From 27ef7b7b37255a9965fe31fb7597720f57ed5154 Mon Sep 17 00:00:00 2001
From: Aaron Kennedy <aaron.kennedy@nokia.com>
Date: Wed, 5 Oct 2011 13:01:30 +1000
Subject: [PATCH 04/11] Introduce a QML compilation mode

In QML mode, there is a second global object - known as the QML
global object.  During property resolution, if a property is not
present on the JS global object, it is resolve on the QML global
object.

This global object behavior is only enabled if a script is being
compiled in QML mode.  The object to use as the QML global object
is passed as a parameter to the Script::Run() method.  Any function
closures etc. created during the run will retain a reference to this
object, so different objects can be passed in different script
runs.
---
 include/v8.h                     |   19 ++++++++--
 src/api.cc                       |   52 ++++++++++++++++++++++++-----
 src/arm/code-stubs-arm.cc        |    4 ++
 src/arm/full-codegen-arm.cc      |   28 +++++++++-------
 src/arm/lithium-arm.cc           |    2 +-
 src/arm/lithium-arm.h            |    6 +++-
 src/arm/lithium-codegen-arm.cc   |    7 ++--
 src/arm/macro-assembler-arm.h    |    5 +++
 src/ast-inl.h                    |    5 +++
 src/ast.h                        |    1 +
 src/code-stubs.h                 |    2 +-
 src/compiler.cc                  |   15 +++++++-
 src/compiler.h                   |   16 +++++++--
 src/contexts.cc                  |   35 +++++++++++++++++++
 src/contexts.h                   |    4 ++
 src/execution.cc                 |   31 ++++++++++++++---
 src/execution.h                  |    8 ++++
 src/full-codegen.cc              |    3 +-
 src/full-codegen.h               |    1 +
 src/heap.cc                      |    4 ++
 src/hydrogen-instructions.h      |    8 ++++-
 src/hydrogen.cc                  |    2 +
 src/ia32/code-stubs-ia32.cc      |    5 +++
 src/ia32/full-codegen-ia32.cc    |   28 +++++++++-------
 src/ia32/lithium-codegen-ia32.cc |    7 ++--
 src/ia32/lithium-ia32.cc         |    2 +-
 src/ia32/lithium-ia32.h          |    6 +++-
 src/ia32/macro-assembler-ia32.h  |    3 ++
 src/objects-inl.h                |    2 +
 src/objects.h                    |    4 ++
 src/parser.cc                    |   27 +++++++++++++--
 src/parser.h                     |    4 ++-
 src/prettyprinter.cc             |    3 ++
 src/runtime.cc                   |   68 +++++++++++++++++++++++++-------------
 src/runtime.h                    |    8 ++--
 src/scopes.cc                    |   61 ++++++++++++++++++++++++++++++++++
 src/scopes.h                     |    8 ++++
 src/variables.cc                 |    3 +-
 src/variables.h                  |    5 +++
 src/x64/code-stubs-x64.cc        |    4 ++
 src/x64/full-codegen-x64.cc      |   28 +++++++++-------
 src/x64/lithium-codegen-x64.cc   |    7 ++--
 src/x64/lithium-x64.cc           |    2 +-
 src/x64/lithium-x64.h            |    6 +++
 src/x64/macro-assembler-x64.h    |    5 +++
 45 files changed, 445 insertions(+), 109 deletions(-)

diff --git a/include/v8.h b/include/v8.h
index 3ef4dd6..193e2fe 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -587,6 +587,11 @@ class ScriptOrigin {
  */
 class V8EXPORT Script {
  public:
+  enum CompileFlags {
+      Default = 0x00,
+      QmlMode = 0x01
+  };
+
   /**
    * Compiles the specified script (context-independent).
    *
@@ -605,7 +610,8 @@ class V8EXPORT Script {
   static Local<Script> New(Handle<String> source,
                            ScriptOrigin* origin = NULL,
                            ScriptData* pre_data = NULL,
-                           Handle<String> script_data = Handle<String>());
+                           Handle<String> script_data = Handle<String>(),
+                           CompileFlags = Default);
 
   /**
    * Compiles the specified script using the specified file name
@@ -618,7 +624,8 @@ class V8EXPORT Script {
    *   will use the currently entered context).
    */
   static Local<Script> New(Handle<String> source,
-                           Handle<Value> file_name);
+                           Handle<Value> file_name,
+                           CompileFlags = Default);
 
   /**
    * Compiles the specified script (bound to current context).
@@ -639,7 +646,8 @@ class V8EXPORT Script {
   static Local<Script> Compile(Handle<String> source,
                                ScriptOrigin* origin = NULL,
                                ScriptData* pre_data = NULL,
-                               Handle<String> script_data = Handle<String>());
+                               Handle<String> script_data = Handle<String>(),
+                               CompileFlags = Default);
 
   /**
    * Compiles the specified script using the specified file name
@@ -656,7 +664,8 @@ class V8EXPORT Script {
    */
   static Local<Script> Compile(Handle<String> source,
                                Handle<Value> file_name,
-                               Handle<String> script_data = Handle<String>());
+                               Handle<String> script_data = Handle<String>(),
+                               CompileFlags = Default);
 
   /**
    * Runs the script returning the resulting value.  If the script is
@@ -666,6 +675,7 @@ class V8EXPORT Script {
    * compiled.
    */
   Local<Value> Run();
+  Local<Value> Run(Handle<Object> qml);
 
   /**
    * Returns the script id value.
@@ -3506,6 +3516,7 @@ class V8EXPORT Context {
    * JavaScript frames an empty handle is returned.
    */
   static Local<Context> GetCalling();
+  static Local<Object> GetCallingQmlGlobal();
 
   /**
    * Sets the security token for the context.  To access an object in
diff --git a/src/api.cc b/src/api.cc
index 85f0d4b..fd718c8 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -1514,7 +1514,8 @@ ScriptData* ScriptData::New(const char* data, int length) {
 Local<Script> Script::New(v8::Handle<String> source,
                           v8::ScriptOrigin* origin,
                           v8::ScriptData* pre_data,
-                          v8::Handle<String> script_data) {
+                          v8::Handle<String> script_data,
+                          v8::Script::CompileFlags compile_flags) {
   i::Isolate* isolate = i::Isolate::Current();
   ON_BAILOUT(isolate, "v8::Script::New()", return Local<Script>());
   LOG_API(isolate, "Script::New");
@@ -1551,7 +1552,8 @@ Local<Script> Script::New(v8::Handle<String> source,
                            NULL,
                            pre_data_impl,
                            Utils::OpenHandle(*script_data),
-                           i::NOT_NATIVES_CODE);
+                           i::NOT_NATIVES_CODE,
+                           compile_flags);
   has_pending_exception = result.is_null();
   EXCEPTION_BAILOUT_CHECK(isolate, Local<Script>());
   return Local<Script>(ToApi<Script>(result));
@@ -1559,21 +1561,23 @@ Local<Script> Script::New(v8::Handle<String> source,
 
 
 Local<Script> Script::New(v8::Handle<String> source,
-                          v8::Handle<Value> file_name) {
+                          v8::Handle<Value> file_name,
+                          v8::Script::CompileFlags compile_flags) {
   ScriptOrigin origin(file_name);
-  return New(source, &origin);
+  return New(source, &origin, 0, Handle<String>(), compile_flags);
 }
 
 
 Local<Script> Script::Compile(v8::Handle<String> source,
                               v8::ScriptOrigin* origin,
                               v8::ScriptData* pre_data,
-                              v8::Handle<String> script_data) {
+                              v8::Handle<String> script_data,
+                              v8::Script::CompileFlags compile_flags) {
   i::Isolate* isolate = i::Isolate::Current();
   ON_BAILOUT(isolate, "v8::Script::Compile()", return Local<Script>());
   LOG_API(isolate, "Script::Compile");
   ENTER_V8(isolate);
-  Local<Script> generic = New(source, origin, pre_data, script_data);
+  Local<Script> generic = New(source, origin, pre_data, script_data, compile_flags);
   if (generic.IsEmpty())
     return generic;
   i::Handle<i::Object> obj = Utils::OpenHandle(*generic);
@@ -1589,13 +1593,18 @@ Local<Script> Script::Compile(v8::Handle<String> source,
 
 Local<Script> Script::Compile(v8::Handle<String> source,
                               v8::Handle<Value> file_name,
-                              v8::Handle<String> script_data) {
+                              v8::Handle<String> script_data,
+                              v8::Script::CompileFlags compile_flags) {
   ScriptOrigin origin(file_name);
-  return Compile(source, &origin, 0, script_data);
+  return Compile(source, &origin, 0, script_data, compile_flags);
 }
 
 
 Local<Value> Script::Run() {
+    return Run(Handle<Object>());
+}
+
+Local<Value> Script::Run(Handle<Object> qml) {
   i::Isolate* isolate = i::Isolate::Current();
   ON_BAILOUT(isolate, "v8::Script::Run()", return Local<Value>());
   LOG_API(isolate, "Script::Run");
@@ -1614,10 +1623,11 @@ Local<Value> Script::Run() {
       fun = i::Handle<i::JSFunction>(i::JSFunction::cast(*obj), isolate);
     }
     EXCEPTION_PREAMBLE(isolate);
+    i::Handle<i::Object> qmlglobal = Utils::OpenHandle(*qml);
     i::Handle<i::Object> receiver(
         isolate->context()->global_proxy(), isolate);
     i::Handle<i::Object> result =
-        i::Execution::Call(fun, receiver, 0, NULL, &has_pending_exception);
+        i::Execution::Call(fun, receiver, 0, NULL, &has_pending_exception, false, qmlglobal);
     EXCEPTION_BAILOUT_CHECK(isolate, Local<Value>());
     raw_result = *result;
   }
@@ -4328,6 +4338,30 @@ v8::Local<v8::Context> Context::GetCalling() {
 }
 
 
+v8::Local<v8::Object> Context::GetCallingQmlGlobal() {
+  i::Isolate* isolate = i::Isolate::Current();
+  if (IsDeadCheck(isolate, "v8::Context::GetCallingQmlGlobal()")) {
+    return Local<Object>();
+  }
+
+  i::Context *context = isolate->context();
+  if (!context->qml_global()->IsUndefined()) {
+    i::Handle<i::Object> qmlglobal(context->qml_global());
+    return Utils::ToLocal(i::Handle<i::JSObject>::cast(qmlglobal));
+  }
+
+  i::JavaScriptFrameIterator it;
+  if (it.done()) return Local<Object>();
+  context = i::Context::cast(it.frame()->context());
+  if (!context->qml_global()->IsUndefined()) {
+    i::Handle<i::Object> qmlglobal(context->qml_global());
+    return Utils::ToLocal(i::Handle<i::JSObject>::cast(qmlglobal));
+  } else {
+      return Local<Object>();
+  }
+}
+
+
 v8::Local<v8::Object> Context::Global() {
   if (IsDeadCheck(i::Isolate::Current(), "v8::Context::Global()")) {
     return Local<v8::Object>();
diff --git a/src/arm/code-stubs-arm.cc b/src/arm/code-stubs-arm.cc
index 17dfbd7..00ac676 100644
--- a/src/arm/code-stubs-arm.cc
+++ b/src/arm/code-stubs-arm.cc
@@ -172,6 +172,10 @@ void FastNewContextStub::Generate(MacroAssembler* masm) {
   __ ldr(r1, MemOperand(cp, Context::SlotOffset(Context::GLOBAL_INDEX)));
   __ str(r1, MemOperand(r0, Context::SlotOffset(Context::GLOBAL_INDEX)));
 
