make use of thinlto for release builds

CMakeLists.txt

@@ -156,7 +156,7 @@ function(give_options_without_warnings target)
 
         set(BUILD_FLAGS_RELEASE
                 -O3
-                -flto=auto
+                -flto=$<IF:$<STREQUAL:${CMAKE_C_COMPILER_ID},Clang>,thin,auto>
                 -mavx -mavx2
                 -Wl,--gc-sections
                 -fdata-sections
@@ -173,6 +173,10 @@ function(give_options_without_warnings target)
 		$<$<BOOL:${TWN_SANITIZE}>:-fstack-protector-all -fsanitize=undefined -fsanitize=address>
                 $<$<BOOL:${EMSCRIPTEN}>:-gsource-map>)
 
+        set(BUILD_SHARED_LIBRARY_FLAGS_RELEASE
+                $<$<STREQUAL:${CMAKE_C_COMPILER_ID},Clang>:-Wl,-plugin-opt,cache-dir=${CMAKE_CURRENT_BINARY_DIR}/linker-cache/>
+                $<$<STREQUAL:${CMAKE_C_COMPILER_ID},Clang>:-Wl,-plugin-opt,cache-policy=prune_after=30m>)
+
         target_compile_options(${target} PUBLIC
                                          ${BUILD_FLAGS}
                                          $<$<CONFIG:Release>:${BUILD_FLAGS_RELEASE}>
@@ -186,6 +190,15 @@ function(give_options_without_warnings target)
                                       -Bsymbolic-functions
                                       $<$<BOOL:${LINUX}>:-Wl,--hash-style=gnu>)
 
+        get_target_property(target_type ${target} TYPE)
+        if (target_type MATCHES SHARED_LIBRARY)
+                target_compile_options(${target} PUBLIC
+                                                 $<$<CONFIG:Release>:${BUILD_SHARED_LIBRARY_FLAGS_RELEASE}>)
+
+                target_link_options(${target} PUBLIC
+                                              $<$<CONFIG:Release>:${BUILD_SHARED_LIBRARY_FLAGS_RELEASE}>)
+        endif()
+
         target_compile_definitions(${target} PRIVATE
                                              $<$<BOOL:${TWN_FEATURE_DYNLIB_GAME}>:TWN_FEATURE_DYNLIB_GAME>
                                              $<$<BOOL:${LINUX}>:_GNU_SOURCE>)