@begin: scope:[]  from
  [0] phi()
  to:@1
@1: scope:[]  from @begin
  [1] phi()
  [2] call main 
  to:@end
@end: scope:[]  from @1
  [3] phi()
main: scope:[main]  from @1
  [4] (byte*) main::screen#0 ← (byte*) 1024
  [5] *(*((const byte**) main::pscreen#0)) ← (byte) 'a'
  [6] *((const byte**) main::pscreen#0) ← ++ *((const byte**) main::pscreen#0)
  [7] *(*((const byte**) main::pscreen#0)) ← (byte) 'b'
  to:main::@return
main::@return: scope:[main]  from main
  [8] return 
  to:@return