[llvm] [VPlan] Split VPWidenMemoryInstructionRecipe (NFCI). (PR #87411)

[via llvm-commits]

================
@@ -9535,7 +9464,68 @@ void VPWidenMemoryInstructionRecipe::execute(VPTransformState &State) {
         NewLI = Builder.CreateVectorReverse(NewLI, "reverse");
     }
 
-    State.set(getVPSingleValue(), NewLI, Part);
+    State.set(this, NewLI, Part);
+  }
+}
+
+void VPWidenStoreRecipe::execute(VPTransformState &State) {
+  auto *SI = cast<StoreInst>(&Ingredient);
+
+  VPValue *StoredValue = getStoredValue();
+  bool CreateScatter = !isConsecutive();
+  const Align Alignment = getLoadStoreAlignment(&Ingredient);
+
+  auto &Builder = State.Builder;
+  State.setDebugLocFrom(getDebugLoc());
+
+  for (unsigned Part = 0; Part < State.UF; ++Part) {
+    Instruction *NewSI = nullptr;
+    Value *Mask = nullptr;
+    if (auto *VPMask = getMask()) {
+      // Mask reversal is only needed for non-all-one (null) masks, as reverse
+      // of a null all-one mask is a null mask.
+      Mask = State.get(VPMask, Part);
+      if (isReverse())
+        Mask = Builder.CreateVectorReverse(Mask, "reverse");
+    }
+
+    Value *StoredVal = State.get(StoredValue, Part);
----------------
ayalz wrote:

```suggestion
    Value *StoredVal = State.get(StoredValue, Part);
    if (isReverse()) {
      // If we store to reverse consecutive memory locations, then we need
      // to reverse the order of elements in the stored value.
      StoredVal = Builder.CreateVectorReverse(StoredVal, "reverse");
      // We don't want to update the value in the map as it might be used in
      // another expression. So don't call resetVectorValue(StoredVal).
    }
```

https://github.com/llvm/llvm-project/pull/87411