perf clang: Update test case to use real BPF script

Allow C++ code to use util.h and tests/llvm.h. Let 'perf test' compile a
real BPF script.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Joe Stringer <joe@ovn.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/20161126070354.141764-14-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Makefile.config

@@ -212,24 +212,27 @@ ifeq ($(DEBUG),0)
   endif
 endif
 
-CFLAGS += -I$(src-perf)/util/include
-CFLAGS += -I$(src-perf)/arch/$(ARCH)/include
-CFLAGS += -I$(srctree)/tools/include/uapi
-CFLAGS += -I$(srctree)/tools/include/
-CFLAGS += -I$(srctree)/tools/arch/$(ARCH)/include/uapi
-CFLAGS += -I$(srctree)/tools/arch/$(ARCH)/include/
-CFLAGS += -I$(srctree)/tools/arch/$(ARCH)/
+INC_FLAGS += -I$(src-perf)/util/include
+INC_FLAGS += -I$(src-perf)/arch/$(ARCH)/include
+INC_FLAGS += -I$(srctree)/tools/include/uapi
+INC_FLAGS += -I$(srctree)/tools/include/
+INC_FLAGS += -I$(srctree)/tools/arch/$(ARCH)/include/uapi
+INC_FLAGS += -I$(srctree)/tools/arch/$(ARCH)/include/
+INC_FLAGS += -I$(srctree)/tools/arch/$(ARCH)/
 
 # $(obj-perf)      for generated common-cmds.h
 # $(obj-perf)/util for generated bison/flex headers
 ifneq ($(OUTPUT),)
-CFLAGS += -I$(obj-perf)/util
-CFLAGS += -I$(obj-perf)
+INC_FLAGS += -I$(obj-perf)/util
+INC_FLAGS += -I$(obj-perf)
 endif
 
-CFLAGS += -I$(src-perf)/util
-CFLAGS += -I$(src-perf)
-CFLAGS += -I$(srctree)/tools/lib/
+INC_FLAGS += -I$(src-perf)/util
+INC_FLAGS += -I$(src-perf)
+INC_FLAGS += -I$(srctree)/tools/lib/
+
+CFLAGS   += $(INC_FLAGS)
+CXXFLAGS += $(INC_FLAGS)
 
 CFLAGS += -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE
 

tools/perf/tests/llvm.h

@@ -1,6 +1,10 @@
 #ifndef PERF_TEST_LLVM_H
 #define PERF_TEST_LLVM_H
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #include <stddef.h> /* for size_t */
 #include <stdbool.h> /* for bool */
 
@@ -20,4 +24,7 @@ enum test_llvm__testcase {
 int test_llvm__fetch_bpf_obj(void **p_obj_buf, size_t *p_obj_buf_sz,
 			     enum test_llvm__testcase index, bool force,
 			     bool *should_load_fail);
+#ifdef __cplusplus
+}
+#endif
 #endif

tools/perf/util/c++/clang-test.cpp

@@ -3,6 +3,10 @@
 #include "llvm/IR/Function.h"
 #include "llvm/IR/LLVMContext.h"
 
+#include <util-cxx.h>
+#include <tests/llvm.h>
+#include <string>
+
 class perf_clang_scope {
 public:
 	explicit perf_clang_scope() {perf_clang__init();}
@@ -14,17 +18,24 @@ extern "C" {
 int test__clang_to_IR(void)
 {
 	perf_clang_scope _scope;
+	unsigned int kernel_version;
+
+	if (fetch_kernel_version(&kernel_version, NULL, 0))
+		return -1;
+
+	std::string cflag_kver("-DLINUX_VERSION_CODE=" +
+				std::to_string(kernel_version));
 
 	std::unique_ptr<llvm::Module> M =
-		perf::getModuleFromSource({"-DRESULT=1"},
+		perf::getModuleFromSource({cflag_kver.c_str()},
 					  "perf-test.c",
-					  "int myfunc(void) {return RESULT;}");
+					  test_llvm__bpf_base_prog);
 
 	if (!M)
 		return -1;
 
 	for (llvm::Function& F : *M)
-		if (F.getName() == "myfunc")
+		if (F.getName() == "bpf_func__SyS_epoll_wait")
 			return 0;
 	return -1;
 }

tools/perf/util/util-cxx.h

@@ -0,0 +1,26 @@
+/*
+ * Support C++ source use utilities defined in util.h
+ */
+
+#ifndef PERF_UTIL_UTIL_CXX_H
+#define PERF_UTIL_UTIL_CXX_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * Now 'new' is the only C++ keyword found in util.h:
+ * in tools/include/linux/rbtree.h
+ *
+ * Other keywords, like class and delete, should be
+ * redefined if necessary.
+ */
+#define new _new
+#include "util.h"
+#undef new
+
+#ifdef __cplusplus
+}
+#endif
+#endif