Merge 'wip/next' into dev

Change-Id: Iff9ee5e23bb326c4371ec8ed81d56f2f05d680e9

12 files changed, 1772 insertions, 344 deletions

diff --git a/Source/JavaScriptCore/debugger/Breakpoint.h b/Source/JavaScriptCore/debugger/Breakpoint.h
new file mode 100644
index 000000000..78d208a2b
--- /dev/null
+++ b/Source/JavaScriptCore/debugger/Breakpoint.h
@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2013 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+ */
+
+#ifndef Breakpoint_h
+#define Breakpoint_h
+
+#include "DebuggerPrimitives.h"
+#include <wtf/DoublyLinkedList.h>
+#include <wtf/RefCounted.h>
+#include <wtf/text/WTFString.h>
+
+namespace JSC {
+
+struct Breakpoint : public DoublyLinkedListNode<Breakpoint> {
+    Breakpoint()
+    {
+    }
+
+    Breakpoint(SourceID sourceID, unsigned line, unsigned column, const String& condition, bool autoContinue, unsigned ignoreCount)
+        : sourceID(sourceID)
+        , line(line)
+        , column(column)
+        , condition(condition)
+        , autoContinue(autoContinue)
+        , ignoreCount(ignoreCount)
+    {
+    }
+
+    Breakpoint(const Breakpoint& other)
+        : id(other.id)
+        , sourceID(other.sourceID)
+        , line(other.line)
+        , column(other.column)
+        , condition(other.condition)
+        , autoContinue(other.autoContinue)
+        , ignoreCount(other.ignoreCount)
+        , hitCount(other.hitCount)
+    {
+    }
+
+    BreakpointID id { noBreakpointID };
+    SourceID sourceID { noSourceID };
+    unsigned line { 0 };
+    unsigned column { 0 };
+    String condition;
+    bool autoContinue { false };
+    unsigned ignoreCount { 0 };
+    unsigned hitCount { 0 };
+
+    static const unsigned unspecifiedColumn = UINT_MAX;
+
+private:
+    Breakpoint* m_prev;
+    Breakpoint* m_next;
+
+    friend class WTF::DoublyLinkedListNode<Breakpoint>;
+};
+
+class BreakpointsList : public DoublyLinkedList<Breakpoint>,
+    public RefCounted<BreakpointsList> {
+public:
+    ~BreakpointsList()
+    {
+        Breakpoint* breakpoint;
+        while ((breakpoint = removeHead()))
+            delete breakpoint;
+        ASSERT(isEmpty());
+    }
+};
+
+} // namespace JSC
+
+#endif // Breakpoint_h
diff --git a/Source/JavaScriptCore/debugger/Debugger.cpp b/Source/JavaScriptCore/debugger/Debugger.cpp
index 2c5a1261a..f50d54be5 100644
--- a/Source/JavaScriptCore/debugger/Debugger.cpp
+++ b/Source/JavaScriptCore/debugger/Debugger.cpp
@@ -1,5 +1,5 @@
 /*
- *  Copyright (C) 2008 Apple Inc. All rights reserved.
+ *  Copyright (C) 2008, 2013, 2014 Apple Inc. All rights reserved.
  *  Copyright (C) 1999-2001 Harri Porten (porten@kde.org)
  *  Copyright (C) 2001 Peter Kelly (pmk@post.com)
  *
@@ -22,126 +22,755 @@
 #include "config.h"
 #include "Debugger.h"
 
+#include "CodeBlock.h"
+#include "DebuggerCallFrame.h"
 #include "Error.h"
+#include "HeapIterationScope.h"
 #include "Interpreter.h"
+#include "JSCJSValueInlines.h"
 #include "JSFunction.h"
 #include "JSGlobalObject.h"
-#include "Operations.h"
+#include "JSCInlines.h"
 #include "Parser.h"
 #include "Protect.h"
+#include "VMEntryScope.h"
 
 namespace {
 
 using namespace JSC;
 
-class Recompiler : public MarkedBlock::VoidFunctor {
+struct GatherSourceProviders : public MarkedBlock::VoidFunctor {
+    HashSet<SourceProvider*> sourceProviders;
+    JSGlobalObject* m_globalObject;
+
+    GatherSourceProviders(JSGlobalObject* globalObject)
+        : m_globalObject(globalObject) { }
+
+    IterationStatus operator()(JSCell* cell)
+    {
+        JSFunction* function = jsDynamicCast<JSFunction*>(cell);
+        if (!function)
+            return IterationStatus::Continue;
+
+        if (function->scope()->globalObject() != m_globalObject)
+            return IterationStatus::Continue;
+
+        if (!function->executable()->isFunctionExecutable())
+            return IterationStatus::Continue;
+
+        if (function->isHostOrBuiltinFunction())
+            return IterationStatus::Continue;
+
+        sourceProviders.add(
+            jsCast<FunctionExecutable*>(function->executable())->source().provider());
+        return IterationStatus::Continue;
+    }
+};
+
+} // namespace
+
+namespace JSC {
+
+class DebuggerPausedScope {
+public:
+    DebuggerPausedScope(Debugger& debugger)
+        : m_debugger(debugger)
+    {
+        ASSERT(!m_debugger.m_currentDebuggerCallFrame);
+        if (m_debugger.m_currentCallFrame)
+            m_debugger.m_currentDebuggerCallFrame = DebuggerCallFrame::create(debugger.m_currentCallFrame);
+    }
+
+    ~DebuggerPausedScope()
+    {
+        if (m_debugger.m_currentDebuggerCallFrame) {
+            m_debugger.m_currentDebuggerCallFrame->invalidate();
+            m_debugger.m_currentDebuggerCallFrame = nullptr;
+        }
+    }
+
+private:
+    Debugger& m_debugger;
+};
+
+// This is very similar to TemporaryChange<bool>, but that cannot be used
+// as the m_isPaused field uses only one bit.
+class TemporaryPausedState {
 public:
-    Recompiler(Debugger*);
-    ~Recompiler();
-    void operator()(JSCell*);
+    TemporaryPausedState(Debugger& debugger)
+        : m_debugger(debugger)
+    {
+        ASSERT(!m_debugger.m_isPaused);
+        m_debugger.m_isPaused = true;
+    }
+
+    ~TemporaryPausedState()
+    {
+        m_debugger.m_isPaused = false;
+    }
+
+private:
+    Debugger& m_debugger;
+};
+
+Debugger::Debugger(VM& vm)
+    : m_vm(vm)
+    , m_pauseOnExceptionsState(DontPauseOnExceptions)
+    , m_pauseOnNextStatement(false)
+    , m_isPaused(false)
+    , m_breakpointsActivated(true)
+    , m_hasHandlerForExceptionCallback(false)
+    , m_suppressAllPauses(false)
+    , m_steppingMode(SteppingModeDisabled)
+    , m_reasonForPause(NotPaused)
+    , m_pauseOnCallFrame(0)
+    , m_currentCallFrame(0)
+    , m_lastExecutedLine(UINT_MAX)
+    , m_lastExecutedSourceID(noSourceID)
+    , m_topBreakpointID(noBreakpointID)
+    , m_pausingBreakpointID(noBreakpointID)
+{
+}
+
+Debugger::~Debugger()
+{
+    HashSet<JSGlobalObject*>::iterator end = m_globalObjects.end();
+    for (HashSet<JSGlobalObject*>::iterator it = m_globalObjects.begin(); it != end; ++it)
+        (*it)->setDebugger(0);
+}
+
+void Debugger::attach(JSGlobalObject* globalObject)
+{
+    ASSERT(!globalObject->debugger());
+    globalObject->setDebugger(this);
+    m_globalObjects.add(globalObject);
+
+    m_vm.setShouldBuildPCToCodeOriginMapping();
+
+    // Call sourceParsed because it will execute JavaScript in the inspector.
+    GatherSourceProviders gatherSourceProviders(globalObject);
+    {
+        HeapIterationScope iterationScope(m_vm.heap);
+        m_vm.heap.objectSpace().forEachLiveCell(iterationScope, gatherSourceProviders);
+    }
+    for (auto* sourceProvider : gatherSourceProviders.sourceProviders)
+        sourceParsed(globalObject->globalExec(), sourceProvider, -1, String());
+}
+
+void Debugger::detach(JSGlobalObject* globalObject, ReasonForDetach reason)
+{
+    // If we're detaching from the currently executing global object, manually tear down our
+    // stack, since we won't get further debugger callbacks to do so. Also, resume execution,
+    // since there's no point in staying paused once a window closes.
+    if (m_currentCallFrame && m_currentCallFrame->vmEntryGlobalObject() == globalObject) {
+        m_currentCallFrame = 0;
+        m_pauseOnCallFrame = 0;
+        continueProgram();
+    }
+
+    ASSERT(m_globalObjects.contains(globalObject));
+    m_globalObjects.remove(globalObject);
+
+    // If the globalObject is destructing, then its CodeBlocks will also be
+    // destructed. There is no need to do the debugger requests clean up, and
+    // it is not safe to access those CodeBlocks at this time anyway.
+    if (reason != GlobalObjectIsDestructing)
+        clearDebuggerRequests(globalObject);
+
+    globalObject->setDebugger(0);
+}
+
+bool Debugger::isAttached(JSGlobalObject* globalObject)
+{
+    return globalObject->debugger() == this;
+}
+
+class Debugger::SetSteppingModeFunctor {
+public:
+    SetSteppingModeFunctor(Debugger* debugger, SteppingMode mode)
+        : m_debugger(debugger)
+        , m_mode(mode)
+    {
+    }
+
+    bool operator()(CodeBlock* codeBlock)
+    {
+        if (m_debugger == codeBlock->globalObject()->debugger()) {
+            if (m_mode == SteppingModeEnabled)
+                codeBlock->setSteppingMode(CodeBlock::SteppingModeEnabled);
+            else
+                codeBlock->setSteppingMode(CodeBlock::SteppingModeDisabled);
+        }
+        return false;
+    }
 
 private:
-    typedef HashSet<FunctionExecutable*> FunctionExecutableSet;
-    typedef HashMap<SourceProvider*, ExecState*> SourceProviderMap;
-    
     Debugger* m_debugger;
-    FunctionExecutableSet m_functionExecutables;
-    SourceProviderMap m_sourceProviders;
+    SteppingMode m_mode;
 };
 
