[libcxx-commits] [PATCH] D112112: [libunwind] Link with -unwindlib=none

[Martin Storsjö via Phabricator via libcxx-commits]

mstorsjo added a comment.

In D112112#3076253 <https://reviews.llvm.org/D112112#3076253>, @hvdijk wrote:

> In D112112#3076215 <https://reviews.llvm.org/D112112#3076215>, @mstorsjo wrote:
>
>> Ah, I see. Can you try by adding `-DCMAKE_C_COMPILER_WORKS=TRUE -DCMAKE_CXX_COMPILER_WORKS=TRUE`? That waives this particular failure.
>
> I tried that at first (for both compiler-rt and libunwind -- I don't think we should be using different workarounds for the two),

Hmm. I used to use `CMAKE_C[XX]_COMPILER_WORKS` for compiler-rt, too, but since 8368e4d54c459fe173d76277f17c632478e91add <https://reviews.llvm.org/rG8368e4d54c459fe173d76277f17c632478e91add> / D91334 <https://reviews.llvm.org/D91334>, compiler-rt/lib/builtins does set `CMAKE_TRY_COMPILE_TARGET_TYPE=STATIC_LIBRARY` (which works fine there, because it doesn't do any linker testing - as it actually only is building a static library), so I no longer need to set those flags there.

> that breaks in a different way:
>
>   CMake Error at cmake/config-ix.cmake:197 (message):
>     Please use architecture with 4 or 8 byte pointers.
>   Call Stack (most recent call first):
>     CMakeLists.txt:251 (include)

That's curious.

If sidestepping this issue a little - if you'd only add those `*_WORKS` flags to libunwind, do things work there too?

When running into this error in compiler-rt, were you pointing cmake at `compiler-rt/lib/builtins` or plain `compiler-rt`? From some quick grepping, it seems like this only would be triggered by the toplevel compiler-rt. In my setups, I first point cmake at `compiler-rt/lib/builtins` and build that, then build libunwind, libcxxabi, libcxx, then after that point it at the root of compiler-rt to build all of it.


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