Basically what is going on here is that the system is recompiled to pass floating point numbers in the ARM VFP registers, rather than the integer registers. Th

Basically what is going on here is that the system is recompiled to pass floating point numbers in the ARM VFP registers, rather than the integer registers. This both reduces register pressure and means you don't have to marshal stuff to and from the integer registers at function boundaries. The reason this hasn't happened before is because VFP is an optional part of the instruction set, and you can still configure compliant ARM cores without a FPU. I'm not sure if their port uses NEON (the ARM SSE equivalent) at all.