Fix DebugEvaluate for generators.

R=mstarzinger@chromium.org
BUG=v8:3225
LOG=N

Review URL: https://codereview.chromium.org/207153004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20195 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/runtime.cc

@@ -11409,6 +11409,14 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_GetFrameDetails) {
 }
 
 
+static bool ParameterIsShadowedByContextLocal(Handle<ScopeInfo> info,
+                                              int index) {
+  VariableMode mode;
+  InitializationFlag flag;
+  return info->ContextSlotIndex(info->ParameterName(index), &mode, &flag) != -1;
+}
+
+
 // Create a plain JSObject which materializes the local scope for the specified
 // frame.
 static Handle<JSObject> MaterializeStackLocalsWithFrameInspector(
@@ -11421,17 +11429,16 @@ static Handle<JSObject> MaterializeStackLocalsWithFrameInspector(
 
   // First fill all parameters.
   for (int i = 0; i < scope_info->ParameterCount(); ++i) {
-    Handle<String> name(scope_info->ParameterName(i));
-    VariableMode mode;
-    InitializationFlag init_flag;
     // Do not materialize the parameter if it is shadowed by a context local.
-    if (scope_info->ContextSlotIndex(*name, &mode, &init_flag) != -1) continue;
+    if (ParameterIsShadowedByContextLocal(scope_info, i)) continue;
 
+    HandleScope scope(isolate);
     Handle<Object> value(i < frame_inspector->GetParametersCount()
                              ? frame_inspector->GetParameter(i)
                              : isolate->heap()->undefined_value(),
                          isolate);
     ASSERT(!value->IsTheHole());
+    Handle<String> name(scope_info->ParameterName(i));
 
     RETURN_IF_EMPTY_HANDLE_VALUE(
         isolate,
@@ -11472,10 +11479,13 @@ static void UpdateStackLocalsFromMaterializedObject(Isolate* isolate,
 
   // Parameters.
   for (int i = 0; i < scope_info->ParameterCount(); ++i) {
+    // Shadowed parameters were not materialized.
+    if (ParameterIsShadowedByContextLocal(scope_info, i)) continue;
+
     ASSERT(!frame->GetParameter(i)->IsTheHole());
     HandleScope scope(isolate);
-    Handle<Object> value = GetProperty(
-        isolate, target, Handle<String>(scope_info->ParameterName(i)));
+    Handle<String> name(scope_info->ParameterName(i));
+    Handle<Object> value = GetProperty(isolate, target, name);
     frame->SetParameterValue(i, *value);
   }
 

test/mjsunit/regress-3225.js

+// Copyright 2014 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --expose-debug-as debug  --harmony-generators
+
+Debug = debug.Debug
+
+var debug_step = 0;
+var failure = null;
+
+function listener(event, exec_state, event_data, data) {
+  if (event != Debug.DebugEvent.Break) return;
+  try {
+    if (debug_step == 0) {
+      assertEquals(1, exec_state.frame(0).evaluate('a').value());
+      assertEquals(3, exec_state.frame(0).evaluate('b').value());
+      exec_state.frame(0).evaluate("a = 4").value();
+      debug_step++;
+    } else {
+      assertEquals(4, exec_state.frame(0).evaluate('a').value());
+      assertEquals(3, exec_state.frame(0).evaluate('b').value());
+      exec_state.frame(0).evaluate("b = 5").value();
+    }
+  } catch (e) {
+    failure = e;
+  }
+}
+
+Debug.setListener(listener);
+
+function* generator(a, b) {
+  var b = 3;  // Shadows a parameter.
+  debugger;
+  yield a;
+  yield b;
+  debugger;
+  return b;
+}
+
+var foo = generator(1, 2);
+
+assertEquals(4, foo.next().value);
+assertEquals(3, foo.next().value);
+assertEquals(5, foo.next().value);
+assertNull(failure);
+
+Debug.setListener(null);