C:\test>perl -MDevel::Peek -E"my $x = 12345; Dump $x; $x ^= 1; Dump $x"
SV = IV(0x2174e0) at 0x2174e8
  REFCNT = 1
  FLAGS = (PADMY,IOK,pIOK)
  IV = 12345
SV = IV(0x2174e0) at 0x2174e8
  REFCNT = 1
  FLAGS = (PADMY,IOK,pIOK)
  IV = 12344