Optimise string additions

Small optimisation for string additions, also add one more check
for exceptions in the code where required.

Change-Id: I6c14bc88ea5d03f7eeed0e0168c5195f9f823693
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

6 files changed, 98 insertions, 33 deletions

diff --git a/src/qml/jsruntime/qv4jsonobject.cpp b/src/qml/jsruntime/qv4jsonobject.cpp
index 8d693f7705..c4d1ebc545 100644
--- a/src/qml/jsruntime/qv4jsonobject.cpp
+++ b/src/qml/jsruntime/qv4jsonobject.cpp
@@ -926,7 +926,7 @@ ReturnedValue JsonObject::method_stringify(SimpleCallContext *ctx)
             for (uint i = 0; i < arrayLen; ++i) {
                 v = o->getIndexed(i);
                 if (v->asNumberObject() || v->asStringObject() || v->isNumber())
-                    v = __qmljs_to_string(v, ctx);
+                    v = __qmljs_to_string(ctx, v);
                 if (v->isString()) {
                     String *s = v->stringValue();
                     if (!stringify.propertyList.contains(s))
diff --git a/src/qml/jsruntime/qv4numberobject.cpp b/src/qml/jsruntime/qv4numberobject.cpp
index 098afa8161..2000297b84 100644
--- a/src/qml/jsruntime/qv4numberobject.cpp
+++ b/src/qml/jsruntime/qv4numberobject.cpp
@@ -250,7 +250,7 @@ ReturnedValue NumberPrototype::method_toPrecision(SimpleCallContext *ctx)
         return Encode::undefined();
 
     if (!ctx->callData->argc || ctx->callData->args[0].isUndefined())
-        return __qmljs_to_string(v, ctx);
+        return __qmljs_to_string(ctx, v);
 
     double precision = ctx->callData->args[0].toInt32();
     if (precision < 1 || precision > 21) {
diff --git a/src/qml/jsruntime/qv4regexpobject.cpp b/src/qml/jsruntime/qv4regexpobject.cpp
index 7322a58412..c2d04cc7ed 100644
--- a/src/qml/jsruntime/qv4regexpobject.cpp
+++ b/src/qml/jsruntime/qv4regexpobject.cpp
@@ -266,10 +266,10 @@ ReturnedValue RegExpCtor::construct(Managed *m, CallData *callData)
     bool ignoreCase = false;
     bool multiLine = false;
     if (!f->isUndefined()) {
-        f = __qmljs_to_string(f, ctx);
-        QString str = f->stringValue()->toQString();
+        f = __qmljs_to_string(ctx, f);
         if (scope.hasException())
             return Encode::undefined();
+        QString str = f->stringValue()->toQString();
         for (int i = 0; i < str.length(); ++i) {
             if (str.at(i) == QLatin1Char('g') && !global) {
                 global = true;
@@ -322,7 +322,9 @@ ReturnedValue RegExpPrototype::method_exec(SimpleCallContext *ctx)
         return ctx->throwTypeError();
 
     ScopedValue arg(scope, ctx->argument(0));
-    arg = __qmljs_to_string(arg, ctx);
+    arg = __qmljs_to_string(ctx, arg);
+    if (scope.hasException())
+        return Encode::undefined();
     QString s = arg->stringValue()->toQString();
 
     int offset = r->global ? r->lastIndexProperty(ctx)->value.toInt32() : 0;
diff --git a/src/qml/jsruntime/qv4runtime.cpp b/src/qml/jsruntime/qv4runtime.cpp
index 4e40779c16..d8ebe635bd 100644
--- a/src/qml/jsruntime/qv4runtime.cpp
+++ b/src/qml/jsruntime/qv4runtime.cpp
@@ -297,30 +297,6 @@ ReturnedValue __qmljs_delete_name(ExecutionContext *ctx, const StringRef name)
     return Encode(ctx->deleteProperty(name));
 }
 
