perf annotate: Add basic support to event group view

Add --group option to enable event grouping.  When enabled, all the
group members information will be shown with the leader so skip
non-leader events.

It only supports --stdio output currently.  Later patches will extend
additional features.

 $ perf annotate --group --stdio
 ...
  Percent                 |      Source code & Disassembly of libpthread-2.15.so
 --------------------------------------------------------------------------------
                          :
                          :
                          :
                          :      Disassembly of section .text:
                          :
                          :      000000387dc0aa50 <__pthread_mutex_unlock_usercnt>:
     8.08    2.40    5.29 :        387dc0aa50:   mov    %rdi,%rdx
     0.00    0.00    0.00 :        387dc0aa53:   mov    0x10(%rdi),%edi
     0.00    0.00    0.00 :        387dc0aa56:   mov    %edi,%eax
     0.00    0.80    0.00 :        387dc0aa58:   and    $0x7f,%eax
     3.03    2.40    3.53 :        387dc0aa5b:   test   $0x7c,%dil
     0.00    0.00    0.00 :        387dc0aa5f:   jne    387dc0aaa9 <__pthread_mutex_unlock_use
     0.00    0.00    0.00 :        387dc0aa61:   test   %eax,%eax
     0.00    0.00    0.00 :        387dc0aa63:   jne    387dc0aa85 <__pthread_mutex_unlock_use
     0.00    0.00    0.00 :        387dc0aa65:   and    $0x80,%edi
     0.00    0.00    0.00 :        387dc0aa6b:   test   %esi,%esi
     3.03    5.60    7.06 :        387dc0aa6d:   movl   $0x0,0x8(%rdx)
     0.00    0.00    0.59 :        387dc0aa74:   je     387dc0aa7a <__pthread_mutex_unlock_use
     0.00    0.00    0.00 :        387dc0aa76:   subl   $0x1,0xc(%rdx)
     2.02    5.60    1.18 :        387dc0aa7a:   mov    %edi,%esi
     0.00    0.00    0.00 :        387dc0aa7c:   lock decl (%rdx)
    83.84   83.20   82.35 :        387dc0aa7f:   jne    387dc0aada <_L_unlock_586>
     0.00    0.00    0.00 :        387dc0aa81:   nop
     0.00    0.00    0.00 :        387dc0aa82:   xor    %eax,%eax
     0.00    0.00    0.00 :        387dc0aa84:   retq
 ...

Signed-off-by: Namhyung Kim <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
index 2f015a9..ae36f3c 100644
--- a/tools/perf/builtin-annotate.c
+++ b/tools/perf/builtin-annotate.c
@@ -232,6 +232,11 @@
 			total_nr_samples += nr_samples;
 			hists__collapse_resort(hists);
 			hists__output_resort(hists);
+
+			if (symbol_conf.event_group &&
+			    !perf_evsel__is_group_leader(pos))
+				continue;
+
 			hists__find_annotations(hists, pos, ann);
 		}
 	}
@@ -314,6 +319,8 @@
 		   "Specify disassembler style (e.g. -M intel for intel syntax)"),
 	OPT_STRING(0, "objdump", &objdump_path, "path",
 		   "objdump binary to use for disassembly and annotations"),
+	OPT_BOOLEAN(0, "group", &symbol_conf.event_group,
+		    "Show event group information together"),
 	OPT_END()
 	};