Try Patryk27 fix

Author: tomtor

llvm/lib/Target/AVR/AVRISelLowering.cpp

@@ -1114,14 +1114,22 @@ bool AVRTargetLowering::getPostIndexedAddressParts(SDNode *N, SDNode *Op,
       if (AVR::isProgramMemoryAccess(LD))
         return false;
 
-    // FIXME: We temporarily apply a test which prevents generating incorrect
-    // code (see https://github.com/llvm/llvm-project/issues/143247 )
-    // until we determined and fixed the root cause.
-    if (Op->getOperand(0)->hasOneUse())
+    SDValue Ptr;
+    if (LoadSDNode *LD = dyn_cast<LoadSDNode>(N)) {
+      Ptr = LD->getBasePtr();
+    } else if (StoreSDNode *ST = dyn_cast<StoreSDNode>(N)) {
+      Ptr = ST->getBasePtr();
+    } else
       return false;
 
     Base = Op->getOperand(0);
     Offset = DAG.getConstant(RHSC, DL, MVT::i8);
+
+    // Post-indexing updates the base, so it's not a valid transform
+    // if that's not the same as the load's pointer.
+    if (Ptr != Base)
+      return false;
+
     AM = ISD::POST_INC;
 
     return true;