Move some arrays into functions so they don't get cloned on each new context.

src/messages.js

 // Copyright 2006-2008 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 10 matching lines @@
 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 
 // -------------------------------------------------------------------
 
-const kVowelSounds = {a: true, e: true, i: true, o: true, u: true, y: true};
-const kCapitalVowelSounds = {a: true, e: true, i: true, o: true, u: true,
-    h: true, f: true, l: true, m: true, n: true, r: true, s: true, x: true,
-    y: true};
-
 function GetInstanceName(cons) {
   if (cons.length == 0) {
     return "";
   }
   var first = %StringToLowerCase(StringCharAt.call(cons, 0));
-  var mapping = kVowelSounds;
+  var vowel_mapping = {a: true, e: true, i: true, o: true, u: true, y: true};

[Mads Ager (chromium), 2009/08/12 13:44:48]

Should we do lazy initialization of these instead as you do for kMessages?

   if (cons.length > 1 && (StringCharAt.call(cons, 0) != first)) {
     // First char is upper case
     var second = %StringToLowerCase(StringCharAt.call(cons, 1));
     // Second char is upper case
     if (StringCharAt.call(cons, 1) != second)
-      mapping = kCapitalVowelSounds;
+      // Capital vowel sounds.
+      vowel_mapping = {a: true, e: true, i: true, o: true, u: true, h: true,
+          f: true, l: true, m: true, n: true, r: true, s: true, x: true,
+          y: true};
+
   }
-  var s = mapping[first] ? "an " : "a ";
+  var s = vowel_mapping[first] ? "an " : "a ";
   return s + cons;
 }
 
 
-const kMessages = {
-  // Error
-  cyclic_proto:                 "Cyclic __proto__ value",
-  // TypeError
-  unexpected_token:             "Unexpected token %0",
-  unexpected_token_number:      "Unexpected number",
-  unexpected_token_string:      "Unexpected string",
-  unexpected_token_identifier:  "Unexpected identifier",
-  unexpected_eos:               "Unexpected end of input",
-  malformed_regexp:             "Invalid regular expression: /%0/: %1",
-  unterminated_regexp:          "Invalid regular expression: missing /",
-  regexp_flags:                 "Cannot supply flags when constructing one RegExp from another",
-  invalid_lhs_in_assignment:    "Invalid left-hand side in assignment",
-  invalid_lhs_in_for_in:        "Invalid left-hand side in for-in",
-  invalid_lhs_in_postfix_op:    "Invalid left-hand side expression in postfix operation",
-  invalid_lhs_in_prefix_op:     "Invalid left-hand side expression in prefix operation",
-  multiple_defaults_in_switch:  "More than one default clause in switch statement",
-  newline_after_throw:          "Illegal newline after throw",
-  redeclaration:                "%0 '%1' has already been declared",
-  no_catch_or_finally:          "Missing catch or finally after try",
-  unknown_label:                "Undefined label '%0'",
-  uncaught_exception:           "Uncaught %0",
-  stack_trace:                  "Stack Trace:\n%0",
-  called_non_callable:          "%0 is not a function",
-  undefined_method:             "Object %1 has no method '%0'",
-  property_not_function:        "Property '%0' of object %1 is not a function",
-  cannot_convert_to_primitive:  "Cannot convert object to primitive value",
-  not_constructor:              "%0 is not a constructor",
-  not_defined:                  "%0 is not defined",
-  non_object_property_load:     "Cannot read property '%0' of %1",
-  non_object_property_store:    "Cannot set property '%0' of %1",
-  non_object_property_call:     "Cannot call method '%0' of %1",
-  with_expression:              "%0 has no properties",
-  illegal_invocation:           "Illegal invocation",
-  no_setter_in_callback:        "Cannot set property %0 of %1 which has only a getter",
-  apply_non_function:           "Function.prototype.apply was called on %0, which is a %1 and not a function",
-  apply_wrong_args:             "Function.prototype.apply: Arguments list has wrong type",
-  invalid_in_operator_use:      "Cannot use 'in' operator to search for '%0' in %1",
-  instanceof_function_expected: "Expecting a function in instanceof check, but got %0",
-  instanceof_nonobject_proto:   "Function has non-object prototype '%0' in instanceof check",
-  null_to_object:               "Cannot convert null to object",
-  reduce_no_initial:            "Reduce of empty array with no initial value",
-  // RangeError
-  invalid_array_length:         "Invalid array length",
-  stack_overflow:               "Maximum call stack size exceeded",
-  apply_overflow:               "Function.prototype.apply cannot support %0 arguments",
-  // SyntaxError
-  unable_to_parse:              "Parse error",
-  duplicate_regexp_flag:        "Duplicate RegExp flag %0",
-  invalid_regexp:               "Invalid RegExp pattern /%0/",
-  illegal_break:                "Illegal break statement",
-  illegal_continue:             "Illegal continue statement",
-  illegal_return:               "Illegal return statement",
-  error_loading_debugger:       "Error loading debugger %0",
-  no_input_to_regexp:           "No input to %0",
-  result_not_primitive:         "Result of %0 must be a primitive, was %1",
-  invalid_json:                 "String '%0' is not valid JSON",
-  circular_structure:           "Converting circular structure to JSON"
-};
+// Lazily initialized array of messages.
+var kMessages = 0;
 
 
 function FormatString(format, args) {
   var result = format;
   for (var i = 0; i < args.length; i++) {
     var str;
     try { str = ToDetailString(args[i]); }
     catch (e) { str = "#<error>"; }
     result = ArrayJoin.call(StringSplit.call(result, "%" + i), str);
   }
@@ skipping 31 matching lines @@
 %FunctionSetInstanceClassName(Script, 'Script');
 %SetProperty(Script.prototype, 'constructor', Script, DONT_ENUM);
 %SetCode(Script, function(x) {
   // Script objects can only be created by the VM.
   throw new $Error("Not supported");
 });
 
