perf tools: Make options always available, even if required libs not linked

This patch keeps options of perf builtins same in all conditions. If
one option is disabled because of compiling options, users should be
notified.

Masami suggested another implementation in [1] that, by adding a
OPTION_NEXT_DEPENDS option before those options in the 'struct option'
array, options parser knows an option is disabled. However, in some
cases this array is reordered (options__order()). In addition, in
parse-option.c that array is const, so we can't simply merge
information in decorator option into the affacted option.

This patch chooses a simpler implementation that, introducing a
set_option_nobuild() function and two option parsing flags. Builtins
with such options should call set_option_nobuild() before option
parsing. The complexity of this patch is because we want some of options
can be skipped safely. In this case their arguments should also be
consumed.

Options in 'perf record' and 'perf probe' are fixed in this patch.

[1] http://lkml.kernel.org/g/50399556C9727B4D88A595C8584AAB3752627CD4@GSjpTKYDCembx32.service.hitachi.net

Test result:

Normal case:

  # ./perf probe --vmlinux /tmp/vmlinux sys_write
  Added new event:
    probe:sys_write      (on sys_write)

  You can now use it in all perf tools, such as:

	perf record -e probe:sys_write -aR sleep 1

Build with NO_DWARF=1:

  # ./perf probe -L sys_write
    Error: switch `L' is not available because NO_DWARF=1

   Usage: perf probe [<options>] 'PROBEDEF' ['PROBEDEF' ...]
      or: perf probe [<options>] --add 'PROBEDEF' [--add 'PROBEDEF' ...]
      or: perf probe [<options>] --del '[GROUP:]EVENT' ...
      or: perf probe --list [GROUP:]EVENT ...
      or: perf probe [<options>] --funcs

    -L, --line <FUNC[:RLN[+NUM|-RLN2]]|SRC:ALN[+NUM|-ALN2]>
                          Show source code lines.
                          (not built-in because NO_DWARF=1)

  # ./perf probe -k /tmp/vmlinux sys_write
    Warning: switch `k' is being ignored because NO_DWARF=1
  Added new event:
    probe:sys_write      (on sys_write)

  You can now use it in all perf tools, such as:

	perf record -e probe:sys_write -aR sleep 1

  # ./perf probe --vmlinux /tmp/vmlinux sys_write
    Warning: option `vmlinux' is being ignored because NO_DWARF=1
  Added new event:
  [SNIP]

  # ./perf probe -l
   Usage: perf probe [<options>] 'PROBEDEF' ['PROBEDEF' ...]
      or: perf probe [<options>] --add 'PROBEDEF' [--add 'PROBEDEF' ...]
...
    -k, --vmlinux <file>  vmlinux pathname
                          (not built-in because NO_DWARF=1)
    -L, --line <FUNC[:RLN[+NUM|-RLN2]]|SRC:ALN[+NUM|-ALN2]>
                          Show source code lines.
                          (not built-in because NO_DWARF=1)
...
    -V, --vars <FUNC[@SRC][+OFF|%return|:RL|;PT]|SRC:AL|SRC;PT>
                          Show accessible variables on PROBEDEF
                          (not built-in because NO_DWARF=1)
        --externs         Show external variables too (with --vars only)
                          (not built-in because NO_DWARF=1)
        --no-inlines      Don't search inlined functions
                          (not built-in because NO_DWARF=1)
        --range           Show variables location range in scope (with --vars only)
                          (not built-in because NO_DWARF=1)

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1450089563-122430-14-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-record.c

@@ -1113,12 +1113,10 @@ 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()
 };
 
@@ -1130,6 +1128,13 @@ int cmd_record(int argc, const char **argv, const char *prefix __maybe_unused)
 	struct record *rec = &record;
 	char errbuf[BUFSIZ];
 
+#ifndef HAVE_LIBBPF_SUPPORT
+# define set_nobuild(s, l, c) set_option_nobuild(record_options, s, l, "NO_LIBBPF=1", c)
+	set_nobuild('\0', "clang-path", true);
+	set_nobuild('\0', "clang-opt", true);
+# undef set_nobuild
+#endif
+
 	rec->evlist = perf_evlist__new();
 	if (rec->evlist == NULL)
 		return -ENOMEM;