[libcxx-commits] [PATCH] D99913: [SystemZ][z/OS] Modify cxxabi to be compatible with existing z/OS runtime

[Muiez Ahmed via Phabricator via libcxx-commits]

muiez marked an inline comment as done.
muiez added inline comments.


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Comment at: libcxxabi/src/CMakeLists.txt:52
+  list(APPEND LIBCXXABI_HEADERS
+    ${LLVM_EXTERNAL_UNWIND_SOURCE_DIR}/unwind.h
+  )
----------------
ldionne wrote:
> Where is `LLVM_EXTERNAL_UNWIND_SOURCE_DIR ` defined? I just want to make sure we're not introducing yet another way of building libc++/libc++abi using external magically provided headers, since that roughly means it's going to be not supported officially from the start.
> 
> Is there a reason why we aren't using LLVM's libunwind in the tree as we normally do?
I updated the revision to add the definition of `LLVM_EXTERNAL_UNWIND_SOURCE_DIR` to a zOS.cmake file.

On z/OS, the unwind library is unique from the one provided in LLVM. It needs to interact with undocumented parts of LE.  For the purposes of libc++abi, the unwind library is an external library that is not part of the standard C runtime. The build needs to add the -I to find the header and -L/-l to find the library. 

A subsequent PR would be made to support the unwinder as an external project.



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  https://reviews.llvm.org/D99913/new/

https://reviews.llvm.org/D99913