Intelligent mobile information devices require low-power and high-performance processors. In order to reduce energy consumption with maintaining computing performance, the authors proposed to utilize information regarding instruction criticality. Every functional unit in their processor has different latency and energy consumption. Only critical instructions are executed in power-hungry units, and the total energy consumption can be reduced. While they have studied several techniques to identify critical instructions for years, they have not found any technique that achieves both simplicity and high accuracy to identify. In this paper, they propose to exploit uncriticality rather than criticality.