[CMake] Create an install-distribution target driven by LLVM_DISTRIBUTION_COMPONENTS

The idea here is to provide a customizable install target that only depends on building the things you actually want to install. It relies on each component being installed having an auto-generated install-${component}, which in turn depends only on the target being installed.

This is fundamentally a workaround for the fact that CMake generates build files which have their "install" target depend on the "all" target. This results in "ninja install" building a bunch of unneeded things.

llvm-svn: 261681

llvm/CMakeLists.txt

@@ -766,3 +766,20 @@ if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
                               -P "${CMAKE_BINARY_DIR}/cmake_install.cmake")
   endif()
 endif()
+
+# This must be at the end of the LLVM root CMakeLists file because it must run
+# after all targets are created.
+if(LLVM_DISTRIBUTION_COMPONENTS)
+  if(CMAKE_CONFIGURATION_TYPES)
+    message(FATAL_ERROR "LLVM_DISTRIBUTION_COMPONENTS cannot be specified with multi-configuration generators (i.e. Xcode or Visual Studio)")
+  endif()
+  
+  add_custom_target(install-distribution)
+  foreach(target ${LLVM_DISTRIBUTION_COMPONENTS})
+    if(TARGET install-${target})
+      add_dependencies(install-distribution install-${target})
+    else()
+      message(FATAL_ERROR "Specified distribution component '${target}' doesn't have an install target")
+    endif()
+  endforeach()
+endif()