Cosmetic: Add macros for NaN, undefined and Infinity to native js code.

Nobody should need to use $NaN, 0/0, 1/0 and void 0. R=mvstanton@chromium.org BUG= Review URL: https://codereview.chromium.org/27491002 git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@17252 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

Cosmetic: Add macros for NaN, undefined and Infinity to native js code.
Nobody should need to use $NaN, 0/0, 1/0 and void 0. R=mvstanton@chromium.org BUG= Review URL: https://codereview.chromium.org/27491002 git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@17252 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
8ef4b0ca · yangguo@chromium.org · f8cc87a0 · 8ef4b0ca · 8ef4b0ca · 8ef4b0ca
Commit 8ef4b0ca authored Oct 17, 2013 by yangguo@chromium.org
18 changed files
--- a/src/array-iterator.js
+++ b/src/array-iterator.js
@@ -36,9 +36,9 @@ var ARRAY_ITERATOR_KIND_VALUES = 2;
 var ARRAY_ITERATOR_KIND_ENTRIES = 3;
 // The spec draft also has "sparse" but it is never used.
-var iteratorObjectSymbol = %CreateSymbol(void 0);
+var iteratorObjectSymbol = %CreateSymbol(UNDEFINED);
-var arrayIteratorNextIndexSymbol = %CreateSymbol(void 0);
+var arrayIteratorNextIndexSymbol = %CreateSymbol(UNDEFINED);
-var arrayIterationKindSymbol = %CreateSymbol(void 0);
+var arrayIterationKindSymbol = %CreateSymbol(UNDEFINED);
 function ArrayIterator() {}
@@ -74,7 +74,7 @@ function ArrayIteratorNext() {
  if (index >= length) {
    iterator[arrayIteratorNextIndexSymbol] = 1 / 0; // Infinity
-    return CreateIteratorResultObject(void 0, true);
+    return CreateIteratorResultObject(UNDEFINED, true);
  }
  iterator[arrayIteratorNextIndexSymbol] = index + 1;

--- a/src/array.js
+++ b/src/array.js
@@ -677,7 +677,7 @@ function ArraySlice(start, end) {
  var start_i = TO_INTEGER(start);
  var end_i = len;
-  if (end !== void 0) end_i = TO_INTEGER(end);
+  if (!IS_UNDEFINED(end)) end_i = TO_INTEGER(end);
  if (start_i < 0) {
    start_i += len;
@@ -1016,7 +1016,7 @@ function ArraySort(comparefn) {
        var proto_length = indices;
        for (var i = from; i < proto_length; i++) {
          if (proto.hasOwnProperty(i)) {
-            obj[i] = void 0;
+            obj[i] = UNDEFINED;
          }
        }
      } else {
@@ -1024,7 +1024,7 @@ function ArraySort(comparefn) {
          var index = indices[i];
          if (!IS_UNDEFINED(index) && from <= index &&
              proto.hasOwnProperty(index)) {
-            obj[index] = void 0;
+            obj[index] = UNDEFINED;
          }
        }
      }
@@ -1061,7 +1061,7 @@ function ArraySort(comparefn) {
      if (first_undefined < last_defined) {
        // Fill in hole or undefined.
        obj[first_undefined] = obj[last_defined];
-        obj[last_defined] = void 0;
+        obj[last_defined] = UNDEFINED;
      }
    }
    // If there were any undefineds in the entire array, first_undefined
@@ -1073,12 +1073,12 @@ function ArraySort(comparefn) {
    // an undefined should be and vice versa.
    var i;
    for (i = first_undefined; i < length - num_holes; i++) {
-      obj[i] = void 0;
+      obj[i] = UNDEFINED;
    }
    for (i = length - num_holes; i < length; i++) {
      // For compatability with Webkit, do not expose elements in the prototype.
      if (i in %GetPrototype(obj)) {
-        obj[i] = void 0;
+        obj[i] = UNDEFINED;
      } else {
        delete obj[i];
      }

--- a/src/d8.js
+++ b/src/d8.js
@@ -40,7 +40,7 @@ function log10(num) {
 function ToInspectableObject(obj) {
  if (!obj && typeof obj === 'object') {
-    return void 0;
+    return UNDEFINED;
  } else {
    return Object(obj);
  }
@@ -333,7 +333,7 @@ function DebugRequest(cmd_line) {
  }
  if ((cmd === undefined) || !cmd) {
-    this.request_ = void 0;
+    this.request_ = UNDEFINED;
    return;
  }
@@ -492,7 +492,7 @@ function DebugRequest(cmd_line) {
    case 'trace':
    case 'tr':
      // Return undefined to indicate command handled internally (no JSON).
-      this.request_ = void 0;
+      this.request_ = UNDEFINED;
      this.traceCommand_(args);
      break;
@@ -500,7 +500,7 @@ function DebugRequest(cmd_line) {
    case '?':
      this.helpCommand_(args);
      // Return undefined to indicate command handled internally (no JSON).
-      this.request_ = void 0;
+      this.request_ = UNDEFINED;
      break;
    default:
@@ -2124,7 +2124,7 @@ function SimpleObjectToJSON_(object) {
      var property_value_json;
      switch (typeof property_value) {
        case 'object':
-          if (property_value === null) {
+          if (IS_NULL(property_value)) {
            property_value_json = 'null';
          } else if (typeof property_value.toJSONProtocol == 'function') {
            property_value_json = property_value.toJSONProtocol(true);
@@ -2217,7 +2217,7 @@ function Stringify(x, depth) {
    case "symbol":
      return "Symbol(" + (x.name ? Stringify(x.name, depth) : "") + ")"
    case "object":
-      if (x === null) return "null";
+      if (IS_NULL(x)) return "null";
      if (x.constructor && x.constructor.name === "Array") {
        var elems = [];
        for (var i = 0; i < x.length; ++i) {
@@ -2233,7 +2233,7 @@ function Stringify(x, depth) {
      var props = [];
      for (var name in x) {
        var desc = Object.getOwnPropertyDescriptor(x, name);
-        if (desc === void 0) continue;
+        if (IS_UNDEFINED(desc)) continue;
        if ("value" in desc) {
          props.push(name + ": " + Stringify(desc.value, depth - 1));
        }

