[llvm-dev] RFC: Switching to the new pass manager by default

[serge guelton via llvm-dev]

On Wed, Oct 18, 2017 at 06:50:54AM +0000, Chandler Carruth via llvm-dev wrote:
> Greetings everyone!
> 
> The new pass manager is getting extremely close to the point where I'm not
> aware of any significant outstanding work needed, and I'd like to see what
> else would be needed to enable it by default. Here are the current
> functionality I'm aware of outstanding:

Hi Chandler,

Here at QuarksLab we're also doing an update after each release so I
cannot test without significant effort, still I'm interested in the
answer to the following question:

In our compiler, we're sometime spawning a (legacy) passmanager in a pass (so
within an exisiting passmanager) when we want some dynamic pass
scheduling based on some analysis or user input.

Legacy passmanager forces the order between function pass and module
pass, they can't be interleaved properly, so we actually had to spawn
several PM instances one after the other to get a fine grain control over
the pass ordering.

How does the new pass manager interacts with these two use cases?