Merge remote-tracking branch 'origin/5.13' into dev

Change-Id: I9ba374f0c652628b7c84c36893c32b22529e384f

11 files changed, 190 insertions, 120 deletions

diff --git a/src/qml/compiler/qv4compilercontext.cpp b/src/qml/compiler/qv4compilercontext.cpp
index 7586611035..52215c2ce6 100644
--- a/src/qml/compiler/qv4compilercontext.cpp
+++ b/src/qml/compiler/qv4compilercontext.cpp
@@ -190,7 +190,7 @@ Context::ResolvedName Context::resolveName(const QString &name, const QQmlJS::AS
     if (c->contextType == ContextType::Eval)
         return result;
 
-    if (c->contextType == ContextType::Binding)
+    if (c->contextType == ContextType::Binding || c->contextType == ContextType::ScriptImportedByQML)
         result.type = ResolvedName::QmlGlobal;
     else
         result.type = ResolvedName::Global;
diff --git a/src/qml/jsruntime/qv4arrayobject.cpp b/src/qml/jsruntime/qv4arrayobject.cpp
index b975d02d9d..b3e607d74a 100644
--- a/src/qml/jsruntime/qv4arrayobject.cpp
+++ b/src/qml/jsruntime/qv4arrayobject.cpp
@@ -103,7 +103,9 @@ void ArrayPrototype::init(ExecutionEngine *engine, Object *ctor)
     ctor->defineDefaultProperty(QStringLiteral("from"), method_from, 1);
     ctor->addSymbolSpecies();
 
-    ScopedObject unscopables(scope, engine->newObject(engine->classes[EngineBase::Class_Empty]->changeVTable(QV4::Object::staticVTable())));
+    Scoped<InternalClass> ic(scope, engine->classes[EngineBase::Class_Empty]
+                                            ->changeVTable(QV4::Object::staticVTable()));
+    ScopedObject unscopables(scope, engine->newObject(ic->d()));
     ScopedString name(scope);
     defineDefaultProperty(QStringLiteral("constructor"), (o = ctor));
     defineDefaultProperty(engine->id_toString(), method_toString, 0);
diff --git a/src/qml/jsruntime/qv4engine.cpp b/src/qml/jsruntime/qv4engine.cpp
index 8a849ddf5f..fdc2118840 100644
--- a/src/qml/jsruntime/qv4engine.cpp
+++ b/src/qml/jsruntime/qv4engine.cpp
@@ -470,11 +470,17 @@ ExecutionEngine::ExecutionEngine(QJSEngine *jsEngine)
     jsObjects[TypeError_Ctor] = memoryManager->allocate<TypeErrorCtor>(global);
     jsObjects[URIError_Ctor] = memoryManager->allocate<URIErrorCtor>(global);
     jsObjects[IteratorProto] = memoryManager->allocate<IteratorPrototype>();
-    jsObjects[ForInIteratorProto] = memoryManager->allocObject<ForInIteratorPrototype>(newInternalClass(ForInIteratorPrototype::staticVTable(), iteratorPrototype()));
-    jsObjects[MapIteratorProto] = memoryManager->allocObject<MapIteratorPrototype>(newInternalClass(SetIteratorPrototype::staticVTable(), iteratorPrototype()));
-    jsObjects[SetIteratorProto] = memoryManager->allocObject<SetIteratorPrototype>(newInternalClass(SetIteratorPrototype::staticVTable(), iteratorPrototype()));
-    jsObjects[ArrayIteratorProto] = memoryManager->allocObject<ArrayIteratorPrototype>(newInternalClass(ArrayIteratorPrototype::staticVTable(), iteratorPrototype()));
-    jsObjects[StringIteratorProto] = memoryManager->allocObject<StringIteratorPrototype>(newInternalClass(StringIteratorPrototype::staticVTable(), iteratorPrototype()));
+
+    ic = newInternalClass(ForInIteratorPrototype::staticVTable(), iteratorPrototype());
+    jsObjects[ForInIteratorProto] = memoryManager->allocObject<ForInIteratorPrototype>(ic);
+    ic = newInternalClass(SetIteratorPrototype::staticVTable(), iteratorPrototype());
+    jsObjects[MapIteratorProto] = memoryManager->allocObject<MapIteratorPrototype>(ic);
+    ic = newInternalClass(SetIteratorPrototype::staticVTable(), iteratorPrototype());
+    jsObjects[SetIteratorProto] = memoryManager->allocObject<SetIteratorPrototype>(ic);
+    ic = newInternalClass(ArrayIteratorPrototype::staticVTable(), iteratorPrototype());
+    jsObjects[ArrayIteratorProto] = memoryManager->allocObject<ArrayIteratorPrototype>(ic);
+    ic = newInternalClass(StringIteratorPrototype::staticVTable(), iteratorPrototype());
+    jsObjects[StringIteratorProto] = memoryManager->allocObject<StringIteratorPrototype>(ic);
 
