[llvm] [VPlan] Generalize collectUsersInExitBlocks for multiple exit bbs. (PR #115066)

[Florian Hahn via llvm-commits]

fhahn wrote:

> Hi @fhahn, it doesn't look like #112138 has to deal with users of exit values, which this patch says it's in preparation for. Do you plan to expand the scope of PR #112138 to include more of PR #88385?
> 
> I am very grateful for your help and feedback in trying to drive PR #88385 forward, but I was under the impression that PR #112138 was simply presenting an alternative basic skeleton for handling multiple loop region successors in VPlan, from which I could then continue to drive PR #88385 forwards.
> 

This is trying to avoid having to add extra code dealing with the exit phis following on the suggestions/comments in https://github.com/llvm/llvm-project/pull/112138/files#r1810491008.  https://github.com/llvm/llvm-project/pull/112138 still only handles live-ins in exit phis, but in the latest version it doesn't have to update the VPIRInstructions; instead it rejects any VPlans that contains VPIRInstructions without operands (i.e. because they are live-out inductions) or any of their added operands aren't live-ins. Alternatively I could also restore the code from https://github.com/llvm/llvm-project/pull/112138/files#r1810491008, WDYT?

https://github.com/llvm/llvm-project/pull/115066