[llvm-dev] How to get from "opt -O3" to "opt <a-single-pass>" with the new PM?

[Mikael Holmén via llvm-dev]

Hi,

I just wrote a PR about a crash that I only see with the new PM:
 https://bugs.llvm.org/show_bug.cgi?id=49185

Normally (with the old PM) when I get a crash with e.g. "opt -O3" I use
-debug-pass=Arguments to get the list of passes run, and then I usually
try to reduce the amount of passes with the goal to reach a simpler opt
command line just running one pass to get a small and stable
reproducer.

With the new PM I have no idea how to do this. -debug-pass=Arguments
doesn't do anything, it doesn't give an error either, it's just silent.

What is the intended workflow to reach a proper nice and small
reproducer that has a minumum of dependencies towards different passes
with the new PM?

Thanks,
Mikael