v8.0.0-rc1

Added

• Support for arbitrary FPGA device grids/floorplans
• Support for clustered blocks with width > 1
• Customizable connection-block and switch-blocks patterns (controlled from FPGA architecture file)
• Fan-out dependent routing mux delays
• VPR can generate/load a routing architecture (routing resource graph) in XML format
• VPR can load routing from a .route file
• VPR can performing analysis (STA/Power/Area) independently from optimization (via vpr --analysis)
• VPR supports netlist primitives with multiple clocks
• VPR can perform hold-time (minimum delay) timing analysis
• Minimum delays can be annotated in the FPGA architecture file
• Flow supports formal verification of circuit implementation against input netlist
• Support for generating FASM to drive bitstream generators
• Routing predictor which predicts and aborts impossible routings early (saves significant run-time during minimum channel width search)
• Support for minimum routable channel width 'hints' (reduces minimum channel width search run-time if accurate)
• Improved VPR debugging/verbosity controls
• VPR can perform basic netlist cleaning (e.g. sweeping dangling logic)
• VPR graphics visualizations:
  • Critical path during placement/routing
  • Cluster pin utilization heatmap
  • Routing utilization heatmap
  • Routing resource cost heatmaps
  • Placement macros
• VPR can route constant nets
• VPR can route clock nets
• VPR can load netlists in extended BLIF (eBLIF) format
• Support for generating post-placement timing reports
• Improved router 'map' lookahead which adapts to routing architecture structure
• Script to upgrade legacy architecture files (vtr_flow/scripts/upgrade_arch.py)
• Support for Fc overrides which depend on both pin and target wire segment type
• Support for non-configurable switches (shorts, inline-buffers) used to model structures like clock-trees and non-linear wires (e.g. 'L' or 'T' shapes)
• Various other features since VTR 7

Changed

• VPR will exit with code 1 on errors (something went wrong), and code 2 when unable to implement a circuit (e.g. unroutable)
• VPR now gives more complete help about command-line options (vpr -h)
• Improved a wide variety of error messages
• Improved STA timing reports (more details, clearer format)
• VPR now uses Tatum as its STA engine
• VPR now detects missmatched architecture (.xml) and implementation (.net/.place/.route) files more robustly
• Improved router run-time and quality through incremental re-routing and improved handling of high-fanout nets
• The timing edges within each netlist primitive must now be specified in the section of the architecture file
• All interconnect tags must have unique names in the architecture file
• Connection block input pin switch must now be specified in section of the architecture file
• Renamed switch types buffered/pass_trans to more descriptive tristate/pass_gate in architecture file
• Require longline segment types to have no switchblock/connectionblock specification
• Improve naming (true/false -> none/full/instance) and give more control over block pin equivalnce specifications
• VPR will produce a .route file even if the routing is illegal (aids debugging), however analysis results will not be produced unless vpr --analsysis is specified
• VPR long arguments are now always prefixed by two dashes (e.g. --route) while short single-letter arguments are prefixed by a single dash (e.g. -h)
• Improved logic optimization through using a recent 2018 version of ABC and new synthesis script
• Significantly improved implementation quality (~14% smaller minimum routable channel widths, 32-42% reduced wirelength, 7-10% lower critical path delay)
• Significantly reduced run-time (~5.5-6.3x faster) and memory usage (~3.3-5x lower)
• Various other changes since VTR 7

Fixed

• FPGA Architecture file tags can be in arbitary orders
• SDC command arguments can be in arbitary orders
• Numerous other fixes since VTR 7

Deprecated

Removed

• Classic VPR timing analyzer
• IO channel distribution section of architecture file