+  // Copy the qml global object from the surrounding context.
+  __ ldr(r1, MemOperand(cp, Context::SlotOffset(Context::QML_GLOBAL_INDEX)));
+  __ str(r1, MemOperand(r0, Context::SlotOffset(Context::QML_GLOBAL_INDEX)));
+
   // Initialize the rest of the slots to undefined.
   __ LoadRoot(r1, Heap::kUndefinedValueRootIndex);
   for (int i = Context::MIN_CONTEXT_SLOTS; i < length; i++) {
diff --git a/src/arm/full-codegen-arm.cc b/src/arm/full-codegen-arm.cc
index 2ee1594..a1841f2 100644
--- a/src/arm/full-codegen-arm.cc
+++ b/src/arm/full-codegen-arm.cc
@@ -182,12 +182,13 @@ void FullCodeGenerator::Generate(CompilationInfo* info) {
 
   // Possibly allocate a local context.
   int heap_slots = info->scope()->num_heap_slots() - Context::MIN_CONTEXT_SLOTS;
-  if (heap_slots > 0) {
+  if (heap_slots > 0 ||
+      (scope()->is_qml_mode() && scope()->is_global_scope())) {
     Comment cmnt(masm_, "[ Allocate local context");
     // Argument to NewContext is the function, which is in r1.
     __ push(r1);
     if (heap_slots <= FastNewContextStub::kMaximumSlots) {
-      FastNewContextStub stub(heap_slots);
+      FastNewContextStub stub((heap_slots < 0)?0:heap_slots);
       __ CallStub(&stub);
     } else {
       __ CallRuntime(Runtime::kNewFunctionContext, 1);
@@ -1168,9 +1169,9 @@ void FullCodeGenerator::EmitLoadGlobalCheckExtensions(Variable* var,
     __ bind(&fast);
   }
 
-  __ ldr(r0, GlobalObjectOperand());
+  __ ldr(r0, var->is_qml_global()?QmlGlobalObjectOperand():GlobalObjectOperand());
   __ mov(r2, Operand(var->name()));
-  RelocInfo::Mode mode = (typeof_state == INSIDE_TYPEOF)
+  RelocInfo::Mode mode = (typeof_state == INSIDE_TYPEOF || var->is_qml_global())
       ? RelocInfo::CODE_TARGET
       : RelocInfo::CODE_TARGET_CONTEXT;
   Handle<Code> ic = isolate()->builtins()->LoadIC_Initialize();
@@ -1246,10 +1247,10 @@ void FullCodeGenerator::EmitVariableLoad(VariableProxy* proxy) {
       Comment cmnt(masm_, "Global variable");
       // Use inline caching. Variable name is passed in r2 and the global
       // object (receiver) in r0.
-      __ ldr(r0, GlobalObjectOperand());
+      __ ldr(r0, var->is_qml_global()?QmlGlobalObjectOperand():GlobalObjectOperand());
       __ mov(r2, Operand(var->name()));
       Handle<Code> ic = isolate()->builtins()->LoadIC_Initialize();
-      __ Call(ic, RelocInfo::CODE_TARGET_CONTEXT);
+      __ Call(ic, var->is_qml_global()?RelocInfo::CODE_TARGET:RelocInfo::CODE_TARGET_CONTEXT);
       context()->Plug(r0);
       break;
     }
@@ -1840,7 +1841,7 @@ void FullCodeGenerator::EmitVariableAssignment(Variable* var,
   if (var->IsUnallocated()) {
     // Global var, const, or let.
     __ mov(r2, Operand(var->name()));
-    __ ldr(r1, GlobalObjectOperand());
+    __ ldr(r1, var->is_qml_global()?QmlGlobalObjectOperand():GlobalObjectOperand());
     Handle<Code> ic = is_strict_mode()
         ? isolate()->builtins()->StoreIC_Initialize_Strict()
         : isolate()->builtins()->StoreIC_Initialize();
@@ -2141,10 +2142,13 @@ void FullCodeGenerator::EmitResolvePossiblyDirectEval(ResolveEvalFlag flag,
   }
   __ mov(r1, Operand(Smi::FromInt(strict_mode)));
   __ push(r1);
+  // Push the qml mode flag.
+  __ mov(r1, Operand(Smi::FromInt(is_qml_mode())));
+  __ push(r1);
 
   __ CallRuntime(flag == SKIP_CONTEXT_LOOKUP
                  ? Runtime::kResolvePossiblyDirectEvalNoLookup
-                 : Runtime::kResolvePossiblyDirectEval, 4);
+                 : Runtime::kResolvePossiblyDirectEval, 5);
 }
 
 
@@ -2217,9 +2221,9 @@ void FullCodeGenerator::VisitCall(Call* expr) {
     context()->DropAndPlug(1, r0);
   } else if (proxy != NULL && proxy->var()->IsUnallocated()) {
     // Push global object as receiver for the call IC.
-    __ ldr(r0, GlobalObjectOperand());
+    __ ldr(r0, proxy->var()->is_qml_global()?QmlGlobalObjectOperand():GlobalObjectOperand());
     __ push(r0);
-    EmitCallWithIC(expr, proxy->name(), RelocInfo::CODE_TARGET_CONTEXT);
+    EmitCallWithIC(expr, proxy->name(), proxy->var()->is_qml_global()?RelocInfo::CODE_TARGET:RelocInfo::CODE_TARGET_CONTEXT);
   } else if (proxy != NULL && proxy->var()->IsLookupSlot()) {
     // Call to a lookup slot (dynamically introduced variable).
     Label slow, done;
@@ -3630,7 +3634,7 @@ void FullCodeGenerator::VisitUnaryOperation(UnaryOperation* expr) {
         // but "delete this" is allowed.
         ASSERT(strict_mode_flag() == kNonStrictMode || var->is_this());
         if (var->IsUnallocated()) {
-          __ ldr(r2, GlobalObjectOperand());
+          __ ldr(r2, var->is_qml_global() ? QmlGlobalObjectOperand() : GlobalObjectOperand());
           __ mov(r1, Operand(var->name()));
           __ mov(r0, Operand(Smi::FromInt(kNonStrictMode)));
           __ Push(r2, r1, r0);
@@ -3916,7 +3920,7 @@ void FullCodeGenerator::VisitForTypeofValue(Expression* expr) {
   VariableProxy* proxy = expr->AsVariableProxy();
   if (proxy != NULL && proxy->var()->IsUnallocated()) {
     Comment cmnt(masm_, "Global variable");
-    __ ldr(r0, GlobalObjectOperand());
+    __ ldr(r0, proxy->var()->is_qml_global() ? QmlGlobalObjectOperand() : GlobalObjectOperand());
     __ mov(r2, Operand(proxy->name()));
     Handle<Code> ic = isolate()->builtins()->LoadIC_Initialize();
     // Use a regular load, not a contextual load, to avoid a reference
diff --git a/src/arm/lithium-arm.cc b/src/arm/lithium-arm.cc
index 8495939..00582ea 100644
--- a/src/arm/lithium-arm.cc
+++ b/src/arm/lithium-arm.cc
@@ -1122,7 +1122,7 @@ LInstruction* LChunkBuilder::DoOuterContext(HOuterContext* instr) {
 
 LInstruction* LChunkBuilder::DoGlobalObject(HGlobalObject* instr) {
   LOperand* context = UseRegisterAtStart(instr->value());
-  return DefineAsRegister(new LGlobalObject(context));
+  return DefineAsRegister(new LGlobalObject(context, instr->qml_global()));
 }
 
 
diff --git a/src/arm/lithium-arm.h b/src/arm/lithium-arm.h
index 73c7e45..49cdccc 100644
--- a/src/arm/lithium-arm.h
+++ b/src/arm/lithium-arm.h
@@ -1301,13 +1301,17 @@ class LOuterContext: public LTemplateInstruction<1, 1, 0> {
 
 class LGlobalObject: public LTemplateInstruction<1, 1, 0> {
  public:
-  explicit LGlobalObject(LOperand* context) {
+  explicit LGlobalObject(LOperand* context, bool qml_global) {
     inputs_[0] = context;
+    qml_global_ = qml_global;
   }
 
   DECLARE_CONCRETE_INSTRUCTION(GlobalObject, "global-object")
 
   LOperand* context() { return InputAt(0); }
+  bool qml_global() { return qml_global_; }
+ private:
+  bool qml_global_;
 };
 
 
diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index f6750a2..63c8463 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -190,12 +190,13 @@ bool LCodeGen::GeneratePrologue() {
 
   // Possibly allocate a local context.
   int heap_slots = scope()->num_heap_slots() - Context::MIN_CONTEXT_SLOTS;
-  if (heap_slots > 0) {
+  if (heap_slots > 0 ||
+      (scope()->is_qml_mode() && scope()->is_global_scope())) {
     Comment(";;; Allocate local context");
     // Argument to NewContext is the function, which is in r1.
     __ push(r1);
     if (heap_slots <= FastNewContextStub::kMaximumSlots) {
-      FastNewContextStub stub(heap_slots);
+      FastNewContextStub stub((heap_slots < 0)?0:heap_slots);
       __ CallStub(&stub);
     } else {
       __ CallRuntime(Runtime::kNewFunctionContext, 1);
@@ -2798,7 +2799,7 @@ void LCodeGen::DoOuterContext(LOuterContext* instr) {
 
 void LCodeGen::DoGlobalObject(LGlobalObject* instr) {
   Register result = ToRegister(instr->result());
-  __ ldr(result, ContextOperand(cp, Context::GLOBAL_INDEX));
+  __ ldr(result, ContextOperand(cp, instr->qml_global()?Context::QML_GLOBAL_INDEX:Context::GLOBAL_INDEX));
 }
 
 
diff --git a/src/arm/macro-assembler-arm.h b/src/arm/macro-assembler-arm.h
index d42ccec..9adeb36 100644
--- a/src/arm/macro-assembler-arm.h
+++ b/src/arm/macro-assembler-arm.h
@@ -1260,6 +1260,11 @@ static inline MemOperand GlobalObjectOperand()  {
 }
 
