Changeset 62628 in webkit for trunk/JavaScriptCore/parser/Lexer.cpp

Timestamp:

Jul 7, 2010, 12:04:46 AM (15 years ago)

Author:

[email protected]

Message:

Refactored string parsing inside the lexer
​https://bugs.webkit.org/show_bug.cgi?id=41606

Reviewed by Oliver Hunt.

Does not use goto. Although the last sunspider
parse-only tests yields 1.044x speedup, I think the
patch can have a slight improvement at most.

• parser/Lexer.cpp:

(JSC::singleEscape):
(JSC::Lexer::parseString):
(JSC::Lexer::lex):

• parser/Lexer.h:

File:

• trunk/JavaScriptCore/parser/Lexer.cpp (modified) (9 diffs)

trunk/JavaScriptCore/parser/Lexer.cpp

@@ -358 +358 @@
         case 'r':
             return 0x0D;
+        case '\\':
+            return '\\';
+        case '\'':
+            return '\'';
+        case '"':
+            return '"';
         default:
-            return c;
+            return 0;
     }
 }
@@ -380 +386 @@
     ASSERT(c <= USHRT_MAX);
     record16(UChar(static_cast<unsigned short>(c)));
+}
+
+ALWAYS_INLINE bool Lexer::parseString(void* lvalp)
+{
+    int stringQuoteCharacter = m_current;
+    shift();
+
+    const UChar* stringStart = currentCharacter();
+
+    while (m_current != stringQuoteCharacter) {
+        if (UNLIKELY(m_current == '\\')) {
+            if (stringStart != currentCharacter())
+                m_buffer16.append(stringStart, currentCharacter() - stringStart);
+            shift();
+
+            int escape = singleEscape(m_current);
+
+            // Most common escape sequences first
+            if (escape) {
+                record16(escape);
+                shift();
+            } else if (UNLIKELY(isLineTerminator(m_current)))
+                shiftLineTerminator();
+            else if (m_current == 'x') {
+                shift();
+                if (isASCIIHexDigit(m_current) && isASCIIHexDigit(peek(1))) {
+                    int prev = m_current;
+                    shift();
+                    record16(convertHex(prev, m_current));
+                    shift();
+                } else
+                    record16('x');
+            } else if (m_current == 'u') {
+                shift();
+                int character = getUnicodeCharacter();
+                if (character != -1)
+                    record16(character);
+                else if (m_current == stringQuoteCharacter)
+                    record16('u');
+                else // Only stringQuoteCharacter allowed after \u
+                    return false;
+            } else if (isASCIIOctalDigit(m_current)) {
+                // Octal character sequences
+                int character1 = m_current;
+                shift();
+                if (isASCIIOctalDigit(m_current)) {
+                    // Two octal characters
+                    int character2 = m_current;
+                    shift();
+                    if (character1 >= '0' && character1 <= '3' && isASCIIOctalDigit(m_current)) {
+                        record16((character1 - '0') * 64 + (character2 - '0') * 8 + m_current - '0');
+                        shift();
+                    } else
+                        record16((character1 - '0') * 8 + character2 - '0');
+                } else
+                    record16(character1 - '0');
+            } else if (m_current != -1) {
+                record16(m_current);
+                shift();
+            } else
+                return false;
+
+            stringStart = currentCharacter();
+            continue;
+        } else if (UNLIKELY(((static_cast<unsigned>(m_current) - 0xE) & 0x2000))) {
+            // New-line or end of input is not allowed
+            if (UNLIKELY(isLineTerminator(m_current)) || UNLIKELY(m_current == -1))
+                return false;
+            // Anything else is just a normal character
+        }
+        shift();
+    }
+
+    if (currentCharacter() != stringStart)
+        m_buffer16.append(stringStart, currentCharacter() - stringStart);
+    reinterpret_cast<YYSTYPE*>(lvalp)->ident = makeIdentifier(m_buffer16.data(), m_buffer16.size());
+    m_buffer16.resize(0);
+    return true;
 }
 
