NOT FOR LANDING: Hack up CSSParser for speed.

third_party/WebKit/Source/core/css/parser/CSSTokenizer.cpp

Index: third_party/WebKit/Source/core/css/parser/CSSTokenizer.cpp
diff --git a/third_party/WebKit/Source/core/css/parser/CSSTokenizer.cpp b/third_party/WebKit/Source/core/css/parser/CSSTokenizer.cpp
index a4d30292d96e9e7a8fe991a0ae3a42a828060818..df1548f4d5327359dcf2272ea2e286577acacad1 100644
--- a/third_party/WebKit/Source/core/css/parser/CSSTokenizer.cpp
+++ b/third_party/WebKit/Source/core/css/parser/CSSTokenizer.cpp
@@ -18,7 +18,7 @@ namespace blink {
 namespace blink {
 
 CSSTokenizer::Scope::Scope(const String& string)
-: m_string(string)
+    : m_string(string)
 {
     // According to the spec, we should perform preprocessing here.
     // See: http://dev.w3.org/csswg/css-syntax/#input-preprocessing
@@ -48,7 +48,7 @@ CSSTokenizer::Scope::Scope(const String& string)
 }
 
 CSSTokenizer::Scope::Scope(const String& string, CSSParserObserverWrapper& wrapper)
-: m_string(string)
+    : m_string(string)
 {
     if (string.isEmpty())
         return;
@@ -76,7 +76,7 @@ CSSTokenizer::Scope::Scope(const String& string, CSSParserObserverWrapper& wrapp
 
 CSSParserTokenRange CSSTokenizer::Scope::tokenRange()
 {
-    return m_tokens;
+    return CSSParserTokenRange(m_tokens.begin(), m_tokens.end());
 }
 
 unsigned CSSTokenizer::Scope::tokenCount()
@@ -125,7 +125,7 @@ CSSParserToken CSSTokenizer::whiteSpace(UChar cc)
     return CSSParserToken(WhitespaceToken);
 }
 
-static bool popIfBlockMatches(Vector<CSSParserTokenType>& blockStack, CSSParserTokenType type)
+static bool popIfBlockMatches(Vector<CSSParserTokenType, 8>& blockStack, CSSParserTokenType type)
 {
     if (!blockStack.isEmpty() && blockStack.last() == type) {
         blockStack.removeLast();
@@ -358,18 +358,184 @@ CSSParserToken CSSTokenizer::nextToken()
     // incremental tokenization of partial sources.
     // However, for now we follow the spec exactly.
     UChar cc = consume();
-    CodePoint codePointFunc = 0;
 
-    if (isASCII(cc)) {
-        ASSERT_WITH_SECURITY_IMPLICATION(cc < codePointsNumber);
-        codePointFunc = codePoints[cc];
-    } else {
-        codePointFunc = &CSSTokenizer::nameStart;
+    switch (cc) {
+    case 0:
+        return endOfFile(cc);
+    case 1:
+    case 2:
+    case 3:
+    case 4:
+    case 5:
+    case 6:
+    case 7:
+    case 8:
+        return CSSParserToken(DelimiterToken, cc);

[esprehn, 2016/04/22 23:30:58]

Skip the virtual call overhead of the lookup table. This also means we don't
need to pass arguments into the functions like comma() which don't need it.

[Timothy Loh, 2016/04/27 06:52:05]

This is definitely an improvement (I think using code generation to make the
lookup table is just unneeded complexity), but I'm not convinced this will
actually make any performance difference.

