public void addPhiInsnForReg(int reg){
  insns.add(0,new PhiInsn(reg,this));
}

public void addPhiInsnForReg ( int reg ) { insns . add ( 0 , new PhiInsn ( reg , this ) ) ; }
adds a phi insn to the beginning of this block . the result type of the phi will be set to void , to indicate that it ' s currently unknown .
