[PATCH] D21464: [PM] WIP: Introduce basic update capabilities to the new PM's CGSCC pass manager, including both plumbing and logic to handle function pass updates.

[David Li via llvm-commits]

davidxl added a comment.

Chandler, thanks for the tremendous effort for trying to make this work. At this moment, I only have very high level comments,  so please bear with me.

Can we have a design document describing the underlying algorithm with formal proof (traversing with mutation)? Given the level of complexity involved and the fact there is no prior literature we can refer to, it is important we get it right.

Besides  it is also  more important to understand what problem the added complexity is trying to solve, why those problems are important to be solved (evidence of missing opportunities in real apps), and why they can not be solved in other ways?  The same questions have been raised in Sean's email thread, and there are some interesting discussions there, so may be you can also chime in there?

As far as I can tell, for the new PM transition,  the consensus is to make the transition NFC initially, which will greatly lower the bar for the new PM to become the default.  If your plan is to make new PM transition depending on this update support in CGSCC pass to be ready,  we need to understand why.

thanks,

David


http://reviews.llvm.org/D21464