+    case 9:
+    case 10:
+        return whiteSpace(cc);
+    case 11:
+        return CSSParserToken(DelimiterToken, cc);
+    case 12:
+    case 13:
+        return whiteSpace(cc);
+    case 14:
+    case 15:
+    case 16:
+    case 17:
+    case 18:
+    case 19:
+    case 20:
+    case 21:
+    case 22:
+    case 23:
+    case 24:
+    case 25:
+    case 26:
+    case 27:
+    case 28:
+    case 29:
+    case 30:
+    case 31:
+        return CSSParserToken(DelimiterToken, cc);
+    case 32:
+        return whiteSpace(cc);
+    case 33:
+        return CSSParserToken(DelimiterToken, cc);
+    case 34:
+        return stringStart(cc);
+    case 35:
+        return hash(cc);
+    case 36:
+        return dollarSign(cc);
+    case 37:
+    case 38:
+        return CSSParserToken(DelimiterToken, cc);
+    case 39:
+        return stringStart(cc);
+    case 40:
+        return leftParenthesis(cc);
+    case 41:
+        return rightParenthesis(cc);
+    case 42:
+        return asterisk(cc);
+    case 43:
+        return plusOrFullStop(cc);
+    case 44:
+        return comma(cc);
+    case 45:
+        return hyphenMinus(cc);
+    case 46:
+        return plusOrFullStop(cc);
+    case 47:
+        return solidus(cc);
+    case 48:
+    case 49:
+    case 50:
+    case 51:
+    case 52:
+    case 53:
+    case 54:
+    case 55:
+    case 56:
+    case 57:
+        return asciiDigit(cc);
+    case 58:
+        return colon(cc);
+    case 59:
+        return semiColon(cc);
+    case 60:
+        return lessThan(cc);
+    case 61:
+    case 62:
+    case 63:
+        return CSSParserToken(DelimiterToken, cc);
+    case 64:
+        return commercialAt(cc);
+    case 65:
+    case 66:
+    case 67:
+    case 68:
+    case 69:
+    case 70:
+    case 71:
+    case 72:
+    case 73:
+    case 74:
+    case 75:
+    case 76:
+    case 77:
+    case 78:
+    case 79:
+    case 80:
+    case 81:
+    case 82:
+    case 83:
+    case 84:
+        return nameStart(cc);
+    case 85:
+        return letterU(cc);
+    case 86:
+    case 87:
+    case 88:
+    case 89:
+    case 90:
+        return nameStart(cc);
+    case 91:
+        return leftBracket(cc);
+    case 92:
+        return reverseSolidus(cc);
+    case 93:
+        return rightBracket(cc);
+    case 94:
+        return circumflexAccent(cc);
+    case 95:
+        return nameStart(cc);
+    case 96:
+        return CSSParserToken(DelimiterToken, cc);
+    case 97:
+    case 98:
+    case 99:
+    case 100:
+    case 101:
+    case 102:
+    case 103:
+    case 104:
+    case 105:
+    case 106:
+    case 107:
+    case 108:
+    case 109:
+    case 110:
+    case 111:
+    case 112:
+    case 113:
+    case 114:
+    case 115:
+    case 116:
+        return nameStart(cc);
+    case 117:
+        return letterU(cc);
+    case 118:
+    case 119:
+    case 120:
+    case 121:
+    case 122:
+        return nameStart(cc);
+    case 123:
+        return leftBrace(cc);
+    case 124:
+        return verticalLine(cc);
+    case 125:
+        return rightBrace(cc);
+    case 126:
+        return tilde(cc);
+    case 127:
+        return CSSParserToken(DelimiterToken, cc);
     }
 
-    if (codePointFunc)
-        return ((this)->*(codePointFunc))(cc);
-    return CSSParserToken(DelimiterToken, cc);
+    ASSERT(!isASCII(cc));
+    return nameStart(cc);
 }
 
 static NumericSign getSign(CSSTokenizerInputStream& input, unsigned& offset)
@@ -619,7 +785,7 @@ void CSSTokenizer::consumeBadUrlRemnants()
     }
 }
 
-void CSSTokenizer::consumeUntilNonWhitespace()
+ALWAYS_INLINE void CSSTokenizer::consumeUntilNonWhitespace()
 {
     // Using HTML space here rather than CSS space since we don't do preprocessing
     while (isHTMLSpace<UChar>(m_input.nextInputChar()))
@@ -749,8 +915,11 @@ bool CSSTokenizer::nextCharsAreNumber()
 // http://dev.w3.org/csswg/css-syntax/#would-start-an-identifier
 bool CSSTokenizer::nextCharsAreIdentifier(UChar first)
 {
+    if (isNameStartCodePoint(first))
+        return true;
+
     UChar second = m_input.nextInputChar();
-    if (isNameStartCodePoint(first) || twoCharsAreValidEscape(first, second))
+    if (twoCharsAreValidEscape(first, second))
         return true;
 
     if (first == '-')