8 files changed, 21 insertions, 18 deletions
diff --git a/src/qml/jsruntime/qv4engine.cpp b/src/qml/jsruntime/qv4engine.cpp
index 8f2c5174da..a11f7f0875 100644
--- a/src/qml/jsruntime/qv4engine.cpp
+++ b/src/qml/jsruntime/qv4engine.cpp
@@ -158,8 +158,6 @@ ExecutionEngine::ExecutionEngine(EvalISelFactory *factory)
     }
     Q_ASSERT(maxCallDepth > 0);
 
-    MemoryManager::GCBlocker gcBlocker(memoryManager);
-
     if (!factory) {
 #if QT_CONFIG(qml_interpreter)
         bool jitDisabled = true;
diff --git a/src/qml/jsruntime/qv4global_p.h b/src/qml/jsruntime/qv4global_p.h
index c37ad1668d..1dbc538be2 100644
--- a/src/qml/jsruntime/qv4global_p.h
+++ b/src/qml/jsruntime/qv4global_p.h
@@ -97,19 +97,19 @@ inline double trunc(double d) { return d > 0 ? floor(d) : ceil(d); }
 //
 // NOTE: This should match the logic in qv4targetplatform_p.h!
 
-#if defined(Q_PROCESSOR_X86) && !defined(__ILP32__) \
+#if defined(Q_PROCESSOR_X86) && (QT_POINTER_SIZE == 4) \
     && (defined(Q_OS_WIN) || defined(Q_OS_LINUX) || defined(Q_OS_QNX) || defined(Q_OS_FREEBSD))
 #  define V4_ENABLE_JIT
-#elif defined(Q_PROCESSOR_X86_64) && !defined(__ILP32__) \
+#elif defined(Q_PROCESSOR_X86_64) && (QT_POINTER_SIZE == 8) \
     && (defined(Q_OS_WIN) || defined(Q_OS_LINUX) || defined(Q_OS_MAC) || defined(Q_OS_FREEBSD))
 #  define V4_ENABLE_JIT
-#elif defined(Q_PROCESSOR_ARM_32)
+#elif defined(Q_PROCESSOR_ARM_32) && (QT_POINTER_SIZE == 4)
 #  if defined(thumb2) || defined(__thumb2__) || ((defined(__thumb) || defined(__thumb__)) && __TARGET_ARCH_THUMB-0 == 4)
 #    define V4_ENABLE_JIT
 #  elif defined(__ARM_ARCH_ISA_THUMB) && __ARM_ARCH_ISA_THUMB == 2 // clang 3.5 and later will set this if the core supports the Thumb-2 ISA.
 #    define V4_ENABLE_JIT
 #  endif
-#elif defined(Q_PROCESSOR_ARM_64)
+#elif defined(Q_PROCESSOR_ARM_64) && (QT_POINTER_SIZE == 8)
 #  if defined(Q_OS_LINUX)
 #    define V4_ENABLE_JIT
 #  endif
diff --git a/src/qml/jsruntime/qv4profiling_p.h b/src/qml/jsruntime/qv4profiling_p.h
index d27e853343..f75ac4d33a 100644
--- a/src/qml/jsruntime/qv4profiling_p.h
+++ b/src/qml/jsruntime/qv4profiling_p.h
@@ -158,12 +158,11 @@ public:
 
     FunctionCall &operator=(const FunctionCall &other) {
         if (&other != this) {
-            if (m_function)
-                m_function->compilationUnit->release();
+            other.m_function->compilationUnit->addref();
+            m_function->compilationUnit->release();
             m_function = other.m_function;
             m_start = other.m_start;
             m_end = other.m_end;
-            m_function->compilationUnit->addref();
         }
         return *this;
     }
diff --git a/src/qml/jsruntime/qv4regexpobject.cpp b/src/qml/jsruntime/qv4regexpobject.cpp
index 218695624b..41d8010fef 100644
--- a/src/qml/jsruntime/qv4regexpobject.cpp
+++ b/src/qml/jsruntime/qv4regexpobject.cpp
@@ -307,7 +307,8 @@ void RegExpCtor::markObjects(Heap::Base *that, ExecutionEngine *e)
 {
     RegExpCtor::Data *This = static_cast<RegExpCtor::Data *>(that);
     This->lastMatch.mark(e);
-    This->lastInput->mark(e);
+    if (This->lastInput)
+        This->lastInput->mark(e);
     FunctionObject::markObjects(that, e);
 }
 
