Ah, sorry! Misread your post. Anyways, the compiler doesn't transform `\array_keys()` yet, so there's no optimization for that.
As for other compiler optimizations, 2 that I know that the compiler does is: 1. Binary OP evaluation i. e. `2 * 2` does not yield `ZEND_ADD` opcode but is instead computed by the compiler directly. 2. There are special functions that have their own opcodes. You can learn more about those here: https://phpinternals.net/articles/optimising_internal_functions_via_new_opcode_instructions Best regards, Benas On Tue, Sep 15, 2020, 4:44 PM Chase Peeler <chasepee...@gmail.com> wrote: > I wasn't proposing that my example be supported. I'm totally okay with the > fact that it doesn't. My question was about whether or not those kinds of > optimizations are documented anywhere so that developers can make sure they > don't miss out on them by not fitting the proper pattern. > > On Tue, Sep 15, 2020 at 9:40 AM Benas IML <benas.molis....@gmail.com> > wrote: > >> Hey, >> >> During my free time, I'm implementing that specific `array_keys` >> optimization. I'm not planning on supporting cases like yours (i. e. >> indirection through a variable) since there's no point in doing that. And >> also, it's not feasible to support every use case. Should we also support >> cases like this? >> >> ```php >> $a = 'array_keys'; >> $b = $a(...); >> $c = 'b'; >> >> foreach ($$c as $key) { >> ... >> } >> ``` >> >> Obviously not. `\array_keys` optimization will work the same way as an >> optimized `strlen` function works. >> >> That means that the optimization is only going to be applied if the >> `array_keys` function is used directly in the `foreach` loop and only if a) >> either the namespace is global b) or `\array_keys(...)`/`use function >> array_keys` is used. >> >> >> Best regards, >> Benas >> >> On Tue, Sep 15, 2020, 4:23 PM Chase Peeler <chasepee...@gmail.com> wrote: >> >>> I brought this up on another thread, but it wasn't addressed (which is >>> fine, since it was somewhat off-topic). I thought it might be >>> worth bringing up in its own thread, though. >>> >>> In the other thread, someone had mentioned the following compiler >>> optimization >>> >>> foreach(\array_keys($arr) as $key) { >>> >>> and quietly transform that into: >>> >>> foreach ($arr as $key => >>> $_unusedVariableNameThatIsntEvenSpilledToTheScope) >>> { >>> >>> I would be more likely to write: >>> $keys = array_keys($arr); >>> foreach($keys as $key){ >>> Which would prevent me from being able to take advantage of the >>> optimization. >>> >>> So, what I was wondering, is if there are other optimizations I might be >>> missing out on, and if so, are they documented anywhere? >>> >>> >>> -- >>> Chase Peeler >>> chasepee...@gmail.com >>> >> > > -- > Chase Peeler > chasepee...@gmail.com >
