public boolean addAlias(String registerName, String alias) {
		Register register = registerMap.get(registerName);
		if (register == null) {
			return false;
		}
		if (registerMap.containsKey(alias)) {
			return false;
		}
		register.addAlias(alias);
		addRegisterToNameMap(alias, register);
		return true;
	}
Add an alias to a previously defined register.
@param registerName defined register
@param alias alias to be added to defined register
@return true if alias addition was successful, else false
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/lang/RegisterBuilder.java