--- a/src/date.js
+++ b/src/date.js
@@ -41,7 +41,7 @@ function ThrowDateTypeError() {
 }
-var timezone_cache_time = $NaN;
+var timezone_cache_time = NAN;
 var timezone_cache_timezone;
 function LocalTimezone(t) {
@@ -66,10 +66,10 @@ function UTC(time) {
 // ECMA 262 - 15.9.1.11
 function MakeTime(hour, min, sec, ms) {
-  if (!$isFinite(hour)) return $NaN;
+  if (!$isFinite(hour)) return NAN;
-  if (!$isFinite(min)) return $NaN;
+  if (!$isFinite(min)) return NAN;
-  if (!$isFinite(sec)) return $NaN;
+  if (!$isFinite(sec)) return NAN;
-  if (!$isFinite(ms)) return $NaN;
+  if (!$isFinite(ms)) return NAN;
  return TO_INTEGER(hour) * msPerHour
      + TO_INTEGER(min) * msPerMinute
      + TO_INTEGER(sec) * msPerSecond
@@ -90,7 +90,7 @@ function TimeInYear(year) {
 //     MakeDay(2007, -33, 1) --> MakeDay(2004, 3, 1)
 //     MakeDay(2007, 14, -50) --> MakeDay(2007, 8, 11)
 function MakeDay(year, month, date) {
-  if (!$isFinite(year) || !$isFinite(month) || !$isFinite(date)) return $NaN;
+  if (!$isFinite(year) || !$isFinite(month) || !$isFinite(date)) return NAN;
  // Convert to integer and map -0 to 0.
  year = TO_INTEGER_MAP_MINUS_ZERO(year);
@@ -99,7 +99,7 @@ function MakeDay(year, month, date) {
  if (year < kMinYear || year > kMaxYear ||
      month < kMinMonth || month > kMaxMonth) {
-    return $NaN;
+    return NAN;
  }
  // Now we rely on year and month being SMIs.
@@ -115,15 +115,15 @@ function MakeDate(day, time) {
  // is no way that the time can be within range even after UTC
  // conversion we return NaN immediately instead of relying on
  // TimeClip to do it.
-  if ($abs(time) > MAX_TIME_BEFORE_UTC) return $NaN;
+  if ($abs(time) > MAX_TIME_BEFORE_UTC) return NAN;
  return time;
 }
 // ECMA 262 - 15.9.1.14
 function TimeClip(time) {
-  if (!$isFinite(time)) return $NaN;
+  if (!$isFinite(time)) return NAN;
-  if ($abs(time) > MAX_TIME_MS) return $NaN;
+  if ($abs(time) > MAX_TIME_MS) return NAN;
  return TO_INTEGER(time);
 }
@@ -132,7 +132,7 @@ function TimeClip(time) {
 // strings over and over again.
 var Date_cache = {
  // Cached time value.
-  time: $NaN,
+  time: NAN,
  // String input for which the cached time is valid.
  string: null
 };
@@ -269,7 +269,7 @@ var parse_buffer = $Array(8);
 // ECMA 262 - 15.9.4.2
 function DateParse(string) {
  var arr = %DateParseString(ToString(string), parse_buffer);
-  if (IS_NULL(arr)) return $NaN;
+  if (IS_NULL(arr)) return NAN;
  var day = MakeDay(arr[0], arr[1], arr[2]);
  var time = MakeTime(arr[3], arr[4], arr[5], arr[6]);
@@ -671,7 +671,7 @@ function DateGetYear() {
 function DateSetYear(year) {
  CHECK_DATE(this);
  year = ToNumber(year);
-  if (NUMBER_IS_NAN(year)) return SET_UTC_DATE_VALUE(this, $NaN);
+  if (NUMBER_IS_NAN(year)) return SET_UTC_DATE_VALUE(this, NAN);
  year = (0 <= TO_INTEGER(year) && TO_INTEGER(year) <= 99)
      ? 1900 + TO_INTEGER(year) : year;
  var t = LOCAL_DATE_VALUE(this);
@@ -746,12 +746,12 @@ function DateToJSON(key) {
 function ResetDateCache() {
  // Reset the timezone cache:
-  timezone_cache_time = $NaN;
+  timezone_cache_time = NAN;
  timezone_cache_timezone = undefined;
  // Reset the date cache:
  cache = Date_cache;
-  cache.time = $NaN;
+  cache.time = NAN;
  cache.string = null;
 }
@@ -762,7 +762,7 @@ function SetUpDate() {
  %CheckIsBootstrapping();
  %SetCode($Date, DateConstructor);
-  %FunctionSetPrototype($Date, new $Date($NaN));
+  %FunctionSetPrototype($Date, new $Date(NAN));
  // Set up non-enumerable properties of the Date object itself.
  InstallFunctions($Date, DONT_ENUM, $Array(

