[PATCH v4 5/7] perf diff: Link same basic blocks among different data

[Jin Yao]

The target is to compare the performance difference (cycles
diff) for the same basic blocks in different data files.

The same basic block means same function, same start address
and same end address. This patch finds the same basic blocks
from different data files and link them together and resort
by the cycles diff.

 v3:
 ---
 The block stuffs are maintained by new structure 'block_hist',
 so this patch is update accordingly.

 v2:
 ---
 Since now the basic block hists is changed to per symbol,
 the patch only links the basic block hists for the same
 symbol in different data files.

Signed-off-by: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>
---
 tools/perf/builtin-diff.c | 90 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)

diff --git a/tools/perf/builtin-diff.c b/tools/perf/builtin-diff.c
index c6ec84d..5f5a9a9 100644
--- a/tools/perf/builtin-diff.c
+++ b/tools/perf/builtin-diff.c
@@ -660,6 +660,85 @@ static int process_block_per_sym(struct hist_entry *he)
 	return 0;
 }
 
+static int block_pair_cmp(struct hist_entry *a, struct hist_entry *b)
+{
+	struct block_info *bi_a = a->block_info;
+	struct block_info *bi_b = b->block_info;
+	int cmp;
+
+	if (!bi_a->sym || !bi_b->sym)
+		return -1;
+
+	if (bi_a->sym->name && bi_b->sym->name) {
+		cmp = strcmp(bi_a->sym->name, bi_b->sym->name);
+		if ((!cmp) && (bi_a->start == bi_b->start) &&
+		    (bi_a->end == bi_b->end)) {
+			return 0;
+		}
+	}
+
+	return -1;
+}
+
+static struct hist_entry *get_block_pair(struct hist_entry *he,
+					 struct hists *hists_pair)
+{
+	struct rb_root_cached *root = hists_pair->entries_in;
+	struct rb_node *next = rb_first_cached(root);
+	int cmp;
+
+	while (next != NULL) {
+		struct hist_entry *he_pair = rb_entry(next, struct hist_entry,
+						      rb_node_in);
+
+		next = rb_next(&he_pair->rb_node_in);
+
+		cmp = block_pair_cmp(he_pair, he);
+		if (!cmp)
+			return he_pair;
+	}
+
+	return NULL;
+}
+
+static void compute_cycles_diff(struct hist_entry *he,
+				struct hist_entry *pair)
+{
+	pair->diff.computed = true;
+	if (pair->block_info->num && he->block_info->num) {
+		pair->diff.cycles =
+			pair->block_info->cycles_aggr / pair->block_info->num_aggr -
+			he->block_info->cycles_aggr / he->block_info->num_aggr;
+	}
+}
+
+static void block_hists_match(struct hists *hists_base,
+			      struct hists *hists_pair)
+{
+	struct rb_root_cached *root = hists_base->entries_in;
+	struct rb_node *next = rb_first_cached(root);
+
+	while (next != NULL) {
+		struct hist_entry *he = rb_entry(next, struct hist_entry,
+						 rb_node_in);
+		struct hist_entry *pair = get_block_pair(he, hists_pair);
+
+		next = rb_next(&he->rb_node_in);
+
+		if (pair) {
+			hist_entry__add_pair(pair, he);
+			compute_cycles_diff(he, pair);
+		}
+	}
+}
+
+static int filter_cb(struct hist_entry *he, void *arg __maybe_unused)
+{
+	/* Skip the calculation of column length in output_resort */
+	he->filtered = true;
+	return 0;
+}
+
 static void hists__precompute(struct hists *hists)
 {
 	struct rb_root_cached *root;
@@ -672,6 +751,7 @@ static void hists__precompute(struct hists *hists)
 
 	next = rb_first_cached(root);
 	while (next != NULL) {
+		struct block_hist *bh, *pair_bh;
 		struct hist_entry *he, *pair;
 		struct data__file *d;
 		int i;
@@ -700,6 +780,16 @@ static void hists__precompute(struct hists *hists)
 				break;
 			case COMPUTE_CYCLES:
 				process_block_per_sym(pair);
+				bh = container_of(he, struct block_hist, he);
+				pair_bh = container_of(pair, struct block_hist,
+						       he);
+
+				if (bh->valid && pair_bh->valid) {
+					block_hists_match(&bh->block_hists,
+							  &pair_bh->block_hists);
+					hists__output_resort_cb(&pair_bh->block_hists,
+								NULL, filter_cb);
+				}
 				break;
 			default:
 				BUG_ON(1);
-- 
2.7.4