[Chore] (CMake): Enable LTO.

Author: BZLZHH

MobileGlues-cpp/CMakeLists.txt

@@ -12,16 +12,59 @@ set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
 if(MACOS)
         set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -w -fvisibility=default -funwind-tables -g -D_THREAD_SAFE -fPIC -stdlib=libc++")
-        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -w -g -std=gnu99 -funwind-tables -O3 -fvisibility=hidden")
+        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -w -g -std=gnu99 -funwind-tables -fvisibility=hidden")
         set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -static-libstdc++")
 else()
         set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -w -fvisibility=hidden -funwind-tables -g -D_THREAD_SAFE -fPIC")
-        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -w -g -std=gnu99 -funwind-tables -O3 -fvisibility=hidden")
+        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -w -g -std=gnu99 -funwind-tables -fvisibility=hidden")
         set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -static-libstdc++")
         set(CMAKE_ANDROID_STL_TYPE c++_static)
 endif()
 
-#set(CMAKE_BUILD_TYPE Release)
+if (NOT CMAKE_BUILD_TYPE STREQUAL "Debug")
+    # Check if ThinLTO or LTO is suppported
+    include(CheckIPOSupported)
+    include(CheckCCompilerFlag)
+    include(CheckCXXCompilerFlag)
+
+    check_ipo_supported(RESULT LTOSupported OUTPUT LTOError)
+
+    check_c_compiler_flag("-flto" HAS_LTO_C)
+    check_cxx_compiler_flag("-flto" HAS_LTO_CXX)
+
+    if (LTOSupported OR (HAS_LTO_C AND HAS_LTO_CXX))
+        # Check ThinLTO
+        check_c_compiler_flag("-flto=thin" HAS_THINLTO_C)
+        check_cxx_compiler_flag("-flto=thin" HAS_THINLTO_CXX)
+        if (HAS_THINLTO_C AND HAS_THINLTO_CXX)
+            message(STATUS "ThinLTO supported, using -flto=thin")
+
+            add_compile_options(-flto=thin)
+            add_link_options(-flto=thin)
+        else()
+            # ThinLTO is not supported
+            message(STATUS "ThinLTO not available, fallback to CMAKE IPO")
+            set(CMAKE_INTERPROCEDURAL_OPTIMIZATION TRUE)
+        endif()
+    else()
+        message(STATUS "IPO not supported: ${LTOError}")
+    endif()
+endif()
+
+
+if (CMAKE_CXX_COMPILER_ID MATCHES "GNU|Clang" AND NOT MATCHES "AppleClang")
+    add_compile_options(-O3 -ffunction-sections -fdata-sections)
+    add_link_options(-Wl,--gc-sections)
+elseif (CMAKE_CXX_COMPILER_ID MATCHES "MSVC")
+#    add_compile_options(/O2)
+else ()
+    add_compile_options(-O2)
+endif()
+
+if (CMAKE_CXX_COMPILER_ID MATCHES "MSVC")
+    add_compile_options(/Zc:preprocessor)
+    add_compile_options(/Zc:__cplusplus)
+endif()
 
 set(PROFILING OFF)