builtins: use -fPIC if supported

[brian]

Summary

Otherwise, I get complaints from the linker when trying to create shared objects
which use certain functions from libclang_rt.builtins-arm.a (__aeabi_l2d is the specific
one I found).

As of r146499, it looks like the Makefiles are already doing this.

[brian]

I'm not completely sure how this works, but I think this comment will show up on the mailing list. Can somebody please review this?

[hintonda]

I can't review it for you, but you can use either 'git blame' or 'arc cover' to try to figure out who a good reviewer might be and add them. If they aren't the right person, hopefully they will add or suggest someone more appropriate.

Good luck...

[compnerd]

lib/builtins/CMakeLists.txt

378

This needs to be more target specific. Not all targets may support this flag.

[brian]

@compnerd: It looks like you're a committer, so you can you commit this?

Thanks!

lib/builtins/CMakeLists.txt

378

I think cmake/builtin-config-ix.cmake checks if the target supports the flag when setting COMPILER_RT_HAS_FPIC_FLAG. Also, it's set the same way COMPILER_RT_HAS_STD_C99_FLAG is, which I doubt all targets support either. Is there something wrong with that approach?

[Eugene.Zelenko]

Looks like patch was not committed, but it should be rebased from trunk.

[brian]

Actually, when I went to rebase, I noticed that D23729 already added -fPIC and some other flags, so this isn't necessary any more.

lib/builtins/CMakeLists.txt

   darwin_add_builtin_libraries(${BUILTIN_SUPPORTED_OS})
 else ()
   append_string_if(COMPILER_RT_HAS_STD_C99_FLAG -std=c99 maybe_stdc99)
+  append_string_if(COMPILER_RT_HAS_FPIC_FLAG -fPIC maybe_fpic)
 
   foreach (arch ${BUILTIN_SUPPORTED_ARCH})
     if (CAN_TARGET_${arch})

                               STATIC
                               ARCHS ${arch}
                               SOURCES ${${arch}_SOURCES}
-                              CFLAGS ${maybe_stdc99}
+                              CFLAGS ${maybe_stdc99} ${maybe_fpic}
                               PARENT_TARGET builtins)
     endif ()
   endforeach ()