CSSValue Immediates: Make CSSPrimitiveValue store a tagged pointer

Source/core/css/CSSValue.h

Index: Source/core/css/CSSValue.h
diff --git a/Source/core/css/CSSValue.h b/Source/core/css/CSSValue.h
index ac7df50a004ea2b8914057e1cfcd39f5a06dba76..b2f0a4ef382f1e1c301ec9e2f4a9503e59ef061c 100644
--- a/Source/core/css/CSSValue.h
+++ b/Source/core/css/CSSValue.h
@@ -41,6 +41,7 @@ public:
         : m_data(const_cast<CSSValueObject*>(&cssValueObject))
     {
         ASSERT(m_data);
+        ASSERT(isObject());
         ref();
     }
 
@@ -50,6 +51,7 @@ public:
         : m_data(cssValueObject.leakRef())
     {
         static_assert(WTF::IsSubclass<T, CSSValueObject>::value, "Parameter must be a container for CSSValueObject");
+        ASSERT(isObject());
         ASSERT(m_data);
     }
 
@@ -58,6 +60,7 @@ public:
         : m_data(cssValueObject.release().leakRef())
     {
         static_assert(WTF::IsSubclass<T, CSSValueObject>::value, "Parameter must be a container for CSSValueObject");
+        ASSERT(isObject());
         ASSERT(m_data);
     }
 #endif
@@ -90,12 +93,20 @@ public:
 
     bool operator==(const CSSValue& other) const
     {
+        if (m_data == other.m_data)
+            return true;
+        if (!isObject() || !other.isObject())
+            return false;
         return m_data->equals(*other.m_data);
     }
 
     // TODO: Remove this and update callsites to use operator== instead.
     bool equals(const CSSValue& other) const
     {
+        if (m_data == other.m_data)
+            return true;
+        if (!isObject() || !other.isObject())
+            return false;
         return m_data->equals(*other.m_data);
     }
 
@@ -105,46 +116,53 @@ public:
     }
 
     // Methods that proxy to CSSValueObject.
-    String cssText() const { return m_data->cssText(); }
-    bool hasFailedOrCanceledSubresources() const { return m_data->hasFailedOrCanceledSubresources(); };
-    bool isPrimitiveValue() const { return m_data->isPrimitiveValue(); }
-    bool isValueList() const { return m_data->isValueList(); }
-    bool isBaseValueList() const { return m_data->isBaseValueList(); }
-    bool isBorderImageSliceValue() const { return m_data->isBorderImageSliceValue(); }
-    bool isCanvasValue() const { return m_data->isCanvasValue(); }
-    bool isCursorImageValue() const { return m_data->isCursorImageValue(); }
-    bool isCrossfadeValue() const { return m_data->isCrossfadeValue(); }
-    bool isFontFeatureValue() const { return m_data->isFontFeatureValue(); }
-    bool isFontFaceSrcValue() const { return m_data->isFontFaceSrcValue(); }
-    bool isFunctionValue() const { return m_data->isFunctionValue(); }
-    bool isImageGeneratorValue() const { return m_data->isImageGeneratorValue(); }
-    bool isGradientValue() const { return m_data->isGradientValue(); }
-    bool isImageSetValue() const { return m_data->isImageSetValue(); }
-    bool isImageValue() const { return m_data->isImageValue(); }
-    bool isImplicitInitialValue() const { return m_data->isImplicitInitialValue(); };
-    bool isInheritedValue() const { return m_data->isInheritedValue(); };
-    bool isInitialValue() const { return m_data->isInitialValue(); };
-    bool isUnsetValue() const { return m_data->isUnsetValue(); };
-    bool isCSSWideKeyword() const { return m_data->isCSSWideKeyword(); };
-    bool isLinearGradientValue() const { return m_data->isLinearGradientValue(); };
-    bool isPathValue() const { return m_data->isPathValue(); };
-    bool isRadialGradientValue() const { return m_data->isRadialGradientValue(); };
-    bool isReflectValue() const { return m_data->isReflectValue(); };
-    bool isShadowValue() const { return m_data->isShadowValue(); };
-    bool isCubicBezierTimingFunctionValue() const { return m_data->isCubicBezierTimingFunctionValue(); };
-    bool isStepsTimingFunctionValue() const { return m_data->isStepsTimingFunctionValue(); };
-    bool isLineBoxContainValue() const { return m_data->isLineBoxContainValue(); };
-    bool isCalcValue() const { return m_data->isCalcValue(); };
-    bool isGridTemplateAreasValue() const { return m_data->isGridTemplateAreasValue(); };
-    bool isSVGDocumentValue() const { return m_data->isSVGDocumentValue(); };
-    bool isContentDistributionValue() const { return m_data->isContentDistributionValue(); };
-    bool isUnicodeRangeValue() const { return m_data->isUnicodeRangeValue(); };
-    bool isGridLineNamesValue() const { return m_data->isGridLineNamesValue(); };
+    String cssText() const
+    {
+        if (isObject())
+            return m_data->cssText();
+        return CSSPrimitiveValue(reinterpret_cast<CSSPrimitiveValue::CSSLargePrimitiveValue*>(m_data.get())).cssText();
+    }
+
+    bool hasFailedOrCanceledSubresources() const { return isObject() ? m_data->hasFailedOrCanceledSubresources() : false; };
+    bool isPrimitiveValue() const { return isObject() ? m_data->isPrimitiveValue() : true; }
+    bool isValueList() const { return isObject() ? m_data->isValueList() : false; }
+    bool isBaseValueList() const { return isObject() ? m_data->isBaseValueList() : false; }
+    bool isBorderImageSliceValue() const { return isObject() ? m_data->isBorderImageSliceValue() : false; }
+    bool isCanvasValue() const { return isObject() ? m_data->isCanvasValue() : false; }
+    bool isCursorImageValue() const { return isObject() ? m_data->isCursorImageValue() : false; }
+    bool isCrossfadeValue() const { return isObject() ? m_data->isCrossfadeValue() : false; }
+    bool isFontFeatureValue() const { return isObject() ? m_data->isFontFeatureValue(): false; }
+    bool isFontFaceSrcValue() const { return isObject() ? m_data->isFontFaceSrcValue(): false; }
+    bool isFunctionValue() const { return isObject() ? m_data->isFunctionValue(): false; }
+    bool isImageGeneratorValue() const { return isObject() ? m_data->isImageGeneratorValue(): false; }
+    bool isGradientValue() const { return isObject() ? m_data->isGradientValue(): false; }
+    bool isImageSetValue() const { return isObject() ? m_data->isImageSetValue(): false; }
+    bool isImageValue() const { return isObject() ? m_data->isImageValue(): false; }
+    bool isImplicitInitialValue() const { return isObject() ? m_data->isImplicitInitialValue(): false; }
+    bool isInheritedValue() const { return isObject() ? m_data->isInheritedValue(): false; }
+    bool isInitialValue() const { return isObject() ? m_data->isInitialValue(): false; }
+    bool isUnsetValue() const { return isObject() ? m_data->isUnsetValue(): false; }
+    bool isCSSWideKeyword() const { return isObject() ? m_data->isCSSWideKeyword(): false; }
+    bool isLinearGradientValue() const { return isObject() ? m_data->isLinearGradientValue(): false; }
+    bool isPathValue() const { return isObject() ? m_data->isPathValue(): false; }
+    bool isRadialGradientValue() const { return isObject() ? m_data->isRadialGradientValue(): false; }
+    bool isReflectValue() const { return isObject() ? m_data->isReflectValue(): false; }
+    bool isShadowValue() const { return isObject() ? m_data->isShadowValue(): false; }
+    bool isCubicBezierTimingFunctionValue() const { return isObject() ? m_data->isCubicBezierTimingFunctionValue(): false; }
+    bool isStepsTimingFunctionValue() const { return isObject() ? m_data->isStepsTimingFunctionValue(): false; }
+    bool isLineBoxContainValue() const { return isObject() ? m_data->isLineBoxContainValue(): false; }
+    bool isCalcValue() const { return isObject() ? m_data->isCalcValue(): false; }
+    bool isGridTemplateAreasValue() const { return isObject() ? m_data->isGridTemplateAreasValue(): false; }
+    bool isSVGDocumentValue() const { return isObject() ? m_data->isSVGDocumentValue(): false; }
+    bool isContentDistributionValue() const { return isObject() ? m_data->isContentDistributionValue(): false; }
+    bool isUnicodeRangeValue() const { return isObject() ? m_data->isUnicodeRangeValue(): false; }
+    bool isGridLineNamesValue() const { return isObject() ? m_data->isGridLineNamesValue(): false; }
 
