[llvm] [VPlan] Impl VPlan-based pattern match for ExtendedRed and MulAccRed (NFCI) (PR #113903)

[Alexey Bataev via llvm-commits]

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@@ -2702,6 +2785,212 @@ class VPReductionEVLRecipe : public VPReductionRecipe {
   }
 };
 
+/// A recipe to represent inloop extended reduction operations, performing a
+/// reduction on a extended vector operand into a scalar value, and adding the
+/// result to a chain. This recipe is abstract and needs to be lowered to
+/// concrete recipes before codegen. The Operands are {ChainOp, VecOp,
+/// [Condition]}.
+class VPExtendedReductionRecipe : public VPReductionRecipe {
+  /// Opcode of the extend recipe will be lowered to.
+  Instruction::CastOps ExtOp;
+  /// Debug location of reduction recipe will be lowered to.
+  DebugLoc RedDL;
+
+public:
+  VPExtendedReductionRecipe(const RecurrenceDescriptor &R, Instruction *RedI,
+                            VPValue *ChainOp, VPWidenCastRecipe *Ext,
+                            VPValue *CondOp, bool IsOrdered)
+      : VPReductionRecipe(VPDef::VPExtendedReductionSC, R,
+                          ArrayRef<VPValue *>({ChainOp, Ext->getOperand(0)}),
----------------
alexey-bataev wrote:

```suggestion
                          {ChainOp, Ext->getOperand(0)},
```
??

https://github.com/llvm/llvm-project/pull/113903