Re: virtual machine [was Re: [ANNOUNCE] Lua 5.0 (alpha) now available]

[Roberto Ierusalimschy <roberto@...>]

> Are there any docs on this?

Only `lopcodes.h'.

> How many registers are there and how many are the same after a return
> from a function call?

There are up to 250 registers for each function. Actually they are
allocated on the stack. We call them "registers" because opcodes can
access them directly.

> Is there a return register?
> How does it deal with lua's multiple return values?

The parameters go on the "upper" registers, and also returns on the
upper registers. (That is, during function calls there is a "dual" view
between registers and stack.)


> Just curious - do you think this reflects the fact that the hw lua 
> typically runs on is register based?

No. There is no relationship between Lua registers (actually some space
pre-allocated in the Lua stack) and the CPU registers (something not
visible from C code).

-- Roberto