perf no longer figures out call stacks when debuginfo-level is enabled

[saethlin]

In the past (weeks ago?) I used to often profile a locally built compiler with debuginfo-level = 1 using perf record --call-graph=dwarf cargo +stage1 build. This used to work great, but somewhat recently, the flamegraphs I render with perf script | inferno-collapse-perf | inferno-flamegraph > flamegraph.svg almost look like they are from a built without debuginfo enabled.

I don't have much useful information to share right now. I'm not sure what would be helpful for debugging this. I can provide some demonstration of the flamegraphs I get out of inferno in a few days, but if anyone has specific data they'd like about the builds I'm producing, happy to provide that.