Optimize the JS == operator

Implement the isEqualTo vtable method for
String, and use that to compare strings and
objects in the == implementation in one go.

Change-Id: I823ae5c4ed0683105e7a6fc5b414db92d1766fc4
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

7 files changed, 59 insertions, 57 deletions

diff --git a/src/qml/qml/v4/qv4runtime.cpp b/src/qml/qml/v4/qv4runtime.cpp
index 6df48fcea6..ed2c1468ee 100644
--- a/src/qml/qml/v4/qv4runtime.cpp
+++ b/src/qml/qml/v4/qv4runtime.cpp
@@ -685,55 +685,34 @@ void __qmljs_get_activation_property(ExecutionContext *ctx, Value *result, Strin
     *result = ctx->getProperty(name);
 }
 
-uint __qmljs_equal(const Value &x, const Value &y)
-{
-    if (x.type() == y.type()) {
-        switch (x.type()) {
-        case Value::Undefined_Type:
-            return true;
-        case Value::Null_Type:
-            return true;
-        case Value::Boolean_Type:
-            return x.booleanValue() == y.booleanValue();
-            break;
-        case Value::Integer_Type:
-            return x.integerValue() == y.integerValue();
-        case Value::String_Type:
-            return x.stringValue()->isEqualTo(y.stringValue());
-        case Value::Object_Type:
-            if (x.objectValue() == y.objectValue())
-                return true;
-            return x.objectValue()->isEqualTo(y.objectValue());
-        default: // double
-            return x.doubleValue() == y.doubleValue();
-        }
-        // unreachable
-    } else {
-        if (x.isNumber() && y.isNumber())
-            return x.asDouble() == y.asDouble();
-        if (x.isNull() && y.isUndefined()) {
-            return true;
-        } else if (x.isUndefined() && y.isNull()) {
-            return true;
-        } else if (x.isNumber() && y.isString()) {
-            Value ny = Value::fromDouble(__qmljs_to_number(y));
-            return __qmljs_equal(x, ny);
-        } else if (x.isString() && y.isNumber()) {
-            Value nx = Value::fromDouble(__qmljs_to_number(x));
-            return __qmljs_equal(nx, y);
-        } else if (x.isBoolean()) {
-            Value nx = Value::fromDouble((double) x.booleanValue());
-            return __qmljs_equal(nx, y);
-        } else if (y.isBoolean()) {
-            Value ny = Value::fromDouble((double) y.booleanValue());
-            return __qmljs_equal(x, ny);
-        } else if ((x.isNumber() || x.isString()) && y.isObject()) {
-            Value py = __qmljs_to_primitive(y, PREFERREDTYPE_HINT);
-            return __qmljs_equal(x, py);
-        } else if (x.isObject() && (y.isNumber() || y.isString())) {
-            Value px = __qmljs_to_primitive(x, PREFERREDTYPE_HINT);
-            return __qmljs_equal(px, y);
-        }
+uint __qmljs_equal_helper(const Value &x, const Value &y)
+{
+    Q_ASSERT(x.type() != y.type());
+
+    if (x.isNumber() && y.isNumber())
+        return x.asDouble() == y.asDouble();
+    if (x.isNull() && y.isUndefined()) {
+        return true;
+    } else if (x.isUndefined() && y.isNull()) {
+        return true;
+    } else if (x.isNumber() && y.isString()) {
+        double dy = __qmljs_to_number(y);
+        return x.asDouble() == dy;
+    } else if (x.isString() && y.isNumber()) {
+        double dx = __qmljs_to_number(x);
+        return dx == y.asDouble();
+    } else if (x.isBoolean()) {
+        Value nx = Value::fromDouble((double) x.booleanValue());
+        return __qmljs_cmp_eq(nx, y);
+    } else if (y.isBoolean()) {
+        Value ny = Value::fromDouble((double) y.booleanValue());
+        return __qmljs_cmp_eq(x, ny);
+    } else if ((x.isNumber() || x.isString()) && y.isObject()) {
+        Value py = __qmljs_to_primitive(y, PREFERREDTYPE_HINT);
+        return __qmljs_cmp_eq(x, py);
+    } else if (x.isObject() && (y.isNumber() || y.isString())) {
+        Value px = __qmljs_to_primitive(x, PREFERREDTYPE_HINT);
+        return __qmljs_cmp_eq(px, y);
     }
 
     return false;
diff --git a/src/qml/qml/v4/qv4runtime_p.h b/src/qml/qml/v4/qv4runtime_p.h
index 52a8925a47..836aedf298 100644
--- a/src/qml/qml/v4/qv4runtime_p.h
+++ b/src/qml/qml/v4/qv4runtime_p.h
@@ -168,7 +168,7 @@ void __qmljs_numberToString(QString *result, double num, int radix = 10);
 QV4::Value __qmljs_to_object(QV4::ExecutionContext *ctx, const QV4::Value &value);
 QV4::Object *__qmljs_convert_to_object(QV4::ExecutionContext *ctx, const QV4::Value &value);
 
-QV4::Bool __qmljs_equal(const QV4::Value &x, const QV4::Value &y);
+QV4::Bool __qmljs_equal_helper(const Value &x, const Value &y);
 Q_QML_EXPORT QV4::Bool __qmljs_strict_equal(const QV4::Value &x, const QV4::Value &y);
 