-QV4::ReturnedValue __qmljs_add_helper(ExecutionContext *ctx, const ValueRef left, const ValueRef right)
-{
-    Scope scope(ctx);
-
-    ScopedValue pleft(scope, __qmljs_to_primitive(left, PREFERREDTYPE_HINT));
-    ScopedValue pright(scope, __qmljs_to_primitive(right, PREFERREDTYPE_HINT));
-    if (pleft->isString() || pright->isString()) {
-        if (!pleft->isString())
-            pleft = __qmljs_to_string(pleft, ctx);
-        if (!pright->isString())
-            pright = __qmljs_to_string(pright, ctx);
-        if (scope.engine->hasException)
-            return Encode::undefined();
-        if (!pleft->stringValue()->length())
-            return right->asReturnedValue();
-        if (!pright->stringValue()->length())
-            return pleft->asReturnedValue();
-        return (new (ctx->engine->memoryManager) String(ctx->engine, pleft->stringValue(), pright->stringValue()))->asReturnedValue();
-    }
-    double x = __qmljs_to_number(pleft);
-    double y = __qmljs_to_number(pright);
-    return Encode(x + y);
-}
-
 QV4::ReturnedValue __qmljs_instanceof(ExecutionContext *ctx, const ValueRef left, const ValueRef right)
 {
     Object *o = right->asObject();
@@ -469,6 +445,90 @@ Returned<String> *__qmljs_convert_to_string(ExecutionContext *ctx, const ValueRe
     } // switch
 }
 
+// This is slightly different from the method above, as
+// the + operator requires a slightly different conversion
+static Returned<String> *convert_to_string_add(ExecutionContext *ctx, const ValueRef value)
+{
+    switch (value->type()) {
+    case Value::Empty_Type:
+        Q_ASSERT(!"empty Value encountered");
+    case Value::Undefined_Type:
+        return ctx->engine->id_undefined.ret();
+    case Value::Null_Type:
+        return ctx->engine->id_null.ret();
+    case Value::Boolean_Type:
+        if (value->booleanValue())
+            return ctx->engine->id_true.ret();
+        else
+            return ctx->engine->id_false.ret();
+    case Value::Managed_Type:
+        if (value->isString())
+            return value->stringValue()->asReturned<String>();
+        {
+            Scope scope(ctx);
+            ScopedValue prim(scope, __qmljs_to_primitive(value, PREFERREDTYPE_HINT));
+            return __qmljs_convert_to_string(ctx, prim);
+        }
+    case Value::Integer_Type:
+        return __qmljs_string_from_number(ctx, value->int_32);
+    default: // double
+        return __qmljs_string_from_number(ctx, value->doubleValue());
+    } // switch
+}
+
+QV4::ReturnedValue __qmljs_add_helper(ExecutionContext *ctx, const ValueRef left, const ValueRef right)
+{
+    Scope scope(ctx);
+
+    ScopedValue pleft(scope, __qmljs_to_primitive(left, PREFERREDTYPE_HINT));
+    ScopedValue pright(scope, __qmljs_to_primitive(right, PREFERREDTYPE_HINT));
+    if (pleft->isString() || pright->isString()) {
+        if (!pleft->isString())
+            pleft = convert_to_string_add(ctx, pleft);
+        if (!pright->isString())
+            pright = convert_to_string_add(ctx, pright);
+        if (scope.engine->hasException)
+            return Encode::undefined();
+        if (!pleft->stringValue()->length())
+            return pright->asReturnedValue();
+        if (!pright->stringValue()->length())
+            return pleft->asReturnedValue();
+        return (new (ctx->engine->memoryManager) String(ctx->engine, pleft->stringValue(), pright->stringValue()))->asReturnedValue();
+    }
+    double x = __qmljs_to_number(pleft);
+    double y = __qmljs_to_number(pright);
+    return Encode(x + y);
+}
+
+QV4::ReturnedValue __qmljs_add_string(QV4::ExecutionContext *ctx, const QV4::ValueRef left, const QV4::ValueRef right)
+{
+    Q_ASSERT(left->isString() || right->isString());
+
+    if (left->isString() && right->isString()) {
+        if (!left->stringValue()->length())
+            return right->asReturnedValue();
+        if (!right->stringValue()->length())
+            return left->asReturnedValue();
+        return (new (ctx->engine->memoryManager) String(ctx->engine, left->stringValue(), right->stringValue()))->asReturnedValue();
+    }
+
+    Scope scope(ctx);
+    ScopedValue pleft(scope, *left);
+    ScopedValue pright(scope, *right);
+
+    if (!pleft->isString())
+        pleft = convert_to_string_add(ctx, left);
+    if (!pright->isString())
+        pright = convert_to_string_add(ctx, right);
+    if (scope.engine->hasException)
+        return Encode::undefined();
+    if (!pleft->stringValue()->length())
+        return pright->asReturnedValue();
+    if (!pright->stringValue()->length())
+        return pleft->asReturnedValue();
+    return (new (ctx->engine->memoryManager) String(ctx->engine, pleft->stringValue(), pright->stringValue()))->asReturnedValue();
+}
+
 void __qmljs_set_property(ExecutionContext *ctx, const ValueRef object, const StringRef name, const ValueRef value)
 {
     Scope scope(ctx);
@@ -1110,7 +1170,7 @@ QV4::ReturnedValue __qmljs_decrement(const QV4::ValueRef value)
     }
 }
 
