instanceof_fast_path_repro.php

instanceof_fast_path_repro.php

@ -0,0 +1,133 @@
<?php

declare(strict_types=1);

/**
 * Reproducer for commit 559d1f63893f5262ad3da2cbb748b77d56a8af2f:
 * "Defer SAVE_OPLINE() on the INSTANCEOF fast path"
 *
 * Run this on a build before and after that commit.
 * The instance-of cases should get faster after the change.
 */

if (PHP_SAPI !== 'cli') {
    fwrite(STDERR, "Run from CLI.\n");
    exit(1);
}

class HitTarget
{
}

interface HitMarker
{
}

final class HitChild extends HitTarget implements HitMarker
{
}

function run_case(string $label, int $rounds, callable $fn): array
{
    $times = [];
    $sink = 0;

    $sink ^= $fn();

    for ($r = 0; $r < $rounds; $r++) {
        $start = hrtime(true);
        $sink ^= $fn();
        $times[] = (hrtime(true) - $start) / 1e9;
    }

    sort($times);

    return [
        'label' => $label,
        'best' => $times[0],
        'avg' => array_sum($times) / count($times),
        'sink' => $sink,
    ];
}

$iterations = isset($argv[1]) ? max(1, (int) $argv[1]) : 30_000_000;
$rounds = isset($argv[2]) ? max(1, (int) $argv[2]) : 7;

gc_disable();

$className = HitTarget::class;
$markerName = HitMarker::class;
$hitTarget = new HitTarget();
$hitChild = new HitChild();

$cases = [
    run_case('baseline', $rounds, static function () use ($iterations): int {
        $sum = 0;

        for ($i = 0; $i < $iterations; $i++) {
            if (($i & 1) === 0) {
                $sum++;
            }
        }

        return $sum;
    }),
    run_case('class-hit', $rounds, static function () use ($iterations, $hitTarget, $className): int {
        $sum = 0;

        for ($i = 0; $i < $iterations; $i++) {
            if ($hitTarget instanceof $className) {
                $sum++;
            }
        }

        return $sum;
    }),
    run_case('interface-hit', $rounds, static function () use ($iterations, $hitChild, $markerName): int {
        $sum = 0;

        for ($i = 0; $i < $iterations; $i++) {
            if ($hitChild instanceof $markerName) {
                $sum++;
            }
        }

        return $sum;
    }),
];

$byLabel = [];
foreach ($cases as $row) {
    $byLabel[$row['label']] = $row;
}

printf(
    "PHP %s\niterations=%d rounds=%d\n\n",
    PHP_VERSION,
    $iterations,
    $rounds
);

echo str_pad('case', 18) . str_pad('best(s)', 12) . str_pad('avg(s)', 12) . "sink\n";
echo str_repeat('-', 52) . "\n";
foreach ($cases as $row) {
    printf(
        "%-18s%-12.6f%-12.6f%d\n",
        $row['label'],
        $row['best'],
        $row['avg'],
        $row['sink']
    );
}

echo "\ninstanceof / baseline ratios (best time, lower is better):\n";
printf(
    "%-18s %.4fx\n",
    'class-hit',
    $byLabel['class-hit']['best'] / $byLabel['baseline']['best']
);
printf(
    "%-18s %.4fx\n",
    'interface-hit',
    $byLabel['interface-hit']['best'] / $byLabel['baseline']['best']
);