 // unary operators
@@ -667,10 +667,13 @@ inline QV4::Bool __qmljs_cmp_eq(const QV4::Value &left, const QV4::Value &right)
         // NaN != NaN
         return (left.tag & QV4::Value::NotDouble_Mask) != QV4::Value::NaN_Mask;
 
-    if (left.isString() && right.isString())
-        return left.stringValue()->isEqualTo(right.stringValue());
+    if (left.type() == right.type()) {
+        if (left.isManaged())
+            return left.managed()->isEqualTo(right.managed());
+        return false;
+    }
 
-    return __qmljs_equal(left, right);
+    return __qmljs_equal_helper(left, right);
 }
 
 inline QV4::Bool __qmljs_cmp_ne(const QV4::Value &left, const QV4::Value &right)
diff --git a/src/qml/qml/v4/qv4string.cpp b/src/qml/qml/v4/qv4string.cpp
index bfdee2d2cc..8b78c40129 100644
--- a/src/qml/qml/v4/qv4string.cpp
+++ b/src/qml/qml/v4/qv4string.cpp
@@ -119,7 +119,7 @@ const ManagedVTable String::static_vtbl =
     deleteIndexedProperty,
     0 /*getLookup*/,
     0 /*setLookup*/,
-    Managed::isEqualTo,
+    isEqualTo,
     0 /*advanceIterator*/,
     "String",
 };
@@ -209,6 +209,23 @@ bool String::deleteIndexedProperty(Managed *m, uint index)
     return false;
 }
 
+bool String::isEqualTo(Managed *t, Managed *o)
+{
+    if (t == o)
+        return true;
+    String *that = static_cast<String *>(t);
+    String *other = static_cast<String *>(o);
+    if (that->hashValue() != other->hashValue())
+        return false;
+    if (that->identifier && that->identifier == other->identifier)
+        return true;
+    if (that->subtype >= StringType_UInt && that->subtype == other->subtype)
+        return true;
+
+    return that->toQString() == other->toQString();
+}
+
+
 String::String(ExecutionEngine *engine, const QString &text)
     : Managed(engine ? engine->emptyClass : 0), _text(text), identifier(0), stringHash(UINT_MAX)
 {
diff --git a/src/qml/qml/v4/qv4string_p.h b/src/qml/qml/v4/qv4string_p.h
index 629fa506b7..31e5c2a5f7 100644
--- a/src/qml/qml/v4/qv4string_p.h
+++ b/src/qml/qml/v4/qv4string_p.h
@@ -123,6 +123,7 @@ struct Q_QML_EXPORT String : public Managed {
     mutable Identifier *identifier;
     mutable uint stringHash;
 
+
 protected:
     static void destroy(Managed *);
     static Value get(Managed *m, String *name, bool *hasProperty);
@@ -133,6 +134,7 @@ protected:
     static PropertyAttributes queryIndexed(const Managed *m, uint index);
     static bool deleteProperty(Managed *, String *);
     static bool deleteIndexedProperty(Managed *m, uint index);
+    static bool isEqualTo(Managed *that, Managed *o);
 
     static const ManagedVTable static_vtbl;
 };
diff --git a/src/qml/qml/v4/qv4value_def_p.h b/src/qml/qml/v4/qv4value_def_p.h
index 89f6647e22..a44af16b6a 100644
--- a/src/qml/qml/v4/qv4value_def_p.h
+++ b/src/qml/qml/v4/qv4value_def_p.h
@@ -79,7 +79,7 @@ struct Q_QML_EXPORT Value
         NotDouble_Mask = 0x7ffc0000,
         Type_Mask = 0xffff8000,
         Immediate_Mask = NotDouble_Mask | 0x00008000,
-        Special_Mask = Immediate_Mask | 0x20000,
+        IsManaged_Mask = Type_Mask & ~0x10000,
         Tag_Shift = 32
     };
     enum ValueType {
@@ -127,6 +127,7 @@ struct Q_QML_EXPORT Value
     inline bool isString() const { return tag == String_Type; }
     inline bool isObject() const { return tag == Object_Type; }
 #endif
+    inline bool isManaged() const { return (tag & IsManaged_Mask) == Object_Type; }
     inline bool isConvertibleToInt() const { return (tag & ConvertibleToInt) == ConvertibleToInt; }
     inline bool isInt32() {
         if (tag == _Integer_Type)
diff --git a/src/qml/qml/v4/qv4value_p.h b/src/qml/qml/v4/qv4value_p.h
index 6d3f0e6edc..2a783ed34b 100644
--- a/src/qml/qml/v4/qv4value_p.h
+++ b/src/qml/qml/v4/qv4value_p.h
@@ -276,7 +276,7 @@ inline String *Value::asString() const
 
 inline Managed *Value::asManaged() const
 {
-    if (isObject() || isString())
+    if (isManaged())
         return managed();
     return 0;
 }
diff --git a/src/qml/qml/v8/qjsvalue.cpp b/src/qml/qml/v8/qjsvalue.cpp
index 2fab183bd0..569dd964fd 100644
--- a/src/qml/qml/v8/qjsvalue.cpp
+++ b/src/qml/qml/v8/qjsvalue.cpp
@@ -747,7 +747,7 @@ QJSValue& QJSValue::operator=(const QJSValue& other)
 */
 bool QJSValue::equals(const QJSValue& other) const
 {
-    return __qmljs_equal(d->value, other.d->value);
+    return __qmljs_cmp_eq(d->value, other.d->value);
 }
 
 /*!