Optimize Runtime::method_get/setElement

This is now actually just as fast as the lookup code,
so disable the generation of lookups for indexed accesses
for now. This saves some runtime memory, as we don't
need the data structures for the lookup.

We can reintroduce lookups, once they offer a real
performance benefit.

Change-Id: Idc3fa7b248e2e25b4b2cd60d5053e2815634c8b7
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

3 files changed, 83 insertions, 29 deletions

diff --git a/src/qml/compiler/qv4isel_moth.cpp b/src/qml/compiler/qv4isel_moth.cpp
index aefb084971..dc6fe317e5 100644
--- a/src/qml/compiler/qv4isel_moth.cpp
+++ b/src/qml/compiler/qv4isel_moth.cpp
@@ -638,7 +638,7 @@ void InstructionSelection::getQObjectProperty(IR::Expr *base, int propertyIndex,
 
 void InstructionSelection::getElement(IR::Expr *base, IR::Expr *index, IR::Expr *target)
 {
-    if (useFastLookups) {
+    if (0 && useFastLookups) {
         Instruction::LoadElementLookup load;
         load.lookup = registerIndexedGetterLookup();
         load.base = getParam(base);
@@ -657,7 +657,7 @@ void InstructionSelection::getElement(IR::Expr *base, IR::Expr *index, IR::Expr
 void InstructionSelection::setElement(IR::Expr *source, IR::Expr *targetBase,
                                       IR::Expr *targetIndex)
 {
-    if (useFastLookups) {
+    if (0 && useFastLookups) {
         Instruction::StoreElementLookup store;
         store.lookup = registerIndexedSetterLookup();
         store.base = getParam(targetBase);
diff --git a/src/qml/jit/qv4isel_masm.cpp b/src/qml/jit/qv4isel_masm.cpp
index ac72d2e8f5..50d40f6f98 100644
--- a/src/qml/jit/qv4isel_masm.cpp
+++ b/src/qml/jit/qv4isel_masm.cpp
@@ -618,7 +618,7 @@ void InstructionSelection<JITAssembler>::setQObjectProperty(IR::Expr *source, IR
 template <typename JITAssembler>
 void InstructionSelection<JITAssembler>::getElement(IR::Expr *base, IR::Expr *index, IR::Expr *target)
 {
-    if (useFastLookups) {
+    if (0 && useFastLookups) {
         uint lookup = registerIndexedGetterLookup();
         generateLookupCall(target, lookup, offsetof(QV4::Lookup, indexedGetter),
                            PointerToValue(base),
@@ -633,7 +633,7 @@ void InstructionSelection<JITAssembler>::getElement(IR::Expr *base, IR::Expr *in
 template <typename JITAssembler>
 void InstructionSelection<JITAssembler>::setElement(IR::Expr *source, IR::Expr *targetBase, IR::Expr *targetIndex)
 {
-    if (useFastLookups) {
+    if (0 && useFastLookups) {
         uint lookup = registerIndexedSetterLookup();
         generateLookupCall(JITAssembler::Void, lookup, offsetof(QV4::Lookup, indexedSetter),
                            PointerToValue(targetBase), PointerToValue(targetIndex),
diff --git a/src/qml/jsruntime/qv4runtime.cpp b/src/qml/jsruntime/qv4runtime.cpp
index 42bf24d7f3..4b440f5335 100644
--- a/src/qml/jsruntime/qv4runtime.cpp
+++ b/src/qml/jsruntime/qv4runtime.cpp
@@ -599,41 +599,53 @@ void Runtime::method_setProperty(ExecutionEngine *engine, const Value &object, i
     o->put(name, value);
 }
 
-ReturnedValue Runtime::method_getElement(ExecutionEngine *engine, const Value &object, const Value &index)
+static Q_NEVER_INLINE ReturnedValue getElementIntFallback(ExecutionEngine *engine, const Value &object, uint idx)
 {
+    Q_ASSERT(idx < UINT_MAX);
     Scope scope(engine);
-    uint idx = index.asArrayIndex();
 
     ScopedObject o(scope, object);
     if (!o) {
-        if (idx < UINT_MAX) {
-            if (const String *str = object.as<String>()) {
-                if (idx >= (uint)str->toQString().length()) {
-                    return Encode::undefined();
-                }
-                const QString s = str->toQString().mid(idx, 1);
-                return scope.engine->newString(s)->asReturnedValue();
+        if (const String *str = object.as<String>()) {
+            if (idx >= (uint)str->toQString().length()) {
+                return Encode::undefined();
             }
+            const QString s = str->toQString().mid(idx, 1);
+            return scope.engine->newString(s)->asReturnedValue();
         }
 
         if (object.isNullOrUndefined()) {
-            QString message = QStringLiteral("Cannot read property '%1' of %2").arg(index.toQStringNoThrow()).arg(object.toQStringNoThrow());
+            QString message = QStringLiteral("Cannot read property '%1' of %2").arg(idx).arg(object.toQStringNoThrow());
             return engine->throwTypeError(message);
         }
 
         o = RuntimeHelpers::convertToObject(scope.engine, object);
-        if (!o) // type error
-            return Encode::undefined();
+        Q_ASSERT(!!o); // can't fail as null/undefined is covered above
+    }
+
+    if (o->arrayData() && !o->arrayData()->attrs) {
+        ScopedValue v(scope, o->arrayData()->get(idx));
+        if (!v->isEmpty())
+            return v->asReturnedValue();
     }
 
