Re: Re: Re: NaN packing for TValue

[Yura Sokolov <funny.falcon@...>]

-10.01.-28163 22:59, Tony Finch wrote:
> On Fri, 25 Feb 2011, Peter Cawley wrote:
> > 2011/2/24 Yura Sokolov<funny.falcon@gmail.com>:
> > > So that there is 3bits for tagging.
> > >
> > > Currently Lua uses 13 different tag values, so that it would be tricky to
> > > pack them into three bits :)
> > If you're willing to pay the price of an extra indirection, you might
> > be able to get away with using a single tag value for all GC types, as
> > the GC header stores the tag value.
> Or steal another three bits from the bottom of the pointer...
>
> Tony.
I thought about both.
Both approaches means extra branching on extracting tag and saving it, I 
think.

Another possible solution could be utilization of fact that higher 
addresses reserved for operating system's core.
So that, userland addresses are all falling in a 47 bit values.

Can anybody confirm or refute this sentence?


Sokolov Yura aka funny_falcon.