-inline Recompiler::Recompiler(Debugger* debugger)
-    : m_debugger(debugger)
+void Debugger::setSteppingMode(SteppingMode mode)
+{
+    if (mode == m_steppingMode)
+        return;
+
+    m_vm.heap.completeAllDFGPlans();
+
+    m_steppingMode = mode;
+    SetSteppingModeFunctor functor(this, mode);
+    m_vm.heap.forEachCodeBlock(functor);
+}
+
+void Debugger::registerCodeBlock(CodeBlock* codeBlock)
 {
+    applyBreakpoints(codeBlock);
+    if (isStepping())
+        codeBlock->setSteppingMode(CodeBlock::SteppingModeEnabled);
 }
 
-inline Recompiler::~Recompiler()
+void Debugger::setProfilingClient(ProfilingClient* client)
 {
-    // Call sourceParsed() after reparsing all functions because it will execute
-    // JavaScript in the inspector.
-    SourceProviderMap::const_iterator end = m_sourceProviders.end();
-    for (SourceProviderMap::const_iterator iter = m_sourceProviders.begin(); iter != end; ++iter)
-        m_debugger->sourceParsed(iter->value, iter->key, -1, String());
+    ASSERT(!!m_profilingClient != !!client);
+    m_profilingClient = client;
+
+    recompileAllJSFunctions();
 }
 
-inline void Recompiler::operator()(JSCell* cell)
+double Debugger::willEvaluateScript()
 {
-    if (!cell->inherits(&JSFunction::s_info))
+    return m_profilingClient->willEvaluateScript();
+}
+
+void Debugger::didEvaluateScript(double startTime, ProfilingReason reason)
+{
+    m_profilingClient->didEvaluateScript(startTime, reason);
+}
+
+void Debugger::toggleBreakpoint(CodeBlock* codeBlock, Breakpoint& breakpoint, BreakpointState enabledOrNot)
+{
+    ScriptExecutable* executable = codeBlock->ownerScriptExecutable();
+
+    SourceID sourceID = static_cast<SourceID>(executable->sourceID());
+    if (breakpoint.sourceID != sourceID)
         return;
 
-    JSFunction* function = jsCast<JSFunction*>(cell);
-    if (function->executable()->isHostFunction())
+    unsigned line = breakpoint.line;
+    unsigned column = breakpoint.column;
+
+    unsigned startLine = executable->firstLine();
+    unsigned startColumn = executable->startColumn();
+    unsigned endLine = executable->lastLine();
+    unsigned endColumn = executable->endColumn();
+
+    // Inspector breakpoint line and column values are zero-based but the executable
+    // and CodeBlock line and column values are one-based.
+    line += 1;
+    column = column ? column + 1 : Breakpoint::unspecifiedColumn;
+
+    if (line < startLine || line > endLine)
+        return;
+    if (column != Breakpoint::unspecifiedColumn) {
+        if (line == startLine && column < startColumn)
+            return;
+        if (line == endLine && column > endColumn)
+            return;
+    }
+    if (!codeBlock->hasOpDebugForLineAndColumn(line, column))
         return;
 
-    FunctionExecutable* executable = function->jsExecutable();
+    if (enabledOrNot == BreakpointEnabled)
+        codeBlock->addBreakpoint(1);
+    else
+        codeBlock->removeBreakpoint(1);
+}
+
+void Debugger::applyBreakpoints(CodeBlock* codeBlock)
+{
+    BreakpointIDToBreakpointMap& breakpoints = m_breakpointIDToBreakpoint;
+    for (auto it = breakpoints.begin(); it != breakpoints.end(); ++it) {
+        Breakpoint& breakpoint = *it->value;
+        toggleBreakpoint(codeBlock, breakpoint, BreakpointEnabled);
+    }
+}
+
+class Debugger::ToggleBreakpointFunctor {
+public:
+    ToggleBreakpointFunctor(Debugger* debugger, Breakpoint& breakpoint, BreakpointState enabledOrNot)
+        : m_debugger(debugger)
+        , m_breakpoint(breakpoint)
+        , m_enabledOrNot(enabledOrNot)
+    {
+    }
+
+    bool operator()(CodeBlock* codeBlock)
+    {
+        if (m_debugger == codeBlock->globalObject()->debugger())
+            m_debugger->toggleBreakpoint(codeBlock, m_breakpoint, m_enabledOrNot);
+        return false;
+    }
+
+private:
+    Debugger* m_debugger;
+    Breakpoint& m_breakpoint;
+    BreakpointState m_enabledOrNot;
+};
+
+void Debugger::toggleBreakpoint(Breakpoint& breakpoint, Debugger::BreakpointState enabledOrNot)
+{
+    m_vm.heap.completeAllDFGPlans();
+
+    ToggleBreakpointFunctor functor(this, breakpoint, enabledOrNot);
+    m_vm.heap.forEachCodeBlock(functor);
+}
+
+void Debugger::recompileAllJSFunctions()
+{
+    m_vm.deleteAllCode();
+}
+
+BreakpointID Debugger::setBreakpoint(Breakpoint breakpoint, unsigned& actualLine, unsigned& actualColumn)
+{
+    SourceID sourceID = breakpoint.sourceID;
+    unsigned line = breakpoint.line;
+    unsigned column = breakpoint.column;
+
+    SourceIDToBreakpointsMap::iterator it = m_sourceIDToBreakpoints.find(sourceID);
+    if (it == m_sourceIDToBreakpoints.end())
+        it = m_sourceIDToBreakpoints.set(sourceID, LineToBreakpointsMap()).iterator;
+    LineToBreakpointsMap::iterator breaksIt = it->value.find(line);
+    if (breaksIt == it->value.end())
+        breaksIt = it->value.set(line, adoptRef(new BreakpointsList)).iterator;
+
+    BreakpointsList& breakpoints = *breaksIt->value;
+    for (Breakpoint* current = breakpoints.head(); current; current = current->next()) {
+        if (current->column == column) {
+            // The breakpoint already exists. We're not allowed to create a new
+            // breakpoint at this location. Rather than returning the breakpointID
+            // of the pre-existing breakpoint, we need to return noBreakpointID
+            // to indicate that we're not creating a new one.
+            return noBreakpointID;
+        }
+    }
+
+    BreakpointID id = ++m_topBreakpointID;
+    RELEASE_ASSERT(id != noBreakpointID);
+
+    breakpoint.id = id;
+    actualLine = line;
+    actualColumn = column;
+
+    Breakpoint* newBreakpoint = new Breakpoint(breakpoint);
+    breakpoints.append(newBreakpoint);
+    m_breakpointIDToBreakpoint.set(id, newBreakpoint);
+
+    toggleBreakpoint(breakpoint, BreakpointEnabled);
+
+    return id;
+}
+
+void Debugger::removeBreakpoint(BreakpointID id)
+{
+    ASSERT(id != noBreakpointID);
+
+    BreakpointIDToBreakpointMap::iterator idIt = m_breakpointIDToBreakpoint.find(id);
+    ASSERT(idIt != m_breakpointIDToBreakpoint.end());
+    Breakpoint* breakpoint = idIt->value;
+
+    SourceID sourceID = breakpoint->sourceID;
+    ASSERT(sourceID);
+    SourceIDToBreakpointsMap::iterator it = m_sourceIDToBreakpoints.find(sourceID);
+    ASSERT(it != m_sourceIDToBreakpoints.end());
+    LineToBreakpointsMap::iterator breaksIt = it->value.find(breakpoint->line);
+    ASSERT(breaksIt != it->value.end());
+
+    toggleBreakpoint(*breakpoint, BreakpointDisabled);
+
+    BreakpointsList& breakpoints = *breaksIt->value;
+#if !ASSERT_DISABLED
+    bool found = false;
+    for (Breakpoint* current = breakpoints.head(); current && !found; current = current->next()) {
+        if (current->id == breakpoint->id)
+            found = true;
+    }
+    ASSERT(found);
+#endif
+
+    m_breakpointIDToBreakpoint.remove(idIt);
+    breakpoints.remove(breakpoint);
+    delete breakpoint;
+
+    if (breakpoints.isEmpty()) {
+        it->value.remove(breaksIt);
+        if (it->value.isEmpty())
+            m_sourceIDToBreakpoints.remove(it);
+    }
+}
+
+bool Debugger::hasBreakpoint(SourceID sourceID, const TextPosition& position, Breakpoint *hitBreakpoint)
+{
+    if (!m_breakpointsActivated)
+        return false;
+
+    SourceIDToBreakpointsMap::const_iterator it = m_sourceIDToBreakpoints.find(sourceID);
+    if (it == m_sourceIDToBreakpoints.end())
+        return false;
+
+    unsigned line = position.m_line.zeroBasedInt();
+    unsigned column = position.m_column.zeroBasedInt();
+
+    LineToBreakpointsMap::const_iterator breaksIt = it->value.find(line);
+    if (breaksIt == it->value.end())
+        return false;
+
+    bool hit = false;
+    const BreakpointsList& breakpoints = *breaksIt->value;
+    Breakpoint* breakpoint;
+    for (breakpoint = breakpoints.head(); breakpoint; breakpoint = breakpoint->next()) {
+        unsigned breakLine = breakpoint->line;
+        unsigned breakColumn = breakpoint->column;
+        // Since frontend truncates the indent, the first statement in a line must match the breakpoint (line,0).
+        ASSERT(this == m_currentCallFrame->codeBlock()->globalObject()->debugger());
+        if ((line != m_lastExecutedLine && line == breakLine && !breakColumn)
+            || (line == breakLine && column == breakColumn)) {
+            hit = true;
+            break;
+        }
+    }
+    if (!hit)
+        return false;
 
