[lldb-dev] Need help with failing LLDB tests on Windows

Ted Woodward via lldb-dev lldb-dev at lists.llvm.org
Wed Nov 4 12:05:17 PST 2020


To expand a bit on what Pavel has written, the lldb module should be in <install>\lib\site-packages\lldb . In that directory is a file, _lldb.pyd, that should be a copy of <install>\bin\liblldb.dll .

Do both files exist? Is _lldb.pyd a copy of liblldb.dll?
See function create_relative_symlink in llvm-project/lldb/CMakeLists.txt for the copy (on non-unix hosts) procedure.

Did you recently change your version of swig? LLDB requires swig 2, but, as you pointed out last year, there are issues with some versions of swig. We use 4.0.1 on Windows.

> -----Original Message-----
> From: lldb-dev <lldb-dev-bounces at lists.llvm.org> On Behalf Of Pavel Labath
> via lldb-dev
> Sent: Wednesday, November 4, 2020 2:49 AM
> To: Adrian McCarthy <amccarth at google.com>; LLDB <lldb-
> dev at lists.llvm.org>
> Subject: [EXT] Re: [lldb-dev] Need help with failing LLDB tests on Windows
>
> On 04/11/2020 01:53, Adrian McCarthy via lldb-dev wrote:
> > For the past couple weeks, I've been trying to figure out why
> > approximately 900+ LLDB tests have been failing for me on my local
> > Windows builds.  Bisect turned up nothing--the "good" version that was
> > working for me no longer works.  Since nobody else seems to be seeing
> > these failures, I suspect it's something environmental.
> >
> > There are three categories of errors.  I'm currently focused on
> > failures that look like this:
> >
> >     FAIL: lldb-api :: lang/objc/unicode-string/TestUnicodeString.py (732
> >     of 2180)
> >     ******************** TEST 'lldb-api ::
> >     lang/objc/unicode-string/TestUnicodeString.py' FAILED
> >     ********************
> >     Script:
> >     --
> >     C:/Program Files/Python38/python.exe
> >     D:/src/llvm/llvm-project/lldb\test\API\dotest.py -S nm -u CXXFLAGS
> >     -u CFLAGS --enable-crash-dialog --env
> >     LLVM_LIBS_DIR=D:/src/llvm/build/ninja_dbg/./lib --arch x86_64
> >     --build-dir D:/src/llvm/build/ninja_dbg/lldb-test-build.noindex -s
> >     D:/src/llvm/build/ninja_dbg/lldb-test-traces --lldb-module-cache-dir
> >     D:/src/llvm/build/ninja_dbg/lldb-test-build.noindex/module-cache-
> lldb\lldb-api
> >     --clang-module-cache-dir
> >     D:/src/llvm/build/ninja_dbg/lldb-test-build.noindex/module-cache-
> clang\lldb-api
> >     --executable D:/src/llvm/build/ninja_dbg/./bin/lldb.exe --compiler
> >     D:/src/llvm/build/ninja_dbg/bin/clang.exe --dsymutil
> >     D:/src/llvm/build/ninja_dbg/./bin/dsymutil.exe --filecheck
> >     D:/src/llvm/build/ninja_dbg/./bin/FileCheck.exe --yaml2obj
> >     D:/src/llvm/build/ninja_dbg/./bin/yaml2obj.exe --lldb-libs-dir
> >     D:/src/llvm/build/ninja_dbg/./lib
> >     D:\src\llvm\llvm-project\lldb\test\API\lang\objc\unicode-string -p
> >     TestUnicodeString.py
> >     --
> >     Exit Code: 1
> >
> >     Command Output (stdout):
> >     --
> >     lldb version 12.0.0 (https://github.com/llvm/llvm-project.git
> >     <https://github.com/llvm/llvm-project.git> revision
> >     0fdcd1ae1c988fa19d0c97e99999e8678b93a0da)
> >        clang revision 0fdcd1ae1c988fa19d0c97e99999e8678b93a0da
> >        llvm revision 0fdcd1ae1c988fa19d0c97e99999e8678b93a0da
> >
> >     --
> >     Command Output (stderr):
> >     --
> >     Traceback (most recent call last):
> >        File
> >     "D:\src\llvm\build\ninja_dbg\Lib\site-packages\lldb\__init__.py",
> >     line 35, in <module>
> >          import _lldb
> >     ModuleNotFoundError: No module named '_lldb'
> >
> >     During handling of the above exception, another exception occurred:
> >
> >     Traceback (most recent call last):
> >        File "D:/src/llvm/llvm-project/lldb\test\API\dotest.py", line 7,
> >     in <module>
> >          lldbsuite.test.run_suite()
> >        File
> >     "D:\src\llvm\llvm-
> project\lldb\packages\Python\lldbsuite\test\dotest.py",
> >     line 874, in run_suite
> >          import lldb
> >        File
> >     "D:\src\llvm\build\ninja_dbg\Lib\site-packages\lldb\__init__.py",
> >     line 38, in <module>
> >          from . import _lldb
> >     ImportError: cannot import name '_lldb' from partially initialized
> >     module 'lldb' (most likely due to a circular import)
> >     (D:\src\llvm\build\ninja_dbg\Lib\site-packages\lldb\__init__.py)
> >
> >
> > It looks like the code in question is generated by Swig (so perhaps it
> > depends on the version of Swig?).  The relevant bit seems to be:
> >
> >     try:
> >          # Try an absolute import first.  If we're being loaded from lldb,
> >          # _lldb should be a built-in module.
> >          import _lldb
> >     except ImportError:
> >          # Relative import should work if we are being loaded by Python.
> >     from . import _lldb
> >
> >
> > I don't have much background in Python modules or how Swig produces
> > the bindings.  It seems suspicious to me that both import attempts are
> > failing (and that we need two).
>
> The reason behind the two imports is that lldb+python have two ways of
> loading each other, depending on who is "on top".
>
> If you're starting with a c++ program (e.g. lldb driver), then the (lib)lldb library
> will be loaded first. It will register itself as a "builtin" python module so that
> "import _lldb" loads _it_, instead of trying to load another copy of lldb.
>
> OTOH, if we are starting from python (like the dotests do), then there is no
> builtin module, and we want to use the second import statement to load lldb
> relative to the __init__.py location.
>
> The fact that the selection of the two methods is implemented by catching
> the exceptions from the first attempt is not ideal. It's possible this could be
> implemented differently (we'd need to find some other way to determine
> which scenario are we in). However, I don't think that will fix the problem
> you're running into.
>
> Regarding python3.8+windows, we also have this
> <https://bugs.llvm.org/show_bug.cgi?id=46891> bug open, but that also
> doesn't sound like the same issue.
>
> BTW, this particular piece of code comes from
> lldb/bindings/python/python.swig, so it is fairly easy to change that.
>
> >  I'm hoping someone can offer some clues  about what's going on here
> >and how it's supposed to work.  Is the hint  about an import cycle
> >relevant or a red herring?
>
> It sounds like a red herring. I get the same error (on linux+python3.8) if I
> delete _lldb.so. So it sounds to me like python is having trouble finding the
> native module (either it's not there or it has wrong debug-ness).
>
> It's also good to check whether you are able to use python scripting from
> inside the lldb driver (e.g. lldb -o "script 1+1").
>
> pl
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