> On 12 Apr 2016, at 04:40, Daniel Green (via RT)
> <perl6-bugs-follo...@perl.org> wrote:
>
> # New Ticket Created by Daniel Green
> # Please include the string: [perl #127881]
> # in the subject line of all future correspondence about this issue.
> # <URL: https://rt.perl.org/Ticket/Display.html?id=127881 >
>
>
> '@array[0, 3, 7]' is much slower than '(@array[0], @array[3], @array[7])'
>
>
> time perl6 -e 'my @a = ^500;my @f;my $s = @a.elems;loop (my $i1 = 0; $i1 <
> $s-1; $i1++) { loop (my $i2 = $i1+1; $i2 < $s; $i2++) { @f.push(@a[$i1,
> $i2]) } };'
>
> real 0m14.974s
> user 0m14.947s
> sys 0m0.017s
>
>
> time perl6 -e 'my @a = ^500;my @f;my $s = @a.elems;loop (my $i1 = 0; $i1 <
> $s-1; $i1++) { loop (my $i2 = $i1+1; $i2 < $s; $i2++) { @f.push((@a[$i1],
> @a[$i2])) } };'
>
> real 0m0.897s
> user 0m0.877s
> sys 0m0.017s
>
>
> With Rakudo version 2016.03 built on MoarVM version 2016.03
This is a known issue. Anytime you use lists, the optimization paths are not
that well developed yet. To give you another example:
$ 6 'for ^100000 { my ($a,$b) = 42,666 }'
real 0m1.628s
user 0m1.582s
sys 0m0.041s
$ 6 'for ^100000 { my $a = 42; my $b = 666 }'
real 0m0.180s
user 0m0.152s
sys 0m0.026s
$ 6 'for ^100000 { my $a; my $b }'
real 0m0.170s
user 0m0.144s
sys 0m0.025s
$ 6 'say (1628 - 170) / (180 - 170)’
145.8
Liz
