Shrinking CSSParserToken for lower CSS parsing memory usage.

Source/core/css/parser/CSSParserToken.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CSSParserToken_h
 #define CSSParserToken_h
 
 #include "core/CoreExport.h"
 #include "core/css/CSSPrimitiveValue.h"
 #include "core/css/parser/CSSParserValues.h"
@@ skipping 69 matching lines @@
 
     CSSParserToken(HashTokenType, CSSParserString);
 
     // Converts NumberToken to DimensionToken.
     void convertToDimensionWithUnit(CSSParserString);
 
     // Converts NumberToken to PercentageToken.
     void convertToPercentage();
 
     CSSParserTokenType type() const { return static_cast<CSSParserTokenType>(m_type); }
-    CSSParserString value() const { return m_value; }
-    bool valueEqualsIgnoringCase(const char* str) const { return m_value.equalIgnoringCase(str); }
+    CSSParserString value() const
+    {
+        CSSParserString ret;
+        ret.initRaw(m_valueDataCharRaw, m_valueLength, m_valueIs8Bit);
+        return ret;
+    }
+    bool valueEqualsIgnoringCase(const char* str) const { return value().equalIgnoringCase(str); }
 
     UChar delimiter() const;
     NumericSign numericSign() const;
     NumericValueType numericValueType() const;
     double numericValue() const;
     HashTokenType hashTokenType() const { ASSERT(m_type == HashToken); return m_hashTokenType; }
     BlockType blockType() const { return static_cast<BlockType>(m_blockType); }
     CSSPrimitiveValue::UnitType unitType() const { return static_cast<CSSPrimitiveValue::UnitType>(m_unit); }
     UChar32 unicodeRangeStart() const { ASSERT(m_type == UnicodeRangeToken); return m_unicodeRange.start; }
     UChar32 unicodeRangeEnd() const { ASSERT(m_type == UnicodeRangeToken); return m_unicodeRange.end; }
 
     CSSPropertyID parseAsUnresolvedCSSPropertyID() const;
 
     void serialize(StringBuilder&) const;
 
 private:
+    void initValueFromCSSParserString(const CSSParserString& value)
+    {
+        m_valueLength = value.m_length;
+        m_valueIs8Bit = value.m_is8Bit;
+        m_valueDataCharRaw = value.m_data.charactersRaw;
+    }
     unsigned m_type : 6; // CSSParserTokenType
     unsigned m_blockType : 2; // BlockType
     unsigned m_numericValueType : 1; // NumericValueType
     unsigned m_numericSign : 2; // NumericSign
     unsigned m_unit : 7; // CSSPrimitiveValue::UnitType
 
-    CSSParserString m_value; // FIXME: Pack this better?
+    // m_value... is an unpacked CSSParserString so that we can pack it
+    // tightly with the rest of this object for a smaller object size.
+    bool m_valueIs8Bit : 1;
+    unsigned m_valueLength;
+
+    union {
+        const LChar* m_valueDataChar8;

[Timothy Loh, 2015/05/29 03:27:46]

We don't use the explicitly typed versions here.

+        const UChar* m_valueDataChar16;
+        const void* m_valueDataCharRaw;
+    };
 
     union {
         UChar m_delimiter;
         HashTokenType m_hashTokenType;
         double m_numericValue;
 
         struct {
             UChar32 start;
             UChar32 end;
         } m_unicodeRange;
     };
 };
 
 } // namespace blink
 
 namespace WTF {
 template <>
 struct IsTriviallyMoveAssignable<blink::CSSParserToken> {
     static const bool value = true;
 };
 }
 
 #endif // CSSSParserToken_h