 
+static inline MemOperand QmlGlobalObjectOperand()  {
+  return ContextOperand(cp, Context::QML_GLOBAL_INDEX);
+}
+
+
 #ifdef GENERATED_CODE_COVERAGE
 #define CODE_COVERAGE_STRINGIFY(x) #x
 #define CODE_COVERAGE_TOSTRING(x) CODE_COVERAGE_STRINGIFY(x)
diff --git a/src/ast-inl.h b/src/ast-inl.h
index 731ad2f..15702cf 100644
--- a/src/ast-inl.h
+++ b/src/ast-inl.h
@@ -116,6 +116,11 @@ bool FunctionLiteral::strict_mode() const {
 }
 
 
+bool FunctionLiteral::qml_mode() const {
+  return scope()->is_qml_mode();
+}
+
+
 } }  // namespace v8::internal
 
 #endif  // V8_AST_INL_H_
diff --git a/src/ast.h b/src/ast.h
index 00cfd7f..319d090 100644
--- a/src/ast.h
+++ b/src/ast.h
@@ -1658,6 +1658,7 @@ class FunctionLiteral: public Expression {
   bool is_expression() const { return is_expression_; }
   bool is_anonymous() const { return is_anonymous_; }
   bool strict_mode() const;
+  bool qml_mode() const;
 
   int materialized_literal_count() { return materialized_literal_count_; }
   int expected_property_count() { return expected_property_count_; }
diff --git a/src/code-stubs.h b/src/code-stubs.h
index 9d4baf4..b7cac89 100644
--- a/src/code-stubs.h
+++ b/src/code-stubs.h
@@ -323,7 +323,7 @@ class FastNewContextStub : public CodeStub {
   static const int kMaximumSlots = 64;
 
   explicit FastNewContextStub(int slots) : slots_(slots) {
-    ASSERT(slots_ > 0 && slots <= kMaximumSlots);
+    ASSERT(slots_ >= 0 && slots <= kMaximumSlots);
   }
 
   void Generate(MacroAssembler* masm);
diff --git a/src/compiler.cc b/src/compiler.cc
index 5a86b4e..596df4a 100644
--- a/src/compiler.cc
+++ b/src/compiler.cc
@@ -450,7 +450,8 @@ Handle<SharedFunctionInfo> Compiler::Compile(Handle<String> source,
                                              v8::Extension* extension,
                                              ScriptDataImpl* input_pre_data,
                                              Handle<Object> script_data,
-                                             NativesFlag natives) {
+                                             NativesFlag natives,
+                                             v8::Script::CompileFlags compile_flags) {
   Isolate* isolate = source->GetIsolate();
   int source_length = source->length();
   isolate->counters()->total_load_size()->Increment(source_length);
@@ -517,6 +518,7 @@ Handle<SharedFunctionInfo> Compiler::Compile(Handle<String> source,
     info.MarkAsGlobal();
     info.SetExtension(extension);
     info.SetPreParseData(pre_data);
+    if (compile_flags & v8::Script::QmlMode) info.MarkAsQmlMode();
     if (natives == NATIVES_CODE) {
       info.MarkAsAllowingNativesSyntax();
     }
@@ -539,7 +541,8 @@ Handle<SharedFunctionInfo> Compiler::Compile(Handle<String> source,
 Handle<SharedFunctionInfo> Compiler::CompileEval(Handle<String> source,
                                                  Handle<Context> context,
                                                  bool is_global,
-                                                 StrictModeFlag strict_mode) {
+                                                 StrictModeFlag strict_mode,
+                                                 bool qml_mode) {
   Isolate* isolate = source->GetIsolate();
   int source_length = source->length();
   isolate->counters()->total_eval_size()->Increment(source_length);
@@ -563,6 +566,7 @@ Handle<SharedFunctionInfo> Compiler::CompileEval(Handle<String> source,
     CompilationInfo info(script);
     info.MarkAsEval();
     if (is_global) info.MarkAsGlobal();
+    if (qml_mode) info.MarkAsQmlMode();
     if (strict_mode == kStrictMode) info.MarkAsStrictMode();
     info.SetCallingContext(context);
     result = MakeFunctionInfo(&info);
@@ -607,6 +611,12 @@ bool Compiler::CompileLazy(CompilationInfo* info) {
       info->MarkAsStrictMode();
     }
 
+    // After parsing we know function's qml mode. Remember it.
+    if (info->function()->qml_mode()) {
+      shared->set_qml_mode(true);
+      info->MarkAsQmlMode();
+    }
+
     // Compile the code.
     if (!MakeCode(info)) {
       if (!isolate->has_pending_exception()) {
@@ -752,6 +762,7 @@ void Compiler::SetFunctionInfo(Handle<SharedFunctionInfo> function_info,
       *lit->this_property_assignments());
   function_info->set_allows_lazy_compilation(lit->AllowsLazyCompilation());
   function_info->set_strict_mode(lit->strict_mode());
+  function_info->set_qml_mode(lit->qml_mode());
   function_info->set_uses_arguments(lit->scope()->arguments() != NULL);
   function_info->set_has_duplicate_parameters(lit->has_duplicate_parameters());
 }
diff --git a/src/compiler.h b/src/compiler.h
index 09aa23d..8eacb71 100644
--- a/src/compiler.h
+++ b/src/compiler.h
@@ -54,6 +54,7 @@ class CompilationInfo BASE_EMBEDDED {
   bool is_global() const { return IsGlobal::decode(flags_); }
   bool is_strict_mode() const { return IsStrictMode::decode(flags_); }
   bool is_in_loop() const { return IsInLoop::decode(flags_); }
+  bool is_qml_mode() const { return IsQmlMode::decode(flags_); }
   FunctionLiteral* function() const { return function_; }
   Scope* scope() const { return scope_; }
   Handle<Code> code() const { return code_; }
@@ -83,6 +84,9 @@ class CompilationInfo BASE_EMBEDDED {
     ASSERT(is_lazy());
     flags_ |= IsInLoop::encode(true);
   }
+  void MarkAsQmlMode() {
+    flags_ |= IsQmlMode::encode(true);
+  }
   void MarkAsAllowingNativesSyntax() {
     flags_ |= IsNativesSyntaxAllowed::encode(true);
   }
@@ -180,6 +184,9 @@ class CompilationInfo BASE_EMBEDDED {
     if (!shared_info_.is_null() && shared_info_->strict_mode()) {
       MarkAsStrictMode();
     }
+    if (!shared_info_.is_null() && shared_info_->qml_mode()) {
+      MarkAsQmlMode();
+    }
   }
 
   void SetMode(Mode mode) {
@@ -203,7 +210,8 @@ class CompilationInfo BASE_EMBEDDED {
   class IsNativesSyntaxAllowed: public BitField<bool, 5, 1> {};
   // Is this a function from our natives.
   class IsNative: public BitField<bool, 6, 1> {};
-
+  // Qml mode
+  class IsQmlMode: public BitField<bool, 7, 1> {};
 
   unsigned flags_;
 
@@ -269,13 +277,15 @@ class Compiler : public AllStatic {
                                             v8::Extension* extension,
                                             ScriptDataImpl* pre_data,
                                             Handle<Object> script_data,
-                                            NativesFlag is_natives_code);
+                                            NativesFlag is_natives_code,
+                                            v8::Script::CompileFlags = v8::Script::Default);
 
   // Compile a String source within a context for Eval.
   static Handle<SharedFunctionInfo> CompileEval(Handle<String> source,
                                                 Handle<Context> context,
                                                 bool is_global,
-                                                StrictModeFlag strict_mode);
+                                                StrictModeFlag strict_mode,
+                                                bool qml_mode);
 
   // Compile from function info (used for lazy compilation). Returns true on
   // success and false if the compilation resulted in a stack overflow.
diff --git a/src/contexts.cc b/src/contexts.cc
index 007d30d..825493a 100644
--- a/src/contexts.cc
+++ b/src/contexts.cc
@@ -103,6 +103,9 @@ Handle<Object> Context::Lookup(Handle<String> name,
     PrintF(")\n");
   }
 
+  Handle<JSObject> qml_global;
+  Handle<JSObject> qml_global_global;
+
   do {
     if (FLAG_trace_contexts) {
       PrintF(" - looking in context %p", reinterpret_cast<void*>(*context));
@@ -110,6 +113,11 @@ Handle<Object> Context::Lookup(Handle<String> name,
       PrintF("\n");
     }
 
+    if (qml_global.is_null() && !context->qml_global()->IsUndefined()) {
+      qml_global = Handle<JSObject>(context->qml_global(), isolate);
+      qml_global_global = Handle<JSObject>(context->global(), isolate);
+    }
+
     // 1. Check global objects, subjects of with, and extension objects.
     if (context->IsGlobalContext() ||
         context->IsWithContext() ||
@@ -221,6 +229,33 @@ Handle<Object> Context::Lookup(Handle<String> name,
     }
   } while (follow_context_chain);
 
+  if (!qml_global.is_null()) {
+    if ((flags & FOLLOW_PROTOTYPE_CHAIN) == 0) {
+      *attributes = qml_global_global->GetLocalPropertyAttribute(*name);
+    } else {
+      *attributes = qml_global_global->GetPropertyAttribute(*name);
+    }
+
+    if (*attributes != ABSENT) {
+      *attributes = ABSENT;
+    } else {
+      if ((flags & FOLLOW_PROTOTYPE_CHAIN) == 0) {
+        *attributes = qml_global->GetLocalPropertyAttribute(*name);
+      } else {
+        *attributes = qml_global->GetPropertyAttribute(*name);
+      }
+
+      if (*attributes != ABSENT) {
+        // property found
+        if (FLAG_trace_contexts) {
+          PrintF("=> found property in qml global object %p\n",
+                 reinterpret_cast<void*>(*qml_global));
+        }
+        return qml_global;
+      }
+    }
+  }
+
   if (FLAG_trace_contexts) {
     PrintF("=> no property/slot found\n");
   }
diff --git a/src/contexts.h b/src/contexts.h
index b80475f..28ba69e 100644
--- a/src/contexts.h
+++ b/src/contexts.h
@@ -196,6 +196,7 @@ class Context: public FixedArray {
     // contexts), eval extension object (function contexts), subject of with
     // (with contexts), or the variable name (catch contexts).
     EXTENSION_INDEX,
+    QML_GLOBAL_INDEX,
     GLOBAL_INDEX,
     MIN_CONTEXT_SLOTS,
 
@@ -297,6 +298,9 @@ class Context: public FixedArray {
   }
   void set_global(GlobalObject* global) { set(GLOBAL_INDEX, global); }
 
+  JSObject *qml_global() { return reinterpret_cast<JSObject *>(get(QML_GLOBAL_INDEX)); }
+  void set_qml_global(JSObject *qml_global) { set(QML_GLOBAL_INDEX, qml_global); }
+
   // Returns a JSGlobalProxy object or null.
   JSObject* global_proxy();
   void set_global_proxy(JSObject* global);
diff --git a/src/execution.cc b/src/execution.cc
index 2021c0f..c64c9ea 100644
--- a/src/execution.cc
+++ b/src/execution.cc
@@ -71,7 +71,8 @@ static Handle<Object> Invoke(bool construct,
                              Handle<Object> receiver,
                              int argc,
                              Object*** args,
-                             bool* has_pending_exception) {
+                             bool* has_pending_exception,
+                             Handle<Object> qml) {
   Isolate* isolate = func->GetIsolate();
 
