Make the runtime entry for setting/changing accessors "atomic".

src/regexp.js

-// Copyright 2006-2009 the V8 project authors. All rights reserved.
+// 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
 //       with the distribution.
@@ skipping 402 matching lines @@
   // value is set the value it is set to is coerced to a string.
   // Getter and setter for the input.
   var RegExpGetInput = function() {
     var regExpInput = LAST_INPUT(lastMatchInfo);
     return IS_UNDEFINED(regExpInput) ? "" : regExpInput;
   };
   var RegExpSetInput = function(string) {
     LAST_INPUT(lastMatchInfo) = ToString(string);
   };
 
-  %DefineOrRedefineAccessorProperty($RegExp, 'input', GETTER, RegExpGetInput,
-                                    DONT_DELETE);
-  %DefineOrRedefineAccessorProperty($RegExp, 'input', SETTER, RegExpSetInput,
-                                    DONT_DELETE);
-  %DefineOrRedefineAccessorProperty($RegExp, '$_', GETTER, RegExpGetInput,
-                                    DONT_ENUM | DONT_DELETE);
-  %DefineOrRedefineAccessorProperty($RegExp, '$_', SETTER, RegExpSetInput,
-                                    DONT_ENUM | DONT_DELETE);
-  %DefineOrRedefineAccessorProperty($RegExp, '$input', GETTER, RegExpGetInput,
-                                    DONT_ENUM | DONT_DELETE);
-  %DefineOrRedefineAccessorProperty($RegExp, '$input', SETTER, RegExpSetInput,
-                                    DONT_ENUM | DONT_DELETE);
+  %DefineOrRedefineAccessorProperty($RegExp, 'input', RegExpGetInput,
+                                    RegExpSetInput, DONT_DELETE);
+  %DefineOrRedefineAccessorProperty($RegExp, '$_', RegExpGetInput,
+                                    RegExpSetInput, DONT_ENUM | DONT_DELETE);
+  %DefineOrRedefineAccessorProperty($RegExp, '$input', RegExpGetInput,
+                                    RegExpSetInput, DONT_ENUM | DONT_DELETE);
 
   // The properties multiline and $* are aliases for each other.  When this
   // value is set in SpiderMonkey, the value it is set to is coerced to a
   // boolean.  We mimic that behavior with a slight difference: in SpiderMonkey
   // the value of the expression 'RegExp.multiline = null' (for instance) is the
   // boolean false (i.e., the value after coercion), while in V8 it is the value
   // null (i.e., the value before coercion).
 
   // Getter and setter for multiline.
   var multiline = false;
   var RegExpGetMultiline = function() { return multiline; };
   var RegExpSetMultiline = function(flag) { multiline = flag ? true : false; };
 
-  %DefineOrRedefineAccessorProperty($RegExp, 'multiline', GETTER,
-                                    RegExpGetMultiline, DONT_DELETE);
-  %DefineOrRedefineAccessorProperty($RegExp, 'multiline', SETTER,
+  %DefineOrRedefineAccessorProperty($RegExp, 'multiline', RegExpGetMultiline,
                                     RegExpSetMultiline, DONT_DELETE);
-  %DefineOrRedefineAccessorProperty($RegExp, '$*', GETTER, RegExpGetMultiline,
-                                    DONT_ENUM | DONT_DELETE);
-  %DefineOrRedefineAccessorProperty($RegExp, '$*', SETTER, RegExpSetMultiline,
+  %DefineOrRedefineAccessorProperty($RegExp, '$*', RegExpGetMultiline,
+                                    RegExpSetMultiline,
                                     DONT_ENUM | DONT_DELETE);
 
 
   var NoOpSetter = function(ignored) {};
 
