[PATCH] D67359: [IVUser] Limit the iterations to check whether a loop has dedicated exits for extreme large case

Mon Sep 9 21:32:10 PDT 2019

skatkov added a comment.

In D67359#1664242 <https://reviews.llvm.org/D67359#1664242>, @wmi wrote:

> In D67359#1664241 <https://reviews.llvm.org/D67359#1664241>, @skatkov wrote:
>
> > I wonder whether the problem is in this function or in analysis itself?
> >  If it is a problem of analysis it is better to restrict it but not an utility function.
>
>
> I feel the problem is in the utility function. Currently the problem is exposed in IVUser pass but the same can happen anywhere else if only the function is called for a huge loop with many exits and with each exit having many predecessors.

Can you do some measurements to ensure that the issue is really in this utility function but not in the user of it?

At the same time it makes sense to update function description to specify that with your change the function can conservatively returns no if it could not get the precise answer.

Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D67359/new/

https://reviews.llvm.org/D67359