More than 30 years ago Miles Davis recorded this music in the company of such other giants as Milt Jackson, Thelonious Monk, Kenny Clarke, Percy Heath, Sonny Rollins, and Horace Silver. Today the music they made is regarded as classic. Bags' Groove, in two versions, is a perfect illustration of the improvisatory process, and the various delights that can develop from take to take; the date with Rollins reveals his development toward major status. It is hard to believe that having heard these 1954 recordings, the critics could have called Davis' triumph at the Newport Jazz Festival in 1955 a ''comeback.'' With Milt Jackson, Thelonious Monk, Percy Heath, Kenny Clarke, Sonny Rollins, Horace Silver.