     str = newString(QStringLiteral("get [Symbol.species]"));
     jsObjects[GetSymbolSpecies] = FunctionObject::createBuiltinFunction(this, str, ArrayPrototype::method_get_species, 0);
diff --git a/src/qml/jsruntime/qv4generatorobject.cpp b/src/qml/jsruntime/qv4generatorobject.cpp
index 566db6fd4e..14caa6953f 100644
--- a/src/qml/jsruntime/qv4generatorobject.cpp
+++ b/src/qml/jsruntime/qv4generatorobject.cpp
@@ -139,7 +139,9 @@ void GeneratorPrototype::init(ExecutionEngine *engine, Object *ctor)
     Scope scope(engine);
     ScopedValue v(scope);
 
-    ScopedObject ctorProto(scope, engine->newObject(engine->newInternalClass(Object::staticVTable(), engine->functionPrototype())));
+    Scoped<InternalClass> ic(scope, engine->newInternalClass(
+                                            Object::staticVTable(), engine->functionPrototype()));
+    ScopedObject ctorProto(scope, engine->newObject(ic->d()));
 
     ctor->defineReadonlyConfigurableProperty(engine->id_length(), Value::fromInt32(1));
     ctor->defineReadonlyProperty(engine->id_prototype(), ctorProto);
diff --git a/src/qml/jsruntime/qv4internalclass.cpp b/src/qml/jsruntime/qv4internalclass.cpp
index 9906e2b1a0..a10fda79f2 100644
--- a/src/qml/jsruntime/qv4internalclass.cpp
+++ b/src/qml/jsruntime/qv4internalclass.cpp
@@ -44,6 +44,7 @@
 #include "qv4object_p.h"
 #include "qv4identifiertable_p.h"
 #include "qv4value_p.h"
+#include "qv4mm_p.h"
 
 QT_BEGIN_NAMESPACE
 
@@ -144,7 +145,7 @@ SharedInternalClassDataPrivate<PropertyKey>::SharedInternalClassDataPrivate(cons
       data(nullptr)
 {
     if (other.alloc()) {
-        int s = other.size();
+        const uint s = other.size();
         data = MemberData::allocate(engine, other.alloc(), other.data);
         setSize(s);
     }
@@ -163,8 +164,8 @@ SharedInternalClassDataPrivate<PropertyKey>::SharedInternalClassDataPrivate(cons
 
 void SharedInternalClassDataPrivate<PropertyKey>::grow()
 {
-    uint a = alloc() * 2;
-    int s = size();
+    const uint a = alloc() * 2;
+    const uint s = size();
     data = MemberData::allocate(engine, a, data);
     setSize(s);
     Q_ASSERT(alloc() >= a);
@@ -204,7 +205,70 @@ void SharedInternalClassDataPrivate<PropertyKey>::mark(MarkStack *s)
         data->mark(s);
 }
 
