[llvm] [LV][EVL] Support interleaved access with tail folding by EVL (PR #152070)

[Luke Lau via llvm-commits]

================
@@ -2457,65 +2460,153 @@ class LLVM_ABI_FOR_TEST VPInterleaveRecipe : public VPRecipeBase {
       addOperand(Mask);
     }
   }
-  ~VPInterleaveRecipe() override = default;
 
-  VPInterleaveRecipe *clone() override {
-    return new VPInterleaveRecipe(IG, getAddr(), getStoredValues(), getMask(),
-                                  NeedsMaskForGaps, getDebugLoc());
+public:
+  VPInterleaveBase *clone() override {
+    llvm_unreachable("cloning not supported");
   }
 
-  VP_CLASSOF_IMPL(VPDef::VPInterleaveSC)
+  static inline bool classof(const VPRecipeBase *R) {
+    return R->getVPDefID() == VPRecipeBase::VPInterleaveSC ||
+           R->getVPDefID() == VPRecipeBase::VPInterleaveEVLSC;
+  }
+
+  static inline bool classof(const VPUser *U) {
+    auto *R = dyn_cast<VPRecipeBase>(U);
+    return R && classof(R);
+  }
 
   /// Return the address accessed by this recipe.
   VPValue *getAddr() const {
     return getOperand(0); // Address is the 1st, mandatory operand.
   }
 
+  /// Return true if the access needs a mask because of the gaps.
+  bool needsMaskForGaps() const { return NeedsMaskForGaps; }
+
   /// Return the mask used by this recipe. Note that a full mask is represented
   /// by a nullptr.
   VPValue *getMask() const {
-    // Mask is optional and therefore the last, currently 2nd operand.
+    // Mask is optional and the last operand.
     return HasMask ? getOperand(getNumOperands() - 1) : nullptr;
   }
 
+  const InterleaveGroup<Instruction> *getInterleaveGroup() { return IG; }
+
+  Instruction *getInsertPos() const { return IG->getInsertPos(); }
+
+  void execute(VPTransformState &State) override {
+    llvm_unreachable("VPInterleaveBase should not be instantiated.");
+  }
+
+  /// Return the cost of this VPInterleaveRecipe.
+  InstructionCost computeCost(ElementCount VF,
+                              VPCostContext &Ctx) const override;
+
+  /// Returns true if the recipe only uses the first lane of operand \p Op.
+  virtual bool onlyFirstLaneUsed(const VPValue *Op) const = 0;
----------------
lukel97 wrote:

I think this needs to be marked as overriden?
```suggestion
  virtual bool onlyFirstLaneUsed(const VPValue *Op) const override = 0;
```

https://github.com/llvm/llvm-project/pull/152070