perf record: Add clang options for compiling BPF scripts

Although previous patch allows setting BPF compiler related options in
perfconfig, on some ad-hoc situation it still requires passing options
through cmdline. This patch introduces 2 options to 'perf record' for
this propose: --clang-path and --clang-opt.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Ahern <dsahern@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kaixu Xia <xiakaixu@huawei.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1444826502-49291-9-git-send-email-wangnan0@huawei.com
[ Add the new options to the 'record' man page ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-record.txt

@@ -314,6 +314,12 @@ This option sets the time out limit. The default value is 500 ms.
 Record context switch events i.e. events of type PERF_RECORD_SWITCH or
 PERF_RECORD_SWITCH_CPU_WIDE.
 
+--clang-path::
+Path to clang binary to use for compiling BPF scriptlets.
+
+--clang-opt::
+Options passed to clang when compiling BPF scriptlets.
+
 SEE ALSO
 --------
 linkperf:perf-stat[1], linkperf:perf-list[1]

tools/perf/builtin-record.c

@@ -31,6 +31,7 @@
 #include "util/auxtrace.h"
 #include "util/parse-branch-options.h"
 #include "util/parse-regs-options.h"
+#include "util/llvm-utils.h"
 
 #include <unistd.h>
 #include <sched.h>
@@ -1112,6 +1113,12 @@ struct option __record_options[] = {
 			"per thread proc mmap processing timeout in ms"),
 	OPT_BOOLEAN(0, "switch-events", &record.opts.record_switch_events,
 		    "Record context switch events"),
+#ifdef HAVE_LIBBPF_SUPPORT
+	OPT_STRING(0, "clang-path", &llvm_param.clang_path, "clang path",
+		   "clang binary to use for compiling BPF scriptlets"),
+	OPT_STRING(0, "clang-opt", &llvm_param.clang_opt, "clang options",
+		   "options passed to clang when compiling BPF scriptlets"),
+#endif
 	OPT_END()
 };