Fix unaligned access to TypedData from native code.

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index 8138adba3c072b30673499a82b309e0e05b0caf1..8d3e64de6af5797346433b72203b56c31a03ecc9 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -7933,11 +7933,13 @@ class TypedData : public Instance {
 #define TYPED_GETTER_SETTER(name, type)                                        \
   type Get##name(intptr_t byte_offset) const {                                 \
     NoSafepointScope no_safepoint;                                             \
-    return *reinterpret_cast<type*>(DataAddr(byte_offset));                    \
+    type result;                                                               \
+    memmove(&result, DataAddr(byte_offset), sizeof(type));                     \

[zra, 2016/11/01 21:46:01]

Should we specialize this by architecture?

[Cutch, 2016/11/01 21:48:21]

+1 We should avoid calling memmove on architectures that don't need it.

+    return result;                                                             \
   }                                                                            \
   void Set##name(intptr_t byte_offset, type value) const {                     \
     NoSafepointScope no_safepoint;                                             \
-    *reinterpret_cast<type*>(DataAddr(byte_offset)) = value;                   \
+    memmove(DataAddr(byte_offset), &value, sizeof(type));                      \
   }
   TYPED_GETTER_SETTER(Int8, int8_t)
   TYPED_GETTER_SETTER(Uint8, uint8_t)