[PATCH] D33543: Re-enable "[SCEV] Do not fold dominated SCEVUnknown into AddRecExpr start"

[Max Kazantsev via Phabricator via llvm-commits]

mkazantsev added inline comments.


================
Comment at: lib/Analysis/ScalarEvolution.cpp:2209
+      switch (static_cast<SCEVTypes>(S->getSCEVType())) {
+      case scConstant:
+        return false;
----------------
sanjoy wrote:
> In a later change, maybe you can change this code to just do:
> 
> ```
> if (auto *SU = dyn_cast<SCEVUnknown>(S))
>   return checkUnknown(...);
> return true;
> ```
> 
> (there should be no need to return false on constants -- they have no operands and thus nothing to follow)
I keep this swich intentionally. If a new type o SCEV ever appears, we will have a warning here. Addressing this warning should motivate the author of new SCEV to pay attention to this situation and process this new node properly.


https://reviews.llvm.org/D33543