Merge remote-tracking branch 'origin/wip/new-backend' into dev

 Conflicts:
	src/qml/compiler/qv4isel_moth.cpp
	src/qml/compiler/qv4jsir_p.h
	src/qml/jsruntime/qv4engine_p.h
	src/qml/jsruntime/qv4vme_moth.cpp
	tests/auto/qml/qml.pro

Change-Id: Ia7b6ec24c7fcbcbb1786d9e798d2df294020ae37

8 files changed, 142 insertions, 187 deletions

diff --git a/src/plugins/qmltooling/qmldbg_debugger/qv4datacollector.cpp b/src/plugins/qmltooling/qmldbg_debugger/qv4datacollector.cpp
index 8ff0a3ca64..a538956e8e 100644
--- a/src/plugins/qmltooling/qmldbg_debugger/qv4datacollector.cpp
+++ b/src/plugins/qmltooling/qmldbg_debugger/qv4datacollector.cpp
@@ -55,47 +55,43 @@
 
 QT_BEGIN_NAMESPACE
 
-QV4::SimpleCallContext *QV4DataCollector::findContext(int frame)
+QV4::CppStackFrame *QV4DataCollector::findFrame(int frame)
 {
-    QV4::ExecutionContext *ctx = engine()->currentContext;
-    while (ctx) {
-        QV4::SimpleCallContext *cCtxt = ctx->asSimpleCallContext();
-        if (cCtxt && cCtxt->d()->v4Function) {
-            if (frame < 1)
-                return cCtxt;
-            --frame;
-        }
-        ctx = engine()->parentContext(ctx);
+    QV4::CppStackFrame *f = engine()->currentStackFrame;
+    while (f && frame) {
+        --frame;
+        f = f->parent;
     }
+    return f;
+}
 
-    return 0;
+QV4::Heap::ExecutionContext *QV4DataCollector::findContext(int frame)
+{
+    QV4::CppStackFrame *f = findFrame(frame);
+
+    return f ? f->context()->d() : 0;
 }
 
-QV4::Heap::SimpleCallContext *QV4DataCollector::findScope(QV4::ExecutionContext *ctxt, int scope)
+QV4::Heap::CallContext *QV4DataCollector::findScope(QV4::Heap::ExecutionContext *ctx, int scope)
 {
-    if (!ctxt)
+    if (!ctx)
         return 0;
 
-    QV4::Scope s(ctxt);
-    QV4::ScopedContext ctx(s, ctxt);
     for (; scope > 0 && ctx; --scope)
-        ctx = ctx->d()->outer;
+        ctx = ctx->outer;
 
-    return (ctx && ctx->d()) ? ctx->asSimpleCallContext()->d() : 0;
+    return (ctx && ctx->type == QV4::Heap::ExecutionContext::Type_CallContext) ?
+                static_cast<QV4::Heap::CallContext *>(ctx) : 0;
 }
 
 QVector<QV4::Heap::ExecutionContext::ContextType> QV4DataCollector::getScopeTypes(int frame)
 {
     QVector<QV4::Heap::ExecutionContext::ContextType> types;
 
-    QV4::Scope scope(engine());
-    QV4::SimpleCallContext *sctxt = findContext(frame);
-    if (!sctxt || sctxt->d()->type < QV4::Heap::ExecutionContext::Type_QmlContext)
-        return types;
+    QV4::Heap::ExecutionContext *it = findFrame(frame)->context()->d();
 
-    QV4::ScopedContext it(scope, sctxt);
-    for (; it; it = it->d()->outer)
-        types.append(QV4::Heap::ExecutionContext::ContextType(it->d()->type));
+    for (; it; it = it->outer)
+        types.append(QV4::Heap::ExecutionContext::ContextType(it->type));
 
     return types;
 }
@@ -109,7 +105,6 @@ int QV4DataCollector::encodeScopeType(QV4::Heap::ExecutionContext::ContextType s
         return 4;
     case QV4::Heap::ExecutionContext::Type_WithContext:
         return 2;
-    case QV4::Heap::ExecutionContext::Type_SimpleCallContext:
     case QV4::Heap::ExecutionContext::Type_CallContext:
         return 1;
     case QV4::Heap::ExecutionContext::Type_QmlContext:
@@ -267,27 +262,17 @@ bool QV4DataCollector::collectScope(QJsonObject *dict, int frameNr, int scopeNr)
     QStringList names;
 
