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Subject: Re: [boost] [endian] Floating point reversal return by value concerns
From: John Maddock (jz.maddock_at_[hidden])
Date: 2015-03-18 13:48:54

>> ah wait.... Beman are you returning by
>> value a non-native representation?
> Yes.
>> If so I imagine that may be an issue as
>> the value gets moved to and from a register: some bit values are not
>> permitted I believe - it's anybodies guess what the hardware would do to
>> those?
> Ouch!

On reflection there's another more serious concern: depending on the FPU
flags set, NaN's, whether signalling or otherwise, may raise a hardware
exception when loaded to a register. The end result is your program
aborts (unless you have some special handling in effect). My "favorite"
example, was Borland's compiler/runtime, which set up the flags so that
even calling numeric_limits<>::quiet_NaN() would abort your program :(


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