Make template scan related function take a template<bool> parameter

This is for performance. Having to do the test in every Advance was too
expensive.

BUG=438991, v8:3230
LOG=N
R=dslomov@chromium.org, marja

Review URL: https://codereview.chromium.org/766193003

Cr-Commit-Position: refs/heads/master@{#25667}

src/scanner.cc

@@ -34,7 +34,6 @@ Handle<String> LiteralBuffer::Internalize(Isolate* isolate) const {
 
 Scanner::Scanner(UnicodeCache* unicode_cache)
     : unicode_cache_(unicode_cache),
-      capturing_raw_literal_(false),
       octal_pos_(Location::invalid()),
       harmony_scoping_(false),
       harmony_modules_(false),
@@ -57,6 +56,7 @@ void Scanner::Initialize(Utf16CharacterStream* source) {
 }
 
 
+template <bool capture_raw>
 uc32 Scanner::ScanHexNumber(int expected_length) {
   DCHECK(expected_length <= 4);  // prevent overflow
 
@@ -67,13 +67,14 @@ uc32 Scanner::ScanHexNumber(int expected_length) {
       return -1;
     }
     x = x * 16 + d;
-    Advance();
+    Advance<capture_raw>();
   }
 
   return x;
 }
 
 
+template <bool capture_raw>
 uc32 Scanner::ScanUnlimitedLengthHexNumber(int max_value) {
   uc32 x = 0;
   int d = HexValue(c0_);
@@ -83,7 +84,7 @@ uc32 Scanner::ScanUnlimitedLengthHexNumber(int max_value) {
   while (d >= 0) {
     x = x * 16 + d;
     if (x > max_value) return -1;
-    Advance();
+    Advance<capture_raw>();
     d = HexValue(c0_);
   }
   return x;
@@ -696,16 +697,17 @@ void Scanner::SeekForward(int pos) {
 }
 
 
+template <bool capture_raw>
 bool Scanner::ScanEscape() {
   uc32 c = c0_;
-  Advance();
+  Advance<capture_raw>();
 
   // Skip escaped newlines.
   if (c0_ >= 0 && unicode_cache_->IsLineTerminator(c)) {
     // Allow CR+LF newlines in multiline string literals.
-    if (IsCarriageReturn(c) && IsLineFeed(c0_)) Advance();
+    if (IsCarriageReturn(c) && IsLineFeed(c0_)) Advance<capture_raw>();
     // Allow LF+CR newlines in multiline string literals.
-    if (IsLineFeed(c) && IsCarriageReturn(c0_)) Advance();
+    if (IsLineFeed(c) && IsCarriageReturn(c0_)) Advance<capture_raw>();
     return true;
   }
 
@@ -719,13 +721,13 @@ bool Scanner::ScanEscape() {
     case 'r' : c = '\r'; break;
     case 't' : c = '\t'; break;
     case 'u' : {
-      c = ScanUnicodeEscape();
+      c = ScanUnicodeEscape<capture_raw>();
       if (c < 0) return false;
       break;
     }
     case 'v' : c = '\v'; break;
     case 'x' : {
-      c = ScanHexNumber(2);
+      c = ScanHexNumber<capture_raw>(2);
       if (c < 0) return false;
       break;
     }
@@ -736,7 +738,9 @@ bool Scanner::ScanEscape() {
     case '4' :  // fall through
     case '5' :  // fall through
     case '6' :  // fall through
-    case '7' : c = ScanOctalEscape(c, 2); break;
+    case '7':
+      c = ScanOctalEscape<capture_raw>(c, 2);
+      break;
   }
 
   // According to ECMA-262, section 7.8.4, characters not covered by the
@@ -749,6 +753,7 @@ bool Scanner::ScanEscape() {
 
 // Octal escapes of the forms '\0xx' and '\xxx' are not a part of
 // ECMA-262. Other JS VMs support them.
+template <bool capture_raw>
 uc32 Scanner::ScanOctalEscape(uc32 c, int length) {
   uc32 x = c - '0';
   int i = 0;
@@ -758,7 +763,7 @@ uc32 Scanner::ScanOctalEscape(uc32 c, int length) {
     int nx = x * 8 + d;
     if (nx >= 256) break;
     x = nx;
-    Advance();
+    Advance<capture_raw>();
   }
   // Anything except '\0' is an octal escape sequence, illegal in strict mode.
   // Remember the position of octal escape sequences so that an error
@@ -782,7 +787,7 @@ Token::Value Scanner::ScanString() {
     uc32 c = c0_;
     Advance();
     if (c == '\\') {
-      if (c0_ < 0 || !ScanEscape()) return Token::ILLEGAL;
+      if (c0_ < 0 || !ScanEscape<false>()) return Token::ILLEGAL;
     } else {
       AddLiteralChar(c);
     }
@@ -810,17 +815,19 @@ Token::Value Scanner::ScanTemplateSpan() {
   // followed by an Expression.
 
