[CMake] Use target_link_libraries(INTERFACE|PRIVATE) on CMake-2.8.12 to increase opportunity for parallel build.

target_link_libraries(INTERFACE) doesn't bring inter-target dependencies in add_library,
although final targets have dependencies to whole dependent libraries.
It makes most libraries can be built in parallel.

target_link_libraries(PRIVATE) is used to shaared library.
Each dependent library is linked to the target.so, and its user will not see its grandchildren.
For example,

  - libclang.so has sufficient libclang*.a(s).
  - c-index-test requires just only libclang.so.

FIXME: lld is tweaked minimally. Adding INTERFACE in each library would be better thing.
llvm-svn: 202241

clang/CMakeLists.txt

@@ -326,7 +326,7 @@ macro(add_clang_library name)
   llvm_add_library(${name} ${ARG_UNPARSED_ARGUMENTS} ${srcs})
 
   if(TARGET ${name})
-    target_link_libraries( ${name} ${LLVM_COMMON_LIBS} )
+    target_link_libraries(${name} ${cmake_2_8_12_INTERFACE} ${LLVM_COMMON_LIBS})
 
     if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY OR ${name} STREQUAL "libclang")
       install(TARGETS ${name}

lld/lib/Core/CMakeLists.txt

@@ -11,7 +11,7 @@ add_lld_library(lldCore
   SymbolTable.cpp
   )
 
-target_link_libraries(lldCore
+target_link_libraries(lldCore ${cmake_2_8_12_INTERFACE}
   lldNative
   lldYAML
   )

lld/lib/ReaderWriter/CMakeLists.txt

@@ -15,7 +15,7 @@ add_lld_library(lldReaderWriter
   FileArchive.cpp
   )
 
-target_link_libraries(lldReaderWriter
+target_link_libraries(lldReaderWriter ${cmake_2_8_12_INTERFACE}
   lldCore
   lldPasses
   )

llvm/cmake/modules/AddLLVM.cmake

@@ -289,7 +289,12 @@ function(llvm_add_library name)
     endif()
   endif()
 
-  target_link_libraries(${name} ${ARG_LINK_LIBS})
+  if(ARG_STATIC)
+    target_link_libraries(${name} ${cmake_2_8_12_INTERFACE} ${ARG_LINK_LIBS})
+  else()
+    # MODULE|SHARED
+    target_link_libraries(${name} ${cmake_2_8_12_PRIVATE} ${ARG_LINK_LIBS})
+  endif()
 
   llvm_config(${name} ${ARG_LINK_COMPONENTS} ${LLVM_LINK_COMPONENTS})
 
@@ -330,7 +335,7 @@ macro(add_llvm_library name)
   # name, but using get_property(... SET) doesn't suffice to determine if a
   # property has been set to an empty value.
   get_property(lib_deps GLOBAL PROPERTY LLVMBUILD_LIB_DEPS_${name})
-  target_link_libraries(${name} ${lib_deps})
+  target_link_libraries(${name} ${cmake_2_8_12_INTERFACE} ${lib_deps})
 endmacro(add_llvm_library name)
 
 macro(add_llvm_loadable_module name)

llvm/cmake/modules/LLVM-Config.cmake

@@ -39,7 +39,15 @@ function(explicit_llvm_config executable)
   set( link_components ${ARGN} )
 
   llvm_map_components_to_libnames(LIBRARIES ${link_components})
-  target_link_libraries(${executable} ${LIBRARIES})
+  get_target_property(t ${executable} TYPE)
+  if("${t}" STREQUAL "STATIC_LIBRARY")
+    target_link_libraries(${executable} ${cmake_2_8_12_INTERFACE} ${LIBRARIES})
+  elseif("${t}" STREQUAL "SHARED_LIBRARY" OR "${t}" STREQUAL "MODULE_LIBRARY")
+    target_link_libraries(${executable} ${cmake_2_8_12_PRIVATE} ${LIBRARIES})
+  else()
+    # Use plain form for legacy user.
+    target_link_libraries(${executable} ${LIBRARIES})
+  endif()
 endfunction(explicit_llvm_config)
 
 

llvm/lib/Support/CMakeLists.txt

@@ -142,5 +142,5 @@ if( NOT MSVC )
     endif()
   endif( MINGW )
 endif( NOT MSVC )
-target_link_libraries(LLVMSupport ${system_libs})
+target_link_libraries(LLVMSupport ${cmake_2_8_12_INTERFACE} ${system_libs})
 set_property(TARGET LLVMSupport PROPERTY LLVM_SYSTEM_LIBS "${system_libs}")