+SharedInternalClassDataPrivate<PropertyAttributes>::SharedInternalClassDataPrivate(
+        const SharedInternalClassDataPrivate<PropertyAttributes> &other, uint pos,
+        PropertyAttributes value)
+    : refcount(1),
+      m_alloc(qMin(other.m_alloc, pos + 8)),
+      m_size(pos + 1),
+      m_engine(other.m_engine)
+{
+    Q_ASSERT(m_size <= m_alloc);
+    m_engine->memoryManager->changeUnmanagedHeapSizeUsage(m_alloc * sizeof(PropertyAttributes));
+    data = new PropertyAttributes[m_alloc];
+    if (other.data)
+        memcpy(data, other.data, (m_size - 1) * sizeof(PropertyAttributes));
+    data[pos] = value;
+}
+
+SharedInternalClassDataPrivate<PropertyAttributes>::SharedInternalClassDataPrivate(
+        const SharedInternalClassDataPrivate<PropertyAttributes> &other)
+    : refcount(1),
+      m_alloc(other.m_alloc),
+      m_size(other.m_size),
+      m_engine(other.m_engine)
+{
+    if (m_alloc) {
+        m_engine->memoryManager->changeUnmanagedHeapSizeUsage(m_alloc * sizeof(PropertyAttributes));
+        data = new PropertyAttributes[m_alloc];
+        memcpy(data, other.data, m_size*sizeof(PropertyAttributes));
+    } else {
+        data = nullptr;
+    }
+}
 
+SharedInternalClassDataPrivate<PropertyAttributes>::~SharedInternalClassDataPrivate()
+{
+    m_engine->memoryManager->changeUnmanagedHeapSizeUsage(
+            -qptrdiff(m_alloc * sizeof(PropertyAttributes)));
+    delete [] data;
+}
+
+void SharedInternalClassDataPrivate<PropertyAttributes>::grow() {
+    uint alloc;
+    if (!m_alloc) {
+        alloc = 8;
+        m_engine->memoryManager->changeUnmanagedHeapSizeUsage(alloc * sizeof(PropertyAttributes));
+    } else {
+        // yes, signed. We don't want to deal with stuff > 2G
+        const uint currentSize = m_alloc * sizeof(PropertyAttributes);
+        if (currentSize < uint(std::numeric_limits<int>::max() / 2))
+            alloc = m_alloc * 2;
+        else
+            alloc = std::numeric_limits<int>::max() / sizeof(PropertyAttributes);
+
+        m_engine->memoryManager->changeUnmanagedHeapSizeUsage(
+                (alloc - m_alloc) * sizeof(PropertyAttributes));
+    }
+
+    auto *n = new PropertyAttributes[alloc];
+    if (data) {
+        memcpy(n, data, m_alloc*sizeof(PropertyAttributes));
+        delete [] data;
+    }
+    data = n;
+    m_alloc = alloc;
+}
 
 namespace Heap {
 
@@ -602,11 +666,10 @@ Heap::InternalClass *InternalClass::frozen()
     return f;
 }
 
-Heap::InternalClass *InternalClass::propertiesFrozen() const
+Heap::InternalClass *InternalClass::propertiesFrozen()
 {
     Scope scope(engine);
-    Scoped<QV4::InternalClass> frozen(scope, engine->internalClasses(EngineBase::Class_Empty)->changeVTable(vtable));
-    frozen = frozen->changePrototype(prototype);
+    Scoped<QV4::InternalClass> frozen(scope, this);
     for (uint i = 0; i < size; ++i) {
         PropertyAttributes attrs = propertyData.at(i);
         if (!nameMap.at(i).isValid())
@@ -615,7 +678,7 @@ Heap::InternalClass *InternalClass::propertiesFrozen() const
             attrs.setWritable(false);
             attrs.setConfigurable(false);
         }
-        frozen = frozen->addMember(nameMap.at(i), attrs);
+        frozen = frozen->changeMember(nameMap.at(i), attrs);
     }
     return frozen->d();
 }
diff --git a/src/qml/jsruntime/qv4internalclass_p.h b/src/qml/jsruntime/qv4internalclass_p.h
index 681cbda5f9..42b61218a5 100644
--- a/src/qml/jsruntime/qv4internalclass_p.h
+++ b/src/qml/jsruntime/qv4internalclass_p.h
@@ -149,55 +149,31 @@ inline PropertyHash::Entry *PropertyHash::lookup(PropertyKey identifier) const
     }
 }
 
