std::pow implementation

[Robert Dewar]

> | If the original C specification had said that "register" meant "register" 
> | unconditionally, then the situation wouldn't have been any different -- 
> | the compiler would have to obey the user, even if the compiler could do 
> | better.

That would be very hard for a standard to say, given that standards describe
as-if semantics and are not in the business of telling you what sequences
of instructions may or may not be used to implement these semantics.