   Token::Value result = Token::TEMPLATE_SPAN;
-  LiteralScope literal(this, true);
+  LiteralScope literal(this);
+  StartRawLiteral();
+  const bool capture_raw = true;
 
   while (true) {
     uc32 c = c0_;
-    Advance();
+    Advance<capture_raw>();
     if (c == '`') {
       result = Token::TEMPLATE_TAIL;
       ReduceRawLiteralLength(1);
       break;
     } else if (c == '$' && c0_ == '{') {
-      Advance();  // Consume '{'
+      Advance<capture_raw>();  // Consume '{'
       ReduceRawLiteralLength(2);
       break;
     } else if (c == '\\') {
@@ -828,20 +835,20 @@ Token::Value Scanner::ScanTemplateSpan() {
         // The TV of LineContinuation :: \ LineTerminatorSequence is the empty
         // code unit sequence.
         uc32 lastChar = c0_;
-        Advance();
+        Advance<capture_raw>();
         if (lastChar == '\r') {
           ReduceRawLiteralLength(1);  // Remove \r
           if (c0_ == '\n') {
-            Advance();  // Adds \n
+            Advance<capture_raw>();  // Adds \n
           } else {
             AddRawLiteralChar('\n');
           }
         }
       } else if (c0_ == '0') {
-        Advance();
+        Advance<capture_raw>();
         AddLiteralChar('0');
       } else {
-        ScanEscape();
+        ScanEscape<true>();
       }
     } else if (c < 0) {
       // Unterminated template literal
@@ -854,7 +861,7 @@ Token::Value Scanner::ScanTemplateSpan() {
       if (c == '\r') {
         ReduceRawLiteralLength(1);  // Remove \r
         if (c0_ == '\n') {
-          Advance();  // Adds \n
+          Advance<capture_raw>();  // Adds \n
         } else {
           AddRawLiteralChar('\n');
         }
@@ -1002,27 +1009,28 @@ uc32 Scanner::ScanIdentifierUnicodeEscape() {
   Advance();
   if (c0_ != 'u') return -1;
   Advance();
-  return ScanUnicodeEscape();
+  return ScanUnicodeEscape<false>();
 }
 
 
+template <bool capture_raw>
 uc32 Scanner::ScanUnicodeEscape() {
   // Accept both \uxxxx and \u{xxxxxx} (if harmony unicode escapes are
   // allowed). In the latter case, the number of hex digits between { } is
   // arbitrary. \ and u have already been read.
   if (c0_ == '{' && HarmonyUnicode()) {
-    Advance();
-    uc32 cp = ScanUnlimitedLengthHexNumber(0x10ffff);
+    Advance<capture_raw>();
+    uc32 cp = ScanUnlimitedLengthHexNumber<capture_raw>(0x10ffff);
     if (cp < 0) {
       return -1;
     }
     if (c0_ != '}') {
       return -1;
     }
-    Advance();
+    Advance<capture_raw>();
     return cp;
   }
-  return ScanHexNumber(4);
+  return ScanHexNumber<capture_raw>(4);
 }
 
 

src/scanner.h

@@ -322,16 +322,13 @@ class Scanner {
   // if aborting the scanning before it's complete.
   class LiteralScope {
    public:
-    explicit LiteralScope(Scanner* self, bool capture_raw = false)
-        : scanner_(self), complete_(false) {
+    explicit LiteralScope(Scanner* self) : scanner_(self), complete_(false) {
       scanner_->StartLiteral();
-      if (capture_raw) scanner_->StartRawLiteral();
     }
      ~LiteralScope() {
        if (!complete_) scanner_->DropLiteral();
      }
     void Complete() {
-      scanner_->TerminateLiteral();
       complete_ = true;
     }
 
@@ -506,6 +503,7 @@ class Scanner {
   static const int kCharacterLookaheadBufferSize = 1;
 
   // Scans octal escape sequence. Also accepts "\0" decimal escape sequence.
+  template <bool capture_raw>
   uc32 ScanOctalEscape(uc32 c, int length);
 
