[PATCH] D33265: [PredicateInfo ] Fix non-determinism in codegen uncovered by reverse iterating SmallPtrSet

[Mandeep Singh Grang via Phabricator via llvm-commits]

mgrang added a comment.

Thanks @davide and @dberlin for your comments.

Just wanted to confirm I understand this: In order to reuse the comparison function from ValueDFS_Compare in our case, we would have to move the localComesBefore function (or parts of it) out of ValueDFS_Compare so that both OBBMap and OpsToRename can use it as a comparator? ValueDFS_Compare constructor accepts BBs, so unless we first convert OpsToRename into ValueDFS (by calling our version of convertUsesToDFSOrdered) we cannot directly use it for sorting OpsToRename.
Or would it be simpler to just keep the comparator inline as you do in your code?

Also is it OK to add -reverse-iterate to the two unit tests as I have done in my patch (so that we catch any future non-determinism arising out of this piece of code)?


https://reviews.llvm.org/D33265