Optimize int.parse with a radix.

runtime/lib/string_patch.dart

Index: runtime/lib/string_patch.dart
diff --git a/runtime/lib/string_patch.dart b/runtime/lib/string_patch.dart
index 9a454b114da22988e9e3ccbb692b605011f8ea72..deb5fcf161410224d29ca5ef2cfc6d68399fc668 100644
--- a/runtime/lib/string_patch.dart
+++ b/runtime/lib/string_patch.dart
@@ -260,12 +260,13 @@ class _StringBase {
       native "StringBase_substringUnchecked";
 
   // Checks for one-byte whitespaces only.
-  static bool _isOneByteWhitespace(int codePoint) {
-    return
-      (codePoint == 32) || // Space.
-      ((codePoint <= 13) ? (9 <= codePoint)  // CR, LF, TAB, etc.
-                         : ((codePoint == 0x85) ||  // NEL
-                            (codePoint == 0xA0)));  // NBSP
+  static bool _isOneByteWhitespace(int codeUnit) {
+    if (codeUnit <= 32) {
+      return ((codeUnit == 32) || // Space.
+              ((codeUnit <= 13) && (codeUnit >= 9)));  // CR, LF, TAB, etc.
+    }
+    if (codeUnit < 0x85) return false;

[srdjan, 2014/09/24 20:05:35]

Is that check worth it? With two below you have three checks instead of two and
more complex code.

[Lasse Reichstein Nielsen, 2014/09/24 20:26:30]

Ack, probably not for the one-byte case. I copied it from the two-byte case
where it's guarding a much more complex test.

[Lasse Reichstein Nielsen, 2014/09/25 14:37:16]

Fixed.
Any chance of optimizing so that (codeunit < 0x85) followed by (codeunit ==
0x85) always boils down to one compare instruction? :)

+    return (codeUnit == 0x85) || (codeUnit == 0xA0);
   }
 
   // Characters with Whitespace property (Unicode 6.2).
@@ -284,7 +285,12 @@ class _StringBase {
   //
   // BOM: 0xFEFF
   static bool _isTwoByteWhitespace(int codeUnit) {
-    if (codeUnit <= 0xA0) return _isOneByteWhitespace(codeUnit);
+    if (codeUnit <= 32) {
+      return (codeUnit == 32) ||
+             ((codeUnit <= 13) && (codeUnit >= 9));
+    }
+    if (codeUnit < 0x85) return false;
+    if ((codeUnit == 0x85) || (codeUnit == 0xA0)) return true;
     return (codeUnit <= 0x200A)
             ? ((codeUnit == 0x1680) ||
                (codeUnit == 0x180E) ||