Aaron Sherman <[EMAIL PROTECTED]> wrote:
> On Wed, 2004-04-28 at 11:33, Dan Sugalski wrote:
> Only one question. What's the performance hit likely to be and is there
> any way around that performance hit for code that doesn't want to take
> it?
As Dan already said there is no performance hit (at least if the MMD
tables don't blow the caches).
Doing 5 M divide vtables[1] on Athon 800, -O3 build:
$ parrot -j mmdp.imc # 10 / 2
PerlInt 1.048340
Integer 1.097163 # left arg MMD, right is VTABLE_get_integer [2]
Integer 1.039819 # left+right MMD, both use PMC_int_val(pmc) [3]
$ parrot -j mmdp.imc # 10 / 3
PerlInt 1.503322 # LHS type morph to PerlNum
Integer 1.039199
The relevant function in integer.pmc has one of the follwing lines inside:
static void
integer_divide(Parrot_Interp interp, PMC* self, PMC* value, PMC* destination){
INTVAL result;
// result = PMC_int_val(self) / VTABLE_get_integer(interp, value); //[2]
result = PMC_int_val(self) / PMC_int_val(value); //[3]
VTABLE_set_integer_native(interp, destination, result);
}
leo
[1]
$ cat mmdp.imc
.pcc_sub _main prototyped
.const int max = 5000000
.const int val = 3 # or 2
$P0 = new PerlInt
$P1 = new PerlInt
$P2 = new PerlInt
$P1 = 10
$P2 = val
.local float start
start = time
.local int i
i = 0
lp1:
$P0 = $P1 / $P2
inc i
if i < max goto lp1
$N0 = time
$N0 -= start
print "PerlInt "
print $N0
print "\n"
$P0 = new Integer
$P1 = new Integer
$P2 = new Integer
$P1 = 10
$P2 = val
.local float start
start = time
.local int i
i = 0
lp2:
$P0 = $P1 / $P2
inc i
if i < max goto lp2
$N0 = time
$N0 -= start
print "Integer "
print $N0
print "\n"
end
.end
