Porposal: Floating-Point Options

[Russell Shaw]

Robert Dewar wrote:
> Scott Robert Ladd wrote:
> 
>> To support different expectations, I suggest defining the following
>> floating-point options for GCC. This is a conceptual overview; once
>> there's a consensus the categories, I'll propose something more formal.
>>
>> -ffp-correct
>>
>> This option focuses code generation on mathematical correctness,
>> portability, and consistency. No 80-bit long doubles, no fsin/fcos,
>> making certain that comparison operators work within reason. Note that
>> this option can only go so far in ensuring portability, given that not
>> every system supports IEEE 754 floats.
> 
> It is wrong, confusing, and provocative to call this correct, since
> there is no justification for using this term, and it implies that
> the current behavior of gcc is incorrect, which is not the case.
> Choosing a good name for this is in fact not so easy

...

The original bug was about testing the equality of doubles. I think that's
just plain mathematically bad. Error bands should be used to test for
"equality", using a band that is in accordance with the minimum precision
specified in the compiler documentation.