Look into inlining methods which return constants and don't throw

[TysonAndre]

<?php
final class XYZ{
    public final function getVal() {
        return 'value';
    }
    public function main() {
        return $this->getVal();
    }
}

$_main: ; (lines=1, args=0, vars=0, tmps=0)
    ; (after optimizer)
    ; /path/to/test_inlining.php:1-10
L0 (10):    RETURN int(1)

XYZ::getVal: ; (lines=1, args=0, vars=0, tmps=0)
    ; (after optimizer)
    ; /path/to/test_inlining.php:3-5
L0 (4):     RETURN string("value")

XYZ::main: ; (lines=3, args=0, vars=0, tmps=1)
    ; (after optimizer)
    ; /path/to/test_inlining.php:6-8
L0 (7):     INIT_METHOD_CALL 0 THIS string("getVal")
L1 (7):     V0 = DO_UCALL
L2 (7):     RETURN V0