[tip:perf/core] tools include compiler-gcc: Add __pure attribute helper

[tip-bot for Arnaldo Carvalho de Melo]

Commit-ID:  6e1690c4c0b540930f08295b6a95c8660b257745
Gitweb:     https://git.kernel.org/tip/6e1690c4c0b540930f08295b6a95c8660b257745
Author:     Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
AuthorDate: Thu, 17 May 2018 15:12:36 -0300
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Thu, 17 May 2018 15:17:21 -0300

tools include compiler-gcc: Add __pure attribute helper

Adopt it from the kernel sources, will be used soon.

Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
Link: https://lkml.kernel.org/n/tip-oubheiqj8edo5rzewt11cbn0@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/include/linux/compiler-gcc.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/include/linux/compiler-gcc.h b/tools/include/linux/compiler-gcc.h
index a3a4427441bf..70fe61295733 100644
--- a/tools/include/linux/compiler-gcc.h
+++ b/tools/include/linux/compiler-gcc.h
@@ -21,6 +21,9 @@
 /* &a[0] degrades to a pointer: a different type from an array */
 #define __must_be_array(a)	BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
 
+#ifndef __pure
+#define  __pure		__attribute__((pure))
+#endif
 #define  noinline	__attribute__((noinline))
 #ifndef __packed
 #define __packed	__attribute__((packed))