They are level shifters. Do grep in the lib dir to see which file has most cell number.
grep cell\( *.lib
or
grep "cell (" *.lib
I have done the grep and find the file with most cell number.
[xyin1@cse-ws-12 db_nldm]$ grep -c "cell (" *.lib
saed32rvt_dlvl_ff0p85v125c_i0p85v.lib:24
saed32rvt_dlvl_ff0p85v125c_i1p16v.lib:24
saed32rvt_dlvl_ff0p85v25c_i0p85v.lib:24
saed32rvt_dlvl_ff0p85v25c_i1p16v.lib:24
saed32rvt_dlvl_ff0p85vn40c_i0p85v.lib:24
saed32rvt_dlvl_ff0p85vn40c_i1p16v.lib:24
saed32rvt_dlvl_ff0p95v125c_i0p95v.lib:24
saed32rvt_dlvl_ff0p95v125c_i1p16v.lib:24
saed32rvt_dlvl_ff0p95v25c_i0p95v.lib:24
saed32rvt_dlvl_ff0p95v25c_i1p16v.lib:24
saed32rvt_dlvl_ff0p95vn40c_i0p95v.lib:24
saed32rvt_dlvl_ff0p95vn40c_i1p16v.lib:24
saed32rvt_dlvl_ff1p16v125c_i1p16v.lib:24
saed32rvt_dlvl_ff1p16v25c_i1p16v.lib:24
saed32rvt_dlvl_ff1p16vn40c_i1p16v.lib:24
saed32rvt_dlvl_ss0p75v125c_i0p75v.lib:24
saed32rvt_dlvl_ss0p75v125c_i0p95v.lib:24
saed32rvt_dlvl_ss0p75v25c_i0p75v.lib:24
saed32rvt_dlvl_ss0p75v25c_i0p95v.lib:24
saed32rvt_dlvl_ss0p75vn40c_i0p75v.lib:24
saed32rvt_dlvl_ss0p75vn40c_i0p95v.lib:24
saed32rvt_dlvl_ss0p7v125c_i0p7v.lib:24
saed32rvt_dlvl_ss0p7v125c_i0p95v.lib:24
saed32rvt_dlvl_ss0p7v25c_i0p7v.lib:24
saed32rvt_dlvl_ss0p7v25c_i0p95v.lib:24
saed32rvt_dlvl_ss0p7vn40c_i0p7v.lib:24
saed32rvt_dlvl_ss0p7vn40c_i0p95v.lib:24
saed32rvt_dlvl_ss0p95v125c_i0p95v.lib:24
saed32rvt_dlvl_ss0p95v25c_i0p95v.lib:24
saed32rvt_dlvl_ss0p95vn40c_i0p95v.lib:24
saed32rvt_dlvl_tt0p78v125c_i0p78v.lib:24
saed32rvt_dlvl_tt0p78v125c_i1p05v.lib:24
saed32rvt_dlvl_tt0p78v25c_i0p78v.lib:24
saed32rvt_dlvl_tt0p78v25c_i1p05v.lib:24
saed32rvt_dlvl_tt0p78vn40c_i0p78v.lib:24
saed32rvt_dlvl_tt0p78vn40c_i1p05v.lib:24
saed32rvt_dlvl_tt0p85v125c_i0p85v.lib:24
saed32rvt_dlvl_tt0p85v125c_i1p05v.lib:24
saed32rvt_dlvl_tt0p85v25c_i0p85v.lib:24
saed32rvt_dlvl_tt0p85v25c_i1p05v.lib:24
saed32rvt_dlvl_tt0p85vn40c_i0p85v.lib:24
saed32rvt_dlvl_tt0p85vn40c_i1p05v.lib:24
saed32rvt_dlvl_tt1p05v125c_i1p05v.lib:24
saed32rvt_dlvl_tt1p05v25c_i1p05v.lib:24
saed32rvt_dlvl_tt1p05vn40c_i1p05v.lib:24
saed32rvt_ff0p85v125c.lib:350
saed32rvt_ff0p85v25c.lib:350
saed32rvt_ff0p85vn40c.lib:350
saed32rvt_ff0p95v125c.lib:350
saed32rvt_ff0p95v25c.lib:350
saed32rvt_ff0p95vn40c.lib:350
saed32rvt_ff1p16v125c.lib:350
saed32rvt_ff1p16v25c.lib:350
saed32rvt_ff1p16vn40c.lib:350
saed32rvt_pg_ff0p85v125c.lib:20
saed32rvt_pg_ff0p85v25c.lib:20
saed32rvt_pg_ff0p85vn40c.lib:20
saed32rvt_pg_ff0p95v125c.lib:20
saed32rvt_pg_ff0p95v25c.lib:20
saed32rvt_pg_ff0p95vn40c.lib:20
saed32rvt_pg_ff1p16v125c.lib:20
saed32rvt_pg_ff1p16v25c.lib:20
saed32rvt_pg_ff1p16vn40c.lib:20
saed32rvt_pg_ss0p75v125c.lib:20
saed32rvt_pg_ss0p75v25c.lib:20
saed32rvt_pg_ss0p75vn40c.lib:20
saed32rvt_pg_ss0p7v125c.lib:20
saed32rvt_pg_ss0p7v25c.lib:20
