Use ByteArray's native for Socket and File.

runtime/lib/byte_array.cc

Index: runtime/lib/byte_array.cc
===================================================================
--- runtime/lib/byte_array.cc	(revision 3621)
+++ runtime/lib/byte_array.cc	(working copy)
@@ -30,6 +30,36 @@
 }
 
 
+DEFINE_NATIVE_ENTRY(ByteArray_copyFromByteArray, 5) {
+  ByteArray& dst = ByteArray::CheckedHandle(arguments->At(0));
+  GET_NATIVE_ARGUMENT(ByteArray, src, arguments->At(1));
+  GET_NATIVE_ARGUMENT(Smi, src_start, arguments->At(2));
+  GET_NATIVE_ARGUMENT(Smi, dst_start, arguments->At(3));
+  GET_NATIVE_ARGUMENT(Smi, count, arguments->At(4));
+  intptr_t icount = count.Value();

[cshapiro, 2012/01/27 23:00:04]

I think the Value() calls are compiled away so you do not need to do the
subexpression elimination on your own.

[Anders Johnsen, 2012/01/27 23:42:39]

Done.

+  if (icount < 0) {
+    GrowableArray<const Object*> args;
+    Exceptions::ThrowByType(Exceptions::kIllegalArgument, args);
+  }
+  if (icount == 0) {
+    return;
+  }
+  intptr_t isrc_start = src_start.Value();
+  intptr_t idst_start = dst_start.Value();
+  if ((isrc_start < 0) || ((isrc_start + icount) > src.Length())) {
+    GrowableArray<const Object*> arguments;
+    arguments.Add(&src_start);
+    Exceptions::ThrowByType(Exceptions::kIndexOutOfRange, arguments);
+  }
+  if ((idst_start < 0) || ((idst_start + icount) > dst.Length())) {
+    GrowableArray<const Object*> arguments;
+    arguments.Add(&dst_start);
+    Exceptions::ThrowByType(Exceptions::kIndexOutOfRange, arguments);
+  }
+  ByteArray::Copy(dst, idst_start, src, isrc_start, icount);
+}
+
+
 static void RangeCheck(const ByteArray& array, const Smi& index,
                        intptr_t num_bytes) {
   if ((index.Value() < 0) || ((index.Value() + num_bytes) > array.Length())) {