[llvm] [VPlan] Model FOR extract of exit value in VPlan. (PR #93395)

[via llvm-commits]

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@@ -831,18 +833,28 @@ bool VPlanTransforms::adjustFixedOrderRecurrences(VPlan &Plan,
     // fixed-order recurrence.
     VPBasicBlock *InsertBlock = Previous->getParent();
     if (isa<VPHeaderPHIRecipe>(Previous))
-      Builder.setInsertPoint(InsertBlock, InsertBlock->getFirstNonPhi());
+      LoopBuilder.setInsertPoint(InsertBlock, InsertBlock->getFirstNonPhi());
     else
-      Builder.setInsertPoint(InsertBlock, std::next(Previous->getIterator()));
+      LoopBuilder.setInsertPoint(InsertBlock,
+                                 std::next(Previous->getIterator()));
 
     auto *RecurSplice = cast<VPInstruction>(
-        Builder.createNaryOp(VPInstruction::FirstOrderRecurrenceSplice,
-                             {FOR, FOR->getBackedgeValue()}));
+        LoopBuilder.createNaryOp(VPInstruction::FirstOrderRecurrenceSplice,
+                                 {FOR, FOR->getBackedgeValue()}));
 
     FOR->replaceAllUsesWith(RecurSplice);
     // Set the first operand of RecurSplice to FOR again, after replacing
     // all users.
     RecurSplice->setOperand(0, FOR);
+
+    Type *IntTy = Plan.getCanonicalIV()->getScalarType();
+    auto *Result = cast<VPInstruction>(MiddleBuilder.createNaryOp(
+        VPInstruction::ExtractFromEnd,
+        {FOR->getBackedgeValue(),
+         Plan.getOrAddLiveIn(ConstantInt::get(IntTy, 2))},
+        {}, "vector.recur.extract.for.phi"));
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ayalz wrote:

ok, this is the unique Name assigned to this VPInstruction instance.

https://github.com/llvm/llvm-project/pull/93395