Detailed route chooses to go up to M6 when route guide says M2

[jeffng-or]

Subject

[Stage]: Detail Router.

Describe the bug

Found during mini-sweep experiments with asap7 ibex (see 3/19 ASAP7 ibex route guide tab): https://docs.google.com/spreadsheets/d/1iT0AK4K9mypLhlooibR_ixc0uNQgGDZAMrKYh79-Qik/edit?gid=1464874749#gid=1464874749

For the 1004 ps clock period, the M6 coverage % drops to 26.84%. The 1003.9 and 1004.1 clock periods have coverage of 57.63% and 90.32%, respectively. So, the drop to 26% is odd.

I looked at a couple of nets where it says the M6 coverage is 0%, but the detailed router actually chooses M6 over the M2 route guide. In the screenshots below, there is one M6 (blue) segment which I've drawn an arrow to. You can see the route guide is M2 (red).

Net 03192:

Net 04653_:

Is there a reason why the router chose to bypass both M2 and M4 in these routes?

@maliberty , I re-ran the sweep with a newer ORFS, so the numbers won't match up to what we were looking at before.

Expected Behavior

Better/more consistent correlation between route guide and coverage

Environment

orfs git commit tag: bdeb1893975b515d232747b2e0dbfc9e9b0989e8

To Reproduce

mkissue tarball: https://drive.google.com/file/d/1zzJgMAszURSmrbQQvsdE98WOxuQVSxBW/view?usp=drive_link

Relevant log output

Screenshots

No response

Additional Context

No response

[maliberty]

My guess is the local density is too high but it still seems surprising to go from m2 to m6

[maliberty]

It is described well in the above if you have sufficient detailed routing background. I don't think this will make an easy first project in that area.