Idea of optimizing php !empty(...) expression.

Hi Oleg,

this is already accomplished.

if (! <exp>) <stat>

would usually be compiled to:

1: <exp>
2: NOT
3: JMPZ -> 5
4: <stat>
5: ...

But OpCache's built-in optimizer (https://github.com/php/php-src/blob/master/ext/opcache/Optimizer/block_pass.c) is able to recognize this during the block level analysis and creates the following opcodes for the Zend engine:

1: <exp>
2: JMPNZ -> 4
3: <stat>
4: ...

Please note that NOT+JMPZ are converted to an equivalent single opcode JMPNZ. An extra NOT_EMPTY opcode is therefore not necessary.

I do not quite understand why you experience a performance difference, probably OpCache is not enabled or optimization flags are not properly set. Please see http://php.net/manual/en/book.opcache.php for more info.

Cheers,

Benjamin Coutu

========== Original ==========
From: Oleg Serov serovov@gmail.com
To: internals@lists.php.net
Date: Sun, 08 Feb 2015 00:13:05 +0100
Subject: [PHP-DEV] Idea of optimizing php !empty(...) expression.

I use !empty() very often and decided to make a benchmark test.

Here is the code and results: http://pastebin.com/fMhhdQiW

if (!empty(...)) working on 23% slower than if (empty()) expression.

So if create new operator not_empty() it will improve performance.

The first question is: What do you think about optimizing !empty(...), do
we need it ?

And I see two way to make this happen.

1. Create new language entity "not_empty".
2. Improve parser and help to handle "!empty" calls different way.

It is obviously that option 2 is better. Is it real to optimize parser that
way?

Thanks!