I'm also an (ex?) compiler engineer and I've played a little with FPGAs and computer architecture. In addition to the obligatory processor design, I recently created a open-source place and route tool for iCE40 FPGAs:

https://github.com/cseed/arachne-pnr

Together with Yosys (a Verilog synthesis tool):

http://www.clifford.at/yosys/

and the IceStorm bitstream creation tools:

http://www.clifford.at/icestorm/

it provides a full Verilog-to-bitstream open source toolchain for the iCE40 FPGAs. There is also a low-cost (~$21) USB development board:

http://www.latticesemi.com/icestick

Unfortunately, this toolchain doesn't support VHDL, so I can't try out the OP's TPU.