[llvm] [VPlan] Use SCEV to prove non-aliasing for stores at different offsets. (PR #170347)

[Florian Hahn via llvm-commits]

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@@ -165,6 +204,15 @@ static bool canHoistOrSinkWithNoAliasCheck(
       if (!R.mayWriteToMemory() && !(CheckReads && R.mayReadFromMemory()))
         continue;
 
+      // For stores, check if we can use SCEV to prove no-alias with the group
+      // leader (all members of the group write to the same address with the
+      // same size).
+      if (auto *Store = dyn_cast<VPReplicateRecipe>(&R)) {
+        if (GroupLeader &&
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fhahn wrote:

I am not sure re-ordering makes things safer, as they are still all default arguments and it still relies on the caller either passing nullptr for all or non of them. I added a dedicated helper class to encapsulate the extra functionality, to make this safer.

https://github.com/llvm/llvm-project/pull/170347