Improvements to array.c code base

9 years ago by Benjamin Coutu — view source

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Hi Dmitry,

I think Xinchen Hui has already implemented the range-function suggestion. I very much appreciate that you are working on the for-each optimization/consistency, this will improve things quite a bit. Focusing on big improvements (thinking anything "hashtable") is absolutely the way to go.

Thanks,

Ben

========== Original ==========
From: Dmitry Stogov dmitry@zend.com
To: Benjamin Coutu ben.coutu@zeyos.com
Date: Mon, 02 Feb 2015 06:53:20 +0100
Subject: [PHP-DEV] Re: Improvements to array.c code base

Hi Benjamin,

We are in the state, when we mainly have to concentrate on big improvements
that we have to deliver till mid of March.
I keep your ideas, but they are stuck at the end of my TODO list.

Thanks. Dmitry.

On Tue, Jan 20, 2015 at 11:30 AM, Benjamin Coutu ben.coutu@zeyos.com
wrote:

Hi Dmitry,

I was doing some code review of ext/standard/array.c and have recognized
some potential for a few performance improvements:

=== ARRAY_SLICE(..., preserve_keys=false) ===

array_slice() can always construct a packed array if preserve_keys is
false, restricting it to inputs with packed flag does not make much sense.
Removing the check for packed inputs on line 2376 would improve
performance if used on non-packed inputs with the default
preserve_keys=false.
Furthermore, ZEND_HASH_FOREACH_VAL should be used instead of
ZEND_HASH_FOREACH_NUM_KEY_VAL on line 2379.
It also think range() should use FAST_ZPP as it is a basic language
feature (other languages even have extra operators for it, e.g. [0..10])

=== RANGE(...) ===

range() always returns a numerically indexed array [0..count-1]. The
resulting array therefore should be constructed as a packed array
(ZEND_HASH_FILL_PACKED+ZEND_HASH_FILL_ADD instead of
zend_hash_next_index_insert_new).

=== ARRAY_FILL(start_key=0, ...)

Just like with range(), array_fill() always returns a numerically indexed
array [0..count-1] if start_key is 0. In this special but very common case
the resulting array can be constructed as a packed array
(ZEND_HASH_FILL_PACKED+ZEND_HASH_FILL_ADD instead of
zend_hash_next_index_insert_new).
Another common case is for start_key to be 1. One could refine the
proposed packed-array branch to just set the first bucket to undefined in
this case.

=== COUNT(...) ===

count() is so ubiquitous! Giving it an opcode and making it part of the VM
seams reasonable.

Please let me know your thoughts.

Cheers,

Ben

--

Benjamin Coutu
Zeyon Technologies Inc.
http://www.zeyos.com