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-rw-r--r--include/linux/compiler-gcc4.h14
1 files changed, 14 insertions, 0 deletions
diff --git a/include/linux/compiler-gcc4.h b/include/linux/compiler-gcc4.h
index e6ef279ca20..94dea3ffbfa 100644
--- a/include/linux/compiler-gcc4.h
+++ b/include/linux/compiler-gcc4.h
@@ -36,6 +36,20 @@
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