02-Jun-2013 22:25, Alex Rønne Petersen пишет:
On 02-06-2013 19:58, Dmitry Olshansky wrote:
The problem here is assuming the interpreter state can be global. Once
you make it non-global (and thus have to pass it in the goto start(...)
call) you get all the overhead of a regular function call.
One pointer to a struct MyInterpreterState. Think of it as 'this'
pointer :)
That's one load and store for every single step in the interpreter.
Sounds harmless, but every cycle matters when every goto start(...)
amounts to a single instruction in the program you're running.
Anyhow cramming the whole interpreter in one huge function too has
downsides (and hopelessly inefficent register allocation is one).
I'd frankly be surprised if that was the case. But without any
investigation, it's just word against word.
See my reply to Walter. Again I personally have not done any
measurements but what that post by LuaJIt author makes a lot of sense to me.
And you still access most locals via stack pointer. And then there got
to be something beyond locals - 'context', that is still passed from one
bytecode execution to another.
It depends on what you mean by context. Can you elaborate?
Context is what a virtual thread represents in the global world. Any
outside hooks into it like argv in C's main are there, function tables
(=extensions) and whatnot.
--
Dmitry Olshansky
