Improve LTO detection code

Split LTO detection into separate func and file, and create a cached
LTO_WORKS variable.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

1 files changed, 32 insertions, 0 deletions

diff --git a/LTO.cmake b/LTO.cmake
new file mode 100644
index 0000000..9a18d77
--- /dev/null
+++ b/LTO.cmake
@@ -0,0 +1,32 @@
+function(check_lto)
+    if (DEFINED LTO_WORKS)
+        return()
+    endif()
+
+    set(LTO_WORKS FALSE CACHE INTERNAL "LTO works")
+
+    CHECK_CXX_COMPILER_FLAG("-flto" HAS_LTO_FLAG)
+
+    if (NOT HAS_LTO_FLAG)
+        return()
+    endif()
+
+    find_program(LTO_AR NAMES "${CMAKE_C_COMPILER}-ar" gcc-ar)
+    find_program(LTO_RANLIB NAMES "${CMAKE_C_COMPILER}-ranlib" gcc-ranlib)
+
+    if (NOT LTO_AR OR NOT LTO_RANLIB)
+        return()
+    endif()
+
+    EXECUTE_PROCESS(COMMAND "${LTO_AR}" --version RESULT_VARIABLE ret OUTPUT_QUIET ERROR_QUIET)
+    if (ret)
+        return()
+    endif()
+
+    EXECUTE_PROCESS(COMMAND "${LTO_RANLIB}" --version RESULT_VARIABLE ret OUTPUT_QUIET ERROR_QUIET)
+    if (ret)
+        return()
+    endif()
+
+    set(LTO_WORKS TRUE CACHE INTERNAL "LTO works")
+endfunction()