--- a/src/debug-debugger.js
+++ b/src/debug-debugger.js
@@ -448,7 +448,7 @@ ScriptBreakPoint.prototype.set = function (script) {
  // If the position is not found in the script (the script might be shorter
  // than it used to be) just ignore it.
-  if (position === null) return;
+  if (IS_NULL(position)) return;
  // Create a break point object and set the break point.
  break_point = MakeBreakPoint(position, this);
@@ -2064,7 +2064,7 @@ DebugCommandProcessor.resolveValue_ = function(value_description) {
  } else if ("value" in value_description) {
    return value_description.value;
  } else if (value_description.type == UNDEFINED_TYPE) {
-    return void 0;
+    return UNDEFINED;
  } else if (value_description.type == NULL_TYPE) {
    return null;
  } else {

--- a/src/i18n.js
+++ b/src/i18n.js
@@ -290,7 +290,7 @@ function addBoundMethod(obj, methodName, implementation, length) {
 * Parameter locales is treated as a priority list.
 */
 function supportedLocalesOf(service, locales, options) {
-  if (service.match(GetServiceRE()) === null) {
+  if (IS_NULL(service.match(GetServiceRE()))) {
    throw new $Error('Internal error, wrong service type: ' + service);
  }
@@ -447,7 +447,7 @@ function resolveLocale(service, requestedLocales, options) {
 * lookup algorithm.
 */
 function lookupMatcher(service, requestedLocales) {
-  if (service.match(GetServiceRE()) === null) {
+  if (IS_NULL(service.match(GetServiceRE()))) {
    throw new $Error('Internal error, wrong service type: ' + service);
  }
@@ -463,7 +463,7 @@ function lookupMatcher(service, requestedLocales) {
      if (AVAILABLE_LOCALES[service][locale] !== undefined) {
        // Return the resolved locale and extension.
        var extensionMatch = requestedLocales[i].match(GetUnicodeExtensionRE());
-        var extension = (extensionMatch === null) ? '' : extensionMatch[0];
+        var extension = IS_NULL(extensionMatch) ? '' : extensionMatch[0];
        return {'locale': locale, 'extension': extension, 'position': i};
      }
      // Truncate locale if possible.
@@ -535,7 +535,7 @@ function parseExtension(extension) {
 * Converts parameter to an Object if possible.
 */
 function toObject(value) {
-  if (value === undefined || value === null) {
+  if (IS_NULL_OR_UNDEFINED(value)) {
    throw new $TypeError('Value cannot be converted to an Object.');
  }
@@ -733,7 +733,7 @@ function toTitleCaseWord(word) {
 function canonicalizeLanguageTag(localeID) {
  // null is typeof 'object' so we have to do extra check.
  if (typeof localeID !== 'string' && typeof localeID !== 'object' ||
-      localeID === null) {
+      IS_NULL(localeID)) {
    throw new $TypeError('Language ID should be string or object.');
  }
@@ -1449,7 +1449,7 @@ function fromLDMLString(ldmlString) {
 function appendToDateTimeObject(options, option, match, pairs) {
-  if (match === null) {
+  if (IS_NULL(match)) {
    if (!options.hasOwnProperty(option)) {
      defineWEProperty(options, option, undefined);
    }
@@ -1751,7 +1751,7 @@ function canonicalizeTimeZoneID(tzID) {
  // We expect only _ and / beside ASCII letters.
  // All inputs should conform to Area/Location from now on.
  var match = GetTimezoneNameCheckRE().exec(tzID);
-  if (match === null) {
+  if (IS_NULL(match)) {
    throw new $RangeError('Expected Area/Location for time zone, got ' + tzID);
  }
@@ -1971,7 +1971,7 @@ $Object.defineProperty($String.prototype, 'localeCompare', {
      throw new $TypeError(ORDINARY_FUNCTION_CALLED_AS_CONSTRUCTOR);
    }
-    if (this === undefined || this === null) {
+    if (IS_NULL_OR_UNDEFINED(this)) {
      throw new $TypeError('Method invoked on undefined or null value.');
    }

