public boolean interferes(RegisterSpec oldSpec, int newReg) {
    return interferes(oldSpec.getReg(), newReg, oldSpec.getCategory());
  }
Checks to see if old namespace reg {@code oldReg} interferes with what currently maps to {@code
newReg}.

@param oldSpec {@code non-null;} old namespace register
@param newReg new namespace register
@return true if oldReg will interfere with newReg
android/android_framework/dex-maker/src/main/java/com/android/dx/ssa/InterferenceRegisterMapper.java