Make PCells more lightweight.

(cherry picked from commit 6eefbd8)

Author: fangerer

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/cell/PCell.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2019, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * The Universal Permissive License (UPL), Version 1.0
@@ -40,24 +40,16 @@
  */
 package com.oracle.graal.python.builtins.objects.cell;
 
-import java.util.ArrayList;
-import java.util.List;
-
-import com.oracle.graal.python.builtins.PythonBuiltinClassType;
-import com.oracle.graal.python.builtins.objects.object.PythonBuiltinObject;
+import com.oracle.graal.python.builtins.objects.PythonAbstractObject;
 import com.oracle.truffle.api.Assumption;
 import com.oracle.truffle.api.CompilerAsserts;
-import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
+import com.oracle.truffle.api.CompilerDirectives;
 import com.oracle.truffle.api.Truffle;
 
-public class PCell extends PythonBuiltinObject {
-    private final Assumption effectivelyFinal = Truffle.getRuntime().createAssumption("cell is effectively final");
+public final class PCell extends PythonAbstractObject {
+    private Assumption effectivelyFinal;
     private Object ref;
 
-    public PCell() {
-        super(PythonBuiltinClassType.PCell);
-    }
-
     public Object getRef() {
         return ref;
     }
@@ -67,7 +59,7 @@ public void clearRef() {
     }
 
     public void setRef(Object ref) {
-        if (effectivelyFinal.isValid()) {
+        if (effectivelyFinal != null && effectivelyFinal.isValid()) {
             if (this.ref != null) {
                 effectivelyFinal.invalidate();
             }
@@ -76,17 +68,13 @@ public void setRef(Object ref) {
     }
 
     public Assumption isEffectivelyFinalAssumption() {
+        CompilerAsserts.neverPartOfCompilation();
+        if (effectivelyFinal == null) {
+            effectivelyFinal = Truffle.getRuntime().createAssumption("cell is effectively final");
+        }
         return effectivelyFinal;
     }
 
-    @Override
-    @TruffleBoundary
-    public List<String> getAttributeNames() {
-        ArrayList<String> arrayList = new ArrayList<>();
-        arrayList.add("cell_contents");
-        return arrayList;
-    }
-
     @Override
     public String toString() {
         CompilerAsserts.neverPartOfCompilation();
@@ -95,4 +83,10 @@ public String toString() {
         }
         return String.format("<cell at %s: %s object at %s>", hashCode(), ref.getClass().getSimpleName(), ref.hashCode());
     }
+
+    @Override
+    public int compareTo(Object o) {
+        CompilerDirectives.transferToInterpreter();
+        throw new UnsupportedOperationException();
+    }
 }

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/nodes/cell/WriteLocalCellNode.java

@@ -33,11 +33,14 @@
 import com.oracle.graal.python.nodes.frame.WriteIdentifierNode;
 import com.oracle.graal.python.nodes.statement.StatementNode;
 import com.oracle.truffle.api.CompilerDirectives;
+import com.oracle.truffle.api.dsl.Cached;
 import com.oracle.truffle.api.dsl.NodeChild;
 import com.oracle.truffle.api.dsl.Specialization;
 import com.oracle.truffle.api.frame.FrameSlot;
 import com.oracle.truffle.api.frame.VirtualFrame;
+import com.oracle.truffle.api.nodes.Node;
 import com.oracle.truffle.api.nodes.NodeInfo;
+import com.oracle.truffle.api.profiles.ConditionProfile;
 
 @NodeInfo(shortName = "write_cell")
 @NodeChild(value = "rhs", type = ExpressionNode.class)
@@ -63,15 +66,12 @@ public void doWrite(VirtualFrame frame, Object value) {
     public abstract void executeWithValue(VirtualFrame frame, Object value);
 