 
 // Helper functions; called from the runtime system.
 function FormatMessage(message) {
+  if (kMessages == 0) {
+    kMessages = {
+      // Error
+      cyclic_proto:                 "Cyclic __proto__ value",
+      // TypeError
+      unexpected_token:             "Unexpected token %0",
+      unexpected_token_number:      "Unexpected number",
+      unexpected_token_string:      "Unexpected string",
+      unexpected_token_identifier:  "Unexpected identifier",
+      unexpected_eos:               "Unexpected end of input",
+      malformed_regexp:             "Invalid regular expression: /%0/: %1",
+      unterminated_regexp:          "Invalid regular expression: missing /",
+      regexp_flags:                 "Cannot supply flags when constructing one RegExp from another",
+      invalid_lhs_in_assignment:    "Invalid left-hand side in assignment",
+      invalid_lhs_in_for_in:        "Invalid left-hand side in for-in",
+      invalid_lhs_in_postfix_op:    "Invalid left-hand side expression in postfix operation",
+      invalid_lhs_in_prefix_op:     "Invalid left-hand side expression in prefix operation",
+      multiple_defaults_in_switch:  "More than one default clause in switch statement",
+      newline_after_throw:          "Illegal newline after throw",
+      redeclaration:                "%0 '%1' has already been declared",
+      no_catch_or_finally:          "Missing catch or finally after try",
+      unknown_label:                "Undefined label '%0'",
+      uncaught_exception:           "Uncaught %0",
+      stack_trace:                  "Stack Trace:\n%0",
+      called_non_callable:          "%0 is not a function",
+      undefined_method:             "Object %1 has no method '%0'",
+      property_not_function:        "Property '%0' of object %1 is not a function",
+      cannot_convert_to_primitive:  "Cannot convert object to primitive value",
+      not_constructor:              "%0 is not a constructor",
+      not_defined:                  "%0 is not defined",
+      non_object_property_load:     "Cannot read property '%0' of %1",
+      non_object_property_store:    "Cannot set property '%0' of %1",
+      non_object_property_call:     "Cannot call method '%0' of %1",
+      with_expression:              "%0 has no properties",
+      illegal_invocation:           "Illegal invocation",
+      no_setter_in_callback:        "Cannot set property %0 of %1 which has only a getter",
+      apply_non_function:           "Function.prototype.apply was called on %0, which is a %1 and not a function",
+      apply_wrong_args:             "Function.prototype.apply: Arguments list has wrong type",
+      invalid_in_operator_use:      "Cannot use 'in' operator to search for '%0' in %1",
+      instanceof_function_expected: "Expecting a function in instanceof check, but got %0",
+      instanceof_nonobject_proto:   "Function has non-object prototype '%0' in instanceof check",
+      null_to_object:               "Cannot convert null to object",
+      reduce_no_initial:            "Reduce of empty array with no initial value",
+      // RangeError
+      invalid_array_length:         "Invalid array length",
+      stack_overflow:               "Maximum call stack size exceeded",
+      apply_overflow:               "Function.prototype.apply cannot support %0 arguments",
+      // SyntaxError
+      unable_to_parse:              "Parse error",
+      duplicate_regexp_flag:        "Duplicate RegExp flag %0",
+      invalid_regexp:               "Invalid RegExp pattern /%0/",
+      illegal_break:                "Illegal break statement",
+      illegal_continue:             "Illegal continue statement",
+      illegal_return:               "Illegal return statement",
+      error_loading_debugger:       "Error loading debugger %0",
+      no_input_to_regexp:           "No input to %0",
+      result_not_primitive:         "Result of %0 must be a primitive, was %1",
+      invalid_json:                 "String '%0' is not valid JSON",
+      circular_structure:           "Converting circular structure to JSON"
+    };
+  }
   var format = kMessages[message.type];
   if (!format) return "<unknown message " + message.type + ">";
   return FormatString(format, message.args);
 }
 
 
 function GetLineNumber(message) {
   if (message.startPos == -1) return -1;
   var location = message.script.locationFromPosition(message.startPos, true);
   if (location == null) return -1;
@@ skipping 703 matching lines @@
     return this.name + ": " + FormatMessage({ type: type, args: this.arguments });
   }
   var message = this.message;
   return this.name + (message ? (": " + message) : "");
 }, DONT_ENUM);
 
 
 // Boilerplate for exceptions for stack overflows. Used from
 // Top::StackOverflow().
 const kStackOverflowBoilerplate = MakeRangeError('stack_overflow', []);