1. A method for failure analysis for an instruction set implementation in a computer system, the method comprising: running a test-case in a simulation model and a reference model; in response to a failure in at least one of the simulation model and the reference model, determining if the test case failed in the simulation model; in response to a failure in the simulation model, determining if the test case failed in the reference model; and in response to the test case passing in the simulation model, determining that the reference model is a source of failure for the instruction set.