Adder code design

You have read in your source HDL followed by compile. An add function in the source HDL code mapped to an adder from the Synopsys Design Ware library. The current implementation is a ripple adder (rpl), but you require a carry-lookahead adder (cla) to be inferred. Does one have to start with reading in the source HDL and specifying constraints to chiange the implementation to a cla adder. 

---