Add comment about previous perf-related commit
@@ -205,6 +205,9 @@ pri func decoder.decode_blocks?(dst base.io_writer, src base.io_reader) {
// TODO: "if status.is_error()" is probably more idiomatic, but for
// some mysterious, idiosyncratic reason, performs noticably worse
// for gcc (but not for clang).
+ //
+ // See git commit 3bf9573 "Work around strange status.is_error
+ // performance".
if not status.is_ok() {
return status
}
