[LLVMdev] APFloat renaming isNormal => isFiniteNonZero and isIEEENormal => isNormal

Stephen Canon
Tue, 18 Jun 2013 23:21:32 -0000

I think it’s a splendid idea (but you already knew that).

On Jun 18, 2013, at 6:45 PM, Michael Gottesman <mgottesman at apple.com>
wrote:

> IEEE-754R defines a normal floating point number as:
> 2.1.38 normal number: For a particular format, a finite non-zero
floating-point number with magnitude greater than or equal to a minimum bemin
value, where b is the radix. Normal numbers can use the full precision available
in a format. In this standard, zero is neither normal nor subnormal.
>
> This implies that a denormal is not a normal number.
>
> In contrast, the current implementation of isNormal in APFloat does treat
denormal numbers as normal numbers breaking this definition. This is not just a
predicate that has a name that differs from IEEE-754R (which I am fine with),
but is an actual name collision with IEEE-754R with a different semantic
meaning. This could easily lead to programmer error and thus in my humble
opinion is worth the hassle/trouble of fixing.
>
> Does anyone have any thoughts/suggestions/objections with my renaming
isNormal => isFiniteNonZero (and making all the relevant changes in the
relevant codebases) and isIEEENormal => isNormal?
>
> Awaiting the flames,
> Michael

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