     QV4::Scope scope(engine());
+
     QV4::Scoped<QV4::CallContext> ctxt(scope, findScope(findContext(frameNr), scopeNr));
     if (!ctxt)
         return false;
 
     Refs collectedRefs;
     QV4::ScopedValue v(scope);
-    int nFormals = ctxt->formalCount();
-    for (unsigned i = 0, ei = nFormals; i != ei; ++i) {
-        QString qName;
-        if (QV4::Identifier *name = ctxt->formals()[nFormals - i - 1])
-            qName = name->string;
-        names.append(qName);
-        v = ctxt->argument(i);
-        collectedRefs.append(collect(v));
-    }
-
-    for (unsigned i = 0, ei = ctxt->variableCount(); i != ei; ++i) {
-        QString qName;
-        if (QV4::Identifier *name = ctxt->variables()[i])
-            qName = name->string;
-        names.append(qName);
+    QV4::InternalClass *ic = ctxt->internalClass();
+    for (uint i = 0; i < ic->size; ++i) {
+        QString name = ic->nameMap[i]->string;
+        names.append(name);
         v = ctxt->d()->locals[i];
         collectedRefs.append(collect(v));
     }
@@ -338,7 +323,7 @@ QJsonObject QV4DataCollector::buildFrame(const QV4::StackFrame &stackFrame, int
     QV4::Scope scope(engine());
     QV4::ScopedContext ctxt(scope, findContext(frameNr));
     while (ctxt) {
-        if (QV4::SimpleCallContext *cCtxt = ctxt->asSimpleCallContext()) {
+        if (QV4::CallContext *cCtxt = ctxt->asCallContext()) {
             if (cCtxt->d()->activation)
                 break;
         }
@@ -346,7 +331,7 @@ QJsonObject QV4DataCollector::buildFrame(const QV4::StackFrame &stackFrame, int
     }
 
     if (ctxt) {
-        QV4::ScopedValue o(scope, ctxt->asSimpleCallContext()->d()->activation);
+        QV4::ScopedValue o(scope, ctxt->d()->activation);
         frame[QLatin1String("receiver")] = toRef(collect(o));
     }
 
diff --git a/src/plugins/qmltooling/qmldbg_debugger/qv4datacollector.h b/src/plugins/qmltooling/qmldbg_debugger/qv4datacollector.h
index de12e8d527..87be009de5 100644
--- a/src/plugins/qmltooling/qmldbg_debugger/qv4datacollector.h
+++ b/src/plugins/qmltooling/qmldbg_debugger/qv4datacollector.h
@@ -58,11 +58,12 @@ public:
     typedef uint Ref;
     typedef QVector<uint> Refs;
 
-    static QV4::Heap::SimpleCallContext *findScope(QV4::ExecutionContext *ctxt, int scope);
+    static QV4::Heap::CallContext *findScope(QV4::Heap::ExecutionContext *ctxt, int scope);
     static int encodeScopeType(QV4::Heap::ExecutionContext::ContextType scopeType);
 
     QVector<QV4::Heap::ExecutionContext::ContextType> getScopeTypes(int frame);
-    QV4::SimpleCallContext *findContext(int frame);
+    QV4::Heap::ExecutionContext *findContext(int frame);
+    QV4::CppStackFrame *findFrame(int frame);
 
     QV4DataCollector(QV4::ExecutionEngine *engine);
 
diff --git a/src/plugins/qmltooling/qmldbg_debugger/qv4debugger.cpp b/src/plugins/qmltooling/qmldbg_debugger/qv4debugger.cpp
index b82df9c6a9..1581cf637d 100644
--- a/src/plugins/qmltooling/qmldbg_debugger/qv4debugger.cpp
+++ b/src/plugins/qmltooling/qmldbg_debugger/qv4debugger.cpp
@@ -115,7 +115,7 @@ void QV4Debugger::resume(Speed speed)
     if (!m_returnedValue.isUndefined())
         m_returnedValue.set(m_engine, QV4::Encode::undefined());
 