-    // Check if the function is already in the set - if so,
-    // we've already retranslated it, nothing to do here.
-    if (!m_functionExecutables.add(executable).isNewEntry)
+    if (hitBreakpoint)
+        *hitBreakpoint = *breakpoint;
+
+    breakpoint->hitCount++;
+    if (breakpoint->ignoreCount >= breakpoint->hitCount)
+        return false;
+
+    if (breakpoint->condition.isEmpty())
+        return true;
+
+    // We cannot stop in the debugger while executing condition code,
+    // so make it looks like the debugger is already paused.
+    TemporaryPausedState pausedState(*this);
+
+    NakedPtr<Exception> exception;
+    DebuggerCallFrame* debuggerCallFrame = currentDebuggerCallFrame();
+    JSValue result = debuggerCallFrame->evaluate(breakpoint->condition, exception);
+
+    // We can lose the debugger while executing JavaScript.
+    if (!m_currentCallFrame)
+        return false;
+
+    if (exception) {
+        // An erroneous condition counts as "false".
+        handleExceptionInBreakpointCondition(m_currentCallFrame, exception);
+        return false;
+    }
+
+    return result.toBoolean(m_currentCallFrame);
+}
+
+class Debugger::ClearCodeBlockDebuggerRequestsFunctor {
+public:
+    ClearCodeBlockDebuggerRequestsFunctor(Debugger* debugger)
+        : m_debugger(debugger)
+    {
+    }
+
+    bool operator()(CodeBlock* codeBlock)
+    {
+        if (codeBlock->hasDebuggerRequests() && m_debugger == codeBlock->globalObject()->debugger())
+            codeBlock->clearDebuggerRequests();
+        return false;
+    }
+
+private:
+    Debugger* m_debugger;
+};
+
+void Debugger::clearBreakpoints()
+{
+    m_vm.heap.completeAllDFGPlans();
+
+    m_topBreakpointID = noBreakpointID;
+    m_breakpointIDToBreakpoint.clear();
+    m_sourceIDToBreakpoints.clear();
+
+    ClearCodeBlockDebuggerRequestsFunctor functor(this);
+    m_vm.heap.forEachCodeBlock(functor);
+}
+
+class Debugger::ClearDebuggerRequestsFunctor {
+public:
+    ClearDebuggerRequestsFunctor(JSGlobalObject* globalObject)
+        : m_globalObject(globalObject)
+    {
+    }
+
+    bool operator()(CodeBlock* codeBlock)
+    {
+        if (codeBlock->hasDebuggerRequests() && m_globalObject == codeBlock->globalObject())
+            codeBlock->clearDebuggerRequests();
+        return false;
+    }
+
+private:
+    JSGlobalObject* m_globalObject;
+};
+
+void Debugger::clearDebuggerRequests(JSGlobalObject* globalObject)
+{
+    m_vm.heap.completeAllDFGPlans();
+
+    ClearDebuggerRequestsFunctor functor(globalObject);
+    m_vm.heap.forEachCodeBlock(functor);
+}
+
+void Debugger::setBreakpointsActivated(bool activated)
+{
+    m_breakpointsActivated = activated;
+}
+
+void Debugger::setPauseOnExceptionsState(PauseOnExceptionsState pause)
+{
+    m_pauseOnExceptionsState = pause;
+}
+
+void Debugger::setPauseOnNextStatement(bool pause)
+{
+    m_pauseOnNextStatement = pause;
+    if (pause)
+        setSteppingMode(SteppingModeEnabled);
+}
+
+void Debugger::breakProgram()
+{
+    if (m_isPaused)
+        return;
+
+    if (!m_vm.topCallFrame)
         return;
 
-    ExecState* exec = function->scope()->globalObject()->JSGlobalObject::globalExec();
-    executable->clearCodeIfNotCompiling();
-    executable->clearUnlinkedCodeForRecompilationIfNotCompiling();
-    if (m_debugger == function->scope()->globalObject()->debugger())
-        m_sourceProviders.add(executable->source().provider(), exec);
+    m_pauseOnNextStatement = true;
+    setSteppingMode(SteppingModeEnabled);
+    m_currentCallFrame = m_vm.topCallFrame;
+    pauseIfNeeded(m_currentCallFrame);
 }
 
-} // namespace
+void Debugger::continueProgram()
+{
+    if (!m_isPaused)
+        return;
 
-namespace JSC {
+    m_pauseOnNextStatement = false;
+    notifyDoneProcessingDebuggerEvents();
+}
 
-Debugger::~Debugger()
+void Debugger::stepIntoStatement()
 {
-    HashSet<JSGlobalObject*>::iterator end = m_globalObjects.end();
-    for (HashSet<JSGlobalObject*>::iterator it = m_globalObjects.begin(); it != end; ++it)
-        (*it)->setDebugger(0);
+    if (!m_isPaused)
+        return;
+
+    m_pauseOnNextStatement = true;
+    setSteppingMode(SteppingModeEnabled);
+    notifyDoneProcessingDebuggerEvents();
 }
 
-void Debugger::attach(JSGlobalObject* globalObject)
+void Debugger::stepOverStatement()
 {
-    ASSERT(!globalObject->debugger());
-    globalObject->setDebugger(this);
-    m_globalObjects.add(globalObject);
+    if (!m_isPaused)
+        return;
+
+    m_pauseOnCallFrame = m_currentCallFrame;
+    notifyDoneProcessingDebuggerEvents();
 }
 
-void Debugger::detach(JSGlobalObject* globalObject)
+void Debugger::stepOutOfFunction()
 {
-    ASSERT(m_globalObjects.contains(globalObject));
-    m_globalObjects.remove(globalObject);
-    globalObject->setDebugger(0);
+    if (!m_isPaused)
+        return;
+
+    VMEntryFrame* topVMEntryFrame = m_vm.topVMEntryFrame;
+    m_pauseOnCallFrame = m_currentCallFrame ? m_currentCallFrame->callerFrame(topVMEntryFrame) : 0;
+    notifyDoneProcessingDebuggerEvents();
+}
+
+void Debugger::updateCallFrame(CallFrame* callFrame)
+{
+    m_currentCallFrame = callFrame;
+    SourceID sourceID = DebuggerCallFrame::sourceIDForCallFrame(callFrame);
+    if (m_lastExecutedSourceID != sourceID) {
+        m_lastExecutedLine = UINT_MAX;
+        m_lastExecutedSourceID = sourceID;
+    }
+}
+
+void Debugger::updateCallFrameAndPauseIfNeeded(CallFrame* callFrame)
+{
+    updateCallFrame(callFrame);
+    pauseIfNeeded(callFrame);
+    if (!isStepping())
+        m_currentCallFrame = 0;
+}
+
+void Debugger::pauseIfNeeded(CallFrame* callFrame)
+{
+    if (m_isPaused)
+        return;
+
+    if (m_suppressAllPauses)
+        return;
+
+    JSGlobalObject* vmEntryGlobalObject = callFrame->vmEntryGlobalObject();
+    if (!needPauseHandling(vmEntryGlobalObject))
+        return;
+
+    Breakpoint breakpoint;
+    bool didHitBreakpoint = false;
+    bool pauseNow = m_pauseOnNextStatement;
+    pauseNow |= (m_pauseOnCallFrame == m_currentCallFrame);
+
+    DebuggerPausedScope debuggerPausedScope(*this);
+
+    intptr_t sourceID = DebuggerCallFrame::sourceIDForCallFrame(m_currentCallFrame);
+    TextPosition position = DebuggerCallFrame::positionForCallFrame(m_currentCallFrame);
+    pauseNow |= didHitBreakpoint = hasBreakpoint(sourceID, position, &breakpoint);
+    m_lastExecutedLine = position.m_line.zeroBasedInt();
+    if (!pauseNow)
+        return;
+
+    // Make sure we are not going to pause again on breakpoint actions by
+    // reseting the pause state before executing any breakpoint actions.
+    TemporaryPausedState pausedState(*this);
+    m_pauseOnCallFrame = 0;
+    m_pauseOnNextStatement = false;
+
+    if (didHitBreakpoint) {
+        handleBreakpointHit(vmEntryGlobalObject, breakpoint);
+        // Note that the actions can potentially stop the debugger, so we need to check that
+        // we still have a current call frame when we get back.
+        if (breakpoint.autoContinue || !m_currentCallFrame)
+            return;
+        m_pausingBreakpointID = breakpoint.id;
+    }
+
+    {
+        PauseReasonDeclaration reason(*this, didHitBreakpoint ? PausedForBreakpoint : m_reasonForPause);
+        handlePause(vmEntryGlobalObject, m_reasonForPause);
+        RELEASE_ASSERT(!callFrame->hadException());
+    }
+
+    m_pausingBreakpointID = noBreakpointID;
+
+    if (!m_pauseOnNextStatement && !m_pauseOnCallFrame) {
+        setSteppingMode(SteppingModeDisabled);
+        m_currentCallFrame = nullptr;
+    }
+}
+
+void Debugger::exception(CallFrame* callFrame, JSValue exception, bool hasCatchHandler)
+{
+    if (m_isPaused)
+        return;
+
+    PauseReasonDeclaration reason(*this, PausedForException);
+    if (m_pauseOnExceptionsState == PauseOnAllExceptions || (m_pauseOnExceptionsState == PauseOnUncaughtExceptions && !hasCatchHandler)) {
+        m_pauseOnNextStatement = true;
+        setSteppingMode(SteppingModeEnabled);
+    }
+
+    m_hasHandlerForExceptionCallback = true;
+    m_currentException = exception;
+    updateCallFrameAndPauseIfNeeded(callFrame);
+    m_currentException = JSValue();
+    m_hasHandlerForExceptionCallback = false;
 }
 
-void Debugger::recompileAllJSFunctions(VM* vm)
+void Debugger::atStatement(CallFrame* callFrame)
 {
-    // If JavaScript is running, it's not safe to recompile, since we'll end
-    // up throwing away code that is live on the stack.
-    ASSERT(!vm->dynamicGlobalObject);
-    if (vm->dynamicGlobalObject)
+    if (m_isPaused)
         return;
 
-    Recompiler recompiler(this);
-    vm->heap.objectSpace().forEachLiveCell(recompiler);
+    PauseReasonDeclaration reason(*this, PausedAtStatement);
+    updateCallFrameAndPauseIfNeeded(callFrame);
 }
 
-JSValue evaluateInGlobalCallFrame(const String& script, JSValue& exception, JSGlobalObject* globalObject)
+void Debugger::callEvent(CallFrame* callFrame)
 {
-    CallFrame* globalCallFrame = globalObject->globalExec();
-    VM& vm = globalObject->vm();
+    if (m_isPaused)
+        return;
 
-    EvalExecutable* eval = EvalExecutable::create(globalCallFrame, vm.codeCache(), makeSource(script), false);
-    if (!eval) {
-        exception = vm.exception;
-        vm.exception = JSValue();
-        return exception;
+    PauseReasonDeclaration reason(*this, PausedAfterCall);
+    updateCallFrameAndPauseIfNeeded(callFrame);
+}
+
+void Debugger::returnEvent(CallFrame* callFrame)
+{
+    if (m_isPaused)
+        return;
+
+    PauseReasonDeclaration reason(*this, PausedBeforeReturn);
+    updateCallFrameAndPauseIfNeeded(callFrame);
+
+    // detach may have been called during pauseIfNeeded
+    if (!m_currentCallFrame)
+        return;
+
+    // Treat stepping over a return statement like stepping out.
+    if (m_currentCallFrame == m_pauseOnCallFrame) {
+        VMEntryFrame* topVMEntryFrame = m_vm.topVMEntryFrame;
+        m_pauseOnCallFrame = m_currentCallFrame->callerFrame(topVMEntryFrame);
     }
 
