PHPカンファレンス2013のセッション、「PHPコアから読み解く、定石の嘘ホント」を参考にまとめたスライドです。

1. 「PHPコアから読み解く 定石の嘘ホント」より
＠akirakoyasu
PHP CONFERENCE
2013 9/14 Sat. 大田区産業プラザPiO

2. Copyright © 2013 Akira Koyasu. Some rights reserved.
Theory
2
定石、定跡（じょうせき）とは、アブストラクトゲームに
おける用語である。お互いが最善と考えられる手を行った
場合の一連の手のこと。チェスでは、「セオリー」とも。
石を用いる囲碁、オセロ、連珠などでは「定石」が、駒を
用いる将棋、チェスなどでは「定跡」が用いられる。
- ja.wikipedia.org
photo#1

3. Copyright © 2013 Akira Koyasu. Some rights reserved. 3
Rule
２つのコードを見せます
どちらが速く動くか考えてください
考える時間は１０秒
相談しないで！

4. Copyright © 2013 Akira Koyasu. Some rights reserved.
Execution Time
4
$time1 = microtime(true);
// test code loop (100000 times)
$time2 = microtime(true);
printf("time: %f sn", ($time2 - $time1));

5. Copyright © 2013 Akira Koyasu. Some rights reserved.
opcode
5
$ sudo pecl install channel://pecl.php.net/vld-0.12.0
$ php -dvld.active=1 -dvld.execute=0 test.php
Extension vld

6. Copyright © 2013 Akira Koyasu. Some rights reserved.
PHP runtime
6
.php.php.php Parser
Compiler
Virtual Machine

7. Copyright © 2013 Akira Koyasu. Some rights reserved.
PHP runtime
6
.php.php.php Parser
Compiler
Virtual Machine
AST
構文解析

8. Copyright © 2013 Akira Koyasu. Some rights reserved.
PHP runtime
6
.php.php.php Parser
Compiler
Virtual Machineopcode
AST
構文解析
コンパイル

9. Copyright © 2013 Akira Koyasu. Some rights reserved.
PHP runtime
6
.php.php.php Parser
Compiler
Virtual Machineopcode
AST
構文解析
コンパイル
実行

10. Copyright © 2013 Akira Koyasu. Some rights reserved. 7
Ready?

11. Copyright © 2013 Akira Koyasu. Some rights reserved.
Loop
8
A B

12. Copyright © 2013 Akira Koyasu. Some rights reserved.
Loop
8
$c = sizeof($arr);
for ($i = 0; $i < $c; $i++) {
$t = $arr[$i];
}
foreach ($arr as $val) {
$t = $val;
}
A B
ただし、 とする$arr = range(0, 100);

13. Copyright © 2013 Akira Koyasu. Some rights reserved.
Loop
8
$c = sizeof($arr);
for ($i = 0; $i < $c; $i++) {
$t = $arr[$i];
}
foreach ($arr as $val) {
$t = $val;
}
A B
ただし、 とする$arr = range(0, 100);

14. Copyright © 2013 Akira Koyasu. Some rights reserved.
foreach ($arr as $val) {
$t = $val;
}
$c = sizeof($arr);
for ($i = 0; $i < $c; $i++) {
$t = $arr[$i];
}
FE_RESET
FE_FETCH
DO_FCALL 'sizeof'
IS_SMALLER
POST_INC
FETCH_DIM_R
Answer
9
A B

15. Copyright © 2013 Akira Koyasu. Some rights reserved.
foreach ($arr as $val) {
$t = $val;
}
$c = sizeof($arr);
for ($i = 0; $i < $c; $i++) {
$t = $arr[$i];
}
time: 0.683817 s
FE_RESET
FE_FETCH
time: 1.043019 s
DO_FCALL 'sizeof'
IS_SMALLER
POST_INC
FETCH_DIM_R
Answer
9
A B

16. Copyright © 2013 Akira Koyasu. Some rights reserved.
foreach ($arr as $val) {
$t = $val;
}
$c = sizeof($arr);
for ($i = 0; $i < $c; $i++) {
$t = $arr[$i];
}
time: 0.683817 s
FE_RESET
FE_FETCH
time: 1.043019 s
DO_FCALL 'sizeof'
IS_SMALLER
POST_INC
FETCH_DIM_R
Answer
9
A B

17. Copyright © 2013 Akira Koyasu. Some rights reserved.
foreach ($arr as $val) {
$t = $val;
}
$c = sizeof($arr);
for ($i = 0; $i < $c; $i++) {
$t = $arr[$i];
}
time: 0.683817 s
FE_RESET
FE_FETCHtime: 1.043019 s
DO_FCALL 'sizeof'
IS_SMALLER
POST_INC
FETCH_DIM_R
Answer
9
A B

18. Copyright © 2013 Akira Koyasu. Some rights reserved.
Elements
10
A B

19. Copyright © 2013 Akira Koyasu. Some rights reserved.
Elements
10
if (count($arr) > 0) {
;
}
if (!empty($arr)) {
;
}
$arr = array();ただし、 とする
A B

20. Copyright © 2013 Akira Koyasu. Some rights reserved.
Elements
10
if (count($arr) > 0) {
;
}
if (!empty($arr)) {
;
}
$arr = array();ただし、 とする
A B

21. Copyright © 2013 Akira Koyasu. Some rights reserved.
Answer
11
if (count($arr) > 0) {
;
}
if (!empty($arr)) {
;
}
A B
DO_FCALL 'count'
IS_SMALLER
ISSET_ISEMPTY_VAR
BOOL_NOT

22. Copyright © 2013 Akira Koyasu. Some rights reserved.
Answer
11
if (count($arr) > 0) {
;
}
if (!empty($arr)) {
;
}
A B
time: 0.026228 s time: 0.008356 s
DO_FCALL 'count'
IS_SMALLER
ISSET_ISEMPTY_VAR
BOOL_NOT

23. Copyright © 2013 Akira Koyasu. Some rights reserved.
Answer
11
if (count($arr) > 0) {
;
}
if (!empty($arr)) {
;
}
A B
time: 0.026228 s time: 0.008356 s
DO_FCALL 'count'
IS_SMALLER
ISSET_ISEMPTY_VAR
BOOL_NOT

24. Copyright © 2013 Akira Koyasu. Some rights reserved.
Answer
11
if (count($arr) > 0) {
;
}
if (!empty($arr)) {
;
}
A B
time: 0.026228 s time: 0.008356 s
DO_FCALL 'count'
IS_SMALLER
ISSET_ISEMPTY_VAR
BOOL_NOT

25. Copyright © 2013 Akira Koyasu. Some rights reserved. 12
Points
測ってみる 調べてみる
考えてみる

26. Copyright © 2013 Akira Koyasu. Some rights reserved. 13
Any Questions?

27. Copyright © 2013 Akira Koyasu. Some rights reserved.
Notes
This work is licensed under the Creative Commons Attribution-
NonCommercial 3.0 Unported License. To view a copy of this
license, visit http://creativecommons.org/licenses/by-nc/3.0/.
14
photo#1: http://www.flickr.com/photos/sbl/1617711/
Thank you very much, Feedback Welcome!
http://twitter.com/akirakoyasu
http://fb.me/akirakoyasu
http://www.akirakoyasu.net