Speed up snapshots of *int8lists, by using memmove.

runtime/vm/dart_api_message.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/bigint_operations.h"
 #include "vm/dart_api_message.h"
 #include "vm/object.h"
 #include "vm/snapshot_ids.h"
 #include "vm/symbols.h"
 #include "vm/unicode.h"
@@ skipping 582 matching lines @@
       i = 0;
       while (i < len) {
         p += Utf8::Encode(Utf16::Next(utf16, &i, len), p);
       }
       *p = '\0';
       ASSERT(p == (object->value.as_string + utf8_len));
       ::free(utf16);
       return object;
     }
 
+#define READ_TYPED_DATA_HEADER(type)                                           \
+      intptr_t len = ReadSmiValue();                                           \
+      Dart_CObject* object =                                                   \
+          AllocateDartCObjectTypedData(Dart_TypedData_k##type, len);           \
+      AddBackRef(object_id, object, kIsDeserialized);                          \
+
+
 #define READ_TYPED_DATA(type, ctype)                                           \
     {                                                                          \
-      intptr_t len = ReadSmiValue();                                           \
-      Dart_CObject* object =                                                   \
-          AllocateDartCObjectTypedData(Dart_TypedData_k##type, len);     \
-      AddBackRef(object_id, object, kIsDeserialized);                          \
+      READ_TYPED_DATA_HEADER(type);                                            \
       if (len > 0) {                                                           \
         ctype* p =                                                             \
             reinterpret_cast<ctype*>(object->value.as_typed_data.values);      \
         for (intptr_t i = 0; i < len; i++) {                                   \
           p[i] = Read<ctype>();                                                \
         }                                                                      \
       }                                                                        \
       return object;                                                           \
     }                                                                          \
 
     case kTypedDataInt8ArrayCid:
-    case kExternalTypedDataInt8ArrayCid:
-      READ_TYPED_DATA(Int8, int8_t);
+    case kExternalTypedDataInt8ArrayCid: {
+      READ_TYPED_DATA_HEADER(Int8);
+      if (len > 0) {
+        uint8_t* p =
+            reinterpret_cast<uint8_t*>(object->value.as_typed_data.values);
+        ReadBytes(p, len);
+      }
+      return object;
+    }
 
     case kTypedDataUint8ArrayCid:
-    case kExternalTypedDataUint8ArrayCid:
-      READ_TYPED_DATA(Uint8, uint8_t);
+    case kExternalTypedDataUint8ArrayCid: {
+      READ_TYPED_DATA_HEADER(Uint8);
+      if (len > 0) {
+        uint8_t* p =
+            reinterpret_cast<uint8_t*>(object->value.as_typed_data.values);
+        ReadBytes(p, len);
+      }
+      return object;
+    }
 
     case kTypedDataUint8ClampedArrayCid:
     case kExternalTypedDataUint8ClampedArrayCid:
       READ_TYPED_DATA(Uint8Clamped, uint8_t);
 
     case kTypedDataInt16ArrayCid:
     case kExternalTypedDataInt16ArrayCid:
       READ_TYPED_DATA(Int16, int16_t);
 
     case kTypedDataUint16ArrayCid:
@@ skipping 537 matching lines @@
     if (!success) {
       UnmarkAllCObjects(object);
       return false;
     }
   }
   UnmarkAllCObjects(object);
   return true;
 }
 
 }  // namespace dart