Re: PCODE Interpereters 101

Scott Amspoker wrote:
> I always felt that P-code's static links weren't a very efficient
> way to handle the problem. The PUSH and POP instructions
> (LOAD/SAVE, whatever) contained the lexical level of the variable as
> well as its offset within its stack frame. For "global" variables
> and variables in the current frame, it was reasonably efficient.
> However, for variables somewhere in between, the engine had to
> follow the static links the necessary number of steps to locate the
> desired frame.




Hi,


You're quite right about this efficiency talk, but if you use a thread
coded intermediate version of the p-code you can gain a lot of speed -
eg. a factor 100 or so. But the overhead is still there... I'm
running a thread coded version of a Pascal compiler and the
performance is pretty good :)


Torben
[Before anyone asks, threaded code is interpreted code where the tokens
are the addresses of the interpretive routines, which makes the interpreter
dispatch about two instructions. -John]

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