Re-enable Parser::symbol_cache_ (after a long time!)

src/parser.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 189 matching lines @@
     UNREACHABLE();
     return;
   }
   terms_.Add(
       new(zone()) RegExpQuantifier(min, max, quantifier_type, atom), zone());
   LAST(ADD_TERM);
 }
 
 
 Handle<String> Parser::LookupSymbol(int symbol_id) {
-  // Length of symbol cache is the number of identified symbols.
-  // If we are larger than that, or negative, it's not a cached symbol.
-  // This might also happen if there is no preparser symbol data, even
-  // if there is some preparser data.
-  if (static_cast<unsigned>(symbol_id)
-      >= static_cast<unsigned>(symbol_cache_.length())) {
+  // If there is no preparser symbol data, a negative number will be passed. In
+  // that case, we'll just read the literal from Scanner. This also guards
+  // against corrupt preparse data where the symbol id is larger than the symbol
+  // count.
+  if (symbol_id < 0 ||
+      (pre_parse_data_ && symbol_id >= pre_parse_data_->symbol_count())) {
     if (scanner()->is_literal_ascii()) {
       return isolate()->factory()->InternalizeOneByteString(
           Vector<const uint8_t>::cast(scanner()->literal_ascii_string()));
     } else {
       return isolate()->factory()->InternalizeTwoByteString(
           scanner()->literal_utf16_string());
     }
   }
   return LookupCachedSymbol(symbol_id);
 }
@@ skipping 5127 matching lines @@
       ASSERT(info()->isolate()->has_pending_exception());
     } else {
       result = ParseProgram();
     }
   }
   info()->SetFunction(result);
   return (result != NULL);
 }
 
 } }  // namespace v8::internal