What is the loop prevention mechanism in LDP?

LDP is a protocol which is used to exchange labels.LDP works totally on the basis of interior gateway routing protocols.LDP uses these same routing protocols to populate its routing table, the information that is used to form the LSPs within the network is the same as with a standard IP-routed network. For this reason, LDP relies on the routing protocols to make sure the information contained in the routing table of the LSR is loop-free, in exactly the same way as a standard IP-routed network.

So if igp is loop free, ldp will be.