perf/core improvements:

New features:
 
 - Show ordered command line options when -h is used or when an
   unknown options is specified (Arnaldo Carvalho de Melo)
 
 - If options are passed after -h, show just its descriptions, not
   all options (Arnaldo Carvalho de Melo)
 
 Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v1
 
 iQIcBAABAgAGBQJWKtbAAAoJENZQFvNTUqpAl8sP/0zdmfJFPIYN2R8UuR3R+Eyx
 Es7m6a3CjVJl3jaki3tlBaH6inPkb1T9EBSx1GxPVnHt9hzzpf9nWnmiNy75ZTkQ
 cHkCYCGTkcAMHIcc3ANsyOMc1RJ151zsCCpolF6Lk4WIbN/FWX1Xf5dIs6zlxxMF
 QUxMMOL/bGR/8QR/oYQ4Zko+E1SMsPSTGwWyGS1LO2G4AY9NbGDh3dLK77Lb5rRH
 7dblrlmwT0WhUJRI/Ph84efG0CsHgH7e69a8uDEMPoNWOorAIHwvvpIQw2YcXcgb
 TYx3Y8YQe3SAuuenl06usLbMB3NBxVkC3mgGPwdeMcqak11wPZESTpdabQML0XSI
 IPxbofIHKifYo8YyIPFd/f0VO/qtQZILZsGP4M16opNFwP5WNApj2LRGCuZ3r1p/
 Fo1n4wih7GfAO8zA0QGxgNESbPSSmweM6QLulZrAYJEf9RUXhoE5+//YUO9to/GC
 3eNPxVsJCeBnJopH4FbSqr1FHKgu5pzneWX6lv0NiPzOSi17V6FVQrIX/e4rOsor
 apMX85mX0r51W8mejuOPAEhcaDdFUVqnoSOyb69bdHdFjwQ+vPemFlpYEhIv2DiQ
 khqJG6or/dJUjkF1pIRF33Eyr43r3yWu0Plu5pCjSm5vXfNHLVuqJNkMGoZlP3dR
 QK1uTL37s2aUKKvTR1i7
 =bJOf
 -----END PGP SIGNATURE-----

Merge tag 'perf-core-for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core

Pull perf/core improvements from Arnaldo Carvalho de Melo:

New user-visible features:

  - Show ordered command line options when -h is used or when an
    unknown option is specified. (Arnaldo Carvalho de Melo)

  - If options are passed after -h, show just its descriptions, not
    all options. (Arnaldo Carvalho de Melo)

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

tools/perf/util/parse-options.c

@@ -2,6 +2,7 @@
 #include "parse-options.h"
 #include "cache.h"
 #include "header.h"
+#include <linux/string.h>
 
 #define OPT_SHORT 1
 #define OPT_UNSET 2
@@ -372,7 +373,8 @@ void parse_options_start(struct parse_opt_ctx_t *ctx,
 }
 
 static int usage_with_options_internal(const char * const *,
-				       const struct option *, int);
+				       const struct option *, int,
+				       struct parse_opt_ctx_t *);
 
 int parse_options_step(struct parse_opt_ctx_t *ctx,
 		       const struct option *options,
@@ -396,8 +398,9 @@ int parse_options_step(struct parse_opt_ctx_t *ctx,
 
 		if (arg[1] != '-') {
 			ctx->opt = ++arg;
-			if (internal_help && *ctx->opt == 'h')
-				return usage_with_options_internal(usagestr, options, 0);
+			if (internal_help && *ctx->opt == 'h') {
+				return usage_with_options_internal(usagestr, options, 0, ctx);
+			}
 			switch (parse_short_opt(ctx, options)) {
 			case -1:
 				return parse_options_usage(usagestr, options, arg, 1);
@@ -412,7 +415,7 @@ int parse_options_step(struct parse_opt_ctx_t *ctx,
 				check_typos(arg, options);
 			while (ctx->opt) {
 				if (internal_help && *ctx->opt == 'h')
-					return usage_with_options_internal(usagestr, options, 0);
+					return usage_with_options_internal(usagestr, options, 0, ctx);
 				arg = ctx->opt;
 				switch (parse_short_opt(ctx, options)) {
 				case -1:
@@ -445,9 +448,9 @@ int parse_options_step(struct parse_opt_ctx_t *ctx,
 
