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Comments (45)

  • cesaref
    It used to be quite normal to add a low level random signal to inputs when writing DSP code so as to avoid dropping into subnormal territory. Careful analysis of the algorithm would identify any points where this was also necessary (e.g. feedback paths when running delays).Obviously those lucky/unlucky enough to be writing 56k fixed precision code wouldn't have this concern, but other ones instead :)I think flush to zero is probably the preferred strategy these days.
  • khuey
    If you don't _need_ subnormals MXCSR.DAZ/FTZ (which you can get gcc to set via -mdaz-ftz) will let you ignore all of this.
  • pixelpoet
    This has been the case since a zillion years, since the Core 2 Duo days at minimum.
  • juancn
    Apparently it only happens on P-cores, recent E-cores have a fast path for subnormals.
  • gwbas1c
    I'm still trying to understand what a subnormal number is; IE, I'm looking for the TLDR so I know just enough to know if I'm using them and need to learn more.Unfortunately, the Wikipedia article, while probably being accurate, doesn't give a clear and concise answer.IE, is 0.0001 a subnormal? Or is it 0.000000000000000000001?
  • mzs
    Are the results compared across architectures?
  • anon
    undefined
  • rf15
    ...Is this running extra micro code to fix some hardware bug/unreliability? How can this happen? Doesn't look like a normal design decision.
  • MotoriX
    [flagged]
  • QuadrupleA
    [dead]