saed32rvt_pg_ss0p7vn40c.lib:20
saed32rvt_pg_ss0p95v125c.lib:20
saed32rvt_pg_ss0p95v25c.lib:20
saed32rvt_pg_ss0p95vn40c.lib:20
saed32rvt_pg_tt0p78v125c.lib:20
saed32rvt_pg_tt0p78v25c.lib:20
saed32rvt_pg_tt0p78vn40c.lib:20
saed32rvt_pg_tt0p85v125c.lib:20
saed32rvt_pg_tt0p85v25c.lib:20
saed32rvt_pg_tt0p85vn40c.lib:20
saed32rvt_pg_tt1p05v125c.lib:20
saed32rvt_pg_tt1p05v25c.lib:20
saed32rvt_pg_tt1p05vn40c.lib:20
saed32rvt_ss0p75v125c.lib:350
saed32rvt_ss0p75v25c.lib:350
saed32rvt_ss0p75vn40c.lib:350
saed32rvt_ss0p7v125c.lib:350
saed32rvt_ss0p7v25c.lib:350
saed32rvt_ss0p7vn40c.lib:350
saed32rvt_ss0p95v125c.lib:350
saed32rvt_ss0p95v25c.lib:350
saed32rvt_ss0p95vn40c.lib:350
saed32rvt_tt0p78v125c.lib:350
saed32rvt_tt0p78v25c.lib:350
saed32rvt_tt0p78vn40c.lib:350
saed32rvt_tt0p85v125c.lib:350
saed32rvt_tt0p85v25c.lib:350
saed32rvt_tt0p85vn40c.lib:350
saed32rvt_tt1p05v125c.lib:350
saed32rvt_tt1p05v25c.lib:350
saed32rvt_tt1p05vn40c.lib:350
saed32rvt_ulvl_ff0p85v125c_i0p85v.lib:12
saed32rvt_ulvl_ff0p85v25c_i0p85v.lib:12
saed32rvt_ulvl_ff0p85vn40c_i0p85v.lib:12
saed32rvt_ulvl_ff0p95v125c_i0p95v.lib:12
saed32rvt_ulvl_ff0p95v25c_i0p95v.lib:12
saed32rvt_ulvl_ff0p95vn40c_i0p95v.lib:12
saed32rvt_ulvl_ff1p16v125c_i0p85v.lib:12
saed32rvt_ulvl_ff1p16v125c_i0p95v.lib:12
saed32rvt_ulvl_ff1p16v125c_i1p16v.lib:12
saed32rvt_ulvl_ff1p16v25c_i0p85v.lib:12
saed32rvt_ulvl_ff1p16v25c_i0p95v.lib:12
saed32rvt_ulvl_ff1p16v25c_i1p16v.lib:12
saed32rvt_ulvl_ff1p16vn40c_i0p85v.lib:12
saed32rvt_ulvl_ff1p16vn40c_i0p95v.lib:12
saed32rvt_ulvl_ff1p16vn40c_i1p16v.lib:12
saed32rvt_ulvl_ss0p75v125c_i0p75v.lib:12
saed32rvt_ulvl_ss0p75v25c_i0p75v.lib:12
saed32rvt_ulvl_ss0p75vn40c_i0p75v.lib:12
saed32rvt_ulvl_ss0p7v125c_i0p7v.lib:12
saed32rvt_ulvl_ss0p7v25c_i0p7v.lib:12
saed32rvt_ulvl_ss0p7vn40c_i0p7v.lib:12
saed32rvt_ulvl_ss0p95v125c_i0p75v.lib:12
saed32rvt_ulvl_ss0p95v125c_i0p7v.lib:12
saed32rvt_ulvl_ss0p95v125c_i0p95v.lib:12
saed32rvt_ulvl_ss0p95v25c_i0p75v.lib:12
saed32rvt_ulvl_ss0p95v25c_i0p7v.lib:12
saed32rvt_ulvl_ss0p95v25c_i0p95v.lib:12
saed32rvt_ulvl_ss0p95vn40c_i0p75v.lib:12
saed32rvt_ulvl_ss0p95vn40c_i0p7v.lib:12
saed32rvt_ulvl_ss0p95vn40c_i0p95v.lib:12
saed32rvt_ulvl_tt0p78v125c_i0p78v.lib:12
saed32rvt_ulvl_tt0p78v25c_i0p78v.lib:12
saed32rvt_ulvl_tt0p78vn40c_i0p78v.lib:12
saed32rvt_ulvl_tt0p85v125c_i0p85v.lib:12
saed32rvt_ulvl_tt0p85v25c_i0p85v.lib:12
saed32rvt_ulvl_tt0p85vn40c_i0p85v.lib:12
saed32rvt_ulvl_tt1p05v125c_i0p78v.lib:12
saed32rvt_ulvl_tt1p05v125c_i0p85v.lib:12
saed32rvt_ulvl_tt1p05v125c_i1p05v.lib:12
saed32rvt_ulvl_tt1p05v25c_i0p78v.lib:12
saed32rvt_ulvl_tt1p05v25c_i0p85v.lib:12
saed32rvt_ulvl_tt1p05v25c_i1p05v.lib:12
saed32rvt_ulvl_tt1p05vn40c_i0p78v.lib:12
saed32rvt_ulvl_tt1p05vn40c_i0p85v.lib:12
saed32rvt_ulvl_tt1p05vn40c_i1p05v.lib:12