compiler.h: add __visible (9a858dc7) · Commits · 戴 / test

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. This is used (at least) by the "Link Time Optimization" patchset. Signed-off-by:

Andi Kleen <ak@linux.intel.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

include/linux/compiler-gcc4.h

+7 −0

Original line number	Diff line number	Diff line
		@@ -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

include/linux/compiler.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -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))

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