public Varnode createConstantVarnode(long value, int size) {
		if (size == 1) {
			byte b = (byte) value;
			final int offset = 128;
			Varnode bv = byteVarnodes[b + offset];
			if (bv == null) {
				AddressSpace spc = addrFactory.getConstantSpace();
				Address addr = spc.getAddress(b & 0xff);
				bv = new Varnode(addr, size);
				byteVarnodes[b + offset] = bv;
			}
			return bv;
		}
		AddressSpace spc = addrFactory.getConstantSpace();
		Address addr = spc.getAddress(value);
		return new Varnode(addr, size);
	}
Check if the symbol at the address is read_only.

@param addr - address of the symbol

@return true if the block is read_only, and there are no write references.
Ghidra/Features/Base/src/main/java/ghidra/program/util/VarnodeContext.java