-    m_currentContext.set(m_engine, *m_engine->currentContext);
+    m_currentFrame = m_engine->currentStackFrame;
     m_stepping = speed;
     m_runningCondition.wakeAll();
 }
@@ -158,7 +158,7 @@ QV4Debugger::ExecutionState QV4Debugger::currentExecutionState() const
 {
     ExecutionState state;
     state.fileName = getFunction()->sourceFile();
-    state.lineNumber = engine()->current->lineNumber;
+    state.lineNumber = engine()->currentStackFrame->lineNumber();
 
     return state;
 }
@@ -187,7 +187,7 @@ void QV4Debugger::maybeBreakAtInstruction()
 
     switch (m_stepping) {
     case StepOver:
-        if (m_currentContext.asManaged()->d() != m_engine->current)
+        if (m_currentFrame != m_engine->currentStackFrame)
             break;
         // fall through
     case StepIn:
@@ -203,7 +203,8 @@ void QV4Debugger::maybeBreakAtInstruction()
         pauseAndWait(PauseRequest);
     } else if (m_haveBreakPoints) {
         if (QV4::Function *f = getFunction()) {
-            const int lineNumber = engine()->current->lineNumber;
+            // lineNumber will be negative for Ret instructions, so those won't match
+            const int lineNumber = engine()->currentStackFrame->lineNumber();
             if (reallyHitTheBreakPoint(f->sourceFile(), lineNumber))
                 pauseAndWait(BreakPointHit);
         }
@@ -216,9 +217,8 @@ void QV4Debugger::enteringFunction()
         return;
     QMutexLocker locker(&m_lock);
 
-    if (m_stepping == StepIn) {
-        m_currentContext.set(m_engine, *m_engine->currentContext);
-    }
+    if (m_stepping == StepIn)
+        m_currentFrame = m_engine->currentStackFrame;
 }
 
 void QV4Debugger::leavingFunction(const QV4::ReturnedValue &retVal)
@@ -229,13 +229,8 @@ void QV4Debugger::leavingFunction(const QV4::ReturnedValue &retVal)
 
     QMutexLocker locker(&m_lock);
 
-    if (m_stepping != NotStepping && m_currentContext.asManaged()->d() == m_engine->current) {
-        if (QV4::ExecutionContext *parentContext
-                = m_engine->parentContext(m_engine->currentContext)) {
-            m_currentContext.set(m_engine, *parentContext);
-        } else {
-            m_currentContext.clear();
-        }
+    if (m_stepping != NotStepping && m_currentFrame == m_engine->currentStackFrame) {
+        m_currentFrame = m_currentFrame->parent;
         m_stepping = StepOver;
         m_returnedValue.set(m_engine, retVal);
     }
@@ -255,10 +250,8 @@ void QV4Debugger::aboutToThrow()
 
 QV4::Function *QV4Debugger::getFunction() const
 {
-    QV4::Scope scope(m_engine);
-    QV4::ExecutionContext *context = m_engine->currentContext;
-    if (QV4::Function *function = context->getFunction())
-        return function;
+    if (m_engine->currentStackFrame)
+        return m_engine->currentStackFrame->v4Function;
     else
         return m_engine->globalCode;
 }
diff --git a/src/plugins/qmltooling/qmldbg_debugger/qv4debugger.h b/src/plugins/qmltooling/qmldbg_debugger/qv4debugger.h
index 06014302e6..4a755f2b72 100644
--- a/src/plugins/qmltooling/qmldbg_debugger/qv4debugger.h
+++ b/src/plugins/qmltooling/qmldbg_debugger/qv4debugger.h
@@ -150,7 +150,7 @@ private:
     void runJobUnpaused();
 
     QV4::ExecutionEngine *m_engine;
-    QV4::PersistentValue m_currentContext;
+    QV4::CppStackFrame *m_currentFrame = 0;
     QMutex m_lock;
     QWaitCondition m_runningCondition;
     State m_state;
diff --git a/src/plugins/qmltooling/qmldbg_debugger/qv4debuggeragent.cpp b/src/plugins/qmltooling/qmldbg_debugger/qv4debuggeragent.cpp
index 9a34d5770a..87e75c49b5 100644
--- a/src/plugins/qmltooling/qmldbg_debugger/qv4debuggeragent.cpp
+++ b/src/plugins/qmltooling/qmldbg_debugger/qv4debuggeragent.cpp
@@ -79,20 +79,19 @@ void QV4DebuggerAgent::debuggerPaused(QV4Debugger *debugger, QV4Debugger::PauseR
     case QV4Debugger::PauseRequest:
     case QV4Debugger::BreakPointHit: {
         event.insert(QStringLiteral("event"), QStringLiteral("break"));
-        QVector<QV4::StackFrame> frames = debugger->stackTrace(1);
-        if (frames.isEmpty())
+        QV4::CppStackFrame *frame = debugger->engine()->currentStackFrame;
+        if (!frame)
             break;
 
