Re: [VOTE] Make compact function reports undefined passed variables
| From: | Dmitry Stogov | Date: | Wed, 13 Jun 2018 08:42:16 +0000 |
| Subject: | Re: [VOTE] Make compact function reports undefined passed variables | ||
| Groups: | php.internals | ||
| Request: | Send a blank email to internals+get-102243@lists.php.net to get a copy of this message | ||
On Jun 10, 2018 10:46 PM, "Hoffman, Zachary Robert" <zrhoffman@ku.edu> wrote:
>The existence of anything that internally relies on
> y is a
>blocker for applying further optimisations to the engine (think stack frames),
>which is probably why Dmitry suggested its removal.
I did not know it was an optimization issue.
Accessing variables by name is a problem for optimimisation and JIT-ing, because we lose data-flow
dependencies. But, this is not the end of the world. We just don't optimize functions that use
this "bad" pattern.
Thanks. Dmitry.
I suppose I could substitute a userland equivalent:
function compact_(array $compact, array $vars)
{
return array_intersect_key($vars, array_flip($compact));
}
which changes A::c() to
function c()
{
$d = $this->d();
$a = pow($d, $d + 1);
$c = $a ^ 0b1100;
$b = $a - $d;
return new B(
compact_(
$this->b(),
get_defined_vars()
)
);
}
That is not so bad. As far as I am concerned, deprecate away.