   // Entering JavaScript.
@@ -106,6 +107,12 @@ static Handle<Object> Invoke(bool construct,
   // make the current one is indeed a global object.
   ASSERT(func->context()->global()->IsGlobalObject());
 
+  Handle<JSObject> oldqml;
+  if (!qml.is_null()) {
+    oldqml = Handle<JSObject>(func->context()->qml_global());
+    func->context()->set_qml_global(JSObject::cast(*qml));
+  }
+
   {
     // Save and restore context around invocation and block the
     // allocation of handles without explicit handle scopes.
@@ -121,6 +128,9 @@ static Handle<Object> Invoke(bool construct,
                                 receiver_pointer, argc, args);
   }
 
+  if (!qml.is_null()) 
+    func->context()->set_qml_global(*oldqml);
+
 #ifdef DEBUG
   value->Verify();
 #endif
@@ -149,7 +159,18 @@ Handle<Object> Execution::Call(Handle<Object> callable,
                                int argc,
                                Object*** args,
                                bool* pending_exception,
-                               bool convert_receiver) {
+                               bool convert_receiver)
+{
+    return Call(callable, receiver, argc, args, pending_exception, convert_receiver, Handle<Object>());
+}
+
+Handle<Object> Execution::Call(Handle<Object> callable,
+                               Handle<Object> receiver,
+                               int argc,
+                               Object*** args,
+                               bool* pending_exception,
+                               bool convert_receiver,
+                               Handle<Object> qml) {
   *pending_exception = false;
 
   if (!callable->IsJSFunction()) {
@@ -173,14 +194,14 @@ Handle<Object> Execution::Call(Handle<Object> callable,
     if (*pending_exception) return callable;
   }
 
-  return Invoke(false, func, receiver, argc, args, pending_exception);
+  return Invoke(false, func, receiver, argc, args, pending_exception, qml);
 }
 
 
 Handle<Object> Execution::New(Handle<JSFunction> func, int argc,
                               Object*** args, bool* pending_exception) {
   return Invoke(true, func, Isolate::Current()->global(), argc, args,
-                pending_exception);
+                pending_exception, Handle<Object>());
 }
 
 
@@ -199,7 +220,7 @@ Handle<Object> Execution::TryCall(Handle<JSFunction> func,
   *caught_exception = false;
 
   Handle<Object> result = Invoke(false, func, receiver, argc, args,
-                                 caught_exception);
+                                 caught_exception, Handle<Object>());
 
   if (*caught_exception) {
     ASSERT(catcher.HasCaught());
diff --git a/src/execution.h b/src/execution.h
index 9fa6e78..baa58b5 100644
--- a/src/execution.h
+++ b/src/execution.h
@@ -65,6 +65,14 @@ class Execution : public AllStatic {
                              bool* pending_exception,
                              bool convert_receiver = false);
 
+  static Handle<Object> Call(Handle<Object> callable,
+                             Handle<Object> receiver,
+                             int argc,
+                             Object*** args,
+                             bool* pending_exception,
+                             bool convert_receiver,
+                             Handle<Object> qml);
+
   // Construct object from function, the caller supplies an array of
   // arguments. Arguments are Object* type. After function returns,
   // pointers in 'args' might be invalid.
diff --git a/src/full-codegen.cc b/src/full-codegen.cc
index e822588..516d237 100644
--- a/src/full-codegen.cc
+++ b/src/full-codegen.cc
@@ -512,7 +512,7 @@ void FullCodeGenerator::VisitDeclarations(
   // Batch declare global functions and variables.
   if (global_count > 0) {
     Handle<FixedArray> array =
-        isolate()->factory()->NewFixedArray(2 * global_count, TENURED);
+        isolate()->factory()->NewFixedArray(3 * global_count, TENURED);
     for (int j = 0, i = 0; i < length; i++) {
       Declaration* decl = declarations->at(i);
       Variable* var = decl->proxy()->var();
@@ -536,6 +536,7 @@ void FullCodeGenerator::VisitDeclarations(
           }
           array->set(j++, *function);
         }
+        array->set(j++, Smi::FromInt(var->is_qml_global()));
       }
     }
     // Invoke the platform-dependent code generator to do the actual
diff --git a/src/full-codegen.h b/src/full-codegen.h
index 6958dae..48753c5 100644
--- a/src/full-codegen.h
+++ b/src/full-codegen.h
@@ -581,6 +581,7 @@ class FullCodeGenerator: public AstVisitor {
   StrictModeFlag strict_mode_flag() {
     return is_strict_mode() ? kStrictMode : kNonStrictMode;
   }
+  bool is_qml_mode() { return function()->qml_mode(); }
   FunctionLiteral* function() { return info_->function(); }
   Scope* scope() { return scope_; }
 
diff --git a/src/heap.cc b/src/heap.cc
index c730455..447dce1 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -4407,6 +4407,7 @@ MaybeObject* Heap::AllocateFunctionContext(int length, JSFunction* function) {
   context->set_previous(function->context());
   context->set_extension(NULL);
   context->set_global(function->context()->global());
+  context->set_qml_global(function->context()->qml_global());
   return context;
 }
 
@@ -4427,6 +4428,7 @@ MaybeObject* Heap::AllocateCatchContext(JSFunction* function,
   context->set_previous(previous);
   context->set_extension(name);
   context->set_global(previous->global());
+  context->set_qml_global(previous->qml_global());
   context->set(Context::THROWN_OBJECT_INDEX, thrown_object);
   return context;
 }
@@ -4445,6 +4447,7 @@ MaybeObject* Heap::AllocateWithContext(JSFunction* function,
   context->set_previous(previous);
   context->set_extension(extension);
   context->set_global(previous->global());
+  context->set_qml_global(previous->qml_global());
   return context;
 }
 
@@ -4463,6 +4466,7 @@ MaybeObject* Heap::AllocateBlockContext(JSFunction* function,
   context->set_previous(previous);
   context->set_extension(scope_info);
   context->set_global(previous->global());
+  context->set_qml_global(previous->qml_global());
   return context;
 }
 
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 6b43f53..d0e6fb0 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -1394,7 +1394,7 @@ class HOuterContext: public HUnaryOperation {
 
 class HGlobalObject: public HUnaryOperation {
  public:
-  explicit HGlobalObject(HValue* context) : HUnaryOperation(context) {
+  explicit HGlobalObject(HValue* context) : HUnaryOperation(context), qml_global_(false) {
     set_representation(Representation::Tagged());
     SetFlag(kUseGVN);
   }
@@ -1405,8 +1405,14 @@ class HGlobalObject: public HUnaryOperation {
     return Representation::Tagged();
   }
 
+  bool qml_global() { return qml_global_; }
+  void set_qml_global(bool v) { qml_global_ = v; }
+
  protected:
   virtual bool DataEquals(HValue* other) { return true; }
+
+ private:
+  bool qml_global_;
 };
 
 
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 64a6ae5..f0c1763 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -3174,6 +3174,7 @@ void HGraphBuilder::VisitVariableProxy(VariableProxy* expr) {
       } else {
         HValue* context = environment()->LookupContext();
         HGlobalObject* global_object = new(zone()) HGlobalObject(context);
+        if (variable->is_qml_global()) global_object->set_qml_global(true);
         AddInstruction(global_object);
         HLoadGlobalGeneric* instr =
             new(zone()) HLoadGlobalGeneric(context,
@@ -3640,6 +3641,7 @@ void HGraphBuilder::HandleGlobalVariableAssignment(Variable* var,
   } else {
     HValue* context =  environment()->LookupContext();
     HGlobalObject* global_object = new(zone()) HGlobalObject(context);
+    if (var->is_qml_global()) global_object->set_qml_global(true);
     AddInstruction(global_object);
     HStoreGlobalGeneric* instr =
         new(zone()) HStoreGlobalGeneric(context,
diff --git a/src/ia32/code-stubs-ia32.cc b/src/ia32/code-stubs-ia32.cc
index 1ca577c..6cc80d3 100644
--- a/src/ia32/code-stubs-ia32.cc
+++ b/src/ia32/code-stubs-ia32.cc
@@ -143,6 +143,11 @@ void FastNewContextStub::Generate(MacroAssembler* masm) {
   __ mov(ebx, Operand(esi, Context::SlotOffset(Context::GLOBAL_INDEX)));
   __ mov(Operand(eax, Context::SlotOffset(Context::GLOBAL_INDEX)), ebx);
 
+  // Copy the qml global object from the previous context.
+  __ mov(ebx, Operand(esi, Context::SlotOffset(Context::QML_GLOBAL_INDEX)));
+  __ mov(Operand(eax, Context::SlotOffset(Context::QML_GLOBAL_INDEX)), ebx);
+
+
   // Initialize the rest of the slots to undefined.
   __ mov(ebx, factory->undefined_value());
   for (int i = Context::MIN_CONTEXT_SLOTS; i < length; i++) {
diff --git a/src/ia32/full-codegen-ia32.cc b/src/ia32/full-codegen-ia32.cc
index d45a9cd..a5883a2 100644
--- a/src/ia32/full-codegen-ia32.cc
+++ b/src/ia32/full-codegen-ia32.cc
@@ -178,12 +178,13 @@ void FullCodeGenerator::Generate(CompilationInfo* info) {
 
   // Possibly allocate a local context.
   int heap_slots = info->scope()->num_heap_slots() - Context::MIN_CONTEXT_SLOTS;
-  if (heap_slots > 0) {
+  if (heap_slots > 0 ||
+      (scope()->is_qml_mode() && scope()->is_global_scope())) {
     Comment cmnt(masm_, "[ Allocate local context");
     // Argument to NewContext is the function, which is still in edi.
     __ push(edi);
     if (heap_slots <= FastNewContextStub::kMaximumSlots) {
-      FastNewContextStub stub(heap_slots);
+      FastNewContextStub stub((heap_slots < 0)?0:heap_slots);
       __ CallStub(&stub);
     } else {
       __ CallRuntime(Runtime::kNewFunctionContext, 1);
@@ -1152,10 +1153,10 @@ void FullCodeGenerator::EmitLoadGlobalCheckExtensions(Variable* var,
 
