private void checkInput(Varnode addressVarnode) {
// TODO: Should we limit to registers defined in input parameter block
		Address addr = addressVarnode.getAddress();
		Register reg = program.getRegister(addr, addressVarnode.getSize());
		if (reg == null || reg.isProcessorContext() || reg.isProgramCounter() ||
			containsRegister(reg, registersModified)) {
			return;
		}
		addRegister(reg, inputRegs);
	}
Check for register corresponding to the specified varnode and add to inputRegs.
@param addressVarnode register or address varnode which has not been written
Ghidra/Features/Base/src/main/java/ghidra/util/state/ResultsState.java