Version 2.2.0.
Fixed a few minor bugs.
Performance improvements for string operations.
git-svn-id: http://v8.googlecode.com/svn/trunk@4302 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
diff --git a/src/heap.cc b/src/heap.cc
index 1f1599a..5421dcc 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -1961,8 +1961,9 @@
return MakeOrFindTwoCharacterString(c1, c2);
}
- bool is_ascii = first->IsAsciiRepresentation()
- && second->IsAsciiRepresentation();
+ bool first_is_ascii = first->IsAsciiRepresentation();
+ bool second_is_ascii = second->IsAsciiRepresentation();
+ bool is_ascii = first_is_ascii && second_is_ascii;
// Make sure that an out of memory exception is thrown if the length
// of the new cons string is too large.
@@ -1997,6 +1998,25 @@
for (int i = 0; i < second_length; i++) *dest++ = src[i];
return result;
} else {
+ // For short external two-byte strings we check whether they can
+ // be represented using ascii.
+ if (!first_is_ascii) {
+ first_is_ascii = first->IsExternalTwoByteStringWithAsciiChars();
+ }
+ if (first_is_ascii && !second_is_ascii) {
+ second_is_ascii = second->IsExternalTwoByteStringWithAsciiChars();
+ }
+ if (first_is_ascii && second_is_ascii) {
+ Object* result = AllocateRawAsciiString(length);
+ if (result->IsFailure()) return result;
+ // Copy the characters into the new object.
+ char* dest = SeqAsciiString::cast(result)->GetChars();
+ String::WriteToFlat(first, dest, 0, first_length);
+ String::WriteToFlat(second, dest + first_length, 0, second_length);
+ Counters::string_add_runtime_ext_to_ascii.Increment();
+ return result;
+ }
+
Object* result = AllocateRawTwoByteString(length);
if (result->IsFailure()) return result;
// Copy the characters into the new object.