Callers of Heap::AllocateStringFromOneByte() and Heap::AllocateStringFromUtf8() handlified.

src/factory.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "factory.h"
 
 #include "macro-assembler.h"
 #include "isolate-inl.h"
 #include "v8conversions.h"
 
@@ skipping 263 matching lines @@
 Handle<String> Factory::NewStringFromOneByte(Vector<const uint8_t> string,
                                              PretenureFlag pretenure) {
   CALL_HEAP_FUNCTION(
       isolate(),
       isolate()->heap()->AllocateStringFromOneByte(string, pretenure),
       String);
 }
 
 Handle<String> Factory::NewStringFromUtf8(Vector<const char> string,
                                           PretenureFlag pretenure) {
+  // Check for ASCII first since this is the common case.
+  const char* start = string.start();
+  int length = string.length();
+  int non_ascii_start = String::NonAsciiStart(start, length);
+  if (non_ascii_start >= length) {
+    // If the string is ASCII, we do not need to convert the characters
+    // since UTF8 is backwards compatible with ASCII.
+    return NewStringFromOneByte(Vector<const uint8_t>::cast(string), pretenure);
+  }
+  // Non-ASCII and we need to decode.
   CALL_HEAP_FUNCTION(
       isolate(),
-      isolate()->heap()->AllocateStringFromUtf8(string, pretenure),
+      isolate()->heap()->AllocateStringFromUtf8Slow(string,
+                                                    non_ascii_start,
+                                                    pretenure),
       String);
 }
 
 
 Handle<String> Factory::NewStringFromTwoByte(Vector<const uc16> string,
                                              PretenureFlag pretenure) {
   CALL_HEAP_FUNCTION(
       isolate(),
       isolate()->heap()->AllocateStringFromTwoByte(string, pretenure),
       String);
@@ skipping 2033 matching lines @@
   if (String::Equals(name, infinity_string())) return infinity_value();
   return Handle<Object>::null();
 }
 
 
 Handle<Object> Factory::ToBoolean(bool value) {
   return value ? true_value() : false_value();
 }
 
 } }  // namespace v8::internal