+AC_CACHE_CHECK([whether gcc supports __attribute__((visibility()))],
+ ac_cv_visibility, [dnl
+save_CFLAGS="$CFLAGS"
+CFLAGS="$save_CFLAGS -Werror"
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([dnl
+int __attribute__((visibility("hidden")))
+foo (int a)
+{
+ return a;
+}])], ac_cv_visibility=yes, ac_cv_visibility=no)
+CFLAGS="$save_CFLAGS"])
+if test "$ac_cv_visibility" = "yes"; then
+ AC_DEFINE([HAVE_VISIBILITY], [1],
+ [Defined if __attribute__((visibility())) is supported])
+fi
+
+AC_CACHE_CHECK([whether gcc supports __attribute__((gcc_struct))],
+ ac_cv_gcc_struct, [dnl
+save_CFLAGS="$CFLAGS"
+CFLAGS="$save_CFLAGS -Werror"
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([dnl
+struct test { int x; } __attribute__((gcc_struct));
+])], ac_cv_gcc_struct=yes, ac_cv_gcc_struct=no)
+CFLAGS="$save_CFLAGS"])
+if test "$ac_cv_gcc_struct" = "yes"; then
+ AC_DEFINE([HAVE_GCC_STRUCT], [1],
+ [Defined if __attribute__((gcc_struct)) is supported])
+fi
+
+AC_CACHE_CHECK([whether gcc supports -fPIC], ac_cv_fpic, [dnl
+save_CFLAGS="$CFLAGS"
+CFLAGS="$save_CFLAGS -fPIC -Werror"
+AC_COMPILE_IFELSE([AC_LANG_SOURCE()], ac_cv_fpic=yes, ac_cv_fpic=no)
+CFLAGS="$save_CFLAGS"
+])
+if test "$ac_cv_fpic" = "yes"; then
+ fpic_CFLAGS="-fPIC"
+else
+ fpic_CFLAGS=""
+fi
+AC_SUBST([fpic_CFLAGS])
+
+AC_CACHE_CHECK([whether gcc supports -fPIE], ac_cv_fpie, [dnl
+save_CFLAGS="$CFLAGS"
+CFLAGS="$save_CFLAGS -fPIE -Werror"
+AC_COMPILE_IFELSE([AC_LANG_SOURCE()], ac_cv_fpie=yes, ac_cv_fpie=no)
+CFLAGS="$save_CFLAGS"
+])
+if test "$ac_cv_fpie" = "yes"; then
+ fpie_CFLAGS="-fPIE"
+else
+ fpie_CFLAGS=""
+fi
+AC_SUBST([fpie_CFLAGS])
+
+dso_LDFLAGS="-shared"
+
+ZDEFS_LDFLAGS="-Wl,-z,defs"
+AC_CACHE_CHECK([whether gcc supports $ZDEFS_LDFLAGS], ac_cv_zdefs, [dnl
+save_LDFLAGS="$LDFLAGS"
+LDFLAGS="$ZDEFS_LDFLAGS $save_LDFLAGS"
+AC_LINK_IFELSE([AC_LANG_PROGRAM()], ac_cv_zdefs=yes, ac_cv_zdefs=no)
+LDFLAGS="$save_LDFLAGS"
+])
+if test "$ac_cv_zdefs" = "yes"; then
+ dso_LDFLAGS="$dso_LDFLAGS $ZDEFS_LDFLAGS"
+fi
+
+ZRELRO_LDFLAGS="-Wl,-z,relro"
+AC_CACHE_CHECK([whether gcc supports $ZRELRO_LDFLAGS], ac_cv_zrelro, [dnl
+save_LDFLAGS="$LDFLAGS"
+LDFLAGS="$ZRELRO_LDFLAGS $save_LDFLAGS"
+AC_LINK_IFELSE([AC_LANG_PROGRAM()], ac_cv_zrelro=yes, ac_cv_zrelro=no)
+LDFLAGS="$save_LDFLAGS"
+])
+if test "$ac_cv_zrelro" = "yes"; then
+ dso_LDFLAGS="$dso_LDFLAGS $ZRELRO_LDFLAGS"
+fi
+
+AC_SUBST([dso_LDFLAGS])
+