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Date: Sun, 4 Aug 2024 19:53:11 +0200
Message-ID: <CAPyj-LA1YqmVEc7SwXZGtaFi=qOMOswOyZVkdFm_8SOYpv644A@mail.gmail.com>
Subject: Re: [PHP-DEV] [Concept] Flip relative function lookup order (global,
 then local)
To: PHP internals <internals@lists.php.net>
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From: tovilo.ilija@gmail.com (Ilija Tovilo)

Hi Claude

On Fri, Aug 2, 2024 at 9:02=E2=80=AFPM Claude Pache <claude.pache@gmail.com=
> wrote:
>
> I propose the following alternative approach:
>
> * establish a restricted whitelist of global functions for which the perf=
ormance gain would be noteworthy if there wasn=E2=80=99t any need to look a=
t local scope first;
>
> * for those functions, disallow to define a function of same name in any =
namespace, e.g.: https://3v4l.org/RKnZt
>
> That way, those functions could be optimised, but the current semantics o=
f namespace lookup would remain unchanged.

That would be an improvement over the status quo. However, if you look
at the bullet points in my original email, while some of the
optimizations apply only to some functions (CTE, custom opcodes and
frameless calls), others apply to all internal, global functions
(double-lookup, lookup by offset, specialized argument passing).
Hence, we may only get a fraction of the benefits by restricting the
optimization to a handful of functions. I also wonder if the impact is
actually bigger, as then there's no workaround for redeclaring the
function, requiring much bigger refactoring.

Ilija