   // All extension objects were empty and it is safe to use a global
   // load IC call.
-  __ mov(eax, GlobalObjectOperand());
+  __ mov(eax, var->is_qml_global()?QmlGlobalObjectOperand():GlobalObjectOperand());
   __ mov(ecx, var->name());
   Handle<Code> ic = isolate()->builtins()->LoadIC_Initialize();
-  RelocInfo::Mode mode = (typeof_state == INSIDE_TYPEOF)
+  RelocInfo::Mode mode = (typeof_state == INSIDE_TYPEOF || var->is_qml_global())
       ? RelocInfo::CODE_TARGET
       : RelocInfo::CODE_TARGET_CONTEXT;
   __ call(ic, mode);
@@ -1229,10 +1230,10 @@ void FullCodeGenerator::EmitVariableLoad(VariableProxy* proxy) {
       Comment cmnt(masm_, "Global variable");
       // Use inline caching. Variable name is passed in ecx and the global
       // object in eax.
-      __ mov(eax, GlobalObjectOperand());
+      __ mov(eax, var->is_qml_global()?QmlGlobalObjectOperand():GlobalObjectOperand());
       __ mov(ecx, var->name());
       Handle<Code> ic = isolate()->builtins()->LoadIC_Initialize();
-      __ call(ic, RelocInfo::CODE_TARGET_CONTEXT);
+      __ call(ic, var->is_qml_global()?RelocInfo::CODE_TARGET:RelocInfo::CODE_TARGET_CONTEXT);
       context()->Plug(eax);
       break;
     }
@@ -1833,7 +1834,7 @@ void FullCodeGenerator::EmitVariableAssignment(Variable* var,
   if (var->IsUnallocated()) {
     // Global var, const, or let.
     __ mov(ecx, var->name());
-    __ mov(edx, GlobalObjectOperand());
+    __ mov(edx, var->is_qml_global()?QmlGlobalObjectOperand():GlobalObjectOperand());
     Handle<Code> ic = is_strict_mode()
         ? isolate()->builtins()->StoreIC_Initialize_Strict()
         : isolate()->builtins()->StoreIC_Initialize();
@@ -2147,9 +2148,12 @@ void FullCodeGenerator::EmitResolvePossiblyDirectEval(ResolveEvalFlag flag,
   }
   __ push(Immediate(Smi::FromInt(strict_mode)));
 
+  // Push the qml mode flag
+  __ push(Immediate(Smi::FromInt(is_qml_mode())));
+
   __ CallRuntime(flag == SKIP_CONTEXT_LOOKUP
                  ? Runtime::kResolvePossiblyDirectEvalNoLookup
-                 : Runtime::kResolvePossiblyDirectEval, 4);
+                 : Runtime::kResolvePossiblyDirectEval, 5);
 }
 
 
@@ -2220,9 +2224,9 @@ void FullCodeGenerator::VisitCall(Call* expr) {
 
   } else if (proxy != NULL && proxy->var()->IsUnallocated()) {
     // Push global object as receiver for the call IC.
-    __ push(GlobalObjectOperand());
+    __ push(proxy->var()->is_qml_global()?QmlGlobalObjectOperand():GlobalObjectOperand());
     increment_stack_height();
-    EmitCallWithIC(expr, proxy->name(), RelocInfo::CODE_TARGET_CONTEXT);
+    EmitCallWithIC(expr, proxy->name(), proxy->var()->is_qml_global()?RelocInfo::CODE_TARGET:RelocInfo::CODE_TARGET_CONTEXT);
 
   } else if (proxy != NULL && proxy->var()->IsLookupSlot()) {
     // Call to a lookup slot (dynamically introduced variable).
@@ -3688,7 +3692,7 @@ void FullCodeGenerator::VisitUnaryOperation(UnaryOperation* expr) {
         // but "delete this" is allowed.
         ASSERT(strict_mode_flag() == kNonStrictMode || var->is_this());
         if (var->IsUnallocated()) {
-          __ push(GlobalObjectOperand());
+          __ push(var->is_qml_global() ? QmlGlobalObjectOperand() : GlobalObjectOperand());
           __ push(Immediate(var->name()));
           __ push(Immediate(Smi::FromInt(kNonStrictMode)));
           __ InvokeBuiltin(Builtins::DELETE, CALL_FUNCTION);
@@ -3996,7 +4000,7 @@ void FullCodeGenerator::VisitForTypeofValue(Expression* expr) {
 
   if (proxy != NULL && proxy->var()->IsUnallocated()) {
     Comment cmnt(masm_, "Global variable");
-    __ mov(eax, GlobalObjectOperand());
+    __ mov(eax, proxy->var()->is_qml_global() ? QmlGlobalObjectOperand() : GlobalObjectOperand());
     __ mov(ecx, Immediate(proxy->name()));
     Handle<Code> ic = isolate()->builtins()->LoadIC_Initialize();
     // Use a regular load, not a contextual load, to avoid a reference
diff --git a/src/ia32/lithium-codegen-ia32.cc b/src/ia32/lithium-codegen-ia32.cc
index 9e1fd34..1abcdd3 100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -211,12 +211,13 @@ bool LCodeGen::GeneratePrologue() {
 
   // Possibly allocate a local context.
   int heap_slots = scope()->num_heap_slots() - Context::MIN_CONTEXT_SLOTS;
-  if (heap_slots > 0) {
+  if (heap_slots > 0 ||
+      (scope()->is_qml_mode() && scope()->is_global_scope())) {
     Comment(";;; Allocate local context");
     // Argument to NewContext is the function, which is still in edi.
     __ push(edi);
     if (heap_slots <= FastNewContextStub::kMaximumSlots) {
-      FastNewContextStub stub(heap_slots);
+      FastNewContextStub stub((heap_slots < 0)?0:heap_slots);
       __ CallStub(&stub);
     } else {
       __ CallRuntime(Runtime::kNewFunctionContext, 1);
@@ -2635,7 +2636,7 @@ void LCodeGen::DoOuterContext(LOuterContext* instr) {
 void LCodeGen::DoGlobalObject(LGlobalObject* instr) {
   Register context = ToRegister(instr->context());
   Register result = ToRegister(instr->result());
-  __ mov(result, Operand(context, Context::SlotOffset(Context::GLOBAL_INDEX)));
+  __ mov(result, Operand(context, Context::SlotOffset(instr->qml_global()?Context::QML_GLOBAL_INDEX:Context::GLOBAL_INDEX)));
 }
 
 
diff --git a/src/ia32/lithium-ia32.cc b/src/ia32/lithium-ia32.cc
index 856106c..0b058e6 100644
--- a/src/ia32/lithium-ia32.cc
+++ b/src/ia32/lithium-ia32.cc
@@ -1138,7 +1138,7 @@ LInstruction* LChunkBuilder::DoOuterContext(HOuterContext* instr) {
 
 LInstruction* LChunkBuilder::DoGlobalObject(HGlobalObject* instr) {
   LOperand* context = UseRegisterAtStart(instr->value());
-  return DefineAsRegister(new LGlobalObject(context));
+  return DefineAsRegister(new LGlobalObject(context, instr->qml_global()));
 }
 
 
diff --git a/src/ia32/lithium-ia32.h b/src/ia32/lithium-ia32.h
index 3a06ac3..087d5cb 100644
--- a/src/ia32/lithium-ia32.h
+++ b/src/ia32/lithium-ia32.h
@@ -1336,13 +1336,17 @@ class LOuterContext: public LTemplateInstruction<1, 1, 0> {
 
 class LGlobalObject: public LTemplateInstruction<1, 1, 0> {
  public:
-  explicit LGlobalObject(LOperand* context) {
+  explicit LGlobalObject(LOperand* context, bool qml_global) {
     inputs_[0] = context;
+    qml_global_ = qml_global;
   }
 
   DECLARE_CONCRETE_INSTRUCTION(GlobalObject, "global-object")
 
   LOperand* context() { return InputAt(0); }
+  bool qml_global() { return qml_global_; }
+ private:
+  bool qml_global_;
 };
 
 
diff --git a/src/ia32/macro-assembler-ia32.h b/src/ia32/macro-assembler-ia32.h
index a1b42c2..7a64b9a 100644
--- a/src/ia32/macro-assembler-ia32.h
+++ b/src/ia32/macro-assembler-ia32.h
@@ -931,6 +931,9 @@ static inline Operand GlobalObjectOperand() {
   return ContextOperand(esi, Context::GLOBAL_INDEX);
 }
 
+static inline Operand QmlGlobalObjectOperand() {
+  return ContextOperand(esi, Context::QML_GLOBAL_INDEX);
+}
 
 // Generates an Operand for saving parameters after PrepareCallApiFunction.
 Operand ApiParameterOperand(int index);
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 36af868..375df0f 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -3615,6 +3615,8 @@ void SharedFunctionInfo::set_optimization_disabled(bool disable) {
 
 BOOL_ACCESSORS(SharedFunctionInfo, compiler_hints, strict_mode,
                kStrictModeFunction)
+BOOL_ACCESSORS(SharedFunctionInfo, compiler_hints, qml_mode,
+               kQmlModeFunction)
 BOOL_ACCESSORS(SharedFunctionInfo, compiler_hints, native, kNative)
 BOOL_ACCESSORS(SharedFunctionInfo, compiler_hints,
                name_should_print_as_anonymous,
diff --git a/src/objects.h b/src/objects.h
index dea5bbd..71895be 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -4725,6 +4725,9 @@ class SharedFunctionInfo: public HeapObject {
   // Indicates whether the function is a strict mode function.
   DECL_BOOLEAN_ACCESSORS(strict_mode)
 
+  // Indicates whether the function is a qml mode function.
+  DECL_BOOLEAN_ACCESSORS(qml_mode)
+
   // False if the function definitely does not allocate an arguments object.
   DECL_BOOLEAN_ACCESSORS(uses_arguments)
 
@@ -4939,6 +4942,7 @@ class SharedFunctionInfo: public HeapObject {
     kCodeAgeShift,
     kOptimizationDisabled = kCodeAgeShift + kCodeAgeSize,
     kStrictModeFunction,
+    kQmlModeFunction,
     kUsesArguments,
     kHasDuplicateParameters,
     kNative,
diff --git a/src/parser.cc b/src/parser.cc
index ad8850e..a9af8eb 100644
--- a/src/parser.cc
+++ b/src/parser.cc
@@ -594,7 +594,8 @@ Parser::Parser(Handle<Script> script,
 
 FunctionLiteral* Parser::ParseProgram(Handle<String> source,
                                       bool in_global_context,
-                                      StrictModeFlag strict_mode) {
+                                      StrictModeFlag strict_mode,
+                                      bool qml_mode) {
   ZoneScope zone_scope(isolate(), DONT_DELETE_ON_EXIT);
 
   HistogramTimerScope timer(isolate()->counters()->parse());
@@ -610,11 +611,11 @@ FunctionLiteral* Parser::ParseProgram(Handle<String> source,
     ExternalTwoByteStringUC16CharacterStream stream(
         Handle<ExternalTwoByteString>::cast(source), 0, source->length());
     scanner_.Initialize(&stream);
-    return DoParseProgram(source, in_global_context, strict_mode, &zone_scope);
+    return DoParseProgram(source, in_global_context, strict_mode, qml_mode, &zone_scope);
   } else {
     GenericStringUC16CharacterStream stream(source, 0, source->length());
     scanner_.Initialize(&stream);
-    return DoParseProgram(source, in_global_context, strict_mode, &zone_scope);
+    return DoParseProgram(source, in_global_context, strict_mode, qml_mode, &zone_scope);
   }
 }
 
