Ultra-low-power adder stage design for exascale floating point units

Currently, the most powerful supercomputers can provide tens of petaflops. Future many-core systems are estimated to provide an exaflop. However, the power budget limitation makes these machines still unfeasible and unaffordable. Floating Point Units (FPUs) are critical from both the power consumption and performance points of view of today's microprocessors and supercomputers. Literature offers very different designs. Some of them are focused on increasing performance no matter the penalty, and others on decreasing power at the expense of lower performance. In this article, we propose a novel approach for reducing the power of the FPU without degrading the rest of parameters. Concretely, this power reduction is also accompanied by an area reduction and a performance improvement. Hence, an overall energy gain will be produced. According to our experiments, our proposed unit consumes 17.5%, 23% and 16.5% less energy for single, double and quadruple precision, with an additional 15%, 21.5% and 14.5% delay reduction, respectively. Furthermore, area is also diminished by 4%, 4.5 and 5%