[clangd-dev] [cfe-dev] Random non-reproducible errors in ClangdTests

Kirill Bobyrev via clangd-dev clangd-dev at lists.llvm.org
Thu Sep 6 03:36:38 PDT 2018


Thanks for the information!

I was able to reproduce many failures in tests using TSan and MSan. I'm
attaching logs for TSan for this particular test that was originally
mentioned (WorkspaceSymbolsTest.Namespaces): it looks like a data race in
Trace and TUScheduler. The pattern looks to be the same for all other tests.

+CC Ilya who is knowledgeable about TUScheduler.

I will attach stdout logs of the test failure and whole TSan output.

Kind regards,
Kirill

 thread-sanitizer.logs
<https://drive.google.com/file/d/1D51ldaFyZgJrqugmLlCnIoCe1EsetRC2/view?usp=drive_web>


On Thu, Sep 6, 2018 at 7:54 AM Mikael Holmén <mikael.holmen at ericsson.com>
wrote:

> Hi,
>
> On 09/05/2018 10:55 PM, Kirill Bobyrev via cfe-dev wrote:
> > Hi Mikael,
> >
> > Thanks for pointing that out! Could you share information about what
> > compiler + system you used to build and run tests?
>
> I've seen the failures when compiling with clang 3.6.0 on RHEL 6.9 as
> well as gcc 5.4.0 on SLED 11.2.
>
> The valgrind run was made on a binary compiled with clang 3.6.0 on
> Ubuntu 14.04.
>
> > Sometimes, UB is
> > relatively easy to reproduce using the same setup.
> >
> > As Mehmet mentioned, it looks that there might be uninitialised variable
> > given the Valgrind log that you provided.
> >
> > Could you please attach the whole log so that it would be easier for us
> > to understand the cause of problem(s)?
>
> Sure!
>
> Thanks,
> Mikael
>
> >
> > +clangd-dev
> >
> > Kind regards,
> > Kirill
> >
> >> On 5 Sep 2018, at 17:39, Mehmet Erol Sanliturk via cfe-dev
> >> <cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>> wrote:
> >>
> >>
> >>
> >> On Wed, Sep 5, 2018 at 4:19 PM, Mikael Holmén via
> >> cfe-dev<cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>>wrote:
> >>
> >>     Hi,
> >>
> >>     For a while now we randomly see failures when running the
> >>     ClangdTests test.
> >>
> >>     E.g the below but sometimes other failures:
> >>
> >>     --------
> >>     FAIL: Extra Tools Unit Tests ::
> >>     clangd/./ClangdTests/WorkspaceSymbolsTest.Namespaces (16172 of
> 39758)
> >>     ******************** TEST 'Extra Tools Unit Tests ::
> >>     clangd/./ClangdTests/WorkspaceSymbolsTest.Namespaces' FAILED
> >>     ********************
> >>     Note: Google Test filter = WorkspaceSymbolsTest.Namespaces
> >>     [==========] Running 1 test from 1 test case.
> >>     [----------] Global test environment set-up.
> >>     [----------] 1 test from WorkspaceSymbolsTest
> >>     [ RUN      ] WorkspaceSymbolsTest.Namespaces
> >>
>  ../tools/clang/tools/extra/unittests/clangd/FindSymbolsTests.cpp:151:
> >>     Failure
> >>     Value of: getSymbols("a")
> >>     Expected: has 4 elements and there exists some permutation of
> >>     elements such that:
> >>      - element #0 (named "ans1") and (in container ""), and
> >>      - element #1 (named "ai1") and (in container "ans1"), and
> >>      - element #2 (named "ans2") and (in container "ans1"), and
> >>      - element #3 (named "ai2") and (in container "ans1::ans2")
> >>     Actual: {}
> >>
>  ../tools/clang/tools/extra/unittests/clangd/FindSymbolsTests.cpp:153:
> >>     Failure
> >>     Value of: getSymbols("::")
> >>     Expected: has 1 element that (named "ans1") and (in container "")
> >>     Actual: {}
> >>
>  ../tools/clang/tools/extra/unittests/clangd/FindSymbolsTests.cpp:155:
> >>     Failure
> >>     Value of: getSymbols("::a")
> >>     Expected: has 1 element that (named "ans1") and (in container "")
> >>     Actual: {}
> >>
>  ../tools/clang/tools/extra/unittests/clangd/FindSymbolsTests.cpp:158:
> >>     Failure
> >>     Value of: getSymbols("ans1::")
> >>     Expected: has 2 elements and there exists some permutation of
> >>     elements such that:
> >>      - element #0 (named "ai1") and (in container "ans1"), and
