weird optimization in sin+cos, x86 backend

Konstantin Vladimirov konstantin.vladimirov@gmail.com
Fri Feb 3 18:13:00 GMT 2012


Hi,

I agree, that this case have no practical value. It was autogenerated
between other thousands of tests and showed really strange results, so
I decided to ask. I thought, this value fits double precision range
and, according to C standard, all double-precision arithmetics must be
avaliable for it.

Thanks everybody for explanation, I will constrain trig function
arguments, according to "x is separable with x+pi/4" rule. It seems,
everything works inside this range.

---
With best regards, Konstantin

On Fri, Feb 3, 2012 at 7:13 PM, Robert Dewar <dewar@adacore.com> wrote:
> On 2/3/2012 10:01 AM, Michael Matz wrote:
>
>> No normal math library supports such an extreme range, even basic
>> identities (like cos^2+sin^2=1) aren't retained with such inputs.
>
>
> I agree: the program is complete nonsense. It would be useful to know
> what the intent was.
>>
>>
>>
>> Ciao,
>> Michael.
>
>



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