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PHP 8 to Add a JIT

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Re: PHP 8 to Add a JIT

#21

Post by beberlei »

chrisseaton wrote: post #5

This is the RFC with more technical details https://wiki.php.net/rfc/jit . I believe their plan is to emit low-level code directly via DynAsm, without their own intermediate representation. This kind of approach has been tried again and again and again and every project doing this either not got the results they wanted and given up or has had to go back and add a proper intermediate representation. Examples include R…

Not sure if this qualifies as intermediate representation in the LLVM sense, but PHP has opcodes already, it is not fully interpreted anymore (like it was in PHP 3).

These opcodes are used for optimizations and cached for the lifetime of the PHP process (across multiple requests).

Re: PHP 8 to Add a JIT

#22

Post by pushpop »

yllus wrote: post #10
dexen wrote: post #2

There is something to be said about PHP's staying power. The early versions of the language weren't considered "right". Except maybe they were right for the problem at hand. The way I see it was PHP captured the vector of change , and left ample room for future developments. Both internal changes (hello, bytecode; hello, JIT), language level features (hi there, namespaces), and runtime level features (oh hai, countle…

I think PHP had a couple of obvious advantages - it almost had a "first mover" advantage in that it happened to be installed alongside CGI-BIN on shared webhosts way back in the way - plus Drupal and WordPress being PHP projects. But to me, one of the most significant advantages PHP has is that its documentation is terrific . PHP.net is simple, clear about parameters and return values (as clear as PHP lets it be anyw…

Things may have changed since v7 but historically I’ve not found PHPs documentation any better than any other language.

In fact I remember a few occasions where I’ve ended up going by the advice of the comments rather than the documentation itself because the documentation was either out dated or just plain wrong.

Re: PHP 8 to Add a JIT

#23

Post by maxxxxx »

I am pretty impressed with the path PHP has been taking lately. They have moved the language from being a mess into aggressively incorporating modern features at a very rapid pace. Especially PHP7 is a really nice language.

Re: PHP 8 to Add a JIT

#25

Post by tyingq »

yllus wrote: post #10
dexen wrote: post #2

There is something to be said about PHP's staying power. The early versions of the language weren't considered "right". Except maybe they were right for the problem at hand. The way I see it was PHP captured the vector of change , and left ample room for future developments. Both internal changes (hello, bytecode; hello, JIT), language level features (hi there, namespaces), and runtime level features (oh hai, countle…

I think PHP had a couple of obvious advantages - it almost had a "first mover" advantage in that it happened to be installed alongside CGI-BIN on shared webhosts way back in the way - plus Drupal and WordPress being PHP projects. But to me, one of the most significant advantages PHP has is that its documentation is terrific . PHP.net is simple, clear about parameters and return values (as clear as PHP lets it be anyw…

"it almost had a "first mover" advantage in that it happened to be installed alongside CGI-BIN on shared webhosts way back in the way"

That's a good observation. Because the mod_php and mod_perl Apache modules were much faster and lighter weight than CGI-BIN, and pre-installed on shared hosting, both PHP and Perl dominated the early web days.

Re: PHP 8 to Add a JIT

#26

Post by pas »

beberlei wrote: post #21
chrisseaton wrote: post #5

This is the RFC with more technical details https://wiki.php.net/rfc/jit . I believe their plan is to emit low-level code directly via DynAsm, without their own intermediate representation. This kind of approach has been tried again and again and again and every project doing this either not got the results they wanted and given up or has had to go back and add a proper intermediate representation. Examples include R…

Not sure if this qualifies as intermediate representation in the LLVM sense, but PHP has opcodes already, it is not fully interpreted anymore (like it was in PHP 3). These opcodes are used for optimizations and cached for the lifetime of the PHP process (across multiple requests).

That's probably too low-level. Usually an AST is needed that is void of all syntactic sugar, yet can express the required data flows and dependencies so the trivial substitutions/replacements/caching and refactorings can be done at this level.

Lower level bytecode lacks these higher level references (it usually has a lot of indices that index into raw lookup tables, but no real symbols that refer to results of computations and other variables).

Re: PHP 8 to Add a JIT

#28

Post by igi3ql »

yllus wrote: post #10
dexen wrote: post #2

There is something to be said about PHP's staying power. The early versions of the language weren't considered "right". Except maybe they were right for the problem at hand. The way I see it was PHP captured the vector of change , and left ample room for future developments. Both internal changes (hello, bytecode; hello, JIT), language level features (hi there, namespaces), and runtime level features (oh hai, countle…

I think PHP had a couple of obvious advantages - it almost had a "first mover" advantage in that it happened to be installed alongside CGI-BIN on shared webhosts way back in the way - plus Drupal and WordPress being PHP projects. But to me, one of the most significant advantages PHP has is that its documentation is terrific . PHP.net is simple, clear about parameters and return values (as clear as PHP lets it be anyw…

I haven't found PHP documentation to be better or worse than the documentation of other languages I've used.

What I dislike about it is the comments that every page includes. Most of them are very poorly written snippets of code from 15 years ago.

If you dislike those comments too, consider adding this to your ad blocker:

    php.net###usernotes

Re: PHP 8 to Add a JIT

#29

Post by kyriakos »

bratao wrote: post #14

One very important motivation what I do not see clearly delineated in this post is for Event-driven applications. Swoole[1] is an example of a PHP framework which enable some very interesting uses such as Websocket services. In those long lived processes, a JIT really shines! [1] https://www.swoole.co.uk/

Know any production grade projects using swoole? I was looking at it in the past but looks very early to trust a business on it.

Re: PHP 8 to Add a JIT

#30

Post by chiefalchemist »

pushpop wrote: post #22
yllus wrote: post #10

Earlier quoted context omitted.

I think PHP had a couple of obvious advantages - it almost had a "first mover" advantage in that it happened to be installed alongside CGI-BIN on shared webhosts way back in the way - plus Drupal and WordPress being PHP projects. But to me, one of the most significant advantages PHP has is that its documentation is terrific . PHP.net is simple, clear about parameters and return values (as clear as PHP lets it be anyw…

Things may have changed since v7 but historically I’ve not found PHPs documentation any better than any other language. In fact I remember a few occasions where I’ve ended up going by the advice of the comments rather than the documentation itself because the documentation was either out dated or just plain wrong.

Perhaps not better, but there certainly have been worse.

As for the comments. Yes. But at least they're there, and quite often helpful. Plenty of times I've read other docs where I wished they had commenting but alas didn't.

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