[Vm-dev] FloatMathPlugin crashes the VM if compiled with gcc optimization

stephane ducasse stephane.ducasse at gmail.com
Wed Dec 29 10:10:06 UTC 2010

>>> Oh, and please, can you shed some light on the history, why for
>>> floating-point
>>> math in Squeak, VM using non-standard math lib, which comes with any C
>>> compiler, but instead, a  portions of separate 3rd party library?
>> You would be surprised to find out just how much the results of the C
>> compiler libraries differ when it comes to edge cases. I've run the
>> experiment in the past:
>> Using Python 2.4:
>>>>> import math
>>>>> math.cos(1.0e32)
>> WinXP:    -0.39929634612021897
>> LinuxX86: -0.49093671143542561

Thanks for the info.
Scary. It is amazing how we can forget this ugly things in the comfort of our images.
I remember a talk of dave thomas (VA) and he said that they burned tons of smart people on such issues.
>> In short, the results *dramatically* vary depending on processor family,
>> processor version, C compiler libraries, and so on. None of the libraries
>> produce cross-platform bit-identical results. fdlibm does.
> i see. And it looks like this library used by java vm. It is very
> strange that Oracle having no interest in maintaining it anymore:
> http://mailman.oakapple.net/pipermail/numeric-interest/2010-September/002054.html

Strange. May be not for free. 


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