-    JSValue result = vm.interpreter->execute(eval, globalCallFrame, globalObject, globalCallFrame->scope());
-    if (vm.exception) {
-        exception = vm.exception;
-        vm.exception = JSValue();
+    VMEntryFrame* topVMEntryFrame = m_vm.topVMEntryFrame;
+    m_currentCallFrame = m_currentCallFrame->callerFrame(topVMEntryFrame);
+}
+
+void Debugger::willExecuteProgram(CallFrame* callFrame)
+{
+    if (m_isPaused)
+        return;
+
+    PauseReasonDeclaration reason(*this, PausedAtStartOfProgram);
+    updateCallFrameAndPauseIfNeeded(callFrame);
+}
+
+void Debugger::didExecuteProgram(CallFrame* callFrame)
+{
+    if (m_isPaused)
+        return;
+
+    PauseReasonDeclaration reason(*this, PausedAtEndOfProgram);
+    updateCallFrameAndPauseIfNeeded(callFrame);
+
+    // Treat stepping over the end of a program like stepping out.
+    if (!m_currentCallFrame)
+        return;
+    if (m_currentCallFrame == m_pauseOnCallFrame) {
+        VMEntryFrame* topVMEntryFrame = m_vm.topVMEntryFrame;
+        m_pauseOnCallFrame = m_currentCallFrame->callerFrame(topVMEntryFrame);
+        if (!m_currentCallFrame)
+            return;
     }
-    ASSERT(result);
-    return result;
+    VMEntryFrame* topVMEntryFrame = m_vm.topVMEntryFrame;
+    m_currentCallFrame = m_currentCallFrame->callerFrame(topVMEntryFrame);
+}
+
+void Debugger::didReachBreakpoint(CallFrame* callFrame)
+{
+    if (m_isPaused)
+        return;
+
+    PauseReasonDeclaration reason(*this, PausedForDebuggerStatement);
+    m_pauseOnNextStatement = true;
+    setSteppingMode(SteppingModeEnabled);
+    updateCallFrameAndPauseIfNeeded(callFrame);
+}
+
+DebuggerCallFrame* Debugger::currentDebuggerCallFrame() const
+{
+    ASSERT(m_currentDebuggerCallFrame);
+    return m_currentDebuggerCallFrame.get();
 }
 
 } // namespace JSC
diff --git a/Source/JavaScriptCore/debugger/Debugger.h b/Source/JavaScriptCore/debugger/Debugger.h
index 95dd62b06..2e91aafbe 100644
--- a/Source/JavaScriptCore/debugger/Debugger.h
+++ b/Source/JavaScriptCore/debugger/Debugger.h
@@ -1,7 +1,7 @@
 /*
  *  Copyright (C) 1999-2001 Harri Porten (porten@kde.org)
  *  Copyright (C) 2001 Peter Kelly (pmk@post.com)
- *  Copyright (C) 2008, 2009 Apple Inc. All rights reserved.
+ *  Copyright (C) 2008, 2009, 2013, 2014 Apple Inc. All rights reserved.
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Lesser General Public
@@ -22,44 +22,220 @@
 #ifndef Debugger_h
 #define Debugger_h
 
+#include "Breakpoint.h"
+#include "CallData.h"
+#include "DebuggerCallFrame.h"
+#include "DebuggerPrimitives.h"
+#include "JSCJSValue.h"
+#include <wtf/HashMap.h>
 #include <wtf/HashSet.h>
+#include <wtf/RefPtr.h>
+#include <wtf/text/TextPosition.h>
 
 namespace JSC {
 
-    class DebuggerCallFrame;
-    class ExecState;
-    class VM;
-    class JSGlobalObject;
-    class JSValue;
-    class SourceProvider;
+class CodeBlock;
+class Exception;
+class ExecState;
+class JSGlobalObject;
+class SourceProvider;
+class VM;
 
-    class JS_EXPORT_PRIVATE Debugger {
+typedef ExecState CallFrame;
+
+class JS_EXPORT_PRIVATE Debugger {
+public:
+    Debugger(VM&);
+    virtual ~Debugger();
+
+    VM& vm() { return m_vm; }
+
+    JSC::DebuggerCallFrame* currentDebuggerCallFrame() const;
+    bool hasHandlerForExceptionCallback() const
+    {
+        ASSERT(m_reasonForPause == PausedForException);
+        return m_hasHandlerForExceptionCallback;
+    }
+    JSValue currentException()
+    {
+        ASSERT(m_reasonForPause == PausedForException);
+        return m_currentException;
+    }
+
+    bool needsExceptionCallbacks() const { return m_pauseOnExceptionsState != DontPauseOnExceptions; }
+
+    enum ReasonForDetach {
+        TerminatingDebuggingSession,
+        GlobalObjectIsDestructing
+    };
+    void attach(JSGlobalObject*);
+    void detach(JSGlobalObject*, ReasonForDetach);
+    bool isAttached(JSGlobalObject*);
+
+    BreakpointID setBreakpoint(Breakpoint, unsigned& actualLine, unsigned& actualColumn);
+    void removeBreakpoint(BreakpointID);
+    void clearBreakpoints();
+    void setBreakpointsActivated(bool);
+    void activateBreakpoints() { setBreakpointsActivated(true); }
+    void deactivateBreakpoints() { setBreakpointsActivated(false); }
+
+    enum PauseOnExceptionsState {
+        DontPauseOnExceptions,
+        PauseOnAllExceptions,
+        PauseOnUncaughtExceptions
+    };
+    PauseOnExceptionsState pauseOnExceptionsState() const { return m_pauseOnExceptionsState; }
+    void setPauseOnExceptionsState(PauseOnExceptionsState);
+
+    enum ReasonForPause {
+        NotPaused,
+        PausedForException,
+        PausedAtStatement,
+        PausedAfterCall,
+        PausedBeforeReturn,
+        PausedAtStartOfProgram,
+        PausedAtEndOfProgram,
+        PausedForBreakpoint,
+        PausedForDebuggerStatement,
+    };
+    ReasonForPause reasonForPause() const { return m_reasonForPause; }
+    BreakpointID pausingBreakpointID() const { return m_pausingBreakpointID; }
+
+    void setPauseOnNextStatement(bool);
+    void breakProgram();
+    void continueProgram();
+    void stepIntoStatement();
+    void stepOverStatement();
+    void stepOutOfFunction();
+
+    bool isPaused() const { return m_isPaused; }
+    bool isStepping() const { return m_steppingMode == SteppingModeEnabled; }
+
+    bool suppressAllPauses() const { return m_suppressAllPauses; }
+    void setSuppressAllPauses(bool suppress) { m_suppressAllPauses = suppress; }
+
+    virtual void sourceParsed(ExecState*, SourceProvider*, int errorLineNumber, const WTF::String& errorMessage) = 0;
+
+    void exception(CallFrame*, JSValue exceptionValue, bool hasCatchHandler);
+    void atStatement(CallFrame*);
+    void callEvent(CallFrame*);
+    void returnEvent(CallFrame*);
+    void willExecuteProgram(CallFrame*);
+    void didExecuteProgram(CallFrame*);
+    void didReachBreakpoint(CallFrame*);
+
+    virtual void recompileAllJSFunctions();
+
+    void registerCodeBlock(CodeBlock*);
+
+    class ProfilingClient {
     public:
-        virtual ~Debugger();
+        virtual ~ProfilingClient() { }
+        virtual bool isAlreadyProfiling() const = 0;
+        virtual double willEvaluateScript() = 0;
+        virtual void didEvaluateScript(double startTime, ProfilingReason) = 0;
+    };
 
-        void attach(JSGlobalObject*);
-        virtual void detach(JSGlobalObject*);
+    void setProfilingClient(ProfilingClient*);
+    bool hasProfilingClient() const { return m_profilingClient != nullptr; }
+    bool isAlreadyProfiling() const { return m_profilingClient && m_profilingClient->isAlreadyProfiling(); }
+    double willEvaluateScript();
+    void didEvaluateScript(double startTime, ProfilingReason);
 
-        virtual void sourceParsed(ExecState*, SourceProvider*, int errorLineNumber, const WTF::String& errorMessage) = 0;
+protected:
+    virtual bool needPauseHandling(JSGlobalObject*) { return false; }
+    virtual void handleBreakpointHit(JSGlobalObject*, const Breakpoint&) { }
+    virtual void handleExceptionInBreakpointCondition(ExecState*, Exception*) const { }
+    virtual void handlePause(JSGlobalObject*, ReasonForPause) { }
+    virtual void notifyDoneProcessingDebuggerEvents() { }
 
-        virtual void exception(const DebuggerCallFrame&, intptr_t, int, int, bool) = 0;
-        virtual void atStatement(const DebuggerCallFrame&, intptr_t, int, int) = 0;
-        virtual void callEvent(const DebuggerCallFrame&, intptr_t, int, int) = 0;
-        virtual void returnEvent(const DebuggerCallFrame&, intptr_t, int, int) = 0;
+private:
+    typedef HashMap<BreakpointID, Breakpoint*> BreakpointIDToBreakpointMap;
 
-        virtual void willExecuteProgram(const DebuggerCallFrame&, intptr_t, int, int) = 0;
-        virtual void didExecuteProgram(const DebuggerCallFrame&, intptr_t, int, int) = 0;
-        virtual void didReachBreakpoint(const DebuggerCallFrame&, intptr_t, int, int) = 0;
+    typedef HashMap<unsigned, RefPtr<BreakpointsList>, WTF::IntHash<int>, WTF::UnsignedWithZeroKeyHashTraits<int>> LineToBreakpointsMap;
+    typedef HashMap<SourceID, LineToBreakpointsMap, WTF::IntHash<SourceID>, WTF::UnsignedWithZeroKeyHashTraits<SourceID>> SourceIDToBreakpointsMap;
 
+    class ClearCodeBlockDebuggerRequestsFunctor;
+    class ClearDebuggerRequestsFunctor;
+    class SetSteppingModeFunctor;
+    class ToggleBreakpointFunctor;
 
-        void recompileAllJSFunctions(VM*);
+    class PauseReasonDeclaration {
+    public:
+        PauseReasonDeclaration(Debugger& debugger, ReasonForPause reason)
+            : m_debugger(debugger)
+        {
+            m_debugger.m_reasonForPause = reason;
+        }
 
