perf annotate: Display the branch counter histogram

Display the branch counter histogram in the annotation view.

Press 'B' to display the branch counter's abbreviation list as well.

Samples: 1M of events 'anon group { branch-instructions:ppp, branch-misses }',
4000 Hz, Event count (approx.):
f3 /home/sdp/test/tchain_edit [Percent: local period]
Percent │ IPC Cycle Branch Counter (Average IPC: 1.39, IPC Coverage: 29.4%)
│ 0000000000401755 <f3>:
0.00 0.00 │ endbr64
│ push %rbp
│ mov %rsp,%rbp
│ movl $0x0,-0x4(%rbp)
0.00 0.00 │1.33 3 |A |- | ↓ jmp 25
11.03 11.03 │ 11: mov -0x4(%rbp),%eax
│ and $0x1,%eax
│ test %eax,%eax
17.13 17.13 │2.41 1 |A |- | ↓ je 21
│ addl $0x1,-0x4(%rbp)
21.84 21.84 │2.22 2 |AA |- | ↓ jmp 25
17.13 17.13 │ 21: addl $0x1,-0x4(%rbp)
21.84 21.84 │ 25: cmpl $0x270f,-0x4(%rbp)
11.03 11.03 │0.61 3 |A |- | ↑ jle 11
│ nop
│ pop %rbp
0.00 0.00 │0.24 20 |AA |B | ← ret

Originally-by: Tinghao Zhang <[e-mail]>
Reviewed-by: Andi Kleen <[e-mail]>
Signed-off-by: Kan Liang <[e-mail]>
Acked-by: Namhyung Kim <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Stephane Eranian <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/builtin-annotate.c

···
 		sort_order = "dso,symbol";
 
 	/*
-	 * Set SORT_MODE__BRANCH so that annotate display IPC/Cycle
-	 * if branch info is in perf data in TUI mode.
+	 * Set SORT_MODE__BRANCH so that annotate displays IPC/Cycle and
+	 * branch counters, if the corresponding branch info is available
+	 * in the perf data in the TUI mode.
 	 */
-	if ((use_browser == 1 || annotate.use_stdio2) && annotate.has_br_stack)
+	if ((use_browser == 1 || annotate.use_stdio2) && annotate.has_br_stack) {
 		sort__mode = SORT_MODE__BRANCH;
+		if (annotate.session->evlist->nr_br_cntr > 0)
+			annotate_opts.show_br_cntr = true;
+	}
 
 	if (setup_sorting(NULL) < 0)
 		usage_with_options(annotate_usage, options);

tools/perf/ui/browsers/annotate.c

···
 	struct symbol *sym = ms->sym;
 	struct annotation *notes = symbol__annotation(sym);
 	u8 pcnt_width = annotation__pcnt_width(notes);
+	u8 cntr_width = annotation__br_cntr_width();
 	int width;
 	int diff = 0;
 
···
 
 	ui_browser__set_color(browser, HE_COLORSET_JUMP_ARROWS);
 	__ui_browser__line_arrow(browser,
-				 pcnt_width + 2 + notes->src->widths.addr + width,
+				 pcnt_width + 2 + notes->src->widths.addr + width + cntr_width,
 				 from, to);
 
 	diff = is_fused(ab, cursor);
 	if (diff > 0) {
 		ui_browser__mark_fused(browser,
-				       pcnt_width + 3 + notes->src->widths.addr + width,
+				       pcnt_width + 3 + notes->src->widths.addr + width + cntr_width,
 				       from - diff, diff, to > from);
 	}
 }
···
 	struct annotation *notes = symbol__annotation(ms->sym);
 	const char *help = "Press 'h' for help on key bindings";
 	int delay_secs = hbt ? hbt->refresh : 0;
+	char *br_cntr_text = NULL;
 	char title[256];
 	int key;
 
···
 	}
 
 	nd = browser->curr_hot;
+
+	annotation_br_cntr_abbr_list(&br_cntr_text, evsel, false);
 
 	while (1) {
 		key = ui_browser__run(&browser->b, delay_secs);
···
 		"r             Run available scripts\n"
 		"p             Toggle percent type [local/global]\n"
 		"b             Toggle percent base [period/hits]\n"
+		"B             Branch counter abbr list (Optional)\n"
 		"?             Search string backwards\n"
 		"f             Toggle showing offsets to full address\n");
 			continue;
···
 			hists__scnprintf_title(hists, title, sizeof(title));
 			annotate_browser__show(&browser->b, title, help);
 			continue;
+		case 'B':
+			if (br_cntr_text)
+				ui_browser__help_window(&browser->b, br_cntr_text);
+			else {
+				ui_browser__help_window(&browser->b,
+							"\n The branch counter is not available.\n");
+			}
+			continue;
 		case 'f':
 			annotation__toggle_full_addr(notes, ms);
 			continue;
···
 	}
 out:
 	ui_browser__hide(&browser->b);
+	free(br_cntr_text);
 	return key;
 }
 

tools/perf/ui/browsers/hists.c

···
 
 	memset(&action, 0, sizeof(action));
 
