Clean up is-ASCII checks.

src/heap.cc

Index: src/heap.cc
diff --git a/src/heap.cc b/src/heap.cc
index 2f70ef0188dbad295cb44622708e2dec3c4a4b24..4713f69e2f0e622b9e2ec9db99a28d24ef148ce5 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -2549,20 +2549,10 @@ MaybeObject* Heap::AllocateExternalStringFromTwoByte(
   }
 
   // For small strings we check whether the resource contains only
-  // ascii characters.  If yes, we use a different string map.
-  bool is_ascii = true;
-  if (length >= static_cast<size_t>(String::kMinNonFlatLength)) {
-    is_ascii = false;
-  } else {
-    const uc16* data = resource->data();
-    for (size_t i = 0; i < length; i++) {
-      if (data[i] > String::kMaxAsciiCharCode) {
-        is_ascii = false;
-        break;
-      }
-    }
-  }
-
+  // ASCII characters.  If yes, we use a different string map.
+  static const size_t kAsciiCheckLengthLimit = 32;
+  bool is_ascii = length <= kAsciiCheckLengthLimit &&
+                  String::IsAscii(resource->data(), length);

[Mads Ager (chromium), 2010/12/22 07:46:24]

Four-space indent?

   Map* map = is_ascii ?
       Heap::external_string_with_ascii_data_map() : Heap::external_string_map();
   Object* result;
@@ -3342,11 +3332,8 @@ MaybeObject* Heap::AllocateStringFromUtf8Slow(Vector<const char> string,
 MaybeObject* Heap::AllocateStringFromTwoByte(Vector<const uc16> string,
                                              PretenureFlag pretenure) {
   // Check if the string is an ASCII string.
-  int i = 0;
-  while (i < string.length() && string[i] <= String::kMaxAsciiCharCode) i++;
-
   MaybeObject* maybe_result;
-  if (i == string.length()) {  // It's an ASCII string.
+  if (String::IsAscii(string.start(), string.length())) {
     maybe_result = AllocateRawAsciiString(string.length(), pretenure);
   } else {  // It's not an ASCII string.
     maybe_result = AllocateRawTwoByteString(string.length(), pretenure);