@@ -402 +486 @@
         if (!m_terminator && !m_delimited && !m_isReparsing) {
             // automatic semicolon insertion if program incomplete
-            token = ';';
             goto doneSemicolon;
         }
@@ -409 +492 @@
 
     m_delimited = false;
-    ASSERT(m_current >= 0);
-
-    if (m_current < 128) {
-        ASSERT(isASCII(m_current));
+
+    if (isASCII(m_current)) {
+        ASSERT(m_current >= 0 && m_current < 128);
 
         switch (AsciiCharacters[m_current]) {
@@ -634 +716 @@
             goto startNumber;
         case CharacterQuote:
-            goto startString;
+            if (UNLIKELY(!parseString(lvalp)))
+                goto returnError;
+            shift();
+            m_delimited = false;
+            token = STRING;
+            break;
         case CharacterAlpha:
             ASSERT(isIdentStart(m_current));
@@ -656 +743 @@
     } else {
         // Rare characters
-        ASSERT(!isASCII(m_current));
 
         if (isNonASCIIIdentStart(m_current))
@@ -664 +750 @@
             m_atLineStart = true;
             m_terminator = true;
-            if (lastTokenWasRestrKeyword()) {
-                token = ';';
+            if (lastTokenWasRestrKeyword())
                 goto doneSemicolon;
-            }
             goto start;
         }
@@ -675 +759 @@
     m_atLineStart = false;
     goto returnToken;
-
-startString: {
-    int stringQuoteCharacter = m_current;
-    shift();
-
-    const UChar* stringStart = currentCharacter();
-    while (m_current != stringQuoteCharacter) {
-        // Fast check for characters that require special handling.
-        // Catches -1, \n, \r, \, 0x2028, and 0x2029 as efficiently
-        // as possible, and lets through all common ASCII characters.
-        if (UNLIKELY(m_current == '\\') || UNLIKELY(((static_cast<unsigned>(m_current) - 0xE) & 0x2000))) {
-            m_buffer16.append(stringStart, currentCharacter() - stringStart);
-            goto inString;
-        }
-        shift();
-    }
-    lvalp->ident = makeIdentifier(stringStart, currentCharacter() - stringStart);
-    shift();
-    m_atLineStart = false;
-    m_delimited = false;
-    token = STRING;
-    goto returnToken;
-
-inString:
-    while (m_current != stringQuoteCharacter) {
-        if (m_current == '\\')
-            goto inStringEscapeSequence;
-        if (UNLIKELY(isLineTerminator(m_current)))
-            goto returnError;
-        if (UNLIKELY(m_current == -1))
-            goto returnError;
-        record16(m_current);
-        shift();
-    }
-    goto doneString;
-
-inStringEscapeSequence:
-    shift();
-    if (m_current == 'x') {
-        shift();
-        if (isASCIIHexDigit(m_current) && isASCIIHexDigit(peek(1))) {
-            int prev = m_current;
-            shift();
-            record16(convertHex(prev, m_current));
-            shift();
-            goto inString;
-        }
-        record16('x');
-        if (m_current == stringQuoteCharacter)
-            goto doneString;
-        goto inString;
-    }
-    if (m_current == 'u') {
-        shift();
-        token = getUnicodeCharacter();
-        if (token != -1) {
-            record16(token);
-            goto inString;
-        }
-        if (m_current == stringQuoteCharacter) {
-            record16('u');
-            goto doneString;
-        }
-        goto returnError;
-    }
-    if (isASCIIOctalDigit(m_current)) {
-        int char1 = m_current;
-        shift();
-        if (char1 >= '0' && char1 <= '3' && isASCIIOctalDigit(m_current) && isASCIIOctalDigit(peek(1))) {
-            int char2 = m_current;
-            shift();
-            record16((char1 - '0') * 64 + (char2 - '0') * 8 + m_current - '0');
-            shift();
-            goto inString;
-        }
-        if (isASCIIOctalDigit(m_current)) {
-            record16((char1 - '0') * 8 + m_current - '0');
-            shift();
-            goto inString;
-        }
-        record16(char1 - '0');
-        goto inString;
-    }
-    if (isLineTerminator(m_current)) {
-        shiftLineTerminator();
-        goto inString;
-    }
-    if (m_current == -1)
-        goto returnError;
-    record16(singleEscape(m_current));
-    shift();
-    goto inString;
-}
 
 startIdentifierWithBackslash: {
@@ -1004 +995 @@
     const HashEntry* entry = m_keywordTable.entry(m_globalData, *lvalp->ident);
     token = entry ? entry->lexerValue() : static_cast<int>(IDENT);
-    goto returnToken;
-}
-
-doneString:
-    // Atomize constant strings in case they're later used in property lookup.
-    shift();
-    m_atLineStart = false;
-    m_delimited = false;
-    lvalp->ident = makeIdentifier(m_buffer16.data(), m_buffer16.size());
-    m_buffer16.resize(0);
-    token = STRING;
 
     // Fall through into returnToken.
+}
 
 returnToken: {