+        ~PauseReasonDeclaration()
+        {
+            m_debugger.m_reasonForPause = NotPaused;
+        }
     private:
-        HashSet<JSGlobalObject*> m_globalObjects;
+        Debugger& m_debugger;
     };
 
-    // This function exists only for backwards compatibility with existing WebScriptDebugger clients.
-    JS_EXPORT_PRIVATE JSValue evaluateInGlobalCallFrame(const WTF::String&, JSValue& exception, JSGlobalObject*);
+    bool hasBreakpoint(SourceID, const TextPosition&, Breakpoint* hitBreakpoint);
+
+    void updateNeedForOpDebugCallbacks();
+
+    // These update functions are only needed because our current breakpoints are
+    // key'ed off the source position instead of the bytecode PC. This ensures
+    // that we don't break on the same line more than once. Once we switch to a
+    // bytecode PC key'ed breakpoint, we will not need these anymore and should
+    // be able to remove them.
+    void updateCallFrame(JSC::CallFrame*);
+    void updateCallFrameAndPauseIfNeeded(JSC::CallFrame*);
+    void pauseIfNeeded(JSC::CallFrame*);
+
+    enum SteppingMode {
+        SteppingModeDisabled,
+        SteppingModeEnabled
+    };
+    void setSteppingMode(SteppingMode);
+
+    enum BreakpointState {
+        BreakpointDisabled,
+        BreakpointEnabled
+    };
+    void toggleBreakpoint(CodeBlock*, Breakpoint&, BreakpointState);
+    void applyBreakpoints(CodeBlock*);
+    void toggleBreakpoint(Breakpoint&, BreakpointState);
+
+    void clearDebuggerRequests(JSGlobalObject*);
+
+    VM& m_vm;
+    HashSet<JSGlobalObject*> m_globalObjects;
+
+    PauseOnExceptionsState m_pauseOnExceptionsState;
+    bool m_pauseOnNextStatement : 1;
+    bool m_isPaused : 1;
+    bool m_breakpointsActivated : 1;
+    bool m_hasHandlerForExceptionCallback : 1;
+    bool m_suppressAllPauses : 1;
+    unsigned m_steppingMode : 1; // SteppingMode
+
+    ReasonForPause m_reasonForPause;
+    JSValue m_currentException;
+    CallFrame* m_pauseOnCallFrame;
+    CallFrame* m_currentCallFrame;
+    unsigned m_lastExecutedLine;
+    SourceID m_lastExecutedSourceID;
+
+    BreakpointID m_topBreakpointID;
+    BreakpointID m_pausingBreakpointID;
+    BreakpointIDToBreakpointMap m_breakpointIDToBreakpoint;
+    SourceIDToBreakpointsMap m_sourceIDToBreakpoints;
+
+    RefPtr<JSC::DebuggerCallFrame> m_currentDebuggerCallFrame;
+
+    ProfilingClient* m_profilingClient { nullptr };
+
+    friend class DebuggerPausedScope;
+    friend class TemporaryPausedState;
+    friend class LLIntOffsetsExtractor;
+};
 
 } // namespace JSC
 
diff --git a/Source/JavaScriptCore/debugger/DebuggerActivation.cpp b/Source/JavaScriptCore/debugger/DebuggerActivation.cpp
deleted file mode 100644
index eec2d6bd7..000000000
--- a/Source/JavaScriptCore/debugger/DebuggerActivation.cpp
+++ /dev/null
@@ -1,110 +0,0 @@
-/*
- * Copyright (C) 2008, 2009 Apple Inc. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
- * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
- * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
- * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
- * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
- * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
- */
-
-#include "config.h"
-#include "DebuggerActivation.h"
-
-#include "JSActivation.h"
-#include "Operations.h"
-
-namespace JSC {
-
-ASSERT_HAS_TRIVIAL_DESTRUCTOR(DebuggerActivation);
-
-const ClassInfo DebuggerActivation::s_info = { "DebuggerActivation", &Base::s_info, 0, 0, CREATE_METHOD_TABLE(DebuggerActivation) };
-
-DebuggerActivation::DebuggerActivation(VM& vm)
-    : JSNonFinalObject(vm, vm.debuggerActivationStructure.get())
-{
-}
-
-void DebuggerActivation::finishCreation(VM& vm, JSObject* activation)
-{
-    Base::finishCreation(vm);
-    ASSERT(activation);
-    ASSERT(activation->isActivationObject());
-    m_activation.set(vm, this, jsCast<JSActivation*>(activation));
-}
-
-void DebuggerActivation::visitChildren(JSCell* cell, SlotVisitor& visitor)
-{
-    DebuggerActivation* thisObject = jsCast<DebuggerActivation*>(cell);
-    ASSERT_GC_OBJECT_INHERITS(thisObject, &s_info);
-    COMPILE_ASSERT(StructureFlags & OverridesVisitChildren, OverridesVisitChildrenWithoutSettingFlag);
-    ASSERT(thisObject->structure()->typeInfo().overridesVisitChildren());
-
-    JSObject::visitChildren(thisObject, visitor);
-    visitor.append(&thisObject->m_activation);
-}
-
-String DebuggerActivation::className(const JSObject* object)
-{
-    const DebuggerActivation* thisObject = jsCast<const DebuggerActivation*>(object);
-    return thisObject->m_activation->methodTable()->className(thisObject->m_activation.get());
-}
-
-bool DebuggerActivation::getOwnPropertySlot(JSCell* cell, ExecState* exec, PropertyName propertyName, PropertySlot& slot)
-{
-    DebuggerActivation* thisObject = jsCast<DebuggerActivation*>(cell);
-    return thisObject->m_activation->methodTable()->getOwnPropertySlot(thisObject->m_activation.get(), exec, propertyName, slot);
-}
-
-void DebuggerActivation::put(JSCell* cell, ExecState* exec, PropertyName propertyName, JSValue value, PutPropertySlot& slot)
-{
-    DebuggerActivation* thisObject = jsCast<DebuggerActivation*>(cell);
-    thisObject->m_activation->methodTable()->put(thisObject->m_activation.get(), exec, propertyName, value, slot);
-}
-
-void DebuggerActivation::putDirectVirtual(JSObject* object, ExecState* exec, PropertyName propertyName, JSValue value, unsigned attributes)
-{
-    DebuggerActivation* thisObject = jsCast<DebuggerActivation*>(object);
-    thisObject->m_activation->methodTable()->putDirectVirtual(thisObject->m_activation.get(), exec, propertyName, value, attributes);
-}
-
-bool DebuggerActivation::deleteProperty(JSCell* cell, ExecState* exec, PropertyName propertyName)
-{
-    DebuggerActivation* thisObject = jsCast<DebuggerActivation*>(cell);
-    return thisObject->m_activation->methodTable()->deleteProperty(thisObject->m_activation.get(), exec, propertyName);
-}
-
-void DebuggerActivation::getOwnPropertyNames(JSObject* object, ExecState* exec, PropertyNameArray& propertyNames, EnumerationMode mode)
-{
-    DebuggerActivation* thisObject = jsCast<DebuggerActivation*>(object);
-    thisObject->m_activation->methodTable()->getPropertyNames(thisObject->m_activation.get(), exec, propertyNames, mode);
-}
-
-bool DebuggerActivation::getOwnPropertyDescriptor(JSObject* object, ExecState* exec, PropertyName propertyName, PropertyDescriptor& descriptor)
-{
-    DebuggerActivation* thisObject = jsCast<DebuggerActivation*>(object);
-    return thisObject->m_activation->methodTable()->getOwnPropertyDescriptor(thisObject->m_activation.get(), exec, propertyName, descriptor);
-}
-
-bool DebuggerActivation::defineOwnProperty(JSObject* object, ExecState* exec, PropertyName propertyName, PropertyDescriptor& descriptor, bool shouldThrow)
-{
-    DebuggerActivation* thisObject = jsCast<DebuggerActivation*>(object);
-    return thisObject->m_activation->methodTable()->defineOwnProperty(thisObject->m_activation.get(), exec, propertyName, descriptor, shouldThrow);
-}
-
-} // namespace JSC
diff --git a/Source/JavaScriptCore/debugger/DebuggerActivation.h b/Source/JavaScriptCore/debugger/DebuggerActivation.h
deleted file mode 100644
index a33d6ddb2..000000000
--- a/Source/JavaScriptCore/debugger/DebuggerActivation.h
+++ /dev/null
@@ -1,73 +0,0 @@
-/*
- * Copyright (C) 2008, 2009 Apple Inc. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
- * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
- * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
- * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
- * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
- * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
- */
-
-#ifndef DebuggerActivation_h
-#define DebuggerActivation_h
-
-#include "JSObject.h"
-
-namespace JSC {
-
-    class DebuggerActivation : public JSNonFinalObject {
-    public:
-        typedef JSNonFinalObject Base;
-
-        static DebuggerActivation* create(VM& vm, JSObject* object)
-        {
-            DebuggerActivation* activation = new (NotNull, allocateCell<DebuggerActivation>(vm.heap)) DebuggerActivation(vm);
-            activation->finishCreation(vm, object);
-            return activation;
-        }
-
-        static void visitChildren(JSCell*, SlotVisitor&);
-        static String className(const JSObject*);
-        static bool getOwnPropertySlot(JSCell*, ExecState*, PropertyName, PropertySlot&);
-        static void put(JSCell*, ExecState*, PropertyName, JSValue, PutPropertySlot&);
-        static void putDirectVirtual(JSObject*, ExecState*, PropertyName, JSValue, unsigned attributes);
-        static bool deleteProperty(JSCell*, ExecState*, PropertyName);
-        static void getOwnPropertyNames(JSObject*, ExecState*, PropertyNameArray&, EnumerationMode);
-        static bool getOwnPropertyDescriptor(JSObject*, ExecState*, PropertyName, PropertyDescriptor&);
-        static bool defineOwnProperty(JSObject*, ExecState*, PropertyName, PropertyDescriptor&, bool shouldThrow);
-
-        JS_EXPORTDATA static const ClassInfo s_info;
-
-        static Structure* createStructure(VM& vm, JSGlobalObject* globalObject, JSValue prototype) 
-        {
-            return Structure::create(vm, globalObject, prototype, TypeInfo(ObjectType, StructureFlags), &s_info); 
-        }
-
-    protected:
-        static const unsigned StructureFlags = OverridesGetOwnPropertySlot | OverridesVisitChildren | JSObject::StructureFlags;
-
-        JS_EXPORT_PRIVATE void finishCreation(VM&, JSObject* activation);
-
-    private:
-        JS_EXPORT_PRIVATE DebuggerActivation(VM&);
-        WriteBarrier<JSActivation> m_activation;
-    };
-
-} // namespace JSC
-
-#endif // DebuggerActivation_h
diff --git a/Source/JavaScriptCore/debugger/DebuggerCallFrame.cpp b/Source/JavaScriptCore/debugger/DebuggerCallFrame.cpp
index a5d045cb9..f4794fd45 100644
--- a/Source/JavaScriptCore/debugger/DebuggerCallFrame.cpp
+++ b/Source/JavaScriptCore/debugger/DebuggerCallFrame.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2008 Apple Inc. All rights reserved.
+ * Copyright (C) 2008, 2013, 2014 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -10,7 +10,7 @@
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
  *     documentation and/or other materials provided with the distribution.
- * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
+ * 3.  Neither the name of Apple Inc. ("Apple") nor the names of
  *     its contributors may be used to endorse or promote products derived
  *     from this software without specific prior written permission.
  *
@@ -29,81 +29,229 @@
 #include "config.h"
 #include "DebuggerCallFrame.h"
 
