Too small data memory causes cryptic "invalid immediate" error instead of nice error message explaining the too small data memory

[Heikki Kultala]

Data segment size is 20 kilobytes.

Data memory size is 16 kibibytes (14 address bits)

There is a 14-byte short immediate on a bus connected to LSU address port.

Instruction scheduler notices that all data memory addresses can be transferred via this immediate, and does not use long immediate for addresses in data segment.

The data segment is then created, and the data does to address which is higher than 16k.

TPEFProgramWriter tries to write the actual address value into TPEF file and as it does not fit into the immediate, it throws an exception.

There should be a check that the data segment is not bigger than the data memory before writing the instructions to the tpef file.