-template<typename T>
-struct SharedInternalClassDataPrivate {
-    SharedInternalClassDataPrivate(ExecutionEngine *)
+template<class T>
+struct SharedInternalClassDataPrivate {};
+
+template<>
+struct SharedInternalClassDataPrivate<PropertyAttributes> {
+    SharedInternalClassDataPrivate(ExecutionEngine *engine)
         : refcount(1),
           m_alloc(0),
           m_size(0),
-          data(nullptr)
+          data(nullptr),
+          m_engine(engine)
     { }
-    SharedInternalClassDataPrivate(const SharedInternalClassDataPrivate &other)
-        : refcount(1),
-          m_alloc(other.m_alloc),
-          m_size(other.m_size)
-    {
-        if (m_alloc) {
-            data = new T[m_alloc];
-            memcpy(data, other.data, m_size*sizeof(T));
-        }
-    }
-    SharedInternalClassDataPrivate(const SharedInternalClassDataPrivate &other, uint pos, T value)
-        : refcount(1),
-          m_alloc(pos + 8),
-          m_size(pos + 1)
-    {
-        data = new T[m_alloc];
-        if (other.data)
-            memcpy(data, other.data, (m_size - 1)*sizeof(T));
-        data[pos] = value;
-    }
-    ~SharedInternalClassDataPrivate() { delete [] data; }
-
+    SharedInternalClassDataPrivate(const SharedInternalClassDataPrivate<PropertyAttributes> &other);
+    SharedInternalClassDataPrivate(const SharedInternalClassDataPrivate<PropertyAttributes> &other,
+                                   uint pos, PropertyAttributes value);
+    ~SharedInternalClassDataPrivate();
 
-    void grow() {
-        if (!m_alloc)
-            m_alloc = 4;
-        T *n = new T[m_alloc * 2];
-        if (data) {
-            memcpy(n, data, m_alloc*sizeof(T));
-            delete [] data;
-        }
-        data = n;
-        m_alloc *= 2;
-    }
+    void grow();
 
     uint alloc() const { return m_alloc; }
     uint size() const { return m_size; }
     void setSize(uint s) { m_size = s; }
 
-    T at(uint i) { Q_ASSERT(data && i < m_alloc); return data[i]; }
-    void set(uint i, T t) { Q_ASSERT(data && i < m_alloc); data[i] = t; }
+    PropertyAttributes at(uint i) { Q_ASSERT(data && i < m_alloc); return data[i]; }
+    void set(uint i, PropertyAttributes t) { Q_ASSERT(data && i < m_alloc); data[i] = t; }
 
     void mark(MarkStack *) {}
 
@@ -205,7 +181,8 @@ struct SharedInternalClassDataPrivate {
 private:
     uint m_alloc;
     uint m_size;
-    T *data;
+    PropertyAttributes *data;
+    ExecutionEngine *m_engine;
 };
 
 template<>
@@ -270,8 +247,12 @@ struct SharedInternalClassData {
         Q_ASSERT(pos == d->size());
         if (pos == d->alloc())
             d->grow();
-        d->setSize(d->size() + 1);
-        d->set(pos, value);
+        if (pos >= d->alloc()) {
+            qBadAlloc();
+        } else {
+            d->setSize(d->size() + 1);
+            d->set(pos, value);
+        }
     }
 
     void set(uint pos, T value) {
@@ -451,7 +432,7 @@ struct InternalClass : Base {
 
     Q_REQUIRED_RESULT InternalClass *sealed();
     Q_REQUIRED_RESULT InternalClass *frozen();
-    Q_REQUIRED_RESULT InternalClass *propertiesFrozen() const;
+    Q_REQUIRED_RESULT InternalClass *propertiesFrozen();
 