@@ -622,6 +623,7 @@ FunctionLiteral* Parser::ParseProgram(Handle<String> source,
 FunctionLiteral* Parser::DoParseProgram(Handle<String> source,
                                         bool in_global_context,
                                         StrictModeFlag strict_mode,
+                                        bool qml_mode,
                                         ZoneScope* zone_scope) {
   ASSERT(target_stack_ == NULL);
   if (pre_data_ != NULL) pre_data_->Initialize();
@@ -642,6 +644,9 @@ FunctionLiteral* Parser::DoParseProgram(Handle<String> source,
     if (strict_mode == kStrictMode) {
       top_scope_->EnableStrictMode();
     }
+    if (qml_mode) {
+      scope->EnableQmlMode();
+    }
     ZoneList<Statement*>* body = new(zone()) ZoneList<Statement*>(16);
     bool ok = true;
     int beg_loc = scanner().location().beg_pos;
@@ -736,6 +741,9 @@ FunctionLiteral* Parser::ParseLazy(CompilationInfo* info,
     if (shared_info->strict_mode()) {
       top_scope_->EnableStrictMode();
     }
+    if (shared_info->qml_mode()) {
+      top_scope_->EnableQmlMode();
+    }
 
     FunctionLiteral::Type type = shared_info->is_expression()
         ? (shared_info->is_anonymous()
@@ -1806,6 +1814,11 @@ Block* Parser::ParseVariableDeclarations(VariableDeclarationContext var_context,
         arguments->Add(value);
         value = NULL;  // zap the value to avoid the unnecessary assignment
 
+        int qml_mode = 0;
+        if (top_scope_->is_qml_mode() && !Isolate::Current()->global()->HasProperty(*name)) 
+          qml_mode = 1;
+        arguments->Add(NewNumberLiteral(qml_mode));
+
         // Construct the call to Runtime_InitializeConstGlobal
         // and add it to the initialization statement block.
         // Note that the function does different things depending on
@@ -1824,6 +1837,11 @@ Block* Parser::ParseVariableDeclarations(VariableDeclarationContext var_context,
             : kNonStrictMode;
         arguments->Add(NewNumberLiteral(flag));
 
+        int qml_mode = 0;
+        if (top_scope_->is_qml_mode() && !Isolate::Current()->global()->HasProperty(*name)) 
+          qml_mode = 1;
+        arguments->Add(NewNumberLiteral(qml_mode));
+
         // Be careful not to assign a value to the global variable if
         // we're in a with. The initialization value should not
         // necessarily be stored in the global object in that case,
@@ -5217,7 +5235,8 @@ bool ParserApi::Parse(CompilationInfo* info) {
       Handle<String> source = Handle<String>(String::cast(script->source()));
       result = parser.ParseProgram(source,
                                    info->is_global(),
-                                   info->StrictMode());
+                                   info->StrictMode(),
+                                   info->is_qml_mode());
     }
   }
   info->SetFunction(result);
diff --git a/src/parser.h b/src/parser.h
index d834ed1..d88d1ef 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -426,7 +426,8 @@ class Parser {
   // Returns NULL if parsing failed.
   FunctionLiteral* ParseProgram(Handle<String> source,
                                 bool in_global_context,
-                                StrictModeFlag strict_mode);
+                                StrictModeFlag strict_mode,
+                                bool qml_mode);
 
   FunctionLiteral* ParseLazy(CompilationInfo* info);
 
@@ -466,6 +467,7 @@ class Parser {
   FunctionLiteral* DoParseProgram(Handle<String> source,
                                   bool in_global_context,
                                   StrictModeFlag strict_mode,
+                                  bool qml_mode,
                                   ZoneScope* zone_scope);
 
   // Report syntax error
diff --git a/src/prettyprinter.cc b/src/prettyprinter.cc
index 37c76ce..73812fd 100644
--- a/src/prettyprinter.cc
+++ b/src/prettyprinter.cc
@@ -618,6 +618,9 @@ void AstPrinter::PrintLiteralWithModeIndented(const char* info,
     EmbeddedVector<char, 256> buf;
     int pos = OS::SNPrintF(buf, "%s (mode = %s", info,
                            Variable::Mode2String(var->mode()));
+    if (var->is_qml_global()) {
+      pos += OS::SNPrintF(buf + pos, ":QML");
+    }
     OS::SNPrintF(buf + pos, ")");
     PrintLiteralIndented(buf.start(), value, true);
   }
diff --git a/src/runtime.cc b/src/runtime.cc
index 5a850e9..0388a77 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -1213,19 +1213,23 @@ static Failure* ThrowRedeclarationError(Isolate* isolate,
 RUNTIME_FUNCTION(MaybeObject*, Runtime_DeclareGlobals) {
   ASSERT(args.length() == 3);
   HandleScope scope(isolate);
-  Handle<GlobalObject> global = Handle<GlobalObject>(
-      isolate->context()->global());
 
   Handle<Context> context = args.at<Context>(0);
   CONVERT_ARG_CHECKED(FixedArray, pairs, 1);
   CONVERT_SMI_ARG_CHECKED(flags, 2);
 
+  Handle<JSObject> js_global = Handle<JSObject>(isolate->context()->global());
+  Handle<JSObject> qml_global = Handle<JSObject>(isolate->context()->qml_global());
+
   // Traverse the name/value pairs and set the properties.
   int length = pairs->length();
-  for (int i = 0; i < length; i += 2) {
+  for (int i = 0; i < length; i += 3) {
     HandleScope scope(isolate);
     Handle<String> name(String::cast(pairs->get(i)));
     Handle<Object> value(pairs->get(i + 1), isolate);
+    Handle<Smi> is_qml_global(Smi::cast(pairs->get(i + 2)));
+
+    Handle<JSObject> global = is_qml_global->value()?qml_global:js_global;
 
     // We have to declare a global const property. To capture we only
     // assign to it when evaluating the assignment for "const x =
@@ -1414,19 +1418,24 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_InitializeVarGlobal) {
   NoHandleAllocation nha;
   // args[0] == name
   // args[1] == strict_mode
-  // args[2] == value (optional)
+  // args[2] == qml_mode
+  // args[3] == value (optional)
 
   // Determine if we need to assign to the variable if it already
   // exists (based on the number of arguments).
-  RUNTIME_ASSERT(args.length() == 2 || args.length() == 3);
-  bool assign = args.length() == 3;
+  RUNTIME_ASSERT(args.length() == 3 || args.length() == 4);
+  bool assign = args.length() == 4;
 
   CONVERT_ARG_CHECKED(String, name, 0);
-  GlobalObject* global = isolate->context()->global();
   RUNTIME_ASSERT(args[1]->IsSmi());
   StrictModeFlag strict_mode = static_cast<StrictModeFlag>(args.smi_at(1));
   ASSERT(strict_mode == kStrictMode || strict_mode == kNonStrictMode);
 
+  RUNTIME_ASSERT(args[2]->IsSmi());
+  int qml_mode = Smi::cast(args[2])->value();
+
+  JSObject* global = qml_mode?isolate->context()->qml_global():isolate->context()->global();
+
   // According to ECMA-262, section 12.2, page 62, the property must
   // not be deletable.
   PropertyAttributes attributes = DONT_DELETE;
@@ -1454,7 +1463,7 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_InitializeVarGlobal) {
         // Found an interceptor that's not read only.
         if (assign) {
           return raw_holder->SetProperty(
-              &lookup, *name, args[2], attributes, strict_mode);
+              &lookup, *name, args[3], attributes, strict_mode);
         } else {
           return isolate->heap()->undefined_value();
         }
@@ -1464,9 +1473,9 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_InitializeVarGlobal) {
   }
 
   // Reload global in case the loop above performed a GC.
-  global = isolate->context()->global();
+  global = qml_mode?isolate->context()->qml_global():isolate->context()->global();
   if (assign) {
-    return global->SetProperty(*name, args[2], attributes, strict_mode, true);
+    return global->SetProperty(*name, args[3], attributes, strict_mode, true);
   }
   return isolate->heap()->undefined_value();
 }
@@ -1476,12 +1485,15 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_InitializeConstGlobal) {
   // All constants are declared with an initial value. The name
   // of the constant is the first argument and the initial value
   // is the second.
-  RUNTIME_ASSERT(args.length() == 2);
+  RUNTIME_ASSERT(args.length() == 3);
   CONVERT_ARG_CHECKED(String, name, 0);
   Handle<Object> value = args.at<Object>(1);
 
+  RUNTIME_ASSERT(args[2]->IsSmi());
+  int qml_mode = Smi::cast(args[2])->value();
+
   // Get the current global object from top.
-  GlobalObject* global = isolate->context()->global();
+  JSObject* global = qml_mode?isolate->context()->qml_global():isolate->context()->global();
 
   // According to ECMA-262, section 12.2, page 62, the property must
   // not be deletable. Since it's a const, it must be READ_ONLY too.
@@ -1505,7 +1517,7 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_InitializeConstGlobal) {
     // Restore global object from context (in case of GC) and continue
     // with setting the value.
     HandleScope handle_scope(isolate);
-    Handle<GlobalObject> global(isolate->context()->global());
+    Handle<JSObject> global(qml_mode?isolate->context()->qml_global():isolate->context()->global());
 
     // BUG 1213575: Handle the case where we have to set a read-only
     // property through an interceptor and only do it if it's
@@ -9204,7 +9216,8 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_CompileString) {
   Handle<SharedFunctionInfo> shared = Compiler::CompileEval(source,
                                                             context,
                                                             true,
-                                                            kNonStrictMode);
+                                                            kNonStrictMode,
+                                                            false);
   if (shared.is_null()) return Failure::Exception();
   Handle<JSFunction> fun =
       isolate->factory()->NewFunctionFromSharedFunctionInfo(shared,
@@ -9217,7 +9230,8 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_CompileString) {
 static ObjectPair CompileGlobalEval(Isolate* isolate,
                                     Handle<String> source,
                                     Handle<Object> receiver,
-                                    StrictModeFlag strict_mode) {
+                                    StrictModeFlag strict_mode, 
+                                    bool qml_mode) {
   Handle<Context> context = Handle<Context>(isolate->context());
   Handle<Context> global_context = Handle<Context>(context->global_context());
 
@@ -9235,7 +9249,8 @@ static ObjectPair CompileGlobalEval(Isolate* isolate,
       source,
       Handle<Context>(isolate->context()),
       context->IsGlobalContext(),
-      strict_mode);
+      strict_mode,
+      qml_mode);
   if (shared.is_null()) return MakePair(Failure::Exception(), NULL);
   Handle<JSFunction> compiled =
       isolate->factory()->NewFunctionFromSharedFunctionInfo(
@@ -9245,7 +9260,7 @@ static ObjectPair CompileGlobalEval(Isolate* isolate,
 
