[PATCH] D111301: [VPlan] Make sure recurrence splice is not inserted between phis.

[Florian Hahn via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rGe3bfb6a14646: [VPlan] Make sure recurrence splice is not inserted between phis. (authored by fhahn).

Changed prior to commit:
  https://reviews.llvm.org/D111301?vs=382602&id=385536#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D111301/new/

https://reviews.llvm.org/D111301

Files:
  llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
  llvm/test/Transforms/LoopVectorize/induction.ll


Index: llvm/test/Transforms/LoopVectorize/induction.ll
===================================================================
--- llvm/test/Transforms/LoopVectorize/induction.ll
+++ llvm/test/Transforms/LoopVectorize/induction.ll
@@ -851,8 +851,10 @@
 }
 
 ; Ensure that the shuffle vector for first order recurrence is inserted
-; correctly after all the phis. These new phis correspond to new IVs 
-; that are generated by optimizing non-free truncs of IVs to IVs themselves 
+; correctly after all the phis. These new phis correspond to new IVs
+; that are generated by optimizing non-free truncs of IVs to IVs themselves.
+; This also ensures the first-order recurrence splice recipe is placed
+; correctly if it is fed by an induction.
 define i64 @trunc_with_first_order_recurrence() {
 ; CHECK-LABEL: trunc_with_first_order_recurrence
 ; CHECK-LABEL: vector.body:
Index: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -9489,16 +9489,20 @@
     if (!RecurPhi)
       continue;
 
+    VPRecipeBase *PrevRecipe = RecurPhi->getBackedgeRecipe();
+    VPBasicBlock *InsertBlock = PrevRecipe->getParent();
+    auto *Region = GetReplicateRegion(PrevRecipe);
+    if (Region)
+      InsertBlock = cast<VPBasicBlock>(Region->getSingleSuccessor());
+    if (Region || PrevRecipe->isPhi())
+      Builder.setInsertPoint(InsertBlock, InsertBlock->getFirstNonPhi());
+    else
+      Builder.setInsertPoint(InsertBlock, std::next(PrevRecipe->getIterator()));
+
     auto *RecurSplice = cast<VPInstruction>(
         Builder.createNaryOp(VPInstruction::FirstOrderRecurrenceSplice,
                              {RecurPhi, RecurPhi->getBackedgeValue()}));
 
-    VPRecipeBase *PrevRecipe = RecurPhi->getBackedgeRecipe();
-    if (auto *Region = GetReplicateRegion(PrevRecipe)) {
-      VPBasicBlock *Succ = cast<VPBasicBlock>(Region->getSingleSuccessor());
-      RecurSplice->moveBefore(*Succ, Succ->getFirstNonPhi());
-    } else
-      RecurSplice->moveAfter(PrevRecipe);
     RecurPhi->replaceAllUsesWith(RecurSplice);
     // Set the first operand of RecurSplice to RecurPhi again, after replacing
     // all users.


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