-QV4::ReturnedValue __qmljs_to_string(const QV4::ValueRef value, QV4::ExecutionContext *ctx)
+QV4::ReturnedValue __qmljs_to_string(QV4::ExecutionContext *ctx, const QV4::ValueRef value)
 {
     if (value->isString())
         return value.asReturnedValue();
diff --git a/src/qml/jsruntime/qv4runtime_p.h b/src/qml/jsruntime/qv4runtime_p.h
index 1bd6805837..4f6f3a33d4 100644
--- a/src/qml/jsruntime/qv4runtime_p.h
+++ b/src/qml/jsruntime/qv4runtime_p.h
@@ -184,7 +184,7 @@ QV4::ReturnedValue __qmljs_foreach_next_property_name(const ValueRef foreach_ite
 QV4::ReturnedValue __qmljs_to_primitive(const ValueRef value, int typeHint);
 Q_QML_EXPORT QV4::Bool __qmljs_to_boolean(const QV4::ValueRef value);
 double __qmljs_to_number(const QV4::ValueRef value);
-QV4::ReturnedValue __qmljs_to_string(const ValueRef value, QV4::ExecutionContext *ctx);
+QV4::ReturnedValue __qmljs_to_string(QV4::ExecutionContext *ctx, const ValueRef value);
 Q_QML_EXPORT Returned<String> *__qmljs_convert_to_string(QV4::ExecutionContext *ctx, const ValueRef value);
 void __qmljs_numberToString(QString *result, double num, int radix = 10);
 ReturnedValue __qmljs_to_object(QV4::ExecutionContext *ctx, const ValueRef value);
@@ -221,6 +221,7 @@ typedef QV4::ReturnedValue (*BinOpContext)(QV4::ExecutionContext *ctx, const QV4
 QV4::ReturnedValue __qmljs_instanceof(QV4::ExecutionContext *ctx, const QV4::ValueRef left, const QV4::ValueRef right);
 QV4::ReturnedValue __qmljs_in(QV4::ExecutionContext *ctx, const QV4::ValueRef left, const QV4::ValueRef right);
 QV4::ReturnedValue __qmljs_add(ExecutionContext *ctx, const QV4::ValueRef left, const QV4::ValueRef right);
+QV4::ReturnedValue __qmljs_add_string(QV4::ExecutionContext *ctx, const QV4::ValueRef left, const QV4::ValueRef right);
 QV4::ReturnedValue __qmljs_bit_or(const QV4::ValueRef left, const QV4::ValueRef right);
 QV4::ReturnedValue __qmljs_bit_xor(const QV4::ValueRef left, const QV4::ValueRef right);
 QV4::ReturnedValue __qmljs_bit_and(const QV4::ValueRef left, const QV4::ValueRef right);
diff --git a/src/qml/jsruntime/qv4stringobject.cpp b/src/qml/jsruntime/qv4stringobject.cpp
index 33dd403e9b..7ba7a38cc0 100644
--- a/src/qml/jsruntime/qv4stringobject.cpp
+++ b/src/qml/jsruntime/qv4stringobject.cpp
@@ -301,8 +301,10 @@ ReturnedValue StringPrototype::method_concat(SimpleCallContext *context)
 
     ScopedValue v(scope);
     for (int i = 0; i < context->callData->argc; ++i) {
-        v = __qmljs_to_string(ValueRef(&context->callData->args[i]), context);
-        assert(v->isString());
+        v = __qmljs_to_string(context, ValueRef(&context->callData->args[i]));
+        if (scope.hasException())
+            return Encode::undefined();
+        Q_ASSERT(v->isString());
         value += v->stringValue()->toQString();
     }