[PATCH] D84951: [LV] Try to sink users recursively for first-order recurrences.

[Ayal Zaks via Phabricator via llvm-commits]

Ayal added inline comments.


================
Comment at: llvm/lib/Analysis/IVDescriptors.cpp:822
+      return false;
   }
 
----------------
Perhaps the logic could be simplified somewhat, compressed to see it all together here:

```
WorkList = { Phi }
while WorkList not empty {
  Insn = pop from WorkList
  for (User *User : Insn->users()) {
    // Cyclic dependence
    if (Previous == User)
      return false;
    // No need to sink User
    if (DT->dominates(Previous, User) ||
        isa<PHINode>(User))
      continue;
    // Cannot sink User
    if ((User->getParent() != PhiBB) ||
        User->mayHaveSideEffects() ||
        User->mayReadFromMemory() ||
        (User->getParent()->getTerminator() == User) ||
        (SinkAfter.find(User) != SinkAfter.end()))
      return false;
    // Sink User tentatively and check its users
    if InstsToSink.insert(User)
      append User to Worklist
  }
}
```


Repository:
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  https://reviews.llvm.org/D84951/new/

https://reviews.llvm.org/D84951