too long

I'm learning PHP and trying to write a little dice loop. I wonder how to rewrite this in a more appropriate syntax:

<?php
    $rollcount = 1;

    do {
        $v = rand(1, 6);
        $w = rand(1, 6);
        $rollcount++;
        echo "<p>$v, $w</p>";
    }
    while ($v != $w);

    if ($v == $w) {
        echo "<p>It took $rollcount turns until double!</p>";
    } else {}
?>

You don't NEED to have an else statement:

if ($v == $w) {
    echo "<p>It took $rollcount turns until double!</p>";
}

If fact, you shouldn't have one unless it is going to perform a specific set of tasks.

$rollcount = 0;
while(true){
    ++$rollcount;
    $v = rand(1,6);
    $w = rand(1,6);
    echo "<p>".$v.", ".$w."</p>";
    if($v === $w){
        break;
    }
}
echo "<p>It took ".$rollcount." turns until double!</p>";

Simply remove that else clause if it doesn't do anything

 else {}

You don't even need that if statement, because control will reach there only when they are both equal.

<?php
    $rollcount = 1;
    do {
        $v = rand(1, 6);
        $w = rand(1, 6);
        $rollcount++;
        echo "<p>$v, $w</p>";
    }
    while ($v != $w);
    echo "<p>It took $rollcount turns until double!</p>"; // that `if` was no needed here. Its implied.
?>