--- a/src/json.js
+++ b/src/json.js
@@ -181,7 +181,7 @@ function JSONSerialize(key, holder, replacer, stack, indent, gap) {
    }
  }
  // Undefined or a callable object.
-  return void 0;
+  return UNDEFINED;
 }
@@ -236,5 +236,5 @@ function JSONSerializeAdapter(key, object) {
  var holder = {};
  holder[key] = object;
  // No need to pass the actual holder since there is no replacer function.
-  return JSONSerialize(key, holder, void 0, new InternalArray(), "", "");
+  return JSONSerialize(key, holder, UNDEFINED, new InternalArray(), "", "");
 }
--- a/src/liveedit-debugger.js
+++ b/src/liveedit-debugger.js
@@ -186,7 +186,7 @@ Debug.LiveEdit = new function() {
    // to old version.
    if (link_to_old_script_list.length == 0) {
      %LiveEditReplaceScript(script, new_source, null);
-      old_script = void 0;
+      old_script = UNDEFINED;
    } else {
      var old_script_name = CreateNameForOldScript(script);
@@ -266,7 +266,7 @@ Debug.LiveEdit = new function() {
      // LiveEdit itself believe that any function in heap that points to a
      // particular script is a regular function.
      // For some functions we will restore this link later.
-      %LiveEditFunctionSetScript(info.shared_function_info, void 0);
+      %LiveEditFunctionSetScript(info.shared_function_info, UNDEFINED);
      compile_info.push(info);
      old_index_map.push(i);
    }
@@ -542,16 +542,16 @@ Debug.LiveEdit = new function() {
    this.children = children;
    // an index in array of compile_info
    this.array_index = array_index;
-    this.parent = void 0;
+    this.parent = UNDEFINED;
    this.status = FunctionStatus.UNCHANGED;
    // Status explanation is used for debugging purposes and will be shown
    // in user UI if some explanations are needed.
-    this.status_explanation = void 0;
+    this.status_explanation = UNDEFINED;
-    this.new_start_pos = void 0;
+    this.new_start_pos = UNDEFINED;
-    this.new_end_pos = void 0;
+    this.new_end_pos = UNDEFINED;
-    this.corresponding_node = void 0;
+    this.corresponding_node = UNDEFINED;
-    this.unmatched_new_nodes = void 0;
+    this.unmatched_new_nodes = UNDEFINED;
    // 'Textual' correspondence/matching is weaker than 'pure'
    // correspondence/matching. We need 'textual' level for visual presentation
@@ -559,10 +559,10 @@ Debug.LiveEdit = new function() {
    // Sometimes only function body is changed (functions in old and new script
    // textually correspond), but we cannot patch the code, so we see them
    // as an old function deleted and new function created.
-    this.textual_corresponding_node = void 0;
+    this.textual_corresponding_node = UNDEFINED;
-    this.textually_unmatched_new_nodes = void 0;
+    this.textually_unmatched_new_nodes = UNDEFINED;
-    this.live_shared_function_infos = void 0;
+    this.live_shared_function_infos = UNDEFINED;
  }
  // From array of function infos that is implicitly a tree creates
@@ -740,7 +740,7 @@ Debug.LiveEdit = new function() {
                old_children[old_index].status_explanation =
                    "Enclosing function is now incompatible. " +
                    scope_change_description;
-                old_children[old_index].corresponding_node = void 0;
+                old_children[old_index].corresponding_node = UNDEFINED;
              } else if (old_children[old_index].status !=
                  FunctionStatus.UNCHANGED) {
                ProcessNode(old_children[old_index],
@@ -748,7 +748,7 @@ Debug.LiveEdit = new function() {
                if (old_children[old_index].status == FunctionStatus.DAMAGED) {
                  unmatched_new_nodes_list.push(
                      old_children[old_index].corresponding_node);
-                  old_children[old_index].corresponding_node = void 0;
+                  old_children[old_index].corresponding_node = UNDEFINED;
                  old_node.status = FunctionStatus.CHANGED;
                }
              }

--- a/src/macros.py
+++ b/src/macros.py
@@ -157,6 +157,11 @@ macro TO_NUMBER_INLINE(arg) = (IS_NUMBER(%IS_VAR(arg)) ? arg : NonNumberToNumber
 macro TO_OBJECT_INLINE(arg) = (IS_SPEC_OBJECT(%IS_VAR(arg)) ? arg : ToObject(arg));
 macro JSON_NUMBER_TO_STRING(arg) = ((%_IsSmi(%IS_VAR(arg)) || arg - arg == 0) ? %_NumberToString(arg) : "null");
+# Constants.  The compiler constant folds them.
+const NAN = $NaN;
+const INFINITY = (1/0);
+const UNDEFINED = (void 0);
 # Macros implemented in Python.
 python macro CHAR_CODE(str) = ord(str[1]);

--- a/src/math.js
+++ b/src/math.js
@@ -131,9 +131,9 @@ function MathMax(arg1, arg2) {  // length == 2
      return (arg1 == 0 && !%_IsSmi(arg1) && 1 / arg1 < 0) ? arg2 : arg1;
    }
    // All comparisons failed, one of the arguments must be NaN.
-    return 0/0;  // Compiler constant-folds this to NaN.
+    return NAN;
  }
-  var r = -1/0;  // Compiler constant-folds this to -Infinity.
+  var r = -INFINITY;
  for (var i = 0; i < length; i++) {
    var n = %_Arguments(i);
    if (!IS_NUMBER(n)) n = NonNumberToNumber(n);
@@ -161,9 +161,9 @@ function MathMin(arg1, arg2) {  // length == 2
      return (arg1 == 0 && !%_IsSmi(arg1) && 1 / arg1 < 0) ? arg1 : arg2;
    }
    // All comparisons failed, one of the arguments must be NaN.
-    return 0/0;  // Compiler constant-folds this to NaN.
+    return NAN;
  }
-  var r = 1/0;  // Compiler constant-folds this to Infinity.
+  var r = INFINITY;
  for (var i = 0; i < length; i++) {
    var n = %_Arguments(i);
    if (!IS_NUMBER(n)) n = NonNumberToNumber(n);