-        const QV4::StackFrame &topFrame = frames.first();
-        body.insert(QStringLiteral("invocationText"), topFrame.function);
-        body.insert(QStringLiteral("sourceLine"), topFrame.line - 1);
-        if (topFrame.column > 0)
-            body.insert(QStringLiteral("sourceColumn"), topFrame.column);
+        body.insert(QStringLiteral("invocationText"), frame->function());
+        body.insert(QStringLiteral("sourceLine"), qAbs(frame->lineNumber()) - 1);
+//        if (frame->column > 0)
+//            body.insert(QStringLiteral("sourceColumn"), frame->column);
         QJsonArray breakPoints;
-        foreach (int breakPointId, breakPointIds(topFrame.source, topFrame.line))
+        foreach (int breakPointId, breakPointIds(frame->source(), frame->lineNumber()))
             breakPoints.push_back(breakPointId);
         body.insert(QStringLiteral("breakpoints"), breakPoints);
-        script.insert(QStringLiteral("name"), topFrame.source);
+        script.insert(QStringLiteral("name"), frame->source());
     } break;
     case QV4Debugger::Throwing:
         // TODO: complete this!
diff --git a/src/plugins/qmltooling/qmldbg_debugger/qv4debugjob.cpp b/src/plugins/qmltooling/qmldbg_debugger/qv4debugjob.cpp
index d57d7e7406..6f254c9e28 100644
--- a/src/plugins/qmltooling/qmldbg_debugger/qv4debugjob.cpp
+++ b/src/plugins/qmltooling/qmldbg_debugger/qv4debugjob.cpp
@@ -44,6 +44,7 @@
 #include <private/qv4qmlcontext_p.h>
 #include <private/qv4qobjectwrapper_p.h>
 #include <private/qqmldebugservice_p.h>
+#include <private/qv4jscall_p.h>
 
 #include <QtQml/qqmlengine.h>
 
@@ -63,26 +64,21 @@ void JavaScriptJob::run()
 {
     QV4::Scope scope(engine);
 
-    QV4::ExecutionContextSaver saver(scope);
-
-    QV4::ExecutionContext *ctx = engine->currentContext;
+    QV4::ScopedContext ctx(scope, engine->currentStackFrame ? engine->currentContext()
+                                                            : engine->rootContext());
     QObject scopeObject;
 
-    if (frameNr > 0) {
-        for (int i = 0; i < frameNr; ++i) {
-            ctx = engine->parentContext(ctx);
-        }
-        engine->pushContext(ctx);
-        ctx = engine->currentContext;
-    }
+    QV4::CppStackFrame *frame = engine->currentStackFrame;
+
+    for (int i = 0; frame && i < frameNr; ++i)
+        frame = frame->parent;
+    if (frameNr > 0 && frame)
+        ctx = static_cast<QV4::ExecutionContext *>(&frame->jsFrame->context);
 
     if (context >= 0) {
         QQmlContext *extraContext = qmlContext(QQmlDebugService::objectForId(context));
-        if (extraContext) {
-            engine->pushContext(QV4::QmlContext::create(ctx, QQmlContextData::get(extraContext),
-                                                        &scopeObject));
-            ctx = engine->currentContext;
-        }
+        if (extraContext)
+            ctx = QV4::QmlContext::create(ctx, QQmlContextData::get(extraContext), &scopeObject);
     } else if (frameNr < 0) { // Use QML context if available
         QQmlEngine *qmlEngine = engine->qmlEngine();
         if (qmlEngine) {
@@ -102,18 +98,15 @@ void JavaScriptJob::run()
                     }
                 }
             }
-            if (!engine->qmlContext()) {
-                engine->pushContext(QV4::QmlContext::create(ctx, QQmlContextData::get(qmlRootContext),
-                                                       &scopeObject));
-                ctx = engine->currentContext;
-            }
-            engine->pushContext(ctx->newWithContext(withContext->toObject(engine)));
-            ctx = engine->currentContext;
+            if (!engine->qmlContext())
+                ctx = QV4::QmlContext::create(ctx, QQmlContextData::get(qmlRootContext), &scopeObject);
         }
     }
 
