Song: embed the Tag object statically into class Song

Reduces overhead because we need to manage only one memory allocation.
According to valgrind/massif, we save 7%.

1 files changed, 6 insertions, 14 deletions

diff --git a/src/SongSort.cxx b/src/SongSort.cxx
index 6eac97f10..dcea033b6 100644
--- a/src/SongSort.cxx
+++ b/src/SongSort.cxx
@@ -30,14 +30,6 @@ extern "C" {
 
 #include <stdlib.h>
 
-static const char *
-tag_get_value_checked(const Tag *tag, TagType type)
-{
-	return tag != nullptr
-		? tag->GetValue(type)
-		: nullptr;
-}
-
 static int
 compare_utf8_string(const char *a, const char *b)
 {
@@ -55,11 +47,11 @@ compare_utf8_string(const char *a, const char *b)
  * nullptr.
  */
 static int
-compare_string_tag_item(const Tag *a, const Tag *b,
+compare_string_tag_item(const Tag &a, const Tag &b,
 			TagType type)
 {
-	return compare_utf8_string(tag_get_value_checked(a, type),
-				   tag_get_value_checked(b, type));
+	return compare_utf8_string(a.GetValue(type),
+				   b.GetValue(type));
 }
 
 /**
@@ -82,10 +74,10 @@ compare_number_string(const char *a, const char *b)
 }
 
 static int
-compare_tag_item(const Tag *a, const Tag *b, TagType type)
+compare_tag_item(const Tag &a, const Tag &b, TagType type)
 {
-	return compare_number_string(tag_get_value_checked(a, type),
-				     tag_get_value_checked(b, type));
+	return compare_number_string(a.GetValue(type),
+				     b.GetValue(type));
 }
 
 /* Only used for sorting/searchin a songvec, not general purpose compares */