CMake: Provide LLVM_PLUGIN_EXT definition

This is needed to support the addition of tests for clang loadable plugins.

In clang, plugins are built as modules (bundles on OS X) rather than dynamic
libraries (dylib) so the build system needs to inform lit of the actual
file extension in use, typically '.so' on Unix and '.dll' on Windows.

(LLVM itself should probably switch to this scheme to fix PR14903 once and for
all.)

No change in build output or functionality intended.

llvm-svn: 198746

cmake/modules/AddLLVM.cmake

@@ -215,6 +215,10 @@ ${name} ignored.")
         LINK_FLAGS " -Wl,-flat_namespace -Wl,-undefined -Wl,suppress")
     endif()
 
+    if (MODULE)
+      set_property(TARGET ${name} PROPERTY SUFFIX ${LLVM_PLUGIN_EXT})
+    endif ()
+
     if( EXCLUDE_FROM_ALL )
       set_target_properties( ${name} PROPERTIES EXCLUDE_FROM_ALL ON)
     else()

cmake/modules/HandleLLVMOptions.cmake

@@ -49,8 +49,6 @@ if(WIN32)
     set(LLVM_ON_WIN32 1)
     set(LLVM_ON_UNIX 0)
   endif(CYGWIN)
-  set(LTDL_SHLIB_EXT ".dll")
-  set(EXEEXT ".exe")
   # Maximum path length is 160 for non-unicode paths
   set(MAXPATHLEN 160)
 else(WIN32)
@@ -59,12 +57,9 @@ else(WIN32)
     set(LLVM_ON_UNIX 1)
     if(APPLE)
       set(LLVM_HAVE_LINK_VERSION_SCRIPT 0)
-      set(LTDL_SHLIB_EXT ".dylib")
     else(APPLE)
       set(LLVM_HAVE_LINK_VERSION_SCRIPT 1)
-      set(LTDL_SHLIB_EXT ".so")
     endif(APPLE)
-    set(EXEEXT "")
     # FIXME: Maximum path length is currently set to 'safe' fixed value
     set(MAXPATHLEN 2024)
   else(UNIX)
@@ -72,6 +67,10 @@ else(WIN32)
   endif(UNIX)
 endif(WIN32)
 
+set(EXEEXT ${CMAKE_EXECUTABLE_SUFFIX})
+set(LTDL_SHLIB_EXT ${CMAKE_SHARED_LIBRARY_SUFFIX})
+set(LLVM_PLUGIN_EXT ${CMAKE_SHARED_MODULE_SUFFIX})
+
 function(add_flag_or_print_warning flag)
   check_c_compiler_flag(${flag} C_SUPPORTS_FLAG)
   check_cxx_compiler_flag(${flag} CXX_SUPPORTS_FLAG)