debug shouldn't print entry/exit for parallel closures (but does)

[steven-johnson]

What it says on the tin -- it makes the debug feature near-useless if you have any parallelism in your schedule. Maybe it's useful for some corner cases but I haven't yet encountered such a case. Can we default it to off for these?

[abadams]

I think this change was unintended. It crept in when we move lowering of parallel closures into lowering instead of codegen. I agree it should be fixed.

[abadams]

Except the code looks like it's really just annotating the main LoweredFunc. I'll investigate.

[abadams]

ok, it looks like this was actually an intentional change, because code for it was added to LowerParallelTasks.cpp