[PATCH 01/74] Add __visible

[Andi Kleen]

From: Andi Kleen <ak@xxxxxxxxxxxxxxx>

gcc 4.6+ has support for a externally_visible attribute, that prevents
the optimizer from optimizing unused symbols away. Add a __visible macro
to use it with that compiler version or later.

Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
---
 include/linux/compiler-gcc4.h |    7 +++++++
 include/linux/compiler.h      |    4 ++++
 2 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/include/linux/compiler-gcc4.h b/include/linux/compiler-gcc4.h
index 2f40791..934bc34 100644
--- a/include/linux/compiler-gcc4.h
+++ b/include/linux/compiler-gcc4.h
@@ -49,6 +49,13 @@
 #endif
 #endif
 
+#if __GNUC_MINOR__ >= 6
+/*
+ * Tell the optimizer that something else uses this function or variable.
+ */
+#define __visible __attribute__((externally_visible))
+#endif
+
 #if __GNUC_MINOR__ > 0
 #define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
 #endif
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 923d093..f430e41 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -278,6 +278,10 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
 # define __section(S) __attribute__ ((__section__(#S)))
 #endif
 
+#ifndef __visible
+#define __visible
+#endif
+
 /* Are two types/vars the same type (ignoring qualifiers)? */
 #ifndef __same_type
 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
-- 
1.7.7.6

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