CSSValue Immediates: Change RefPtr<CSSValue> to store tagged pointers

Source/core/css/CSSValue.cpp

Index: Source/core/css/CSSValue.cpp
diff --git a/Source/core/css/CSSValue.cpp b/Source/core/css/CSSValue.cpp
index d8a94be96cb0712b2e146f95e0c2bab34ab8f683..b183fa0062c0d0cc172fc22badf88bca72ff7330 100644
--- a/Source/core/css/CSSValue.cpp
+++ b/Source/core/css/CSSValue.cpp
@@ -65,11 +65,14 @@ static_assert(sizeof(CSSValue) <= sizeof(SameSizeAsCSSValue), "CSSValue should s
 
 bool CSSValue::isImplicitInitialValue() const
 {
-    return m_classType == InitialClass && toCSSInitialValue(this)->isImplicit();
+    return !isTaggedPtr() && classType() == InitialClass && toCSSInitialValue(this)->isImplicit();
 }
 
 bool CSSValue::hasFailedOrCanceledSubresources() const
 {
+    if (isTaggedPtr())
+        return false;
+
     if (isValueList())
         return toCSSValueList(this)->hasFailedOrCanceledSubresources();
     if (classType() == FontFaceSrcClass)
@@ -92,6 +95,12 @@ inline static bool compareCSSValues(const CSSValue& first, const CSSValue& secon
 
 bool CSSValue::equals(const CSSValue& other) const
 {
+    if (isTaggedPtr() && other.isTaggedPtr())
+        return this == &other;
+
+    if (isTaggedPtr() || other.isTaggedPtr())
+        return compareCSSValues<CSSPrimitiveValue>(*this, other);
+
     if (m_classType == other.m_classType) {
         switch (m_classType) {
         case BorderImageSliceClass:
@@ -160,6 +169,9 @@ bool CSSValue::equals(const CSSValue& other) const
 
 String CSSValue::cssText() const
 {
+    if (isTaggedPtr())
+        return toCSSPrimitiveValue(this)->customCSSText();
+
     switch (classType()) {
     case BorderImageSliceClass:
         return toCSSBorderImageSliceValue(this)->customCSSText();
@@ -224,6 +236,9 @@ String CSSValue::cssText() const
 
 void CSSValue::destroy()
 {
+    if (isTaggedPtr())
+        return;
+
     switch (classType()) {
     case BorderImageSliceClass:
         delete toCSSBorderImageSliceValue(this);
@@ -315,6 +330,9 @@ void CSSValue::destroy()
 
 void CSSValue::finalizeGarbageCollectedObject()
 {
+    if (isTaggedPtr())
+        return;
+
     switch (classType()) {
     case BorderImageSliceClass:
         toCSSBorderImageSliceValue(this)->~CSSBorderImageSliceValue();
@@ -406,6 +424,9 @@ void CSSValue::finalizeGarbageCollectedObject()
 
 DEFINE_TRACE(CSSValue)
 {
+    if (isTaggedPtr())
+        return;
+
     switch (classType()) {
     case BorderImageSliceClass:
         toCSSBorderImageSliceValue(this)->traceAfterDispatch(visitor);
@@ -495,4 +516,4 @@ DEFINE_TRACE(CSSValue)
     ASSERT_NOT_REACHED();
 }
 
-}
+} // namespace blink