--- a/src/messages.js
+++ b/src/messages.js
@@ -796,7 +796,7 @@ function CallSite(receiver, fun, pos, strict_mode) {
 }
 function CallSiteGetThis() {
-  return this[CallSiteStrictModeKey] ? void 0 : this[CallSiteReceiverKey];
+  return this[CallSiteStrictModeKey] ? UNDEFINED : this[CallSiteReceiverKey];
 }
 function CallSiteGetTypeName() {
@@ -826,7 +826,7 @@ function CallSiteGetScriptNameOrSourceURL() {
 }
 function CallSiteGetFunction() {
-  return this[CallSiteStrictModeKey] ? void 0 : this[CallSiteFunctionKey];
+  return this[CallSiteStrictModeKey] ? UNDEFINED : this[CallSiteFunctionKey];
 }
 function CallSiteGetFunctionName() {
@@ -1092,7 +1092,7 @@ function FormatStackTrace(obj, error_string, frames) {
    var array = [];
    %MoveArrayContents(frames, array);
    formatting_custom_stack_trace = true;
-    var stack_trace = void 0;
+    var stack_trace = UNDEFINED;
    try {
      stack_trace = $Error.prepareStackTrace(obj, array);
    } catch (e) {
@@ -1160,7 +1160,7 @@ function captureStackTrace(obj, cons_opt) {
    // Turn this accessor into a data property.
    %DefineOrRedefineDataProperty(obj, 'stack', result, NONE);
    // Release context values.
-    stack = error_string = void 0;
+    stack = error_string = UNDEFINED;
    return result;
  };
@@ -1171,7 +1171,7 @@ function captureStackTrace(obj, cons_opt) {
    %DefineOrRedefineDataProperty(this, 'stack', v, NONE);
    if (this === obj) {
      // Release context values if holder is the same as the receiver.
-      stack = error_string = void 0;
+      stack = error_string = UNDEFINED;
    }
  };
@@ -1213,7 +1213,7 @@ function SetUpError() {
        // Define all the expected properties directly on the error
        // object. This avoids going through getters and setters defined
        // on prototype objects.
-        %IgnoreAttributesAndSetProperty(this, 'stack', void 0, DONT_ENUM);
+        %IgnoreAttributesAndSetProperty(this, 'stack', UNDEFINED, DONT_ENUM);
        if (!IS_UNDEFINED(m)) {
          %IgnoreAttributesAndSetProperty(
            this, 'message', ToString(m), DONT_ENUM);
@@ -1251,7 +1251,7 @@ function GetPropertyWithoutInvokingMonkeyGetters(error, name) {
  while (error && !%HasLocalProperty(error, name)) {
    error = %GetPrototype(error);
  }
-  if (error === null) return void 0;
+  if (IS_NULL(error)) return UNDEFINED;
  if (!IS_OBJECT(error)) return error[name];
  // If the property is an accessor on one of the predefined errors that can be
  // generated statically by the compiler, don't touch it. This is to address
@@ -1260,11 +1260,11 @@ function GetPropertyWithoutInvokingMonkeyGetters(error, name) {
  if (desc && desc[IS_ACCESSOR_INDEX]) {
    var isName = name === "name";
    if (error === $ReferenceError.prototype)
-      return isName ? "ReferenceError" : void 0;
+      return isName ? "ReferenceError" : UNDEFINED;
    if (error === $SyntaxError.prototype)
-      return isName ? "SyntaxError" : void 0;
+      return isName ? "SyntaxError" : UNDEFINED;
    if (error === $TypeError.prototype)
-      return isName ? "TypeError" : void 0;
+      return isName ? "TypeError" : UNDEFINED;
  }
  // Otherwise, read normally.
  return error[name];

--- a/src/mirror-debugger.js
+++ b/src/mirror-debugger.js
@@ -117,7 +117,7 @@ function LookupMirror(handle) {
 * @returns {Mirror} the mirror reflects the undefined value
 */
 function GetUndefinedMirror() {
-  return MakeMirror(void 0);
+  return MakeMirror(UNDEFINED);
 }
@@ -482,7 +482,7 @@ ValueMirror.prototype.value = function() {
 * @extends ValueMirror
 */
 function UndefinedMirror() {
-  %_CallFunction(this, UNDEFINED_TYPE, void 0, ValueMirror);
+  %_CallFunction(this, UNDEFINED_TYPE, UNDEFINED, ValueMirror);
 }
 inherits(UndefinedMirror, ValueMirror);
@@ -957,7 +957,7 @@ FunctionMirror.prototype.scopeCount = function() {
 FunctionMirror.prototype.scope = function(index) {
  if (this.resolved()) {
-    return new ScopeMirror(void 0, this, index);
+    return new ScopeMirror(UNDEFINED, this, index);
  }
 };
@@ -1670,7 +1670,7 @@ FrameMirror.prototype.scopeCount = function() {
 FrameMirror.prototype.scope = function(index) {
-  return new ScopeMirror(this, void 0, index);
+  return new ScopeMirror(this, UNDEFINED, index);
 };

--- a/src/object-observe.js
+++ b/src/object-observe.js
@@ -72,12 +72,12 @@ function ObservationWeakMap(map) {
 ObservationWeakMap.prototype = {
  get: function(key) {
    key = %UnwrapGlobalProxy(key);
-    if (!IS_SPEC_OBJECT(key)) return void 0;
+    if (!IS_SPEC_OBJECT(key)) return UNDEFINED;
    return %WeakCollectionGet(this.map_, key);
  },
  set: function(key, value) {
    key = %UnwrapGlobalProxy(key);
-    if (!IS_SPEC_OBJECT(key)) return void 0;
+    if (!IS_SPEC_OBJECT(key)) return UNDEFINED;
    %WeakCollectionSet(this.map_, key, value);
  },
  has: function(key) {
@@ -492,7 +492,7 @@ function ObjectNotifierPerformChange(changeType, changeFn) {
  ObjectInfoAddPerformingType(objectInfo, changeType);
  try {
-    %_CallFunction(void 0, changeFn);
+    %_CallFunction(UNDEFINED, changeFn);
  } finally {
    ObjectInfoRemovePerformingType(objectInfo, changeType);
  }
@@ -525,7 +525,7 @@ function CallbackDeliverPending(callback) {
  %MoveArrayContents(callbackInfo, delivered);
  try {
-    %_CallFunction(void 0, delivered, callback);
+    %_CallFunction(UNDEFINED, delivered, callback);
  } catch (ex) {}
  return true;
 }

