perldelta for save source lines as PVIV instead of as PVMG

Author: tonycoz

pod/perldelta.pod

@@ -369,6 +369,14 @@ manager will later use a regex to expand these into links.
 In some cases an C<eval> would not add integer parts to the source
 lines saved by the debugger.  [GH #23151]
 
+=item *
+
+Save debugger lines as C<PVIV> SVs rather than as C<PVMG> SVs as they
+don't need magic, aren't blessed and don't need to store a floating
+point part.  This should save 24 bytes per stored line for 64-bit
+systems, more for C<-Duselongdouble> or C<-Dusequadmath> builds.
+Discussed in [GH #23171].
+
 =back
 
 =head1 Known Problems