Avoid needless refcount operations in native storage delete

Author: msimacek

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/common/SequenceStorageNodes.java

@@ -3597,7 +3597,7 @@ static void doLastItem(Node inliningTarget, SequenceStorage s, @SuppressWarnings
             setLenNode.execute(inliningTarget, s, s.length() - 1);
         }
 
-        @Specialization(guards = "!isForeignSequenceStorage(s)")
+        @Specialization(guards = {"!isNativeObjectStorage(s)", "!isForeignSequenceStorage(s)"})
         static void doGeneric(Node inliningTarget, SequenceStorage s, int idx,
                         @Cached GetItemScalarNode getItemNode,
                         @Cached SetItemScalarNode setItemNode,
@@ -3610,6 +3610,21 @@ static void doGeneric(Node inliningTarget, SequenceStorage s, int idx,
             setLenNode.execute(inliningTarget, s, len - 1);
         }
 
+        @Specialization
+        static void doNativeObjectStorage(Node inliningTarget, NativeObjectSequenceStorage s, int idx,
+                        @Cached(inline = false) CStructAccess.ReadPointerNode readPointerNode,
+                        @Cached(inline = false) CStructAccess.WritePointerNode writePointerNode,
+                        @Cached CExtNodes.XDecRefPointerNode decRefNode) {
+            int len = s.length();
+            Object deleted = readPointerNode.readArrayElement(s.getPtr(), idx);
+            for (int i = idx; i < len - 1; i++) {
+                writePointerNode.writeArrayElement(s.getPtr(), i, readPointerNode.readArrayElement(s.getPtr(), i + 1));
+            }
+            writePointerNode.writeArrayElement(s.getPtr(), len - 1, 0L);
+            s.setNewLength(len - 1);
+            decRefNode.execute(inliningTarget, deleted);
+        }
+
         @Specialization
         static void doForeign(Node inliningTarget, ForeignSequenceStorage s, int idx,
                         @Cached ForeignSequenceStorage.RemoveNode removeNode) {

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/nodes/PGuards.java

@@ -113,6 +113,7 @@
 import com.oracle.graal.python.runtime.sequence.storage.ForeignSequenceStorage;
 import com.oracle.graal.python.runtime.sequence.storage.IntSequenceStorage;
 import com.oracle.graal.python.runtime.sequence.storage.LongSequenceStorage;
+import com.oracle.graal.python.runtime.sequence.storage.NativeObjectSequenceStorage;
 import com.oracle.graal.python.runtime.sequence.storage.ObjectSequenceStorage;
 import com.oracle.graal.python.runtime.sequence.storage.SequenceStorage;
 import com.oracle.graal.python.util.OverflowException;
@@ -297,6 +298,10 @@ public static boolean isForeignSequenceStorage(SequenceStorage sequenceStorage)
         return sequenceStorage instanceof ForeignSequenceStorage;
     }
 
+    public static boolean isNativeObjectStorage(SequenceStorage sequenceStorage) {
+        return sequenceStorage instanceof NativeObjectSequenceStorage;
+    }
+
     public static boolean isList(Object o) {
         return o instanceof PList;
     }