Delete arguments of generators after the prolog

Author: steve-s

graalpython/com.oracle.graal.python.test/src/tests/unittest_tags_bytecode_dsl/test_contextlib.txt

@@ -84,3 +84,4 @@ test.test_contextlib.TestSuppress.test_no_args @ linux-x86_64
 test.test_contextlib.TestSuppress.test_no_exception @ linux-x86_64
 test.test_contextlib.TestSuppress.test_no_result_from_enter @ linux-x86_64
 test.test_contextlib.TestSuppress.test_other_exception @ linux-x86_64
+test_contextlib.txt:test.test_contextlib.ContextManagerTestCase.test_nokeepref @ linux-x86_64

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/compiler/bytecode_dsl/RootNodeCompiler.java

@@ -1652,9 +1652,13 @@ private void copyArguments(ArgumentsTy args, Builder b) {
             BytecodeLocal local = getLocal(args.kwArg.arg);
             assert local != null;
             b.beginStoreLocal(local);
-            b.emitLoadKeywordArguments(idx);
+            b.emitLoadKeywordArguments(idx++);
             b.endStoreLocal();
         }
+
+        if (scope.isCoroutine() || scope.isGenerator()) {
+            b.emitClearArguments(idx);
+        }
     }
 
     /* ---------------- StatementCompiler -------------------- */

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/nodes/bytecode_dsl/PBytecodeDSLRootNode.java

@@ -1204,6 +1204,19 @@ public static void perform(VirtualFrame frame, LocalRangeAccessor locals,
         }
     }
 
+    @Operation(storeBytecodeIndex = false)
+    @ConstantOperand(type = int.class)
+    public static final class ClearArguments {
+        @Specialization
+        @ExplodeLoop
+        public static void perform(VirtualFrame frame, int count,
+                        @Bind BytecodeNode bytecodeNode) {
+            for (int i = 0; i < count; i++) {
+                PArguments.setArgument(frame.getArguments(), i, null);
+            }
+        }
+    }
+
     @Operation(storeBytecodeIndex = false)
     @ConstantOperand(type = int.class)
     public static final class LoadVariableArguments {