perf test: Print result for each LLVM subtest

Currently 'perf test llvm' and 'perf test BPF' have multiple sub-tests,
but the result is provided in only one line:

  # perf test LLVM
  35: Test LLVM searching and compiling                        : Ok

This patch introduces sub-tests support, allowing 'perf test' to report
result for each sub-tests:

  # perf test LLVM
  35: Test LLVM searching and compiling                        :
  35.1: Basic BPF llvm compiling test                          : Ok
  35.2: Test kbuild searching                                  : Ok
  35.3: Compile source for BPF prologue generation test        : Ok

When a failure happens:

  # cat ~/.perfconfig
  [llvm]
       clang-path = "/bin/false"
  # perf test LLVM
  35: Test LLVM searching and compiling                        :
  35.1: Basic BPF llvm compiling test                          : FAILED!
  35.2: Test kbuild searching                                  : Skip
  35.3: Compile source for BPF prologue generation test        : Skip

And:

  # rm ~/.perfconfig
  # ./perf test LLVM
  35: Test LLVM searching and compiling                        :
  35.1: Basic BPF llvm compiling test                          : Skip
  35.2: Test kbuild searching                                  : Skip
  35.3: Compile source for BPF prologue generation test        : Skip

Skip by user:

  # ./perf test -s 1,`seq -s , 3 42`
   1: vmlinux symtab matches kallsyms                          : Skip (user override)
   2: detect openat syscall event                              : Ok
  ...
  35: Test LLVM searching and compiling                        : Skip (user override)
  ...

Suggested-and-Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1447749170-175898-4-git-send-email-wangnan0@huawei.com
[ Changed so that func is not on an anonymous union ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/llvm.c

@@ -46,7 +46,7 @@ static struct {
 	},
 	[LLVM_TESTCASE_BPF_PROLOGUE] = {
 		.source = test_llvm__bpf_test_prologue_prog,
-		.desc = "Test BPF prologue generation",
+		.desc = "Compile source for BPF prologue generation test",
 	},
 };
 
@@ -131,44 +131,39 @@ out:
 	return ret;
 }
 
-int test__llvm(int subtest __maybe_unused)
+int test__llvm(int subtest)
 {
-	enum test_llvm__testcase i;
+	int ret;
+	void *obj_buf = NULL;
+	size_t obj_buf_sz = 0;
 
-	for (i = 0; i < __LLVM_TESTCASE_MAX; i++) {
-		int ret;
-		void *obj_buf = NULL;
-		size_t obj_buf_sz = 0;
+	if ((subtest < 0) || (subtest >= __LLVM_TESTCASE_MAX))
+		return TEST_FAIL;
 
-		ret = test_llvm__fetch_bpf_obj(&obj_buf, &obj_buf_sz,
-					       i, false);
+	ret = test_llvm__fetch_bpf_obj(&obj_buf, &obj_buf_sz,
+				       subtest, false);
 
-		if (ret == TEST_OK) {
-			ret = test__bpf_parsing(obj_buf, obj_buf_sz);
-			if (ret != TEST_OK)
-				pr_debug("Failed to parse test case '%s'\n",
-					 bpf_source_table[i].desc);
-		}
-		free(obj_buf);
-
-		switch (ret) {
-		case TEST_SKIP:
-			return TEST_SKIP;
-		case TEST_OK:
-			break;
-		default:
-			/*
-			 * Test 0 is the basic LLVM test. If test 0
-			 * fail, the basic LLVM support not functional
-			 * so the whole test should fail. If other test
-			 * case fail, it can be fixed by adjusting
-			 * config so don't report error.
-			 */
-			if (i == 0)
-				return TEST_FAIL;
-			else
-				return TEST_SKIP;
+	if (ret == TEST_OK) {
+		ret = test__bpf_parsing(obj_buf, obj_buf_sz);
+		if (ret != TEST_OK) {
+			pr_debug("Failed to parse test case '%s'\n",
+				 bpf_source_table[subtest].desc);
 		}
 	}
-	return TEST_OK;
+	free(obj_buf);
+
+	return ret;
+}
+
+int test__llvm_subtest_get_nr(void)
+{
+	return __LLVM_TESTCASE_MAX;
+}
+
+const char *test__llvm_subtest_get_desc(int subtest)
+{
+	if ((subtest < 0) || (subtest >= __LLVM_TESTCASE_MAX))
+		return NULL;
+
+	return bpf_source_table[subtest].desc;
 }