Re: [boost] [endian] Floating point reversal return by value concerns

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 :(

John.