At 10:45 AM 09-06-2001 -0400, Ken Fox wrote:
>Dave Mitchell wrote:
> > So how does that all work then? What does the parrot assembler for
> >
> > foo($x+1, $x+2, ...., $x+65)
>
>The arg list will be on the stack. Parrot just allocates new PMCs and
>pushes the PMC on the stack.
>
>I assume it will look something like
>
> new_pmc pmc_register[0]
> add pmc_register[0], $x, 1
> push pmc_register[0]
>
> new_pmc pmc_register[0]
> add pmc_register[0], $x, 2
> push pmc_register[0]
>
> ...
>
> call foo, 65
Hmmm, I assumed it would be something like:
load $x, P0 ;; load $x into PMC register 0
new P2 ;; Create a new PMC in register 2
push p0,p2 ;; Make P2 be ($x)
add p0,#1,p1 ;; Add 1 to $x, store in PMC register 1
push p1,p2 ;; Make P2 be ($x,$x+1)
add p0,#2,p1 ;; Add 2 to $x, store in PMC register 1
push p1,p2 ;; Make P2 be ($x,$x+1,$x+2)
...
call foo,p2 ;; Call foo($x,$x+1,...,$x+65)
Although this would be premature optimization, since I see this idiom being
used a lot, it may be useful to have some special-purpose ops to handle
creating arg-lists, like a "new_array size,register" op, that would create
a new PMC containing a pre-sized array (thus eliminating repeatedly growing
the array with the push ops), or a "push5 destreg, reg1, reg2, reg3, reg4,
reg5" op (and corresponding pushN ops for N=2 to 31) that push the
specified registers (in order) onto the destreg.
>Hmm. It didn't occur to me that raw values might go on the call
>stack. Is the call stack going to store PMCs only? That would
>simplify things a lot.
If ops and functions should be able to be used interchangeably, I wouldn't
expect any function arguments to be stored on the stack, but passed via
registers (or lists referenced in registers).
>- Ken