-#include "JSFunction.h"
 #include "CodeBlock.h"
+#include "DebuggerEvalEnabler.h"
+#include "DebuggerScope.h"
 #include "Interpreter.h"
-#include "Operations.h"
+#include "JSFunction.h"
+#include "JSLexicalEnvironment.h"
+#include "JSCInlines.h"
 #include "Parser.h"
+#include "StackVisitor.h"
+#include "StrongInlines.h"
 
 namespace JSC {
 
-String DebuggerCallFrame::functionName() const
+class LineAndColumnFunctor {
+public:
+    StackVisitor::Status operator()(StackVisitor& visitor)
+    {
+        visitor->computeLineAndColumn(m_line, m_column);
+        return StackVisitor::Done;
+    }
+
+    unsigned line() const { return m_line; }
+    unsigned column() const { return m_column; }
+
+private:
+    unsigned m_line;
+    unsigned m_column;
+};
+
+class FindCallerMidStackFunctor {
+public:
+    FindCallerMidStackFunctor(CallFrame* callFrame)
+        : m_callFrame(callFrame)
+        , m_callerFrame(nullptr)
+    { }
+
+    StackVisitor::Status operator()(StackVisitor& visitor)
+    {
+        if (visitor->callFrame() == m_callFrame) {
+            m_callerFrame = visitor->callerFrame();
+            return StackVisitor::Done;
+        }
+        return StackVisitor::Continue;
+    }
+
+    CallFrame* getCallerFrame() const { return m_callerFrame; }
+
+private:
+    CallFrame* m_callFrame;
+    CallFrame* m_callerFrame;
+};
+
+DebuggerCallFrame::DebuggerCallFrame(CallFrame* callFrame)
+    : m_callFrame(callFrame)
 {
-    if (!m_callFrame->codeBlock())
-        return String();
+    m_position = positionForCallFrame(m_callFrame);
+}
 
-    if (!m_callFrame->callee())
-        return String();
+RefPtr<DebuggerCallFrame> DebuggerCallFrame::callerFrame()
+{
+    ASSERT(isValid());
+    if (!isValid())
+        return 0;
 
-    JSObject* function = m_callFrame->callee();
-    if (!function || !function->inherits(&JSFunction::s_info))
-        return String();
-    return jsCast<JSFunction*>(function)->name(m_callFrame);
+    if (m_caller)
+        return m_caller;
+
+    FindCallerMidStackFunctor functor(m_callFrame);
+    m_callFrame->vm().topCallFrame->iterate(functor);
+
+    CallFrame* callerFrame = functor.getCallerFrame();
+    if (!callerFrame)
+        return nullptr;
+
+    m_caller = DebuggerCallFrame::create(callerFrame);
+    return m_caller;
 }
-    
-String DebuggerCallFrame::calculatedFunctionName() const
+
+JSC::JSGlobalObject* DebuggerCallFrame::vmEntryGlobalObject() const
 {
-    if (!m_callFrame->codeBlock())
-        return String();
+    ASSERT(isValid());
+    if (!isValid())
+        return 0;
+    return m_callFrame->vmEntryGlobalObject();
+}
 
-    JSObject* function = m_callFrame->callee();
+SourceID DebuggerCallFrame::sourceID() const
+{
+    ASSERT(isValid());
+    if (!isValid())
+        return noSourceID;
+    return sourceIDForCallFrame(m_callFrame);
+}
 
-    if (!function)
+String DebuggerCallFrame::functionName() const
+{
+    ASSERT(isValid());
+    if (!isValid())
         return String();
+    return m_callFrame->friendlyFunctionName();
+}
 
-    return getCalculatedDisplayName(m_callFrame, function);
+DebuggerScope* DebuggerCallFrame::scope()
+{
+    ASSERT(isValid());
+    if (!isValid())
+        return 0;
+
+    if (!m_scope) {
+        VM& vm = m_callFrame->vm();
+        JSScope* scope;
+        CodeBlock* codeBlock = m_callFrame->codeBlock();
+        if (codeBlock && codeBlock->scopeRegister().isValid())
+            scope = m_callFrame->scope(codeBlock->scopeRegister().offset());
+        else if (JSCallee* callee = jsDynamicCast<JSCallee*>(m_callFrame->callee()))
+            scope = callee->scope();
+        else
+            scope = m_callFrame->lexicalGlobalObject();
+
+        m_scope.set(vm, DebuggerScope::create(vm, scope));
+    }
+    return m_scope.get();
 }
 
 DebuggerCallFrame::Type DebuggerCallFrame::type() const
 {
-    if (m_callFrame->callee())
+    ASSERT(isValid());
+    if (!isValid())
+        return ProgramType;
+
+    if (jsDynamicCast<JSFunction*>(m_callFrame->callee()))
         return FunctionType;
 
     return ProgramType;
 }
 
-JSObject* DebuggerCallFrame::thisObject() const
+JSValue DebuggerCallFrame::thisValue() const
 {
-    CodeBlock* codeBlock = m_callFrame->codeBlock();
-    if (!codeBlock)
-        return 0;
-
-    JSValue thisValue = m_callFrame->uncheckedR(codeBlock->thisRegister()).jsValue();
-    if (!thisValue.isObject())
-        return 0;
-
-    return asObject(thisValue);
+    ASSERT(isValid());
+    return thisValueForCallFrame(m_callFrame);
 }
 
-JSValue DebuggerCallFrame::evaluate(const String& script, JSValue& exception) const
+// Evaluate some JavaScript code in the scope of this frame.
+JSValue DebuggerCallFrame::evaluate(const String& script, NakedPtr<Exception>& exception)
 {
-    if (!m_callFrame->codeBlock())
+    ASSERT(isValid());
+    CallFrame* callFrame = m_callFrame;
+    if (!callFrame)
+        return jsNull();
+
+    JSLockHolder lock(callFrame);
+
+    if (!callFrame->codeBlock())
         return JSValue();
     
-    VM& vm = m_callFrame->vm();
-    EvalExecutable* eval = EvalExecutable::create(m_callFrame, m_callFrame->codeBlock()->unlinkedCodeBlock()->codeCacheForEval(), makeSource(script), m_callFrame->codeBlock()->isStrictMode());
-    if (vm.exception) {
-        exception = vm.exception;
-        vm.exception = JSValue();
+    DebuggerEvalEnabler evalEnabler(callFrame);
+    VM& vm = callFrame->vm();
+    auto& codeBlock = *callFrame->codeBlock();
+    ThisTDZMode thisTDZMode = codeBlock.unlinkedCodeBlock()->constructorKind() == ConstructorKind::Derived ? ThisTDZMode::AlwaysCheck : ThisTDZMode::CheckIfNeeded;
+
+    VariableEnvironment variablesUnderTDZ;
+    JSScope::collectVariablesUnderTDZ(scope()->jsScope(), variablesUnderTDZ);
+
+    EvalExecutable* eval = EvalExecutable::create(callFrame, makeSource(script), codeBlock.isStrictMode(), thisTDZMode, codeBlock.unlinkedCodeBlock()->derivedContextType(), codeBlock.unlinkedCodeBlock()->isArrowFunction(), &variablesUnderTDZ);
+    if (vm.exception()) {
+        exception = vm.exception();
+        vm.clearException();
+        return jsUndefined();
     }
 
-    JSValue result = vm.interpreter->execute(eval, m_callFrame, thisObject(), m_callFrame->scope());
-    if (vm.exception) {
-        exception = vm.exception;
-        vm.exception = JSValue();
+    JSValue thisValue = thisValueForCallFrame(callFrame);
+    JSValue result = vm.interpreter->execute(eval, callFrame, thisValue, scope()->jsScope());
+    if (vm.exception()) {
+        exception = vm.exception();
+        vm.clearException();
     }
     ASSERT(result);
     return result;
 }
 
+void DebuggerCallFrame::invalidate()
+{
+    RefPtr<DebuggerCallFrame> frame = this;
+    while (frame) {
+        frame->m_callFrame = nullptr;
+        if (frame->m_scope) {
+            frame->m_scope->invalidateChain();
+            frame->m_scope.clear();
+        }
+        frame = frame->m_caller.release();
+    }
+}
+
+TextPosition DebuggerCallFrame::positionForCallFrame(CallFrame* callFrame)
+{
+    if (!callFrame)
+        return TextPosition();
+
+    LineAndColumnFunctor functor;
+    callFrame->iterate(functor);
+    return TextPosition(OrdinalNumber::fromOneBasedInt(functor.line()), OrdinalNumber::fromOneBasedInt(functor.column()));
+}
+
+SourceID DebuggerCallFrame::sourceIDForCallFrame(CallFrame* callFrame)
+{
+    ASSERT(callFrame);
+    CodeBlock* codeBlock = callFrame->codeBlock();
+    if (!codeBlock)
+        return noSourceID;
+    return codeBlock->ownerScriptExecutable()->sourceID();
+}
+
+JSValue DebuggerCallFrame::thisValueForCallFrame(CallFrame* callFrame)
+{
+    if (!callFrame)
+        return jsNull();
+
+    ECMAMode ecmaMode = NotStrictMode;
+    CodeBlock* codeBlock = callFrame->codeBlock();
+    if (codeBlock && codeBlock->isStrictMode())
+        ecmaMode = StrictMode;
+    JSValue thisValue = callFrame->thisValue().toThis(callFrame, ecmaMode);
+    return thisValue;
+}
+
 } // namespace JSC
diff --git a/Source/JavaScriptCore/debugger/DebuggerCallFrame.h b/Source/JavaScriptCore/debugger/DebuggerCallFrame.h
index 66585a637..b583455bc 100644
--- a/Source/JavaScriptCore/debugger/DebuggerCallFrame.h
+++ b/Source/JavaScriptCore/debugger/DebuggerCallFrame.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2008 Apple Inc. All rights reserved.
+ * Copyright (C) 2008, 2013, 2014 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -10,7 +10,7 @@
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
  *     documentation and/or other materials provided with the distribution.
- * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
+ * 3.  Neither the name of Apple Inc. ("Apple") nor the names of
  *     its contributors may be used to endorse or promote products derived
  *     from this software without specific prior written permission.
  *
@@ -29,39 +29,65 @@
 #ifndef DebuggerCallFrame_h
 #define DebuggerCallFrame_h
 
