[llvm] [LV][VPlan] Use VF VPValue in VPVectorPointerRecipe (PR #110974)

[Florian Hahn via llvm-commits]

================
@@ -1813,38 +1813,59 @@ void VPWidenGEPRecipe::print(raw_ostream &O, const Twine &Indent,
 }
 #endif
 
+void VPReverseVectorPointerRecipe ::execute(VPTransformState &State) {
+  auto &Builder = State.Builder;
+  State.setDebugLocFrom(getDebugLoc());
+  unsigned CurrentPart = getUnrollPart(*this);
+  // Use i32 for the gep index type when the value is constant,
+  // or query DataLayout for a more suitable index type otherwise.
+  const DataLayout &DL = Builder.GetInsertBlock()->getDataLayout();
+  Type *IndexTy = State.VF.isScalable()
+                      ? DL.getIndexType(IndexedTy->getPointerTo())
+                      : Builder.getInt32Ty();
+  Value *Ptr = State.get(getOperand(0), VPLane(0));
+  bool InBounds = isInBounds();
+
+  // the wide store needs to start at the last vector element.
+  Value *RunTimeVF = State.get(getVFValue(), VPLane(0));
+  if (IndexTy != RunTimeVF->getType())
+    RunTimeVF = Builder.CreateZExtOrTrunc(RunTimeVF, IndexTy);
+  // NumElt = -CurrentPart * RunTimeVF
+  Value *NumElt = Builder.CreateMul(
+      ConstantInt::get(IndexTy, -(int64_t)CurrentPart), RunTimeVF);
+  // LastLane = 1 - RunTimeVF
+  Value *LastLane = Builder.CreateSub(ConstantInt::get(IndexTy, 1), RunTimeVF);
+  Value *ResultPtr = Builder.CreateGEP(IndexedTy, Ptr, NumElt, "", InBounds);
+  ResultPtr = Builder.CreateGEP(IndexedTy, ResultPtr, LastLane, "", InBounds);
+
+  State.set(this, ResultPtr, /*IsScalar*/ true);
+}
+
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+void VPReverseVectorPointerRecipe::print(raw_ostream &O, const Twine &Indent,
+                                         VPSlotTracker &SlotTracker) const {
+  O << Indent;
+  printAsOperand(O, SlotTracker);
+  O << " = reverse-vector-pointer ";
+  printOperands(O, SlotTracker);
+}
+#endif
+
 void VPVectorPointerRecipe ::execute(VPTransformState &State) {
   auto &Builder = State.Builder;
   State.setDebugLocFrom(getDebugLoc());
   unsigned CurrentPart = getUnrollPart(*this);
   // Use i32 for the gep index type when the value is constant,
   // or query DataLayout for a more suitable index type otherwise.
   const DataLayout &DL = Builder.GetInsertBlock()->getDataLayout();
-  Type *IndexTy = State.VF.isScalable() && (IsReverse || CurrentPart > 0)
+  Type *IndexTy = State.VF.isScalable() && (CurrentPart > 0)
----------------
fhahn wrote:

```suggestion
  Type *IndexTy = State.VF.isScalable() && CurrentPart > 0
```

https://github.com/llvm/llvm-project/pull/110974