   // Call this after setting source_ to the input.
@@ -529,7 +527,6 @@ class Scanner {
   inline void StartRawLiteral() {
     raw_literal_buffer_.Reset();
     next_.raw_literal_chars = &raw_literal_buffer_;
-    capturing_raw_literal_ = true;
   }
 
   INLINE(void AddLiteralChar(uc32 c)) {
@@ -538,26 +535,20 @@ class Scanner {
   }
 
   INLINE(void AddRawLiteralChar(uc32 c)) {
-    DCHECK(capturing_raw_literal_);
     DCHECK_NOT_NULL(next_.raw_literal_chars);
     next_.raw_literal_chars->AddChar(c);
   }
 
   INLINE(void ReduceRawLiteralLength(int delta)) {
-    DCHECK(capturing_raw_literal_);
     DCHECK_NOT_NULL(next_.raw_literal_chars);
     next_.raw_literal_chars->ReduceLength(delta);
   }
 
-  // Complete scanning of a literal.
-  inline void TerminateLiteral() { capturing_raw_literal_ = false; }
-
   // Stops scanning of a literal and drop the collected characters,
   // e.g., due to an encountered error.
   inline void DropLiteral() {
     next_.literal_chars = NULL;
     next_.raw_literal_chars = NULL;
-    capturing_raw_literal_ = false;
   }
 
   inline void AddLiteralCharAdvance() {
@@ -566,8 +557,9 @@ class Scanner {
   }
 
   // Low-level scanning support.
+  template <bool capture_raw = false>
   void Advance() {
-    if (capturing_raw_literal_) {
+    if (capture_raw) {
       AddRawLiteralChar(c0_);
     }
     c0_ = source_->Advance();
@@ -585,10 +577,8 @@ class Scanner {
     if (ch > static_cast<uc32>(unibrow::Utf16::kMaxNonSurrogateCharCode)) {
       source_->PushBack(unibrow::Utf16::TrailSurrogate(c0_));
       source_->PushBack(unibrow::Utf16::LeadSurrogate(c0_));
-      if (capturing_raw_literal_) ReduceRawLiteralLength(2);
     } else {
       source_->PushBack(c0_);
-      if (capturing_raw_literal_) ReduceRawLiteralLength(1);
     }
     c0_ = ch;
   }
@@ -613,8 +603,8 @@ class Scanner {
   // Literal strings are collected for identifiers, strings, numbers as well
   // as for template literals. For template literals we also collect the raw
   // form.
-  // These functions only give the correct result if the literal
-  // was scanned between calls to StartLiteral() and TerminateLiteral().
+  // These functions only give the correct result if the literal was scanned
+  // when a LiteralScope object is alive.
   Vector<const uint8_t> literal_one_byte_string() {
     DCHECK_NOT_NULL(current_.literal_chars);
     return current_.literal_chars->one_byte_literal();
@@ -658,11 +648,12 @@ class Scanner {
     return current_.raw_literal_chars->is_one_byte();
   }
 
-
+  template <bool capture_raw>
   uc32 ScanHexNumber(int expected_length);
   // Scan a number of any length but not bigger than max_value. For example, the
   // number can be 000000001, so it's very long in characters but its value is
   // small.
+  template <bool capture_raw>
   uc32 ScanUnlimitedLengthHexNumber(int max_value);
 
   // Scans a single JavaScript token.
@@ -686,11 +677,13 @@ class Scanner {
   // Scans an escape-sequence which is part of a string and adds the
   // decoded character to the current literal. Returns true if a pattern
   // is scanned.
+  template <bool capture_raw>
   bool ScanEscape();
   // Decodes a Unicode escape-sequence which is part of an identifier.
   // If the escape sequence cannot be decoded the result is kBadChar.
   uc32 ScanIdentifierUnicodeEscape();
   // Helper for the above functions.
+  template <bool capture_raw>
   uc32 ScanUnicodeEscape();
 
   Token::Value ScanTemplateSpan();
@@ -713,10 +706,6 @@ class Scanner {
   // Buffer to store raw string values
   LiteralBuffer raw_literal_buffer_;
 
-  // We only need to capture the raw literal when we are scanning template
-  // literal spans.
-  bool capturing_raw_literal_;
-
   TokenDesc current_;  // desc for current token (as returned by Next())
   TokenDesc next_;     // desc for next token (one token look-ahead)