--- a/src/proxy.js
+++ b/src/proxy.js
@@ -40,7 +40,7 @@ function ProxyCreate(handler, proto) {
    throw MakeTypeError("handler_non_object", ["create"])
  if (IS_UNDEFINED(proto))
    proto = null
-  else if (!(IS_SPEC_OBJECT(proto) || proto === null))
+  else if (!(IS_SPEC_OBJECT(proto) || IS_NULL(proto)))
    throw MakeTypeError("proto_non_object", ["create"])
  return %CreateJSProxy(handler, proto)
 }
@@ -56,7 +56,7 @@ function ProxyCreateFunction(handler, callTrap, constructTrap) {
    // Make sure the trap receives 'undefined' as this.
    var construct = constructTrap
    constructTrap = function() {
-      return %Apply(construct, void 0, arguments, 0, %_ArgumentsLength());
+      return %Apply(construct, UNDEFINED, arguments, 0, %_ArgumentsLength());
    }
  } else {
    throw MakeTypeError("trap_function_expected",

--- a/src/regexp.js
+++ b/src/regexp.js
@@ -189,7 +189,7 @@ function RegExpExec(string) {
  // matchIndices is either null or the lastMatchInfo array.
  var matchIndices = %_RegExpExec(this, string, i, lastMatchInfo);
-  if (matchIndices === null) {
+  if (IS_NULL(matchIndices)) {
    this.lastIndex = 0;
    return null;
  }
@@ -232,7 +232,7 @@ function RegExpTest(string) {
    %_Log('regexp', 'regexp-exec,%0r,%1S,%2i', [this, string, lastIndex]);
    // matchIndices is either null or the lastMatchInfo array.
    var matchIndices = %_RegExpExec(this, string, i, lastMatchInfo);
-    if (matchIndices === null) {
+    if (IS_NULL(matchIndices)) {
      this.lastIndex = 0;
      return false;
    }
@@ -253,7 +253,7 @@ function RegExpTest(string) {
    %_Log('regexp', 'regexp-exec,%0r,%1S,%2i', [regexp, string, lastIndex]);
    // matchIndices is either null or the lastMatchInfo array.
    var matchIndices = %_RegExpExec(regexp, string, 0, lastMatchInfo);
-    if (matchIndices === null) {
+    if (IS_NULL(matchIndices)) {
      this.lastIndex = 0;
      return false;
    }
@@ -384,7 +384,7 @@ function RegExpMakeCaptureGetter(n) {
 var lastMatchInfo = new InternalPackedArray(
    2,                 // REGEXP_NUMBER_OF_CAPTURES
    "",                // Last subject.
-    void 0,            // Last input - settable with RegExpSetInput.
+    UNDEFINED,         // Last input - settable with RegExpSetInput.
    0,                 // REGEXP_FIRST_CAPTURE + 0
    0                  // REGEXP_FIRST_CAPTURE + 1
 );

--- a/src/runtime.js
+++ b/src/runtime.js
@@ -526,8 +526,8 @@ function ToNumber(x) {
                                    : %StringToNumber(x);
  }
  if (IS_BOOLEAN(x)) return x ? 1 : 0;
-  if (IS_UNDEFINED(x)) return $NaN;
+  if (IS_UNDEFINED(x)) return NAN;
-  if (IS_SYMBOL(x)) return $NaN;
+  if (IS_SYMBOL(x)) return NAN;
  return (IS_NULL(x)) ? 0 : ToNumber(%DefaultNumber(x));
 }
@@ -537,8 +537,8 @@ function NonNumberToNumber(x) {
                                    : %StringToNumber(x);
  }
  if (IS_BOOLEAN(x)) return x ? 1 : 0;
-  if (IS_UNDEFINED(x)) return $NaN;
+  if (IS_UNDEFINED(x)) return NAN;
-  if (IS_SYMBOL(x)) return $NaN;
+  if (IS_SYMBOL(x)) return NAN;
  return (IS_NULL(x)) ? 0 : ToNumber(%DefaultNumber(x));
 }

--- a/src/string.js
+++ b/src/string.js
@@ -28,7 +28,6 @@
 // This file relies on the fact that the following declaration has been made
 // in runtime.js:
 // var $String = global.String;
-// var $NaN = 0/0;
 // -------------------------------------------------------------------
@@ -574,7 +573,7 @@ function StringSlice(start, end) {
  var s_len = s.length;
  var start_i = TO_INTEGER(start);
  var end_i = s_len;
-  if (end !== void 0) {
+  if (!IS_UNDEFINED(end)) {
    end_i = TO_INTEGER(end);
  }
@@ -699,7 +698,7 @@ function StringSplitOnRegExp(subject, separator, limit, length) {
        %_CallFunction(result, %_SubString(subject, start, end),
                       ArrayPushBuiltin);
      } else {
-        %_CallFunction(result, void 0, ArrayPushBuiltin);
+        %_CallFunction(result, UNDEFINED, ArrayPushBuiltin);
      }
      if (result.length === limit) break outer_loop;
    }
@@ -756,7 +755,7 @@ function StringSubstr(start, n) {
  // Correct n: If not given, set to string length; if explicitly
  // set to undefined, zero, or negative, returns empty string.
-  if (n === void 0) {
+  if (IS_UNDEFINED(n)) {
    len = s.length;
  } else {
    len = TO_INTEGER(n);
@@ -765,7 +764,7 @@ function StringSubstr(start, n) {
  // Correct start: If not given (or undefined), set to zero; otherwise
  // convert to integer and handle negative case.
-  if (start === void 0) {
+  if (IS_UNDEFINED(start)) {
    start = 0;
  } else {
    start = TO_INTEGER(start);

