This feels somewhat different, but still a hack.
I don't have strong suggestions on how to approach this, but what we've got
here feels like a hack and one prone to bitrot.
All the above needs a bit of cleanup in the way we use (or not use) PROP_xxx.
For example right now you can't startwith a __GIMPLE with a pass inside the
loop pipeline because those passes expect loops to be initialized and be in
loop-closed SSA. And with the hack above for the property providers you'll
always run pass_crited (that's a bad user of a PROP_).
Ideally we'd figure out required properties from the startwith pass
(but there's not
an easy way to compute it w/o actually "executing" the passes) and then enable
enough passes on the way to it providing those properties.
Or finally restructure things in a way that the pass manager automatically runs
property provider passes before passes requiring properties that are
not yet available...
Instead of those pass->name comparisions we could invent a new flag in the
pass structure whether a pass should always be run for __GIMPLE or ___RTL
but that's a bit noisy right now.
So I'm fine with the (localized) "hacks" for the moment.