hi,
we've started a project (will have a web-page soon) that aims to port the
php-language (www.php.net) to run on top of parrot. we've written some
initial code and i'm kinda stuck while writing the codegen (i target imc)
my problem is that php is typeless. i am writing code to to some basic
type-recognition in my ast to be able to leverage the much speedier I S and
N types in parrot, but for obvious reasons i have to make the php basic
type an PMC. problem now is that using pmc for everything will make execution
much much slower that it could be.
my compiler currently translates:
<?php
for ($i = 0; $i < 100; $i = $i + 5.5) {
echo "hallo";
}
?>
to:
.pcc_sub _main prototyped
.sym PerlUndef TEMP0
TEMP0 = new PerlUndef
.sym PerlUndef TEMP1
TEMP1 = new PerlUndef
.sym PerlUndef TEMP2
TEMP2 = new PerlUndef
.sym PerlUndef TEMP3
TEMP3 = new PerlUndef
.sym PerlUndef TEMP4
TEMP4 = new PerlUndef
.sym PerlUndef i
i = new PerlUndef
i = 0
LBL0:
TEMP1 = 100
I0 = 0
unless i < TEMP1 goto LBL3
I0 = 1
LBL3:
unless I0 goto LBL2
TEMP4 = "hallo"
print TEMP4
TEMP2 = 5.5
TEMP3 = i + TEMP2
i = clone TEMP3
goto LBL0
LBL2:
.end
(i know it can be made better - working on it) - but the basic dilemma is
obvious: $i starts as an INT and becomes a FLOAT at runtime. so my compiler
made it a PMC. (i know that i'll at one point have to write my own PMC for
the PHP base-type, but for now PerlUndef works for me).
because pmc as so much slower that native types i loose most of parrots
brilliant speed due to the fact that i don't know the types at
compile-time.
i believe you'll face the same problem once perl6 becomes a reality on
parrot so here's my question (i've only been on perl6-internals for some
week, so sorry if this has been discussed in depth before):
would't it make sense to introduce one additional new type into parrot that
can "morph" between the normal types (I, S, N, P)?
something like (i call the type VAL):
typedef enum { INT, NUMBER, STRING, ... PMC } ValType;
typedef struct {
ValType type;
union {
INTVAL i;
NUMBER n;
STRING s;
...
PMC p;
} u;
} VAL;
and add support for this in the executor in the most efficient way.
if you think this is unneeded could you explain how you are planning to
make untyped languages run really fast on parrot and what direction i have
to take to use that technique? (PMC will always carry the vtable jump
overhead, so they will be slower than what perl or php use currently in the
inner execution loop)
i'd also like to add that eg PHP has different semantics when you do binary
operations on strings that perl has so this VAL type would have to be
as flexible as a PMC. (PHP would have to use a different implementation
than Perl6 or Python)
thies
--
Thies C. Arntzen - Looking for all sorts of freelance work - just ask..
http://www.amazon.de/exec/obidos/wishlist/AB9DY62QWDSZ
