= (CmmProc info lbl params [], emptyUFM)
build_mapping (CmmProc info lbl params (head:blocks))
= (CmmProc info lbl params (head:others), mapping)
= (CmmProc info lbl params [], emptyUFM)
build_mapping (CmmProc info lbl params (head:blocks))
= (CmmProc info lbl params (head:others), mapping)