diff --git a/src/qml/jsruntime/qv4runtime.cpp b/src/qml/jsruntime/qv4runtime.cpp
index d6c55926b1..023a739e33 100644
--- a/src/qml/jsruntime/qv4runtime.cpp
+++ b/src/qml/jsruntime/qv4runtime.cpp
@@ -499,6 +499,7 @@ Heap::String *RuntimeHelpers::convertToString(ExecutionEngine *engine, const Val
         {
             Scope scope(engine);
             ScopedValue prim(scope, RuntimeHelpers::toPrimitive(value, STRING_HINT));
+            Q_ASSERT(!prim->isManaged() || prim->isString());
             return RuntimeHelpers::convertToString(engine, prim);
         }
     case Value::Integer_Type:
diff --git a/src/qml/jsruntime/qv4script.cpp b/src/qml/jsruntime/qv4script.cpp
index b54177bee9..62145f36cc 100644
--- a/src/qml/jsruntime/qv4script.cpp
+++ b/src/qml/jsruntime/qv4script.cpp
@@ -88,8 +88,6 @@ void Script::parse()
     ExecutionEngine *v4 = scope->engine();
     Scope valueScope(v4);
 
-    MemoryManager::GCBlocker gcBlocker(v4->memoryManager);
-
     IR::Module module(v4->debugger() != 0);
 
     QQmlJS::Engine ee, *engine = &ee;
diff --git a/src/qml/jsruntime/qv4string.cpp b/src/qml/jsruntime/qv4string.cpp
index 1efd8cb714..cde2131aab 100644
--- a/src/qml/jsruntime/qv4string.cpp
+++ b/src/qml/jsruntime/qv4string.cpp
@@ -102,6 +102,7 @@ void Heap::String::init(MemoryManager *mm, String *l, String *r)
     stringHash = UINT_MAX;
     largestSubLength = qMax(l->largestSubLength, r->largestSubLength);
     len = l->len + r->len;
+    Q_ASSERT(largestSubLength <= len);
 
     if (!l->largestSubLength && l->len > largestSubLength)
         largestSubLength = l->len;
@@ -113,6 +114,15 @@ void Heap::String::init(MemoryManager *mm, String *l, String *r)
         simplifyString();
 }
 
+void Heap::String::destroy() {
+    if (!largestSubLength) {
+        mm->changeUnmanagedHeapSizeUsage(qptrdiff(-text->size) * (int)sizeof(QChar));
+        if (!text->ref.deref())
+            QStringData::deallocate(text);
+    }
+    Base::destroy();
+}
+
 uint String::toUInt(bool *ok) const
 {
     *ok = true;
@@ -151,7 +161,7 @@ void Heap::String::simplifyString() const
     text->ref.ref();
     identifier = 0;
     largestSubLength = 0;
-    mm->growUnmanagedHeapSizeUsage(size_t(text->size) * sizeof(QChar));
+    mm->changeUnmanagedHeapSizeUsage(qptrdiff(text->size) * (qptrdiff)sizeof(QChar));
 }
 
 void Heap::String::append(const String *data, QChar *ch)
diff --git a/src/qml/jsruntime/qv4string_p.h b/src/qml/jsruntime/qv4string_p.h
index 4890a85724..5b0fd292d6 100644
--- a/src/qml/jsruntime/qv4string_p.h
+++ b/src/qml/jsruntime/qv4string_p.h
@@ -73,11 +73,7 @@ struct Q_QML_PRIVATE_EXPORT String : Base {
 #ifndef V4_BOOTSTRAP
     void init(MemoryManager *mm, const QString &text);
     void init(MemoryManager *mm, String *l, String *n);
-    void destroy() {
-        if (!largestSubLength && !text->ref.deref())
-            QStringData::deallocate(text);
-        Base::destroy();
-    }
+    void destroy();
     void simplifyString() const;
     int length() const {
         Q_ASSERT((largestSubLength &&