Store OSR frame in a Pair with previous value

Author: msimacek

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/function/PArguments.java

@@ -31,7 +31,6 @@
 import com.oracle.graal.python.runtime.PythonOptions;
 import com.oracle.graal.python.runtime.exception.PException;
 import com.oracle.graal.python.util.PythonUtils;
-import com.oracle.truffle.api.CompilerAsserts;
 import com.oracle.truffle.api.exception.AbstractTruffleException;
 import com.oracle.truffle.api.frame.Frame;
 import com.oracle.truffle.api.frame.MaterializedFrame;
@@ -42,7 +41,7 @@
  * The layout of an argument array for a Python frame.
  *
  *                                         +-------------------+
- * INDEX_VARIABLE_ARGUMENTS             -> | Object[]          |  This slot is also used to pass parent frame reference in bytecode OSR compilation.
+ * INDEX_VARIABLE_ARGUMENTS             -> | Object[]          |
  *                                         +-------------------+
  * INDEX_KEYWORD_ARGUMENTS              -> | PKeyword[]        |
  *                                         +-------------------+
@@ -244,19 +243,6 @@ public static PCell[] getClosure(Object[] arguments) {
         return (PCell[]) arguments[INDEX_CLOSURE];
     }
 
-    /*
-     * We repurpose the varargs slot for storing the OSR frame. In the bytecode interpreter, varargs
-     * should only be read once at the beginning of execute which is before OSR.
-     */
-    public static void setOSRFrame(Object[] arguments, VirtualFrame parentFrame) {
-        CompilerAsserts.neverPartOfCompilation();
-        arguments[INDEX_VARIABLE_ARGUMENTS] = parentFrame;
-    }
-
-    public static Frame getOSRFrame(Object[] arguments) {
-        return (Frame) arguments[INDEX_VARIABLE_ARGUMENTS];
-    }
-
     public static PCell[] getClosure(Frame frame) {
         return getClosure(frame.getArguments());
     }

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/nodes/bytecode/PBytecodeRootNode.java

@@ -57,6 +57,8 @@
 import java.util.Set;
 import java.util.concurrent.locks.Lock;
 
+import org.graalvm.collections.Pair;
+
 import com.oracle.graal.python.PythonLanguage;
 import com.oracle.graal.python.builtins.PythonBuiltinClassType;
 import com.oracle.graal.python.builtins.modules.BuiltinFunctions.FormatNode;
@@ -176,9 +178,9 @@
 import com.oracle.graal.python.nodes.builtins.ListNodesFactory;
 import com.oracle.graal.python.nodes.builtins.TupleNodes;
 import com.oracle.graal.python.nodes.builtins.TupleNodesFactory;
+import com.oracle.graal.python.nodes.bytecode.PBytecodeRootNodeFactory.ObjHashMapPutNodeGen;
 import com.oracle.graal.python.nodes.bytecode.SequenceFromStackNode.ListFromStackNode;
 import com.oracle.graal.python.nodes.bytecode.SequenceFromStackNode.TupleFromStackNode;
-import com.oracle.graal.python.nodes.bytecode.PBytecodeRootNodeFactory.ObjHashMapPutNodeGen;
 import com.oracle.graal.python.nodes.bytecode.SequenceFromStackNodeFactory.ListFromStackNodeGen;
 import com.oracle.graal.python.nodes.bytecode.SequenceFromStackNodeFactory.TupleFromStackNodeGen;
 import com.oracle.graal.python.nodes.bytecode.instrumentation.InstrumentationRoot;
@@ -1100,16 +1102,22 @@ public Object execute(VirtualFrame virtualFrame) {
         }
     }
 
+    // Doesn't matter which PArguments slot we use as long as it exists
+    private static final int OSR_FRAME_INDEX = 0;
+
     @Override
     public Object[] storeParentFrameInArguments(VirtualFrame parentFrame) {
         Object[] arguments = parentFrame.getArguments();
-        PArguments.setOSRFrame(arguments, parentFrame);
+        arguments[0] = Pair.create(arguments[OSR_FRAME_INDEX], parentFrame);
         return arguments;
     }
 
     @Override
+    @SuppressWarnings("unchecked")
     public Frame restoreParentFrameFromArguments(Object[] arguments) {
-        return PArguments.getOSRFrame(arguments);
+        Pair<Object, Frame> pair = (Pair<Object, Frame>) arguments[OSR_FRAME_INDEX];
+        arguments[0] = pair.getLeft();
+        return pair.getRight();
     }
 
     @Override