-    QV4::Script script(ctx, this->script);
-    script.strictMode = ctx->d()->strictMode;
+    QV4::Script script(ctx, QV4::Compiler::EvalCode, this->script);
+    if (const QV4::Function *function = frame ? frame->v4Function : engine->globalCode)
+        script.strictMode = function->isStrict();
+
     // In order for property lookups in QML to work, we need to disable fast v4 lookups. That
     // is a side-effect of inheritContext.
     script.inheritContext = true;
@@ -214,12 +207,15 @@ void ValueLookupJob::run()
     // set if the engine is currently executing QML code.
     QScopedPointer<QObject> scopeObject;
     QV4::ExecutionEngine *engine = collector->engine();
+    QV4::Scope scope(engine);
+    QV4::Heap::ExecutionContext *qmlContext = 0;
     if (engine->qmlEngine() && !engine->qmlContext()) {
         scopeObject.reset(new QObject);
-        engine->pushContext(QV4::QmlContext::create(engine->currentContext,
+        qmlContext = QV4::QmlContext::create(engine->currentContext(),
                                 QQmlContextData::get(engine->qmlEngine()->rootContext()),
-                                scopeObject.data()));
+                                scopeObject.data());
     }
+    QV4::ScopedStackFrame frame(scope, qmlContext);
     for (const QJsonValue &handle : handles) {
         QV4DataCollector::Ref ref = handle.toInt();
         if (!collector->isValidRef(ref)) {
@@ -229,8 +225,6 @@ void ValueLookupJob::run()
         result[QString::number(ref)] = collector->lookupRef(ref, true);
     }
     flushRedundantRefs();
-    if (scopeObject)
-        engine->popContext();
 }
 
 const QString &ValueLookupJob::exceptionMessage() const
diff --git a/src/plugins/qmltooling/qmldbg_debugger/qv4debugservice.cpp b/src/plugins/qmltooling/qmldbg_debugger/qv4debugservice.cpp
index fe00ed1e28..fca811cb28 100644
--- a/src/plugins/qmltooling/qmldbg_debugger/qv4debugservice.cpp
+++ b/src/plugins/qmltooling/qmldbg_debugger/qv4debugservice.cpp
@@ -42,7 +42,6 @@
 #include "qqmlengine.h"
 
 #include <private/qv4engine_p.h>
-#include <private/qv4isel_moth_p.h>
 #include <private/qv4function_p.h>
 #include <private/qqmldebugconnector_p.h>
 #include <private/qv8engine_p.h>
@@ -706,7 +705,6 @@ void QV4DebugServiceImpl::engineAdded(QJSEngine *engine)
         QV4::ExecutionEngine *ee = QV8Engine::getV4(engine->handle());
         if (QQmlDebugConnector *server = QQmlDebugConnector::instance()) {
             if (ee) {
-                ee->iselFactory.reset(new QV4::Moth::ISelFactory);
                 QV4Debugger *debugger = new QV4Debugger(ee);
                 if (state() == Enabled)
                     ee->setDebugger(debugger);
diff --git a/src/plugins/qmltooling/qmldbg_nativedebugger/qqmlnativedebugservice.cpp b/src/plugins/qmltooling/qmldbg_nativedebugger/qqmlnativedebugservice.cpp
index cff1728f49..eeedb59ce6 100644
--- a/src/plugins/qmltooling/qmldbg_nativedebugger/qqmlnativedebugservice.cpp
+++ b/src/plugins/qmltooling/qmldbg_nativedebugger/qqmlnativedebugservice.cpp
@@ -49,7 +49,6 @@
 #include <private/qv4objectiterator_p.h>
 #include <private/qv4identifier_p.h>
 #include <private/qv4runtime_p.h>
-#include <private/qv4isel_moth_p.h>
 #include <private/qqmldebugpacket_p.h>
 #include <private/qqmldebugserviceinterfaces_p.h>
 
@@ -208,7 +207,7 @@ private:
 
     void handleDebuggerDeleted(QObject *debugger);
 
-    void evaluateExpression(QV4::Scope &scope, const QString &expression);
+    QV4::ReturnedValue evaluateExpression(const QString &expression);
     bool checkCondition(const QString &expression);
 
     QStringList breakOnSignals;
@@ -230,7 +229,7 @@ private:
 
     QV4::ExecutionEngine *m_engine;
     QQmlNativeDebugServiceImpl *m_service;
-    QV4::PersistentValue m_currentContext;
+    QV4::CppStackFrame *m_currentFrame = 0;
     Speed m_stepping;
     bool m_pauseRequested;
     bool m_runningJob;
@@ -241,29 +240,31 @@ private:
 bool NativeDebugger::checkCondition(const QString &expression)
 {
     QV4::Scope scope(m_engine);
-    evaluateExpression(scope, expression);
-    return scope.result.booleanValue();
+    QV4::ScopedValue r(scope, evaluateExpression(expression));
+    return r->booleanValue();
 }
 