     Q_REQUIRED_RESULT InternalClass *asProtoClass();
 
diff --git a/src/qml/jsruntime/qv4memberdata.cpp b/src/qml/jsruntime/qv4memberdata.cpp
index 246f857643..f327c85001 100644
--- a/src/qml/jsruntime/qv4memberdata.cpp
+++ b/src/qml/jsruntime/qv4memberdata.cpp
@@ -69,12 +69,25 @@ Heap::MemberData *MemberData::allocate(ExecutionEngine *e, uint n, Heap::MemberD
     size_t alloc = MemoryManager::align(sizeof(Heap::MemberData) + (n - 1)*sizeof(Value));
     // round up to next power of two to avoid quadratic behaviour for very large objects
     alloc = nextPowerOfTwo(alloc);
-    Heap::MemberData *m = e->memoryManager->allocManaged<MemberData>(alloc);
-    if (old)
+
+    // The above code can overflow in a number of interesting ways. All of those are unsigned,
+    // and therefore defined behavior. Still, apply some sane bounds.
+    if (alloc > std::numeric_limits<int>::max())
+        alloc = std::numeric_limits<int>::max();
+
+    Heap::MemberData *m;
+    if (old) {
+        const size_t oldSize = sizeof(Heap::MemberData) + (old->values.size - 1) * sizeof(Value);
+        if (oldSize > alloc)
+            alloc = oldSize;
+        m = e->memoryManager->allocManaged<MemberData>(alloc);
         // no write barrier required here
-        memcpy(m, old, sizeof(Heap::MemberData) + (old->values.size - 1) * sizeof(Value));
-    else
+        memcpy(m, old, oldSize);
+    } else {
+        m = e->memoryManager->allocManaged<MemberData>(alloc);
         m->init();
+    }
+
     m->values.alloc = static_cast<uint>((alloc - sizeof(Heap::MemberData) + sizeof(Value))/sizeof(Value));
     m->values.size = m->values.alloc;
     return m;
diff --git a/src/qml/jsruntime/qv4qmlcontext.cpp b/src/qml/jsruntime/qv4qmlcontext.cpp
index a2c8e3916f..12ada7ee70 100644
--- a/src/qml/jsruntime/qv4qmlcontext.cpp
+++ b/src/qml/jsruntime/qv4qmlcontext.cpp
@@ -465,10 +465,23 @@ ReturnedValue QQmlContextWrapper::resolveQmlContextPropertyLookupGetter(Lookup *
             return static_cast<Heap::CallContext*>(ctx.d())->locals[index].asReturnedValue();
     }
 
-    Scoped<QQmlContextWrapper> qmlContext(scope, engine->qmlContext()->qml());
     bool hasProperty = false;
-    ScopedValue result(scope, QQmlContextWrapper::getPropertyAndBase(qmlContext, name, /*receiver*/nullptr,
-                                                                     &hasProperty, base, l));
+    ScopedValue result(scope);
+
+    Scoped<QmlContext> callingQmlContext(scope, engine->qmlContext());
+    if (callingQmlContext) {
+        Scoped<QQmlContextWrapper> qmlContextWrapper(scope, callingQmlContext->d()->qml());
+        result = QQmlContextWrapper::getPropertyAndBase(qmlContextWrapper, name, /*receiver*/nullptr, &hasProperty,
+                                                        base, l);
+    } else {
+        // Code path typical to worker scripts, compiled with lookups but no qml context.
+        result = l->resolveGlobalGetter(engine);
+        if (l->globalGetter != Lookup::globalGetterGeneric) {
+            hasProperty = true;
+            l->qmlContextGlobalLookup.getterTrampoline = l->globalGetter;
+            l->qmlContextPropertyGetter = QQmlContextWrapper::lookupInGlobalObject;
+        }
+    }
     if (!hasProperty)
         return engine->throwReferenceError(name.toQString());
     return result->asReturnedValue();
diff --git a/src/qml/jsruntime/qv4script.cpp b/src/qml/jsruntime/qv4script.cpp
index 7bbef3335e..6cb2e95cdc 100644
--- a/src/qml/jsruntime/qv4script.cpp
+++ b/src/qml/jsruntime/qv4script.cpp
@@ -201,7 +201,6 @@ QQmlRefPointer<QV4::CompiledData::CompilationUnit> Script::precompile(QV4::Compi
     }
 