 
 RUNTIME_FUNCTION(ObjectPair, Runtime_ResolvePossiblyDirectEval) {
-  ASSERT(args.length() == 4);
+  ASSERT(args.length() == 5);
 
   HandleScope scope(isolate);
   Handle<Object> callee = args.at<Object>(0);
@@ -9308,15 +9323,17 @@ RUNTIME_FUNCTION(ObjectPair, Runtime_ResolvePossiblyDirectEval) {
   }
 
   ASSERT(args[3]->IsSmi());
+  ASSERT(args[4]->IsSmi());
   return CompileGlobalEval(isolate,
                            args.at<String>(1),
                            args.at<Object>(2),
-                           static_cast<StrictModeFlag>(args.smi_at(3)));
+                           static_cast<StrictModeFlag>(args.smi_at(3)),
+                           Smi::cast(args[4])->value());
 }
 
 
 RUNTIME_FUNCTION(ObjectPair, Runtime_ResolvePossiblyDirectEvalNoLookup) {
-  ASSERT(args.length() == 4);
+  ASSERT(args.length() == 5);
 
   HandleScope scope(isolate);
   Handle<Object> callee = args.at<Object>(0);
@@ -9329,10 +9346,12 @@ RUNTIME_FUNCTION(ObjectPair, Runtime_ResolvePossiblyDirectEvalNoLookup) {
   }
 
   ASSERT(args[3]->IsSmi());
+  ASSERT(args[4]->IsSmi());
   return CompileGlobalEval(isolate,
                            args.at<String>(1),
                            args.at<Object>(2),
-                           static_cast<StrictModeFlag>(args.smi_at(3)));
+                           static_cast<StrictModeFlag>(args.smi_at(3)),
+                           Smi::cast(args[4])->value());
 }
 
 
@@ -11771,6 +11790,7 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_DebugEvaluate) {
   Handle<JSFunction> function(JSFunction::cast(frame->function()));
   Handle<SerializedScopeInfo> scope_info(function->shared()->scope_info());
   ScopeInfo<> sinfo(*scope_info);
+  bool qml_mode = function->shared()->qml_mode();
 
   // Traverse the saved contexts chain to find the active context for the
   // selected frame.
@@ -11840,7 +11860,8 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_DebugEvaluate) {
       Compiler::CompileEval(function_source,
                             context,
                             context->IsGlobalContext(),
-                            kNonStrictMode);
+                            kNonStrictMode,
+                            qml_mode);
   if (shared.is_null()) return Failure::Exception();
   Handle<JSFunction> compiled_function =
       isolate->factory()->NewFunctionFromSharedFunctionInfo(shared, context);
@@ -11850,7 +11871,8 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_DebugEvaluate) {
   Handle<Object> receiver(frame->receiver(), isolate);
   Handle<Object> evaluation_function =
       Execution::Call(compiled_function, receiver, 0, NULL,
-                      &has_pending_exception);
+                      &has_pending_exception, false,
+                      Handle<Object>(function->context()->qml_global()));
   if (has_pending_exception) return Failure::Exception();
 
   Handle<Object> arguments = GetArgumentsObject(isolate,
@@ -11930,7 +11952,7 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_DebugEvaluateGlobal) {
   // Currently, the eval code will be executed in non-strict mode,
   // even in the strict code context.
   Handle<SharedFunctionInfo> shared =
-      Compiler::CompileEval(source, context, is_global, kNonStrictMode);
+      Compiler::CompileEval(source, context, is_global, kNonStrictMode, false);
   if (shared.is_null()) return Failure::Exception();
   Handle<JSFunction> compiled_function =
       Handle<JSFunction>(
diff --git a/src/runtime.h b/src/runtime.h
index c6f7773..284f723 100644
--- a/src/runtime.h
+++ b/src/runtime.h
@@ -257,8 +257,8 @@ namespace internal {
   \
   /* Eval */ \
   F(GlobalReceiver, 1, 1) \
-  F(ResolvePossiblyDirectEval, 4, 2) \
-  F(ResolvePossiblyDirectEvalNoLookup, 4, 2) \
+  F(ResolvePossiblyDirectEval, 5, 2) \
+  F(ResolvePossiblyDirectEvalNoLookup, 5, 2) \
   \
   F(SetProperty, -1 /* 4 or 5 */, 1) \
   F(DefineOrRedefineDataProperty, 4, 1) \
@@ -325,8 +325,8 @@ namespace internal {
   /* Declarations and initialization */ \
   F(DeclareGlobals, 3, 1) \
   F(DeclareContextSlot, 4, 1) \
-  F(InitializeVarGlobal, -1 /* 2 or 3 */, 1) \
-  F(InitializeConstGlobal, 2, 1) \
+  F(InitializeVarGlobal, -1 /* 3 or 4 */, 1) \
+  F(InitializeConstGlobal, 3, 1) \
   F(InitializeConstContextSlot, 3, 1) \
   F(OptimizeObjectForAddingMultipleProperties, 2, 1) \
   \
diff --git a/src/scopes.cc b/src/scopes.cc
index d5a7a9f..25921fa 100644
--- a/src/scopes.cc
+++ b/src/scopes.cc
@@ -35,6 +35,8 @@
 
 #include "allocation-inl.h"
 
+#include "debug.h"
+
 namespace v8 {
 namespace internal {
 
@@ -202,6 +204,7 @@ void Scope::SetDefaults(Type type,
   scope_calls_eval_ = false;
   // Inherit the strict mode from the parent scope.
   strict_mode_ = (outer_scope != NULL) && outer_scope->strict_mode_;
+  qml_mode_ = (outer_scope != NULL) && outer_scope->qml_mode_;
   outer_scope_calls_eval_ = false;
   outer_scope_calls_non_strict_eval_ = false;
   inner_scope_calls_eval_ = false;
@@ -923,6 +926,25 @@ void Scope::ResolveVariable(Scope* global_scope,
         ASSERT(global_scope != NULL);
         var = global_scope->DeclareGlobal(proxy->name());
 
+        if (qml_mode_) {
+          Handle<GlobalObject> global = Isolate::Current()->global();
+
+#ifdef ENABLE_DEBUGGER_SUPPORT
+          if (Isolate::Current()->debug()->IsLoaded() && Isolate::Current()->debug()->InDebugger()) {
+            //Get the context before the debugger was entered.
+            SaveContext *save = Isolate::Current()->save_context();
+            while (save != NULL && *save->context() == *Isolate::Current()->debug()->debug_context())
+              save = save->prev();
+
+            global = Handle<GlobalObject>(save->context()->global());
+          }
+#endif
+
+          if (!global->HasProperty(*(proxy->name()))) {
+            var->set_is_qml_global(true);
+          }
+        }
+
       } else if (scope_inside_with_) {
         // If we are inside a with statement we give up and look up
         // the variable at runtime.
@@ -944,6 +966,25 @@ void Scope::ResolveVariable(Scope* global_scope,
         if (context->GlobalIfNotShadowedByEval(proxy->name())) {
           var = NonLocal(proxy->name(), Variable::DYNAMIC_GLOBAL);
 
+          if (qml_mode_) {
+            Handle<GlobalObject> global = Isolate::Current()->global();
+
+#ifdef ENABLE_DEBUGGER_SUPPORT
+            if (Isolate::Current()->debug()->IsLoaded() && Isolate::Current()->debug()->InDebugger()) {
+              //Get the context before the debugger was entered.
+              SaveContext *save = Isolate::Current()->save_context();
+              while (save != NULL && *save->context() == *Isolate::Current()->debug()->debug_context())
+                save = save->prev();
+
+              global = Handle<GlobalObject>(save->context()->global());
+            }
+#endif
+
+            if (qml_mode_ && !global->HasProperty(*(proxy->name()))) {
+              var->set_is_qml_global(true);
+            }
+          }
+
         } else {
           var = NonLocal(proxy->name(), Variable::DYNAMIC);
         }
@@ -954,6 +995,26 @@ void Scope::ResolveVariable(Scope* global_scope,
         // variable is global unless it is shadowed by eval-introduced
         // variables.
         var = NonLocal(proxy->name(), Variable::DYNAMIC_GLOBAL);
+
+        if (qml_mode_) {
+          Handle<GlobalObject> global = Isolate::Current()->global();
+
+#ifdef ENABLE_DEBUGGER_SUPPORT
+          if (Isolate::Current()->debug()->IsLoaded() && Isolate::Current()->debug()->InDebugger()) {
+            //Get the context before the debugger was entered.
+            SaveContext *save = Isolate::Current()->save_context();
+            while (save != NULL && *save->context() == *Isolate::Current()->debug()->debug_context())
+              save = save->prev();
+
+            global = Handle<GlobalObject>(save->context()->global());
+          }
+#endif
+
+          if (qml_mode_ && !global->HasProperty(*(proxy->name()))) {
+            var->set_is_qml_global(true);
+          }
+        }
+
       }
     }
   }
diff --git a/src/scopes.h b/src/scopes.h
index 2917a63..0f1ed6d 100644
--- a/src/scopes.h
+++ b/src/scopes.h
@@ -206,6 +206,11 @@ class Scope: public ZoneObject {
     strict_mode_ = FLAG_strict_mode;
   }
 
+  // Enable qml mode for this scope
+  void EnableQmlMode() {
+    qml_mode_ = true;
+  }
+
   // ---------------------------------------------------------------------------
   // Predicates.
 