-void NativeDebugger::evaluateExpression(QV4::Scope &scope, const QString &expression)
+QV4::ReturnedValue NativeDebugger::evaluateExpression(const QString &expression)
 {
+    QV4::Scope scope(m_engine);
     m_runningJob = true;
 
-    QV4::ExecutionContextSaver saver(scope);
-
-    QV4::ExecutionContext *ctx = m_engine->currentContext;
-    m_engine->pushContext(ctx);
+    QV4::ExecutionContext *ctx = m_engine->currentStackFrame ? m_engine->currentContext()
+                                                             : m_engine->rootContext();
 
-    QV4::Script script(ctx, expression);
-    script.strictMode = ctx->d()->strictMode;
+    QV4::Script script(ctx, QV4::Compiler::EvalCode, expression);
+    if (const QV4::Function *function = m_engine->currentStackFrame
+            ? m_engine->currentStackFrame->v4Function : m_engine->globalCode)
+        script.strictMode = function->isStrict();
     // In order for property lookups in QML to work, we need to disable fast v4 lookups.
     // That is a side-effect of inheritContext.
     script.inheritContext = true;
     script.parse();
     if (!m_engine->hasException)
-        scope.result = script.run();
+        return script.run();
 
     m_runningJob = false;
+    return QV4::Encode::undefined();
 }
 
 NativeDebugger::NativeDebugger(QQmlNativeDebugServiceImpl *service, QV4::ExecutionEngine *engine)
@@ -314,19 +315,19 @@ void NativeDebugger::handleCommand(QJsonObject *response, const QString &cmd,
         handleContinue(response, NotStepping);
 }
 
-static QString encodeContext(QV4::ExecutionContext *executionContext)
+static QString encodeFrame(QV4::CppStackFrame *f)
 {
     QQmlDebugPacket ds;
-    ds << quintptr(executionContext);
+    ds << quintptr(f);
     return QString::fromLatin1(ds.data().toHex());
 }
 
-static void decodeContext(const QString &context, QV4::ExecutionContext **executionContext)
+static void decodeFrame(const QString &f, QV4::CppStackFrame **frame)
 {
-    quintptr rawContext;
-    QQmlDebugPacket ds(QByteArray::fromHex(context.toLatin1()));
-    ds >> rawContext;
-    *executionContext = reinterpret_cast<QV4::ExecutionContext *>(rawContext);
+    quintptr rawFrame;
+    QQmlDebugPacket ds(QByteArray::fromHex(f.toLatin1()));
+    ds >> rawFrame;
+    *frame = reinterpret_cast<QV4::CppStackFrame *>(rawFrame);
 }
 
 void NativeDebugger::handleBacktrace(QJsonObject *response, const QJsonObject &arguments)
@@ -334,25 +335,24 @@ void NativeDebugger::handleBacktrace(QJsonObject *response, const QJsonObject &a
     int limit = arguments.value(QLatin1String("limit")).toInt(0);
 
     QJsonArray frameArray;
-    QV4::ExecutionContext *executionContext = m_engine->currentContext;
-    for (int i  = 0; i < limit && executionContext; ++i) {
-        if (QV4::Function *function = executionContext->getFunction()) {
+    QV4::CppStackFrame *f= m_engine->currentStackFrame;
+    for (int i  = 0; i < limit && f; ++i) {
+        QV4::Function *function = f->v4Function;
 
-            QJsonObject frame;
-            frame.insert(QStringLiteral("language"), QStringLiteral("js"));
-            frame.insert(QStringLiteral("context"), encodeContext(executionContext));
+        QJsonObject frame;
+        frame.insert(QStringLiteral("language"), QStringLiteral("js"));
+        frame.insert(QStringLiteral("context"), encodeFrame(f));
 
-            if (QV4::Heap::String *functionName = function->name())
-                frame.insert(QStringLiteral("function"), functionName->toQString());
-            frame.insert(QStringLiteral("file"), function->sourceFile());
+        if (QV4::Heap::String *functionName = function->name())
+            frame.insert(QStringLiteral("function"), functionName->toQString());
+        frame.insert(QStringLiteral("file"), function->sourceFile());
 
-            int line = executionContext->d()->lineNumber;
-            frame.insert(QStringLiteral("line"), (line < 0 ? -line : line));
+        int line = f->lineNumber();
+        frame.insert(QStringLiteral("line"), (line < 0 ? -line : line));
 
-            frameArray.push_back(frame);
-        }
+        frameArray.push_back(frame);
 