     @Specialization
-    void writeObject(VirtualFrame frame, Object value) {
+    void writeObject(VirtualFrame frame, Object value,
+                    @Cached WriteToCellNode writeToCellNode,
+                    @Cached("createBinaryProfile()") ConditionProfile profile) {
         Object localValue = readLocal.execute(frame);
-        if (localValue instanceof PCell) {
-            PCell cell = (PCell) localValue;
-            if (value == NO_VALUE) {
-                cell.clearRef();
-            } else {
-                cell.setRef(value);
-            }
+        if (profile.profile(localValue instanceof PCell)) {
+            writeToCellNode.execute((PCell) localValue, value);
             return;
         }
         CompilerDirectives.transferToInterpreter();
@@ -82,4 +82,24 @@ void writeObject(VirtualFrame frame, Object value) {
     public Object getIdentifier() {
         return frameSlot.getIdentifier();
     }
+
+    abstract static class WriteToCellNode extends Node {
+
+        public abstract void execute(PCell cell, Object value);
+
+        @Specialization(guards = "cell == cachedCell", limit = "1")
+        void doWriteCached(@SuppressWarnings("unused") PCell cell, Object value,
+                        @Cached("cell") PCell cachedCell) {
+            doWriteGeneric(cachedCell, value);
+        }
+
+        @Specialization(replaces = "doWriteCached")
+        void doWriteGeneric(PCell cell, Object value) {
+            if (value == NO_VALUE) {
+                cell.clearRef();
+            } else {
+                cell.setRef(value);
+            }
+        }
+    }
 }

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/nodes/object/GetClassNode.java

@@ -45,6 +45,7 @@
 import com.oracle.graal.python.builtins.objects.PEllipsis;
 import com.oracle.graal.python.builtins.objects.PNone;
 import com.oracle.graal.python.builtins.objects.PNotImplemented;
+import com.oracle.graal.python.builtins.objects.cell.PCell;
 import com.oracle.graal.python.builtins.objects.cext.CExtNodes.GetNativeClassNode;
 import com.oracle.graal.python.builtins.objects.cext.PythonAbstractNativeObject;
 import com.oracle.graal.python.builtins.objects.cext.PythonNativeVoidPtr;
@@ -113,6 +114,17 @@ protected PythonBuiltinClass getIt(@SuppressWarnings("unused") GetSetDescriptor
             return contextRef.get().getCore().lookupType(PythonBuiltinClassType.GetSetDescriptor);
         }
 
+        @Specialization(assumptions = "singleContextAssumption()")
+        protected PythonBuiltinClass getIt(@SuppressWarnings("unused") PCell object,
+                        @Cached("getIt(object)") PythonBuiltinClass klass) {
+            return klass;
+        }
+
+        @Specialization
+        protected PythonBuiltinClass getIt(@SuppressWarnings("unused") PCell object) {
+            return contextRef.get().getCore().lookupType(PythonBuiltinClassType.PCell);
+        }
+
         @Specialization(assumptions = "singleContextAssumption()")
         protected PythonBuiltinClass getIt(@SuppressWarnings("unused") PNone object,
                         @Cached("getIt(object)") PythonBuiltinClass klass) {

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/nodes/object/GetLazyClassNode.java

@@ -44,6 +44,7 @@
 import com.oracle.graal.python.builtins.objects.PEllipsis;
 import com.oracle.graal.python.builtins.objects.PNone;
 import com.oracle.graal.python.builtins.objects.PNotImplemented;
+import com.oracle.graal.python.builtins.objects.cell.PCell;
 import com.oracle.graal.python.builtins.objects.cext.CExtNodes.GetNativeClassNode;
 import com.oracle.graal.python.builtins.objects.cext.PythonAbstractNativeObject;
 import com.oracle.graal.python.builtins.objects.cext.PythonNativeObject;
@@ -128,6 +129,11 @@ protected static LazyPythonClass getIt(@SuppressWarnings("unused") GetSetDescrip
             return PythonBuiltinClassType.GetSetDescriptor;
         }
 
+        @Specialization
+        protected static LazyPythonClass getIt(@SuppressWarnings("unused") PCell object) {
+            return PythonBuiltinClassType.PCell;
+        }
+
         @Specialization
         protected static LazyPythonClass getIt(@SuppressWarnings("unused") PNone object) {
             return PythonBuiltinClassType.PNone;