-	annotation_br_cntr_abbr_list(&br_cntr_text, evsel, false);
+	if (!annotation_br_cntr_abbr_list(&br_cntr_text, evsel, false))
+		annotate_opts.show_br_cntr = true;
 
 	while (1) {
 		key = hist_browser__run(browser, "? - help", true, 0);

tools/perf/util/annotate.c

···
 	}
 }
 
-static int annotation__compute_ipc(struct annotation *notes, size_t size)
+static int annotation__compute_ipc(struct annotation *notes, size_t size,
+				   struct evsel *evsel)
 {
+	unsigned int br_cntr_nr = evsel->evlist->nr_br_cntr;
 	int err = 0;
 	s64 offset;
 
···
 				al->cycles->max = ch->cycles_max;
 				al->cycles->min = ch->cycles_min;
 			}
+			if (al && notes->branch->br_cntr) {
+				if (!al->br_cntr) {
+					al->br_cntr = calloc(br_cntr_nr, sizeof(u64));
+					if (!al->br_cntr) {
+						err = ENOMEM;
+						break;
+					}
+				}
+				al->num_aggr = ch->num_aggr;
+				al->br_cntr_nr = br_cntr_nr;
+				al->evsel = evsel;
+				memcpy(al->br_cntr, &notes->branch->br_cntr[offset * br_cntr_nr],
+				       br_cntr_nr * sizeof(u64));
+			}
 		}
 	}
 
···
 				struct annotation_line *al;
 
 				al = annotated_source__get_line(notes->src, offset);
-				if (al)
+				if (al) {
 					zfree(&al->cycles);
+					zfree(&al->br_cntr);
+				}
 			}
 		}
 	}
···
 					    "Cycle(min/max)");
 		}
 
+		if (annotate_opts.show_br_cntr) {
+			if (show_title) {
+				obj__printf(obj, "%*s ",
+					    ANNOTATION__BR_CNTR_WIDTH,
+					    "Branch Counter");
+			} else {
+				char *buf;
+
+				if (!annotation_br_cntr_entry(&buf, al->br_cntr_nr, al->br_cntr,
+							      al->num_aggr, al->evsel)) {
+					obj__printf(obj, "%*s ", ANNOTATION__BR_CNTR_WIDTH, buf);
+					free(buf);
+				}
+			}
+		}
+
 		if (show_title && !*al->line) {
 			ipc_coverage_string(bf, sizeof(bf), notes);
 			obj__printf(obj, "%*s", ANNOTATION__AVG_IPC_WIDTH, bf);
···
 	annotation__set_index(notes);
 	annotation__mark_jump_targets(notes, sym);
 
-	err = annotation__compute_ipc(notes, size);
+	err = annotation__compute_ipc(notes, size, evsel);
 	if (err)
 		return err;
 

tools/perf/util/annotate.h

···
 #define ANNOTATION__CYCLES_WIDTH 6
 #define ANNOTATION__MINMAX_CYCLES_WIDTH 19
 #define ANNOTATION__AVG_IPC_WIDTH 36
+#define ANNOTATION__BR_CNTR_WIDTH 30
 #define ANNOTATION_DUMMY_LEN	256
 
 struct annotation_options {
···
 	     show_nr_jumps,
 	     show_minmax_cycle,
 	     show_asm_raw,
+	     show_br_cntr,
 	     annotate_src,
 	     full_addr;
 	u8   offset_level;
···
 	char			*fileloc;
 	char			*path;
 	struct cycles_info	*cycles;
+	int			 num_aggr;
+	int			 br_cntr_nr;
+	u64			*br_cntr;
+	struct evsel		*evsel;
 	int			 jump_sources;
 	u32			 idx;
 	int			 idx_asm;
···
 static inline bool annotation_line__filter(struct annotation_line *al)
 {
 	return annotate_opts.hide_src_code && al->offset == -1;
+}
+
+static inline u8 annotation__br_cntr_width(void)
+{
+	return annotate_opts.show_br_cntr ? ANNOTATION__BR_CNTR_WIDTH : 0;
 }
 
 void annotation__update_column_widths(struct annotation *notes);

tools/perf/util/disasm.c

···
 	zfree_srcline(&al->path);
 	zfree(&al->line);
 	zfree(&al->cycles);
+	zfree(&al->br_cntr);
 }
 
 static size_t disasm_line_size(int nr)