tools/perf/build: Split out feature check: 'volatile-register-var'

Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/n/tip-5dOevlybbwvbk3zTbcxrrqet@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

tools/perf/config/Makefile

@@ -105,6 +105,7 @@ FEATURE_TESTS =				\
 	hello				\
 	stackprotector-all		\
 	stackprotector			\
+	volatile-register-var		\
 	libnuma
 
 $(foreach test,$(FEATURE_TESTS),$(call feature_check,$(test),$(test)))
@@ -117,7 +118,7 @@ ifeq ($(feature-stackprotector), 1)
   CFLAGS += -Wstack-protector
 endif
 
-ifeq ($(call try-cc,$(SOURCE_HELLO),$(CFLAGS) -Werror -Wvolatile-register-var,-Wvolatile-register-var),y)
+ifeq ($(feature-volatile-register-var), 1)
   CFLAGS += -Wvolatile-register-var
 endif
 

tools/perf/config/feature-checks/Makefile

@@ -3,6 +3,7 @@ FILES=					\
 	test-hello			\
 	test-stackprotector-all		\
 	test-stackprotector		\
+	test-volatile-register-var	\
 	test-libnuma
 
 CC := $(CC) -MD
@@ -22,6 +23,9 @@ test-stackprotector-all:
 test-stackprotector:
 	$(BUILD) -Werror -fstack-protector
 
+test-volatile-register-var:
+	$(BUILD) -Werror -Wvolatile-register-var
+
 test-libnuma:
 	$(BUILD) -lnuma
 

tools/perf/config/feature-checks/test-volatile-register-var.c

@@ -0,0 +1,6 @@
+#include <stdio.h>
+
+int main(void)
+{
+	return puts("hi");
+}