[libunwind] Support building libunwind as a DLL

[compnerd]

LG with the adjustment for the dll storage macros.

CMakeLists.txt

313

Ugh, I really do dislike the _LIBUNWIND_DISABLE_VISIBILITY_ANNOTATIONS macro, but that isn't your fault.

src/config.h

53

I think that !defined(__ELF__) && !defined(__MACHO__) is better than defined(_WIN32), as these are PE/COFF specific, not Windows specification.

[mstorsjo]

src/config.h

53

Ok, I can make it use that instead. libcxx and libcxxabi do use defined(_WIN32) in their similar checks though.

CMakeLists.txt

if (LIBUNWIND_ENABLE_ARM_WMMX)
   list(APPEND LIBUNWIND_COMPILE_FLAGS -D__ARM_WMMX)
 endif()
 
 # This is the _ONLY_ place where add_definitions is called.
 if (MSVC)
   add_definitions(-D_CRT_SECURE_NO_WARNINGS)
 endif()
 
+# Disable DLL annotations on Windows for static builds.
+if (WIN32 AND LIBUNWIND_ENABLE_STATIC AND NOT LIBUNWIND_ENABLE_SHARED)
+  add_definitions(-D_LIBUNWIND_DISABLE_VISIBILITY_ANNOTATIONS)
+endif()
+
 #===============================================================================
 # Setup Source Code
 #===============================================================================
 
 include_directories(include)
 
 find_path(
   LIBUNWIND_LIBCXX_INCLUDES_INTERNAL

src/config.h

#if defined(__ARM_DWARF_EH__) || !defined(__arm__)
     #define _LIBUNWIND_SUPPORT_DWARF_INDEX 1
   #endif
 #endif
 
 #if defined(_LIBUNWIND_DISABLE_VISIBILITY_ANNOTATIONS)
   #define _LIBUNWIND_EXPORT
   #define _LIBUNWIND_HIDDEN
 #else
-  // FIXME: these macros are not correct for COFF targets
+  #if defined(_WIN32)
+    #define _LIBUNWIND_EXPORT __declspec(dllexport)
+    #define _LIBUNWIND_HIDDEN
+  #else
     #define _LIBUNWIND_EXPORT __attribute__((visibility("default")))
     #define _LIBUNWIND_HIDDEN __attribute__((visibility("hidden")))
   #endif
+#endif
 
 #if (defined(__APPLE__) && defined(__arm__)) || defined(__USING_SJLJ_EXCEPTIONS__)
 #define _LIBUNWIND_BUILD_SJLJ_APIS
 #endif
 
 #if defined(__i386__) || defined(__x86_64__) || defined(__ppc__) || defined(__ppc64__)
 #define _LIBUNWIND_SUPPORT_FRAME_APIS
 #endif