     Codegen cg(unitGenerator, /*strict mode*/false);
-    cg.setUseFastLookups(false);
     cg.generateFromProgram(fileName, finalUrl, source, program, module, contextType);
     errors = cg.qmlErrors();
     if (!errors.isEmpty()) {
diff --git a/src/qml/memory/qv4mm.cpp b/src/qml/memory/qv4mm.cpp
index b3d9155ebc..34d334a24d 100644
--- a/src/qml/memory/qv4mm.cpp
+++ b/src/qml/memory/qv4mm.cpp
@@ -93,8 +93,6 @@
 #include <pthread_np.h>
 #endif
 
-#define MIN_UNMANAGED_HEAPSIZE_GC_LIMIT std::size_t(128 * 1024)
-
 Q_LOGGING_CATEGORY(lcGcStats, "qt.qml.gc.statistics")
 Q_DECLARE_LOGGING_CATEGORY(lcGcStats)
 Q_LOGGING_CATEGORY(lcGcAllocatorStats, "qt.qml.gc.allocatorStats")
@@ -759,7 +757,7 @@ MemoryManager::MemoryManager(ExecutionEngine *engine)
     , hugeItemAllocator(chunkAllocator, engine)
     , m_persistentValues(new PersistentValueStorage(engine))
     , m_weakValues(new PersistentValueStorage(engine))
-    , unmanagedHeapSizeGCLimit(MIN_UNMANAGED_HEAPSIZE_GC_LIMIT)
+    , unmanagedHeapSizeGCLimit(MinUnmanagedHeapSizeGCLimit)
     , aggressiveGC(!qEnvironmentVariableIsEmpty("QV4_MM_AGGRESSIVE_GC"))
     , gcStats(lcGcStats().isDebugEnabled())
     , gcCollectorStats(lcGcAllocatorStats().isDebugEnabled())
@@ -779,35 +777,9 @@ Heap::Base *MemoryManager::allocString(std::size_t unmanagedSize)
     lastAllocRequestedSlots = stringSize >> Chunk::SlotSizeShift;
     ++allocationCount;
 #endif
-
-    bool didGCRun = false;
-    if (aggressiveGC) {
-        runGC();
-        didGCRun = true;
-    }
-
     unmanagedHeapSize += unmanagedSize;
-    if (unmanagedHeapSize > unmanagedHeapSizeGCLimit) {
-        if (!didGCRun)
-            runGC();
-
-        if (3*unmanagedHeapSizeGCLimit <= 4*unmanagedHeapSize)
-            // more than 75% full, raise limit
-            unmanagedHeapSizeGCLimit = std::max(unmanagedHeapSizeGCLimit, unmanagedHeapSize) * 2;
-        else if (unmanagedHeapSize * 4 <= unmanagedHeapSizeGCLimit)
-            // less than 25% full, lower limit
-            unmanagedHeapSizeGCLimit = qMax(MIN_UNMANAGED_HEAPSIZE_GC_LIMIT, unmanagedHeapSizeGCLimit/2);
-        didGCRun = true;
-    }
-
-    HeapItem *m = blockAllocator.allocate(stringSize);
-    if (!m) {
-        if (!didGCRun && shouldRunGC())
-            runGC();
-        m = blockAllocator.allocate(stringSize, true);
-    }
 
-//    qDebug() << "allocated string" << m;
+    HeapItem *m = allocate(&blockAllocator, stringSize);
     memset(m, 0, stringSize);
     return *m;
 }
@@ -819,32 +791,11 @@ Heap::Base *MemoryManager::allocData(std::size_t size)
     ++allocationCount;
 #endif
 