 		arg += 2;
 		if (internal_help && !strcmp(arg, "help-all"))
-			return usage_with_options_internal(usagestr, options, 1);
+			return usage_with_options_internal(usagestr, options, 1, ctx);
 		if (internal_help && !strcmp(arg, "help"))
-			return usage_with_options_internal(usagestr, options, 0);
+			return usage_with_options_internal(usagestr, options, 0, ctx);
 		if (!strcmp(arg, "list-opts"))
 			return PARSE_OPT_LIST_OPTS;
 		if (!strcmp(arg, "list-cmds"))
@@ -642,9 +645,69 @@ static void print_option_help(const struct option *opts, int full)
 	fprintf(stderr, "%*s%s\n", pad + USAGE_GAP, "", opts->help);
 }
 
-int usage_with_options_internal(const char * const *usagestr,
-				const struct option *opts, int full)
+static int option__cmp(const void *va, const void *vb)
 {
+	const struct option *a = va, *b = vb;
+	int sa = tolower(a->short_name), sb = tolower(b->short_name), ret;
+
+	if (sa == 0)
+		sa = 'z' + 1;
+	if (sb == 0)
+		sb = 'z' + 1;
+
+	ret = sa - sb;
+
+	if (ret == 0) {
+		const char *la = a->long_name ?: "",
+			   *lb = b->long_name ?: "";
+		ret = strcmp(la, lb);
+	}
+
+	return ret;
+}
+
+static struct option *options__order(const struct option *opts)
+{
+	int nr_opts = 0;
+	const struct option *o = opts;
+	struct option *ordered;
+
+	for (o = opts; o->type != OPTION_END; o++)
+		++nr_opts;
+
+	ordered = memdup(opts, sizeof(*o) * (nr_opts + 1));
+	if (ordered == NULL)
+		goto out;
+
+	qsort(ordered, nr_opts, sizeof(*o), option__cmp);
+out:
+	return ordered;
+}
+
+static bool option__in_argv(const struct option *opt, const struct parse_opt_ctx_t *ctx)
+{
+	int i;
+
+	for (i = 1; i < ctx->argc; ++i) {
+		const char *arg = ctx->argv[i];
+
+		if (arg[0] != '-')
+			continue;
+
+		if (arg[1] == opt->short_name ||
+		    (arg[1] == '-' && opt->long_name && strcmp(opt->long_name, arg + 2) == 0))
+			return true;
+	}
+
+	return false;
+}
+
+int usage_with_options_internal(const char * const *usagestr,
+				const struct option *opts, int full,
+				struct parse_opt_ctx_t *ctx)
+{
+	struct option *ordered;
+
 	if (!usagestr)
 		return PARSE_OPT_HELP;
 
@@ -661,11 +724,20 @@ int usage_with_options_internal(const char * const *usagestr,
 	if (opts->type != OPTION_GROUP)
 		fputc('\n', stderr);
 
-	for (  ; opts->type != OPTION_END; opts++)
+	ordered = options__order(opts);
+	if (ordered)
+		opts = ordered;
+
+	for (  ; opts->type != OPTION_END; opts++) {
+		if (ctx && ctx->argc > 1 && !option__in_argv(opts, ctx))
+			continue;
 		print_option_help(opts, full);
+	}
 
 	fputc('\n', stderr);
 
+	free(ordered);
+
 	return PARSE_OPT_HELP;
 }
 
@@ -673,7 +745,7 @@ void usage_with_options(const char * const *usagestr,
 			const struct option *opts)
 {
 	exit_browser(false);
-	usage_with_options_internal(usagestr, opts, 0);
+	usage_with_options_internal(usagestr, opts, 0, NULL);
 	exit(129);
 }