$ perl -MDevel::Peek -e'$x=-2.1; Dump $x; $x*=0; Dump $x'
SV = NV(0x5291b8) at 0x504ca0
  REFCNT = 1
  FLAGS = (NOK,pNOK)
  NV = -2.1
SV = PVNV(0x507598) at 0x504ca0
  REFCNT = 1
  FLAGS = (NOK,pNOK)
  IV = -2
  NV = -0
  PV = 0

$ perl -MDevel::Peek -e'$x=-2.0; Dump $x; $x*=0; Dump $x'
SV = NV(0x5291b8) at 0x504ca0
  REFCNT = 1
  FLAGS = (NOK,pNOK)
  NV = -2
SV = PVNV(0x507598) at 0x504ca0
  REFCNT = 1
  FLAGS = (IOK,pIOK)
  IV = 0
  NV = -2
  PV = 0