missing __atomic_load_8 etc. symbols

Hi!

While feeding back a pkgsrc patch for compiler-rt, upstream asked me
about a compile error they're seeing when testing. I guess it's about
the latest git head of compiler-rt.

When building on NetBSD 10/x86_64, they are seeing:

/usr/bin/ld: /usr/bin/ld: DWARF error: invalid or unhandled FORM value: 0x25
compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.i386.dir/sanitizer_libignore.cpp.o: in function `__sanitizer::LibIgnore::AddIgnoredLibrary(char const*)':
sanitizer_libignore.cpp:(.text._ZN11__sanitizer9LibIgnore17AddIgnoredLibraryEPKc+0x31): undefined reference to `__atomic_load_8'
/usr/bin/ld: sanitizer_libignore.cpp:(.text._ZN11__sanitizer9LibIgnore17AddIgnoredLibraryEPKc+0x98): undefined reference to `__atomic_compare_exchange_8'
/usr/bin/ld: sanitizer_libignore.cpp:(.text._ZN11__sanitizer9LibIgnore17AddIgnoredLibraryEPKc+0xf1): undefined reference to `__atomic_compare_exchange_8'
/usr/bin/ld: sanitizer_libignore.cpp:(.text._ZN11__sanitizer9LibIgnore17AddIgnoredLibraryEPKc+0x138): undefined reference to `__atomic_compare_exchange_8'
/usr/bin/ld: sanitizer_libignore.cpp:(.text._ZN11__sanitizer9LibIgnore17AddIgnoredLibraryEPKc+0x15a): undefined reference to `__atomic_load_8'
/usr/bin/ld: sanitizer_libignore.cpp:(.text._ZN11__sanitizer9LibIgnore17AddIgnoredLibraryEPKc+0x1cf): undefined reference to `__atomic_load_8'
/usr/bin/ld: sanitizer_libignore.cpp:(.text._ZN11__sanitizer9LibIgnore17AddIgnoredLibraryEPKc+0x222): undefined reference to `__atomic_compare_exchange_8'
/usr/bin/ld: sanitizer_libignore.cpp:(.text._ZN11__sanitizer9LibIgnore17AddIgnoredLibraryEPKc+0x28e): undefined reference to `__atomic_compare_exchange_8'

and on NetBSD-current they get:

/usr/bin/ld: compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.i386.dir/sanitizer_libignore.cpp.o: in function `__sanitizer::LibIgnore::AddIgnoredLibrary(char const*)':
/home/brad/tmp/llvm-brad/compiler-rt/lib/sanitizer_common/sanitizer_atomic_clang.h:43:(.text._ZN11__sanitizer9LibIgnore17AddIgnoredLibraryEPKc+0x31): undefined reference to `__atomic_load_8'
/usr/bin/ld: /home/brad/tmp/llvm-brad/compiler-rt/lib/sanitizer_common/sanitizer_atomic_clang.h:84:(.text._ZN11__sanitizer9LibIgnore17AddIgnoredLibraryEPKc+0x98): undefined reference to `__atomic_compare_exchange_8'
/usr/bin/ld: compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.i386.dir/sanitizer_libignore.cpp.o: in function `Lock':
/home/brad/tmp/llvm-brad/compiler-rt/lib/sanitizer_common/sanitizer_atomic_clang.h:84:(.text._ZN11__sanitizer9LibIgnore17AddIgnoredLibraryEPKc+0xf1): undefined reference to `__atomic_compare_exchange_8'
/usr/bin/ld: /home/brad/tmp/llvm-brad/compiler-rt/lib/sanitizer_common/sanitizer_atomic_clang.h:84:(.text._ZN11__sanitizer9LibIgnore17AddIgnoredLibraryEPKc+0x138): undefined reference to `__atomic_compare_exchange_8'
/usr/bin/ld: compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.i386.dir/sanitizer_libignore.cpp.o: in function `__sanitizer::LibIgnore::AddIgnoredLibrary(char const*)':
/home/brad/tmp/llvm-brad/compiler-rt/lib/sanitizer_common/sanitizer_atomic_clang.h:43:(.text._ZN11__sanitizer9LibIgnore17AddIgnoredLibraryEPKc+0x15a): undefined reference to `__atomic_load_8'
/usr/bin/ld: /home/brad/tmp/llvm-brad/compiler-rt/lib/sanitizer_common/sanitizer_atomic_clang.h:43:(.text._ZN11__sanitizer9LibIgnore17AddIgnoredLibraryEPKc+0x1cf): undefined reference to `__atomic_load_8'
/usr/bin/ld: /home/brad/tmp/llvm-brad/compiler-rt/lib/sanitizer_common/sanitizer_atomic_clang.h:84:(.text._ZN11__sanitizer9LibIgnore17AddIgnoredLibraryEPKc+0x222): undefined reference to `__atomic_compare_exchange_8'

So basically two problems:

- DWARM FORM 0x25 unsupported on NetBSD 10
  I guess because the binutils there are too old?

- missing symbols __atomic_load_8, __atomic_compare_exchange_8
  what should provide these?

Feel free to directly answer in the upstream discussion:

https://github.com/llvm/llvm-project/issues/125566

or I can forward.

Thanks,
 Thomas