
void main()
main: scope:[main]  from
  [0] phi()
  to:main::@1
main::@1: scope:[main]  from main main::@2
  [1] main::ptr#2 = phi( main/ptrs, main::@2/main::ptr#1 )
  [2] if((char *)0!=*main::ptr#2) goto main::@2
  to:main::@return
main::@return: scope:[main]  from main::@1
  [3] return 
  to:@return
main::@2: scope:[main]  from main::@1
  [4] *(*main::ptr#2) = 'a'
  [5] screen#0 = *main::ptr#2
  [6] screen#0[1] = 'b'
  [7] main::ptr#1 = main::ptr#2 + SIZEOF_POINTER
  to:main::@1
