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Date: Fri, 5 Jul 2024 21:58:41 +0200
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Subject: Re: [PHP-DEV] [RFC] Lazy Objects
To: Arnaud Le Blanc <arnaud.lb@gmail.com>
Cc: Marco Pivetta <ocramius@gmail.com>,
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From: tim@bastelstu.be (=?UTF-8?Q?Tim_D=C3=BCsterhus?=)

Hi

On 7/2/24 17:49, Arnaud Le Blanc wrote:
>> I'm curious, how did the implementation look like? Is there a proof of
>> concept commit or patch available somewhere? As the author of the first
>> internal enum (Random\IntervalBoundary) I had the pleasure of finding
>> out that there was no trivial way to efficiently match the various enum
>> cases. See the PR review here:
>> https://github.com/php/php-src/pull/9679#discussion_r1045943444
> 
> I've benchmarked this implementation:
> https://github.com/arnaud-lb/php-src/commit/f5f87d8a7abeba2f406407606949e5c6e512baab.
> Using a backed enum to have a more direct way to map enum cases to
> integers didn't make a significant difference.
> Here is the benchmark:
> https://gist.github.com/arnaud-lb/76f77b5d7409a9e4deea995c179c6e96.
> Caching the options array between calls had a less dramatic slowdown
> (around 10%): https://gist.github.com/arnaud-lb/87e7f58cc11463dd3aa098218eb95a90.

Your Gists don't seem to include the actual numbers, so the second link 
is not particularly useful.

However you said that using a backed enum does not improve the 
situation, so there probably really is not much that can be done.

For completeness I want to note, though: You might be able to improve 
the type checking performance by directly checking the CE instead of 
going through `instanceof_function()`, because you know that inheritance 
is not a thing for enums. Not sure if this makes much of a difference, 
given the fact that `instanceof_function()` already does this and is 
force-inlined, but it might remove the branch with the call to 
`instanceof_function_slow()`.

Best regards
Tim Düsterhus