[PATCH V6 17/18] tools/perf: Update data_type_cmp and sort__typeoff_sort function to include var_name in comparison

[Athira Rajeev]

Currently data_type_cmp() only compares size and type name.
But in cases where the type name of two data type entries
is same, but var_name is different, the comparison can't distinguish
two different types.

Consider there is a "long unsigned int" with var_name as "X" and there
is global variable "long unsigned int". Currently since
data_type_cmp uses only type_name for comparison ( "long unsigned int"),
it won't distinguish these as separate entries. Update the
functions "data_type_cmp" as well as "sort__typeoff_sort" to
compare variable names after type name if it exists.

Also updated "hist_entry__typeoff_snprintf" to print var_name if
it is set. With the changes,

     11.42%  long unsigned int  long unsigned int +0 (current_stack_pointer)
     4.68%  struct paca_struct  struct paca_struct +2312 (__current)
     4.57%  struct paca_struct  struct paca_struct +2354 (irq_soft_mask)
     2.69%  struct paca_struct  struct paca_struct +2808 (canary)
     2.68%  struct paca_struct  struct paca_struct +8 (paca_index)
     2.24%  struct paca_struct  struct paca_struct +48 (data_offset)
     1.43%  long unsigned int  long unsigned int +0 (no field)

Signed-off-by: Athira Rajeev <atrajeev@xxxxxxxxxxxxxxxxxx>
---
 tools/perf/util/annotate-data.c | 24 ++++++++++++++++++++++--
 tools/perf/util/sort.c          | 23 +++++++++++++++++++++--
 2 files changed, 43 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/annotate-data.c b/tools/perf/util/annotate-data.c
index 8d05f3dbddf6..759c6a22e719 100644
--- a/tools/perf/util/annotate-data.c
+++ b/tools/perf/util/annotate-data.c
@@ -167,7 +167,7 @@ static void exit_type_state(struct type_state *state)
 }
 
 /*
- * Compare type name and size to maintain them in a tree.
+ * Compare type name, var_name  and size to maintain them in a tree.
  * I'm not sure if DWARF would have information of a single type in many
  * different places (compilation units).  If not, it could compare the
  * offset of the type entry in the .debug_info section.
@@ -176,12 +176,32 @@ static int data_type_cmp(const void *_key, const struct rb_node *node)
 {
 	const struct annotated_data_type *key = _key;
 	struct annotated_data_type *type;
+	int64_t ret = 0;
 
 	type = rb_entry(node, struct annotated_data_type, node);
 
 	if (key->self.size != type->self.size)
 		return key->self.size - type->self.size;
-	return strcmp(key->self.type_name, type->self.type_name);
+
+	ret = strcmp(key->self.type_name, type->self.type_name);
+	if (ret) {
+		return ret;
+	}
+
+	/*
+	 * Compare var_name if it exists for key and type.
+	 * If both nodes doesn't have var_name, but one of
+	 * them has, return non-zero. This is to indicate nodes
+	 * are not the same if one has var_name, but other doesn't.
+	 */
+	if (key->self.var_name && type->self.var_name) {
+		ret = strcmp(key->self.var_name, type->self.var_name);
+		if (ret)
+			return ret;
+	} else if (key->self.var_name || type->self.var_name)
+		return 1;
+
+	return ret;
 }
 
 static bool data_type_less(struct rb_node *node_a, const struct rb_node *node_b)
diff --git a/tools/perf/util/sort.c b/tools/perf/util/sort.c
index cd39ea972193..c6d885060ee7 100644
--- a/tools/perf/util/sort.c
+++ b/tools/perf/util/sort.c
@@ -2267,9 +2267,25 @@ sort__typeoff_sort(struct hist_entry *left, struct hist_entry *right)
 		right_type = right->mem_type;
 	}
 
+	/*
+	 * Compare type_name first. Next, ompare var_name if it exists
+	 * for left and right hist_entry. If both entries doesn't have
+	 * var_name, but one of them has, return non-zero. This is to
+	 * indicate entries are not the same if one has var_name, but the
+	 * other doesn't.
+	 * If type_name and var_name is same, use mem_type_off field.
+	 */
 	ret = strcmp(left_type->self.type_name, right_type->self.type_name);
 	if (ret)
 		return ret;
+
+	if (left_type->self.var_name && right_type->self.var_name) {
+		ret = strcmp(left_type->self.var_name, right_type->self.var_name);
+		if (ret)
+			return ret;
+	} else if (right_type->self.var_name || left_type->self.var_name)
+		return 1;
+
 	return left->mem_type_off - right->mem_type_off;
 }
 
@@ -2305,9 +2321,12 @@ static int hist_entry__typeoff_snprintf(struct hist_entry *he, char *bf,
 	char buf[4096];
 
 	buf[0] = '\0';
-	if (list_empty(&he_type->self.children))
+	if (list_empty(&he_type->self.children)) {
 		snprintf(buf, sizeof(buf), "no field");
-	else
+		if (he_type->self.var_name)
+			strcpy(buf, he_type->self.var_name);
+
+	} else
 		fill_member_name(buf, sizeof(buf), &he_type->self,
 				 he->mem_type_off, true);
 	buf[4095] = '\0';
-- 
2.43.0