PAL_VirtualUnwindOutOfProc for MacOS #39213
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Add MacOS compact unwind section parsing (__unwind_info) and stepping: SearchCompactEncodingSection, SearchDwarfSection, GetProcInfo, StepWithCompactEncoding*. Add back some (from a previous commit) of the dwarf unwind info parsing functions to use for the dwarf unwind info (__eh_frame section): ReadValue*, ReadULEB128, ReadSLEB128, ReadEncodedPointer, ParseCie, ExtractFde, ExtractProcInfoFromFde. These functions were used and fairly well tested in 3.x. Build libunwind8 source on MacOS for those dwarf unwind info cases.
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Tagging subscribers to this area: @tommcdon |
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@janvorli, @sdmaclea as far as the changes I made to build libunwind8 for MacOS, I hope we can come up with a way to add them without requiring them to be pushed to the libunwind8 repo. I didn't make any changes to the core files only changed CMakeLists.txt and adding some subdirectories (which could be moved out of the libunwind directory). |
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It is not inherently obvious why we wouldn't want to upstream this. Perhaps because MacOS libunwind support is always installed. So there is no need for MacOS support in the libunwind project.
I have mixed feelings about the directory layout. I would wait for @janvorli feedback on the directory style.
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As far as push these changes to the libunwind repo: it would require a lot of work because most of the time the dwarf unwind isn't used so libunwind isn't used. It is the compact/compressed unwind info that is used at lot more and requires the compact "step" code I wrote in remote-unwind.cpp. So most of the new code would have to be ported to the libunwind8 coding conventions, etc. In other words, without the compact format parsing/stepping just building it on macOS doesn't have any benefit. |
The methoddesc's enum memory region code needed add more of the code version manager's data to the coredump.
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Hello @mikem8361! Because this pull request has the p.s. you can customize the way I help with merging this pull request, such as holding this pull request until a specific person approves. Simply @mention me (
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Add MacOS compact unwind section parsing (__unwind_info) and stepping: SearchCompactEncodingSection, SearchDwarfSection, GetProcInfo, StepWithCompactEncoding*.
Add back some (from a previous commit) of the dwarf unwind info parsing functions to use for the dwarf unwind info (__eh_frame section): ReadValue*, ReadULEB128, ReadSLEB128, ReadEncodedPointer, ParseCie, ExtractFde, ExtractProcInfoFromFde. These functions were used and fairly well tested in 3.x.
Build libunwind8 source on MacOS for those dwarf unwind info cases.