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

[Florian Hahn via Phabricator via llvm-commits]

fhahn added inline comments.


================
Comment at: llvm/lib/Analysis/IVDescriptors.cpp:822
+      return false;
   }
 
----------------
Ayal wrote:
> 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
>   }
> }
> ```
Thanks! I adjusted/compacted the code as suggested, but with keeping the check if the instruction has been sunk already and the assertion is UserI is a PHINode.


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https://reviews.llvm.org/D84951