  Field programmable gate arrays (FPGAs) provide designers with the ability to
quickly create hardware circuits. Increases in FPGA configurable logic capacity
and decreasing FPGA costs have enabled designers to more readily incorporate
FPGAs in their designs. FPGA vendors have begun providing configurable soft
processor cores that can be synthesized onto their FPGA products. While FPGAs
with soft processor cores provide designers with increased flexibility, such
processors typically have degraded performance and energy consumption compared
to hard-core processors. Previously, we proposed warp processing, a technique
capable of optimizing a software application by dynamically and transparently
re-implementing critical software kernels as custom circuits in on-chip
configurable logic. In this paper, we study the potential of a MicroBlaze
soft-core based warp processing system to eliminate the performance and energy
overhead of a soft-core processor compared to a hard-core processor. We
demonstrate that the soft-core based warp processor achieves average speedups
of 5.8 and energy reductions of 57% compared to the soft core alone. Our data
shows that a soft-core based warp processor yields performance and energy
consumption competitive with existing hard-core processors, thus expanding the
usefulness of soft processor cores on FPGAs to a broader range of applications.
