perf build: Move feature checks code under tools/build

Moving feature checks code under tools/build directory.

Changing also $feature_dir to point to new feature directory location
and perf Makefiles to include Makefile.feature from new location.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <david.ahern@oracle.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-3lamtb30dhf4wo99y1n8kxg0@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/tools/build/feature/test-sync-compare-and-swap.c b/tools/build/feature/test-sync-compare-and-swap.c
new file mode 100644
index 000000000000..c34d4ca4af56
--- /dev/null
+++ b/tools/build/feature/test-sync-compare-and-swap.c
@@ -0,0 +1,14 @@
+#include <stdint.h>
+
+volatile uint64_t x;
+
+int main(int argc, char *argv[])
+{
+	uint64_t old, new = argc;
+
+	argv = argv;
+	do {
+		old = __sync_val_compare_and_swap(&x, 0, 0);
+	} while (!__sync_bool_compare_and_swap(&x, old, new));
+	return old == new;
+}