols that contain the string vftable (though it checks the mangled name, so a bit hard to find):

else ifeq ($(call isTargetOs, windows), true)
  DUMP_SYMBOLS_CMD := $(DUMPBIN) -symbols *.obj
  FILTER_SYMBOLS_AWK_SCRIPT := \
      '{ \
        if ($$7 ~ /??_7.*@@6B@/ && $$7 !~ /type_info/) print $$7; \
      }'

The following line prints the vftable symbol if it doesn't contain the string 'type_info':
if ($$7 ~ /??_7.*@@6b@/ && $$7 !~ /type_info/) print $$7;

The printed values are added to a list of symbols that get filtered out of the mapfile, which is then passed to the linker.

I can get the code to link if I add a second exception for vftable symbols containing the string 'lambda':
if ($$7 ~ /??_7.*@@6b@/ && $$7 !~ /type_info/ && $$7 !~ /lambda/) print $$7;

I did an additional experiment where I completely removed this filtering of vftable symbols. When I did that the linker complained that we used more than 64K symbols.

---

Progress

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Issue

• JDK-8275405: Linking error for classes with lambda template parameters and virtual functions

Reviewers

• Magnus Ihse Bursie (@magicus - Reviewer) ⚠️ Review applies to 54a353f
• Per Liden (@pliden - Reviewer)

Reviewing

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[stefank]

/label hotspot build

[bridgekeeper]

👋 Welcome back stefank! 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]

@stefank
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[mlbridge]

Webrevs

• 01: Full - Incremental (fddb8be6)
• 00: Full (54a353f3)

[magicus]

Looks good to me.

[magicus]

Suggested change

	# the lambda type as a template parameter. The usage of those classes wont
	# the lambda type as a template parameter. The usage of those classes won't

[openjdk]

@stefank 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:

8275405: Linking error for classes with lambda template parameters and virtual functions

Reviewed-by: ihse, pliden

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 5 new commits pushed to the master branch:

• a91a0a5: 8233724: Remove -Wc++14-compat warning suppression in operator_new.cpp
• 1271fbf: 8248584: Enable CHECK_UNHANDLED_OOPS for Windows fastdebug builds
• 135cf3c: 8275439: Remove PrintVtableStats
• 50a5723: 8274910: Compile in G1 evacuation failure injection code based on define
• 5454a76: 8275273: Add missing HtmlStyle documentation

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.

[pliden]

Looks good to me!

[stefank]

Thanks for reviewing!
/integrate

[openjdk]

Going to push as commit 09f5235.
Since your change was applied there have been 17 commits pushed to the master branch:

• a120937: 8274988: G1: refine G1SegmentedArrayAllocOptions and G1CardSetAllocOptions
• c7a80e6: 8275607: G1: G1CardSetAllocator::drop_all needs to call G1SegmentedArray::drop_all
• af7c56b: 8275167: x86 intrinsic for unsignedMultiplyHigh
• cea3f01: 8275666: serviceability/jvmti/GetObjectSizeClass.java shouldn't have vm.flagless
• d1e3ca4: 8233558: [TESTBUG] WindowOwnedByEmbeddedFrameTest.java fails on macos
• 913f928: 8273507: Convert test/jdk/java/nio/channels/Channels/TransferTo.java to TestNG test
• 0021a2f: 8275449: Add linux-aarch64-zero build profile
• 46b5bfb: 8233648: [TESTBUG] DefaultMenuBarTest.java failing on macos
• bbc6061: 8272614: Unused parameters in MethodHandleNatives linking methods
• 7e28bdd: 8275055: Improve HeapRegionRemSet::split_card()
• ... and 7 more: https://git.openjdk.java.net/jdk/compare/bd0bed71e55f0bb8b4619495c79184f94c0701fb...master

Your commit was automatically rebased without conflicts.

[openjdk]

@stefank Pushed as commit 09f5235.

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