-    if (idx < UINT_MAX) {
-        if (o->arrayData() && !o->arrayData()->attrs) {
-            ScopedValue v(scope, o->arrayData()->get(idx));
-            if (!v->isEmpty())
-                return v->asReturnedValue();
+    return o->getIndexed(idx);
+}
+
+static Q_NEVER_INLINE ReturnedValue getElementFallback(ExecutionEngine *engine, const Value &object, const Value &index)
+{
+    Q_ASSERT(index.asArrayIndex() == UINT_MAX);
+    Scope scope(engine);
+
+    ScopedObject o(scope, object);
+    if (!o) {
+        if (object.isNullOrUndefined()) {
+            QString message = QStringLiteral("Cannot read property '%1' of %2").arg(index.toQStringNoThrow()).arg(object.toQStringNoThrow());
+            return engine->throwTypeError(message);
         }
 
-        return o->getIndexed(idx);
+        o = RuntimeHelpers::convertToObject(scope.engine, object);
+        Q_ASSERT(!!o); // can't fail as null/undefined is covered above
     }
 
     ScopedString name(scope, index.toString(engine));
@@ -642,18 +654,39 @@ ReturnedValue Runtime::method_getElement(ExecutionEngine *engine, const Value &o
     return o->get(name);
 }
 
-void Runtime::method_setElement(ExecutionEngine *engine, const Value &object, const Value &index, const Value &value)
+ReturnedValue Runtime::method_getElement(ExecutionEngine *engine, const Value &object, const Value &index)
+{
+    uint idx;
+    if (index.asArrayIndex(idx)) {
+        if (Heap::Base *b = object.heapObject()) {
+            if (b->vtable()->isObject) {
+                Heap::Object *o = static_cast<Heap::Object *>(b);
+                if (o->arrayData && o->arrayData->type == Heap::ArrayData::Simple) {
+                    Heap::SimpleArrayData *s = o->arrayData.cast<Heap::SimpleArrayData>();
+                    if (idx < s->len)
+                        if (!s->data(idx).isEmpty())
+                            return s->data(idx).asReturnedValue();
+                }
+            }
+        }
+        return getElementIntFallback(engine, object, idx);
+    }
+
+    return getElementFallback(engine, object, index);
+}
+
+static Q_NEVER_INLINE void setElementFallback(ExecutionEngine *engine, const Value &object, const Value &index, const Value &value)
 {
     Scope scope(engine);
     ScopedObject o(scope, object.toObject(engine));
-    if (scope.engine->hasException)
+    if (engine->hasException)
         return;
 
-    uint idx = index.asArrayIndex();
-    if (idx < UINT_MAX) {
-        if (o->arrayType() == Heap::ArrayData::Simple) {
-            Heap::SimpleArrayData *s = static_cast<Heap::SimpleArrayData *>(o->arrayData());
-            if (s && idx < s->len && !s->data(idx).isEmpty()) {
+    uint idx;
+    if (index.asArrayIndex(idx)) {
+        if (o->d()->arrayData && o->d()->arrayData->type == Heap::ArrayData::Simple) {
+            Heap::SimpleArrayData *s = o->d()->arrayData.cast<Heap::SimpleArrayData>();
+            if (idx < s->len) {
                 s->data(idx) = value;
                 return;
             }
@@ -666,6 +699,27 @@ void Runtime::method_setElement(ExecutionEngine *engine, const Value &object, co
     o->put(name, value);
 }
 
+void Runtime::method_setElement(ExecutionEngine *engine, const Value &object, const Value &index, const Value &value)
+{
+    uint idx;
+    if (index.asArrayIndex(idx)) {
+        if (Heap::Base *b = object.heapObject()) {
+            if (b->vtable()->isObject) {
+                Heap::Object *o = static_cast<Heap::Object *>(b);
+                if (o->arrayData && o->arrayData->type == Heap::ArrayData::Simple) {
+                    Heap::SimpleArrayData *s = o->arrayData.cast<Heap::SimpleArrayData>();
+                    if (idx < s->len) {
+                        s->data(idx) = value;
+                        return;
+                    }
+                }
+            }
+        }
+    }
+
+    return setElementFallback(engine, object, index, value);
+}
+
 ReturnedValue Runtime::method_foreachIterator(ExecutionEngine *engine, const Value &in)
 {
     Scope scope(engine);