1. A method of operation of a multi-slice processor, the multi-slice processor including a plurality of execution slices, wherein each execution slice comprises a history buffer, wherein the history buffer includes a plurality of entries and at least one of the entries includes transactional memory state data corresponding to a transactional memory instruction updating a transaction memory state, the method comprising: propagating a flush signal to each of the plurality of entries of the history buffer, wherein the flush signal comprises a flush instruction tag and each entry of the history buffer comprises logic configured to compare a flush instruction tag to one or more other instruction tags stored in the entry, wherein the flush instruction tag comprises an identifier of an instruction to flush; responsive to the flush signal, generating, from an entry of the history buffer, the transactional memory state data, including: for each of the plurality of entries, and in response to the flush signal, determining whether to generate the transactional memory state data in dependence upon an evictor tag and upon an instruction tag, wherein the evictor tag corresponds to an instruction tag of an instruction causing an update to the transaction memory state; and restoring to a transactional memory state in dependence upon the transactional memory state data.