> >>      - element #1 (named "ans2") and (in container "ans1")
> >>     Actual: {}
> >>
>  ../tools/clang/tools/extra/unittests/clangd/FindSymbolsTests.cpp:160:
> >>     Failure
> >>     Value of: getSymbols("::ans1")
> >>     Expected: has 1 element that (named "ans1") and (in container "")
> >>     Actual: {}
> >>
>  ../tools/clang/tools/extra/unittests/clangd/FindSymbolsTests.cpp:163:
> >>     Failure
> >>     Value of: getSymbols("::ans1::")
> >>     Expected: has 2 elements and there exists some permutation of
> >>     elements such that:
> >>      - element #0 (named "ai1") and (in container "ans1"), and
> >>      - element #1 (named "ans2") and (in container "ans1")
> >>     Actual: {}
> >>
>  ../tools/clang/tools/extra/unittests/clangd/FindSymbolsTests.cpp:165:
> >>     Failure
> >>     Value of: getSymbols("::ans1::ans2")
> >>     Expected: has 1 element that (named "ans2") and (in container
> "ans1")
> >>     Actual: {}
> >>
>  ../tools/clang/tools/extra/unittests/clangd/FindSymbolsTests.cpp:167:
> >>     Failure
> >>     Value of: getSymbols("::ans1::ans2::")
> >>     Expected: has 1 element that (named "ai2") and (in container
> >>     "ans1::ans2")
> >>     Actual: {}
> >>     [  FAILED  ] WorkspaceSymbolsTest.Namespaces (39 ms)
> >>     [----------] 1 test from WorkspaceSymbolsTest (39 ms total)
> >>
> >>     [----------] Global test environment tear-down
> >>     [==========] 1 test from 1 test case ran. (40 ms total)
> >>     [  PASSED  ] 0 tests.
> >>     [  FAILED  ] 1 test, listed below:
> >>     [  FAILED  ] WorkspaceSymbolsTest.Namespaces
> >>
> >>      1 FAILED TEST
> >>
> >>
> >>     It can fail and then at once pass again so something funny is
> >>     going on.
> >>
> >>
> >>     I ran valgrind on ClangdTests and then I got a bunch of
> >>     complaints, the first being:
> >>
> >>
> >>     [ RUN      ] ClangdVFSTest.SearchLibDir
> >>     Updating file /clangd-test/foo.cpp with command [/clangd-test]
> >>     clang -ffreestanding -xc++ -target x86_64-linux-unknown -m64
> >>     --gcc-toolchain=/randomusr -stdlib=libstdc++ /clangd-test/foo.cpp
> >>
>  -resource-dir=/data/repo/llvm-patch/build-all/tools/clang/tools/extra/unittests/clangd/../lib/clang/8.0.0
> >>     Preamble for file /clangd-test/foo.cpp cannot be reused.
> >>     Attempting to rebuild it.
> >>     Built preamble of size 175020 for file /clangd-test/foo.cpp
> >>     ==14605== Thread 2 worker:foo.cpp:
> >>     ==14605== Conditional jump or move depends on uninitialised value(s)
> >>     ==14605==    at 0xCDF8A6:
> >>     clang::Sema::SetCtorInitializers(clang::CXXConstructorDecl*, bool,
> >>     llvm::ArrayRef<clang::CXXCtorInitializer*>) (in
> >>
>  /data/repo/llvm-patch/build-all/tools/clang/tools/extra/unittests/clangd/ClangdTests)
> >>     ==14605==    by 0xD01CB9:
> >>     clang::Sema::DefineImplicitDefaultConstructor(clang::SourceLocation,
> >>     clang::CXXConstructorDecl*) (in
> >>
>  /data/repo/llvm-patch/build-all/tools/clang/tools/extra/unittests/clangd/ClangdTests)
> >>     ==14605==    by 0xEA3B93:
> >>     PerformConstructorInitialization(clang::Sema&,
> >>     clang::InitializedEntity const&, clang::InitializationKind const&,
> >>     llvm::MutableArrayRef<clang::Expr*>,
> >>     clang::InitializationSequence::Step const&, bool&, bool, bool,
> >>     clang::SourceLocation, clang::SourceLocation) (in
> >>
>  /data/repo/llvm-patch/build-all/tools/clang/tools/extra/unittests/clangd/ClangdTests)
> >>     ==14605==    by 0xE9AA3F:
> >>     clang::InitializationSequence::Perform(clang::Sema&,
> >>     clang::InitializedEntity const&, clang::InitializationKind const&,
> >>     llvm::MutableArrayRef<clang::Expr*>, clang::QualType*) (in
> >>
>  /data/repo/llvm-patch/build-all/tools/clang/tools/extra/unittests/clangd/ClangdTests)
> >>     ==14605==    by 0xBFA3C4:
> >>     clang::Sema::ActOnUninitializedDecl(clang::Decl*) (in
> >>
>  /data/repo/llvm-patch/build-all/tools/clang/tools/extra/unittests/clangd/ClangdTests)
> >>     ==14605==    by 0x13C5EFF:
