1. A method for merging stores in an N-entry first-in-first-out (FIFO) store queue in a processor, comprising: executing instructions before a checkpoint is generated, wherein executing instructions before the checkpoint is generated involves performing limited or no merging of stores into existing entries in the store queue; upon detecting a predetermined condition, generating the checkpoint; and executing instructions after the checkpoint is generated, wherein executing instructions after the checkpoint is generated involves freely merging subsequent stores into post-checkpoint entries in the store queue.