public void set(int reg, TypeBearer type, LocalItem local) {
      this.reg = reg;
      this.type = type;
      this.local = local;
    }
Set all the instance variables.

@param reg {@code >= 0;} the register number
@param type {@code non-null;} the type (or possibly actual value) which is loaded from or
    stored to the indicated register
@param local {@code null-ok;} the associated local variable, if any
@return {@code non-null;} an appropriately-constructed instance
android/android_framework/dex-maker/src/main/java/com/android/dx/rop/code/RegisterSpec.java