 
   // Static properties set by a successful match.
-  %DefineOrRedefineAccessorProperty($RegExp, 'lastMatch', GETTER,
-                                    RegExpGetLastMatch, DONT_DELETE);
-  %DefineOrRedefineAccessorProperty($RegExp, 'lastMatch', SETTER, NoOpSetter,
+  %DefineOrRedefineAccessorProperty($RegExp, 'lastMatch', RegExpGetLastMatch,
+                                    NoOpSetter, DONT_DELETE);
+  %DefineOrRedefineAccessorProperty($RegExp, '$&', RegExpGetLastMatch,
+                                    NoOpSetter, DONT_ENUM | DONT_DELETE);
+  %DefineOrRedefineAccessorProperty($RegExp, 'lastParen', RegExpGetLastParen,
+                                    NoOpSetter, DONT_DELETE);
+  %DefineOrRedefineAccessorProperty($RegExp, '$+', RegExpGetLastParen,
+                                    NoOpSetter, DONT_ENUM | DONT_DELETE);
+  %DefineOrRedefineAccessorProperty($RegExp, 'leftContext',
+                                    RegExpGetLeftContext, NoOpSetter,
                                     DONT_DELETE);
-  %DefineOrRedefineAccessorProperty($RegExp, '$&', GETTER, RegExpGetLastMatch,
-                                    DONT_ENUM | DONT_DELETE);
-  %DefineOrRedefineAccessorProperty($RegExp, '$&', SETTER, NoOpSetter,
-                                    DONT_ENUM | DONT_DELETE);
-  %DefineOrRedefineAccessorProperty($RegExp, 'lastParen', GETTER,
-                                    RegExpGetLastParen, DONT_DELETE);
-  %DefineOrRedefineAccessorProperty($RegExp, 'lastParen', SETTER, NoOpSetter,
+  %DefineOrRedefineAccessorProperty($RegExp, '$`', RegExpGetLeftContext,
+                                    NoOpSetter, DONT_ENUM | DONT_DELETE);
+  %DefineOrRedefineAccessorProperty($RegExp, 'rightContext',
+                                    RegExpGetRightContext, NoOpSetter,
                                     DONT_DELETE);
-  %DefineOrRedefineAccessorProperty($RegExp, '$+', GETTER, RegExpGetLastParen,
-                                    DONT_ENUM | DONT_DELETE);
-  %DefineOrRedefineAccessorProperty($RegExp, '$+', SETTER, NoOpSetter,
-                                    DONT_ENUM | DONT_DELETE);
-  %DefineOrRedefineAccessorProperty($RegExp, 'leftContext', GETTER,
-                                    RegExpGetLeftContext, DONT_DELETE);
-  %DefineOrRedefineAccessorProperty($RegExp, 'leftContext', SETTER, NoOpSetter,
-                                    DONT_DELETE);
-  %DefineOrRedefineAccessorProperty($RegExp, '$`', GETTER, RegExpGetLeftContext,
-                                    DONT_ENUM | DONT_DELETE);
-  %DefineOrRedefineAccessorProperty($RegExp, '$`', SETTER, NoOpSetter,
-                                    DONT_ENUM | DONT_DELETE);
-  %DefineOrRedefineAccessorProperty($RegExp, 'rightContext', GETTER,
-                                    RegExpGetRightContext, DONT_DELETE);
-  %DefineOrRedefineAccessorProperty($RegExp, 'rightContext', SETTER, NoOpSetter,
-                                    DONT_DELETE);
-  %DefineOrRedefineAccessorProperty($RegExp, "$'", GETTER,
-                                    RegExpGetRightContext,
-                                    DONT_ENUM | DONT_DELETE);
-  %DefineOrRedefineAccessorProperty($RegExp, "$'", SETTER, NoOpSetter,
-                                    DONT_ENUM | DONT_DELETE);
+  %DefineOrRedefineAccessorProperty($RegExp, "$'", RegExpGetRightContext,
+                                    NoOpSetter, DONT_ENUM | DONT_DELETE);
 
   for (var i = 1; i < 10; ++i) {
-    %DefineOrRedefineAccessorProperty($RegExp, '$' + i, GETTER,
-                                      RegExpMakeCaptureGetter(i), DONT_DELETE);
-    %DefineOrRedefineAccessorProperty($RegExp, '$' + i, SETTER, NoOpSetter,
+    %DefineOrRedefineAccessorProperty($RegExp, '$' + i,
+                                      RegExpMakeCaptureGetter(i), NoOpSetter,
                                       DONT_DELETE);
   }
 }
 
 SetUpRegExp();