visualize scheduling result: dump to Graphviz's dot file

[zihaoli-cn]

Add a supplementary visualizing tool. It is useful if you want to see the scheduling result on the data dependence graph.

Features:

• show critical path explicitly
  • nodes and edges on critical path are colored in red
• show pipeline register explicitly
  • summary of the total length
• show nodes' name, op(operands...), type, and delay

Here is an example to visualize crc32.opt.ir.

bazel build //xls/visualization/sched_viz:sched_printer_main //xls/examples:ir_examples
bazel-bin/xls/visualization/sched_viz/sched_printer_main --clock_period_ps=8 --delay_model=unit bazel-bin/xls/examples/crc32.opt.ir > tmp.dot
dot -Tpng tmp.dot -ocrc32.png

The output will be: