PHP polymorphic inline caches

lol.php

<?php

class A {
	public $somePropertyWithReasonablyLongName = 1;
}

class B {
	public $somePropertyWithReasonablyLongName = 1;
}


// AAAA
$arr = [];
for ($i = 0; $i < 256; $i++) {
	$arr[$i] = new A;
}

$s = microtime(1);
for ($i = 0; $i < 10000000; $i++) {
	$arr[$i & 0xff]->somePropertyWithReasonablyLongName;
}
echo microtime(1) - $s, " s\n";



// ABAB
$arr = [];
for ($i = 0; $i < 256; $i++) {
	$arr[$i] = (($i % 2 === 0) ? new A : new B);
}

$s = microtime(1);
for ($i = 0; $i < 10000000; $i++) {
	$arr[$i & 0xff]->somePropertyWithReasonablyLongName;
}
echo microtime(1) - $s, " s\n";


//        PHP 5.6   PHP 7.0
// -------------------------
// AAAA     0.6 s     0.3 s
// ABAB     0.7 s     0.4 s