--- Dan Sugalski <[EMAIL PROTECTED]> wrote:
> =head1 Stacks
[snip]
> The stacks are at least:
>
> =over 4
>
> =item Temp stack
>
> for squirreling away the contents of individual registers
>
> =item Register stack
>
> For pushing the entire register file at once. There are
> four sets, one
> for each register type.
>
> =item state stack
>
> For the interpreter's internal state
>
> =back
Perl 5-ish save stack for dynamic scoping? (whatever term
replaces 'local')
What is the subroutine calling convention? Caller cleans or
callee cleans?
> =head1 Registers
>
> We have four sets. Each set has 64 members
Do we really need 64 ints and 64 floats? 64 stringish ones
I can understand (sort of) - the RE engine could use them.
Maybe only 32 each of ints and floats? Also, what about the
suggestion to have the various special values
(&PL_sv_undef, &PL_sv_yes, &PL_sv_yes) be registers (so
undef $foo becomes 'st sp_reg0, $foo' or somesuch)? Also,
what about having one or more of the registers be the
'lexical state register(s)' to inplement pragmas (or is
this the state stack?)?
> =head1 Opcodes
>
> Opcodes are all dispatched indirectly via an opcode
> function
> table. Each segment of bytecode (a segment roughly
> corresponding to a
> compilation unit--a precompiled module would be in its
> own segment,
> for example) has its own opcode function table.
Be wary of this. I tried this in Perl 5 (on an old sun4c,
granted), and I came out with something like a 5% slowdown
over having the function pointer actually stored in the op,
IIRC.
> =head1 The opcode loop
>
> This is a tight loop. All it does is call an opcode
> function, get back
> a pointer to the next opcode to execute, and check the
> event dispatch
> flag. Lather, rinse, repeat ad infinitum.
How does this port to a TIL form?
> =head1 Bytecode
Looks good from here (and a _lot_ prettier than
B::Bytecode/ByteLoader!).
-- BKS
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