perf hist: Support multi-line header

This is a preparation to support multi-line headers in 'perf mem report'.

Normal sort keys and output fields that don't have contents for multi-
line will print the header string at the last line only.

As we don't use multi-line headers normally, it should not have any
changes in the output.

Signed-off-by: Namhyung Kim <[e-mail]>
Tested-by: Arnaldo Carvalho de Melo <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Kan Liang <[e-mail]>
Cc: Leo Yan <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Ravi Bangoria <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/ui/browsers/hists.c

···
 	return ret;
 }
 
-static int hists_browser__scnprintf_hierarchy_headers(struct hist_browser *browser, char *buf, size_t size)
+static int hists_browser__scnprintf_hierarchy_headers(struct hist_browser *browser,
+						      char *buf, size_t size, int line)
 {
 	struct hists *hists = browser->hists;
 	struct perf_hpp dummy_hpp = {
···
 		if (column++ < browser->b.horiz_scroll)
 			continue;
 
-		ret = fmt->header(fmt, &dummy_hpp, hists, 0, NULL);
+		ret = fmt->header(fmt, &dummy_hpp, hists, line, NULL);
 		if (advance_hpp_check(&dummy_hpp, ret))
 			break;
 
···
 
 		first_node = false;
 	}
+
+	if (line < hists->hpp_list->nr_header_lines - 1)
+		return ret;
 
 	if (!first_node) {
 		ret = scnprintf(dummy_hpp.buf, dummy_hpp.size, "%*s",
···
 			}
 			first_col = false;
 
-			ret = fmt->header(fmt, &dummy_hpp, hists, 0, NULL);
+			ret = fmt->header(fmt, &dummy_hpp, hists, line, NULL);
 			dummy_hpp.buf[ret] = '\0';
 
 			start = strim(dummy_hpp.buf);
···
 
 static void hists_browser__hierarchy_headers(struct hist_browser *browser)
 {
+	struct perf_hpp_list *hpp_list = browser->hists->hpp_list;
 	char headers[1024];
+	int line;
 
-	hists_browser__scnprintf_hierarchy_headers(browser, headers,
-						   sizeof(headers));
+	for (line = 0; line < hpp_list->nr_header_lines; line++) {
+		hists_browser__scnprintf_hierarchy_headers(browser, headers,
+							   sizeof(headers), line);
 
-	ui_browser__gotorc_title(&browser->b, 0, 0);
-	ui_browser__set_color(&browser->b, HE_COLORSET_ROOT);
-	ui_browser__write_nstring(&browser->b, headers, browser->b.width + 1);
+		ui_browser__gotorc_title(&browser->b, line, 0);
+		ui_browser__set_color(&browser->b, HE_COLORSET_ROOT);
+		ui_browser__write_nstring(&browser->b, headers, browser->b.width + 1);
+	}
 }
 
 static void hists_browser__headers(struct hist_browser *browser)

tools/perf/ui/hist.c

···
 }
 
 static int hpp__header_fn(struct perf_hpp_fmt *fmt, struct perf_hpp *hpp,
-			  struct hists *hists, int line __maybe_unused,
+			  struct hists *hists, int line,
 			  int *span __maybe_unused)
 {
 	int len = hpp__width_fn(fmt, hpp, hists);
-	return scnprintf(hpp->buf, hpp->size, "%*s", len, fmt->name);
+	const char *hdr = "";
+
+	if (line == hists->hpp_list->nr_header_lines - 1)
+		hdr = fmt->name;
+
+	return scnprintf(hpp->buf, hpp->size, "%*s", len, hdr);
 }
 
 int hpp_color_scnprintf(struct perf_hpp *hpp, const char *fmt, ...)

