the kernel context */
#define __cold __attribute__((__cold__))
+
+#if __GNUC_MINOR__ >= 5
+/*
+ * Mark a position in code as unreachable. This can be used to
+ * suppress control flow warnings after asm blocks that transfer
+ * control elsewhere.
+ *
+ * Early snapshots of gcc 4.5 don't support this and we can't detect
+ * this in the preprocessor, but we can live with this because they're
+ * unreleased. Really, we need to have autoconf for the kernel.
+ */
+#define unreachable() __builtin_unreachable()
+#endif
+
#endif
+
+ #if __GNUC_MINOR__ > 0
+ #define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
+ #endif
+ #if __GNUC_MINOR__ >= 4
+ #define __compiletime_warning(message) __attribute__((warning(message)))
+ #define __compiletime_error(message) __attribute__((error(message)))
+ #endif