perf hists: Basic support of hierarchical report view

In the hierarchical view, entries will be grouped and sorted on the
first key, and then on the second key, and so on.  Add the
he->hroot_{in,out} fields to keep the lower level entries. Actually this
can share space, in a union, with callchain's 'sorted_root' since the
hroots are only used by non-leaf entries and callchain is only used by
leaf entries.

It also adds the 'parent_he' and 'depth' fields which can be used by browsers.

This patch only implements collapsing part which creates internal
entries for each sort key.  These need to be sorted by output_sort stage
and to be displayed properly in the later patch(es).

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1456326830-30456-3-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/sort.h b/tools/perf/util/sort.h
index 5b9c624..10315e0 100644
--- a/tools/perf/util/sort.h
+++ b/tools/perf/util/sort.h
@@ -96,9 +96,11 @@
 	s32			socket;
 	s32			cpu;
 	u8			cpumode;
+	u8			depth;
 
 	/* We are added by hists__add_dummy_entry. */
 	bool			dummy;
+	bool			leaf;
 
 	char			level;
 	u8			filtered;
@@ -120,13 +122,22 @@
 	char			*srcline;
 	char			*srcfile;
 	struct symbol		*parent;
-	struct rb_root		sorted_chain;
 	struct branch_info	*branch_info;
 	struct hists		*hists;
 	struct mem_info		*mem_info;
 	void			*raw_data;
 	u32			raw_size;
 	void			*trace_output;
+	struct perf_hpp_fmt	*fmt;
+	struct hist_entry	*parent_he;
+	union {
+		/* this is for hierarchical entry structure */
+		struct {
+			struct rb_root	hroot_in;
+			struct rb_root  hroot_out;
+		};				/* non-leaf entries */
+		struct rb_root	sorted_chain;	/* leaf entry has callchains */
+	};
 	struct callchain_root	callchain[0]; /* must be last member */
 };