     DEFINE_INLINE_TRACE()
     {
         ASSERT(m_data);
-        visitor->trace(m_data);
+        if (isObject())
+            visitor->trace(m_data);
     }
 
     // Only for use by the toFooCSSValue() macros. Don't use this.
@@ -162,7 +180,7 @@ private:
     void ref() const
     {
 #if !ENABLE(OILPAN)
-        if (m_data)
+        if (m_data && isObject())
             m_data->ref();
 #endif
     }
@@ -170,11 +188,16 @@ private:
     void deref() const
     {
 #if !ENABLE(OILPAN)
-        if (m_data)
+        if (m_data && isObject())
             m_data->deref();
 #endif
     }
 
+    bool isObject() const
+    {
+        return !(*reinterpret_cast<const uintptr_t*>(&m_data) & 1);
+    }
+
     RawPtrWillBeMember<CSSValueObject> m_data;
 };
 
@@ -256,6 +279,10 @@ public:
 
     bool operator==(const NullableCSSValue& rhs) const
     {
+        if (m_data == rhs.m_data)
+            return true;
+        if (!isObject() || (rhs && !rhs.isObject()))
+            return false;
         return m_data ? rhs.m_data && m_data->equals(*rhs.m_data) : !bool(rhs.m_data);
     }
 
@@ -296,7 +323,8 @@ public:
 
     DEFINE_INLINE_TRACE()
     {
-        visitor->trace(m_data);
+        if (isObject())
+            visitor->trace(m_data);
     }
 
     // Only for use by the toFooCSSValue() macros. Don't use this.
@@ -311,7 +339,7 @@ private:
     void ref() const
     {
 #if !ENABLE(OILPAN)
-        if (m_data)
+        if (m_data && isObject())
             m_data->ref();
 #endif
     }
@@ -319,11 +347,16 @@ private:
     void deref() const
     {
 #if !ENABLE(OILPAN)
-        if (m_data)
+        if (m_data && isObject())
             m_data->deref();
 #endif
     }
 
+    bool isObject() const
+    {
+        return !(*reinterpret_cast<const uintptr_t*>(&m_data) & 1);
+    }
+
     RawPtrWillBeMember<CSSValueObject> m_data;
 };