-#include "CallFrame.h"
+#include "DebuggerPrimitives.h"
+#include "Strong.h"
+#include <wtf/NakedPtr.h>
+#include <wtf/PassRefPtr.h>
+#include <wtf/RefCounted.h>
+#include <wtf/text/TextPosition.h>
 
 namespace JSC {
-    
-    class DebuggerCallFrame {
-    public:
-        enum Type { ProgramType, FunctionType };
 
-        DebuggerCallFrame(CallFrame* callFrame)
-            : m_callFrame(callFrame)
-        {
-        }
+class DebuggerScope;
+class Exception;
+class ExecState;
+typedef ExecState CallFrame;
 
-        DebuggerCallFrame(CallFrame* callFrame, JSValue exception)
-            : m_callFrame(callFrame)
-            , m_exception(exception)
-        {
-        }
+class DebuggerCallFrame : public RefCounted<DebuggerCallFrame> {
+public:
+    enum Type { ProgramType, FunctionType };
 
-        CallFrame* callFrame() const { return m_callFrame; }
-        JSGlobalObject* dynamicGlobalObject() const { return m_callFrame->dynamicGlobalObject(); }
-        JSScope* scope() const { return m_callFrame->scope(); }
-        JS_EXPORT_PRIVATE String functionName() const;
-        JS_EXPORT_PRIVATE String calculatedFunctionName() const;
-        JS_EXPORT_PRIVATE Type type() const;
-        JS_EXPORT_PRIVATE JSObject* thisObject() const;
-        JS_EXPORT_PRIVATE JSValue evaluate(const String&, JSValue& exception) const;
-        JSValue exception() const { return m_exception; }
+    static Ref<DebuggerCallFrame> create(CallFrame* callFrame)
+    {
+        return adoptRef(*new DebuggerCallFrame(callFrame));
+    }
 
-    private:
-        CallFrame* m_callFrame;
-        JSValue m_exception;
-    };
+    JS_EXPORT_PRIVATE explicit DebuggerCallFrame(CallFrame*);
+
+    JS_EXPORT_PRIVATE RefPtr<DebuggerCallFrame> callerFrame();
+    ExecState* exec() const { return m_callFrame; }
+    JS_EXPORT_PRIVATE SourceID sourceID() const;
+
+    // line and column are in base 0 e.g. the first line is line 0.
+    int line() const { return m_position.m_line.zeroBasedInt(); }
+    int column() const { return m_position.m_column.zeroBasedInt(); }
+    const TextPosition& position() const { return m_position; }
+
+    JS_EXPORT_PRIVATE JSGlobalObject* vmEntryGlobalObject() const;
+    JS_EXPORT_PRIVATE DebuggerScope* scope();
+    JS_EXPORT_PRIVATE String functionName() const;
+    JS_EXPORT_PRIVATE Type type() const;
+    JS_EXPORT_PRIVATE JSValue thisValue() const;
+    JSValue evaluate(const String&, NakedPtr<Exception>&);
+
+    bool isValid() const { return !!m_callFrame; }
+    JS_EXPORT_PRIVATE void invalidate();
+
+    // The following are only public for the Debugger's use only. They will be
+    // made private soon. Other clients should not use these.
+
+    JS_EXPORT_PRIVATE static TextPosition positionForCallFrame(CallFrame*);
+    JS_EXPORT_PRIVATE static SourceID sourceIDForCallFrame(CallFrame*);
+    static JSValue thisValueForCallFrame(CallFrame*);
+
+private:
+    CallFrame* m_callFrame;
+    RefPtr<DebuggerCallFrame> m_caller;
+    TextPosition m_position;
+    // The DebuggerPausedScope is responsible for calling invalidate() which,
+    // in turn, will clear this strong ref.
+    Strong<DebuggerScope> m_scope;
+};
 
