the status of poisoned may indicate that the register may have a data dependency that is not currently satisfied in other embodiments the data valid bit may be set by other data validity metrics the data valid bit may be used to control data bypassing during the non speculative e g re execution mode in one embodiment the nat bit may indicate the presence of a deferred exception the instructions that have produced valid target data placed into the adt 250 may also be re executed during the re execution the target data generated during the re execution may be compared with the target data stored previously in the adt 250 in those cases where the target data in the adt 250 does not match the results of current re execution any instructions that consumed the target data from the adt 250 may be trapped and re executed in other words the advance target data is not guaranteed to be correct but the correctness is verified during the re execution process referring now to fig3 a and 3b code fragments in regular execution and re execution are shown according to one embodiment of the present disclosure instructions are shown with target registers preceding.