[knc1]

Holy War challenge accepted ::

K4&K5 == -mfpu=vfpv3-d16 -mfloat-abi=softfp (rather than: -mfpu=vfpv3 or -mfpu=neon)

Keep in mind that the neon instruction set treats denormals as zero.
Should not make a difference in typical uses, like finding the pixel bounds of a graphic item.
Will make a difference in fft and inverse fft code (big time).
Would probably not be recommended for building gcc with either - very likely to screw up the optimizer's tree coloring.

Hmm...
I wouldn't trust the neon instruction set for building Lua either (Lua's only (default) internal numeric type is double)

Note: Only messing with the K3 code at the moment here, not (yet) with K4&K5.