--- a/src/v8natives.js
+++ b/src/v8natives.js
@@ -32,7 +32,6 @@
 // var $Number = global.Number;
 // var $Function = global.Function;
 // var $Array = global.Array;
-// var $NaN = 0/0;
 //
 // in math.js:
 // var $floor = MathFloor
@@ -95,7 +94,7 @@ function SetUpLockedPrototype(constructor, fields, methods) {
  }
  if (fields) {
    for (var i = 0; i < fields.length; i++) {
-      %SetProperty(prototype, fields[i], void 0, DONT_ENUM | DONT_DELETE);
+      %SetProperty(prototype, fields[i], UNDEFINED, DONT_ENUM | DONT_DELETE);
    }
  }
  for (var i = 0; i < methods.length; i += 2) {
@@ -148,7 +147,7 @@ function GlobalParseInt(string, radix) {
    string = TO_STRING_INLINE(string);
    radix = TO_INT32(radix);
    if (!(radix == 0 || (2 <= radix && radix <= 36))) {
-      return $NaN;
+      return NAN;
    }
  }
@@ -197,15 +196,16 @@ function GlobalEval(x) {
 function SetUpGlobal() {
  %CheckIsBootstrapping();
+  var attributes = DONT_ENUM | DONT_DELETE | READ_ONLY;
  // ECMA 262 - 15.1.1.1.
-  %SetProperty(global, "NaN", $NaN, DONT_ENUM | DONT_DELETE | READ_ONLY);
+  %SetProperty(global, "NaN", NAN, attributes);
  // ECMA-262 - 15.1.1.2.
-  %SetProperty(global, "Infinity", 1/0, DONT_ENUM | DONT_DELETE | READ_ONLY);
+  %SetProperty(global, "Infinity", INFINITY, attributes);
  // ECMA-262 - 15.1.1.3.
-  %SetProperty(global, "undefined", void 0,
+  %SetProperty(global, "undefined", UNDEFINED, attributes);
-               DONT_ENUM | DONT_DELETE | READ_ONLY);
  // Set up non-enumerable function on the global object.
  InstallFunctions(global, DONT_ENUM, $Array(
@@ -475,12 +475,12 @@ function ToPropertyDescriptor(obj) {
 function ToCompletePropertyDescriptor(obj) {
  var desc = ToPropertyDescriptor(obj);
  if (IsGenericDescriptor(desc) || IsDataDescriptor(desc)) {
-    if (!desc.hasValue()) desc.setValue(void 0);
+    if (!desc.hasValue()) desc.setValue(UNDEFINED);
    if (!desc.hasWritable()) desc.setWritable(false);
  } else {
    // Is accessor descriptor.
-    if (!desc.hasGetter()) desc.setGet(void 0);
+    if (!desc.hasGetter()) desc.setGet(UNDEFINED);
-    if (!desc.hasSetter()) desc.setSet(void 0);
+    if (!desc.hasSetter()) desc.setSet(UNDEFINED);
  }
  if (!desc.hasEnumerable()) desc.setEnumerable(false);
  if (!desc.hasConfigurable()) desc.setConfigurable(false);
@@ -491,7 +491,7 @@ function ToCompletePropertyDescriptor(obj) {
 function PropertyDescriptor() {
  // Initialize here so they are all in-object and have the same map.
  // Default values from ES5 8.6.1.
-  this.value_ = void 0;
+  this.value_ = UNDEFINED;
  this.hasValue_ = false;
  this.writable_ = false;
  this.hasWritable_ = false;
@@ -499,9 +499,9 @@ function PropertyDescriptor() {
  this.hasEnumerable_ = false;
  this.configurable_ = false;
  this.hasConfigurable_ = false;
-  this.get_ = void 0;
+  this.get_ = UNDEFINED;
  this.hasGetter_ = false;
-  this.set_ = void 0;
+  this.set_ = UNDEFINED;
  this.hasSetter_ = false;
 }
@@ -593,7 +593,7 @@ function ConvertDescriptorArrayToDescriptor(desc_array) {
  }
  if (IS_UNDEFINED(desc_array)) {
-    return void 0;
+    return UNDEFINED;
  }
  var desc = new PropertyDescriptor();
@@ -647,10 +647,11 @@ function GetOwnProperty(obj, v) {
  var p = ToName(v);
  if (%IsJSProxy(obj)) {
    // TODO(rossberg): adjust once there is a story for symbols vs proxies.
-    if (IS_SYMBOL(v)) return void 0;
+    if (IS_SYMBOL(v)) return UNDEFINED;
    var handler = %GetHandler(obj);
-    var descriptor = CallTrap1(handler, "getOwnPropertyDescriptor", void 0, p);
+    var descriptor = CallTrap1(
+                         handler, "getOwnPropertyDescriptor", UNDEFINED, p);
    if (IS_UNDEFINED(descriptor)) return descriptor;
    var desc = ToCompletePropertyDescriptor(descriptor);
    if (!desc.isConfigurable()) {
@@ -666,7 +667,7 @@ function GetOwnProperty(obj, v) {
  var props = %GetOwnProperty(ToObject(obj), p);
  // A false value here means that access checks failed.
-  if (props === false) return void 0;
+  if (props === false) return UNDEFINED;
  return ConvertDescriptorArrayToDescriptor(props);
 }
@@ -693,7 +694,7 @@ function DefineProxyProperty(obj, p, attributes, should_throw) {
  if (IS_SYMBOL(p)) return false;
  var handler = %GetHandler(obj);
