From: Thierry Reding treding@nvidia.com
Checks whether or not the compiler supports the -fvisibility option. If so it sets the VISIBILITY_CFLAGS variable which can be added to the per directory AM_CFLAGS where appropriate.
Libraries can use the HAVE_VISIBILITY preprocessor definition to check for availability and use something like this:
#if defined(HAVE_VISIBILITY) # define drm_private __attribute__((visibility("hidden"))) # define drm_public __attribute__((visibility("default"))) #else # define drm_private # define drm_public #endif
By default all symbols will be hidden via the VISIBILITY_CFLAGS. Only symbols explicitly marked drm_public will be exported.
Signed-off-by: Thierry Reding treding@nvidia.com --- configure.ac | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+)
diff --git a/configure.ac b/configure.ac index d2d19d66dc17..3f4164238494 100644 --- a/configure.ac +++ b/configure.ac @@ -365,6 +365,26 @@ AC_ARG_WITH([kernel-source], [kernel_source="$with_kernel_source"]) AC_SUBST(kernel_source)
+dnl Add flags for gcc and g++ +if test "x$GCC" = xyes; then + # Enable -fvisibility=hidden if using a gcc that supports it + save_CFLAGS="$CFLAGS" + AC_MSG_CHECKING([whether $CC supports -fvisibility=hidden]) + VISIBILITY_CFLAGS="-fvisibility=hidden" + CFLAGS="$CFLAGS $VISIBILITY_CFLAGS" + AC_LINK_IFELSE([AC_LANG_PROGRAM()], AC_MSG_RESULT([yes]), + [VISIBILITY_CFLAGS=""; AC_MSG_RESULT([no])]); + + # Restore CFLAGS; VISIBILITY_CFLAGS are added to it where needed. + CFLAGS=$save_CFLAGS + + if test "x$VISIBILITY_CFLAGS" != x; then + AC_DEFINE(HAVE_VISIBILITY, 1, [Compiler has -fvisibility support]) + fi + + AC_SUBST([VISIBILITY_CFLAGS]) +fi + AC_SUBST(WARN_CFLAGS) AC_CONFIG_FILES([ Makefile