tools/perf/ui/stdio/hist.c

···
 	unsigned header_width = 0;
 	struct perf_hpp_fmt *fmt;
 	struct perf_hpp_list_node *fmt_node;
+	struct perf_hpp_list *hpp_list = hists->hpp_list;
 	const char *sep = symbol_conf.field_sep;
 
 	indent = hists->nr_hpp_node;
-
-	/* preserve max indent depth for column headers */
-	print_hierarchy_indent(sep, indent, " ", fp);
 
 	/* the first hpp_list_node is for overhead columns */
 	fmt_node = list_first_entry(&hists->hpp_formats,
 				    struct perf_hpp_list_node, list);
 
-	perf_hpp_list__for_each_format(&fmt_node->hpp, fmt) {
-		fmt->header(fmt, hpp, hists, 0, NULL);
-		fprintf(fp, "%s%s", hpp->buf, sep ?: "  ");
-	}
+	for (int line = 0; line < hpp_list->nr_header_lines; line++) {
+		/* first # is displayed one level up */
+		if (line)
+			fprintf(fp, "# ");
 
-	/* combine sort headers with ' / ' */
-	first_node = true;
-	list_for_each_entry_continue(fmt_node, &hists->hpp_formats, list) {
-		if (!first_node)
-			header_width += fprintf(fp, " / ");
-		first_node = false;
+		/* preserve max indent depth for column headers */
+		print_hierarchy_indent(sep, indent, " ", fp);
 
-		first_col = true;
 		perf_hpp_list__for_each_format(&fmt_node->hpp, fmt) {
-			if (perf_hpp__should_skip(fmt, hists))
-				continue;
-
-			if (!first_col)
-				header_width += fprintf(fp, "+");
-			first_col = false;
-
-			fmt->header(fmt, hpp, hists, 0, NULL);
-
-			header_width += fprintf(fp, "%s", strim(hpp->buf));
+			fmt->header(fmt, hpp, hists, line, NULL);
+			fprintf(fp, "%s%s", hpp->buf, sep ?: "  ");
 		}
+
+		if (line < hpp_list->nr_header_lines - 1)
+			goto next_line;
+
+		/* combine sort headers with ' / ' */
+		first_node = true;
+		list_for_each_entry_continue(fmt_node, &hists->hpp_formats, list) {
+			if (!first_node)
+				header_width += fprintf(fp, " / ");
+			first_node = false;
+
+			first_col = true;
+			perf_hpp_list__for_each_format(&fmt_node->hpp, fmt) {
+				if (perf_hpp__should_skip(fmt, hists))
+					continue;
+
+				if (!first_col)
+					header_width += fprintf(fp, "+");
+				first_col = false;
+
+				fmt->header(fmt, hpp, hists, line, NULL);
+
+				header_width += fprintf(fp, "%s", strim(hpp->buf));
+			}
+		}
+
+next_line:
+		fprintf(fp, "\n");
 	}
 
-	fprintf(fp, "\n# ");
+	fprintf(fp, "# ");
 
 	/* preserve max indent depth for initial dots */
 	print_hierarchy_indent(sep, indent, dots, fp);

tools/perf/util/sort.c

···
 }
 
 static int __sort__hpp_header(struct perf_hpp_fmt *fmt, struct perf_hpp *hpp,
-			      struct hists *hists, int line __maybe_unused,
+			      struct hists *hists, int line,
 			      int *span __maybe_unused)
 {
 	struct hpp_sort_entry *hse;
 	size_t len = fmt->user_len;
+	const char *hdr = "";
+
+	if (line == hists->hpp_list->nr_header_lines - 1)
+		hdr = fmt->name;
 
 	hse = container_of(fmt, struct hpp_sort_entry, hpp);
 
 	if (!len)
 		len = hists__col_len(hists, hse->se->se_width_idx);
 
-	return scnprintf(hpp->buf, hpp->size, "%-*.*s", len, len, fmt->name);
+	return scnprintf(hpp->buf, hpp->size, "%-*.*s", len, len, hdr);
 }
 
 static int __sort__hpp_width(struct perf_hpp_fmt *fmt,