[Profiler] Profiling support for parallel programs

[ayakayorihiro]

This PR contains:

• The profiler-instrumentation pass is now updated to contain four types of probes in order to capture call site information.
  • group_probe: A probe that is high when a group is active.
  • primitive_probe: A probe that is high when a primitive cell is active.
  • se_probe: A probe that is high when a group that structurally enables another group is active.
  • cell_probe: A probe that is high when a group that invokes a non-primitive cell is active.
• profiler-process.py: an updated VCD postprocessing script that generates .folded and .dot files:
  • A "flattened" flame graph, where each parallel arm gets its own "cycle". So, if arm A and arm B were executing on a single cycle, the flame graph would account for a cycle in arm A and a cycle in arm B.
  • A scaled flame graph, where a cycle is divided between the parallel arms in execution. So, if arm A and arm B were executing on a single cycle, the flame graph would account for 0.5 cycles in arm A and 0.5 cycles in arm B.
  • aggregate.dot: A tree summary of the execution of the program. Nodes (groups and cells) are labeled with the number of times the node was a leaf, and edges are labeled with the number of cycles that edge was activated.
  • rank{i}.dot: A tree representation of the ith most active stack picture. rankings.csv lists the specific cycles that each ranked tree was active for.
• Updated fud2 support (fud2/scripts/profiler.rhai)
• Utility scripts to help convert generated .folded and .dot files into visualizations (svg and png files respectively)
• Updated tests/cleanup of old tests that relied on scripts that no longer exist

As usual, I'd really appreciate any suggestions or thoughts!!

[ekiwi]

Two small changes and then we can merge this in.

[ekiwi]

!

@ayakayorihiro : is this ready to be merged?

[ayakayorihiro]

Merging :)