Re: [PATCH] Add support for floating point endpoints to frange.

[Jeff Law <jeffreyalaw@gmail.com>]

On 8/29/2022 8:42 AM, Toon Moene wrote:
> On 8/29/22 16:36, Aldy Hernandez wrote:
>
>> On Mon, Aug 29, 2022 at 4:30 PM Toon Moene <toon@moene.org> wrote:
>>>
>>> On 8/29/22 16:15, Aldy Hernandez wrote:
>>>
>>>> But even with -ffinite-math-only, is there any benefit to propagating
>>>> a known NAN?  For example:
>>>
>>> The original intent (in 2002) for the option -ffinite-math-only was for
>>> the optimizers to ignore all the various exceptions to common
>>> optimizations because they might not work correctly when presented with
>>> a NaN or an Inf.
>>>
>>> I do not know what the effect for floating point range information 
>>> would
>>> be - offhand.
>>>
>>> But in the *spirit* of this option would be to ignore that the range
>>> [5.0, 5.0] would "also" contain NaN, for instance.
>>
>> Hmm, this is somewhat similar to what Jakub suggested.  Perhaps we
>> could categorically set !NAN for !HONOR_NANS at frange construction
>> time?
>>
>> For reference:
>> bool
>> HONOR_NANS (machine_mode m)
>> {
>>    return MODE_HAS_NANS (m) && !flag_finite_math_only;
>> }
>>
>> Thanks.
>> Aldy
>>
>
> Yep, I think that would do it.
Agreed.
Jeff