3v4l.org

run code in 200+ php & hhvm versions
<?php $x = 'test'; $z = 'w'; function char($char) {return $char;} echo "this is a ${trim(' '.++$z.char(' '))}";
Finding entry points
Branch analysis from position: 0
1 jumps found. (Code = 62) Position 1 = -2
filename:       /in/0dLop
function name:  (null)
number of ops:  17
compiled vars:  !0 = $x, !1 = $z
line     #* E I O op                           fetch          ext  return  operands
-------------------------------------------------------------------------------------
   2     0  E >   ASSIGN                                                   !0, 'test'
   3     1        ASSIGN                                                   !1, 'w'
   4     2        NOP                                                      
   6     3        INIT_FCALL                                               'trim'
         4        PRE_INC                                          $4      !1
         5        CONCAT                                           ~5      '+', $4
         6        INIT_FCALL                                               'char'
         7        SEND_VAL                                                 '+'
         8        DO_FCALL                                      0  $6      
         9        CONCAT                                           ~7      ~5, $6
        10        SEND_VAL                                                 ~7
        11        DO_ICALL                                         $8      
        12        FETCH_R                      local               ~9      $8
        13        NOP                                                      
        14        FAST_CONCAT                                      ~10     'this+is+a+', ~9
        15        ECHO                                                     ~10
        16      > RETURN                                                   1

Function char:
Finding entry points
Branch analysis from position: 0
1 jumps found. (Code = 62) Position 1 = -2
filename:       /in/0dLop
function name:  char
number of ops:  3
compiled vars:  !0 = $char
line     #* E I O op                           fetch          ext  return  operands
-------------------------------------------------------------------------------------
   4     0  E >   RECV                                             !0      
         1      > RETURN                                                   !0
         2*     > RETURN                                                   null

End of function char

Generated using Vulcan Logic Dumper, using php 7.3.0