-  var result = CallTrap2(handler, "defineProperty", void 0, p, attributes);
+  var result = CallTrap2(handler, "defineProperty", UNDEFINED, p, attributes);
  if (!ToBoolean(result)) {
    if (should_throw) {
      throw MakeTypeError("handler_returned_false",
@@ -710,7 +711,7 @@ function DefineProxyProperty(obj, p, attributes, should_throw) {
 function DefineObjectProperty(obj, p, desc, should_throw) {
  var current_or_access = %GetOwnProperty(ToObject(obj), ToName(p));
  // A false value here means that access checks failed.
-  if (current_or_access === false) return void 0;
+  if (current_or_access === false) return UNDEFINED;
  var current = ConvertDescriptorArrayToDescriptor(current_or_access);
  var extensible = %IsExtensible(ToObject(obj));
@@ -841,7 +842,7 @@ function DefineObjectProperty(obj, p, desc, should_throw) {
      flag |= READ_ONLY;
    }
-    var value = void 0;  // Default value is undefined.
+    var value = UNDEFINED;  // Default value is undefined.
    if (desc.hasValue()) {
      value = desc.getValue();
    } else if (!IS_UNDEFINED(current) && IsDataDescriptor(current)) {
@@ -920,7 +921,7 @@ function DefineArrayProperty(obj, p, desc, should_throw) {
    // For the time being, we need a hack to prevent Object.observe from
    // generating two change records.
    obj.length = new_length;
-    desc.value_ = void 0;
+    desc.value_ = UNDEFINED;
    desc.hasValue_ = false;
    threw = !DefineObjectProperty(obj, "length", desc, should_throw) || threw;
    if (emit_splice) {
@@ -1045,7 +1046,7 @@ function ObjectGetOwnPropertyNames(obj) {
  // Special handling for proxies.
  if (%IsJSProxy(obj)) {
    var handler = %GetHandler(obj);
-    var names = CallTrap0(handler, "getOwnPropertyNames", void 0);
+    var names = CallTrap0(handler, "getOwnPropertyNames", UNDEFINED);
    return ToNameArray(names, "getOwnPropertyNames", false);
  }
@@ -1194,7 +1195,7 @@ function ObjectDefineProperties(obj, properties) {
 // Harmony proxies.
 function ProxyFix(obj) {
  var handler = %GetHandler(obj);
-  var props = CallTrap0(handler, "fix", void 0);
+  var props = CallTrap0(handler, "fix", UNDEFINED);
  if (IS_UNDEFINED(props)) {
    throw MakeTypeError("handler_returned_undefined", [handler, "fix"]);
  }
@@ -1560,8 +1561,8 @@ function NumberToFixed(fractionDigits) {
  }
  if (NUMBER_IS_NAN(x)) return "NaN";
-  if (x == 1/0) return "Infinity";
+  if (x == INFINITY) return "Infinity";
-  if (x == -1/0) return "-Infinity";
+  if (x == -INFINITY) return "-Infinity";
  return %NumberToFixed(x, f);
 }
@@ -1578,11 +1579,11 @@ function NumberToExponential(fractionDigits) {
    // Get the value of this number in case it's an object.
    x = %_ValueOf(this);
  }
-  var f = IS_UNDEFINED(fractionDigits) ? void 0 : TO_INTEGER(fractionDigits);
+  var f = IS_UNDEFINED(fractionDigits) ? UNDEFINED : TO_INTEGER(fractionDigits);
  if (NUMBER_IS_NAN(x)) return "NaN";
-  if (x == 1/0) return "Infinity";
+  if (x == INFINITY) return "Infinity";
-  if (x == -1/0) return "-Infinity";
+  if (x == -INFINITY) return "-Infinity";
  if (IS_UNDEFINED(f)) {
    f = -1;  // Signal for runtime function that f is not defined.
@@ -1608,8 +1609,8 @@ function NumberToPrecision(precision) {
  var p = TO_INTEGER(precision);
  if (NUMBER_IS_NAN(x)) return "NaN";
-  if (x == 1/0) return "Infinity";
+  if (x == INFINITY) return "Infinity";
-  if (x == -1/0) return "-Infinity";
+  if (x == -INFINITY) return "-Infinity";
  if (p < 1 || p > 21) {
    throw new $RangeError("toPrecision() argument must be between 1 and 21");
@@ -1654,18 +1655,18 @@ function SetUpNumber() {
               DONT_ENUM | DONT_DELETE | READ_ONLY);
  // ECMA-262 section 15.7.3.3.
-  %SetProperty($Number, "NaN", $NaN, DONT_ENUM | DONT_DELETE | READ_ONLY);
+  %SetProperty($Number, "NaN", NAN, DONT_ENUM | DONT_DELETE | READ_ONLY);
  // ECMA-262 section 15.7.3.4.
  %SetProperty($Number,
               "NEGATIVE_INFINITY",
-               -1/0,
+               -INFINITY,
               DONT_ENUM | DONT_DELETE | READ_ONLY);
  // ECMA-262 section 15.7.3.5.
  %SetProperty($Number,
               "POSITIVE_INFINITY",
-               1/0,
+               INFINITY,
               DONT_ENUM | DONT_DELETE | READ_ONLY);
  %ToFastProperties($Number);