[CMake] Fix llvm_setup_rpath function

[azharudd]

Summary

Set _install_rpath to CMAKE_INSTALL_RPATH if it is defined, so that eventually
INSTALL_RPATH is set to CMAKE_INSTALL_RPATH.
The "if(NOT DEFINED CMAKE_INSTALL_RPATH)" was missing a corresponding else
clause.
This also cleans up the fix made in r285908.

Patch by Azharuddin Mohammed

[beanz]

I think there is actually a more general solution to this. At the top of the function we can just have:

if(CMAKE_INSTALL_RPATH)
  return()
endif()

Then we can remove the conditionals on CMAKE_INSTALL_RPATH, and just allow the target to inherit from the global setting, which is the default.

[azharudd]

In D26289#588354, @beanz wrote:

I think there is actually a more general solution to this. At the top of the function we can just have:

if(CMAKE_INSTALL_RPATH)
  return()
endif()

Then we can remove the conditionals on CMAKE_INSTALL_RPATH, and just allow the target to inherit from the global setting, which is the default.

sounds good. updated.

[beanz]

LGTM!

cmake/modules/AddLLVM.cmake

 endfunction()
 
 function(llvm_setup_rpath name)
+  if(CMAKE_INSTALL_RPATH)
+    return()
+  endif()
+
   if(LLVM_INSTALL_PREFIX AND NOT (LLVM_INSTALL_PREFIX STREQUAL CMAKE_INSTALL_PREFIX))
     set(extra_libdir ${LLVM_LIBRARY_DIR})
   elseif(LLVM_BUILD_LIBRARY_DIR)

     set(_install_name_dir INSTALL_NAME_DIR "@rpath")
     set(_install_rpath "@loader_path/../lib" ${extra_libdir})
   elseif(UNIX)
-    if(NOT DEFINED CMAKE_INSTALL_RPATH)
-      set(_install_rpath "\$ORIGIN/../lib${LLVM_LIBDIR_SUFFIX}" ${extra_libdir})
-      if(${CMAKE_SYSTEM_NAME} MATCHES "(FreeBSD|DragonFly)")
-        set_property(TARGET ${name} APPEND_STRING PROPERTY
-                     LINK_FLAGS " -Wl,-z,origin ")
-      elseif(${CMAKE_SYSTEM_NAME} STREQUAL "Linux" AND NOT LLVM_LINKER_IS_GOLD)
-        # $ORIGIN is not interpreted at link time by ld.bfd
-        set_property(TARGET ${name} APPEND_STRING PROPERTY
-                     LINK_FLAGS " -Wl,-rpath-link,${LLVM_LIBRARY_OUTPUT_INTDIR} ")
-      endif()
+    set(_install_rpath "\$ORIGIN/../lib${LLVM_LIBDIR_SUFFIX}" ${extra_libdir})
+    if(${CMAKE_SYSTEM_NAME} MATCHES "(FreeBSD|DragonFly)")
+      set_property(TARGET ${name} APPEND_STRING PROPERTY
+                   LINK_FLAGS " -Wl,-z,origin ")
+    elseif(${CMAKE_SYSTEM_NAME} STREQUAL "Linux" AND NOT LLVM_LINKER_IS_GOLD)
+      # $ORIGIN is not interpreted at link time by ld.bfd
+      set_property(TARGET ${name} APPEND_STRING PROPERTY
+                   LINK_FLAGS " -Wl,-rpath-link,${LLVM_LIBRARY_OUTPUT_INTDIR} ")
     endif()
   else()
     return()
   endif()
 
-  if(DEFINED _install_rpath)
-    set_target_properties(${name} PROPERTIES
-                          BUILD_WITH_INSTALL_RPATH On
-                          INSTALL_RPATH "${_install_rpath}"
-                          ${_install_name_dir})
-  endif()
+  set_target_properties(${name} PROPERTIES
+                        BUILD_WITH_INSTALL_RPATH On
+                        INSTALL_RPATH "${_install_rpath}"
+                        ${_install_name_dir})
 endfunction()