[llvm] [VPlan] Extract reverse operation for reverse accesses (PR #146525)

[Luke Lau via llvm-commits]

================
@@ -7754,14 +7754,30 @@ VPRecipeBuilder::tryToWidenMemory(Instruction *I, ArrayRef<VPValue *> Operands,
     Builder.insert(VectorPtr);
     Ptr = VectorPtr;
   }
-  if (LoadInst *Load = dyn_cast<LoadInst>(I))
-    return new VPWidenLoadRecipe(*Load, Ptr, Mask, Consecutive, Reverse,
-                                 VPIRMetadata(*Load, LVer), I->getDebugLoc());
 
-  StoreInst *Store = cast<StoreInst>(I);
-  return new VPWidenStoreRecipe(*Store, Ptr, Operands[0], Mask, Consecutive,
+  if (auto *Load = dyn_cast<LoadInst>(I)) {
+    auto *LoadR =
+        new VPWidenLoadRecipe(*Load, Ptr, Mask, Consecutive, Reverse,
+                              VPIRMetadata(*Load, LVer), Load->getDebugLoc());
+    if (Reverse) {
+      Builder.insert(LoadR);
+      return new VPInstruction(VPInstruction::Reverse, {LoadR},
+                               LoadR->getDebugLoc());
+    }
+    return LoadR;
+  }
+
+  auto *Store = cast<StoreInst>(I);
+  VPValue *StoredVal = Operands[0];
+  if (Reverse) {
+    auto *ReverseR = new VPInstruction(VPInstruction::Reverse, {StoredVal},
+                                       Store->getDebugLoc());
+    Builder.insert(ReverseR);
----------------
lukel97 wrote:

```suggestion
    StoredVal = Builder.createNaryOp(VPInstruction::Reverse, StoredVal, Store->getDebugLoc());
```

https://github.com/llvm/llvm-project/pull/146525