Tracing JIT drops loop-PHI CV register from SNAPSHOT after intermediate op1_def

Description

Tracing JIT returns wrong values from hot loops!

<?php
function f(array $meta, int $n): int {
    $s = 0; $i = 0; $sink = 0;
    while ($i < $n) {
        $copy = $s;                    // QM_ASSIGN, op1_def on $s under RC inference
        $sink += $copy;                // keep ASSIGN past DCE
        $m = (int) $meta[$s];          // FETCH_DIM_R use of $s, ZREG_LAST_USE
        if (($m & 0xFF) === 1) {       // IS_IDENTICAL guard, side-exit's SNAPSHOT misses $s
            $i++;
            $s = ($m >> 32) & 0xFFFFFF;
            continue;
        }
        return $s;
    }
    return $s;
}
$meta = [0 => 1 | (1 << 32), 1 => 2 | (2 << 32)];
for ($w = 0; $w < 2000; $w++) f($meta, 3);
var_dump(f($meta, 3));

Results in:

$ php -d opcache.enable_cli=1 -d opcache.jit_buffer_size=64M -d opcache.jit=tracing repro.php
int(0)

Expected:

$ php -d opcache.enable_cli=1 -d opcache.jit_buffer_size=64M -d opcache.jit=function repro.php
int(1)

PHP Version

PHP 8.4 and above

Start by running the supplied repro.php with the tracing and function JIT settings, then compare the resulting values and inspect the loop's snapshot behavior around the intermediate operation and side exit. Done means the tracing JIT returns int(1), matching the function JIT result, without regressing the provided hot-loop case.