FPGA-based real-time data processing for accelerating reconstruction at LHCb

<!--HTML-->In Run-3 beginning in 2022, the LHCb software trigger will start reconstructing events at the LHC average crossing rate of 30 MHz. Within the upgraded DAQ system, LHCb established a testbed for new heterogeneous computing solutions for real-time event reconstruction, in view of future runs at even higher luminosities. One such solution is a highly-parallelized custom tracking processor (“Artificial Retina”), implemented in state of the art FPGA devices connected by fast serial links. We describe the status of the development of a life-size demonstrator system for the reconstruction of pixel tracking detectors, that will run on real data during Run-3.