-        executionContext = m_engine->parentContext(executionContext);
+        f = f->parent;
     }
 
     response->insert(QStringLiteral("frames"), frameArray);
@@ -457,15 +457,15 @@ void Collector::collect(QJsonArray *out, const QString &parentIName, const QStri
 void NativeDebugger::handleVariables(QJsonObject *response, const QJsonObject &arguments)
 {
     TRACE_PROTOCOL("Build variables");
-    QV4::ExecutionContext *executionContext = 0;
-    decodeContext(arguments.value(QLatin1String("context")).toString(), &executionContext);
-    if (!executionContext) {
-        setError(response, QStringLiteral("No execution context passed"));
+    QV4::CppStackFrame *frame = 0;
+    decodeFrame(arguments.value(QLatin1String("context")).toString(), &frame);
+    if (!frame) {
+        setError(response, QStringLiteral("No stack frame passed"));
         return;
     }
-    TRACE_PROTOCOL("Context: " << executionContext);
+    TRACE_PROTOCOL("Context: " << frame);
 
-    QV4::ExecutionEngine *engine = executionContext->engine();
+    QV4::ExecutionEngine *engine = frame->v4Function->internalClass->engine;
     if (!engine) {
         setError(response, QStringLiteral("No execution engine passed"));
         return;
@@ -481,28 +481,16 @@ void NativeDebugger::handleVariables(QJsonObject *response, const QJsonObject &a
     QJsonArray output;
     QV4::Scope scope(engine);
 
-    if (QV4::SimpleCallContext *callContext = executionContext->asSimpleCallContext()) {
-        QV4::Value thisObject = callContext->thisObject();
-        collector.collect(&output, QString(), QStringLiteral("this"), thisObject);
-        QV4::Identifier *const *variables = callContext->variables();
-        QV4::Identifier *const *formals = callContext->formals();
-        if (callContext->d()->type == QV4::Heap::ExecutionContext::Type_CallContext) {
-            QV4::CallContext *ctx = static_cast<QV4::CallContext *>(callContext);
-            for (unsigned i = 0, ei = ctx->variableCount(); i != ei; ++i) {
-                QString qName;
-                if (QV4::Identifier *name = variables[i])
-                    qName = name->string;
-                QV4::Value val = ctx->d()->locals[i];
-                collector.collect(&output, QString(), qName, val);
-            }
-        }
-        for (unsigned i = 0, ei = callContext->formalCount(); i != ei; ++i) {
-            QString qName;
-            if (QV4::Identifier *name = formals[i])
-                qName = name->string;
-            QV4::ReturnedValue rval = callContext->argument(i);
-            QV4::ScopedValue sval(scope, rval);
-            collector.collect(&output, QString(), qName, *sval);
+    QV4::ScopedValue thisObject(scope, frame->thisObject());
+    collector.collect(&output, QString(), QStringLiteral("this"), thisObject);
+    QV4::Scoped<QV4::CallContext> callContext(scope, frame->callContext());
+    if (callContext) {
+        QV4::InternalClass *ic = callContext->internalClass();
+        QV4::ScopedValue v(scope);
+        for (uint i = 0; i < ic->size; ++i) {
+            QString name = ic->nameMap[i]->string;
+            v = callContext->d()->locals[i];
+            collector.collect(&output, QString(), name, v);
         }
     }
 
@@ -512,15 +500,15 @@ void NativeDebugger::handleVariables(QJsonObject *response, const QJsonObject &a
 void NativeDebugger::handleExpressions(QJsonObject *response, const QJsonObject &arguments)
 {
     TRACE_PROTOCOL("Evaluate expressions");
-    QV4::ExecutionContext *executionContext = 0;
-    decodeContext(arguments.value(QLatin1String("context")).toString(), &executionContext);
-    if (!executionContext) {
-        setError(response, QStringLiteral("No execution context passed"));
+    QV4::CppStackFrame *frame = 0;
+    decodeFrame(arguments.value(QLatin1String("context")).toString(), &frame);
+    if (!frame) {
+        setError(response, QStringLiteral("No stack frame passed"));
         return;
     }
     TRACE_PROTOCOL("Context: " << executionContext);
 
-    QV4::ExecutionEngine *engine = executionContext->engine();
+    QV4::ExecutionEngine *engine = frame->v4Function->internalClass->engine;
     if (!engine) {
         setError(response, QStringLiteral("No execution engine passed"));
         return;
@@ -543,8 +531,7 @@ void NativeDebugger::handleExpressions(QJsonObject *response, const QJsonObject
         TRACE_PROTOCOL("Evaluate expression: " << expression);
         m_runningJob = true;
 
