Parsing some kinds of integers and junk values in Runtime_NumberToString. For...

Parsing some kinds of integers and junk values in Runtime_NumberToString. For that values the string is converted into int and then into SMI. It lets to avoid floating point operations.


Committed: http://code.google.com/p/v8/source/detail?r=4331
Review URL: http://codereview.chromium.org/1572004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4339 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/runtime.cc

@@ -4482,7 +4482,9 @@ static Object* Runtime_StringToNumber(Arguments args) {
     bool minus = (data[0] == '-');
     int start_pos = (minus ? 1 : 0);
 
-    if (start_pos == len || data[start_pos] > '9') {
+    if (start_pos == len) {
+      return Heap::nan_value();
+    } else if (data[start_pos] > '9') {
       // Fast check for a junk value. A valid string may start from a
       // whitespace, a sign ('+' or '-'), the decimal point, a decimal digit or
       // the 'I' character ('Infinity'). All of that have codes not greater than