A pipelined execution unit uses the bubbles that occur during execution to selectively repeat operations performed in one or more stages of a multistage execution pipeline to verify the results of such operations during otherwise unused execution cycles for the execution pipeline. Whenever a bubble follows a particular instruction within an execution pipeline, the result of an operation that is performed for that instruction by a particular stage of the execution pipeline may be stored, and the operation may be repeated by the stage in a subsequent execution cycle in which no productive operation would otherwise be performed due to the presence of the bubble. The results of the operations may then be compared and used to either verify the original result or identify a potential error in the execution of the instruction.