-        evaluateExpression(scope, expression);
-        QV4::ScopedValue result(scope, scope.result);
+        QV4::ScopedValue result(scope, evaluateExpression(expression));
 
         m_runningJob = false;
         if (result->isUndefined()) {
@@ -595,7 +582,7 @@ void NativeDebugger::handleContinue(QJsonObject *response, Speed speed)
     if (!m_returnedValue.isUndefined())
         m_returnedValue.set(m_engine, QV4::Encode::undefined());
 
-    m_currentContext.set(m_engine, *m_engine->currentContext);
+    m_currentFrame = m_engine->currentStackFrame;
     m_stepping = speed;
 }
 
@@ -605,7 +592,7 @@ void NativeDebugger::maybeBreakAtInstruction()
         return;
 
     if (m_stepping == StepOver) {
-        if (m_currentContext.asManaged()->d() == m_engine->current)
+        if (m_currentFrame == m_engine->currentStackFrame)
             pauseAndWait();
         return;
     }
@@ -623,7 +610,8 @@ void NativeDebugger::maybeBreakAtInstruction()
 
     if (m_service->m_breakHandler->m_haveBreakPoints) {
         if (QV4::Function *function = getFunction()) {
-            const int lineNumber = m_engine->current->lineNumber;
+            // lineNumber will be negative for Ret instructions, so those won't match
+            const int lineNumber = m_engine->currentStackFrame->lineNumber();
             if (reallyHitTheBreakPoint(function, lineNumber))
                 pauseAndWait();
         }
@@ -636,7 +624,7 @@ void NativeDebugger::enteringFunction()
         return;
 
     if (m_stepping == StepIn) {
-        m_currentContext.set(m_engine, *m_engine->currentContext);
+        m_currentFrame = m_engine->currentStackFrame;
     }
 }
 
@@ -645,8 +633,8 @@ void NativeDebugger::leavingFunction(const QV4::ReturnedValue &retVal)
     if (m_runningJob)
         return;
 
-    if (m_stepping != NotStepping && m_currentContext.asManaged()->d() == m_engine->current) {
-        m_currentContext.set(m_engine, *m_engine->parentContext(m_engine->currentContext));
+    if (m_stepping != NotStepping && m_currentFrame == m_engine->currentStackFrame) {
+        m_currentFrame = m_currentFrame->parent;
         m_stepping = StepOver;
         m_returnedValue.set(m_engine, retVal);
     }
@@ -668,9 +656,8 @@ void NativeDebugger::aboutToThrow()
 
 QV4::Function *NativeDebugger::getFunction() const
 {
-    QV4::ExecutionContext *context = m_engine->currentContext;
-    if (QV4::Function *function = context->getFunction())
-        return function;
+    if (m_engine->currentStackFrame)
+        return m_engine->currentStackFrame->v4Function;
     else
         return m_engine->globalCode;
 }
@@ -681,12 +668,11 @@ void NativeDebugger::pauseAndWait()
 
     event.insert(QStringLiteral("event"), QStringLiteral("break"));
     event.insert(QStringLiteral("language"), QStringLiteral("js"));
-    if (QV4::ExecutionContext *executionContext = m_engine->currentContext) {
-        if (QV4::Function *function = executionContext->getFunction()) {
-            event.insert(QStringLiteral("file"), function->sourceFile());
-            int line = executionContext->d()->lineNumber;
-            event.insert(QStringLiteral("line"), (line < 0 ? -line : line));
-        }
+    if (QV4::CppStackFrame *frame = m_engine->currentStackFrame) {
+        QV4::Function *function = frame->v4Function;
+        event.insert(QStringLiteral("file"), function->sourceFile());
+        int line = frame->lineNumber();
+        event.insert(QStringLiteral("line"), (line < 0 ? -line : line));
     }
 
     m_service->emitAsynchronousMessageToClient(event);
@@ -731,7 +717,6 @@ void QQmlNativeDebugServiceImpl::engineAboutToBeAdded(QJSEngine *engine)
         TRACE_PROTOCOL("Adding execution engine" << ee);
         if (ee) {
             NativeDebugger *debugger = new NativeDebugger(this, ee);
-            ee->iselFactory.reset(new QV4::Moth::ISelFactory);
             if (state() == Enabled)
                 ee->setDebugger(debugger);
             m_debuggers.append(QPointer<NativeDebugger>(debugger));