Dead Code Elimination (DCE)
PHP 7.1
compiled vars: !0 = $a
line #* E I O op ext return operands
3 0 E > QM_ASSIGN !0 1
4 1 > RETURN 0
PHP 7.2
compiled vars: none
line #* E I O op ext return operands
4 0 E > > RETURN 0
Try to trick it:
PHP 7.2
RECV !0
3 1 ASSIGN_ADD 0 !1 !0, 3
4 2 > RETURN !0
]]>
But...
|
PHP 7.2
compiled vars: !0 = $x, !1 = $y, !2 = $a
line #* op return operands
2 0 RECV !0
1 RECV !1
3 2 INIT_ARRAY !2 !0
4 3 ASSIGN_DIM !2, 1
4 OP_DATA !1
5 5 ASSIGN !2, !1
6 6 RETURN !2
|
PHP 7.3
compiled vars: !0 = $x, !1 = $y, !2 = $a
line #* op return operands
2 0 RECV !0
1 RECV !1
5 2 QM_ASSIGN !2 !1
6 3 RETURN !2
|
foo = $x;
return $x;
}
]]>
PHP 7.3
foo = $x;
return $x;
}
]]>
PHP 7.3
PHP 7.3
foo = 0;
$i = 1;
$c = $i < 2;
if ($c) {
$k = 2 * $i;
$o->foo = $i;
echo $o->foo;
}
$o->foo += 2;
$o->foo++;
return $o->foo;
}
]]>
PHP 7.4