-    bool didRunGC = false;
-    if (aggressiveGC) {
-        runGC();
-        didRunGC = true;
-    }
-
     Q_ASSERT(size >= Chunk::SlotSize);
     Q_ASSERT(size % Chunk::SlotSize == 0);
 
-//    qDebug() << "unmanagedHeapSize:" << unmanagedHeapSize << "limit:" << unmanagedHeapSizeGCLimit << "unmanagedSize:" << unmanagedSize;
-
-    if (size > Chunk::DataSize) {
-        HeapItem *h = hugeItemAllocator.allocate(size);
-//        qDebug() << "allocating huge item" << h;
-        return *h;
-    }
-
-    HeapItem *m = blockAllocator.allocate(size);
-    if (!m) {
-        if (!didRunGC && shouldRunGC())
-            runGC();
-        m = blockAllocator.allocate(size, true);
-    }
-
+    HeapItem *m = allocate(&blockAllocator, size);
     memset(m, 0, size);
-//    qDebug() << "allocating data" << m;
     return *m;
 }
 
diff --git a/src/qml/memory/qv4mm_p.h b/src/qml/memory/qv4mm_p.h
index bbbbb1aef6..6dfdd81cb2 100644
--- a/src/qml/memory/qv4mm_p.h
+++ b/src/qml/memory/qv4mm_p.h
@@ -264,13 +264,13 @@ public:
     size_t getLargeItemsMem() const;
 
     // called when a JS object grows itself. Specifically: Heap::String::append
+    // and InternalClassDataPrivate<PropertyAttributes>.
     void changeUnmanagedHeapSizeUsage(qptrdiff delta) { unmanagedHeapSize += delta; }
 
     template<typename ManagedType>
     typename ManagedType::Data *allocIC()
     {
-        size_t size = align(sizeof(typename ManagedType::Data));
-        Heap::Base *b = *icAllocator.allocate(size, true);
+        Heap::Base *b = *allocate(&icAllocator, align(sizeof(typename ManagedType::Data)));
         return static_cast<typename ManagedType::Data *>(b);
     }
 
@@ -284,12 +284,52 @@ protected:
     Heap::Object *allocObjectWithMemberData(const QV4::VTable *vtable, uint nMembers);
 
 private:
+    enum {
+        MinUnmanagedHeapSizeGCLimit = 128 * 1024
+    };
+
     void collectFromJSStack(MarkStack *markStack) const;
     void mark();
     void sweep(bool lastSweep = false, ClassDestroyStatsCallback classCountPtr = nullptr);
     bool shouldRunGC() const;
     void collectRoots(MarkStack *markStack);
 
+    HeapItem *allocate(BlockAllocator *allocator, std::size_t size)
+    {
+        bool didGCRun = false;
+        if (aggressiveGC) {
+            runGC();
+            didGCRun = true;
+        }
+
+        if (unmanagedHeapSize > unmanagedHeapSizeGCLimit) {
+            if (!didGCRun)
+                runGC();
+
+            if (3*unmanagedHeapSizeGCLimit <= 4 * unmanagedHeapSize) {
+                // more than 75% full, raise limit
+                unmanagedHeapSizeGCLimit = std::max(unmanagedHeapSizeGCLimit,
+                                                    unmanagedHeapSize) * 2;
+            } else if (unmanagedHeapSize * 4 <= unmanagedHeapSizeGCLimit) {
+                // less than 25% full, lower limit
+                unmanagedHeapSizeGCLimit = qMax(std::size_t(MinUnmanagedHeapSizeGCLimit),
+                                                unmanagedHeapSizeGCLimit/2);
+            }
+            didGCRun = true;
+        }
+
+        if (size > Chunk::DataSize)
+            return hugeItemAllocator.allocate(size);
+
+        if (HeapItem *m = allocator->allocate(size))
+            return m;
+
+        if (!didGCRun && shouldRunGC())
+            runGC();
+
+        return allocator->allocate(size, true);
+    }
+
 public:
     QV4::ExecutionEngine *engine;
     ChunkAllocator *chunkAllocator;