[PATCH 5/5] perf annotate: Add --skip-empty option

[Namhyung Kim <namhyung@kernel.org>]

Like in perf report, we want to hide empty events in the perf annotate
output.  This is consistent when the option is set in perf report.

For example, the following command would use 3 events including dummy.

  $ perf mem record -a -- perf test -w noploop

  $ perf evlist
  cpu/mem-loads,ldlat=30/P
  cpu/mem-stores/P
  dummy:u

Just using perf annotate with --group will show the all 3 events.

  $ perf annotate --group --stdio | head
   Percent                 |	Source code & Disassembly of ...
  --------------------------------------------------------------
                           : 0     0xe060 <_dl_relocate_object>:
      0.00    0.00    0.00 :    e060:       pushq   %rbp
      0.00    0.00    0.00 :    e061:       movq    %rsp, %rbp
      0.00    0.00    0.00 :    e064:       pushq   %r15
      0.00    0.00    0.00 :    e066:       movq    %rdi, %r15
      0.00    0.00    0.00 :    e069:       pushq   %r14
      0.00    0.00    0.00 :    e06b:       pushq   %r13
      0.00    0.00    0.00 :    e06d:       movl    %edx, %r13d

Now with --skip-empty, it'll hide the last dummy event.

  $ perf annotate --group --stdio --skip-empty | head
   Percent         |	Source code & Disassembly of ...
  ------------------------------------------------------
                   : 0     0xe060 <_dl_relocate_object>:
      0.00    0.00 :    e060:       pushq   %rbp
      0.00    0.00 :    e061:       movq    %rsp, %rbp
      0.00    0.00 :    e064:       pushq   %r15
      0.00    0.00 :    e066:       movq    %rdi, %r15
      0.00    0.00 :    e069:       pushq   %r14
      0.00    0.00 :    e06b:       pushq   %r13
      0.00    0.00 :    e06d:       movl    %edx, %r13d

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/Documentation/perf-annotate.txt |  3 +++
 tools/perf/builtin-annotate.c              |  2 ++
 tools/perf/util/annotate.c                 | 22 +++++++++++++++++-----
 3 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/tools/perf/Documentation/perf-annotate.txt b/tools/perf/Documentation/perf-annotate.txt
index b95524bea021..156c5f37b051 100644
--- a/tools/perf/Documentation/perf-annotate.txt
+++ b/tools/perf/Documentation/perf-annotate.txt
@@ -165,6 +165,9 @@ include::itrace.txt[]
 --type-stat::
 	Show stats for the data type annotation.
 
+--skip-empty::
+	Do not display empty (or dummy) events.
+
 
 SEE ALSO
 --------
diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
index cf60392b1c19..efcadb7620b8 100644
--- a/tools/perf/builtin-annotate.c
+++ b/tools/perf/builtin-annotate.c
@@ -795,6 +795,8 @@ int cmd_annotate(int argc, const char **argv)
 		    "Show stats for the data type annotation"),
 	OPT_BOOLEAN(0, "insn-stat", &annotate.insn_stat,
 		    "Show instruction stats for the data type annotation"),
+	OPT_BOOLEAN(0, "skip-empty", &symbol_conf.skip_empty,
+		    "Do not display empty (or dummy) events in the output"),
 	OPT_END()
 	};
 	int ret;
diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
index 917897fe44a2..eafe8d65052e 100644
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -848,6 +848,10 @@ static void annotation__calc_percent(struct annotation *notes,
 
 			BUG_ON(i >= al->data_nr);
 
+			if (symbol_conf.skip_empty &&
+			    evsel__hists(evsel)->stats.nr_samples == 0)
+				continue;
+
 			data = &al->data[i++];
 
 			calc_percent(notes, evsel, data, al->offset, end);
@@ -901,7 +905,7 @@ int symbol__annotate(struct map_symbol *ms, struct evsel *evsel,
 		.options	= &annotate_opts,
 	};
 	struct arch *arch = NULL;
-	int err;
+	int err, nr;
 
 	err = evsel__get_arch(evsel, &arch);
 	if (err < 0)
@@ -922,10 +926,18 @@ int symbol__annotate(struct map_symbol *ms, struct evsel *evsel,
 			return -1;
 	}
 
-	if (evsel__is_group_event(evsel))
-		notes->src->nr_events = evsel->core.nr_members;
-	else
-		notes->src->nr_events = 1;
+	nr = 0;
+	if (evsel__is_group_event(evsel)) {
+		struct evsel *pos;
+
+		for_each_group_evsel(pos, evsel) {
+			if (symbol_conf.skip_empty &&
+			    evsel__hists(pos)->stats.nr_samples == 0)
+				continue;
+			nr++;
+		}
+	}
+	notes->src->nr_events = nr ? nr : 1;
 
 	if (annotate_opts.full_addr)
 		notes->src->start = map__objdump_2mem(ms->map, ms->sym->start);
-- 
2.46.0.rc2.264.g509ed76dc8-goog