[CMake][libcxx] Do not rely on the existence of c++abi or unwind targets

There is no guaranteed order in which CMake files for individual
runtimes are invoked and therefore we cannot rely on existence of
targets defined in other runtimes. Use the new HAVE_<name> options
instead in those cases.

Differential Revision: https://reviews.llvm.org/D28391

llvm-svn: 291632

libcxx/CMakeLists.txt

@@ -119,8 +119,7 @@ if (LIBCXX_CXX_ABI STREQUAL "default")
           ${LLVM_MAIN_SRC_DIR}/runtimes/libcxxabi/include
     NO_DEFAULT_PATH
   )
-  if (NOT DEFINED LIBCXX_STANDALONE_BUILD AND
-      IS_DIRECTORY "${LIBCXX_LIBCXXABI_INCLUDES_INTERNAL}")
+  if (IS_DIRECTORY "${LIBCXX_LIBCXXABI_INCLUDES_INTERNAL}")
     set(LIBCXX_CXX_ABI_LIBNAME "libcxxabi")
     set(LIBCXX_CXX_ABI_INCLUDE_PATHS "${LIBCXX_LIBCXXABI_INCLUDES_INTERNAL}")
     set(LIBCXX_CXX_ABI_INTREE 1)

libcxx/lib/CMakeLists.txt

@@ -229,7 +229,8 @@ if (LIBCXX_ENABLE_STATIC)
     if (LIBCXX_CXX_ABI_LIBRARY_PATH)
       set(MERGE_ARCHIVES_SEARCH_PATHS "-L${LIBCXX_CXX_ABI_LIBRARY_PATH}")
     endif()
-    if (TARGET ${LIBCXX_CXX_ABI_LIBRARY})
+    if ((TARGET ${LIBCXX_CXX_ABI_LIBRARY}) OR
+        (${LIBCXX_CXX_ABI_LIBRARY} STREQUAL "cxxabi(_static|_shared)?" AND HAVE_LIBCXXABI))
       set(MERGE_ARCHIVES_ABI_TARGET "$<TARGET_LINKER_FILE:${LIBCXX_CXX_ABI_LIBRARY}>")
     else()
       set(MERGE_ARCHIVES_ABI_TARGET
@@ -300,7 +301,9 @@ if (LIBCXX_ENABLE_SHARED AND LIBCXX_ENABLE_ABI_LINKER_SCRIPT)
   set(LIBCXX_INTERFACE_LIBRARY_NAMES)
   foreach(lib ${LIBCXX_INTERFACE_LIBRARIES})
     # FIXME: Handle cxxabi_static and unwind_static.
-    if (TARGET ${lib})
+    if (TARGET ${lib} OR
+        (${lib} MATCHES "cxxabi(_static|_shared)?" AND HAVE_LIBCXXABI) OR
+        (${lib} MATCHES "unwind(_static|_shared)?" AND HAVE_LIBUNWIND))
       list(APPEND LIBCXX_INTERFACE_LIBRARY_NAMES "$<TARGET_PROPERTY:${lib},OUTPUT_NAME>")
     else()
       list(APPEND LIBCXX_INTERFACE_LIBRARY_NAMES "${lib}")