Description:
------------
i would have expected that opcache optimizes the repeated FETCH_CONSTANT out

---------------------------------

define('IS_ROBOT', 1);

function a()
{
 return IS_ROBOT . IS_ROBOT . IS_ROBOT . IS_ROBOT;
}

function b()
{
 $IS_ROBOT = IS_ROBOT;
 return $IS_ROBOT . $IS_ROBOT . $IS_ROBOT . $IS_ROBOT;
}

---------------------------------

*************************************************************************************************************
*                                                VLD OPCACHE                                                *
*************************************************************************************************************

function name:  a
number of ops:  8
-------------------------------------------------------------------------------------
   7     0*       FETCH_CONSTANT                                   ~1      'IS_ROBOT'
         1*       FETCH_CONSTANT                                   ~2      'IS_ROBOT'
         2*       FAST_CONCAT                                      ~0      ~1, ~2
         3*       FETCH_CONSTANT                                   ~2      'IS_ROBOT'
         4*       FAST_CONCAT                                      ~1      ~0, ~2
         5*       FETCH_CONSTANT                                   ~2      'IS_ROBOT'
         6*       FAST_CONCAT                                      ~0      ~1, ~2
         7*       RETURN                                                   ~0

function name:  b
number of ops:  5
-------------------------------------------------------------------------------------
  12     0*       FETCH_CONSTANT                                   !0      'IS_ROBOT'
  13     1*       FAST_CONCAT                                      ~1      !0, !0
         2*       FAST_CONCAT                                      ~2      ~1, !0
         3*       FAST_CONCAT                                      ~1      ~2, !0
         4*       RETURN                                                   ~1

Expected result:
----------------
i would have expexted that repeatet FETCH_CONSTANT within a function is optimized out like the second implementation doing it in userland by copy it to a local variable

not that much of a performance overhead but on the other hand if it's a function which a loop using dozens of constants more than once.....