private void gatherUnmarkedOp() {
		for (; opedgeproc < opedge.size(); ++opedgeproc) {
			PcodeOp op = opedge.get(opedgeproc).getOp();
			if (markset.contains(op)) {
				continue;
			}
			markop.add(op);
			markset.add(op);
		}
	}
Encode a particular PcodeOp and slot
@param op is the PcodeOp to preserve
@param slot is the slot to preserve (-1 for output, >=0 for input)
@param method is the method to use for encoding (4, 5, or 6)
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/pcode/DynamicHash.java