 } // namespace JSC
 
diff --git a/Source/JavaScriptCore/debugger/DebuggerEvalEnabler.h b/Source/JavaScriptCore/debugger/DebuggerEvalEnabler.h
new file mode 100644
index 000000000..bb75b1f15
--- /dev/null
+++ b/Source/JavaScriptCore/debugger/DebuggerEvalEnabler.h
@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2014 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef DebuggerEvalEnabler_h
+#define DebuggerEvalEnabler_h
+
+#include "CallFrame.h"
+#include "JSGlobalObject.h"
+
+namespace JSC {
+
+class DebuggerEvalEnabler {
+public:
+    explicit DebuggerEvalEnabler(const ExecState* exec)
+        : m_exec(exec)
+        , m_evalWasDisabled(false)
+    {
+        if (exec) {
+            JSGlobalObject* globalObject = exec->lexicalGlobalObject();
+            m_evalWasDisabled = !globalObject->evalEnabled();
+            if (m_evalWasDisabled)
+                globalObject->setEvalEnabled(true, globalObject->evalDisabledErrorMessage());
+        }
+    }
+
+    ~DebuggerEvalEnabler()
+    {
+        if (m_evalWasDisabled) {
+            JSGlobalObject* globalObject = m_exec->lexicalGlobalObject();
+            globalObject->setEvalEnabled(false, globalObject->evalDisabledErrorMessage());
+        }
+    }
+
+private:
+    const ExecState* m_exec;
+    bool m_evalWasDisabled;
+};
+
+} // namespace JSC
+
+#endif // DebuggerEvalEnabler_h
diff --git a/Source/JavaScriptCore/debugger/DebuggerPrimitives.h b/Source/JavaScriptCore/debugger/DebuggerPrimitives.h
new file mode 100644
index 000000000..ab7301b5c
--- /dev/null
+++ b/Source/JavaScriptCore/debugger/DebuggerPrimitives.h
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2013 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+ */
+
+#ifndef DebuggerPrimitives_h
+#define DebuggerPrimitives_h
+
+#include <stddef.h>
+
+namespace JSC {
+
+typedef size_t SourceID;
+static const SourceID noSourceID = 0;
+
+typedef size_t BreakpointID;
+static const BreakpointID noBreakpointID = 0;
+
+} // namespace JSC
+
+#endif // DebuggerPrimitives_h
diff --git a/Source/JavaScriptCore/debugger/DebuggerScope.cpp b/Source/JavaScriptCore/debugger/DebuggerScope.cpp
new file mode 100644
index 000000000..c3efbd56d
--- /dev/null
+++ b/Source/JavaScriptCore/debugger/DebuggerScope.cpp
@@ -0,0 +1,218 @@
+/*
+ * Copyright (C) 2008-2009, 2014 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+ */
+
+#include "config.h"
+#include "DebuggerScope.h"
+
+#include "JSLexicalEnvironment.h"
+#include "JSCInlines.h"
+#include "JSWithScope.h"
+
+namespace JSC {
+
+STATIC_ASSERT_IS_TRIVIALLY_DESTRUCTIBLE(DebuggerScope);
+
+const ClassInfo DebuggerScope::s_info = { "DebuggerScope", &Base::s_info, 0, CREATE_METHOD_TABLE(DebuggerScope) };
+
+DebuggerScope::DebuggerScope(VM& vm, JSScope* scope)
+    : JSNonFinalObject(vm, scope->globalObject()->debuggerScopeStructure())
+{
+    ASSERT(scope);
+    m_scope.set(vm, this, scope);
+}
+
+void DebuggerScope::finishCreation(VM& vm)
+{
+    Base::finishCreation(vm);
+}
+
+void DebuggerScope::visitChildren(JSCell* cell, SlotVisitor& visitor)
+{
+    DebuggerScope* thisObject = jsCast<DebuggerScope*>(cell);
+    ASSERT_GC_OBJECT_INHERITS(thisObject, info());
+    JSObject::visitChildren(thisObject, visitor);
+    visitor.append(&thisObject->m_scope);
+    visitor.append(&thisObject->m_next);
+}
+
+String DebuggerScope::className(const JSObject* object)
+{
+    const DebuggerScope* scope = jsCast<const DebuggerScope*>(object);
+    ASSERT(scope->isValid());
+    if (!scope->isValid())
+        return String();
+    JSObject* thisObject = JSScope::objectAtScope(scope->jsScope());
+    return thisObject->methodTable()->className(thisObject);
+}
+
+bool DebuggerScope::getOwnPropertySlot(JSObject* object, ExecState* exec, PropertyName propertyName, PropertySlot& slot)
+{
+    DebuggerScope* scope = jsCast<DebuggerScope*>(object);
+    ASSERT(scope->isValid());
+    if (!scope->isValid())
+        return false;
+    JSObject* thisObject = JSScope::objectAtScope(scope->jsScope());
+    slot.setThisValue(JSValue(thisObject));
+
+    // By default, JSObject::getPropertySlot() will look in the DebuggerScope's prototype
+    // chain and not the wrapped scope, and JSObject::getPropertySlot() cannot be overridden
+    // to behave differently for the DebuggerScope.
+    //
+    // Instead, we'll treat all properties in the wrapped scope and its prototype chain as
+    // the own properties of the DebuggerScope. This is fine because the WebInspector
+    // does not presently need to distinguish between what's owned at each level in the
+    // prototype chain. Hence, we'll invoke getPropertySlot() on the wrapped scope here
+    // instead of getOwnPropertySlot().
+    bool result = thisObject->getPropertySlot(exec, propertyName, slot);
+    if (result && slot.isValue() && slot.getValue(exec, propertyName) == jsTDZValue()) {
+        // FIXME:
+        // We hit a scope property that has the TDZ empty value.
+        // Currently, we just lie to the inspector and claim that this property is undefined.
+        // This is not ideal and we should fix it.
+        // https://bugs.webkit.org/show_bug.cgi?id=144977
+        slot.setValue(slot.slotBase(), DontEnum, jsUndefined());
+        return true;
+    }
+    return result;
+}
+
+void DebuggerScope::put(JSCell* cell, ExecState* exec, PropertyName propertyName, JSValue value, PutPropertySlot& slot)
+{
+    DebuggerScope* scope = jsCast<DebuggerScope*>(cell);
+    ASSERT(scope->isValid());
+    if (!scope->isValid())
+        return;
+    JSObject* thisObject = JSScope::objectAtScope(scope->jsScope());
+    slot.setThisValue(JSValue(thisObject));
+    thisObject->methodTable()->put(thisObject, exec, propertyName, value, slot);
+}
+
+bool DebuggerScope::deleteProperty(JSCell* cell, ExecState* exec, PropertyName propertyName)
+{
+    DebuggerScope* scope = jsCast<DebuggerScope*>(cell);
+    ASSERT(scope->isValid());
+    if (!scope->isValid())
+        return false;
+    JSObject* thisObject = JSScope::objectAtScope(scope->jsScope());
+    return thisObject->methodTable()->deleteProperty(thisObject, exec, propertyName);
+}
+
+void DebuggerScope::getOwnPropertyNames(JSObject* object, ExecState* exec, PropertyNameArray& propertyNames, EnumerationMode mode)
+{
+    DebuggerScope* scope = jsCast<DebuggerScope*>(object);
+    ASSERT(scope->isValid());
+    if (!scope->isValid())
+        return;
+    JSObject* thisObject = JSScope::objectAtScope(scope->jsScope());
+    thisObject->methodTable()->getPropertyNames(thisObject, exec, propertyNames, mode);
+}
+
+bool DebuggerScope::defineOwnProperty(JSObject* object, ExecState* exec, PropertyName propertyName, const PropertyDescriptor& descriptor, bool shouldThrow)
+{
+    DebuggerScope* scope = jsCast<DebuggerScope*>(object);
+    ASSERT(scope->isValid());
+    if (!scope->isValid())
+        return false;
+    JSObject* thisObject = JSScope::objectAtScope(scope->jsScope());
+    return thisObject->methodTable()->defineOwnProperty(thisObject, exec, propertyName, descriptor, shouldThrow);
+}
+
+DebuggerScope* DebuggerScope::next()
+{
+    ASSERT(isValid());
+    if (!m_next && m_scope->next()) {
+        VM& vm = *m_scope->vm();
+        DebuggerScope* nextScope = create(vm, m_scope->next());
+        m_next.set(vm, this, nextScope);
+    }
+    return m_next.get();
+}
+
+void DebuggerScope::invalidateChain()
+{
+    if (!isValid())
+        return;
+
+    DebuggerScope* scope = this;
+    while (scope) {
+        DebuggerScope* nextScope = scope->m_next.get();
+        scope->m_next.clear();
+        scope->m_scope.clear(); // This also marks this scope as invalid.
+        scope = nextScope;
+    }
+}
+
+bool DebuggerScope::isCatchScope() const
+{
+    return m_scope->isCatchScope();
+}
+
+bool DebuggerScope::isFunctionNameScope() const
+{
+    return m_scope->isFunctionNameScopeObject();
+}
+
+bool DebuggerScope::isWithScope() const
+{
+    return m_scope->isWithScope();
+}
+
+bool DebuggerScope::isGlobalScope() const
+{
+    return m_scope->isGlobalObject();
+}
+
+bool DebuggerScope::isGlobalLexicalEnvironment() const
+{
+    return m_scope->isGlobalLexicalEnvironment();
+}
+
+bool DebuggerScope::isClosureScope() const
+{
+    // In the current debugger implementation, every function or eval will create an
+    // lexical environment object. Hence, a lexical environment object implies a
+    // function or eval scope.
+    return m_scope->isVarScope() || m_scope->isLexicalScope();
+}
+
+bool DebuggerScope::isNestedLexicalScope() const
+{
+    return m_scope->isNestedLexicalScope();
+}
+
+JSValue DebuggerScope::caughtValue(ExecState* exec) const
+{
+    ASSERT(isCatchScope());
+    JSLexicalEnvironment* catchEnvironment = jsCast<JSLexicalEnvironment*>(m_scope.get());
+    SymbolTable* catchSymbolTable = catchEnvironment->symbolTable();
+    RELEASE_ASSERT(catchSymbolTable->size() == 1);
+    PropertyName errorName(catchSymbolTable->begin(catchSymbolTable->m_lock)->key.get());
+    PropertySlot slot(m_scope.get(), PropertySlot::InternalMethodType::Get);
+    bool success = catchEnvironment->getOwnPropertySlot(catchEnvironment, exec, errorName, slot);
+    RELEASE_ASSERT(success && slot.isValue());
+    return slot.getValue(exec, errorName);
+}
+
+} // namespace JSC
diff --git a/Source/JavaScriptCore/debugger/DebuggerScope.h b/Source/JavaScriptCore/debugger/DebuggerScope.h
new file mode 100644
index 000000000..fef60c899
--- /dev/null
+++ b/Source/JavaScriptCore/debugger/DebuggerScope.h
@@ -0,0 +1,122 @@
+/*
+ * Copyright (C) 2008-2009, 2014 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+ */
+
+#ifndef DebuggerScope_h
+#define DebuggerScope_h
+
+#include "JSObject.h"
+
+namespace JSC {
+
+class DebuggerCallFrame;
+class JSScope;
+
+class DebuggerScope : public JSNonFinalObject {
+public:
+    typedef JSNonFinalObject Base;
+    static const unsigned StructureFlags = Base::StructureFlags | OverridesGetOwnPropertySlot | OverridesGetPropertyNames;
+
+    static DebuggerScope* create(VM& vm, JSScope* scope)
+    {
+        DebuggerScope* debuggerScope = new (NotNull, allocateCell<DebuggerScope>(vm.heap)) DebuggerScope(vm, scope);
+        debuggerScope->finishCreation(vm);
+        return debuggerScope;
+    }
+
+    static void visitChildren(JSCell*, SlotVisitor&);
+    static String className(const JSObject*);
+    static bool getOwnPropertySlot(JSObject*, ExecState*, PropertyName, PropertySlot&);
+    static void put(JSCell*, ExecState*, PropertyName, JSValue, PutPropertySlot&);
+    static bool deleteProperty(JSCell*, ExecState*, PropertyName);
+    static void getOwnPropertyNames(JSObject*, ExecState*, PropertyNameArray&, EnumerationMode);
+    static bool defineOwnProperty(JSObject*, ExecState*, PropertyName, const PropertyDescriptor&, bool shouldThrow);
+
+    DECLARE_EXPORT_INFO;
+
+    static Structure* createStructure(VM& vm, JSGlobalObject* globalObject) 
+    {
+        return Structure::create(vm, globalObject, jsNull(), TypeInfo(ObjectType, StructureFlags), info()); 
+    }
+
+    class iterator {
+    public:
+        iterator(DebuggerScope* node)
+            : m_node(node)
+        {
+        }
+
+        DebuggerScope* get() { return m_node; }
+        iterator& operator++() { m_node = m_node->next(); return *this; }
+        // postfix ++ intentionally omitted
+
+        bool operator==(const iterator& other) const { return m_node == other.m_node; }
+        bool operator!=(const iterator& other) const { return m_node != other.m_node; }
+
+    private:
+        DebuggerScope* m_node;
+    };
+
+    iterator begin();
+    iterator end();
+    DebuggerScope* next();
+
+    void invalidateChain();
+    bool isValid() const { return !!m_scope; }
+
+    bool isCatchScope() const;
+    bool isFunctionNameScope() const;
+    bool isWithScope() const;
+    bool isGlobalScope() const;
+    bool isClosureScope() const;
+    bool isGlobalLexicalEnvironment() const;
+    bool isNestedLexicalScope() const;
+
+    JSValue caughtValue(ExecState*) const;
+
+private:
+    JS_EXPORT_PRIVATE DebuggerScope(VM&, JSScope*);
+    JS_EXPORT_PRIVATE void finishCreation(VM&);
+
+    JSScope* jsScope() const { return m_scope.get(); }
+
+    WriteBarrier<JSScope> m_scope;
+    WriteBarrier<DebuggerScope> m_next;
+
+    friend class DebuggerCallFrame;
+};
+
+inline DebuggerScope::iterator DebuggerScope::begin()
+{
+    return iterator(this); 
+}
+
+inline DebuggerScope::iterator DebuggerScope::end()
+{ 
+    return iterator(0); 
+}
+
+} // namespace JSC
+
+#endif // DebuggerScope_h
diff --git a/Source/JavaScriptCore/debugger/ScriptProfilingScope.h b/Source/JavaScriptCore/debugger/ScriptProfilingScope.h
new file mode 100644
index 000000000..ba6bdfc51
--- /dev/null
+++ b/Source/JavaScriptCore/debugger/ScriptProfilingScope.h
@@ -0,0 +1,93 @@
+/*
+ * Copyright (C) 2015 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+ * THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef ScriptProfilingScope_h
+#define ScriptProfilingScope_h
+
+#include "Debugger.h"
+#include "JSGlobalObject.h"
+#include <wtf/Optional.h>
+
+namespace JSC {
+
+class ScriptProfilingScope {
+public:
+    ScriptProfilingScope(JSGlobalObject* globalObject, ProfilingReason reason)
+        : m_globalObject(globalObject)
+        , m_reason(reason)
+    {
+        if (shouldStartProfile())
+            m_startTime = m_globalObject->debugger()->willEvaluateScript();
+    }
+
+    ~ScriptProfilingScope()
+    {
+        if (shouldEndProfile())
+            m_globalObject->debugger()->didEvaluateScript(m_startTime.value(), m_reason);
+    }
+
+private:
+    bool shouldStartProfile() const
+    {
+        if (!m_globalObject)
+            return false;
+
+        if (!m_globalObject->hasDebugger())
+            return false;
+
+        if (!m_globalObject->debugger()->hasProfilingClient())
+            return false;
+
+        if (m_globalObject->debugger()->isAlreadyProfiling())
+            return false;
+
+        return true;
+    }
+
+    bool shouldEndProfile() const
+    {
+        // Did not start a profile.
+        if (!m_startTime)
+            return false;
+
+        // Debugger may have been removed.
+        if (!m_globalObject->hasDebugger())
+            return false;
+
+        // Profiling Client may have been removed.
+        if (!m_globalObject->debugger()->hasProfilingClient())
+            return false;
+
+        return true;
+    }
+
+    JSGlobalObject* m_globalObject { nullptr };
+    Optional<double> m_startTime;
+    ProfilingReason m_reason;
+};
+
+}
+
+#endif // ScriptProfilingScope_h