JS: Encode result of Math.min and Math.max as int when possible

So now Math.max(array1.length, array2.length) won't return a double
anymore.

This improves the score in the crypto benchmark by ~10%

Change-Id: I8453a671d28d7f2a39ba74b18b3155f031d9b12f
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

4 files changed, 27 insertions, 7 deletions

diff --git a/src/qml/jsapi/qjsvalue_p.h b/src/qml/jsapi/qjsvalue_p.h
index 62e09f72be..bcf0a9d12d 100644
--- a/src/qml/jsapi/qjsvalue_p.h
+++ b/src/qml/jsapi/qjsvalue_p.h
@@ -62,7 +62,7 @@
 
 QT_BEGIN_NAMESPACE
 
-class QJSValuePrivate
+class Q_AUTOTEST_EXPORT QJSValuePrivate
 {
 public:
     static inline QV4::Value *getValue(const QJSValue *jsval)
diff --git a/src/qml/jsruntime/qv4mathobject.cpp b/src/qml/jsruntime/qv4mathobject.cpp
index 652f6c603e..e176235786 100644
--- a/src/qml/jsruntime/qv4mathobject.cpp
+++ b/src/qml/jsruntime/qv4mathobject.cpp
@@ -399,7 +399,7 @@ ReturnedValue MathObject::method_max(const FunctionObject *, const Value *, cons
         if (x > mx || std::isnan(x))
             mx = x;
     }
-    RETURN_RESULT(Encode(mx));
+    RETURN_RESULT(Encode::smallestNumber(mx));
 }
 
 ReturnedValue MathObject::method_min(const FunctionObject *, const Value *, const Value *argv, int argc)
@@ -412,7 +412,7 @@ ReturnedValue MathObject::method_min(const FunctionObject *, const Value *, cons
             mx = x;
         }
     }
-    RETURN_RESULT(Encode(mx));
+    RETURN_RESULT(Encode::smallestNumber(mx));
 }
 
 ReturnedValue MathObject::method_pow(const FunctionObject *, const Value *, const Value *argv, int argc)
diff --git a/src/qml/jsruntime/qv4value_p.h b/src/qml/jsruntime/qv4value_p.h
index 7c9ca9c0bf..6a6df3eb6d 100644
--- a/src/qml/jsruntime/qv4value_p.h
+++ b/src/qml/jsruntime/qv4value_p.h
@@ -334,14 +334,17 @@ public:
             return true;
         if (isDouble()) {
             double d = doubleValue();
-            int i = (int)d;
-            if (i == d && !(d == 0 && std::signbit(d))) {
-                setInt_32(i);
+            if (isInt32(d)) {
+                setInt_32(int(d));
                 return true;
             }
         }
         return false;
     }
+    QML_NEARLY_ALWAYS_INLINE static bool isInt32(double d) {
+        int i = int(d);
+        return (i == d && !(d == 0 && std::signbit(d)));
+    }
     double asDouble() const {
         if (tag() == quint32(ValueTypeInternal::Integer))
             return int_32();
@@ -733,7 +736,7 @@ struct Encode {
     }
 
     static ReturnedValue smallestNumber(double d) {
-        if (static_cast<int>(d) == d && !(d == 0. && std::signbit(d)))
+        if (Value::isInt32(d))
             return Encode(static_cast<int>(d));
         else
             return Encode(d);
diff --git a/tests/auto/qml/qjsengine/tst_qjsengine.cpp b/tests/auto/qml/qjsengine/tst_qjsengine.cpp
index c20937f9a1..935fd53a42 100644
--- a/tests/auto/qml/qjsengine/tst_qjsengine.cpp
+++ b/tests/auto/qml/qjsengine/tst_qjsengine.cpp
@@ -39,6 +39,7 @@
 #include <qqmlcomponent.h>
 #include <stdlib.h>
 #include <private/qv4alloca_p.h>
+#include <private/qjsvalue_p.h>
 
 #ifdef Q_CC_MSVC
 #define NO_INLINE __declspec(noinline)
@@ -220,6 +221,7 @@ private slots:
     void multilineStrings();
 
     void throwError();
+    void mathMinMax();
 
 public:
     Q_INVOKABLE QJSValue throwingCppMethod();
@@ -4326,6 +4328,21 @@ QJSValue tst_QJSEngine::throwingCppMethod()
     return QJSValue(47);
 }
 
+void tst_QJSEngine::mathMinMax()
+{
+    QJSEngine engine;
+
+    QJSValue result = engine.evaluate("var a = .5; Math.min(1, 2, 3.5 + a, '5')");
+    QCOMPARE(result.toNumber(), 1.0);
+    QVERIFY(QJSValuePrivate::getValue(&result) != nullptr);
+    QVERIFY(QJSValuePrivate::getValue(&result)->isInteger());
+
+    result = engine.evaluate("var a = .5; Math.max('0', 1, 2, 3.5 + a)");
+    QCOMPARE(result.toNumber(), 4.0);
+    QVERIFY(QJSValuePrivate::getValue(&result) != nullptr);
+    QVERIFY(QJSValuePrivate::getValue(&result)->isInteger());
+}
+
 QTEST_MAIN(tst_QJSEngine)
 
 #include "tst_qjsengine.moc"