> >>
>  clang::Parser::ParseDeclarationAfterDeclaratorAndAttributes(clang::Declarator&,
> >>     clang::Parser::ParsedTemplateInfo const&,
> >>     clang::Parser::ForRangeInit*) (in
> >>
>  /data/repo/llvm-patch/build-all/tools/clang/tools/extra/unittests/clangd/ClangdTests)
> >>     ==14605==    by 0x13C40B7:
> >>     clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&,
> >>     clang::DeclaratorContext, clang::SourceLocation*,
> >>     clang::Parser::ForRangeInit*) (in
> >>
>  /data/repo/llvm-patch/build-all/tools/clang/tools/extra/unittests/clangd/ClangdTests)
> >>     ==14605==    by 0x13AAF5B:
> >>
>  clang::Parser::ParseDeclOrFunctionDefInternal(clang::Parser::ParsedAttributesWithRange&,
> >>     clang::ParsingDeclSpec&, clang::AccessSpecifier) (in
> >>
>  /data/repo/llvm-patch/build-all/tools/clang/tools/extra/unittests/clangd/ClangdTests)
> >>     ==14605==    by 0x13AAA1D:
> >>
>  clang::Parser::ParseDeclarationOrFunctionDefinition(clang::Parser::ParsedAttributesWithRange&,
> >>     clang::ParsingDeclSpec*, clang::AccessSpecifier) (in
> >>
>  /data/repo/llvm-patch/build-all/tools/clang/tools/extra/unittests/clangd/ClangdTests)
> >>     ==14605==    by 0x13A9861:
> >>
>  clang::Parser::ParseExternalDeclaration(clang::Parser::ParsedAttributesWithRange&,
> >>     clang::ParsingDeclSpec*) (in
> >>
>  /data/repo/llvm-patch/build-all/tools/clang/tools/extra/unittests/clangd/ClangdTests)
> >>     ==14605==    by 0x13A8629:
> >>
>  clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&)
> >>     (in
> >>
>  /data/repo/llvm-patch/build-all/tools/clang/tools/extra/unittests/clangd/ClangdTests)
> >>     ==14605==    by 0x13A840F:
> >>
>  clang::Parser::ParseFirstTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&)
> >>     (in
> >>
>  /data/repo/llvm-patch/build-all/tools/clang/tools/extra/unittests/clangd/ClangdTests)
> >>     ==14605==
> >>     Updating file /clangd-test/foo.cpp with command [/clangd-test]
> >>     clang -ffreestanding -xc++ -target x86_64-linux-unknown -m64
> >>     --gcc-toolchain=/randomusr -stdlib=libstdc++ /clangd-test/foo.cpp
> >>
>  -resource-dir=/data/repo/llvm-patch/build-all/tools/clang/tools/extra/unittests/clangd/../lib/clang/8.0.0
> >>     Reusing preamble for file /clangd-test/foo.cpp
> >>     [       OK ] ClangdVFSTest.SearchLibDir (952 ms)
> >>
> >>
> >>
> >>     It's not obvious to me what the problem really is. Does anyone
> >>     here have a clue?
> >>
> >>     Regards,
> >>     Mikael
> >>     _______________________________________________
> >>
> >>
> >>
> >>
> >>
> >> One reason of non-reproducible errors in a program is mainly
> >> "uninitialized variables" .
> >> These variables uses whatever remains in the memory from previous
> >> allocations and used by the new program .
> >> Therefore when these values are used , program behavior is unexpected .
> >>
> >>
> >> Another may be "array index showing outside of an array" . Especially
> >> in loops , if loop passes array boundaries toward up or down  .
> >> Or , when a value is directly used to index an array , but it is out
> >> of bounds .
> >>
> >>
> >> The above reasons are not , "all" , but "some" .
> >>
> >>
> >>
> >>
> >> Mehmet Erol Sanliturk
> >>
> >>
> >>
> >>
> >>
> >> _______________________________________________
> >> cfe-dev mailing list
> >> cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>
> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
> >
> >
> >
> > _______________________________________________
> > cfe-dev mailing list
> > cfe-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
> >
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/clangd-dev/attachments/20180906/f2dc7ec4/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: stdout-clangd-thread-sanitizer.logs
Type: application/octet-stream
Size: 1344 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/clangd-dev/attachments/20180906/f2dc7ec4/attachment-0001.obj>


More information about the clangd-dev mailing list