On Tue, Dec 12, 2017 at 2:43 AM, Johannes Schlüter
<johan...@schlueters.de> wrote:
> The issue, as you well know, is that references disable copy-on-write. Thus
> assume you have code like this:
>
> function with_ref(&$a) {
> count ($a);
> }
>
> function no_ref($a) {
> count($a);
> }
>
> The count in with_ref() will copy the array, while no_ref() can use copy on
> write and won't actually copy.
>
That *was* true in PHP 5.
In PHP 7, the with_ref() version has a very slight overhead boxing the
array into an IS_REF zval, then unboxing it for the call to count().
This isn't a deep (or even shallow) copy. It's one extra zval alloc
and a few integer ops.
-Sara
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