Sara GolemonMay 17

"""Checking whether an array is empty with a strict comparison against the empty array is a common pattern in PHP. A GitHub search for "=== []" language:PHP reveals 44k hits. From the set of !$a, count($a) === 0, empty($a) and $a === [] it however is also the slowest option."""

https://github.com/php/php-src/pull/18571

This is a great example of how you should write whatever you find most readable and maintainable, and let us worry about efficiency. Wtih this PR, the "slow" approach becomes a "fast" one.

zend_vm: Add OPcode specialization for `=== []` by TimWolla · Pull Request #18571 · php/php-src

Checking whether an array is empty with a strict comparison against the empty array is a common pattern in PHP. A GitHub search for "=== []" language:PHP reveals 44k hits. From the set of...

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Show threadBen RamseyMay 17
@pollita This is great! I’ve been using `=== []` because logic dictates it should be faster than a function call (i.e., `count($a) === 0`). I had no idea it was the slower option.
Show threadNiels DosscheMay 17
@ramsey Count is usually not a function call, it's a dedicated opcode
Show threadTim DüsterhusMay 17
@nielsdos @ramsey Within namespaces it's important to point out that this optimization only happens with fully-qualifying the call to `count()`. Either as `\count()` or via `use function count;`. Otherwise a `count()` function could exist in the namespace.
Show threadNiels DosscheMay 18
@timwolla True. Which makes me wonder whether it makes sense to emit a JMP_FRAMELESS opcode, not to call these functions framelessly, but to try to use the dedicated op anyway. Maybe I should try this
Show threadGina Peter BanyardMay 18
@nielsdos @timwolla Isn't the problem the fallback to global namespace the problem? As I'm not really sure how you will be able to get from the opcode that does this to the call one being frameless
Show threadNiels Dossche
@Girgias @timwolla The idea is to do something like this (in pseudocode):
01 JMP_FRAMELESS 04 string("foo\\strlen")
... etc
02 V0 = DO_FCALL_BY_NAME
03 JMP 05
04 V0 = COUNT ...
05 Do something with V0
May 18 at 4:16pmWeb