[llvm] [AArch64][SelectionDAG] Add CodeGen support for scalar FEAT_CPA (PR #105669)

[Alexander Richardson via llvm-commits]

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@@ -8061,10 +8062,20 @@ SDValue SelectionDAG::getMemBasePlusOffset(SDValue Base, TypeSize Offset,
 
 SDValue SelectionDAG::getMemBasePlusOffset(SDValue Ptr, SDValue Offset,
                                            const SDLoc &DL,
-                                           const SDNodeFlags Flags) {
+                                           const SDNodeFlags Flags,
+                                           const bool Inverted) {
   assert(Offset.getValueType().isInteger());
   EVT BasePtrVT = Ptr.getValueType();
-  return getNode(ISD::ADD, DL, BasePtrVT, Ptr, Offset, Flags);
+  if (!this->getTarget().shouldPreservePtrArith(
+          this->getMachineFunction().getFunction())) {
+    return getNode(ISD::ADD, DL, BasePtrVT, Ptr, Offset, Flags);
+  } else {
+    if (Inverted) {
+      return getNode(ISD::PTRADD, DL, BasePtrVT, Offset, Ptr, Flags);
+    } else {
+      return getNode(ISD::PTRADD, DL, BasePtrVT, Ptr, Offset, Flags);
+    }
----------------
arichardson wrote:

```suggestion
    return getNode(ISD::PTRADD, DL, BasePtrVT, Ptr, Offset, Flags);
```

https://github.com/llvm/llvm-project/pull/105669