PassManager.passes() needs a drawer

[1ucian0]

For context, originally posted by @jaygambetta in #2179 (comment)

I also think I should be able to draw a pass manager

pm.draw()

and it make a flow diagram of all the passes I have in my pass manager with the inputs going into them

Via #2079, PassManager.passes() returns structure with the passes and flow control in a pass manager instance. A drawer should take that structure and make flow diagram based on it.

[maddy-tod]

I'm happy to do this if no one has started on it already? Are there any further ideas about what this should look like?

[1ucian0]

I was thinking in something like a flow chart in graphviz (we use it already for drawing the dag)... Let me know if you have questions about the PassManager.passes() structure.

[ajavadia]

I think the thing to show would be that blocks of multiple passes can have a "control" (do-while) and/or a "condition" (if). Otherwise just drawing each pass in a box, and showing the input parameters of the pass, seems ok.