Add UseCounter for Date.parse's legacy parse heuristics.

src/dateparser-inl.h

 // Copyright 2011 the V8 project 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 V8_DATEPARSER_INL_H_
 #define V8_DATEPARSER_INL_H_
 
 #include "src/char-predicates-inl.h"
 #include "src/dateparser.h"
 #include "src/unicode-cache-inl.h"
 
 namespace v8 {
 namespace internal {
 
 template <typename Char>
-bool DateParser::Parse(Vector<Char> str,
-                       FixedArray* out,
-                       UnicodeCache* unicode_cache) {
+bool DateParser::Parse(Isolate* isolate, Vector<Char> str, FixedArray* out) {
+  UnicodeCache* unicode_cache = isolate->unicode_cache();
   DCHECK(out->length() >= OUTPUT_SIZE);
   InputReader<Char> in(unicode_cache, str);
   DateStringTokenizer<Char> scanner(&in);
   TimeZoneComposer tz;
   TimeComposer time;
   DayComposer day;
 
   // Specification:
   // Accept ES5 ISO 8601 date-time-strings or legacy dates compatible
   // with Safari.
@@ skipping 40 matching lines @@
   //  specification.
   //  After a valid "T" has been read while scanning an ES5 datetime string,
   //  the input can no longer be a valid legacy date, since the "T" is a
   //  garbage string after a number has been read.
 
   // First try getting as far as possible with as ES5 Date Time String.
   DateToken next_unhandled_token = ParseES5DateTime(&scanner, &day, &time, &tz);
   if (next_unhandled_token.IsInvalid()) return false;
   bool has_read_number = !day.IsEmpty();
   // If there's anything left, continue with the legacy parser.
+  bool legacy_parser = !next_unhandled_token.IsEndOfInput();
   for (DateToken token = next_unhandled_token;
        !token.IsEndOfInput();
        token = scanner.Next()) {
     if (token.IsNumber()) {
       has_read_number = true;
       int n = token.number();
       if (scanner.SkipSymbol(':')) {
         if (scanner.SkipSymbol(':')) {
           // n + "::"
           if (!time.IsEmpty()) return false;
@@ skipping 74 matching lines @@
       }
     } else if ((token.IsAsciiSign() || token.IsSymbol(')')) &&
                has_read_number) {
       // Extra sign or ')' is illegal if a number has been read.
       return false;
     } else {
       // Ignore other characters and whitespace.
     }
   }
 
-  return day.Write(out) && time.Write(out) && tz.Write(out);
+  bool success = day.Write(out) && time.Write(out) && tz.Write(out);
+
+  if (legacy_parser && success) {
+    isolate->CountUsage(v8::Isolate::kLegacyDateParser);

[Dan Ehrenberg, 2016/06/09 12:16:32]

I bet we'll find that this gets hit a significant amount of the time (based on
the fact that we and other browsers get a bunch of bug reports about this path).
If we want to lock things down, we will probably need some more fine-grained use
counters. For example, we ignore arbitrary characters at the end of a date, but
I don't believe other browsers do, so this may be something specific to count.

+  }
+
+  return success;
 }
 
 
 template<typename CharType>
 DateParser::DateToken DateParser::DateStringTokenizer<CharType>::Scan() {
   int pre_pos = in_->position();
   if (in_->IsEnd()) return DateToken::EndOfInput();
   if (in_->IsAsciiDigit()) {
     int n = in_->ReadUnsignedNumeral();
     int length = in_->position() - pre_pos;
@@ skipping 154 matching lines @@
   if (tz->IsEmpty()) tz->Set(0);
   day->set_iso_date();
   return DateToken::EndOfInput();
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_DATEPARSER_INL_H_