Added CodeGen support for 16-bit SW16 and LW16 instructions.
LGTM, with additional comment.
I think it would be good if you add a comment for this if statement, because it behaves differently than the other similar "if (select...)" statements in this file (it returns false when the select function returns true, while the other similar statements return true when the select function returns true). The comment might be (for example):
For all the other cases where "lw" would be selected, don't select "lw16".