[lldb][windows] delay loading liblldb.dll and manually add Python's DLL directory #11571
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lldb/cmake/modules/AddLLDB.cmake
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| target_link_libraries(${name} PRIVATE ${ARG_LINK_LIBS}) | ||
| if(MSVC) |
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This should be WIN32 not MSVC otherwise this will regress if you use a different compiler.
lldb/tools/driver/Driver.cpp
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| // toolchain, therefore the directory might not exist. | ||
| void AddPythonDLLToSearchPath() { | ||
| wchar_t buffer[MAX_PATH]; | ||
| DWORD length = GetModuleFileNameW(NULL, buffer, MAX_PATH); |
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This is risky - the path is possibly a long path (i.e. >MAX_PATH). In such a case, LLDB will be unusable permanently. The path returned is the path used to load, so this is not something we can control.
It is likely best to use GetModuleHandleW and then GetFinalPathNameByHandleW to get the path.
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I was not able to use GetModuleHandleW with GetFinalPathNameByHandleW directly after, there had to be an intermiedary GetModuleFileNameW and it was back to the original problem.
I found this SO thread where others are struggling with this API. I settled with the grow the buffer until it fits solution.
charles-zablit
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lldb/tools/driver/Driver.cpp
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| inline std::wstring GetPathToExecutableW() { | ||
| // Iterate until we max out the Windows max path length (256*2^7 > 32,767). | ||
| static const size_t maximumIterations = 7; | ||
| std::wstring buffer; |
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Why not use std::vector<WCHAR>?
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lldb/tools/driver/Driver.cpp
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| static const size_t maximumIterations = 7; | ||
| std::vector<WCHAR> buffer; | ||
| DWORD bufferSize = MAX_PATH; | ||
| for (size_t i = 0; i < maximumIterations; i++) { |
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I wonder if this is better written as:
| for (size_t i = 0; i < maximumIterations; i++) { | |
| for (size_t i = 0; buffer.size() < 32767; i++) { |
lldb/tools/driver/Driver.cpp
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| // `Swift/Toolchains/x.x.x/usr/bin/lldb.exe`. | ||
| for (int i = 0; i < 5; i++) { | ||
| sys::path::remove_filename(pythonDir); | ||
| } |
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I wonder if we can make this a CMake configuration option for a relative path, and then upstream this.
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Can we support this configuration upstream and add all the necessary support there? |
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Closing this PR now that llvm#162509 is opened. |
This patch delays the load of
python310.dllon Windows, by using MSVC's/DELAYLOADparameter.This allows the use of the
SetDllDirectoryWAPI to manually addC:/toolchain-install-dir/Python-3.10.1to the list of DLL search paths.This patch is part of 2 other PRs which aim at packaging the Embeddable version of Python with the toolchain's installer: