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

Michael Gottesman mgottesman at apple.com
Tue Jun 18 18:47:43 PDT 2013


It seems like there is a consensus that this is a good change. Any nay sayers?

Michael

On Jun 18, 2013, at 5:07 PM, Eric Christopher <echristo at gmail.com> wrote:

> LGTM (and you've already gotten other positive feedback as well).
> 
> -eric
> 
> On Tue, Jun 18, 2013 at 3:45 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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