@Override
	public Address evaluateConstant(VarnodeContext context, Instruction instr, int pcodeop,
			Address constant, int size, DataType dataType, RefType refType) {

		// Constant references below minSpeculative or near the end of the address space are suspect,
		// even if memory exists for those locations.
		AddressSpace space = constant.getAddressSpace();
		long maxAddrOffset = space.getMaxAddress().getOffset();
		long wordOffset = constant.getOffset();

		if (((wordOffset >= 0 && wordOffset < minSpeculativeOffset) ||
			(Math.abs(maxAddrOffset - wordOffset) < maxSpeculativeOffset)) &&
			!space.isExternalSpace()) {
			return null;
		}

		// could just be integer -1 extended into address
		if (wordOffset == 0xffffffffL || wordOffset == 0xffffL || wordOffset == -1L) {
			return null;
		}

		return constant;
	}
If you override this method, and the default behavior of checking 0-256 and mask values is desired,
call super.evaluateConstant() in your overriden method.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/analysis/ConstantPropagationContextEvaluator.java