Why if/else block should be avoided in loop, if possible.

branchPredictionPerformance.php

<?php
$sortedSet = range(1, 10000000);
$randomSet = $sortedSet;
shuffle($randomSet);

$cnt = count($sortedSet);
$filter = $cnt / 2;
$sortedSetChunks = array_chunk($sortedSet, $filter);
$randomSetChunks = array_chunk($randomSet, $filter);

//process random set by considering if/ else block within loop
$startTime = microtime(true);
processSet($randomSet, $filter);
$endTime = microtime(true);

echo "\nRandom set with if/ else block processed in " . ($endTime - $startTime) . " s\n";

//process random sets without any if else block in loop
$startTime = microtime(true);
foreach ($randomSetChunks as $randomSet) {
    processBrokenSet($randomSet);
}
$endTime = microtime(true);

echo "\nSplit random sets processed in " . ($endTime - $startTime) . " s\n";

//process sorted set by considering if/ else block within loop
$startTime = microtime(true);
processSet($sortedSet, $filter);
$endTime = microtime(true);

echo "\nSorted set with if/ else block processed in " . ($endTime - $startTime) . " s\n";

//process sorted sets without any if else block in loop
$startTime = microtime(true);
foreach ($sortedSetChunks as $sortedSet) {
    processBrokenSet($sortedSet);
}
$endTime = microtime(true);

echo "\nSplit sorted sets processed in " . ($endTime - $startTime) . " s\n";

function processSet(array $set, $filter)
{
    $i = 0;
    $sum = 0;
    $sum1 = 0;

    foreach ($set as $value) {
        if ($i > $filter) {
            $sum += $value;
        } else {
            $sum1 += $value;
        }

        $i++;
    }

    $total = ($sum + $sum1);
    echo "Sum: $sum Sum1: $sum1 Total: $total";

    return $total;
}

function processBrokenSet(array $set)
{
    $sum = 0;

    foreach ($set as $value) {
        $sum += $value;
    }

    echo "Sum: $sum";

    return $sum;
}