Re: newproxy, bug

[Mark Hamburg <mark@...>]

On Jan 11, 2011, at 4:38 AM, Mike Pall wrote:

> Geoff Leyland wrote:
>> It took a while to work out how to stop LuaJIT optimising out
>> the loops altogether - it might still be optimising more than I
>> want.  I'm sure this is not a good test, but for what it's
>> worth:
> 
> Well, LuaJIT _is_ optimizing away all of the proxy overhead, of
> course. :-)
> 
> But I was talking about Lua, not LuaJIT. And about hash keys, e.g.
> strings. A pattern like this will show the worst case:
> 
>  p.x = 1; p.x = 1; p.y = 1; p.z = 1; p.z = 1; p.z = 1; p.y = 1;
> 
> This is 40%-50% slower with table-based proxies vs. userdata
> proxies. The actual cost is much higher -- it's shadowed by the
> interpreter overhead.

Interesting. Does this suggest that if newproxy were to go away, there should be a short-circuit path for setting values in empty tables -- i.e., tables essentially being used as proxies?

Mark