@@ -216,6 +221,7 @@ class Scope: public ZoneObject {
   bool is_catch_scope() const { return type_ == CATCH_SCOPE; }
   bool is_block_scope() const { return type_ == BLOCK_SCOPE; }
   bool is_strict_mode() const { return strict_mode_; }
+  bool is_qml_mode() const { return qml_mode_; }
   bool is_strict_mode_eval_scope() const {
     return is_eval_scope() && is_strict_mode();
   }
@@ -381,6 +387,8 @@ class Scope: public ZoneObject {
   bool scope_calls_eval_;
   // This scope is a strict mode scope.
   bool strict_mode_;
+  // This scope is a qml mode scope.
+  bool qml_mode_;
 
   // Computed via PropagateScopeInfo.
   bool outer_scope_calls_eval_;
diff --git a/src/variables.cc b/src/variables.cc
index 971061b..da07620 100644
--- a/src/variables.cc
+++ b/src/variables.cc
@@ -67,7 +67,8 @@ Variable::Variable(Scope* scope,
     local_if_not_shadowed_(NULL),
     is_valid_LHS_(is_valid_LHS),
     is_accessed_from_inner_scope_(false),
-    is_used_(false) {
+    is_used_(false),
+    is_qml_global_(false) {
   // names must be canonicalized for fast equality checks
   ASSERT(name->IsSymbol());
 }
diff --git a/src/variables.h b/src/variables.h
index 56c8dab..4d27f98 100644
--- a/src/variables.h
+++ b/src/variables.h
@@ -174,6 +174,8 @@ class Variable: public ZoneObject {
     index_ = index;
   }
 
+  bool is_qml_global() const { return is_qml_global_; }
+  void set_is_qml_global(bool is_qml_global) { is_qml_global_ = is_qml_global; }
  private:
   Scope* scope_;
   Handle<String> name_;
@@ -190,6 +192,9 @@ class Variable: public ZoneObject {
   // Usage info.
   bool is_accessed_from_inner_scope_;  // set by variable resolver
   bool is_used_;
+
+  // QML info
+  bool is_qml_global_;
 };
 
 
diff --git a/src/x64/code-stubs-x64.cc b/src/x64/code-stubs-x64.cc
index 8d9dba7..6ab12fc 100644
--- a/src/x64/code-stubs-x64.cc
+++ b/src/x64/code-stubs-x64.cc
@@ -139,6 +139,10 @@ void FastNewContextStub::Generate(MacroAssembler* masm) {
   __ movq(rbx, Operand(rsi, Context::SlotOffset(Context::GLOBAL_INDEX)));
   __ movq(Operand(rax, Context::SlotOffset(Context::GLOBAL_INDEX)), rbx);
 
+  // Copy the qmlglobal object from the previous context.
+  __ movq(rbx, Operand(rsi, Context::SlotOffset(Context::QML_GLOBAL_INDEX)));
+  __ movq(Operand(rax, Context::SlotOffset(Context::QML_GLOBAL_INDEX)), rbx);
+
   // Initialize the rest of the slots to undefined.
   __ LoadRoot(rbx, Heap::kUndefinedValueRootIndex);
   for (int i = Context::MIN_CONTEXT_SLOTS; i < length; i++) {
diff --git a/src/x64/full-codegen-x64.cc b/src/x64/full-codegen-x64.cc
index 1d9b8ff..08b3872 100644
--- a/src/x64/full-codegen-x64.cc
+++ b/src/x64/full-codegen-x64.cc
@@ -173,12 +173,13 @@ void FullCodeGenerator::Generate(CompilationInfo* info) {
 
   // Possibly allocate a local context.
   int heap_slots = info->scope()->num_heap_slots() - Context::MIN_CONTEXT_SLOTS;
-  if (heap_slots > 0) {
+  if (heap_slots > 0 ||
+      (scope()->is_qml_mode() && scope()->is_global_scope())) {
     Comment cmnt(masm_, "[ Allocate local context");
     // Argument to NewContext is the function, which is still in rdi.
     __ push(rdi);
     if (heap_slots <= FastNewContextStub::kMaximumSlots) {
-      FastNewContextStub stub(heap_slots);
+      FastNewContextStub stub((heap_slots < 0)?0:heap_slots);
       __ CallStub(&stub);
     } else {
       __ CallRuntime(Runtime::kNewFunctionContext, 1);
@@ -1129,10 +1130,10 @@ void FullCodeGenerator::EmitLoadGlobalCheckExtensions(Variable* var,
 
   // All extension objects were empty and it is safe to use a global
   // load IC call.
-  __ movq(rax, GlobalObjectOperand());
+  __ movq(rax, var->is_qml_global() ? QmlGlobalObjectOperand() : GlobalObjectOperand());
   __ Move(rcx, var->name());
   Handle<Code> ic = isolate()->builtins()->LoadIC_Initialize();
-  RelocInfo::Mode mode = (typeof_state == INSIDE_TYPEOF)
+  RelocInfo::Mode mode = (typeof_state == INSIDE_TYPEOF || var->is_qml_global())
       ? RelocInfo::CODE_TARGET
       : RelocInfo::CODE_TARGET_CONTEXT;
   __ call(ic, mode);
@@ -1207,9 +1208,9 @@ void FullCodeGenerator::EmitVariableLoad(VariableProxy* proxy) {
       // Use inline caching. Variable name is passed in rcx and the global
       // object on the stack.
       __ Move(rcx, var->name());
-      __ movq(rax, GlobalObjectOperand());
+      __ movq(rax, var->is_qml_global() ? QmlGlobalObjectOperand() : GlobalObjectOperand());
       Handle<Code> ic = isolate()->builtins()->LoadIC_Initialize();
-      __ call(ic, RelocInfo::CODE_TARGET_CONTEXT);
+      __ call(ic, var->is_qml_global() ? RelocInfo::CODE_TARGET : RelocInfo::CODE_TARGET_CONTEXT);
       context()->Plug(rax);
       break;
     }
@@ -1750,7 +1751,7 @@ void FullCodeGenerator::EmitVariableAssignment(Variable* var,
   if (var->IsUnallocated()) {
     // Global var, const, or let.
     __ Move(rcx, var->name());
-    __ movq(rdx, GlobalObjectOperand());
+    __ movq(rdx, var->is_qml_global() ? QmlGlobalObjectOperand() : GlobalObjectOperand());
     Handle<Code> ic = is_strict_mode()
         ? isolate()->builtins()->StoreIC_Initialize_Strict()
         : isolate()->builtins()->StoreIC_Initialize();
@@ -2034,9 +2035,12 @@ void FullCodeGenerator::EmitResolvePossiblyDirectEval(ResolveEvalFlag flag,
   }
   __ Push(Smi::FromInt(strict_mode));
 
+  // Push the qml mode flag
+  __ Push(Smi::FromInt(is_qml_mode()));
+
   __ CallRuntime(flag == SKIP_CONTEXT_LOOKUP
                  ? Runtime::kResolvePossiblyDirectEvalNoLookup
-                 : Runtime::kResolvePossiblyDirectEval, 4);
+                 : Runtime::kResolvePossiblyDirectEval, 5);
 }
 
 
@@ -2105,8 +2109,8 @@ void FullCodeGenerator::VisitCall(Call* expr) {
   } else if (proxy != NULL && proxy->var()->IsUnallocated()) {
     // Call to a global variable.  Push global object as receiver for the
     // call IC lookup.
-    __ push(GlobalObjectOperand());
-    EmitCallWithIC(expr, proxy->name(), RelocInfo::CODE_TARGET_CONTEXT);
+    __ push(proxy->var()->is_qml_global() ? QmlGlobalObjectOperand() : GlobalObjectOperand());
+    EmitCallWithIC(expr, proxy->name(), proxy->var()->is_qml_global() ? RelocInfo::CODE_TARGET : RelocInfo::CODE_TARGET_CONTEXT);
   } else if (proxy != NULL && proxy->var()->IsLookupSlot()) {
     // Call to a lookup slot (dynamically introduced variable).
     Label slow, done;
@@ -3552,7 +3556,7 @@ void FullCodeGenerator::VisitUnaryOperation(UnaryOperation* expr) {
         // but "delete this" is allowed.
         ASSERT(strict_mode_flag() == kNonStrictMode || var->is_this());
         if (var->IsUnallocated()) {
-          __ push(GlobalObjectOperand());
+          __ push(var->is_qml_global() ? QmlGlobalObjectOperand() : GlobalObjectOperand());
           __ Push(var->name());
           __ Push(Smi::FromInt(kNonStrictMode));
           __ InvokeBuiltin(Builtins::DELETE, CALL_FUNCTION);
@@ -3850,7 +3854,7 @@ void FullCodeGenerator::VisitForTypeofValue(Expression* expr) {
   if (proxy != NULL && proxy->var()->IsUnallocated()) {
     Comment cmnt(masm_, "Global variable");
     __ Move(rcx, proxy->name());
-    __ movq(rax, GlobalObjectOperand());
+    __ movq(rax, proxy->var()->is_qml_global() ? QmlGlobalObjectOperand() : GlobalObjectOperand());
     Handle<Code> ic = isolate()->builtins()->LoadIC_Initialize();
     // Use a regular load, not a contextual load, to avoid a reference
     // error.
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index 45aaad7..08050f0 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -196,12 +196,13 @@ bool LCodeGen::GeneratePrologue() {
 
   // Possibly allocate a local context.
   int heap_slots = scope()->num_heap_slots() - Context::MIN_CONTEXT_SLOTS;
-  if (heap_slots > 0) {
+  if (heap_slots > 0 ||
+      (scope()->is_qml_mode() && scope()->is_global_scope())) {
     Comment(";;; Allocate local context");
     // Argument to NewContext is the function, which is still in rdi.
     __ push(rdi);
     if (heap_slots <= FastNewContextStub::kMaximumSlots) {
-      FastNewContextStub stub(heap_slots);
+      FastNewContextStub stub((heap_slots < 0)?0:heap_slots);
       __ CallStub(&stub);
     } else {
       __ CallRuntime(Runtime::kNewFunctionContext, 1);
@@ -2581,7 +2582,7 @@ void LCodeGen::DoOuterContext(LOuterContext* instr) {
 
 void LCodeGen::DoGlobalObject(LGlobalObject* instr) {
   Register result = ToRegister(instr->result());
-  __ movq(result, GlobalObjectOperand());
+  __ movq(result, instr->qml_global()?QmlGlobalObjectOperand():GlobalObjectOperand());
 }
 
 
diff --git a/src/x64/lithium-x64.cc b/src/x64/lithium-x64.cc
index a67a593..a243fef 100644
--- a/src/x64/lithium-x64.cc
+++ b/src/x64/lithium-x64.cc
@@ -1117,7 +1117,7 @@ LInstruction* LChunkBuilder::DoOuterContext(HOuterContext* instr) {
 
 
 LInstruction* LChunkBuilder::DoGlobalObject(HGlobalObject* instr) {
-  return DefineAsRegister(new LGlobalObject);
+  return DefineAsRegister(new LGlobalObject(instr->qml_global()));
 }
 
 
diff --git a/src/x64/lithium-x64.h b/src/x64/lithium-x64.h
index d43a86a..cf89181 100644
--- a/src/x64/lithium-x64.h
+++ b/src/x64/lithium-x64.h
@@ -1301,7 +1301,13 @@ class LOuterContext: public LTemplateInstruction<1, 1, 0> {
 
 class LGlobalObject: public LTemplateInstruction<1, 0, 0> {
  public:
+  explicit LGlobalObject(bool qml_global) : qml_global_(qml_global) {}
+
   DECLARE_CONCRETE_INSTRUCTION(GlobalObject, "global-object")
+  
+  bool qml_global() { return qml_global_; }
+ private:
+  bool qml_global_;
 };
 
 
diff --git a/src/x64/macro-assembler-x64.h b/src/x64/macro-assembler-x64.h
index 7e0ba00..744ce20 100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -1413,6 +1413,11 @@ static inline Operand GlobalObjectOperand() {
 }
 
 
+static inline Operand QmlGlobalObjectOperand() {
+  return ContextOperand(rsi, Context::QML_GLOBAL_INDEX);
+}
+
+
 // Provides access to exit frame stack space (not GCed).
 static inline Operand StackSpaceOperand(int index) {
 #ifdef _WIN64
-- 
1.7.4.4