Improve performance of Onebytestring allocation and hascode computatio. About 10% improvement on a …

runtime/vm/object.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/bigint_operations.h"
@@ skipping 10481 matching lines @@
  private:
   uint32_t hash_;
 };
 
 
 intptr_t String::Hash(const String& str, intptr_t begin_index, intptr_t len) {
   ASSERT(begin_index >= 0);
   ASSERT(len >= 0);
   ASSERT((begin_index + len) <= str.Length());
   StringHasher hasher;
-  CodePointIterator it(str, begin_index, len);
-  while (it.Next()) {
-    hasher.Add(it.Current());
+  if (str.IsOneByteString()) {
+    for (intptr_t i = 0; i < len; i++) {
+      hasher.Add(*OneByteString::CharAddr(str, i + begin_index));
+    }
+  } else {
+    CodePointIterator it(str, begin_index, len);
+    while (it.Next()) {
+      hasher.Add(it.Current());
+    }
   }
   return hasher.Finalize(String::kHashBits);
 }
 
 
 template<typename T>
 static intptr_t HashImpl(const T* characters, intptr_t len) {
   ASSERT(len >= 0);
   StringHasher hasher;
   for (intptr_t i = 0; i < len; i++) {
@@ skipping 825 matching lines @@
 
 RawOneByteString* OneByteString::New(intptr_t len,
                                      Heap::Space space) {
   ASSERT(Isolate::Current() == Dart::vm_isolate() ||
          Isolate::Current()->object_store()->one_byte_string_class() !=
          Class::null());
   if (len < 0 || len > kMaxElements) {
     // This should be caught before we reach here.
     FATAL1("Fatal error in OneByteString::New: invalid len %"Pd"\n", len);
   }
-  String& result = String::Handle();
   {
     RawObject* raw = Object::Allocate(OneByteString::kClassId,
                                       OneByteString::InstanceSize(len),
                                       space);
     NoGCScope no_gc;
-    result ^= raw;
-    result.SetLength(len);
-    result.SetHash(0);
+    RawOneByteString* result = reinterpret_cast<RawOneByteString*>(raw);
+    result->ptr()->length_ = Smi::New(len);
+    result->ptr()->hash_ = 0;
+    return result;
   }
-  return OneByteString::raw(result);
 }
 
 
 RawOneByteString* OneByteString::New(const uint8_t* characters,
                                      intptr_t len,
                                      Heap::Space space) {
   const String& result = String::Handle(OneByteString::New(len, space));
   if (len > 0) {
     NoGCScope no_gc;
     memmove(CharAddr(result, 0), characters, len);
@@ skipping 1702 matching lines @@
   }
   return result.raw();
 }
 
 
 const char* WeakProperty::ToCString() const {
   return "_WeakProperty";
 }
 
 }  // namespace dart